JP2003162145A - Developing apparatus, process cartridge and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing apparatus which hardly causes deterioration of an electrically conductive covering layer on a developer carrier surface due to repetitive copying or endurance, which has high durability and by which stable image quality can be obtained. <P>SOLUTION: The developing apparatus has at least a developing vessel 7 for housing a developer 4d, a developer carrier 4a for carrying the developer housed in the developing vessel and transporting the developer in a developing region and a developer layer thickness regulating member 4c for regulating layer thickness of the developer carried on the developer carrier. The developer has a electrically conductive fine particle and a toner particle containing at least a binding resin and a colorant. Circularity (a) of the toner is below 0.970 and a resin covering layer formed on a base body on the developer carrier contains a positively charged material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer used in electrophotographic devices, electrostatic recording devices, magnetic recording devices and the like, an image forming method using the developer, and a process cartridge having the developer.

[0002]

Further, the present invention relates to a copying machine, a printer, a facsimile machine, a plotter, etc., which forms a toner image on an image carrier in advance and then transfers the toner image onto a recording medium such as a transfer material to form an image. The present invention relates to an image forming apparatus and a process cartridge that can be attached to and detached from these image forming apparatuses.

In recent years, in an image forming method by electrophotography, as a charging device for a charged body such as a latent image carrier,
Many contact charging devices have been proposed and put into practical use because they have advantages such as low ozone and low power compared to corona chargers.

The contact charging device is a conductive charging member (contact charging member / contact charger) of a roller type (charging roller), a fur brush type, a magnetic brush type, a blade type, etc. ) Is contacted and a predetermined voltage bias is applied to the contact charging member to charge the surface of the body to be charged to a predetermined polarity and potential.

The charging roller is made of a conductive or medium-resistive rubber material or foam, and there are also those obtained by laminating these rubber materials and foam to obtain desired characteristics.

The charging roller has elasticity in order to obtain a constant contact state with the member to be charged, but because of this, frictional resistance is large, and in many cases it is driven by the member to be charged or driven with a slight speed difference. It Therefore, even if the direct injection charging is attempted, the absolute charging ability is deteriorated, the contact is insufficient, the contact unevenness due to the roller shape, and the charging unevenness due to the adhered matter on the charged body are unavoidable.

FIG. 2 is a graph showing an example of charging efficiency of contact charging in electrophotography. The horizontal axis represents the bias applied to the contact charging member, and the vertical axis represents the charging potential of the charged body (hereinafter, referred to as a photoconductor) obtained at that time.

A charging characteristic in the case of roller charging is represented by A. That is, the surface potential of the photoconductor starts to rise after the applied voltage passes the discharge threshold of about -500V, and thereafter, the surface potential of the photoconductor linearly increases with a slope of 1 with respect to the applied voltage. This threshold voltage is defined as the charging start voltage V _th . Therefore, when charging to -500V, -1000V
For example, a DC voltage of V is applied, or in addition to a charging voltage of −500V DC, an AC voltage having a peak-to-peak voltage of 1200V is applied so that the photoconductor potential is charged to a charging potential so that a potential difference equal to or more than a discharge threshold value is always maintained. The method of converging to is common.

That is, in order to obtain the photosensitive member surface potential V _d required for electrophotography, it is necessary to apply a DC voltage higher than the required V _d + V _th to the charging roller. The method of applying only the DC voltage to the contact charging member in this way to perform charging is called "DC charging method".

However, in DC charging, the resistance value of the contact charging member fluctuates due to environmental fluctuations and the _Vth fluctuates when the film thickness changes due to abrasion of the photoconductor. Therefore, the potential of the photoconductor is desired. It was difficult to make the value of.

Further, when AC charging is performed for uniform charging, further ozone is generated, vibration noise (AC charging sound) between the contact charging member and the photoconductor due to the electric field of AC voltage, and discharge. Deterioration of the surface of the photoconductor due to the phenomenon becomes remarkable, which is a new problem.

For fur brush charging, a member (fur brush charger) having a conductive fiber brush portion is used as a contact charging member, and the conductive fiber brush portion is brought into contact with a photoconductor as a member to be charged. A predetermined charging bias is applied to the conductive fiber brush portion to charge the surface of the photoconductor to a predetermined polarity and potential.

As the fur brush charger, a fixed type and a roll type have been put into practical use. The fixed type is made by folding a medium resistance fiber into a base cloth and forming it into a pile and adhering it to the electrode. The roll type is formed by winding the pile around a core metal. A fiber density of about 100 fibers / mm ² can be obtained relatively easily, but the contact property is still insufficient for sufficiently uniform charging by direct injection charging.
In order to carry out sufficiently uniform charging by direct injection charging, it is necessary to give the fur brush charger a speed difference with respect to the photoconductor such that it is difficult in terms of mechanical structure, which is not realistic.

Charging characteristics of this fur brush charging when a DC voltage is applied are shown in FIG. 2B. Therefore, even in the case of the fur brush charging, in both the fixed type and the roll type, in many cases, a high charging bias is applied and charging is performed using a discharge phenomenon.

On the other hand, in the magnetic brush charging, a member (magnetic brush charger) having a magnetic brush portion formed into a brush shape by magnetically restraining conductive magnetic particles with a magnet roll or the like is used as a contact charging member. The magnetic brush portion is brought into contact with a photoconductor as a member to be charged and a predetermined charging bias is applied to charge the surface of the photoconductor to a predetermined polarity and potential. In the case of this magnetic brush charging, the direct injection charging mechanism is dominant as the charging mechanism.

By using conductive magnetic particles having a particle size of 5 to 50 μm as the magnetic brush portion and providing a sufficient speed difference from the photosensitive member, nearly uniform direct injection charging is possible.

Charging characteristics of the magnetic brush when a direct current is applied are represented by C in FIG. As shown in FIG. 2, it is possible to obtain a charging potential almost proportional to the applied bias.

However, the magnetic brush charging has the disadvantages that the device construction is complicated, and that the conductive magnetic particles forming the magnetic brush portion fall off and adhere to the photoconductor. As described above, there is a demand for a simple and stable uniform charging device having a direct injection charging mechanism that is substantially free of generation of discharge products such as ozone and can obtain uniform charging at a low applied voltage.

On the other hand, an image forming method that does not generate waste toner is desired from the viewpoint of resource saving, waste reduction, and effective use of toner. For example, the latent image is developed with toner to form a visible image, and after the toner image is transferred to a recording medium such as paper, the toner remaining on the latent image carrier without being transferred to the recording medium is cleaned by various methods. The so-called toner reuse, in which the toner is circulated in the developing device and reused, has been put into practical use. However, there is a problem that the latent image carrier is worn and shortened due to the cleaning member being pressed against the surface of the latent image carrier. Further, from the aspect of the apparatus, the image forming apparatus inevitably becomes large in size due to the provision of the toner reuse apparatus and the cleaning apparatus, which becomes a bottleneck when aiming at downsizing of the apparatus.

On the other hand, as a system without waste toner, a technique called development / cleaning or cleanerless has been proposed. As disclosed in Japanese Patent Application Laid-Open No. 5-2287, the prior art relating to development / cleaning or cleanerless is mainly focused on a positive memory, a negative memory or the like due to the influence of transfer residual toner on an image. It was However, with the increasing use of electrophotography, it has become necessary to transfer a toner image to various recording media, and in this sense, it is not satisfactory for various recording media.

Japanese Patent Laid-Open Nos. Hei 2-302772 and Hei 5 have disclosed the technology related to cleanerless.
Although there are JP-A-2289, JP-A-5-53482, JP-A-5-61383, etc., a desirable image forming method is not mentioned, and a toner constitution is not mentioned.

As a developing method which essentially does not have a cleaning device and is preferably applied to cleaning / development or cleanerless, it has been indispensable to rub the surface of the latent image carrier with toner and the toner carrier. A lot of studies have been conducted on the contact developing method in which the toner or the developer comes into contact with the latent image carrier. This is because it is considered advantageous that the toner or the developer comes into contact with the latent image carrier and rubs in order to collect the transfer residual toner particles in the developing unit. However, in the development / cleaning or cleanerless process to which the contact development method is applied, toner deterioration, toner carrier surface deterioration, photoconductor surface deterioration, wear, etc. are caused by long-term use, and a sufficient solution to durability characteristics is not achieved. Not done. Therefore, a development / cleaning method based on a non-contact development method has been desired.

In the developing / cleaning method and the cleanerless image forming method, the charge polarity and charge amount of the transfer residual toner particles on the photoconductor are controlled, and the transfer residual toner particles are stably recovered in the developing process to recover the recovered toner. The key is to prevent the development characteristics from deteriorating. Therefore, the charging member controls the charging polarity and the charging amount of the transfer residual toner particles. This will be specifically described by taking a general laser printer as an example.

In the case of reversal development using a charging member applying a negative polarity voltage, a negative charging photosensitive member and a negative charging toner, an image visualized by the transfer member applying a positive polarity voltage in the transfer step. However, due to the relationship between the type of recording medium (difference in thickness, resistance, permittivity, etc.) and the image area, the charge polarity of the transfer residual toner changes, and a positive charge is applied. From those having a negative charge to those having a negative charge. However, even if the transfer residual toner is swung to the positive polarity in the transfer process, when the photoconductor is charged by the negative polarity charging member, the charge polarity of the transfer residual toner is uniformly moved to the negative side together with the photoconductor surface. Can be arranged. Therefore, when reversal development is used as the developing method, the transfer residual toner negatively charged remains in the light portion potential portion of the toner to be developed, while the toner remains in the dark portion potential of the toner that should not be developed. Due to the developing electric field, the toner is attracted toward the toner carrier, and the transfer residual toner particles are collected without remaining on the photoconductor having the dark portion potential. That is, the developing / cleaning and cleanerless image forming method is established by controlling the charging polarity of the transfer residual toner at the same time as the charging of the photoconductor by the charging member.

However, if the transfer residual toner particles exceed the ability of the contact charging member to control the toner charging polarity and adhere to or mix with the contact charging member, the transfer residual toner particles cannot be evenly charged. It becomes difficult to collect the toner in the developing process. Even if the transfer residual toner particles are collected on the toner carrier by a mechanical force such as rubbing, if the transfer residual toner particles are not uniformly charged, the triboelectric chargeability of the toner on the toner carrier is increased. And adversely affect development characteristics. That is, in the development / cleaning and cleanerless image forming methods, the charge control characteristics of the transfer residual toner particles when passing through the charging member and the adhesion / mixing characteristics to the charging member are closely linked to the durability characteristics and the image quality characteristics. .

In the developing / cleaning image forming method, as a method for improving the developing / cleaning performance by improving the charge control characteristic of transfer residual toner particles when passing through the charging member, Japanese Patent Laid-Open No. 11-15206 discloses a specific method. An image forming method using a toner having toner particles containing carbon black and a specific azo iron compound and an inorganic fine powder has been proposed. Further, in the developing / cleaning image forming method, it has been proposed to improve the developing / cleaning performance by reducing the amount of transfer residual toner particles with a toner having a transfer efficiency that defines the shape factor of the toner. However, the contact charging used here is also due to the discharge charging mechanism, not the direct injection charging mechanism, and therefore there is the above-mentioned problem due to discharge charging. Further, although these proposals have the effect of suppressing the deterioration of the charging property due to the transfer residual toner particles of the contact charging member, the effect of positively enhancing the charging property cannot be expected.

Further, in a commercially available electrophotographic printer, a roller member that abuts on the photosensitive member is used between the transfer step and the charging step to assist or control the recovery property of the transfer residual toner particles during development. There is also a cleaning image forming apparatus.
Such an image forming apparatus exhibits a good developing / cleaning property and can greatly reduce the amount of waste toner.
The cost is high, and the advantages of developing and cleaning are lost in terms of downsizing.

Japanese Patent Publication No. 7-99442 discloses a structure in which powder is applied to the contact surface of the contact charging member with the surface to be charged in order to prevent uneven charging and to perform stable uniform charging. However, the contact charging member (charging roller) is driven by the charged body (photoreceptor) to rotate (no speed difference drive), and the generation of ozone products is much less than that of a corona charger such as a scorotron. However, as in the case of the roller charging described above, the charging principle still mainly uses the discharge charging mechanism. In particular, in order to obtain more stable charging uniformity, a voltage in which an AC voltage is superimposed on a DC voltage is applied, so that the ozone products are more likely to be generated by the discharge. Therefore, when the device is used for a long period of time, adverse effects such as image deletion due to ozone products are likely to appear. Further, when the above configuration is applied to a cleanerless image forming apparatus, it becomes difficult that the applied powder is uniformly attached to the charging member due to the mixture of the transfer residual toner particles, and the effect of uniform charging is obtained. It fades.

Further, in Japanese Patent Application Laid-Open No. 5-150539, in an image forming method using contact charging, toner particles and silica fine particles which cannot be completely cleaned by blade cleaning during repeated image formation for a long time are formed on the surface of the charging means. In order to prevent charging inhibition due to adhesion and accumulation, it is disclosed that the developer contains at least developer particles and conductive particles having an average particle size smaller than that of the developer particles. However, the contact charging or the proximity charging used here is due to the discharge charging mechanism and not the direct injection charging mechanism, so that there is the above-mentioned problem due to the discharge charging. Furthermore, when this configuration is applied to a cleanerless image forming apparatus, compared with the case where a cleaning mechanism is provided,
Effects of a large amount of conductive fine particles and transfer residual toner particles on the charging property due to passing through the charging step, recoverability of these large amounts of conductive fine particles and transfer residual toner particles in the developing step, recovered conductive fine particles and transfer No consideration is given to the influence of the residual toner particles on the developing characteristics of the developer. Further, when the direct injection charging mechanism is applied to the contact charging, the conductive fine particles are not supplied to the contact charging member in the required amount, and the charging failure occurs due to the influence of the transfer residual toner particles.

In proximity charging, it is difficult to uniformly charge the photoconductor with a large amount of conductive fine particles and transfer residual toner particles, and the effect of leveling the pattern of transfer residual toner particles cannot be obtained. Toner particles block the pattern image exposure and produce pattern ghosts. Further, when the power source is momentarily cut off during image formation or paper is jammed, the inside of the machine is contaminated by the developer.

In contrast to these, Japanese Unexamined Patent Publication No. 10-307456
Japanese Patent Application Laid-Open Publication No. JP-A-2003-264242, wherein an image is formed by applying a developer containing toner particles and electrically conductive charge-accelerating particles having a particle diameter of ½ or less of the toner particle diameter to a developing and cleaning image forming method using a direct injection charging mechanism. A device is disclosed.
According to this proposal, it is possible to obtain a developing / cleaning image forming apparatus that can reduce the amount of waste toner significantly without generating discharge products and is advantageous in downsizing at a low cost. Alternatively, a good image that does not cause diffusion can be obtained. However, further improvements are desired.

Further, in Japanese Patent Application Laid-Open No. 10-307421, a developing / cleaning image using a direct injection charging mechanism with a developer containing conductive particles having a particle diameter of 1/50 to 1/2 of the toner particle diameter is used. There is disclosed an image forming apparatus which is applied to a forming method and has conductive particles having a transfer promoting effect.

Further, in Japanese Patent Application Laid-Open No. 10-307455, the particle size of the conductive fine powder is set to be equal to or smaller than the size of one pixel of the constituent pixels, and in order to obtain better charging uniformity, the conductive fine powder is It is described that the particle size is 10 nm to 50 μm.

In Japanese Unexamined Patent Publication No. 10-307457, the conductive particles are set to about 5 in order to make it difficult to visually recognize the influence of the defective charging portion on the image in consideration of human visual characteristics.
It is described that the thickness is not more than μm, preferably 20 nm to 5 μm.

Further, according to Japanese Unexamined Patent Publication No. 10-307458, the particle size of the conductive fine powder is set to be equal to or smaller than the toner particle size, so that the development of the toner is hindered at the time of development and the developing bias causes the conductive fine powder. It is described that it is possible to prevent the leakage of the image through the film and eliminate the defect of the image.
At the same time, by setting the particle size of the conductive fine powder to be larger than 0.1 μm, the conductive fine powder is embedded in the image carrier and the adverse effect of blocking the exposure light is also solved and excellent image recording is directly realized. A developing / cleaning image forming method using an injection charging mechanism is described. However, further improvements are desired.

According to Japanese Unexamined Patent Publication No. 10-307456, conductive fine powder is externally added to the toner, and at least the contact portion between the flexible contact charging member and the image carrier has the conductivity contained in the toner. The fine powder adheres to the image carrier in the developing process and remains on the image carrier even after the transferring process, and is carried and intervened. The resulting development-cleaning image forming apparatus is disclosed. However, these proposals also have room for further improvement in stable performance in repeated use over a long period of time and in the case of using toner particles having a smaller particle diameter in order to enhance resolution.

It has also been proposed to externally add conductive particles having an average particle size. For example, Japanese Patent Laid-Open No. 9-
In Japanese Patent No. 146293, the average particle diameter is 5 to 50 n.
m of fine powder A and fine powder B having an average particle size of 0.1 to 3 μm
As an external additive, a toner has been proposed in which toner particles are strongly adhered to the toner mother particles having a particle size of 4 to 12 μm or more, but the ratio of the fine powder B released and the toner particles separated from the toner mother particles is determined. The purpose is to reduce. Further, in JP-A-11-95479,
Although a toner containing conductive silica particles having a defined particle size and a hydrophobicized inorganic oxide has been proposed, the purpose is to leak the electric charges accumulated in the toner to the outside by the conductive silica particles. It's only what you did.

Further, Japanese Patent Application Laid-Open No. 11-194530 proposes a toner having an external additive fine particle A and an inorganic fine powder B having a particle size of 0.6 to 4 μm and having a regulated particle size distribution. Inorganic fine powder B due to the inclusion of the additive fine particles A
The purpose is to prevent the toner from being deteriorated by being embedded in the toner mother particles and the like, and no consideration is given to the adhesion and release of the external additive fine particles A to the toner mother particles. In addition, JP-A-10
In Japanese Patent Laid-Open No. 83096, there is proposed a toner in which conductive fine particles and silica fine particles are added to the surface of spherical resin fine particles containing a colorant. Transfer of charge between particles
The purpose is to speed up the exchange and improve the uniformity of triboelectrification of the toner.

As described above, as the developer for use in the image forming method having the injection charging step, the image forming method having the developing / cleaning step or the cleanerless image forming method, sufficient consideration has been given to external additives. Not
None of the proposals of developers including external additives have been sufficiently studied so as to be applicable to an image forming method having an injection charging step, a developing / cleaning image forming method or a cleanerless image forming method.

By the way, image forming apparatuses are increasingly required to have higher speed and lower cost. For example, in a laser printer that uses a widely used electrophotographic method, the printing speed of an introductory model for individuals called a low end is 6 to 8 sheets per minute, but it is as high as 10 to 15 sheets per minute. And the price is becoming lower. When the printing speed is converted into the moving speed (process speed) of the image carrier, it is about 50 mm / sec to 10 mm.
The speed has been increased to near 0 mm / sec, and it is considered that the speed will be further increased in the future.

As the process speed increases, generally, the collectability of the transfer residual toner particles in the development / cleaning tends to decrease. As the process speed becomes faster, it is difficult to sufficiently control the charge of the transfer residual toner particles in the primary charging, and the charge of the transfer residual toner particles discharged from the primary charging to the recovery in the development tends to become uneven. It is considered that the reason is that it is difficult to suppress the influence on the triboelectrification property of the developer due to the mixture of the transfer residual toner particles collected by the development.
This tendency is particularly remarkable in the non-contact development method. This is because in the recovery of the transfer residual toner particles in the contact developing method, the electrostatic force works more effectively due to the contact between the developer carrier and the image carrier, and the physical force due to the rubbing works. It is presumed that this is because it is easy to compensate for the decrease in the collectability of transfer residual toner particles due to the increase in speed.

The chargeability of direct injection charging also tends to decrease as the process speed increases. It is presumed that this is because the probability of contact between the image carrier and the contact charging member via the conductive fine powder is reduced, or the charging time for injecting charges to charge the image carrier is shortened. Further, in order to maintain the contact probability, if the moving speed ratio of the charging member to the moving speed of the image carrier is maintained or increased together with the increase of the process speed, a large increase in torque causes a cost increase, Problems such as scratches on the image bearing member and the charging member and contamination inside the apparatus due to scattering of transfer residual toner particles attached to or mixed with the charging member are likely to occur. Therefore,
A developer capable of controlling the moving speed of the charging member to a low value at a higher process speed to prevent defective pattern collection and image smearing, and to sufficiently reduce the deterioration of the chargeability of the image carrier after repeated use. And an image forming method is required.

[0043]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and to provide a developing device, a process cartridge and an image forming method capable of forming a toner image by a good developing and cleaning process. To provide.

It is another object of the present invention to enable simple and stable uniform charging by a direct injection charging mechanism which is substantially free of generation of discharge products such as ozone and which can be uniformly charged at a low applied voltage. To provide a developing device, a process cartridge and an image forming method.

Further, an object of the present invention is to provide a developing device, a process cartridge and an image forming method capable of significantly reducing the amount of waste toner and enabling a developing / cleaning step which is low cost and advantageous for downsizing. To do.

Further, an object of the present invention is to provide an image forming method and a process cartridge having a developing / cleaning step capable of stably obtaining a good image even when toner particles having a small particle size are used for enhancing resolution. To provide.

It is another object of the present invention that the conductive coating layer on the surface of the developer carrier does not easily deteriorate due to repeated copying or durability, has high durability, and has stable image quality. And an image forming method.

The object of the present invention is that, even under different environmental conditions, problems such as density decrease, sleeve ghost, and fog do not occur for a long period of time, the sharpness of character lines is good, and the image density is high. A developing device, a process cartridge, and an image forming method capable of stably obtaining a high-quality image.

The object of the present invention is to control the uneven charging of the toner on the surface of the developer carrying member, which appears when a toner having a small particle size is used, and to give the toner quick and appropriate charging. A developer carrier, a developing device having the developer carrier, a process cartridge, and an image forming method are provided.

[0050]

The above object can be achieved by the following constitution of the present invention.

That is, the developing device of the present invention includes a developing container for accommodating the developer, a developer carrying member for carrying the developer contained in the developing container and transporting the developer to the developing area. A developing device having at least a developer layer thickness regulating member for regulating the layer thickness of the developer carried on the developer carrying body, wherein the developer contains at least a binder resin and a colorant. The toner particles have conductive particles, and the toner particles have a circularity a of less than 0.970 determined by the following formula. The developer carrying member is at least a substrate and a resin coating formed on the substrate. The resin coating layer contains at least a binder resin for the coating layer and a positively chargeable substance.

[0052]

[Equation 4] (In the formula, L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the projected image of the particle.) Resin formed on the substrate of the developer carrying member The coating layer preferably contains at least a binder resin for the coating layer and a conductive substance.

The resin coating layer formed on the substrate of the developer carrying member preferably contains at least a binder resin for the coating layer and a lubricating substance.

In the above developing apparatus, it is preferable that the resin coating layer formed on the substrate of the developer carrier has a nitrogen-containing heterocyclic compound as a positively chargeable substance.

The nitrogen-containing heterocyclic compound is preferably an imidazole compound.

Further, the imidazole compound is preferably a compound represented by the following formula (1) or (2).

[0057]

[Chemical 4] [In the formula, R ₁ and R ₂ represent a hydrogen atom or a substituent selected from the group consisting of an alkyl group, an aralkyl group and an aryl group, and R ₁ and R ₂ may be the same or different. Well, R ₃ and R ₄ represent a linear alkyl group having 3 to 30 carbon atoms, and R ₃ and R ₄ may be the same or different. ]

[0058]

[Chemical 5] [In the formula, R ₅ and R ₆ represent a hydrogen atom or a substituent selected from the group consisting of an alkyl group, an aralkyl group and an aryl group, and R ₅ and R ₆ may be the same, and R ₇ Represents a linear alkyl group having 3 to 30 carbon atoms. It is preferable that the resin coating layer further has spherical particles having a number average particle diameter of 0.3 to 30 μm in addition to the conductive substance and the nitrogen-containing heterocyclic compound.

The spherical particles are preferably resin particles.

The spherical particles are preferably conductive spherical particles having a true density of 3 g / cm ³ or less.

Further, in the above developing apparatus, a copolymer containing a unit derived from a nitrogen-containing vinyl monomer as a positively chargeable substance is contained in the resin coating layer formed on the substrate of the developer carrier. It is preferable to contain.

The nitrogen-containing vinyl monomer preferably contains a vinyl polymerizable monomer.

The copolymer is 3,000 to 50,000.
It is preferable to have a weight average molecular weight (Mw) of.

The copolymer preferably has a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw / Mn) of 3.5 or less.

The nitrogen-containing vinyl monomer is a (meth) acrylic acid derivative having a nitrogen-containing group and a nitrogen-containing heterocyclic N group.
-It is preferred to have one or more monomers selected from the group consisting of vinyl compounds.

The nitrogen-containing vinyl monomer is represented by the following general formula (3)

[0067]

[Chemical 6] [In the formula, R ₇ , R ₈ , R ₉ and R ₁₀ represent a hydrogen atom or a saturated hydrocarbon group having 1 to 4 carbon atoms, and n is 1 to 4
Indicates an integer. ] What is shown by these is preferable.

Further, in the above-mentioned developing device, in the resin coating layer formed on the substrate of the developer carrying member, a binder resin, a vinyl polymerizable monomer and a sulfonic acid group are used as positively chargeable substances. It is preferable to contain a copolymer with the contained acrylamide monomer. At the same time, it is preferable that a part or all of the binder resin for the coating layer has at least one of —NH ₂ group, ═NH group, or —NH— bond in its molecular structure.

The copolymerization ratio (mass%) of the vinyl polymerizable monomer and the acrylamide group-containing sulfonic acid group monomer is 9
It is preferably 8: 2 to 80:20 and a copolymer having a weight average molecular weight (Mw) of 2,000 to 50,000.

The above-mentioned copolymer comprises a vinyl-polymerizable monomer and 2
-It is preferably a copolymer with acrylamido-2-methylpropanesulfonic acid.

It is preferable that at least a phenol resin is contained in the binder resin.

It is preferable that the phenol resin is a phenol resin produced by using a nitrogen-containing compound as a catalyst, and has in its structure either --NH ₂ group, ═NH group or --NH-- bond.

At least a polyamide resin is preferably contained in the binder resin.

At least a polyurethane resin is preferably contained in the binder resin.

In order to form irregularities on the surface of the coating layer in the resin layer, spherical particles are preferably contained,
The number average particle diameter of the spherical particles is more preferably 0.3 to 30 μm.

It is preferable that the particles for forming irregularities on the surface of the coating layer are spherical and that the true density is 3 g / cm ³ or less.

The particles for forming irregularities on the surface of the coating layer are preferably conductive spherical particles.

Further, it is preferable that the developer layer thickness regulating member included in the developing device of the present invention is a magnetic blade or an elastic blade.

The developer is preferably a magnetic developer containing magnetic toner particles.

The weight average particle diameter (D4) of the developer is 4
It is preferably 10 μm.

The developer has a particle size of 0.60 to 159.21.
In the number-based particle size distribution of the μm particles, 1.
15 particles in the particle size range from 00 μm to less than 2.00 μm
-60% by number and 3.00 μm or more and 8.96 μm
It is preferable to contain 15 to 70% by number of particles having a particle size range of less than m.

The developer has a volume average particle size of 0.1 to 1
It is preferable that the conductive fine particles have a size of 0 μm.

[0083] The developer has a volume resistivity of ¹⁰ 0 - 10
^It is preferable that the conductive fine particles have a resistance of ⁹ Ω · cm, more preferably 10 ¹ to 10 ⁶ Ω · cm.

It is preferable that the conductive fine particles are non-magnetic.

It is preferable that the conductive fine particles contain at least one oxide selected from zinc oxide, tin oxide and titanium oxide.

In the process cartridge of the present invention, the electrostatic latent image formed on the latent image carrier is visualized as a developer image by a developer, and the visualized developer image is transferred to a transfer material to form an image. It is a process cartridge for forming.

The process cartridge of the present invention is formed on the latent image bearing member for bearing the electrostatic latent image, the charging means for charging the latent image bearing member, and the latent image bearing member. At least a developing device for forming a developer image by developing an electrostatic latent image with a developer, wherein the developing device and the latent image carrier are integrated to form an image forming apparatus main body. On the other hand, the developer is detachably attached, and the developer has toner particles containing at least a binder resin and a colorant and conductive fine particles, and the toner particles have a circular shape obtained by the following formula. Degree a is 0.970
The developing device is a developing container for accommodating a developer, a developer carrier for carrying the developer contained in the developing container and transporting the developer to a developing area, and the developer. The developer carrier has at least a developer layer thickness regulating member for regulating the layer thickness of the developer carried on the carrier, and the developer carrier has at least a substrate and a resin coating layer formed on the substrate. And the resin coating layer contains at least a binder resin for the coating layer and a positively chargeable substance.

[0088]

[Equation 5] (In the formula, L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the projected image of the particle.) In the process cartridge of the present invention, the developing device is The electrostatic latent image formed on the latent image carrier is visualized as a developer image by developing with a developer, and after the developer image is transferred to a transfer material as a recording medium, The developer remaining on the latent image carrier is recovered.

It is preferable that the charging means is a charging member that contacts the latent image carrier and charges the latent image carrier by applying a voltage to the contact part.

Charging the latent image carrier by applying a voltage to at least the contact portion between the charging means and the latent image carrier with the conductive fine particles of the developer interposed. Is preferred.

In the above process cartridge, the above-mentioned developing device of the present invention can be preferably used.

The image forming method of the present invention comprises a charging step for charging the latent image carrier and a latent image formation for writing image information as an electrostatic latent image on the charged surface of the latent image carrier charged in the charging step. Process, and the electrostatic latent image is developed using a developing device equipped with a developer carrying member that carries the developer to a developing area facing the latent image carrying member while carrying the developer. And a fixing step of fixing the developer image transferred onto the transfer material by a fixing means. Each of these steps is performed. An image forming method in which an image is repeatedly formed, wherein the developer has conductive particles and toner particles containing at least a binder resin and a colorant, and the toner particles have a circularity determined by the following formula. a is less than 0.970 The developing device includes a developing container for accommodating a developer, a developer carrying member for carrying the developer contained in the developing container and transporting the developer to a developing area, and the developer carrying member. It has at least a developer layer thickness regulating member for regulating the layer thickness of the developer carried thereon, and the developer carrying body comprises at least a substrate and a resin coating layer formed on the substrate. The resin coating layer contains at least a binder resin for the coating layer and a positively chargeable substance.

[0093]

[Equation 6] (In the formula, L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the projected image of the particle.) In the image forming method of the present invention, the developing step includes It is a step of visualizing the electrostatic latent image and collecting the developer remaining on the latent image carrier after the developer image is transferred to the transfer material.

In the charging step, it is preferable to charge the latent image carrier by bringing a charging means into contact with the latent image carrier and applying a voltage to the contact portion.

In the charging step, a voltage is applied to at least a contact portion between the charging means and the latent image carrier with the conductive fine particles contained in the developer interposed therebetween.
It is preferable to charge the latent image carrier.

In the image forming method, the developing device of the present invention described above can be preferably used.

[0097]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

<Developer> The developer used in the present invention is preferably a one-component developer containing at least toner particles and conductive fine powder.

The developer used in the present invention has at least toner particles containing at least a binder resin and a colorant and conductive fine powder, and has a particle size of 0.60 μm or more and 159.2.
In the number-based particle size distribution in the particle size range of less than 1 μm,
It contains 15 to 60% by number of particles in the particle size range of 1.00 μm or more and less than 2.00 μm, and 3.00 μm or more and 8.9.
It is preferable to contain 15 to 70% by number of particles having a particle size range of less than 6 μm. Furthermore, it is preferable to contain an inorganic fine powder having an average primary particle diameter of 4 to 80 nm as an external additive.

By using such a developer, good chargeability can be stably imparted to the developer, and good images can be obtained without causing charging failure even when the developer is repeatedly used for a long time. In addition, it is possible to provide an image forming method having a developing / cleaning step which is advantageous in downsizing at low cost, and which can significantly reduce the amount of waste toner.

Further, by using such a developer, there is substantially no discharge product such as ozone, and the charging using a direct injection charging mechanism which can obtain uniform charging at a low applied voltage is simple. An image forming method which can be favorably performed and which can obtain a good image without causing charging failure even when the developer is repeatedly used for a long period of time becomes possible. Further, by using such a developer, even if a large amount of the developer component adheres to or mixes with the contact charging member, it is possible to suppress the deterioration of the uniform charging property, and it is possible to suppress the image due to the charging failure of the image carrier. An image forming method by contact charging, which can suppress defects, becomes possible.

Further, in the developing / cleaning image forming method using such a developer, a developer stably exhibiting good triboelectrification characteristics can be obtained, and even after repeated use of the developer for a long time, transfer residual toner A good image can be obtained without defective collection of particles or image defects due to uniform charging or obstruction of latent image formation, and the amount of waste toner can be greatly reduced, which is advantageous for downsizing at low cost. A development / cleaning image forming method becomes possible.

When the electrostatic latent image formed on the image carrier is developed, an appropriate amount of the conductive fine powder contained in the developer moves together with the toner particles from the developer carrier to the latent image carrier. The toner image formed on the latent image carrier by developing the electrostatic latent image is transferred to a transfer material such as paper in a transfer process. At this time, a part of the conductive fine powder on the latent image carrier also adheres to the transfer material, but the rest remains adhered and held on the latent image carrier. When transfer is performed by applying a transfer bias having a polarity opposite to the charging polarity of the toner particles, the toner is attracted to the transfer material side and actively transfers, but the conductive fine powder on the latent image carrier is conductive. It is difficult to transfer to the transfer material side because of its nature. Therefore, a part of the conductive fine powder adheres to the transfer material, but the rest remains adhered and held on the latent image carrier.

In the image forming method which does not have the step of removing the conductive fine powder that is adhered and retained on the latent image carrier from the latent image carrier like the cleaning step, the latent image carrier after the transfer step is used. The toner particles remaining on the surface (hereinafter referred to as "transfer residual toner particles") and the conductive fine powder move on the surface carrying an image on the latent image carrier (hereinafter referred to as "image carrying surface"). Along with that, it is carried to the charging section. That is, when the contact charging member is used in the charging step, the conductive fine powder is carried to the contact portion formed by contact between the latent image carrier and the contact charging member, and adheres to the contact charging member.
mixing. Therefore, the contact charging of the latent image carrier is performed with the conductive fine powder interposed in the contact portion between the latent image carrier and the contact charging member.

In the present invention, the conductive fine powder is positively conveyed to the charging portion to prevent the transfer residual toner particles from adhering and
Even though the contact charging member is contaminated by the mixture, the contact resistance of the contact charging member can be maintained, so that the latent image carrier can be favorably charged by the contact charging member.

However, when a sufficient amount of the conductive fine powder is not present in the charging portion of the contact charging member, it is easy to reduce the charge of the image carrier due to the adhesion and mixing of the transfer residual toner particles on the contact charging member. And stains the image.

Further, by positively carrying the conductive fine powder to the contact portion formed by the contact between the latent image carrier and the contact charging member, the contact charging member can be closely contacted with the latent image carrier. Since the contact resistance can be maintained, the direct charging of the latent image carrier by the contact charging member can be favorably performed.

Further, the transfer residual toner particles adhering to and mixed with the contact charging member are gradually discharged from the contact charging member onto the latent image carrier, and reach the developing section as the image carrying surface moves.
In the developing step, cleaning / development is performed, that is, the transfer residual toner particles are collected. Similarly, the conductive fine powder adhering to and mixed with the contact charging member is also gradually discharged from the contact charging member onto the image bearing member, and reaches the developing unit as the image bearing surface moves. That is, the conductive fine powder is present on the latent image carrier together with the transfer residual toner particles, and the transfer residual toner particles are collected in the developing step. When the transfer residual toner particles are collected by the developing bias electric field in the developing step, the transfer residual toner particles are collected by the developing bias electric field, while the conductive fine powder on the latent image carrier is used. Is conductive and is difficult to recover. Therefore, although a part of the conductive fine powder is collected, the rest remains attached and held on the latent image carrier. According to the study of the present inventors, the presence of the conductive fine powder that is difficult to be collected in the developing step on the image carrier thus improves the collectability of the transfer residual toner particles on the latent image carrier. It turned out to have an effect. That is, the conductive fine powder on the image bearing member acts as a recovery aid for the transfer residual toner particles on the latent image bearing member to make the recovery of the transfer residual toner particles in the developing process more reliable, and It is possible to effectively prevent image defects such as positive ghost and fog due to poor collection.

Conventionally, most of the purpose of externally adding the conductive fine powder to the developer is to control the triboelectric chargeability of the toner by adhering the conductive fine powder to the surface of the toner particle, and to separate the toner from the toner particle. Alternatively, the conductive fine powder that is released has been treated as an adverse effect that causes a change or deterioration of the developer characteristics. On the other hand, the developer of the present invention is different from the external addition of the conductive fine powder to the developer, which has been widely studied in the past, in that the conductive fine powder is positively released from the surface of the toner particles. The conductive fine powder is carried through the latent image bearing member after transfer to a charging portion which is a contact portion formed by the contact between the image bearing member and the contact charging member, and the conductive fine powder is intervened to interpose the latent image bearing member. By positively improving the charging property, stable and uniform charging is possible, and the occurrence of an image defect due to a decrease in the charge of the latent image carrier is prevented. In addition, since the conductive fine powder is present on the latent image carrier in the developing step, the conductive fine powder acts as a recovery aid for the transfer residual toner particles on the latent image carrier, and the transfer residual toner particles in the developing step. Can be more reliably recovered, and image defects such as positive ghost and fog due to poor recovery of transfer residual toner particles can be effectively prevented.

In the developer of the present invention, the conductive fine powder that adheres to the surface of the toner particles and behaves together with the toner particles promotes the chargeability of the latent image carrier and the development which the developer of the present invention effectively exerts. The contribution to the improvement of the cleaning performance is small, the developing property of the toner particles is lowered, the recovery property of the transfer residual toner particles in the developing and cleaning process is lowered,
Also, since the amount of toner particles remaining after transfer increases due to a decrease in transferability, there are cases in which there are adverse effects such as inhibiting uniform charging.

The conductive fine powder contained in the developer of the present invention is transferred to the image bearing surface through the charging step and the developing step due to the repeated image formation, and further, the transfer step is accompanied with the movement of the image bearing surface. The conductive fine powder is continuously supplied to the charging section by being carried again to the charging section through the above. Therefore, even if the conductive fine powder is reduced in the charging unit due to falling off or the uniform charging promoting ability of the conductive fine powder is deteriorated, the conductive fine powder is continuously supplied to the charging unit. Even when it is repeatedly used over a long period of time, the chargeability of the image bearing member is prevented from lowering, and good uniform charging is stably maintained.

Of the particle size of the conductive fine powder added to the developer,
According to the study of the present inventors regarding the effect of accelerating the charging property of the latent image carrier and the effect of developing and cleaning, the conductive fine powder having a very small particle size (for example, about 0.1 μm or less) is used. ) Easily adheres firmly to the surface of the toner particles, the conductive fine powder cannot be sufficiently supplied to the non-image area on the latent image carrier in the developing step, and the conductive particles from the surface of the toner particles are also conductive in the transfer step. No fine powder is released. Therefore, the conductive fine powder cannot be positively left on the latent image carrier after the transfer, and the conductive fine powder cannot be positively supplied to the charging portion. Therefore, the effect of improving the chargeability of the latent image carrier cannot be obtained, and when the transfer residual toner particles adhere to the contact charging member and mix, an image defect occurs due to the decrease in the chargeability of the latent image carrier.

Further, even in the developing / cleaning step, since the conductive fine powder cannot be supplied onto the latent image carrier, the particle size of the conductive fine powder even if supplied onto the latent image carrier is large. Is too small, the effect of improving the recoverability of the transfer residual toner particles cannot be obtained, and image defects such as positive ghost and fog due to poor recovery of the transfer residual toner particles cannot be effectively prevented.

Further, among the conductive fine powders, those having a too large particle size (for example, particles having a size of about 4 μm or more) have a large particle size even when supplied to the charging section, so that the conductive fine powder falls off from the charging member. It becomes difficult to keep the conductive fine powder having a sufficient number of particles stably interposed in the charging portion, and it is impossible to promote uniform charging property of the latent image carrier. Further, since the number of particles of the conductive fine powder per unit weight is reduced, the conductive fine powder having the number of particles sufficient to obtain the effect of promoting uniform charging of the latent image carrier is interposed in the charging section (charging section). By increasing the number of contact points between the latent image carrier and the conductive fine powder in, the effect of promoting uniform chargeability of the latent image carrier is enhanced. However, it is necessary to increase the amount of the conductive fine powder added to the developer. However, if the amount of the conductive fine powder added is too large, the triboelectric charging ability and the developability of the developer as a whole are lowered, and the image density is lowered and the toner is scattered. Further, since the conductive fine powder has a large particle size, the effect as a recovery aid for the transfer residual toner particles in the developing step cannot be sufficiently obtained. To increase the recovery of transfer residual toner particles, if the amount of conductive fine powder present on the image bearing member is too large, the particle size is large, which adversely affects the latent image forming process, such as blocking image exposure. May cause image defects.

The inventors of the present invention proceeded with an earnest study by studying the particle size of the conductive fine powder and further studying the particle size distribution of the developer containing an external additive, which is directly involved in the actual behavior of the developer. Finally, the present invention was achieved.

That is, the developer contains at least toner particles containing at least a binder resin and a colorant, an inorganic fine powder having a number average particle diameter of primary particles of 4 to 80 nm, and a conductive fine powder. , 0.60 μm or more 159.2
In the number-based particle size distribution in the particle size range of less than 1 μm,
It contains 15 to 60% by number of particles in the particle size range of 1.00 μm or more and less than 2.00 μm, and 3.00 μm or more and 8.9.
By including 15 to 70% by number of particles having a particle size range of less than 6 μm, charging failure of the latent image carrier due to contact charging can be effectively prevented, and the latent image carrying by the direct injection charging mechanism can be carried out. The uniform charging property of the body can be improved.
Further, it is possible to enhance the recovery of the transfer residual toner particles in the development / cleaning and effectively prevent image defects such as positive ghost and fog due to poor recovery of the transfer residual toner particles.

More specifically, the inorganic fine powder having a number average particle size of the primary particles of 4 to 80 nm contained in the developer of the present invention adheres to the surface of the toner particles and behaves together with the toner particles, thereby developing. It improves the fluidity of the agent and makes the triboelectric charging characteristics of the toner particles uniform. Therefore, the transferability of the toner particles is improved, the amount of the transfer residual toner particles mixed in the contact charging member is reduced, the chargeability of the latent image carrier is prevented from being lowered, and the transfer residual toner particles can be collected in the developing process. The load of can be reduced.

This inorganic fine powder adheres to the surface of the toner particles and behaves together with the toner particles, and the number average particle diameter of the primary particles is as small as 4 to 80 nm, and the particle diameter in the state of being adhered to the toner is also small. 0.1 from primary particle size to aggregate
μm or less, and 0.60 μm or more of the developer 15
It does not substantially affect the number-based particle size distribution in the particle size range of less than 9.21 μm.

On the other hand, the conductive fine powder contained in the developer of the present invention is 0.60 μm or more of the developer and 159.21 μm.
In the particle size distribution of the number of particles in the particle size range of less than m, 15 to 6 particles having a particle size of 1.00 μm or more and less than 2.00 μm are used.
Contributes to the inclusion of 0% by number. More specifically,
The conductive fine powder contained in the developer of the present invention has at least particles in a particle size range of 1.00 μm or more and less than 2.00 μm, and a developer of particles in a particle size range of 1.00 μm or more and less than 2.00 μm The effect of the present invention can be obtained by incorporating the conductive fine powder into the developer so that the content in the above range. According to the studies by the present inventors, the presence of conductive fine powder having a particle size range of 1.00 μm or more and less than 2.00 μm in the developer causes the transfer residual toner particles to be transferred to the contact charging member during contact charging. Prevents charging failure of the image carrier due to adhesion and mixing,
It was found that the uniform chargeability of the latent image carrier in the direct injection charging is improved, and the charging failure and the failure to collect transfer residual toner particles are effectively prevented in the image forming method using development and cleaning. In addition, the particle size of the conductive fine powder is greatly involved in the effect as the recovery aid of the transfer residual toner particles in the developing process of the conductive fine powder, and the optimum conductivity of the conductive fine powder as the recovery aid of the transfer residual toner particles is obtained. There is a powder particle size range, especially 1.00 μm or more and 2.00 μm
It has been found that the content (number%) of the conductive fine powder having a particle diameter in the range of less than the particle diameter is deeply involved in the effect as a recovery aid of the transfer residual toner particles.

Particles of the conductive fine powder having a particle size range of 1.00 μm or more and less than 2.00 μm do not adhere firmly to the toner particle surface and are sufficiently supplied to the non-image area on the image carrier in the developing step. In the transfer process, the toner particles are positively released from the surface of the toner particles and efficiently supplied to the charging unit via the latent image bearing surface after the transfer. Further, the conductive fine powder,
Since the latent image carrier can be uniformly dispersed and intervened in the charging unit, the latent image carrier has a high charge promoting effect and is stably held in the charging unit, so that the chargeability of the latent image carrier can be maintained even when the image forming apparatus is repeatedly used over a long period of time. Is prevented, and good uniform charging is stably maintained. In addition, even when the contamination of the charging member due to transfer residual toner particles is unavoidable as in the developing / cleaning image forming method using a contact charging member in the charging step, it is possible to prevent the chargeability of the latent image carrier from deteriorating. You can Further, the particles of the conductive fine powder are efficiently supplied to the latent image carrying surface after the transfer, and exhibit a particularly excellent effect as a recovery aid for the particles of the transfer residual toner. The collectability of particles can be improved.

As described above, the developing agent of the present invention contains
The content of the particles in the particle size range of 1.00 μm or more and less than 2.00 μm in the number-based particle size distribution of the particle size range of 60 μm or more and less than 159.21 μm is 15 to 60% by number. 1.00 in the above particle size measurement range
By setting the content of particles in the particle size range of μm or more and less than 2.00 μm to the above range, it is possible to improve the uniform charging property of the image carrier in the charging step. In addition, since an appropriate amount of conductive fine powder can be stably present in the charging portion, exposure failure due to excessive presence of conductive fine powder on the image carrier is prevented in the subsequent exposure step. can do. 1.00 μm or more in developer 2.00
If the content of particles in the particle size range of less than μm is less than the above range, the uniform charging property of the image bearing member due to contact charging cannot be sufficiently improved, and the transfer residue during development / cleaning cannot be achieved. The effect of effectively preventing defective collection of toner particles is not sufficient. Further, when the content of particles in the particle size range of 1.00 μm or more and less than 2.00 μm in the developer is too much higher than the above range, excessive conductive fine powder is supplied to the charging unit, so that charging is performed. Conductive fine powder that can not be held in the area is discharged onto the image carrier to the extent that it blocks the exposure light, causing image defects due to poor exposure or scattering and contaminating the inside of the machine. .

0.60 μm or more of the developer of the present invention 15
The content of particles having a particle size of 1.00 or more and less than 2.00 μm in the number-based particle size distribution in the particle size range of less than 9.21 μm is more preferably 20 to 50% by number,
It is more preferably 20 to 45% by number. By setting the content of the above particles within this range, the uniform chargeability of the latent image bearing member due to contact charging is further improved, and defective collection of transfer residual toner particles in an image forming method using development and cleaning is effective. The effect of prevention is further enhanced. Further, excessive conductive fine powder is prevented from being supplied to the charging section, and a large amount of conductive fine powder that cannot be held in the charging section is discharged onto the latent image carrier, resulting in image defects due to exposure failure. The occurrence of can be suppressed more reliably.

As described above, the developer of the present invention has
In order to contain 15 to 60% by number of particles in the particle size range of 1.00 μm or more and less than 2.00 μm in the number-based particle size distribution of the particle size range of 60 μm or more and less than 159.21 μm, 1.00 μm or more and less than 2.00 μm The electroconductive fine powder may be contained in the developer so that the content of the particles in the particle size range of 1) in the developer falls within the above range. However, in the number-based particle size distribution of the developer in the particle size range of 0.60 μm or more and less than 159.21 μm, 1.00 μm
The particles in the particle size range of 2.00 μm or more are not limited to the above conductive fine powder, and may include toner particles and other particles added to the developer.

The toner particles containing at least the binder resin and the colorant contained in the developer of the present invention can be obtained by a known production method, and the toner production method and production conditions (for example, the average particle diameter of the toner). The amount of toner particles in the particle size range of 1.00 μm or more and less than 2.00 μm, which is generated depending on the crushing conditions in the case of being manufactured by the crushing method or the crushing method, changes. However, if the developer is 0.60 μm or more 159.21
In the number-based particle size distribution in the particle size range of less than μm, if the content of particles in the particle size range of 1.00 μm or more and less than 2.00 μm due to toner particles exceeds 10% by number,
The triboelectrification property of toner particles having a particle size range of 1.00 μm or more and less than 2.00 μm is greatly different from the triboelectrification property of toner particles having a particle size near the average particle size, so that the tribo distribution becomes broad and Sex tends to decrease.

That is, the developer is 0.60 μm or more and 15
In the number-based particle size distribution in the particle size range of less than 9.21 μm, 1.00 μm or more and 2.0 due to the conductive fine powder
It is preferable to contain 5 to 60% by number of particles of less than 0 μm.

Further, in the developer of the present invention, in the number-based particle size distribution of the particle size range of 0.60 μm or more and less than 159.21 μm, 15 to 70 particles in the particle size range of 3.00 μm or more and less than 8.96 μm are used. It is characterized by containing a number%.

In the developer of the present invention, particles having a particle size range of 3.00 μm or more and less than 8.96 μm develop the electrostatic latent image formed on the latent image carrier to form a toner image,
A predetermined amount is required to form a toner image on the transfer material by transferring the toner image onto the transfer material.
Further, particles in the particle size range of 3.00 μm or more and less than 8.96 μm electrostatically adhere to the electrostatic latent image formed on the latent image carrier, and the electrostatic latent image is faithfully converted into a toner image. It can have triboelectric charging characteristics suitable for development.

Particles having a particle size of less than 3.00 μm are difficult to have stable triboelectrification characteristics such as holding excessive electrification or excessively diminishing triboelectric charge. Therefore, the amount of adhesion to a portion (white background portion of the image) on the latent image carrier on which the electrostatic latent image is absent tends to increase, and it is difficult to faithfully develop the electrostatic latent image as a toner image. Further, particles having a particle size of less than 3.00 μm are difficult to maintain good transferability to a transfer material having unevenness on the surface (for example, paper having unevenness due to fibers on the surface). Transfer residual toner particles increase. Therefore, a large amount of transfer residual toner particles are attached to the latent image carrier during the charging process, and a large amount of transfer residual toner particles are adhered to and mixed with the contact charging member. And the contact charging member has a close contact with the latent image bearing member through the conductive fine powder, so that the effect of the present invention of enhancing the charging property of the latent image bearing member tends to be impaired. Further, when the particle size of the transfer residual toner particles becomes smaller, the mechanical and electrostatic force acting on the transfer residual toner particles in the developing process becomes smaller, and in the case of the magnetic toner, the magnetic recovery force becomes smaller, so that the transfer residual toner particles are relatively transferred. The adhesion between the residual toner particles and the latent image carrier increases, and the collectability of the transfer residual toner particles in the developing process decreases,
Image defects such as positive ghost and fog tend to occur easily due to poor recovery of transfer residual toner particles.

Particles having a particle size of 8.96 μm or more are
It is difficult to provide triboelectric charging characteristics that are high enough to faithfully develop an electrostatic latent image as a toner image. Generally, the larger the particle size of the developer, the lower the resolution of the toner image obtained, but 1.00 μm or more and 2.00 μm or more.
In the developer of the present invention in which the conductive fine powder is contained so that the content of the particles in the particle size range of less than m is within the predetermined range, the developer contains many particles of the conductive fine powder. In particular, since the triboelectric charge amount of toner particles having a large particle size is more likely to decrease, particles having a particle size of 8.96 μm or more are sufficient to faithfully develop an electrostatic latent image as a toner image. It becomes difficult to impart a high triboelectric charging property, and it becomes more difficult to obtain a toner image having good resolution.

Therefore, 0.60 μm or more and 159.21 μ
2. In the number-based particle size distribution in the particle size range of less than m.
By setting the content of particles in the particle size range of 00 μm or more and less than 8.96 μm to the above range, it is possible to secure toner particles having a triboelectric charging property suitable for faithfully developing an electrostatic latent image as a toner image. , 1.00 μm or more and 2.00 μm
An image excellent in resolution at high image density is obtained by using the developer of the present invention containing conductive fine powder so that the content of the particles in the particle size range of less than is within a predetermined range. Can be obtained.

In the present invention, 3.00 μm in the developer
When the content of particles in the particle size range of less than 8.96 μm is too small than the above range, toner particles having triboelectrification characteristics suitable for faithfully developing the electrostatic latent image as a toner image are secured. Will be difficult to do. Therefore, the obtained image has a lot of fogging, a low image density, or a low resolution.

Further, 3.00 μm or more and 8.9 in the developer.
When the content of particles in the particle size range of less than 6 μm is more than the above range, the above-mentioned 1.00 μm or more and 2.00 μm
It becomes difficult to set the content of the particles having a particle size range of less than m in the developer within the range specified in the present invention. Also,
Even if the content of the particles in the particle size range of 1.00 μm or more and less than 2.00 μm in the developer is within the range specified in the present invention, the content of particles in the particle size range of 3.00 μm or more and less than 8.96 μm 1.00 μm or more based on the content 2.
There is a relative shortage of particles in the particle size range of less than 00 μm. For this reason, the uniform chargeability of the image carrier due to contact charging cannot be sufficiently improved, and the effect of effectively preventing defective collection of transfer residual toner particles during development and cleaning cannot be sufficiently obtained.

0.60 μm or more of the developer of the present invention 15
The content of particles in the particle size range of 3.00 μm or more and less than 8.96 μm in the number-based particle size distribution of the particle size range of less than 9.21 μm is more preferably 20 to 65% by number, and 25 It is more preferable that the content is -60% by number. By setting the content of the above particles within this range, the uniform charging property of the image carrier due to contact charging is further improved, and the defective collection of transfer residual toner particles in the image forming method using development and cleaning is effectively prevented. It is possible to obtain an image having a high image density, less fog, and excellent resolution.

As described above, the particles having the triboelectrification characteristics suitable for faithfully developing the electrostatic latent image as a toner image are secured, and an image having a high image density and less fog and excellent resolution is obtained. To obtain the developer of the present invention,
15 to 70% by number of particles having a particle size range of 3.00 μm or more and less than 8.96 μm in the number-based particle size distribution of the particle size range of m or more and less than 159.21 μm. Therefore,
It is desirable that the content of particles having a particle size range of 3.00 μm or more and less than 8.96 μm in the developer be attributed to the toner particles. However, in the developer, 0.60 μm or more 15
In the number-based particle size distribution in the particle size range of less than 9.21 μm, the particles in the particle size range of 3.00 μm or more and less than 8.96 μm are not limited to the toner particles, and are added to the conductive fine powder and the developer. Other particles may be included.

The developer of the present invention is 0.60 μm or more and 15
In the number-based particle size distribution in the particle size range of less than 9.21 μm, particles having a particle size of 8.96 μm or more are 0 to 20% by number.
It is preferable to contain.

As described above, 1.00 μm or more and 2.0
In the developer of the present invention in which the conductive fine powder is contained so that the content of the particles having a particle size range of less than 0 μm in the developer falls within the range specified in the present invention, a large amount of the conductive fine particles is contained in the developer. Since it contains powder particles, it becomes difficult to impart particles having a particle size of 8.96 μm or more with triboelectric charging characteristics sufficiently high to faithfully develop an electrostatic latent image as a toner image. 8.96 μm in the above particle size measurement range
When the content of the above particles in the developer is more than the above range, the developer as a whole may be provided with triboelectrification characteristics sufficiently high to faithfully develop the electrostatic latent image as a toner image. It becomes difficult, and the resolution of the obtained image tends to be low.

Further, in the case of toner particles having a particle size of 8.96 μm or more, it is easy to locally retain a high triboelectric charge on the surface of the toner particles, and if conductive fine powder adheres to such a portion, the conductive fine powder Becomes to behave together with the toner particles without being released from the toner particles, and the conductive fine powder supplied onto the latent image bearing member after transfer tends to decrease.

Therefore, the effect of accelerating the charging of the latent image carrier due to the presence of the conductive fine powder in the charging portion may not be sufficiently obtained. In addition, since the conductive fine powder supplied onto the latent image carrier after transfer tends to decrease, the effect of improving the collectability of the transfer residual toner may not be obtained in some cases.

Further, when toner particles having a large particle diameter are carried to the charging section as transfer residual toner particles, the contactability of the contact charging member to the latent image carrier is impaired, and charging failure of the latent image carrier is caused. It will be easier. That is, the effect of the present invention that enhances the uniform charging property of the latent image carrier may not be obtained because the contact charging member has a close contact property with the latent image carrier through the conductive fine powder. Further, when the transfer residual toner particles having a large particle diameter are to be collected in the developing step, the transfer residual toner particles having a large particle diameter are not collected and an image defect occurs, or the exposure in the latent image forming step is performed. Occasionally, it may cause an image defect by blocking.

Therefore, the developer of the present invention is 0.60 μm.
In the number-based particle size distribution in the particle size range of 159.21 μm or less, the number of particles having a particle size of 8.96 μm or more in the developer is more preferably 0 to 10% by number, and 0 to 10% by number is more preferable.
It is more preferably 7% by number. By setting the content of the above particles in this range, it is possible to obtain an image having higher image density, less fog, and excellent resolution. Also,
Since the contact charging member has close contact with the latent image bearing member through the conductive fine powder, it is more advantageous in enhancing the uniform charging property of the latent image bearing member, and recovery of transfer residual toner during development. This is more advantageous in suppressing the generation of image defects due to defects and light blocking of exposure in the latent image forming process.

Further, the developer of the present invention has a content of particles in the particle size range of 1.00 μm or more and less than 2.00 μm in the number-based particle size distribution of the particle size range of 0.60 μm or more and less than 159.21 μm. A number%, 2.00 μm or more 3.
When the content of particles in the particle size range of less than 00 μm is defined as B number%, it is preferable that the relationship of A> B is satisfied.
It is more preferable to satisfy the relationship of> 2B.

That is, 2.00 μm or more and 3.00 μm
The content B of the particles in the particle size range of less than B% by number is 1.00 μ
The content A of the particles in the particle size range of m or more and less than 2.00 μm is preferably less than A number%. When the number-based particle size distribution in the measured particle size range of 0.60 μm or more and less than 159.21 μm of the developer of the present invention satisfies the above relationship, conductive fine powder may be uniformly dispersed and intervene in the charging part. It is possible to obtain a good uniform charging property.

When the above A and B do not satisfy the relation of A> B, the uniform dispersibility of the conductive fine powder present in the charging portion is lowered, or the holding property of the conductive fine powder on the contact charging member is lowered. And the effect of uniformizing the charging of the latent image bearing member is likely to deteriorate. In addition, the supply of the conductive fine powder to the charging portion is poor, and the repeated use over a long period of time reduces the effect of accelerating the charging of the latent image bearing member, making the charging of the latent image bearing member unstable. When the relationship of A> B is not established, the transferability is relatively low, that is, 2.00 μm or more and 3.00 μm.
Since more toner particles having a particle size range of less than m are supplied to and retained in the charging portion, the retention of the conductive fine powder in the charging portion is relatively decreased, and the image forming apparatus is repeatedly used over a long period of time. Tends to hinder the uniform charging of the latent image carrier, and the fine particles of the toner particles in the transfer residual toner particles increase, so that the collectability of the transfer residual toner particles decreases, and a positive ghost or fog easily occurs.

That is, the conductive fine powder particles in the particle size range of 2.00 μm or more and less than 3.00 μm are:
The electrostatic charge accelerating effect obtained by interposing the conductive fine powder in the charging portion is significantly inferior to that of the conductive fine powder having a particle size range of 00 μm or more and less than 2.00 μm. Is also inferior in the effect of improving the recoverability of. 2.
Of the particles in the particle size range of 00 μm or more and less than 3.00 μm, the toner particles are liable to cause fog because of the unstable triboelectricity, and the transferability is low. Therefore, a larger amount of transfer residual toner particles are supplied to the charging section, which tends to hinder uniform charging of the latent image carrier. Further, since the transfer residual toner particles increase and the triboelectric chargeability of the transfer residual toner is unstable, the collectability of the transfer residual toner particles during development tends to decrease. Therefore, it is preferable that the content of particles having a particle size in the particle size range of 2.00 μm or more and less than 3.00 μm is small. That is, it is preferable that the content ratio of particles having a particle size in the particle size range of 2.00 μm or more and less than 3.00 μm is small in the entire particle size distribution of the developer.

From these viewpoints, 1.00 μm or more.2.
If the content A of particles in the particle size range of less than 00 μm is% by number,
The content B of particles in the particle size range of 2.00 μm or more and less than 3.00 μm is preferably more than B% by number, and 1.00 μm
More preferably, the content A number% of particles in the particle size range of m or more and less than 2.00 μm is more than twice the content B number% of particles in the particle size range of 2.00 μm or more and less than 3.00 μm. .

When the content of particles in the particle size range of 3.00 μm or more and less than 8.96 μm is defined as C number%, the C number% of the particles in the particle size range of 2.00 μm or more and less than 3.00 μm is The content B is preferably more than twice the number% and more preferably more than three times.

In the number-based particle size distribution in the particle size range of 0.60 μm or more and less than 159.21 μm, 2.00 μm
The content B number% of particles in the particle size range of 3.00 μm or more is preferably 20 number% or less, more preferably 10% or less, and particularly preferably 5% or less.

The developer of the present invention has a number-based particle size distribution in the particle size range of 0.60 μm or more and less than 159.21 μm, and is represented by the following formula in the particle size range of 3.00 μm or more and less than 15.04 μm. The coefficient of variation K _{n of the} number distribution
It is preferably 5 to 40.

Coefficient of variation of particle size distribution on a number basis K _n = (S
_n / D ₁ ) × 100 [In the formula, S _n represents the standard deviation of the number distribution in the particle size range of 3.00 μm or more and less than 15.04 μm, and D ₁ is the particle size range of 3.00 μm or more and less than 15.04 μm. Represents the number-based average equivalent circle diameter (μm). By setting the coefficient of variation K _n to 5 to 40, uniform mixing of the toner particles and the conductive fine powder can be obtained, and the conductive fine powder is more uniformly supplied onto the latent image carrier. As a result, the effect of uniformizing the charging of the latent image carrier can be further enhanced. Further, the charge amount distribution of the toner particles is sharpened, the toner particles that become fog and the transfer residual toner particles are reduced, and the charge inhibition of the latent image carrier can be suppressed more stably. In addition, since the transfer residual toner particles can be more stably collected in the developing process, it is possible to more reliably suppress the image defect caused by the defective collection. In order to further sharpen the distribution of the charge amount of the toner particles, the above variation coefficient K
More preferably, _n is 5 to 30.

Further, the developer of the present invention has a weight average particle size (D ₄ ) of 4 to 1 obtained from the volume-based particle size distribution in the particle size range of 0.60 μm or more and less than 159.21 μm.
It is preferably 0 μm, and 3.00 μm or more 15.
In the particle size range of less than 04 μm, the variation coefficient K _{v of the} volume-based particle size distribution represented by the following formula is preferably 10 to 30.

Coefficient of variation of volume-based particle size distribution K _v = (S
_v / D ₄ ) × 100 [In the formula, S _v represents the standard deviation of the volume distribution in the particle size range of 3.00 μm or more and less than 15.04 μm, and D ₄ is the particle size range of 3.00 μm or more and less than 15.04 μm. Represents the volume-based volume average particle size (μm). ] The coefficient of variation K _{v of the} volume-based particle size distribution is 10 to 30, so that the developer has 3.00 μm or more and 15.04 μm or more.
In this case, the distribution of the charge amount of the particles in the particle size range of less than is sharpened, the toner particles that become fog and the toner particles remaining after the transfer are reduced, and the charge inhibition of the image carrier can be suppressed more stably.
Further, since the collectability of the transfer residual toner particles in the developing / cleaning step can be improved, image defects due to defective collection can be effectively prevented. Therefore, the coefficient of variation K
More preferably, _v is 10 to 25.

If the coefficient of variation K _n or K _v is smaller than the above range, it becomes difficult to produce toner particles, and if the coefficient of variation K _n or K _v is larger than the above range. In addition, it is difficult to obtain a uniform mixing property of the toner particles with the inorganic fine powder and the conductive fine powder, and it is difficult to obtain a stable charging promoting effect of the image carrier. In addition, the distribution of the charge amount of the developer as a whole becomes broad, and the image density decreases,
Image quality deteriorates due to increased fog. Furthermore, the amount of transfer residual toner particles increases, which hinders the charging property, and the recovery rate of the transfer residual toner particles in the development / cleaning step decreases.

[0153] With the variation coefficient _{K v} 15-30, the charge amount distribution of the particles is sharpened in a particle size range of less than 15.04μm than 3.00μm developer, the toner particles and transfer to the fog The residual toner particles are reduced, and the charge inhibition of the image carrier can be suppressed more stably.
Further, since the collectability of the transfer residual toner particles in the developing / cleaning step can be improved, it is possible to effectively prevent the image defect due to the defective collection of the toner particles. The variation coefficient K _v is more preferably 15 to 25.

Further, in the developer of the present invention, it is preferable that the average circularity of the toner obtained by the following formula is less than 0.970. When the average circularity is 0.970 or more, the external additive is less likely to be retained on the toner surface, and as a result, the charge is nonuniform and fog is likely to occur. Further, the external additive may be embedded due to stirring of the developer or temperature rise during the durable use, and the deterioration of the toner surface becomes remarkable, which causes a problem in the durability and the like.

Circularity a = L ₀ / L [In the formula, L ₀ represents the perimeter of a circle having the same area as the projected image of the particle, and L represents the perimeter of the projected image of the particle. The developer of the present invention preferably has a standard deviation SD of 0.045 or less in the circularity distribution calculated by the following formula in a particle size range of 3.00 μm or more and less than 15.04 μm. During standard deviation _{SD = {Σ (a i -a} m) 2 / n} 1/2 [wherein, _{a i} represents the circularity of each particle in the size range less than 3.00μm 15.04μm, _{a m} Is 3.0
The average circularity of particles of 0 μm or more and less than 15.04 μm is represented, and n represents the total number of particles having a particle diameter of 3.00 μm or more and less than 15.04 μm. When the standard deviation SD of the circularity distribution of the developer is 0.045 or less, the liberation of the conductive fine powder from the toner particles is stabilized, and the conductive fine powder can be supplied onto the image carrier. Since it is more stable, the inhibition of charging of the image bearing member can be suppressed more stably, and the recoverability of toner particles in the step of developing and cleaning (that is, the step of developing and cleaning) is more stable.

In the present invention, the particle size, particle size distribution and circularity distribution of the developer are the flow type particle image analyzer FPIA-
A circle equivalent diameter measured by 1000 (manufactured by Toa Medical Electronics Co., Ltd.) is defined as "particle diameter", and a particle diameter of 0.60 µm or more 15
It is a value obtained by using the number-based particle size distribution and circularity distribution of less than 9.21 μm.

The measurement by the flow-type particle image analyzer is performed by the following method. Fine dust is removed through a filter, and as a result, the measurement range (for example, equivalent circle diameter of 0.60 μm or more and 159.21 μm) in 10 ³ cm ^3.
(less than m), a few drops of a surfactant (preferably diluted with water from which fine dust is removed from alkylbenzene sulfonate to about 10 times) diluted in 10 ml of water having 20 or less particles are added. An appropriate amount (for example, 0.5 to 20 mg) of a measurement sample is added to this, and dispersion treatment is performed for 3 minutes with an ultrasonic homogenizer (output 50 W, 6 mm diameter step type chip), and the particle concentration of the measurement sample is 7,000 to 100.
0.60 μ using a sample dispersion liquid adjusted to 00 particles / 10 ⁻³ cm ³ (for particles in the diameter range equivalent to the measurement circle)
The particle size distribution and the circularity distribution of particles having a circle equivalent diameter of m or more and less than 159.21 μm are measured.

The outline of the measurement is as follows: Catalog of FPIA-1000 issued by Toa Medical Electronics Co., Ltd. (June 1995 version), operation manual of measuring device and JP-A-8-136.
It is described in Japanese Patent No. 439, but is as follows.

The sample dispersion liquid is passed through the flow passage (which spreads along the flow direction) of a flat and flat transparent flow cell (thickness: about 200 μm). A strobe and a CCD camera are mounted on opposite sides of the flow cell so as to form an optical path that intersects and passes through the thickness of the flow cell. While the sample dispersion is flowing, strobe light is illuminated at 1/30 second intervals to obtain an image of the particles flowing through the flow cell. As a result, each particle is photographed as a two-dimensional image having a certain range parallel to the flow cell. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area as the area of this two-dimensional image is calculated as the equivalent circle diameter.

The circumference of each particle is obtained from the two-dimensional image of each particle, and the circularity distribution is obtained by calculating the ratio of the area of this two-dimensional image to the circumference of a circle having the same area. Desired.

The measurement results (frequency% and cumulative% of particle size distribution and circularity distribution) were 0.06 to 0.06 as shown in Table 1 below.
The range of 400 μm can be obtained by dividing it into 226 channels (divided into 30 channels for one octave). In actual measurement, the equivalent circle diameter is 0.60 μm or more 15
Particles are measured in the range of less than 9.21 μm.

[0162]

[Table 1]

[0163] The measuring apparatus "FPIA-1000" used in the present invention, after calculating the circularity of each particle,
In calculating the average circularity, the particles are divided into 61 classes by dividing the circularity 0.40 to 1.00 according to the circularity obtained, and the average circularity is calculated using the center value and frequency of the division points. The calculation method is used. However, the error between the value of the average circularity calculated by this calculation method and the average circularity calculated by the arithmetic mean of the circularity of each particle is very small, and is substantially negligible. And
In the present invention, such a calculation method may be used for the reason of handling data such as shortening of calculation time and simplification of calculation calculation formula.

The developer of the present invention has a particle size of 0.1 to 0.1.
It is preferable to have 5 to 500 particles of conductive fine powder of 10 μm per 100 toner particles. Particle size is 0.1
The particles of the conductive fine powder having a particle size of 10 μm easily separate from the toner particles to behave easily, and are uniformly attached to the charging member and stably held. Therefore, the particle size in the developer is 0.1 to 1
By having 5 to 500 particles of the conductive fine powder of 0 μm per 100 toner particles, the supply of the conductive fine powder onto the image carrier is further promoted in the developing process and the transfer process, and the image carrier is charged. The stability can be made more uniform. Further, since the developer contains 5 to 500 particles of conductive fine powder having a particle size of 0.1 to 10 μm per 100 toner particles, the recoverability of the transfer residual toner particles in the developing and cleaning step is more stable. To do.

In the developer of the present invention, the particle size is 0.1 to 0.1
When the number of particles of the conductive fine powder of 10 μm is less than 5 per 100 toner particles, it is caused by the conductive fine powder.
5 to 5 particles in the particle size range of 00 μm or more and less than 2.00 μm
It is difficult to contain 60% by number, and the above-mentioned 1.
15 particles in the particle size range from 00 μm to less than 2.00 μm
In some cases, the effects of the present invention, such as the effect of accelerating the charging of the image carrier and the effect of improving the collectability of the transfer residual toner particles in the cleaning for development and the like, may be significantly reduced by the inclusion of -60% by number. Further, in the developer of the present invention, the particle size is 0.
1 to 10 μm of conductive fine powder is toner particles 100.
If the number of particles is significantly larger than 500, the ratio of the particles of the conductive fine powder to the toner particles is too high, which hinders the triboelectric charging of the toner particles and reduces the developability and transferability as a developer. Image density decrease, fog increase,
The uniform chargeability is deteriorated due to the increase of the transfer residual toner particles, and the defective collection of the transfer residual toner particles during the development / cleaning is likely to occur. From such a point of view, particles of conductive fine powder of 0.1 to 10 μm are added to the toner particles 1 in the developer.
More preferably 5 to 300 per 00,
It is more preferable to have 10 to 200 pieces.

The number of conductive fine particles of 0.1 to 10 μm per 100 toner particles in the developer of the present invention is a value obtained by the following measurement. That is, a photograph of the developer magnified by the scanning electron microscope is compared with a photograph of the developer mapped by the elements contained in the conductive fine powder by an element analysis means such as XMA attached to the scanning electron microscope. And toner particles 100
For each of the particles, the conductive fine powder adhering to or separated from the surface of the toner particles is specified, and the image processing apparatus (for example, FE-S manufactured by Hitachi, Ltd.) among the specified conductive fine powder is specified.
Image information magnified 3000 to 10000 times from EMS-800 is introduced into an image analyzer LuzexIII manufactured by Nireco Co., Ltd. through an interface for analysis.
Is a value obtained by counting the number of particles of the conductive fine powder having an equivalent circle diameter of 0.1 to 10 μm.

Further, in the developer of the present invention, the content of the conductive fine powder is preferably 0.1 to 10% by mass of the whole developer. By setting the content of the conductive fine powder within the above range, an appropriate amount of conductive fine powder for promoting the charging of the image carrier can be supplied to the charging portion, and the transfer residual toner in the development / cleaning process. It is possible to supply the conductive fine powder in an amount necessary for enhancing the collectability of particles onto the image carrier. When the content of the conductive fine powder of the developer is too smaller than the above range, the amount of the conductive fine powder supplied to the charging section is likely to be insufficient, and it is difficult to obtain a stable charge promoting effect of the image carrier. . In this case, even in the image formation using the development / cleaning, the amount of the conductive fine powder present on the image carrier together with the transfer residual toner particles at the time of development tends to be insufficient, and the recovery property of the transfer residual toner particles is not sufficiently improved. There are cases. Further, when the content of the conductive fine powder of the developer is too large than the above range, excessive conductive fine powder is easily supplied to the charging portion, and a large amount of conductive fine powder cannot be held in the charging portion. Then, defective exposure is likely to occur due to discharge onto the image carrier. Further, the triboelectrification characteristics of the toner particles may be deteriorated or disturbed, which may cause a decrease in image density and an increase in fog.

From such a viewpoint, the content of the conductive fine powder of the developer is more preferably 0.1 to 10% by mass, further preferably 0.2 to 5% by mass.

Further, the resistance of the conductive fine powder is 10 ⁹ Ω · cm or less in order to impart to the developer the effect of accelerating the charging of the latent image carrier and the effect of improving the transfer residual toner particle recoverability. preferable. If the resistance of the conductive fine powder is too large than the above range, the conductive fine powder is interposed in the contact area between the charging member and the latent image carrier or in the charging area in the vicinity of the contact area, and contact is made via the conductive fine powder. Even if the close contact property of the charging member to the latent image carrier is maintained, the charging promotion effect for obtaining good uniform charging property of the latent image carrier becomes small. Even during development / cleaning, the conductive fine powder is likely to be charged with the same polarity as the transfer residual toner particles, and when the charge of the conductive fine powder is large with the same polarity as the transfer residual toner particles, the transfer residual toner particle recoverability is deteriorated. The improvement effect is significantly reduced.

In order to sufficiently bring out the charge accelerating effect of the latent image bearing member by the conductive fine powder and to stably obtain the good uniform charging property of the latent image bearing member, the resistance of the conductive fine powder is set to the contact charging. The resistance of the contact charging member is preferably smaller than the resistance of the surface portion of the member or the contact portion with the latent image carrier.
/ 100 or less is more preferable.

Furthermore, the resistance of the conductive fine powder is 10 ⁶ Ω · c.
When it is m or less, it is possible to overcome the charge inhibition due to the adhesion and mixing of the insulating transfer residual toner particles to the contact charging member, and to perform the uniform charging of the image carrier better, and also to perform the development / cleaning. In order to obtain the effect of improving the recoverability of the transfer residual toner particles more stably, it is preferable. It is further preferred that the electroconductive fine powder of the resistor is ¹⁰ 0 ^{~10 5 Ω} · cm.

In the present invention, the resistance of the conductive fine powder can be measured by the tablet method and normalized.
That is, about 0.5 g of the powder sample was put in a cylinder having a bottom area of 2.26 cm ² , and 147 N (15 kg) was applied between the upper and lower electrodes arranged above and below the powder sample and at the same time 100 V was applied.
The voltage is applied to measure the resistance value, and then normalized to calculate the specific resistance.

The conductive fine powder is preferably transparent, white or light-colored conductive fine powder because the conductive fine powder transferred onto the transfer material is not noticeable as fog. The conductive fine powder is preferably transparent, white or light-colored conductive fine powder also from the viewpoint of preventing the exposure light from being obstructed in the latent image forming step. Further, it is preferable that the conductive fine powder has a transmittance of 30% or more for the image exposure light forming the electrostatic latent image. This transmittance is 35%
It is more preferable that the above is satisfied.

An example of the method for measuring the light transmittance of the conductive fine powder in the present invention will be shown below. The transmittance is measured with one layer of conductive fine powder fixed on the adhesive layer of a transparent film having an adhesive layer on one surface. Light is emitted from the vertical direction of the sheet, and the light transmitted to the back surface of the film is condensed and the amount of light is measured. The light transmittance as the net light amount was calculated based on the difference in the light amount when the film alone was used and when the conductive fine powder was attached. Actually, X-Rite 310
It can be measured using a T transmission densitometer.

The conductive fine powder is preferably non-magnetic. Since the conductive fine powder is non-magnetic, it is transparent,
White or pale conductive fine powder is easily obtained. On the contrary, it is difficult to make the conductive material having magnetism transparent, white or light color. Further, in the image forming method in which the developer is conveyed and held by a magnetic force for carrying the developer, the conductive fine powder having magnetism is hard to be developed. Therefore, the conductive fine powder is supplied onto the image carrier. Out of
Accumulation of conductive fine powder on the surface of the developer carrier easily causes problems such as hindering development of toner particles.
Furthermore, when magnetically conductive fine powder is added to magnetic toner particles, it tends to be difficult for the conductive fine powder to be released from the toner particles due to the magnetic cohesive force, and the conductive fine powder is supplied onto the image carrier. The property is likely to deteriorate.

As the conductive fine powder in the present invention, for example, carbon fine powder such as carbon black and graphite; metal fine powder such as copper, gold, silver, aluminum and nickel; zinc oxide, titanium oxide, tin oxide and aluminum oxide. , Metal oxides such as indium oxide, silicon oxide, magnesium oxide, barium oxide, molybdenum oxide, iron oxide and tungsten oxide; metal compounds such as molybdenum sulfide, cadmium sulfide and potassium titanate, or complex oxides of these are required. It can be used by adjusting the particle size and particle size distribution accordingly.

Among them, the conductive fine powder preferably contains at least one oxide selected from zinc oxide, tin oxide and titanium oxide. Further, fine particles having an inorganic oxide such as zinc oxide, tin oxide or titanium oxide on at least the surface thereof are particularly preferable. These oxides can be set to have a low resistance as a conductive fine powder, are non-magnetic, have a white or light color, and the conductive fine powder transferred onto the transfer material is not noticeable as fog. Therefore, it is preferable.

When the conductive fine powder is made of a conductive inorganic oxide or contains a conductive inorganic oxide, the main metal element of the conductive inorganic oxide is used for the purpose of controlling the resistance value or the like. Alternatively, a metal oxide containing an element such as antimony or aluminum, or a conductive material can be used. For example, zinc oxide containing aluminum, stannic oxide fine particles containing antimony, or fine particles obtained by treating the surface of titanium oxide, barium sulfate or aluminum borate with tin oxide containing antimony. The amount of the element such as antimony and aluminum contained in the conductive inorganic oxide is 0.05 to 20.
It is preferable to set it as the mass%, more preferably 0.05
-10 mass%, especially preferably 0.1-5 mass%.

Further, a conductive inorganic oxide in which the inorganic oxide is made oxygen deficient is also preferably used.

Commercially available tin oxide / antimony-treated conductive titanium oxide fine particles include, for example, EC-300.
(Titanium Industry Co., Ltd.), ET-300, HJ-1, H
I-2 (above, Ishihara Sangyo Co., Ltd.), WP (Mitsubishi Materials Co., Ltd.), etc. are mentioned.

Commercially available antimony-doped conductive tin oxides include, for example, T-1 (Mitsubishi Materials Corporation) and SN-100P (Ishihara Sangyo Co., Ltd.), and commercially available stannic oxide includes SH- S (Japan Chemical Industry Co., Ltd.) and the like can be mentioned.

Particularly preferred are metal oxides such as zinc oxide containing aluminum, and metal oxides such as oxygen-deficient zinc oxide, tin oxide, and titanium oxide, in that high whiteness or translucency is obtained. And fine particles having at least the surface thereof.

The particle size is preferably 0.1 to 10 μm. If the volume average particle diameter of the conductive fine powder is too smaller than the above range, the content of the conductive fine powder in the developer must be set small in order to prevent the deterioration of the developing property. If the amount of the conductive fine powder added is set too small, the effective amount of the conductive fine powder cannot be secured, and in the charging process, the electrostatic charge of the contact charging member may be hindered by the adhesion and mixing of the insulating transfer residual toner particles. An amount of conductive fine powder sufficient to overcome and charge the latent image carrier satisfactorily cannot be interposed in the contact area between the charging member and the latent image carrier or in the charging area in the vicinity thereof, Poor charging is likely to occur.
From this viewpoint, the conductive fine powder has a volume average particle diameter of 0.1 μm.
m or more, preferably 0.15 μm or more, more preferably 0.2 μm or more.

If the volume average particle size of the conductive fine powder is larger than the above range, the conductive fine powder dropped from the charging member blocks or diffuses the exposure light forming the electrostatic latent image. There is a case where a defect of the electrostatic latent image is caused to deteriorate the image quality, which is not preferable. Further, if the volume average particle size of the conductive fine powder is larger than the above range, the number of particles of the conductive fine powder per unit weight decreases, so that the recovery of transfer residual toner particles can be sufficiently improved. Disappear. Also,
Since the number of particles of the conductive fine powder decreases, the conductive fine powder is charged in consideration of the decrease and deterioration of the conductive fine powder existing in the charging member and its vicinity due to the dropping of the conductive fine powder from the charging member. In order to continuously supply and interpose the charging area in the contact portion between the member and the image carrier or in the vicinity thereof,
In order for the contact charging member to maintain close contact with the image carrier through the conductive fine powder and to stably obtain good uniform charging property, the content of the conductive fine powder in the developer should be large. I have no choice but to do it. However, if the content of the conductive fine powder is too large, the chargeability and the developability of the developer as a whole, especially in a high humidity environment, are lowered, and the image density is lowered and the toner is scattered. From such a viewpoint, the volume average particle diameter of the conductive fine powder is more preferably 10 μm or less, and most preferably 5 μm or less.

A method for measuring the volume average particle size and particle size distribution of the above conductive fine powder will be illustrated. Coulter LS-23
A liquid module is attached to a 0-type laser diffraction type particle size distribution measuring device, and a particle size of 0.04 to 2000 μm is set as a measurement range, and the volume average particle size of the conductive fine powder is calculated from the obtained volume-based particle size distribution. As the measurement procedure, a trace amount of a surfactant was added to 10 cc of pure water, 10 mg of a conductive fine powder sample was added thereto, and the mixture was dispersed for 10 minutes by an ultrasonic disperser (ultrasonic homogenizer), and then a measurement time of 90
The measurement is performed once per second.

In the measurement from the toner, pure water 100
2 g of toner by adding a trace amount of surfactant to g
Add 10g, ultrasonic disperser (ultrasonic homogenizer)
After 10 minutes of dispersion, the toner particles are separated from the conductive fine powder by a centrifuge or the like. In the case of magnetic toner, a magnet can also be used. The separated dispersion is measured for 90 seconds with one measurement.

In the present invention, as a method for adjusting the particle size and particle size distribution of the conductive fine powder, a manufacturing method and a manufacturing method are used so that the primary particles of the conductive fine powder can obtain a desired particle size and particle size distribution at the time of manufacturing. In addition to the method of setting the conditions, a method of aggregating small particles of primary particles, a method of crushing large particles of primary particles, a method by classification, or the like is possible, and further, a group having a desired particle size and particle size distribution. A method of attaching or fixing conductive particles to a part or all of the surface of material particles, a method of using conductive fine particles having a form in which a conductive component is dispersed in particles having a desired particle size and particle size distribution, and the like are also possible. It is also possible to adjust the particle size and particle size distribution of the conductive fine powder by combining these methods.

The particle diameter when the particles of the conductive fine powder are formed as an agglomerate is defined as the average particle diameter as the agglomerate. There is no problem that the conductive fine powder exists not only in the state of primary particles but also in the state of agglomeration of secondary particles. Whatever the state of aggregation, any form may be used as long as it is present as an aggregate in the charging area between the charging member and the image carrier or in the charging area in the vicinity thereof to realize the function of assisting or promoting charging.

The developer of the present invention further contains an inorganic fine powder having a number average particle diameter of primary particles of 4 to 80 nm. When the number average particle diameter of the primary particles of the inorganic fine powder is too large than the above range, or when the inorganic fine powder in the above range is not added, the charging member when the transfer residual toner particles adhere to the charging member Therefore, it becomes difficult to stably adhere to the latent image carrier with good uniformity. Further, it becomes difficult to uniformly disperse the conductive fine powder in the developer with respect to the toner particles, and it is easy to cause uneven supply of the conductive fine powder onto the latent image carrier, and uneven supply to the contact charging member. In the case of occurrence of, the latent image carrier corresponding to the portion where the supply of the conductive fine particles is insufficient is apt to be charged, and an image defect is likely to occur. Further, when the amount of the conductive fine powder present on the latent image carrier is uneven during the development / cleaning, the recoverability of the transfer residual toner particles is temporarily or partially lowered, resulting in poor recovery. Further, since the developer does not have good fluidity and the toner particles are apt to be imparted with triboelectrification, problems such as increased fog, reduced image density, and toner scattering are likely to occur. When the number average particle diameter of the primary particles of the inorganic fine powder is smaller than 4 nm, the cohesiveness of the inorganic fine powder is increased, and the particle size distribution is wide, having a strong cohesiveness that is hard to be broken by the crushing process instead of the primary particles. Since it easily acts as an agglomerate, an image defect due to development of the agglomerate of the inorganic fine powder, and an image defect due to damage to the image bearing member, the developer bearing member, the contact charging member, or the like are likely to occur. From these viewpoints, the number average particle diameter of the primary particles of the inorganic fine powder is more preferably 6 to 50 nm, and 8 to
More preferably, it is 35 nm.

That is, in the present invention, the inorganic fine powder having the average diameter of the primary particles is attached to the surface of the toner particles to improve the fluidity of the developer and to make the triboelectric charging of the toner particles uniform. Not only is it added, but it also has the effect of uniformly dispersing the conductive fine powder in the developer with respect to the toner particles and uniformly supplying the conductive fine powder onto the latent image carrier.

In the present invention, the number average particle diameter of the primary particles of the inorganic fine powder is a value obtained by measuring by the following method. That is, the photograph of the developer magnified by the scanning electron microscope is contrasted with the photograph of the developer mapped by the element contained in the inorganic fine powder by the element analysis means such as XMA attached to the scanning electron microscope. The number average particle size can be determined by measuring 100 or more primary particles of the inorganic fine powder that are present on the surface of the toner either adhering to or free from them.

In the present invention, the inorganic fine powder is silica, titania, having a number average particle diameter of primary particles of 4 to 80 nm,
It is preferable to contain at least one selected from alumina. For example, as the silica fine powder, it is possible to use both a so-called dry method produced by vapor phase oxidation of a silicon halide or a dry silica called fumed silica, and a so-called wet silica produced from water glass or the like. However, dry silica having less silanol groups on the surface and inside the silica fine powder and less production residues such as Na ₂ O and SO ^{3 −} is preferable. In the case of dry silica, it is also possible to obtain a composite fine powder of silica and another metal oxide by using a metal halogen compound such as aluminum chloride or titanium chloride together with a silicon halogen compound in the manufacturing process. Include.

In addition, in the present invention, the inorganic fine powder is preferably hydrophobized. By hydrophobizing the inorganic fine powder, it is possible to prevent the deterioration of the chargeability of the inorganic fine powder in a high humidity environment, and to improve the environmental stability of the triboelectric charge amount of the toner particles on which the inorganic fine powder adheres to the surface. Further, it is possible to further improve the environmental stability of the image density as a developer and the development characteristics such as fog. By suppressing the fluctuation of the chargeability of the inorganic fine powder and the triboelectric charge amount of the toner particles on the surface of which the inorganic fine powder adheres to the environment, the easiness of releasing the conductive fine powder from the toner particles varies. It is possible to prevent this, stabilize the supply amount of the conductive fine powder onto the image carrier, and improve the environmental stability of the chargeability of the image carrier and the recovery property of the transfer residual toner particles.

As the treatment agent for the hydrophobic treatment, a treatment agent such as silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oil, silane compounds, silane coupling agents, other organic silicon compounds and organic titanium compounds are used alone. Alternatively, it may be used in combination. Among them, it is particularly preferable that the inorganic fine powder is treated with at least silicone oil.

The silicone oil preferably has a viscosity at 25 ° C. of 10 to 200,000 mm ² / s, more preferably 3,000 to 80,000 mm ² / s. If the viscosity of the silicone oil is lower than the above range, the treatment of the inorganic fine powder is not stable, and the treated silicone oil is desorbed, transferred or deteriorated by heat and mechanical stress, and the image quality is deteriorated. Tend. If the viscosity is too high, the uniform treatment of the inorganic fine powder tends to be difficult.

As the silicone oil used, for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil and fluorine modified silicone oil are particularly preferable.

As a method for treating silicone oil,
For example, the inorganic fine powder treated with the silane compound and the silicone oil may be directly mixed by using a mixer such as a Henschel mixer, or the inorganic fine powder may be sprayed with the silicone oil. Alternatively, a method may be used in which silicone oil is dissolved or dispersed in a suitable solvent, and then silica fine powder is added and mixed to remove the solvent. The method using a sprayer is more preferable because the formation of aggregates of the inorganic fine powder is relatively small.

The amount of silicone oil to be treated is 1 for inorganic fine powder.
1 to 23 parts by weight, preferably 5 to 20 parts by weight with respect to 00 parts by weight
Good mass parts. If the amount of silicone oil is less than the above range, good hydrophobicity cannot be obtained, and if it is too large, problems such as fog may occur.

In the present invention, it is preferable that the inorganic fine powder is treated with at least the silane compound and simultaneously with the silicone oil.
It is particularly preferable to use a silane compound for the treatment of the inorganic fine powder in order to enhance the adhesion of the silicone oil to the inorganic fine powder and to make the hydrophobicity and the chargeability of the inorganic fine powder uniform.

The conditions for treating the inorganic fine powder include, for example, a silylation reaction as a first-step reaction to eliminate silanol groups by a chemical bond, and a second-step reaction with a silicone oil to form a hydrophobic thin film on the surface. can do.

Further, in the developer of the present invention, the content of the inorganic fine powder is preferably 0.1 to 3.0% by mass of the whole developer. If the content of the inorganic fine powder is less than the above range, the effect of adding the inorganic fine powder cannot be sufficiently obtained. The fine powder covers the conductive fine powder, and the conductive fine powder behaves in the same manner as when the resistance is high, which reduces the supply of the conductive fine powder onto the image carrier and promotes charging. The effects of the present invention such as a decrease in the effect and a decrease in the collectability of the transfer residual toner particles are impaired. The content of the inorganic fine powder is 0.3 to 2.0 mass% of the entire developer.
Is more preferable, and even more preferably 0.5 to
It is 1.5% by mass.

[0202] inorganic fine powder number-average diameter of 4~80nm primary particles used in the present invention has a specific surface area by nitrogen adsorption measured by BET method preferably has 20~250m ² / g, 40~200m ² / G is more preferable. The specific surface area can be calculated according to the BET method by using the specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) to adsorb nitrogen gas on the sample surface and using the BET multipoint method.

In the present invention, the toner particles are colored resin particles containing at least a binder resin and a colorant. The resistance of the toner particles is preferably 10 ¹⁰ Ω · cm or more, and more preferably 10 ¹² Ω · cm or more. If the toner particles do not exhibit substantially insulating properties, it is difficult to achieve both developability and transferability. Further, injection of electric charges into the toner particles due to the developing electric field is likely to occur, disturbing the charging of the developer and causing fog.

The binder resin contained in the toner particles used in the present invention includes, for example, styrene resins, styrene copolymer resins, polyester resins, polyvinyl chloride resins, phenol resins, natural modified phenol resins, Natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyurethane resin, polyamide resin, furan resin, epoxy resin,
Xylene resin, polyvinyl butyral, terpene resin,
Cumaron indene resin, petroleum resin, etc. can be used.

Examples of the comonomer for the styrene monomer of the styrene type copolymer include styrene derivatives such as vinyltoluene; for example, acrylic acid or methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, Acrylic acid-2
-Acrylic acid esters such as ethylhexyl and phenyl acrylate; for example, methacrylic acid esters such as methacrylic acid or methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate; for example maleic acid or butyl maleate, malein Dicarboxylic acid esters having a double bond such as methyl acidate and dimethyl maleate; vinyl esters such as acrylamide, acrylonitrile, methacrylonitrile, butadiene or vinyl chloride, vinyl acetate, vinyl benzoate; for example, ethylene, propylene Ethylene olefins such as butylene, vinyl vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone, and vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether Such vinyl ethers of ether; vinyl monomer is used singly or two or more such.

Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, and examples thereof include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; examples are ethylene glycol diacrylate and ethylene. Glycol dimethacrylate, 1,
A carboxylic acid ester having two double bonds such as 3-butanediol dimethacrylate; a divinyl compound such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and a compound having three or more vinyl groups; alone or in a mixture. Used as.

The glass transition temperature (Tg) of the binder resin is
It is preferably 50 to 70 ° C. If the glass transition temperature is lower than the above range, the storability of the developer will be lowered, and if it is too high, the fixability will be poor.

The developer according to the present invention preferably has a maximum endothermic peak in a temperature range of 70 ° C. or higher and lower than 120 ° C. in an endothermic curve of a DSC chart by a differential thermal analysis analyzer (DSC). In order to have the maximum endothermic peak in such a temperature range, it is preferable to include a wax component in the toner particles.

Examples of the wax contained in the toner particles used in the present invention include low molecular weight polyethylene, low molecular weight polypropylene, polyolefin, polyolefin copolymer, microcrystalline wax, paraffin wax and Fischer-Tropsch wax. Waxes; oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene waxes; or block copolymers thereof; waxes having fatty acid ester as a main component such as carnauba wax and montanic acid ester wax; deoxidized carnauba wax Examples thereof include those obtained by partially or entirely deoxidizing fatty acid esters. Furthermore, saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkylcarboxylic acids having a longer-chain alkyl group; unsaturated fatty acids such as brassic acid, eleostearic acid, and vinalinaric acid; Saturated alcohols such as stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubayl alcohol, cetyl alcohol, melisyl alcohol, or long-chain alkyl alcohols having a longer-chain alkyl group; polyhydric alcohols such as sorbitol; linoleic acid Fatty acid amides such as amide, oleic acid amide, and lauric acid amide; methylenebisstearic acid amide,
Saturated fatty acid bisamides such as ethylenebiscabrylic acid amide, ethylenebislauric acid amide, hexamethylenebisstearic acid amide, ethylenebisoleic acid amide, hexamethylenebisoleic acid amide, N, N '
-Unsaturated fatty acid amides such as dioleoyl adipamide, N, N'-dioleyl sebacic amide; aromatic bisamides such as m-xylene bisstearic amide and N, N'-distearyl isophthalic amide Fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate, magnesium stearate (generally called metal soap); grafted onto aliphatic hydrocarbon wax using vinyl monomers such as styrene and acrylic acid And waxes; partially esterified products of fatty acids such as behenic acid monoglyceride and polyhydric alcohols; methyl ester compounds having a hydroxyl group obtained by hydrogenation of vegetable oils and the like.

In the present invention, the wax is preferably added in an amount of 0.5 to 20 parts by mass with respect to 100 parts by mass of the binder resin,
It is more preferably used in the range of 0.5 to 15 parts by mass.

The colorant contained in the toner particles used in the present invention includes carbon black, lamp black,
Iron Black, Ultramarine, Nigrosine Dye, Aniline Blue, Phthalocyanine Blue, Phthalocyanine Green, Hansa Yellow G, Rhodamine 6G, Calco Oil Blue, Chrome Yellow, Quinacridone, Benzidine Yellow, Rose Bengal, Triarylmethane Dye, Monoazo, Disazo Conventionally known dyes and pigments such as dyes and pigments may be used alone or in combination.

The developer of the present invention has a magnetic field of 79.6 kA / m.
It is preferred intensity of magnetization is a magnetic developer which is 10~40Am ² / kg in. The strength of magnetization of the developer is more preferably ²⁰ to 35 Am ² / kg.

The reason for defining the strength of magnetization in the magnetic field of 79.6 kA / m in the present invention is as follows. Usually, the strength of magnetization at magnetic saturation (saturation magnetization) is used as an amount representing the magnetic characteristics of a magnetic substance, but in the present invention, the magnetic developer in a magnetic field actually acting on the magnetic developer in the image forming apparatus. This is because the strength of magnetization of is important. When the magnetic developer is applied to the image forming apparatus, the magnetic field acting on the magnetic developer is commercially available in order not to increase the leakage of the magnetic field to the outside of the image forming apparatus or to keep the cost of the magnetic field generation source low. It is several tens to hundreds of tens of kA / m in many existing image forming apparatuses, and a magnetic field of 79.6 kA / m (1000 oersted) is a typical value of the magnetic field actually acting on the magnetic developer in the image forming apparatus. The strength of the magnetization was selected and defined at a magnetic field of 79.6 kA / m.

When the strength of the magnetization of the developer in the magnetic field of 79.6 kA / m is too small, the magnetic force makes it difficult to carry the developer, and the developer is uniformly developed on the carrier. It becomes impossible to carry the agent.
Further, when the developer is conveyed by magnetic force, the spikes of the one-component magnetic developer cannot be formed uniformly, so that the feedability of the conductive fine powder to the latent image carrier is lowered, and the transfer residue remains. The recoverability of toner particles is also reduced. When the strength of magnetization at a magnetic field of 79.6 kA / m is larger than the above range, the magnetic cohesiveness of the toner particles is increased, and the conductive fine powder is uniformly dispersed in the developer and a latent image carrier is formed. Is difficult to supply, and the effect of accelerating the charging of the image carrier or the effect of accelerating the recovery of toner, which is the effect of the present invention, is impaired.

To obtain such a magnetic developer, toner particles contain a magnetic material. In the present invention, the magnetic substance to be contained in the toner particles in order to use the developer as a magnetic developer includes magnetic iron oxides such as magnetite, maghemite and ferrite; iron; metals such as cobalt and nickel; or metals such as aluminum and cobalt;
Copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese,
Included are alloys of metals such as selenium, titanium, tungsten, vanadium and mixtures thereof.

As the magnetic characteristics of these magnetic materials, the saturation magnetization is 10 to 200 Am ² under a magnetic field of 795.8 kA / m.
/ Kg, a residual magnetization of 1 to 100 Am ² / kg, and a coercive force of 1 to 30 kA / m are preferably used. These magnetic materials are 20 to 2 with respect to 100 parts by mass of the binder resin.
It is used in 100 parts by mass. Among such magnetic materials, those mainly containing magnetite are particularly preferable.

In the present invention, the magnetic strength of the magnetic developer is a vibration type magnetic force meter VSMP-1-10 (manufactured by Toei Industry Co., Ltd.).
Using an external magnetic field of 79.6 kA / m at room temperature of 25 ° C.
Can be measured at. Also, the magnetic characteristics of the magnetic substance are
It can be measured with an external magnetic field of 796 kA / m at room temperature of 25 ° C.

Further, in the present invention, the developer has a mesh size of 1
It passes through a 49 μm sieve and cannot pass through a 74 μm aperture (mesh aperture 149 μm pass-mesh aperture 74 μm on), and the triboelectric charge amount for spherical iron powder having a particle size is 20 to 1 in absolute value.
It is preferably 00 mC / kg. When the triboelectric charge amount of the developer is smaller than the above range in absolute value, the transferability of the toner particles is decreased and the transfer residual toner particles are increased, so that the chargeability of the latent image carrier is apt to be decreased. Becomes
The load of collecting the transfer-residual toner particles becomes large, and collection failure is likely to occur. When the triboelectric charge amount of the developer is larger than the above-mentioned range in absolute value, the electrostatic cohesiveness of the developer is increased, and the conductive fine powder is uniformly dispersed in the developer and is dispersed on the image carrier. The supply becomes difficult, and the effect of accelerating the charging of the image carrier or the effect of accelerating the recovery of toner, which is the effect of the present invention, is impaired. In particular, in the case of a magnetic developer, since the developer also has magnetic cohesiveness, it is necessary to further suppress electrostatic cohesiveness, and the magnetic developer has an opening of 149 μm pass-opening 7
The absolute value of the triboelectric charge for spherical iron powder of 4 μm is 2
It is preferably 5 to 50 mC / kg.

The method for measuring the triboelectric charge amount of the developer in the present invention will be described in detail with reference to the drawings. FIG. 4 is an explanatory view of an apparatus for measuring the triboelectric charge amount of the developer. 23 ° C, relative humidity 60
% Environment, the developer whose frictional charge is to be measured and a spherical iron powder carrier having a particle size of 149 μm opening-74 μm on opening (for example, spherical iron powder D manufactured by Dowa Iron Powder Co., Ltd.
It is possible to use SP138) mass ratio of 5:
95 (for example, 0.5 g of developer and 9.5 iron powder carrier)
The mixture of g) is put into a polyethylene bottle having a volume of 50 to 100 ml and shaken 100 times. Next, a metal measuring container 2 provided with a screen 23 having an opening of 31 μm on the bottom.
About 0.5 g of the above mixture is put in 2 and the lid 24 made of metal is put. At this time, the weight of the entire measurement container 22 is weighed, and this is defined as W1 (g). Next, in the suction device 21 (at least the portion in contact with the measurement container 22 is an insulator), the suction port 27
Then, the pressure of the vacuum gauge 25 is set to 2450 Pa by sucking from the air and adjusting the air flow control valve 26. In this state, suction is sufficiently performed (for about 1 minute) to remove the toner by suction. The potential of the electrometer 29 at this time is V (volt). 28 here
Is a capacitor and has a capacity of C (μF). Also,
The weight of the entire measurement container after suction is weighed and is W2 (g).
The triboelectric charge amount of this developer is calculated by the following formula.

Triboelectric charge amount of developer (mC / kg) = C ×
V / (W1-W2) In the present invention, the developer preferably contains a charge control agent. Among the charge control agents, there are the following substances for controlling the developer to have a positive charge property.

Modified products of nigrosine and fatty acid metal salts and the like; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate,
And onium salts such as phosphonium salts and the like, lake pigments thereof, triphenylmethane dyes and lake pigments thereof (as a laker, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid) , Lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclohexyltin borate. Diorgano tin borates such as; guanidine compounds, imidazole compounds. These may be used alone or in combination of two or more. Among these, a triphenylmethane compound and a quaternary ammonium salt whose counter ion is not halogen are preferably used. Further, a homopolymer of the monomer represented by the general formula (4): a copolymer with a polymerizable monomer such as the above-mentioned styrene, acrylic acid ester and methacrylic acid ester can be used as a positive charge control agent. In this case, these charge control agents also function as (all or part of) the binder resin.

[0222]

[Chemical 7] [However, R ₁ , R ₂ and R ₃ are hydrogen atoms or carbon atoms 1
~ 4 saturated hydrocarbon groups. In the constitution of the present invention, the compound represented by the following general formula (5) is particularly preferable as the positive charge control agent.

[0223]

[Chemical 8] [In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ may be the same or different from each other, and are each a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkyl group. Represents an aryl group. R ⁷ , R ⁸ and R ⁹ , which may be the same or different, each represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. A ⁻ is a sulfate ion, a nitrate ion, a borate ion, a phosphate ion, a hydroxide ion, an organic sulfate ion, an organic sulfonate ion, an organic phosphate ion, a carboxylate ion, an organic borate ion,
It exhibits anions such as tetrafluoroborate. Further, the following substances may be mentioned as those for controlling the developer to be negatively charged. For example, organic metal complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

Further, an azo metal complex represented by the following general formula (6) is preferable.

[0225]

[Chemical 9] [In the formula, M represents a coordination center metal, and Sc, Ti, V,
Examples include Cr, Co, Ni, Mn, and Fe. Ar is an aryl group, and examples thereof include a phenyl group and a naphthyl group,
It may have a substituent. Examples of the substituent in this case include a nitro group, a halogen group, a carboxyl group, an anilide group, an alkyl group having 1 to 18 carbon atoms, and an alkoxy group. X, X ', Y and Y'are -O-, -CO-,-.
NH- or -NR- (R is an alkyl group having 1 to 4 carbon atoms)
Is. K represents hydrogen, sodium, potassium, ammonium, or aliphatic ammonium. In particular, Fe and Cr are preferable as the central metal, and halogen, an alkyl group and an anilide group are preferable as the substituent.
Hydrogen, ammonium and aliphatic ammonium are preferable as the counter ion.

Alternatively, the basic organic acid metal complex represented by the following general formula (7) also imparts a negative charging property and can be used in the present invention.

[0227]

[Chemical 10]

In the general formula (7), Fe, Al, Zn, Zr and Cr are particularly preferable as the central metal, halogen, an alkyl group and an anilide group are preferable as the substituent, and hydrogen, an alkali metal as the counter ion, Ammonium and aliphatic ammonium are preferred. Also, a mixture of complex salts having different counter ions is preferably used.

As a method of incorporating the charge control agent into the developer, there are a method of adding the charge control agent inside the toner particles and a method of adding it externally. The amount of these charge control agents used is determined according to the type of binder resin, the presence or absence of other additives, and the toner production method including the dispersion method, and is not uniquely limited. It is preferably 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the binder resin.
Used in the range of parts by mass.

In producing the toner particles according to the present invention, the constituent materials as described above are thoroughly mixed by a ball mill or other mixer, and then heated by a heating roll, kneader,
There is a method of obtaining toner particles by thoroughly kneading using a heat kneader such as an extruder, cooling and solidifying, and then performing surface treatment such as pulverization, classification, and toner shape adjustment if necessary.

As the treatment for adjusting the shape of the toner particles, a method of dispersing the toner particles obtained by a pulverizing method in water or an organic solution and heating or swelling, a heat treatment method of passing through a hot air stream, mechanical energy A mechanical impact method, etc., in which is applied and treated. As means for applying a mechanical impact force, for example, like a device such as a mechanofusion system manufactured by Hosokawa Micron Co., Ltd. or a hybridization system manufactured by Nara Machinery Co., Ltd., the toner particles are pressed against the inside of the casing by a centrifugal force by a blade rotating at high speed. , A method of applying a mechanical impact force to the toner particles by a force such as a compressive force and / or a frictional force.

In the present invention, in the case of carrying out the process of applying a mechanical shock, the atmospheric temperature at the time of the process is set to a temperature near the glass transition point Tg of the toner particles (Tg ± 30 ° C.) in order to prevent aggregation. It is preferable from the viewpoint of productivity. More preferably, the spheroidizing treatment of the toner particles by thermo-mechanical impact is carried out at a temperature in the range of the glass transition point Tg ± 20 ° C. of the toner during the treatment so that the conductive fine powder can be effectively worked. Especially effective for.

An example of a method of spheroidizing toner particles by repeatedly applying a thermo-mechanical impact force will be specifically described with reference to FIGS. 6 and 7.

FIG. 6 is a schematic diagram showing the structure of the toner particle spheroidizing apparatus used in the toner particle production examples 2 to 4 described later, and FIG. 7 shows the structure of the processing section 1 of FIG. It is a typical partial sectional view shown.

In this toner particle spheronization processing apparatus, the toner particles are pressed into the inside of the casing by centrifugal force by the blades rotating at high speed, and at least the thermomechanical impact force due to the compressive force and the frictional force is repeatedly applied to make the toner particles spherical Processing. As shown in FIG. 7, the processing unit I includes four rotating rotors 72a, 72b,
72c and 72d are installed. These rotating rotors 72a to 72d have a peripheral speed of the outermost edge of, for example, 100 m.
Per second by the electric motor 84
It is rotated by rotating 3. The rotation speed of the rotary rotors 72a to 72d at this time is, for example, 130 s.
^-1 . Further, the suction blower 85 (see FIG. 6) is operated to suck an air volume equal to or larger than the air flow rate generated by the rotation of the blades 79a to 79d integrally provided with the rotary rotors 72a to 72d. . Toner particles from the feeder 86 and hopper 82 together with air
The toner particles that have been sucked and introduced into the first cylindrical processing chamber 8 pass through the powder supply pipe 81 and the powder supply port 80.
It is introduced in the central part of 9a. The toner particles are spheronized by the blade 79a and the side wall 77 in the first cylindrical processing chamber 89a, and then the spheronized toner particles are provided in the first central portion of the guide plate 78a. It is introduced into the central portion of the second cylindrical processing chamber 89b through the powder discharge port 90a, and is further subjected to the spheroidizing process by the blade 79b and the side wall 77.

The toner particles spherically processed in the second cylindrical processing chamber 89b pass through the second powder discharge port 90b provided in the central portion of the guide plate 78b and the third cylindrical processing chamber 89c. Is introduced into the central part of the guide plate 78 and is subjected to a spheroidizing process by the blade 79c and the side wall 77, and further, the guide plate 78
The toner particles are introduced into the central portion of the fourth cylindrical processing chamber 89d through the third powder discharge port 90c provided in the central portion of c, and subjected to the spheroidizing treatment by the blade 79d and the side wall 77, and The powder is discharged from the discharge pipe 93 through the third powder discharge port 90d provided at the center of the guide plate 78d. The air carrying the toner particles passes through the first to fourth cylindrical processing chambers 89a to 89d and is carried out through the carry-out pipe 93, the cyclone 91, the bag filter 92, and the suction blower 8.
It is discharged to the outside of the system of the apparatus through 5.

The toner particles introduced into the cylindrical processing chambers 89a to 89d are momentarily mechanically impacted by the blades 79a to 79d, and further collide with the side wall 77 to generate a mechanical impact force. receive. Rotating rotors 72a to 72
blades 7 of a predetermined size respectively installed in d
Due to the rotation of 9a to 79d, convection that circulates from the central portion to the outer peripheral portion and from the outer peripheral portion to the central portion occurs in the space above the rotating rotor surface. The toner particles are stored in the cylindrical processing chambers 89a to 89d.
Remain inside and undergo spheronization. When the temperature of the surface of the toner particles rises to around the glass transition temperature of the binder resin forming the toner particles due to the heat generated by the mechanical impact force, the toner particles are spheroidized due to the thermomechanical impact force. It By passing through the cylindrical processing chambers 89a to 89d, the toner particles are continuously and efficiently sphericalized.

The degree of spheroidization of the toner particles can be adjusted by the residence time and temperature of the toner particles in the spheroidization processing section. Specifically, the rotational speed of the rotary rotor, the number of revolutions, the blade Height, width and number of sheets, clearance between blade outer circumference and side wall, suction air volume of suction blower,
It is also adjusted by the temperature of the toner particles when they are introduced into the spheroidizing unit, the temperature of the air carrying the toner particles, and the like.

As a batch type apparatus, it is also a preferable example to use a hybridization system commercialized by Nara Machinery Co., Ltd.

The shape of the toner particles obtained by the pulverization method can be controlled by selecting the toner particle constituent materials such as the binder resin and appropriately setting the conditions during the pulverization.
The productivity tends to decrease when the circularity of the toner particles is increased by the air flow type crusher, and it is preferable to set the condition for increasing the circularity of the toner particles by using the mechanical crusher.

In the present invention, in order to suppress the variation coefficient of the particle size distribution of toner particles to a low level, it is preferable to use a multi-division classifier in the classifying step from the viewpoint of productivity. Further, in order to reduce the ultrafine particles of the toner particles in the particle size range of 1.00 μm or more and less than 2.00 μm, it is preferable to use a mechanical crusher in the crushing process.

The toner according to the present invention can be produced by adding external additives to the toner particles obtained as described above, mixing them with a mixer, and passing them through a sieve if necessary.

Examples of the production apparatus used when producing the toner particles by the pulverization method include a mixer such as a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.); a super mixer (manufactured by Kawata Co., Ltd.); A Nauta mixer, a turbulizer, a cyclomix (manufactured by Hosokawa Micron); a spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.); a reedige mixer (manufactured by Matsubo) Co., Ltd.); Bus Co Kneader (Buss)
); TEM type extruder (made by Toshiba Machine Co., Ltd.); TEX
Biaxial kneader (manufactured by Japan Steel Works); PCM kneader (manufactured by Ikegai Iron Works Co., Ltd.); triple roll mill, mixing roll mill,
Kneader (manufactured by Inoue Seisakusho); Kneedex (manufactured by Mitsui Mining Co., Ltd.); MS type pressure kneader, Nider Ruder (manufactured by Moriyama Seisakusho); Banbury mixer (manufactured by Kobe Steel, Ltd.). Counter jet mill,
Micron Jet, Inomizer (manufactured by Hosokawa Micron); lDS type mill, PJM jet crusher (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); Cross Jet Mill (manufactured by Kurimoto Iron Works Co., Ltd.); Ulmax (manufactured by Soka Engineering Co., Ltd.); SK Jet O-mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.), and among these, it is more preferable to use a mechanical crusher such as Kryptron or Turbo Mill. As classifiers, class sealer, micron classifier, spedic classifier (manufactured by Seishin Enterprise Co., Ltd.); turbo classifier (manufactured by Nisshin Engineering Co., Ltd.); micron separator, turboplex (ATP), TSP separator (manufactured by Hosokawa Micron) Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); YM Micro Cut (manufactured by Yasukawa Shoji Co., Ltd.), among which a multi-division classifier such as Elbow Jet can be used. More preferable. As a sieving device used for sieving coarse particles, Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonator Sieve, Gyro Shifter (Tokuju Kosakusho Co., Ltd.); Vibrasonic System (Dalton Co., Ltd.); Soniclean (Shinto) Kogyo Co., Ltd.); Turbo Screener (Turbo Kogyo Co., Ltd.); Micro Shifter (Makino Sangyo Co., Ltd.);

The following additives are used as additives to the developer for the purpose of imparting various characteristics used in the present invention.

(1) As abrasives, metal oxides such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide and chromium oxide; nitrides such as silicon nitride; carbides such as silicon carbide; calcium sulfate;
Examples thereof include metal salts such as barium sulfate and calcium carbonate.

(2) Examples of the lubricant include fluorine-based resin powders such as polyvinylidene fluoride and polytetrafluoroethylene; silicone-based resin powders; fatty acid metal salts such as zinc stearate and calcium stearate.

These additives are used in an amount of 0.05 to 10 parts by mass, preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the toner particles. These additives may be used alone or in combination.

<Developing Device, Process Cartridge and Image Forming Method> Next, the developing device and the image forming method of the present invention which can suitably use the developer of the present invention will be described. The process cartridge of the present invention will also be described.

The developing device of the present invention comprises (I) a developer container for containing a developer, and (II) a developer for carrying the developer contained in the developer container and transporting the developer to a developing area. It has at least a carrier and (III) a developer layer thickness regulating member for regulating the layer thickness of the developer carried on the developer carrier.

In the image forming method of the present invention, image information is written as an electrostatic latent image on the charging surface of the latent image carrier charged in (I) the charging step of charging the latent image carrier and (II) the charging step. Latent image forming step, (III) developing the electrostatic latent image by using a developing device equipped with a developer carrying member for carrying the developer to a developing area facing the latent image carrying member. And a developing step of visualizing as a developer image, (I
V) a transfer step of transferring the developer image formed in the developing step onto a transfer material, and (V) a fixing step of fixing the developer image transferred onto the transfer material by a fixing means,
This is a method of repeating these steps to form an image.

Further, in the first aspect of the image forming method of the present invention, the above-mentioned charging step is a step of charging the latent image carrier by bringing the charging means into contact with the latent image carrier, and contacting the charging means with the latent image carrier. A contact charging method is used in which the image carrier is charged by applying a voltage in the state where the conductive particles of the developer are present in the contact area.

In a second aspect of the image forming method of the present invention, the latent image is formed after the developing step visualizes the electrostatic latent image and the developer image is transferred to the transfer material. This is a step of collecting the developer remaining on the carrier.

That is, the image forming method of the second aspect uses a so-called developing / cleaning method, in which the developing step also serves as a step of collecting the developer remaining on the image carrier after the toner image is transferred onto the transfer material. It was what I had.

The process cartridge of the present invention comprises a latent image carrier for carrying an electrostatic latent image, a charging means for charging the latent image carrier, and an electrostatic latent image formed on the image carrier. At least a developing means for forming a developer image by developing the image with the developer of the present invention, wherein the developing device and the latent image carrier are integrated with respect to the main body of the image forming device. It has a structure that is detachably attached.

According to a first aspect of the process cartridge of the present invention, the charging means is in contact with the latent image carrier, and a voltage is applied in the contact portion with the conductive fine particles contained in the developer interposed. The contact charging method is used in which the latent image carrier is charged by applying the voltage.

In a second aspect of the process cartridge of the present invention, the developing device visualizes an electrostatic latent image formed on the latent image bearing member as a developer image by developing the electrostatic latent image with a developer. At the same time, the developer remaining on the latent image carrier after the developer image is transferred to the transfer material is collected.

The developing means of the present invention comprises a developer carrying member arranged to face the latent image carrying member, and a developer layer regulating member for forming a thin developer layer on the developer carrying member. And a means for forming the toner image by transferring the developer from the developer layer on the developer carrier to the latent image carrier.

The developing means has at least a developer carrying member arranged to face the latent image carrying member and a developer layer regulating member for forming a thin developer layer on the developer carrying member. It is preferable.

The developing device, process cartridge and image forming method of the present invention will be described in detail below.

First, in the charging step in the image forming method of the present invention, a non-contact type charging device such as a corona charger as a charging means, or an image bearing member which is a member to be charged, a roller type (charging roller), A conductive charging member (contact charging member / contact charging device) such as a fur brush type, a magnetic brush type, or a blade type is brought into contact with the charging member (hereinafter, “contact charging member”)
(Hereinafter referred to as ") is applied by a predetermined charging bias to charge the surface of the body to be charged to a predetermined polarity and potential. In the present invention, it is preferable to use a contact charging device which has advantages such as low ozone and low electric power as compared with a non-contact type charging device such as a corona charger.

The transfer residual toner particles on the latent image carrier may be particles corresponding to the pattern of the image to be formed or particles due to so-called fog toner in the portion where the image is not formed. It is difficult to completely collect the transfer residual toner particles corresponding to the pattern of the image to be formed by developing and cleaning. If the toner particles are not collected sufficiently, the uncollected toner particles will appear in the next image as they are. Causes a pattern ghost. The transfer residual toner particles corresponding to such a pattern of the image can greatly improve the collectability in the development / cleaning by leveling the pattern of the transfer residual toner particles. For example, if the developing process is a contact developing process, a relative speed difference is provided between the moving speed of the developer carrying body carrying the developer and the moving speed of the latent image carrying body in contact with the developer carrying body. As a result, the pattern of the transfer residual toner particles can be leveled and at the same time the transfer residual toner particles can be efficiently collected. However, when a large amount of transfer residual toner particles remain on the image carrier, such as when the power supply is interrupted or paper is jammed during image formation, image exposure is performed using a pattern in which the transfer residual toner particles remain on the image carrier. A pattern ghost for preventing latent image formation is generated. On the other hand, when the contact charging device is used, the pattern of the transfer residual toner particles is leveled by the contact charging member, so that the transfer residual toner particles can be efficiently collected even in the non-contact developing process. Therefore, it is possible to prevent the occurrence of pattern ghost due to defective collection. Also, when a large amount of transfer residual toner particles remain on the latent image carrier,
The contact charging member temporarily blocks transfer residual toner particles, smoothes the pattern of the transfer residual toner particles, and gradually ejects the transfer residual toner particles onto the image carrier to prevent pattern ghosts due to latent image formation inhibition. You can When a large amount of transfer residual toner particles are blocked by the contact charging member, the chargeability of the latent image bearing member is deteriorated due to the contamination of the contact charging member. It is possible to reduce the deterioration of the uniform charging property to a range where there is no practical problem. From this point as well, it is preferable to use the contact charging device in the present invention.

In the present invention, it is preferable to provide a relative speed difference between the moving speed on the surface of the charging member and the moving speed on the surface of the latent image carrier. If a relative speed difference is provided between the moving speed on the surface of the charging member and the moving speed on the surface of the image carrier, the torque between the contact charging member and the latent image carrier is significantly increased. And, the surface of the latent image bearing member is significantly scraped, but by interposing the component of the developer in the contact portion between the contact charging member and the latent image bearing member, a lubricating effect (friction reducing effect) can be obtained. It is possible to provide a speed difference without causing a significant increase in torque or significant scraping.

Further, the component contained in the developer interposed at the contact portion between the latent image carrier and the charging member in contact with the latent image carrier is
It is preferable to contain at least the above-mentioned conductive fine powder. Further, the content ratio of the conductive fine powder to the whole developer component interposed in the contact portion is such that the conductive fine powder contained in the developer of the present invention (developing before being subjected to image formation of the present invention It is more preferable that the content ratio of the conductive fine powder) in the agent is higher. The component of the developer present in the contact portion contains at least conductive fine powder,
A conduction path between the latent image carrier and the contact charging member is secured,
It is possible to suppress the deterioration of the uniform charging property of the latent image carrier due to the adhesion or mixing of the transfer residual toner particles to the contact charging member. Further, since the content ratio of the conductive fine powder to the entire developer component interposed in the contact portion is higher than the content ratio of the conductive fine powder contained in the developer of the present invention, the contact charging member It is possible to more stably suppress the decrease in the uniform charging property of the latent image carrier due to the adhesion or mixing of the transfer residual toner particles. Further, by using the developer of the present invention, even when the relative moving speed between the contact charging member and the latent image carrier is relatively large in the charging section, excellent lubricity is exhibited. 1.00 μm or more 2 By supplying the electrically conductive fine powder containing a large amount of particles in the particle size range of less than 0.000 μm to the charging unit, it is possible to suppress the abrasion and damage of the contact charging member and the latent image carrier.

The charging bias applied to the contact charging member can obtain a good chargeability of the latent image carrier even if only the DC voltage is applied. However, the DC voltage is superposed with the alternating voltage (AC voltage). May be As a waveform of such an alternating voltage, a sine wave, a rectangular wave, a triangular wave, or the like can be appropriately used. Further, the alternating voltage may be a voltage of a pulse wave formed by periodically turning on / off the DC power supply. Thus, as the alternating voltage, a bias having a waveform whose voltage value changes periodically can be used.

In the present invention, the charging bias applied to the contact charging member is preferably applied within a range where discharge products are not generated. That is, it is preferably lower than the discharge start voltage between the contact charging member and the body to be charged (latent image carrier). Further, a charging method in which the direct injection charging mechanism is dominant is preferable.

In the developing / cleaning method, the insulating transfer residual toner particles remaining on the latent image bearing member come into contact with the contact charging member to be attached or mixed, so that the charging property of the latent image bearing member is lowered. In the case of the charging method in which the discharge charging mechanism is dominant, the toner layer attached to the surface of the contact charging member becomes a resistance that inhibits the discharge voltage, so that the chargeability of the latent image carrier rapidly decreases. On the other hand, in the case of the charging method in which the direct injection charging mechanism is dominant, the transfer residual toner particles adhered to or mixed in the contact charging member decrease the contact probability between the surface of the contact charging member and the body to be charged. The uniform charging property of the member to be charged (latent image bearing member) is lowered, which lowers the contrast and uniformity of the electrostatic latent image, which lowers the image density or increases the fog. Based on the mechanism of charge reduction of the discharge charging mechanism and the direct injection charging mechanism, a latent image carrier is obtained by interposing conductive fine powder at least in the contact portion between the latent image carrier and the charging member in contact with the image carrier. The effect of preventing the deterioration of the charging property and the effect of accelerating the charging are more remarkable in the direct injection charging mechanism, and it is preferable to apply the developer of the present invention to the direct injection charging mechanism. That is, in the discharge charging mechanism, at least the conductive fine powder is interposed in the contact portion between the latent image carrier and the charging member that contacts the latent image carrier, so that the transfer residual toner particles adhere to or mix with the contact charging member. In order to prevent the formed toner layer from becoming a resistance that hinders the discharge voltage from the charging member to the latent image carrier, the contact portion between the latent image carrier and the charging member in contact with the latent image carrier and the vicinity thereof. It is necessary to increase the content ratio of the conductive fine powder with respect to the entire developer component interposed in the charged area of. Therefore,
When a large amount of transfer residual toner particles adheres to or mixes with the contact charging member, the amount of transfer residual toner particles adhered or mixed is adjusted so that the toner layer adhered to or mixed with the contact charging member does not become a resistance that hinders the discharge voltage. To limit
More transfer residual toner particles have to be discharged onto the latent image carrier, which tends to hinder latent image formation. On the other hand, in the direct injection charging mechanism, the conductive fine powder is interposed at least in the contact portion between the latent image carrier and the charging member in contact with the latent image carrier, so that the conductive fine powder can be easily introduced. A contact point between the contact charging member and the member to be charged can be secured, and the transfer residual toner particles adhering to or mixed with the contact charging member are prevented from lowering the contact probability between the contact charging member and the member to be charged, thereby carrying a latent image. It is possible to suppress a decrease in the chargeability of the body.

In particular, when a relative speed difference is provided between the moving speed on the surface of the contact charging member and the moving speed on the surface of the latent image carrier, it is present at the contact portion between the latent image carrier and the contact charging member. Since the amount of the entire developer component is limited by the friction between the contact charging member and the latent image carrier, the inhibition of charging of the latent image carrier is more reliably suppressed, and the contact charging member and the latent image carrier are brought into contact with each other. By significantly increasing the opportunity for the conductive fine powder to come into contact with the latent image bearing member in the part, it is possible to obtain higher contact between the contact charging member and the latent image bearing member. Direct injection charging to the latent image carrier can be further promoted. On the other hand, in the discharge charging, since the latent image carrier and the contact charging member are not in contact with each other but the contact charging member is not in contact with each other and discharging is performed in a region having a minute gap, The effect of suppressing the charging inhibition due to the limitation of the total amount of the developer components intervening in the toner cannot be expected.

From this viewpoint as well, in the present invention, it is preferable to use the charging method in which the direct injection charging mechanism is dominant, and the direct injection charging mechanism not relying on the discharge charging mechanism is dominant.

In order to realize the charging method, it is preferable that the charging bias applied to the contact charging member is lower than the discharge start voltage between the contact charging member and the member to be charged (latent image carrier).

As a structure for providing a relative speed difference between the moving speed on the surface of the contact charging member and the moving speed on the surface of the latent image carrier, the speed difference is provided by rotationally driving the contact charging member. preferable.

The moving direction on the surface of the charging member and the moving direction on the surface of the latent image carrier are preferably opposite to each other. That is, it is preferable that the charging member and the latent image carrier move in opposite directions. The contact charging member and the latent image carrier are moved in opposite directions to enhance the effect of temporarily collecting and leveling the transfer residual toner particles on the latent image carrier carried to the contact charging member on the contact charging member. It is preferable. For example, it is desirable that the contact charging member is rotationally driven, and that the rotation direction thereof is opposite to the moving direction of the surface of the latent image carrier.
That is, the transfer residual toner particles on the image bearing member are reversely rotated to be temporarily separated from the latent image bearing member and charged, whereby direct injection charging is predominantly performed and inhibition of latent image formation is suppressed. It is possible. Furthermore, by enhancing the effect of leveling the pattern of the transfer residual toner particles, it becomes possible to improve the collectability of the transfer residual toner particles and more reliably prevent the occurrence of pattern ghosts due to defective recovery.

It is also possible to move the charging member in the same direction as the moving direction of the surface of the latent image carrier to give a relative speed difference. However, since the charging property of the direct injection charging depends on the ratio of the moving speed of the latent image carrier to the relative moving speed of the charging member to the moving distance of the latent image carrier, the same relative moving speed ratio as in the opposite direction is obtained. In addition, since the moving speed of the charging member in the forward direction is higher than that in the reverse direction, moving the charging member in the reverse direction is advantageous in terms of moving speed. Also, in terms of the effect of leveling the pattern of the transfer residual toner particles, it is advantageous to move the charging member in the direction opposite to the moving direction of the surface of the latent image carrier.

In the present invention, the ratio of the moving speed of the latent image carrier to the moving speed of the charging member (relative moving speed ratio) is 10
Is preferably 500%, more preferably 20% to 400%. If the relative moving speed ratio is too smaller than the above range, it is not possible to sufficiently increase the contact probability between the contact charging member and the latent image bearing member, and the chargeability of the latent image bearing member due to direct injection charging is insufficient. Can be difficult to maintain. Further, the amount of the conductive fine powder present in the contact portion between the latent image carrier and the contact charging member is restricted by the friction between the contact charging member and the latent image carrier, thereby inhibiting the charging of the latent image carrier. In some cases, the effect of suppressing the above phenomenon and the effect of leveling the pattern of the transfer residual toner particles and enhancing the collectability of the developer in the cleaning with development may not be sufficiently obtained. If the relative movement speed ratio is too large than the above range,
Since the moving speed of the charging member is increased, the developer component carried in the contact portion between the latent image carrier and the contact charging member scatters easily to cause contamination in the apparatus, and the latent image carrier Also, the contact charging member is apt to be worn or scratched, which tends to shorten the service life.

When the moving speed of the charging member is 0 (when the charging member is stationary), the contact point of the charging member with the latent image carrier is a fixed point, so the image carrier of the charging member is fixed. Wear or deterioration of the contact portion to the image carrier tends to occur, and the effect of suppressing charge inhibition of the image bearing member and the effect of leveling the pattern of the transfer residual toner particles and enhancing the recoverability of the developer in the development / cleaning are likely to decrease. Absent.

The relative moving speed ratio indicating the relative speed difference described here can be expressed by the following equation. Here, the moving speed of the charging member is Vc, the moving speed of the image carrier is Vp, and the moving speed of the charging member is a latent image when the surface of the charging member moves in the same direction as the surface of the latent image carrier at the contact portion. It has the same sign as the moving speed of the carrier.

Relative moving speed ratio (%) = | [(Vc-V
p) / Vp] × 100 | In the present invention, the transfer residual toner particles on the latent image carrier are temporarily collected by the charging member, and the conductive fine powder is carried on the charging member to form a latent image carrier. In order to predominantly perform direct injection charging by providing a contact portion with the charging member, the contact charging member preferably has elasticity. Further, it is preferable that the contact charging member has elasticity also in order to improve the collectability of the transfer residual toner particles by leveling the pattern of the transfer residual toner particles by the contact charging member.

Further, in the present invention, the charging member is preferably conductive in order to charge the latent image carrier by applying a voltage to the charging member. Therefore, the charging member should be an elastic conductive roller, a magnetic brush contact charging member having a magnetic brush portion in which magnetic particles are magnetically restrained, and the magnetic brush portion being in contact with an object to be charged, or a brush made of conductive fibers. Is preferred. From the viewpoint that the structure of the charging member can be simplified, the charging member is more preferably an elastic conductive roller or a brush roller having conductivity, and a developer component that adheres to or mixes with the charging member (for example, transfer residual toner particles or conductive particles). It is particularly preferable that the charging member is an elastic conductive roller because it is easy to stably and stably hold the fine powder).

If the hardness of the elastic conductive roller as the roller member is too low, the shape is not stable, so that the contact property with the member to be charged is deteriorated, and further, the contact portion between the charging member and the latent image carrier is The intervening conductive fine powder scrapes or damages the surface layer of the elastic conductive roller, so that stable chargeability of the latent image carrier cannot be obtained. Further, if the hardness is too high, not only the charging contact portion cannot be secured between the charged body and the charged body (latent image carrier) but also the micro contact property to the surface of the charged body is deteriorated. Stable chargeability cannot be obtained. Furthermore, the effect of leveling the pattern of the transfer residual toner particles is reduced, and the collectability of the transfer residual toner particles cannot be improved. Therefore, if the contact pressure of the elastic conductive port roller with respect to the latent image bearing member is increased so that the charging contact portion and the leveling effect are sufficiently obtained, the contact charging member or the latent image bearing member may be scraped or scratched. It will be easier. From these viewpoints, the Asker C hardness of the elastic conductive roller as the roller member is preferably in the range of 20 to 50, more preferably in the range of 25 to 50, and further preferably in the range of 25 to 40. . Here, the Asker C hardness is a hardness measured using a spring-type hardness meter Asker C (manufactured by Kobunshi Keiki Co., Ltd.) defined by JlSK6301. In the present invention, the load is set to 9.8 N and the measurement is performed in the form of a roller.

In the present invention, the surface of the roller member as the contact charging member preferably has minute cells or irregularities so as to stably hold the conductive fine particles.

Further, the conductive elastic roller has elasticity to obtain a sufficient contact state with the latent image carrier, and at the same time, functions as an electrode having a resistance low enough to charge the moving latent image carrier. This is very important. On the other hand, it is necessary to prevent voltage leakage when a defective portion such as a pinhole exists on the latent image carrier. When a latent image carrier such as an electrophotographic photoreceptor is used as the member to be charged, the resistance of the conductive elastic roller is 1 in order to obtain sufficient charging property and leak resistance.
It is preferably 0 ³ to 10 ⁸ Ω · cm, and 10 ⁴ to
More preferably, it is 10 ⁷ Ω · cm. The resistance of the conductive elastic roller is measured by applying 100 V between the core metal and the aluminum drum in a state where the roller is pressure-bonded to a cylindrical aluminum drum having a diameter of 30 mm so that a contact pressure of 49 N / m is applied to the roller. can do.

For example, the conductive elastic roller is manufactured by forming a medium resistance layer of rubber or foam as a flexible member on a core metal. The medium resistance layer is formulated with resin (eg urethane), conductive particles (eg carbon black), sulphating agent, foaming agent, etc., formed into a roller shape on the cored bar, and then cut and polished the surface if necessary. Then, the shape is adjusted and a conductive elastic roller can be manufactured.

The material of the conductive elastic roller is not limited to the elastic foam, and the material of the elastic body is ethylene-propylene-diene polyethylene (EPD).
M), urethane, butadiene acrylonitrile rubber (N
BR), a rubber material such as silicone rubber or isoprene rubber, and a conductive material such as carbon black or a metal oxide may be dispersed for resistance adjustment.
The thing which made these foam is mentioned. It is also possible to adjust the resistance by using an ion conductive material without dispersing the conductive material or in combination with the conductive material.

The conductive elastic roller is disposed in pressure contact with the latent image carrier, which is the member to be charged, with a predetermined pressing force against the elasticity, and the conductive elastic roller contacts the latent image carrier. A charging contact portion is formed. The width of the charging contact portion is not particularly limited, but it is preferably 1 mm or more, more preferably 2 mm or more in order to obtain stable and dense adhesion between the conductive elastic roller and the latent image carrier. preferable.

The charging member used in the charging step of the present invention may be one that charges the image carrier by applying a voltage to a brush (brush member) made of conductive fibers. As the charging brush as such a contact charging member, a brush whose resistance is adjusted by dispersing a conductive material in commonly used fibers can be used. As the fiber, a generally known fiber can be used, and examples thereof include nylon, acrylic, rayon, polycarbonate and polyester. As the conductive material, a generally known material can be used, for example, nickel,
Examples thereof include conductive metals such as iron, aluminum, gold and silver, conductive metal oxides such as iron oxide, zinc oxide, tin oxide, antimony oxide and titanium oxide, and conductive powder such as carbon black. If necessary, these conductive materials may be surface-treated for the purpose of making them hydrophobic and adjusting their resistance. Upon use, the conductive material is appropriately selected and used in consideration of dispersibility with fibers and productivity.

The charging brush as the contact charging member is classified into a fixed type and a rotatable roll type. Examples of the roll-shaped charging brush include a roll brush in which a tape made of a pile of conductive fibers is spirally wound around a metal cored bar. The conductive fiber has a fiber thickness of 1 to 20 denier (fiber diameter of about 10 to 500 μm),
The length of the fibers of the brush is preferably 1 to 15 mm, and the brush density is preferably 10,000 to 300,000 per square inch (1.5 × 10 ^{7 to} 4.5 × 10 ⁸ per square meter).

As the charging brush, one having a brush density as high as possible is preferably used, and it is also preferable to make one fiber from several to several hundred fine fibers. For example, it is possible to bundle 50 fine fibers of 300 denier, such as 300 denier / 50 filaments, and to implant them as one fiber. However, in the present invention, what determines the charging point of the direct injection charging mainly depends on the interposition density of the conductive fine powder in the charging contact portion between the charging member and the latent image carrier and in the vicinity thereof. Therefore, the selection range of the charging member is widened.

The resistance value of the charging brush is preferably 10 ³ to 10 ⁸ Ω · cm in order to obtain sufficient chargeability and leak resistance of the image bearing member, as in the case of the elastic conductive roller. More preferably, it is 10 ⁴ to 10 ⁷ Ω · cm.

As the material of the charging brush, conductive rayon fibers REC-B and REC- manufactured by Unitika Ltd. are used.
C, REC-M1, REC-M10, and Toray Industries, Inc.
SA-7 made by Nippon Silkworm Co., Ltd., Thunderon made by Japan Silkworm Co., Ltd., Bertron made by Kanebo, Cracabo made by Kuraray Co., Ltd., carbon dispersed in rayon, Mitsubishi Rayon Co., Ltd.
There are manufactured products such as locals, but in terms of environmental stability REC-
It is particularly preferable to use B, REC-C, REC-M1 or REC-M10.

The flexibility of the contact charging member increases the chances that the conductive fine powder will contact the latent image carrier at the contact portion between the contact charging member and the latent image carrier, which is high. It is preferable in that the contact property can be obtained and the direct injection charging property is improved. That is, the contact charging member comes into close contact with the latent image carrier through the conductive fine powder, and the conductive fine powder present at the contact portion between the contact charging member and the latent image carrier makes a gap on the surface of the latent image carrier. By rubbing without rubbing, the charging of the latent image bearing member by the contact charging member is dominated by stable and safe direct injection charging through conductive fine powder, which does not use the discharge phenomenon.
Therefore, by applying the direct injection charging through the conductive fine powder, a high charging efficiency which could not be obtained by the conventional roller charging by the discharge charging can be obtained, which is almost equal to the voltage applied to the contact charging member. An electric potential can be applied to the latent image carrier. Further, since the contact charging member has flexibility, the effect of temporarily blocking transfer residual toner particles when a large amount of transfer residual toner particles is supplied to the contact charging member and transfer residual toner particles By increasing the effect of leveling the pattern, it is possible to more reliably prevent the occurrence of image defects due to latent image formation inhibition and defective collection of transfer residual toner particles.

If the amount of the conductive fine powder present in the contact portion between the latent image carrier and the contact charging member is too small, the lubricating effect of the conductive fine powder cannot be sufficiently obtained, and the latent image carrier and the contact charging member are not obtained. Therefore, it becomes difficult to rotationally drive the contact charging member with respect to the latent image carrier with a speed difference. That is, if the amount of the conductive fine powder present is small, the driving torque becomes excessively large, and if it is forcibly rotated, the surfaces of the contact charging member and the latent image carrier are easily scraped. In addition, the effect of increasing contact opportunities due to the conductive fine powder may not be sufficiently obtained, so that good charging performance of the latent image carrier may not be obtained. On the other hand, when the amount of the conductive fine powder present in the contact portion is too large, the amount of the conductive fine powder falling from the contact charging member remarkably increases, which causes a latent image formation obstruction such as shading of image exposure and causes an image formation. Is likely to be adversely affected.

According to the studies made by the present inventors, the amount of the conductive fine powder present in the contact portion between the latent image carrier and the contact charging member is preferably 10 ³ particles / mm ² or more, and 10
It is more preferable that the number is ⁴ pieces / mm ² or more. When the intervening amount of the conductive fine powder is 10 ³ particles / mm ² or more, the driving torque does not become excessive and the lubricating effect of the conductive fine powder can be sufficiently obtained. 10 ³ intervening amount /
If it is significantly lower than mm ² , the desired effect of increasing the chance of contact cannot be obtained sufficiently, and the chargeability of the image bearing member tends to decrease.

When the direct injection charging method is applied as the uniform charging of the latent image carrier in the development / cleaning image formation, the latent image carrier is charged by adhering or mixing transfer residual toner particles to the charging member. There is a concern that sex will decline. To prevent the transfer residual toner particles from adhering to and mixing with the charging member, or overcome the charge inhibition of the latent image carrier due to the adhesion or mixing of the transfer residual toner particles to the charging member, and to perform good direct injection charging. , The amount of conductive fine powder present in the contact portion between the image carrier and the contact charging member is 10 ⁴ particles / m 2.
It is preferably m ² or more. Intervening amount is 10 ⁴ pieces / m
If it is significantly lower than m ² , the chargeability of the latent image bearing member is likely to decrease when there are many transfer residual toner particles.

The proper range of the amount of the conductive fine powder present on the latent image carrier in the charging step is to determine the density of the conductive fine powder by coating the latent image carrier on the latent image carrier. It is also determined depending on whether the effect of uniform charging property of is obtained.

Needless to say, at the time of charging the latent image carrier, it is necessary to make contact charging more uniform than at least the recording resolution. However, as in the graph showing the visual characteristics of the human eye in FIG. 3, when the spatial frequency is 10 cycles / mm or more, the number of identification gradations on the image approaches 1 without limit, that is, it becomes impossible to identify density unevenness. If this characteristic is positively utilized, when conductive fine powder is deposited on the latent image carrier, at least 10 cycles on the image carrier will be obtained.
The conductive fine powder may be present at a density of s / mm or more, and direct injection charging may be performed. Even if a microscopic charging failure occurs on the latent image carrier in the absence of conductive fine powder, the density unevenness on the image caused by the charging failure is in the spatial frequency range that exceeds human visual characteristics. Since it occurs, there is no problem on the image.

When the coating density of the conductive fine powder on the latent image carrier is changed, whether or not charging failure as density unevenness is recognized on the image is determined by applying the conductive fine powder even if it is a little. If it is done (for example, 10 pieces / mm ² ), the effect of suppressing the uneven charging is recognized, but it is still insufficient in terms of whether the uneven density on the image is acceptable to humans. However, the coating amount was 10 ² pieces / m
When it is m ² or more, a desirable result can be rapidly obtained in the objective evaluation of the image. Furthermore, the coating amount is 10 ³
By increasing the number of particles / mm ² or more, there is no problem on the image due to the charging failure.

The charging by the direct injection charging method is fundamentally different from the discharge charging method, and the charging is performed by surely contacting the charging member with the member to be charged. Even if it is applied excessively on the body, there are always parts that cannot be contacted. However, by applying the conductive fine powder that positively utilizes the human visual characteristics of the present invention, this problem is practically solved.

The upper limit of the amount of the conductive fine powder present on the latent image carrier is until one layer of the conductive fine powder is uniformly coated on the latent image carrier. Even if it is done, the effect does not improve, and conversely, the exposure light source may be blocked by discharging excess conductive fine powder after the charging step
There is an adverse effect such as scattering.

The upper limit of the coating density cannot be generally stated because it depends on the particle size of the conductive fine powder and the holding property of the conductive fine powder of the contact charging member. The upper limit can be the amount by which one layer of the fine powder is uniformly coated on the image bearing member.

The amount of the conductive fine powder present on the latent image carrier depends on the particle size of the conductive fine powder and the like, but is 5 × 10 ⁵ particles / particle.
When it exceeds mm ² , the conductive fine powder tends to drop off from the latent image carrier remarkably, contaminating the inside of the image forming apparatus and carrying the latent image regardless of the light transmittance of the conductive fine powder itself. Insufficient exposure to the body may occur. When the existing amount is 5 × 10 ⁵ particles / mm ² or less, the amount of particles that fall off can be suppressed to be low, contamination in the apparatus due to scattering of conductive fine powder can be reduced, and inhibition of exposure can be improved.

Further, in the developing / cleaning step,
An experiment was also conducted on the effect of improving the collectability of transfer residual toner particles due to the amount of the conductive fine powder present on the latent image bearing member. When the existing amount exceeds 10 ² / mm ² , the recovery of the transfer residual toner particles is obviously improved as compared with the case where the conductive fine powder does not exist on the latent image carrier, and An image was obtained by developing and cleaning without image defects to the extent that one layer of conductive fine powder was uniformly applied. As in the case of the amount of conductive fine powder present on the latent image carrier after transfer and before charging, when the amount of conductive fine powder present exceeds 5 × 10 ⁵ particles / mm ² , conductivity gradually increases. It was observed that the fine powder was remarkably dropped from the latent image bearing member, affecting the latent image formation and increasing the fog.

That is, the intervening amount of conductive fine powder at the contact portion between the latent image carrier and the contact charging member is 10 ³ particles / mm.
² or more, and the amount of conductive fine powder present on the latent image carrier is set to 10 ² particles / mm ² or more and 5 × 10 ⁵ particles / mm ²
The chargeability of the latent image bearing member is good, the collectability of transfer residual toner particles is good, and an image having no image defects due to contamination in the apparatus or exposure inhibition is formed by setting so as not to greatly exceed Is preferred for. The amount of conductive fine powder present at the contact portion between the latent image carrier and the contact charging member is 10 ^4.
It is more preferable to set the number of pieces / mm ² or more.

The relationship between the amount of conductive fine powder present in the contact portion between the latent image carrier and the contact charging member and the amount of conductive fine powder present on the latent image carrier in the latent image forming step is as follows. Amount of conductive fine powder supplied to the contact portion between the carrier and the contact charging member,
Adhesion of conductive fine powder to latent image carrier and contact charging member, retention of contact charging member to conductive fine powder,
Since there are factors such as the ability of the latent image carrier to hold the conductive fine powder, it cannot be unconditionally determined. Experimentally, the presence of particles that have fallen off on the latent image carrier when the amount of conductive fine powder present in the contact portion between the latent image carrier and the contact charging member is in the range of 10 ³ to 10 ⁶ particles / mm ^2. The amount (the amount of conductive fine powder present on the latent image carrier in the latent image forming step) is 10 ² to
It was 10 ⁵ pieces / mm ² .

A method of measuring the amount of conductive fine powder present in the charging contact portion and the amount of conductive fine powder present on the latent image carrier in the latent image forming step will be described. It is preferable to directly measure the amount of the conductive fine powder present in the charging portion at the contact surface portion of the contact charging member and the latent image carrier, but the moving direction of the surface of the contact charging member forming the contact portion is the latent image carrier. When the direction of movement of the surface of the body is opposite to that of the particles, most of the particles existing on the latent image bearing member before coming into contact with the contact charging member are peeled off by the contacting charging member while moving in the opposite direction. In the present invention, the amount of particles on the surface of the contact charging member immediately before reaching the contact surface portion is used as the interposition amount. Specifically, the rotation of the image carrier and the elastic conductive roller is stopped without applying the charging bias, and the surfaces of the latent image carrier and the elastic conductive roller are covered with a video microscope (OVM1 made by OLYMPUS).
000N) and digital still recorder (DELTIS
It is photographed by SR-3100). As for the elastic conductive roller, the elastic conductive roller is brought into contact with the slide glass under the same conditions as the contact with the image carrier, and the contact surface is made from the rear surface of the slide glass with a video microscope at 10 positions with an objective lens of 1000 times. I took the picture above. In order to separate individual particles from the obtained digital image, binarization processing is performed with a certain threshold value, and the number of areas where particles are present is measured using desired image processing software. Further, the amount of the latent image bearing member present is also measured by photographing the image bearing member with a similar video microscope and performing the same processing.

The amount of conductive fine powder present on the latent image carrier is
The latent image bearing member after transfer and before charging and after charging and before developing is photographed by the same means as above and measured using image processing software.

[0305] In the present invention, the volume resistivity of the outermost surface layer is ^{1 × 10 9 ~1 × 10 1} 4 Ω · cm of the latent image carrier, and more preferably is ^{1 × 10 10 ~1 × 10 14} Ω · cm This is preferable because a better chargeability of the latent image bearing member can be provided. In the charging method that directly injects electric charges, it is possible to transfer the electric charges more efficiently by lowering the resistance on the side of the body to be charged. For this purpose, the volume resistance value of the outermost surface layer is preferably 1 × 10 ¹⁴ Ω · cm or less. On the other hand, in order to hold the electrostatic latent image as the latent image carrier for a certain period of time, the volume resistance value of the outermost surface layer is preferably 1 × 10 ⁹ Ω · cm or more. In order to retain an electrostatic latent image without disturbing even a minute latent image even in a high humidity environment, the resistance value is 1 × 10 ¹⁰ Ω.
It is preferably at least cm.

Further, the latent image carrier is an electrophotographic photosensitive member, and the outermost surface layer of the electrophotographic photosensitive member has a volume resistance of 1 × 10.
^{The range of 9} to 1 × 10 ¹⁴ Ω · cm is more preferable because the image carrier can be sufficiently charged even in an apparatus having a high process speed.

Also, the latent image carrier is amorphous selenium,
A photosensitive drum or photosensitive belt having a photoconductive insulating material layer such as CdS, ZnO ₂ , amorphous silicon or an organic photosensitive material is preferable, and a photosensitive body having an amorphous silicon photosensitive layer or an organic photosensitive layer is particularly preferably used. Be done.

The organic photosensitive layer may be a single layer type in which the photosensitive layer contains a charge generating substance and a substance having a charge transporting property in the same layer, or a functional separation type photosensitive layer having a charge transporting layer and a charge generating layer. It may be. A laminated photosensitive layer having a structure in which a charge generation layer and then a charge transport layer are laminated in this order on a conductive substrate is one of preferred examples.

By adjusting the surface resistance of the latent image carrier,
Further, the latent image carrier can be charged more stably and uniformly.

It is also preferable to provide a charge injection layer on the surface of the electrophotographic photoreceptor for the purpose of more efficiently or promoting charge injection by adjusting the surface resistance of the latent image carrier. The charge injection layer preferably has a form in which conductive fine particles are dispersed in a resin.

The form of providing the charge injection layer is, for example, (i) providing a charge injection layer on an inorganic photoreceptor such as selenium or amorphous silicon or a single layer type organic photoreceptor (ii) function-separated type organic photoreceptor As a charge transport layer of the body, a layer having a surface layer having a charge transport agent and a resin also functions as a charge injection layer (for example, as the charge transport layer, a charge transport agent and conductive particles are dispersed in a resin, Alternatively, the charge transport layer itself or the presence state thereof may allow the charge transport layer to have a function as a charge injection layer. (Iii) A charge injection layer may be provided as an outermost surface layer on the function-separated type organic photoreceptor. It is important that the volume resistance of the outermost surface layer is within the preferable range.

The charge injection layer is made of, for example, a layer of an inorganic material such as a metal vapor deposition film or a conductive powder-dispersed resin layer in which conductive particles are dispersed in a binder resin. The powder dispersion resin layer is a dipping coating method,
It is formed by applying an appropriate coating method such as a spray coating method, a roll coating method, and a beam coating method.

Further, it may be constituted by mixing or copolymerizing an insulating binder with a resin having a high light-transmitting ionic conductivity, or may be constituted by a single resin having a medium resistance and a photoconductivity.

Among these, it is preferable that the outermost surface layer of the latent image carrier is a resin layer in which conductive fine particles made of at least a metal oxide (hereinafter referred to as “oxide conductive fine particles”) are dispersed. That is, by forming the outermost surface layer of the image bearing member in such a structure, the resistance of the surface of the electrophotographic photosensitive member can be lowered to more efficiently transfer charges, and the surface resistance can be lowered. Is preferable because it is possible to suppress blurring or flow of the latent image due to diffusion of the latent image charge while the image carrier holds the electrostatic latent image.

In the case of the resin layer in which the conductive oxide particles are dispersed, the particle size of the conductive oxide particles is preferably smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles. . Therefore, the particle diameter of the dispersed conductive oxide fine particles is preferably 0.5 μm or less. The content of the oxide conductive fine particles is preferably 2 to 90% by mass, and more preferably 5 to 70% by mass, based on the total mass of the outermost layer. When the content of the oxide conductive fine particles is too small than the above range, it becomes difficult to obtain a desired volume resistance value. Further, when the content is more than the above range,
Since the film strength is reduced, the charge injection layer is easily scraped off, the life of the photoconductor tends to be shortened, and the resistance becomes too low, causing an image defect due to the flow of a latent image potential. It will be easier.

The layer thickness of the charge injection layer is 0.1-10.
The thickness is preferably 5 μm or less, more preferably 5 μm or less from the viewpoint of obtaining the sharpness of the latent image outline, and more preferably 1 μm or more from the viewpoint of the durability of the charge injection layer.

The binder of the charge injection layer may be the same as the binder of the lower layer, but in this case, the coating surface of the lower layer (for example, the charge transport layer) may be disturbed during the coating of the charge injection layer. Therefore, it is necessary to particularly select the forming method.

The method for measuring the volume resistance value of the outermost surface layer of the latent image bearing member in the present invention is the same as the outermost surface layer of the image bearing member on the polyethylene terephthalate (PET) film on the surface of which gold is vapor-deposited. A layer made of a composition was prepared, and a volume resistance measuring device (41 manufactured by Hewlett-Packard Co.) was used.
40BpAMASTER), temperature 23 ° C, humidity 65%
In this environment, a voltage of 100V is applied for measurement.

Further, in the present invention, it is preferable to impart releasability to the surface of the latent image carrier, and the contact angle of the surface of the latent image carrier to water is preferably 85 degrees or more.
More preferably, the contact angle of water on the surface of the latent image carrier is 9
It is 0 degrees or more.

The fact that the surface of the latent image carrier has a high contact angle means that the surface of the latent image carrier has a high releasability from the toner particles. Due to this effect, the recovery efficiency of the developer is improved in the developing / cleaning step. Also,
Since the amount of transfer residual toner particles can be remarkably reduced, it is also possible to suppress a decrease in chargeability of the latent image carrier due to transfer residual toner particles.

As means for imparting releasability to the surface of the latent image bearing member, for example, the resin itself constituting the film has a low surface energy. Add additives that impart water repellency and lipophilicity. A material having high releasability is made into a powder and dispersed. Is mentioned.

The above can be achieved by introducing a fluorine-containing group or a silicone-containing group into the structure of the resin.
For this, a surfactant may be added as an additive. Examples thereof include the use of compounds containing a fluorine atom such as polytetrafluoroethylene, polyvinylidene fluoride and carbon fluoride, a silicone resin or a polyolefin resin.

By these means, it is possible to make the contact angle of the surface of the latent image carrier with water to 85 degrees or more.

Among these, the outermost surface layer of the latent image bearing member is preferably a layer in which fine lubricant particles made of at least one material selected from at least fluorine resin, silicone resin or polyolefin resin are dispersed. .
In particular, it is preferable to use a fluorine-containing resin such as polytetrafluoroethylene or polyvinylidene fluoride. In the present invention, when a fluorine-containing resin is used as the releasable powder as the powder, the dispersion in the outermost surface layer is suitable.

In order to contain these powders on the surface, a layer in which the powders are dispersed in a binder resin is provided on the outermost surface of the photosensitive member, or an organic photosensitive material originally composed mainly of resin is used. In the case of a body, the powder may be dispersed in the outermost surface layer without newly providing a surface layer.

The amount of the above-mentioned powder having releasability added to the surface layer of the latent image carrier is 1 to 60 with respect to the total mass of the surface layer.
It is preferably mass%, and more preferably 2 to 50 mass%. If the amount added is less than the above range, the transfer residual toner particles are not sufficiently reduced and the recovery efficiency of the developer in the developing / cleaning device is not sufficient. If the amount added is too large, it is not preferable because the strength of the film is reduced, or the amount of light incident on the photoreceptor is significantly reduced and the chargeability of the image carrier is impaired. The particle size of the powder is preferably 1 μm or less from the viewpoint of image quality,
It is more preferably 0.5 μm or less, and if the particle size is larger than the above range, line breakage is likely to be deteriorated due to scattering of incident light and resolution is likely to be impaired.

In the present invention, pure water was used to measure the contact angle, and the device used was a contact angle meter CA-DS type manufactured by Kyowa Interface Science Co., Ltd.

One of the preferable modes of the photoreceptor as the latent image carrier used in the present invention will be described below. As the conductive substrate, a metal such as aluminum or stainless steel; a plastic having a coating layer of an aluminum alloy or an indium oxide-tin oxide alloy; paper or plastic impregnated with conductive particles; a plastic having a conductive polymer; a cylindrical shape Cylinders and films are used.

On these conductive substrates, the adhesiveness of the photosensitive layer is improved, the coatability is improved, the substrate is protected, and defects are covered on the substrate.
An undercoat layer may be provided for the purpose of improving the charge injection property from the substrate or protecting the photosensitive layer against electrical breakdown.

The subbing layer is polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenol resin, casein, polyamide, copolymer nylon, glue. , Gelatin, polyurethane or aluminum oxide. The thickness of the undercoat layer is usually 0.1 to 10 μm, preferably 0.1 to 3
μm is good.

The charge generation layer may be an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone pigment, a squarylium dye, a pyrylium salt, a thiopyrylium salt, a triphenylmethane dye, selenium or an amorphous material. A charge generating substance such as an inorganic substance such as silicon is dispersed in an appropriate binder and coated, or formed by vapor deposition. Of these, phthalocyanine pigments are preferable for adjusting the sensitivity of the photoconductor to a sensitivity compatible with the present invention. Examples of the binder include polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacrylic resin, phenol resin,
Examples thereof include silicone resin, epoxy resin, and vinyl acetate resin. The amount of the binder contained in the charge generation layer is 80% by mass or less, preferably 0 to 40% by mass. The thickness of the charge generation layer is 5 μm or less, particularly 0.05 to
2 μm is preferable.

The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transport layer is formed by dissolving a charge transport substance in a solvent, if necessary, together with a binder resin, and coating the solution, and the film thickness thereof is generally 5 to 40 μm. As the charge-transporting substance, biphenylene in the main chain or side chain,
Polycyclic aromatic compounds such as anthracene, pyrene and phenanthrene; nitrogen-containing cyclic compounds such as indole, carbazole, oxadiazole and pyrazoline; hydrazone compounds; styryl compounds; selenium; selenium-tellurium;
Amorphous silicon: Cadmium sulfide can be mentioned.

As the binder resin in which these charge transport substances are dispersed, polycarbonate resin, polyester resin,
Resins such as polymethacrylic acid esters, polystyrene resins, acrylic resins and polyamide resins; organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene.

As the surface layer, a layer in which conductive fine particles are dispersed in a resin may be provided in order to make charge injection more efficient or accelerated. As the surface layer resin, polyester, polycarbonate, acrylic resin, epoxy resin,
Phenolic resins or curing agents for these resins may be used alone or in combination of two or more. Examples of the conductive fine particles include metal or metal oxide.
Preferably, there are ultrafine particles of zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin oxide coated titanium oxide, tin coated indium oxide, antimony coated tin oxide or zirconium oxide. These may be used alone or in combination of two or more.

FIG. 5 is a layer structure model diagram of a latent image carrier (photoreceptor) provided with a charge injection layer as a surface layer. That is, the photoconductor is composed of a conductive substrate (aluminum drum substrate) 11, a conductive layer 12, a positive charge injection prevention layer 13, a charge generation layer 14,
The charge injection layer 16 is applied to a general organic photoconductor drum, which is coated in the order of the charge transport layer 15 to improve the charging performance by charge injection.

The important point of the charge injection layer 16 formed on the outermost surface layer of the latent image carrier is that the surface layer has a volume resistance value of 1 × 10.
It is in the range of ⁹ to 1 × 10 ¹⁴ Ω · cm. Even when the charge injection layer 16 is not provided as in this configuration, the same effect can be obtained when the charge transport layer 15 which is the outermost layer of the latent image carrier is in the above resistance range. For example, even if an amorphous silicon photoconductor having a surface layer having a volume resistance of about 10 ¹³ Ω · cm is used, good chargeability can be obtained by charge injection.

In the present invention, the latent image forming step and the latent image forming means for forming an electrostatic latent image on the charged surface of the latent image carrier are
The step of writing image information as an electrostatic latent image on the surface of the latent image carrier by image exposure and the image exposure means are preferable. The image exposure means for forming an electrostatic latent image is not limited to a laser scanning exposure means for forming a digital latent image, but a usual analog image exposure or LE.
Other light emitting elements such as D may be used, or a combination of a light emitting element such as a fluorescent lamp and a liquid crystal shutter, etc.
It does not matter if it can form an electrostatic latent image corresponding to image information.

The latent image carrier may be an electrostatic recording dielectric. In this case, after the primary surface of the dielectric surface as the image carrier surface is uniformly charged to a predetermined polarity and potential, the target electrostatic latent image is selectively discharged by a charge removing means such as a charge removing needle head or an electron gun. Write and form.

As described above, in the developer of the present invention, the average circularity of the toner is preferably less than 0.970 from the viewpoint of holding an external additive on the toner surface for preventing toner deterioration. However, when the circularity of the toner is low, the charge amount becomes insufficient, and the transfer efficiency is likely to decrease. Furthermore, even if the particle size of the conductive fine particles added to the toner particles is properly adjusted, it is often impossible to completely prevent the deterioration of the triboelectrification characteristics of the toner particles. Therefore, when using a toner having such an average circularity of less than 0.970 and conductive fine particles added externally, it is necessary to enhance the charge imparting property of the developer carrier.

Therefore, in the present invention, the developer carrying member has a substrate and a resin coating layer formed on the substrate, and the resin coating layer contains a positively chargeable substance. I am using. Further, in order to prevent excessive charging of the developer and optimize the charge amount, it is preferable that the resin coating layer contains at least a conductive substance, and the resin coating layer is a conductive resin coating layer. .

As the binder resin for the coating layer of the developer carrying member used in the present invention, any generally known resin can be used. For example, styrene resin, vinyl resin, styrene-diene resin, polyether sulfone resin, polycarbonate resin, polyphenylene oxide resin,
Thermosetting of thermoplastic resins such as polyamide resin, fluororesin, fibrin resin, acrylic resin, epoxy resin, polyester resin, alkyd resin, phenol resin, melamine resin, polyurethane resin, urea resin, silicone resin, polyimide resin, etc. A resin or a photocurable resin can be used. Among these, those having excellent releasability such as silicone resin and fluororesin, or
It is more preferable to use those having excellent mechanical properties such as polyether sulfone resin, polycarbonate resin, polyphenylene oxide resin, polyamide resin, phenol resin, polyester resin, polyurethane resin, styrene resin, and acrylic resin.

It is also preferable to add a positively chargeable substance to these known binder resins for use.

The positively chargeable substance may be any substance that is positively charged when mixed alone with iron powder and frictionally charged. Further, if the binder resin for the coating layer to be dispersed shows positive charge, when used in combination with such a resin, it is not always positive when mixed alone with iron powder and frictionally charged. It does not always have to be charged.

Such positively chargeable substances are generally used as a positive charge control agent such as nigrosine dyes, triphenylmethane dyes, quaternary ammonium salts, guanidine derivatives, imidazole derivatives, amine compounds and polyamine compounds. There are inorganic powders such as synthetic silica, quartz powder, alumina and hydrotalcite compounds; and copolymers having sulfonic acid group-containing acrylamide as a constituent monomer. There is also a method in which these inorganic fine powders are treated with an aminosilane coupling agent and used.

Of these, the following compounds are preferably used in order to favorably charge the developer.

As the positively chargeable substance, it is preferable to contain a nitrogen-containing heterocyclic compound in the coating layer.

The nitrogen-containing heterocyclic compound used at this time has a number average particle size of preferably 20 μm or less, more preferably 0.1 to 15 μm. That is,
When the number average particle diameter of the nitrogen-containing heterocyclic compound exceeds 20 μm, the nitrogen-containing heterocyclic compound is poorly dispersed in the conductive resin coating layer that constitutes the developing sleeve, and the charging performance is sufficiently improved. It is difficult to be done, which is not preferable.

Examples of the nitrogen-containing heterocyclic compound which can be used in the present invention include imidazole, imidazoline, imidazolone, pyrazoline, pyrazole, pyrazolone, oxazoline, oxazole, oxazolone, thiazoline, thiazole,
Thiazolone, selenazoline, selenazole, selenazolone, oxadiazole, thiadiazole, tetrazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, benzoselenazole, pyrazine, pyrimidine, pyridazine, triazine,
Compounds such as oxazine, thiazine, tetrazine, polyazine, pyridazine, pyrimidine, pyrazine, indole, isoindole, indazole, carbazole, quinoline, pyridine, isoquinoline, cinnoline, quinazoline, quinaxaline, phthalazine, purine, pyrrole, triazole, phenazine. . In the present invention, an imidazole compound is particularly preferable because it promotes the effect of the interaction between the developer carrier and the toner used in the present invention.

In the present invention, when an imidazole compound represented by the following general formula (1) or (2) is used in the conductive resin coating layer of the developer carrier, among the imidazole compounds, the toner can be rapidly and It is more preferable because a uniform charge imparting ability can be provided and the strength of the conductive resin coating layer can be increased.

[0350]

[Chemical 11] [Wherein, R ₁ and R ₂ represent a hydrogen atom or a substituent selected from the group consisting of an alkyl group, an aralkyl group and an aryl group, and R ₁ and R ₂ may be the same or different. Good. R ₃ and R ₄ represent a linear alkyl group having 3 to 30 carbon atoms, and R ₃ and R ₄ may be the same or different. ]

[0351]

[Chemical 12] [Wherein R ₅ and R ₆ represent a hydrogen atom or a substituent selected from the group consisting of an alkyl group, an aralkyl group and an aryl group, and R ₅ and R ₆ may be the same or different. Good. R ₇ represents a linear alkyl group having 3 to 30 carbon atoms. The reason why it is preferable to use the imidazole compound having the above-mentioned structure is that the imidazole compound having the structure represented by the general formula (1) or (2) is a linear alkyl group having 3 to 30 carbon atoms as a substituent. Since it has a group, the dispersibility in the binder resin for the coating layer is good, so that it is well dispersed together with other constituent materials of the conductive resin coating layer of the developing sleeve, and the conductive resin coating layer in a particularly excellent dispersed state. It is believed that as a result of the formation of the surface, the triboelectric charging property of the developing sleeve with respect to the toner is improved.

A nitrogen-containing heterocyclic compound such as an imidazole compound having a structure represented by the above-mentioned general formula (1) or (2), which can be preferably used in the present invention, has a nitrogen-containing heterocyclic group It may be a ring, may be condensed with another group, and may be substituted. Furthermore, when the heterocyclic group of the nitrogen-containing heterocyclic compound which can be preferably used in the present invention is substituted, examples of the substituent include an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group and an alkoxy group. , Aryl group, substituted amino group, ureido group, urethane group, aryloxy group,
Sulfamoyl group, carbamoyl group, alkyl or arylthio group, alkyl or aryl sulfonyl group, alkyl or aryl sulfinyl group, hydroxy group, halogen atom, cyano group, sulfo group, aryloxycarbonyl group, acyl group, alkoxycarbonyl group, acyloxy group, Those having a carbonamide group, a sulfonamide group, a carbosyl group, a phosphoric acid amide group, a diacylamino group, an imide group or the like can be used. These substituents may further have a substituent. As examples of the substituent at that time, the above-mentioned substituents as the substituent of the nitrogen-containing heterocycle can be used.

Next, the contents of the nitrogen-containing heterocyclic compound and the conductive fine particles in the conductive resin coating layer will be described. However, this is a particularly preferred range in the present invention,
The present invention is not limited to this. First, the content of the nitrogen-containing heterocyclic compound dispersed in the conductive resin coating layer is preferably 0.5 to 60 parts by mass, more preferably 1 to 100 parts by mass with respect to the binder resin for the coating layer. Fifty
Particularly preferable results are obtained when the content is in the range of parts by mass. That is, when the content of the nitrogen-containing heterocyclic compound is less than 0.5 parts by mass, the effect of adding the nitrogen-containing heterocyclic compound is small, and when it exceeds 60 parts by mass, the volume resistance of the conductive resin coating layer is reduced. It becomes difficult to control it low, and the charge-up phenomenon easily occurs.

The content of the conductive fine particles to be dispersedly contained in the conductive resin coating layer in combination with the nitrogen-containing heterocyclic compound is preferably 40 parts by mass or less with respect to 100 parts by mass of the binder resin for the coating layer. , And more preferably in the range of 2 to 35 parts by mass, particularly preferable results are obtained. That is, when the content of the conductive fine particles exceeds 40 parts by mass, the coating strength of the conductive resin coating layer and the toner charge amount decrease, which is not preferable.

In the developer carrier of the present invention, it is also preferable that the coating layer contains a nitrogen-containing compound as a positively chargeable substance. Examples of such a material include a copolymer containing a unit derived from a nitrogen-containing vinyl monomer. As the polymer forming the copolymer,
Vinyl polymerizable monomers are preferred. Since the binder resin contained in the resin coating layer has a copolymer of a vinyl polymerizable monomer having high mechanical strength and a nitrogen-containing vinyl monomer having high negative triboelectrification property to a developer, The agent carrier has high abrasion resistance of the resin coating layer and high toner adhesion / fusion resistance, and has good triboelectrification characteristics until it is used for many sheets.

Since this copolymer has a nitrogen-containing vinyl monomer, the dispersibility of conductive fine powder such as carbon black and graphite in the resin coating layer is improved. Therefore, the electric resistance of the resin coating layer is favorably reduced, the uniformity of the triboelectric charging property on the surface of the resin coating layer is improved, the triboelectric charging property for the developer is higher, and the charge amount of the developer is higher. Since the distribution becomes sharper and the coating strength of the resin coating layer itself is improved, the durability of a large number of sheets is further improved. Although the reason why the copolymer has this nitrogen-containing vinyl monomer improves the dispersibility of the conductive fine powder such as carbon black and graphite in the resin coating layer, it is not clearly understood. By including a polar group based on the nitrogen atom in the nitrogen vinyl monomer, the solubility in a solvent, particularly a solvent having a polarity is improved, so that the wettability of the solution in which the resin is dissolved with respect to the conductive fine particles is improved. It is considered that the dispersibility of the conductive fine particles in the resin coating layer is improved when the resin coating layer is formed by coating the conductive fine particles in the solution. In particular, when the conductive fine particles are a substance such as carbon black having a polar group on the surface, the affinity is further increased by the polar group based on the nitrogen atom, which is more effective.

In the present invention, the copolymerization mol ratio of the copolymer having the vinyl polymerizable monomer (M) and the nitrogen-containing vinyl monomer (N) is M: N = 4: 1 to 999: 1.
It is preferable to satisfy. When the ratio of M exceeds 999: 1, there is almost no effect of adding the nitrogen-containing vinyl monomer, that is, the effect of improving the triboelectrification imparting property is extremely small, and the effect of copolymerization is hardly seen. When the ratio of M is less than 4: 1, the resin layer is not stable due to, for example, a decrease in Tg, and the temperature rise of the main body of the electrophotographic apparatus impairs charging and abrasion resistance of the resin layer. The toner may be easily fixed. Further, even if the ratio of the nitrogen-containing vinyl monomer is further increased, the effect of imparting charge is saturated, so that it is not particularly required.

In the present invention, the vinyl polymerizable monomer which can be the main component of the above-mentioned copolymer is, for example, styrene, α-methylstyrene, acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, acrylic. N-Butyl acid, iso-butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, cyclohexyl acrylate, hydroxyethyl acrylate, dimethyl (amino) ethyl acrylate, diethyl (amino) ethyl Acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, hydroxyethyl methacrylate. Rate, dimethyl (amino) ethyl methacrylate, diethyl (amino) ethyl methacrylate, acrylonitrile, methacrylonitrile, monocarboxylic acids having such acrylamide double bond,
Or an ester compound thereof; for example, a dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate, and an ester compound thereof; these may be used alone or in 2
It can be used as a mixture of two or more species. In particular, when an acid monomer or an acid ester monomer having a vinyl group is contained, it has an effect on the charge stability of the developer on the developer carrier. In that case, as the effect of stabilizing the triboelectric charge amount, it is slightly better to use the acid monomer than the acid ester monomer.

In the present invention, it is preferable to use methyl methacrylate as the vinyl polymerizable monomer. When used as a polymer, methyl methacrylate has excellent mechanical strength. Further, when it is used by being contained in the binder resin of the sleeve surface layer, good triboelectricity imparting property to the developer can be obtained. However, when used as a homopolymer, the triboelectric charge imparting property is often insufficient, and the dispersibility of pigments such as carbon black and graphite is not so good. By using as a copolymer containing a nitrogen-containing vinyl monomer as in the present invention,
The triboelectric charging property can be improved. In the present invention, the methyl methacrylate component is preferably 8
Since it is contained in a proportion of 0% or more, it does not impair mechanical strength, such as abrasion resistance, even when compared with a methyl methacrylate homopolymer. Furthermore, since the nitrogen-containing vinyl monomer component is contained, when the pigment component such as the conductive fine powder is dispersed in the resin layer, the dispersibility is improved, and in this respect as well, the abrasion resistance and the like are improved. preferable.

The molecular weight of the copolymer containing the unit derived from the nitrogen-containing vinyl monomer is preferably in the range of 3,000 to 50,000 in terms of weight average molecular weight Mw. When the molecular weight Mw is less than 3,000, the amount of low-molecular weight components is too large, so that the toner easily adheres to or sticks to the sleeve, and the charge imparting property of the resin deteriorates. If the Mw exceeds 50,000, the molecular weight is too high and the viscosity of the resin in the solvent is high, which may cause poor coating or poor dispersion when pigments are added, resulting in a non-uniform resin layer composition. This may cause unstable toner charging, unstable surface roughness, and reduced abrasion resistance.

Further, Mw / Mn representing the ratio of the weight average molecular weight to the number average molecular weight of the copolymer containing a unit derived from a nitrogen-containing vinyl monomer is preferably 3.5 or less. When Mw / Mn exceeds 3.5, the amount of low molecular weight components increases, so that the adhesion of the toner and the fusion of the toner increase, and the property of imparting triboelectric charge to the toner tends to decrease.

In the present invention, the molecular weight distribution of the GPC chromatogram of the copolymer containing the unit derived from the nitrogen-containing vinyl monomer is measured as follows. That is, the column was stabilized in a heat chamber at 40 ° C., and THF as a solvent was flowed through the column at this temperature at a flow rate of 1 ml / min to prepare a THF sample solution of about 100 μm.
l Inject and measure. When measuring the molecular weight of a sample,
The molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of the calibration and the number of counts prepared from several kinds of monodisperse polystyrene standard samples. As a standard polystyrene sample for preparing a calibration curve, for example, a standard polystyrene sample having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation or Showa Denko is used, and it is suitable to use a standard polystyrene sample of at least about 10 points. . An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns, for example, Shodex GPCKF-801, 802 manufactured by Showa Denko KK
Combination of 803, 804, 805, 806, 807, 800P and TSKgel G1000H manufactured by Tosoh Corporation
(H _XL ), G2000H (H _XL ), G3000H
(H _XL ), G4000H (H _XL ), G5000H
(H _XL ), G6000H (H _XL ), G7000H
(H _XL ), the combination of TSKguardcolumn can be mentioned.

As a typical example of the nitrogen-containing vinyl monomer,
For example, p-dimethylaminostyrene, dimethylaminomethyl acrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminomethyl acrylate, diethylaminoethyl acrylate, dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminopropyl methacrylate, diethylaminomethyl methacrylate, diethylamino And ethyl methacrylate,
Further, nitrogen-containing heterocyclic N-vinyl compounds such as N-vinylimidazole, N-vinylbenzimidazole, N-vinylcarbazole, N-vinylpyrrole, N-vinylpiperidine, N-vinylmorpholine and N-vinylindole are Can be mentioned.

Particularly, dimethylaminomethyl acrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminomethyl acrylate, diethylaminoethyl acrylate, dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminopropyl methacrylate, diethylaminomethyl methacrylate, diethylaminoethyl methacrylate. The following general formula (3) such as

[0365]

[Chemical 13] [In the formula, R ₇ , R ₈ , R ₉ and R ₁₀ represent a hydrogen atom or a saturated hydrocarbon group having 1 to 4 carbon atoms, and n is 1 to 4
Indicates an integer. ] It is preferable to use the nitrogen-containing vinyl monomer represented by

Particularly, the following general formula (8) such as dimethylaminoethyl methacrylate and diethylaminoethyl acrylate is used.

[0367]

[Chemical 14] [However, R ₁ , R ₂ and R ₃ are hydrogen atoms or carbon atoms 1
~ 4 saturated hydrocarbon groups. ] It is preferable to use the nitrogen-containing vinyl monomer shown in the above.

As the nitrogen-containing vinyl monomer used in the present invention, a quaternary ammonium group-containing vinyl monomer can also be used. Examples of the quaternary ammonium group-containing vinyl monomer include those represented by the following general formula (9).

[0369]

[Chemical 15] [In the formula, R ₅ represents a hydrogen atom or a methyl group, R ₆ represents an alkylene group having 1 to 4 carbon atoms, R _{7 to} R ₉ represent a methyl group, an ethyl group or a propyl group, and X ₁ Is -COO
- or shows a -CONH-, A ^- is Cl ^-, (1/2) S
It represents an anion such as O ₄ ^2- . In the present invention, the copolymer containing a nitrogen-containing vinyl monomer may be used alone as the binder resin for the coating layer, or may be used by adding it to another binder resin. When used by being added to other binder resins, generally known resins as described above can be used. A thermosetting resin is more preferable in consideration of the mechanical strength required for the developer carrying member, but a thermoplastic resin can also be applied as long as it has sufficient mechanical strength.

Further, such a resin may be blended with a thermosetting resin or the like having higher strength as a charge control agent and used. Even in such a case, the positive chargeability of the sleeve is improved due to the effect caused by the nitrogen-containing vinyl monomer.

Further, in the developer carrying member of the present invention,
As a positively chargeable substance, at least a copolymer of a vinyl polymerizable monomer and a sulfonic acid group-containing acrylamide monomer is contained in the coating layer on the surface of the development carrier, and at the same time, as a binder resin for the coating layer, its molecule is used. It is also preferable to use a resin containing at least one of —NH ₂ group, ═NH group, or —NH— bond in the structure.

In the present invention, although the definite reason that it exhibits a positive charging property is not clear, a copolymer of a vinyl polymerizable monomer and a sulfonic acid group-containing acrylamide monomer is used in which at least -NH ₂ group is contained in the molecular structure. = NH group, or when used by being dispersed in a binder resin for a coating layer having a -NH- bond, the resin is uniformly dispersed, and a resin is formed by the structural interaction between the copolymer and the binder resin. It is considered that this is because the entire composition has uniform chargeability and sufficient positive chargeability.

The above-mentioned polymer in the present invention has a copolymerization ratio based on the mass of a vinyl-polymerizable monomer and a sulfonic acid group-containing acrylamide monomer of 98: 2 to 80:20, and a weight average molecular weight of 2000 to 50,000. It is preferable that they are united. If the proportion of the sulfonic acid group-containing acrylamide monomer is less than 2% by mass, the ability to induce a positive charge on the toner is poor. If it exceeds 20% by mass, environmental stability such as moisture resistance is deteriorated and coating film characteristics are deteriorated, which is not preferable. The weight average molecular weight is 2000
If it is less than the above range, the amount of the low molecular weight component is too much, so that the toner is likely to adhere to or stick to the sleeve, or the charge imparting property of the resin is deteriorated. Weight average molecular weight is 50,000
If it exceeds, the compatibility with the resin will decrease, stable chargeability will not be obtained due to environmental changes and aging, and since the resin viscosity in the solvent is high, when coating defects or pigments are added This may cause poor dispersion, the composition of the resin coating layer may become non-uniform, the toner charging may not be stable, the surface roughness of the resin coating layer may not be stable, and the abrasion resistance may decrease.

The addition amount of the sulfonic acid group-containing acrylamide monomer used in the present invention as described above is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 1 part by mass, the addition of charge cannot be improved by addition, and if the amount exceeds 100 parts by mass, the dispersion in the binder resin becomes poor and the coating strength is apt to decrease.

The vinyl polymerizable monomer that can be used for producing the above copolymer in the present invention includes:
Styrene, α-methylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate,
iso-butyl (meth) acrylate, cyclohexyl (meth) acrylate, dimethyl (amino) ethyl (meth) acrylate, diethyl (amino) ethyl (meth)
Examples thereof include acrylate, hydroxyethyl (meth) acrylate, (meth) acrylic acid, vinyl acetate and vinyl propionate, and these can be used alone or as a mixture of two or more kinds. Preferred is a combination of styrene and an acrylic ester or a methacrylic ester. In general, the glass transition point of the binder resin for toner is usually 70 ° C. or lower to 60 ° C. or lower. Therefore, when the vinyl polymerizable monomer is used, the adhesion of the toner to the surface of the coating film should be prevented. In order to avoid it, it is preferable that the binder resin for the coating layer is appropriately selected so that a coating film having a glass transition point of 65 ° C. or higher, preferably 70 ° C. or higher, more preferably 90 ° C. or higher is formed.

Further, as the sulfonic acid group-containing acrylamide monomer, 2-acrylamidopropanesulfonic acid, 2-acrylamido-n-butanesulfonic acid, 2-acrylamido
Acrylamide-n-hexanesulfonic acid, 2-acrylamido-n-octanesulfonic acid, 2-acrylamido-n-dodecanesulfonic acid, 2-acrylamido-n
-Tetradecane sulfonic acid, 2-acrylamido-2-
Methylpropanesulfonic acid, 2-acrylamido-2-
Phenylpropanesulfonic acid, 2-acrylamido-2,2,4-trimethylpentanesulfonic acid, 2-acrylamido-2-methylphenylethanesulfonic acid, 2
-Acrylamido-2- (4-chlorophenyl) propanesulfonic acid, 2-acrylamido-2-carboxymethylpropanesulfonic acid, 2-acrylamido-2-
(2-pyridyl) propanesulfonic acid, 2-acrylamido-1-methylpropanesulfonic acid, 3-acrylamido-3-methylbutanesulfonic acid, 2-methacrylamido-n-decanesulfonic acid, 2-methacrylamido-
Mention may be made of n-tetradecane sulfonic acid. Preferred is 2-acrylamido-2-methylpropanesulfonic acid.

Polymerization initiators that can be used when copolymerizing the vinyl polymerizable monomer and the sulfonic acid group-containing acrylamide monomer include peroxide initiators and azo initiators. A peroxide initiator having a carboxyl group and having an effect on the negative charging property is good, and the initiator is 0.5 to
It is preferably used in the range of 5% by mass. Further, as the polymerization method, it is possible to use any method such as solution polymerization, suspension polymerization, and bulk polymerization, but is not particularly limited, but an organic solvent containing a lower alcohol such as methanol, isopropanol, butanol, etc. Among them, it is particularly preferable to employ the solution polymerization method in which the above-mentioned monomer mixture is copolymerized.

In this case, the binder resin for the coating layer in the developer carrying member is a copolymer of the vinyl polymerizable monomer and a sulfonic acid group-containing acrylamide monomer, and a part or all of the copolymer has a molecular structure thereof. A binder resin having at least one of —NH ₂ group, ═NH group, or —NH— bond is used.

As the substance having a —NH ₂ group, R—N
The primary amine represented by H ₂ or a polyamine having the same, the primary amide represented by RCO-NH ₂ or the polyamide having them, and the like; 2 amine or a polyamine having them, a secondary amide represented by (RCO) ₂ = NH, or a polyamide having them, etc., —NH
Examples of the substance having a —bond include polyurethanes having a —NHCO— bond in addition to the above-mentioned polyamines and polyamides, and one or more of the above substances are contained, or as a copolymer, industrially. A synthetic resin is preferably used. Among them, phenol resins, polyamide resins and urethane resins using ammonia as a catalyst are preferable. As the phenol resin constituting the binder resin used in the present invention, as a result of intensive studies by the present inventors, by using a phenol resin using a nitrogen-containing compound as a catalyst in the production process, at the time of heat curing Structural interaction with the copolymer easily occurs,
It was found that the entire resin composition has uniform chargeability and has sufficient positive chargeability.

Therefore, such a phenol resin is used as one of the materials constituting the coating layer on the developer carrying member in the present invention.
As a result, a good negative imparting property can be obtained.
Examples of the nitrogen-containing compound used as a catalyst in the production process of the phenol resin used in the present invention include, as acidic catalysts, ammonium sulfate, ammonium phosphate,
Ammonium or amino salts of acids such as ammonium sulfamate, ammonium carbonate, ammonium acetate and ammonium maleate, and basic catalysts such as ammonia or dimethylamine, diethylamine, diisopropylamine, diisobutylamine, diamylamine, trimethylamine, triethylamine. , Tri-n-butylamine, triamylamine, dimethylbenzylamine, diethylbenzylamine, dimethylaniline, diethylaniline, n, n-di-n-butylaniline, n, n-diamylaniline, n, n-dit-amyl Aniline, n-methylethanolamine, n-ethylethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiamine Ethanolamine, n- butyl diethanolamine, di-n- butyl ethanolamine, triisopropanolamine, ethylenediamine, such as the amino compounds of hexamethylenetetramine, pyridine, alpha
Pyridines such as picoline, β-picoline, γ-picoline, 2,4-lutidine, 2,6-lutidine and derivatives thereof,
Quinoline compounds, imidazole, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-
Methylimidazole, 2-phenylimidazole, 2-
There are nitrogen-containing heterocyclic compounds such as phenyl-4-methylimidazole and 2-heptadecylimidazole.

As the polyamide resin constituting the binder resin used in the present invention, for example, nylon 6, 66, 610, 11, 12, 9, 13, Q2 nylon, or nylon containing these as the main components is used. Copolymer,
Alternatively, both N-alkyl modified nylon and N-alkoxyl alkyl modified nylon can be preferably used. Furthermore, any resin modified with polyamide such as polyamide-modified phenolic resin, or an epoxy resin using polyamide resin as a curing agent may be used as long as it is a resin containing a polyamide resin component. Can also be preferably used.

Further, as the urethane resin constituting the binder resin used in the present invention, any urethane resin having a urethane bond can be preferably used. This urethane bond is obtained by a polymerization addition reaction of polyisocyanate and polyol.

As the polyisocyanate as the main raw material of this polyurethane resin, diphenylene methane-4,
4'-diisocyanate (MDI), isophorone diisocyanate (IPDI), polymethylene polyphenyl polyisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, carbodiimide-modified diphenylmethane-
4,4'-diisocyanate, trimethyl hexajylene diisocyanate, ortho toluidine diisocyanate, naphthylene diisocyanate, xylene diisocyanate, paraphenylene diisocyanate, lysine diisocyanate methyl ester, dimethyl diisocyanate can be used.

As the polyol which is the main raw material for the polyurethane resin, polyester adipate such as polyethylene adipate ester, polybutylene adipate ester, polydiethylene glycol adipate ester, polyhexene adipate ester and polycaprolactone ester, polytetramethylene glycol and polypropylene glycol can be used. Such polyether polyols can be used.

In the present invention, the volume resistance of the resin coating layer formed on the surface of the developer carrier with the above-mentioned materials is 10 or less.
It is preferably adjusted to ³ Ω · cm or less, and more preferably 10 ³ to 10 ⁻² Ω · cm. That is, when the volume resistance of the resin coating layer exceeds 10 ³ Ω · cm, charge-up is likely to occur, and ghost deterioration and concentration reduction are likely to occur. Therefore, in the developing device of the present invention, in order to adjust the volume resistance of the resin coating layer on the surface of the developer carrier to the preferable range as described above, the conductive resin is added to the binder resin which is the film forming material of the resin coating layer. Disperse the substance. The particle diameter of the electrically conductive substance used in this case is preferably 20 μm or less in terms of number average particle diameter, preferably 10 μm.
It is more preferable to use the following. Furthermore, in order to avoid the unevenness formed on the surface of the resin coating layer, it is preferable to use one having a thickness of 1 μm or less.

As the conductive substance that can be used at this time,
For example, carbon black such as furnace black, lamp black, thermal black, acetylene black and channel black; metal oxides such as titanium oxide, tin oxide, zinc oxide, molybdenum oxide, potassium titanate, antimony oxide and indium oxide; aluminum,
Examples thereof include metals such as copper, silver and nickel, and inorganic fillers such as graphite, metal fibers and carbon fibers. The addition amount of these conductive substances in the resin coating layer,
It is preferably used in an amount of 100 parts by mass or less with respect to 100 parts by mass of the binder resin. If the amount added exceeds 100 parts by mass, the coating strength tends to decrease, and addition of a large amount of the conductive substance tends to cause a decrease in the charge amount of the toner.

Further, in the developing device of the present invention, the resin coating layer provided on the surface of the developer carrying member to be used has a particle size of 0 in addition to the above-mentioned positively chargeable substance and conductive substance. It is preferable that spherical particles of about 3 to 30 μm are dispersed in the coating resin layer. With such a configuration, the surface roughness of the developer carrying member can be stabilized, and the toner coating amount on the developer carrying member can be optimized. Further, the inclusion of the spherical particles in the resin coating layer allows the surface of the developer bearing member to have a uniform surface roughness, and at the same time, even when the resin coating layer provided on the surface of the developer bearing member is worn out. Since the change in the surface roughness of the layer can be reduced, it is possible to obtain the effect of making it difficult to cause toner contamination or toner fusion on the developer carrying member. Furthermore,
By including the spherical particles as described above, due to the interaction with the nitrogen-containing heterocyclic compound contained in the resin coating layer,
The effect of controlling the charge possessed by the nitrogen-containing heterocyclic compound is further enhanced, the quick and uniform charging property to the toner can be further improved, and further, the charging property is stabilized.

The spherical particles used in the present invention have a number average particle diameter of 0.3 to 30 μm, more preferably 2 to 2
It is preferably 0 μm. That is, when the number average particle diameter of the spherical particles contained in the resin coating layer is less than 0.3 μm, the effect of imparting uniform roughness to the surface of the developer carrying member and the effect of enhancing the charge imparting performance are small. In addition to insufficient rapid and uniform charging of the developer, toner wear-up due to abrasion of the resin coating layer, toner contamination and toner fusion tend to occur, resulting in deterioration of ghost,
This is not preferable because the image density is likely to decrease. on the other hand,
When spherical particles having a number average particle size of more than 30 μm are added, the surface roughness of the resin coating layer tends to be too large, which makes it difficult to sufficiently charge the toner, and the resin coating layer It is not preferable because the mechanical strength is reduced.

Further, the spherical particles used in the present invention have a true density of 3 g / cm ³ or less, preferably 2.
7 g / cm ³ or less, more preferably 0.9 to 2.3 g /
It is recommended to use a cm ³ one. That is, when the true density of the spherical particles exceeds ³ g / cm ³ , the dispersibility of the spherical particles in the resin coating layer becomes insufficient, it becomes difficult to impart uniform roughness to the surface of the coating layer, and the nitrogen-containing The heterocyclic compound is not evenly dispersed, and the ability to impart a rapid and uniform charge to the toner and the strength of the coating layer become insufficient, which is not preferable. On the other hand, the true density of spherical particles is 0.9 g /
Even when it is smaller than cm ^3, the dispersibility of the spherical particles in the coating layer tends to be insufficient, which is not preferable.

The spherical shape in the spherical particles referred to in the present invention means
The particle has a major axis / minor axis ratio of about 1.0 to 1.5, more preferably a major axis / minor axis ratio of 1.
It is preferable to use spherical particles that are closer to the true spherical shape of 0 to 1.2. That is, when the ratio of the major axis / minor axis of the spherical particles exceeds 1.5, the dispersibility of the spherical particles in the conductive resin coating layer decreases, and the positively chargeable substance in the coating layer becomes A decrease in dispersibility and non-uniformity of the roughness of the surface of the coating layer occur, resulting in rapid and uniform charge imparting property to the toner, and
It is also not preferable from the viewpoint of film strength of the resin coating layer formed.

As the spherical particles used in the present invention, known spherical particles can be used. For example, spherical resin particles, spherical metal oxide particles, spherical carbonized particles and the like can be mentioned. Examples of the spherical resin particles include spherical resin particles having a desired particle diameter, which are directly obtained by a suspension polymerization method, a dispersion polymerization method, or the like. Of these, spherical resin particles are particularly preferable in the present invention, because a suitable surface roughness can be obtained with a smaller addition amount and a more uniform surface shape can be easily obtained. Such spherical resin particles, polyacrylate, acrylic resin particles such as polymethacrylate, polyamide resin particles such as nylon, polyethylene, polyolefin resin particles such as polypropylene, silicone resin particles, phenolic resin particles, Examples thereof include polyurethane resin particles, styrene resin particles, and benzoguanamine particles. These resin particles are not limited to those obtained by the above-mentioned polymerization method, and resin particles obtained by the pulverization method may be subjected to thermal or physical sphering treatment. .

Further, in the present invention, the inorganic fine powder may be adhered or fixed to the surface of the above-mentioned spherical particles for use. As the inorganic fine powder used at this time, for example,
_{SiO 2, SrTiO 3, CeO 2} , CrO, Al 2 O
₃ , oxides such as ZnO and MgO, nitrides such as Si ₃ N ₄ , carbides such as SiC, CaSO ₄ , BaSO ₄ ,
Examples thereof include sulfates and carbonates such as CaCO ₃ . The inorganic fine powder may be treated with a coupling agent.

In particular, for the purpose of improving the adhesion with the binder resin, or for imparting hydrophobicity to the spherical particles, etc.
It is preferable to use a fine inorganic powder treated with a coupling agent. Examples of the coupling agent used at this time include a silane coupling agent, a titanium coupling agent, and a zircoaluminate coupling agent. More specifically, for example, as the silane coupling agent, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane. , Benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, Dimethyldiethoxysilane, jardimethoxysilane,
Diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,
3-diphenyltetramethyldisiloxane, and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and having a hydroxyl group bonded to a silicon atom for each one located at the terminal are mentioned. .

As described above, preferably, the inorganic fine particles treated with the coupling agent are adhered or fixed on the surface of the spherical particles to be treated, whereby the dispersibility of the spherical particles in the conductive resin coating layer, It is possible to improve the uniformity of the surface of the coating layer, stain resistance, charge imparting property to toner, abrasion resistance of the conductive resin coating layer, and the like.

Further, in the present invention, it is preferable to use conductive particles as the spherical particles. That is,
By imparting conductivity to the spherical particles, it becomes difficult for charges to accumulate on the surface of the spherical particles due to their conductivity, so that it is possible to reduce the toner adhesion to the developer carrying member and improve the charge imparting ability to the toner. it can. The spherical particles used at that time have a volume resistance value of 10 ⁶ Ω · cm.
Below, it is more preferable to have conductivity of 10 ⁻³ to 10 ⁶ Ω · cm. That is, when the volume resistance of the spherical particles used in the present invention exceeds 10 ⁶ Ω · cm,
The spherical particles exposed on the surface of the coating layer due to abrasion are liable to cause contamination and fusion of the toner, and it is difficult to rapidly and uniformly charge the toner, which is not preferable.

As a method for obtaining the conductive spherical particles having such a volume resistance, it is preferable to use the following method, but the method is not necessarily limited to these methods. That is, as a method for obtaining conductive spherical particles that can be suitably used in the present invention, for example, resin-based spherical particles or mesocarbon microbeads are fired to carbonize and / or graphitize to have a low density and good conductivity. A method of obtaining spherical carbon particles can be mentioned. Examples of the resin spherical particles used at this time include resins such as phenol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer, and polyacrylonitrile. The mesocarbon microbeads can be usually produced by washing spherical crystals produced in the process of heating and firing the medium pitch with a large amount of a solvent such as tar, medium oil or quinoline.

As a more preferable method for obtaining conductive spherical particles which can be used in the present invention, spherical particles such as phenol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer and polyacrylonitrile can be used. The surface of resin particles is coated with bulk mesophase pitch by a mechanochemical method, and the coated particles are heat-treated in an oxidizing atmosphere and then fired in an inert atmosphere or in a vacuum to carbonize and / or graphitize, resulting in conductivity. The method of obtaining the spherical spherical carbon particles can be mentioned. The spherical carbon particles obtained by this method are more preferable as the spherical particles to be used in the present invention, because the coated portion of the spherical carbon particles is crystallized by being graphitized and the conductivity is improved.

The electroconductive spherical carbon particles obtained by the above-mentioned method can control the electroconductivity of the spherical carbon particles obtained by changing the firing conditions to some extent in any method. Therefore, spherical carbon particles that can be preferably used in the present invention can be easily obtained. In addition, the spherical carbon particles obtained by the above method may have a conductive particle on the surface within a range in which the true density of the conductive spherical particle does not exceed ³ g / cm ³ in order to further increase the conductivity in some cases. The above metal and / or metal oxide may be plated.

As another method for obtaining the conductive spherical particles which can be preferably used in the present invention, the conductive fine particles smaller than the particle diameter of the core particles are mechanically mixed with the core particles composed of the spherical resin particles in an appropriate mixing ratio. The conductive particles are uniformly attached to the periphery of the core particles by the action of van der Waals force and electrostatic force, and then the local temperature rise is caused by, for example, applying mechanical impact force. The surface of the core particles is softened by the method, and the conductive fine particles are fixed to the surface of the core particles to coat the surface of the core particles with the particles to obtain spherical resin particles that have been subjected to the conductivity treatment. The core particles, it is preferable to use a small spherical resin particles of true density made of an organic compound, as the resin, for example,
PMMA, acrylic resin, polybutadiene resin, polystyrene resin, polyethylene, polypropylene, polybutadiene, or copolymers thereof, benzoguanamine resin, phenol resin, polyamide resin, nylon, fluorine resin, silicone resin, epoxy resin, polyester resin, etc. To be Conductive fine particles (small particles) coated on the surface of core particles (mother particles) made of these materials
As the small particles, those having a particle size of 1/8 or less of the particle size of the mother particles are used so that the coating film made of the conductive fine particles is uniformly provided on the surface of the core particles. It is preferable.

Further, as another method for obtaining the conductive spherical particles which can be preferably used in the present invention, the conductive spherical particles in which the conductive fine particles are dispersed by uniformly dispersing the conductive fine particles in the spherical resin particles are used. The method of obtaining a particle | grain is mentioned.
As a method for uniformly dispersing the conductive fine particles in the spherical resin particles, for example, the binder resin and the conductive fine particles are kneaded to disperse the conductive fine particles, followed by cooling and solidification, and pulverization to a predetermined particle size. And to obtain conductive spherical particles by spheroidizing by mechanical and thermal treatments; or adding a polymerization initiator, conductive fine particles and other additives into a polymerizable monomer, and uniformly using a disperser. The dispersed polymerizable monomer composition is suspended in an aqueous phase containing a dispersion stabilizer by a stirrer or the like so as to have a predetermined particle size and polymerized, and the conductive fine particles are dispersed in a spherical shape. Examples thereof include a method of obtaining particles.

Also in the case of conductive spherical resin particles in which conductive fine particles are dispersed in the binder resin obtained by these methods, these are used as core particles, and particles smaller than the core particles are used as described above. After mechanically mixing the conductive fine particles of a suitable diameter in an appropriate mixing ratio, the conductive fine particles are uniformly attached to the periphery of the conductive spherical particles by the action of Van der Waals force and electrostatic force, and then, for example, mechanical The surface temperature of the electrically conductive spherical particles is softened by the local temperature rise caused by the application of the dynamic impact force, the electrically conductive fine particles are fixed to the surface of the core particles, and the surface of the core particles is coated with the electrically conductive fine particles. You may raise and use.

Further, the content of the spherical particles dispersed in the conductive resin coating layer is 100% by weight of the binder resin 100 for coating layer.
Particularly preferable results are obtained when the amount is preferably 2 to 120 parts by mass, more preferably 2 to 80 parts by mass with respect to parts by mass. That is, when the content of the spherical particles is less than 2 parts by mass, the effect of adding the spherical particles is small, and
If the amount is more than the amount by mass, the chargeability of the toner may be too low.

Further, in the developing device of the present invention, if a lubricating material is further dispersed in the resin coating layer provided on the surface of the developing carrier as a developing carrier, the present invention is further improved. This is preferable because the effect of is promoted. Examples of the lubricating substance that can be used in this case include graphite, molybdenum disulfide, boron nitride, mica, graphite fluoride, silver-niobium selenide, calcium chloride-graphite, talc, and fatty acid metal salts such as zinc stearate. Can be mentioned. Among these, graphite is especially
It is preferably used because it does not impair the conductivity of the conductive resin coating layer. Further, as these lubricating substances, those having a number average particle diameter of preferably about 0.2 to 20 μm, more preferably 0.3 to 15 μm may be used.

Further, as the addition amount of the above-mentioned lubricating substance,
It is preferably 5 to 100 parts by mass of the binder resin for the coating layer.
Particularly preferable results are obtained when the amount is 120 parts by mass, more preferably 10 to 100 parts by mass. That is, when the content of the lubricating particles exceeds 120 parts by mass, the film strength and the toner charge amount decrease, and when the content is less than 5 parts by mass, a toner having a small particle size of 7 μm or less is used. When the developing device is used for a long period of time, toner contamination tends to occur on the surface of the resin coating layer.

The developer carrying member used in the present invention comprises at least a substrate and a conductive resin coating layer formed on the substrate and made of the above-mentioned material. A metal cylindrical tube is used as the substrate, but as the metal cylindrical tube,
For example, a cylindrical tube made of stainless steel or aluminum is preferably used.

In the present invention, when the resin coating layer is formed of the above-mentioned constituent materials, the surface roughness of the resin coating layer is expressed by the center line average roughness (hereinafter referred to as “Ra”). The value of is preferably 0.3 to 3.5 μm, more preferably 0.5 to 3.0 μm. That is, Ra on the surface of the conductive resin coating layer is 0.
If it is less than 3 μm, the toner transporting property may be deteriorated and a sufficient image density may not be obtained.
When Ra on the surface of the conductive resin coating layer exceeds 3.5 μm, the toner may be conveyed too much and the toner may not be sufficiently charged.

Further, the resin coating layer having the above-mentioned structure preferably has a layer thickness of 25 μm or less, more preferably 20 μm or less, further preferably 4 to 20 μm, because a uniform film thickness can be obtained. . However, it is not particularly limited to this layer thickness. The resin coating layer having such a layer thickness may have an adhesion weight of about 4,000 to 20,000 mg / m ² , though it depends on the material for forming the resin coating layer.

The methods for measuring physical properties relating to the present invention will be described below.

(1) Measurement of charge polarity of resin coating layer <Method for producing sample plate>: Resin solution for forming a resin coating layer (excluding conductive substances such as carbon and graphite) whose charge polarity is to be measured Is coated on a SUS plate with a bar coater (# 60) and dried to heat to form a film (drying / heating temperature and time are, in the case of a thermoplastic resin, until the solution is completely evaporated, In the case of a thermosetting resin, a sample plate is prepared until the resin is completely crosslinked. With this sample plate grounded,
Let stand overnight in an environment of ℃ and 60% relative humidity.

<Preparation method of particles>: Iron powder (particle size: about 100)
(μm) is grounded and left overnight at 23 ° C. and 60% relative humidity.

<Measurement method>: The measurement was 23 ° C. and the relative humidity was 6
Perform in a 0% environment. First, the sample plate prepared above is set on the surface charge amount measuring device TS-100AS (manufactured by Toshiba Chemical Co., Ltd.) shown in FIG. 8, and the value of the electrometer 55 is grounded to zero. Put the iron powder 51 whose humidity has been adjusted in the above into the dropping device 52, press the START switch to drop the iron powder 51 on the sample plate 53 for 20 seconds, and then ground the receptacle 5 in advance.
Receive at 4. At this time, the polarity indicated by the electrometer 55 is read to determine the charge polarity of the resin coating layer (only the resin component) with respect to the iron powder. In addition, 56 is a condenser.

(2) Measurement of center line average roughness (Ra) Based on the method of measuring surface roughness of JIS B0601, a surf coder SE-3300 manufactured by Kosaka Laboratory was used to measure the axial direction 3
Each of the points x 2 in the circumferential direction = 6 points was measured, and the average value was taken.

(3) Measurement of volume resistance of particles A granular sample was placed in an aluminum ring having a diameter of 40 mm and 250
It was pressure-molded at 0 N, and the volume resistance value was measured using a 4-meter probe with a resistivity meter Loresta AP or Hiresta IP (both manufactured by Mitsubishi Yuka). The measurement environment is 20-2
It was set to 5 ° C. and 50 to 60% RH.

(4) Measurement of volume resistance of resin coating layer A coating layer having a thickness of 7 to 20 μm was formed on a PET sheet having a thickness of 100 μm to prepare a sample for measurement, and the sample was measured according to the ASTM standard (D -991-82) and
Japan Rubber Association Standard SRIS (2301-1969)
The voltage drop type digital ohmmeter (manufactured by Kawaguchi Denki Seisakusho) provided with electrodes having a four-terminal structure for measuring the volume resistance of conductive rubber and plastic in conformity with. still,
The measurement environment was 20 to 25 ° C. and 50 to 60 RH%.

(5) Measurement of True Density of Spherical Particles The true density of the spherical particles used in the present invention was measured using a dry densitometer Acupic 1330 (manufactured by Shimadzu Corporation).

(6) Particle Size Measurement of Spherical Particles The particle size was measured as follows using a Coulter LS-130 type particle size distribution meter (manufactured by Coulter Co.) which is a laser diffraction type particle size distribution meter. An aqueous module is used as the measuring method, and pure water is used as the measuring solvent. First, the inside of the measurement system of the particle size distribution meter is washed with pure water for about 5 minutes, 10 to 25 mg of sodium sulfite is added to the measurement system as an antifoaming agent, and the background function is executed. Next, 3 to 4 drops of the surfactant is added to 10 ml of pure water, and 5 to 25 mg of the measurement sample is further added. An aqueous solution in which this sample is suspended is dispersed by an ultrasonic disperser for about 1 to 3 minutes to obtain a sample liquid for measurement, and the sample liquid is gradually added to the measurement system of the above-mentioned measuring device for measurement. At that time, the PIDS on the screen of the device is 4
The sample concentration in the measurement system is adjusted so as to be 5 to 55%, the measurement is performed, and the number average particle diameter is calculated by arithmetic operation from the number distribution.

(7) Particle size measurement of conductive fine particles contained in the developer The particle size of the conductive fine particles was measured using an electron microscope.
The photographing magnification is 60,000, but if it is difficult, the photograph is magnified and printed at a low magnification and then 60,000 times. Measure the particle size of the primary particles on the photograph. At this time, the major axis and the minor axis are measured, and the averaged value is taken as the particle size. This is measured for 100 samples, and the 50% value is taken as the average particle size.

Next, the developing conditions suitable for the present invention will be described.

In the present invention, 3 to 3 on the developer carrying member.
It is preferable to form a developer layer of 0 g / m ² . By forming a developer layer of ³ to 30 g / m ² on the developer carrier, it is easy to form a uniform developer layer, and the conductive fine powder is uniformly supplied on the image carrier, It is easy to obtain uniform charging of the image carrier. When the amount of the developer on the developer carrier is too small than the above range, it is difficult to obtain a sufficient image density, and the minute unevenness of the developer layer on the developer carrier causes uneven image density and conductivity. It becomes easy to appear as uneven charging of the image carrier due to uneven supply of fine powder. If the amount of the developer on the developer carrier is more than the above range, the triboelectric charge is apt to be insufficiently imparted to the toner particles, the toner is likely to be scattered, the fog is increased, and the transferability is deteriorated. It becomes easy to hinder the charging of the image carrier.

Also, 5 to 25 g / m ² on the developer carrying member.
It is more preferable to form the developer layer of. By forming a developer layer of 5 to 25 g / m ² on the developer carrier,
It is easier to impart triboelectric charge to the developer on the developer carrier more uniformly, and the influence of the collected transfer residual toner particles on the triboelectric charge of toner particles near the developer carrier is reduced, resulting in more stable development. A cleaning property can be obtained. When the amount of the developer on the developer carrier is too small than the above range, the collected transfer residual toner particles easily affect the triboelectrification of the toner particles in the vicinity of the developer carrier, and the friction of some toner particles is reduced. In some cases, the developer layer becomes uneven due to excessive charging, and the transferability of the transfer residual toner particles becomes uneven. When the amount of the developer on the developer carrier is more than the above range, the collected transfer residual toner particles are conveyed to the developing section again without being sufficiently triboelectrically charged again, and are used for the development. By doing so, fogging is more likely to occur.

Further, in the present invention, the surface of the developer carrying member carrying the developer may move in the same direction as the moving direction of the image carrying member or may move in the opposite direction. . When the moving directions are the same, it is desirable that the moving speed is 100% or more relative to the moving speed of the image carrier.
If it is less than 100%, the image quality may deteriorate.

The moving speed ratio of the moving speed of the surface of the developer carrying member to the moving speed of the surface of the image carrying member is 100% or more (the moving speed of the surface of the developer carrying member is higher than the moving arrest rate of the surface of the image carrying member or If the same), the toner particles are sufficiently supplied from the developer carrying member side to the image carrying member side, so that it is easy to obtain a sufficient image density and the conductive fine powder is sufficiently supplied. It is possible to obtain good chargeability of the body.

Further, it is more preferable that the moving speed of the surface of the developer carrying member is 1.05 to 3.0 times the moving speed of the surface of the image carrying member. As the moving speed ratio increases, the amount of toner supplied to the development site increases, the frequency of toner desorption increases with respect to the latent image, and unnecessary parts are scraped off and applied to necessary parts repeatedly. The collectability of the residual toner particles is improved, and it is possible to more reliably suppress the occurrence of pattern ghosts due to defective collection. Furthermore, an image faithful to the latent image can be obtained. Further, in the contact development process, as the moving speed ratio increases, the collectability of the transfer residual toner particles is further improved due to the sliding friction between the image bearing member and the developer bearing member. However, if the moving speed ratio greatly exceeds the above range, fogging due to scattering of the developer from the developer carrying member and image stain are likely to occur, and the image carrying member or the developer carrying member is rubbed by rubbing in the contact development process. Wear and abrasion tend to shorten the life. When the developer layer thickness regulating member that regulates the amount of the developer on the developer carrier is in contact with the developer carrier through the developer, the developer layer thickness regulating member or the developer carrier is It is easy to shorten the life due to abrasion and scraping due to rubbing. From the above viewpoint, the moving speed of the surface of the developer carrying member is 1.1 to the moving speed of the surface of the image carrying member.
It is more preferable that the distance is 2.5 times.

In the present invention, in order to apply the non-contact type developing method, it is preferable to form the developer layer on the developer carrier thinner than a predetermined distance from the image carrier. . According to the present invention, it has become possible to realize development / cleaning image formation using a non-contact type developing method, which has been difficult in the past, with high image quality. In the developing process, the developer layer is not in contact with the image carrier, and the non-contact developing method that visualizes the electrostatic latent image of the image carrier as a toner image is applied. Even if a large amount of fine powder is added to the developer, the development fog does not occur due to the development bias being injected into the image carrier. Therefore, a good image can be obtained.

Further, the developer bearing member is 1 with respect to the image bearing member.
It is preferable that they are installed facing each other with a separation distance of 00 to 1000 μm. If the distance between the developer carrier and the image carrier is too small, the change in the developing characteristics of the developer with respect to the deviation of the distance becomes large.
It becomes difficult to mass-produce image forming apparatuses that satisfy stable image quality. If the distance between the developer bearing member and the image bearing member is larger than the above range, the ability of the toner particles to follow the latent image on the image bearing member is reduced, resulting in lower resolution and lower image density. It is easy to cause deterioration of image quality. Further, the feedability of the conductive fine powder onto the image bearing member is easily lowered, and the charging property of the image bearing member is easily lowered. More preferably, the developer carrier is 100 to 600 μm with respect to the image carrier.
It is to be installed facing each other with a separation distance of. The distance between the developer carrier and the image carrier is 100 to 60.
When the thickness is 0 μm, the transfer residual toner particles in the developing / cleaning step can be more significantly collected. If the separation distance is larger than the above range, the collectability of the transfer residual toner particles to the developing device deteriorates, and fogging due to defective collection is likely to occur.

In the present invention, it is preferable that the development is carried out in a developing step in which an alternating electric field (AC electric field) is formed between the developer carrying member and the image carrying member to carry out the development. The alternating electric field can be formed by applying an alternating voltage between the developer carrying member and the image carrying member. The developing bias to be applied may be a DC voltage with an alternating voltage (AC voltage) superimposed thereon.

As the waveform of the alternating voltage, a sine wave, a rectangular wave, a triangular wave or the like can be appropriately used. Further, it may be a pulse wave formed by periodically turning on / off the DC power supply. Thus, as the waveform of the alternating voltage, a bias whose voltage value changes periodically can be used.

Between the developer carrying member carrying the developer and the image carrying member, at least a peak-to-peak electric field strength of 3 × 10 ⁶ to 10 × 10 ⁶ V / m and a frequency of 100 to 5 are obtained.
It is preferable to form an alternating electric field (alternating electric field) of 000 Hz by applying a developing bias. By forming an AC electric field in the above range by applying a developing bias, the conductive fine powder added to the developer is easily transferred to the image carrier side uniformly, and the conductive fine powder is mediated by the conductive fine powder in the charging section. By obtaining the uniform and dense contact between the contact charging member and the image bearing member, uniform charging of the image bearing member (particularly direct injection charging) can be remarkably promoted. Further, by forming the AC electric field by the developing bias, even if there is a high potential difference between the developer bearing member and the image bearing member, charge injection into the image bearing member does not occur in the developing section, so that the conductive fine powder is Even if a large amount is added to the developer, the development bias does not cause the development fog due to the charge injection into the image carrier, and a good image can be obtained. If the strength of the AC electric field formed by applying a developing bias between the developer carrying member and the image carrying member is too small than the above range, the amount of conductive fine powder supplied to the image carrying member will be insufficient. And the uniform charging property of the image bearing member is likely to decrease. Further, since the developing power is small, an image having a low image density is likely to be obtained. On the other hand, when the strength of the AC electric field is too large, the developing power is too large, and thus the resolution is deteriorated due to the crushing of fine lines, the image quality is deteriorated due to increased fog, and the chargeability of the image carrier is easily deteriorated. Image defects due to leakage of the developing bias to the image carrier are likely to occur. Further, if the frequency of the alternating electric field formed by applying a developing bias between the developer carrier and the image carrier is lower than the above range, the conductive fine powder is uniformly supplied to the image carrier. It is difficult to cause unevenness in uniform charging of the image carrier. When the frequency of the alternating electric field is higher than the above range, the amount of the conductive fine powder supplied to the image carrier tends to be insufficient, and the uniform charging property of the image carrier tends to decrease.

Further, between the developer carrying member carrying the developer and the latent image carrying member, at least a peak-to-peak electric field strength of 4 × 10 ⁶ to 10 × 10 ⁶ V / m and a frequency of 5 were used.
It is more preferable to form an alternating electric field (alternating electric field) of 00 to 4000 Hz by applying a developing bias. By forming the AC electric field in the above range by the developing bias, the conductive fine powder added to the developer is easily transferred to the latent image carrier side uniformly, and the conductive fine powder is uniformly transferred to the latent image carrier after transfer. Powder can be applied, and high transfer residual toner particle recoverability can be maintained even when a non-contact developing method is applied.

If the strength of the AC electric field formed by applying a developing bias between the developer carrying member and the latent image carrying member is too small, the recoverability of the transfer residual toner particles to the developing device will be improved. And the fog is apt to occur due to poor collection. Further, if the frequency of the alternating electric field formed by applying a developing bias between the developer carrying member and the latent image carrying member is lower than the above range, the frequency of toner desorption with respect to the latent image decreases, and The collectability of the transfer residual toner particles to the apparatus is likely to be deteriorated, and the image quality is also likely to be deteriorated. If the frequency of the AC electric field is higher than the above range, the toner particles that can follow the change in the electric field are reduced, so that the collectability of the transfer residual toner particles is deteriorated, and a positive ghost is generated due to poor recovery of the transfer residual toner particles. It will be easier.

In the present invention, the transfer step may be a step in which the toner image formed in the developing step is transferred to the intermediate transfer member and then retransferred to a recording medium such as paper.
That is, the transfer material that receives the transfer of the toner image from the latent image carrier may be an intermediate transfer member such as a transfer drum. When the transfer material is used as an intermediate transfer body, a toner image is obtained by transferring the intermediate transfer body onto a recording medium such as paper again. By applying the intermediate transfer member, the amount of transfer residual toner particles on the latent image carrier can be reduced regardless of various recording media such as thick paper.

Further, in the present invention, it is preferable that the transfer member is in contact with the latent image carrier through the transfer material (recording medium) during transfer.

In the contact transfer step of transferring the toner image on the latent image carrier to the transfer material while contacting the transfer means via the latent image carrier and the transfer material, the contact pressure of the transfer means is the linear pressure 2. It is preferably 94 to 980 N / m, and more preferably 19.6 to 490 N / m. If the contact pressure of the transfer unit is less than the above range, the transfer deviation of the transfer material and transfer failure are likely to occur, which is not preferable. If the contact pressure is higher than the above range, the latent image carrier surface may be deteriorated or toner particles may be attached, and as a result, toner fusion may occur on the latent image carrier surface.

An apparatus having a transfer roller or a transfer belt is preferably used as the transfer means in the contact transfer step. The transfer roller has at least a cored bar and a conductive elastic layer covering the cored bar. The conductive elastic layer is made of an elastic material such as polyurethane rubber or ethylene-propylene-diene polyethylene (EPDM), carbon black, zinc oxide, The electrical resistance value (volume resistivity) is 10 ⁶ to by mixing and dispersing a conductivity-imparting agent such as tin oxide and silicon carbide.
It is preferable that the elastic body is a solid or foamed layer having a medium resistance adjusted to 10 ¹⁰ Ω · cm.

A preferable transfer process condition for the transfer roller is that the contact pressure of the transfer roller is 2.94 to 490 N /
m, and more preferably 19.6 to 294 N / m. When the linear pressure as the contact pressure is smaller than the above range, the transfer residual toner particles increase and the chargeability of the latent image bearing member is easily impaired. If the contact pressure of the transfer means is higher than the above range, the conductive fine powder is easily transferred to the transfer material due to the pressing force, and the supply amount of the conductive fine powder to the latent image carrier or the contact charging member is reduced. By doing so, the effect of accelerating the charging of the latent image bearing member is lowered, and the collectability of the transfer residual toner particles in the development / cleaning is lowered. In addition, toner scattering on the image is increased.

In the contact transfer step of electrostatically transferring the toner image onto the transfer material while bringing the transfer means into contact with the latent image carrier via the transfer material, the applied DC voltage is ± 0.2 to ± 10 k.
V is preferable.

The developing device of the present invention is particularly effectively used for an image forming device having a small-diameter photosensitive member having a diameter of 30 mm or less as a latent image carrier. That is, by not having an independent cleaning process after the transfer process and before the charging process, the degree of freedom in arrangement of each process of charging, exposure, development, and transfer is increased, and it is possible to combine with a small-diameter photoconductor having a diameter of 30 mm or less. Therefore, the image forming apparatus can be downsized and the space can be saved. Even in the case of a belt-shaped photoconductor, the degree of freedom in arrangement in each step is similarly increased, so that a photoconductor belt having a radius of curvature of 25 mm or less at the contact portion can be used in order to achieve downsizing and space saving of the image forming apparatus. It is also effective for the image forming apparatus used.

In the image forming apparatus of the present invention, the process cartridge having at least the latent image carrier and the developing means as described above may be detachably attached to the main body of the image forming apparatus. The process cartridge may further include the charging unit.

[0439]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

First, an example of manufacturing a photosensitive member as a latent image carrier used in the examples of the present invention will be described.

<Example of Photoreceptor Production> A photoreceptor using an organic photoconductive substance for negative charging (hereinafter referred to as “OPC photoreceptor”) was produced. A cylinder of aluminum having a diameter of 24 mm was used as the base of the photoreceptor. The following layers were sequentially laminated on this cylinder by dip coating,
A photoconductor having a structure as shown in FIG. 5 was produced.

The first layer is the conductive layer 12, which is provided to smooth out defects and the like of the aluminum substrate 11 and to prevent generation of moire due to reflection of laser exposure. A resin layer (mainly composed of a powder of tin oxide and titanium oxide dispersed in a phenol resin).

The second layer is a positive charge injection preventing layer 13, which plays a role of preventing the positive charge injected from the aluminum base 11 from canceling out the negative charge charged on the surface of the photosensitive member, and is made of methoxymethylated nylon. 10 ⁶ Ω · cm
It is a medium resistance layer having a thickness of about 1 μm whose resistance is adjusted to some extent.

The third layer is the charge generation layer 14 and has a thickness of about 0.3 μm in which a disazo pigment is dispersed in a propylal resin.
Layer, which generates positive and negative charge pairs upon being exposed to a laser.

The fourth layer is the charge transport layer 15 and has a thickness of about 25 in which a hydrazone compound is dispersed in a polycarbonate resin.
It is a μm layer and is a P-type semiconductor. Therefore, the negative charges charged on the surface of the photoconductor cannot move in this layer, and only the positive charges generated in the charge generation layer can be transported to the surface of the photoconductor.

The fifth layer is the charge injection layer 16, which is made by dispersing conductive tin oxide ultrafine particles and tetrafluoroethylene resin particles having a particle size of about 0.25 μm in a photocurable acrylic resin. Specifically, 100 wt% of tin oxide particles having a particle size of about 0.03 μm, which are doped with antimony to reduce resistance, are further added with 20 wt% of tetrafluoroethylene resin particles, and a dispersant of 1. 2% by mass is dispersed. The coating liquid thus prepared was applied to a thickness of about 2.5 μm by a spray coating method to form the charge injection layer 16.

The volume resistance of the outermost surface layer of the photoreceptor thus obtained was 5 × 10 ¹² Ω · cm, and the contact angle of the photoreceptor surface with water was 102 °.

Next, an example of manufacturing the charging member used in the examples of the present invention will be described.

<Production Example of Charging Member> Diameter 6 mm, length 2
With a 64 mm SUS roller as a core metal, urethane resin, carbon black as conductive particles, a sulfurizing agent,
A urethane foam layer having a medium resistance in which a foaming agent or the like was formulated was formed into a roller shape, and further cut and polished to adjust the shape and surface property.
In this way, a charging roller having a flexible urethane roller having a diameter of 12 mm and a length of 234 mm was manufactured.

The charging roller thus obtained had a urethane foam roller resistance of 10 ⁵ Ω · cm and a hardness of Asker C
The hardness was 30 degrees.

<Production Example of Toner Particles Ts-1> 100 parts by mass of styrene-butyl acrylate-butyl maleic acid half ester copolymer (Tg 63 ° C., molecular weight: Mp12000, Mn6500, Mw230,000) Magnetic iron oxide (average) Particle diameter 0.22 μm, coercive force (Hc) 5.2 kA / m in magnetic field of 795.5 kA / m, saturation magnetization (σs) 85 Am ² / kg, residual magnetization (σr) 5.0 Am ² / kg) 90 parts by mass Monoazo iron complex (negative charge control agent) 2 parts by mass Low molecular weight ethylene-propylene copolymer 4 parts by mass The above materials were mixed in a blender, and the mixture was melt-kneaded by an extruder heated to 130 ° C. to obtain The obtained kneaded product was cooled, coarsely pulverized, and then finely pulverized using a fine pulverizer using a jet stream. Furthermore, the finely pulverized product thus obtained is strictly classified by a multi-division classifier utilizing the Coanda effect, and the weight average particle size 7 is obtained from the volume-based particle size distribution in the particle size range of 0.60 μm or more and less than 159.21 μm. ．
9 μm toner particles Ts-1 were obtained. Toner particles Ts-
The resistance of No. 1 was 10 ¹⁴ Ω · cm or more.

The circularity distribution was measured by a method using a flow type particle image analyzer FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.) as described in the embodiment of the invention. More specifically, a hard glass screw cap bottle having an inner diameter of 30 mm and a height of 65 mm (for example, a screw cap bottle SV-30 for 30 ml made by Nichiden Rika Glass Co., Ltd.) is filtered to remove fine dust (circle equivalent). Diameter 0.60 μm or more 159.
The number of particles in the particle size range of less than 21 μm is preferably 20 or less measured in 10 ³ cm ³ and 10 ml of diluted surfactant (preferably alkylbenzene sulfonate is used in water to remove fine dust). A few drops). The particle concentration of the measurement sample is 7,000 for the particles in the diameter range equivalent to the measurement circle.
Add an appropriate amount (for example, 0.5 to 20 mg) so that the number becomes 10000 pieces / 10 ³ cm ³ and disperse for 3 minutes with an ultrasonic homogenizer (output 50 W, frequency 20 kHz, ULTRASONICHOMO Co., Ltd.).
6mm diameter step type tip is applied to GENIZERUH-50, and the scale of power control volume is 7
Particles having a circle-equivalent diameter of 0.60 μm or more and less than 159.21 μm, using a sample dispersion liquid that has been subjected to treatment with a dispersion force of about half of the maximum output when using the same chip). The particle size distribution and the circularity distribution were measured.

From the obtained particle size distribution, the content (number%) of particles in the particle size range of 1.00 μm or more and less than 2.00 μm and the circularity were determined. Table 2 shows the respective physical properties of the toner particles Ts-1.

<Production Example Ts-2 of Toner Particles> The coarsely pulverized product obtained in Production Example Ts-1 of toner particles was finely pulverized by a mechanical pulverizer. The obtained finely pulverized product is classified by a multi-division classifier to obtain toner particles Ts-2 having a weight average particle size of 6.8 μm which is obtained from a volume-based particle size distribution in a particle size range of 0.60 μm or more and less than 159.21 μm. Obtained. The resistance of the toner particles was 10 ¹⁴ Ω · cm or more.

<Production Example Ts-3 of Toner Particles> The classified product obtained in Production Example Ts-2 of toner particles was subjected to thermomechanical impact force using the toner particle spheroidizing treatment apparatus shown in FIGS. 6 and 7. Spheroidizing treatment by repeatedly giving
Weight average particle size 6.5μ obtained from volume-based particle size distribution in the particle size range of 0.60 μm or more and less than 159.21 μm
m toner particles Ts-3 were obtained.

<Production Example Ts-4 of Toner Particles> The classified product obtained in Production Example Ts-3 of toner particles was subjected to a spheroidizing treatment by passing it through hot air at 300 ° C. momentarily to give a weight average particle diameter of 6 Magnetic toner particles Ts-4 having a particle size of 0.9 μm were obtained. The magnetic toner particles Ts-4 had a resistance of 10 ¹⁴ Ω · cm.

[0457]   <Production Example Tp-1 of Toner Particles> -Polyester resin (Tg 60 ° C, acid value 20 mg KOH / g, hydroxyl value 30 mg KOH / g, molecular weight: Mp7000, Mn3000, Mw55000)   100 parts by mass Magnetic iron oxide (average particle size 0.20 μm, Hc9. 2 kA / m, σs82 Am^Two/ Kg, σr11.5Am^Two/ Kg) 90 quality Quantity part ・ Monoazo iron complex (negative charge control agent) 2 parts by mass ・ Low molecular weight ethylene-propylene copolymer 4 parts by mass The above materials were prepared in the same manner as in the toner particle production example Ts-1.
For melt kneading, coarse pulverization, and fine pulverizer using jet stream
Finely pulverized and classified, 0.60 μm or more 159.2
Calculated from volume-based particle size distribution in the particle size range of less than 1 μm
To obtain toner particles Tp-1 having a weight average particle diameter of 8.1 μm.
It was The toner particle Tp-1 has a resistance of 10 ¹⁴Ω · cm or less
Was on.

<Production Example Tp-2 of Toner Particles> The coarsely pulverized product obtained in Production Example Tp-1 of toner particles was finely pulverized by a mechanical pulverizer. The obtained finely pulverized product is classified by a multi-division classifier to obtain toner particles Tp-2 having a weight average particle size of 7.0 μm, which is obtained from a volume-based particle size distribution in a particle size range of 0.60 μm or more and less than 159.21 μm. Obtained. The resistance of the toner particles was 10 ¹⁴ Ω · cm or more.

<Production Example Tp-3 of Toner Particles> The classified product obtained in Production Example Tp-2 of toner particles was subjected to thermomechanical impact force using the toner particle spheroidizing treatment apparatus shown in FIGS. 6 and 7. Spheroidizing treatment by repeatedly giving
Weight average particle size 6.7μ obtained from volume-based particle size distribution in the particle size range of 0.60 μm or more and less than 159.21 μm
m toner particles Tp-3 were obtained.

<Production Example Tp-4 of Toner Particles> The classified product obtained in Production Example Tp-3 of toner particles was subjected to a spheronizing treatment by instantaneously passing hot air at 300 ° C. to obtain a weight average particle diameter of 7 Magnetic toner particles Tp-4 of 0.2 μm were obtained. The magnetic toner particles Tp-4 had a resistance of 10 ¹⁴ Ω · cm.

Each of the toner particles Ts-1 to Ts-4 and Tp-
Table 2 shows typical physical property values of 1 to 4.

[0462]

[Table 2]

<Production Example I-1 of Inorganic Fine Powder> Hydrophobic dry silica fine powder treated with hexamethyldisilazane and then with dimethyl silicone oil was converted into inorganic fine powder I-
It was set to 1. The number average diameter of the primary particles of this inorganic fine powder I-1 was 12 nm, and the BET specific surface area was 120 m ² / g.

<Example I-2 of Inorganic Fine Powder> A dry silica fine powder treated with hexamethyldisilazane was used as an inorganic fine powder I-.
It was set to 2. The number average diameter of primary particles of this inorganic fine powder I-2 was 16 nm, and the BET specific surface area was 170 m ² / g.

Table 3 shows typical physical properties of the above inorganic fine powders I-1 to I-2.

[0466]

[Table 3]

<Examples of Conductive Fine Particles C-1 to 3> Zinc oxide having a volume average particle diameter of 0.07 μm, 1.52 μm, and 2.03 μm was used as conductive fine particles C-1, C-2, and C-3. . The resistance of the conductive fine particles measured by the tablet method described in the embodiment of the invention is 1.2 × 10 ³ Ω · c, respectively.
m, 8.9 × 10 ³ Ω · cm, 2.7 × 10 ⁴ Ω · cm
Met.

<Examples of Conductive Fine Particles C-4 to 6> Tin oxide having a volume average particle diameter of 0.50 μm, 1.15 μm and 5.22 μm was used as the conductive fine particles C-4, C-5 and C-6. . The resistance of the conductive fine particles measured by the tablet method described in the embodiment of the invention is 7.3 × 10 ⁴ Ω · c, respectively.
m, 1.2 × 10 ⁵ Ω · cm, 1.8 × 10 ⁷ Ω · cm
Met.

<Example C-7 of conductive fine particles> Particle size: about 0.1
Conductive fine particles in which 50% by mass of tin oxide was attached to titanium oxide powder of μm were designated as conductive fine particles C-7. The resistance of the conductive fine particles measured by the tablet method described in the embodiment of the invention was 3.1 × 10 ² Ω · cm.

Table 4 shows typical physical properties of the above conductive fine particles C-1 to C-7.

[0471]

[Table 4]

<Manufacturing Example Rs-0 of Developer> The magnetic toner particle Ts-1 obtained in Manufacturing Example Ts-1 of toner particle is 1
1.23 parts by mass of the inorganic fine powder I-1 was added to 00 parts by mass and uniformly mixed by a mixer to obtain a developer Rs-0.

0.60 μ of the obtained magnetic developer Rs-0
The number-based particle size distribution in the particle size range of m to less than 159.21 μm was measured by a method using a flow type particle image analyzer FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.) as described in the toner particle production example. . Table 5 shows the respective physical properties of the developer Rs-0.

<Production Example Rs-1 of Developer> The magnetic toner particles Ts-1 obtained in Production Example Ts-1 of toner particles are
1.23 parts by mass of the inorganic fine powder I-1 and 1.03 parts by mass of the conductive fine particles C-4 were added to 00 parts by mass, and uniformly mixed by a mixer to obtain a developer Rs-1.

<Production Example Rs-2 to 7 of Developer> In Production Example Rs-1 of Developer, conductive fine particles C-4 are respectively added to C-5, C-2, C-3, C-7 and C. Developers Rs-2, Rs-3, Rs-4, Rs-5, and Rs- in the same manner as in Developer Production Example RS-1, except that C-6 and C-1 were used.
6, Rs-7 was obtained.

<Developer Production Examples Rs-8 to 10> In Developer Production Example Rs-1, toner particles Ts-2, Ts-3, and Ts-4 were used instead of the toner particles Ts-1. Developers Rs-8, Rs-9, and Rs-10 were obtained in the same manner as in Developer Production Example Rs-1 except for the above.

<Manufacturing Example Rp-0 of Developer> One part of the magnetic toner particles Tp-1 obtained in Manufacturing Example Tp-1 of toner particles is used.
1.23 parts by mass of the inorganic fine powder I-2 was added to 00 parts by mass and uniformly mixed by a mixer to obtain a developer Rp-0.

<Manufacturing Example Rp-1 of Developer> The magnetic toner particles Tp-1 obtained in Manufacturing Example Tp-1 of toner particles are
1.23 parts by mass of the inorganic fine powder I-2 and 1.03 parts by mass of the conductive fine particles C-4 were added to 00 parts by mass, and uniformly mixed by a mixer to obtain a developer Rp-1.

<Production Example Rp-2 to 7 of Developer> In Production Example Rp-1 of the developer, conductive fine powder C-4 was added to C-5, C-2, C-3, C-7, respectively. Developers Rp-2, Rp-3, Rp-4, Rp-5, Rp-in the same manner as in Developer Production Example Rp-1 except that C-6 and C-1 were used.
6, Rp-7 was obtained.

<Production Example Rp-8 to 10 of Developer> In Production Example Rp-1 of the developer, toner particles Tp-2, Tp-3 and Tp-4 were used instead of the toner particles Tp-1. Developers Rp-8, Rp-9, and Rp-10 were obtained in the same manner as in Developer Production Example Rp-1 except for the above.

The above developers Rs-0 to Rp-0.
Weight average particle diameter of -10, 1.00 μm or more and 2.00 μm
Table 5 shows the content (number%) of particles in the particle size range of less than 3.00 μm and less than 8.96 μm.

[0482]

[Table 5]

<Production Example of Developer Carrier Dp-l-1> As the nitrogen-containing heterocyclic compound which is a positively chargeable substance, a compound represented by the general formula B can be used.
Imidazole compound particles having a number average particle diameter of 3 μm represented by −1 were used.

[0484]

[Chemical 16]

Resol type phenolic resin solution (containing 50% methanol) 400 parts by mass Nitrogen-containing heterocyclic compound B-1 (imidazole compound) 15 parts by mass isopropyl alcohol 335 parts by mass The above materials are used as glass particles having a diameter of 2 mm. After sand mill dispersion for 1 hour, glass particles were separated by sieving, this resin solution was applied on a SUS plate with a bar coater (# 60), and this was heated and cured at 150 ° C / 30 minutes to give a sample. A plate was made. When this sample plate was grounded, it was left overnight in an environment of 23 ° C. and relative humidity of 60%, and the triboelectrification polarity with iron powder was measured as described above. .

As the electrically conductive spherical particles, the number average particle size is 7.
A number average particle diameter of 2 was obtained by using a likai machine (automatic mortar, manufactured by Ishikawa Industry Co., Ltd.) on 100 parts by mass of spherical phenol resin particles of 8 μm.
14 parts by mass of coal-based bulk mesophase pitch powder having a particle size of μm or less was uniformly coated, heat-stabilized in air at 280 ° C., and then graphitized by firing at 2000 ° C. in a nitrogen atmosphere, and further classified. Number average particle size 7.2μ
m spherical conductive carbon particles were used. 20 parts by mass of conductive carbon black 80 parts by mass of graphite having a number average particle diameter of 3.4 μm 400 parts by mass of a resol type phenol resin solution (containing 50% of methanol) 400 μm of nitrogen-containing heterocyclic compound B-1 (imidazole compound) 1
5 parts by mass, spherical carbon particles (number average particle size 7.2 μm) 10 parts by mass, isopropyl alcohol 125 parts by mass The above materials were sand mill dispersed with zirconia particles having a diameter of 2 mm for 3 hours, and then the zirconia particles were separated by sieving. , Solid content adjusted to 40% with isopropyl alcohol, coating liquid (c (carbon) / GF (graphite) / B
(Phenol resin) / CA (Nitrogen-containing heterocyclic compound B-
1) / R (spherical particles) = 0.2 / 0.8 / 2.0 / 0.
15 / 0.1) was obtained. The coating solution was coated on an insulating sheet with a bar coater and dried, cut into a regular shape, and measured with a low-resistivity meter Lorester (manufactured by Mitsubishi Chemical Corporation) to find that the volume resistivity was 3.52 Ω. It was cm.

A coating film of 15 μm was formed on the Al cylinder having a diameter of 16 mm by spraying this coating material, and then heated and cured by a hot air dryer at 150 ° C./30 minutes to prepare a developer carrying member Dp-l-1. did. Ra on the surface of the conductive coating layer on the developer carrying member was changed to Surfcoder SE-330.
0 (manufactured by Kosaka Laboratory) was measured at 6 points with an evaluation length of 4 mm, and the average value thereof was calculated to be Ra = 1.21 μm.

<Preparation Example of Developer Carrier Dp-l-2 to 4>
As the nitrogen-containing heterocyclic compound, imidazole compound particles represented by the general formulas B-2 to 4 and having a number average particle diameter of 3 μm were used.

[0489]

[Chemical 17]

When the triboelectrification polarity with respect to iron powder was measured in the same manner as in Production Example Dp-1-1 of developer carrying body, all showed positive electrification property.

This is dispersed and coated in the same manner as in Developer Production Example Dp-l-1 to give a developer support Dp-1-2.
4 were produced and the same evaluation was performed.

<Developer Carrier Preparation Example Dp-n-1> 600 parts by mass of resol type phenolic resin solution (containing 50% methanol) 20 parts by mass of nitrogen-containing heterocyclic compound B-1 (imidazole compound) isopropyl alcohol 447 parts by mass The above material was subjected to sand mill dispersion with glass particles having a diameter of 2 mm for 1 hour, and then the glass particles were separated by sieving, and the resin solution was applied onto a SUS plate with a bar coater (# 60), Heat and cure this at 150 ° C / 30 minutes,
Make a sample plate. The sample plate is grounded and left overnight at 23 ° C. and 60% relative humidity.
As described in the embodiment of the invention, the triboelectric charging polarity with the iron powder was measured, and the result showed positive charging property. -Conductive carbon black 20 parts by mass-Graphite having a number average particle diameter of 3.4 μm 80 parts by mass-Resol type phenol resin solution (containing 50% methanol) 600 parts by mass-Nitrogen-containing heterocyclic compound B-1 (imidazole compound) 20 Parts by mass / spherical carbon particles (number average particle diameter 3.7 μm) 10 parts by mass / isopropyl alcohol 700 parts by mass Add zirconia beads having a diameter of 2 mm as media particles to the above material, disperse in a sand mill for 2 hours, and use a sieve. The beads were separated, and the solid content was adjusted to 40% with isopropyl alcohol, and the coating liquid (c (carbon) / GF (graphite) / B (binder resin) / CA (nitrogen-containing heterocyclic compound B-1) / R (Spherical particle) = 0.2 / 0.8 / 3.
0 / 0.2 / 0.1) was obtained.

This was dispersed and coated in the same manner as in the developer carrying body preparation example Dp-l-1, to give a developer carrying body Dp-n-1.
Was prepared and the same evaluation was performed.

<Preparation Example of Developer Carrier Dp-n-2 to 4>
Developer carrier Dp-n-1 was the same as Developer carrier manufacture example Dp-n-1, except that the nitrogen-containing heterocyclic compound was replaced with B-2 to B-4. -N
-2-4 were produced and the same evaluation was performed.

[0495]

[Table 6]

<Developer Carrier Production Example Dm-l-1> Resol-type phenol resin (solid content 50%) 320 parts by mass Methyl methacrylate-dimethylaminoethyl methacrylate copolymer P-1 (solid content 50%) (Mole ratio 90:10, Mw = 10,200, Mn = 4,500, Mw / Mn = 2.3) 80 parts by mass / MEK 400 parts by mass Sand mill dispersion of the above materials with glass particles having a diameter of 2 mm for 1 hour. After that, the glass particles are separated by sieving, the resin solution is applied onto a SUS plate by a bar coater (# 60), and this is heated and cured at 150 ° C./30 minutes to prepare a sample plate. The sample plate is grounded and left overnight at 23 ° C. and 60% relative humidity.
As described in the embodiment of the invention, the triboelectric charging polarity with the iron powder was measured, and the result showed positive charging property.

As the spherical particles, the number average particle diameter is 7.8 μm.
100 parts of spherical phenolic resin particles of No. 1 were uniformly coated with 14 parts of coal-based bulk mesophase pitch powder having a number average particle diameter of 2 μm or less using a Laikai machine (automatic mortar, manufactured by Ishikawa Plant), and heat-stabilized in air at 280 ° C. Spherical conductive carbon particles having a number average diameter of 11.7 μm obtained by graphitizing by firing at 2000 ° C. in a nitrogen atmosphere after the chemical conversion treatment and further classification were used. Carbon black 20 parts by mass Crystalline graphite having a number average particle size of 4.8 μm 80 parts by mass Resol-type phenol resin (solid content 50%) 320 parts by mass Methyl methacrylate-dimethylaminoethyl methacrylate copolymer P-1 ( Solid content 50%) (molar ratio 90:10, Mw = 10,200, Mn = 4,500, Mw / Mn = 2.3) 80 parts by mass Spherical carbon particles (number average particle size 11.7 μm) 30 parts by mass Parts / MEK 130 parts by mass Sand mill dispersion of the above materials with φ2 mm zirconia particles for 3 hours, and then separating the zirconia particles by sieving, adjusting the solid content to 40% with MEK, and coating liquid (c (carbon)) / GF (graphite) / B (phenolic resin) / D (copolymer P-1) / R (spherical particles) = 0.2
/0.8/1.6/0.4/0.3) was obtained. This coating solution was coated on an insulating sheet with a bar coater and dried, cut into a regular shape, and measured with a low resistivity meter, Lorester (manufactured by Mitsubishi Chemical Corporation). The volume resistivity was 5.0.
It was 3 Ω · cm.

A coating having a thickness of 15 μm was formed on the Al cylinder having a diameter of 16 mm by a spray method with this coating material, and then heated and cured at 150 ° C./30 minutes by a hot air drier to prepare a developer carrying member D-1. Ra on the surface of the conductive coating layer on the developer carrying member was measured at 6 points with a surf coder SE-3300 (manufactured by Kosaka Laboratory) at an evaluation length of 4 mm, and the average value was calculated. Ra = 1. It was 27 μm.

<Developer Carrier Production Example Dm-l-2 to 4>
Copolymer P- used in the developer carrier production example Dm-l-1
In place of 1, using the copolymers P-2 to 4 in which the molecular weight of the copolymer and the molar ratio of methyl methacrylate and dimethylaminoethyl methacrylate were changed, the same procedure as in Dm-l-1 The developer carrying member Dm-l-
Nos. 2 to 4 were produced and evaluated in the same manner as in the developer carrier production example Dm-l-1.

Copolymer used for developer carrier Dm-1-2: methyl methacrylate-dimethylaminoethyl methacrylate copolymer P-2 (solid content 40%) (molar ratio 90:
10, Mw = 40,000, Mn = 19000, Mw
/Mn=2.1) Copolymer used for developer carrier Dm-l-3 Methyl methacrylate-dimethylaminoethyl methacrylate copolymer P-3 (solid content 40%) (molar ratio 90:
10, Mw = 3,700, Mn = 2,300, Mw / M
n = 1.6) Copolymer methyl methacrylate-dimethylaminoethyl methacrylate copolymer P-4 (solid content 40%) used for the developer carrier Dm-l-4 (molar ratio 70:
30, Mw = 8,500, Mn = 2,900, Mw / M
n = 2.9) <Developer carrier production example Dm-n-1> Resol type phenol resin (solid content 50%) 460 parts by mass Methyl methacrylate-dimethylaminoethyl methacrylate copolymer P-1 (solid content 50%) 140 parts by mass / MEK 400 parts by mass The above materials are sand mill-dispersed for 1 hour with glass particles having a diameter of 2 mm, and then the glass particles are separated by sieving, and the resin solution is spread on a SUS plate by a bar. Coater (#
60) is applied, and this is heated and cured at 150 ° C./30 minutes to prepare a sample plate. The sample plate is grounded and left overnight at 23 ° C. and 60% relative humidity. As described in the embodiment of the invention, the triboelectric charging polarity with the iron powder was measured, and the result showed positive charging property. Carbon black 20 parts by mass Crystalline graphite having a number average particle size of 4.8 μm 80 parts by mass Resol-type phenol resin (solid content 50%) 460 parts by mass Methyl methacrylate-dimethylaminoethyl methacrylate copolymer P-1 ( Solid content 50%) 140 parts by mass / spherical carbon particles (number average particle size 7.2 μm) 30 parts by mass / MEK 130 parts by mass Zirconia beads having a diameter of 2 mm are added as media particles to the above material, and dispersed by a sand mill for 2 hours. , Separate the beads using a sieve, adjust the solid content to 40% with MEK, and apply the coating liquid (c (carbon) / GF (graphite) / B
(Binder resin) / D (copolymer P-1) / R (spherical particles)
= 0.2 / 0.8 / 2.3 / 0.7 / 0.3) was obtained.

This was dispersed and coated in the same manner as in Production Example of Developer Carrier Dm-l-1, to give a developer carrier Dm-n-1.
Was prepared and the same evaluation was performed.

<Developer Carrier Production Example Dm-n-2 to 4>
Developer carrier preparation example Dm-n-1, except that the copolymer was replaced with P-2 to P-4.
The developer carrying members Dm-n-2 to 4 were prepared in the same manner as in -n-1, and the same evaluation was performed.

[0503]

[Table 7]

<Production Example of Developer Carrier Df-1-1><Production of Charge Control Resin> -Methanol: 300 parts by mass-Toluene: 100 parts by mass-Styrene: 468 parts by mass-2-Ethylhexyl acrylate: 90 parts by mass・ 2-Acrylamido-2-methylpropanesulfonic acid: 42 parts by mass ・ Lauroyl peroxide: 6 parts by mass The above raw materials were charged into a flask and equipped with a stirrer, a temperature measuring device and a nitrogen introducing device, and under a nitrogen atmosphere at 65 ° C. The solution was polymerized in (1) and held for 10 hours to complete the polymerization reaction.
The obtained polymer was dried under reduced pressure and pulverized to obtain a charge control resin F-1 having a weight average molecular weight of 10,000.

The charge control resins F-2 and F-3 were obtained by changing the composition ratio as shown in Table 8 below.

Charge control resin solution F-1 was prepared by dissolving 50 parts by weight of charge control resin F-1 in 50 parts by weight of methyl ethyl ketone. -Phenolic resin (containing 50% of methanol) 340 parts by mass-Charge control resin solution F-1 (containing 50% of MEK) 60 parts by mass-Isopropyl alcohol 267 parts by mass Sand mill dispersion of the above materials with glass particles having a diameter of 2 mm for 1 hour. After that, the glass particles are separated by sieving, the resin solution is applied onto a SUS plate by a bar coater (# 60), and this is heated and cured at 150 ° C./30 minutes to prepare a sample plate. The sample plate is grounded and left overnight at 23 ° C. and 60% relative humidity.
As described in the embodiment of the invention, the triboelectric charging polarity with the iron powder was measured, and the result showed positive charging property. Carbon black 20 parts by mass Crystalline graphite having a number average particle size of 5.5 μm 80 parts by mass Phenolic resin (containing 50% methanol) 340 parts by mass Charge control resin solution F-1 (MEK50) % Content) 60 parts by mass / spherical carbon particles (number average particle size 11.7 μm) 20 parts by mass / isopropyl alcohol 120 parts by mass

A coating film of 15 μm was formed on the Al cylinder having a diameter of 16 mm by spraying this coating material, and then it was heated and cured by a hot air dryer at 150 ° C./30 minutes to prepare a developer carrier Df-l-1. did. Ra on the surface of the conductive coating layer on the developer carrying member was changed to Surfcoder SE-330.
0 (manufactured by Kosaka Laboratory) was measured at 6 points with an evaluation length of 4 mm, and the average value thereof was calculated to be Ra = 1.07 μm.

<Developer carrier preparation example Df-1-2> In the developer carrier preparation example Df-1-1, the phenol resin prepared with ammonia as a catalyst and the phenol resin prepared with hexamethylenetetramine as a catalyst were used. A developer carrying member Df-1-2 was prepared in the same manner as in the developer carrying member manufacturing example Df-1-1 except that the resin was used instead, and the same evaluation as in the developer carrying member manufacturing example Df-1-1 was made. I went.

<Developer carrier production example Df-l-3> Charge control resin F- used in developer carrier production example Df-l-1
A developer except that instead of 1, the charge control resin F-2 obtained by changing the composition ratio as shown in Table 8 was used, and the phenol resin produced using ammonia as a catalyst was replaced with a polyamide resin. A developer carrying member Df-l-3 was produced in the same manner as in the carrying member manufacturing example Df-l-1, and the same evaluation as in the developer carrying member manufacturing example Df-l-1 was performed.

<Production Example of Developer Carrier Df-l-4> Charge Control Resin F- used in Production Example of Developer Carrier Df-l-1
A developer except that the charge control resin F-3 obtained by changing the composition ratio as shown in Table 8 was used in place of 1, and the phenol resin produced using ammonia as a catalyst was replaced with a polyurethane resin. Carrier Production Example Df-l-1
A developer carrying member Df-l-4 was prepared in the same manner as described above, and was evaluated in the same manner as in the developer carrying member manufacturing example Df-l-1.

<Developer Carrier Production Example Df-n-1> 500 parts by mass of phenol resin (containing 50% methanol) 100 parts by mass of charge control resin solution F-1 (containing 50% MEK) 400 parts by mass of isopropyl alcohol The above material was subjected to sand mill dispersion with glass particles having a diameter of 2 mm for 1 hour, and then the glass particles were separated by sieving, and the resin solution was applied onto a SUS plate by a bar coater (# 60), and this was applied at 150 ° C. A sample plate is prepared by heating and curing for 30 minutes. The sample plate is grounded and left overnight at 23 ° C. and 60% relative humidity.
As described in the embodiment of the invention, the triboelectric charging polarity with the iron powder was measured, and the result showed positive charging property. Carbon black 20 parts by mass Crystalline graphite having a number average particle diameter of 5.5 μm 80 parts by mass Phenol resin produced with ammonia as a catalyst (containing 50% methanol) 500 parts by mass Charge control resin solution F-1 (MEK50) % Content) 100 parts by mass / spherical carbon particles (number average particle size 7.2 μm) 20 parts by mass / isopropyl alcohol 120 parts by mass Add zirconia beads having a diameter of 2 mm as media particles to the above material, and disperse in a sand mill for 2 hours. The beads were separated using a sieve, the solid content was adjusted to 40% with isopropyl alcohol, and the coating liquid (c (carbon) / GF (graphite) / B (binder resin) / CA (charge control resin F) was used.
-1) / R (spherical particles) = 0.2 / 0.8 / 2.5 /
0.5 / 0.2) was obtained.

This is applied in the same manner as in the developer carrier preparation example Df-l-1 to prepare a developer carrier Df-n-1, which is the same as in the developer carrier preparation example Df-l-1. Was evaluated.

<Developer carrier preparation example Df-n-2> In the developer carrier preparation example Df-n-1, the phenol resin prepared with ammonia as a catalyst and the phenol resin prepared with hexamethylenetetramine as a catalyst were used. A developer carrying member Df-n-2 was prepared in the same manner as in the developer carrying member manufacturing example Df-n-1 except that the resin was used, and the same evaluation as in the developer carrying member manufacturing example Df-n-1 was performed. I went.

<Production Example of Developer Carrier Df-n-3> Charge Control Resin F- used in Production Example of Developer Carrier Df-n-1
A developer except that instead of 1, the charge control resin F-2 obtained by changing the composition ratio as shown in Table 8 was used, and the phenol resin produced using ammonia as a catalyst was replaced with a polyamide resin. A developer carrying member Df-n-3 was prepared in the same manner as the carrying member manufacturing example Df-n-1, and the same evaluation as in the developer carrying member manufacturing example Df-n-1 was performed.

<Developer Carrier Production Example Df-n-4> Charge Control Resin F- used in Developer Carrier Production Example Df-n-1
A developer except that the charge control resin F-3 obtained by changing the composition ratio as shown in Table 8 was used in place of 1, and the phenol resin produced using ammonia as a catalyst was replaced with a polyurethane resin. Carrier Production Example Df-n-1
A developer carrying member Df-n-4 was prepared in the same manner as in, and the same evaluation as in Developer carrying member manufacturing example Df-n-1 was performed.

[0516]

[Table 8]

<Description of Image Forming Apparatus> FIG. 1 is a diagram showing an example of the configuration of the image forming apparatus of the present invention. This image forming apparatus is a laser printer (recording apparatus) of a development / cleaning process (cleanerless system) using a transfer type electrophotographic process. The developer has a process cartridge from which a cleaning unit having a cleaning member such as a cleaning blade has been removed, and a magnetic one-component developer (that is, a magnetic toner having an external additive and magnetic toner particles) is used as the developer. 1 is an example of a non-contact development image forming apparatus arranged such that a developer layer on a carrier and an image carrier are in non-contact with each other.

(1) The structure 1 of the image forming apparatus is a rotary drum type OPC photosensitive member of the photosensitive member manufacturing example 1 as a latent image carrier, and is 1 in the clockwise direction (the direction of the arrow).
It is rotationally driven at a peripheral speed (process speed) of 00 mm / sec.

Reference numeral 2 denotes a charging roller of a charging member manufacturing example as a contact charging member, which comprises a core metal 2a and an elastic layer 2b. The charging roller 2 is arranged so as to be pressed against the photoconductor 1 against elasticity with a predetermined pressing force. Reference numeral n is a charging portion which is a contact portion between the photoconductor 1 and the charging roller 2. In this embodiment, the charging roller 2 is a charging portion n which is a contact portion with the photoconductor 1.
In the counter direction (direction opposite to the moving direction of the surface of the photoconductor) 141 mm / sec (relative moving speed ratio 250%)
It is driven to rotate at a peripheral speed of. Further, the surface of the charging roller 2 was previously coated with the same conductive fine powder m as the conductive fine powder m externally added to the toner particles t so that the coating amount was approximately uniform.

To the core metal 2a of the charging roller 2, a DC voltage of -700V was applied as a charging bias from the charging bias applying power source S1. In this embodiment, the surface of the photoconductor 1 has a potential (−) which is almost equal to the voltage applied to the charging roller 2.
680 V) is uniformly charged by the direct injection charging method. This will be described later.

Reference numeral 3 is a laser beam scanner (exposure device) including a laser diode, a polygon mirror and the like. This laser beam scanner outputs a laser beam (wavelength 740 nm) whose intensity is modulated corresponding to a time series electric digital pixel signal of target image information, and scans and exposes a uniformly charged surface of the photoconductor 1 with the laser beam. To do. By this scanning exposure, an electrostatic latent image corresponding to desired image information is formed on the photoconductor 1.

Reference numeral 4 is a developing device. The electrostatic latent image on the surface of the photoconductor 1 is developed as a toner image by this developing device. The developing device 4 of this embodiment has a negative chargeability of 1 as a developer.
It is a non-contact type reversal developing device using the developer 1 which is a component insulating developer. The developer 4d has toner particles t and conductive fine powder m.

Reference numeral 4a is a non-magnetic developing sleeve having a diameter of 16 mm, which contains a magnet roll 4b as a developer carrying and conveying member. The developing sleeve 4a is used for the photoconductor 1
Are opposed to each other with a separation distance of 300 μm,
At the developing portion (developing area portion) a which is a portion facing the photoconductor 1, the peripheral speed of the photoconductor 1 is set to 120 in the forward direction and the rotational direction of the photoconductor 1.
% Peripheral speed (peripheral speed 120 mm / sec).

On the developing sleeve 4a, the developer 4d is coated in a thin layer by the elastic blade 4c. The layer thickness of the developer 4d on the developing sleeve 4 is regulated by the elastic blade 4c and an electric charge is applied thereto.

The developer 4 coated on the developing sleeve 4a
When the sleeve 4a rotates, the photosensitive drum 1
And is conveyed to the developing unit a, which is a portion facing the sleeve 4a. A developing bias voltage is applied to the sleeve 4a by the developing bias applying power source S2. Development bias voltage is -420V DC voltage and frequency is 1600H.
z, peak-to-peak voltage 1500 V (electric field strength 5 × 10 ⁶ V /
m) was used to superimpose the rectangular alternating voltage, and one-component jumping development was performed between the developing sleeve 4a and the photoconductor 1.

Reference numeral 5 denotes a medium resistance transfer roller as a contact transfer means, which is brought into pressure contact with the photosensitive member 1 at a linear pressure of 98 N / m to form a transfer contact portion b. A transfer material P as a recording medium is fed to the transfer contact portion b from a paper feeding portion (not shown) at a predetermined timing, and a predetermined transfer bias voltage is applied to the transfer roller 5 from a transfer bias applying power source S3. As a result, the toner image on the side of the photoconductor 1 is sequentially transferred onto the surface of the transfer material P fed to the transfer contact portion b.

In this embodiment, the transfer roller 5 has a resistance of 5 ×.
Transfer was carried out by applying a DC voltage of +3000 V using a 10 ⁸ Ωcm one. That is, the transfer material P introduced into the transfer contact portion b is nipped and conveyed by the transfer contact portion b, and the toner images formed and carried on the surface of the photoconductor 1 are sequentially generated by the electrostatic force. Transferred by pressing force.

Reference numeral 6 denotes a fixing device such as a heat fixing system. The transfer material P, which has been fed to the transfer unit b and has received the transfer of the toner image on the side of the photoconductor 1, is separated from the surface of the photoconductor 1 and introduced into the fixing device 6, where it is fixed with the toner image. And is discharged outside the apparatus as an image formed product (print, copy).

In the image forming apparatus of this example, the cleaning unit is removed, and the transfer residual developer (transfer residual toner particles) remaining on the surface of the photoconductor 1 after the transfer of the toner image onto the transfer material P is performed by the cleaning means. Without being removed
As the photoconductor 1 rotates, it reaches the developing portion a via the charging portion n and is developed and cleaned (recovered) in the developing device 4.

In the image forming apparatus of this embodiment, the three process devices of the photoconductor 1, the charging roller 2 and the developing device 4 are collectively constructed as a process cartridge 7 which is detachable from the main body of the image forming device. In the present invention, the combination of process equipment to be a process cartridge is not limited to the above, and is arbitrary. Reference numeral 8 is a process cartridge attachment / detachment guide / holding member.

(2) Behavior of conductive fine powder Conductive fine powder m contained in the developer 4d of the developing device 4
When toner is developed by the developing device 4 for the electrostatic latent image on the photoconductor 1 side, an appropriate amount is transferred to the photoconductor 1 side together with the toner particles t.

The toner image (that is, toner particles) on the photosensitive member 1 is attracted to the transfer material P side, which is a recording medium, and actively transferred at the transfer portion b due to the effect of the transfer bias. However, since the conductive fine powder m on the photoconductor 1 is conductive, it is not positively transferred to the transfer material P side, and is substantially attached and retained on the photoconductor 1 and remains.

In this embodiment, since the image forming apparatus does not have the cleaning step, the transfer residual toner particles and the conductive fine powder remaining on the surface of the photoconductor 1 after the transfer are accompanied by the rotation of the photoconductor 1. Then, it is carried to the charging section n which is a contact section between the photoconductor 1 and the charging roller 2 which is a contact charging member, and adheres to the charging roller 2. Therefore, the photoconductor 1 and the charging roller 2
Direct injection charging of the photoconductor 1 is performed in a state where the conductive fine powder m is present in the contact portion n with.

Due to the presence of the conductive fine powder m, even if the transfer residual toner particles adhere to the charging roller 2, the close contact property and contact resistance of the charging roller 2 to the photosensitive member 1 can be maintained. Direct charging of the photosensitive member 1 by the charging roller 2 can be performed.

That is, the charging roller 2 closely contacts the photoconductor 1 through the conductive fine powder m, and the conductive fine powder m rubs the surface of the photoconductor 1 without any gap. As a result, the charging of the photoconductor 1 by the charging roller 2 can be dominated by stable and safe linear injection charging that does not use a discharge phenomenon, and high charging that cannot be obtained by conventional roller charging or the like. Efficiency is obtained. Therefore, it is possible to apply a potential almost equal to the voltage applied to the charging roller 2 to the photoconductor 1.

Transfer residual toner particles adhering to or mixed with the charging roller 2 are gradually discharged from the charging roller 2 onto the photosensitive member 1, and reach the developing portion a as the surface of the photosensitive member 1 moves, and the developing device 4 Development and cleaning (recovery)
To be done.

For development / cleaning, the photoreceptor 1 is used after transfer.
The toner particles remaining on top of the toner particles are removed from the fogging bias of the developing device (at the developing device during development of the latent image after development after the next charging process and exposure process after the image formation process). It is recovered by the fog-removal potential difference Vback, which is the potential difference between the applied DC voltage and the surface potential of the photoconductor. In the case of reversal development as in the image forming apparatus of this embodiment, this development and cleaning is
This is performed by the action of an electric field that collects toner particles from the dark potential of the photoconductor to the developing sleeve due to the developing bias and an electric field that causes (develops) toner particles from the developing sleeve to the light potential of the photoconductor.

[0538] Further, since the image forming apparatus is operated,
The conductive fine powder m contained in the developer of the developing device 4 moves to the surface of the photoconductor 1 at the developing portion a and is carried to the charging portion n via the transfer portion b as the surface of the photoconductor 1 moves. As a result, new conductive fine powder m is continuously supplied to the charging portion n, so that the conductive fine powder m is reduced in the charging portion n due to dropping or the like, or the conductive fine powder m of the charging portion n is deteriorated. Even in this case, however, it is possible to prevent the chargeability from deteriorating, and the good chargeability of the photoconductor 1 is stably maintained.

Thus, in the image forming apparatus of the contact charging system, the transfer system and the toner recycling process, the simple charging roller 2 is used as the contact charging member, and the uniform charging property is applied to the photoconductor 1 as the image carrier with a low charge. It can be given by voltage. Moreover, even when the transfer residual toner particles reach the charging portion, ozone-less direct injection charging can be stably maintained for a long period of time, and uniform charging property can be provided. Therefore, there is no obstacle due to ozone products, no obstacle due to poor charging, etc., simple configuration,
A low-cost image forming apparatus can be obtained.

As mentioned above, the conductive fine powder impairs the charging property.
The resistance value is 1 × 10 because it does not touch ⁹Ω · cm or less
Need to Resistance value of conductive fine powder is 1 × 10⁹Ω ・
If it is larger than cm, the charging roller 2 will be mediated by conductive fine powder.
Then, the conductive fine powder is brought into close contact with the photosensitive member 1 and the conductive fine powder is transferred to
Even if the surface is rubbed, the charge is sufficiently injected into the photoconductor 1.
Therefore, it is difficult to charge the photoconductor 1 to a desired potential.
Become. In addition, contact development in which the developer directly contacts the photoreceptor 1.
When the device is used, the developer in the developing section a is introduced into the developer.
The photoconductor 1 is charged with a developing bias through the electroconductive fine powder.
If the image is fogged, the image is fogged, the image is missing, or the density is low.
Will occur.

In this embodiment, since the developing device is a non-contact type developing device, the developing bias is not injected into the photoconductor 1 and a good image can be obtained. Further, since no charge is injected into the photoconductor 1 at the developing portion a, a high potential difference such as an AC bias can be provided between the developing sleeve 4a and the photoconductor 1. This facilitates uniform development of the conductive fine powder m, so that the conductive fine powder m can be uniformly applied to the surface of the photoconductor 1 and evenly contacted at the charging portion to obtain good chargeability. Therefore, it becomes possible to obtain a good surface image.

[0542] Due to the lubricating effect (friction reducing effect) of the conductive fine powder present on the contact surface between the charging roller 2 and the photosensitive member 1, the speed difference can be easily and effectively provided between the charging roller 2 and the photosensitive member 1. Can be provided. Due to this lubricating effect,
The friction between the charging roller 2 and the photoconductor 1 can be reduced, the drive torque can be reduced, and the surface of the charging roller 2 or the photoconductor 1 can be prevented from being scraped or damaged. Further, by providing this speed difference, the mutual contact portion (charging portion) n between the charging roller 2 and the photosensitive member 1
In the above, the chances of the conductive fine powder coming into contact with the photoconductor 1 can be significantly increased, and high contact property can be obtained. Therefore,
Good direct injection charging is possible.

In this embodiment, the charging roller 2 is rotationally driven, and its rotation direction is opposite to the moving direction of the surface of the photoconductor 1, so that the photoconductor carried to the charging section n is carried out. The transfer residual toner particles on No. 1 are temporarily collected by the charging roller 2, and the amount of transfer residual toner particles present in the charging portion n is leveled. Therefore, it is possible to prevent occurrence of charging failure due to uneven distribution of the transfer residual toner particles in the charging portion n, and more stable charging property can be obtained.

Further, by rotating the charging roller 2 in the opposite direction, the transfer residual toner particles on the photoconductor 1 are once separated from the photoconductor 1 and charged, whereby direct injection charging can be predominantly performed. Is. Further, the conductive fine powder does not deteriorate due to excessive detachment from the charging roller 2.

<Example L-1> A combination of the developer Rs-1 and the developer carrying member Dp-l-1 was used. The toner cartridge is filled with 120 g of the developer Rs-1, and the evaluation environment is 23 ° C./60%, and the image of 3500 of 5% coverage is obtained.
It was used until the amount of developer in the toner cartridge was reduced by continuous printing of one sheet. 90g as transfer material
/ M ² of A4 copy paper was used. As a result, the image density was sufficiently high, the fog was small, and the developability was not decreased even after the initial printing and after the continuous printing of 3,500 sheets.

After continuous printing of 3,500 sheets, when the portion corresponding to the contact portion n with the photosensitive member was observed on the charging roller, a slight amount of transfer residual toner particles was confirmed, but almost conductive fine particles C- It was covered with 4.

Further, since the conductive fine particles C-4 were present at the contact portion n between the photosensitive member and the charging roller and the resistance of the conductive fine particles C-4 was sufficiently low, the initial value was 3,500.
Image defects due to poor charging did not occur until after continuous printing of one sheet, and good direct injection chargeability was obtained.

Also, by using as the latent image carrier a photoreceptor having a volume resistance of the outermost surface layer of the photoreceptor of 5 × 10 ¹² Ω · cm, an electrostatic latent image can be maintained and a sharp transfer can be achieved. It was possible to obtain the character image of the outline and realize the direct injection electrification that can obtain the sufficient electrification property even after the continuous printing of 3500 sheets.
After direct injection charging after continuous printing of 3500 sheets, the photoconductor potential is -690 against an applied charging bias of -700V.
It was V, no decrease in chargeability was observed from the beginning, and no decrease in image quality due to decrease in chargeability was observed.

Furthermore, in combination with the use of the photoconductor in which the contact angle of water on the surface of the latent image carrier is 102 degrees,
The transfer efficiency was excellent at the initial stage and after continuous printing of 3500 sheets. Considering that the amount of transfer residual toner particles on the photoconductor after transfer is small, the transfer residual toner particles on the charging roller after the continuous printing of 3500 sheets was very small and the fog in the non-image area was From the small amount, it is understood that the collectability of the transfer residual toner particles in the development was good.

[0550] The print image evaluation method will be described below.

(A) Image Density Initially, and after completion of continuous printout of 3500 sheets, evaluation was made by the image density of the first sheet which was left for 2 days and then turned on again. The image density is "Macbeth reflection densitometer"
(Manufactured by Macbeth Co., Ltd.) was used to measure the relative density of a white background portion having a document density of 0.00 with respect to a printout image. The evaluation results are shown in Table 11. In addition, each symbol in Table 11 means the following evaluation, respectively. A: Very good image density (1.40 or more) sufficient to express a graphic image with high quality. B: Good, sufficient image density (1.35 or more and less than 1.40) to obtain non-graphic and high-quality image. C: An image density that is normal and is sufficient to recognize characters (1.20 or more and less than 1.35). D: Bad. Very light image density (less than 1.20).

(B) At the beginning of image fog and after the continuous printout of 3500 sheets, the printout image is sampled, and the fog density is determined from the difference between the whiteness of the white part of the printout image and the whiteness of the transfer paper. (%) Was calculated and the image fog was evaluated. Whiteness is "Reflectometer" (made by Tokyo Denshoku Co., Ltd.)
It was measured by. The evaluation results are shown in Table 11. In addition, Table 1
Each symbol in 1 means the following evaluations. A: Very good, fog (less than 1.5%) which is not generally recognized in the meat limit. B: Fog which is good and cannot be recognized unless seen carefully (1.5% or more and less than 2.5%). C: Normal. Fog is easy to recognize, but acceptable fog (2.5% to less than 4.0%). D: Bad. Fog recognized as image stains (4.0%
that's all).

(C) After developing an image in which a ghost solid white part and a solid black part are adjacent to each other, a halftone image is developed, and the difference in density caused by the boundary between the solid white part and the solid black part appearing on the halftone image is visually observed. And observed according to the following criteria. A: No difference in light and shade is seen. B: A slight shade difference is seen. C: Some difference in light and shade can be seen, but practical use is possible. D: A difference in light and shade is noticeable.

(D) Transferability The transferability was evaluated at the initial stage and after the completion of printing out 3500 sheets. Transferability was measured by taping the transfer residual toner particles on the photoconductor during solid black image formation with mylar tape, and peeling off the mylar tape from the Macbeth density of the tape. The value was evaluated by subtracting the Macbeth concentration. The evaluation results are shown in Table 11. In addition, each symbol in Table 11 means the following evaluation, respectively. A: Very good (less than 0.05) B: Good (0.05 or more and less than 0.10) C: Normal (0.10 or more and less than 0.20) D: Bad (0.20 or more) (e ) Chargeability of image carrier After printing about 40 to 50 sheets and after continuously printing out 3500 sheets, the photoreceptor is charged as usual and the surface potential of the photoreceptor at that time is detected at the developing device position. Was arranged and measured, and the chargeability of the image bearing member was evaluated by the difference in potential at both time points. The evaluation results are shown in Table 11.
The smaller the difference, the greater the decrease in the chargeability of the latent image carrier.

(F) Pattern collection failure After continuously printing out the same pattern of vertical lines (repeating vertical lines of 2 dots 98 spaces), a printout test of a halftone image (repeating horizontal lines of 2 dots 3 spaces) was conducted. It was visually evaluated whether or not the light and shade corresponding to the pattern of the vertical line was generated on the halftone image. The evaluation results are shown in Table 11. In addition, each symbol in Table 11 means the following evaluation, respectively. A: Very good (non-occurrence) B: Good (slightly light and shade is observed) C: Normal (thickness unevenness occurs, but it is within the practically acceptable level) D: Poor (lightness unevenness is remarkable) (G) Image stain The image stain was evaluated by visually observing the image after fixing and based on the following evaluation criteria. Table 11 shows the evaluation results.
Shown in. A: Not generated. B: A slight occurrence. The effect on the image is extremely slight. C: Occurred to some extent. It is a practically acceptable level. D: Image stain is remarkable.

The results are shown in Table 1 as the evaluation of Example L-1.
Shown in 1.

<Examples L-2 to 60, 85 to 108> Evaluations were made in the same manner as in Example L-1 with the combinations of the developers and the developer carriers shown in Tables 9 and 10. The results are shown in Table 1.
1 to 13 and 14 to 15.

<Example L-61 to 72> Example L-with the combination of the developer and the developer carrier as shown in Table 10.
Evaluation was performed in the same manner as 1. The results are shown in Table 13. Fog was rather abundant from the beginning, and poor pattern collection was a little bad. The decrease in the chargeability of the image bearing member after the continuous printing of 3,500 sheets was slightly large, but it was within the allowable range for practical use.

<Examples L-73 to 84> Examples L-73 to 84 were prepared by combining the developers and developer carriers shown in Table 10 with each other.
Evaluation was performed in the same manner as 1. The results are shown in Table 14. Although the image density was slightly low from the initial stage and the occurrence of defective pattern collection was observed, it was within the allowable range for practical use.

<Comparative Example L-0> Developer Rs-0 in which conductive fine powder was not externally added, and developer carrier Dp-1.
When evaluated with a combination of -1, the chargeability of the image bearing member was greatly reduced and the fog was worsened.

<Comparative Examples L-1 to 9, 22> Diameter 16 mm
Was blasted with # 80 amorphous alumina particles, and a developer carrier having Ra = 0.32 was used. The developers were evaluated in the combinations of Tables 9 and 10 in the same manner as in Example L-1. The results are shown in Tables 11 to 15. The image density was low.

<Comparative Examples L-10 to 21> By combining a developer and a developer carrier as shown in Table 10, Example L-
Evaluation was performed in the same manner as 1. The results are shown in Table 15. The conductive fine powder on the surface of the toner particles was liable to be lost, so that the chargeability of the image bearing member was greatly reduced, and fog and image stain were also noticeable.

[0563]

[Table 9]

[0564]

[Table 10]

[0565]

[Table 11]

[0566]

[Table 12]

[0567]

[Table 13]

[0568]

[Table 14]

[0569]

[Table 15]

<Examples N-1 to 60, 85 to 108> Evaluations were made in the same manner as in Example L-1 with the combinations of the developer and the developer carrier shown in Tables 16 and 17. The results are shown in Tables 18-21.

<Examples N-61 to 72> Example L-with the combination of the developer and the developer carrier as shown in Table 17.
Evaluation was performed in the same manner as 1. The results are shown in Table 20. Fog was rather abundant from the beginning, and poor pattern collection was a little bad. The decrease in the chargeability of the image bearing member after the continuous printing of 3,500 sheets was slightly large, but it was within the allowable range for practical use.

<Examples N-73 to 84> Examples L-73 to 84 were combined with the combination of the developer and the developer carrier as shown in Table 17 to obtain Example L-.
Evaluation was performed in the same manner as 1. The results are shown in Table 21. Although the image density was slightly low from the initial stage and the occurrence of defective pattern collection was observed, it was within the allowable range for practical use.

<Comparative Example N-0> Developer without external addition of conductive fine powder Production Example Rp-0 / Developer carrier Dp-n
When evaluated with a combination of -1, the chargeability of the image bearing member was greatly reduced and the fog was worsened.

<Comparative Examples N-1 to 9, 22> Comparative Example L-1
Using the Al blast developer carriers of Nos. 9 and 22, the developers were evaluated in the combinations of Tables 16 and 17 in the same manner as in Example L-1. The results are shown in Tables 18-22. The image density was low.

<Comparative Examples N-10 to 21> In the combination of the developer and the developer carrier as shown in Table 17, Example L-
Evaluation was performed in the same manner as 1. The results are shown in Table 22. The conductive fine powder on the surface of the toner particles was liable to be lost, so that the chargeability of the image bearing member was greatly reduced, and fog and image stain were also noticeable.

[0576]

[Table 16]

[0577]

[Table 17]

[0578]

[Table 18]

[0579]

[Table 19]

[0580]

[Table 20]

[0581]

[Table 21]

[0582]

[Table 22]

[0583]

As described above, according to the present invention,
It is possible to achieve a development / cleaning image forming method which is excellent in recoverability of transfer residual toner particles. A developer was obtained that enabled the cleaning image forming method.

Further, in the image forming apparatus of the contact charging system, the transfer system and the toner recycling process, the inhibition of latent image formation is suppressed, and the recoverability of the transfer residual toner particles is excellent,
A development / cleaning image forming apparatus in which pattern ghost is sufficiently suppressed has become possible.

Further, the developer capable of controlling the supply of the conductive fine powder to the contact charging member, overcoming the charge inhibition due to the adhesion and mixing of the transfer residual toner particles, and making the image carrier satisfactorily charged. was gotten. Furthermore, it was possible to obtain a process cartridge which exhibits good developing / cleaning properties, can significantly reduce the amount of waste toner, and is advantageous in terms of cost reduction and downsizing.

Further, a simple member can be used as the contact charging member, and ozone-free direct injection charging can be stably maintained at a low applied voltage for a long period of time regardless of contamination of transfer charging toner particles on the contact charging member. In addition, the image carrier can be provided with a uniform charging property. Therefore, it is possible to obtain a process cartridge having a simple structure and low cost, which does not have a trouble due to ozone products and a trouble due to poor charging.

Further, by interposing the conductive fine powder in the contact portion between the charging member and the image carrier, the scratches on the image carrier can be greatly reduced when it is repeatedly used for a long time. The above image defect can be suppressed.

According to the present invention, the charge imparting ability to the toner is improved more uniformly and rapidly than the conventionally used developer carrying member, and the durability is further improved, so that a good image can be provided for a long time. It becomes possible to maintain a state in which it can be done.

Therefore, according to the present invention, by the developer carrier having high durability and good charge imparting ability, which is free from deterioration such as abrasion and toner contamination of the coating layer on the surface of the developer carrier due to repeated copying or durability, It is possible to provide a high-quality image with high image density and high image density for a long period of time without deterioration of image density, deterioration of sleeve ghost, and fog under different environments.

Further, according to the present invention, the negative charge imparting property to the toner is stabilized for a long period of time even under different environmental conditions, the toner coat is made uniform, and the surface of the developer carrying member by repeated copying or durability is improved. A highly durable developer carrier that does not cause abrasion of the conductive coating layer, sleeve contamination by toner, sleeve fusion, etc. provides high-quality images for a long period of time without image density reduction, ghosting, or fog deterioration. can do.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating an outline of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a graph showing charging characteristics of each charging member.

FIG. 3 is a graph showing human visual characteristics according to spatial frequencies.

FIG. 4 is a schematic view showing an outline of a developer charge amount measuring device used in the present invention.

FIG. 5 is a schematic diagram showing a layer structure of a photoconductor as an image bearing member of the present invention.

FIG. 6 is a configuration diagram showing an outline of a toner particle spheronizing device used in an example of the present invention.

FIG. 7 is a schematic diagram of a processing unit of a toner particle spheronizing device used in an example of the present invention.

FIG. 8 is an explanatory diagram of a surface charge amount measuring device for measuring the charge polarity of the resin coating layer.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 5/147 503 G03G 5/147 504 3J103 504 9/08 9/08 15/02 101 15/02 101 21 / 00 312 21/10 15/08 507B (72) Inventor Kenji Fujishima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Kyosho Akashi 3-30 Shimomaruko, Ota-ku, Tokyo No. 2 Canon Inc. (72) Inventor Satoshi Otake 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Masayoshi Shimamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Naoki Okamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2H005 AA15 EA05 EA10 2H068 AA03 AA04 AA05 BA16 BB02 BB20 BB28 BB35 BB52 CA22 CA29 CA37 FA27 2H077 AA12 AA37 AC11 AC16 AD02 AD06 AD13 AD17 AD35 FA13 FA25 GA03 2H134 GA01 GB02 HF13 JA05 JA11 JA14 KA20 KB11 KB21 GA21 GA21 GA21 GA21 GA21 GA21 GAH44 GA23 FA21 GA21 GA21 GA21 GA21 GA21 GAHGA HA28 HB12 HB17 HB22 HB48 JA01 JA28 LA01 LA12 LA38 NA01 3J103 AA02 AA15 AA24 AA32 AA41 AA51 EA05 FA05 FA12 FA14 FA18 GA02 GA52 GA57 GA58 GA60 HA03 HA04 HA05 HA11 HA15 HA16 HA20 HA37 HA41 HA46 HA48 HA54

Claims (35)

[Claims] 1. A developer container for containing a developer, a developer carrier for carrying the developer housed in the developer container and transporting the developer to a developing region, and a developer carrier on the developer carrier. A developing device having at least a developer layer thickness regulating member for regulating the layer thickness of a carried developer, wherein the developer comprises toner particles containing at least a binder resin and a colorant, and conductive fine particles. The toner particles have a circularity a calculated by the following formula of 0.9.
The developer carrier has at least a base and a resin coating layer formed on the base, and the resin coating layer includes at least a binder resin for the coating layer and a positively chargeable substance. And a developing device characterized by containing. [Equation 1] (In the formula, L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the projected image of the particle.) 2. The developing device according to claim 1, wherein the resin coating layer contains a conductive substance. 3. The developing device according to claim 1, wherein the resin coating layer contains a lubricating substance. 4. The developing device according to claim 1, wherein the resin coating layer contains a conductive substance and a lubricating substance. 5. The developing device according to claim 1, wherein the positively chargeable substance is a nitrogen-containing heterocyclic compound. 6. The developing device according to claim 5, wherein the nitrogen-containing heterocyclic compound is an imidazole compound. 7. The developing device according to claim 6, wherein the imidazole compound is a compound represented by the following formula (1) or (2). [Chemical 1] [In the formula, R ₁ and R ₂ represent a hydrogen atom or a substituent selected from the group consisting of an alkyl group, an aralkyl group and an aryl group, and R ₁ and R ₂ may be the same or different. Well, R ₃ and R ₄ represent a linear alkyl group having 3 to 30 carbon atoms, and R ₃ and R ₄ may be the same or different. ] [Chemical 2] [In the formula, R ₅ and R ₆ represent a hydrogen atom or a substituent selected from the group consisting of an alkyl group, an aralkyl group and an aryl group, and R ₅ and R ₆ may be the same, and R ₇ Represents a linear alkyl group having 3 to 30 carbon atoms. ] 8. The developing device according to claim 1, wherein the positively chargeable substance is a copolymer containing at least a unit derived from a nitrogen-containing vinyl monomer. 9. The weight average molecular weight (M
9. The developing device according to claim 8, wherein w) is 3,000 to 50,000. 10. The weight average molecular weight (M
The developing device according to claim 8 or 9, wherein the ratio (Mw / Mn) of w) to the number average molecular weight (Mn) is 3.5 or less. 11. The nitrogen-containing vinyl monomer has at least one monomer selected from the group consisting of a (meth) acrylic acid derivative having a nitrogen-containing group and a nitrogen-containing heterocyclic N-vinyl compound. Claim 8
11. The developing device according to any one of 1 to 10. 12. The nitrogen-containing vinyl monomer has the following general formula (3): [In the formula, R ₇ , R ₈ , R ₉ and R ₁₀ represent a hydrogen atom or a saturated hydrocarbon group having 1 to 4 carbon atoms, and n is 1 to 4
Indicates an integer. ] It is shown by these, The Claim 8 characterized by the above-mentioned.
11. The developing device according to any one of 1 to 10. 13. The positively chargeable substance is a copolymer of a vinyl polymerizable monomer and a sulfonic acid group-containing acrylamide monomer, and the binder resin for the coating layer has at least —NH _{2 in} its molecular structure. The developing device according to claim 1, wherein the developing device has one of a group, a = NH group, and a -NH- bond. 14. The copolymer has a copolymerization ratio (mass%) of a vinyl polymerizable monomer and a sulfonic acid group-containing acrylamide monomer of 98: 2 to 80:20 and a weight average molecular weight (Mw) of 2. 14. The developing device according to claim 13, wherein the developing device has a density of 1,000 to 50,000. 15. The developing device according to claim 13, wherein the copolymer is a copolymer of a vinyl polymerizable monomer and 2-acrylamido-2-methylpropanesulfonic acid. 16. The developing device according to claim 13, wherein the binder resin for the coating layer contains at least a phenol resin. 17. The phenolic resin is a phenolic resin produced by using a nitrogen-containing compound as a catalyst,
-NH ₂ group in its structure, = NH group or -NH-
A phenolic resin having any of the bonds.
6. The developing device according to item 6. 18. The developing device according to claim 13, wherein the binder resin for the coating layer contains at least a polyamide resin. 19. The developing device according to claim 13, wherein the binder resin for the coating layer contains at least a polyurethane resin. 20. The developing device according to claim 1, wherein the coating resin layer contains particles having a number average particle diameter of 0.3 to 30 μm. 21. The developing device according to claim 20, wherein the particles are spherical and have a true density of 3 g / cm ³ or less. 22. The developing device according to claim 20, wherein the particles are conductive spherical particles. 23. The developer has a particle size of 0.60 μm to 1
In the number-based particle size distribution of particles having a particle size of 59.21 μm, 15 to 60% by number of particles having a particle size range of 1.00 μm or more and less than 2.00 μm are contained, and a particle size range of 3.00 μm or more and less than 8.96 μm is used. 15-70% by number of particles
The developing device according to any one of claims 1 to 22, wherein the developing device comprises: 24. The developing device according to claim 1, wherein the conductive fine particles have a volume average particle diameter of 0.1 to 10 μm. 25. The conductive fine particles have a volume resistance value of 1
It is 0 ^{0-10 9} Ω · cm, The claim 1 characterized by the above-mentioned.
25. The developing device according to any one of 24 to 24. 26. The developing device according to claim 1, wherein the conductive fine particles are non-magnetic. 27. The developing device according to claim 1, wherein the conductive fine particles contain at least one oxide selected from zinc oxide, tin oxide, and titanium oxide. 28. A latent image carrier for carrying an electrostatic latent image; charging means for charging the latent image carrier; an electrostatic latent image formed on the latent image carrier, a developer; A developing device for forming a developer image by developing using the developing device and the latent image carrier are integrated, and are detachably attached to the image forming apparatus main body. The developer has toner particles containing at least a binder resin and a colorant and conductive fine particles, and the toner particles have a circularity a calculated by the following formula of 0.9.
The developing device is less than 70, and the developing device includes a developing container for containing a developer, a developer carrying body for carrying the developer contained in the developing container and transporting the developer to a developing area, and the developing device. The developer carrier has at least a developer layer thickness regulating member for regulating the layer thickness of the developer carried on the developer carrier, and the developer carrier has at least a substrate and a resin coating formed on the substrate. And a layer, the resin coating layer containing at least a binder resin for the coating layer and a positively chargeable substance. [Equation 2] (In the formula, L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the projected image of the particle.) 29. The developing device visualizes the electrostatic latent image formed on the latent image carrier as a developer image by developing with a developer, and the developer image is recorded on the recording medium. 29. The process cartridge according to claim 28, wherein the developer remaining on the latent image carrier is recovered after being transferred onto the barrel transfer material. 30. The latent image bearing member is in contact with the latent image carrier, and a voltage is applied to the latent image bearing member in a state where the conductive fine particles of the developer intervene, whereby the latent image is carried out. 30. The process cartridge according to claim 28, wherein the carrier is charged. 31. The process cartridge according to claim 28, wherein the developing device is the developing device according to any one of claims 2 to 27. 32. A charging step of charging a latent image carrier, a latent image forming step of writing image information as an electrostatic latent image on a charging surface of the latent image carrier charged in the charging step, and the electrostatic step. A developing step of developing a latent image by using a developing device equipped with a developer carrying member that carries the developer to a developing area facing the latent image carrying member while carrying the developer, and visualizing the latent image as a developer image; A transfer step of transferring the developer image onto a transfer material, and a fixing step of fixing the developer image transferred onto the transfer material by a fixing means, and these steps are repeated to form an image. In the image forming method, the developer has toner particles containing at least a binder resin and a colorant and conductive fine particles, and the toner particles have a circularity a of 0.9 calculated by the following formula.
The developing device is less than 70, and the developing device includes a developing container for containing a developer, a developer carrying body for carrying the developer contained in the developing container and transporting the developer to a developing area, and the developing device. The developer carrier has at least a developer layer thickness regulating member for regulating the layer thickness of the developer carried on the developer carrier, and the developer carrier has at least a substrate and a resin coating formed on the substrate. An image forming method, wherein the resin coating layer contains at least a binder resin for the coating layer and a positively chargeable substance. [Equation 3] (In the formula, L ₀ represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the projected image of the particle.) 33. The developing step is a step of visualizing the electrostatic latent image and collecting the developer remaining on the latent image carrier after the developer image is transferred to the transfer material. 33. The image forming method according to claim 32, wherein: 34. The charging step is a step of charging the latent image carrier by bringing a charging unit into contact with the latent image carrier, and the conductive portion of the developer is provided at a contact portion between the charging unit and the latent image carrier. 34. The image forming method according to claim 32 or 33, wherein the latent image carrier is charged by applying a voltage in a state in which the conductive fine particles are interposed. 35. The image forming method according to claim 32, wherein the developing device is the developing device according to any one of claims 2 to 27.