JP2003057951A - Image forming method, image forming device, process cartridge and developing device used in image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming method realizing control to attain suitable triboelectrification by stably appropriately electrifying developer without excessively electrifying it, and an image forming device, a process cartridge, and a developing device used in the image forming device. SOLUTION: In this image forming method, a developing stage serves also as a cleaning stage for recovering the developer remaining on an image carrier after transferring a toner image to transfer material. The developer has toner particles incorporating at least a binding resin component and magnetic powder. The surface of the toner particles is coated with inorganic impalpable powder and conductive impalpable powder whose average particle size is larger than that of the inorganic impalpable powder and smaller than that of the developer. The developer is magnetic developer whose average circularity is >=0.970 and where the magnetic powder is not exposed to the surface substantially. The developer carrier is constituted of base substance and a resin coating layer formed on the base substance, and the resin coating layer incorporates at least substance having negative electrifying properties. The image forming device, the process cartridge, and the developing device used in the image forming device are also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and an image forming apparatus for developing and visualizing a latent image formed on an image bearing member such as an electrophotographic photosensitive member or an electrostatic recording dielectric member. , A process cartridge, and a developing device used in the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, a number of methods are known as electrophotographic methods, but generally, a charging step of charging an image carrier using a photoconductive substance and a method of statically charging the charged image carrier are carried out. A step of forming an electric latent image, a developing step of developing the electrostatic latent image formed on the image carrier, a transfer step of transferring the developed image to a transfer material by a transfer means, and a transfer step. A desired copy is obtained through a fixing step of heating and fixing the transferred image transferred on the material.

The developing method in electrophotography is mainly divided into a one-component developing method and a two-component developing method. In recent years, since it is necessary to reduce the size of the copying apparatus for the purpose of reducing the weight and size of the electrophotographic apparatus, a developing apparatus using a one-component developer is often used. For example, as a developing method using a one-component developer, a jumping developing method is proposed in JP-A-55-18656.

However, the above-mentioned developing method has an unstable factor relating to the magnetic developer used. The magnetic developer contains a considerable amount of finely divided magnetic powder mixed and dispersed, and a part of the magnetic powder is exposed on the surface of the toner particles. Affects the charging property,
As a result, various characteristics required for the developer such as the developing characteristics and durability of the magnetic developer are changed or deteriorated.

When the conventional magnetic developer containing the magnetic powder is used, it is considered that the above-mentioned problems are caused largely by the fact that the magnetic powder is exposed on the surface of the toner particles. To be That is, the magnetic powder fine particles having a relatively low resistance as compared with the resin constituting the toner particles are exposed on the surface of the toner particles, which lowers the developer charging performance and the developer fluidity, and During long-term use, the image density is deteriorated due to the peeling of the magnetic powder due to the friction between the developers or the developer layer thickness regulating member, and the deterioration of the image such as uneven density is caused.

Conventionally, toner particles are produced by mixing a binder resin, a colorant, etc., melted and uniformly dispersed, pulverized by a fine pulverizer and classified by a classifier to obtain toner particles having a desired particle size. However, the selection range of the material is limited in order to make the toner particles into a fine particle diameter. For example,
The resin colorant dispersion must be sufficiently brittle to be finely pulverized in an economically available manufacturing apparatus. From this requirement, in order to make the resin colorant dispersion brittle, when the resin colorant dispersion is actually pulverized at a high speed, particles in a wide particle size range are easily formed, and particularly a relatively large proportion of fine particles ( The problem arises that it contains particles that are too crushed. Further, such a brittle material is often used when used as a developer in a printer or the like.
Further, it is easily subjected to fine pulverization or pulverization, and the generation of such fine particles easily causes toner adhesion to the photoconductor and the developer carrying member, which causes defective images.

In the pulverization method, it is difficult to completely and uniformly disperse solid fine particles such as a magnetic substance or a coloring agent in a resin. Depending on the degree of dispersion, fog may increase and image density may decrease. Cause. Furthermore, the crushing method is
In essence, the magnetic fine particles are exposed on the surface of the toner particles, which is likely to be disadvantageous in terms of increased fog, fluidity of the developer, and charging stability in a harsh environment.

In order to overcome the above problems of toner particles produced by a pulverization method, a method of producing toner particles by a suspension polymerization method has been proposed. This manufacturing method does not need to impart brittleness to the developer because it does not go through the crushing step, and can also use a large amount of a low softening point substance that could not be used in the conventional crushing method. The selection range of is expanded. The toner particles by suspension polymerization (hereinafter, polymerized toner) can be easily made into fine particles, and further, since the shape of the obtained toner particles is spherical, the flowability is excellent,
It is advantageous for high image quality.

On the other hand, as an image forming method, an electrostatic recording method,
Many methods such as a magnetic recording method and a toner jet method are known. Generally, after the transfer, the developer remaining on the image carrier without being transferred to the transfer material is cleaned by various methods and stored in the waste developer container as waste developer, and the above steps are repeated. The image forming method is used.

In this cleaning step, a method is used in which the developer remaining on the transfer is mechanically scraped off or dammed to be collected in a waste developer container. However, the image forming apparatus inevitably becomes large in size because it is equipped with an apparatus for performing such a cleaning process, which becomes a bottleneck when aiming at downsizing of the apparatus. Furthermore,
From the viewpoint of resource saving, waste reduction, and effective use of toner, a system without waste developer, a system excellent in fixing property and offset resistance has been desired.

On the other hand, as a system without waste developer, a technique called simultaneous cleaning with development or cleanerless has been proposed. However, as for the disclosure of the conventional technique related to simultaneous development cleaning or cleanerless, as disclosed in Japanese Patent Laid-Open No. 5-2287, the focus is on the positive memory, the negative memory, etc. due to the influence of the residual developer on the image. Is. However, as the use of electrophotography has advanced in recent years, it is necessary to transfer a toner image to various transfer materials, and in this sense, it is not satisfactory for various transfer materials.

Further, as a developing method preferably applied to simultaneous developing cleaning or cleanerless, in the simultaneous developing simultaneous cleaning which does not essentially have a cleaning device in the past, a structure in which the surface of the image bearing member is rubbed with a developer and a developing sleeve is used. Since it has been indispensable, many contact development methods have been studied in which the toner or developer carrying member comes into contact with the image carrying member. This is because, in order to collect the transfer residual developer in the developing means, it is considered that the structure in which the toner or the developer carrying member contacts with the image carrying member and rubs is advantageous.
However, in the simultaneous development cleaning or cleanerless process to which the contact development method is applied, toner deterioration due to long-term use, development sleeve surface deterioration, photoreceptor surface deterioration or abrasion, etc. are caused, and a sufficient solution to durability characteristics has been made. Absent. Therefore, a simultaneous development cleaning method using a non-contact developing method is desired.

Various methods are known for forming a latent image on an image bearing member such as an electrophotographic photosensitive member or an electrostatic recording dielectric member. For example, in electrophotography, an electrostatic latent image is formed by exposing a photoconductor, which uses a photoconductive material as an image carrier, uniformly to a required polarity and potential and then performing image pattern exposure. The method is generally used.

Conventionally, a corona charger (corona discharger) has been often used as a charging device for uniformly charging (including static elimination) the image carrier to a required polarity and potential. In recent years, as a charging device for an object to be charged such as an image carrier, a contact charging device has been proposed and put into practical use because it has advantages such as low ozone and low power as compared with a corona charger.

Charging mechanism of contact charging (charging mechanism,
In the charging principle), two types of charging mechanisms, a discharge charging mechanism and a direct injection charging mechanism, coexist, and each characteristic appears depending on which one is dominant.

In the contact charging device, a roller charging method using a charging roller as a contact charging member is preferable from the viewpoint of stability of charging and is widely used. The discharge charging mechanism is dominant in the charging mechanism in the conventional roller charging method.

The charging roller has elasticity in order to obtain a constant contact state with the member to be charged. Therefore, the charging roller has a large frictional resistance, and in many cases, 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 capability 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 inevitable.

In the method of charging by applying only DC voltage to the contact charging member (DC charging method), in order to obtain the photoreceptor surface potential Vd required for electrophotography, Vd is added to the charging roller. A DC voltage higher than the charging start voltage is required. However, in DC charging, the resistance value of the contact charging member fluctuates due to environmental changes and the charging start voltage fluctuates when the film thickness changes due to abrasion of the photoconductor, so the potential of the photoconductor is set to a desired value. Difficult to do. Therefore, as disclosed in Japanese Patent Laid-Open No. 63-149669, a voltage obtained by superimposing an AC component on a DC voltage corresponding to a desired Vd is applied to the contact charging member in order to further uniformize the charging. The "AC charging method" is used.
This is for the purpose of leveling the potential by the AC, and the potential of the body to be charged converges on Vd which is the center of the peak of the AC voltage, and is not affected by disturbance such as the environment. However, even in such a contact charging device, since the essential charging mechanism uses the discharge phenomenon from the contact charging member to the photosensitive member, as described above, the voltage applied to the contact charging member is a photosensitive member. A value higher than the body surface potential is required, and a small amount of ozone is generated.

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 are generated. Deterioration of the surface of the photoconductor becomes remarkable, which is a new problem.

Of the contact charging methods, in the fur brush charging, the discharge charging mechanism is dominant in the charging mechanism, and a high charging bias is applied and charging is performed using the discharge phenomenon.

On the other hand, in the magnetic brush charging, the direct injection charging mechanism is dominant as the charging mechanism. The particle diameter of the conductive magnetic particles forming the magnetic brush portion is 5 to 5
By using a film having a thickness of 50 μm and providing a sufficient speed difference from the photoconductor, uniform direct injection charging is possible. Magnetic brush charging makes it possible to obtain a charging potential almost proportional to the applied bias. However, there are problems that the device configuration is complicated, and that the conductive magnetic particles that form the magnetic brush portion fall off and adhere to the photoconductor.

Now, consider the case where these contact charging methods are applied to the simultaneous development cleaning method and the cleanerless image forming method. In the simultaneous development cleaning method and the cleanerless image forming method, the transfer residual developer remaining on the photoconductor because it does not have a cleaning member directly contacts the contact charging member and is attached or mixed. Further, in the case of the charging method in which the discharge charging mechanism is dominant, the deterioration of the developer due to the discharge energy causes deterioration of the adhesion to the charging member. When the commonly used insulating toner adheres to or mixes with the contact charging member, the charging property is deteriorated.

In the case of the charging method in which the discharge charging mechanism is predominant, the decrease in the chargeability of the member to be charged rapidly occurs when the toner layer adhered to the surface of the contact charging member becomes a resistance that inhibits the discharge voltage. Occur. On the other hand, in the case of the charging method in which the direct injection charging mechanism is dominant, the transfer residual developer adhered or mixed in reduces the contact probability between the surface of the contact charging member and the member to be charged and The chargeability decreases.

This decrease in the uniform charging property of the member to be charged results in a decrease in the contrast and uniformity of the electrostatic latent image after image exposure, which lowers the image density or increases the fog.

Further, in the simultaneous development cleaning method and the cleanerless image forming method, the charge polarity and charge amount of the transfer residual developer on the photoconductor are controlled, and the transfer residual developer is stably recovered in the developing step and recovered. The point is to prevent the developer from deteriorating the developing characteristics, and the charging member controls the charge polarity and charge amount of the transfer residual developer.

This will be specifically described by taking a general laser printer as an example. In the case of reversal development using a charging member that applies a negative polarity voltage, a negatively charging photoreceptor and a negatively charging developer, in the transfer process, the toner image visualized by the positive polarity transfer member is transferred to the transfer material. However, due to the relationship between the type of transfer material (difference in thickness, resistance, dielectric constant, etc.) and the image area, the charging polarity of the transfer residual developer changes from plus to minus. However, due to the negative polarity charging member when charging the negatively chargeable photoconductor, even the transfer residual developer as well as the surface of the photoconductor is uniformly swung to the positive polarity in the transfer process, The charging polarity can be made uniform. Therefore, when reversal development is used as the developing method, negatively charged transfer residual developer remains in the bright portion potential portion of the developer to be developed, and dark portion potential of the developer that should not be developed. In view of the development electric field, the transfer residual developer is attracted toward the developer carrying member and is collected without remaining on the photoconductor having the dark portion potential. That is, the charging member controls the charging polarity of the transfer residual developer at the same time as the charging of the photosensitive member, whereby the simultaneous development cleaning and cleanerless image forming method is established.

However, if the transfer residual developer adheres to or mixes with the contact charging member beyond the capability of controlling the developer charging polarity of the contact charging member, the transfer residual developer cannot be evenly charged. The developer carrier makes it difficult to collect the developer. Further, even if the developer-carrying member is recovered by a mechanical force such as rubbing, the charge on the developer on the developer-carrying member is adversely affected if the transfer residual developer is not uniformly charged. Affect the developing characteristics.

That is, in the simultaneous development cleaning and cleanerless image forming method, the charge control characteristics of the transfer residual developer when passing through the charging member and the adhesion / mixing characteristics to the charging member are the durability characteristics and the image quality characteristics. It is closely connected.

In Japanese Patent Application Laid-Open No. 5-150539, in an image forming method using a contact charging method, toner particles and silica fine particles which cannot be cleaned by a blade during repeated image formation for a long time adhere to the surface of a charging means.・
In order to prevent charging inhibition due to accumulation, it is disclosed that the developer contains at least developer particles and conductive particles having an average particle size smaller than the developer particles. However, the contact charging or the proximity charging used here is based on the discharge charging mechanism and has the above-mentioned problems due to the discharge charging. Further, when applied to a cleaner-less image forming apparatus, the large amount of conductive fine particles and the residual transfer developer pass through the charging process, which affects the charging property, as compared with the case where a cleaning mechanism is provided. No consideration is given to the recoverability of the conductive fine particles and the transfer residual developer in the developing step, and the influence of the recovered conductive fine particles and the transfer residual developer on the developing characteristics of the developer. Furthermore,
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 developer.

In proximity charging, it is difficult to uniformly charge the photoconductor with a large amount of conductive fine particles and transfer residual developer, and the effect of leveling the pattern of the transfer residual developer cannot be obtained. A pattern ghost is generated to block the pattern image exposure of the agent. Further, when the power is interrupted or paper is jammed during image formation, the inside of the machine is significantly contaminated with toner.

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 the transfer residual developer recovery in the development or to control the simultaneous development. There is also a cleaning image forming apparatus. Such an image forming apparatus exhibits a good simultaneous cleaning property during development, and can significantly reduce the amount of waste developer.
The cost is high, and the advantage of simultaneous cleaning during development is lost in terms of size reduction.

In contrast to these, Japanese Patent Laid-Open No. 10-307456
Japanese Patent Application Laid-Open Publication No. 2003-242977, wherein a toner containing toner particles and electrically conductive charge-promoting particles having a particle diameter of ½ or less of the toner particle diameter is applied to a simultaneous development developing image forming method using a direct injection charging mechanism. A device is disclosed. According to this proposal, without generating discharge products,
An image forming apparatus for simultaneous cleaning with development, which can reduce the amount of waste toner to a large extent and is advantageous in cost reduction and downsizing, can be obtained, and a good image can be obtained without causing charging failure, light blocking of image exposure, or diffusion.

Further, in Japanese Unexamined Patent Publication No. 10-307421, a toner containing conductive particles having a particle diameter of 1/50 to 1/2 of the toner particle diameter is directly injected into a cleaning image using a direct injection charging mechanism. 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 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 the particle of the conductive fine powder is obtained in order to obtain better charging uniformity. It is described that the diameter is 10 nm to 50 μm.

In Japanese Laid-Open Patent Publication No. 10-307457, the conductive particles are set to about 5 μm in order to make it difficult to visually recognize the influence of the charging failure portion on the image in consideration of human visual characteristics.
It is described that the thickness is m or less, 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, or the developing bias is a conductive fine particle. The conductive fine powder is embedded in the image carrier by preventing leakage through the powder, eliminating image defects, and setting the particle size of the conductive fine powder to be larger than 0.1 μm. A simultaneous development image forming method using a direct injection charging mechanism that solves the problem of blocking exposure light and realizes excellent image recording is described.

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 is electrically conductive contained in the toner. Fine powder adheres to the image carrier during the development process, remains on the image carrier even after the transfer process, and is carried and intervened. An image forming apparatus capable of simultaneously developing and cleaning is disclosed.

However, these proposals also have room for further improvement to improve stable performance and resolution in repeated use over a long period of time.

Furthermore, it is difficult to adjust the charge of the polymerized toner, and although various measures have been taken to improve the charge characteristics by means of external additives, the uneven charge of the developer and the occurrence of fusion on the sleeve surface are caused. The problem with durability stability is
Not completely resolved.

Further, as copying is repeated, the developer is repeatedly rubbed against the developer carrier, and as a result, non-development substances such as additives for improving the fluidity of the developer are deposited on the developer carrier. Alternatively, since the low softening point substance in the developer forms a film on the sleeve, there is a problem that the surface state of the developer carrying member changes and the developability of the developer changes.

Furthermore, there is room for further improvement such as poor charging of the developer on the developer carrying member due to the influence of the collection of the charge promoting particles and the transfer residual developer upon repeated use over a long period of time.

It is desired to prevent these charging defects, improve the uniformity of charging, and suppress developer contamination and developer fusion.

[0043]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming method, an image forming apparatus, a process cartridge, and a developing device which solve the above problems. More specifically, an image forming method, an image forming apparatus, a process cartridge, which has a capability of imparting a rapid and uniform and stable charge to a developer, which prevents charging failure when toner particles obtained by a polymerization method having a substantially spherical shape are used, To provide a developing device used in this image forming apparatus.

Another object of the present invention is that it is possible to greatly reduce the amount of waste developer without producing discharge products, enable low-cost simultaneous development cleaning image formation advantageous for downsizing, and An object of the present invention is to provide an image forming method for simultaneous cleaning with development, an image forming apparatus, a process cartridge, and a developing apparatus used in this image forming apparatus, which can obtain a good image even if it is repeatedly used over a long period of time.

Further, an object of the present invention is to provide an image forming method, an image forming apparatus, a process cartridge, and an image forming apparatus capable of forming a cleaning image simultaneously with development, which is excellent in transferability and recovery of a transfer residual developer. It is to provide a developing device used for.

[0046]

The present invention is as follows. (1) A charging step of applying a voltage to a charging member to charge an image bearing member, an electrostatic latent image forming step of forming an electrostatic latent image on the charged image bearing member, and the following (a) to ( a developing step including d); (a) a step of supporting a developer contained in a developing container on a developer carrier; (b) a layer thickness of the developer on the developer carrier. Process of controlling by layer thickness control member;
(C) A step of carrying and carrying the developer whose layer thickness is regulated to a developing area where the developer carrying member and the image carrying member face each other;
(D) A step of transferring the developer on the developer carrier to an electrostatic latent image on the image carrier to form a toner image; the toner image formed on the surface of the image carrier is electrostatically transferred onto a transfer material. And a fixing step of heating and fixing the toner image transferred onto the transfer material, the developing step comprises the step of transferring the toner image onto the transfer material and then onto the image carrier. The developer also serves as a cleaning step for collecting the remaining developer, and the developer is composed of toner particles containing at least a binder resin component and magnetic powder, inorganic fine powder on the surface of the toner particles, and inorganic fine powder. Is larger than the developer and has an average particle size smaller than that of the developer, and the average circularity determined by the following formula (1) is 0.970 or more, and the magnetic powder is substantially exposed on the surface. Not a magnetic developer, carrying the developer , The substrate and the base of a resin coating layer formed on the support, wherein the resin coating layer, an image forming method characterized in that it contains at least negatively charged substances.

[0047]

Equation 4] circularity _{a = L 0 / L (1} ) ( wherein, L ₀ represents the circumferential length of a circle having the same projected area as a particle image, L is showing the circumferential length of a projected image of a particle. (2) Part or all of the binder resin for the coating layer of the resin coating layer has at least one of —NH ₂ group, ═NH group, and —NH— bond in its molecular structure ( 1)
Image forming method. (3) The image forming method according to (1) or (2), wherein the binder resin for the coating layer of the resin coating layer contains at least a phenol resin. (4) The phenolic resin is a phenolic resin produced by adding and condensing phenols and aldehydes using a nitrogen-containing compound as a catalyst.
The image forming method according to (3), which is a phenol resin having any one of an NH ₂ group, an = NH group, and a -NH- bond. (5) The image forming method according to any one of (1) to (4), wherein the resin coating layer contains at least a quaternary ammonium salt compound that is positively charged with iron powder. (6) The image forming method according to any one of (1) to (4), wherein the resin coating layer contains a benzylic acid compound. (7) The image forming method according to any one of (1) to (6), wherein the resin coating layer is a conductive resin coating layer in which conductive fine powder is further dispersed and contained in a binder resin for coating layer. (8) The magnetic powder is mainly composed of magnetite, and the ratio of the iron element content (B) to the carbon element content (A) present on the toner particle surface (A) measured by X-ray photoelectron spectroscopy ( B / A) is less than 0.001 (1)
To (7) the image forming method. (9) Let C be the volume average particle diameter of the magnetic developer, and let D be the minimum value of the distance between the magnetic powder and the toner particle surface in the tomographic plane observation of the magnetic developer using a transmission electron microscope (TEM). When done, D / C ≦ 0.02 (1) to (8)
The image forming method of any one of. (10) The toner particles are toner particles obtained by suspension polymerization of a polymerizable monomer system containing at least a polymerizable monomer serving as a binder resin component and a magnetic powder in an aqueous medium ( The image forming method according to any one of 1) to (9). (11) The image forming method according to any one of (1) to (10), wherein the conductive fine powder of the magnetic developer has a volume resistance of 10 ⁹ Ωcm or less. (12) The image forming method according to any one of (1) to (10), wherein the conductive fine powder of the magnetic developer has a volume resistance of 10 ⁶ Ωcm or less. (13) The image forming method according to any one of (1) to (12), wherein the conductive fine powder of the magnetic developer is non-magnetic. (14) The image forming method according to any one of (1) to (13), wherein the developer has toner particles and conductive fine powder having a volume average particle diameter of 0.1 μm to 0.5 μm. . (15) The charging step is a step of charging the image carrier by applying a voltage to a charging member that forms an abutting portion with the image carrier with the conductive fine powder interposed therebetween and is in contact therewith (1 ) To (14), the image forming method. (16) In the charging step, the conductive fine powder contained in the magnetic developer adheres to the image carrier in the developing step,
The image forming method according to (15), which remains on the image bearing member even after the transfer step, and is carried and interposed at least in the contact portion and / or the vicinity of the charging member and the image bearing member. (17) The image forming method according to any one of (1) to (16), wherein the conductive fine powder is fine particles containing at least one oxide selected from zinc oxide, tin oxide, and titanium oxide. (18) A process cartridge for visualizing an electrostatic latent image formed on an image bearing member as a toner image with a developer and transferring the visualized developer image to a transfer material to form an image. The process cartridge includes an image bearing member for carrying an electrostatic latent image, a charging unit for charging the image bearing member, an electrostatic latent image formed on the image bearing member, and a developer. And a developing means for collecting the developer remaining on the image carrier after the toner image is visualized as a toner image by transferring the toner image onto the transfer material. The developing device and the latent image carrier are integrated and are detachably attached to the image forming apparatus main body.
The developer is toner particles containing at least a binder resin component and magnetic powder, inorganic fine powder on the surface of the toner particles, and conductive fine powder having an average particle size larger than the inorganic fine powder and smaller than the developer. A magnetic developer having a body, an average circularity determined by the above formula (1) of 0.970 or more, and the magnetic powder is not substantially exposed on the surface. A developer container for containing the developer, a developer carrier for carrying the magnetic developer housed in the developer container and transporting the magnetic developer to the developing area, and a developer carried on the developer carrier. Having at least a developer layer thickness regulating member for regulating the layer thickness of, the developer carrying member comprises a substrate and a resin coating layer formed on the substrate, the resin coating layer, Characterized by containing at least a negatively chargeable substance Process cartridge to be. (19) To store a charging unit that applies a voltage to the charging member to charge the image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the charged image carrier, and a developer Of the developing container, a developer carrying member for carrying the developer contained in the developing container and transporting the developer to the developing area, and a layer thickness of the developer carried on the developer carrying member. Developing means having at least a developer layer thickness regulating member, transfer means for electrostatically transferring the toner image formed on the surface of the image carrier to a transfer material, and heating and fixing the toner image transferred on the transfer material. In the image forming apparatus, the developing means visualizes the electrostatic latent image formed on the image bearing member as a toner image by developing the electrostatic latent image with the developer. After the image is transferred to the transfer material, The developer has means for collecting the developer remaining on the carrier, and the developer is a toner particle containing at least a binder resin component and a magnetic powder, an inorganic fine powder on the surface of the toner particle, and an inorganic fine powder. A conductive fine powder having an average particle size larger than the body and smaller than the developer, the average circularity determined by the above formula (1) is 0.970 or more, and the magnetic powder is substantially on the surface. It is a magnetic developer which is not exposed, and the developer carrier comprises a substrate and a resin coating layer formed on the substrate, and the resin coating layer contains at least a negatively chargeable substance. A characteristic image forming apparatus. (20) A developing device used in the image forming apparatus of the present invention.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the developing step also serves as a cleaning step for collecting the developer remaining on the image carrier after the toner image is transferred onto the transfer material.
Toner particles containing at least a binder resin component and magnetic powder, inorganic fine powder on the surface of the toner particles, and conductive fine powder having an average particle size larger than the inorganic fine powder and smaller than the developer. A magnetic developer having an average circularity of 0.970 or more determined by the following formula (1) and substantially no magnetic powder exposed on the surface, wherein the developer carrier is
A substrate and a resin coating layer formed on the substrate,
The resin coating layer contains at least a negatively chargeable substance.

[0049]

Equation 5] circularity _{a = L 0 / L (1} ) ( wherein, L ₀ represents the circumferential length of a circle having the same projected area as a particle image, L is showing the circumferential length of a projected image of a particle. ) As described above, in the image forming method of the simultaneous development cleaning method, the developing step of developing the electrostatic latent image also serves as the cleaning step of collecting the developer remaining on the image carrier after transferring the image to the transfer material. There has been a demand for a developer having characteristics of high transfer efficiency with less residual developer.

In general, the developer produced by the polymerization method has a small contact area between the toner particles and the photoconductor when compared with the developer produced by the conventional pulverization method by a jet mill, and the toner particles are exposed to light. Adhesion to the body is considered to be reduced, and the transferability is greatly improved, and the transfer efficiency is greatly improved, but on the other hand, coloring materials such as carbon and magnetic powders used in magnetic developers are used as toner particles. Since these additives are taken inside, they do not act as sites for leaking the charges generated on the surface of the toner particles, so that the developer is easily charged up. In the present invention, as a developer used in the image forming method of the simultaneous development developing method which also serves as a cleaning step of collecting the developer remaining on the image carrier after the toner image developed in the developing step is transferred to a transfer material, charging acceleration is performed. Although the one to which the conductive fine powder is added as the particles is used, the electric charge is hard to leak even when such a developer is used, and therefore uneven development and blotches, and the concentration due to the developer carrier adherence of the developer Decrease is likely to occur. Further, the charging failure of the developer on the developer carrying member is likely to occur due to the influence of the collection of the charge promoting particles and the transfer residual developer in the repeated use.

Although a method of adding various inorganic fine powders to the toner particles as an external additive has been proposed for the purpose of improving these charging characteristics and the like, a sufficient method has not been obtained yet. <1> Developer carrier according to the present invention As a result of repeated studies on the surface of the developer carrier that imparts triboelectric charges to the developer, a resin coating layer was formed on the substrate of the developer carrier, and its formation By containing at least the negatively chargeable substance in the resin coating layer, in the simultaneous developing cleaning system, the generation of the developer having an excessive charge with respect to the negatively chargeable developer produced by the polymerization method, It has been found that the strong adherence of the developer to the surface of the developer carrier can be effectively prevented and the triboelectric charge amount can be charged to a suitable level.

In the present invention, known resins can be used as the resin coating binder resin used in the resin coating layer.
For example, styrene resin, vinyl resin, polyether sulfone resin, polycarbonate resin, polyphenylene oxide resin, polyamide resin, fluororesin, fibrin resin, thermoplastic resin such as acrylic resin, epoxy resin, polyester resin, alkyd resin A thermosetting or photocurable resin such as phenol resin, melamine resin, polyurethane resin, urea resin, silicone resin or polyimide resin can be used. Among them, those having releasability such as silicone resin and fluorine resin, or polyether sulfone resin, polycarbonate resin, polyphenylene oxide resin, polyamide resin, phenol resin, polyester resin, polyurethane resin, styrene resin, acrylic resin Those having such excellent mechanical properties are more preferable.

Of these, a silicone resin and a fluororesin having a negative charging property are preferable, and they may be mixed with another binder resin for the purpose of increasing the mechanical strength. In addition, -N together with a quaternary ammonium salt having a positive charging property with respect to iron powder
It is preferable to use a binder resin having at least one structure of H ₂ group, ═NH group, or —NH— bond.

As the substance having a --NH ₂ group, R--N
Examples thereof include primary amines represented by H ₂ or polyamines having them, primary amides represented by RCO-NH ₂ or polyamides having them. = NH group is a secondary amine represented by R = NH or a polyamine having them, (RCO) ₂ = NH
The second amide represented by or a polyamide having them, and the like. Examples of the substance having a -NH- bond include -NHC in addition to the above-mentioned polyamine and polyamide.
Examples thereof include polyurethane having an OO-bond. As the binder resin for the covering layer, an industrially synthesized resin containing one or more of the above substances or as a copolymer is preferably used. Among them, from the viewpoint of versatility, a phenol resin, a polyamide resin, and a urethane resin produced by adding and condensing phenols and aldehydes using a nitrogen-containing compound as a catalyst can be preferably used.

Examples of the nitrogen-containing compound used as a catalyst in the production of the phenol resin include an acidic catalyst and a basic catalyst. Examples of the acidic catalyst include ammonium sulfate, ammonium phosphate, ammonium sulfamate, ammonium carbonate and acetic acid. Examples thereof include ammonium salts such as ammonium and ammonium maleate, or amine salts. As the basic catalyst, for example, ammonia,
Alternatively, 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-amylaniline, N-methylethanolamine, N-ethylethanolamine, diethanolamine,
Triethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine,
n-butyldiethanolamine, di-n-butylethanolamine, triisopropanolamine, ethylenediamine, amino compounds such as hexamethylenetetramine, pyridine, α-picoline, β-picoline, 2,4-lutidine, 2,
Pyridine such as 6-lutidine and its derivatives, quinoline compounds, imidazole, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-
Examples thereof include imidazole such as phenylimidazole, 2-phenyl-4-methylimidazole and 2-heptadecylimidazole and derivatives thereof.

It is also preferable to use a negatively chargeable substance added to these known binder resins. A conventionally known substance can be used as such a negatively chargeable substance. For example,
In addition to silica powder, fluororesin powder, and the like, there are organic metal complexes, chelate compounds, monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Further, there are aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

Among these, the following compounds are preferably used in order to charge the developer well. Aluminum compound of benzylic acid, boron compound, zinc compound,
There are chromium compounds and the like. Examples of the benzylic acid compound include an aluminum compound of benzylic acid having an unsubstituted group or a substituent represented by the following general formula (1).

[0058]

[Chemical 1] (In the formula, R5 and R6 may be the same or different and each is a linear or branched alkyl group, alkenyl group, alkoxyl group, halogen atom, nitro group, cyano group, amino group, carboxyl group and A substituent selected from the group consisting of hydroxyl groups is shown, and m and n are integers from 0 to 5.)

Among them, an aluminum compound of benzylic acid represented by the following general formula (2) is more preferable.

[0060]

[Chemical 2] (In the formula, R5 and R6 may be the same or different and each is a linear or branched alkyl group, alkenyl group, alkoxyl group, halogen atom, nitro group, cyano group, amino group, carboxyl group and And m and n each represents an integer of 0 to 5. Y represents a monovalent cation, hydrogen, lithium, sodium, potassium, ammonium or alkylammonium.)

It is also preferable to further contain acrylamide containing sulfonic acid. For example, 2-acrylamidopropanesulfonic acid, 2-acrylamido-n-butanesulfonic acid, 2-acrylamido-n-hexanesulfonic acid, 2-acrylamido-n-octanesulfonic acid, 21-acrylamido-n-dodecanesulfonic acid, 2
-Acrylamido-n-tetradecane sulfonic acid, 2-
Acrylamide-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
-Methacrylamide-n-decane sulfonic acid, 21-methacrylamido-n-tetradecane sulfonic acid and the like can be mentioned. Preferably 2-acrylamido-2-
Methyl propane sulfonic acid may be mentioned.

The amount of the negatively chargeable substance added to the resin coating layer is 1 to 1 with respect to 100 parts by mass of the binder resin for the resin coating layer.
It is preferably set to 00 parts by mass. If it is less than 1 part by mass, the charging stability is not improved by the addition, and if it exceeds 100 parts by mass, the existing amount in the binder resin for the resin coating layer becomes excessive and the binder resin for the original resin coating layer is added. The characteristics are likely to be impaired and the strength of the coating layer tends to be lowered.

As a more preferable means for containing the negatively chargeable substance in the resin coating layer in the present invention, prior to the present invention, there is a conventional method disclosed in JP-A-10-326040 and JP-A-11-052711. A quaternary ammonium salt compound known as a toner positive charge control agent, that is, a quaternary ammonium salt compound which is itself positively charged with iron powder, and a binder resin for a resin coating layer. In particular, a part or all of the binder resin for the resin coating layer has at least -NH ₂ group, = N in its molecular structure.
When the resin coating layer of the developer bearing member is formed using one having an H group or one having an —NH— bond, the quaternary ammonium salt compound is incorporated into the binder resin for the resin coating layer and is positively charged. It was found that the resin (resin coating layer) itself exhibits a strong negative chargeability to the conductive toner and a good charge imparting property, and by using this as a developer carrier in a developing device, a very good image can be obtained. We are proposing to obtain it.

The advantage of this method is that, for example, in comparison with the above-mentioned system in which silica, a fluororesin powder, and a negative charge control agent are added to the resin coating layer in order to impart a charge to the toner,
Since the quaternary ammonium salt compound can be dissolved in the solvent of the binder resin for the resin coating layer and made to exist uniformly in the resin, when the resin coating layer is formed, the negative chargeable material in which the entire resin layer is uniform In comparison with the silica-added system that is dispersed in a matrix, the entire developer carrier shows a uniform and good charge imparting property, and furthermore, since it is not a powder-added system, the mechanical strength is That is, the durability is good.

As a result of further investigations on these disclosed techniques, the present inventors have found that when a negatively chargeable developer is used, it has a spherical shape to a substantially spherical shape as used in the present invention. When using a developer in which magnetic powder is not exposed to the surface and tends to have an excessive electric charge, by adding a quaternary ammonium salt compound to the resin coating layer, the excessive electric charge of the developer can be reduced. It has been found that the generation is suppressed and suitable charging characteristics are obtained. That is, a quaternary ammonium salt compound known as a positive charge control agent for toner in the past, that is, a quaternary ammonium salt compound which is itself positively chargeable to iron powder is used, and an appropriate amount of addition is used. By setting the amount, as the binder resin for the resin coating layer, a part or the whole of the binder resin for the resin coating layer has —NH ₂ group, ═NH group, and —NH— bond in its molecular structure. By forming the resin coating layer of the developer carrying member by using one having any of the following, the generation of a developer having an excessive charge with respect to the magnetic developer of the present invention, and It has been found that the strong adherence of the developer can be effectively prevented and the triboelectric charge amount can be charged to a suitable level.

As a result of a study for improving the charging property of the toner of the present invention produced by a polymerization method having the advantage of high transfer efficiency, it was found that the resin coating layer of the developer carrying member has the above-mentioned constitution. , Stabilize the charge amount of the developer,
It is possible to prevent uneven development, blotches, fog, and image density reduction due to charge-up.

The quaternary ammonium salt compound preferably used in the present invention is one having a positive charging property with respect to iron powder. For example, the compound represented by the following general formula 3 may be mentioned.

[0068]

[Chemical 3]

(In the formula, R1, R2, R3 and R4 respectively represent an alkyl group which may have a substituent, an aryl group which may have a substituent and an aralkyl group, and R1 to 4 are They may be the same or different. X ⁻ represents an anion of an acid.) On the other hand, for example, as represented by the following formula 4, the iron powder itself has a negative charging property to iron powder. The quaternary fluorine ammonium salt compound was also examined, but it was found that the addition of the compound did not achieve the intended purpose of the present invention. That is, the compound represented by the following formula 4 has a fluorine resin atom having a strong electron-withdrawing property in its structure, and thus has a negative chargeability to the iron powder itself, but like the case of the present invention, Even if a resin coating layer is formed by using a resin composition in which the compound is dispersed in a binder resin for a resin coating layer, a quaternary ammonium salt compound which is itself positively charged with iron powder is obtained. The effect was not obtained as much as it was contained.

[0070]

[Chemical 4]

Specific examples of the quaternary ammonium salt compound which is preferably used in the present invention and which is itself positively charged with iron powder include those represented by the following general formulas 5 to 12. However, of course, the present invention is not limited to these.

[0072]

[Chemical 5]

[0073]

[Chemical 6]

[0074]

[Chemical 7]

[0075]

[Chemical 8]

[0076]

[Chemical 9]

[0077]

[Chemical 10]

[0078]

[Chemical 11]

[0079]

[Chemical 12]

Fourth used in the present invention as shown above
The addition amount of the primary ammonium salt compound is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the binder resin for the resin coating layer. If it is less than 1 part by mass, the charging stability is not improved by the addition, and if it exceeds 100 parts by mass, the amount present in the binder resin for the resin coating layer becomes excessive and the characteristics of the original resin are impaired. It is easy to cause deterioration.

The binder resin for the resin coating layer used for the resin coating layer of the developer carrying member used in the present invention is not particularly limited, but a part or all of the binder resin for the resin coating layer has a molecular structure. it is preferred to have at least -NH ₂ group, = NH group or the structure of any of -NH- bound to. By forming the resin coating layer using such a binder resin for the resin coating layer, the effect of the present invention is easily exhibited. In the present invention, when the resin coating layer of the developer carrying member having the above-mentioned structure is used, the definite reason why the charge imparting property of the resin coating layer itself is changed is not clear, but iron powder quaternary ammonium salt compound which is positively chargeable for and, -NH ₂ group, = NH group or -NH- bond with and has resin coating layer binder resin has at least one structure resin, By forming the coating layer, the quaternary ammonium salt is incorporated into the structure of the binder resin for resin coating layer. At that time, the original structure of the quaternary ammonium salt having a positive polarity is lost, and the binder resin for the resin coating layer incorporating these becomes uniform and has sufficient chargeability, which contributes to stabilization of charge. It is thought to be to do so.

In the developer carrier used in the present invention, in order to adjust the volume resistance of the resin coating layer, conductive fine powder may be dispersed and contained in the binder resin for the coating layer. As such a conductive fine powder, the number average particle diameter is preferably 20 μm or less, more preferably 10 μm or less. To avoid irregularities formed on the surface of the binder resin for the coating layer, the number average particle size is 1
It is more preferable to use conductive fine powder having a particle size of not more than μm.

The average particle size of the conductive fine powder in the present invention is measured in a measurement range of 0.04 to 2000 μm by attaching a liquid module to a LS-230 type laser diffraction type particle size distribution measuring device manufactured by Beckman Coulter. As a measuring method, a trace amount of a surfactant is added to 10 ml of pure water, 10 mg of a conductive fine powder sample is added thereto, and the mixture is dispersed for 10 minutes by an ultrasonic disperser (ultrasonic homogenizer), and then a measuring time of 90 The measurement is performed once per second.

The conductive fine powder used in the present invention includes carbon black such as furnace black, lamp black, thermal black, acetylene black and channel black; titanium oxide, tin oxide, zinc oxide,
Metal oxides such as molybdenum oxide, potassium titanate, antimony oxide and indium oxide; aluminum,
Metals such as copper, silver and nickel, graphite, metal fibers,
Examples include inorganic fillers such as carbon fibers.

The amount of the conductive fine powder added to the resin coating layer is 1 with respect to 100 parts by weight of the binder resin for the coating layer.
A range of not more than 00 parts by mass gives preferable results. A more preferable addition amount is 40 parts by mass. If the amount added exceeds 100 parts by mass, the coating strength tends to decrease, and the addition of a large amount of non-chargeable particles may cause the toner charge amount to decrease.

As the constitution of the resin coating layer of the developer carrying member used in the present invention, it is preferable to further disperse a lubricating substance in the resin coating layer because the effect of the present invention is further promoted. Examples of the lubricating substance include graphite,
Examples include molybdenum disulfide, boron nitride, mica, graphite fluoride, silver-niobium selenide, calcium chloride-graphite, talc, fatty acid metal salts such as zinc stearate, etc., and especially graphite does not impair the conductivity of the coating layer. Therefore, it is preferably used. It is preferable to use those lubricants having a number average particle diameter of preferably about 0.2 to 20 μm, more preferably 0.3 to 15 μm.

The average particle size of the lubricating substance in the present invention is
In the same manner as the particle size measurement of the conductive fine powder, a liquid module is attached to a LS-230 type laser diffraction particle size distribution analyzer manufactured by Beckman Coulter, Inc., and 0.04 to 2000 μm.
Measure in the measurement range of m. The addition amount of the above-mentioned lubricating substance is 10 to 1 with respect to 100 parts by mass of the binder resin for the coating layer.
A range of 20 parts by weight gives particularly favorable results. When the amount added exceeds 120 parts by mass, the strength of the coating layer tends to decrease, and addition of a large amount of non-electrostatic additive is
A decrease in the charge amount of the toner occurs. On the contrary, if the amount is less than 10 parts by mass, it is difficult to obtain the effect of preventing the toner from adhering to the developer carrying member.

In addition, the resin coating layer of the developer carrying member stabilizes the surface roughness by dispersing spherical particles in the resin coating layer in addition to the above-mentioned additive substance, thereby stabilizing the surface roughness of the developer carrying member. It is possible to optimize the developer coating amount. The spherical particles maintain a uniform surface roughness on the surface of the coating layer of the developer carrier, and at the same time, even if the surface of the coating layer is worn, the change in the surface roughness of the coating layer is small, and the developer is not contaminated or develops. This has the effect of making it difficult to cause agent fusion.

The spherical particles used in the present invention have a number average particle diameter of 0.3 to 30 μm, preferably 2 to 20 μm.
m. If the number average particle diameter of the spherical particles is less than 0.3 μm, the effect of imparting a uniform roughness to the surface and the effect of stabilizing the charging performance due to it are small, and rapid and uniform charging of the developer becomes insufficient. . In addition, the developer may become unstable, and the abrasion of the coating layer may further reduce the transportability, resulting in poor charging of the developer, contamination of the developer, and fusion of the developer. Is likely to occur, which is not preferable. When the number average particle diameter exceeds 30 μm, the roughness of the surface of the coating layer becomes too large, the amount of developer conveyed becomes large, and it becomes difficult to sufficiently regulate the developer by the developer regulating section. It becomes difficult to sufficiently charge the image, and the image quality is deteriorated. Furthermore, the mechanical strength of the coating layer is reduced and the durability of the film is reduced, which is not preferable.

The number average particle size of the spherical particles is LS, manufactured by Beckman Coulter, in the same manner as the particle size measurement of the conductive fine powder.
It is measured using a -230 type laser diffraction particle size distribution analyzer.

The spherical particles have a true density of 3 g / cm ³ or less,
It is preferably 2.7 g / cm ³ or less, more preferably 0.
It is preferably 9 to 2.3 g / cm ³ . That is, when the true density of the spherical particles exceeds ³ g / cm ³ , the dispersibility of the spherical particles in the coating layer becomes insufficient, and it becomes difficult to impart uniform roughness to the surface of the coating layer. In addition, since the storage stability of the paint is not good, it is difficult to obtain a triboelectrification imparting member surface having uniform surface irregularities. Even when the true density of the spherical particles is smaller than 0.9 g / cm ³ , the dispersibility and storage stability of the spherical particles in the coating layer tend to be insufficient. The true density of the spherical particles is Accubic 1
It measures using 330 (made by Shimadzu).

In the present invention, “spherical” in spherical particles
Means that the major axis / minor axis ratio of the particles is about 1.0 to 1.5, and particles having a major axis / minor axis ratio of 1.0 to 1.2 are preferably used in the present invention. Good to do. When the ratio of the major axis / minor axis of the spherical particles exceeds 1.5, the surface roughness of the coating layer becomes non-uniform, and the toner is rapidly and uniformly charged and the strength of the conductive coating layer is increased. Not preferable.

As the spherical particles used in the present invention, known spherical particles can be used. For example, there are spherical resin particles, spherical metal oxide particles, spherical carbonized particles, and the like.
The spherical resin particles are obtained, for example, by a suspension polymerization method, a dispersion polymerization method or the like, and a suitable surface roughness can be obtained with a smaller addition amount, and a more uniform surface shape can be easily obtained.
Examples of such spherical particles include acrylic resin particles such as polyacrylate and polymethacrylate, polyamide resin particles such as nylon, polyolefin resin particles such as polyethylene and polypropylene, silicone resin particles, phenol resin particles, polyurethane particles. Examples thereof include resin particles, styrene resin particles, benzoguanamine particles and the like.
The resin particles obtained by the pulverization method may be thermally or physically spheroidized before use.

The inorganic fine powder may be adhered or fixed to the surface of the spherical particles. Such inorganic fine powders include SiO ₂ , SrTiO ₃ , CeO ₂ and Cr.
O, Ai ₂ O ₃ , oxides such as ZnO and MgO, Si ₃ N ₄
Etc., nitrides such as SiC, carbides such as SiC, CaSO ₄ , BaS
Examples thereof include sulfates and carbonates such as O ₄ and CaCO ₃ .

The inorganic fine powder attached to the spherical particles may be treated with a coupling agent before use. In particular, it is preferable to use spherical particles to which inorganic fine powder treated with a coupling agent is attached for the purpose of improving the adhesiveness with the binder resin or imparting hydrophobicity to the particles. Examples of such coupling agents include silane coupling agents, titanium coupling agents, zircoaluminate coupling agents, and the like. More specifically, as the silane coupling agent, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyl. Dimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethyldichlorosilane Ethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldi Rokisan, 1,3-diphenyl tetramethyl disiloxane, and 1
Examples thereof include dimethylpolysiloxane having 2 to 12 siloxane units per molecule, each unit located at the terminal having a hydroxyl group bonded to a silicon atom directed to one unit.

By thus adhering the inorganic fine powder treated with the coupling agent onto the surface of the spherical particles, the dispersibility in the resin coating layer, the uniformity of the resin coating layer surface, and the resistance of the resin coating layer can be improved. It is possible to improve the stain resistance, the charge imparting property to the toner, the abrasion resistance of the resin coating layer, and the like.

The spherical particles used in the present invention are more preferably conductive. That is, by imparting conductivity to the spherical particles, it is difficult to accumulate charges on the surface of the particles due to the conductivity, and it is possible to reduce developer adhesion and improve chargeability to the developer. In the present invention, as the conductivity of the spherical particles, the volume resistance value is 10 ⁶ Ωcm or less, more preferably 10 ⁻³ to 10 ⁶ Ωc.
The conductive spherical particles of m are preferable.

In the present invention, the volume resistance of the spherical particles is 1
When it exceeds 0 ⁶ Ωcm, the developer tends to be contaminated or fused with the spherical particles exposed on the surface of the coating layer due to abrasion as nuclei, and rapid and uniform charging is difficult to perform, which is not preferable.

As a method for obtaining such conductive spherical particles, the following methods are preferable, but the methods are not necessarily limited to these methods.

A particularly preferable method for obtaining the conductive spherical particles used in the present invention is, for example, low density and good quality obtained by firing spherical resin particles or mesocarbon microbeads to carbonize and / or graphitize. A method of obtaining conductive spherical carbonized material particles can be mentioned. And, as the resin used for the spherical resin particles, for example, a phenol resin,
Examples thereof include 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 and quinoline.

A more preferable method for obtaining conductive spherical particles is to coat spherical resin particles such as phenol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer and polyacrylonitrile on the surface of spherical resin particles. , Bulk mesophase pitch is coated 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, and a conductive spherical carbonized product The method of obtaining a particle | grain is mentioned. The spherical carbonized material particles obtained by this method are more preferable because the conductivity of the spherical carbonized material particles obtained by graphitization is improved because the coated portion of the spherical carbonized material particles is crystallized.

The conductive spherical carbonized material particles obtained by the above-mentioned method can control the conductivity of the spherical carbonized particle obtained by changing the firing conditions by any method. It is preferably used in the invention. In some cases, the spherical carbon particles obtained by the above-mentioned method may be a conductive metal and / or a metal with a true density of the conductive spherical particles not exceeding ³ g / cm ³ in order to further increase the conductivity. It may be plated with an oxide.

As another method for obtaining the conductive spherical particles used in the present invention, conductive fine particles having a particle size smaller than that of the core particles are appropriately mixed with the core particles made of spherical resin particles. By mechanically mixing in a ratio, due to the action of Van der Waals force and electrostatic force, the conductive particles are uniformly attached around the core particles, and then, for example, a local temperature is generated by applying a mechanical impact force. There is a method of softening the surface of the core particle by the rise and forming conductive fine particles on the surface of the core particle to obtain spherical resin particles that have been made conductive.

As another method for obtaining the conductive spherical particles used in the present invention, the conductive fine particles are uniformly dispersed in spherical resin particles to obtain conductive spherical particles having the conductive fine particles dispersed therein. There is a method. As a method for uniformly dispersing the conductive fine particles in the spherical resin particles,
For example, a binder resin used for spherical resin particles and conductive fine particles are kneaded to disperse the conductive fine particles, followed by cooling and solidification, pulverization to a predetermined particle size, and mechanical treatment and thermal treatment. A method of obtaining conductive spherical particles by spheroidizing; or, adding a polymerization initiator, conductive fine particles and other additives to a polymerizable monomer used for spherical resin particles and uniformly dispersing them by a disperser. A method of obtaining spherical particles in which conductive fine particles are dispersed by suspending the monomer composition in an aqueous phase containing a dispersion stabilizer so as to have a predetermined particle size by a stirrer or the like and performing polymerization, Can be mentioned.

Next, the structure of the developer carrying member used in the present invention will be described.

The developer carrying member comprises a substrate and a resin coating layer surrounding and covering the substrate. The shape of the substrate includes a cylindrical member, a columnar member, a belt-shaped member and the like. A metal cylindrical member is preferably used in the developing method which is not in contact with the drum, and specifically, a metal cylindrical tube is preferably used. As the metal cylindrical tube, nonmagnetic ones such as stainless steel, aluminum and alloys thereof are preferably used. A cylindrical member having a layered structure containing rubber or elastomer such as urethane, EPDM, or silicon is preferably used as the substrate in the case of the developing method in which the drum is directly contacted.

Further, in the present invention using a magnetic developer, in order to magnetically attract and hold the developer on the developer carrying member, a magnet roller or the like having a magnet therein is provided inside the developer carrying member. Deploy. In that case, the base body may be cylindrical and a magnet roller may be disposed inside the base body. The method for forming the resin coating layer of the present invention is not particularly limited, and can be performed by an ordinary method. For example, a coating solution containing the binder resin for the coating layer and the quaternary ammonium salt compound is applied to the base material of the developer carrier by a method such as a dipping method, a spray method or a brush coating method, and dried. By doing so, the developer carrier used in the present invention can be obtained.

<2> Developer Used in the Present Invention Next, the developer used in the present invention to obtain a toner image as a visible image from an electrostatic latent image (hereinafter, also referred to as “toner”) will be described. .

The toner used in the present invention includes toner particles containing at least a binder resin component and magnetic powder, inorganic fine powder, and conductive fine powder having an average particle size larger than the inorganic fine powder and smaller than the toner. A magnetic toner that has a body and has an average circularity of 0.970 or more determined by the above formula (1), and in which the magnetic powder is not substantially exposed on the surface.

First, the circularity of toner will be described.

A toner composed of a toner having a circularity of 0.970 or more (powder composed of a toner particle group) is very excellent in transferability. It is considered that this is because the contact area between the toner particles and the photoconductor is small, and the adhesion force of the toner particles to the photoconductor due to the image force, the Van der Waals force, etc. is reduced. Therefore, when such a toner is used, the transfer rate is high and the transfer residual toner is greatly reduced, so that the toner at the pressure contact portion between the charging member and the photoconductor is very small, toner fusion is prevented, and image defects are generated. It is considered to be significantly suppressed.

Further, since toner particles having a circularity of 0.970 or more have almost no edge portion on the surface, friction is reduced at the pressure contact portion between the charging member and the photosensitive member, and abrasion of the photosensitive member surface is suppressed. Conceivable.

These effects become more prominent in the image forming method including the contact transfer step in which voids during transfer are likely to occur.

The circularity of the toner in the present invention is used as a simple method for quantitatively expressing the shape of toner particles. In the present invention, the flow type particle image measuring apparatus FPIA- manufactured by Toa Medical Electronics Co., Ltd. is used. Measurement was performed using a 1000 type, calculation was performed using the following formula (2), and the sum of circularity of all particles measured as shown in the following formula (3) was divided by the total number of particles (m). The value is defined as the average circularity (am).

[0116]

[6] circularity (ai) = L ₀ / L formula (2) (wherein, L ₀ represents the circumferential length of a circle having the same projected area as the magnetic toner particle image, L is the projected image of the magnetic toner particles Indicates the perimeter of.)

[0117]

[Equation 7] Here, the particle projection area is the area of the binarized toner particle image, and the perimeter of the particle projection image is defined as the length of the contour line obtained by connecting the edge points of the toner particle image.

The circularity in the present invention is an index showing the degree of unevenness of the developer particles, and it is 1.000 when the toner particles are completely spherical, and the smaller the surface shape becomes, the smaller the circularity is. Becomes

The measuring device "F" used in the present invention is used.
PIA-1000 "calculates the circularity of each particle, and then calculates the average circularity and the mode circularity, and the particles have a circularity of 0.40 to 1.00 depending on the circularity obtained.
A calculation method is used in which the average circularity is calculated using the center value and frequency of the divided points. However, the error between each value of the average circularity calculated by this calculation method and each value of the average circularity calculated by the above-mentioned calculation formula that directly uses the circularity of each particle is very small and substantially In the present invention, for the reason of handling data such as shortening of calculation time and simplification of calculation calculation formula, the calculation formula of directly using the circularity of each particle described above is used. You may use such a calculation method which changed a part using a concept.

The measurement procedure is as follows.

About 5 mg of the magnetic toner was dispersed in 10 ml of water in which about 0.1 mg of the surfactant was dissolved to prepare a dispersion, and the dispersion was irradiated with ultrasonic waves (20 KHz, 50 W) for 5 minutes to disperse the dispersion. The liquid concentration is set to 5000 to 20,000 / μl, and measurement is performed by the above-mentioned device to obtain the average circularity.

Further, the magnetic toner of the present invention is one in which the magnetic powder is not substantially exposed on the surface, and more specifically, it is present on the surface of the magnetic toner particles measured by X-ray photoelectron spectroscopy. The ratio (B / A) of the iron element content (B) to the carbon element content (A) is 0.001
It is preferably less than.

That is, in the image forming method including the contact charging step, when the magnetic toner in which the magnetic powder is exposed on the toner particle surface is used, the abrasion of the photoconductor due to the exposed magnetic powder becomes more remarkable. This is because it is easy. However, when the above-mentioned (B / A) is less than 0.001, that is, when the magnetic toner in which the magnetic powder is not substantially exposed on the surface of the toner particles is used, the toner is transferred to the surface of the photoconductor by the charging member. Even if pressed, the surface of the photoconductor is hardly scraped, and it becomes possible to significantly reduce the scraping of the photoconductor and toner fusion.

The ratio (B) of the iron element content (B) to the carbon element content (A) existing on the surface of the magnetic toner (B)
/ A) can be calculated by performing surface composition analysis by ESCA (X-ray photoelectron spectroscopy analysis).

In the present invention, the ESCA device and measurement conditions are as follows. Apparatus used: PHI 1600S type X-ray photoelectron spectrometer Measurement conditions: X-ray source MgKα (400 W) Spectral range 800 μmφ In the present invention, from the measured peak intensity of each element, PH
The surface atomic concentration is calculated using the relative sensitivity factor provided by Company I. In this measurement, it is preferable to carry out ultrasonic cleaning of the toner to remove the inorganic fine powder and the like adhering to the surface of the magnetic toner particles, and then to separate by magnetic force and to dry and measure.

A special toner in which magnetic powder particles are contained only in a specific portion inside the particles is disclosed in JP-A-7-2.
It has already been disclosed in Japanese Patent Publication No. 09904. However, in Japanese Patent Laid-Open No. 7-209904,
No mention is made of the circularity of the disclosed toner.

In the image forming method of the present invention, the use of a toner having a specific circularity is an essential element, and the toner as described in JP-A-7-209904 is used in the use form of the present invention. However, it is unclear whether a similar effect will appear. To summarize the toner constitution disclosed in Japanese Patent Laid-Open No. 7-209904, the toner layer has a structure in which a resin layer containing no magnetic powder particles is formed near the surface of the toner particles with a certain thickness or more. This means that there is a considerable proportion of the toner surface layer portion where the magnetic powder particles are not present. In other words, however, in such a toner, when the average particle diameter is as small as 10 μm, for example, the volume in which the magnetic powder particles can exist becomes small, so that it is difficult to include a sufficient amount of the magnetic powder particles. . Moreover, in such a toner, the ratio of the surface resin layer in which the magnetic powder particles do not exist differs between the toner particles having a large particle size and the particles having a small particle size distribution in the toner particle size distribution, and therefore, the included magnetic powder content also Since they are different, the developability and transferability also differ depending on the particle size of the toner, and the selective developability depending on the particle size is easily seen. Therefore, when printing is performed for a long time with such a magnetic toner, particles containing a large amount of magnetic powder and hard to develop, that is, toner particles having a large particle size, tend to remain, resulting in deterioration of image density and image quality, and further It also leads to deterioration.

Therefore, in the present invention, the dispersion state of the magnetic powder in the toner particles may be set to the following preferable dispersion state. The preferable dispersed state of the magnetic powder in the toner particles is a state in which the magnetic powder particles are present in the entire toner particles as uniformly as possible without aggregation. That is, when the volume average particle diameter of the toner is C, and the minimum value of the distance between the magnetic powder and the toner particle surface is D in observation of the tomographic plane of the magnetic toner using a transmission electron microscope (TEM), D / C ≦
Using a magnetic toner of 0.02 is also one of the features of the present invention.

The method of adjusting D / C ≦ 0.02 in the present invention includes controlling the kind of the surface treatment agent for the magnetic powder and the uniformity of the treatment.

The volume average particle diameter C of the magnetic toner in the present invention can be measured by a Coulter Multisizer described later, and D can be measured as follows. As a specific observing method by TEM, after the toner particles to be observed are sufficiently dispersed in a room temperature curable epoxy resin, a cured product obtained by curing for 2 days in an atmosphere at a temperature of 40 ° C. Alternatively, a method of freezing and observing as a flaky sample with a microtome equipped with diamond teeth is preferable.

In the image forming method of the present invention, in order to further improve the image quality and faithfully develop finer latent image dots, the weight average particle diameter of the toner is 3 to 10 μm, more preferably 4 to 8 μm. Preferably there is. Weight average particle size is 3μ
When the toner is smaller than m, the transfer residual toner on the photoconductor increases due to a decrease in transfer efficiency, and it tends to be difficult to suppress abrasion of the photoconductor or toner fusion in the contact charging step. In addition to increasing the total surface area of the toner,
The flowability and agitation of the toner are reduced, and it becomes difficult to uniformly charge the individual toner particles, so that fog and transferability tend to deteriorate, and in addition to scraping and fusing, it is a cause of uneven image uniformity. This is not preferable for the toner used in the present invention because it tends to occur. Further, when the weight average particle diameter of the toner exceeds 10 μm, scatter easily occurs in characters and line images, and it is difficult to obtain high resolution. Further, as the image forming apparatus becomes higher in resolution, the reproduction of one dot tends to deteriorate with toner of 8 μm or more.

The average particle size of the toner can be measured by various methods such as Coulter Counter TA-II type or Coulter Multisizer (manufactured by Beckman Coulter), but in the present invention, Coulter Multisizer (manufactured by Beckman Coulter) is used. An interface (made by Nikkaki) and PC980 that outputs the number distribution and volume distribution by using
1 Personal computer (manufactured by NEC) is connected, and the electrolyte is a 1% NaCl aqueous solution prepared using primary sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used.

The measuring method is as follows:
A surfactant, preferably 0.1 to 5 ml of alkylbenzene sulfonate, is added as a dispersant to 150 ml,
Further, 2 to 20 mg of the measurement sample is added. The electrolytic solution in which the sample is suspended is dispersed by an ultrasonic disperser for about 1 to 3 minutes, and the volume and the number of toner particles of 2 μm or more are measured by the Coulter Multisizer using a 100 μm aperture as an aperture. The distribution and the number distribution are calculated.

Then, the volume-based weight average particle diameter (D4) determined from the volume distribution according to the present invention is determined.

In the present invention, the toner particles are polymerized,
Particularly, it is preferable that the magnetic toner of the present invention is produced by the suspension polymerization method, and then the inorganic fine powder and the conductive fine powder are mixed and added to adhere the inorganic fine powder and the conductive fine powder to the surface. In this suspension polymerization method, the polymerizable monomer serving as the binder resin component, the magnetic powder, and the colorant (further, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives) are uniformly added. After being dissolved or dispersed in to form a polymerizable monomer system, this polymerizable monomer system is dispersed in a continuous layer (for example, an aqueous medium) containing a dispersion stabilizer by using an appropriate stirrer to simultaneously perform the polymerization reaction. To obtain a toner having a desired particle size. The toner obtained by this suspension polymerization method (hereinafter referred to as a polymerized toner) has a substantially spherical individual toner particle shape, so that a toner having a circularity of 0.970 or more, which is an essential physical property requirement of the present invention, is obtained. Easy to get caught.
In addition, in this invention, an aqueous medium is a medium which has water as a main component. Specifically, water itself as an aqueous medium, water with a small amount of a surfactant added, and water pH
Examples include those to which a preparation agent has been added and those to which an organic solvent has been added to water.

However, it is difficult to suppress the exposure of the magnetic powder from the particle surface even if the polymerized toner contains the usual magnetic powder. Further, not only the fluidity and charging characteristics of the toner particles are significantly deteriorated, but also the strong interaction between the magnetic powder and water during the production of the suspension-polymerized toner makes it possible to obtain a toner having an average circularity of 0.970 or more. Hard to get. This is because first of all, the magnetic powder particles are generally hydrophilic so that they tend to be present on the toner surface. It is considered that the reason is that the surface of the turbid particles is dragged and the shape is distorted and is unlikely to be circular. In order to solve these problems, it is important to modify the surface characteristics of magnetic powder particles. Since the magnetic powder has excellent hydrophobicity and dispersibility, the magnetic powder used in the polymerized toner in the present invention has a surface which is dispersed in an aqueous medium so that the magnetic powder has a primary particle size and a cup shape. It is preferably a magnetic powder treated while hydrolyzing the ring agent. This hydrophobizing method is less likely to cause coalescence of magnetic powder particles than in the case of treating in the gas phase, and the electrostatic repulsion action between the magnetic powder particles due to the hydrophobizing operation works, and the magnetic powder is almost the primary particles. The surface is treated in the state of.

When the magnetic powder is used as a material for polymerized toner, the dispersibility in the toner particles becomes very good, and the magnetic powder is not exposed on the surface of the toner particles, and the magnetic toner is almost spherical. Can be obtained. That is, the average circularity is 0.970 or more, and the ratio (B / A) of (B) to the content (A) of the carbon element present on the surface of the magnetic toner measured by X-ray photoelectron spectroscopy is 0.1. 0
It is possible to obtain a magnetic toner of less than 01.

Examples of coupling agents that can be used in the surface treatment of the magnetic powder according to the present invention include silane coupling agents and titanium coupling agents. The treatment amount was 0. 0 with respect to 100 parts by mass of the magnetic powder.
05 to 20 parts by mass, preferably 0.1 to 10 parts by mass.

In the magnetic powder thus obtained, no particle agglomeration is observed and the surface of each particle is uniformly subjected to a hydrophobic treatment. Therefore, when used as a material for polymerized toner, dispersibility in toner particles is improved. Is very good. Moreover, there is no exposure from the surface of the toner particles, and a polymerized toner having a substantially spherical shape can be obtained.

The magnetic powder used in the toner of the present invention is 10 to 200 parts by weight per 100 parts by weight of the binder resin component.
It is preferable to use parts by mass. More preferably 20-
It is preferable to use 180 parts by mass. If it is less than 10 parts by mass, the coloring power of the toner is poor and it is difficult to suppress fog. On the other hand, when the amount exceeds 200 parts by mass, the holding force by the magnetic force to the developer carrying member is increased, the developing property is deteriorated, and it is difficult to uniformly disperse the magnetic powder to each toner particle, and the fixing property is also improved. Tends to decrease.

The magnetic powder used in the present invention includes magnetic iron oxides such as magnetite, maghemite and ferrite, metals such as iron, cobalt and nickel, or these metals and aluminum, cobalt, copper, lead and magnesium,
Examples thereof include alloys of metals such as tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof, and those mainly composed of magnetite are preferable.

The shape of the magnetic powder may be octahedron, hexahedron, sphere, needle, scaly shape, etc., but the one with less anisotropy such as octahedron, hexahedron, sphere, or irregular shape is imaged. It is preferable for increasing the concentration. The shape of such magnetic powder is SE
It can be confirmed by M or the like. The average particle size of the magnetic powder is preferably 0.01 to 1.0 μm, more preferably 0.05 to 0.5 μm. When the average particle size is less than 0.01 μm, the blackness is significantly reduced, the coloring power is insufficient as a colorant for black and white toners, and the composite oxide particles are strongly aggregated, resulting in dispersion. Sex tends to deteriorate. On the other hand, if the average particle size exceeds 1.0 μm, the coloring power becomes insufficient as in the case of general colorants. In addition, particularly when used as a colorant for a toner having a small particle diameter, it is stochastically difficult to disperse the same number of magnetic powders in each toner particle, and the dispersibility tends to deteriorate. The average particle size of the magnetic powder can be measured using a transmission electron microscope. Specifically, the powder sample of the toner to be measured is observed with a transmission electron microscope, 100 magnetic powder particle diameters in the visual field are measured, and the number average particle diameter is calculated and used as the average particle diameter.

Furthermore, in addition to the magnetic powder, other coloring agent may be used in combination. Examples of the coloring material that can be used in combination include magnetic or non-magnetic inorganic compounds, known dyes and pigments. Specifically, for example, ferromagnetic metal particles such as cobalt and nickel, or chromium, manganese, and
Examples thereof include copper, zinc, aluminum, alloys containing rare earth elements, particles such as hematite, titanium black, nigrosine dye / pigment, carbon black, and phthalocyanine. These may also be used by treating the surface with a coupling agent as with the magnetic powder.

It is also one of the preferable usage forms that the toner according to the present invention contains a releasing agent.

The toner image transferred onto the transfer material is then transferred to
It is fixed on the transfer material by heat, pressure, or other energy, and a semi-permanent image is obtained. At this time, hot roll type fixing is generally used.

As described above, the weight average particle diameter is 10 μm.
An extremely high-definition image can be obtained by using the following toners, but the toner particles with a small particle size enter the gaps between the fibers of the paper when a transfer material such as paper is used, and the toner from the heat fixing roller is used. Insufficient heat reception causes low temperature offset. However, in the toner according to the present invention, by containing an appropriate amount of the release agent as the release agent, it becomes possible to prevent abrasion of the photoconductor while achieving both high resolution and offset resistance.

Examples of the releasing agent that can be used in the toner according to the present invention include petroleum waxes such as paraffin wax, microcrystalline wax and petrolactam and their derivatives, montan wax and its derivatives, hydrocarbon wax by the Fischer-Tropsch method and Derivatives, polyolefin waxes represented by polyethylene and their derivatives, natural waxes such as carnauba wax and candelilla wax and their derivatives, and the derivatives include oxides, block copolymers with vinyl monomers, and graft modified products. Including. Furthermore, fatty acids such as higher aliphatic alcohols, stearic acid and palmitic acid, or compounds thereof, acid amide wax, ester wax, ketone, hydrogenated castor oil and its derivatives, plant wax,
The endothermic peak in the differential thermal analysis of animal wax is 45
It is preferably in the range of 50 ° C. or higher and 110 ° C. or lower, and more preferably 50 ° C. or higher and 90 ° C. or lower.

When the release agent is used, its content is preferably in the range of 0.5 to 50% by mass based on the whole toner. If the content is less than 0.5% by mass, the low-temperature offset suppressing effect is poor, and if it exceeds 50% by mass, the long-term storability is deteriorated and the dispersibility of other toner materials is deteriorated, resulting in a toner fluidity. And deterioration of image characteristics.

The toner relating to the image forming method of the present invention may be blended with a charge control agent in order to stabilize the charging characteristics. Known charge control agents can be used,
In particular, a charge control agent having a high charging speed and capable of stably maintaining a constant charge amount is preferable. Further, when the toner is produced by the direct polymerization method, a charge control agent having a low polymerization inhibitory property and substantially no solubilized product in the aqueous dispersion medium is particularly preferable. Specific compounds include salicylic acid as a negatively chargeable charge control agent, alkylsalicylic acid, dialkylsalicylic acid, naphthoic acid, a metal compound of an aromatic carboxylic acid such as dicarboxylic acid, a metal salt or a metal complex of an azo dye or an azo pigment, Polymeric compounds having a sulfonic acid or carboxylic acid group in the side chain, boron compounds, urea compounds, silicon compounds, calixarene and the like can be mentioned. As a method of incorporating the charge control agent into the toner,
There are a method of adding inside the toner particle and a method of adding externally.
The amount of these charge control agents used is determined by the type of binder resin component, the presence or absence of other additives, and the toner manufacturing method including the dispersion method, and is not uniquely limited. , 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 component.
Used in the range of parts by mass.

A method of producing a toner by the suspension polymerization method, which is related to the image forming method of the invention, will be described.

The following are examples of the polymerizable monomer that constitutes the polymerizable monomer system used in the polymerized toner according to the present invention.

Examples of the polymerizable monomer include styrene-based monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene and p-ethylstyrene; methyl acrylate and acryl. Ethyl acetate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, etc. Acrylic esters; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, methacrylic acid. Phenyl, dimethylaminoethyl methacrylate, methacrylic acid esters such as diethylaminoethyl methacrylate; and other acrylonitrile, methacrylonitrile, and the like monomers acrylamide.

These polymerizable monomers may be used alone or in combination. Among the above-mentioned polymerizable monomers, it is preferable to use styrene or a styrene derivative alone or in combination with other monomers, from the viewpoints of developing characteristics and durability of the toner.

In the production of the polymerized toner according to the present invention, a resin may be added to the polymerizable monomer system for polymerization.
For example, hydrophilic monomers such as amino groups, carboxylic acid groups, hydroxyl groups, sulfonic acid groups, glycidyl groups, and nitrile groups cannot be used because the polymerizable monomers are water-soluble and dissolve in an aqueous suspension to cause emulsion polymerization. When it is desired to introduce a group-containing monomer component into the toner, a random copolymer, a block copolymer, a graft copolymer or the like of these and a vinyl compound such as styrene or ethylene is used, or polyester, polyamide It may be used in the form of a polycondensate such as polyether, a polyaddition polymer such as polyether or polyimine. When such a high molecular weight polymer containing a polar functional group is coexisted in the toner, the wax component is phase-separated, the inclusion becomes stronger, and the toner having good offset resistance, blocking resistance, and low temperature fixing property is obtained. Obtainable. When such a polymer having a polar functional group is used, its average molecular weight is preferably 5,000 or more. When it is 5,000 or less, especially 4,000 or less, the present polymer tends to concentrate near the surface, and
It is not preferable because the blocking resistance is likely to be adversely affected.

As the polar polymer, a polyester resin is particularly preferable.

Further, a resin other than the above may be added to the polymerizable monomer system for the purpose of improving the dispersibility and fixing property of the material, the image characteristics, and the like.
For example, polystyrene, homopolymers of styrene such as polystyrene and polyvinyltoluene, and substitution products thereof; styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, Styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-
Octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methylmethacrylate copolymer, styrene-ethylmethacrylate copolymer, styrene-butylmethacrylate copolymer, styrene- Dimethylaminoethyl methacrylate copolymer,
Styrene-vinyl methyl ether copolymer, styrene-
Styrene series such as vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer Copolymer; polymethylmethacrylate, polybutylmethacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin, polyacrylic acid resin, rosin, modified rosin, tempel resin, phenol resin , Aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins and the like can be used alone or in combination.

The addition amount of these resins is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer. If it is less than 1 part by mass, the effect of addition is small, while if it is added in an amount of 20 parts by mass or more, it tends to be difficult to design various physical properties of the polymerized toner.

Further, when a polymer having a molecular weight different from the molecular weight range of the toner obtained by polymerizing the polymerizable monomer is dissolved in the polymerizable monomer system and polymerized, a wide molecular weight distribution is obtained.
It is possible to obtain toner with high offset resistance.

As the polymerization initiator used in the production of the polymerized toner relating to the image forming method of the present invention, those having a half-life of 0.5 to 30 hours at the time of the polymerization reaction are added to the polymerizable monomer in an amount of 0. When the polymerization reaction is carried out with an addition amount of 5 to 20 parts by mass, a polymer having a maximum in the molecular weight of 10,000 to 100,000 can be obtained, and the toner can have desired strength and appropriate melting characteristics. Examples of the polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile),
2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-
Azo-based or diazo-based polymerization initiators such as azobis-4-methoxy-2,4-dimethylvaleronitrile and azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2 , 4
Examples thereof include peroxide-based polymerization initiators such as dichlorobenzoyl peroxide, lauroyl peroxide, and t-butylperoxy 2-ethylhexanoate.

When the polymerized toner relating to the image forming method of the present invention is produced, a crosslinking agent may be added, and the preferable addition amount is 0.001 to 1 with respect to the polymerizable monomer system.
It is 5% by mass.

As the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used. For example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene, etc .; for example, ethylene glycol diacrylate, Ethylene glycol dimethacrylate,
A carboxylic acid ester having two double bonds such as 1,3-butanediol dimethacrylate; a divinyl compound such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and a compound having three or more vinyl groups; Are used alone or as a mixture.

In the method for producing a polymerized toner relating to the image forming method of the present invention, generally, the above-mentioned toner composition, that is, the polymerizable monomer, magnetic powder, release agent, plasticizer, charge control agent, crosslinking agent, In some cases, components necessary for toner such as a colorant and other additives, for example, an organic solvent, which is added to reduce the viscosity of the polymer produced by the polymerization reaction, a high molecular polymer, a dispersant, etc. are appropriately added, and a homogenizer, The polymerizable monomer system uniformly dissolved or dispersed by a disperser such as a ball mill, colloid mill or ultrasonic disperser is suspended in an aqueous medium containing a dispersion stabilizer. At this time, the particle size of the obtained toner particles becomes sharper by using a high-speed stirrer or a high-speed disperser such as an ultrasonic disperser to immediately make the desired toner particle size. Regarding the timing of adding the polymerization initiator, it may be added at the same time as the addition of other additives to the polymerizable monomer, or may be mixed immediately before the suspension in the aqueous medium. It is also possible to add a polymerization initiator dissolved in a polymerizable monomer or a solvent immediately after granulation and before starting the polymerization reaction.

After the granulation, an ordinary stirrer may be used to stir the particles so that the particle state is maintained and the particles are prevented from floating and settling.

In the case of producing a polymerized toner relating to the image forming method of the present invention, known surfactants and organic / inorganic dispersants can be used as the dispersion stabilizer, and among them, the inorganic dispersant produces harmful ultrafine powder. Since it is difficult to obtain, and the dispersion stability is obtained due to its steric hindrance, the stability does not easily deteriorate even when the reaction temperature is changed, and the cleaning is easy and the toner is not adversely affected.
It can be preferably used. Examples of such inorganic dispersants include calcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, and other polyvalent metal salts of phosphate, calcium carbonate,
Examples thereof include carbonates such as magnesium carbonate, inorganic salts such as calcium metasilicate, calcium sulfate and barium sulfate, and inorganic oxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silica, bentonite and alumina.

These inorganic dispersants are used as the polymerizable monomer 10
It is desirable to use 0.2 to 20 parts by mass per 0 parts by mass, but it is difficult to generate ultrafine particles, but it is not enough to atomize the toner, so 0.001 to 0.
You may use together 1 mass part surfactant.

Examples of the surfactant include sodium dodecylbenzenesulfate, sodium tetradecylsulfate, sodium pentadecylsulfate, sodium octylsulfate,
Examples thereof include sodium oleate, sodium laurate, sodium stearate, potassium stearate and the like.

When these inorganic dispersants are used, they may be used as they are, but in order to obtain finer particles, it is preferable to generate the inorganic dispersant particles in an aqueous medium. For example, in the case of calcium phosphate, by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring to generate water-insoluble calcium phosphate,
A more uniform and fine dispersion is possible. At this time, a water-soluble sodium chloride salt is by-produced at the same time, but when the water-soluble salt is present in the aqueous medium, the dissolution of the polymerizable monomer in water is suppressed, and the ultrafine toner particles due to emulsion polymerization are It is more convenient because it is less likely to occur. Since it becomes an obstacle when removing the remaining polymerizable monomer at the end of the polymerization reaction, it is better to replace the aqueous medium or desalt with an ion exchange resin.
The inorganic dispersant can be almost completely removed by dissolving it with an acid or an alkali after completion of the polymerization.

In the polymerization step, the polymerization temperature is 40
Polymerization is carried out at a temperature of not less than 0 ° C, generally 50 to 90 ° C. When the polymerization is carried out within this temperature range, the release agent and waxes to be sealed inside are precipitated by phase separation and the encapsulation becomes more complete. In order to consume the remaining polymerizable monomer, the reaction temperature is 90 to 15 at the end of the polymerization reaction.
It is possible to raise it to 0 ° C.

In the present invention, it is also important that the fine inorganic powder is added to the toner as a fluidizing agent. The inorganic fine powder is added to improve the fluidity of the toner and make the toner particles evenly charged, but the inorganic fine powder is subjected to a treatment such as a hydrophobic treatment to adjust the toner charge amount and improve the environmental stability. It is also a preferable form to impart the function of.

The inorganic fine powder preferably has an average primary particle size of 4 to 80 nm. When the average primary particle size is larger than 80 nm,
Alternatively, when the inorganic fine powder having a particle size of 80 nm or less is not added, when the transfer residual toner adheres to the charging member, it tends to adhere to the charging member, and it is difficult to stably obtain good charging characteristics. Further, good fluidity of the toner is not obtained, charge impartment to the toner particles is likely to be non-uniform, and problems such as increased fog, reduced image density, and toner scattering cannot be avoided. When the average primary particle size of the inorganic fine powder is smaller than 4 nm, the inorganic fine powder has a strong cohesive property, and is not a primary particle but is hard to be broken by crushing treatment. It tends to act as an aggregate, and image defects due to development of aggregates, damage to the image bearing member or the developing bearing member, and the like are likely to occur.

In order to make the charge distribution of the toner particles more uniform, the average primary particle size of the inorganic fine powder is more preferably 6 to 35 nm.

In the present invention, the average primary particle size of the inorganic fine powder is measured as follows. The surface of the toner is contrasted with the photograph of the toner magnified by the scanning electron microscope and the photograph of the toner mapped by the element contained in the inorganic fine powder by the element analysis means such as XMA attached to the scanning electron microscope. It can be measured by measuring 100 or more primary particles of the inorganic fine powder existing in the state of being adhered to or separated from and measuring the number average particle diameter.

As the inorganic fine powder used in the present invention,
Silica, alumina, titania, etc. can be used.

For example, as the silica, 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 can be used. However, dry silica having less silanol groups on the surface and inside the silica fine powder and having less production residue of Na ₂ O, SO ₃ ^2-, etc. is preferable. Further, in the case of dry silica, it is also possible to obtain a composite fine powder of silica and other metal oxide by using other metal halogen compound such as aluminum chloride and titanium chloride together with the silicon halogen compound in the manufacturing process. Also includes.

The addition amount of the inorganic fine powder having an average primary particle diameter of 4 to 80 nm is 0.1 to 3.0% by mass with respect to the toner particles.
If the addition amount is less than 0.1% by mass, the effect is not sufficient, and if it is 3.0% by mass or more, the fixing property tends to deteriorate.

The inorganic fine powder is preferably one which has been subjected to a hydrophobizing treatment in view of the characteristics in a high temperature and high humidity environment. This is because when the inorganic fine powder added to the toner absorbs moisture, the charge amount of the toner particles is significantly reduced, and toner scattering easily occurs.

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, organic titanium compounds, etc. are used alone. Alternatively, it may be used in combination.

Among them, the one treated with silicone oil is preferable, and more preferably, the one treated with silicone oil at the same time as or after the hydrophobic treatment of the inorganic fine powder is treated with silicone oil even in a high humidity environment. It is good for keeping the value high and preventing toner scattering.

Specifically, for example, a silylation reaction is performed as a first step reaction to eliminate silanol groups by a chemical bond, and then a second step reaction is performed to form a hydrophobic thin film on the surface with silicone oil. it can.

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 it is less than 10 mm ² / s, the inorganic fine powder is not stable and the image quality tends to deteriorate due to heat and mechanical stress. If it exceeds 200,000 mm ² / s,
Uniform treatment tends to be difficult.

As the silicone oil to be used, for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil and the like 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 an appropriate 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 the 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 too small, good hydrophobicity cannot be obtained, and if it is too large, problems such as fog may occur.

The average primary particle size used in the present invention is 80 n.
m or less of the inorganic fine powder has a specific surface area by nitrogen adsorption measured by BET method is preferably one in 20~250m ² / g range, more preferably better ones 40 to 200 m ² / g.

The specific surface area was determined according to the BET method by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) and calculating the specific surface area using the BET multipoint method. To be

Further, the toner according to the present invention preferably contains conductive fine powder which is larger than the number average primary particle diameter of the inorganic fine powder and smaller than the weight average particle diameter of the toner. Although the number average primary particle diameter and the weight average particle diameter are not compared on the same scale, since the inorganic fine powder is relatively smaller than the conductive fine powder and the conductive fine powder is relatively smaller than the toner, the present invention In the above, these were used as one index for comparing the sizes of the conductive fine powders.

The conductive fine powder has a volume average particle diameter of 0.1 to 0.1.
The thickness is preferably 10 μm. When the volume average particle diameter of the conductive fine powder is small, it is preferable to set the content of the conductive fine powder in the whole toner to be small in order to prevent the deterioration of the developing property. Volume average particle diameter of conductive fine powder is 0.1
If it is less than μm, an effective amount of the conductive fine powder cannot be secured, and in the charging step, the charging of the image bearing member is performed favorably by overcoming the charging inhibition due to the adhesion and mixing of the insulating transfer residual toner to the contact charging member. A sufficient amount of conductive fine powder to
Since it cannot be interposed in the contact area between the charging member and the image carrier or in the charging area in the vicinity thereof, charging failure is likely to occur. From this viewpoint, the volume average particle diameter of the conductive fine powder is preferably 0.15 μm or more, more preferably 0.2 μm or more and 5 μm or less.

The volume average particle diameter of the conductive fine powder is 10
If it is larger than μm, the conductive fine powder that has fallen off the charging member tends to block or diffuse the exposure light for writing the electrostatic latent image, resulting in a defect of the electrostatic latent image and lowering the image quality.
Furthermore, if the volume average particle diameter of the conductive fine powder is large, the number of particles per unit weight decreases, so the conductive fine powder should be reduced in consideration of reduction and deterioration due to the conductive fine powder falling off from the charging member. In order to continuously supply the conductive fine powder to the contact area between the charging member and the image carrier or to the charging area in the vicinity thereof, and to cause the conductive fine powder to intervene, the contact charging member transfers to the image carrier via the conductive fine powder. In order to maintain the dense contact property and stably obtain the good charging property, the content of the conductive fine powder in the whole toner must be increased. However, if the content of the conductive fine powder is too large, the developability is lowered, especially in a high humidity environment, 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 preferably 5 μm or less.

The content of the conductive fine powder with respect to the entire toner is preferably 0.1 to 10% by mass. If the content of the conductive fine powder in the total toner is less than 0.1% by mass, the charging of the image bearing member is improved by overcoming the charging inhibition due to the adhesion / mixing of the insulating transfer residual toner to the contact charging member. It is not possible to intervene a sufficient amount of conductive fine powder to cause contact between the charging member and the image bearing member or the charging area in the vicinity thereof, and the charging property is likely to deteriorate, resulting in poor charging. . On the other hand, if the content is more than 10% by mass, the amount of the conductive fine powder collected by the cleaning at the same time as the development becomes too much, which deteriorates the chargeability and the developability of the toner in the developing portion, resulting in a decrease in the image density and Toner is easily scattered. The content of the conductive fine powder with respect to the entire toner is preferably 0.2 to 5 mass%.

The resistance of the conductive fine powder is 10 ⁹ Ωcm.
The following are preferred. If the resistance of the conductive fine powder is larger than 10 ⁹ Ωcm, the conductive fine powder is interposed in the contact area between the charging member and the image carrier or in the charging area in the vicinity thereof, and the conductive fine powder of the contact charging member is interposed. Even if the close contact with the image bearing member is maintained, it is difficult to obtain the charge promoting effect for obtaining good chargeability.

Moreover, the resistance of the conductive fine powder is 10 ⁶ Ωcm.
The following is preferable for overcoming the charging inhibition due to the adhesion / mixing of the insulating transfer residual toner to the contact charging member and for better charging of the image carrier.

In order to sufficiently bring out the charge accelerating effect of the conductive fine powder and to stably obtain a good charging property, the resistance of the conductive fine powder is brought into contact with the surface portion of the contact charging member or the image carrier. It is preferably smaller than the resistance of the part.

Further, it is preferable that the conductive fine powder is a transparent, white or light-colored conductive fine powder because the influence on the color reproducibility of the conductive fine powder transferred onto the transfer material is prevented. . Even in the sense that it does not interfere with the exposure light in the electrostatic latent image forming step, the conductive fine powder may be transparent, white or light-colored conductive fine powder, and more preferably,
The transmittance of the conductive fine powder for exposure light is preferably 30% or more.

In the present invention, the light transmittance of the conductive fine powder can be measured by the following procedure. The transmittance is measured in a state where one layer of conductive fine powder is fixed on a transparent film having an adhesive layer on one surface. The light is emitted from the vertical direction of the sheet, and the light transmitted to the back surface of the film is condensed to measure the light amount. The transmittance of the conductive fine powder is calculated as the net amount of light from the amount of light when only the film is attached to the conductive fine powder. Actually, it is measured using a 310T transmission densitometer manufactured by X-Rite.

The conductive fine powder is preferably non-magnetic. Since the conductive fine powder is non-magnetic, it is transparent,
It is easy to obtain white or light conductive fine powder. On the contrary, it is difficult for the conductive fine powder having magnetism to be transparent, white or light colored. 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. Shortage and the accumulation of conductive fine powder on the surface of the developer carrying member tend to cause problems such as hindering development of toner particles. Furthermore, if magnetic conductive fine powder is added to magnetic toner particles, it tends to be difficult for the conductive fine powder to separate 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.

Examples of the conductive fine powder in the present invention include 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. , Indium oxide, silicon oxide, magnesium oxide,
Metal oxides such as barium oxide, molybdenum oxide, iron oxide and tungsten oxide; metal compounds such as molybdenum sulfide, cadmium sulfide and potassium titanate, or composite oxides of these, adjust the particle size and particle size distribution as necessary. It can be used. Among these, fine powders of conductive inorganic oxide such as zinc oxide, tin oxide and titanium oxide are particularly preferable.

Further, for the purpose of controlling the resistance value of the conductive inorganic oxide fine powder, a metal oxide doped with an element such as antimony or aluminum, or a fine powder having a conductive material on its surface can be used. Examples thereof include titanium oxide fine powder surface-treated with tin oxide / antimony, stannic oxide fine powder doped with antimony, and stannic oxide fine powder.

Commercially available tin oxide / antimony-treated conductive titanium oxide fine powder is, 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 oxides include SH-. S (Japan Chemical Industry Co., Ltd.) and the like can be mentioned.

A method for measuring the volume average particle diameter of the above conductive fine powder will be exemplified. Coulter's LS-230 type laser diffraction particle size distribution measuring device is equipped with a liquid module to set a particle size of 0.04 to 2000 μm as a measurement range, and the volume average particle size of the conductive fine powder is determined from the obtained particle size distribution based on the volume. Calculate the diameter. As a measurement procedure, a trace amount of a surfactant is added to 10 cc of pure water, and a sample 1 of conductive fine powder is added to this.
0 mg was added, and ultrasonic dispersion machine (ultrasonic homogenizer)
After 10 minutes of dispersion, measurement time 90 seconds, number of measurements 1
Measure in times.

In the measurement from the toner, pure water 100
Toner 2 to 1 by adding a trace amount of surfactant to g
After adding 0 g and dispersing with an ultrasonic disperser (ultrasonic homogenizer) for 10 minutes, 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, the method of adjusting the particle size of the conductive fine powder is not limited to the method of setting the manufacturing method and the manufacturing conditions such that the primary particles of the conductive fine powder can obtain a desired particle size at the time of manufacturing. Also, a method of aggregating small particles of primary particles, a method of crushing large particles of primary particles, a method by classification, etc. are possible, and further, a part or all of the surface of the base material particle having a desired particle size is electrically conductive. A method of attaching or fixing conductive particles, a method of using conductive particles having a form in which a conductive component is dispersed in particles having a desired particle size, and the like are also possible. It is also possible to adjust.

The particle size when the particles of the conductive fine powder are formed as an agglomerate is defined as the average particle size of 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, the form is not limited 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, and the function of assisting or promoting charging can be realized.

In the present invention, the resistance of the conductive fine powder can be measured by the tablet method and normalized. That is, approximately 0.5 in a cylinder with a bottom area of 2.26 cm ^2.
A powder sample (g) is put into the upper and lower electrodes, and a pressure of 15 kg is applied to the upper and lower electrodes.

The toner used in the present invention may further contain other additives within a range that does not have a substantial adverse effect, such as lubricant powders such as Teflon (registered trademark) powder, zinc stearate powder and polyvinylidene fluoride powder. Or cerium oxide powder, silicon carbide powder, abrasives such as strontium titanate powder, or titanium oxide powder, fluidity-imparting agent such as aluminum oxide powder, anti-caking agent, also reverse polarity organic fine particles, and inorganic fine particles It can also be used in a small amount as a developability improver. It is also possible to use these additives after the surface is hydrophobized.

<3> Image Forming Method and Image Forming Apparatus of the Present Invention In the image forming method of the present invention, a charging step of applying a voltage to a charging member to charge the image bearing member, and a charged image bearing member, An electrostatic latent image forming step of forming an electrostatic latent image, a developing step including the following (a) to (d), and (a) carrying a developer contained in a developing container on a developer carrier. A step of: (b) a step of regulating the layer thickness of the developer on the developer carrier by a developer layer thickness regulating member;
(C) A step of carrying and carrying the developer whose layer thickness is regulated to a developing area where the developer carrying member and the image carrying member face each other;
(D) A step of transferring the developer on the developer carrier to an electrostatic latent image on the image carrier to form a toner image; the toner image formed on the surface of the image carrier is electrostatically transferred onto a transfer material. And a fixing step of heating and fixing the toner image transferred onto the transfer material, the developing step comprises the step of transferring the toner image onto the transfer material and then onto the image carrier. The image forming method also serves as a cleaning step for collecting the remaining developer, wherein the developer is the magnetic developer and the developer carrier is the developer carrier. The image forming apparatus of the present invention uses the image forming method of the present invention.

The charging step in the present invention is a step of charging the image bearing member by applying a voltage to the charging member which forms a contact portion with the image bearing member and is in contact therewith, and at least the charging member and the image bearing member. The conductive fine powder contained in the toner adheres to the image bearing member in the developing step at the contact portion with the body and / or in the vicinity thereof, and remains on the image bearing body even after the transferring step and is carried and intervened. is doing.

An image forming apparatus using the image forming method of the present invention will be described below with reference to the drawings, but the present invention is not limited to these.

FIG. 1 is a schematic view of the developing device of the present invention using a magnetic one-component developer. In FIG. 1, an image carrier that holds an electrostatic latent image formed by a known process, for example, the electrophotographic photosensitive drum 1 is rotated in the arrow B direction. The developing sleeve 8 as a developer carrying member carries the developer 4 having the magnetic toner supplied by the hopper 3 as a developing container and rotates in the direction of arrow A, so that the developing sleeve 8 and the photosensitive drum 1 are separated from each other. The developer 4 is conveyed to the developing area D facing each other. As shown in FIG. 1, the developer 4 is placed inside the developing sleeve 8.
A magnet roller 5 in which a magnet is inscribed is arranged on the top for magnetic attraction and holding.

The developing sleeve 8 used in the developing device in the present invention may use the above-mentioned developer carrying member, and specifically, has the resin coating layer 7 coated on the metal cylindrical tube 6 as the base. A stirring blade 10 for stirring the developer 4 is provided in the hopper 3. Reference numeral 11 is a gap indicating that the developing sleeve 8 and the magnet roller 5 are in a non-contact state.

The developer 4 obtains a triboelectric charge capable of developing the electrostatic latent image on the photosensitive drum 1 by friction between the developers and the resin coating layer 7 on the developing sleeve 8. In the example of FIG. 1, in order to regulate the layer thickness of the developer 4 conveyed to the developing area D, a material having rubber elasticity such as urethane rubber or silicone rubber as a developer layer thickness regulating member,
Alternatively, the developer layer thickness regulating member 2 made of an elastic plate made of a material having metal elasticity such as phosphor bronze or stainless steel is used, and the developer is elastically pressed against the developing sleeve 8 in the counter direction via the developer to develop. Forming a thin layer of agent. In this way, the thin layer of the developer 4 formed on the developing sleeve 8 is preferably thinner than the minimum gap between the developing sleeve 8 and the photosensitive drum 1 in the developing area D. .

The contact pressure of the developer layer thickness regulating member 2 against the developing sleeve 8 is a linear pressure of 5 to 50 g / cm.
It is preferable in that the regulation of the developer can be stabilized and the thickness of the developer layer can be made suitable. When the contact pressure of the developer layer thickness regulating member is less than the linear pressure of 5 g / cm, the regulation of the developer becomes weak, causing fog and toner leakage, and the linear pressure of 50
When it exceeds g / cm, the damage to the toner becomes large, which easily causes deterioration of the toner and fusion of the toner to the sleeve and the blade.

In order to fly the one-component developer 4 carried on the developing sleeve 8, an alternating bias voltage is applied to the developing sleeve 8 by a power source 9 as a bias means. When a DC voltage is used as the developing bias, a voltage having a value between the potential of the image portion (area where the developer 4 is adhered and visualized) of the electrostatic latent image and the potential of the background portion is applied to the developing sleeve 8. Is preferably applied to In order to increase the density of the developed image or to improve the gradation, an alternating bias voltage may be applied to the developing sleeve 8 to form an oscillating electric field in the developing area D, the direction of which is alternately inverted. . In this case, it is preferable to apply to the developing sleeve 8 an alternating bias voltage in which a DC voltage component having an intermediate value between the developed image portion potential and the background portion potential is superimposed.

In the case of so-called normal development, in which toner is visualized by adhering toner to the high potential part of the electrostatic latent image having the high potential part and the low potential part, the polarity is opposite to that of the electrostatic latent image. Use toner. In the case of so-called reversal development, in which toner is attached to the low potential part of an electrostatic latent image having a high potential part and a low potential part to make it visible, a toner charged to the same polarity as the polarity of the electrostatic latent image is used. To do. High potential and low potential are expressions using absolute values. In any of these cases, the developer 4 is charged by at least friction with the developing sleeve 8.

The drawings are merely schematic illustrations of the developing device of the present invention, and it goes without saying that there are various forms in the shape of the developer container (hopper 3), the presence or absence of the stirring blades 10, and the arrangement of the magnetic poles. .

FIG. 2 is a schematic view of a developing device of another embodiment according to the present invention. In FIG. 2, the developer layer thickness regulating member is elastically pressed against the developing sleeve 8 in the forward direction via the developer.

The present invention comprises these developing means, image carrier,
The charging means may be integrated and used as a process cartridge. An example of an image forming apparatus using the developing device having the developer carrier of the present invention illustrated in FIG. 1 will be described with reference to FIG. First, the surface of the photosensitive drum 1 as an image carrier is negatively charged by the contact (roller) charging means 18 as a primary charging means, and an electrostatic latent image is formed on the photosensitive drum 1 by image scanning by exposure 12 of laser light. Is formed. Next, the developing sleeve 8 having the developer layer thickness regulating member 2 as a developer carrying member
By the developing device equipped with, the electrostatic latent image,
Reversal development is performed by the negatively-charged one-component developer 4 having toner in the hopper 3 as a developing container.

As shown in FIG. 3, in the developing area D, the photosensitive drum 1 is grounded to the developing sleeve, and the developing sleeve 8 is applied with an alternating bias, a pulse bias and / or a DC bias by the power source 9. Next, when the transfer material P is conveyed and reaches the transfer portion, the contact (roller) transfer means 13 as a transfer means charges the transfer material P from the back surface (the surface opposite to the photosensitive drum side) of the transfer material P by the voltage application means 20. As a result, the developed image formed on the surface of the photosensitive drum 1 is transferred onto the transfer material P by the contact transfer means 13. Next, the transfer material P separated from the photosensitive drum 1 is conveyed to a heating and pressure roller fixing device 15 as a fixing means, and the fixing image is fixed by the fixing device.

In the above series of steps, the photosensitive drum (that is, the image carrier) 1 has a photosensitive layer and a conductive substrate, and moves in the direction of arrow B. The developing sleeve 8 is in the same direction as the surface of the photosensitive drum 1 in the developing area D (arrow A).
Rotate to move in the direction). The one-component developer 4 in the hopper 3 is carried on the developing sleeve 8, and due to friction with the surface of the developing sleeve 8 and / or friction between toners, for example, a negative triboelectric charge is given. Further, the developer layer thickness regulating member 12 regulates the thickness of the developer layer thinly (30 to 300 μm) and uniformly so that the developer is thinner than the gap between the photosensitive drum 1 and the developing sleeve 8 in the developing region D. Allow the layers to form.

The developing sleeve 8 is 100 with respect to the image bearing member.
It is preferable that they are installed facing each other with a separation distance of ˜1000 μm. If the separation distance of the developing sleeve 8 from the image carrier is smaller than 100 μm, the change in the developing characteristics of the toner due to the deviation of the separation distance becomes large, which makes it difficult to mass-produce an image forming apparatus satisfying a stable image property. Become. When the separation distance of the developing sleeve 8 from the image carrier is larger than 1000 μm, the collectability of the transfer residual toner to the developing device is deteriorated, and fogging due to defective collection is likely to occur. Further, since the ability of the toner to follow the electrostatic latent image on the image carrier is lowered, the resolution is lowered, and the image density is lowered. Preferably 120-500 μm
Is good.

Further, it is preferable to adjust the rotational speed of the developing sleeve 8 so that the surface speed of the developing sleeve 8 becomes substantially equal to or close to the surface speed of the photosensitive drum 1. . In the developing area D, an alternating bias or a pulse bias may be applied to the developing sleeve 8 as a developing bias voltage by the power supply 9. Between the developing sleeve 8 and the latent image carrier, at least a peak-to-peak electric field strength of 3 × 10 ⁶ to 10 × 1 is provided.
It is preferable to apply an alternating electric field of 0. ⁶ V / m and a frequency of 100 to 5000 Hz as the developing bias.

When transferring the developer in the developing area D,
The developer is transferred to the electrostatic latent image side by the electrostatic force on the surface of the photosensitive drum 1 and the action of the developing bias voltage such as the alternating bias or the pulse bias. Here, the behaviors of the toner particles and the conductive fine powder during the image forming process when the conductive fine powder is externally added to the toner particles in the simultaneous development image forming method will be described.

A suitable amount of the conductive fine powder contained in the toner moves to the image carrier side together with the toner particles during the development of the electrostatic latent image on the image carrier side in the developing step.

The toner image on the image carrier is transferred to the transfer material side in the transfer process. A part of the conductive fine powder on the image carrier also adheres to the transfer material side, but the rest remains adhered and held on the image carrier. When transfer is performed by applying a transfer bias having a polarity opposite to that of the toner, the toner is attracted to the transfer material side and actively transfers, but the conductive fine powder on the image carrier is conductive. The transfer material is not positively transferred to the transfer material side, and some of the material adheres to the transfer material side, but the rest remains adhered and held on the image carrier.

In the image forming method using no cleaner, the transfer residual toner remaining on the surface of the image bearing member after transfer and the above-mentioned residual conductive fine powder are transferred to the charging portion which is the contact portion between the image bearing member and the contact charging member. It is carried as it is by the movement of the surface of the image carrier and adheres to and mixes with the contact charging member.

Therefore, the contact charging of the image carrier is carried out with the conductive fine powder interposed in the contact portion between the image carrier and the contact charging member.

Due to the presence of the conductive fine powder, it is possible to maintain the close contact property and contact resistance of the contact charging member to the image bearing member regardless of the contamination due to the adhesion and mixing of the transfer residual toner on the contact charging member. Therefore, it is possible to favorably charge the image carrier by the contact charging member.

The transfer residual toner adhering to and mixed with the contact charging member is uniformly charged to the same polarity as the charging bias by the charging bias applied from the charging member to the image carrier, and the image is gradually transferred from the contact charging member. Exhaled on the carrier,
As the surface of the image bearing member moves, it reaches the developing section, where it is cleaned (collected) at the same time as the developing process.

Further, by repeating the image formation, the conductive fine powder contained in the toner is transferred to the surface of the image carrier at the developing section, and is moved to the charging section via the transfer section by the movement of the image carrying surface. Since the conductive fine powder is continuously supplied to the charging unit one after another, even if the conductive fine powder is reduced or deteriorates due to falling off or the like in the charging unit, it is possible to prevent the deterioration of the charging property. Good chargeability is stably maintained.

In the charging step in the image forming method of the present invention, a roller type (charging roller), a fur brush type, a magnetic brush type, a blade type conductive charging member (contact type) is attached to the image bearing member (charged member). A contact charging device is used in which a charging member and a contact charger are contacted with each other, and a predetermined charging bias is applied to the contact charging member to charge the surface of the body to be charged to a predetermined polarity and potential. Although it is possible to obtain good chargeability by applying a DC bias alone to the contact charging member, a DC voltage may be superposed with an alternating voltage (AC voltage).

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.

In the present invention, the charging member preferably has elasticity in providing a contact portion for interposing the conductive fine powder between the charging member and the image carrier, and a voltage is applied to the charging member. Therefore, it is preferable that the image carrier is electrically conductive so as to be charged. Therefore, the charging member has an elastic conductive roller, a magnetic brush part in which magnetic particles are magnetically restrained, and a magnetic brush contact charging member in which the magnetic brush part is brought into contact with an object to be charged or a charging brush composed of conductive fibers. And is preferably good.

If the hardness of the elastic conductive roller is too low, the shape of the elastic conductive roller is not stable, so that the contact property with the member to be charged is deteriorated. Further, the conductive fine powder is added to the contact portion between the charging member and the image carrier. It is difficult to obtain a stable charging property by scraping or damaging the surface layer of the elastic conductive roller by interposing. Further, if the hardness is too high, not only the charging contact portion cannot be secured between the charged body and the micro contact property to the surface of the charged body is deteriorated, but the Asker C hardness is preferably 25 to 50 degrees. It is a range.

It is important that the elastic conductive roller has elasticity to obtain a sufficient contact state with the member to be charged and at the same time functions as an electrode having a resistance low enough to charge the moving member to be charged. On the other hand, it is necessary to prevent voltage leakage when there is a defective portion such as a pinhole on the charged body. When an electrophotographic photosensitive member is used as the member to be charged, 10 ³ to 10 ⁸ Ω is required to obtain sufficient chargeability and leak resistance.
Resistance is more preferable, and more preferably 10 ⁴ to 10 ⁷
It is good that the resistance is Ω.

The roller resistance is 1 kg in total pressure on the core metal of the roller.
It is possible to measure by applying 100 V between the core metal and the aluminum drum in a state where the roller is pressure-bonded to the cylindrical aluminum drum having a diameter of 30 mm so as to apply the load of.

For example, the elastic conductive roller is formed 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 a resin (for example, urethane), a conductive substance (for example, carbon black), a sulfiding agent, a foaming agent, etc., and is formed in a roller shape on the core metal. After that, the elastic conductive roller can be prepared by cutting and polishing the surface to adjust the shape, if necessary. It is preferable that the surface of the roller has minute cells or irregularities in order to interpose conductive fine powder.

The material of the elastic conductive roller is not limited to the elastic foam, and the material of the elastic body is ethylene-propylene-diene polyethylene (EPDM),
Urethane, butadiene acrylonitrile rubber (NB
R), silicone rubber, isoprene rubber, and the like, a rubber material in which a conductive material such as carbon black or a metal oxide is dispersed for resistance adjustment, or a foamed material thereof. 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 elastic conductive roller is arranged so as to be pressed against a member to be charged as an image bearing member with a predetermined pressing force against elasticity, and a charging member which is a contact portion between the elastic conductive roller and the image bearing member is disposed. Form a contact part. The width of the charging contact portion is not particularly limited, but it is 1 mm or more, and more preferably 2 mm in order to obtain a stable and dense adhesion between the elastic conductive roller and the image carrier.
The above is good.

Further, as the charging brush as the contact charging member, one in which resistance is adjusted by dispersing a conductive material in commonly used fibers is used. As the fiber, a generally known fiber can be used, for example, nylon,
Examples thereof include acrylic, rayon, polycarbonate, polyester and the like. As the conductive material, generally known conductive materials can be used, and examples thereof include conductive metals such as nickel, iron, aluminum, gold and silver, or iron oxide, zinc oxide, tin oxide, antimony oxide, titanium oxide and the like. Examples of the conductive metal oxides are also conductive powders such as carbon black. If necessary, these conductive materials may be surface-treated for the purpose of making them hydrophobic and adjusting their resistance. At the time of use, it is selected and used in consideration of dispersibility with fibers and productivity.

When a charging brush is used as the contact charging member, there are a fixed type and a rotatable roll type. As the roll-shaped charging brush, for example, a tape in which conductive fibers are piled can be spirally wound around a metal cored bar to form a roll brush. The conductive fiber is
Fiber thickness is 1-20 denier (fiber diameter 10-500μ
m), the fiber length of the brush is 1 to 15 mm, and the brush density is 10,000 to 300,000 per square inch (about 1.5 × 10 ^{7 to} 4.5 × 10 ⁸ per square meter). Is preferably used.

As the charging brush, it is preferable to use a material having a brush density as high as possible, and it is also preferable to form one fiber from several to several hundred fine fibers. For example, 30
It is also possible to bundle 50 fine fibers of 300 denier, such as 0 denier / 50 filaments, and to implant them as one fiber. However, in the present invention,
The charging point of the direct injection charging is mainly determined by the contact density between the charging member and the image carrier and the density of the conductive fine powder in the vicinity thereof. The range of choices is wide.

The resistance value of the charging brush is 10 ³ in order to obtain sufficient charging property and leak resistance as in the case of the elastic conductive roller.
The resistance is preferably 10 ⁸ Ω, more preferably 1
The resistance is preferably 0 ⁴ to 10 ⁷ Ω.

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-
B, REC-C, REC-M1 and REC-M10 are particularly preferable.

Further, the flexibility of the contact charging member increases the chances that the conductive fine powder comes into contact with the image bearing member at the contact portion between the contact charging member and the image bearing member, resulting in high contactability. Is preferable, and it is preferable in that the direct injection charging property is improved. That is, the contact charging member comes into close contact with the image carrier through the conductive fine powder, and the conductive fine powder present at the contact portion between the contact charging member and the image carrier slides on the surface of the image carrier without a gap. By rubbing, the charging of the image bearing member by the contact charging member is dominated by stable and safe direct injection charging that does not use the discharge phenomenon due to the presence of conductive fine powder, which is not obtained by conventional roller charging or the like. The charging efficiency can be obtained, and a potential almost equal to the voltage applied to the contact charging member can be applied to the image carrier.

Further, it is preferable to provide a relative speed difference between the moving speed of the surface of the charging member forming the contact portion and the moving speed of the surface of the image carrier. At the contact portion between the contact charging member and the image bearing member, the opportunity for the conductive fine powder to come into contact with the image bearing member is remarkably increased, and higher contactability can be obtained. good.

By interposing the conductive fine powder at the contact portion between the contact charging member and the image carrier, the lubricating effect (friction reducing effect) of the conductive fine powder is provided between the contact charging member and the image carrier. It is possible to provide a speed difference without a significant increase in torque and significant abrasion of the surfaces of the contact charging member and the image carrier.

As a structure for providing the speed difference, the contact charging member may be rotationally driven to provide the speed difference between the image carrier and the contact charging member.

In order to temporarily collect and level the transfer residual toner on the image bearing member carried to the charging section on the contact charging member, it is preferable to move the contact charging member and the image bearing member in opposite directions. . It is desirable that the contact charging member be rotated in a direction opposite to the moving direction of the surface of the image carrier. That is, it is possible to predominantly perform direct injection charging by temporarily separating the transfer residual toner on the image bearing member by reverse rotation and performing charging.

It is also possible to move the charging member in the same direction as the moving direction of the surface of the image carrier to give a speed difference, but the charging property of the direct injection charging is the peripheral speed of the image carrier and the peripheral speed of the charging member. Therefore, in order to obtain the same peripheral speed ratio as in the reverse direction, the rotation speed of the charging member in the forward direction is larger than that in the reverse direction. It is advantageous in terms. The peripheral speed ratio described here is the peripheral speed ratio (%) = (peripheral speed of charging member−peripheral speed of latent image carrier) / latent image carrier peripheral speed × 100 (the peripheral speed of the charging member is at the contact portion). Positive value when the surface of the charging member moves in the same direction as the surface of the latent image carrier).

As an index showing the relative speed difference, there is a relative moving speed ratio represented by the following equation. Relative moving speed ratio (%) = | (Vc−Vp) / Vp | × 1
00 (where Vc is the moving speed of the charging member surface, Vp is the moving speed of the image carrier surface, and Vc is V when the charging member surface moves in the same direction as the image carrier surface at the contact portion.
ptp The value has the same sign. ) The relative moving speed ratio is preferably 10 to 500%, more preferably 20 to 400%. If the relative moving speed ratio is too small than the above range, the contact probability between the contact charging member and the image carrier cannot be sufficiently increased, and the chargeability of the image carrier is maintained by direct injection charging. It can be difficult to do. Further, the amount of the conductive fine powder present in the contact portion between the image carrier and the contact charging member is limited by the friction between the contact charging member and the image carrier to suppress the charging inhibition of the image carrier. In some cases, the effect and the effect of leveling the pattern of the transfer residual toner particles and improving the recoverability of the developer in the simultaneous cleaning with development may not be sufficiently obtained. If the relative moving speed ratio is higher than the above range, the moving speed of the charging member is increased, so that the developer component carried in the contact portion between the image carrier and the contact charging member is scattered. As a result, the inside of the apparatus is liable to be contaminated, the image carrier and the contact charging member are apt to be worn or scratched, and the life thereof is shortened. Further, 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 image carrier is a fixed point, so that the contact portion of the charging member with the image carrier is fixed. Is likely to be worn or deteriorated, and the effect of suppressing the 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 simultaneous cleaning with development are unfavorable.

If the amount of the conductive fine powder present in the contact portion between the image carrier and the contact charging member is too small, the lubricating effect of the conductive fine powder cannot be sufficiently obtained, and the image carrier and the contact charging member are charged. Due to the large friction with the member, it is difficult to rotationally drive the contact charging member on the image carrier with a speed difference. That is, the driving torque becomes excessively large, and if it is forcibly rotated, the surfaces of the contact charging member and the image carrier tend to be scraped. Further, the effect of increasing contact opportunities due to the conductive fine powder may not be obtained, and it is difficult to obtain sufficient charging performance. On the other hand, if the intervening amount is too large, the amount of the conductive fine powder falling from the contact charging member remarkably increases, and the image formation tends to be adversely affected.

According to the experiment, the interposition amount of the conductive fine powder is 10
³ pieces / mm ² or more is preferable, and more preferably 10 ⁴ pieces / mm ²
mm ² or more is good. If it is lower than 10 ³ pieces / mm ² , sufficient lubrication effect and effect of increasing contact opportunity cannot be obtained, and the charging performance is apt to deteriorate. When it is lower than 10 ⁴ particles / mm ² , the charging performance is apt to deteriorate when the transfer residual toner is large.

The coating density range of the conductive fine powder is also determined by the density of the conductive fine powder applied on the image carrier to obtain the effect of uniform charging.

It is needless to say that at the time of charging, contact charging more uniform than at least this recording resolution is required. However, regarding the visual characteristics of the human eye, the spatial frequency is 10
When the number of cycles / mm or more, the number of identification gradations on the image approaches 1 as much as possible, that is, the density unevenness cannot be identified. If this property is positively utilized, when conductive fine powder is attached to the image carrier, the conductive fine powder is present at a density of at least 10 cycles / mm on the image carrier and direct injection charging is performed. It would be good. Even if a microscopic charging failure occurs where there is no conductive fine powder, density unevenness on the image caused by the charging failure occurs in the spatial frequency region that exceeds human visual characteristics. Then there is no problem.

Whether the charging failure as density unevenness is recognized on the image when the coating density of the conductive fine powder is changed is determined by applying even a small amount of the conductive fine powder (for example, 10 pieces). / Mm ² ), an effect of suppressing the occurrence of charging unevenness is recognized, but it is still insufficient in terms of whether density unevenness on an image is acceptable to humans.

However, if the coating amount is 10 ² pieces / mm ² or more, a desirable result can be rapidly obtained in the objective evaluation of the image. Furthermore, by increasing the coating amount by 10 ³ pieces / mm ² or more, there is no problem on the image due to poor charging.

The charging by the direct injection charging system is fundamentally different from the discharge charging system, and the charging is carried out by surely contacting the photoconductor with the charging member. Even if it is applied excessively on the image bearing member, there always exists a portion 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.

However, when the direct injection charging method is applied as the uniform charging of the image carrier in the cleaning simultaneous development image formation, the transfer residual toner adheres to or mixes with the charging member, resulting in deterioration of the charging characteristics. In order to prevent the transfer residual toner from adhering to and mixing with the charging member, or overcome the adverse effects on the charging characteristics due to the adhesion or mixing of the transfer residual toner to the charging member, and to perform good direct injection charging, an image carrier It is preferable that the amount of the conductive fine powder present in the contact portion between the contact charging member and the contact charging member is 10 ⁴ particles / mm ² or more.

The upper limit of the coating density cannot be generally determined because it depends on the particle size of the conductive fine powder, but if it is forcedly described, one layer of the conductive fine powder is uniformly formed on the image bearing member. The amount applied is the upper limit. If it is applied more than that, the effect is not improved, and conversely, there is a problem that the exposure light source is blocked or scattered.

The amount of the conductive fine powder is 5 × 10 ⁵ pieces / mm ²
When it exceeds the above value, the amount of the conductive fine powder falling onto the image carrier remarkably increases, and the exposure amount to the image carrier is insufficient regardless of the light transmittance of the conductive fine powder itself. If it is 5 × 10 ⁵ particles / mm ² or less, the amount of particles that fall off can be suppressed to a low level, and the exposure inhibition can be improved. The amount of particles dropped off on the image bearing member in the range of the intervening amount was measured and found to be 10 ² to 10 ⁵ particles / mm ² , so that the amount of particles present without any adverse effect on image formation was 10 ^{4 to} 5 ×. 1
An intervening amount of 0 ⁵ pieces / mm ² is preferable.

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 image carrier in the electrostatic latent image forming step will be described. It is desirable to measure the amount of conductive fine powder present directly at the contact surface between the contact charging member and the image carrier, but there should be a speed difference between the surface of the contact charging member forming the contact part and the surface of the image carrier. In the present invention, most of the particles that were present on the image bearing member before coming into contact with the contact charging member are stripped off by the contacting charging member while moving in the opposite direction. The amount of particles on the surface of the charging member is used as an intervening amount.

Specifically, it is as follows. The rotation of the image carrier and the elastic conductive roller is stopped without applying the charging bias, and the surfaces of the image carrier and the elastic conductive roller are covered with a video microscope (OVM100 made by OLYMPUS.
0N) and digital still recorder (S manufactured by DELTIS
R-3100). Regarding the elastic conductive roller, the elastic conductive roller is brought into contact with the slide glass under the same conditions as the contact of the elastic conductive roller with the image carrier, and the contact surface from the back surface of the slide glass with a video microscope is 10 places with a 1000 × objective lens. The above is taken. In order to separate the individual fine powders from the obtained digital image, a binarization process is performed with a certain threshold value, and the number of regions where the fine powders are present is measured using a desired image processing software. Further, the amount of existence on the image bearing member is also measured by photographing the image bearing member with the same video microscope and performing the same processing.

In addition, in the image forming method of the present invention,
The outermost surface layer of the image bearing member preferably has a volume resistance of 1 × 10 ⁹ Ωcm or more and 1 × 10 ¹⁴ Ωcm or less, and when the volume resistance is in the range, a better charging property can be given. 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 Ωcm or less. On the other hand, in order to hold the electrostatic latent image as the image carrier for a certain period of time, the volume resistance value of the outermost surface layer is 1
It is preferable that it is × 10 ⁹ Ωcm or more.

Further, the image bearing member is an electrophotographic photosensitive member,
The volume resistance of the outermost surface layer of the electrophotographic photosensitive member is 1 × 10 ⁹ Ω
It is more preferable that it is not less than 1 cm and not more than 1 × 10 ¹⁴ Ωcm since sufficient chargeability can be provided even in a device having a high process speed.

The image carrier is amorphous selenium, C
A photosensitive drum or photosensitive belt having a photoconductive insulating material layer such as dS, 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. To be

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

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

It is also preferable to provide a charge injection layer on the surface of the electrophotographic photosensitive member for the purpose of more efficiently or promoting charge injection of the image bearing member. The charge injection layer preferably has a form in which conductive fine particles are dispersed in a binder resin.

The charge injection layer may be provided by, 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, and (ii) function-separated type organic photoreceptor. The surface layer composed of the charge transfer agent and the binder resin as the charge transfer layer of the photoconductor also functions as the charge injection layer (for example, the charge transfer agent and the conductive fine particles are contained in the binder resin as the charge transfer layer). Or the charge-transporting agent itself or the state of its existence so that the charge-transporting layer has a function as a charge-injecting layer), (iii) the charge-injecting layer is provided as the outermost layer on the function-separated type organic photoconductor However, it is important that the volume resistance of the outermost surface layer is within a preferable range.

The charge injection layer is composed of, for example, a layer of an inorganic material such as a metal vapor deposition film, or a conductive fine particle dispersed resin layer in which conductive fine particles are dispersed in a binder resin. The conductive fine particle dispersed resin layer is formed by applying a suitable coating method such as a dipping coating method, 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 resin with a resin having a high light-transmitting ion conductivity, or a resin having a medium resistance and a photoconductivity alone.

Among these, it is preferable that the outermost surface layer of the image bearing member 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 oxide conductive fine particles are dispersed, the particle size of the oxide conductive fine particles is smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles. Is preferred. Therefore, the particle diameter of the dispersed oxide conductive fine particles is preferably 0.5 μm or less. The content of the oxide conductive fine particles is preferably 2 to 90% by mass, more preferably 5 to 70% by mass, based on the total weight of the outermost layer. When the content of the oxide conductive fine particles is less than the above range, it becomes difficult to obtain a desired volume resistance value. Further, if the content is more than the above range, the film strength is lowered, the charge injection layer is easily scraped off, the life of the photoreceptor tends to be shortened, and the resistance is too low. As a result, an image defect is likely to occur due to the latent image potential flowing.

The thickness of the charge injection layer is 0.1 to 10 μm.
m is preferable, and is 5 in order to obtain the sharpness of the outline of the latent image.
It is more preferably at most 1 μm from the viewpoint of durability of the charge injection layer. The binder resin of the charge injection layer may be the same as the binder resin used for the lower layer of the charge injection layer (for example, the charge transport layer). In this case, however, the binder resin of the lower layer is applied when the charge injection layer is applied. Since the coated surface may be disturbed, it is necessary to particularly select the forming method.

The method for measuring the volume resistance value of the outermost surface layer of the image bearing member in the present invention is as follows. And a volume resistance measuring device (manufactured by Hewlett-Packard Company 41
40B pA MATER), temperature 23 ° C, humidity 6
The measurement is performed by applying a voltage of 100 V in a 5% environment.

Further, in the present invention, it is preferable to impart releasability to the surface of the image bearing member, and the contact angle of the surface of the image bearing member with water is preferably 85 degrees or more. More preferably, the contact angle of water on the surface of the image bearing member is 90 degrees or more.

The fact that the surface of the image bearing member has a high contact angle means that the surface of the image bearing member has a high releasability with respect to the toner particles. Due to this effect, the recovery efficiency of the developer is improved in the cleaning process simultaneous with development. Also,
Since the amount of transfer residual toner can be significantly reduced,
It is also possible to suppress a decrease in chargeability of the image carrier due to the transfer residual toner.

As means for imparting releasability to the surface of the image bearing member, for example, resin having a low surface energy is used for the resin constituting the film, or an additive for imparting water repellency or lipophilicity is added, Examples of the method include dispersing a material having high releasability (fine particles of lubricant) in the form of powder. The resin having low surface energy can be obtained by introducing a fluorine-containing group or a silicone-containing group into the structure of the resin. Examples of the additive include a surfactant. As the lubricant fine particles, it is possible to use a fluorine resin containing a fluorine atom such as polytetrafluoroethylene, polyvinylidene fluoride and carbon fluoride, a silicone resin or a polyolefin resin.

By these means, the contact angle of water on the surface of the image bearing member can be set to 85 degrees or more. Among these, the outermost surface layer of the image bearing member is preferably a layer in which lubricant fine 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-based resin is used as the lubricant fine particles in the releasable powder, it is suitable to be dispersed in the outermost surface layer.

In order to contain these lubricant fine particles in the outermost surface layer, a layer in which the powder is dispersed in a binder resin is provided on the outermost surface of the photoreceptor, or the resin is mainly used. In the case of an organic photoreceptor, the powder may be dispersed in the outermost surface layer without providing a new surface layer.

The amount of the lubricant fine particles added to the surface layer of the image bearing member is preferably 1 to 60% by mass, and more preferably 2 to 50% by mass, based on the total weight of the surface layer. If the amount added is less than the above range, the transfer residual toner is not sufficiently reduced, and the recovery efficiency of the developer in the simultaneous developing cleaning device is insufficient. 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, more preferably 0.5 μm or less, and if the particle size is larger than the above range, the line is broken due to scattering of incident light. Tend to get worse,
It is easy to damage the resolution.

In the present invention, the contact angle is measured using pure water, and the apparatus is a contact angle meter CA-DS type manufactured by Kyowa Interface Science Co., Ltd.

One of the preferable modes of the photosensitive member as the image bearing member 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 coating property is improved, the substrate is protected, and the defects are covered on the substrate.
A conductive layer or 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 conductive layer is a resin layer containing metal or metal oxide particles, and the film thickness is preferably 10 to 30 μm.

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, It is formed of a material such as gelatin, polyurethane or aluminum oxide. The thickness of the undercoat layer is usually 0.1 to 10 μm, preferably 0.1 to 3 μm.
m is good.

The charge generation layer may be an azo pigment, phthalocyanine pigment, indigo pigment, perylene pigment, polycyclic quinone pigment, squarylium dye, pyrylium salt, thiopyrylium salt, triphenylmethane dye, selenium or amorphous. A charge generating substance such as an inorganic substance such as silicon is dispersed in a suitable binder resin 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. As the binder resin, for example, polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacrylic resin, phenol resin,
Examples thereof include silicone resin, epoxy resin, vinyl acetate resin and the like. The amount of binder resin contained in the charge generation layer is 8
It is 0% 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
˜2 μm is preferred.

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, etc. Is mentioned.

As the binder resin in which these charge transport substances are dispersed, polycarbonate resin, polyester resin,
Resins such as polymethacrylic acid ester, polystyrene resin, acrylic resin and polyamide resin; and 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 described above. As the resin of the surface layer,
Polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or a curing agent of these resins may be used alone or in combination of two or more kinds. Examples of the conductive fine particles include metal or metal oxide. Preferred are oxide conductive fine particles such as 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 can be used alone 2
You may use it in mixture of 2 or more types.

In the present invention, the electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the image carrier is preferably an image exposing means. The image exposure means for forming the electrostatic latent image is not limited to the laser scanning exposure means for forming a digital electrostatic latent image, but a normal analog image exposure or other light emission such as an LED. An element may be used, or a combination of a light emitting element such as a fluorescent lamp and a liquid crystal shutter may be used as long as it can form an electrostatic latent image corresponding to image information.

[0292]

EXAMPLES The present invention will be specifically described below with reference to production examples and examples, but these do not limit the present invention in any way. In the following formulation, all parts are parts by mass.

<1> Manufacture of Photoreceptor A photoreceptor using an organic photoconductive substance for negative charging (hereinafter referred to as “O”)
"PC photoconductor") was manufactured. A cylinder of aluminum having a diameter of 24 mm was used as the base of the photoreceptor. The following layers were applied onto the cylinder by dip coating to successively stack the layers to prepare a photoreceptor.

The first layer is a conductive layer and has a thickness of about 20 provided to smooth out defects and the like in the aluminum substrate and to prevent moire due to reflection of laser exposure.
A conductive particle-dispersed resin layer having a thickness of μm (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 (undercoat layer), which plays a role of preventing the positive charges injected from the aluminum substrate from canceling out the negative charges charged on the surface of the photoconductor, and is a methoxymethyl group. 10 ⁶ Ωc due to nylon
It is a medium resistance layer having a thickness of about 1 μm whose resistance is adjusted to about m.

The third layer is a charge generating layer, which is a layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a propylal resin, and positive and negative charge pairs are generated by laser exposure.

The fourth layer is a charge transport layer and has a thickness of about 25 μm in which a hydrazone compound is dispersed in a polycarbonate resin.
Layer, which 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 a charge injection layer, which comprises a photocurable acrylic resin, conductive tin oxide fine particles and a particle size of about 0.25.
It is a dispersion of tetrafluoroethylene resin particles of μm. 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 dispersed. The coating solution prepared in this manner was applied by spray coating to a thickness of about 2.5 μm to form a charge injection layer.

The volume resistance of the outermost surface layer of the thus obtained photoconductor was 5 × 10 ¹² Ωcm, and the contact angle of the photoconductor surface with water was 103 °.

<2> Manufacture of Magnetic Powder (Manufacturing Example 1 of Magnetic Powder) In an aqueous solution of ferrous sulfate, 1. An aqueous solution containing ferrous hydroxide was prepared by mixing 0 to 1.1 equivalents of caustic soda solution. P of aqueous solution
While maintaining H around 9, blow air into
An oxidation reaction was carried out at 0 ° C. to prepare a slurry liquid for generating seed crystals. Next, 0.9 to 1.2 relative to the initial alkali amount (sodium component of caustic soda) in this slurry liquid.
After adding the ferrous sulfate aqueous solution to an equivalent amount, maintaining the slurry liquid at pH 8 and advancing the oxidation reaction while blowing air, washing the magnetic iron oxide particles generated after the oxidation reaction,
It was filtered and once taken out. At this time, a small amount of water sample was taken and the water content was measured. Then, after re-dispersed in a different aqueous medium without drying the water-containing sample was adjusted to pH of the redispersion to about 6, sufficiently stirring the silane coupling agent (n-C ₁₀ H ₂₁ Si (OCH ₃ ) ₃ ) was added to magnetic iron oxide in an amount of 1.0 part by mass (the amount of magnetic iron oxide was calculated by subtracting the water content from the water-containing sample),
Coupling treatment was performed. The produced hydrophobic iron oxide particles were washed, filtered and dried by a conventional method, and then the particles which were slightly aggregated were crushed to obtain a magnetic powder 1. (Manufacturing Example 2 of Magnetic Powder) The same oxidization reaction as in Manufacturing Example 1 of magnetic powder, the magnetic iron oxide particles produced after the oxidization reaction are washed, filtered, dried without surface treatment, and aggregated. The resulting particles were crushed to obtain magnetic powder 2. <3> Preparation of conductive fine powder (Example 1 of conductive fine powder) A conductive zinc oxide having a volume average particle size of 2.7 μm (resistance 1.5 × 10 ⁴ Ωcm) was used as the conductive fine powder 1. When observed with a scanning electron microscope, this conductive fine powder was composed of zinc oxide primary particles of 0.1 to 0.3 μm and aggregates of 1 to 4 μm.

The exposure light wavelength 74 of the laser beam scanner used for image exposure in the image forming apparatus of Example 1 described later.
Using a light source having a wavelength of 740 nm in accordance with 0 nm, the transmittance in this wavelength range is 310T manufactured by X-Rite.
When measured using a transmission densitometer, the transmittance of this conductive fine powder was about 35%.

(Example 2 of conductive fine powder) From conductive fine powder 1, conductive zinc oxide (resistance 2.8 × 10 ⁴ Ωcm) having a volume average particle diameter of 0.7 μm was obtained by a classification operation. This was used as the conductive fine powder 2.

(Example 3 of conductive fine powder) Volume average particle diameter
8 μm conductive tin oxide (resistance 2.2 × 10 ⁵ Ωcm)
Was used as the conductive fine powder 3.

(Example 4 of conductive fine powder) Volume average particle diameter
1 μm conductive titanium oxide (resistance 3.4 × 10 ⁶ Ωc
m) was used as the conductive fine powder 4.

<4> Production of Developer (Production Example 1 of Developer) 0.1M in 709 g of ion-exchanged water
After adding 451 g of -Na ₃ PO ₄ aqueous solution and heating to 60 ° C, 67.7 g of 1.0 M-CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ . -Styrene 80 parts-n-butyl acrylate 20 parts-Unsaturated polyester resin 3 parts-Saturated polyester resin 3 parts-Negatively charged control agent (monoazo dye-based Fe compound) 1.5 parts-Magnetic powder 1 90 parts above The formulation was uniformly dispersed and mixed using an attritor (Mitsui Miike Kakoki Co., Ltd.).

This monomer composition was heated to 60 ° C., and 6 parts of an ester wax mainly containing behenyl behenate (maximum value of endothermic peak in DSC: 72 ° C.) was added, mixed and dissolved, and then polymerized. Initiator 2,2'-azobis (2,4-
Dimethylvaleronitrile) [t1 / 2 = 140 minutes, 60 ° C
Conditions] 5 g was dissolved.

The above polymerizable monomer system is added to the above aqueous medium.
Enter, 60 ℃, N₂TK homomixer under atmosphere
-(Special Kika Kogyo Co., Ltd.) 1 at 10,000 rpm
The mixture was stirred for 5 minutes and granulated. After that, stir with a paddle stirring blade
While reacting at 60 ° C. for 6 hours. After that, adjust the liquid temperature to 80 ° C.
The stirring was continued for another 4 hours. After the reaction is completed, the temperature is changed to 80 ℃.
Distill for 2 hours, then cool the suspension and add hydrochloric acid.
In addition Ca₃(PO_Four) ₂Dissolved, filtered, washed with water, dried
To obtain toner particles having a weight average particle diameter of 6.7 μm.

100 parts of this toner, 12 parts of the above-mentioned conductive fine powder, and silica having a primary particle size of 8 nm were treated with hexamethyldisilazane on the surface to obtain a BET value of 250 m ² after the treatment.
The developer 1 was prepared by mixing 1.1 parts of the hydrophobic silica fine powder of 0.1 g / g with a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.). Also, toner particles, developer particle size, circularity,
The B / A value and D / C were measured by the method described in the above embodiment. Table 1 shows the physical properties of Developer 1.

[0309]

[Table 1]

(Production Example 2 of Developer) The same procedure as in Production Example 1 of Developer except that 90 parts of the magnetic powder 2 was used in place of the magnetic powder 1, and the weight average particle diameter was 7.3 μm. Toner particles are obtained. Table 1 shows the physical properties of Developer 2.

(Production Example 3 of Developer) A weight average particle diameter of 6.7 μm was obtained in the same manner as in Production Example 1 of Developer except that the conductive fine powder 2 was used in place of the conductive fine powder 1.
Toner particles were obtained. Table 1 shows the physical properties of Developer 3.

(Manufacturing Example 4 of Developer) By the same procedure as in Manufacturing Example 1 of Developer except that the conductive fine powder 3 is used in place of the conductive fine powder 1, the weight average particle diameter is 6.7 μm.
Toner particles were obtained. Table 1 shows the physical properties of Developer 4.

(Manufacturing Example 5 of Developer) The same procedure as in Manufacturing Example 1 for Developer except that the conductive fine powder 4 is used in place of the conductive fine powder 1, the weight average particle diameter is 6.7 μm.
Toner particles were obtained. Table 1 shows the physical properties of Developer 5.

Developer Production Example 6 Developer 6 was prepared in the same manner as in Developer Production Example 1 except that conductive fine powder 1 was not added. Table 1 shows the physical properties of Developer 6.

[0315]

Example 1 <Manufacturing of developing sleeve> Manufacturing of the developing sleeve will be described.

The following materials were dispersed in φ2 mm zirconia particles using a sand mill for 3 hours, and then the zirconia particles were separated by sieving and the solid content was adjusted to 36% with methanol to obtain a coating material 1. -Carbon 15 parts-Graphite 85 parts-Ammonia-catalyzed phenol resin intermediate (solid content 50%) 300 parts-Quaternary ammonium salt compound represented by formula 5 30 parts-Number average particle size 5.2 μm Spherical carbon particles (A) 30 parts, methanol 130 parts Quaternary ammonium salt compound (1) triboelectric charge amount with iron powder, commercially available triboelectric charge measuring instrument (TB-manufactured by Toshiba Chemical
200 type) and the blow-off method,
It had a positive polarity. As spherical particles, spherical carbon particles A
Was used. The physical properties are shown in Table 2. Number average particle size 5.2μ
m, true density 1.51 g / cm ³ , volume resistance 7.5 × 10
^{It was -2} Ωcm and the ratio of major axis / minor axis was 1.15.

The paint 1 was sprayed to form an A having a diameter of 16 mm.
A resin coating layer of about 10 μm was formed on a cylindrical body, and then heated and cured at 150 ° C./30 minutes with a hot air drier to prepare a developer carrier (1). Table 3 shows the paint formulation and the physical properties of the developer carrier.

[0318]

[Table 2]

[0319]

[Table 3]

<Image forming apparatus> As an image forming apparatus, L
A modified version of BP-1760 was used. This modified machine is
It is a laser printer (recording device) of a simultaneous cleaning process (cleanerless system) using a transfer type electrophotographic process. It has a process cartridge that removes a cleaning unit that has a cleaning member such as a cleaning blade, uses a magnetic one-component developer as the developer, and the developer layer on the developer carrier does not contact the image carrier. The device is arranged so that

As a primary charging member, a rubber roller charger in which conductive carbon is dispersed and coated with nylon resin is brought into contact with the photoreceptor having the above-mentioned charge injection layer (contact pressure 60 g).
/ Cm), AC voltage 2.0 k to DC voltage -700 Vdc
A bias with Vpp superimposed is applied to uniformly charge the surface of the photoconductor. After the primary charging, an electrostatic latent image is formed by exposing the image portion with laser light.

At this time, the dark potential Vd = -700V and the light potential VL = -150V. The gap between the photosensitive drum and the developing sleeve is 290 μm, and the developing magnetic pole 85 mT (85
0 Gauss), thickness 1.0m as a developer layer thickness regulating member
m, free blade 1.0 mm silicone rubber blade 2
They were brought into contact with each other with a linear pressure of 9.4 N / m (30 g / cm).

Next, as a developing bias, a DC bias component Vdc = -500V and an AC bias component V to be superimposed.
pp = 1600V and f = 2000Hz were used. Also,
The peripheral speed of the developing sleeve is the peripheral speed of the photoconductor (94 mm / sec).
110% speed in the forward direction (103 mm / s
ec).

Transfer roller (made of ethylene-propylene rubber in which conductive carbon is dispersed, volume resistance value of conductive elastic layer 10 ⁸ Ωcm, surface rubber hardness 24 °, diameter 20 m)
m, a contact pressure of 59 N / m (60 g / cm) was set to a constant speed with respect to the peripheral speed of the photoconductor (94 mm / sec), and the transfer bias was set to 1.5 kV DC.

As a fixing method, a fixing device of the type which does not have the oil coating function of LBP-1760 and which is heated and pressure-fixed by a heater through a film is used. At this time, a pressure roller having a surface layer of a fluororesin was used, and the diameter of the roller was 30 mm. The fixing temperature is 180
C., the contact width was set to 7 mm.

<Image Evaluation> Using Developer 1 as a developer, room temperature and low humidity (N / L) and 30 at 24 ° C. and 10% RH were used.
An image drawing test was performed in a high temperature and high humidity (H / H) environment of 80 ° C. and 80% RH. As the transfer material, 75 g / m ² paper was used. As a result, it shows high transcription in the initial stage,
A good image without fog on the non-image was obtained without omission of characters or lines during transfer.

Next, durability was evaluated with an image pattern consisting of only horizontal lines with a printing area ratio of 5%. The obtained results are shown in Tables 4 and 5.

Durability test evaluation was performed on the following evaluation items. (1) Image density Image output is 15,000 sheets at 24 ° C, 10% RH normal temperature and low humidity (N / L) and 30 ° C, 80% RH high temperature and high humidity (H / H) environment. It went to (15k). The initial density was the density of the 20th sheet after drawing. The solid black image density was measured with a reflection density RD918 (manufactured by Macbeth Co.), and the average value of 5 points was taken as the image density.

(2) Toner charge amount (Q / M) and toner transport amount (M / S) The toner carried on the developing sleeve is sucked and collected by the metal cylindrical tube and the cylindrical filter, and at that time, the metal cylindrical tube. From the amount of charge Q accumulated in the condenser through the capacitor, the weight M of collected toner, and the area S from which the toner is sucked, the amount of charge Q / M (mC / kg) per unit weight and the toner weight M / S (mg / cm ² ) was calculated and used as the toner charge amount (Q / M) and the toner transport amount (M / S), respectively.

(3) Fog The measurement of fogging is done by REFLECTTMET manufactured by Tokyo Denshoku Co., Ltd.
It was measured using an ER MODEL TC-6DS.
A green filter was used as a filter, and fog was calculated from the following formula. Fog (reflectance) (%) = reflectance (%) on standard paper−reflectance (%) of non-image portion of sample If the fog is 2.0% or less, a good image is obtained.

(4) After the scraping of the photosensitive member and the completion of the toner fusion image formation, the scratches on the photosensitive drum surface and the occurrence of toner adhesion to the scratches and the black spots or white spots in the halftone image are visually evaluated. did. A: Very good (not generated) B: Good (slightly scratched, but no effect on the image) C: Normal (toner sticking or scratches, but little effect on the image) D : Poor (a lot of toner adheres along the scratches, causing vertical stripe image defects)

(5) Non-uniform charging: Image failure due to primary charging failure due to transfer residual toner,
That is, the charging unevenness was evaluated on the halftone image. The density difference (unevenness) appearing on the halftone image was visually evaluated according to the following criteria. ◯: No difference in shade is seen. ○ △: A slight difference in shade is seen. Δ: Practical is acceptable although there is a slight difference in shade. Poor: Practical use is not possible because of a marked difference in shade.

(6) Contamination resistance of the coating layer The surface of the developer bearing member after the durability test was observed by SEM, and the degree of toner contamination was evaluated according to the following criteria. ◯: Minor contamination is observed. ○ △: Some contamination is observed. Δ: Contamination is partially observed. X: Significant contamination is observed.

(7) Transfer rate The transfer efficiency is as follows. The transfer residual toner on the photoconductor after the transfer of the solid black image is taped off with Mylar tape and peeled off, and the value of the Macbeth density of the one stuck on the paper is C, after transfer and before fixing. When the Macbeth density of the Mylar tape stuck on the toner-laden paper was set to D and the Macbeth density of the Mylar tape stuck to the unused paper was set to E, it was approximately calculated by the following formula.

[0335]

[Equation 8]

If the transfer efficiency is 90% or more, there is no problem in the image.

[0337]

[Table 4]

[0338]

[Table 5]

[0339]

Example 2 Developer 2 is used as a developer, and Example 1 is used.
When the durability test was evaluated by the same image forming method as
Very good results have been obtained. The results are shown in Tables 4 and 5.

[0340]

Third Embodiment A developer 3 is used as a developer, and the first embodiment is used.
When the durability test was evaluated by the same image forming method as
Good results have been obtained. The results are shown in Tables 4 and 5.

Comparative Example 1 Developer 1 was used as the developer, and Example 1 was used.
Durability test evaluation was performed by the same image forming method. The results are shown in Tables 4 and 5. An image with large density unevenness on the page was obtained.

[0341]

Comparative Example 2 A developing sleeve (15) of a comparative example was obtained by sandblasting an Al cylindrical tube having a diameter of 16 mm and roughening the surface to a surface roughness Ra of 1.18 μm. With respect to this developing sleeve, durability test evaluation was performed in the same manner as in Example 1 using Developer 1. The results are shown in Tables 4 and 5. The solid black image density was reduced in each environment. Table 3 shows the paint formulation and physical properties of the developer carrying member (15).

Comparative Example 3 A developing sleeve (surface roughness Ra of 1.18 μm) that was sandblasted in the same manner as in Comparative Example 2 was subjected to the durability test evaluation in the same manner as in Example 1 using Developer 2. The results are shown in Tables 4 and 5.

[0342]

Example 4 A coating material was prepared in the same manner as in Example 1 except that the quaternary ammonium salt compound represented by the formula 6 was used in the preparation of the resin coating layer of the developing sleeve, and the developer carrying member (2) was prepared. Obtained. When the amount of charge of the quaternary ammonium salt compound represented by Formula 6 was measured by blow-off using iron powder as in Example 1, it was positive. Table 3 shows the paint formulation and physical properties of the developer carrying member (2). Durability test evaluation was performed in the same manner as in Example 1 using the developer carrier (2) and the developer 1. Good results were obtained as shown in Tables 4 and 5.

[0343]

[Example 5] The durability test was performed in the same manner as in Example 1 using the developer carrier (2) and the developer 2. The results are shown in Tables 4 and 5. The result was practically satisfactory.

[0344]

Comparative Example 4 Using the developer carrying member (2) and the developer 6, the durability test was evaluated by the same image forming method as in Example 1. The results are shown in Tables 4 and 5. An image with large density unevenness on the page was obtained.

[0345]

Example 6 A coating material was obtained in the same manner as in Example 1 except that the quaternary ammonium salt compound represented by the formula 7 was used in the production of the resin coating layer for the developing sleeve to produce a developer carrying member (3). did. When the charge amount of the quaternary ammonium salt compound represented by the formula 7 was measured by blow-off using iron powder in the same manner as in Example 1, it was positive. Table 3 shows the paint formulation and physical properties of the developer carrying member (3). Durability test evaluation was performed in the same manner as in Example 1 by using the developer carrier (3) and the developer 1. Good results were obtained as shown in Tables 4 and 5.

[0346]

Example 7 A durability test was conducted in the same manner as in Example 1 except that the developer carrier (3) and the developer 2 were used. The results are shown in Tables 4 and 5. The result was practically satisfactory.

[0347]

Example 8 The same as Example 1 except that the amount of the quaternary ammonium salt compound represented by the formula 5 used for the resin coating layer of the developing sleeve was changed from 30 parts by mass to 10 parts by mass to prepare a coating material. To obtain a developer carrier (4).
Table 3 shows the paint formulation and physical properties of the developer carrying member (4).

Durability test evaluation was performed in the same manner as in Example 1 except that the developer carrier (4) and the developer 1 were used. The results are shown in Tables 4 and 5.

[0349]

[Example 9] The same as Example 1 except that the amount of the quaternary ammonium salt compound represented by Formula 5 used in the resin coating layer of the developing sleeve was changed from 30 parts by mass to 50 parts by mass to prepare a coating material. To obtain a developer carrier (5).
Table 3 shows the paint formulation and physical properties of the developer carrying member (5).

Durability test evaluation was performed in the same manner as in Example 1 except that the developer carrier (5) and the developer 1 were used. The results are shown in Tables 4 and 5.

[0351]

Example 10 As the spherical particles used in the resin coating layer of the developing sleeve, the number average particle size used in Example 1 was 5.
Number average particle size of 5.0 instead of 2 μm spherical carbon particles
A developer carrying member (6) was produced in the same manner as in Example 1 except that the PMMA particles (B) of μm were used. This PMM
A particles have a true density of 1.16 g / cm ³ and a volume resistance of 10 ¹⁵
It was Ωcm or more and the ratio of major axis / minor axis was 1.12. Table 3 shows the paint formulation and physical properties of the developer carrying member (6).

Using the developer carrier (6), the same durability test evaluation as in Example 1 was carried out. The results are shown in Tables 4 and 5.

[0353]

[Embodiment 11] A developer carrying member (7) is prepared in substantially the same manner as in the production of the developer carrying member (1) except that boron nitride is used instead of graphite in the production of the resin coating layer of the developer carrying member. It was made. The raw materials used are as follows. -Carbon 15 parts-Boron nitride 85 parts-Ammonia-catalyzed phenol resin intermediate (solid content 50%) 300 parts-Quaternary ammonium salt compound of formula 5 30 parts-Number average particle size 5.2 μm Durability test evaluation was performed in the same manner as in Example 1 by using 30 parts of the spherical carbon particles (A) and 150 parts of methanol and the developer carrier (7) and the developer 1.

The results are shown in Tables 4 and 5.

[0355]

Example 12 A developer carrying body (8) was prepared in the same manner as the developer carrying body (1) except that the coating material for the resin coating layer prepared from the following materials was used. Durability test evaluation was performed in the same manner as in Example 1 using the body (8) and the developer 1. The results are shown in Tables 4 and 5.

[0356]

Example 13 A developer carrying member (9) was prepared in the same manner except that the coating material for the resin coating layer prepared from the following materials was used, and the developer carrying member (9) and the developer 1 were prepared. Durability test evaluation was performed in the same manner as in Example 1. -Urethane resin (solid content 40%) 375 parts-carbon 15 parts-graphite 85 parts-quaternary ammonium salt compound represented by formula 5 30 parts-spherical carbon particles (A) 30 parts-methanol 130 parts The results are shown in Table 4, It shows in Table 5.

[0357]

Example 14 A developer carrying member (1) was prepared in the same manner except that a coating material for a resin coating layer prepared from the following materials was used.
0) was prepared, and the durability test was performed in the same manner as in Example 1 using the developer carrier (10) and the developer 1. -Carbon 15 parts-Graphite 85 parts-Ammonia-catalyzed phenol resin intermediate (solid content 50%) 300 parts-Quaternary ammonium salt compound of the formula 5 30 parts-Methanol 100 parts The results are shown in Table 4. It shows in Table 5.

[0358]

Example 15 In the production of a developer carrier, benzylic acid (2 m) was used as a substance for making the resin coating layer negatively charged.
and an aluminum compound of benzylic acid containing 1 mol of an aluminum atom, specifically, the materials shown in Table 3 were used to prepare a coating material for a resin coating layer to obtain a developer carrier (11). Durability test evaluation was performed in the same manner as in Example 1 using the developer carrying member (11) and the developer 1. The results are shown in Tables 4 and 5.

[0359]

Example 16 In the production of a developer carrier, as a substance for making the resin coating layer negatively charged, 1 mol of a boron atom and 2 benzylic acid were used instead of 1 mol of an aluminum atom.
mol of the benzyl borate compound, specifically, the materials shown in Table 3 were used to prepare a coating material for the resin coating layer to obtain a developer carrier (12). Durability test evaluation was performed in the same manner as in Example 1 using the developer carrier (12) and the developer 1. The results are shown in Tables 4 and 5.

[0360]

Example 17 In the production of a developer carrier, a Cr complex of 3,5-ditertiarybutylsalicylic acid was used as a substance for making the resin coating layer negatively charged, and specifically, the materials shown in Table 3 were used. Was used to prepare a coating material for a resin coating layer to obtain a developer carrier (13). The developer carrier (1
Durability test evaluation was performed in the same manner as in Example 1 using 3) and Developer 1. The results are shown in Tables 4 and 5.

[0361]

Example 18 A chromium complex of azonaphthol containing chlorophenol instead of the quaternary ammonium salt compound represented by the formula 5 as a substance for making the resin coating layer negatively charged in the production of the developer carrier. A developer carrying member (14) was prepared in the same manner as above, except that the durability test was evaluated in the same manner as in Example 1. The triboelectrification amount of the chromium complex of azonaphthol containing chlorophenol with iron powder was determined by the blow-off method as in Example 1.
It had a negative polarity. The results are shown in Tables 4 and 5.

[Examples 19 and 20] Developer carrier 1 used in Example 1
Using the developers 4 and 5 using tin oxide and titanium oxide as the conductive fine powder and performing the durability test by the same image forming method as in Example 1, favorable results were obtained. The results are shown in Tables 4 and 5.

[Comparative Examples 5 and 6] By using the developer sleeves and the developers 4 and 5 which are sandblasted as in Comparative Example 2,
Durability test evaluation was performed by the same image forming method as in Example 1. The results are shown in Tables 4 and 5.

[0362]

According to the present invention, it is possible to stably and appropriately give a proper charge to the developer without overcharging (charge-up) the developer and control the developer to a suitable tribo. An image forming method can be provided.

Further, it is possible to provide an image forming method capable of controlling to a suitable tribo even when a developer produced by a polymerization method, which has been difficult to impart a stable charge to the prior art, is used.

Further, it is intended to provide a stable image forming method which is excellent in stain resistance such as prevention of fusion to the surface of the developer carrying member and which produces a high-quality image with less density decrease and fogging for a long term and durability. You can

Further, the present invention can provide an image forming method which is excellent in transferability and is excellent in recoverability of the transfer residual developer, and which enables simultaneous cleaning and image formation during development.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of a developing device used in an image forming method of the present invention.

FIG. 2 is a schematic diagram showing another configuration example of a developing device used in the image forming method of the present invention.

FIG. 3 is a schematic diagram showing a configuration example of an image forming apparatus using the image forming method of the present invention.

[Explanation of symbols]

1 Electrophotographic photosensitive drum (image carrier) 2 Developer layer thickness control member 3 hopper 4 developer 5 magnet roller 6 Metal Cylindrical Tube 7 Resin coating layer 8 Development sleeve (developer carrier) 9 power supplies 10 stirring blades 11 Gap 12 exposure 13 Contact transfer means 14 Voltage applying means 15 Heat and pressure roller fixing device 17 erase exposure 18 Contact charging means

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) G03G 9/087 G03G 15/08 507B 15/02 101 9/08 101 21/00 301 384 (72) Inventor Masamura Masayoshi Tokyo 3-30-2 Shimomaruko, Ota-ku, Canon Inc., Canon Inc. (72) Satoshi Otake, 3-30-2 Shimomaruko, Ota-ku, Tokyo Inc. (72) Inventor, Ikki Saiki Shimomaruko, Ota-ku, Tokyo 3-30-2 Canon Inc. (72) Inventor Naoki Okamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2H005 AA02 AA08 AA15 AB06 CB07 EA01 EA05 FA06 2H077 AA37 AC01 AC16 AD06 AD13 AD17 AD23 AD31 AD35 DB12 DB14 DB15 EA03 FA13 FA19 FA22 GA01 2H134 GA01 GB02 HF13 KG01 KG03 KG04 KG07 KG08 KH01 KH12 MA07 MA09 MA19 2H200 FA03 FA08 FA12 FA14 GA23 GA34 GA45 GA53 GA56B37 HA28 HA16 HA37 BHAB HA21 HA16 HA37 BHAB HAB HB47 JA02 MA01 MA04 MA20 MB04 MC15

Claims (52)

[Claims] 1. A charging step of applying a voltage to a charging member to charge an image bearing member; an electrostatic latent image forming step of forming an electrostatic latent image on the charged image bearing member; To (d), and (a) a step of supporting a developer contained in a developing container on a developer carrier; (b) a layer thickness of the developer on the developer carrier. A step of regulating by a developer layer thickness regulating member;
(C) A step of carrying and carrying the developer whose layer thickness is regulated to a developing area where the developer carrying member and the image carrying member face each other;
(D) A step of transferring the developer on the developer carrier to an electrostatic latent image on the image carrier to form a toner image; the toner image formed on the surface of the image carrier is electrostatically transferred onto a transfer material. And a fixing step of heating and fixing the toner image transferred onto the transfer material, wherein the developing step transfers the toner image onto the transfer material and then onto the image carrier. The developer also serves as a cleaning step for collecting the remaining developer, and the developer is composed of toner particles containing at least a binder resin component and magnetic powder, inorganic fine powder on the surface of the toner particles, and inorganic fine powder. Is larger than the developer and has an average particle size smaller than that of the developer, and the average circularity determined by the following formula (1) is 0.970 or more, and the magnetic powder is substantially exposed on the surface. Is not a magnetic developer, The carrier comprises a substrate and a resin coating layer formed on the substrate, and the resin coating layer contains at least a negatively chargeable substance. ## EQU1 ## Circularity a = L ₀ / L (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 binder resin for the coating layer of the resin coating layer,
Some or all have, in their molecular structure, —NH ₂ groups, ═N
The image forming method according to claim 1, which has at least either an H group or a —NH— bond. 3. The binder resin for a coating layer of the resin coating layer,
Claim 1 or 2 containing at least a phenol resin.
The image forming method described in 1 .. 4. The phenol resin is a phenol resin produced by adding and condensing phenols and aldehydes using a nitrogen-containing compound as a catalyst, and has —NH ₂ group and ═NH group in its structure. 4. The image forming method according to claim 3, which is a phenol resin having any of a —NH bond and a —NH— bond. 5. The image forming method according to claim 1, wherein the resin coating layer contains at least a quaternary ammonium salt compound that is positively charged with iron powder. 6. The image forming method according to claim 1, wherein the resin coating layer contains a benzylic acid compound. 7. The image according to claim 1, wherein the resin coating layer is a conductive resin coating layer in which conductive fine powder is further dispersed and contained in a binder resin for coating layer. Forming method. 8. The magnetic powder is mainly composed of magnetite, and the content of iron element (B) relative to the content of carbon element (A) present on the surface of the toner particles measured by X-ray photoelectron spectroscopy is The image forming method according to claim 1, wherein the ratio (B / A) is less than 0.001. 9. The volume average particle diameter of the magnetic developer is C, and the minimum value of the distance between the magnetic powder and the surface of the toner particles in a tomographic surface observation of the magnetic developer using a transmission electron microscope (TEM) is The image forming method according to claim 1, wherein D / C ≦ 0.02 when D is set. 10. The toner particles are toner particles obtained by suspension-polymerizing a polymerizable monomer system containing at least a polymerizable monomer as a binder resin component and a magnetic powder in an aqueous medium. The image forming method according to any one of claims 1 to 9. 11. The image forming method according to claim 1, wherein the conductive fine powder of the magnetic developer has a volume resistance of 10 ⁹ Ωcm or less. 12. The image forming method according to claim 1, wherein the conductive fine powder of the magnetic developer has a volume resistance of 10 ⁶ Ωcm or less. 13. The image forming method according to claim 1, wherein the conductive fine powder of the magnetic developer is non-magnetic. 14. The developer according to claim 1, wherein the developer includes toner particles and conductive fine powder having a volume average particle diameter of 0.1 μm to 10 μm. The image forming method according to item. 15. The charging step is a step of charging the image carrier by applying a voltage to a charging member that forms a contact portion with the conductive fine powder and forms a contact portion with the conductive fine powder to contact the charging member. The image forming method according to claim 1. 16. In the charging step, the conductive fine powder contained in the magnetic developer adheres to the image carrier in the developing step and remains on the image carrier even after the transferring step, and at least the charging member. The image forming method according to claim 15, wherein the image forming body is carried to and / or near the contact portion of the image carrier. 17. The conductive fine powder contains at least one kind of oxide selected from fine particles containing at least zinc oxide, tin oxide and titanium oxide. The image forming method according to item. 18. A process cartridge for forming an image by visualizing an electrostatic latent image formed on an image carrier as a toner image with a developer and transferring the visualized developer image onto a transfer material. Wherein the process cartridge comprises an image carrier for carrying an electrostatic latent image, a charging means for charging the image carrier,
The electrostatic latent image formed on the image carrier is visualized as a toner image by developing with a developer, and the toner image remains on the image carrier after being transferred to a transfer material. At least a developing means for collecting the developer, the developing device and the latent image carrier are integrated and detachably attached to the main body of the image forming apparatus, The developer is a toner particle containing at least a binder resin component and a magnetic powder, an inorganic fine powder on the surface of the toner particle, and a conductive fine powder having an average particle size larger than the inorganic fine powder and smaller than the developer. And the average circularity determined by the following formula (1) is 0.970 or more, and the magnetic powder is substantially not exposed on the surface. A developing container for accommodating the A developer carrier for carrying the magnetic developer contained in the image container and conveying it to the developing area, and a developer for controlling the layer thickness of the developer carried on the developer carrier. It has at least a layer thickness regulating member, the developer carrying member comprises a substrate and a resin coating layer formed on the substrate, and the resin coating layer contains at least a negatively chargeable substance. Process cartridge characterized by. ## EQU2 ## Circularity a = L ₀ / L (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. ) 19. A part or all of the binder resin for a coating layer of the resin coating layer has, in its molecular structure, —NH ₂ groups,
19. The process cartridge according to claim 18, which has at least either a = NH group or a -NH- bond. 20. The process cartridge according to claim 18, wherein the coating layer binder resin of the resin coating layer contains at least a phenol resin. 21. The phenolic resin is a phenolic resin produced by adding and condensing phenols and aldehydes using a nitrogen-containing compound as a catalyst, and has —NH ₂ group and ═NH group in its structure. 21. The process cartridge according to claim 20, wherein the process cartridge is a phenolic resin having any one of —, and —NH— bond. 22. The process cartridge according to claim 18, wherein the resin coating layer contains at least a quaternary ammonium salt compound that is positively charged with iron powder. 23. The process cartridge according to claim 18, wherein the resin coating layer contains a benzylic acid compound. 24. The process according to claim 18, wherein the resin coating layer is a conductive resin coating layer in which conductive fine powder is further dispersed and contained in a binder resin for coating layer. cartridge. 25. The magnetic powder is mainly composed of magnetite, and the content of iron element (B) relative to the content of carbon element (A) present on the surface of the toner particles measured by X-ray photoelectron spectroscopy analysis. The process cartridge according to any one of claims 18 to 24, wherein the ratio (B / A) is less than 0.001. 26. The volume average particle diameter of the magnetic developer is C,
19. D / C ≦ 0.02, where D is the minimum value of the distance between the magnetic powder and the toner particle surface in the tomographic surface observation of the magnetic developer using a transmission electron microscope (TEM). 25. The process cartridge according to any one of items 25 to 25. 27. The toner particles are toner particles obtained by suspension polymerization of a polymerizable monomer system containing at least a polymerizable monomer as a binder resin component and a magnetic powder in an aqueous medium. 27. The process cartridge according to any one of claims 18 to 26. 28. The process cartridge according to claim 18, wherein the conductive fine powder of the magnetic developer has a volume resistance of 10 ⁹ Ωcm or less. 29. The process cartridge according to claim 18, wherein the conductive fine powder of the magnetic developer has a volume resistance of 10 ⁶ Ωcm or less. 30. The process cartridge according to claim 18, wherein the conductive fine powder of the magnetic developer is non-magnetic. 31. The developer according to claim 18, wherein the developer contains toner particles and conductive fine powder having a volume average particle diameter of 0.1 μm to 10 μm. The process cartridge according to item. 32. The charging means is means for charging the image carrier by applying a voltage to a charging member which forms a contact portion with the conductive fine powder to form an abutting portion with which the conductive fine powder is interposed. The process cartridge according to any one of claims 18 to 31. 33. The conductive fine powder contained in the magnetic developer adheres to the image carrier during development and remains on the image carrier after transfer, and at least a contact portion between the charging member and the image carrier. 33. The process cartridge according to claim 32, wherein the process cartridge is carried to and / or near the intermediate. 34. The conductive fine powder contains at least one kind of oxide selected from fine particles containing at least zinc oxide, tin oxide and titanium oxide. The process cartridge according to item. 35. A charging means for applying a voltage to a charging member to charge the image carrier, an electrostatic latent image forming means for forming an electrostatic latent image on the charged image carrier, and a developer. And a developer carrier for carrying the developer contained in the developer container and carrying it to the developing area, and a layer thickness of the developer carried on the developer carrier. Developing means having at least a developer layer thickness regulating member for transferring, a transfer means for electrostatically transferring the toner image formed on the surface of the image carrier to a transfer material, and heating the toner image transferred on the transfer material. In an image forming apparatus having a fixing unit for fixing, the developing unit visualizes the electrostatic latent image formed on the image bearing member as a toner image by developing the electrostatic latent image with a developer, The toner image was transferred to the transfer material And a means for collecting the developer remaining on the image bearing member, wherein the developer is toner particles containing at least a binder resin component and magnetic powder, and an inorganic fine powder on the surface of the toner particles. And a conductive fine powder having an average particle size larger than the inorganic fine powder and smaller than the developer, and having an average circularity of 0.970 or more determined by the following formula (1), which is substantially a magnetic powder. The body is a magnetic developer whose surface is not exposed, and the developer carrier comprises a substrate and a resin coating layer formed on the substrate, and the resin coating layer contains at least a negatively chargeable substance. An image forming apparatus characterized by containing. Equation 3] circularity _{a = L 0 / L (1} ) ( wherein, L ₀ represents the circumferential length of a circle having the same projected area as a particle image, L is showing the circumferential length of a projected image of a particle. ) 36. A part or all of the binder resin for a coating layer of the resin coating layer has, in its molecular structure, —NH ₂ groups,
The image forming apparatus according to claim 35, wherein the image forming apparatus has at least one of a = NH group and a -NH- bond. 37. The image forming apparatus according to claim 35, wherein the binder resin for the coating layer of the resin coating layer contains at least a phenol resin. 38. The phenolic resin is a phenolic resin produced by adding and condensing phenols and aldehydes using a nitrogen-containing compound as a catalyst, and has —NH ₂ group and ═NH group in its structure. 38. The image forming apparatus according to claim 37, wherein the image forming apparatus is a phenol resin having any one of-, and -NH- bond. 39. The image forming apparatus according to claim 35, wherein the resin coating layer contains at least a quaternary ammonium salt compound that is positively charged with iron powder. 40. The image forming apparatus according to claim 35, wherein the resin coating layer contains a benzylic acid compound. 41. The image according to any one of claims 35 to 40, wherein the resin coating layer is a conductive resin coating layer in which conductive fine powder is further dispersed and contained in a binder resin for coating layer. Forming equipment. 42. The magnetic powder is mainly composed of magnetite, and the content of iron element (B) relative to the content of carbon element (A) present on the surface of the toner particles measured by X-ray photoelectron spectroscopy is measured. The image forming apparatus according to claim 35, wherein the ratio (B / A) is less than 0.001. 43. The volume average particle diameter of the magnetic developer is C,
D / C ≦ 0.02, where D is the minimum value of the distance between the magnetic powder and the surface of the toner particles in the tomographic surface observation of the magnetic developer using a transmission electron microscope (TEM). 42. The image forming apparatus according to any one of items 42 to 42. 44. The toner particles are toner particles obtained by suspension polymerization of a polymerizable monomer system containing at least a polymerizable monomer as a binder resin component and a magnetic powder in an aqueous medium. The image forming apparatus according to any one of claims 35 to 43. 45. The image forming apparatus according to claim 35, wherein the conductive fine powder of the magnetic developer has a volume resistance of 10 ⁹ Ωcm or less. 46. The image forming apparatus according to claim 35, wherein the conductive fine powder of the magnetic developer has a volume resistance of 10 ⁶ Ωcm or less. 47. The image forming apparatus according to claim 35, wherein the conductive fine powder of the magnetic developer is non-magnetic. 48. The developer according to claim 35, wherein the developer contains toner particles and conductive fine powder having a volume average particle diameter of 0.1 μm to 10 μm. The image forming apparatus according to item. 49. The charging device is a device for charging the image carrier by applying a voltage to a charging member which forms a contact portion with the conductive fine powder to form a contact portion with the conductive fine powder and is in contact therewith. The image forming apparatus according to claim 35. 50. The conductive fine powder contained in the magnetic developer adheres to the image carrier during development and remains on the image carrier even after transfer, and at least a contact portion between the charging member and the image carrier. 50. The image forming apparatus according to claim 49, wherein the image forming apparatus is carried to and / or in the vicinity. 51. The electrically conductive fine powder contains at least one oxide selected from fine particles containing at least zinc oxide, tin oxide, and titanium oxide. The image forming apparatus according to item. 52. A developer container for containing a developer, a developer carrier for carrying the magnetic developer housed in the developer container and transporting the magnetic developer to a development area, 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 developing device uses an electrostatic latent image formed on an image bearing member by using a developer. And visualized as a toner image by performing development, and after the toner image is transferred to the transfer material,
The developer remaining on the image bearing member is collected, and the developer bearing member comprises a substrate and a resin coating layer formed on the substrate, and the resin coating layer has at least a negative charging property. A developing device containing the substance according to claim 35 and used in the image forming apparatus according to any one of claims 35 to 51.