JPH1115204A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the deterioration of a toner, to prevent defective cleaning and to stabilize image formation by incorporating toner particles contg. a bonding resin, specified carbon black and an azo-contg. iron compd. and inorg. fine powder into the toner. SOLUTION: A toner layer formed by a toner carried on the surface of a toner carrier is brought into contact with the surface of an image carrier to develop an electrostatic latent image. The toner contains toner particles contg. a bonding resin, carbon black and an azo-contg. iron compd. and inorg. fine powder. The carbon black has 25-80 nm average primary particle diameter and the azo-contg. iron compd. is represented by the formula, wherein X1 and X2 are H, lower alkyl, etc., (m) and (m') are integers of 1-3, R1 and R3 are H, 1-18C alkyl, etc., (n) and (n') are integers of 1-3, R2 and R4 are H or nitro and A<+> is a cation selected from among an ammonium ion, an H ion and a mixed ion of them.

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 utilizing an electrophotographic method, an electrostatic recording method or a magnetic recording method. More specifically, the present invention relates to a method for forming a toner image on a photoreceptor. The present invention relates to an image forming method used in an image forming apparatus such as a copying machine, a printer, and a facsimile, which forms an image by transferring a toner image onto a transfer material.

[0002]

2. Description of the Related Art Conventionally, many methods have been known as electrophotography. In general, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means. The latent image is developed using toner to produce a visible image,
After transferring the toner image to a transfer material such as paper as necessary,
This is to fix a toner image on a transfer material by heat, pressure or the like to obtain a fixed image. At this time, the toner remaining on the photosensitive member without being transferred to the transfer material after the transfer is cleaned by various methods.

As a method of visualizing an electric latent image, a cascade developing method, a magnetic brush developing method, a non-magnetic one-component developing method, and a pressure developing method are known. Further, a magnetic one-component developing method in which a magnetic toner is used, and a rotating sleeve having a magnetic pole disposed at the center is used to fly between the photosensitive member and the sleeve by an electric field is also used.

As for the printer device, LED and LBP printers have become the mainstream in the recent market, and the direction of technology is higher resolution, that is, 240 dpi or 300 dpi conventionally.
Was 400 dpi, 600 dpi or 120
It has become 0 dpi. Accordingly, higher definition has been required for the developing system. Copiers are also becoming more sophisticated, and are moving toward digitalization. Since the method of forming an electrostatic charge image with a laser in a digital method is mainly used, the resolution has also become higher, and thus, as with a printer, a high resolution image has been obtained.
There is a demand for a high-definition developing method.

For this reason, the particle size of the toner has been reduced,
JP-A-1-112253, JP-A-1-19115
No. 6, JP-A-2-214156, JP-A-2-214156
284158, JP-A-3-181952,
JP-A-4-162048 proposes a toner having a specific particle size distribution and a small particle size.

In recent years, a so-called contact one-component developing method has been proposed in which development is performed by using a semiconductive developing roller or a developing roller having a dielectric layer formed on its surface to press against a photosensitive member surface layer.

In the one-component developing method, when the photosensitive member and the toner carrier have a distance, the lines of electric force concentrate on the edge of the electrostatic latent image on the photosensitive member, and the toner is developed along the lines of electric force. As a result, the quality of the image is likely to be degraded due to the edge effect in which the toner is unbalancedly developed at the edge of the image.

The edge effect is prevented by bringing the photoconductor and the toner carrier very close to each other, but the gap between the photoconductor and the toner carrier is mechanically set, that is, the thickness of the toner layer on the toner carrier is reduced. It is difficult to set the gap smaller than that.

Therefore, the edge effect can be prevented by using the contact one-component developing method in which the toner carrier is pressed against the photosensitive member to perform the development. However, if the toner carrier surface moving speed is the same as the photoconductor surface moving speed, a satisfactory image cannot be obtained when the latent image on the photoconductor is visualized. Therefore, in the contact one-component developing method,
By making the toner carrier surface moving speed different from the photoconductor surface moving speed, part of the toner on the toner carrier is developed with respect to the latent image on the photoconductor surface, and another part of the toner is Peeling off results in a developed image without edge effects that is very faithful to the latent image.

In such a contact one-component developing method, it is essential that the surface of the photoreceptor is rubbed with toner and a toner carrier. Since deterioration or wear is likely to occur, deterioration of durability characteristics remains as a problem, and there has been a demand for an improved method. Therefore, in the contact one-component developing method, for such a reason, it is necessary to improve the durability characteristics of the apparatus, and furthermore, there is an essential problem that it is difficult to increase the speed at which the apparatus is loaded.

A study of a contact-type one-component non-magnetic developing system has been conducted on pages 25 to 28 of the Transactions of Japan Hardcopy '89. However, its durability characteristics are not mentioned.

FUJITSU Sci. Tech.
J. , 28,4, pp. 473-480 (Decemb
er 1992) report an outline of a printer using a one-component contact developing method. However, its durability is not sufficient and there is room for further improvement.

JP-A-5-188765 and JP-A-5-188758 disclose a technique relating to a one-component contact developing method, but do not disclose a technique for improving durability.

In recent years, from the viewpoint of environmental protection, a contact charging method and a photosensitive member in which a charging member is brought into contact with the surface of a photosensitive member to perform charging in a primary charging step and a transfer step using a corona discharge conventionally used. A contact transfer method in which a transfer member is brought into contact with a surface via a transfer material to perform transfer is becoming mainstream.

Such a contact charging method and a contact transfer method are proposed in, for example, JP-A-63-149669 and JP-A-2-123385. These abut a conductive elastic roller on the photoconductor, uniformly charge the photoconductor while applying a voltage to the conductive roller, and then, after exposure, to obtain a toner image by a developing process,
A transfer material is passed while pressing another conductive roller to which a voltage is applied to the photoconductor, and a toner image on the photoconductor is transferred to the transfer material, and then a copy image is obtained through a fixing process. is there.

However, in such a contact transfer method, the transfer member is brought into contact with the photoreceptor via the transfer material at the time of transfer, so that when transferring the toner image formed on the photoreceptor to the transfer material, The toner images are pressed against each other, causing a problem of partial transfer failure called so-called "missing transfer".

Further, as the diameter of the toner becomes smaller, the adhesion force (mirror image force, Van der Waals force, etc.) of the toner particles to the photoreceptor becomes larger than the Coulomb force applied to the toner particles during transfer. As a result, the transfer residual toner tends to increase.

Therefore, the toner and the photoreceptor used in such an image forming method are required to have excellent releasability.

In order to enhance the releasability of the toner from the photoreceptor and to improve the transferability of the toner, a toner having a nearly spherical shape produced by a suspension polymerization method is used.
No. 52 (corresponding US Pat. No. 5,659,857)
Is disclosed. Toners produced by the suspension polymerization method have been proposed for a long time. (For example, Japanese Patent Publication No. 36-1
No. 0231). In this suspension polymerization method, a polymerizable monomer and a colorant (and, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives) are uniformly dissolved or decomposed to obtain a monomer composition. Is adjusted in a continuous layer (for example, an aqueous phase) containing a dispersion stabilizer using a suitable stirrer, and a polymerization reaction is carried out to obtain a toner having a desired particle size. To obtain particles.

In this suspension polymerization method, since a droplet of the monomer composition is formed in a dispersion medium having a large polarity such as water, the component having a polar group contained in the monomer composition is an aqueous phase. It is possible to produce a spherical toner having a so-called core / shell structure or sea-island structure in which a non-polar component is easily present in the surface layer portion, which is an interface with the polymer, and the non-polar component does not exist in the surface layer portion.

By incorporating a wax component, which is a release agent, into a toner produced by the polymerization method, it has become possible to achieve both low-temperature fixing properties and the contradictory performances of blocking resistance and high-temperature offset resistance.

When such a toner is used, there is an advantage that the colorant is hardly exposed to the surface and uniform triboelectricity is obtained. Further, since the classification step can be omitted, the effect of reducing the production cost such as saving energy, shortening the time and improving the process yield is great.

However, since the shape of the toner obtained by this method is substantially spherical, a cleaning failure occurs due to slippage of the toner particles during the cleaning in the above-described electrophotographic process, especially when performing blade cleaning. In some cases, the quality of the copied image may be significantly impaired.

In particular, in non-magnetic one-component contact development, the charge amount of the toner developed on the photoreceptor is high, and the adhesion (mirror image force) of the toner particles to the photoreceptor is increased. Tend to increase. There is also a tendency that the charge amount of the transfer residual toner tends to increase, and the adhesion of the toner particles to the photoreceptor also increases, so that a cleaning failure tends to occur during cleaning.

It is widely known that carbon black is contained in a toner as a black colorant. It is known that the dispersibility of carbon black is greatly affected by physical properties such as primary particle size, specific surface area, structure structure, and surface properties (functional groups on the surface, etc.). If you do
It is known that the selection greatly affects the toner characteristics.

For example, carbon black has a small primary particle size, a large specific surface area, and has a structured structure as compared with other pigments, so that it is very difficult to disperse. If the dispersibility of the carbon black in the toner particles is insufficient, the chargeability of the toner is impaired, and the toner is adversely affected by fogging during development. Other adverse effects such as low density or increased toner consumption also occur.

When a toner is produced using carbon black as a pigment by the above polymerization method, a further problem occurs.

First, since carbon black has a functional group such as a quinone group on the surface that inhibits the polymerizability of the monomer, the polymerization rate is slowed down when the toner is produced by a polymerization method, and the degree of polymerization is increased. However, the particles become unstable during granulation, causing agglomeration and coalescence, making it difficult to take out the particles.

Second, the polymerizable monomer and carbon black (and, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives) are uniformly dissolved or dispersed to prepare a monomer composition. When adjusting, the carbon black is difficult to disperse in the monomer composition, and when this monomer composition is suspended and dispersed in a hydrogen medium to produce toner particles, the carbon black is unevenly distributed in the toner particles. Or toner particles not containing carbon black are likely to be generated.

Third, since carbon black is conductive, the charge on the surface of the toner is liable to leak, which greatly affects the chargeability of the toner. Variations in the carbon black content, dispersibility, and presence or absence of aggregation for each toner particle result in variations in the chargeability of the toner particles, causing a reduction in development efficiency and an increase in fog.

Such variations in the carbon black content, dispersion and agglomeration among the toner particles, and uneven distribution in the particles cause the toner particles having a significantly higher charge amount than the desired charge amount and the low charge amount. As a result, toner particles are generated, and the chargeability of the toner becomes unstable. In particular, in non-magnetic one-component contact development, when the amount of toner particles with a low charge amount increases, the toner particles electrostatically adhere to the toner carrier, fly without being held, and stain the image inside the apparatus, so-called toner scattering, Alternatively, fog on the image is likely to occur. Toner particles having an unnecessarily high charge amount tend to increase transfer residual toner due to an increase in adhesion (mirror image force) to the photoreceptor, and also increase the charge amount of the transfer residual toner. Defects are more likely to occur. Furthermore, the charge amount of the entire toner is reduced by inhibiting the charge of other toner particles,
It is easy to cause toner scattering and fog.

It is also known to include an azo-based iron complex compound as a charge control agent in a toner.

Japanese Patent Application Laid-Open No. Hei 7-281485 proposes a non-magnetic one-component developing method in which a specific azo-based iron complex compound is added to a toner to use a suspension polymerized toner having improved chargeability. However, no studies have been made on carbon black, which greatly affects the polymerizability and chargeability of the toner.

[0034]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to form an electrostatic latent image on a photoreceptor and, in the process of developing the electrostatic latent image, to form a toner image on the surface of the photoreceptor and on a toner carrier In the image forming method using the contact one-component developing method, the development of the electrostatic latent image can be achieved by the contact of the photosensitive layer and the surface of the photoconductor and the surface of the toner carrier with each other. An object of the present invention is to disclose a technique for improving the above.

An object of the present invention is to disclose a technique for improving the deterioration of the surface of a toner carrier.

An object of the present invention is to provide an image forming method which does not cause cleaning failure even in blade cleaning.

An object of the present invention is to provide an image forming method capable of increasing the speed of the apparatus.

It is an object of the present invention to provide an image forming method which improves the fixing property and the anti-offset property, and at the same time has the durability for stably realizing a high quality image for a long period of time.

Further, an object of the present invention is to provide a charging method using a contact charging member without causing poor charging.
An object of the present invention is to provide an image forming method capable of obtaining a stable image over a long period of time.

[0040]

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

The present invention provides: (a) a charging step of charging an image carrier for carrying an electrostatic latent image; and (b) an exposure step of forming an electrostatic latent image on the charged image carrier by image exposure. (C) developing the electrostatic latent image with toner carried on the surface of the toner carrier to form a toner image; and (d) transferring the toner image formed on the surface of the image carrier. (E) a cleaning step of cleaning and removing the toner remaining on the surface of the image carrier after the transfer step; and (a) to (e) using the cleaned image carrier. In the image forming method in which the step (e) is repeated, the toner layer formed by the toner carried on the surface of the toner carrier contacts the surface of the image carrier to develop the electrostatic latent image. Is achieved, the toner , Toner particles containing at least a binder resin, carbon black and an azo-based iron compound, and inorganic fine powder, wherein the carbon black has an average primary particle size of 25 to 80 nm. The systemic iron compound has the following general formula (1)

[0042]

[Outside 2] [In the formula, X ₁ and X ₂ each represent a member selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, and a halogen atom; X ₁ and X ₂ are the same or different; And m ′ represent an integer of 1 to 3, R ₁ and R ₃ represent a hydrogen atom, a C ₁ -C ₁₈ alkyl group,
C ₂ -C ₁₈ alkenyl group, sulfonamide group, mesyl group, sulfonic acid group, carboxyester group, hydroxy group, C ₁ -C ₁₈ alkoxy group, acetylamino group, benzoylamino group and halogen atom R ₁ and R ₃ are the same or different, n and n ′ represent an integer of 1 to 3, R ₂ and R ₄ represent a hydrogen atom or a nitro group, and A ⁺ represents ammonium It shows a cation selected from the group consisting of ions, hydrogen ions, sodium ions, potassium ions and mixed ions thereof. ] The present invention relates to an image forming method comprising the compound represented by the formula:

According to the present invention, a toner using a specific azo-based iron compound and carbon black having specific physical properties as a toner composition is applied to an image forming method having a one-component contact developing system. An image forming method using a pre-development cleaning method in which a rapid rise of toner charge is possible, a high-quality image is obtained, and a cleaning process for removing transfer residual toner from the surface of the image carrier is performed before the development process. When applied to, it is possible to obtain a stable cleaning property.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of a developing device used in the image forming method of the present invention, an elastic roller is used as a toner carrier for supporting a toner which is a one-component developer. A developing device adopting a method in which a toner is coated, a toner layer is formed, and the toner layer is brought into contact with the surface of a photoconductor as an image carrier. At this time, the toner may be either magnetic or non-magnetic, and it is important that the toner layer is in contact with the surface of the photoreceptor. It is preferable that the toner carrier is substantially in contact with the surface of the photoconductor, but this means that the toner carrier is in contact with the surface of the photoconductor when the toner layer is removed from the toner carrier. means. At this time, in order to obtain an image having no edge effect due to an electric field acting between the photoconductor and the elastic roller facing the photoconductor surface via the toner, the surface of the elastic roller or the vicinity of the surface has a potential, and the surface of the photoconductor and the surface of the photoconductor are in contact with each other. An electric field needs to be formed between the surfaces of the toner carriers. For this reason, the elastic layer formed of the elastic rubber on the surface of the low-resistance core material of the elastic roller is resistance-controlled in the medium-resistance region to prevent conduction with the photoreceptor surface and maintain an electric field, or to provide a low-resistance conductive material. It is also possible to use a thin dielectric layer on the surface layer of the sex roller. Further, a configuration in which the surface side facing the photoreceptor surface is coated with an insulating material on a conductive roller, or a configuration in which a conductive layer is provided on an inner surface side not facing the photoreceptor with an insulating sleeve is also possible.

When the one-component contact developing method is used, the surface of the developing roller and the surface of the photoreceptor as a toner carrier for carrying the toner may be rotated in the same direction or in the opposite direction. May be. When the rotation direction is the same, the peripheral speed of the surface of the developing roller is preferably greater than 100% in peripheral speed ratio with respect to the peripheral speed of the photoconductor. If it is less than 100%, there is a problem in image quality such as poor line breakage. The higher the peripheral speed ratio, the more
The amount of toner supplied to the development site is large, the frequency of toner detachment from the latent image increases, and unnecessary parts are scraped off and applied to necessary parts repeatedly, so that an image faithful to the latent image is obtained. can get.

The present invention does not include an image forming method using a two-component developing method using a magnetic brush composed of a toner and a carrier.

In the present invention, it is preferable to include a cleaning step for removing transfer residual toner present on the surface of the image carrier without being transferred in the transfer step. This cleaning step uses a pre-development cleaning method in which a cleaning member is brought into contact with the surface of the image carrier to perform cleaning after the transfer step and before the development step.

In this pre-development cleaning system,
Providing a cleaning unit between the transfer unit and the charging unit by a cleaning member that abuts on the surface of the image carrier and removes transfer residual toner present on the surface of the image carrier can be provided by transferring to the charging member. It is preferable because the influence of the residual toner can be reduced.

In the present invention, a blade, a roller, a fur brush or a magnetic brush can be used as a cleaning member used in the pre-development cleaning system. Two or more of these cleaning members may be used in combination.

The present inventors use a specific carbon black and a specific azo-based iron compound when applying a toner containing carbon black to an image forming method based on a one-component contact development system, so that the photoreceptor can be used. It has been found that the charge amount of the developing toner can be appropriately controlled to prevent the cleaning property from being lowered due to excessive charging of the transfer residual toner.

That is, if the transfer residual toner is excessively charged, the cleaning property is liable to be reduced due to the high adhesion of the transfer residual toner to the photosensitive member. In particular, when the shape of the toner particles is close to spherical, such as a toner produced by a polymerization method such as a suspension polymerization method, the scraping property in the cleaning step is reduced, and slipping through the cleaning member easily occurs, which is disadvantageous for cleaning. Further, excessive charging of the transfer residual toner significantly reduces the cleaning property.

The charge of the transfer residual toner greatly changes depending on the transfer bias condition and the resistance of the transfer material. In general, a voltage having a polarity opposite to the charge polarity of the toner is applied to the transfer bias. If the resistance is high, the toner particles having a high charge will not be transferred due to the strong adhesion to the photoreceptor, but will proceed to the cleaning process with the same charge polarity.

Therefore, as the toner, it is preferable that the charge amount of the developed toner on the photosensitive member is appropriately controlled, and that the toner having the originally high charge amount is not developed on the photosensitive member.

In order to prevent a toner having a high charge amount from being developed on the photoreceptor, it is necessary to impart a charge to the toner or to suppress the chargeability of the toner. However, if the toner is not sufficiently charged, fog, toner scattering, Evils such as a decrease in transferability are likely to occur.

By using a toner in which the specific carbon black of the present invention and a specific azo-based iron compound are used in combination,
It is possible to suppress the generation of excessively high charged toner particles and to give the toner an appropriate charge amount. Thereby, stable performance with excellent durability is exhibited also in the developing step.
This is because the toner of the present invention using the specific carbon black and the specific azo-based iron compound in combination has a charge control effect by a good dispersion of the carbon black and a charge control effect of suppressing excessive charging of the azo-based iron compound itself. Probably a synergistic effect.

In the case of reversal development (where the charge polarity of the toner and the charge polarity of the photoreceptor are the same), if the transfer material is easy to pass an electric field such as thin paper, the toner that is strongly charged to the opposite polarity by the transfer bias Particles are formed, and the toner particles strongly charged to the opposite polarity also have a strong adhesive force to the photoreceptor and tend to be unable to be completely cleaned.

On the other hand, by using the toner of the present invention in which the specific carbon black and the specific azo-based iron compound are used in combination, it is possible to suppress the generation of excessively oppositely charged toner particles. .

The control of toner charging by the transfer bias is also
Due to the synergistic effect of the charge control effect by the good dispersion of carbon black and the charge control effect of suppressing excessive charging of the azo iron compound itself by using the specific carbon black and the specific azo iron compound of the present invention in combination. It is thought to be brought.

Although the reasons for these are not necessarily clear, the present inventors have found that the specific azo-based iron compound used in the present invention causes the toner to have an excessively high charge amount (so-called charge amount). This phenomenon prevents toner particles from retaining excessive reverse charge even when a reverse polarity electric field is applied to the toner during the transfer process, and an azo-based iron compound is used as a dispersant. This also seems to be due to the fact that the amount of triboelectrification of each toner particle becomes uniform as a result of improved carbon black dispersibility.

One of the features of the image forming method of the present invention is that carbon black having a particle size of 25 to 80 nm
That is, a toner in which a specific azo-based iron compound is used in combination.

By using a toner containing a specific carbon black and a specific azo-based iron compound in an image forming method using a one-component contact developing system, the present inventors have found that the toner is excessively charged in the developing step. Less toner particles,
In addition, it has been found that the number of toner particles that are strongly charged to the opposite polarity by the transfer bias in the transfer step is reduced, and therefore, good cleaning can be performed in the cleaning step.

Although the reason is not necessarily clear, according to the knowledge of the present inventors, the specific azo iron compound used in the present invention causes the toner to have an abnormally high charge amount (so-called charge-up phenomenon). ) Prevents the toner from holding excessive reverse charge even when a reverse electric field is applied to the toner in the transfer process, and the azo-based iron complex compound also functions as a dispersant. This is considered to be due to the combination of the effect of improving the dispersibility of carbon black and the improvement of the uniformity of charge for each toner particle.

The average primary particle size of carbon black is 25 n
When it is smaller than m, when used in combination with the azo-based iron compound used in the present invention, the primary particle diameter is fine, so that it is difficult to obtain a sufficient dispersion and the effect of the present invention cannot be obtained. Further, when toner particles are produced by a suspension polymerization method, the toner particle size tends to be coarse, and it is difficult to make full use of the toner particles.

The carbon black has an average primary particle size of 80 n.
If it is larger than m, only a low-density image can be obtained due to insufficient coloring power as a toner even if dispersed well.
Alternatively, there is a disadvantage that the toner consumption increases.

In the present invention, the carbon black preferably has an average primary particle size of 25 to 55 nm.
More preferably, the thickness is 35 to 55 nm. When used in combination with the specific azo-based iron compound of the present invention, when the particle size of the carbon black is within this range, the charge polarity and the charge amount of the transfer residual toner by the charging member are more reliably and uniformly controlled, and This is more advantageous in terms of the stability of the charge amount and the toner coloring power.

The average primary particle size of the carbon black in the toner according to the present invention can be measured by taking a photograph enlarged with a transmission electron microscope.

The carbon black used in the present invention is:
DBP oil absorption is preferably 40 to 150 ml / 100
g, more preferably 50 to 140 ml / 100 g.

When carbon black having a DBP oil absorption of less than 40 ml / 100 g and having a short structure is used, the charge amount of the toner tends to be too low.
If the P oil absorption exceeds 150 ml / 100 g, it is difficult to obtain fine dispersion of carbon black due to a strong long structure.

The measurement of the DBP oil absorption of carbon black is performed in accordance with “ASTM method D2414-79”.

The carbon black used in the present invention is
Specific surface area by nitrogen adsorption is 100 m ² / g or less, preferably 30 to 90 m ² / g, more preferably 40 to 90 m
² / g, and the volatile component is 2% or less, preferably 0.1 to 1.8%, more preferably 0.1 to 1.8%.
It is good to be 1.7%. The carbon black according to the present invention has a smaller specific surface area and a smaller volatile content than the carbon black commonly used in toners.

Carbon black having a small specific surface area and a small volatile content has an advantage of low polymerization inhibition because it has few functional groups having polymerization inhibition, and is also advantageous for uniform dispersion of carbon black in the toner. It is.

If the specific surface area of the carbon black due to nitrogen adsorption is larger than 100 m ² / g, polymerization inhibition tends to occur. If the volatile matter of carbon black exceeds 2%, it is not preferable because a large number of polymerization-inhibiting functional groups are present on the surface.

The measurement of the specific surface area of carbon black by nitrogen adsorption is performed according to “ASTM method D3037-78”.

The measurement of the volatile content of carbon black is described in “J.
This is performed in accordance with IS K 6221-1982. Specifically, first, carbon black as a measurement sample is shaken into a platinum crucible or a porcelain crucible having the same shape and the same capacity as that of a dropping lid until it does not exceed 2 mm below the lid, and weighs the mass. Cover this and put it in an electric furnace,
After heating at 950 ± 25 ° C. for exactly 7 minutes, take out, allow to cool to room temperature in a desiccator, measure the mass after heating, and determine the volatile content by the following formula.

[0075]

[Outside 3] V: volatile matter (%) W _D : mass of dried sample (g) W _R : mass of sample after heating (g)

When the toner is produced by a polymerization method, a masterbatch step of pre-dispersing the carbon black according to the present invention and the azo-based iron complex compound in a polymerizable monomer is carried out at a higher concentration. Can be dispersed, so that a shearing force is easily applied, and the effect of improving dispersibility is increased.

FIG. 6 shows the change in viscosity of the dispersion when carbon black and the azo-based iron compound according to the present invention are dispersed in a styrene monomer. As is clear from the figure, the addition of the azo-based iron compound drastically increases the viscosity of the dispersion, and shows that carbon black is stably dispersed with a high shear force.

FIG. 7 shows the relationship between the oil absorption of carbon black and the viscosity of the dispersion when a certain amount of an azo iron compound is added to carbon black having a particle size of 25 to 80 nm and dispersed in a styrene monomer. Is shown. From this figure,
It is shown that carbon black having a high oil absorption of 40 ml / 100 g or more has higher viscosity of the dispersion system and better dispersibility. However, the oil absorption of carbon black is 1
If it exceeds 50 ml / 100 g, the viscosity of the dispersion becomes too high, and the granulation during polymerization tends to be impaired.

According to the study of the present inventors, the content of carbon black A [wt.
%] And the azo-based iron complex compound B [wt%] preferably satisfy the following condition 2 ≦ A / B ≦ 35, and more preferably satisfy the following condition 3 ≦ A / B ≦ 35. good.

If the content of the azo-based iron compound is too small relative to the content of carbon black, the viscosity does not increase, as is clear from FIG. 7, and the carbon black does not stably disperse. In this case, carbon black precipitates with the lapse of time, and when a toner is produced using this dispersion, the coloring power does not increase.

If the content of the azo-based iron compound is too large relative to the carbon black content, the azo-based iron compound causes secondary agglomeration, dispersibility is reduced, and this secondary agglomerate inhibits polymerization inhibition. This makes it difficult to produce toner particles satisfactorily.

In the present invention, the content of carbon black in the toner particles is preferably 0.1 to 30% by weight, more preferably 1 to 20% by weight, and further preferably 3 to 1% by weight.
The content is preferably 5% by weight.

In the present invention, the content of the azo iron compound in the toner particles is preferably 0.01 to 20% by weight, more preferably 0.1 to 10% by weight, and further preferably 0.1 to 3.0%. % By weight.

When the content of carbon black in the toner particles is less than 0.1% by weight, the coloring power of the toner is low, and it is difficult to obtain a high image density. It is not preferable because it occurs. If the amount exceeds 30% by weight, the dispersibility of carbon black is not sufficiently uniform even if the azo-based iron compound used in the present invention is used, and fog and toner scattering are likely to occur.

If the content of the azo-based iron compound in the toner particles is less than 0.01% by weight, the viscosity of the dispersion tends to increase, and the effect of improving the dispersibility of carbon black is not sufficiently exhibited. On the other hand, if it exceeds 3, the viscosity of the dispersion liquid decreases, and the effect of improving the dispersibility of carbon black decreases.

As described above, the present inventors use carbon black having an appropriate structure in a specific oil absorption range, a small specific surface area and a small volatile content together with a specific azo-based iron complex compound. It has been found that a toner in which the charge control characteristic of the transfer toner when passing through the charging member is further improved can be obtained.

By applying the toner thus obtained to an image forming method of a one-component contact developing system, the proportion of toner particles having an excessively large amount of charge in the transfer residual toner, or
Since the existence ratio of the toner particles having an excessively opposite polarity and an excessive charge amount is small, the transfer residual toner can be satisfactorily removed from the photoreceptor surface in the cleaning step, and a high-quality image can be formed.

The azo-based iron compound used in the present invention has a structure represented by the following formula (1).

[0089]

[Outside 4] [Wherein, X ₁ and X ₂ each represent a member selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, and a halogen atom; X ₁ and X ₂ are the same or different; And m 'is 1-3
And R ₁ and R ₃ are a hydrogen atom, C ₁
Alkyl -C _18, alkenyl group of C 2 _{-C 18,} a sulfonamide group, a mesyl group, a sulfonic acid group, carboxy ester group, hydroxy _group, an alkoxy group of C 1 _{-C 18,} an acetylamino group, benzoylamino group And a member selected from the group consisting of a halogen atom, wherein R ₁ and R ₃ are the same or different, and n
And n ′ represent an integer of 1 to 3, and R ₂ and R ₄
Represents a hydrogen atom or a nilot group, and A ⁺ represents a cation selected from the group consisting of ammonium ion, hydrogen ion, sodium ion, potassium ion and a mixed ion thereof. ]

In the present invention, “lower” means having 1 to 6 carbon atoms.

Typical specific examples of the azo-based iron complex compound of the above general formula include the following compounds.

[0092]

[Outside 5]

[0093]

[Outside 6]

The azo-based iron complex compound is also used as a negative charge control agent. The compound can be synthesized by a known method.

In the present invention, the shape of the toner is preferably close to a sphere from the viewpoint of improving the fusion of the toner on the toner carrier and the contamination of the surface of the charging member in image formation on a large number of sheets. Shape factor SF− indicating the shape of the toner
1 and SF-2 are preferably such that the value of SF-1 is 100 <S
F-1 ≦ 160 and the value of SF-2 is 100 <S
F-2 ≦ 140 is preferable, and more preferably, the value of SF-1 is 100 <SF-1 ≦ 140, and the value of SF-2 is 100 <SF-2 ≦ 120. It is preferable to improve the transferability while performing.

In the present invention, SF-1 indicating the shape factor is used.
And SF-2 are, for example, FE-SEM (S
-800), 100 toner images of 2 μm or more, which are magnified 1000 times, are randomly sampled, and the image information is introduced into, for example, an image analyzer (Luzex III) manufactured by Nicolet and analyzed via an interface. The values calculated from the following formulas are used as shape factors SF-1 and SF-2.
Is defined.

[0097]

[Outside 7] (Where MXLNG is the absolute maximum length of the particle, PERI is the perimeter of the particle, and AREA is the projected area of the particle.)

The shape coefficient SF-1 indicates the degree of roundness of the toner particles, and the shape coefficient SF-2 indicates the degree of unevenness of the toner particles.

When the shape factor SF-1 of the toner exceeds 160, the toner is separated from the spherical shape and approaches an irregular shape, the toner is easily broken in the developing device, the particle size distribution fluctuates, and the charge amount distribution becomes broad. Land fog and inverted fog are likely to occur. When the shape factor SF-2 of the toner exceeds 140,
It is not preferable because the transfer efficiency of the toner image at the time of transfer from the photoreceptor to the transfer material is lowered, and the transfer of characters and line images is lost during transfer.

To faithfully develop minute latent image dots for higher image quality, the toner particles have a weight average diameter of 3 μm.
m to 9 μm, preferably 4 μm to 8 μm, and the coefficient of variation in the number distribution is 35% or less, preferably 25% or less. In the case of toner particles having a weight average diameter of less than 3 μm, a large amount of toner particles remain untransferred on the photoreceptor or the intermediate transfer member due to a decrease in transfer efficiency, and further, it is likely to cause non-uniform unevenness of an image due to fog or poor transfer. .
When the weight average diameter of the toner particles exceeds 9 μm, fusion to members such as the surface of the photoconductor and the intermediate transfer material is likely to occur.
When the coefficient of variation in the number distribution of toner particles exceeds 35%, the tendency is further enhanced.

Coefficient of variation A in the number distribution of toner particles
Is calculated from the following equation.

Coefficient of variation = [S / D ₁ ] × 100 where S represents a standard deviation value in the number distribution of toner particles, and D ₁ is a number average particle diameter (μm) of the toner particles.
Is shown. ]

The average particle size and the particle size distribution of the toner particles are measured by using a Coulter Counter TA-II or a Coulter Multisizer (manufactured by Coulter), and an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution.
C9801 personal computer (manufactured by NEC) is connected and the electrolyte is 1% NaC using primary grade sodium chloride.
Prepare an aqueous solution. For example, ISOTON R-I
I (manufactured by Coulter Scientific Japan) can be used. As a measuring method, the electrolytic aqueous solution 100 to
In 150 ml, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and a 100 μm aperture was used as the aperture by the Coulter Counter TA-II.
The volume and number distribution of the toner were measured to calculate a volume distribution and a number distribution. Then, a volume-based weight average particle diameter (D4) determined from the volume distribution according to the present invention and a number-based number average particle diameter (D1) determined from the number distribution were determined.

In the present invention, it is preferable to add a release agent to the toner particles in order to improve the fixing property and the offset resistance of the toner.

As the release agent used in the present invention, AS
The main endothermic maximum peak value (melting point) in a DSC curve measured according to TM D3418-8 is 30 to 120.
Compounds having a temperature in the range of preferably from 40 to 90 ° C are more preferable. If the maximum peak value (melting point) of the wax is less than 30 ° C., the self-cohesive force of the release agent becomes weak, and as a result, the high-temperature offset resistance becomes weak, which is not preferable. If the maximum peak value (melting point) of the wax exceeds 120 ° C., the fixing temperature becomes high, and it becomes difficult to appropriately smooth the surface of the fixed image, which is not preferable from the viewpoint of lowering the color mixing.

Further, when toner particles are obtained by a polymerization method, since the granulation and polymerization are carried out in an aqueous medium, if the endothermic maximum peak value (melting point) is high, the release agent is mainly deposited during granulation. It is not preferable because it comes.

For the measurement of the temperature (melting point) of the maximum peak value of the release agent, for example, DSC-7 manufactured by Perkin Elmer Co., Ltd. is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the heat quantity correction uses the heat of fusion of indium. For the sample, an aluminum pan was used and an empty pan was set as a control, and the temperature was raised from 20 ° C to 180 ° C at a heating rate of 1 °.
The measurement is performed at 0 ° C./min.

Examples of the release agent include polymethylene wax such as paraffin wax, polyolefin wax and Fischer-Tropsch wax, amide wax, higher fatty acid, higher fatty acid metal salt, long-chain alkyl alcohol, ester wax and derivatives thereof (for example, These graft compounds or block compounds). Particularly, the ester wax is more preferable in that the fixing property can be improved because the ester wax acts as a plasticizer of a binder resin of the toner such as a styrene acrylic copolymer at the time of fixing the toner image by heating.

In the present invention, a toner having a core / shell structure in the toner, the shell portion of which is formed of a polymer synthesized by polymerization, and the core portion of which is constituted by wax as a release agent, is used in the present invention. When used in the image forming method, deterioration of toner particles and contamination of the image forming apparatus can be prevented, so that good chargeability is maintained and a toner image excellent in dot latent image reproduction can be formed for a long time. It becomes possible. In addition, since the wax acts efficiently at the time of fixing by heating and pressing, it is preferable because the low-temperature fixing property and the high-temperature offset resistance can be improved.

In the present invention, the toner having a core / shell structure refers to a shell formed by a polymer synthesized by polymerization of a polymerizable monomer on a surface of a core with a wax as a release agent. Means that the toner is in a state of being carried out.

In the present invention, the core / shell structure of the toner can be confirmed by observing the tomographic plane of the toner particles.

As a specific method for observing the tomographic plane of the toner particles, the toner particles are sufficiently dispersed in a room-temperature curable epoxy resin, and then cured in an atmosphere at 40 ° C. for 2 days. Is dyed with ruthenium tetroxide and, if necessary, osmium tetroxide, and then a flaky sample is cut out using a microtome with diamond teeth, and the tomographic morphology of the toner particles is determined using a transmission electron microscope (TEM). Observe. It is preferable to use a ruthenium tetroxide dyeing method in order to provide a contrast between materials by utilizing a slight difference in crystallinity between the wax and the resin constituting the outer shell. FIG. 9 shows a typical example.

In the present invention, the content of the release agent in the toner particles is preferably 2 to 30% by weight, more preferably 2 to 25% by weight. When the content of the release agent is less than 2% by weight, the fixability is not sufficiently improved, and when the content is more than 30% by weight, coalescence of the toner particles tends to occur at the time of granulation even in the production by the polymerization method. Those having a wide distribution were easily formed, and were not suitable for the present invention.

In the present invention, when a toner having a core / shell structure is produced, a polar resin is further added to the resin constituting the shell portion so that the shell portion is encapsulated in the core portion by wax as a release agent. Is particularly preferred.

As the polar resin used in the present invention, a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a saturated polyester resin, and an epoxy resin are preferably used.

The content of the polar resin in the toner particles is preferably 1 to 20% by weight, more preferably 2 to 16% by weight.
(Based on the weight of toner particles).

When the content of the polar resin is less than 1% by weight, the effect of addition is not sufficiently exhibited, and when it exceeds 20% by weight, the charging characteristics of the toner are often affected. In particular, the chargeability of the toner in a high-temperature, high-humidity environment tends to be lowered, which is not preferable.

In the present invention, an outermost shell resin layer may be further provided on the surface of the toner.

The glass transition temperature of the outermost resin layer is designed to be equal to or higher than the glass transition temperature of the outer resin layer in order to further improve the blocking resistance, and is further crosslinked so as not to impair fixability. Is preferred. It is preferable that the outermost resin layer contains a polar resin and a charge control agent for improving the chargeability.

The method for providing the outermost shell layer is not particularly limited, but includes, for example, the following methods.

1. In the latter half of the polymerization reaction or after the end, if necessary, a monomer in which a polar resin, a charge control agent, and a cross-linking agent are dissolved and dispersed in the reaction system is added, the mixture is adsorbed on polymer particles, and a polymerization initiator is added to perform polymerization. Method.

2. Emulsion polymer particles or soap-free polymer particles composed of a monomer containing a polar resin, a charge control agent, and a cross-linking agent are added to the reaction system as required, and are aggregated on the surface of the polymer particles and, if necessary, fixed by heat. Method.

3. A method in which emulsion polymerized particles or soap-free polymerized particles comprising a monomer containing a polar resin, a charge control agent, and a cross-linking agent are mechanically fixed to the toner particle surface in a dry system, if necessary.

In the present invention, a monomer composition containing a wax as a release agent and a polar resin together with a colorant and a polymerizable monomer in an aqueous medium is polymerized in an aqueous medium to produce toner particles. In the case of producing toner particles containing a wax and a polar function, the produced toner particles are composed of a core portion made of wax, a shell composed of a polymer synthesized by polymerizing a polymerizable monomer, and a polar resin. And a core / shell structure having a portion, and a polar resin is located in the outermost resin layer of the shell portion. Therefore, in the case of toner particles of such a form, since a polar group is present on the surface of carbon black used as a colorant, the carbon black does not enter into the non-polar wax, and is contained in the shell portion. Therefore, the coloring power tends to be lower than that of the toner particles in which the carbon black is uniformly dispersed in the toner particles, and the polar resin is located in the outermost shell layer of the shell portion. Therefore, the ratio of carbon black located on the surface portion of the toner particles is reduced, so that the triboelectric charging property of the toner tends to be lower than that of the toner particles containing no polar resin.

However, in the present invention, since the toner particles contain carbon black and a specific azo-based iron compound as described above, the toner particles are improved by the effect of improving the dispersibility of carbon black by the azo-based iron compound. It is possible to suppress a decrease in the coloring power, and to suppress a decrease in the triboelectric charging property of the toner by the effect of improving the dispersibility of the carbon black and the high charge control effect of the azo-based iron compound.

In the image forming method of the one-component contact developing system of the present invention, the toner on the toner carrier comes into contact with the surface of the image carrier at the time of development. It is preferable that the toner has resistance to fusing of the toner to the surface of the carrier.

Accordingly, the toner used in the one-component contact developing system is required to have higher mechanical properties than the toner used in the one-component non-contact developing system or the two-component developing system having a toner and a carrier. .

The resin component of the toner particles used in the present invention has a C component insoluble in THF (tetrahydrofuran) and a component soluble in THF, and the component soluble in THF is a gel permeation chromatogram. In the molecular weight distribution measured by (GPC), it has an A component having a molecular weight of less than 1,000,000 and a B component having a molecular weight of 1,000,000 or more,
It is preferable that these A component, B component and insoluble C component satisfy the following conditions.

TH of the resin component of the toner particles according to the present invention
The components soluble in F (corresponding to the above components A and B) are GP
In the molecular weight distribution of C, the number average molecular weight (Mn) is preferably 9000 to 1,000,000, more preferably 10 to 10,000,000.
000 to 500,000, weight average molecular weight (Mw)
The ratio (Mw / Mn) of the toner and the number average molecular weight (Mn) is preferably from 5 to 500, and more preferably from 7 to 400, so that various properties required for the toner can be achieved in a well-balanced manner.

The resin component of these toner particles preferably has a content ( _A ) of component ( _A ) of 30 to 95% by weight, more preferably 50 to 90% by weight, based on the weight of the resin component.
, And the (2) the content of the B component (W _B) is preferably 0
20 wt%, more preferably, from 1 to 20 wt%, (3) the content of the C component (W _C) is preferably 0 to 7
0% by weight, more preferably 1 to 70% by weight,
(4) total content of components B and C (W _B + W _C) is preferably 5 to 70 wt%, more preferably 10 to 50 wt%
Is preferably used by the image forming method of the present invention.

In the resin component of the toner particles used in the present invention, the above-mentioned component A (THF-soluble component having a molecular weight of less than 1,000,000) in the THF-soluble GPC molecular weight distribution has a molecular weight of 3,000 to 50,000. Preferably 5000 molecular weight
Having a main peak in the region of 22000 to 22000 is preferable because matching with the image forming apparatus is good. When the main peak has a molecular weight of less than 3000, the charging characteristics of the toner may be deteriorated, fusion may occur at a contact portion with the image forming apparatus, or high-temperature offset resistance and blocking resistance may be reduced. If the molecular weight of the main peak exceeds 50,000, the contact portion with the image forming apparatus is liable to be damaged, and the low-temperature fixability tends to be remarkably reduced.

When the content of the component _A (W _A ) is less than 30% by weight, the low-temperature fixability tends to decrease, and when it exceeds 95% by weight, matching with the image forming apparatus deteriorates. However, toner fusion and image quality deterioration are likely to occur.

If the content of the component _B (WB) exceeds 20% by weight, the high-temperature offset resistance is improved, but the low-temperature fixability is undesirably reduced.

If the content of the component _C (W _C ) is more than 70% by weight, the matching with the image forming apparatus may be impaired, or low-temperature fixing may be difficult, which is not preferable. Even if there is no C component at all, if the B component is contained preferably in 5 to 20% by weight, more preferably 10 to 20% by weight, it is possible to maintain developability and fixing property. Conversely, even if there is no B component at all, if the C component is contained in an amount of preferably 5 to 70% by weight, more preferably 10 to 70% by weight, the developability and the fixing property can be maintained.

Further, the total content of the B component and the C component (W _B
+ W _C) is preferably 5 to 70 wt%, it is better and more preferably from 10 to 50 wt%. If the total content of the components B and C (W _B + W _C) is less than 5 wt%, the toner charging characteristics and high-temperature offset resistance, even worse matching with the image forming apparatus, the toner fusing When the content exceeds 70% by weight, the low-temperature fixability is undesirably reduced.

In the present invention, the molecular weight and the content (W _A , W _B, and W) of each resin component (A to C components) in the toner particles are determined.
_C ) is measured and calculated by the following method.

In the present invention, the C component insoluble in THF refers to a resin component insoluble in THF (tetrahydrofuran) as a resin component in toner particles, and the content thereof is determined based on the content of the resin composition containing a crosslinking component. As a measure of the degree of cross-linking, even if the THF-insoluble content is 0% by weight, it does not necessarily mean that cross-linking is not performed. C insoluble in THF
The content of the component is defined by a value measured as follows.

First, the content of an additive in toner particles such as a pigment is measured in advance by a known method. Next, a fixed amount of 0.5 to 1.0 g of the developer is weighed (W ₁ g), placed in a cylindrical filter paper (No. 86R manufactured by Toyo Roshi Kaisha), subjected to a Soxhlet extractor, and 100 to 200 ml of THF is used as a solvent. After extracting for 20 hours and evaporating the soluble component extracted by the solvent, the resultant is vacuum-dried at 100 ° C. for several hours, and the amount of the THF-soluble resin component is weighed (W ₂ g). Then, of the additives such as pigments contained in the fixed amount of the developer, the weight of the component soluble in THF is W ₃ g, and the weight of the component insoluble in THF is W ₄ g. According to the formula, the THF-insoluble component (the component C) in the resin component is calculated.

[0139]

[Outside 8]

On the other hand, the main peak position and content (W _A ) of the component A having a molecular weight of less than 1,000,000 in the molecular weight distribution of GPC of the component soluble in THF, the content (W _B ) of the component B having a molecular weight of 1,000,000 or more, (Based on the weight of the resin component) means that the THF-soluble resin component obtained in the above-mentioned Soxhlet extraction is GP
It is used as a measurement sample of C and is determined from the obtained molecular weight distribution. The area% of the region having a molecular weight of less than 1,000,000 (component A) and the region having a molecular weight of 1,000,000 or more (component B) are expressed as weight%
Then, the weight percentage of the A component and the B component (W _A and W _B ) is determined based on the assumption that the weight is equal to the weight of the resin component.

In the present invention, the resin component contains a wax component in addition to the binder resin.

In the present invention, the molecular weight distribution of the resin component in the toner particles is measured by GPC (gel permeation chromatography) under the following conditions. In addition, the material used is a material which has been dispersed / dissolved in a solvent in advance and filtered through a solvent-resistant membrane filter (pore diameter: 0.3 μm).

Apparatus: GPC-150C (manufactured by Waters) Column: KF801 to 7 (manufactured by Shodex) Temperature: 40 ° C. Solvent: THF Flow rate: 1.0 ml / min Sample: concentration 0.05 to 0. 0.1 ml of 6% by weight sample
Injection

Measurement is performed under the above conditions, and the molecular weight of the sample is calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

As the binder resin for the toner used in the present invention, generally used styrene- (meth) acrylic copolymers, polyester resins, epoxy resins and styrene-butadiene copolymers can be used. I can do it. In the method of obtaining toner particles by a polymerization method, those monomers are preferably used. Specifically, styrene, o (m-, p-)-methylstyrene, m (p-)-
Styrene monomers such as ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, (meth) acrylic acid Dodecyl, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
(Meth) acrylate monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile and acrylamide Is preferably used. These monomers are described in Polymer Handbook, 2nd edition-P139-1
Monomers may be used alone or in an appropriate mixture so that the theoretical glass transition temperature (Tg) described in 92 (manufactured by John Wiley & Sons) indicates 40 to 75 ° C. When the theoretical glass transition temperature is lower than 40 ° C., problems arise in terms of the storage stability of the toner and the durability stability of the developer, and when it exceeds 75 ° C., the fixing point increases.

Furthermore, in the present invention, the above-mentioned THF
100000 to produce insolubles and / or molecular weight
In order to generate 0 or more components, it is preferable to use a crosslinking agent during the synthesis of the binder resin.

As the crosslinking agent used in the toner of the present invention, divinylbenzene, bis (4-acryloxypolyethoxyphenyl) propane,
Ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate , Triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 200, # 400, # 600 diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, polyester type diacrylate (MANDA Nippon Kayaku) and One in which the above diacrylate is replaced with methacrylate is exemplified.

As polyfunctional crosslinking agents, pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate,
Tetramethylolmethanetetraacrylate, oligoester acrylate and its methacrylate, 2,2-
Examples include bis (4-methacryloxy, polyethoxyphenyl) propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate and triallyl trimellitate.

These cross-linking agents can be used in combination with other vinyl monomers 1
The amount is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 00 parts by weight.

If the amount of the crosslinking agent is less than 0.05 parts by weight, the crosslinking reaction of the binder resin is not sufficiently performed, and
If the amount is more than 10 parts by weight, the crosslinking reaction of the binder resin proceeds excessively, and it becomes difficult to control the content of the THF-insoluble portion of the toner particles in the range of 5 to 70% by weight.

The azo iron complex compound used in the present invention also has a function as a charge control agent, but may further use another charge control agent. As the other charge control agent, a known charge control agent can be used, but a charge control agent having a high charging speed and capable of stably maintaining a constant charge amount is preferable. Further, in the case of producing toner particles by a polymerization method in the present invention, a charge control agent having no polymerization inhibition and having no solubilized substance in an aqueous system is particularly preferable.

Specific compounds of another charge control agent include:
Metal compounds of salicylic acid, naphthoic acid, dicarboxylic acid or derivatives thereof, metal compounds of azo pigments or derivatives thereof, sulfonic acids, high molecular compounds having carboxylic acids as side chains, boron compounds, urea compounds, silicon compounds as negatives , Caryx Arene is available. As the Hoj type, nigrosine, a triphenylmethane type compound, a quaternary ammonium salt, a high molecular compound having the quaternary ammonium salt in a side chain, a guanidine compound, and an imidazole compound are preferably used.

Another charge control agent is preferably 0.2 to 10 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the binder resin.
It is preferable that 5 to 5 parts by weight be contained in the toner particles. However, in the present invention, the addition of another charge control agent is not essential, and even in the case of using a non-magnetic-component blade coating developing method, the toner is positively used for frictional charging with the blade member or the sleeve member to thereby form toner in the toner. Need not necessarily include another charge control agent.

In the case where toner particles are produced by the polymerization method in the present invention, for example, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-
Azo such as azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile Benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate,
A peroxide-based polymerization initiator such as cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, or lauroyl peroxide is used.

The amount of the polymerization initiator to be added varies depending on the desired degree of polymerization, but generally ranges from 0.5 to 2 parts by weight based on the monomer.
0% by weight is used. Although the type of the initiator slightly varies depending on the polymerization method, it is used alone or in combination with reference to the 10-hour half-life temperature.

In order to control the degree of polymerization, known crosslinking agents, chain transfer agents and polymerization inhibitors may be further added and used.

When the suspension polymerization is used as the toner production method according to the present invention, for example, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, carbonate, or the like may be used as an inorganic oxide as a dispersant. Examples include calcium, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, magnetic substances, and ferrite. As the organic compound, for example, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, and starch are used by being dispersed in an aqueous phase. These dispersants are preferably used in an amount of 0.2 to 10.0 parts by weight based on 100 parts by weight of the polymerizable monomer.

As these dispersants, commercially available ones may be used as they are. However, in order to obtain finely dispersed particles having a uniform particle size, the inorganic compound is formed under high-speed stirring in a dispersion medium. Can also be used. For example, in the case of tricalcium phosphate, a dispersant suitable for a suspension polymerization method can be obtained by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring. A surfactant may be used in an amount of 0.001 to 0.1 part by weight to make these dispersants finer. Specifically, commercially available nonionic, anionic, and cationic surfactants can be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate,
Sodium oleate, sodium laurate, potassium stearate and calcium oleate are preferably used.

In the case where a polymerization method is used in the toner production method according to the present invention, the toner can be specifically produced by the following production method.

Carbon black and an azo-based iron compound, and if necessary, a charge control agent, a polymerization initiator, and other additives are added to the polymerizable monomer, and the mixture is homogenized by a mixing device such as a homogenizer or an ultrasonic disperser. To prepare a polymerizable monomer composition. The polymerizable monomer composition thus prepared is dispersed in an aqueous phase containing a dispersion stabilizer using a conventional mixer or a mixing device such as a homomixer or a homogenizer. Preferably, the stirring speed and time are adjusted so that the droplets of the polymerizable monomer composition have a desired size of the toner particles, and the granulation is performed. Thereafter, by the action of the dispersion stabilizer, the stirring may be performed to such an extent that the particle state is maintained and the particles are prevented from settling.
The polymerization is performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction. Further, in order to improve the durability in the image forming method using the toner of the present invention, the polymerization reaction is performed to remove unreacted polymerizable monomers and by-products. The aqueous medium may be partially distilled off in the second half or after the end of the polymerization reaction. After the polymerization reaction,
The generated toner particles are washed, collected by filtration, and dried. In the suspension polymerization method, it is generally preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer system.

In the present invention, as described above, a polymerizable monomer composition is prepared through a master batch process in order to improve the dispersibility of carbon black in toner particles.

Specifically, based on 100 parts by weight of the first polymerizable monomer, preferably 4 to 40 parts by weight, more preferably 5 to 25 parts by weight of carbon black and preferably 0.2 to 5 parts by weight. By mixing and dispersing the azo iron compound in an amount of 0.5 parts by weight, more preferably 0.5 to 3 parts by weight, carbon black can be mixed at a very high concentration with respect to the polymerizable monomer. And the share at the time of mixing is sufficiently increased, so that the dispersibility of carbon black can be drastically improved in combination with the dispersing effect of the azo-based iron compound.

When the mixing amount of carbon black is less than 4 parts by weight, even if an azo-based iron compound is used, the viscosity of the dispersion is small and sufficient dispersion is difficult to achieve. Meanwhile, 4
If the amount exceeds 0 parts by weight, it becomes difficult to control the viscosity of the dispersion, and as a result, the dispersion tends to be uneven.

When the amount of the azo-based iron compound is less than 0.2 parts by weight, the effect of increasing the viscosity of the dispersion is insufficient. On the other hand, when the amount exceeds 5 parts by weight, the viscosity increases. And dispersion tends to be non-uniform.

The viscosity of the (masterbatch) dispersion containing the first polymerizable monomer, carbon black and an azo-based iron compound, and if necessary, a wax component and / or a charge control agent is preferably 100 to 100. 2000 centimeter voice,
More preferably, it is good to be 150-1600 cm voice.

When the viscosity of the dispersion is less than 100 centipoise, the viscosity is too low and the dispersion share is not applied.
Uniform dispersion of carbon black becomes difficult. On the other hand, 20
When the viscosity exceeds 00 centivoise, the viscosity is too high and it is difficult to maintain a uniform dispersion state, and at the same time, the dischargeability from the manufacturing apparatus is deteriorated and the productivity is reduced. This dispersion is mixed with a second polymerizable monomer and, if necessary, a wax component, a polymer having a polar functional period, a charge control agent, a polymerization initiator and other additives to form a polymerizable monomer. A monomer composition is prepared.

The mixing amount of the second polymerizable monomer with respect to 100 parts by weight of the dispersion is preferably 20 to 100 parts by weight, more preferably 30 to 70 parts by weight. Is good in terms of uniform dispersibility in a polymerizable monomer.

When the mixing amount of the second polymerizable monomer is less than 20 parts by weight, it takes time to disperse uniformly, and when it exceeds 100 parts by weight, reagglomeration of carbon black is required. Etc. are likely to occur, and it also takes time for uniform dispersion.

The content ratio of carbon black in the polymerizable monomer composition relative to the weight of the polymerizable monomer composition is preferably 1 to 20% by weight, more preferably 3 to 1%.
An amount of 5% by weight is good in terms of the coloring power of the toner and the stabilization of the charging of the toner.

When the content of carbon black in the polymerizable monomer composition is less than 1% by weight, it is difficult to achieve a high image density, and when it exceeds 20% by weight, particularly high content is obtained. The charge of the toner under moisture tends to be low.

The content ratio of the azo-based iron compound to the weight of the polymerizable monomer composition in the polymerizable monomer composition is as follows:
Preferably 0.1 to 3.0% by weight, more preferably 0.1 to 3.0% by weight.
The content of 2 to 2.0% by weight is preferable in that the viscosity of the dispersion is maintained in an appropriate state and the uniform dispersibility of carbon black is improved.

When the content of the azo-based iron compound in the polymerizable monomer composition is less than 0.1% by weight, the effect of improving the dispersibility of carbon black is exhibited without increasing the viscosity of the dispersion. On the other hand, when the content exceeds 3.0% by weight, the viscosity of the dispersion liquid is reduced, and the effect of improving the dispersibility of carbon black is also lost.

In the present invention, by coating the surface of the toner particles with an external additive, the toner particles are imparted with appropriate fluidity and chargeability, while at the same time improving the cleaning performance and reducing the contact members such as the photosensitive member charging member. It is desirable to adopt a configuration for the electrical member that can alleviate the stress of the toner, and the coverage of the external additive on the toner surface is preferably 5 to 99%, more preferably 10 to 99%. Further, by having the inorganic fine powder as an external additive on the surface of the toner particles, the transfer efficiency is improved, and the omission during transfer of a character or a line image is improved.

The coverage of the external additive on the surface of the toner particles was determined by using an FE-SEM (S-800) manufactured by Hitachi, Ltd.
One hundred samples were randomly sampled, and the image information was introduced into an image analyzer (Luzex3) manufactured by Nicole via an interface, analyzed, and calculated.

The external additive used in the present invention preferably has an average particle size of 1/10 or less of the weight average particle size of the toner particles from the viewpoint of durability when added to the toner.
The average particle size of the additive means the average particle size obtained by observing the surface of the toner particles with an electron microscope.

Examples of the external additive include metal oxides (aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide, chromium oxide,
Tin oxide and zinc oxide), nitride (silicon nitride, carbide (silicon carbide)), metal salts (calcium sulfate, barium sulfate and calcium carbonate), fatty acid metal salts (zinc stearate and calcium stearate), carbon black and silica These external additives are preferably used in an amount of 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, based on 100 parts by weight of the toner particles. A hydrophobized material is more preferable.

The inorganic fine powder used in the present invention includes:
Particularly, in order to improve charging stability, developability, fluidity, and storage stability, it is preferable that at least one kind is fine particles selected from silica, alumina, titania, or a composite oxide thereof. Furthermore, silica is more preferable. For example, as the silica, both a so-called dry method produced by a vapor phase oxidation of a silicon halide or an alkoxide or a so-called fumed silica and a so-called wet silica produced from an alkoxide water glass can be used. . Dry silica having less silanol groups on the surface and inside the silica fine powder and having less production residue such as Na ₂ O and SO ₃ ²⁻ is more preferable. In the case of fumed silica, for example, by using another metal halide such as aluminum chloride or titanium chloride together with a silicon halide in the production process, it is also possible to obtain a composite fine powder of silica and another metal oxide. Is also included.

The inorganic fine powder used in the present invention is BET
The specific surface area by measuring nitrogen adsorption in law 30 m ² / g or more, particularly in the range of 50 to 400 m ² / g give good results. The inorganic fine powder is preferably 0.1 to 8 parts by weight, more preferably 0.5 to 5 parts by weight, further preferably more than 1.0 part by weight and 3.0 parts by weight based on 100 parts by weight of the toner particles. Good to use up to. The inorganic fine powder used in the present invention may be, if necessary, a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, a silane having a functional period for the purpose of hydrophobicity, charge control, and the like. It is also possible to use a treating agent such as a coupling agent, another organosilicon compound or an organotitanium compound alone or in combination.

In order to maintain a high charge amount and achieve a low consumption and a high transfer rate, it is more preferable that the inorganic fine powder is treated with at least a silicone oil.

In order to improve transferability and / or cleaning performance, it is also a preferable embodiment to further add inorganic or organic particles having a primary particle diameter of 50 nm or more (preferably having a specific surface area of less than 30 m ² / g). It is.
As the spherical particles, spherical silica particles, spherical polymethylsilsesquioxane particles, and spherical resin particles are preferably used.

The toner used in the present invention may further contain other additives within a range that does not cause a substantial adverse effect, for example, lubricant powders such as Teflon powder, zinc stearate powder and polyvinylidene fluoride powder; Abrasives such as powder, silicon carbide powder and strontium titanate powder; fluidity imparting agents such as acid value titanium powder and acid value aluminum powder; anti-caking agents; such as carbon black powder, zinc oxide powder and acid value tin powder. A conductivity imparting agent;
Organic fine particles of opposite polarity; and inorganic fine particles can also be used in small amounts as a developing property improver.

In order to produce the toner particles used in the present invention, in addition to the above-described polymerization method, for example, a binder resin, an azo-based iron complex compound, carbon black, and a release agent may be added to a pressure kneader or an extruder. Or, after uniformly dispersing using a media disperser, colliding with a target mechanically or under a jet stream, finely pulverizing to a desired toner particle size, and further subjecting to a classification process to sharpen the particle size distribution to obtain a toner. A method of producing a toner by a so-called pulverization method; a method of atomizing a molten mixture into air using a disk or a multi-fluid nozzle described in JP-B-56-13945 to obtain a spherical toner; A dispersion polymerization method in which a toner obtained by dissolving a polymer is directly produced by polymerization of a polymerizable monomer using an organic solvent in which an insoluble polymer is obtained; or directly in the presence of a water-soluble polar polymerization initiator. Emulsion polymerization method as typified by soap-free polymerization method of generating a combined toner; and the like.

In the present invention, it is preferable that the surface of the photoreceptor is provided with a releasability, and the contact angle of water on the surface of the photoreceptor is preferably 85 degrees or more. More preferably, the contact angle of water on the surface of the photoreceptor is 90 degrees or more.

The fact that the photosensitive member surface has a high contact angle
This indicates that the photoreceptor surface has high releasability. With this effect, the amount of toner remaining after transfer can be significantly reduced, greatly reducing the load in the cleaning process and more reliably preventing the occurrence of defective cleaning. can do.

Further, since the surface of the photoreceptor has a high releasability, the amount of toner remaining after transfer can be remarkably reduced. Occasionally, the recovery efficiency of the transfer residual toner in the development area is also improved, and a positive ghost image is prevented.

Here, the mechanism of generation of a ghost image will be described.

The problem of light shielding by the transfer residual toner is particularly problematic when the surface of the photoconductor is repeatedly used for one transfer material, that is, the length of one circumference of the photoconductor is longer than the length of the transfer material in the traveling direction. If the transfer residual toner is short, the charge, exposure and development must be performed in a state where the transfer residual toner is present on the photoreceptor. Therefore, the potential on the surface of the photoreceptor where the transfer residual toner exists is not sufficiently reduced and the development contrast is insufficient. Therefore, the reversal development appears on the image as a negative ghost having a lower density than the surroundings.

On the other hand, if the cleaning effect of the transfer residual toner is insufficient at the time of development, the toner is developed on the surface of the photoreceptor where the transfer residual toner is present, so that the density is higher than the surrounding area and a positive ghost occurs. .

With the structure of the present invention, the ghost image described above can be essentially prevented.

The image forming method of the present invention is effective when the surface of the photoreceptor is mainly composed of a polymer binder. For example, (i) a case where a protective film mainly composed of a resin is provided on an inorganic photoreceptor such as selenium or amorphous silicon; (ii) a charge transporting material and a resin as a charge transporting layer of a functionally separated organic photoreceptor. Having a surface layer having
(Iii) There is a case where the above-mentioned protective layer is further provided thereon. As means for imparting releasability to such a surface layer, a resin having a low surface energy is used for the resin constituting the film, additives for imparting water repellency and lipophilicity are added, and high releasability is provided. And dispersing the material having the above into a powder form. Is achieved by introducing a fluorine-containing group and a silicone-containing group into the structure of the resin.
, A surfactant may be added as an additive. For example, a compound containing a fluorine atom such as polytetrafluoroethylene, polyvinylidene fluoride and carbon fluoride may be used.

By these means, the contact angle of the surface of the photoreceptor with water can be made 85 degrees or more. If the contact angle of the photoreceptor surface with water is less than 85 degrees, the toner and the toner carrier are likely to deteriorate due to durability.

Of these, fluorine-containing resins such as polytetrafluoroethylene and polyvinylidene fluoride are particularly preferred.
In the present invention, when a fluorine-containing resin is used as the releasable powder as the powder, the dispersion in the outermost surface layer is preferable.

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

The amount of the powder added to the surface layer is 1 to 60% by weight, and more preferably 2 to 50% by weight, based on the total weight of the surface layer.
Is preferred. When the amount is less than 1% by weight, the residual toner of the transfer is not sufficiently reduced, the cleaning efficiency of the residual toner is not sufficient, and the ghost prevention effect is insufficient. When the amount is more than 60% by weight, the strength of the film is reduced. This is not preferable because the amount of light incident on the photosensitive member is significantly reduced. The particle size of the powder is preferably 1 μm or less, and more preferably 0.5 μm or less from the viewpoint of image quality. If it is larger than 1 μm, the line will be cut poorly due to scattering of incident light, which is not practical.

The present invention is particularly effective when the charging means is a contact charging method in which a charging member is brought into contact with a photosensitive member. That is, if there is a large amount of residual toner after cleaning, the residual toner adheres directly to the charging member in a later process, causing charging failure. Therefore, compared to corona discharge in which the charging means does not contact the photoconductor, the amount of residual toner is smaller,
It is necessary to make it hard to adhere.

One preferred embodiment of the photoreceptor 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;
Cylindrical cylinders and films of paper or plastic impregnated with conductive particles; plastic with conductive polymer;

On these conductive substrates, the adhesion of the photosensitive layer is improved, the coating property is improved, the substrate is protected, the defect is coated on the substrate,
An undercoat layer may be provided for the purpose of improving the charge injection property from the substrate and protecting the photosensitive layer against electrical breakdown.

The undercoat layer may be made of 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, Made of gelatin, polyurethane or aluminum oxide material. The thickness of the undercoat layer is usually 0.1 to 10 μm, preferably 0.1 to 3 μm.
Is good.

The charge generation layer is made of an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone pigment, a squarylium dye, a pyrylium salt, a thiopyrylium salt, a triphenylmethane dye or selenium or amorphous. An inorganic charge generating substance such as silicon is dispersed in a suitable binder and coated or formed by vapor deposition. Of these, phthalocyanine pigments are preferred for adjusting the sensitivity of the photoreceptor to a sensitivity suitable for the present invention. As the binder, a wide range of binder resins can be selected, for example, polycarbonate resin, polyester resin, polyvinyl butyral resin, polystyrene resin, acrylic resin, methacryl resin, phenol resin, silicone resin, epoxy resin, vinyl acetate resin. No. The amount of the binder contained in the charge generation layer is 80% by weight or less, preferably 0% by weight.
The content is preferably up to 40% by weight. The thickness of the charge generation layer is 5
μm or less, particularly preferably 0.05 to 2 μm.

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 transporting layer is formed by dissolving a charge transporting substance in a solvent together with a binder resin if necessary, and applying the solution. The film thickness is generally 5 to 40 μm. Examples of charge transport layer materials include polycyclic aromatic compounds such as biphenylene, anthracene, pyrene and phenanthrene in the main chain or side chain; nitrogen-containing cyclic compounds such as indole, carbazole, oxadiazole and pyrazoline; hydrazone compounds; styryl compounds Selenium; selenium-tellurium; amorphous silicon; cadmium sulfide.

Examples of the binder resin for decomposing these charge transport materials include polycarbonate resin, polyester resin,
Resins such as polymethacrylate, polystyrene resin, acrylic resin and polyamide resin; organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene.

A protective layer may be provided as a surface layer. As the resin of the protective layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or a curing agent of these resins is used alone or in combination of two or more.

The conductive fine particles may be dispersed in the resin of the protective layer. Examples of the conductive fine particles include metals and metal oxides. Preferably, zinc oxide, titanium oxide,
There are ultrafine particles of tin oxide, antimony oxide, indium oxide, bismuth oxide, tin oxide-coated titanium oxide, tin-coated indium oxide, antimony-coated tin oxide, or zirconium oxide. These may be used alone or as a mixture of two or more. In general, when particles are dispersed in the protective layer, it is necessary that the particle size of the particles is smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles, and the conductivity dispersed in the protective layer The particle size of the insulating particles is preferably 0.5 μm or less. The content in the protective layer is preferably from 2 to 90% by weight, more preferably from 5 to 80% by weight, based on the total weight of the protective layer. The layer thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 1 to 7 μm.

The surface layer can be applied by spray coating, beam coating or permeation (dipping) coating of the resin dispersion.

The condition of the developing step used in the present invention is that the toner layer on the toner carrier is in contact with the surface of the photoreceptor.

In the case of a one-component developer, a method is also used in which an elastic roller is used as a toner carrier, and a toner layer formed by coating the surface of the elastic roller with toner is brought into contact with the surface of the photoreceptor. At this time, the toner may be either magnetic or non-magnetic, and it is important that the toner layer is in contact with the surface of the photoreceptor. The toner carrier is substantially in contact with the photoconductor surface, which means that the toner carrier is in contact with the photoconductor surface when the toner layer is removed from the toner carrier. At this time, in order to obtain an image without an edge effect by an electric field acting between the photoconductor surface and the elastic roller facing the photoconductor surface via the toner layer, the surface of the elastic roller or the vicinity thereof has a potential. It is necessary to have an electric field between the photoreceptor surface and the toner carrying surface. For this reason, it is also possible to use a method in which the elastic rubber of the elastic roller is resistance-controlled in the medium resistance region to keep the electric field while preventing conduction with the photoreceptor surface, or to provide a thin insulating layer on the surface layer of the conductive roller. . In addition, a conductive resin sleeve whose outer surface facing the photoconductor surface of the conductive roller is coated with an insulating material, or a configuration in which a conductive layer is provided on the inner surface of the insulating sleeve that does not face the photoconductor surface are also possible. It is. It is also possible to adopt a configuration in which a rigid roller is used as the toner carrier and the photosensitive member is made flexible such as a belt. The electric resistance of the developing roller as the toner carrier is preferably in the range of 10 ² to 10 ⁹ Ω.

The electric resistance of the developing roller is measured by the following method. That is, as shown in FIG. 9, the aluminum roller 102 having a diameter of 16 mm and the developing roller 101 are brought into contact with a contact load of 4.9 N (500 g).
02 is rotated at 2 rps. Next, the developing roller 101
Is applied with a DC voltage of V ₁ = 400V.

[0209] The variable resistor R is disposed on the ground side, while adjusting the resistance value of the variable resistor R in accordance with the developing roller 101, to measure the voltage V ₂ at both ends thereof, by calculating the current value, developing The electric resistance of the roller 101 is calculated.

When the one-component contact developing method is used, the surface of the developing roller carrying the toner may be rotated in the same direction as the moving direction of the photosensitive member surface, or may be rotated in the opposite direction. When the rotation is in the same direction, it is desirable that the peripheral speed ratio is higher than 100% with respect to the peripheral speed of the photoconductor.
If it is less than 100%, the image quality is poor. The higher the peripheral speed ratio, the greater the amount of toner supplied to the development site, the more frequently the toner is attached to and detached from the latent image, and unnecessary portions are scraped off and added to necessary portions repeatedly. As a result, an image faithful to the latent image can be obtained. Specifically, the moving speed of the surface of the toner carrier is preferably 1.05 to 3.0 times the moving speed of the surface of the photoconductor.

Hereinafter, the transfer step applicable to the image forming method of the present invention will be specifically described.

In the transfer step, it is preferable to use a contact transfer method in which a toner image is electrostatically transferred to a transfer material while a transfer means is in contact with the surface of the photoreceptor via a transfer material.
The contact pressure of the transfer means against the photoreceptor surface is preferably at least a linear pressure of 2.9 N / m (3 g / cm), and more preferably 9.8 to 490 N / m (10 to 490 N / m).
(500 g / cm). If the linear pressure as the contact pressure is less than 2.9 N / m (3 g / cm), it is not preferable because the transfer of the transfer material and the occurrence of transfer failure tend to occur. If the contact pressure is too high, the surface of the photoconductor is deteriorated and toner adheres, and as a result, the toner is fused on the surface of the photoconductor.

As the transfer means in the contact transfer step,
An apparatus having a transfer roller or a transfer belt is used. The transfer roller has at least a core metal and a conductive elastic layer covering the core metal, and the conductive elastic layer has a volume resistance of about 10 ⁶ to 10 ¹⁰ Ωcm such as urethane or EPDM in which conductive fine particles such as carbon are dispersed. Made of elastic material.

The present invention is particularly effectively used in an image forming apparatus in which the surface of a photoreceptor is an organic compound. That is, when the organic compound forms the surface layer of the photoreceptor, the transferability is higher because the adhesiveness with the binder resin contained in the toner particles is higher than other photoreceptors using an inorganic material. It has a technical problem that it tends to decrease. Therefore, the effect of high transferability by the toner used in the present invention becomes more remarkable.

Examples of the surface material of the photoreceptor according to the present invention include silicone resin, vinylidene chloride, ethylene-vinyl chloride, styrene-acrylonitrile, styrene-methyl methacrylate, styrene, polyethylene terephthalate, and polycarbonate. There is no limitation, and other monomers or copolymers and blends of the above-mentioned binder resins can be used.

In the present invention, the present invention is particularly effectively used for an image forming apparatus having a small-diameter photosensitive drum having a diameter of 50 mm or less. That is, in the case of a small-diameter photosensitive drum, pressure concentration at the contact portion of the contact member at the same linear pressure is likely to occur. Although it is considered that the same phenomenon occurs in the belt photoconductor, the present invention is also effective for an image forming apparatus using a photoconductor belt having a radius of curvature of 25 mm or less at the contact portion.

Further, in the present invention, it is desirable to control the total charge amount of the toner when developing the toner. Therefore, the surface of the toner carrier according to the present invention is preferably covered with a resin layer in which conductive fine particles and / or a lubricant are dispersed.

As a charging method, a known corona charging method called a corotron or a scorotron is used, and a method using a pin electrode can also be used. Further, a contact charging method in which a charging member is brought into contact with the surface of the photoreceptor to perform charging can also be used.

In the present invention, it is particularly effective when the charging means is a contact charging method in which the charging member is brought into contact with the surface of the photosensitive member. That is, compared to non-contact corona discharge in which the charging means does not come into contact with the photoreceptor surface, the contact charging method is liable to cause deterioration of the photoreceptor surface, and from the viewpoint of durability, an increase in untransferred toner due to a decrease in transferability. There is a technical problem that cleaning performance is in a severe direction. Therefore, the effect of the high transferability used in the present invention becomes more remarkable.

As a preferable process condition when a charging roller is used as a contact charging member, the contact pressure of the charging roller is 4.9 to 490 N / m (5 to 500 g / c
m), more preferably 9.8-392 N / m (10-4
Further, a DC voltage is preferably applied in order to make the polarity of the transfer residual toner the same as the charge polarity of the photoreceptor and to facilitate collection during development. When a superimposed one is used, 2 × Vth
(V) It is preferable that an AC voltage having a peak-to-peak voltage less than [Vth; discharge start voltage (V) in DC application] is superimposed on the DC voltage.

Other contact charging members include a method using a charging blade and a method using a conductive brush. These contact charging means have the effects of eliminating the need for high voltage and reducing the generation of ozone.

In the case where the contact charging member is a roller or a blade, a conductive metal such as iron, copper or stainless steel; a carbon dispersed resin; a metal or a metal oxide dispersed resin is used as the conductive substrate. In the case of a blade, a rod shape or a plate shape can be used. As the configuration of the elastic roller, one having an elastic layer, a conductive layer, and a low resistance layer provided on a conductive substrate is used.

As the elastic layer, a sponge made of rubber or rubber such as chloroprene rubber, isoprene rubber, EPDM rubber, polyurethane rubber, epoxy rubber and butyl rubber; styrene-butadiene thermoplastic elastomer, polyurethane thermoplastic elastomer, polyester It can be formed of a thermoplastic elastomer such as a thermoplastic thermoplastic elastomer and an ethylene-vinyl acetate thermoplastic elastomer.

The conductive layer preferably has a volume resistivity of 10 ⁷
Ω · cm or less, more preferably 10 ¹ to 10 ⁶ Ω · cm
Good to be. As the conductive layer, for example, a metal deposition film, a conductive particle dispersed resin, a conductive resin, or the like is used.
Specific examples include vapor-deposited films of conductive metals such as aluminum, indium, nickel, copper and iron; conductive particles such as carbon, aluminum, nickel and titanium oxide formed of urethane, polyester, vinyl acetate-vinyl chloride copolymer and Conductive particle-dispersed resin dispersed in a resin such as polymethyl methacrylate; and conductive resins such as quaternary ammonium salt-containing polymethyl methacrylate, polyvinyl aniline, polyvinyl pyrrole, polydiacetylene and polyethylene imine.

The resistive layer has a volume resistivity of 10 ⁶ to 10 ¹² Ω.
・ It is good to be a layer of cm. As the resistance layer, a semiconductive resin or a conductive particle dispersed insulating resin can be used. As the semiconductive resin, for example, ethyl cellulose, nitrocellulose, methoxymethylated nylon, ethoxymethylated nylon, copolymerized nylon, polyvinyl hydrin or casein is used. As the conductive particle-dispersed resin, for example, a small amount of conductive particles such as carbon, aluminum, indium oxide, and titanium oxide are dispersed in an insulating resin such as urethane, polyester, vinyl acetate-vinyl chloride copolymer, and polymethyl methacrylate. Dispersed materials may be mentioned.

As the conductive brush as the contact charging member, a brush whose resistance is adjusted by dispersing a conductive material in generally used fibers is used. As the fibers, generally known fibers can be used, and examples thereof include nylon, acrylic, rayon, polycarbonate, and polyester. As the conductive material, generally known conductive materials can be used, for example, conductive metals such as copper, nickel, iron, aluminum, gold and silver; iron oxide, zinc oxide,
Oxides of conductive metals such as tin oxide, antimony oxide and titanium oxide; and conductive powders such as carbon black. In addition, these conductive materials may be subjected to a surface treatment for the purpose of hydrophobicity and resistance adjustment as required. At the time of use, it is selected and used in consideration of dispersibility with fibers and productivity.

The conductive brush may have a fiber thickness of 1 to 20 denier (fiber diameter of about 10 to 500 μm),
The brush fibers preferably have a length of 1 to 15 mm and a brush density of 10,000 to 300,000 per square inch (about 1.5 × 10 ^{7 to} 4.5 × 10 ⁸ per square meter). .

The image forming method of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a diagram schematically showing an image forming apparatus having a process cartridge as an example of an embodiment of the image forming method of the present invention.

The photosensitive member 36 is charged by the charging roller 31 serving as a contact charging means, and the image portion is exposed to laser light 40 to form an electrostatic latent image. The toner 30 stored in the developing device 32 is applied to the toner application roller 35 and the application blade 3.
3 is applied onto the toner carrier 34, and the toner carrier 3
The toner image on the photoconductor 36 is formed by bringing the toner layer on the photoconductor 4 into contact with the surface of the photoconductor 36 and developing the electrostatic latent image on the photoconductor 36 by a reversal development method. At least a DC bias is applied to the toner carrier 34 by a bias applying unit 41. The toner image on the photoreceptor 36 is transferred onto a recording material 38 as a transferred transfer material by a bias applying unit 42.
The toner image transferred by the transfer roller 37, which is a transfer unit to which a bias is applied, and transferred onto the recording material is fixed by the heat and pressure fixing unit 43 having a heating roller and a pressure roller.

In the image forming apparatus, the blade-shaped cleaning member 3 which comes into contact with the surface of the photoreceptor 36 between the transfer section by the transfer roller 37 and the charging section by the charging roller 31 is used.
9. The transfer residual toner on the tourist spot 36 after the transfer process is scraped off by the cleaning member 39 and collected by the cleaner. The photoreceptor 36 from which the transfer residual toner has been removed is charged again by the charging roller 31, and after the charging, an electrostatic latent image is formed by exposure to the laser light 40. The electrostatic latent image on the photoconductor 36 is developed with the toner on the toner carrier 34. The toner image on the photoconductor 36 after the development process is transferred by the transfer roller 37 onto the conveyed recording material 38. Photoconductor 36 after transfer process
After the transfer member is removed by the cleaning member, the toner is charged again by the charging roller 31, and the same process is repeatedly performed thereafter.

FIG. 2 shows another example of the image forming apparatus capable of smoothly removing the toner contributed to the development from the developing sleeve in addition to supplying the toner to the developing sleeve as the toner carrier. Show.

In FIG. 2, reference numeral 1 denotes a photosensitive drum, around which a primary charging roller 2 as contact charging means, a developing device 8 as developing means, a transfer charging roller 21 as contact and transfer means, and a register roller 19 are provided. Have been. Then, the photosensitive drum 1 is, for example, −
It is charged to 700V. The applied voltage by the bias applying means 5 is, for example, a DC voltage of -1350V. And
The laser beam 7 is applied to the photosensitive drum 1 by the laser generator 6.
And a digital electrostatic latent image is formed. The electrostatic latent image on the photosensitive drum 1 is developed by the non-magnetic one-component toner 15 by the developing device 8, and a bias voltage is applied to the electrostatic latent image by a bias applying unit 24 which is in contact with the photosensitive drum 1 via a recording material 20 as a transfer material. The image is transferred onto the recording material 20 by the transfer roller 21 being applied. The recording material 20 on which the toner image 26 is placed is conveyed by the conveyor belt 25 to a heating and pressing fixing device 27 having a heating roller 38 and a pressing roller 29 and is fixed on the recording material 20. 82
Is a cleaner having a cleaning member 81,
The transfer residual toner on the photosensitive drum after the transfer process is scraped off by the cleaning member 81 and collected by the cleaner 82.

The charging roller 2 basically has a core 4 in the center and a conductive elastic layer 3 forming the outer periphery thereof.

As shown in FIGS. 3 and 4, the developing device 8 contacts the photosensitive drum 1 with the toner layer on the developing sleeve 9 as a toner carrier, and applies a bias to the core 10 by the bias applying means 18. Further, a developing sleeve as a toner carrier including an elastic roller 9 having an elastic layer 11 is provided. A toner application roller 13 having a core metal 13 to which a bias is applied by a bias applying unit 17 and an elastic layer 14 is provided in the developing device 8. A toner regulating blade 16 is provided as a member for regulating the amount of toner attached to and transported to the developing sleeve 9, and the amount of toner (toner layer) transported to the developing area by the contact pressure of the toner regulating blade 16 against the developing sleeve 9. Thickness) is controlled.
In the developing area, at least a DC developing bias is applied to the developing sleeve 9, and the toner layer on the developing sleeve contacts the surface of the photosensitive drum 1, and the photosensitive drum 1 according to the electrostatic latent image.
Transfers upward to form a toner image.

When the light part potential of the photosensitive drum 1 is 0 to 250 V and the dark part potential is 300 to 1000 V, the supply bias voltage applied by the bias applying means 17 is 100 to 900 V and the bias applying means 18 Is preferably 100 to 900 V. Further, the supply bias voltage applied by the bias applying means 17 is
8 in absolute value from the developing bias voltage applied by 8
A larger value of 0 to 400 V is preferable because the supply of the non-magnetic toner 15 to the developing sleeve 9 and the stripping of the non-magnetic toner from the developing sleeve 9 are performed smoothly.

With respect to the rotation direction of the developing sleeve 9, the surfaces of the toner application rollers 12 move in the counter direction as indicated by the arrows (the rotation direction is the same direction).
It is preferable in terms of supplying and stripping non-magnetic toner.

The image forming apparatus shown in FIG. 1 or 2 employs an image forming method of a type in which a toner image formed on an image carrier is directly transferred to a recording material without using an intermediate transfer member. is there.

Next, the toner image formed on the image carrier is subjected to a first transfer onto an intermediate transfer member as a transfer material, and the toner image transferred onto the intermediate transfer member is subjected to a second transfer onto a recording material. An image forming method for performing the following will be described using the image forming apparatus shown in FIG.

In FIG. 4, a charging roller 52, which rotates in contact with a photosensitive drum 51 as an image carrier, gives a surface potential on the photosensitive drum 51, and forms an electrostatic latent image by exposure means 53. The electrostatic latent image is developed by four color toners of magenta toner, cyan toner, yellow toner, and black toner by developing units 54, 55, 56, and 57 of a one-component contact developing system to form a full-color toner image. At the time of development, each of the developing devices 54, 55,
When one of 56 and 57 moves, the toner carrier of the developing device comes into contact with the surface of the photosensitive drum 51 to perform development, and after the development, the developing device moves to the original position again. The toner carrier is separated from the surface of the photosensitive drum 51. This operation is repeated four times for each developing device. The toner image is transferred onto the intermediate transfer member 58 for each color, and is repeated a plurality of times to form a multiple toner image.

As the intermediate transfer member 58, a drum-shaped member is used, and a holding member is stretched on the outer peripheral surface, and a conductive member such as carbon black, zinc oxide, tin oxide,
What has an elastic layer (for example, nitrile butadiene rubber) in which silicon carbide or titanium oxide is sufficiently dispersed is used. A belt-shaped intermediate transfer member may be used.

The hardness of the intermediate transfer member 58 formed on the surface of the supporting member 59 is 10 to 50 degrees (JIS K-6301).
In the case of a transfer belt, in the case of a transfer belt, it is preferable that the transfer portion to a transfer material (recording material) is formed of a support member having an elastic layer 150 having this hardness.

In the transfer from the photosensitive drum 51 to the intermediate transfer member 58, a transfer current is obtained by applying a bias from a power source 66 to a metal core 59 as a support member of the intermediate transfer member 58, and the transfer of the toner image is performed. Done. Corona discharge or roller charging from the back side of the holding member or the belt may be used.

The multi-toner image on the intermediate transfer member 58 is collectively transferred onto the recording material S by the transfer means 61. As the transfer unit, a contact electrostatic transfer unit using a corona charger, a transfer roller, or a transfer belt is used.

The recording material S having a toner image is formed by the heating element 6
A fixing nip portion between the fixing roller 68 and the pressure roller 69 of the heating and fixing device 70 having a fixing roller 68 as a fixing member having the fixing member 7 therein and a pressure roller 69 pressing the fixing roller 68 is formed. As the S passes, the toner image is fixed on the recording material S.

The toner containing carbon black used in the present invention is used as a black toner in one of the developing units 54, 55, 56 and 57 of the above-described image forming apparatus, and the remaining toner is used as the black toner. The three developing units use three chromatic color toners. The black toner used in the present invention is used for forming a color image or a full-color image in combination with a chromatic color toner, or for forming a monochrome image using only the black toner.

In FIG. 4, reference numeral 63 denotes a cleaner (first cleaning means) having a cleaning member 62 for removing the toner remaining on the surface of the photosensitive drum 51 after the first transfer. Is
It is in contact with the surface of the photosensitive drum 51. 65 is the second
Is a cleaner (second cleaning means) having a cleaning member 64 for removing toner remaining on the surface of the intermediate transfer member 58 after the transfer of the toner image.

[0248]

Hereinafter, the present invention will be described in more detail with reference to specific production methods, examples, and comparative examples of a toner and a photosensitive drum.

The carbon blacks shown in Table 1 were prepared.

[0250]

[Table 1]

(Preparation of Masterbatch Dispersions 1 to 19)
As shown in Table 2 below, carbon black al and a dispersant were added to 2000 g of the styrene monomer, respectively.
Was added to Attritor 1S (manufactured by Mitsui Mining Co., Ltd.), and 180 mm at a temperature of 25 ° C. at 200 rpm using 2 mm zirconia beads.
For 1 minute, and a masterbatch dispersion liquid 1 to 19 in which carbon black and a dispersant are dispersed in a styrene monomer.
Was prepared. Table 2 shows the viscosities of the obtained master batch dispersions 1 to 19.

[0252]

[Table 2]

[0253]

[Outside 9]

[Production Example A of Polymerized Toner] In a two-liter four-necked flask, 700 g of ion-exchanged water was added with 0.1 M-
After 500 g of an aqueous solution of Na ₃ PO ₄ was charged and heated to 60 ° C., the mixture was stirred at 12000 rpm using a high-speed stirrer TK homomixer (manufactured by Tokushu Kika Kogyo). To this, 76 g of a 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing a minute water-insoluble dispersion stabilizer.

(Pre-dispersion) Master batch dispersion 11
00 g (monomer) styrene 66 g n-butyl acrylate (n-BA) 34 g (polar resin) saturated polyester (condensation product of propoxylated bisphenol and terephthalic acid, acid value 14, peak molecular weight 7,000) 8 g (release agent) ester wax (Melting point 65 ° C) 30g

The above formulation was heated to 60 ° C. and dissolved uniformly.
Dispersed. 10 g of a polymerization initiator 2,2'-azobis (2,4-dimethylvaleronitrile) was dissolved therein,
A polymerizable monomer composition was prepared.

The polymerizable monomer composition was put into the aqueous medium, and the mixture was stirred at 12,000 rpm for 10 minutes with a TK homomixer at 60 ° C. in an N ₂ atmosphere. Granulated. Thereafter, the mixture was reacted at the same temperature for 5 hours while stirring with a paddle stirring blade (50 rpm), then heated to 80 ° C., and further reacted for 5 hours. After the completion of the polymerization reaction, the remaining monomers are distilled off under reduced pressure, and after cooling, hydrochloric acid is added to dissolve the calcium phosphate, followed by filtration, washing with water and drying, and sharp black polymer particles having a weight average particle size of about 6.9 μm. (Black toner particles).

To 100 parts by weight of the obtained black toner particles, 1.6 parts by weight of hydrophobic silica having a specific surface area of 140 m ² / g by the BET method was externally added.
I got Table 4 shows the physical properties of the obtained toner.

[Production Examples BF of Polymerized Toner] A master batch dispersion liquid 2-6 in which the addition amount of the azo-based iron complex compound (1) was changed as shown in Table 2 was used, except that:
In the same manner as in [Production Example A of Polymerized Toner],
F was produced. Table 4 shows the physical properties of the obtained toner.

[Production Example G of Polymerized Toner] The same as [Production Example A of Polymerized Toner] except that Masterbatch Dispersion 7 using carbon black b shown in Table 1 instead of carbon black a was used. Thus, a polymerized toner G was prepared. Table 4 shows the physical properties of the obtained toner.

[Production Examples H and I of Polymerized Toner] 0.1M-
By adjusting the amounts of the aqueous solution of Na ₃ PO _{4 and the} aqueous solution of 1.0 M CaCl ₂ , polymerized toners H and I were prepared in the same manner as in [Production Example G of Polymerized Toner].
Table 4 shows the physical properties of the obtained toner.

[Production Examples J to R of Polymerized Toner] Carbon blacks c to l shown in Table 1 in place of carbon black a
Polymerized toners J to R were prepared in the same manner as in [Production Example A of Polymerized Toner], except that Masterbatch Dispersion Liquid 8-17 using No. was used. The master batch dispersion 1
In No. 6, the viscosity was too high to take out, and no toner could be obtained. Table 4 shows the physical properties of the obtained toner.

[Production Examples of Polymerized Toner S, T] Master batch dispersions 18 and 19 using an azo chromium compound and a zinc compound of ditertiary butyl salicylic acid instead of the azo iron compound (1) were used. Except for the above, polymerized toners S and T were produced in the same manner as in [Production Example A of Polymerized Toner]. Table 4 shows the physical properties of the obtained toner.

[Production Examples of Polymerized Toners U and V] Polymerized toners were prepared in the same manner as in [Production Example A of Polymerized Toner] except that the formulation of the polymerizable monomer composition was changed as shown in Table 3. U and V were prepared. Table 4 shows the physical properties of the obtained toner.

[Production Examples of Polymerized Toners W to Z] Except that part of the styrene monomer contained in the polymerizable monomer composition was changed to divinylbenzene, Similarly, polymerized toners W to Z were produced.

Table 4 shows the physical properties of the obtained toner.

[Production Examples AA and BB of Polymerized Toner] Polymerized toner AA was prepared in the same manner as in [Production Example A of Polymerized Toner] except that the amount of the polymerization initiator added and the temperature conditions during the polymerization reaction were changed. , BB. Table 4 shows the physical properties of the obtained toner.

Table 3 shows the formulations of the polymerized toners A to Z, AA and BB.

[0269]

[Table 3]

[0270]

[Table 4]

(Photoreceptor Production Example 1) Diameter 30 mm, length 2
A 54 mm aluminum cylinder was used as a substrate. On this substrate, layers having the following structures were sequentially laminated by dip coating to prepare a photoreceptor 1.

(1) Conductive coating layer: mainly composed of tin oxide and titanium oxide powder dispersed in a phenol resin. The thickness is 15 μm.

(2) Undercoat layer: mainly composed of modified nylon and copolymerized nylon. The film thickness is 0.6 μm.

(3) Charge generation layer: mainly composed of an azo pigment having absorption in a long wavelength region dispersed in butyral resin. The film thickness is 0.6 μm.

(4) Charge transporting layer: mainly composed of a hole transporting triphenylamine compound dissolved in a polycarbonate resin (molecular weight 20,000 according to Ostwald viscosity method) at a weight ratio of 8:10, and further comprising polytetrafluoroethylene. Powder (particle size: 0.2 μm) was added at 10% by weight based on the total solid content, and dispersed uniformly. 25 μm thick.

The contact angle of the surface of the obtained photosensitive member 1 with water was 95 degrees.

The contact angle was measured using pure water, and the apparatus used was a contact angle meter CA-DS, Kyowa Interface Science Co., Ltd.

(Photoreceptor Production Example 2) Except that polytetrafluoroethylene powder (particle size: 0.2 μm) was not added to the charge transport layer, the film thickness was 25 μm in the same manner as in Photoreceptor Production Example 1.
m of the charge transport layer was formed, and a photoreceptor 2 was prepared.

The contact angle of the surface of the obtained photoreceptor 2 with water was 79 degrees.

<Embodiment 1> Image forming apparatus 600d
pi laser beam printer (Canon: LBP-
8 Mark IV) was prepared. This apparatus was modified to print 12 sheets per minute on LTR size paper at a process speed of 80 mm / s (variable toner carrier speed). FIG.
As shown in (1), this device uniformly charges the photoconductor 36 (30φ) using the charging roller 32 to which DC and AC components are applied. At this time, the DC component is controlled to a constant voltage, and the AC component is controlled to a constant current. After charging, laser light 4
Forming an electrostatic latent image by exposing the image portion with 0,
After the toner image is formed as a visible image by the toner 30, the toner image is transferred to the transfer material 38 by the transfer roller 37 to which a voltage is applied.

Next, the developing container 32 in the process cartridge was modified. A medium resistance rubber roller (16φ) made of silicone rubber in which resistance is adjusted by dispersing carbon black instead of an aluminum sleeve containing a magnet serving as a toner supply body is used as the toner carrier 34.
It came into contact with the photoconductor 36. The moving direction and the rotational peripheral speed of the surface of the toner carrier 34 are the same in the contact portion with the photoconductor surface, and the toner carrier 34 is driven to be 150% of the rotational speed of the photoconductor. That is, the peripheral speed of the toner carrier is 120
mm / s, and the relative speed to the photoreceptor surface is 80 m
m / s.

As a means for applying the toner to the toner carrier, an application roller 35 was provided at the developing portion, and was brought into contact with the toner carrier. At the contact portion, the toner was applied onto the toner carrier by rotating the application roller 35 so that the moving direction of the surface of the applying roller 35 moved in the opposite direction to the moving direction of the toner carrier. Furthermore, a resin-coated stainless steel blade 33 was attached to control the coat layer of the toner on the toner carrier. As the cleaning member 39, a blade made of urethane rubber is used.

As the photoconductor, photoconductor 1 manufactured in (Photoconductor Production Example 1) was used, and toner A was used as the toner. Process conditions were set so as to satisfy the following development conditions.

Photoconductor dark area potential -700V Photoconductor light area potential -150V Developing bias -450V (DC component only)

A continuous image output test was performed on 1,000 sheets while supplying toner, and the image was evaluated. The image density, spatter suppression, fog suppression and transferability were good, and no cleaning failure occurred. The same image quality was obtained.
Both the photoreceptor and the developing roller were observed, but they did not need to be replaced without fusing.

(Evaluation Method) (1) Image Density A square solid black image having a side of 5 mm is formed, and Macb
The image density of the solid black image was measured using an image density measuring device RD918 manufactured by eth.

(2) Scattering Scattering evaluation is a splattering evaluation of fine lines related to the image quality of a graphical image as described below. A 1-dot line image that is more easily scattered than a character line is printed out. At this time, the reproducibility of the line and the scattering of toner around the line were visually evaluated.

A: Almost no scattering occurs, showing good line reproducibility. B: Slight scattering is observed. C: Scattering is observed, but there is little influence on line reproducibility. D: Remarkable scattering is observed, and lines are observed. Poor reproducibility

(3) Transferability The transferability was determined based on the Macbeth density of a tape obtained by taping off the transfer residual toner on the photoreceptor at the time of forming a solid black image with a Mylar tape and affixing the stripped Mylar tape on paper. The evaluation was made by subtracting the Macbeth density from the paper only pasted on paper. Therefore,
The smaller the value, the better the transferability.

(4) Fog Fog is caused by tapping off the untransferred toner on the photoreceptor at the time of forming a solid white image with a Mylar tape and stripping off the Mylar tape. Evaluation was made by subtracting the Macbeth density of the paper stuck on the paper. Therefore,
The smaller the value, the better the fog suppression.

(5) Resolution The resolving power was evaluated based on the reproducibility of a small dot having a diameter of 600 μm and 50 μm as shown in FIG.

A: 5 or less defects in 100 B: 6 to 10 defects in 100 C: 11 to 20 defects in 100 D: 20 or more defects in 100

(6) Matching with Roller Development After completion of the printout test, the state of fixation of the residual toner on the surface of the development roller and the effect on the printout image were visually evaluated.

A: very good (no occurrence) B: good (almost no occurrence) C: normal (there is sticking but little influence on the image) D: bad (many sticking and image unevenness occurs)

(7) Matching with Photosensitive Drum After the printout test was completed, the occurrence of scratches on the surface of the photosensitive drum and adhesion of residual toner and the effect on the printout image were visually evaluated.

A: very good (not generated) B: good (slight flaws are seen, but there is no effect on the image) C: normal (there is adhesion or flaw, but little effect on the image) D: Poor (many sticking causes vertical streak-like image defect)

(8) Matching with Fixing Device After the printout test was completed, the flaws on the surface of the fixing roller and the state of fixation of the residual toner were visually evaluated.

A: Very good (not generated) B: Good (slightly fixed, but has no effect on the image) C: Normal (There is fixed or scratched, but there is little effect on the image) D : Bad (Many sticking causes image defects)

The evaluation results are shown in Table 5.

<Example 2> An experiment was performed in the same manner as in Example 1 except for the following.

The direction of movement of the surface of the toner carrier was the same in the contact portion with the surface of the photoconductor, and the toner carrier was driven to be 200% of the peripheral speed of the photoconductor. The peripheral speed of the toner carrier is 160 mm / s, and the relative speed with respect to the photosensitive member surface is 80 mm / s.

The toner B was used and the process conditions were set so as to satisfy the following developing conditions.

Developing bias -500V (DC component only)

A durability test was performed on 1,000 sheets while supplying toner. The image density, fog suppression, and transferability were good, no cleaning failure occurred, and an image quality equivalent to the initial level was obtained. Further, both the photoreceptor and the developing roller were observed, but no replacement was required without fusing or the like.
Table 5 shows the evaluation results.

<Examples 3 to 6> Evaluations were made in the same manner as in Example 1 except that polymerized toners B to E were used as toners. As shown in Table 5, generally good results were obtained.

<Comparative Example 1> A similar test was performed as in Example 1, except that the polymerized toner F and the photoreceptor 2 of Photoreceptor Production Example 2 were used.

Process conditions were set so as to satisfy the following developing conditions.

Developing bias -350V (DC component only)

At the time of 500 sheets, cleaning failure occurred. Whenever the cleaning failure occurred, the durability was continued while cleaning the cleaning blade. When 1000 sheets were printed, white spots due to toner fusion occurred in a part of the solid black image at the photoconductor cycle.

When the photosensitive member was replaced, the white dots disappeared, but the image density did not recover to the initial level. The reproduction of the isolated dot of 50 μm was insufficient, and the scattering of the line image was conspicuous. Table 5 shows the results.

<Examples 7 to 14> Evaluations were made in the same manner as in Example 1 except that polymerized toners G and J to P were used as toners. As shown in Table 5, generally good results were obtained.

Comparative Examples 2 and 3 Evaluations were made in the same manner as in Example 1 except that polymerized toners Q and R were used as toners. As shown in Table 5, good results were not obtained because the carbon black used for the toner was not the specific carbon black in the present invention. In the case of the polymerized toner Q, remarkable image stains due to poor cleaning occurred, and in the case of the polymerized toner R, slight cleaning failure occurred at 1000 sheets, and the image density was low.

<Comparative Examples 4 and 5> Evaluations were made in the same manner as in Example 1 except that polymerized toners S and T were used as toners. As shown in Table 5, good results were not obtained because the dispersant used in the toner was not the specific azo-based iron compound in the present invention. Although the polymerized toner S was good at the beginning, the image density was lowered at 1000 sheets. Further, the polymerized toner T had a low image density and other characteristics were not sufficient.

Examples 15 to 22 Except that polymerized toners U to Z, AA and BB were used as toners,
Evaluation was performed in the same manner as in Example 1. Table 5 shows the results.

[0315]

[Table 5]

<Examples 23 to 31> Polymerized toners G to I were used as toners, and the added amount of each external additive (hydrophobic silica having a specific surface area of 140 m ² / g by the BET method) was 0.5. %, 1.8%, and 3.0%, except that the evaluation was performed in the same manner as in Example 1. As shown in Table 6, when the amount of the external additive added was 0.5%, the amount of transfer residual toner due to an increase in fog was slightly large, and when the amount was 3.0%, the fixing property was slightly inferior. I got

[0317]

[Table 6]

<Embodiment 32> In the electrophotographic apparatus used in Embodiment 1, the toner application roller 35 in the developing container 32 was used.
The first embodiment is performed in the same manner as the first embodiment, except that a single-layer sponge roller is used and a bias voltage is applied from a bias applying unit (not shown) to the toner application roller 35. An image was formed and evaluated in the same manner as described above.

During the development, the developing roller 34 was applied with only a DC component of -300 V as a developing bias voltage, and the toner application roller 35 was applied with only a DC component of -450 V as an application bias voltage.

Evaluation was performed in the same manner as in Example 1. As a result, both image density and fog suppression were stable and good, and no cleaning failure occurred, and excellent image quality was obtained. The matching with the image forming apparatus was also good.

<Example 33> The developing device 5 of the image forming apparatus shown in FIG.
7 was used to form an image.

As shown in FIG. 4, the image forming apparatus has a first
After the transfer step, as a first cleaning means for removing the toner remaining on the surface of the photoconductor, a cleaner having a cleaning member in contact with the surface of the photoconductor includes a first transfer unit and a charging unit for charging the photoconductor. Further, as a second cleaning means for removing toner remaining on the surface of the intermediate transfer member after the second transfer step, a cleaner having a cleaning member in contact with the surface of the intermediate transfer member is provided. Downstream of the second transfer portion,
Is provided downstream of the transfer section.

As the developing unit 57, the one having the configuration of the developing unit 8 shown in FIGS. 2 and 3 was used.

Medium resistance rubber roller (16φ) made of silicone rubber in which resistance is adjusted by dispersing carbon black
Is a toner carrier 9 and is in contact with the photoconductor. The moving direction and the rotational peripheral speed of the surface of the toner carrier 9 are the same in the contact portion with the photoconductor surface, and the toner carrier 9 is driven to be 150% of the rotational speed of the photoconductor. That is, the peripheral speed of the toner carrier is 120 mm / s, and the relative speed with respect to the photoconductor surface is 80 mm / s.

As means for applying toner to the toner carrier, a single-layer sponge roller was provided as the application roller 12, and was brought into contact with the toner carrier. At the contact,
The toner was applied to the toner carrier by rotating the application roller so that the surface of the application roller moved in the direction opposite to the direction of movement of the toner carrier. Further, a resin-coated stainless steel blade 16 was attached for controlling the toner coat layer on the toner carrier.

The photoreceptor 1 manufactured in (Photoreceptor Production Example 1) was used as the photoreceptor, the toner A was used as the toner, and the following developing conditions and image forming conditions were set so as to satisfy the transfer member.

Photoconductor dark area potential: -700 V Photoconductor light area potential: -150 V Development bias applied to the developing roller: -450 V (DC component only) Bias applied to the toner application roller: -300 V (DC component only) Transfer bias applied to the intermediate transfer property in the transfer step of:
300 V (DC component only) Transfer bias applied to the transfer roller in the second transfer step:
1000V (DC component only)

The toner image transferred onto the recording material under the above-described image forming conditions was heat-fixed to the recording material by the following heat fixing device.

As the heat fixing device 70, a heat roll type fixing device having no oil application function was used. At this time, both the upper roller 68 and the lower roller 69 had a surface layer made of a fluororesin, and the diameter of the roller was 55 mm. The fixing temperature was set at 140 ° C., and the nip width was set at 7 mm.

Using the image forming apparatus having the above configuration, a continuous image output test was performed on 2,000 sheets while supplying toner, and the image was evaluated. The image density, scattering suppression, fog suppression,
The transferability was good, no cleaning failure occurred, and an image quality equivalent to that of the initial stage was obtained. The photoreceptor, the developing roller, and the intermediate transfer member were observed, but they did not need to be replaced without fusing.

[0331]

According to the present invention, the combined use of the specific carbon black and the specific azo-iron complex compound of the present invention provides a good charge control effect due to good dispersion of the carbon black, and suppresses excessive charging of the azo-iron complex compound itself. Due to the synergistic effect of the charge control effect, the excellent charge controllability of the toner on the toner carrier, in which excessive charging is suppressed, provides excellent development characteristics even in contact one-component development.

Therefore, the charge amount of the developing toner on the photoreceptor can be appropriately controlled to prevent the cleaning property from being deteriorated due to the excessive charging of the transfer residual toner. The cleaning property of a toner having a high sphericity such as a removed toner is also greatly improved.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an image forming method using a contact one-component developing device, which is used as an example of an embodiment of the image forming method of the present invention.

FIG. 2 is a schematic diagram illustrating an image forming method using a contact one-component developing device, which is used as still another example of the image forming method of the present invention.

FIG. 3 is an enlarged view of a developing device of the image forming apparatus shown in FIG.

FIG. 4 is a diagram schematically illustrating an image forming apparatus using an intermediate transfer member.

FIG. 5 is an explanatory diagram of an isolated dot pattern for evaluating a resolution.

FIG. 6 is a graph showing a change in viscosity when carbon black and an azo-based iron complex compound according to the present invention are dispersed in styrene.

FIG. 7 is a graph showing the relationship between oil absorption and viscosity of carbon black when a certain amount of an azo-based iron complex compound is added and dispersed in styrene in the carbon black according to the present invention.

FIG. 8 is a schematic diagram illustrating an example of a cross section of a toner particle including a wax component.

FIG. 9 is a schematic explanatory view of a measuring device for measuring an electric resistance value of a developing roller.

[Explanation of symbols]

 REFERENCE SIGNS LIST 30 toner 31 charging roller 32 developing container 33 toner regulating blade 34 toner carrier (elastic roller) 35 toner application roller 36 photoconductor (image carrier) 37 transfer roller 38 transfer material 39 cleaning member 40 laser light (exposure) 41 bias application Means 43 Fixing device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 9/087 G03G 15/08 507E 15/02 102 15/16 103 15/08 507 9/08 346 365 15/16 103 371 374 384 (72) Inventor Satoshi Handa 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yasawa Ayaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (45)

[Claims] (A) a charging step of charging an image carrier for carrying an electrostatic latent image; (b) an exposure step of forming an electrostatic latent image on the charged image carrier by image exposure; c) developing the electrostatic latent image with the toner carried on the surface of the toner carrier to form a toner image; and (d) applying the toner image formed on the surface of the image carrier to a transfer material. A transfer step of transferring; and (e) a cleaning step of cleaning and removing toner remaining on the surface of the image carrier after the transfer step, and using the cleaned image carrier to perform the above (a) to (e). In the image forming method, the step of repeating the process of the step (a), wherein the toner layer formed by the toner carried on the surface of the toner carrier comes into contact with the surface of the image carrier, thereby completing the development of the electrostatic latent image. The toner is bound Toner particles containing at least fat, carbon black and an azo-based iron compound, and inorganic fine powder, wherein the carbon black has an average primary particle size of 25 to 80 nm, and the azo-based iron compound Is represented by the following general formula (1) [In the formula, X ₁ and X ₂ each represent a member selected from the group consisting of a hydrogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, and a halogen atom; X ₁ and X ₂ are the same or different; And m ′ represent an integer of 1 to 3, R ₁ and R ₃ represent a hydrogen atom, a C ₁ -C ₁₈ alkyl group,
C ₂ -C ₁₈ alkenyl group, sulfonamide group, mesyl group, sulfonic acid group, carboxyester group, hydroxy group, C ₁ -C ₁₈ alkoxy group, acetylamino group, benzoylamino group and halogen atom R ₁ and R ₃ are the same or different, n and n ′ represent an integer of 1 to 3, R ₂ and R ₄ represent a hydrogen atom or a nitro group, and A ⁺ represents ammonium It shows a cation selected from the group consisting of ions, hydrogen ions, sodium ions, potassium ions and mixed ions thereof. ] An image forming method comprising: 2. The carbon black has a thickness of 25 to 55 nm.
2. An average primary particle size of
2. The image forming method according to 1., 3. The carbon black is 40 to 150 ml.
The image forming method according to claim 1, wherein the image forming method has a DBP oil absorption of / 100 g. 4. The carbon black is 100 m ² / g.
4. The image forming method according to claim 1, wherein the image forming method has the following specific surface area by nitrogen adsorption and volatile matter of 2% or less. 5. The toner particles have a carbon black content of A weight% and an azo-based iron compound content of B weight%.
The image forming method according to claim 1, wherein the following condition is satisfied: 2 ≦ A / B ≦ 35. 6. The toner has a shape factor of SF-1 and SF.
6. The image forming method according to claim 1, wherein -2 satisfies the following relationship: 100 <SF-1 ≦ 160 100 <SF-2 ≦ 140. 7. The toner has a shape factor of SF-1 and SF.
The image forming method according to claim 1, wherein -2 satisfies the following relationship: 100 <SF-1 ≦ 140 100 <SF-2 ≦ 120. 8. The toner particles are produced by polymerizing a polymerizable monomer composition containing at least a polymerizable monomer, carbon black and the azo-based iron compound in an aqueous medium. The image forming method according to claim 1, wherein: 9. The toner particles polymerize a polymerizable monomer composition containing at least a polymerizable monomer, the carbon black, the azo-based iron compound, a release agent and a polar resin in an aqueous medium. The image forming method according to claim 1, wherein the image forming method is manufactured by the above method. 10. The polymerizable monomer composition is obtained by dispersing the carbon black and the azo-based iron compound in a first polymerizable monomer with at least a second polymerizable monomer. 9. A mixture prepared and adjusted.
2. The image forming method according to 1., 11. The polymerizable monomer composition is obtained by dispersing the carbon black and the azo-based iron compound in a first polymerizable monomer into at least a second polymerizable monomer. The image forming method according to claim 9, wherein the mixture is prepared by mixing with a release agent and the polar resin. 12. The toner particles contain a wax as a release agent in addition to the binder resin, the carbon black and the azo-based iron compound, and the toner particles contain a core of the release agent. The image forming method according to any one of claims 1 to 7, wherein the image forming method has a core / shell structure including a part and a shell part having a binder resin covering the surface of the core part. 13. The toner particles contain a wax as a release agent and a polar resin in addition to the binder resin, the carbon black and the azo-based iron compound. A core / shell structure having a core portion of the agent and a shell portion having a binder resin covering the surface of the core portion, and an outer shell resin layer having the polar resin is provided on the surface portion of the shell portion. The image forming method according to claim 1, wherein is formed. 14. The toner particles contain, in addition to the binder resin, the carbon black and the azo-based iron compound, 2 to 30% by weight of a wax as a release agent on a weight basis of the toner particles. The image forming method according to claim 1, wherein: 15. The toner particles contain, in addition to the binder resin, the carbon black and the azo iron compound, a wax as a release agent in an amount of 2 to 25% by weight based on the weight of the toner particles. The image forming method according to claim 1, wherein: 16. The toner particles comprise, in addition to the binder resin, the carbon black and the azo-based iron compound, 2 to 30% by weight of a wax as a release agent and 1 to 20% by weight of a polar resin. The image forming method according to any one of claims 1 to 7, wherein the toner particles are contained on a weight basis of the toner particles. 17. The toner particles have a maximum endothermic peak in a temperature range of 40 ° C. to 90 ° C. in an endothermic curve measured by DSC as a releasing agent, in addition to the binder resin, the carbon black and the azo-based iron compound. The image forming method according to any one of claims 1 to 7, further comprising a wax. 18. The resin component of the toner particles is THF.
It has a C component insoluble in (tetrahydrofuran) and a component soluble in THF, and the component soluble in THF has a molecular weight of 1,000 in a molecular weight distribution measured by gel permeation chromatogram (GPC). It has an A component of less than 2,000 and a B component of a molecular weight of 1,000,000 or more. Based on the weight of the resin component of the toner particles, the content of the A component (W _A ) and the content of the B component meets content (W _B) and the content of the C component (W _C) is the following condition _{30 ≦ W a ≦ 95 0 ≦} W B ≦ 20 0 ≦ W C ≦ 70 5 ≦ W B + W C ≦ 70 The image forming method according to any one of claims 1 to 17, wherein: 19. The resin component of the toner particles is THF.
It has a C component insoluble in (tetrahydrofuran) and a component soluble in THF, and the component soluble in THF has a molecular weight of 1,000 in a molecular weight distribution measured by gel permeation chromatogram (GPC). It has an A component of less than 2,000 and a B component of a molecular weight of 1,000,000 or more. Based on the weight of the resin component of the toner particles, the content of the A component (W _A ) and the content of the B component The content (W _B ) and the content of the C component (W _C ) satisfy the following condition: 50 ≦ W _A ≦ 901 1 ≦ W _B ≦ 201 1 ≦ W _C ≦ 70 10 ≦ W _B + W _C ≦ 50 The image forming method according to any one of claims 1 to 17, wherein: 20. The resin component of the toner particles has a THF-soluble component, and the THF-soluble component has a molecular weight distribution measured by a gel permeation chromatogram (GPC). 9000 to 1,000,000
0 and the ratio (Mw / M) of the number average molecular weight (Mn) to the weight average molecular weight (Mw) of 5 to 500.
20. The image forming method according to claim 1, wherein n) is satisfied. 21. The resin component of the toner particles has a THF-soluble component, and the THF-soluble component has a molecular weight distribution measured by a gel permeation chromatogram (GPC). 10,000-500,000
And the ratio (Mw / M) of the number average molecular weight (Mw) to the number average molecular weight (Mw) of 7 to 400 and the number average molecular weight (Mn).
20. The image forming method according to claim 1, wherein n) is satisfied. 22. The toner according to claim 1, wherein the toner satisfies an external additive covering ratio of 5 to 99% in which the surface of the toner particles is coated with the external additive having the inorganic fine powder. 22. The image forming method according to any one of 21. 23. The method according to claim 22, wherein the external additive contains fine particles selected from a group consisting of metal oxides, nitrides, carbides, metal salts, fatty acid metal salts, carbon black and silica. The image forming method as described in the above. 24. The inorganic fine powder comprises silica, alumina,
3. A fine particle selected from the group consisting of titania and their complex oxides.
3. The image forming method according to any one of 3. 25. The image forming method according to claim 1, wherein the inorganic fine powder has a specific surface area of 30 m ² / g by a BET method. 26. The image forming method according to claim 1, wherein the inorganic fine powder has a specific surface area of 50 to 400 m ² / g by a BET method. 27. The image according to claim 1, wherein the inorganic fine powder is contained in an amount of 0.1 to 8 parts by weight based on 100 parts by weight of the toner and the toner particles. Forming method. 28. The image forming method according to claim 1, wherein said inorganic fine powder is treated with at least silicone oil. 29. The image bearing member according to claim 1, wherein the image bearing member is made of an electrophotographic photoreceptor, and the surface of the photoreceptor has a contact angle with water of 85 degrees or more. An image forming method according to any one of the above. 30. The image forming method according to claim 29, wherein a surface layer in which a compound powder containing a fluorine atom is dispersed in a resin is formed on the surface of the photoreceptor. 31. The compound powder containing a fluorine atom,
31. The image forming method according to claim 30, comprising a fluororesin powder. 32. In the developing step, the moving direction of the surface of the toner carrier in the developing area is set to the same direction as the moving direction of the surface of the image carrier. An image forming method according to any one of the above. 33. In the developing step, the moving speed of the surface of the toner carrier in the developing area is set to be 1.05 to 3.0 times the moving speed of the surface of the image carrier. 33. The image forming method according to claim 32, wherein: 34. In the developing step, a toner layer having a regulated toner layer thickness is formed on the surface of the toner carrier by bringing a toner layer thickness regulating member into contact with the toner carried on the toner carrier. The image forming method according to any one of claims 1 to 33, wherein: 35. The toner held in a developing device, and the toner held in the developing device is supplied to the toner carrier by a toner supply member for supplying the toner to the toner carrier. 2. The method according to claim 1, wherein the supply is performed.
35. The image forming method according to any one of items 34 to 34. 36. The toner supply member is a toner application roller that is in contact with the surface of the toner carrier, and the direction of movement of the surface of the toner application roller is set in a direction opposite to the direction of movement of the surface of the toner carrier. The image forming method according to claim 35, wherein the method is performed. 37. A developing bias voltage is applied to the toner carrier during development of the electrostatic latent image, and an application bias voltage is applied to the toner applying roller when supplying toner to the toner carrier. The image forming method according to claim 36, wherein the method is performed. 38. An application bias voltage applied to the toner application roller is set to be higher in absolute value than a development bias voltage applied to the toner carrier, and the toner application roller is provided on a surface of the toner carrier. 38. The image forming method according to claim 37, wherein the toner is supplied to the toner carrier, and the toner remaining on the surface of the toner carrier after development is removed. 39. The electrostatic latent image on the image carrier has a bright portion potential of 0 to 250 V in absolute value and a dark portion potential of 30% in absolute value.
0 to 1000 V, the application bias voltage applied to the toner application roller has an absolute value of 100 to 900 V, and the development bias voltage applied to the toner carrier has an absolute value of 100 to 900 V. The coating bias voltage is
The absolute value of the developing bias voltage is set to be higher than the developing bias voltage by 10 to 400 V. The toner applying roller supplies the toner to the surface of the toner carrier, and strips off the toner remaining on the surface of the toner carrier after development. The image forming method according to claim 37, wherein: 40. In the transfer step, a transfer member to which a voltage is applied from the outside is brought into contact with the image carrier through the transfer material, so that the toner image formed on the image carrier is removed. 2. The method according to claim 1, wherein the image is transferred to a transfer material.
40. The image forming method according to any one of the above items. 41. In the transfer step, a recording material is used as the transfer material, and the toner image formed on the surface of the image carrier is transferred to the recording material, and the toner image transferred to the recording material is transferred. The image forming method according to claim 1, wherein the image is fixed on the recording material. 42. In the transfer step, a first transfer for transferring the toner image formed on the image carrier to the intermediate transfer member is performed using an intermediate transfer member as the transfer material, 2. The method according to claim 1, wherein a second transfer of transferring the toner image transferred to the transfer member to a recording material is performed, and the toner image transferred to the recording material is fixed to the recording material. 40. The image forming method according to any one of the above items. 43. The image forming apparatus according to claim 1, wherein in the charging step, the image carrier is charged by bringing a charging member to which a voltage is applied from the outside into contact with the image carrier. The image forming method according to any one of the above. 44. The charging device according to claim 43, wherein a DC voltage is externally applied to the charging member in the charging step.
2. The image forming method according to 1., 45. The image forming apparatus according to claim 43, wherein in the charging step, a DC voltage and an AC voltage less than twice the discharge starting voltage in applying the DC voltage are externally applied to the charging member. Method.