JP2023062241A - Electrophotographic image forming system - Google Patents

Abstract

To provide an electrophotographic image forming system that achieves both an improvement in wear resistance and prevention of an image memory in long-term use of an electrophotographic photoreceptor.SOLUTION: In an electrophotographic image forming system of the present invention, a toner particle contains a toner base particle, and lubricant as an external additive. The volume-based particle size distribution of the lubricant has two peaks on a small particle diameter side and a large particle diameter side. A volume-based average particle size of the lubricant having the peak on the small particle diameter side is 3.0 μm or less, and a volume-based average particle size of the lubricant having the peak on the large particle diameter side is larger than a volume-based average particle size of the toner base particles. Cleaning means has a brush roller having a plurality of pile bundles, and a cleaning blade. When a pile bundle fineness [dtex] and a pile density [KF/inch2] of the brush roller are defined as X and Y, respectively, the following formulas (1) and (2) are satisfied. Formula (1): 100≤Y≤250; formula (2): 0.7≤X/Y≤2.2.SELECTED DRAWING: Figure 3

Description

The present invention relates to electrophotographic imaging systems.
More specifically, the present invention relates to an electrophotographic image forming system that achieves both improvement in abrasion resistance and suppression of image memory in long-term use of an electrophotographic photoreceptor.

Conventionally, in an electrophotographic image forming system, a lubricant is supplied to the surface of an electrophotographic photoreceptor (hereinafter also simply referred to as a "photoreceptor") to reduce the frictional force between the surface of the photoreceptor and a cleaning blade. It has been attempted to prevent the toner for electrostatic charge image development (hereinafter also simply referred to as "toner") from slipping through and the abrasion of the photoreceptor.

As a method of supplying the lubricant to the surface of the photoreceptor, there are a method of supplying with a brush and a method of supplying the lubricant by containing it in the toner. For these reasons, many electrophotographic image forming systems employ a system in which the toner is contained and supplied. However, in the case of supplying the toner with the lubricant contained therein, image memory caused by the difference in print coverage of the image may become a problem. "Image memory" means that when a certain image chart (first type of image chart) is printed and then another image chart (second type of image chart) is printed continuously, the This is an image defect that causes image density unevenness corresponding to the printed and non-printed portions of the first type of image chart. If the print coverage difference of the image is large, the distribution of the lubricant on the photoreceptor is uneven, and accordingly the surface potential of the photoreceptor is uneven. This unevenness in the surface potential of the photosensitive member causes image memory.

Japanese Patent Application Laid-Open No. 2002-200002 discloses a technique of using a lubricant having a peak on the small particle size side and a lubricant having a peak on the large particle size side in order to prevent uneven distribution of the lubricant in a system in which the lubricant is contained in the toner and supplied. ing. In this technology, since the lubricant having a peak on the small particle size side is less likely to separate from the toner base particles, it is easily supplied to the toner application area on the photoreceptor (the area on the photoreceptor corresponding to the printed area of the image chart). , the lubricant having a peak on the large particle size side tends to separate from the toner base particles, and is easily supplied to the toner non-applied area on the photoreceptor (the area on the photoreceptor corresponding to the non-printing portion of the image chart).

Due to such an action mechanism, the technique of using both a lubricant having a peak on the small particle size side and a lubricant having a peak on the large particle size side can prevent uneven distribution of the lubricant on the photoreceptor to some extent. However, in order to more stably form high-quality images, there has been a demand for the development of an electrophotographic image forming system capable of further suppressing image memory.

JP 2014-228763 A

The present invention has been made in view of the above-mentioned problems and circumstances, and the problem to be solved is to provide an electrophotographic image forming system that achieves both improvement in wear resistance in long-term use of an electrophotographic photoreceptor and suppression of image memory. It is to be.

In order to solve the above problems, the present inventors have investigated the causes of the above problems and found that a lubricant having a peak on the small particle size side (hereinafter also referred to as a "small particle size side lubricant") is an external additive for toner particles. ) and a lubricant having a peak on the large particle size side (hereinafter also referred to as “lubricant on the large particle size side”). The present inventors have found that an electrophotographic image forming system that achieves both improved abrasion resistance and reduced image memory in long-term use of an electrophotographic photoreceptor can be provided by adjusting to .theta.
That is, the above problems related to the present invention are solved by the following means.

1. An electrophotographic imaging system for forming an image using an electrostatic image developing toner comprising toner particles, comprising:
an electrophotographic photosensitive member, charging means, exposure means, developing means, transfer means and cleaning means,
the toner particles contain toner base particles and a lubricant as an external additive;
The volume-based particle size distribution of the lubricant has two peaks on the small particle size side and the large particle size side, and the volume-based average particle size of the lubricant having the peak on the small particle size side is 3.0 μm or less. , the volume-based average particle size of the lubricant having a peak on the large particle size side is larger than the volume-based average particle size of the toner base particles;
The cleaning means has a brush roller having a plurality of pile bundles, and a cleaning blade provided downstream of the brush roller in the rotation direction of the electrophotographic photosensitive member,
An electrophotographic image forming system, wherein the following formulas (1) and (2) are satisfied, where X is the pile bundle fineness [dtex] of the brush roller and Y is the pile density [KF/inch ² ].
Formula (1): 100≤Y≤250
Formula (2): 0.7≤X/Y≤2.2

2. 2. The electrophotographic image forming system according to claim 1, wherein the electrophotographic photoreceptor has a surface protective layer containing a cured resin.

3. 3. The electrophotographic image forming system of claim 1 or 2, wherein the lubricant is particles containing zinc stearate as a main component.

4. 4. The electrophotographic image forming system according to any one of items 1 to 3, wherein a Young's modulus of the pile constituting the pile bundle is within a range of 25 to 70 cN/dtex.

According to the above-described means of the present invention, it is possible to provide an electrophotographic image forming system that achieves both an improvement in abrasion resistance in long-term use of an electrophotographic photoreceptor and a suppression of image memory.

Although the expression mechanism or action mechanism of the effects of the present invention has not been clarified, it is speculated as follows.

The electrophotographic image forming system of the present invention is characterized in that the toner particles contain a small particle size lubricant and a large particle size lubricant as external additives. When the toner particles contain a lubricant as an external additive, the lubricant is supplied onto the photoreceptor, and the abrasion resistance of the photoreceptor is improved.

Further, since the lubricant having a small particle size has a large contact area with the toner base particles, it has a large adhesive force to the toner base particles and is difficult to separate from the toner base particles. Therefore, the lubricant having a small particle size is easily supplied to the toner application area on the photoreceptor where the toner base particles move. On the other hand, lubricants with large particle diameters have a small contact area with the toner base particles, so that the Coulomb force and non-electrostatic force with the toner base particles are reduced, and the Coulomb force due to the development electric field overcomes the toner base particles. easily released from Therefore, the large-particle-size lubricant is easily supplied to the non-toner-applied area on the photoreceptor. In this way, by using a small particle size lubricant and a large particle size lubricant together, the lubricant is supplied to both the toner-applied area and the non-toned area on the photoreceptor, resulting in a print coverage difference. Even if it is large, uneven distribution of the lubricant is unlikely to occur, and image memory can be suppressed.

Also, the electrophotographic image forming system of the present invention is characterized in that the cleaning means has a brush roller having a plurality of pile bundles. The brush roller collects excess lubricant on the photoreceptor, and transfers small-diameter lubricant, which tends to exist in large amounts in the toner-applied area, to the toner-non-applied area. It has the function of diffusing the large particle size side of the lubricant to the toner application area.

Furthermore, the brush roller according to the present invention is characterized by satisfying the following formulas (1) and (2), where X is the pile bundle fineness [dtex] and Y is the pile density [KF/inch ² ]. .
Formula (1): 100≤Y≤250
Formula (2): 0.7≤X/Y≤2.2

If the brush roller does not satisfy the above conditions, the effect of recovering and diffusing the lubricant is not sufficiently exhibited, and the problem of the present invention cannot be solved. Specifically, when the pile density Y is less than 100, the rubbing force is too small, and when the pile density Y is greater than 250, the operating area per pile bundle is too small. Collection and diffusion effects are not exhibited. If X/Y is less than 0.7, the operating area per pile bundle becomes too small. As a result, the recovery/diffusion effect of the lubricant is not exhibited.

When the brush roller according to the present invention satisfies the above conditions, the movable area per pile bundle, the rubbing force, and the probability of contact between the pile and the lubricant are moderate. As a result, the recovery/diffusion effect of the lubricant is remarkably increased, and a high image memory suppressing effect is exhibited.

Due to these expression mechanisms or action mechanisms, in the electrophotographic image forming system of the present invention, it is possible to achieve both improvement in wear resistance in long-term use of the electrophotographic photoreceptor and suppression of image memory.

A diagram for explaining an example of particle size distribution of a lubricant having peaks on the small particle size side and the large particle size side. A diagram for explaining the cumulative frequency and content ratio of the particle size distribution of a lubricant having peaks on the small particle size side and the large particle size side. Schematic diagram of cleaning means Schematic diagram of image forming apparatus

The electrophotographic image forming system of the present invention is an electrophotographic image forming system for forming an image using an electrostatic charge image developing toner containing toner particles, comprising an electrophotographic photoreceptor, charging means, exposure means, developing means, Transfer means and cleaning means are provided, and the toner particles contain toner base particles and a lubricant as an external additive, and the volume-based particle size distribution of the lubricant has two peaks on the small particle size side and the large particle size side. the lubricant having a peak on the small particle size side has a volume-based average particle size of 3.0 μm or less, and the lubricant having a peak on the large particle size side has a volume-based average particle size of the toner base particles and the cleaning means comprises a brush roller having a plurality of pile bundles, and a cleaning blade provided downstream of the brush roller in the rotation direction of the electrophotographic photosensitive member, When the pile bundle fineness [dtex] of the brush roller is X and the pile density [KF/inch ² ] is Y, the above formulas (1) and (2) are satisfied.
This feature is a technical feature common to or corresponding to the following embodiments.

As an embodiment of the electrophotographic image forming system of the present invention, the electrophotographic photoreceptor preferably has a surface protective layer containing a cured resin. This can further improve the abrasion resistance of the electrophotographic photoreceptor.

As an embodiment of the electrophotographic image forming system of the present invention, it is preferable that the lubricant is particles containing zinc stearate as a main component. This is because particles containing zinc stearate as a main component have a low adhesion to the toner base particles, and easily migrate to the photoreceptor when added in a small amount.

As an embodiment of the electrophotographic image forming system of the present invention, it is preferable that the Young's modulus of the pile constituting the pile bundle is in the range of 25 to 70 cN/dtex. As a result, the rubbing force becomes appropriate, and the effect of recovering and diffusing the lubricant can be further improved.

DETAILED DESCRIPTION OF THE INVENTION The present invention, its constituent elements, and embodiments and modes for carrying out the present invention will be described in detail below. In the present application, "-" is used to mean that the numerical values before and after it are included as the lower limit and the upper limit.

<1 Overview of Electrophotographic Image Forming System>
The electrophotographic image forming system of the present invention (hereinafter also simply referred to as "image forming system") forms an image using an electrostatic charge image developing toner containing toner particles (hereinafter also simply referred to as "toner"). An electrophotographic image forming system comprising an electrophotographic photoreceptor (hereinafter also simply referred to as "photoreceptor"), charging means, exposure means, developing means, transfer means and cleaning means, wherein the toner particles are toner It contains base particles and an external additive, the external additive is at least a lubricant, the volume-based particle size distribution of the lubricant has two peaks on the small particle size side and the large particle size side, and the small particles The volume-based average particle size of the lubricant having a peak on the diameter side (hereinafter also referred to as "lubricant on the small particle size side") is 3.0 μm or less, and the lubricant having a peak on the large particle size side (hereinafter referred to as The volume-based average particle size of the toner base particles is larger than the volume-based average particle size of the toner base particles, and the cleaning means includes a brush roller having a plurality of pile bundles, and the electron and a cleaning blade provided on the downstream side of the brush roller in the rotational direction of the photoreceptor, wherein X is the pile bundle fineness [dtex] of the brush roller, and Y is the pile density [KF/inch ² ]. It is characterized by satisfying the following formulas (1) and (2).
Formula (1): 100≤Y≤250
Formula (2): 0.7≤X/Y≤2.2

In the image forming system of the present invention, the apparatus section is particularly called an "image forming apparatus". The image forming system of the present invention forms an image by using the image forming apparatus and the toner particles of the present invention.

Each configuration of the electrostatic image developing toner and the image forming apparatus will be described below.

<2 Toner for electrostatic charge image development>
The toner particles contained in the toner for electrostatic charge image development according to the present invention contain toner base particles and an external additive, and the external additive is at least a lubricant, and the volume-based particle size distribution of the lubricant is on the small particle size side. and a lubricant having two peaks on the large particle size side and a peak on the small particle size side (lubricant on the small particle size side) has a volume-based average particle size of 3.0 μm or less, and the large particle size The volume-based average particle diameter of the lubricant having a peak on the side (large-diameter-side lubricant) is larger than the volume-based average particle diameter of the toner base particles.

In the present invention, "toner base particles" constitute the base of "toner particles". The "toner base particles" contain at least a binder resin and a colorant, and may optionally contain other components such as a release agent (wax) and charge control agent. . "Toner base particles" are referred to as "toner particles" with the addition of external additives. The term "toner for electrostatic charge image development" refers to aggregates of "toner particles".

<2.1 Lubricant>
The toner particles according to the present invention contain a lubricant as an external additive.

The lubricating agent supplied onto the photoreceptor is uniformly distributed on the photoreceptor by the brush roller, and spread on the photoreceptor by the cleaning blade. The lubricant spread on the photoreceptor reduces the friction between the cleaning blade and the surface of the photoreceptor, thereby preventing toner slipping through and abrasion of the photoreceptor.

The lubricant according to the present invention has a volume-based particle size distribution having two peaks on the small particle size side and the large particle size side, and a lubricant having a peak on the small particle size side (small particle size side lubricant). The volume-based average particle size of the lubricant having a peak on the large particle size side (lubricant on the large particle size side) is equal to the volume-based average particle size of the toner base particles. characterized by being greater than

When the volume-based average particle size of the lubricant having a peak on the small particle size side is 3.0 μm or less, it adheres to the toner base particles and exhibits the function of adhering to the toner application area on the photoreceptor. Further, the volume-based average particle size of the lubricant having a peak on the small particle size side is preferably in the range of 1.0 to 3.0 μm. When the thickness is 1.0 μm or more, the adhesion amount of the lubricant does not become too small.

The volume-based average particle size of the lubricant having a peak on the large particle size side is larger than the volume-based average particle size of the toner base particles. If it is larger than the volume average particle diameter of the toner base particles, it does not adhere to the toner base particles and exhibits the function of developing the toner non-applied area independently of the toner particles. Furthermore, it is preferable that the volume-based average particle size of the lubricant having a peak on the large particle size side is in the range of 8.0 to 15.0 μm. When the thickness is 8.0 μm or more, the particles are easily released from the toner base particles and easily adhere to the toner non-applied regions. .

The volume-based particle size of the lubricant can be measured, for example, by using a flow-type particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation) after separating the toner base particles and the external additive from the toner, for example, according to the following procedure. .

5 g of toner particles and 50 mL of 0.7% sodium dodecylbenzenesulfonate aqueous solution are placed in a 100 mL beaker and dispersed by stirring at 300 rpm for 5 minutes with a magnetic stirrer "Model MS500D" (manufactured by Yamato Scientific).

After the dispersion, an ultrasonic homogenizer US-1200T (manufactured by Nippon Seiki Seisakusho) is used to apply ultrasonic vibrations to the toner dispersion for 10 minutes at a frequency of 20 kHz, an OUTPUT scale of 3, and an output of TUNING scale of 6.

The toner dispersion is separated by centrifugal separator "Model H-900" (manufactured by Kokusan Co., Ltd.) under the following conditions.
Rotor: PC-400 (radius 18.1 cm)
Rotation speed: 1200rpm (292G)
Time: 10 minutes

After centrifugation, 40 mL of supernatant is collected. At this time, a pipette is used so that the sedimented toner base particles do not enter, and the supernatant liquid is carefully collected.

The volume-based particle size of the external additive contained in the collected supernatant was measured using a flow-type particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation), and the volume-based particle size distribution and the volume-based average particle size were determined. Each diameter can be obtained.

The measurement range is 0.6 to 400 μm. External additives other than lubricants added to the toner base particles have a particle size of 0.6 μm or less, so the measurement is performed in the range of 0.6 to 400 μm, and the external additives other than the lubricants are not measured. The particle size distribution obtained corresponds to the particle size distribution of the lubricant.

FIG. 1 is a diagram for explaining an example of a volume-based particle size distribution of a lubricant having peaks on the small particle size side and the large particle size side. It is an example of the particle size distribution of a conventional lubricant. b is an example of the volume-based particle size distribution of the lubricant having two peaks on the small particle size side and the large particle size side according to the present invention, P1 is the peak on the small particle size side, and P2 is the large particle size side. indicate a peak. D indicates the minimum particle size of the particle size distribution curve. The content ratio is obtained by dividing the grain size D of the minimum value into the small grain size side and the large grain size side. That is, the respective content ratios are values when the volume-based particle size distribution of the lubricant shown in FIG.

FIG. 2 is a diagram showing the integrated value of the frequency of the volume-based particle size distribution of the lubricant, and is a diagram for explaining the content ratio of the lubricant having a peak on the small particle size side and the lubricant having a peak on the large particle size side. Here, the integrated frequency value (intersection point with D) at the particle size D of the minimum value of the particle size distribution represents the content ratio of the lubricant having a peak on the small particle size side.

In the lubricant according to the present invention, the volume-based particle size distribution of the lubricant has two peaks on the small particle size side and the large particle size side, and the content ratio of the lubricant having the peak on the small particle size side is 50 It is preferably ~70% by mass.

The respective content ratios are values obtained when the volume-based particle size distribution of the lubricant shown in FIG.

The lubricant used in the present invention is preferably particles containing a fatty acid metal salt as a main component, and preferably has a Mohs hardness of 2 or less, from the viewpoint of spreadability to the photoreceptor. Here, the “main component” means the component with the highest mass ratio among the constituent components.

The fatty acid metal salt is preferably a metal salt selected from zinc, calcium, magnesium, aluminum and lithium. Among these, fatty acid zinc, fatty acid lithium, and fatty acid magnesium are particularly preferred. Moreover, as the fatty acid of the fatty acid metal salt, a higher fatty acid having 12 or more and 22 or less carbon atoms is preferable. When a fatty acid having 12 or more carbon atoms is used, the generation of free fatty acid can be suppressed, and when the fatty acid has 22 or less carbon atoms, the melting point of the fatty acid metal salt does not become too high and good fixability can be obtained. can be done. Stearic acid is particularly preferred as the fatty acid.

As the fatty acid metal salt particles used in the present invention, particles containing zinc stearate as a main component, particles containing calcium stearate as a main component, or particles containing magnesium stearate as a main component are preferable. Among them, particles containing zinc stearate as a main component are particularly preferable because they have a small adhesive force to the toner base particles and easily migrate to the photoreceptor when added in a small amount.

Further, in the present invention, two kinds of lubricants having different average particle diameters are used in order to make the particle size distribution of the lubricant contained in the toner have two peaks, one on the small particle size side and the other on the large particle size side. is preferred. In this case, the components of the two lubricants having different average particle diameters may be the same or different.

The content of the lubricant in the toner is preferably 0.01 to 0.5 parts by mass with respect to 100 parts by mass of the toner base particles. Within this range, a sufficient lubricating effect can be obtained.

<2.2 Toner base particles>
As the toner base particles, known toner base particles can be used. Such toner base particles are specifically composed of toner base particles containing at least a binder resin and a colorant. Further, the toner base particles may further contain other components such as a release agent and a charge control agent, if necessary.

The volume-based average particle diameter of the toner base particles is preferably in the range of 5.0 to 8.0 μm. If the volume-based average particle size of the toner base particles is within this range, a high-definition image can be obtained.

The average circularity (shape factor) of the toner base particles is preferably 0.930 to 0.990, more preferably 0.955 to 0.980, from the viewpoint of improving fluidity.

(Measuring Method of Average Circularity and Volume-based Average Particle Diameter of Toner Base Particles)
The average circularity and volume-based average particle size of the toner base particles can be measured using, for example, a flow type particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation). Specifically, the toner was blended with an aqueous solution containing a surfactant, and after dispersion by performing ultrasonic dispersion treatment for 1 minute, measurement conditions HPF (high-magnification imaging ) mode, photographing can be performed at an appropriate density with 3,000 to 10,000 HPFs detected, and the average circularity and the volume-based average particle size can be measured.

Regarding the circularity, the circularity of each toner base particle is calculated by the following formula, and the average circularity is calculated. Here, "equivalent circle diameter" means the diameter of a circle having the same area as the particle image.
Circularity = Perimeter of circle obtained from circle equivalent diameter / Perimeter of projected particle image

(Binder resin)
A thermoplastic resin is preferably used as the binder resin constituting the toner base particles.

As such a binder resin, those generally used as binder resins constituting toner base particles can be used without particular limitation. acrylates, alkyl methacrylates, etc.), styrene acrylic copolymer resins, polyester resins, silicone resins, olefin resins, amide resins, and epoxy resins.

Among these, styrene-based resins, acrylic-based resins, styrene-acrylic copolymer-based resins, and polyester resins are preferable because they have low-viscosity melting properties and high sharp-melting properties. It is preferable to use 50% or more of a styrene-acrylic copolymer resin as the main resin. These can be used singly or in combination of two or more.

Polymerizable monomers for obtaining the binder resin include, for example, styrene-based monomers such as styrene, methylstyrene, methoxystyrene, butylstyrene, phenylstyrene, and chlorostyrene; methyl acrylate, ethyl acrylate, butyl Acrylic acid ester-based monomers such as acrylates and ethylhexyl acrylate; Methacrylic acid ester-based monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and ethylhexyl methacrylate; Carboxylic acids such as acrylic acid, methacrylic acid, and fumaric acid System monomers and the like can be used.

These can be used singly or in combination of two or more.

The binder resin constituting the toner base particles preferably has a glass transition temperature (Tg) of 30 to 50° C. from the viewpoint of low-temperature fixing. When the glass transition temperature is within this range, good low-temperature fixability and heat-resistant storage stability are obtained.

The glass transition temperature of the binder resin can be measured using "Diamond DSC" (manufactured by PerkinElmer).

As for the measurement procedure, 3.0 mg of the binding resin is sealed in an aluminum pan and set in a holder. Use an empty aluminum pan as a reference. As the measurement conditions, the measurement temperature is 0 to 200 ° C., the temperature increase rate is 10 ° C./min, and the temperature decrease rate is 10 ° C./min. Analysis is performed based on data in heating (2nd. Heat).

The glass transition temperature is obtained by drawing a tangent line indicating the maximum slope between the extended line of the baseline before the rise of the first endothermic peak and the rising portion of the first peak to the peak apex, and taking the intersection point as the glass transition point. show.

The glass transition temperature (Tg) of the toner base particles is measured by the same method as above using the toner base particles as the measurement sample.

Furthermore, the softening temperature of the binder resin is preferably 80 to 130°C, more preferably 90 to 120°C. The softening temperature can be measured, for example, with a flow tester "CFT-500D" (manufactured by Shimadzu Corporation).

The softening temperature is measured, for example, as follows.

First, in an environment with a temperature of 20 ± 1 ° C. and a relative humidity of 50 ± 5% RH, put 1.1 g of the sample in a petri dish and flatten it and leave it for 12 hours or more. (manufacturer) for 30 seconds with a force of 3820 kg/cm ² to prepare a cylindrical molded sample with a diameter of 1 cm, and then this molded sample is placed in an environment with a temperature of 24 ± 5 ° C and a relative humidity of 50 ± 20% RH. , with a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), under the conditions of a load of 196 N (20 kgf), a starting temperature of 60 ° C., a preheating time of 300 seconds, and a heating rate of 6 ° C./min, the hole of the cylindrical die (1 mm diameter × 1 mm), extruded from the end of preheating using a piston with a diameter of 1 cm, and the offset method temperature T _0ffset measured by the melting temperature measurement method of the heating method with an offset value of 5 mm is taken as the softening temperature of the sample. .

The softening temperature of the toner base particles is measured using a sample as the toner base particles in the same manner as described above.

(coloring agent)
A known inorganic or organic colorant can be used as the colorant that constitutes the toner base particles.

The amount of the colorant to be added is in the range of 1 to 30% by weight, preferably 2 to 20% by weight, based on the total toner base particles.

(Release agent)
The toner base particles may contain a releasing agent. Release agents include, for example, hydrocarbon waxes (polyethylene wax, oxidized polyethylene wax, polypropylene wax, oxidized polypropylene wax, etc.), carnauba wax, fatty acid ester wax, sasol wax, rice wax, and candelilla wax. , jojoba oil wax, and beeswax wax.

The content of the release agent in the toner base particles is preferably in the range of 1 to 30 parts by mass, more preferably in the range of 5 to 20 parts by mass, with respect to 100 parts by mass of the binder resin.

(Charge control agent)
The toner base particles may contain a charge control agent. Examples of charge control agents include metal complexes of salicylic acid derivatives of zinc and aluminum (salicylic acid metal complexes), calixarene compounds, organic boron compounds, and fluorine-containing quaternary ammonium salt compounds.

The content of the charge control agent in the toner base particles is preferably in the range of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the binder resin.

(Method for producing toner base particles)
Examples of methods for producing toner base particles include a kneading pulverization method, a suspension polymerization method, an emulsion aggregation method, a dissolution suspension method, a polyester elongation method, and a dispersion polymerization method.

Among these methods, it is preferable to employ the emulsion aggregation method from the viewpoints of uniformity of particle size, controllability of shape, and ease of core-shell structure formation, which are advantageous for high image quality and high stability.

In the emulsion aggregation method, a dispersion liquid of fine resin particles dispersed with a surfactant or a dispersion stabilizer is mixed with a dispersion liquid of constituent components of toner base particles such as fine colorant particles, if necessary, and a flocculant is added. Then, or at the same time as the aggregation, the fine resin particles are fused and the shape is controlled to produce toner base particles.

Here, the resin fine particles may optionally contain internal additives such as a release agent and a charge control agent. It can also be a particle.

From the viewpoint of toner structure design, it is also preferable to add different kinds of resin fine particles during aggregation to form toner base particles having a core-shell structure.

Resin fine particles can be produced, for example, by an emulsion polymerization method, a mini-emulsion polymerization method, a phase inversion emulsification method, or the like, or by combining several production methods. When the fine resin particles contain an internal additive, it is particularly preferable to use a mini-emulsion polymerization method.

<2.3 External additives other than lubricants>
In addition to the lubricant, the toner particles preferably contain fine particles such as known inorganic fine particles and organic fine particles on their surfaces as an external additive from the viewpoint of improving the chargeability and fluidity of the toner. As the inorganic fine particles, it is preferable to use inorganic oxide fine particles such as silica, titania, and alumina, and these inorganic fine particles are preferably hydrophobized with a silane coupling agent, a titanium coupling agent, or the like. .

Polymers such as polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymers can be used as the organic fine particles.

The total content of inorganic fine particles and organic fine particles is preferably in the range of 0.05 to 5 parts by mass, more preferably in the range of 0.1 to 3 parts by mass, based on 100 parts by mass of the toner base particles. preferable.

(metal oxide fine particles)
For the purpose of further enhancing the polishing effect of the surface of the photoreceptor, the toner particles according to the present invention preferably contain metal oxide fine particles having a high polishing effect as an external additive.

The fine metal oxide particles are deposited on the tip of the cleaning blade and act as an abrasive to refresh the surface of the photoreceptor. Further, by polishing the excess lubricant spread on the photoreceptor, the occurrence of image defects such as black dots on the surface of the photoreceptor is suppressed. Further, it has the effect of removing discharge products and the effect of controlling the fluidity and chargeability of toner.

As the metal oxide fine particles, silica fine particles, alumina fine particles, cerium oxide fine particles, calcium titanate fine particles, or strontium titanate fine particles having a number average primary particle diameter within the range of 100 to 300 nm are preferable. Among these, calcium titanate fine particles or strontium titanate fine particles are particularly preferred.

The content of the metal oxide fine particles is preferably in the range of 0.05 to 5 parts by mass, more preferably in the range of 0.1 to 3 parts by mass, based on 100 parts by mass of the toner base particles.

From the viewpoint of heat-resistant storage stability and environmental stability, the metal oxide fine particles are preferably surface-modified with a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, or the like.

<2.4 External Additive Addition Method>
Examples of the method for adding the external additive include a dry method in which the external additive is added in the form of powder to the dried toner base particles, and mechanical mixing devices such as a Henschel mixer and a coffee mill are used as the mixing device. mentioned.

Further, in the present invention, it is preferable to add and mix the lubricant in two stages in order to control the particle size distribution of the lubricant. Specifically, it is preferable to first add and mix a lubricant having a peak on the small particle size side and then add and mix a lubricant having a peak on the large particle size side. External additives such as metal oxide fine particles other than the lubricant may be added and mixed in any of the above two steps.

<2.5 Developer>
The toner particles according to the present invention can be used in the image forming system of the present invention as a magnetic or non-magnetic single-component developer, but may be mixed with carrier particles and used as a two-component developer. When this toner is used as a two-component developer, magnetic particles made of conventionally known materials such as iron, ferrite, magnetite, lead, aluminum, and alloys thereof can be used as the carrier particles. Particles are preferred. As the carrier particles, resin-coated carrier (coated carrier) particles in which the surfaces of magnetic particles are coated with a coating agent such as resin, binder-type carrier particles in which magnetic fine powder is dispersed in a binder resin, and the like are used. good too.

The coating resin constituting the resin-coated carrier particles is not particularly limited, but examples thereof include olefin resins, styrene resins, styrene-acrylic resins, acrylic resins, silicone resins, ester resins, and fluorine resins. be done. Also, the binder resin constituting the binder-type carrier particles is not particularly limited, and known ones can be used. can. Among these, styrene-acrylic resins and resin-coated carrier particles coated with acrylic resins are preferable from the viewpoint of chargeability and durability.

The volume average particle diameter of the carrier particles is preferably in the range of 20 to 100 μm, more preferably in the range of 25 to 80 μm, because high-quality images can be obtained and carrier adhesion is suppressed. is more preferred. The volume average particle diameter of the carrier particles can typically be measured by a laser diffraction particle size distribution analyzer "HELOS" (manufactured by Sympatech) equipped with a wet disperser.

<3 Cleaning means>
The cleaning means according to the present invention is characterized by having a brush roller having a plurality of pile bundles and a cleaning blade provided downstream of the brush roller in the rotation direction of the photoreceptor.

FIG. 3 is a schematic diagram of the cleaning means. The cleaning means shown in FIG. 3 has a brush roller 120 and a cleaning blade 121 provided downstream of the brush roller 120 in the direction of rotation of the photoreceptor 111 (the direction of the arrow in the figure).

<3.1 Brush roller>
The brush roller according to the present invention has a plurality of pile bundles, and when the pile bundle fineness [dtex] is X and the pile density [KF/inch ² ] is Y, the following formula (1) and (2) is satisfied.
Formula (1): 100≤Y≤250
Formula (2): 0.7≤X/Y≤2.2

In the present invention, the term "pile" refers to protruding fibers planted on the base fabric. The term "pile bundle" refers to a pile bundle implanted in the same opening of the base fabric.

The main function of the brush roller according to the present invention is to uniformize the distribution of the lubricant present on the photoreceptor. Specifically, the lubricant excessively present on the photoreceptor is recovered, and the small-diameter lubricant that tends to exist in the toner-applied area is transferred to the toner-non-applied area. By diffusing the large particle diameter side of the lubricant, which is easy to transfer, to the toner application area, the distribution of the lubricant existing on the photoreceptor is made uniform. This makes it possible to suppress the image memory.

The configuration of the brush roller is not particularly limited as long as it has a plurality of pile bundles and satisfies the above formulas (1) and (2). For example, the pile is planted on a cylindrical shaft. The base fabric may be fixed with an adhesive or the like. Various techniques such as pile weaving and electrostatic flocking can be used as a method for flocking the pile on the base fabric.

In the present invention, the "pile bundle fineness [dtex]" represented by X refers to the fineness of the pile bundle, and is a value that can be obtained by the following formula.
Pile bundle fineness [dtex] = fineness of one pile [dtex] x number of piles per pile bundle

In the present invention, "pile density [KF/inch ² ]" represented by Y means the number of piles per 1 inch ² . Here, "KF" is a unit that becomes "1 KF" in "1000". Therefore, for example, 100 KF/inch ² means that the number of piles per 1 inch ² is 100,000 (that is, 100,000/inch ² ). In addition, regarding the number of piles in the case of loop piles, one loop is regarded as two piles.

Each of the above values can be confirmed, for example, by loosening the pile bundle to make it easy to observe and observing it with an optical microscope at an appropriate magnification.

In the brush roller according to the present invention, by setting the pile bundle fineness X and the pile density Y within the range satisfying the above formulas (1) and (2), the movable area per pile bundle, the rubbing force, the pile and The probability of contact with the lubricant becomes moderate, and the recovery and diffusion effect of the lubricant increases. Thereby, the distribution of the lubricant on the photoreceptor can be made uniform.

When the pile density Y is less than 100, the rubbing force becomes too small, so the effect of collecting and diffusing the lubricant becomes small. On the other hand, if the pile density Y is greater than 250, the operating area per pile bundle becomes too small, so the effect of diffusing the lubricant becomes small.

If X/Y is less than 0.7, the operating area per pile bundle becomes too small, and the diffusion effect of the lubricant becomes small. On the other hand, when X/Y is greater than 2.2, the probability of contact between the pile and the lubricant becomes too small, so the effect of recovering and diffusing the lubricant becomes small.

The Young's modulus of the pile is preferably in the range of 25 to 70 cN/dtex by adjusting the rubbing force to an appropriate range. As a result, the rubbing force becomes appropriate, and the effect of recovering and diffusing the lubricant can be further improved.

The Young's modulus of the pile can be measured, for example, by using a thermomechanical analyzer TMA/SS6000 manufactured by Seiko Instruments. In this case, the ambient temperature for measurement is 25°C. As a measurement sample, a plurality of piles having a length of 10 mm or more are collected so that the total mass per 10 mm of length is 0.5 mg. The plurality of piles are arranged in parallel and mounted with a chuck-to-chuck distance of 10 mm, and a constant load of 0.73 mN/dtex is applied. Then, after obtaining a stress-strain curve under the condition of 240 mN/min, the slope of the tangent line of the curve when the strain is 0.1% is defined as Young's modulus.

Although the length of the pile is not particularly limited, it is preferably in the range of 2.5 to 3.5 mm from the viewpoint of recovery and diffusion of the lubricant.

Although the fineness of one pile is not particularly limited, it is preferably in the range of 2.2 to 6.6 dtex from the viewpoint of the recovery and diffusion effect of the lubricant.

The pile material is not particularly limited, but synthetic resins such as polyester, acrylic, 6-nylon, 12-nylon, vinylon, and aramid, and mixtures of two or more of these can be used.

The pile shape is not particularly limited, and for example, a loop pile with loops left on the pile or a straight cut pile with loops cut can be used.

The brush roller preferably rotates on a rotation axis parallel to the rotation axis of the photoreceptor. This rotation direction may be the with direction (the direction in which the surface moves in the same direction) or the counter direction (the direction in which the surface moves in the opposite direction) with respect to the rotation direction of the photosensitive member. However, from the viewpoint of the diffusion effect of the lubricant, the with direction is preferable.

The number of rotations of the brush roller is not particularly limited, but is preferably within the range of 300 to 900 rpm from the viewpoint of the diffusion effect of the lubricant.

The brush roller may be configured to apply a voltage having a polarity opposite to that of the residual toner in order to improve the effect of collecting the residual toner.

<3.2 Cleaning Blade>
A cleaning blade according to the present invention will be described with reference to FIG. The cleaning blade 121 shown in FIG. 3 is supported by a support member 122, and the tip of the cleaning blade 121 moves in the opposite direction (counter direction) to the rotation direction of the photoreceptor 111 at the contact portion C with the surface of the photoreceptor 111. ).

The cleaning blade 121 according to the present invention is preferably brought into pressure contact with the surface of the photoreceptor 111 so that the edge angle _θe of the ridgeline at the tip is within the range of 90 to 130°. The edge angle _θe refers to the angle of the ridge line portion at the tip of the contact portion C with the surface of the photoreceptor 111 .

When the edge angle θ _e is 90° or more, the wedge angle θ ₃ becomes small, so that a shearing action for cleaving and extending the layered crystals of the lubricant is obtained, and the surface lubricity can be improved. The wedge angle _θ3 is the angle formed by the cleaning blade 121 and the ridgeline of the photoreceptor 111 on the upstream side in the rotational direction.

When the edge angle θ _e is 130° or less, the wedge angle θ ₃ does not become too small, the polishing property becomes appropriate, and lubricity can be effectively obtained. In addition, since the force of the toner particles pushing back the blade vertically upward does not become too large, cleaning defects are less likely to occur.

Further, when the edge angle _θe is in the range of 90 to 130°, the stick-slip vibration of the cleaning blade is reduced, the slipping of the toner particles is improved, and the cleaning property is improved.

From the viewpoint of effectively improving surface lubricity and cleanability, the edge angle θ _e is preferably 95° or more and preferably 110° or less.

The cleaning blade 121 according to the present invention is preferably brought into pressure contact with the surface of the photoreceptor 111 so that the effective contact angle _θ1 is within the range of 7 to 20°. The effective contact angle _θ1 is the angle formed by the cleaning blade 121 and the ridgeline of the photoreceptor 111 on the downstream side in the rotation direction.

When the effective contact angle θ ₁ is 7° or more, the wedge angle θ ₃ becomes small, so that a shearing action of cleaving and extending the layered crystals of the lubricant is obtained, and the surface lubricity can be improved.

When the effective contact angle θ ₁ is 20° or less, the wedge angle θ ₃ does not become too small, the abrasiveness becomes appropriate, and lubricity can be effectively obtained. In addition, since the force of the toner particles pushing back the blade vertically upward does not become too large, cleaning defects are less likely to occur.

From the viewpoint of effectively improving surface lubricity, the effective contact angle θ ₁ is preferably 9° or more and preferably 17° or less.

The edge angle θ _e and the effective contact angle θ ₁ can be obtained by calculating deflection using the cross-sectional shape of the cleaning blade 121 and physical properties such as Young's modulus of the material.

The cleaning blade 121 is preferably made of polyurethane from the viewpoint of abrasion resistance and moldability. Polyurethanes include those obtained by reacting polyols, polyisocyanates and, if necessary, cross-linking agents.

The cleaning blade 121 may have a single-layer structure, or may have a multi-layer structure in which a support layer and a contact layer are laminated.

The hardness of the cleaning blade 121 is preferably within the range of 65 to 85 degrees as defined in JIS-A. If the hardness is 65° or more, the cleaning blade 121 is difficult to be pulled in, and the wedge angle _θ3 does not become too small. On the other hand, when the hardness is 85° or less, the surface pressure becomes large, the polishing force does not become too strong, and the lubricating effect is sufficiently obtained because the lubricant becomes difficult to remove.

The impact resilience of the cleaning blade 121 is preferably within the range of 10 to 40 degrees. If the rebound resilience is within the above range, the vibration is moderately suppressed, the wedge angle _θ3 is stabilized, and the shearing action of the fatty acid metal salt can be exhibited more effectively.

The free length L of the cleaning blade 121 is preferably within the range of 8.5-11.5 mm. Also, the thickness of the cleaning blade 121 is preferably within the range of 1.7 to 2.5 mm.

The contact force of the cleaning blade 121 is preferably in the range of 12 to 30 N/m from the viewpoint of preventing unwiped and curling. If the contact force is 12 N/m or more, there is no fear of unwiping, and if it is 30 N/m or less, there is no fear of turning over.

The supporting member 122 can be a conventionally known one, and examples thereof include those made of rigid metal, elastic metal, plastic, ceramic, and the like. Among them, a rigid metal is preferable.

<4 Electrophotographic Photoreceptor>
Although the layer structure of the electrophotographic photoreceptor according to the present invention is not particularly limited, it preferably has a surface protective layer from the viewpoint of abrasion resistance. An electrophotographic photoreceptor having a surface protective layer can have, for example, a layer structure shown in (1) to (4) below.

(1) A layer structure in which a photosensitive layer (charge generation layer and charge transport layer) and a surface protective layer are sequentially laminated on a conductive support (2) A photosensitive layer (charge transport material and charge transport layer) is laminated on a conductive support (3) An intermediate layer, a photosensitive layer (a charge generating layer and a charge transport layer), and a surface protective layer are laminated on a conductive support. (4) A layer structure in which an intermediate layer, a photosensitive layer (single layer containing a charge-transporting substance and a charge-generating substance), and a surface protective layer are sequentially laminated on a conductive support.

As in the above example, the photosensitive layer may have a single-layer structure containing a charge-generating substance and a charge-transporting substance, or two layers of a charge-generating layer containing a charge-generating substance and a charge-transporting layer containing a charge-transporting substance. It may be a function-separated photosensitive layer composed of.

<4.1 Surface protective layer>
The surface protective layer preferably contains at least a binder resin and a charge-transporting substance, and more preferably contains metal oxide particles.

As the binder resin, for example, a resin such as polycarbonate can be used, but from the viewpoint of abrasion resistance, it is preferable to use a cured resin. A "cured resin" refers to a resin obtained by curing at least a polymerizable compound.

Photoreceptors with low abrasion resistance have a short service life, but have the property that the difference in lubricant adhesion amount does not increase due to surface abrasion, and image memory is less likely to occur. On the other hand, a photoreceptor with high wear resistance is less likely to wear, so image memory is likely to occur. However, in the image forming system of the present invention, the image memory can be suppressed by the configuration of the toner particles and the brush roller, so the photoreceptor can be configured to give priority to abrasion resistance. That is, by containing the cured resin in the surface protective layer, it is possible to achieve both abrasion resistance in long-term use of the photoreceptor and suppression of image memory at a high level.

The polymerizable compound is preferably a monomer that is polymerized (cured) by irradiation with actinic rays such as ultraviolet rays and electron beams to form resins such as polystyrene and polyacrylate that are generally used as binder resins for photoreceptors. Particularly preferred are styrene-based monomers, acrylic-based monomers, methacrylic-based monomers, vinyltoluene-based monomers, vinyl acetate-based monomers, and N-vinylpyrrolidone-based monomers.

Among them _, a crosslinkable radically _{polymerizable} compound ₍ radical Polymerizable monomers or oligomers thereof) are particularly preferred.

The above radically polymerizable compounds may be used alone or in combination. Further, these polymerizable compounds may be used as monomers, or may be used in the form of oligomers.

Examples of radically polymerizable compounds are shown below. The terms "Ac group number (acryloyl group number)" and "Mc group number (methacryloyl group number)" hereinafter refer to the number of acryloyl groups and the number of methacryloyl groups, respectively.

However, R is shown below in the above.

However, in the above, R' is shown below.

Among the above, the more preferable polymerizable compound used in the present invention has a quaternary carbon atom (branched structure) substituted with a carbon atom, and has 3 or more acryloyl groups at the terminals with this branched structure as the central structure. Specifically, groups of Ac-1 to Ac-6, Ac-31, Ac-37 and Ac-38 having a trimethylolpropane skeleton, a pentaerythritol skeleton or a dipentaerythritol skeleton, quaternaries substituted with carbon atoms Mc-1 having a carbon atom (branched structure) and three or more methacryloyl groups at the end with this branched structure as a central structure, specifically having a trimethylolpropane skeleton, a pentaerythritol skeleton or a dipentaerythritol skeleton. -Mc-6, Mc-31, Mc-37 and Mc-38 groups, and Mc-9 and Mc-11 groups having an isocyanuric ring skeleton and having three or more terminal methacryloyl groups.

It is preferable to use a compound having 3 or more functional groups (reactive groups) as the radically polymerizable compound. Two or more kinds of radically polymerizable compounds may be used in combination, but even in this case, it is preferable to use 50% by mass or more of radically polymerizable compounds having three or more functional groups. In addition, the curable reactive group equivalent, that is, "curable functional group molecular weight/number of functional groups" is preferably 1000 or less, more preferably 500 or less. This increases the crosslink density and improves wear resistance.

When reacting the radically polymerizable compound used in the present invention, a method of reacting by electron beam cleavage, a method of adding a radical polymerization initiator and reacting with light or heat, and the like are used. Either a photopolymerization initiator or a thermal polymerization initiator can be used as the polymerization initiator. Also, both photoinitiators and thermal initiators can be used together.

As the radical polymerization initiator for these photocurable compounds, a photopolymerization initiator is preferable, and among them, an alkylphenone-based compound or a phosphine oxide-based compound is preferable. Compounds having an α-hydroxyacetophenone structure or an acylphosphine oxide structure are particularly preferred. In addition, examples of compounds that initiate cationic polymerization include ionic polymerization initiators and nonionic polymerization initiators. Examples of ionic polymerization initiators include aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium and phosphonium, B(C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , and CF ₃ SO ₃ ^-salts . Examples of nonionic polymerization initiators include sulfonates that generate sulfonic acid, halides that generate hydrogen halide, iron allene complexes, and the like. Among these, a sulfonate that generates sulfonic acid or a halide that generates hydrogen halide, which are nonionic polymerization initiators, are particularly preferred.

Photopolymerization initiators preferably used are exemplified below.

Examples of α-aminoacetophenone series

Examples of α-hydroxyacetophenone compounds

Examples of acylphosphine oxide compounds

Examples of other radical polymerization initiators

On the other hand, thermal polymerization initiators include ketone peroxide compounds, peroxyketal compounds, hydroperoxide compounds, dialkyl peroxide compounds, diacyl peroxide compounds, peroxydicarbonate compounds, and peroxyesters. These thermal polymerization initiators are disclosed in company product catalogs and the like.

These polymerization initiators may be used singly or in combination of two or more. The content of the polymerization initiator is preferably in the range of 0.1 to 20 parts by mass, more preferably in the range of 0.5 to 10 parts by mass, per 100 parts by mass of the polymerizable compound.

As the charge-transporting substance contained in the surface protective layer, known charge-transporting substances can be used, for example, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, triphenylamine derivatives and the like. These may be used in combination of two or more.

Also, the charge transport material is preferably a compound having a structure represented by the following general formula (1). Compounds having a structure represented by the following general formula (1) do not exhibit absorption in the short wavelength region, and most of them have a molecular weight of 450 or less, and can enter the voids of the binder resin of the surface protective layer. is. For this reason, it is possible to smoothly inject charge carriers from the charge transport layer without lowering the wear resistance of the surface protective layer, and without causing an increase in residual charge or the occurrence of transfer memory, the surface protective layer charge can be transported to the surface of the

[In general formula (1), R ₁ , R ₂ , R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms. , k, l, and n are integers of 1 to 5, and m is an integer of 1 to 4. Moreover, when these k, l, m or n are plural, these plural groups may be the same or different. ]

Examples of the alkyl group having 1 to 7 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n- hexyl group, 3-methylpentan-2-yl group, 3-methylpentan-3-yl group, 4-methylpentyl group, 4-methylpentan-2-yl group, 1,3-dimethylbutyl group, 3, 3-dimethylbutyl group, 3,3-dimethylbutan-2-yl group, n-heptyl group, 1-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 1-ethyl pentyl group, 1-(n-propyl)butyl group, 1,1-dimethylpentyl group, 1,4-dimethylpentyl group, 1,1-diethylpropyl group, 1,3,3-trimethylbutyl group, and 1- and ethyl-2,2-dimethylpropyl group. Among these, alkyl groups having 1 to 5 carbon atoms are more preferred, and methyl, ethyl, propyl, n-butyl and n-pentyl groups are even more preferred.

Examples of alkoxy groups having 1 to 7 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy and n-pentyloxy groups. , isopentyloxy group, neopentyloxy group, 1,2-dimethyl-propoxy group, n-hexyloxy group, 3-methylpentan-2-yloxy group, 3-methylpentan-3-yloxy group, 4-methylpentyl oxy group, 4-methylpentan-2-yloxy group, 1,3-dimethylbutyloxy group, 3,3-dimethylbutyloxy group, 3,3-dimethylbutan-2-yloxy group, n-heptyloxy group, 1 -methylhexyloxy group, 3-methylhexyloxy group, 4-methylhexyloxy group, 5-methylhexyloxy group, 1-ethylpentyloxy group, 1-(n-propyl)butyloxy group, 1,1-dimethylpentyl oxy group, 1,4-dimethylpentyloxy group, 1,1-diethylpropyloxy group, 1,3,3-trimethylbutyloxy group, 1-ethyl-2,2-dimethylpropyloxy group and the like. Among them, an alkoxy group having 1 to 2 carbon atoms is more preferable, and a methoxy group is even more preferable.

In particular, at least one of R ₁ , R ₂ , R ₃ and R ₄ preferably has a propyl group, a butyl group or a pentyl group.

Moreover, it is more preferable that each of R ₁ and R ₂ is a hydrogen atom or a methyl group. More preferably, R ₃ is a hydrogen atom and R ₄ is an alkyl group having 1 to 5 carbon atoms. Moreover, it is more preferable that each of k, l, m and n is 1.

Specific examples of compounds having a structure represented by general formula (1) are shown below.

The charge-transporting substance can be synthesized by a known synthesis method such as the method described in JP-A-2006-143720.

Metal oxide particles contained in the surface protective layer include, for example, silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide), zirconium oxide, tin oxide, titania (titanium oxide), niobium oxide, Examples include metal oxide particles such as molybdenum oxide and vanadium oxide, with tin oxide, titanium oxide, and zinc oxide being preferred.

The volume resistivity [Ω cm] of the metal oxide particles is preferably in the range of 1×10 ³ to 1×10 ¹¹ from the viewpoint of stable potential retention, and is preferably in the range of 5×10 ³ to 4×. More preferably, it is in the range of 10 ¹⁰ Ω·cm.

The volume resistivity VR (volume resistivity) refers to the electrical resistivity of electricity flowing inside an object, and is a value represented by the following formula.
VR=(A/L)×R
VR: volume resistivity [Ω cm]
A: Cross-sectional area of substance [cm ² ]
L: Distance between electrodes [cm]
ρ: Electrical resistivity [Ω]

The volume resistivity VR [Ω cm] of the metal oxide particles is measured by filling the metal oxide particles in a container having electrodes arranged in parallel with a distance between the electrodes of 0.2 cm, for example, and applying a direct current with a potential difference of 500 V between both electrodes. The electrical resistivity ρ [Ω] can be obtained by measuring with a 4329A High Resistance Meter manufactured by Yokogawa Hewlett-Packard Co., Ltd.

The metal oxide particles are preferably surface-modified with a surface modifier having a radically polymerizable functional group, particularly a surface modifier having an acryloyl group or a methacryloyl group.

As the surface modifier having an acryloyl group or a methacryloyl group, the following compounds are exemplified.

S-1 CH ₂ =CHSi(CH ₃ )(OCH ₃ ) ₂
S-2 CH ₂ =CHSi(OCH ₃ ) ₃
S-3 CH ₂ =CHSiCl ₃
S-4 _CH2 =CHCOO( _CH2 ) _2Si ( _CH3 )( _OCH3 ) ₂
S-5 _CH2 =CHCOO( _CH2 ) _2Si ( _OCH3 ) ₃
S-6 _CH2 =CHCOO( _CH2 ) _3Si ( _CH3 )( _OCH3 ) ₂
S-7 _CH2 =CHCOO( _CH2 ) _3Si ( _OCH3 ) ₃
S-8 _CH2 =CHCOO( _CH2 ) _2Si ( _CH3 ) _Cl2
S-9 _CH2 =CHCOO _{( CH2} ) _2SiCl3
S-10 _CH2 =CHCOO( _CH2 ) _3Si ( _CH3 ) _Cl2
S-11 _CH2 = _CHCOO ( _CH2 ) _3SiCl3
S-12 _CH2 =C( _CH3 )COO( _CH2 ) _2Si ( _CH3 )( _OCH3 ) ₂
S-13 _CH2 =C( _CH3 )COO( _CH2 ) _2Si ( _OCH3 ) ₃
S-14 _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _CH3 )( _OCH3 ) ₂
S-15 _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _OCH3 ) ₃
S-16 _CH2 =C( _CH3 )COO( _CH2 ) _2Si ( _CH3 ) _Cl2
S-17 _CH2 =C( _CH3 ) _COO ( _CH2 ) _2SiCl3
S-18 _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _CH3 ) _Cl2
S-19 _CH2 =C( _CH3 ) _COO ( _CH2 ) _3SiCl3
S-20 _{CH2 =} CHSi( _C2H5 )( _OCH3 ) ₂
S-21 _CH2 =C( _CH3 )Si( _OCH3 ) ₃
S-22 _CH2 = _C ( _CH3 )Si( _OC2H5 ) ₃
S-23 _CH2 =CHSi( _OCH3 ) ₃
S-24 _CH2 =C( _CH3 )Si( _CH3 )( _OCH3 ) ₂
S-25 _CH2 =CHSi( _CH3 ) _Cl2
S-26 _CH2 =CHCOOSi( _OCH3 ) ₃
S-27 _CH2 = _CHCOOSi ( _OC2H5 ) ₃
S-28 _CH2 =C( _CH3 )COOSi( _OCH3 ) ₃
S-29 _CH2 =C( _CH3 ) _COOSi ( _OC2H5 ) ₃
S- _{30 CH2} =C( _CH3 )COO( _CH2 ) _3Si ( _OC2H5 ) ₃

Among the above, S-4 to S-7, which are compounds having an ether-bonded acryloyl group and a terminal methoxy group, and S-12 to S-, which are compounds having an ether-bonded methacryloyl group and a terminal methoxy group. 15 and S-24 are more preferred.

In addition, the amount of the surface modifier applied to the metal oxide particles is preferably in the range of 0.1 to 200 parts by mass, more preferably 7 to 70 parts by mass, relative to 100 parts by mass of the metal oxide particles before treatment. is more preferable.

A method for modifying the surface of metal oxide particles with a surface modifier having a radically polymerizable functional group will be described below using titanium oxide particles as an example.

First, 100 parts by mass of titanium oxide particles and 0.1 to 200 parts by mass of a surface modifier having a radically polymerizable functional group are suspended in 50 to 5000 parts by mass of a solvent to form a slurry (suspension of solid particles). to prepare.

The slurry is placed in a wet media dispersion type device and wet pulverized to refine the titanium oxide particles and at the same time to progress the surface modification of the titanium oxide particles. Thereafter, the solvent is removed and powdered, so that uniform titanium oxide particles surface-modified with a finer surface-modifying compound (such as a silane compound) can be obtained.

The above-mentioned wet media dispersion type device is a container filled with beads as media, and by rotating a stirring disk attached perpendicularly to the rotating shaft at high speed, the agglomerated particles of metal oxide particles are crushed, pulverized and dispersed. There is no problem as long as the configuration of the apparatus is a form that allows the metal oxide particles to be sufficiently dispersed and surface-modified when the metal oxide particles are surface-modified. For example, various modes such as vertical type/horizontal type, continuous type/batch type, etc. can be adopted. Specifically, sand mills, ultravisco mills, pearl mills, grain mills, dyno mills, agitator mills, dynamic mills and the like can be used. These wet media dispersion type devices use grinding media such as balls and beads to perform fine grinding and dispersion by impact crushing, friction, shearing, shear stress, and the like.

As the beads used in the above-mentioned wet media dispersion type apparatus, balls made of glass, alumina, zircon, zirconia, steel, flint stone, etc. can be used as raw materials, but those made of zirconia or zircon are particularly preferable. As for the size of the beads, beads with a diameter of about 1 to 2 mm are generally used, and beads with a diameter of about 0.1 to 1.0 mm are preferably used.

Various materials such as stainless steel, nylon, and ceramics can be used for the disk and inner wall of the container used in the wet media dispersion type apparatus. preferable.

By the wet treatment as described above, the titanium oxide particles can be surface-modified with a surface-modifying agent having a radically polymerizable functional group.

In the above, titanium oxide particles have been described as an example, but metal oxide particles such as alumina, zinc oxide, tin oxide, and silica also have hydroxyl groups on their surfaces like titanium oxide. In addition, the surface can be modified with a surface modifier having a radically polymerizable functional group.

The method for producing the metal oxide particles is not particularly limited, and particles produced by known production methods can be used.

The number average primary particle size of the metal oxide particles is preferably in the range of 1 to 300 nm, more preferably in the range of 3 to 100 nm, and even more preferably in the range of 5 to 40 nm.

The number-average primary particle size of the metal oxide particles is obtained by, for example, taking a 10,000-fold enlarged photograph with a scanning electron microscope (manufactured by JEOL Ltd.) and scanning 300 particles at random. ) were analyzed using an automatic image processing analyzer LUZEX AP (Nireco Co., Ltd.) software version Ver. 1.32 can be used to calculate the number average primary particle size.

For the surface protective layer according to the present invention, for example, a surface protective layer coating solution is prepared by mixing a polymerizable compound, a polymerization initiator, a charge transport substance, metal oxide particles, etc. in a solvent, and the surface protective layer coating solution is prepared. It can be formed by coating on the charge transport layer described later, drying and curing.

The ratio of the metal oxide particles in the surface protective layer is preferably 20 to 170 parts by mass, more preferably 25 to 90 parts by mass, when the resin component in the surface protective layer is 100 parts by mass. . It may be considered that the resin component in the surface protective layer is formed by the curing reaction of all the polymerizable compounds contained in the surface protective layer coating solution.

The content of the charge-transporting substance in the surface protective layer is preferably in the range of 2 to 60 parts by mass, more preferably in the range of 10 to 50 parts by mass, based on 100 parts by mass of the resin component of the surface protective layer. , more preferably in the range of 10 to 35 parts by mass.

Also, the ratio of the charge transport substance to the resin component in the surface protective layer may be regarded as the same as the ratio of the charge transport substance content to the polymerizable compound content in the surface protective layer coating solution.

Further, the surface protective layer can further contain various antioxidants, and various lubricant particles can be added. For example, fluorine atom-containing resin particles can be added. Examples of fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodichloride ethylene resin, and these resins. It is preferable to appropriately select one or more of the copolymers, and tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

Solvents for forming the surface protective layer include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, cyclohexane, Examples include, but are not limited to, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, diethylamine, and the like.

Any solvent can be used as long as it can dissolve or disperse the polymerizable compound, the metal oxide particles, and the charge transport material. The method for producing the surface protective layer coating solution is not particularly limited either, and the polymerizable compound, the metal oxide particles, the charge-transporting substance, and, if necessary, various additives are added to the solvent, and the mixture is stirred and mixed until dissolved or dispersed. Just do it. Also, the amount of the solvent is not particularly limited, and it can be adjusted appropriately so that the surface protective layer coating solution has a viscosity suitable for the coating work.

As a method for applying the surface protective layer coating solution, known methods such as dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper, and circular slide hopper are used. be able to.

After applying the coating solution for the surface protective layer, it is preferable to carry out a curing reaction by irradiating an actinic ray after performing natural drying or heat drying. Specifically, the coating film of the surface protective layer coating solution is irradiated with actinic rays to generate radicals, polymerize, and form cross-linking bonds by cross-linking reactions between molecules and within molecules to cure and form a cured resin. preferably generated. As the actinic rays, ultraviolet rays and electron beams are more preferable, and ultraviolet rays are particularly preferable because they are easy to use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, and flash (pulse) xenon lamps can be used. Irradiation conditions vary depending on each lamp, but the irradiation dose of actinic rays is usually 5 to 500 mJ/cm ² , preferably 5 to 100 mJ/cm ² . The power of the lamp is preferably 0.1 kW to 5 kW, particularly preferably 0.5 kW to 3 kW.

As an electron beam source, there are no particular restrictions on the electron beam irradiation apparatus, and in general, curtain beam type electron beam accelerators, which are relatively inexpensive and can produce a large output, are effective as electron beam accelerators for such electron beam irradiation. Used. The acceleration voltage for electron beam irradiation is preferably in the range of 100 to 300 kV. The absorbed dose is preferably within the range of 0.5 to 10 Mrad.

The irradiation time for obtaining the required dose of actinic rays is preferably within the range of 0.1 seconds to 10 minutes, more preferably within the range of 0.1 seconds to 5 minutes from the viewpoint of work efficiency.

The timing of the step of drying the coating film of the surface protective layer coating solution is not limited to before irradiation with actinic rays, and may be after irradiation with actinic rays or during irradiation with actinic rays.

The drying conditions can be appropriately selected according to the type of solvent, film thickness, and the like. The drying temperature is preferably in the range of room temperature to 180°C, particularly preferably in the range of 80°C to 140°C. The drying time is preferably in the range from 1 minute to 200 minutes, particularly preferably in the range from 5 minutes to 100 minutes.

The thickness of the surface protective layer is preferably in the range of 0.2-10 μm, more preferably in the range of 0.5-6 μm.

<4.2 Conductive support>
The conductive support used in the present invention may be any material as long as it has electrical conductivity. A metal foil such as aluminum or copper laminated on a plastic film, a plastic film vapor-deposited with aluminum, indium oxide, tin oxide, etc., a metal provided with a conductive layer by applying a conductive substance alone or with a binder resin, Examples include plastic films and paper.

<4.3 Intermediate layer>
In the present invention, an intermediate layer having a barrier function and an adhesive function may be provided between the conductive support and the photosensitive layer. Considering various trouble prevention, etc., it can be said that providing an intermediate layer is a preferable aspect.

The intermediate layer is formed by dissolving a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, and gelatin in a known solvent and applying the same coating method as the surface protective layer, such as dip coating. can. Of these, alcohol-soluble polyamide resins are preferred.

Also, various conductive fine particles and metal oxide particles can be contained for the purpose of adjusting the resistance of the intermediate layer. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide, and zirconium oxide. Ultrafine particles can be used.

These metal oxide particles may be used singly or in combination of two or more. When two or more types are mixed, they may take the form of solid solution or fusion. The average particle size of such metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

As the solvent used for forming the intermediate layer, a solvent capable of dispersing the inorganic particles well and dissolving the binder resin, particularly the polyamide resin, is preferable. Specifically, alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, and sec-butanol improve the solubility and coating properties of the polyamide resin. excellent and desirable. Examples of co-solvents that can be used in combination with the above-mentioned solvents to improve storage stability and dispersibility of particles and produce favorable effects include benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

The concentration of the binder resin in the coating solution for forming the intermediate layer is appropriately selected according to the thickness of the intermediate layer and the production speed.

When the inorganic particles are dispersed, the mixing ratio of the inorganic particles is preferably in the range of 20 to 400 parts by mass, more preferably in the range of 50 to 350 parts by mass, per 100 parts by mass of the binder resin.

As means for dispersing the inorganic particles, an ultrasonic dispersing machine, a ball mill, a sand mill, a homomixer, or the like can be used, but the means is not limited to these.

In order to form the intermediate layer, the binder resin is dissolved in the above solvent, the inorganic fine particles are dispersed by the above method, and this solution can be applied to a desired thickness on the conductive support. . The applied layer is then dried to complete the intermediate layer. The method for drying the intermediate layer can be appropriately selected according to the type of solvent and film thickness, but heat drying is preferred.

The thickness of the intermediate layer is preferably in the range of 0.1-15 μm, more preferably in the range of 0.3-10 μm.

<4.4 Charge Generation Layer>
The charge-generating layer used in the present invention preferably contains a charge-generating substance and a binder resin, and is preferably formed by dispersing the charge-generating substance in a binder resin solution and applying the solution.

Charge-generating substances include azo raw materials (Sudan Red, Diane Blue, etc.), quinone pigments (pyrenequinone, anthanthrone, etc.), indigo pigments (quinocyanine pigments, perylene pigments, indigo, thioindigo, etc.), polycyclic quinone pigments (pyranthrone , and diphthaloylpyrene), phthalocyanine pigments, etc., but are not limited thereto. Preferred are polycyclic quinone pigments and titanyl phthalocyanine pigments. These charge-generating substances can be used alone or in the form of being dispersed in a known resin.

Known resins can be used as the binder resin for the charge generating layer, and examples include polystyrene resins, polyethylene resins, polypropylene resins, acrylic resins, methacrylic resins, vinyl chloride resins, vinyl acetate resins, polyvinyl butyral resins, epoxy resins, Polyurethane resins, phenolic resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (e.g., vinyl chloride-vinyl acetate copolymer resins, chloride vinyl-vinyl acetate-maleic anhydride copolymer resin), and poly-vinylcarbazole resin, but are not limited thereto. Polyvinyl butyral resin is preferred.

The charge-generating layer is formed by dispersing the charge-generating substance in a solution of a binder resin dissolved in a solvent using a dispersing machine to prepare a coating solution. Dry preparation of the membrane is preferred. As a coating method, the same method as that for the surface protective layer can be used.

Solvents for dissolving and applying the binder resin used in the charge generation layer include, for example, toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, t-butyl acetate, methanol, ethanol, Propanol, butanol, methyl cellosolve, 4-methoxy-4-methyl-2-pentanone, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, diethylamine, and the like, but are not limited to these. isn't it.

As a means for dispersing the charge-generating substance, an ultrasonic dispersing machine, a ball mill, a sand mill, a homomixer, or the like can be used, but the means is not limited to these.

The mixing ratio of the charge-generating substance to the binder resin is preferably in the range of 1 to 600 parts by mass, more preferably in the range of 50 to 500 parts by mass, per 100 parts by mass of the binder resin.

Incidentally, the coating liquid for the charge generation layer can be prevented from generating image defects by filtering foreign matters and aggregates before coating. It can also be formed by vacuum deposition of the pigment.

The thickness of the charge generation layer varies depending on the properties of the charge generation material, the properties of the binder resin, the mixing ratio, etc., but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.05 to 3 μm.

<4.5 Charge transport layer>
The charge transport layer used in the photoreceptor of the present invention preferably contains a charge transport material and a binder resin, and is preferably formed by dissolving the charge transport material in a binder resin solution and applying the solution.

As the charge-transporting substance contained in the charge-transporting layer, known charge-transporting substances can be used, for example, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, triphenylamine derivatives and the like. These may be used in combination of two or more.

It is preferable that the charge-transporting layer provided under the surface protective layer contains a charge-transporting substance having a high ionization potential with respect to the charge-generating layer and the surface-protecting layer, a high mobility, and a long flying distance. As the charge-transporting substance used in the charge-transporting layer, a charge-transporting substance different from the compound having the structure represented by the general formula (1) is preferably used.

Preferred examples of charge-transporting materials that satisfy the above properties and are used in photoreceptors for short-wave exposure such as short-wave lasers are shown below.

Preferable examples of the charge-transporting material used in the photoreceptor for long-wave exposure using a long-wave laser or the like are shown below.

In addition, the following compounds can also be preferably used as the charge-transporting substance contained in the charge-transporting layer.

The charge-transporting substance can be synthesized by a known synthesis method, for example, the synthesis methods described in JP-A-2010-26428 and JP-A-2010-91707.

As the binder resin for the charge transport layer, known resins can be used, such as polycarbonate resins, polyacrylate resins, polyester resins, polystyrene resins, styrene-acrylonitrile copolymer resins, polymethacrylic acid ester resins, and styrene-methacrylic resins. Examples thereof include acid ester copolymer resins, and polycarbonate resins are preferred. Furthermore, BPA, BPZ, dimethyl BPA, and BPA-dimethyl BPA copolymers are preferred from the viewpoints of crack resistance, abrasion resistance, and chargeability.

The charge-transporting layer is preferably formed by dissolving a binder resin and a charge-transporting substance to prepare a coating solution, applying the coating solution to a given thickness with a coating machine, and drying the coating film. As a coating method, the same method as that for the surface protective layer can be used.

Solvents for dissolving the binder resin and charge transport material include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, and tetrahydrofuran. , 1,4-dioxane, 1,3-dioxolane, pyridine, diethylamine, and the like, but are not limited to these.

The mixing ratio of the charge-transporting material to the binder resin is preferably in the range of 10 to 500 parts by mass, more preferably in the range of 20 to 250 parts by mass, per 100 parts by mass of the binder resin.

The thickness of the charge-transporting layer varies depending on the properties of the charge-transporting material, the properties of the binder resin, the mixing ratio, etc., but is preferably in the range of 5 to 40 μm, more preferably in the range of 10 to 30 μm.

Antioxidants, electron conductive agents, stabilizers, silicone oil, and the like may be added to the charge transport layer. As for the antioxidant, those described in JP-A-2000-305291 and the like are preferable. As for the electronic conductive agent, those described in JP-A-50-137543 and JP-A-58-76483 are preferred.

<5 Image forming apparatus>
As described above, in the image forming system of the present invention, the apparatus section is particularly called "image forming apparatus". That is, the image forming apparatus according to the present invention is characterized by comprising an electrophotographic photosensitive member, charging means, exposure means, developing means, transfer means and cleaning means.

FIG. 4 is a schematic diagram showing an example of the configuration of the image forming apparatus according to the present invention. The image forming apparatus 100 shown in FIG. 4 is called a tandem-type color image forming apparatus, and includes four sets of image forming units 110Y, 110M, 110C, and 110Bk, a sheet feeding/conveying means 150, and a fixing means 170. have.

A document image reading device SC is arranged on the upper part of the main body of the image forming apparatus 100 .

The image forming units 110Y, 110M, 110C, and 110Bk are arranged side by side in the vertical direction.

The image forming units 110Y, 110M, 110C, and 110Bk include rotating drum-shaped photoreceptors 111Y, 111M, 111C, and 111Bk, and charging units sequentially arranged along the rotation direction of the photoreceptors in the outer peripheral surface region. Means 113Y, 113M, 113C, 113Bk; exposure means 115Y, 115M, 115C, and 115Bk; developing means 117Y, 117M, 117C, and 117Bk; and primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk and cleaning means 119Y, 119M, 119C, and 119Bk.

Toner images of yellow (Y), magenta (M), cyan (C), and black (Bk) are formed on the photoreceptors 111Y, 111M, 111C, and 111Bk, respectively.

Note that FIG. 4 is a schematic diagram for explanation mainly showing the positional relationship of each means of the image forming apparatus, and thus details of the cleaning means are not shown. 119Bk has a brush roller and a cleaning blade, as described above with reference to FIG.

Since the details of the photoreceptor and the cleaning means are as described above, other configurations will be described below. Note that the image forming unit 110Y will be described as an example when the drawings are used for description.

The charging means is means for uniformly charging the surface of the photoreceptor. The charging means includes contact systems such as charging rollers, charging brushes and charging blades, and non-contact systems such as corona chargers (corotron chargers, strokoton chargers, etc.). The contact method has the advantage of generating less harmful ozone gas with the charging process. The non-contact method has the advantage that filming is less likely to occur because proximity discharge is not used as compared with the contact method.

The exposing means is means for forming an electrostatic latent image corresponding to the image by exposing the photoreceptor to which a uniform potential is applied by the charging means, based on the image signal. Exposing means includes, for example, an LED having light emitting elements arranged in an array in the axial direction of the photosensitive member and an imaging element, and a laser optical system.

The developing means (developing machine) is means for supplying toner to the surface of the photoreceptor and developing the electrostatic latent image formed on the surface of the photoreceptor to form a toner image. Specifically, the developing means 117Y shown in FIG. 4 includes a developing roller 118Y that incorporates a magnet and holds developer and rotates, and a DC and/or AC bias voltage is applied between the photosensitive member 111Y and the developing roller 118Y. It is composed of a voltage applying device (not shown) that applies voltage.

The rotation of the developing roller 118Y conveys the toner to the photoreceptor 111Y. Then, the toner thin layer on the developing roller 118Y contacts the photoreceptor 111Y to develop the electrostatic latent image on the photoreceptor 111Y. The developing roller 118Y is connected to a voltage application device. A DC and/or AC bias voltage is applied to the developing roller 118Y by this voltage applying device. By controlling the voltage applied to the developing roller 118Y, the developing bias can be adjusted to a desired value.

Due to the potential difference (development potential difference) between the developing roller 118Y and the potential of the electrostatic latent image carried by the photoreceptor 111Y, an electric field is formed in the developing portion where the developing roller 118Y and the photoreceptor 111Y face each other. . The toner in the developer conveyed to the developing section by the rotation of the developing roller 118Y moves due to the action of the force received from the electric field, and adheres to the electrostatic latent image on the photoreceptor 111Y. By visualizing the electrostatic latent image carried on the photoreceptor 111Y, a toner image corresponding to the shape of the electrostatic latent image is formed on the surface of the photoreceptor 111Y.

A transfer means is a means for transferring a toner image on a photoreceptor to a transfer body (intermediate transfer body or transfer material). A primary transfer roller 133Y shown in FIG. 4 transfers the toner image formed on the photoreceptor 111Y to the intermediate transfer member 131 in the form of an endless belt. The primary transfer roller 133Y is arranged in contact with the intermediate transfer body 131. As shown in FIG.

In the image forming apparatus 100 shown in FIG. 4, the toner images formed on the photosensitive members 111Y, 111M, 111C, and 111Bk are transferred onto the intermediate transfer member 131 by primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk. Then, an intermediate transfer method is adopted in which each toner image transferred on the intermediate transfer member 131 is transferred onto the transfer material P by a secondary transfer roller (secondary transfer means) 217. A direct transfer method may be employed in which the toner image is directly transferred onto the transfer material P by transfer means.

Since the image forming system of the present invention uses toner particles containing a lubricant as an external additive, the lubricant can be supplied to the cleaning means. may be provided.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. In the examples, "parts" or "%" are used, but "mass parts" or "mass%" are indicated unless otherwise specified.

<Preparation of Photoreceptor>
A photoreceptor was produced by the following procedure.

(Conductive support)
A conductive support having a surface roughness Rz of 1.5 (μm) was prepared by cutting the surface of a cylindrical aluminum support having a diameter of 30 mm.

(middle layer)
The following materials were mixed and dispersed in batches for 10 hours using a sand mill. After standing overnight, the mixture was filtered (using a ligimesh 5 μm filter manufactured by Nippon Pall Co., Ltd.) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part by mass Titanium oxide SMT500SAS (manufactured by Tayca) 3 parts by mass Methanol 20 parts by mass

This intermediate layer coating solution was applied onto the conductive support by dip coating to form an intermediate layer having a dry film thickness of 2 μm.

(Charge generation layer)
The following materials were mixed and dispersed for 10 hours using a sand mill to prepare a charge generating layer coating solution. The following titanyl phthalocyanine pigment has a maximum diffraction peak at a position of at least 27.3° in Cu-Kα characteristic X-ray diffraction spectrum measurement. #6000-C manufactured by Denki Kagaku Kogyo Co., Ltd. was used as the polyvinyl butyral resin described below.

Charge generation material: Titanyl phthalocyanine pigment 20 parts by mass Polyvinyl butyral resin 10 parts by mass t-butyl acetate 700 parts by mass 4-methoxy-4-methyl-2-pentanone 300 parts by mass

This charge generation layer coating solution was applied onto the intermediate layer by dip coating to form a charge generation layer having a dry film thickness of 0.3 μm.

(Charge transport layer)
A charge transport layer coating solution was prepared by mixing the following materials. The following polycarbonate resin F (Iupizeta (registered trademark) FPC-6535A, manufactured by Mitsubishi Gas Chemical Company, Inc.) is a copolymer of bisphenol Z and a dihydroxy compound, and has a viscosity average molecular weight of 33,000. In addition, Irganox 1010 manufactured by BASF Japan was used as an antioxidant.

Polycarbonate resin F 100 parts by mass Charge transport material (CTM-47) 50 parts by mass Antioxidant 2 parts by mass Tetrahydrofuran 540 parts by mass Toluene 135 parts by mass Silicone oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 0.3 parts by mass

This charge transport layer coating solution was applied onto the charge generation layer by dip coating to form a charge transport layer having a dry film thickness of 20 μm.

(Surface protective layer)
The following materials were mixed to prepare a mixed solution for surface modification of metal oxide particles. As the tin oxide particles, those manufactured by CIK Nanotech Co., Ltd. having a number average primary particle diameter of 20 nm and a volume resistivity of 1.05×10 ⁵ Ω·cm were used. As the surface modifier, the following compound S-15 was used as a compound having a radically polymerizable functional group.

Compound S-15: _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _OCH3 ) ₃

Metal oxide particles (tin oxide particles) 100 parts by mass Surface modifier (compound S-15) 30 parts by mass Toluene/isopropyl alcohol = 1/1 (mass ratio) 300 parts by mass

The mixed liquid prepared above was placed in a sand mill together with zirconia beads, and stirred at about 40° C. at a rotation speed of 1500 rpm. The treated mixture was then taken out and put into a Henschel mixer and stirred at a rotation speed of 1500 rpm for 15 minutes. Thereafter, the tin oxide particles were dried at 120° C. for 3 hours to complete surface modification of the tin oxide particles with the compound having a radically polymerizable functional group, thereby obtaining surface-modified tin oxide particles.

It was confirmed that the surface of the tin oxide particles was coated with the compound S-15 by detecting Si peaks using an X-ray fluorescence spectrometer "XRF-1700 (manufactured by Shimadzu Corporation)".

Next, the following materials were mixed and stirred, and sufficiently dissolved and dispersed to prepare a surface protective layer coating solution.

Surface-modified tin oxide particles 50 parts Polymerizable compound (compound Mc-1) 100 parts Charge transport material (compound CTM-13) 15 parts Polymerization initiator (polymerization initiator 3-2) 10 parts Chain transfer agent (2-mercapto benzoxazole) 10 parts 2-butanol 320 parts tetrahydrofuran 80 parts

This surface protective layer coating solution was applied onto the charge transport layer using a circular slide hopper coating machine. After coating, ultraviolet rays were irradiated for 1 minute using a metal halide lamp to form a surface protective layer having a dry film thickness of 3.0 μm.

A photoreceptor was produced by the above procedure.

<Preparation of Toner Particles>
Toner Particle 1 was produced by the following procedure.

(Preparation of Dispersion Liquid of Resin Fine Particles for Core Portion)
A surfactant solution prepared by dissolving 4 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 3040 parts by mass of ion-exchanged water is charged into a reaction vessel equipped with a stirring device, a temperature sensor, a cooling pipe, and a nitrogen introducing device, The internal temperature was raised to 80° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.

To this surfactant solution, a polymerization initiator solution in which 10 parts by mass of a polymerization initiator (potassium persulfate: KPS) is dissolved in 400 parts by mass of ion-exchanged water is added, the temperature is set to 75 ° C., and then 532 parts by mass of styrene. 200 parts by mass of n-butyl acrylate, 68 parts by mass of methacrylic acid and 16.4 parts by mass of n-octylmercaptan was added dropwise over 1 hour.

This system was heated and stirred at 75° C. for 2 hours to carry out polymerization (first stage polymerization) to prepare a dispersion of fine resin particles [A]. The weight-average molecular weight (Mw) of the fine resin particles [A] prepared by the first-stage polymerization was 16,500.

Measurement of the weight average molecular weight (Mw), using "HLC-8220" (manufactured by Tosoh Corporation) and column "TSKguardcolumn + TSKgelSuperHZM-M triplet" (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran as a carrier solvent (THF) is flowed at a flow rate of 0.2 mL/min, and the measurement sample is dissolved in tetrahydrofuran to a concentration of 1 mg/mL under the dissolution conditions of treating for 5 minutes using an ultrasonic disperser at room temperature, and then the pore size is 0. A sample solution is obtained by treating with a 2 μm membrane filter, 10 μl of this sample solution is injected into the apparatus together with the above carrier solvent, and detected using a refractive index detector (RI detector). The distribution is calculated using a calibration curve measured using monodisperse polystyrene standard particles. As standard polystyrene samples for calibration curve measurement, Pressure Chemical's molecular weights of 6×10 ² , 2.1×10 ³ , 4×10 ³ , 1.75×10 ⁴ , 5.1×10 ⁴ , 1 Using 1×10 ⁵ , 3.9×10 ⁶ , 8.6×10 ⁵ , 2×10 ⁶ , and 4.48×10 ⁶ , standard polystyrene samples of at least 10 points are measured, and a calibration curve is obtained. It was created. A refractive index detector was used as a detector.

A monomer mixture consisting of 101.1 parts by mass of styrene, 62.2 parts by mass of n-butyl acrylate, 12.3 parts by mass of methacrylic acid, and 1.75 parts by mass of n-octyl mercaptan was placed in a flask equipped with a stirring device. 93.8 parts by mass of paraffin wax "HNP-57" (manufactured by Nippon Seiro Co., Ltd.) was added as a release agent to the mixture, and heated to 90°C to dissolve.

On the other hand, a surfactant solution prepared by dissolving 3 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 1560 parts by mass of ion-exchanged water was heated to 98° C., and the above-mentioned resin fine particles [A 32.8 parts by mass (in terms of solid content) of the dispersion liquid of ] is added, and the monomer solution containing the paraffin wax is added to 8 A dispersion containing emulsified particles having a dispersed particle size of 340 nm was prepared by mixing and dispersing for a period of time.

Next, a polymerization initiator solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of deionized water was added to the emulsified particle dispersion. Polymerization (second-stage polymerization) was performed by heating and stirring this system at 98° C. for 12 hours to prepare a dispersion of fine resin particles [B]. The weight-average molecular weight (Mw) of the fine resin particles [B] prepared by the second-stage polymerization was 23,000.

A polymerization initiator solution prepared by dissolving 5.45 parts by mass of potassium persulfate in 220 parts by mass of ion-exchanged water was added to the fine resin particles [B], and 293.8 parts by mass of styrene was added at a temperature of 80°C. A monomer mixture consisting of 154.1 parts by mass of n-butyl acrylate and 7.08 parts by mass of n-octyl mercaptan was added dropwise over 1 hour.

After the completion of the dropwise addition, polymerization (third-stage polymerization) was carried out by heating and stirring for 2 hours, and then cooled to 28° C. to obtain a dispersion liquid of fine resin particles for the core portion. The weight average molecular weight (Mw) of the fine resin particles for the core portion was 26,800. Further, the volume-based average particle diameter of the fine resin particles for the core portion was 125 nm. Furthermore, the glass transition temperature (Tg) of the fine resin particles for the core portion was 30.5°C.

(Preparation of Dispersion Liquid of Resin Fine Particles for Shell Layer)
In the first-stage polymerization in the preparation of the dispersion liquid of the fine resin particles for the core portion, 548 parts by mass of styrene, 156 parts by mass of 2-ethylhexyl acrylate, 96 parts by mass of methacrylic acid, and 16.5 parts by mass of n-octylmercaptan were used. Polymerization reaction and post-reaction treatment were carried out in the same manner except that a different monomer mixture was used to prepare a dispersion of fine resin particles for shell layer. The glass transition temperature (Tg) of the fine resin particles for the shell layer was 49.8°C.

(Preparation of colorant fine particle dispersion)
90 parts by mass of sodium dodecyl sulfate was added to 1,600 parts by mass of ion-exchanged water, and while stirring this solution, 420 parts by mass of carbon black "Regal 330R" (manufactured by Cabot Corporation) was gradually added. Mix" (manufactured by M Technic Co., Ltd.) was used for dispersion treatment to prepare a colorant fine particle dispersion liquid in which the colorant fine particles were dispersed.

The particle size of the fine colorant particles in this fine colorant particle dispersion was measured using an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Denshi Co., Ltd.) and found to be 110 nm.

(Formation of core portion)
420 parts by mass of resin fine particle dispersion for the core part (in terms of solid content), 900 parts by mass of ion-exchanged water, and 100 parts by mass of colorant fine particle dispersion are mixed with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device. Place in an attached reaction vessel and stir.

After adjusting the temperature in the reaction vessel to 30° C., a 5 mol/L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 8-11.

Then, an aqueous solution prepared by dissolving 60 parts by mass of magnesium chloride hexahydrate in 60 parts by mass of ion-exchanged water was added at 30° C. over 10 minutes while stirring. After standing for 3 minutes, the temperature was started to rise, and the system was heated to 80° C. (core formation temperature) over 80 minutes.

In this state, the particle size of the particles was measured using a flow-type particle image analyzer "FPIA2100" (manufactured by Sysmex Corporation). part dissolved in 1,000 parts by mass of ion-exchanged water to stop particle size growth, and furthermore, as aging treatment, fusion bonding is performed by heating and stirring for 1 hour at a liquid temperature of 80 ° C. (core part aging temperature). was continued to form a core portion.

The circularity of the core portion was 0.930 when measured with a flow type particle image analyzer "FPIA2100" (manufactured by Sysmex Corporation).

In addition, the core portion was observed at 10,000 times by scanning transmission electron microscopy using a field emission scanning electron microscope "JSM-7401F" (manufactured by JEOL Ltd.). It was confirmed that no agent-dispersed fine particles remained.

(Formation of shell layer)
Then, 46.8 parts by mass (in terms of solid content) of a dispersion liquid of fine resin particles for shell layer was added at 65°C. Further, an aqueous solution prepared by dissolving 2 parts by mass of magnesium chloride hexahydrate in 60 parts by mass of ion-exchanged water was added over 10 minutes. After that, the temperature was raised to 80° C. (shell formation temperature), and stirring was continued for 1 hour to fuse the particles of the resin fine particles for the shell layer to the surface of the core portion.

Thereafter, aging treatment was performed at 80° C. (shell aging temperature) to a predetermined degree of circularity to form a shell layer. Here, an aqueous solution prepared by dissolving 40.2 parts by mass of sodium chloride in 1000 parts by mass of ion-exchanged water was added, and the mixture was cooled to 30°C at a rate of 8°C/min. The generated fused particles were filtered and washed repeatedly with deionized water at 45°C. Then, it was dried with hot air at 40°C.

Through the above procedure, toner base particles having a shell layer on the surface of the core portion were obtained. The toner base particles had a volume-based average particle size of 5.9 μm, a glass transition temperature (Tg) of 31° C., and an average circularity of 0.960.

(Addition of external additive)
An external additive was added to the toner base particles prepared above in the following procedure. Two types of fatty acid metal salt particles were added as lubricants. Hereinafter, of the two types of lubricants added in the production of each toner, the lubricant with the smaller volume-based average particle size is referred to as "lubricant (1)", and the lubricant with the larger volume-based average particle size is referred to as "lubricant (2). )”.

To 100 parts by mass of the dried toner base particles, 0.25 parts by mass of zinc stearate particles (volume-based average particle diameter 1.0 μm, manufactured by NOF Corporation) as a lubricant (1) is added, and a Henschel mixer "FM10B" is added. (manufactured by Mitsui Miike Kakoki Co., Ltd.), the mixture was mixed for 3 minutes at a stirring blade peripheral speed of 15 m/sec and a treatment temperature of 30°C.

Next, 0.75 parts by mass of small-diameter silica fine particles (“RX-200” fumed silica HMDS treatment, number average particle diameter 12 nm; manufactured by Nippon Aerosil Co., Ltd.), spherical silica fine particles (“X-24 9600” silica HMDS treatment by sol-gel manufacturing method 1.50 parts by mass of number average particle size 80 nm; manufactured by Shin-Etsu Chemical Co., Ltd.), 0.1 parts by mass of zinc stearate particles (volume-based average particle size 15.0 μm, manufactured by NOF Corporation) as lubricant (2), 0.5 parts by mass of calcium titanate particles (“TC110” number average primary particle size 300 nm, silicone oil treatment, manufactured by Titan Kogyo Co., Ltd.) are added as metal oxide fine particles with a high polishing effect, and a Henschel mixer “FM10B” (Mitsui Miike Kakoki) is added. Co., Ltd.), mixing was performed for 15 minutes at a stirring blade peripheral speed of 40 m/sec and a processing temperature of 30°C.

Thereafter, toner particles 1 were produced by removing coarse particles using a sieve with an opening of 90 μm.

Toner Particles 2 to 9 were produced by replacing Lubricant (1) and Lubricant (2) added in the production of Toner Particle 1 with fatty acid metal salt particles (both manufactured by NOF CORPORATION) shown in Table I. In toner particles 2 and 3, only one kind of fatty acid metal salt particles was added.

In Table I, "addition amount [parts by mass]" is the amount added to 100 parts by mass of the toner base particles. "ZnSt", "MgSt" and "CaSt" are respectively "zinc stearate", "magnesium stearate" and "calcium stearate".

The volume-based particle size distribution of the lubricant in toner particles 1 to 9 was measured by the following procedure.

5 g of toner particles and 50 mL of 0.7% sodium dodecylbenzenesulfonate aqueous solution were placed in a 100 mL beaker and dispersed by stirring at 300 rpm for 5 minutes with a magnetic stirrer "Model MS500D" (manufactured by Yamato Kagaku).

After the above dispersion, the toner dispersion was subjected to ultrasonic vibration for 10 minutes using an ultrasonic homogenizer US-1200T (manufactured by Nippon Seiki Seisakusho) at a frequency of 20 kHz, an OUTPUT scale of 3, and an output of TUNING scale of 6. .

The toner dispersion was separated by centrifugal separator "Model H-900" (manufactured by Kokusan Co., Ltd.) under the following conditions.
Rotor: PC-400 (radius 18.1 cm)
Rotation speed: 1200rpm (292G)
Time: 10 minutes

After centrifugation, 40 mL of the supernatant liquid was collected using a pipette so that the sedimented toner base particles did not enter.

The volume-based particle size of the particles contained in the collected supernatant is measured using a flow-type particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation) with a measurement range of 0.6 to 400 μm. The volume-based particle size distribution of

The volume-based particle size distribution of the lubricant in toner particles 1, 4 to 9 had two peaks on the small particle size side and the large particle size side. The volume-based average particle size of a lubricant having a peak on the small particle size side (lubricant on the small particle size side) and the volume-based average particle size of a lubricant having a peak on the large particle size side (lubricant on the large particle size side) are As shown in Table II.

The volume-based particle size distribution of the lubricant in toner particles 2 and 3 did not have two peaks on the small particle size side and the large particle size side.

<Method of making brush roller>
A pile fabric obtained by weaving the following pile into a base fabric was wound around the outer layer of an aluminum shaft having an outer diameter of 13 mm and a length of 330 mm, and fixed with an adhesive to prepare a brush roller 1.

(pile)
Material: Polyester Shape: Cut pile Young's modulus: 45cN/dtex
Pile bundle fineness X: 150 dtex
Pile density: 80KF/inch ²
Pile length: 3mm

Brush rollers 2 to 17 were produced by changing the pile woven into the pile fabric used in the production of brush roller 1 as shown in Table II.

<Image forming system>
The photoreceptor prepared above was mounted on a commercially available full-color multifunction machine "bizhub C650i" (manufactured by Konica Minolta). Imaging Systems 1-26 were also modified to accommodate brush rollers, using toner particles 1-9 and brush rollers 1-17 in the combinations listed in Table II. The brush roller was provided upstream of the cleaning blade in the rotation direction of the photoreceptor.

The rotation of the brush roller was in the with direction (direction in which the surface moves in the same direction) with respect to the rotation direction of the photosensitive member, and the rotation speed was 600 rpm. The number of rotations of the brush roller was controlled by an applied voltage by installing an external DC drive motor.

<Evaluation of Difference in Lubricant Adhesion Amount on Photoreceptor>
In a low-temperature and low-humidity environment (temperature of 10° C., humidity of 10% RH), 1000 sheets of a pattern image having a printing portion and a non-printing portion on both sides with respect to the rotating direction of the photoreceptor were continuously output. Thereafter, the surface protective layer of the area corresponding to the printed portion of the pattern image (toner-applied area) and the surface protective layer of the area corresponding to the non-printed portion of the pattern image (non-toner-applied area) were each removed by 5 mm from the photoreceptor. A corner was cut off and this was used as a measurement sample.

By X-ray photoelectron spectroscopy (ESCA: Electron Spectroscopy for Chemical Analysis), the abundance ratio "atom%" of metal derived from the fatty acid metal salt constituting the lubricant was measured, and this was used as a substitute for the lubricant adhesion amount.

Using an X-ray photoelectron spectrometer “K-Alpha” (manufactured by Thermo Fisher Scientific), quantitative analysis was performed on the ratio of elements contained in the measurement sample under the following measurement conditions.

(Measurement condition)
X-ray: Al monochrome source Acceleration: 12 kV, 6 mA
Resolution: 50 eV
Beam system: 400 μm
Step size: 0.1 eV

The elements to be quantitatively analyzed were all elements that could exist on the surface of the measurement sample, such as elements contained in the constituents of the surface protective layer and elements contained in the constituents of the toner particles.

From the peak area of each element quantitatively analyzed, the relative sensitivity factor was used to calculate the abundance ratio "atom %" of the metal derived from the fatty acid metal salt constituting the lubricant. The difference between the value measured from the measurement sample of the surface protective layer in the toner-applied area and the value measured from the measured sample of the surface protective layer in the non-toner-applied area was used as the evaluation result. The evaluation results are shown in Table II.

<Evaluation of image memory suppression effect>
In a low-temperature and low-humidity environment (temperature of 10° C., humidity of 10% RH), 1000 sheets of a pattern image having a printing portion and a non-printing portion on both sides with respect to the rotating direction of the photoreceptor were continuously output. After that, one full-surface halftone image was output.

Of this full-surface halftone image, the reflection density (D1) on the same side as the printed portion of the pattern image and the reflection density (D0) on the same side as the non-printed portion of the pattern image were measured. "Macbeth RD920" (manufactured by Macbeth) was used as a measuring device.

A reflection density difference ΔD (D1−D0) was calculated, and the effect of suppressing image memory was evaluated according to the following criteria. The evaluation results are shown in Table II. ◯ or above was determined to be acceptable.
◎: Reflection density difference ΔD is less than 0.1 ○: Reflection density difference ΔD is 0.1 or more and less than 0.3 x: Reflection density difference ΔD is 0.3 or more

<Abrasion resistance evaluation>
Under the environment of temperature 23° C. and humidity 50% RH, 300,000 sheets of a character chart corresponding to a printing rate of 5% were printed continuously on both sides. After that, the thickness of the surface protective layer of the photoreceptor was measured using an eddy current film thickness measuring machine "Fisherscope MMS PC" (manufactured by Fisher Instruments Co., Ltd.).

The amount of wear of the surface protective layer was calculated from the measured thickness, and the wear resistance was evaluated according to the following criteria. The evaluation results are shown in Table II. ◯ or above was determined to be acceptable.
◎: Wear amount is less than 0.2 μm ○: Wear amount is 0.2 μm or more and less than 0.4 μm ×: Wear amount is 0.4 μm or more

From the above examples, it can be seen that the electrophotographic image forming system of the present invention achieves both an improvement in abrasion resistance in long-term use of an electrophotographic photoreceptor and a suppression of image memory.

100 Image forming apparatuses 110Y, 110M, 110C, 110Bk Image forming units 111Y, 111M, 111C, 111Bk, 111 Electrophotographic photosensitive members 113Y, 113M, 113C, 113Bk Charging means 115Y, 115M, 115C, 115Bk Exposure means 117Y, 117M, 117C , 117Bk developing means 118Y, 118M, 118C, 118Bk developing rollers 119Y, 119M, 119C, 119Bk cleaning means 133Y, 133M, 133C, 133Bk transferring means (primary transfer rollers)
120 brush roller 121 cleaning blade 122 support member

Claims (4)

An electrophotographic imaging system for forming an image using an electrostatic image developing toner comprising toner particles, comprising:
an electrophotographic photosensitive member, charging means, exposure means, developing means, transfer means and cleaning means,
the toner particles contain toner base particles and a lubricant as an external additive;
The volume-based particle size distribution of the lubricant has two peaks on the small particle size side and the large particle size side, and the volume-based average particle size of the lubricant having the peak on the small particle size side is 3.0 μm or less. , the volume-based average particle size of the lubricant having a peak on the large particle size side is larger than the volume-based average particle size of the toner base particles;
The cleaning means has a brush roller having a plurality of pile bundles, and a cleaning blade provided downstream of the brush roller in the rotation direction of the electrophotographic photosensitive member,
An electrophotographic image forming system, wherein the following formulas (1) and (2) are satisfied, where X is the pile bundle fineness [dtex] of the brush roller and Y is the pile density [KF/inch ² ].
Formula (1): 100≤Y≤250
Formula (2): 0.7≤X/Y≤2.2 2. The electrophotographic image forming system according to claim 1, wherein the electrophotographic photoreceptor has a surface protective layer containing a cured resin. 3. The electrophotographic imaging system of claim 1, wherein the lubricant is particles containing zinc stearate as a main component. 4. The electrophotographic image forming system according to any one of claims 1 to 3, wherein a Young's modulus of the piles forming the pile bundle is in the range of 25 to 70 cN/dtex.

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