JP2016138936A - Electrophotographic photoreceptor, electrophotographic process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact electrophotographic photoreceptor that can achieve dispersibility, wear resistance, and electrical characteristics of silica particles, and can save energy in a high-speed image forming apparatus.SOLUTION: There is provided an electrophotographic photoreceptor including a charge generating layer and a charge transport layer in this order on a conductive substrate, where the charge transport layer is the outermost layer and contains a charge transport material, binder resin, resin having a polysiloxane structure, and silica particles; the resin having a polysiloxane structure is a polycarbonate resin or a polyester resin; the average primary particle diameter of the silica particles is 0.2 μm or more and 0.9 μm or less.SELECTED DRAWING: None

Description

  The present invention relates to an electrophotographic photosensitive member, an image forming apparatus, and an electrophotographic cartridge used for a copying machine, a printer, and the like.

In recent years, electrophotographic technology is widely used not only in the field of copying machines but also in the field of various printers because it can obtain images of immediacy and high quality.
As for photoconductors that are the core of electrophotographic technology, in recent years, photoconductors using organic photoconductive materials that have the advantages of non-polluting, easy film formation, easy manufacture, etc. Has been developed. In particular, a stacked type photoconductor composed of a charge generation layer and a charge transfer layer that separates the function of absorbing light to generate charges and the function of transporting the generated charges has become the mainstream. Currently, these photoreceptors are widely used in the field of image forming apparatuses such as copying machines and laser printers.

  In order to form an image by electrophotography, the surface of the photoconductor is charged, image exposed and developed to form a toner image, and the toner image is transferred and fixed on a transfer material to obtain an image. The photoreceptor is used repeatedly over a long period of time after residual toner is cleaned. Although the photoreceptor is worn by repeated use, the organic photoreceptor is generally inferior in abrasion resistance as compared with the inorganic photoreceptor. Therefore, measures such as development of a binder resin (Patent Document 1) having a high printing durability and a surface protective layer (Patent Documents 2 to 4) have been taken. For example, a technology (Patent Document 5) in which fine particles such as titanium oxide and tin oxide are contained in the surface protective layer and the absorbance per 1 μm of the film thickness of the surface protective layer is set to a specific value, and a radical polymerizable monomer in the surface protective layer Further, a technique (Patent Document 6) containing a crosslinkable resin and a filler, and a technique (Patent Documents 7 to 10) containing silica particles in a surface protective layer are known. On the other hand, a technique in which a protective layer is not provided and the outermost surface layer is a charge transport layer is also known (Patent Document 11). In that case, in a system to which fine particles are added, a coating solution and a photoreceptor for forming the surface layer It is required to maintain electrical characteristics including repetitive characteristics of normal temperature and normal humidity and high temperature and high humidity while maintaining good dispersion stability even in the state of manufacturing.

  In recent years, even in a high-speed image forming apparatus such as a high-end MFP, miniaturization and energy saving of an electrophotographic apparatus have been advanced. In general, a high-speed machine has a long printing life, so that the wear resistance required for the photosensitive member is increased. However, since it is difficult to improve the material in the prior art, countermeasures have been taken by increasing the outer diameter of the photoconductor, so that the size of the electrophotographic apparatus tends to increase. In addition to being a high-speed machine, LEDs have been used in electrophotographic apparatuses for energy saving, and it has become necessary to maintain electrical characteristics while achieving both wear resistance. . In order to provide an electrophotographic photoreceptor satisfying these characteristics, it is necessary to develop a highly functional charge transport material that exhibits high mobility and a sufficiently low residual potential upon exposure. In order to solve these problems, studies have been made on a charge transport material in which a π-electron system such as a stilbene skeleton is extended (Patent Document 12).

JP 2006-053549 A JP 2000-66424 A JP 2000-66425 A JP 2000-206715 A JP 2006-99035 A JP 2008-26689 A JP 2003-140373 A JP 2012-98639 A Japanese Patent No. 3844258 Japanese Patent No. 3859086 Japanese Patent Application Laid-Open No. 2014-191079 JP 2013-025189 A

  Of the above-mentioned techniques, the technique of containing silica particles in the surface layer is simple and can improve wear resistance, but is insufficient from the viewpoint of dispersibility of silica in the state of the photoreceptor. In addition, the wear resistance depends largely on the image forming method of the image forming apparatus. The present invention solves such problems, and provides an electrophotographic photosensitive member capable of achieving both dispersibility, abrasion resistance, and electrical characteristics of silica particles, and further, is compact and saves energy even in a high-speed image forming apparatus. It is to make it feasible.

As a result of intensive studies, the inventor has achieved both the dispersibility, abrasion resistance, and electrical properties of silica particles by including a charge transport material having a specific structure, silica particles, and a binder resin having a specific structure in the photosensitive layer. I found out that I can do it. That is, the present invention resides in the following <1> to <8>.
<1> In an electrophotographic photosensitive member having a charge generation layer and a charge transport layer in this order on a conductive substrate, the charge transport layer is the outermost layer, a charge transport material, a binder resin, a resin having a polysiloxane structure, And a silica resin, wherein the charge transport material is represented by the following formula (1), and the resin having the polysiloxane structure is a polycarbonate resin or a polyester resin having a structure represented by the following general formula (2): An electrophotographic photoreceptor, wherein the silica particles have an average primary particle size of 0.2 μm or more and 0.9 μm or less.

(In formula (1), R ^{1 to} R ⁸ each independently represents hydrogen, an alkoxy group or an alkyl group.)

(In formula (2), R ⁹ and R ¹⁰ each independently represents a methyl group, an ethyl group, or a phenyl group.)
<2> The electrophotographic photosensitive member according to <1>, wherein an average primary particle size of the silica particles is 0.3 μm or more and 0.8 μm or less.
<3> The electrophotographic photosensitive member according to <1> or <2>, wherein the content of the silica particles is 3 wt% or more and 30 wt% or less of the entire charge transport layer.
<4> The electrophotographic photosensitive member according to any one of <1> to <3>, wherein the silica particles are surface-treated with a reactive organosilicon compound.
<5> The electrophotographic photosensitive member according to any one of <1> to <4>, wherein the conductive substrate is cylindrical and has an outer diameter of 10 mm to 24 mm.
<6> The electrophotographic photosensitive member according to any one of <1> to <5>, a charging unit for charging the electrophotographic photosensitive member, and an electrostatic latent image by performing image exposure on the charged electrophotographic photosensitive member. An electrophotographic cartridge comprising: an image exposing unit for forming the electrostatic latent image; and a developing unit for developing the electrostatic latent image with toner, wherein the developing unit is non-contact development.
<7> An image forming apparatus using the electrophotographic cartridge according to <6>.
<8> The image forming apparatus according to <7>, wherein the image exposure unit is an LED.

  According to the present invention, an electrophotographic photosensitive member having both dispersibility, abrasion resistance, and electrical characteristics of silica particles can be provided, and compact and energy saving can be realized even in a high-speed image forming apparatus.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus of the present invention. 1 is an X-ray diffraction pattern of oxytitanium phthalocyanine used in Examples. 1 is an X-ray diffraction pattern of oxytitanium phthalocyanine used in Examples.

  Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and is appropriately modified and implemented without departing from the spirit of the present invention. can do.

<Electrophotographic photoreceptor>
The charge generation layer is formed directly on the conductive support or after forming a conductive layer, an undercoat layer or the like. A charge transport layer is formed on the charge generation layer, and the charge transport layer becomes the outermost surface layer.

[Conductive support]
There is no particular limitation on the conductive support, but for example, metal materials such as aluminum, aluminum alloy, stainless steel, copper, and nickel, and conductive powder such as metal, carbon, and tin oxide are added to impart conductivity. A resin material, a resin, glass, paper, or the like on which a conductive material such as aluminum, nickel, or ITO (indium tin oxide) is deposited or applied on the surface is mainly used. These may be used alone or in combination of two or more in any combination and ratio. As a form of the conductive support, a drum form, a sheet form, a belt form or the like is used. Further, a conductive material having an appropriate resistance value may be used on a conductive support made of a metal material in order to control conductivity and surface properties and to cover defects.

Moreover, when using metal materials, such as an aluminum alloy, as an electroconductive support body, you may use, after giving an anodic oxide film. When an anodized film is applied, it is desirable to perform a sealing treatment by a known method.
The surface of the support may be smooth, or may be roughened by using a special cutting method or by performing a roughening treatment. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support. In order to reduce the cost, it is possible to use the drawing tube as it is without performing the cutting process.

  The conductive substrate is preferably cylindrical. In that case, the outer diameter is usually 5 mm or more, and preferably 10 mm or more from the viewpoint of wear. Moreover, it is 60 mm or less normally, Preferably it is 24 mm or less from a viewpoint of size reduction.

[Underlayer]
In the present invention, the undercoat layer is not essential, but when an undercoat layer is provided, any undercoat layer can be provided. As the undercoat layer, a binder alone can be used, but it is preferable in terms of electrical characteristics and the like to contain an inorganic filler such as metal oxide particles.

As the metal oxide particles, those having high dispersion stability of the coating liquid are preferable, and specific examples include silica, alumina, titanium oxide, barium titanate, zinc oxide, lead oxide, and indium oxide. Among these, metal oxide particles exhibiting n-type semiconductor characteristics are preferable, titanium oxide, zinc oxide, and tin oxide are more preferable, and titanium oxide is most preferable.
Titanium oxide can be either crystalline or amorphous, but in the case of crystalline, the crystalline form may be any of anatase, rutile, or brookite, but anatase for reasons such as water absorption and surface treatment efficiency. A type or rutile type is generally used. Particularly preferably, a rutile type is used.

  As for the particle size of the metal compound particles, those having an average particle size of usually 100 nm or less are preferable, and 10 to 60 nm is particularly preferable from the viewpoint of dispersion stability in the coating solution. The particle size of the particles used in the coating solution may be uniform or a composite system having different particle sizes. In the case of a composite system having different particle sizes, those having a maximum particle size peak near 150 nm and a particle size distribution with a minimum particle size of about 30 nm to about 500 nm are preferable. And 0.03 μm may be mixed and used.

  The metal oxide particles are preferably surface-treated with an organometallic compound or the like. The surface treatment can be produced by a dry method or a wet method. That is, in the dry method, it can be produced by a method in which a surface treatment agent is mixed with metal oxide particles to coat the metal oxide particles and, if necessary, heat treatment is performed. In the wet method, the metal oxide particles and a mixture of the surface treatment agent of the present invention mixed with an appropriate solvent are thoroughly stirred until they are uniformly attached or mixed with media, and then dried, if necessary. It can manufacture by the method of heat-processing.

  The surface treating agent is preferably a reactive organometallic compound. For example, methyl hydrogen polysiloxane, a silane treating agent having the following structure, and among them, methyldimethoxysilane is particularly preferable. A silane coupling agent having an acrylic group is also preferable, and 3-acryloxypropylmethoxysilane is particularly preferable.

(M represents SiR ^3. R represents a hydrogen atom or an alkyl group, R ¹ and R ² represent an alkyl group, and R ³ represents an alkyl group or an alkoxy group.)
Regarding the amount of the surface treatment agent, if the treatment amount is too small, the effect of the surface treatment cannot be obtained, and if the treatment amount is too large, there is a treatment agent that is not modified on the particle surface, and during the coating process, etc. This may cause repelling of the coating film. Therefore, the amount of the surface treatment agent is preferably adjusted according to the type of the metal oxide particles, and the lower limit is usually 0.3 parts by mass or more, preferably 1 part by mass with respect to the metal oxide particles used. On the other hand, the upper limit is usually 20 parts by mass or less, preferably 10 parts by mass or less.

  As the binder resin contained in the undercoat layer, resin materials such as polyvinyl acetal, polyamide resin, phenol resin, polyester, epoxy resin, polyurethane, and polyacrylic acid can be used. Among these, a polyamide resin having excellent adhesion to the support and low solubility in a solvent used in the charge generation layer coating solution is preferable. Among polyamide resins, a copolymer polyamide having a cycloalkane ring structure as a constituent component is preferable, and a copolymer polyamide having a cyclohexane ring structure as a constituent component is more preferable.

The ratio between the metal oxide particles and the binder resin can be arbitrarily selected, but is 0.5 to 8 parts by mass with respect to 1 part by mass of the binder resin in terms of liquid stability, coating properties, and electrical characteristics. The range is preferable, and the range of 2 parts by mass to 5 parts by mass is more preferable.
If the film thickness of the undercoat layer is too thin, the effect on local charging failure will not be sufficient, and conversely if it is too thick, the residual potential will increase or the adhesive strength between the conductive substrate and the photosensitive layer will decrease. Cause. In the present invention, the thickness of the undercoat layer is preferably 0.1 to 20 μm, more preferably 2 to 10 μm, still more preferably 3 to 6 μm.

The volume resistance value of the undercoat layer is usually 1 × 10 ¹¹ Ω · cm or more, preferably 1 × 10 ¹² Ω · cm or more, and usually 1 × 10 ¹⁴ Ω · cm or less, preferably 1 × 10 ¹³ Ω. -It is cm or less.
In order to obtain a subbing coating solution containing metal oxide particles and a binder resin, a metal oxide treated with a pulverization or dispersion treatment device such as a planetary mill, ball mill, sand mill, bead mill, paint shaker, attritor, or ultrasonic wave. The particle slurry may be mixed with a binder resin or a solution obtained by dissolving the binder resin in an appropriate solvent, and dissolved and stirred. Conversely, metal oxide particles may be added to the binder resin solution, and pulverization or dispersion treatment may be performed with the above-described dispersion apparatus.

[Charge generation layer]
The charge generation layer is formed by binding a charge generation material with a binder resin. Examples of the charge generation material include inorganic photoconductive materials such as selenium and its alloys, cadmium sulfide, and organic photoconductive materials such as organic pigments, but organic photoconductive materials are preferred, especially organic pigments. Is preferred. Examples of organic pigments include phthalocyanine pigments, azo pigments, dithioketopyrrolopyrrole pigments, squalene (squarylium) pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments. . Among these, phthalocyanine pigments or azo pigments are particularly preferable. When organic pigments are used as the charge generating substance, usually, fine particles of these organic pigments are used in the form of a dispersion layer bound with various binder resins.

  When a metal-free phthalocyanine compound or a metal-containing phthalocyanine compound is used as the charge generation material, a photosensitive member having a high sensitivity to a laser beam having a relatively long wavelength, for example, a laser beam having a wavelength around 780 nm, is obtained. When an azo pigment such as diazo or trisazo is used, it is sufficient for white light, laser light having a wavelength around 660 nm, or laser light having a relatively short wavelength, for example, laser having a wavelength around 450 nm or 400 nm. A photosensitive member having a high sensitivity can be obtained.

When an organic pigment is used as the charge generating material, a phthalocyanine pigment or an azo pigment is particularly preferable. The phthalocyanine pigment provides a photosensitive material with high sensitivity to a laser beam having a relatively long wavelength, and the azo pigment has a sufficient sensitivity to white light and a laser beam having a relatively short wavelength. , Each is excellent.
When using a phthalocyanine pigment as a charge generation material, specifically, metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, aluminum or other metal or oxide thereof, halide, water Those having crystal forms of coordinated phthalocyanines such as oxides and alkoxides, and phthalocyanine dimers using oxygen atoms as bridging atoms are used. In particular, titanyl phthalocyanines (also known as oxytitanium) such as X-type, τ-type metal-free phthalocyanine, A-type (also known as β-type), B-type (also known as α-type), D-type (also known as Y-type), which are highly sensitive crystal types Phthalocyanine), vanadyl phthalocyanine, chloroindium phthalocyanine, hydroxyindium phthalocyanine, chlorogallium phthalocyanine such as type II, hydroxygallium phthalocyanine such as type V, μ-oxo-gallium phthalocyanine dimer such as type G and type I, type II, etc. The [mu] -oxo-aluminum phthalocyanine dimer is preferred.

  Among these phthalocyanines, A-type (also known as β-type), B-type (also known as α-type), and powder X-ray diffraction angle 2θ (± 0.2 °) are 27.1 ° or 27.3 °. D-type (Y-type) titanyl phthalocyanine, II-type chlorogallium phthalocyanine, V-type and 28.1 ° have the strongest peaks, and 26.2 ° have peaks A hydroxygallium phthalocyanine, G-type μ-oxo-gallium, having a clear peak at 28.1 ° and a half width W of 25.9 ° of 1 ° ≦ W ≦ 0.4 ° A phthalocyanine dimer and the like are particularly preferable.

  The phthalocyanine compound may be a single compound or several mixed or mixed crystal states. As the mixed state that can be put in the phthalocyanine compound or crystal state here, those obtained by mixing the respective constituent elements later may be used, or they may be mixed in the production / treatment process of the phthalocyanine compound such as synthesis, pigmentation, and crystallization. It may be the one that caused the condition. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known. In order to generate a mixed crystal state, as described in JP-A-10-48859, two types of crystals are mixed, mechanically ground and made amorphous, and then converted into a specific crystal state by solvent treatment. The method of doing is mentioned.

  When an azo pigment is used as the charge generation material, various bisazo pigments and trisazo pigments are preferably used. When an organic pigment is used as the charge generation material, one kind may be used alone, or two or more kinds of pigments may be mixed and used. In this case, it is preferable to use a combination of two or more kinds of charge generating materials having spectral sensitivity characteristics in different spectral regions of the visible region and the near red region. Among them, a disazo pigment, a trisazo pigment and a phthalocyanine pigment are preferably used in combination. More preferred.

The binder resin used for the charge generation layer is not particularly limited, but examples include polyvinyl butyral resin, polyvinyl formal resin, polyvinyl acetal type such as partially acetalized polyvinyl butyral resin in which a part of butyral is modified with formal, acetal, or the like. Resin, Polyarylate resin, Polycarbonate resin, Polyester resin, Modified ether type polyester resin, Phenoxy resin, Polyvinyl chloride resin, Polyvinylidene chloride resin, Polyvinyl acetate resin, Polystyrene resin, Acrylic resin, Methacrylic resin, Polyacrylamide resin, Polyamide Resin, polyvinyl pyridine resin, cellulosic resin, polyurethane resin, epoxy resin, silicone resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, casein, vinyl chloride -Vinyl acetate-vinyl acetate copolymers such as vinyl acetate copolymers, hydroxy-modified vinyl chloride-vinyl acetate copolymers, carboxyl-modified vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, etc. Insulating resins such as polymers, styrene-butadiene copolymers, vinylidene chloride-acrylonitrile copolymers, styrene-alkyd resins, silicon-alkyd resins, phenol-formaldehyde resins, poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl And organic photoconductive polymers such as perylene. Any one of these binder resins may be used alone, or two or more thereof may be mixed and used in any combination.

Specifically, the charge generation layer is prepared by, for example, preparing a coating solution by dispersing a charge generation material in a solution obtained by dissolving the above-described binder resin in an organic solvent, and providing this on a conductive support (providing an undercoat layer). In some cases, it is formed by coating (on the undercoat layer).
In the charge generation layer, the mixing ratio (mass) of the binder resin and the charge generation material is usually 10 parts by mass or more, preferably 30 parts by mass or more, and usually 1000 parts by mass with respect to 100 parts by mass of the binder resin. Part or less, preferably 500 parts by mass or less, and the film thickness is usually 0.1 μm or more, preferably 0.15 μm or more, and usually 10 μm or less, preferably 0.6 μm or less. If the ratio of the charge generation material is too high, the stability of the coating solution may be reduced due to aggregation of the charge generation material, while if the ratio of the charge generation material is too low, the sensitivity as a photoreceptor may be decreased. There is.

  As a method for dispersing the charge generation material, a known dispersion method such as a ball mill dispersion method, an attritor dispersion method, a sand mill dispersion method, or a bead mill dispersion can be used. At this time, it is effective to refine the particles to a particle size in the range of 0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm or less.

[Charge transport layer]
A single charge transport layer is preferably formed on the charge generation layer, and the charge transport layer is preferably the outermost surface layer. The charge transport layer contains a charge transport material, a binder resin, a resin having a polysiloxane structure, and silica particles. You may contain another component as needed.
Specifically, such a charge transport layer is obtained by, for example, preparing a coating solution by dissolving or dispersing a charge transport material and the like, a binder resin, and silica particles in a solvent, and coating and drying on the charge generation layer. be able to.

  From the viewpoint of filming resistance, the average primary particle diameter of the silica particles is 0.2 μm or more, preferably 0.3 μm or more, and particularly preferably 0.4 μm or more. From the viewpoint of coating solution stability, it is 0.9 μm or less, preferably 0.8 μm or less. When the average primary particle diameter of the silica particles is smaller than 0.2 μm, the filming suppression effect is small. When it is larger than 0.9 μm, the stability of the coating solution is deteriorated.

The content of silica particles is usually 3 wt% or more of the entire charge transport layer, and preferably 5 wt% or more from the viewpoint of filming suppression. Further, it is usually 30 wt% or less of the entire charge transport layer, and is preferably 15 wt% or less from the viewpoint of dispersion stability of the coating liquid, and the viewpoint of filming suppression by suppressing aggregation in the load transport layer film. To 10 wt% or less is particularly preferable.

As a kind of silica particle, there is silica having a hollow inside the silica, but silica having no hollow is preferable from the viewpoint of dot suppression.
The silica particles are preferably surface-treated with a reactive organosilicon compound. The surface treatment can be produced by a dry method and a wet method. In the dry method, the surface treatment agent can be mixed with the metal oxide particles so that the metal oxide particles are coated, and heat treatment is performed as necessary. In the wet method, the metal oxide particles and a mixture of the surface treatment agent of the present invention mixed with an appropriate solvent are thoroughly stirred until they are uniformly attached or mixed with media, and then dried, if necessary. It can be manufactured by performing heat treatment.

Examples of reactive organosilicon compounds include silane coupling agents, silane treatment agents, and siloxane compounds, with silane treatment agents being preferred. Among the silane treatment agents, silane treatment agents having an alkyl group having 1 to 3 carbon atoms are preferable. Such silane treating agents include hexamethyldisilazane, trimethylmethoxysilane, trimethylethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, dimethyldimethoxysilane, dimethylethoxysilane, methyldimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane. Etc.
As the charge transport material, a compound represented by the following formula (1) is used.

(In formula (1), R ^{1 to} R ⁸ each independently represents hydrogen, an alkoxy group or an alkyl group.)
In general formula (1), examples of the alkyl group include linear alkyl groups such as methyl, ethyl, n-propyl, and n-butyl groups, branched alkyl groups such as isopropyl and ethylhexyl groups, and cyclohexyl groups. And the like, and from the viewpoint of electrical characteristics and production, a methyl group is preferable. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a butoxy group, and a methoxy group and an ethoxy group are preferable from the viewpoint of electrical characteristics.
Typical examples of the compound represented by the general formula (1) include the following exemplified compounds. However, it is not limited to these compounds.

From the viewpoint of charge mobility, the ratio of the binder resin to the compound represented by the general formula (1) is usually 10 parts by mass or more with respect to 100 parts by mass of the binder resin. From the viewpoint of stability when the charge transport material is repeatedly used, 30 parts by mass or more is preferable, and 40 parts by mass or more is more preferable. On the other hand, from the viewpoint of thermal stability and abrasion resistance of the photosensitive layer, it is usually used at a ratio of 150 parts by mass or less. 80 mass parts or less are preferable from a compatible viewpoint, and 60 mass parts or less are more preferable.

  The content of the compound represented by the general formula (1) and silica particles is usually 1 part by mass or more with respect to 100 parts by mass of the compound represented by the general formula (1). From the viewpoint of suppression, it is preferably 5 parts by mass or more. Further, it is usually 60 parts by mass or less, preferably 50 parts by mass or less from the viewpoint of dispersion stability of the coating solution, and particularly preferably 40 parts by mass or less from the viewpoint of suppressing aggregation in the film.

  The compound represented by the general formula (1) may be used alone or in combination with other charge transporting materials. The charge transporting material used in combination is not particularly limited. For example, aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, and quinone compounds such as diphenoquinone. Electron-withdrawing materials such as, carbazole derivatives, indole derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, heterocyclic compounds such as benzofuran derivatives, aniline derivatives, hydrazone derivatives, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, And an electron donating material such as a polymer in which a plurality of types of these compounds are bonded, or a polymer having a group consisting of these compounds in the main chain or side chain. Among these, aromatic amine derivatives, stilbene derivatives, hydrazone derivatives, and those obtained by bonding a plurality of these compounds are preferable.

  Examples of the binder resin used in the charge transport layer include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, polycarbonate, polyarylate, polyester, polyester carbonate, polysulfone, polyimide, phenoxy, Examples thereof include epoxies and silicone resins, and these partially crosslinked cured products can also be used. Of the binder resins, polycarbonate resin or polyarylate resin is particularly preferable. These resins may be used alone or in combination.

The viscosity average molecular weight (Mv) of the binder resin is usually 10,000 or more from the viewpoint of mechanical properties, and preferably 20,000 or more, more preferably 30,000 or more from the viewpoint of wear resistance. Further, from the viewpoint of applicability, it is usually 200,000 or less, and from the viewpoint of dispersibility, it is preferably 100,000 or less, more preferably 80,000 or less.
Specific examples of suitable structures of the binder resin are shown below. These specific examples are shown for illustration, and any binder resin may be mixed and used as long as it is not contrary to the gist of the present invention.

  The ratio of the binder resin to the entire charge transporting material is preferably used at a ratio of 30 parts by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint of stability and charge mobility when repeatedly used. More than mass part is more preferable. On the other hand, it is preferably used at a ratio of 150 parts by mass or less from the viewpoint of thermal stability and abrasion resistance of the photosensitive layer, and from the viewpoint of compatibility between the charge transport material and the binder resin, 120 parts by mass or less is more preferable. 60 parts by mass or less is particularly preferable.

  The charge transport layer contains a resin having a polysiloxane structure. The resin having a polysiloxane structure is a polycarbonate resin or a polyester resin having a structure represented by the following general formula (2).

(In formula (2), R ⁹ and R ¹⁰ each independently represents a methyl group, an ethyl group, or a phenyl group.)
As the configuration of the resin having a polysiloxane component, the configuration of a resin having a known polysiloxane can be used. For example, when the resin component is A and the polysiloxane component is B, the following configuration is exemplified.
1. A block copolymer having a polysiloxane component at one end as in AB
2. A block copolymer having polysiloxane components at both ends as in B-A-B
3. A block copolymer having a resin component on both sides of a polysiloxane component, such as ABA
4). A block copolymer in which the polysiloxane component is branched from the main chain resin, such as AA (-B) -A
Furthermore, it is possible to use a resin in which one of these or a plurality of configurations is combined. Among these, from the viewpoint of slipperiness and wear resistance, a resin having a polysiloxane component at least at one end, that is, a resin having a polysiloxane component at one end (Example 1 above), or a polysiloxane component at both ends It is preferable to use a resin having the above (Example 2 above). In addition, the repeating unit structure mentioned as said binder resin is applicable to the component (resin component corresponding to said A) which comprises block copolymer other than a polysiloxane component.

  The polysiloxane structure in the case of having at least a part of the polymer terminal is shown. Any structure can be used as long as the effect of the present invention is not significantly impaired.

  A polysiloxane structure having a resin component on both sides of the polysiloxane component is shown. Any structure can be used as long as the effects of the present invention are not significantly impaired.

The proportion of the polysiloxane structure contained in the resin having the polysiloxane component is usually 10% by mass or less, preferably 7% by mass or less, and usually 2% by mass or more, preferably 4% by mass. That's it.
The viscosity-average molecular weight of the resin having a polysiloxane component is arbitrary as long as the effects of the present invention are not significantly impaired. From the viewpoint of wear resistance, it is preferably 20,000 or more, more preferably 30,000 or more, From the viewpoint of solubility in a solvent and productivity, it is preferably 100,000 or less, more preferably 90,000 or less.

It is usually 100 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the charge transport layer of the resin having the polysiloxane component, and preferably 50 parts by mass or less, more preferably 25 parts from the viewpoint of electrical characteristics. On the other hand, it is usually 2 parts by mass or more, and preferably 4 parts by mass or more, more preferably 10 parts by mass or more from the viewpoint of slipperiness.
The thickness of the charge transport layer is not particularly limited, but from the viewpoint of electrical characteristics and image stability, and from the viewpoint of high resolution, it is usually preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 35 μm or less, and still more preferably. 15 μm or more and 25 μm or less.

  In order to improve the film forming property, flexibility, coating property, stain resistance, gas resistance, light resistance, etc. in the charge transport layer, or to further improve the mechanical strength of the photosensitive layer, a well-known plasticizer, It is also preferable to add additives such as a lubricant, a dispersion aid, an antioxidant, an ultraviolet absorber, an electron-withdrawing compound, a dye, a pigment, a sensitizer, a leveling agent, a stabilizer, a fluidity-imparting agent, and a crosslinking agent. . Examples of the antioxidant include hindered phenol compounds and hindered amine compounds. Examples of dyes and pigments include various pigment compounds and azo compounds. Examples of leveling agents include silicone oil and fluorine-based surfactants.

Electron-withdrawing compounds include tetracyanoquinodimethane, dicyanoquinomethane, cyano compounds such as aromatic esters having a dicyanoquinovinyl group, nitro compounds such as 2,4,6-trinitrofluorenone, and condensation of perylene. Polycyclic aromatic compounds, diphenoquinone derivatives, quinones, aldehydes, ketones, esters, acid anhydrides, phthalides, metal complexes of substituted and unsubstituted salicylic acid, metal salts of substituted and unsubstituted salicylic acid, aromatic carboxylic acids And metal salts of aromatic carboxylic acids. Preferably, cyanide compounds, nitro compounds, condensed polycyclic aromatic compounds, diphenoquinone derivatives, metal complexes of substituted and unsubstituted salicylic acid, metal salts of substituted and unsubstituted salicylic acid, metal complexes of aromatic carboxylic acid, aromatic carboxylic acid Metal salts are used.

<Method for forming each layer>
Each layer constituting the photoreceptor is formed by immersing, coating, spraying, nozzle coating, bar coating, roll coating, blade coating, etc., on a support, a coating solution obtained by dissolving or dispersing a substance contained in each layer in a solvent. In this method, the coating and drying steps are sequentially repeated for each layer.

  Although there is no particular limitation on the solvent or dispersion medium used for the production of the photosensitive layer, specific examples include ethers such as tetrahydrofuran, 1,4-dioxane and dimethoxyethane, esters such as methyl formate and ethyl acetate, acetone, Ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene and xylene, dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, tetrachloroethane, Chlorinated hydrocarbons such as 1,2-dichloropropane and trichloroethylene, nitrogen-containing compounds such as n-butylamine, isopropanolamine, diethylamine, triethanolamine, ethylenediamine and triethylenediamine, acetonitrile, and N-methylpyrrolide , N, N- dimethylformamide, aprotic polar solvents such as dimethyl sulfoxide and the like. Moreover, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and kinds.

The amount of the solvent or dispersion medium used is not particularly limited, but considering the purpose of each layer and the properties of the selected solvent / dispersion medium, it is appropriate so that the physical properties such as solid content concentration and viscosity of the coating liquid are within a desired range. It is preferable to adjust.
In the case of the charge transport layer, the solid content concentration of the coating solution is usually 5% by mass or more, preferably 10% by mass or more, and usually 40% by mass or less, preferably 35% by mass or less. Further, the viscosity of the coating solution is usually in the range of 10 cps or more, preferably 50 cps or more, and usually 500 cps or less, preferably 400 cps or less.

In the case of the charge generation layer, the solid content concentration of the coating solution is usually 0.1% by mass or more, preferably 1% by mass or more, and usually 15% by mass or less, preferably 10% by mass or less. The viscosity of the coating solution is usually 0.01 cps or more, preferably 0.1 cps or more, and usually 20 cps or less, preferably 10 cps or less.
Examples of the coating method include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a wire bar coating method, a blade coating method, a roller coating method, an air knife coating method, and a curtain coating method. Other known coating methods can also be used.

<Image forming apparatus>
An image forming apparatus such as a copying machine or a printer using the electrophotographic photosensitive member of the present invention includes at least charging, exposure, development, transfer, and cleaning processes. Also good. For example, as shown in FIG. 1, the image forming apparatus includes an electrophotographic photoreceptor 1, a charging device 2, an exposure device 3, and a developing device 4, and further, a transfer device 5 and a cleaning device 6 as necessary. In addition, those provided with the fixing device 7 can be applied.

The electrophotographic photoreceptor 1 is not particularly limited as long as it is the above-described electrophotographic photoreceptor of the present invention, but in FIG. 1, as an example, a drum in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. The photoconductor is shown. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged along the outer peripheral surface of the electrophotographic photoreceptor 1.
The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. In FIG. 1, a roller-type charging device (charging roller) is shown as an example of the charging device 2, but other corona charging devices such as corotron and scorotron, and contact-type charging devices such as charging brushes are often used.

  In many cases, the electrophotographic photosensitive member 1 and the charging device 2 are designed to be removable from the main body of the image forming apparatus as a cartridge including both of them (hereinafter also referred to as a photosensitive cartridge). For example, when the electrophotographic photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be removed from the image forming apparatus main body, and another new photosensitive cartridge can be mounted on the image forming apparatus main body. ing. Also, the toner described later is often stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the used toner cartridge runs out, this toner cartridge is removed. It can be removed from the main body of the image forming apparatus and another new toner cartridge can be mounted. Further, a cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, and the toner may be used.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Among these, LED is preferable from the viewpoint of life. Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, the exposure may be performed using monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength slightly shorter than 600 nm to 700 nm, or monochromatic light with a short wavelength of 380 nm to 500 nm. .

  The type of the developing device 4 is not particularly limited, and an arbitrary device such as a dry development method such as cascade development, one-component conductive toner development, two-component magnetic brush development, or a wet development method can be used. In FIG. 1, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge. From the viewpoint of interaction with silica particles, non-contact development is preferred.

  The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like disposed so as to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Is.

  The cleaning device 6 is not particularly limited, and any cleaning device such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, or a blade cleaner can be used. However, the present invention is effective for a blade cleaner. Is easy to demonstrate. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner.

In the electrophotographic apparatus configured as described above, an image is recorded as follows.
That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.
Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.

The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.
When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.

After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.
In addition to the above-described configuration, the image forming apparatus may be configured to perform, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.

  The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.

<Manufacture of coating liquid for undercoat layer formation>
Coating liquid A
A rutile type titanium oxide having an average primary particle size of 40 nm (“TTO55N” manufactured by Ishihara Sangyo Co., Ltd.) and 3% by mass of methyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co., Ltd.) with respect to the titanium oxide were added to a Henschel mixer. 1 kg of a raw slurry obtained by mixing 50 parts of surface-treated titanium oxide obtained by mixing with 120 parts of methanol, and using a zirconia bead having a diameter of about 100 μm (YTZ manufactured by Nikkato Co., Ltd.) as a dispersion medium, a mill volume of about 0 Using a 15-liter Ultra Apex Mill (UAM-015 type) manufactured by Kotobuki Kogyo Co., Ltd., a titanium oxide dispersion was prepared by dispersing for 1 hour in a liquid circulation state with a rotor peripheral speed of 10 m / second and a liquid flow rate of 10 kg / hour .

The titanium oxide dispersion, a mixed solvent of methanol / 1-propanol / toluene, and ε-caprolactam [compound represented by the following formula (A)] / bis (4-amino-3-methylcyclohexyl) methane [the following formula Compound represented by (B)] / hexamethylenediamine [compound represented by the following formula (C)] / decamethylene dicarboxylic acid [compound represented by the following formula (D)] / octadecamethylene dicarboxylic acid [following formula (E ) And a copolymerized polyamide pellet having a composition molar ratio of 75% / 9.5% / 3% / 9.5% / 3% while stirring and mixing the mixture to obtain polyamide pellets. After dissolution, ultrasonic dispersion with an ultrasonic transmitter with an output of 1200 W is performed for 1 hour, and a PTFE membrane filter (a) with a pore size of 5 μm is added. The mixture was filtered through Dovetec Mytecs LC), and the mass ratio of the surface-treated titanium oxide / copolymerized polyamide was 3/1, and the mass ratio of the mixed solvent of methanol / 1-propanol / toluene was 7/1/2. Thus, an undercoat layer-forming coating solution A having a solid content concentration of 18.0% by mass was obtained.

<Manufacture of coating solution for forming charge generation layer>
Charge generation layer forming coating solution B
The charge generation layer forming coating solution was prepared as follows. As a charge generation substance, 20 parts of oxytitanium phthalocyanine shown in the X-ray diffraction spectrum of FIG. 2 and 280 parts of 1,2-dimethoxyethane were mixed, and pulverized with a sand grind mill for 1 hour for atomization dispersion treatment. Subsequently, 10 parts of polyvinyl butyral (trade name “Denkabutyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) were added to 255 parts of 1,2-dimethoxyethane and 4-methoxy-4-. A binder liquid obtained by dissolving in 85 parts of a mixed solution of methyl-2-pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a coating solution B1 for forming a charge generation layer.

  As a charge generation material, 20 parts of oxytitanium phthalocyanine shown in the X-ray diffraction spectrum of FIG. 3 and 280 parts of 1,2-dimethoxyethane were mixed and pulverized with a sand grind mill for 4 hours for atomization dispersion treatment. Subsequently, 10 parts of polyvinyl butyral (trade name “Denkabutyral” # 6000C, manufactured by Denki Kagaku Kogyo Co., Ltd.) were added to 255 parts of 1,2-dimethoxyethane and 4-methoxy-4-. A binder solution obtained by dissolving in 85 parts of a mixture of methyl-2-pentanone and 230 parts of 1,2-dimethoxyethane were mixed to prepare a charge generation layer forming coating solution B2. The charge generation layer forming coating solution B1 and the charge generation layer forming coating solution B2 were mixed at a ratio of 6: 4 to prepare the charge generation layer forming coating solution B used in this example.

<Manufacture of coating liquid for charge transport layer formation>
Charge transport layer forming coating solution C1
Ultrasonic dispersion of silicon oxide with a mean primary particle size of 0.4μ surface treated with hexamethylene disilazane (manufactured by Nippon Shokubai Co., Ltd., product name KE-S50, hereinafter referred to as T50) with tetrahydrofuran solvent for 4 hours. And a silicon oxide slurry was obtained. 90 parts of a polycarbonate resin (resin X1, viscosity average molecular weight 50,000) represented by the following repeating structure and 10 parts of a resin having a polysiloxane structure are added to the silicon oxide slurry so that silicon oxide becomes 10 parts. (Resin XE1, viscosity average molecular weight 50,000), 60 parts of CTM1 as a charge transport material, 2 parts of compound AD1 represented by the following formula, 0.05 part of leveling agent silicone oil (Shin-Etsu Chemical KF96-10CS) The mixture was dissolved by heating with stirring in a tetrahydrofuran solvent to obtain a charge transport layer forming coating solution C1 having a solid content of 20% by mass.

Coating liquid C2
Instead of T50 used for the charge transport layer forming coating solution C1, silicon oxide having an average primary particle size of 0.8 μ and surface-treated with hexamethylene disilazane (product name KE-S100 manufactured by Nippon Shokubai Co., Ltd.) The coating liquid C2 for forming a charge transport layer was prepared in the same manner as C1, except that T100) was used.

Coating liquid C3
A charge transport layer forming coating solution C3 was prepared in the same manner as C1, except that T50 used in the charge transport layer forming coating solution C1 was not used.

Coating liquid C4
A charge transport layer forming coating solution C4 was prepared in the same manner as C1, except that XE1 used in the charge transport layer forming coating solution C1 was not used.

Coating liquid C5
A charge transport layer forming coating solution C5 was prepared in the same manner as C1, except that CTM2 represented by the following structure was used instead of CTM1 used for the charge transport layer forming coating solution C1.

<Manufacture of photosensitive drum>
Hereinafter, using the coating liquid, as shown in Table 1, photosensitive drums corresponding to Examples 1 to 4 and Comparative Examples 1 to 6 were produced as follows. A coating solution for forming an undercoat layer, a coating solution for forming a charge generation layer, prepared in a manufacturing example of a coating solution on a cylinder made of an aluminum alloy having an outer diameter of 30 mm, a length of 248 mm, and a wall thickness of 0.75 mm. The coating solution for forming the charge transport layer is sequentially applied and dried by the dip coating method, and the undercoat layer, the charge generation layer, and the charge transport are adjusted so that the film thicknesses after drying are 1.5 μm, 0.5 μm, and 36 μm, respectively. A layer was formed to produce a photoreceptor drum. The charge transport layer was dried at 125 ° C. for 24 minutes.

<Evaluation of dispersibility>
The dispersibility of the silica particles on the photoreceptor surface was confirmed visually or by palpation. The results are shown in Table-1. The level of dispersibility is as follows.
○: There is no aggregation of silica anywhere on the surface of the photoreceptor, and no rough aggregate is felt even when touched by hand.
(Triangle | delta): Aggregation is seen especially in a very small part of the lower end of the photoreceptor surface. In addition, when touched with a hand, a rough aggregate is felt. However, there is no practical problem because it is outside the image area.
X: Aggregation is observed on the entire surface of the photoconductor, and a rough aggregate is felt when touched with a hand. Since it is in the image area, there is a problem in practical use.

<Evaluation of electrical characteristics>
Next, these electrophotographic photosensitive members are attached to an electrophotographic characteristic evaluation apparatus (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404 to 405) prepared according to the Electrophotographic Society standard. The sample was mounted on a photoconductor characteristic measuring machine and evaluated in an environment of 25 ° C./50% of the electric characteristics by the cycle of charging (minus polarity), exposure, potential measurement, and static elimination according to the following procedure. In addition, the photosensitive member is charged so that the initial surface potential is −800 V, and the halogen lamp is irradiated with monochromatic light of 780 nm using an interference filter, and the exposure light is irradiated with an intensity of 1.0 μJ / cm ² . After exposure, the surface potential (VL) after exposure after 65 ms was measured (−V). The measured data is shown in Table-1.

<Image test>
The obtained photoreceptor is mounted on a photoreceptor cartridge of a monochrome printer ML6510 (DC roller charging, laser exposure, non-magnetic two-component, non-contact development) manufactured by Samsung, at a temperature of 25 ° C. and a relative humidity of 50%. Continuous printing of 30,000 sheets was performed at a printing rate of 5%. The film thickness before and after printing was measured after printing 30,000 sheets, and the amount of film reduction in terms of 1,000 rotations of the photoreceptor was calculated. The results are shown in Table-1.

The dispersibility is improved by the addition of Si resin, as can be seen by comparing Example 1 and Comparative Example 2. This is considered to be due to the fact that the resin Si has affinity with the silica Si and spreads over the entire photoreceptor to prevent aggregation.
As can be seen from the comparison between Example 1 and Comparative Example 1, the wear was remarkably improved by the addition of silica. It is considered that the addition of silica locally causes the polymer chain to curl, which improves the wear resistance by increasing the mechanical strength.
As for electrical characteristics, low VL was achieved by using CTM1 as can be seen by comparing Example 1 and Comparative Example 3. As a result, the image density can be stably maintained even in an image forming apparatus having a high printing speed. Further, even in an image forming apparatus using an LED with low exposure power, the image density can be stably maintained. In addition, wear is improved.

<Abrasion resistance of small outer diameter photoreceptor>
In the image forming apparatus, the total number of rotations throughout the life of a photoconductor having a smaller base diameter is larger than that of a photoconductor having a large outer diameter. Specifically, based on the total number of revolutions when the outer diameter of the substrate is φ30, the number of revolutions is 0.5 times for φ60, 1.25 times for φ24, and 1.5 times for φ20. For example, when the photoconductor of Example 1 is manufactured with φ20, the wear rate is 16.1 [nm / Kcyc], which is 1.5 times. Here, if it is assumed that the print life can withstand 100,000 pages with a wear rate of 30.5 [nm / Kcyc] (Comparative Example 2), the photoconductor of Example 1 with a diameter of φ20. It will be able to withstand the page, and high life will be achieved. Furthermore, by reducing the outer diameter, the entire image forming apparatus can be designed compactly.

1 Photoconductor (Electrophotographic photoconductor)
2 Charging device (charging roller; charging unit)
3 Exposure equipment (exposure section)
4 Development device (development unit)
DESCRIPTION OF SYMBOLS 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Control member 71 Upper fixing member (fixing roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper (paper, medium)

Claims (8)

In an electrophotographic photoreceptor having a charge generation layer and a charge transport layer in this order on a conductive substrate, the charge transport layer is the outermost layer, a charge transport material, a binder resin, a resin having a polysiloxane structure, and silica particles The charge transport material is represented by the following formula (1), the resin having the polysiloxane structure is a polycarbonate resin or a polyester resin having a structure represented by the following general formula (2), and the silica particles The electrophotographic photosensitive member is characterized by having an average primary particle size of 0.2 μm or more and 0.9 μm or less.

(In formula (1), R ^{1 to} R ⁸ each independently represents hydrogen, an alkoxy group or an alkyl group.)

(In formula (2), R ⁹ and R ¹⁰ each independently represents a methyl group, an ethyl group, or a phenyl group.)   The electrophotographic photosensitive member according to claim 1, wherein an average primary particle size of the silica particles is 0.3 μm or more and 0.8 μm or less.   The electrophotographic photosensitive member according to claim 1, wherein the content of the silica particles is 3 wt% or more and 30 wt% or less of the entire charge transport layer.   The electrophotographic photosensitive member according to claim 1, wherein the silica particles are surface-treated with a reactive organosilicon compound.   The electrophotographic photosensitive member according to claim 1, wherein the conductive substrate has a cylindrical shape and an outer diameter of 10 mm to 24 mm. An electrostatic latent image is formed by performing image exposure on the electrophotographic photosensitive member according to claim 1, a charging device for charging the electrophotographic photosensitive member, and the charged electrophotographic photosensitive member. An electrophotographic cartridge having an image exposure device and a developing device for developing the electrostatic latent image with toner, wherein the developing device is non-contact development.   An image forming apparatus using the electrophotographic cartridge according to claim 6.   The image forming apparatus according to claim 7, wherein the image exposure unit is an LED.

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