JP2013104974A - Electrophotographic photoreceptor, image forming device, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having an outermost layer that maintains high abrasion resistance.SOLUTION: The electrophotographic photoreceptor includes at least a photosensitive layer formed on a substrate, and as an outermost layer, a layer formed by containing binder resin having a structural unit represented by general formula (A) and hindered phenol antioxidant with a content of 15 mass% with respect to the binder resin. In the general formula (A), Rand Rrepresent independently a halogen atom, an alkyl group of 1-6C, a cycloalkyl group of 5-7C, or an aryl group of 6-12C. (a) and b independently represent integers of 0-4.

Description

  The present invention relates to an electrophotographic photoreceptor, an image forming apparatus, and a process cartridge.

  In a conventional electrophotographic image forming apparatus, a toner image formed on the surface of an electrophotographic photosensitive member is transferred to a recording medium through processes of charging, exposure, development, and transfer.

  For example, in Cited Document 1, an electrophotographic photosensitive film that is advantageous in mechanical strength and electrical characteristics by containing a resin having a specific polycarbonate or polyarylate structural unit and a specific phenolic antioxidant in the photosensitive layer. The body has been proposed.

  In the cited document 2, the photosensitive layer surface cleaning property is obtained by containing at least a specific polycarbonate copolymer as a binder resin, a specific stilbene compound as a charge transfer agent, and an amine antioxidant in the photosensitive layer. There has been proposed an electrophotographic photosensitive member that improves the light resistance and does not cause light fatigue.

JP 2004-045858 A JP 2008-256851 A

  An object of the present invention is to provide an electrophotographic photosensitive member having an outermost surface layer in which high wear resistance is maintained.

  The above problem is solved by the following means. That is,

The invention according to claim 1
Having at least a photosensitive layer on the substrate;
The outermost surface layer includes a binder resin having a structural unit represented by the following general formula (A), and a hindered phenol-based antioxidant having a content of 15% by mass or more based on the binder resin. An electrophotographic photosensitive member having a layer formed thereon.

(In the general formula (A), R ¹ and R ² are each independently a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a group having 6 to 12 carbon atoms. Represents an aryl group, and a and b each independently represent an integer of 0 or more and 4 or less.)

The invention according to claim 2
The electrophotographic photosensitive member according to claim 1, wherein the binder resin is a copolymer having a structural unit represented by the general formula (A) and a structural unit represented by the following general formula (B). body.

(In General Formula (B), R ³ and R ⁴ are each independently a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a carbon atom having 6 to 12 carbon atoms. Each represents an aryl group, and c and d each independently represent an integer of 0 or more and 4 or less, X represents —CR ⁵ R ⁶ — (wherein R ⁵ and R ⁶ each independently represents a hydrogen atom, trifluoromethyl) Group, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms), a 1,1-cycloalkylene group having 5 to 11 carbon atoms, and α having 2 to 10 carbon atoms. , Ω-alkylene group, —O—, —S—, —SO—, or —SO ₂ —.

The invention according to claim 3
The binder resin is a copolymer in which the copolymerization ratio of the structural unit represented by the general formula (A) is 15 mol% or more and 25 mol% or less with respect to all the structural units constituting the binder resin. The electrophotographic photosensitive member according to claim 1.

The invention according to claim 4
The electrophotographic photosensitive member according to claim 1, wherein the outermost surface layer of the electrophotographic photosensitive member contains fluororesin particles.

The invention according to claim 5
The electrophotographic photosensitive member according to any one of claims 1 to 4,
A charging device for charging the electrophotographic photosensitive member;
A latent image forming device that exposes the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image; and
A developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member to form a toner image;
A transfer device for transferring the toner image formed on the surface of the electrophotographic photosensitive member to the surface of a recording medium;
A cleaning device for cleaning the surface of the electrophotographic photosensitive member;
An image forming apparatus comprising:

The invention according to claim 6
It is detachable from the image forming apparatus,
The electrophotographic photosensitive member according to claim 1,
A charging device that charges the electrophotographic photosensitive member, a latent image forming device that exposes the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image, and an electrostatic latent image formed on the surface of the electrophotographic photosensitive member. Developing device for developing image to form toner image, transfer device for transferring toner image formed on surface of electrophotographic photosensitive member to surface of recording medium, and cleaning device for cleaning surface of electrophotographic photosensitive member At least one selected from the group of:
A process cartridge comprising:

According to the first aspect of the invention, the outermost surface layer includes a binder resin containing the structural unit represented by the general formula (A), and a hindered phenol-based oxidation having a content of 15% by mass or more with respect to the binder resin. As compared with the case where at least one of the inhibitor is not included, an electrophotographic photoreceptor having an outermost surface layer in which high wear resistance is maintained can be provided.
According to the invention of claim 2, the binder resin is more resistant than a copolymer having a structural unit represented by the general formula (A) and a structural unit represented by the general formula (B). An electrophotographic photosensitive member having an outermost surface layer with high wear can be provided.
According to the invention of claim 3, the outermost surface layer having high wear resistance compared to the case where the copolymerization ratio of the structural unit represented by the general formula (A) is outside the range of claim 3. An electrophotographic photosensitive member can be provided.
According to the fourth aspect of the present invention, an electrophotographic photosensitive member having an outermost surface layer having high wear resistance can be provided as compared with a case where the outermost surface layer does not contain fluororesin particles.

According to the fifth aspect of the present invention, the life of the image forming apparatus can be extended as compared with the case where this configuration is not provided.
According to the sixth aspect of the present invention, the life of the process cartridge can be extended as compared with the case where this configuration is not provided.

1 is a schematic cross-sectional view showing an electrophotographic photosensitive member according to the present embodiment. 1 is a schematic cross-sectional view showing an electrophotographic photosensitive member according to the present embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus and a process cartridge according to an exemplary embodiment.

Embodiments that are examples of the present invention will be described below.

The electrophotographic photosensitive member according to this embodiment has at least a photosensitive layer on a substrate.
The electrophotographic photoreceptor according to the exemplary embodiment has a binder resin having a structural unit represented by the following general formula (A) as the outermost surface layer, and a content with respect to the binder resin of 15% by mass or more. And a hindered phenol-based antioxidant.

  Here, the binder resin having the structural unit represented by the general formula (A) is a material having excellent wear resistance. For this reason, when this binder resin includes the outermost surface layer of the electrophotographic photosensitive member, the wear resistance of the layer is improved.

In addition, when an antioxidant is included in the outermost surface layer, it is considered that structural fatigue and destruction of the structural unit of the binder resin, which can be caused by repeated discharge (oxidation), are suppressed.
On the other hand, when an antioxidant is contained in a large amount in the outermost surface layer, the outermost surface layer becomes brittle and wear resistance tends to be lowered.

However, although the reason is not clear, if a hindered phenol-based antioxidant is used as the antioxidant to be included in the outermost surface layer including the binder resin having the structural unit represented by the general formula (A), Even if an inhibitor is contained in a large amount (15% by mass or more based on the binder resin) in the outermost surface layer, not only the outermost surface layer does not become brittle, but also the wear resistance of the outermost surface layer is improved. Was found to be maintained.
The reason for this is not clear, but the phenolic antioxidant suppresses oxidative degradation of the layer by having a molecular scavenging function when subjected to repeated discharges. If it is contained in a large amount, the influence of the radical scavenging action on the binder resin that should occur naturally becomes so small that it can be ignored, and the intermolecular interaction between the structural units represented by the general formula (A) is impaired. This is because the strength forming effect is presumed to be maintained.

For this reason, the electrophotographic photosensitive member according to the present embodiment is an electrophotographic photosensitive member having an outermost surface layer that maintains high wear resistance due to the above configuration.
In the process cartridge and the image forming apparatus including the electrophotographic photosensitive member according to the present embodiment, a long life is realized.

Hereinafter, the electrophotographic photoreceptor according to the exemplary embodiment will be described with reference to the drawings.
FIG. 3 is a schematic cross-sectional view showing the electrophotographic photoreceptor according to this embodiment. FIG. 4 is a schematic sectional view showing an electrophotographic photoreceptor according to another embodiment.

An electrophotographic photoreceptor 10A shown in FIG. 3 is, for example, a so-called function-separated photoreceptor (or laminated photoreceptor), and an undercoat layer 1 is provided on a conductive substrate 4, and a charge generation layer 2 is provided thereon. And a structure in which the charge transport layer 3 is sequentially formed. In the electrophotographic photoreceptor 10A, the charge generation layer 2 and the charge transport layer 3 constitute a photosensitive layer.
In the electrophotographic photoreceptor 10 </ b> A shown in FIG. 3, the charge transport layer 3 is the outermost surface layer disposed on the side farthest from the conductive substrate 4.

An electrophotographic photoreceptor 10B shown in FIG. 4 contains, for example, a charge generation material and a charge transport material in the same layer (single layer type photosensitive layer 6 (charge generation / charge transport layer)).
Specifically, the electrophotographic photoreceptor 10B shown in FIG. 4 has a structure in which the undercoat layer 1 is provided on the conductive substrate 4 and the single-layer type photosensitive layer 6 is formed thereon. .
In the electrophotographic photoreceptor 10 </ b> B shown in FIG. 4, the single-layer type photosensitive layer 6 is the outermost surface layer disposed on the side farthest from the conductive substrate 4.

  Hereinafter, each element in the electrophotographic photoreceptor 10 will be described. Note that the description is omitted.

First, the conductive substrate will be described. “Conductivity” means, for example, a volume resistivity of 10 ¹³ Ω · cm or less.
Any conductive substrate may be used as long as it is conventionally used. For example, thin films (eg, metals such as aluminum, nickel, chromium, stainless steel, and films of aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, indium tin oxide (ITO), etc.) And a plastic film coated or impregnated with a conductivity-imparting agent, a plastic film coated or impregnated with a conductivity-imparting agent, and the like. The shape of the conductive substrate is not limited to a cylindrical shape, and may be a sheet shape or a plate shape.

  When a metal pipe is used as the conductive substrate, the surface may be left as it is, and treatments such as mirror cutting, etching, anodizing, rough cutting, centerless grinding, sand blasting, and wet honing have been performed in advance. Also good.

Next, the undercoat layer will be described.
The undercoat layer is provided for the purpose of preventing light reflection on the surface of the conductive substrate and preventing inflow of unnecessary carriers from the conductive substrate to the photosensitive layer.

The undercoat layer includes, for example, a binder resin and, if necessary, other additives.
As the binder resin contained in the undercoat layer, acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, Known polymer resin compounds such as polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, and charge transporting group Examples thereof include charge transporting resins having a conductive resin such as polyaniline. Among these, resins that are insoluble in the upper coating solvent are preferably used, and phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, epoxy resins, and the like are particularly preferably used.

The undercoat layer may contain a metal compound such as a silicon compound, an organic zirconium compound, an organic titanium compound, or an organic aluminum compound.
The ratio between the metal compound and the binder resin is not particularly limited, and is preferably set within a range in which desired electrophotographic photoreceptor characteristics can be obtained.

  Resin particles may be added to the undercoat layer in order to adjust the surface roughness. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate (PMMA) resin particles. The surface may be polished after forming the undercoat layer for adjusting the surface roughness. As a polishing method, buffing, sandblasting, wet honing, grinding, or the like is used.

Here, the structure of the undercoat layer is particularly preferably a structure containing at least a binder resin and conductive particles. The conductivity means that the volume resistivity is less than 10 ⁷ Ω · cm, for example.
Examples of the conductive particles include metal particles (particles such as aluminum, copper, nickel, and silver), conductive metal oxide particles (particles such as antimony oxide, indium oxide, tin oxide, and zinc oxide), and conductive substance particles. (Carbon fiber, carbon black, particles of graphite powder) and the like. Among these, conductive metal oxide particles are preferable. You may mix and use 2 or more types of electroconductive particle.
In addition, the conductive particles may be subjected to a surface treatment with a hydrophobizing agent (for example, a coupling agent) or the like to adjust the resistance.
For example, the content of the conductive particles is preferably 10% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 80% by mass or less with respect to the binder resin.

  In forming the undercoat layer, an undercoat layer forming coating solution in which the above components are added to a solvent is used. In addition, as a method of dispersing particles in the coating solution for forming the undercoat layer, a media dispersing machine such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, a stirring, an ultrasonic dispersing machine, a roll mill, a high-pressure homogenizer, etc. Medialess dispersers are used. Here, examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high-pressure state, and a penetration method in which a fine flow path is dispersed in a high-pressure state. .

  Examples of the method for applying the coating solution for forming the undercoat layer onto the conductive substrate include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. It is done.

The volume resistivity of the undercoat layer is not less than 1.0 × 10 ⁸ Ω · cm, preferably not less than 1.0 × 10 ⁸ Ω · cm and more preferably not more than 1.0 × 10 ¹¹ Ω · cm. Desirably 1.0 × 10 ⁹ Ω · cm or more and 1.0 × 10 ¹⁰ Ω · cm or less If the volume resistivity of the undercoat layer is too high, residual potential tends to remain, which is disadvantageous in terms of electrical characteristics. is there.

  The volume resistivity of the undercoat layer can be adjusted by, for example, 1) a method for adjusting the drying temperature of the undercoat layer, or 2) the surface treatment agent type and amount for surface-treating the pigment (for example, zinc oxide) in the undercoat layer. It is realized by a method of adjusting by the above.

The volume resistivity of the undercoat layer is a value determined by the following measurement method.
For the undercoat layer, a gold electrode with a diameter of 1 mm was used as the counter electrode, and the current value after 30 seconds when an electric field of 10 ⁷ V / m was applied in an environment of 22 ° C. and 55% RH was measured. Ask.

  The thickness of the undercoat layer is 30 μm or more, preferably 30 μm or more and 60 μm or less, more preferably 30 μm or more and 50 μm or less.

  The film thickness of the undercoat layer is a value determined by an eddy current film thickness meter (for example, Surfix N: manufactured by PHYNIX).

  Here, although not shown, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer. As the binder resin used for the intermediate layer, acetal resins such as polyvinyl butyral, polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl In addition to polymer resins such as acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, zirconium, titanium, aluminum, manganese, silicon atom, etc. An organometallic compound containing These compounds may be used alone or as a mixture or polycondensate of a plurality of compounds. Among these, an organometallic compound containing zirconium or silicon is preferable.

  In forming the intermediate layer, a coating solution for forming an intermediate layer in which the above components are added to a solvent is used. As the coating method for forming the intermediate layer, usual methods such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method are used.

  The thickness of the intermediate layer is preferably set to a film thickness range of 0.1 μm or more and 3 μm or less, for example. Further, this intermediate layer may be used as an undercoat layer.

Next, the charge generation layer will be described.
The charge generation layer includes, for example, a charge generation material and a binder resin. Examples of such a charge generating material include phthalocyanine pigments such as metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine. A chlorogallium phthalocyanine crystal having strong diffraction peaks at least at 7.4 °, 16.6 °, 25.5 ° and 28.3 °, a Bragg angle (2θ ± 0.2 °) to CuKα characteristic X-ray of at least 7 Metal-free phthalocyanine crystals having strong diffraction peaks at .7 °, 9.3 °, 16.9 °, 17.5 °, 22.4 °, and 28.8 °, Bragg angle (2θ ± 0) with respect to CuKα characteristic X-rays .2 °) at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 ° Hydroxygallium phthalocyanine crystals having strong diffraction peaks at 25.1 ° and 28.3 °, Bragg angles (2θ ± 0.2 °) with respect to CuKα characteristic X-rays of at least 9.6 °, 24.1 ° and 27.2 A titanyl phthalocyanine crystal having a strong diffraction peak at 0 ° can be mentioned. In addition, examples of the charge generation material include quinone pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, anthrone pigments, quinacridone pigments, and the like. These charge generation materials may be used alone or in combination of two or more.

Examples of the binder resin constituting the charge generation layer include polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile-styrene. Copolymer resin, acrylonitrile-butadiene copolymer, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride Examples thereof include resins, silicone resins, phenol-formaldehyde resins, polyacrylamide resins, polyamide resins, poly-N-vinylcarbazole resins. These binder resins may be used alone or in combination of two or more.
The mixing ratio of the charge generating material and the binder resin is desirably in the range of 10: 1 to 1:10.

When forming the charge generation layer, a coating solution for forming a charge generation layer in which the above components are added to a solvent is used.
As a method for dispersing particles (for example, charge generation material) in the coating solution for forming the charge generation layer, a media dispersion machine such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, an agitation, an ultrasonic dispersion machine, a roll mill, etc. Medialess dispersers such as high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high-pressure state, and a penetration method in which a fine flow path is dispersed in a high-pressure state.

  Examples of the method for applying the charge generation layer forming coating liquid on the undercoat layer include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. It is done.

  The thickness of the charge generation layer is desirably set in the range of 0.01 μm to 5 μm, more desirably 0.05 μm to 2.0 μm.

Next, the charge transport layer will be described.
The charge transport layer includes, for example, a binder resin, an antioxidant, and a charge transport material.

  As the binder resin, a binder resin having a structural unit (repeating unit) represented by the following general formula (A), that is, a co-polymer containing a structural unit (repeating unit) represented by the following general formula (A) A coalescence (polycarbonate resin) is employed (hereinafter, this binder resin is referred to as “specific polycarbonate resin”).

In general formula (A), R ¹ and R ² are each independently a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an aryl having 6 to 12 carbon atoms. Represents a group.
a and b each independently represent an integer of 0 or more and 4 or less.

In general formula (A), R ¹ and R ² each independently preferably represents an alkyl group having 1 to 6 carbon atoms, and more preferably represents a methyl group.
In general formula (A), it is desirable that a and b each independently represent an integer of 0 or more and 2.

  Specifically, the structural unit represented by the general formula (A) is preferably a structural unit represented by the following structural formula (A1).

  The specific polycarbonate resin is not particularly limited as long as it contains the structural unit represented by the general formula (A), but from the viewpoint of further suppressing the abrasion by improving the mechanical strength of the outermost surface layer. It is preferable that the copolymer includes a structural unit represented by the formula (A) and a structural unit represented by the following general formula (B).

In general formula (B), R ³ and R ⁴ each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an aryl having 6 to 12 carbon atoms. Represents a group.
c and d each independently represent an integer of 0 or more and 4 or less.
X is —CR ⁵ R ⁶ — (wherein R ⁵ and R ⁶ are each independently a hydrogen atom, a trifluoromethyl group, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. 1), a 1,1-cycloalkylene group having 5 to 11 carbon atoms, an α, ω-alkylene group having 2 to 10 carbon atoms, —O—, —S—, —SO—, or —SO _2. -Represents. )

In general formula (B), R ³ and R ⁴ preferably each independently represent an alkyl group having 1 to 6 carbon atoms, and more preferably a methyl group.
It is desirable that c and d each independently represent an integer of 0 or more and 2.

In the general formula (B), X is, ^-CR 5 ^{R 6} -, preferably having 5 to 11 of 1,1-cycloalkylene group carbon, ^-CR 5 ^{R 6} - is more desirable. R ⁵ and R ⁶ in —CR ⁵ R ⁶ — are each independently preferably an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and among them, a methyl group or a phenyl group Is more desirable.

  Specifically, the structural unit represented by the general formula (B) is preferably a structural unit represented by the following structural formulas (B1) to (B3).

  Here, the structural unit represented by the general formula (A), the structural unit represented by the general formula (B), and the polycarbonate resin that is a copolymer including the structural unit are represented by the following general formula (2A), for example. 4,4'-dihydroxybiphenyl compound and a bisphenol compound represented by the following general formula (2B) as raw materials, such as polycondensation with a carbonate-forming compound such as phosgene or transesterification with bisaryl carbonate Obtained by the method.

In general formulas (2A) and (2B), R ¹ , R ² , R ³ , R ⁴ , a, b, c, d, and X are the same as those in general formulas (A) and (B). .

  Here, specific examples of the 4,4′-dihydroxybiphenyl compound represented by the general formula (2A) include 4,4′-dihydroxybiphenyl and 4,4′-dihydroxy-3,3′-dimethylbiphenyl. 4,4'-dihydroxy-2,2'-dimethylbiphenyl, 4,4'-dihydroxy-3,3'-dicyclohexylbiphenyl, 3,3'-difluoro-4,4'-dihydroxybiphenyl, 4,4 ' -Dihydroxy-3,3'-diphenylbiphenyl and the like.

  On the other hand, specific examples of the bisphenol compound represented by the general formula (2B) include bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, and 1,2-bis (4 -Hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3-methyl-4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) butane, 2 , 2-bis (4-hydroxyphenyl) octane, 4,4-bis (4-hydroxyphenyl) heptane, 1,1-bis (4-hydroxyphenyl) -1,1-diphenylmethane, 1,1-bis (4 -Hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) -1-phenylmethane, bis (4-hydroxyphenyl) ) Ether, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2, 2-bis (3-methyl-4-hydroxyphenyl) propane, 2- (3-methyl-4-hydroxyphenyl) -2- (4-hydroxyphenyl) -1-phenylethane, bis (3-methyl-4- Hydroxyphenyl) sulfide, bis (3-methyl-4-hydroxyphenyl) sulfone, bis (3-methyl-4-hydroxyphenyl) methane, 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane, 2, 2-bis (2-methyl-4-hydroxyphenyl) propane, 1,1-bis (2-butyl) 4-hydroxy-5-methylphenyl) butane, 1,1-bis (2-tert-butyl-4-hydroxy-3-methylphenyl) ethane, 1,1-bis (2-tert-butyl-4-hydroxy-) 5-methylphenyl) propane, 1,1-bis (2-tert-butyl-4-hydroxy-5-methylphenyl) butane, 1,1-bis (2-tert-butyl-4-hydroxy-5-methylphenyl) ) Isobutane, 1,1-bis (2-tert-butyl-4-hydroxy-5-methylphenyl) heptane, 1,1-bis (2-tert-butyl-4-hydroxy-5-methylphenyl) -1- Phenylmethane, 1,1-bis (2-tert-amyl-4-hydroxy-5-methylphenyl) butane, bis (3-chloro-4-hydroxyphenyl) ) Methane, bis (3,5-dibromo-4-hydroxyphenyl) methane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 2,2-bis (3-fluoro-4-hydroxyphenyl) Propane, 2,2-bis (3-bromo-4-hydroxyphenyl) propane, 2,2-bis (3,5-difluoro-4-hydroxyphenyl) propane, 2,2-bis (3,5-dichloro- 4-hydroxyphenyl) propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, 2,2-bis (3-bromo-4-hydroxy-5-chlorophenyl) propane, 2,2- Bis (3,5-dichloro-4-hydroxyphenyl) butane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) butane, 1-phenyl-1, - bis (3-fluoro-4-hydroxyphenyl) ethane, bis (3-fluoro-4-hydroxyphenyl) ether, 1,1-bis (3-cyclohexyl-4-hydroxyphenyl) cyclohexane. These bisphenol compounds may be used alone or in combination.

  In the specific polycarbonate resin, the copolymerization ratio of the structural unit represented by the general formula (A) is preferably in the range of 5 mol% or more and 95 mol% or less with respect to all the structural units constituting the polycarbonate resin. From the viewpoint of improving the mechanical strength and improving the wear resistance, it is preferably in the range of 5 mol% to 50 mol%, more preferably in the range of 15 mol% to 25 mol%.

  Specific examples of the specific polycarbonate resin include the following, but are not limited thereto. In the exemplified compounds, m and n represent copolymerization ratios.

  Here, in the above exemplary compounds, m and n represent copolymerization ratios (molar ratios), but m: n = 95: 5 to 5:95 or less, 50:50 to 5:95, and more preferably. Is in the range of 15:85 to 25:75.

  The weight average molecular weight of the specific polycarbonate resin is preferably in the range of 20000 to 1200000, more preferably in the range of 40000 to 100000, and particularly preferably in the range of 60000 to 80000.

  In addition, you may use other binder resin together with specific polycarbonate resin in the range which does not impair a function. Examples of the other binder resin include polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile-styrene copolymer. Resin, acrylonitrile-butadiene copolymer resin, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, Insulating resins such as silicone resin, phenol-formaldehyde resin, polyacrylamide resin, polyamide resin, chlorinated rubber, and polyvinylcarbazole, polyvinylanthracene, polyvinyl chloride Organic photoconductive polymers such as Rupiren like. These other binder resins may be used alone or in combination of two or more.

Here, the specific polycarbonate resin may be, for example, 10% by mass or more and 90% by mass or less, and preferably 30% by mass or more and 90% by mass or less, with respect to the total solid content of the outermost surface layer (charge transport layer). Desirably, it is 50 mass% or more and 90 mass% or less.
Also. The blending ratio (mass ratio) of the binder resin (specific polycarbonate resin + other binder resin) and the charge transport material is desirably 10: 1 to 1: 5.

The antioxidant will be described.
As the antioxidant, a hindered phenol antioxidant is employed.
Examples of the hindered phenol antioxidant include 2,6-di-t-butyl-4-methylphenol, 2,5-di-t-butylhydroquinone, N, N′-hexamethylenebis (3,5 -Di-t-butyl-4-hydroxyhydrocinnamide, 3,5-di-t-butyl-4-hydroxy-benzylphosphonate-diethyl ester, 2,4-bis [(octylthio) methyl] -o- Cresol, 2,6-di-tert-butyl-4-ethylphenol, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) [= 2,2-methylenebis (6-tert-butyl-4- Methylphenol)], 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 2,5-di-t-amylhydroquinone, 2-t-butyl-6- (3-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 4,4'-butylidenebis (3-methyl -6-t-butylphenol) and the like.
Among these, 2,6-di-t-butyl-4-methylphenol, 2,2′-methylenebis (4-methyl-6) is used from the viewpoint of improving the mechanical strength of the outermost surface layer and increasing the wear resistance. -T-butylphenol) [= 2,2-methylenebis (6-tert-butyl-4-methylphenol)] and the like.

The content of the antioxidant (hindered phenol-based antioxidant) needs to be 15% by mass or more with respect to the binder resin, preferably 15% by mass to 30% by mass, more preferably 15%. It is not less than 25% by mass and more desirably not less than 16% by mass and not more than 22% by mass.
By setting the content of the antioxidant (hindered phenol-based antioxidant) in the above range, the wear resistance of the outermost surface layer is improved. On the other hand, if the content is too large, the outermost surface layer tends to become brittle.

The charge transporting material will be described.
Examples of the charge transport material include oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [ Pyrazoline derivatives such as pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, N, N′-bis (3,4-dimethylphenyl) biphenyl- Aromatic tertiary amino compounds such as 4-amine, tri (p-methylphenyl) aminyl-4-amine, dibenzylaniline, N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine Aromatic tertiary diamino compounds such as 3- (4'-dimethylaminophenyl) -5,6-di- (4'-methoxyphenyl) -1,2,4 1,2,4-triazine derivatives such as triazine, hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, 6-hydroxy-2,3- Benzofuran derivatives such as di (p-methoxyphenyl) benzofuran, α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N-diphenylaniline, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, poly -Hole transport materials such as -N-vinylcarbazole and its derivatives, quinone compounds such as chloranil and broanthraquinone, tetraanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2,4,5,7 -Fluorenone such as tetranitro-9-fluorenone Examples thereof include an electron transport material such as a compound, a xanthone compound, and a thiophene compound, and a polymer having a group consisting of the above-described compounds in a main chain or a side chain.
As these charge transport materials, aromatic tertiary amine compounds and aromatic tertiary diamine compounds are desirable, and in particular, from the viewpoint of compatibility when used in combination with the charge transport material represented by the general formula (1), N, N'-bis (3-methylphenyl) -N, N'-diphenylbenzidine is preferred.
These charge transport materials may be used alone or in combination of two or more.

Other additives will be described.
The charge transport layer preferably contains fluororesin particles from the viewpoint of improving the mechanical strength of the outermost surface layer and enhancing the wear resistance.
Examples of the fluororesin particles include a tetrafluoroethylene resin, a trifluoroethylene chloride resin, a hexafluoropropylene resin, a vinyl fluoride resin, a vinylidene fluoride resin, a difluorodiethylene chloride resin, and copolymers thereof. It is desirable to select one or more of the particles. Among these, as the fluororesin particles, tetrafluoroethylene resin particles and vinylidene fluoride resin particles are particularly desirable.

The primary particle size of the fluororesin particles is preferably 0.05 μm or more and 1 μm or less, and preferably 0.1 μm or more and 0.5 μm or less.
The primary particles are obtained by obtaining a sample piece from the outermost surface layer (charge transport layer) of the electrophotographic photosensitive member, and observing this with a SEM (scanning electron microscope) at a magnification of 5000 times or more, for example. The maximum diameter of the fluororesin particles is measured, and this is the average value obtained for 50 particles. Note that a JSM-6700F manufactured by JEOL Ltd. is used as the SEM, and a secondary electron image with an acceleration voltage of 5 kV is observed.

  The fluororesin particles are preferably used in combination with a fluorine-based graft polymer as a dispersant. The amount of the dispersant is not particularly limited, but is preferably 0.1% by mass or more and 10% by mass or less with respect to the fluororesin particles.

  The content of the fluororesin particles is desirably 2% by mass or more and 15% by mass or less, and more desirably 4% by mass or more and 12% by mass or less with respect to the total solid content of the charge transport layer (outermost surface layer). More preferably, it is 6 mass% or more and 10 mass% or less.

The charge transport layer may further contain a fluorine-modified silicone oil as necessary. Examples of the fluorine-modified silicone oil include fluorine-modified silicone oil in which a part or all of the substituents of the organopolysiloxane are substituted with a fluoroalkyl group (for example, a fluoroalkyl group having 1 to 10 carbon atoms).
The content of the fluorine-modified silicone oil is, for example, preferably in the range of 0.1 ppm to 1000 ppm, and preferably in the range of 0.5 ppm to 500 ppm.

The charge transport layer is formed using a charge transport layer forming coating solution in which the above components are added to a solvent. As a method for dispersing particles (for example, fluororesin particles) in the coating liquid for forming the charge transport layer, a media dispersing machine such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, a stirring, an ultrasonic dispersing machine, a roll mill, etc. Medialess dispersers such as high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high-pressure state, and a penetration method in which a fine flow path is dispersed in a high-pressure state.
For example, when fluorine resin particles are dispersed in the charge transport layer forming coating solution, that is, when fluorine resin particles are included in the charge transport layer, a fluorosurfactant or fluorine-based surfactant is used as a dispersion stabilizer for the fluororesin particles. It is preferable to use a graft polymer in combination. Examples of the fluorine-based graft polymer include a macromonomer composed of an acrylic ester compound, a methacrylic ester compound, a styrene compound, and a resin graft-polymerized from perfluoroalkylethyl methacrylate.
The content of the fluorosurfactant or the fluorograft polymer is preferably, for example, from 1% by mass to 5% by mass with respect to the fluororesin particles.

  As a method for applying the charge transport layer forming coating solution on the charge generation layer, dip coating method, push-up coating method, wire bar coating method, spray coating method, blade coating method, knife coating method, curtain coating method, etc. The method is used.

  The film thickness of the charge transport layer is preferably 25 μm or more as described above, but may be, for example, 5 μm or more and less than 25 μm.

Next, the single layer type photosensitive layer will be described.
The single-layer type photosensitive layer includes, for example, a charge generation material, a binder resin, and a charge transport material represented by the general formula (1).

The content of the charge generating material in the single-layer type photosensitive layer is about 10% by mass to 85% by mass, desirably 20% by mass to 50% by mass. In addition, the content of the charge transport material is desirably 5% by mass or more and 50% by mass or less.
The film thickness of the single-layer photosensitive layer is preferably 25 μm or more as described above, but may be, for example, 5 μm or more and less than 25 μm.

  Each layer constituting the photosensitive layer may contain additives such as a light stabilizer and a heat stabilizer. For example, as an antioxidant, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, an organic sulfur compound, an organic phosphorus compound, and the like can be given. Examples of the light stabilizer include derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine.

Further, each layer constituting the photosensitive layer may contain at least one electron accepting substance. Examples of the electron acceptor include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, Examples include chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, and phthalic acid. Of these, benzene derivatives having an electron-withdrawing substituent such as fluorenone, quinone, Cl, CN, and NO ₂ are particularly desirable.

  The electrophotographic photoreceptor 10 may have a form in which a protective layer is separately provided on the photosensitive layer. In the case of this embodiment, the protective layer corresponds to the outermost surface layer and has the above composition.

(Image forming device / process cartridge)
An image forming apparatus according to this embodiment includes an electrophotographic photosensitive member, a charging device that charges the electrophotographic photosensitive member, and a latent image that forms an electrostatic latent image by exposing the surface of the charged electrophotographic photosensitive member. Forming device, developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member to form a toner image, and toner image formed on the surface of the electrophotographic photosensitive member on the surface of the recording medium A transfer device for transferring, and a cleaning device for cleaning the surface of the electrophotographic photosensitive member.
The electrophotographic photoreceptor 10 according to the present embodiment is applied as the electrophotographic photoreceptor.

  Note that the image forming apparatus according to the present embodiment forms, for example, an electrophotographic photosensitive member, a charging device that charges the belt electrophotographic photosensitive member, and an electrostatic latent image by exposing the surface of the charged electrophotographic photosensitive member. A latent image forming apparatus, a developing apparatus that develops an electrostatic latent image formed on the surface of an electrophotographic photosensitive member to form a toner image, and a toner image formed on the surface of the electrophotographic photosensitive member is transferred to the surface of a recording medium. At least one selected from the group of a transfer device for cleaning and a cleaning device for cleaning the surface of the electrophotographic photosensitive member may be formed into a cartridge and provided as a process cartridge.

Hereinafter, an image forming apparatus according to the present embodiment will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to the present embodiment.
As shown in FIG. 1, the image forming apparatus 100 according to the present embodiment includes an electrophotographic photosensitive member 10, and a charging device 52 that charges the electrophotographic photosensitive member 10 and a charging device 52 that are charged around the electrophotographic photosensitive member 10. A latent image forming device 54 that exposes the electrophotographic photoreceptor 10 to form a latent image, a developing device 56 that develops the electrostatic latent image formed by the latent image forming device 54 with toner, and forms a toner image; A transfer device 58 that transfers the toner image formed by the device 56 to the recording medium P, and a cleaning device 60 that has a cleaning member 62 that cleans deposits such as residual toner and paper dust on the surface of the electrophotographic photosensitive member 10 after transfer. And.
Further, the image forming apparatus 100 includes a fixing device 40 that fixes the toner image transferred to the recording medium P by the transfer device 58.

  The image forming apparatus 100 according to the present embodiment is not limited to the above-described configuration. For example, an intermediate transfer type image forming apparatus using an intermediate transfer member and an image forming unit that forms toner images of each color are arranged in parallel. A so-called tandem image forming apparatus may be used.

  Hereinafter, details of main components in the image forming apparatus 100 according to the present embodiment will be described.

  Examples of the charging device 52 include a contact-type charger using a conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, and the like. Further, examples of the charging device 20 include a non-contact type roller charger and a known charger such as a scorotron charger using a corona discharge or a corotron charger.

  Examples of the latent image forming device 54 include optical equipment that exposes the surface of the electrophotographic photoreceptor 10 with light such as semiconductor laser light, LED light, and liquid crystal shutter light imagewise. The wavelength of the light source is preferably in the spectral sensitivity region of the electrophotographic photosensitive member. As the wavelength of the semiconductor laser, for example, near infrared having an oscillation wavelength around 780 nm is preferable. However, the present invention is not limited to this wavelength, and a laser having an oscillation wavelength of 600 nm or a laser having an oscillation wavelength of 400 nm to 450 nm as a blue laser may be used. Further, as the exposure apparatus 30, for example, a surface emitting laser light source of a multi-beam output type is also effective for color image formation.

  The developing device 56 stores a two-component developer composed of toner and a carrier, or a one-component developer containing toner, and supplies the toner contained in the developer to the surface of the electrophotographic photoreceptor 10, thereby The electrostatic latent image formed on the photographic photosensitive member 10 is developed with toner to form a toner image.

  Examples of the transfer device 58 include known transfer chargers such as a contact transfer charger using a belt, a roller, a film, a rubber blade, etc., a scorotron transfer charger using a corona discharge, and a corotron transfer charger. Can be mentioned.

  The cleaning device 60 is a device that cleans deposits such as toner, paper dust, and carriers attached to the surface of the electrophotographic photosensitive member 10 from the surface of the electrophotographic photosensitive member 10. The cleaning device 60 includes a cleaning member 62, and the deposit on the electrophotographic photosensitive member 10 is cleaned by the cleaning member 62. An example of the cleaning member 62 is a plate-like member (so-called cleaning blade).

  The plate-like member as the cleaning member 62 is a plate-like member extending in the direction along the rotation axis of the electrophotographic photosensitive member 10, and the electrophotographic photosensitive member 10 is charged with an electron from a position charged by the charging device 52. A tip portion (hereinafter referred to as an edge portion) is provided on the upstream side in the rotation direction (arrow a) of the photographic photosensitive member 10 so as to be in contact with pressure.

  The plate-like member (cleaning member 62) is an untransferred residual toner remaining on the electrophotographic photosensitive member 10 without being transferred to the recording medium P by the transfer device 58 when the electrophotographic photosensitive member 10 rotates in the direction of arrow a. Or clean paper dust.

  Examples of the material of the plate-like member include known elastic materials, such as urethane rubber, silicon rubber, fluorine rubber, chloroprene rubber, and butadiene rubber. Among these, polyurethane rubber is particularly preferable.

  The cleaning member 62 may be a brush-like member or a columnar member. Examples of the brush-like member include a cylindrical member having conductive resin fibers and animal hairs on the outer peripheral surface of the conductive substrate. A voltage having a polarity opposite to that of the toner held on the electrophotographic photosensitive member 10 is used. A member that cleans deposits on the electrophotographic photosensitive member 10 when applied to the conductive substrate is exemplified. In addition, the columnar member has a configuration in which a magnet is fixedly disposed inside and a cylindrical nonmagnetic sleeve that is rotated on the outer periphery thereof is provided, and a magnetic carrier is held on the surface of the sleeve so that an electrophotographic photosensitive member is provided. 12 is a member for collecting the toner. When this cylindrical member is used as the cleaning member 62, a configuration in which a corotron is separately provided for pretreatment may be used.

Next, the operation of the image forming apparatus 100 according to the present embodiment will be described.
In the image forming apparatus 100 according to the present embodiment, the electrophotographic photoreceptor 10 is rotated (in the direction of arrow a in FIG. 1). Then, an electrostatic latent image is formed by the latent image forming device 54 on the surface of the electrophotographic photosensitive member 10 charged by the charging device 52 of the electrophotographic photosensitive member 10. When the area where the electrostatic latent image is formed reaches the position where the developing device 56 is provided by the rotation of the electrophotographic photosensitive member 10, the electrostatic latent image is developed by the toner supplied from the developing device 56. Thus, a toner image is formed. Further, when the area where the toner image is formed on the electrophotographic photosensitive member 10 reaches the position where the transfer device 58 is provided by the rotation of the electrophotographic photosensitive member 10, the transfer device 58 uses a conveyance device (not shown). The toner image on the electrophotographic photosensitive member 10 is transferred to the transported recording medium P. When the recording medium P to which the toner image has been transferred is conveyed by a conveyance device (not shown) and reaches the position where the fixing device 40 is provided, the recording medium P is fixed by the fixing device 40 and the image is formed on the recording medium P. Is formed.

The toner remaining on the electrophotographic photosensitive member 10, the adhered carrier, paper dust, and the like are cleaned by the cleaning member 62 of the cleaning device 60.

For example, as illustrated in FIG. 2, the image forming apparatus 100 according to the present embodiment integrally accommodates the electrophotographic photosensitive member 10, the charging device 52, the developing device 56, and the cleaning device 60 in a housing 24. It is also possible to have a form provided with the processed process cartridge 102.
The process cartridge 102 integrally accommodates a plurality of members and is attached to and detached from the image forming apparatus 100.
The configuration of the process cartridge 102 is not limited to this, and is selected, for example, from at least the group of the electrophotographic photosensitive member 10, the charging device 52, the latent image forming device 54, the developing device 56, the transfer device 58, and the cleaning device 60. What is necessary is just a structure which has at least 1 sort.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention. Unless otherwise specified, all “parts” mean “parts by mass”.

(Preparation of electrophotographic photoreceptor 1)
100 parts by mass of zinc oxide (average particle size: 70 nm, manufactured by Teica, specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts by mass of methanol, and KBM603 (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a silane coupling agent. 25 parts by mass was added and stirred for 2 hours. Thereafter, methanol was distilled off under reduced pressure, and baking was performed at 120 ° C. for 3 hours to obtain silane coupling agent surface-treated zinc oxide particles.
60 parts by mass of the surface-treated zinc oxide particles, 0.6 parts by mass of alizarin, 13.5 parts by mass of blocked isocyanate (Sumidule 3173, manufactured by Sumitomo Bayern Urethane Co., Ltd.) as a curing agent, and butyral resin (BM-1, manufactured by Sekisui Chemical Co., Ltd.) 15 parts by mass, 38 parts by mass of a solution obtained by dissolving 85 parts by mass of methyl ethyl ketone and 25 parts by mass of methyl ethyl ketone are mixed, and 4 hours in a sand mill using glass beads having a diameter of 1 mm. Was dispersed to obtain a dispersion. To the obtained dispersion, 0.005 parts by mass of dioctyltin dilaurate and 4.0 parts by mass of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone) are added as a catalyst to obtain an undercoat layer coating solution. It was. This coating solution was applied onto an aluminum substrate having a diameter of 30 mm by a dip coating method, followed by drying and curing at 180 ° C. for 40 minutes to obtain an undercoat layer having a thickness of 23 μm.

  Next, as a charge generation material, it has strong diffraction peaks at Bragg angles (2θ ± 0.2 °) with respect to CuKα characteristic X-rays of at least 7.4 °, 16.6 °, 25.5 ° and 28.3 °. Using a glass bead having a diameter of 1 mm, a mixture of 15 parts by mass of chlorogallium phthalocyanine crystal, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide) and 300 parts by mass of n-butyl alcohol was used. Then, it was dispersed in a sand mill for 4 hours to obtain a coating solution for the charge generation layer. This charge generation layer coating solution was dip coated on the undercoat layer and dried to obtain a charge generation layer having a thickness of 0.2 μm.

Next, as a material for forming the charge transport layer, liquid A: 1.0 part by mass of tetrafluoroethylene resin particles (average particle size: 0.2 μm), fluorine-based graft polymer (GF300, manufactured by Toagosei Co., Ltd., weight average molecular weight) 30,000) 0.01 part by mass was maintained at a liquid temperature of 20 ° C. together with 4 parts by mass of tetrahydrofuran and 1 part by mass of toluene, and stirred and mixed for 48 hours to obtain a tetrafluoroethylene resin particle suspension. Next, Liquid B: 4 parts by mass of N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine as a charge transport material, the following structural formula (A-1), and copolymerization ratio m : 6 parts by mass of biphenyl copolymerization type polycarbonate resin (weight average molecular weight 62,000) of n = 25: 75, 2,6-di-t-butyl-4-methyl as hindered phenol-based antioxidant (S1) 1.0 part by mass of phenol was mixed and 24 parts by mass of tetrahydrofuran and 11 parts by mass of toluene were mixed and dissolved.
After the A liquid was added to the B liquid and stirred and mixed, the pressure was increased to 500 kgf / cm ² using a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) equipped with a through-type chamber having a fine flow path. 10 ppm of fluorine-modified silicone oil (trade name: FL-100, manufactured by Shin-Etsu Silicone Co., Ltd.) was added to the solution obtained by repeating the dispersion treatment six times, and stirred to obtain a coating solution for forming a charge transport layer. This coating solution was applied onto the charge generation layer and dried at 115 ° C. for 40 minutes to form a charge transport layer having a thickness of 20 μm. Thus, the electrophotographic photoreceptor 1 was produced.

(Preparation of electrophotographic photoreceptor 2)
The electrophotographic photosensitive member 2 was prepared in the same manner as the electrophotographic photosensitive member 1 except that the amount of the tetrafluoroethylene resin particles described in the electrophotographic photosensitive member 1 was 0 parts by mass (a state containing no fluorine). Produced.

(Preparation of electrophotographic photoreceptor 3)
Instead of the biphenyl copolymerized polycarbonate resin, a biphenyl copolymerized polycarbonate resin represented by the structural formula (A-1) and having a copolymerization ratio m: n = 15: 85 (weight average molecular weight 52,000) is used. An electrophotographic photoreceptor 3 was produced in the same manner as the electrophotographic photoreceptor 1 except that the amount of tetrafluoroethylene resin particles was 0 parts by mass (a state containing no fluorine).

(Preparation of electrophotographic photoreceptor 4)
Instead of the biphenyl copolymerization type polycarbonate resin described in the electrophotographic photoreceptor 1, it is represented by the structural formula (A-1) and has a copolymerization ratio of m: n = 5: 95 (weight average molecular weight 48,000). The electrophotographic photosensitive member 4 was prepared in the same manner as the electrophotographic photosensitive member 1 except that a biphenyl copolymerized polycarbonate resin was used and the amount of tetrafluoroethylene resin particles was changed to 0 part by mass (a state containing no fluorine). Produced.

(Preparation of electrophotographic photoreceptor 5)
Instead of the biphenyl copolymerization type polycarbonate resin described in the electrophotographic photosensitive member 1, it is represented by the structural formula (A-1) and has a copolymerization ratio m: n = 0: 100 (weight average molecular weight 40,000). An electrophotographic photosensitive member 5 was produced in the same manner as the electrophotographic photosensitive member 1 except that polycarbonate resin was used and the amount of tetrafluoroethylene resin particles was changed to 0 part by mass (a state containing no fluorine).

(Preparation of electrophotographic photoreceptor 6)
Instead of the antioxidant described in the electrophotographic photosensitive member 1, a hindered phenol-based antioxidant (S2), a summizer MDP-S (manufactured by Sumitomo Chemical Co., Ltd .: 2,2′-methylenebis (4-methyl-6-t- Butylphenol) [= 2,2-methylenebis (6-tert-butyl-4-methylphenol)])) 1.0 parts by weight, except that 1.0 part by weight was used. 6 was produced.

(Preparation of electrophotographic photoreceptor 7)
Instead of the antioxidant described in the electrophotographic photosensitive member 1, a hindered phenol-based antioxidant (S2), a summizer MDP-S (manufactured by Sumitomo Chemical Co., Ltd .: 2,2′-methylenebis (4-methyl-6-t -Butylphenol) [= 2,2-methylenebis (6-tert-butyl-4-methylphenol)])) 1.0 part by mass, and the amount of tetrafluoroethylene resin particles is 0 part by mass (containing no fluorine) The electrophotographic photosensitive member 7 was produced in the same manner as the electrophotographic photosensitive member 1 except that the state) was changed.

(Preparation of electrophotographic photoreceptor 8)
Instead of the biphenyl copolymerized polycarbonate resin described in the electrophotographic photosensitive member 1, it is represented by the following structural formula (A-2), and has a copolymerization ratio m: n = 25: 75 (weight average molecular weight 74,000). An electrophotographic photoreceptor 8 was produced in the same manner as the electrophotographic photoreceptor 1 except that a biphenyl copolymer type polycarbonate resin was used.

(Preparation of electrophotographic photoreceptor 9)
Instead of the biphenyl copolymerization type polycarbonate resin described in the electrophotographic photoreceptor 1, it is represented by the structural formula (A-2) and has a copolymerization ratio m: n = 25: 75 (weight average molecular weight 74,000). The electrophotographic photosensitive member 9 was prepared in the same manner as the electrophotographic photosensitive member 1 except that a biphenyl copolymerized polycarbonate resin was used and the amount of tetrafluoroethylene resin particles was changed to 0 part by mass (a state containing no fluorine). Produced.

(Preparation of electrophotographic photoreceptor 10)
Instead of the biphenyl copolymerization type polycarbonate resin described in the electrophotographic photoreceptor 1, it is represented by the structural formula (A-2) and has a copolymerization ratio of m: n = 15: 85 (weight average molecular weight 52,000). The electrophotographic photosensitive member 10 was prepared in the same manner as the electrophotographic photosensitive member 1 except that a biphenyl copolymerized polycarbonate resin was used and the amount of the tetrafluoroethylene resin particles was 0 parts by mass (a state containing no fluorine). Produced.

(Preparation of electrophotographic photoreceptor 11)
Instead of the biphenyl copolymerization type polycarbonate resin described in the electrophotographic photoreceptor 1, it is represented by the structural formula (A-2) and has a copolymerization ratio m: n = 5: 95 (weight average molecular weight 63,000). The electrophotographic photoreceptor 11 was prepared in the same manner as the electrophotographic photoreceptor 1 except that a biphenyl copolymerized polycarbonate resin was used and the amount of tetrafluoroethylene resin particles was 0 parts by mass (a state containing no fluorine). Produced.

(Preparation of electrophotographic photoreceptor 12)
Instead of the biphenyl copolymerization type polycarbonate resin described in the electrophotographic photoreceptor 1, it is represented by the structural formula (A-2) and has a copolymerization ratio m: n = 0: 100 (weight average molecular weight 60,000). The electrophotographic photosensitive member 12 was produced in the same manner as the electrophotographic photosensitive member 1 except that the polycarbonate resin shown was used and the amount of tetrafluoroethylene resin particles was changed to 0 part by mass (a state containing no fluorine). .

(Preparation of electrophotographic photoreceptor 13)
Other than using 1.285 parts by mass of the hindered phenolic antioxidant (S1) described in the electrophotographic photoreceptor 1 and setting the amount of tetrafluoroethylene resin particles to 0 parts by mass (containing no fluorine). Produced an electrophotographic photoreceptor 13 in the same manner as the electrophotographic photoreceptor 1.

(Preparation of electrophotographic photoreceptor 14)
Except that 0.85 parts by mass of the hindered phenolic antioxidant (S1) described in the electrophotographic photoreceptor 1 is used, and the amount of tetrafluoroethylene resin particles is 0 parts by mass (a state not containing fluorine). Produced an electrophotographic photoreceptor 14 in the same manner as the electrophotographic photoreceptor 1.

(Preparation of electrophotographic photoreceptor 15)
Instead of the antioxidant described in the electrophotographic photosensitive member 1, a hindered phenol-based antioxidant (S2), a summizer MDP-S (manufactured by Sumitomo Chemical Co., Ltd .: 2,2′-methylenebis (4-methyl-6-t -Butylphenol) [= 2,2-methylenebis (6-tert-butyl-4-methylphenol)])) 0.85 parts by mass, and the amount of tetrafluoroethylene resin particles is 0 parts by mass (containing no fluorine) The electrophotographic photosensitive member 15 was produced in the same manner as the electrophotographic photosensitive member 1 except that the state) was changed.

(Preparation of electrophotographic photoreceptor 16)
Other than using 0.5 parts by mass of the hindered phenolic antioxidant (S1) described in the electrophotographic photosensitive member 1 and setting the amount of tetrafluoroethylene resin particles to 0 parts by mass (a state that does not contain fluorine). Produced an electrophotographic photoreceptor 16 in the same manner as the electrophotographic photoreceptor 1.

(Preparation of electrophotographic photoreceptor 17)
Other than using 0.1 parts by mass of the hindered phenolic antioxidant (S1) described in the electrophotographic photoreceptor 1 and setting the amount of tetrafluoroethylene resin particles to 0 parts by mass (containing no fluorine). Produced an electrophotographic photoreceptor 17 in the same manner as the electrophotographic photoreceptor 1.

(Preparation of electrophotographic photoreceptor 18)
Instead of the hindered phenol-based antioxidant (S1) described in the electrophotographic photoreceptor 1, 1.0 part by mass of a sulfur-based antioxidant (S3), Sumitizer TPM (manufactured by Sumitomo Chemical Co., Ltd.) is used. An electrophotographic photoreceptor 18 was produced in the same manner as the electrophotographic photoreceptor 1 except that the amount of ethylene resin particles was 0 parts by mass (a state containing no fluorine).

(Preparation of electrophotographic photoreceptor 19)
Instead of the hindered phenolic antioxidant (S1) described in the electrophotographic photosensitive member 1, 1.0 part by mass of a phosphorus antioxidant (S4) IRGAFOS168 (manufactured by BASF) is used, and a tetrafluoroethylene resin is used. An electrophotographic photoreceptor 19 was produced in the same manner as the electrophotographic photoreceptor 1 except that the amount of particles was 0 parts by mass (a state containing no fluorine).

(Preparation of electrophotographic photoreceptor 20)
Other than using 1.5 parts by mass of the hindered phenolic antioxidant (S1) described in the electrophotographic photoreceptor 1 and setting the amount of tetrafluoroethylene resin particles to 0 parts by mass (containing no fluorine). Produced an electrophotographic photoreceptor 20 in the same manner as the electrophotographic photoreceptor 1.

(Preparation of electrophotographic photoreceptor 21)
Other than using 1.7 parts by mass of the hindered phenolic antioxidant (S1) described in the electrophotographic photosensitive member 1 and setting the amount of tetrafluoroethylene resin particles to 0 parts by mass (containing no fluorine). Produced an electrophotographic photosensitive member 21 in the same manner as the electrophotographic photosensitive member 1.

  Table 1 summarizes the structural formula, copolymerization ratio m: n, antioxidant type, antioxidant amount, and fluororesin particle amount of the polycarbonate used in the preparation of each electrophotographic photosensitive member.

(Examples 1-13, Comparative Examples 1-8)
The electrophotographic photoreceptors shown in Table 2 were referred to as Examples 1 to 13 and Comparative Examples 1 to 8, respectively.

(Evaluation test)
The electrophotographic photosensitive member of each example was mounted on a drum cartridge of Docu Print 505 manufactured by Fuji Xerox Co., Ltd., and an abrasion resistance evaluation test was performed. In the above evaluation test, an image carrier after continuously printing 50,000 sheets and 100,000 sheets of an image quality pattern with an average image density of 10% on A4 paper in an environment of 10 ° C. and 15 RH% was taken out. The wear rate (amount of wear per 1000 rotations of the image carrier) was determined based on the difference in film thickness of the image carrier, and the wear resistance was evaluated.
Further, wear stability was evaluated based on the following evaluation criteria.

(Wear stability evaluation criteria)
G1: Less than 5% increase in wear rate from 0 to 50000 sheets and wear rate from 50000 to 100000 sheets G2: Increase in wear rate from 0 to 50000 sheets and increase in wear rate from 50000 to 100000 sheets 5% or more and 10% or less G3: Wear rate from 0 to 50000 sheets and increase in wear rate from 50000 to 100000 sheets are 10% or more and 15% or less G4: Wear rate from 0 to 50000 sheets and 50000 More than 15% increase in wear rate from 1 to 100,000 sheets

  The above evaluation results are shown in Table 2.

  From the above results, it can be seen that the present example has a lower wear rate and less variation (good wear stability) than the comparative example.

DESCRIPTION OF SYMBOLS 1 Subbing layer, 2 Charge generation layer, 3 Charge transport layer, 4 Base | substrate, 6 Photosensitive layer, 7 Single layer type photosensitive layer, 10 Image holding body, 10A Image holding body, 10B Electrophotographic photosensitive body, 52 Charging apparatus, 54 Latent image forming device, 56 developing device, 58 transfer device, 62 cleaning member

Claims (6)

Having at least a photosensitive layer on the substrate;
The outermost surface layer includes a binder resin having a structural unit represented by the following general formula (A), and a hindered phenol-based antioxidant having a content of 15% by mass or more based on the binder resin. An electrophotographic photosensitive member having a layer formed thereon.


(In the general formula (A), R ¹ and R ² are each independently a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a group having 6 to 12 carbon atoms. Represents an aryl group, and a and b each independently represent an integer of 0 or more and 4 or less.) The electrophotographic photosensitive member according to claim 1, wherein the binder resin is a copolymer having a structural unit represented by the general formula (A) and a structural unit represented by the following general formula (B). body.


(In General Formula (B), R ³ and R ⁴ are each independently a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a carbon atom having 6 to 12 carbon atoms. Each represents an aryl group, and c and d each independently represent an integer of 0 or more and 4 or less, X represents —CR ⁵ R ⁶ — (wherein R ⁵ and R ⁶ each independently represents a hydrogen atom, trifluoromethyl) Group, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms), a 1,1-cycloalkylene group having 5 to 11 carbon atoms, and α having 2 to 10 carbon atoms. , Ω-alkylene group, —O—, —S—, —SO—, or —SO ₂ —.   The binder resin is a copolymer in which the copolymerization ratio of the structural unit represented by the general formula (A) is 15 mol% or more and 25 mol% or less with respect to all the structural units constituting the binder resin. The electrophotographic photosensitive member according to claim 1.   The electrophotographic photosensitive member according to claim 1, wherein the outermost surface layer of the electrophotographic photosensitive member contains fluororesin particles. The electrophotographic photosensitive member according to any one of claims 1 to 4,
A charging device for charging the electrophotographic photosensitive member;
A latent image forming device that exposes the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image; and
A developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member to form a toner image;
A transfer device for transferring the toner image formed on the surface of the electrophotographic photosensitive member to the surface of a recording medium;
A cleaning device for cleaning the surface of the electrophotographic photosensitive member;
An image forming apparatus comprising: It is detachable from the image forming apparatus,
The electrophotographic photosensitive member according to claim 1,
A charging device that charges the electrophotographic photosensitive member, a latent image forming device that exposes the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image, and an electrostatic latent image formed on the surface of the electrophotographic photosensitive member. Developing device for developing image to form toner image, transfer device for transferring toner image formed on surface of electrophotographic photosensitive member to surface of recording medium, and cleaning device for cleaning surface of electrophotographic photosensitive member At least one selected from the group of:
A process cartridge comprising: