JP2012173511A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor capable of achieving both of suppression of image blurring and improvement in durability.SOLUTION: The electrophotographic photoreceptor comprises a photosensitive layer 2 and a protective layer 6 successively layered on a conductive support body 1. The protective layer 6 contains a polymerization product obtained by polymerizing a radical polymerizable compound and surface-treated metal oxide fine particles 7 prepared by surface treating metal oxide fine particles with a surface treating agent. The surface treating agent comprises two or more kinds of surface treating agents including a surface treating agent having at least a radical polymerizable reactive group and a surface treating agent containing an antioxidation structure.

Description

  The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor used in an image forming apparatus using an electrophotographic system.

  In recent years, organic photoreceptors containing organic photoconductive materials have been widely used as electrophotographic photoreceptors. Organic photoconductors are advantageous for inorganic photoconductors because it is easy to develop materials compatible with various exposure light sources from visible light to infrared light, the ability to select materials without environmental pollution, and low manufacturing costs. Is a point.

  On the other hand, an electrophotographic photosensitive member (hereinafter also referred to as a photosensitive member) is directly charged with electrical or mechanical external force by charging, exposure, development, transfer, cleaning, etc., so that it is charged even when image formation is repeated. There is a demand for durability to maintain stability, such as stability and potential retention.

  In recent years, especially in the digital trend, demand for high-definition and high-quality images has increased, and toners with small particle diameters by polymerization methods such as dissolved suspension toners and emulsion polymerization aggregation toners have become mainstream. The toner having a small particle size has a large adhesion force to the surface of the photoconductor, and the removal of residual toner such as transfer residual toner adhering to the surface of the photoconductor tends to be insufficient. In the cleaning method using a rubber blade, there are phenomena such as "toner slipping" where the toner passes through the blade, "blade curl" where the blade is reversed, or the generation of scratching noise between the photoconductor and the blade, so-called "blade squealing" Likely to happen. In order to solve the above “toner slipping”, it is necessary to increase the contact pressure of the blade to the photosensitive member. However, the repeated use causes a problem that the surface of the organic photosensitive member is worn and the durability is insufficient. appear. Further, it is required to have sufficient durability against deterioration caused by ozone and nitrogen oxides generated during charging.

  For this reason, a technique for improving the mechanical strength by providing a protective layer (or a surface layer) on the surface of the photoreceptor has been proposed.

Specifically, in the protective layer of the photoreceptor, a hybrid containing a curable compound (or also referred to as a polymerization product) obtained by polymerizing a polymerizable compound and a metal oxide whose surface is treated with a reactive compound. A protective layer is used to improve the surface strength. Further, the durability of the photoreceptor is improved by reducing wear due to repeated printing.
However, this technique has a problem that the surface of the photoconductor is difficult to be scraped, and therefore, discharge products are deposited and image blurring occurs.
Therefore, as a countermeasure against image blur, an antioxidant such as a compound having a hindered phenol structure is added to the curable compound of the hybrid protective layer to prevent oxidative deterioration due to deposited discharge products. A technique for suppressing the above is known (for example, Patent Document 1). In addition, a technique for adding an antioxidant containing a curable reactive group to suppress image blur while maintaining surface strength by incorporating an antioxidant into a hybrid protective layer is also known ( For example, Patent Document 2).

JP 2010-107962 A JP 2010-237241 A

However, in the technique of Patent Document 1, an antioxidant is contained as an impurity in the curable compound of the hybrid protective layer, which causes a reduction in the photoreceptor surface strength. As a result, there is a problem that the durability of the improved photoreceptor is lowered.
Further, in the technique of Patent Document 2, since the antioxidant is incorporated into the curable compound, the above-described decrease in durability can be suppressed, but the surface of the metal oxide fine particles contained in the hybrid protective layer is as follows. Since there is a hydroxyl group (OH group), there is water absorption, and the hydroxyl group is a site where image blur is likely to occur. Therefore, if an antioxidant is simply contained in the curable compound of the protective layer, hydroxyl groups remain on the surface of the metal oxide fine particles, and image blur cannot be reliably suppressed.
The present invention has been made in view of the above circumstances, and an object thereof is to provide an electrophotographic photosensitive member capable of achieving both suppression of image blur and improvement in durability.

In order to solve the above problems, the invention of claim 1 is an electrophotographic photosensitive member in which a photosensitive layer and a protective layer are sequentially laminated on a conductive support.
The protective layer contains a polymerization product obtained by polymerizing a radical polymerizable compound and surface-treated metal oxide fine particles obtained by surface-treating metal oxide fine particles with a surface treatment agent;
Provided is an electrophotographic photoreceptor, wherein the surface treatment agent is at least two types of surface treatment agents, a surface treatment agent having a reactive group capable of radical polymerization and a surface treatment agent containing an antioxidant structure. Is done.

  According to a second aspect of the present invention, there is provided the electrophotographic photosensitive member according to the first aspect, wherein the metal oxide fine particles are any one of alumina fine particles, tin oxide fine particles, and titanium oxide fine particles.

  The invention according to claim 3 is characterized in that the surface treatment agent having a reactive group capable of radical polymerization is a compound containing either an acryloyl group or a methacryloyl group. A photoreceptor is provided.

  The invention according to claim 4 is characterized in that the radical polymerizable compound is a polymerizable monomer or polymerizable oligomer containing either an acryloyl group or a methacryloyl group. The described electrophotographic photoreceptor is provided.

According to the present invention, by adding metal oxide fine particles surface-treated with a surface treatment agent having a reactive group capable of radical polymerization, the strength of the polymerized product (curable compound) is improved, and durability during repeated printing is achieved. It is possible to improve the performance.
Also, by adding metal oxide fine particles surface-treated with a surface treatment agent containing an antioxidant structure, the hydroxyl group on the surface of the metal oxide fine particles is converted into a silane coupling reaction with a surface treatment agent containing an antioxidant structure. In addition, by introducing an antioxidant structure near the hydroxyl group remaining on the surface of the metal oxide fine particles, the image is significantly more than simply incorporating an antioxidant into the polymerization product as in the past. Blur can be suppressed.
Further, since the antioxidant structure is incorporated into the crosslinked structure with the radical polymerizable compound, the strength of the polymerization product can be maintained without causing a decrease in the strength of the polymerization product.

It is a schematic diagram showing an example of a layer structure of the electrophotographic photosensitive member according to the present invention. 1 is a schematic cross-sectional view showing an example of an image forming apparatus using an electrophotographic photosensitive member according to the present invention.

Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not limited to these.
In order to improve the abrasion resistance of the photoreceptor, it is preferable to provide a protective layer on the photosensitive layer.
This protective layer is mainly composed of a radical polymerizable compound, and is preferably cured by applying a curing treatment after coating to increase the hardness. Further, by adding surface-treated metal oxide fine particles treated with a surface treatment agent having a radical polymerizable reactive group in the protective layer, a crosslinking reaction with the radical polymerizable compound is performed, and the hardness of the protective layer is further increased. I can do it. However, if the hardness is too high, the discharge product cannot be removed by cleaning and accumulates on the surface of the protective layer, resulting in image blur.

Therefore, in the present invention, the protective layer contains a polymerization product obtained by polymerizing the radically polymerizable compound and the surface-treated metal oxide fine particles obtained by surface-treating the metal oxide fine particles with a surface treatment agent, As the surface treatment agent, at least two types of surface treatment agents, that is, a surface treatment agent having a reactive group capable of radical polymerization and a surface treatment agent containing an antioxidant structure were used.
Thus, by adding metal oxide fine particles surface-treated with a surface treatment agent having a radical polymerizable reactive group, a hard metal is included in the crosslinked structure with the radical polymerizable compound, and as a protective layer The strength is improved, and the abrasion resistance and scratch resistance during repeated printing can be improved.

Further, by adding metal oxide fine particles surface-treated with a surface treatment agent containing an antioxidant structure, it is possible to prevent image deterioration by preventing oxidative deterioration due to deposits on the surface of the photoreceptor. In particular, in the present invention, the hydroxyl groups (OH groups) on the surface of the metal oxide fine particles are eliminated by a silane coupling reaction with a surface treatment agent containing an antioxidant structure, and further remain on the surface of the metal oxide fine particles. By introducing an antioxidant structure in the vicinity of the hydroxyl group, image blurring can be greatly suppressed as compared with the conventional case where an antioxidant is simply incorporated into the polymerization product (curable compound).
In addition, since the antioxidant structure is incorporated into the cross-linked structure with the radical polymerizable compound, the polymerization product does not cause a decrease in the strength of the polymerization product by adding an antioxidant to the polymerization product as in the past. Strength can be maintained.

<Structure of protective layer>
Hereinafter, the protective layer of the present invention will be described in detail.

<Radically polymerizable compound>
The radical polymerizable compound that can be used in the protective layer of the present invention is a polymerizable monomer or polymerizable oligomer having either an acryloyl group or a methacryloyl group as a radical polymerizable reactive group.
Examples of these polymerizable monomers and polymerizable oligomers include the following compounds, but the polymerizable monomers and polymerizable oligomers that can be used in the present invention are not limited thereto.

ここで、Ｒは下記アクリロイル基、Ｒ′は下記メタクリロイル基を表す。

Here, R represents the following acryloyl group, and R ′ represents the following methacryloyl group.

  The above radical polymerizable compound is a known commercial product.

Examples of the radical polymerizable compound of the present invention include the following radical polymerizable compounds in addition to the polymerizable compounds described above.

  The above radical polymerizable compound is easily synthesized by a known synthesis method, that is, starting from pentapentaerythritol, tetrapentaerythritol, pentapentaerythritol or the like as a starting material and performing an ester reaction with these with acrylic acid or methacrylic acid. I can do it.

<Surface treated metal oxide fine particles>
Next, a composition (hereinafter referred to as “surface-treated metal oxide fine particles”) obtained by subjecting metal oxide fine particles to a surface treatment with a surface treatment agent used in the protective layer of the present invention will be described.
The surface treatment agent used for the surface treatment of the metal oxide fine particles may be any surface treatment agent having reactivity with a hydroxyl group or the like present on the surface of the metal oxide fine particles. Among them, at least one surface treatment agent having a reactive group capable of radical polymerization (hereinafter referred to as a surface treatment agent having a radical polymerizable reactive group) and a surface treatment agent containing an antioxidant structure (hereinafter referred to as oxidation). The surface treatment agent is used as a surface treatment agent in combination of one or more, a total of two or more.

[Metal oxide fine particles]
The metal oxide fine particles constituting the surface-treated metal oxide fine particles used in the protective layer of the present invention may be metal oxide particles including transition metals, such as silica (silicon oxide), magnesium oxide, and oxidation. Zinc, lead oxide, alumina (aluminum oxide), tin oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, Metal oxide fine particles such as titanium dioxide, niobium oxide, molybdenum oxide, and vanadium oxide are exemplified, and among these, fine particles of alumina (Al ₂ O ₃ ), tin oxide (SnO ₂ ), and titanium dioxide (TiO ₂ ) are preferable. Further preferred are alumina and tin oxide.

  The number average primary particle size of the metal oxide fine particles is preferably in the range of 1 to 300 nm. Especially preferably, it is 3-100 nm.

  The number average primary particle size of the metal oxide fine particles is a photographic image (excluding aggregated particles) obtained by taking an enlarged photograph of 10,000 times with a scanning electron microscope (manufactured by JEOL Ltd.) and randomly capturing 300 particles with a scanner. The automatic image processing analyzer “LUZEX AP” (manufactured by Nireco Corporation) software version Ver. The number average primary particle size was calculated using 1.32.

[Surface treatment agent having radical polymerizable reactive group]
Next, the surface treating agent used for the surface treatment of the metal oxide fine particles will be described.

  The surface treatment agent having a radical polymerizable reactive group is a radical polymerizable surface treatment agent having reactivity with a hydroxyl group or the like present on the surface of the metal oxide fine particles (hereinafter also referred to as a polymerizable surface treatment agent), Any silane coupling agent having a radically polymerizable reactive group such as a vinyl group, acryloyl group, or methacryloyl group may be used. Examples of the polymerizable surface treating agent having such reactivity include the following known compounds. Illustrated.

_{S-1: CH 2 = CHSi} (CH 3) (OCH 3) 2
_{S-2: CH 2 = CHSi} (OCH 3) 3
S-3: CH ₂ = CHSiCl _{3
S-4: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5: CH 2 = CHCOO} (CH 2) 2 Si (OCH 3) 3
_{S-6: CH 2 = CHCOO} (CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
_{S-7: CH 2 = CHCOO} (CH 2) 3 Si (OCH 3) 3
_{S-8: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) Cl 2
_{S-9: CH 2 = CHCOO} (CH 2) 2 SiCl 3
_{S-10: CH 2 = CHCOO} (CH 2) 3 Si (CH 3) Cl 2
S-11: CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13: CH 2 = C} (CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17: CH 2 = C} (CH 3) COO (CH 2) 2 SiCl 3
_{S-18: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19: CH 2 = C} (CH 3) COO (CH 2) 3 SiCl 3
_{S-20: CH 2 = CHSi} (C 2 H 5) (OCH 3) 2
_{S-21: CH 2 = C} (CH 3) Si (OCH 3) 3
_{S-22: CH 2 = C} (CH 3) Si (OC 2 H 5) 3
_{S-23: CH 2 = CHSi} (OCH 3) 3
_{S-24: CH 2 = C} (CH 3) Si (CH 3) (OCH 3) 2
_{S-25: CH 2 = CHSi} (CH 3) Cl 2
_{S-26: CH 2 = CHCOOSi} (OCH 3) 3
_{S-27: CH 2 = CHCOOSi} (OC 2 H 5) 3
_{S-28: CH 2 = C} (CH 3) COOSi (OCH 3) 3
_{S-29: CH 2 = C} (CH 3) COOSi (OC 2 H 5) 3
_{S-30: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
_{S-31: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) 2 (OCH 3)
_{S-32: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCOCH 3) 2
_{S-33: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (ONHCH 3) 2
_{S-34: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OC 6 H 5) 2
_{S-35: CH 2 = CHCOO} (CH 2) 2 Si (C 10 H 21) (OCH 3) 2
_{S-36: CH 2 = CHCOO} (CH 2) 2 Si (CH 2 C 6 H 5) (OCH 3) 2
Moreover, as a surface treating agent, you may use the silane compound which has a reactive group which can be radically polymerized other than said S-1 to S-36. These surface treatment agents can be used alone or in admixture of two or more.

[Antioxidant surface treatment agent]
The antioxidant surface treatment agent may be any antioxidant surface treatment agent that is reactive with hydroxyl groups and the like that are also present on the surface of the metal oxide fine particles, and preferably has two or more phenol groups and one phenol. It is an antioxidant surface treating agent having a structure represented by the following general formula (a).
Formula _{(a) :( CH 3 (CH} 2) n O) 3 Si-
(However, n is an integer of 0-2.)
Specifically, a silane coupling agent having an antioxidant structure as described below is exemplified.

ここでＲｓ１およびＲｓ２は下記に示す官能基である。
Ｒｓ１ ＝ − Ｓｉ（ＯＣＨ_３）_３
Ｒｓ２ ＝ − Ｓｉ（ＯＣ_２Ｈ_５）_３
また、酸化防止表面処理剤としては、前記Ａ−１〜Ａ−１６に限定されず、酸化防止構造を含有するシラン化合物を用いることができる。これらの酸化防止表面処理剤は、単独で、または２種以上併用しても良い。

Here, Rs1 and Rs2 are functional groups shown below.
_{Rs1 = - Si (OCH 3)} 3
_{Rs2 = - Si (OC 2 H} 5) 3
Moreover, as an antioxidant surface treating agent, it is not limited to said A-1 to A-16, The silane compound containing an antioxidant structure can be used. These antioxidant surface treatment agents may be used alone or in combination of two or more.

  The antioxidant surface treating agent of the present invention can be synthesized by a known method in which an antioxidant, which is commercially available as an example, and a halogenated alkoxysilane are reacted under a catalyst. Examples of commercially available antioxidants include SUMILIZER (registered trademark) GA-80 (manufactured by Sumitomo Chemical Co., Ltd.), and examples of halogenated alkoxysilanes include chlorotriethoxysilane (manufactured by Aldrich).

  The polymerizable surface treatment agent and the antioxidant surface treatment agent can be used in any ratio, but the antioxidant surface treatment agent is 5 to 20% by mass of the total surface treatment agent, and the polymerizable surface treatment agent is 80 mass% to 95 mass% of the total surface treatment agent is preferable. Within this range, the cross-linking effect and the antioxidant effect can be controlled within a preferable range.

[Preparation of surface-treated metal oxide fine particles]
When the surface treatment is performed, a wet media dispersion type apparatus is used by using 0.1 to 100 parts by mass of the polymerizable surface treatment agent and the antioxidant surface treatment agent and 50 to 5000 parts by mass of the solvent with respect to 100 parts by mass of the particles. It is preferable to process. Moreover, it can also process by a dry type. Below, the surface treatment method which manufactures the metal oxide particle surface-treated uniformly with the surface treating agent is demonstrated.

  That is, by subjecting a slurry (suspension of solid particles) containing metal oxide particles and a surface treatment agent to wet pulverization, the metal oxide particles are refined and the surface treatment of the particles proceeds at the same time. Thereafter, by removing the solvent and pulverizing, metal oxide particles that are uniformly surface-treated with the surface treatment agent can be obtained.

  The wet media dispersion type apparatus, which is a surface treatment apparatus used in the present invention, is filled with beads as a medium in a container and further rotated at high speed by a stirring disk attached perpendicularly to the rotation axis, thereby forming a metal oxide. It is an apparatus having a step of crushing and pulverizing and dispersing the agglomerated particles, as long as the metal oxide particles can be sufficiently dispersed and subjected to surface treatment when the surface treatment is performed on the metal oxide particles. For example, various types such as a vertical type, a horizontal type, a continuous type, and a batch type can be adopted without any problem. Specifically, a sand mill, ultra visco mill, pearl mill, glen mill, dyno mill, agitator mill, dynamic mill and the like can be used. These dispersion-type devices are pulverized and dispersed by impact crushing, friction, shearing, shear stress, etc., using a grinding medium (media) such as balls and beads.

  As the beads used in the wet media dispersion type apparatus, balls made of glass, alumina, zircon, zirconia, steel, flint stone and the like can be used, and those made of zirconia or zircon are particularly preferable. Further, as the size of the beads, those having a diameter of about 1 to 2 mm are usually used, but in the present invention, those having a diameter of about 0.1 to 1.0 mm are preferably used.

  Various materials such as stainless steel, nylon and ceramic can be used for the disk and container inner wall used in the wet media dispersion type apparatus. In the present invention, the disk and container inner wall made of ceramic such as zirconia or silicon carbide are particularly used. Is preferred.

  By the wet treatment as described above, metal oxide particles having a reactive group capable of reacting with a reactive acryloyl group or a reactive methacryloyl group and an antioxidant structure can be obtained by surface treatment with a surface treating agent.

  Furthermore, the protective layer according to the present invention can be formed by using a known resin together with the compound obtained by the reaction.

  Known resins include polyester resins, polycarbonate resins, polyurethane resins, acrylic resins, epoxy resins, silicone resins, alkyd resins, and the like.

  In addition to these, the protective layer according to the present invention may be formed by containing a polymerization initiator, lubricant particles and the like as necessary.

<Polymerization initiator>
In the present invention, the protective layer is formed by curing reaction of the polymerizable compound, but the curing reaction is performed by a method using an electron beam cleavage reaction or a method using light or heat in the presence of a radical polymerization initiator. be able to. When the curing reaction is performed using a radical polymerization initiator, any of a photopolymerization initiator and a thermal polymerization initiator can be used as the polymerization initiator. Further, both light and heat initiators can be used in combination.

  Examples of the polymerization initiator that can be used in the present invention include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylazobisvaleronyl), 2,2′-azobis (2 Azo compounds such as -methylbutyronitrile), benzoyl peroxide (BPO), di-tert-butyl hydroperoxide, tert-butyl hydroperoxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, peroxide Examples thereof include thermal polymerization initiators such as peroxides such as lauroyl.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (Irgacure 369: manufactured by BASF Japan Ltd.), 2-hydroxy-2-methyl -1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, etc. Acetophenone or ketal photoinitiators, benzoin, benzoin methyl ether, Benzoin ether photopolymerization initiators such as zoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl Benzophenone photopolymerization initiators such as ether, acrylated benzophenone, 1,4-benzoylbenzene, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichloro Examples thereof include thioxanthone photopolymerization initiators such as thioxanthone.

  Other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine Oxide (Irgacure 819: manufactured by BASF Japan), bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine And imidazole compounds. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.

  The polymerization initiator used in the present invention is preferably a photopolymerization initiator, preferably an alkylphenone compound or a phosphine oxide compound, more preferably an initiator having an α-hydroxyacetophenone structure or an acylphosphine oxide structure. preferable.

  These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.1-40 mass parts with respect to 100 mass parts of polymeric compounds, Preferably it is 0.5-20 mass parts.

<Lubricant particles>
It is also possible to contain various lubricant particles in the protective layer. For example, fluorine atom-containing resin fine particles can be added. Fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluorochloroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these One or two or more types are preferably selected from the copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

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

<Formation of protective layer>
The protective layer is formed by exposing a coating solution prepared by adding a radical polymerizable compound, surface-treated metal oxide fine particles, and a known resin, a polymerization initiator, a lubricant particle, an antioxidant, and the like, if necessary, by a known method. It can be produced by applying to the surface of the layer, performing natural drying or heat drying, and then curing. The thickness of the protective layer is preferably 0.2 to 10 μm, and more preferably 0.5 to 6 μm.

In the present invention, the protective layer is cured by irradiating the coating film with active rays to generate radicals and polymerize,
Further, it is preferable to form a cured resin by forming a crosslinked bond between molecules and within the molecule by a crosslinking reaction. The active ray is preferably light such as ultraviolet light or visible light, or an electron beam, and ultraviolet light is particularly preferred from the standpoint of ease of use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, an ultraviolet LED, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 1 to 20 mJ / cm ² , preferably 5 to 15 mJ / cm ² . The output voltage of the light source is preferably 0.1 to 5 kW, and particularly preferably 0.5 to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.005 Gy to 100 kGy (0.5 to 10 Mrad).

  The irradiation time of the active ray is a time for obtaining the necessary irradiation amount of the active ray, specifically 0.1 seconds to 10 minutes is preferable, and 1 second to 5 minutes is more preferable from the viewpoint of curing efficiency or work efficiency. It is said.

  In the present invention, the protective layer can be dried before and after irradiation with active rays and during irradiation with active rays, and the timing of drying can be appropriately selected in combination with the irradiation conditions of active rays. The drying conditions for the protective layer can be appropriately selected depending on the type of solvent used in the coating solution and the thickness of the protective layer. The drying temperature is preferably from room temperature to 180 ° C, particularly preferably from 80 ° C to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes to 100 minutes.

<Structure of photoconductor>
[Photosensitive layer structure]
The photoreceptor of the present invention is obtained by forming a photosensitive layer and a protective layer on a conductive support.
The layer structure of the photosensitive layer is not particularly limited, and examples of the specific layer structure including the protective layer include the following.
(1) Layer configuration in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated on a conductive support. (2) A single layer containing a charge transport material and a charge generation material on a conductive support. Layer structure in which layer and protective layer are sequentially laminated (3) Layer structure in which intermediate layer, charge generation layer, charge transport layer and protective layer are sequentially laminated on conductive support (4) Conductive support A layer structure in which an intermediate layer, a single layer containing a charge transporting material and a charge generating material, and a protective layer are sequentially laminated on the photosensitive member of the present invention has any one of the above-mentioned layer structures (1) to (4). Among them, a layer structure in which an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer are sequentially provided on a conductive support is particularly preferable.

  FIG. 1 is a schematic view showing an example of the layer structure of the photoreceptor of the present invention.

  In FIG. 1, 1 is a conductive support, 2 is a photosensitive layer, 3 is an intermediate layer, 4 is a charge generation layer, 5 is a charge transport layer, 6 is a protective layer, and 7 is a surface-treated metal oxide fine particle.

  Next, the conductive support, intermediate layer, photosensitive layer (charge generation layer, charge transport layer) constituting the photoreceptor of the present invention, and members constituting the photosensitive layer will be described.

[Conductive support]
The support used in the present invention may be any one as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or sheet, aluminum Metal foil such as copper or copper laminated on plastic film, aluminum, indium oxide or tin oxide deposited on plastic film, metal or plastic with conductive layer applied alone or with binder resin Examples include film and paper.

[Middle layer]
In the present invention, an intermediate layer having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. The intermediate layer can be formed by dip coating or the like by dissolving a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane and gelatin in a known solvent. Among the binder resins, an alcohol-soluble polyamide resin is preferable.

  The intermediate layer can contain various conductive fine particles and metal oxide particles for the purpose of adjusting the resistance. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide. Ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide can be used. These metal oxide particles can be used alone or in combination. When two or more kinds are mixed and used, they may take the form of a solid solution or fusion. Such metal oxide particles preferably have a number average primary particle size of 0.3 μm or less, more preferably 0.1 μm or less.

As the solvent that can be used for forming the intermediate layer, a solvent in which inorganic fine particles such as conductive fine particles and metal oxide particles described above are well dispersed and a binder resin such as a polyamide resin is dissolved is preferable. Specifically, with respect to the polyamide resin, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol and the like are preferable as the binder resin. It is preferable because good solubility and coating performance are exhibited. Further, in order to improve the storage stability and the dispersibility of the inorganic fine particles, the following cosolvent can be used in combination with the solvent. Examples of co-solvents that can provide favorable effects include methanol, benzyl alcohol, toluene,
Examples include cyclohexanone and tetrahydrofuran.

  The binder resin concentration at the time of forming the coating solution can be appropriately selected according to the film thickness of the intermediate layer and the coating method. Moreover, when inorganic fine particles etc. are disperse | distributed, it is preferable that the mixing ratio of the inorganic fine particles with respect to binder resin shall be 20-400 mass parts with respect to 100 mass parts of binder resin, and is 50-200 mass parts. It is more preferable.

  Examples of the means for dispersing the inorganic fine particles include, but are not limited to, an ultrasonic disperser, a ball mill, a sand grinder, and a homomixer.

  Moreover, the drying method of an intermediate | middle layer can select suitably a well-known drying method according to the kind of solvent and the film thickness to form, and heat drying is especially preferable.

  The thickness of the intermediate layer is preferably from 0.1 to 15 μm, more preferably from 0.3 to 10 μm.

(Photosensitive layer)
As described above, the photosensitive layer constituting the photoreceptor of the present invention has a charge generation layer (CGL) and a charge transport layer (CTL) in addition to a single layer structure in which a charge generation function and a charge transport function are provided in one layer. And a layer structure in which the functions of the photosensitive layer are separated from each other. As described above, the function-separated type layer structure has an advantage that it is easy to control various electrophotographic characteristics according to the purpose, in addition to being able to control the increase in residual potential with repeated use. The negatively chargeable photoreceptor has a structure in which a charge generation layer (CGL) is provided on an intermediate layer and a charge transport layer (CTL) is provided thereon. The positively chargeable photoreceptor is a charge transport layer (CTL) provided on the intermediate layer. The charge generation layer (CGL) is provided thereon. A preferred layer structure of the photosensitive layer is a negatively charged photoreceptor having the function separation structure.

  Below, each layer of the photosensitive layer of the function-separated negatively charged photosensitive member will be described as a specific example of the photosensitive layer.

(Charge generation layer)
The charge generation layer formed in the present invention contains a charge generation material and a binder resin,
What was formed by apply | coating the coating liquid formed by disperse | distributing a charge generating substance in a binder resin solution is preferable.

  Charge generation materials include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and phthalocyanine pigments is not. These charge generation materials can be used alone or in a form dispersed in a known binder resin.

  As the binder resin for forming the charge generation layer, known resins can be used. For example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy Resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and copolymer resin containing two or more of these resins (for example, vinyl chloride-vinyl acetate copolymer resin) , Vinyl chloride-vinyl acetate-maleic anhydride copolymer resin) and poly-vinyl carbazole resin, but are not limited thereto.

  The charge generation layer is formed by dispersing the charge generation material in a solution obtained by dissolving the binder resin in a solvent using a disperser to prepare a coating solution, and applying the coating solution to a certain film thickness using a coating device. It is preferable to prepare the film by drying.

As a solvent for dissolving and coating the binder resin used in the charge generation layer, for example,
Toluene, xylene, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate,
Examples include methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine, but are not limited thereto.

  As a means for dispersing the charge generating material, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.

The mixing ratio of the charge generating material to the binder resin is preferably 1 to 600 parts by weight, more preferably 50 to 500 parts by weight based on 100 parts by weight of the binder resin. The thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 0.01 to 5 μm, and more preferably 0.05 to 3 μm. It should be noted that the coating solution for the charge generation layer can prevent the occurrence of image defects by filtering foreign matter and aggregates before coating.
The pigment can also be formed by vacuum deposition.

(Charge transport layer)
The charge transport layer formed in the present invention contains at least a charge transport material and a binder resin in the layer, and is formed by dissolving and coating the charge transport material in a binder resin solution.

As the charge transport material, a known compound can be used, and examples thereof include the following. Carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benz Imidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives,
Stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene and the like. These compounds can be used alone or in admixture of two or more.

In addition, a known resin can be used as the binder resin for the charge transport layer, for example,
There are the following. That is, polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic acid ester resin, styrene-methacrylic acid ester copolymer resin, and the like.
Of these, polycarbonate resins are preferred, and bisphenol A (BPA) is also preferred.
Polycarbonate resins such as bisphenol Z (BPZ), dimethyl BPA, and BPA-dimethyl BPA copolymer are preferred from the viewpoint of crack resistance, abrasion resistance, and charging characteristics.

The charge transport layer can be formed by a known method typified by a coating method, for example,
In the coating method, a desired charge transporting layer can be formed by preparing a coating solution by dissolving the binder resin and the charge transporting material, applying the coating solution with a certain film thickness, and drying the coating solution.

Examples of the solvent for dissolving the binder resin and the charge transport material include toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol,
Examples include ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane and the like. The solvent used when preparing the coating liquid for forming the charge transport layer is not limited to the above.

  The mixing ratio of the binder resin and the charge transport material is preferably 10 to 500 parts by weight, and more preferably 20 to 100 parts by weight with respect to 100 parts by weight of the binder resin.

  The thickness of the charge transport layer varies depending on the characteristics of the charge transport material and the binder resin, the mixing ratio thereof, and the like, but is preferably 5 to 40 μm, and more preferably 10 to 30 μm.

  In the charge transport layer, a known antioxidant can be added. For example, an antioxidant described in JP-A-2000-305291 can be used.

[Coating method of photoreceptor]
Each layer such as an intermediate layer, a charge generation layer, a charge transport layer and a protective layer constituting the photoreceptor of the present invention can be formed by a known coating method. Specific examples include a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, and a circular amount-regulating coating method.

  The circular amount regulation type coating method is described in JP-A-58-189061.

<Image forming apparatus>
An image forming apparatus according to the present invention will be described.

An image forming apparatus that realizes the effects of the present invention is as follows.
(1) An electrophotographic photosensitive member having at least the protective layer of the present invention,
(2) Charging means for charging the surface of the electrophotographic photosensitive member described above,
(3) An exposure unit that performs image exposure on the surface of the electrophotographic photosensitive member charged by the charging unit to form a latent image;
(4) developing means for visualizing the latent image formed by the exposure means to form a toner image;
(5) The image forming apparatus includes a transfer unit that transfers the toner image formed on the surface of the electrophotographic photosensitive member by the developing unit onto a transfer medium such as paper or a transfer belt.

  Note that a non-contact charging device is preferably used as the charging means for charging the electrophotographic photosensitive member. Examples of the non-contact charging device include a corona charging device, a corotron charging device, and a scorotron charging device.

  FIG. 2 is a cross-sectional configuration diagram illustrating an example of a color image forming apparatus showing one of the embodiments of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

An image forming unit 10Y that forms a yellow image includes a charging unit (charging step) 2Y, an exposure unit (exposure step) 3Y disposed around a drum-shaped photoconductor 1Y as a first image carrier.
It has a developing means (developing process) 4Y, a primary transfer roller 5Y as a primary transfer means (primary transfer process), and a cleaning means 6Y. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

The four sets of image forming units 10Y, 10M, 10C, and 10Bk include charging means 2Y, 2M, 2C, and 2Bk that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk, and image exposure means 3Y, 3M, 3C, 3Bk and rotating developing means 4Y, 4M, 4C, 4Bk, and
It comprises cleaning means 6Y, 6M, 6C and 6Bk for cleaning the photosensitive drums 1Y, 1M, 1C and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

The image forming unit 10Y includes a charging unit 2Y around a photosensitive drum 1Y that is an image forming body.
(Hereinafter simply referred to as charging means 2Y or charger 2Y), exposure means 3Y, developing means 4Y, and cleaning means 6Y (hereinafter simply referred to as cleaning means 6Y or cleaning blade 6Y) are arranged, and photosensitive drum 1Y is arranged. A yellow (Y) toner image is formed thereon. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure means 3Y, the exposure means 3Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge (image forming unit), and this image forming unit is connected to the apparatus main body. It may be configured to be detachable. In addition, at least one of a charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (image forming unit), which is detachable from the apparatus main body. A single image forming unit may be detachable using guide means such as a rail of the apparatus main body.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A transfer material P as a transfer material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and a plurality of intermediates. After passing through rollers 22A, 22B, 22C, 22D and registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to transfer a color image all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a toner image transfer support formed on a photosensitive member such as an intermediate transfer member or a transfer material is collectively referred to as a transfer medium.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. Consists of.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
<Preparation of surface-treated metal oxide>
(Preparation of surface-treated metal oxide fine particles 1)
100 parts by weight of “tin oxide” having a number average primary particle size of 20 nm as metal oxide fine particles, 28.5 parts by weight of “Exemplary Compound S-12” as a polymerizable surface treatment agent, and “Exemplary Compound A-” as an antioxidant surface treatment agent 1 ”1.5 parts by mass and 1000 parts by mass of methyl ethyl ketone were placed in a wet sand mill (alumina beads having a diameter of 0.5 mm), mixed at 30 ° C. for 6 hours, and then methyl ethyl ketone and alumina beads were separated by filtration at 60 ° C. It was dried to produce “surface-treated metal oxide fine particles 1”.

(Preparation of surface-treated metal oxide fine particles 2)
In the production of the surface-treated metal oxide fine particles 1, “surface-treated metal oxide fine particles 2” were produced in the same manner except that “alumina” having a number average primary particle size of 30 nm was used as the metal fine particles.

(Preparation of surface-treated metal oxide fine particles 3)
The “surface-treated metal oxide fine particles 3” were produced in the same manner as in the production of the surface-treated metal oxide fine particles 1 except that “titanium oxide” having a number average primary particle size of 30 nm was used as the metal fine particles.

(Preparation of surface-treated metal oxide fine particles 4)
In the preparation of the surface-treated metal oxide fine particles 1, the surface treatment agent was changed to 29.7 parts by weight of “Exemplary Compound S-12” and the antioxidant surface treatment agent was changed to 0.3 parts by weight of “Exemplary Compound A-1”. Produced “surface-treated metal oxide fine particles 4” in the same manner.

(Preparation of surface-treated metal oxide fine particles 5)
In the preparation of the surface-treated metal oxide fine particles 1, the same procedure was performed except that the surface treatment agent was changed to 27 parts by weight of “Exemplary Compound S-12” and the antioxidant surface treatment agent was changed to 3 parts by weight of “Exemplary Compound A-1”. “Surface-treated metal oxide fine particles 5” were produced.

(Preparation of surface-treated metal oxide fine particles 6)
In the preparation of the surface-treated metal oxide fine particles 1, the surface treatment agent was changed to 25.5 parts by weight of “Exemplary Compound S-12” and the antioxidant surface treatment agent was changed to 4.5 parts by weight of “Exemplary Compound A-1”. Produced “surface-treated metal oxide fine particles 6” in the same manner.

(Preparation of surface-treated metal oxide fine particles 7)
In the production of the surface-treated metal oxide fine particles 1, the same procedure was performed except that the surface treatment agent was changed to 24 parts by weight of “Exemplary Compound S-12” and the antioxidant surface treatment agent was changed to 6 parts by weight of “Exemplary Compound A-1”. “Surface-treated metal oxide fine particles 7” were produced.

(Preparation of surface-treated metal oxide fine particles 8)
In the production of the surface-treated metal oxide fine particles 1, except that the surface treatment agent was changed to 21 parts by weight of “Exemplary Compound S-12” and the antioxidant surface treatment agent was changed to 9 parts by weight of “Exemplary Compound A-1”. “Surface-treated metal oxide fine particles 8” were produced.

(Preparation of surface-treated metal oxide fine particles 9)
“Surface treated metal oxide fine particles 9” were produced in the same manner as in the preparation of the surface treated metal oxide fine particles 1 except that “Exemplified Compound A-2” was changed as the antioxidant surface treatment agent.

(Preparation of surface-treated metal oxide fine particles 10)
“Surface-treated metal oxide fine particles 10” were produced in the same manner as in the preparation of the surface-treated metal oxide fine particles 1 except that “Exemplified Compound A-3” was changed as the antioxidant surface treatment agent.

(Preparation of surface-treated metal oxide fine particles 11)
“Surface-treated metal oxide fine particles 11” were produced in the same manner as in the preparation of the surface-treated metal oxide fine particles 1, except that “Exemplified Compound S-15” was changed as the polymerizable surface treatment agent.

(Preparation of surface-treated metal oxide fine particles 12)
In the production of the surface-treated metal oxide fine particles 1, “surface-treated metal oxide fine particles” were similarly prepared except that 30 parts by weight of “Exemplary Compound S-12” was added as a surface treatment agent and an antioxidant surface treatment agent was not added. 12 "was produced.

(Preparation of surface-treated metal oxide fine particles 13)
In the preparation of the surface-treated metal oxide fine particles 1, “Surface Treatment” was similarly performed except that 1.5 parts by weight of “Exemplary Compound A-1” was added as an antioxidant surface treatment agent and no polymerizable surface treatment agent was added. Metal oxide fine particles 13 ”were prepared.

<Preparation of Photoreceptor 1>
(Preparation of conductive support)
The surface of the cylindrical aluminum support was cut to prepare a conductive support having a surface roughness Rz = 1.5 (μm).

(Formation of intermediate layer)
A dispersion having the following composition was diluted twice with the same mixed solvent, allowed to stand overnight, and then filtered (filter; using a lysh mesh 5 μm filter manufactured by Nippon Pole Co., Ltd.) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part by mass Titanium oxide SMT500SAS (manufactured by Teica) 3 parts by mass Methanol 10 parts by mass Using a sand mill as a disperser, dispersion was carried out for 10 hours in a batch system.

  The said coating liquid was apply | coated and dried by the dip coating method so that it might become a dry film thickness of 2 micrometers on the said electroconductive support body, and the "intermediate layer" was formed.

(Formation of charge generation layer)
The following compositions were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution.

Charge generation material: titanyl phthalocyanine pigment (titanyl phthalocyanine pigment having a maximum diffraction peak at a position of at least 27.3 ° by Cu-Kα characteristic X-ray diffraction spectrum measurement) 20 parts by mass Polyvinyl butyral resin (# 6000-C: electrochemical 10 parts by mass t-butyl acetate 700 parts by mass 4-methoxy-4-methyl-2-pentanone 300 parts by mass This charge generation layer coating solution is applied onto the intermediate layer by a dip coating method and dried. , Dry film thickness 0.
A “charge generation layer” of 3 μm was formed.

(Formation of charge transport layer)
The following composition was mixed and dissolved to prepare a charge transport layer coating solution.

Charge transport material (4,4′-dimethyl-4 ″-(β-phenylstyryl) triphenylamine) 225 parts by mass Binder: Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts by mass Antioxidant (Irganox 1010: Nippon Ciba Geigy) 6 parts by mass THF 1600 parts by mass Toluene 400 parts by mass Silicone oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass This charge transport layer coating solution is placed on the charge generation layer with a circular amount regulating type coating machine. It was applied and dried to form a “charge transport layer” having a dry film thickness of 20 μm.

(Formation of protective layer)
The following composition was dissolved and dispersed to prepare a protective layer coating solution.

Surface treated metal oxide fine particles 1 100 parts by mass Polymerizable compound (Exemplary Compound M-1) 100 parts by mass Polymerization initiator (Irgacure 819: manufactured by BASF Japan Ltd.) 7.5 parts by mass sec-butyl alcohol 100 parts by mass This protection A layer coating solution was applied onto the charge transport layer using a circular amount regulating type coating device to form a protective layer. After drying the formed protective layer, using a metal halide lamp, the distance from the light source to the surface of the photoreceptor is set to 100 mm under a nitrogen stream, irradiated with ultraviolet light for 1 minute at a lamp output of 4 kW, and a dry film thickness of 2.0 μm. A “protective layer” was formed to produce “photoreceptor 1”.

<Preparation of photoconductors 2 to 10>
“Photoreceptors 2 to 10” were produced in the same manner except that the surface-treated metal oxide fine particles 2 to 10 were respectively changed in the production of the photoreceptor 1.

<Preparation of Photoreceptor 11>
“Photoreceptor 11” was produced in the same manner except that the amount of the surface-treated metal oxide fine particles 1 was changed to 200 parts by mass in the production of the photoreceptor 1.

<Preparation of Photoreceptor 12>
“Photoreceptor 12” was produced in the same manner except that the surface-treated metal oxide fine particles 11 were changed in the production of the photoreceptor 1.

<Preparation of Photoreceptor 13>
“Photoreceptor 13” was produced in the same manner except that the photoconductive member 1 was changed to the exemplary compound M-2 as a polymerizable compound.

<Preparation of Photoreceptor 14>
“Photoreceptor 14” was produced in the same manner as in the production of Photoreceptor 1 except that Example Compound M-18 was changed as the polymerizable compound.

<Preparation of photoconductors 15 to 16>
“Photoreceptors 15 to 16” were produced in the same manner except that the surface-treated metal oxide fine particles 12 to 13 were respectively changed in the production of the photoreceptor 1.

<Preparation of photoconductor 17>
“Photoreceptor 17” was produced in the same manner except that the surface-treated metal oxide fine particles 12 were changed and 5 parts by mass of the antioxidant B-1 shown below was added.

<Preparation of Photoconductor 18>
“Photoreceptor 18” was produced in the same manner as in the production of photoconductor 1, except that the surface-treated metal oxide fine particles 12 were changed and 5 parts by mass of antioxidant B-2 shown below was added.

<Evaluation method and criteria>
The following evaluations were performed on photoreceptors 1 to 18.
(Image blur)
The electrophotographic photosensitive member of the present invention is mounted on “bizhub PRO C6500” (tandem color composite machine of laser exposure / reversal development / intermediate transfer body at a wavelength of 780 nm) manufactured by Konica Minolta Business Technologies, Inc. (30 ° C., 85% RH). ), Print 25,000 sheets of A4 plate image with 5% print area ratio for each color of yellow (Y), magenta (M), cyan (C), and black (K) on neutral paper of A4 plate. The main power of the actual machine was stopped 60 seconds later. Immediately after the power was turned on 12 hours after the stop, a halftone image (relative reflection density 0.4 by Macbeth densitometer) and a 6 dot lattice image of the entire A3 plate were printed on the entire surface of the A3 neutral paper. The state of the printed image was observed and the following evaluation was performed.
◎: No blurring in halftone and grid images (good)
○: A thin strip-like density decrease in the longitudinal direction of the photoreceptor is observed only in the halftone image (no problem in practical use)
Δ: A strip-like density decrease in the long axis direction of the photoconductor is observed only in the halftone image (practical use possible)
×: Lattice image loss or line width narrowing due to image blurring (practical problem)
After the above evaluation, an A4 plate image with a color printing ratio of 5% for each of yellow (Y), magenta (M), cyan (C), and black (K) at 30 ° C. and 85% RH is applied to neutral A4 paper. Image blurring was similarly evaluated again after printing 1 million sheets. The evaluation results are shown in Table 1 below.

(Abrasion resistance of photoreceptor surface)
In the evaluation of the image blur, after printing 1 million sheets, the initial film thickness and the film thickness difference after 1 million sheets were evaluated. The protective layer has a uniform film thickness (measured at 10 random locations on the photosensitive body because the film thickness tends to be uneven at both ends, excluding at least 3 cm at both ends). Thickness. The film thickness measuring device is an eddy current type film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO), and the difference between the initial film thickness and the protective layer film thickness after printing 1 million sheets is defined as the film thickness depletion amount.
Specifically, the following α value was evaluated.
α value = {(thickness loss [μm]) / (total number of revolutions of drum [rot.])} ×
100,000
That is, the smaller the α value, the higher the wear resistance.
The evaluation results are shown in Table 1 below.

  As is apparent from the results in Table 1, it is recognized that the photoconductors 1 to 14 of the present invention are better in wear resistance and image blur than the photoconductors 15 to 18 for comparison.

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Photosensitive layer 3 Intermediate layer 4 Charge generation layer 5 Charge transport layer 6 Protective layer 7 Surface-treated metal fine particles 1Y, 1M, 1C, 1Bk Photosensitive drums 2Y, 2M, 2C, 2Bk Charging means 3Y, 3M, 3C, 3Bk Image exposing means 4Y, 4M, 4C, 4Bk Developing means 6Y, 6M, 6C, 6Bk Cleaning means 10Y, 10M, 10C, 10Bk Image forming unit

Claims (4)

In an electrophotographic photosensitive member obtained by sequentially laminating a photosensitive layer and a protective layer on a conductive support,
The protective layer contains a polymerization product obtained by polymerizing a radical polymerizable compound and surface-treated metal oxide fine particles obtained by surface-treating metal oxide fine particles with a surface treatment agent;
An electrophotographic photoreceptor, wherein the surface treatment agent is at least two kinds of surface treatment agents, a surface treatment agent having a reactive group capable of radical polymerization and a surface treatment agent containing an antioxidant structure.   2. The electrophotographic photoreceptor according to claim 1, wherein the metal oxide fine particles are any of alumina fine particles, tin oxide fine particles, and titanium oxide fine particles.   3. The electrophotographic photosensitive member according to claim 1, wherein the surface treatment agent having a radical polymerizable reactive group is a compound containing either an acryloyl group or a methacryloyl group.   The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the radical polymerizable compound is a polymerizable monomer or polymerizable oligomer containing either an acryloyl group or a methacryloyl group.

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