JP2006018153A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having proper cleanability, lubricity and wear resistance. <P>SOLUTION: In the electrophotographic photoreceptor obtained, by disposing a photosensitive layer on a conductive substrate, where at least the outermost layer thereof contains a solvent-soluble polyimide resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photosensitive member using a specific polyimide resin at least as an outermost layer, and more specifically, various electrophotographys that maintain excellent mechanical strength and electrophotographic characteristics that can withstand repeated use over a long period of time. The present invention relates to an electrophotographic photosensitive member that can be suitably used in the field.

As an electrophotographic photosensitive member provided with a photosensitive layer on a conductive substrate, recently, at least two layers of a charge generation layer (CGL) that generates charges by exposure and a charge transport layer (CTL) that transports charges are formed as a photosensitive layer. The laminated organic electrophotographic photoreceptor (OPC) or the photosensitive layer is composed of a single layer in which a charge generation material and a charge transport material are dispersed in a binder resin, or a single layer in which only the charge generation material is dispersed in a binder resin. A single layer type organic electrophotographic photosensitive member comprising one layer has been proposed and used. Further, as a laminated type and single layer type electrophotographic photosensitive member, those provided with a protective layer (OCL) for protecting the surface layer are both used for the problem described later.
The organic electrophotographic photosensitive member is required to have predetermined sensitivity, electrical characteristics, and optical characteristics according to the applied electrophotographic process. In this electrophotographic photosensitive member, operations such as corona charging or contact charging using a roll or brush, toner development, transfer to paper, and cleaning treatment are repeatedly performed on the surface of the photosensitive layer. Electrical and mechanical external forces are applied to the. Therefore, in order to maintain the image quality of electrophotography over a long period of time, the photosensitive layer provided on the surface of the electrophotographic photoreceptor is required to have durability against these external forces. Specifically, durability against surface wear and scratches due to friction, corona charging and contact charging, active gas such as ozone during transfer, and surface deterioration due to discharge is required.
In order to meet such demands, polycarbonate resins having good compatibility with charge transport materials used in the photosensitive layer and good optical properties have been used as binder resins for organic electrophotographic photoreceptors. That is, as the polycarbonate resin, those using 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 1,1-bis (4-hydroxyphenyl) cyclohexane [bisphenol Z] or the like as a raw material have been used. . However, even with this polycarbonate resin using bisphenol A or bisphenol Z as a raw material, it is insufficient to satisfy the above requirements, and many polycarbonate resins and other resins having structures other than bisphenol A and bisphenol Z are used. A method has been proposed and put into practical use.

  In recent years, with the colorization of printers and copiers using an electrophotographic process, there is a demand for low surface energy on the surface of the photosensitive member that achieves high cleaning properties, in particular, its durability. To solve this problem, additives such as hydrophobicity imparting agents and low surface energy material fine particles are dispersed. However, the additive is easy to bleed out from the electrophotographic photosensitive member and has low surface energy. The fine particles of the material tend to aggregate and have problems such as light scattering in the photoreceptor and poor dispersibility during production of the photoreceptor. Moreover, in order to improve the dispersibility of various fine particles, attempts have been made to change the binder resin or add various additives (Patent Documents 1 and 2). This leads to deterioration of electrophotographic characteristics such as a reduction in sensitivity, which causes another problem.

JP-A-63-65451 JP-A-5-45920

  The present invention solves the above-mentioned problems found in conventional electrophotographic photoreceptors, and provides electrophotographic characteristics such as mechanical strength and cleaning properties excellent in wear resistance, scratch resistance, printing durability, etc. over a long period of time. An object of the present invention is to provide an electrophotographic photoreceptor excellent in practical use.

In order to solve the above-mentioned problems, the present inventors have made extensive studies, and as a result, by incorporating a polyimide resin soluble in a solvent into the surface layer of the photoconductor, particularly in mechanical properties such as printing durability. It has been found that an electrophotographic photoreceptor can be obtained which is excellent, particularly has electrophotographic characteristics such as cleaning characteristics, and has no problems such as light scattering and poor dispersion due to aggregation. The present invention has been completed based on such findings.
That is, the present invention provides the following electrophotographic photosensitive member.
1. An electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate, wherein at least the outermost layer contains a polyimide resin soluble in a solvent.
2. A polyimide resin soluble in a solvent is represented by the following general formula (A)

（式中、Ｘ及びＹは、それぞれ独立にヘテロ原子を有していてもよい炭化水素基であり、Ｘ及びＹのうちの少なくとも一つは、脂肪族環状構造を含む基である。）
表される繰り返し単位を有する上記１に記載の電子写真感光体。

(Wherein X and Y are each independently a hydrocarbon group optionally having a hetero atom, and at least one of X and Y is a group containing an aliphatic cyclic structure.)
2. The electrophotographic photosensitive member according to 1 above having a repeating unit represented.

  According to the present invention, by including a polyimide resin soluble in a solvent in the binder resin of the outermost layer (such as a photosensitive layer) of an electrophotographic photosensitive member, the mechanical strength such as abrasion resistance of the photosensitive member is improved and the durability is improved. It is possible to provide an electrophotographic photosensitive member having a low surface energy (low friction coefficient) that can realize high cleaning properties even after the test.

The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member in which a photosensitive layer is provided on a conductive substrate. As long as such a photosensitive layer is formed on a conductive substrate, the structure is particularly limited. In addition, various types of electrophotographic photosensitive members such as a single layer type and a multilayer type may be used. Of these, a laminated electrophotographic photosensitive member having a photosensitive layer having at least one charge generation layer and at least one charge transport layer forming a surface layer is preferable.
In the present invention, the outermost layer of the electrophotographic photoreceptor is the outermost layer in the case of a structure having a protective layer, and the charge transport layer in the case of a structure having no protective layer. When it has a protective layer, the soluble polyimide resin according to the present invention may be contained only in the protective layer, and it may be contained not only in the protective layer but also in the charge transport layer of the inner layer.

  The polyimide resin soluble in the solvent used in the present invention (hereinafter sometimes simply referred to as “soluble polyimide resin”) may be any polyimide resin soluble in an organic solvent, and its production method is also limited. It is not a thing. Here, the “resin that is soluble in a solvent” means that when mixed with a solvent (substantially a solvent that dissolves the outermost binder resin), transparency is impaired in the visible light region (total light transmittance is 80). %) Or less), that is, a resin having an average particle size of 100 nm or less even when present as particles. As a soluble polyimide resin, the following general formula (A)

（式中、Ｘ及びＹは、それぞれ独立にヘテロ原子を有していてもよい炭化水素基であり、Ｘ及びＹのうちの少なくとも一つは、脂肪族環状構造を含む基である。）

(Wherein X and Y are each independently a hydrocarbon group optionally having a hetero atom, and at least one of X and Y is a group containing an aliphatic cyclic structure.)

And a compound having a repeating unit. In the general formula (A), examples of the hetero atom of the hydrocarbon group which may have a hetero atom represented by X or Y include an oxygen atom and a sulfur atom. This repeating unit is composed of a structural unit containing X and a structural unit (—Y—) containing Y, and examples of the structural unit containing X include structural units represented by the following formulae.

  Moreover, as a structural unit containing said Y, the structural unit shown, for example by a following formula is mentioned.

  The structural unit containing X and the structural unit containing Y are obtained from the corresponding raw materials, the structural unit containing X is obtained from the corresponding tetracarboxylic acid or tetracarboxylic acid derivative, and the structural unit containing Y is a diamine. Obtained from derivatives. Examples of the tetracarboxylic acid derivative include the following compounds.

  Moreover, as said diamine derivative, the following compound is mentioned, for example.

As the conductive substrate used in the electrophotographic photosensitive member of the present invention, various substrates such as known ones can be used. Specifically, aluminum, nickel, chromium, palladium, titanium, molybdenum, indium, gold , Platinum, silver, copper, zinc, brass, stainless steel, lead oxide, tin oxide, indium oxide, ITO (indium tin oxide: tin-doped indium oxide) or graphite plates, drums, sheets, and vapor deposition, sputtering, coating It is possible to use glass, cloth, paper or plastic film, sheet and seamless sieve belt, etc. that have been subjected to conductive treatment by coating or the like, and a metal drum that has been subjected to metal oxidation treatment by electrode oxidation or the like.
The charge generation layer of the multilayer electrophotographic photosensitive member contains at least a charge generation substance, and this charge generation layer generates a charge on the base substrate by vacuum deposition, chemical vapor deposition, sputtering, or the like. It can be obtained by forming a layer of the substance or forming a layer formed by binding the charge generating substance using a binder resin on the underlying layer.
Various methods such as a known method can be used as a method for forming a charge generation layer using a binder resin. Usually, for example, a coating solution in which a charge generation material is dispersed or dissolved in a suitable solvent together with a binder resin is used. For example, a method of applying to a predetermined base layer and drying is preferably used. The thickness of the charge generation layer thus obtained is usually 0.01 to 2.0 μm, preferably 0.1 to 0.8 μm. If the thickness of the charge generation layer is 0.01 μm or more, it is easy to form a layer having a uniform thickness, and if it is 2.0 μm or less, the electrophotographic characteristics are improved.

Various known materials can be used as the charge generation material in the charge generation layer. Specific compounds include amorphous selenium, selenium alone such as trigonal selenium, selenium alloys such as selenium-tellurium, selenium compounds such as As ₂ Se ₃ or selenium-containing compositions, zinc oxide, CdS-Se, etc. Inorganic materials consisting of Group 12 and Group 16 elements of the periodic table, oxide-based semiconductors such as titanium oxide, silicon-based materials such as amorphous silicon, metal-free phthalocyanines such as τ-type metal-free phthalocyanine and χ-type metal-free phthalocyanine Pigment, α-type copper phthalocyanine, β-type copper phthalocyanine, γ-type copper phthalocyanine, ε-type copper phthalocyanine, X-type copper phthalocyanine, A-type titanyl phthalocyanine, B-type titanyl phthalocyanine, C-type titanyl phthalocyanine, D-type titanyl phthalocyanine, E-type titanyl Phthalocyanine, F-type titanyl phthalocyanine, G-type titanyl Russianine, H-type titanyl phthalocyanine, K-type titanyl phthalocyanine, L-type titanyl phthalocyanine, M-type titanyl phthalocyanine, N-type titanyl phthalocyanine, Y-type titanyl phthalocyanine, oxo titanyl phthalocyanine, Bragg angle 2θ in X-ray diffraction diagram is 27.3 ± 0 .Metallic phthalocyanine pigments such as titanyl phthalocyanine exhibiting a strong diffraction peak twice, cyanine dyes, anthracene pigments, bisazo pigments, pyrene pigments, polycyclic quinone pigments, quinacridone pigments, indigo pigments, perylene pigments, pyrylium dyes, squalium pigments, Anthanthrone pigment, benzimidazole pigment, azo pigment, thioindigo pigment, quinoline pigment, lake pigment, oxazine pigment, dioxazine pigment, triphenylmethane pigment, azurenium dye, Rear triarylmethane dyes, xanthine dyes, thiazine dyes, thiapyrylium dyes, polyvinylcarbazole, and the like bisbenzimidazole pigments. These compounds can be used as a charge generation material singly or in combination of two or more.
Among these charge generating materials, preferred are those specifically described in JP-A-11-172003.

  There is no restriction | limiting in particular as binder resin in the said charge generation layer, A well-known various thing can be used. Specifically, polystyrene resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetal resin, alkyd resin, acrylic resin, polyacrylonitrile resin, polycarbonate resin, polyamide resin, butyral resin, Polyester resin, vinylidene chloride-vinyl chloride copolymer, methacrylic resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin , Phenol-formaldehyde resin, styrene-alkyd resin, melamine resin, polyether resin, benzoguanamine resin, epoxy acrylate resin, urethane acrylate resin, poly-N-vinylcarbazole Fat, polyvinyl butyral resin, polyvinyl formal resin, polysulfone resin, casein, gelatin, polyvinyl alcohol resin, ethyl cellulose, nitrocellulose, carboxymethyl cellulose, vinylidene chloride polymer latex, acrylonitrile-butadiene copolymer, vinyl toluene-styrene copolymer, Examples include soybean oil-modified alkyd resin, nitrated polystyrene resin, polymethylstyrene resin, poisoprene resin, polythiocarbonate resin, polyarylate resin, polyhaloarylate resin, polyallyl ether resin, polyvinyl acrylate resin, and polyester acrylate resin. These can be used individually by 1 type or in combination of 2 or more types.

The charge transport layer can be formed by binding a charge transport material using a binder resin on a base layer (for example, a charge generation layer). There is no restriction | limiting in particular as binder resin in the said charge transport layer, Various things can be used. As the binder resin, the same binder resin as that used in the charge generation layer can be used. Of the above binder resins, polycarbonate resins are preferred from the viewpoints of mechanical properties, optical properties, electrical properties, ease of formation of the charge transport layer, and the like. One or more of the soluble polyimide resins according to the present invention may be used as a binder resin, or the soluble polyimide resin according to the present invention and the binder resin may be mixed and used. When this mixture is used, good coatability and mechanical properties can be obtained.
As a method for forming the charge transport layer, various methods such as a known method can be used, but usually, the soluble polyimide resin according to the present invention, the charge transport material and polycarbonate, or the object of the present invention is not impaired. Within a range, a method of applying a coating solution dispersed or dissolved in an appropriate solvent together with another binder resin onto a substrate serving as a predetermined base and drying is used. In the resin composition containing the polyimide resin and the binder resin according to the present invention, the content of the soluble polyimide resin according to the present invention is preferably 0.1 to 10% by mass, and 1 to 7% by mass based on the total amount of the composition. More preferred. When the content is 0.1% by mass or more, the effect of containing the soluble polyimide resin is obtained. When the content is 10% by mass or less, the light transmittance and mechanical strength of the electrophotographic photosensitive member are not lowered. Good electrophotographic characteristics can be obtained. The blending ratio of the charge transport material used for forming the charge transport layer and the resin composition in the present invention is preferably 20:80 to 80:20, more preferably 30:70 to 70:30 in terms of mass ratio.

The thickness of the charge transport layer thus formed is usually about 5 to 100 μm, preferably 10 to 30 μm. When this thickness is 5 μm or more, the initial potential is increased, and when it is 100 μm or less, the electrophotographic characteristics are improved.
Examples of the charge transport material that can be used in the present invention include various known compounds. Such compounds include carbazole compounds, indole compounds, imidazole compounds, oxazole compounds, pyrazole compounds, oxadiazole compounds, pyrazoline compounds, thiadiazole compounds, aniline compounds, hydrazone compounds, aromatic amine compounds, aliphatic amine compounds, stilbenes. Compound, fluorenone compound, butadiene compound, quinone compound, quinodimethane compound, thiazole compound, triazole compound, imidazolone compound, imidazolidine compound, bisimidazolidine compound, oxazolone compound, benzothiazole compound, benzimidazole compound, quinazoline compound, benzofuran compound, acridine Compound, phenazine compound, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthra Emissions, polyvinyl acridine, poly-9-vinylphenyl anthracene, pyrene - formaldehyde resin, ethylcarbazole resin, or the like polymers having these structures in the main chain or side chain is preferably used. These compounds may be used alone or in combination of two or more.
Among these charge transport materials, compounds specifically exemplified in JP-A-11-172003 are particularly preferably used.

In the electrophotographic photosensitive member of the present invention, an undercoat layer that is usually used can be provided between the conductive substrate and the photosensitive layer. As the undercoat layer, fine particles such as titanium oxide, aluminum oxide, zirconia, titanic acid, zirconic acid, lanthanum acid, titanium black, silica, lead titanate, barium titanate, tin oxide, indium oxide, silicon oxide, polyamide Components such as resin, phenol resin, casein, melamine resin, benzoguanamine resin, polyurethane resin, epoxy resin, cellulose, nitrocellulose, polyvinyl alcohol, and polyvinyl butyral resin can be used. Moreover, you may use the said binder resin as resin used for this undercoat layer. These fine particles and resins can be used alone or in various mixtures. In the case of using these as a mixture, it is preferable to use inorganic fine particles and a resin together because a film having good smoothness is formed.
The thickness of this undercoat layer is usually about 0.01 to 10 μm, preferably 0.01 to 1 μm. When the thickness is 0.01 μm or more, it is easy to form the undercoat layer uniformly, and when it is 10 μm or less, the electrophotographic characteristics are improved.

Further, a known blocking layer that is usually used can be provided between the conductive substrate and the photosensitive layer. As this blocking layer, the same one as the above binder resin can be used. The thickness of this blocking layer is usually about 0.01 to 20 μm, preferably 0.01 to 10 μm. When the thickness is 0.01 μm or more, it is easy to form a blocking layer uniformly, and when the thickness is 20 μm or less, there is no possibility of deteriorating electrophotographic characteristics.
Furthermore, in the electrophotographic photoreceptor of the present invention, when a protective layer is laminated on the photosensitive layer, one kind of the soluble polyimide resin according to the present invention is used alone or two or more kinds are mixed in this protective layer. Can be used. The thickness of this protective layer is usually about 0.01 to 20 μm, preferably 0.01 to 10 μm. In addition to the soluble polyimide resin according to the present invention, the protective layer includes the charge generation material, charge transport material, additive, metal and oxide thereof, nitride, salt, alloy, carbon black, and organic conductive compound. A conductive material such as can be contained.

Further, in order to improve the performance of the electrophotographic photoreceptor, the charge generation layer and the charge transport layer include a binder, a plasticizer, a curing catalyst, a fluidity imparting agent, a pinhole control agent, a spectral sensitivity sensitizer ( Sensitizing dye) may be added. In addition, various chemical substances, antioxidants, surfactants, anti-curling agents, leveling agents, and other additives are added for the purpose of preventing increase in residual potential, reduction in charging potential, and reduction in sensitivity due to repeated use. Can be added.
As the binder, silicone resin, polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyketone resin, polycarbonate resin, polystyrene resin, polymethacrylate resin, polyacrylamide resin, polybutadiene resin, polyisoprene resin, melamine resin, benzoguanamine resin , Polychloroprene resin, polyacrylonitrile resin, ethyl cellulose resin, nitrocellulose resin, urea resin, phenol resin, phenoxy resin, polyvinyl butyral resin, formal resin, vinyl acetate resin, vinyl acetate / vinyl chloride copolymer resin, polyester carbonate resin, etc. Can be mentioned. Also, heat and / or photocurable resins can be used. In any case, there is no particular limitation as long as it is an electrical insulating resin that can form a film in a normal state.
This binder is preferably added at a blending ratio of 1 to 200% by mass with respect to the resin composition containing the soluble polyimide resin and the binder resin according to the present invention, which forms the charge transport layer, and is 5 to 100%. The mass% is more preferable. When the blending ratio of the binder is 1% by mass or more, the film of the photosensitive layer becomes uniform, and when it is 200% by mass or less, the sensitivity does not decrease and the residual potential does not increase.

Specific examples of the plasticizer include biphenyl, biphenyl chloride, o-terphenyl, halogenated paraffin, dimethyl naphthalene, dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, diethylene glycol phthalate, triphenyl phosphate, diisobutyl adipate, dimethyl sebacate, dibutyl. Examples include sebacate, butyl laurate, methyl phthalyl ethyl glycolate, dimethyl glycol phthalate, methyl naphthalene, benzophenone, polypropylene, polystyrene, and fluorohydrocarbon.
Specific examples of the curing catalyst include methanesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenedisulfonic acid, and the like. Examples of the fluidity-imparting agent include modaflow, acronal 4F, and the like. , Benzoin, and dimethyl phthalate.
These plasticizer, curing catalyst, fluidity imparting agent, and pinhole control agent are 5% by mass or less based on the resin composition containing the soluble polyimide resin and the binder resin according to the present invention, which forms the charge transport layer. It is preferable to use in.
Further, as a spectral sensitizer, when using a sensitizing dye, for example, triphenylmethane dyes such as methyl violet, crystal violet, knight blue, and victoria blue, erythrosin, rhodamine B, rhodamine 3R, acridine orange, Acridine dyes such as frappeosin, thiazine dyes such as methylene blue and methylene green, oxazine dyes such as capri blue and meldra blue, cyanine dyes, merocyanine dyes, styryl dyes, pyrylium salt dyes and thiopyrylium salt dyes are suitable.

  An electron-accepting substance can be added to the photosensitive layer for the purpose of improving sensitivity, reducing residual potential, and reducing fatigue during repeated use. Specific examples thereof include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, pyroanhydride Merit acid, merit anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, 1,3,5-trinitrobenzene, p-nitrobenzonitrile, picryl chloride, quinone chloride, Chloranil, bromanyl, benzoquinone, 2,3-dichlorobenzoquinone, dichlorodicyanoparabenzoquinone, naphthoquinone, diphenoquinone, tropoquinone, anthraquinone, 1-chloroanthraquinone, dinitroanthraquinone, 4-nitrobenzophenone, 4,4'-dinini Lobenzophenone, 4-nitrobenzalmalondinitrile, ethyl α-cyano-β- (p-cyanophenyl) acrylate, 9-anthracenylmethylmalondinitrile, 1-cyano- (p-nitrophenyl) -2 -(P-chlorophenyl) ethylene, 2,7-dinitrofluorenone, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 9-fluorenylidene- (dicyanomethylenemalononitrile), polynitro- 9-fluorenylidene- (dicyanomethylenemalonodinitrile), picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, 3,5-dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitro Compounds with high electron affinity such as salicylic acid, phthalic acid, merit acid, etc. Masui. These compounds may be added to either the charge generation layer or the charge transport layer, and the blending ratio thereof is usually about 0.01 to 200% by mass, preferably about 0.1% by mass with respect to the charge generation material or the charge transport material. 1-50 mass%.

In addition, to improve surface properties, tetrafluoroethylene resin, trifluorinated ethylene chloride resin, tetrafluoroethylene hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin and those Copolymers and fluorine-based graft polymers may be used. The blending ratio of these surface modifiers is usually about 0.1 to 60% by mass, preferably 2 to 40% by mass with respect to the resin composition containing the solubility according to the present invention and the polyimide resin and binder resin. It is. When the blending ratio is 0.1% by mass or more, surface modification such as surface durability and surface energy reduction is sufficient, and when it is 60% by mass or less, electrophotographic characteristics are improved.
As the antioxidant, a hindered phenol antioxidant, an aromatic amine antioxidant, a hindered amine antioxidant, a sulfide antioxidant, an organic phosphorus antioxidant, and the like are preferable. The mixing ratio of these antioxidants is usually 0.01 to 10 mass based on the charge transport material or the resin composition containing the solubility according to the present invention and the polyimide resin and the binder resin for forming the charge transport layer. %, Preferably 0.1 to 5% by mass.
Specific examples of hindered phenol-based antioxidants, aromatic amine-based antioxidants, hindered amine-based antioxidants, sulfide-based antioxidants, and organophosphorus-based antioxidants are disclosed in JP-A-11-172003. There is what is described in.

These antioxidants may be used individually by 1 type, and 2 or more types may be mixed and used for them. These may be added to the surface protective layer, the undercoat layer and the blocking layer in addition to the photosensitive layer.
Examples of the solvent used to form the charge generation layer and the charge transport layer include aromatic solvents such as benzene, toluene, xylene, chlorobenzene, and anisole, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, methanol, ethanol, and isopropanol. Alcohols such as ethyl acetate, esters such as ethyl cellosolve, halogenated hydrocarbons such as carbon tetrachloride, chloroform, dichloromethane and tetrachloroethane, ethers such as tetrahydrofuran and dioxane, dimethylformamide, dimethyl sulfoxide, etc. Can do. One of these solvents may be used alone, or two or more thereof may be used as a mixed solvent.

As a method for preparing the coating solution, the above-mentioned preparation raw material can be dispersed or dissolved using a ball mill, ultrasonic waves, paint shaker, red devil, sand mill, mixer, attritor or the like. About the method of coating the obtained coating liquid, dip coating method, electrostatic coating method, powder coating method, spray coating method, roll coating method, applicator coating method, spray coater coating method, bar coater coating method, Use roll coater coating method, dip coater coating method, doctor blade coating method, wire bar coating method, knife coater coating method, attritor coating method, spinner coating method, bead coating method, blade coating method, curtain coating method, etc. Can do.
The photosensitive layer of the single-layer electrophotographic photoreceptor uses a resin composition containing the soluble polyimide resin according to the present invention and a binder resin, a charge generation material, a charge transport material, an additive, other binder resins, and the like. Formed. In this case, the preparation of the coating liquid, the coating method thereof, the prescription of additives, and the like are the same as in the case of forming the photosensitive layer of the above-described multilayer electrophotographic photosensitive member. Further, in this single layer type electrophotographic photosensitive member, an undercoat layer, a blocking layer, and a surface protective layer may be provided in the same manner as described above.

The thickness of the photosensitive layer in the single layer type electrophotographic photosensitive member is usually about 5 to 100 μm, preferably 8 to 50 μm. When this thickness is 5 μm or more, the initial potential is increased, and when it is 100 μm or less, the electrophotographic characteristics are improved.
The ratio of the charge generating material used in the production of this single-layer type electrophotographic photosensitive member: the resin composition containing the soluble polyimide resin and the binder resin according to the present invention is a mass ratio, usually about 1:99 to 30:70. Preferably, it is 3: 97-15: 85. In addition, when a charge transport material is added, the ratio of the charge transport material: the resin composition containing the soluble polyimide resin and the binder resin according to the present invention is generally about 5:95 to 80:20, preferably about mass ratio. Is 10: 90-60: 40.

The electrophotographic photoreceptor of the present invention thus obtained is a photoreceptor having excellent wear resistance and maintaining excellent printing durability and electrophotographic characteristics over a long period of time. , Multicolor, full color; analog, digital), printer (laser, LED, liquid crystal shutter), facsimile, plate making machine, and other various electrophotographic fields.
When the electrophotographic photosensitive member of the present invention is used, corona discharge (corotron, scorotron), contact charging (charging roll, charging brush), injection charging, or the like is used for charging. For the exposure, any of a halogen lamp, a fluorescent lamp, a laser (semiconductor, He—Ne), an LED, and a photoreceptor internal exposure method may be adopted. For the development, a dry development method such as cascade development, two-component magnetic brush development, one-component insulating toner development, one-component conductive toner development, or a wet development method using liquid toner is used. For transfer, electrostatic transfer methods such as corona transfer, roller transfer, and belt transfer, pressure transfer methods, and adhesive transfer methods are used. For fixing, heat roller fixing, radiant flash fixing, open fixing, pressure fixing, or the like is used. Furthermore, brush cleaner, magnetic brush cleaner, magnetic roller cleaner, blade cleaner, etc. are used for cleaning and static elimination.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
[Example 1]
The following general formula

（式中、ｎは繰り返し単位数である。）

(In the formula, n is the number of repeating units.)

And a polycarbonate resin (PC-Z) having a reduced viscosity [η _sp / c] of 1.1 dl / g at 20 ° C. of a solution having a concentration of 0.5 g / dl using methylene chloride as a solvent and the following general formula

（式中、ｍは繰り返し単位数である。）

(In the formula, m is the number of repeating units.)

(Trade name: PI 100, solution viscosity of 30% by weight solution dissolved in N-methyl-2-pyrrolidone (NMP) is 1700 mPa · S, manufactured by Maruzen Petrochemical Co., Ltd.) The electrophotographic photosensitive member was prepared by the method described below and its performance was evaluated.
Using a polyethylene terephthalate resin film deposited with aluminum metal as the conductive substrate, a charge generating layer and a charge transport layer were sequentially laminated on the surface to produce an electrophotographic photoreceptor having a laminated photosensitive layer.
0.5 parts by mass of oxotitanium phthalocyanine was used as the charge generating substance, and 0.5 parts by mass of butyral resin was used as the binder resin. These are added to 19 parts by mass of methylene chloride as a solvent, dispersed by a ball mill, and this dispersion is applied to the surface of the conductive substrate film by a bar coater and dried to obtain a charge having a thickness of about 0.5 μm. A generation layer was formed.
Next, as a charge transport material, the following compound (CTM-1)

0.5 g, the copolymer polycarbonate resin 0.5 g, the soluble polyimide resin 0.025 g and the polycarbonate resin 0.475 g were dissolved in 10 ml of tetrahydrofuran to prepare a coating solution. This coating solution was applied onto the charge generation layer with an applicator and dried to form a charge transport layer having a thickness of about 20 μm.
Next, the electrophotographic characteristics were measured using an electrostatic charging test apparatus EPA-8100 (manufactured by Kawaguchi Electric Manufacturing Co., Ltd.). A corona discharge of −6 kV was performed, and the initial surface potential (V ₀ ), the residual potential (V _R ) after 5 seconds of light irradiation (10 Lux), and the half-exposure dose (E _1/2 ) were measured. Furthermore, the wear resistance of this charge transport layer was evaluated using a Suga abrasion tester NUS-ISO-3 type (manufactured by Suga Test Instruments Co., Ltd.). The test condition was that the abrasion paper (containing alumina particles having a particle diameter of 3 μm) applied with a load of 4.9 N was brought into contact with the surface of the photosensitive layer and 2,000 reciprocating motions were performed to measure the mass loss. Furthermore, the dynamic friction coefficient of the wear scar of the sample evaluated for wear resistance was measured using a surface property tester (manufactured by Haydon Co., Ltd.). The test was performed by applying a weight of 0.49 N to the steel ball and sweeping it at a constant speed (200 mm / min).
[Example 2]
Following formula

And a polycarbonate resin having a reduced viscosity [η _sp / c] of 1.2 dl / g at 20 ° C. in a solution having a concentration of 0.5 g / dl using methylene chloride as a solvent, and the following general formula:

In the same manner as in Example 1, using a soluble polyimide resin (manufactured by Maruzen Petrochemical Co., Ltd., trade name: PI101, solution viscosity of a 30% by weight solution dissolved in NMP is 2000 mPa · S). A photoconductor was prepared and its performance was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Examples 1 and 2]
An electrophotographic photosensitive member was produced in the same manner as in Examples 1 and 2 except that the same polycarbonate resin as in Examples 1 and 2 was used and a soluble polyimide resin was not used, and the same evaluation was performed. The results are shown in Table 1.

[Comparative Example 3]
In Example 1, an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that polyimide resin (manufactured by Toray DuPont, trade name: Kapton EN) was used instead of soluble polyimide resin. There was no solvent capable of dissolving this polyimide resin, and an electrophotographic photosensitive member could not be produced.

The electrophotographic photoreceptor of the present invention is a photoreceptor having good cleaning properties, slipperiness and abrasion resistance, and is a copying machine (monochrome, multicolor, full color: analog, digital), printer (laser, LED, liquid crystal shutter). It is suitably used in various electrophotographic fields such as facsimiles and plate-making machines.

Claims (2)

  An electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate, wherein at least the outermost layer contains a polyimide resin soluble in a solvent. A polyimide resin soluble in a solvent is represented by the following general formula (A)

(Wherein X and Y are each independently a hydrocarbon group optionally having a hetero atom, and at least one of X and Y is a group containing an aliphatic cyclic structure.)
The electrophotographic photosensitive member according to claim 1, having a repeating unit represented by: