JP4566875B2 - Electrophotographic photosensitive member, method for manufacturing electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus - Google Patents

Description

The present invention relates to an electrophotographic photoreceptor, a manufacturing method of an electrophotographic photoreceptor to a process cartridge及 Beauty electrophotographic apparatus having the electrophotographic photosensitive member.

  Examples of the photoconductive substance (charge generating substance or charge transporting substance) used for the electrophotographic photoreceptor mounted in the electrophotographic apparatus include inorganic photoconductive substances such as selenium, cadmium sulfide, and zinc oxide. On the other hand, in recent years, organic photoconductive substances have been actively developed from the viewpoint of pollution-free, high productivity, and ease of material design.

  An electrophotographic photosensitive member (organic electrophotographic photosensitive member) using an organic photoconductive substance is obtained by applying a coating liquid obtained by dissolving and dispersing an organic photoconductive substance or a binder resin in a solvent on a support, It usually has a photosensitive layer formed by drying it. The layer structure of the photosensitive layer is generally a laminate type (normal layer type) in which a charge generation layer and a charge transport layer are laminated in this order from the support side.

  An electrophotographic photosensitive member using an organic photoconductive material has the above-mentioned advantages, but does not satisfy all of the characteristics required for an electrophotographic photosensitive member, and in particular, the image quality and durability of an output image. Further improvement in sex is desired.

  Conventionally, a polycarbonate resin has been often used as a binder resin for the surface layer of an electrophotographic photoreceptor. In recent years, proposals have been made to further improve the durability of an electrophotographic photosensitive member by using a polyarylate resin having a mechanical strength higher than that of a polycarbonate resin (Patent Document 1, etc.). The polyarylate resin is one type of aromatic dicarboxylic acid polyester resin.

  In addition, as a technique for enhancing the durability of the photoreceptor, proposals have been made to include organic resin fine particles and inorganic fine particles in the surface layer of the photoreceptor, but in particular, the inorganic layer is included to increase the strength of the surface layer. Many proposals have been made that high durability photoconductors can be produced (Patent Documents 2 to 4, etc.). Patent Document 3 discloses an electrophotographic photosensitive member having a surface layer made highly durable by combining a polyarylate resin and inorganic fine particles. Patent Document 4 uses a photosensitive layer containing inorganic fine particles and a fluorosurfactant, thereby improving the dispersion stability of the inorganic fine particles, having high wear resistance, and providing a good image. A photoreceptor is disclosed.

  However, although the electrophotographic photoreceptor disclosed in Patent Documents 2 and 3 achieves high durability due to the inclusion of inorganic fine particles, the dispersion stability of the inorganic fine particles is insufficient, and therefore secondary aggregation occurs. . As a result, there has been a problem that scratches are generated on the photoconductor during repeated use of the photoconductor to cause image defects. The problem of generating image scratches due to the inclusion of inorganic fine particles also occurs in combination with the high-strength polyarylate resin used in Patent Document 3, and can be improved simply by improving the strength of the resin used in the photosensitive layer. do not do. This is considered to be due to the fact that in a highly durable photoreceptor, scratches generated on the photoreceptor are less likely to disappear due to rubbing of paper or the like. The above problem is also disclosed in Patent Document 4, which includes a fluorosurfactant to improve dispersion stability and suppress aggregation of inorganic fine particles in the coating liquid. An electrophotographic photoreceptor capable of providing a more stable image is disclosed.

That is, in order to provide a high-strength photoconductor by containing inorganic fine particles, it is necessary to suppress the cause of scratches generated on the photoconductor. When the inorganic fine particles contained in the surface layer become agglomerated, the agglomeration becomes a cause of scratches, so that the dispersed state of the inorganic fine particles contained in the surface layer is stably set to the primary particle size of the inorganic fine particles. It is important to keep. Patent Document 4 discloses that a fluorosurfactant is contained as a technique for stably maintaining the primary particle size. However, since a fluorosurfactant may cause deterioration in photoreceptor characteristics, an alternative method is desired.
Japanese Patent Laid-Open No. 10-039521 Japanese Patent Laid-Open No. 8-146664 JP 2002-351113 A JP 2004-219925 A

  The present invention has been made in view of the above-mentioned problems, and improves the dispersion stability of inorganic fine particles, has high durability, and suppresses scratches that occur on the photosensitive layer during repeated use, thereby stably providing a good image. An object of the present invention is to provide an electrophotographic photoreceptor capable of obtaining the above. Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

This onset Ming, conductive support and Te electrophotographic photoreceptor odor having a photosensitive layer formed on the electrically conductive substrate, the outermost surface layer of the electrophotographic photosensitive member, represented by the following structural formula (1) An electrophotographic photoreceptor comprising a polyarylate resin having a structural unit and inorganic fine particles, wherein the inorganic fine particles are silica or alumina.
(In the formula ^{(1), R 21, R} 23, R 26 and R ²⁸ each independently represent a hydrogen atom or a methyl group, X is a divalent having the structure represented by the following following formula (2) Indicates a group.
(In the formula ^{(2), R 31} and ^{R 32} each independently represent a hydrogen atom or a methyl group, or, ^{R 31} and ^{R 32,} cyclo-hex that the ^{R 31} and ^{R 32} are formed by combining shows the isopropylidene group.))

  A process cartridge and an electrophotographic apparatus according to the present invention include the above-described electrophotographic photosensitive member.

  According to the present invention, it is highly durable and can stably provide a good image even when used repeatedly for a long time.

  As described above, the electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor having a photosensitive layer on a conductive support, wherein the outermost surface layer of the electrophotographic photoreceptor is at least a structural unit represented by the following structural formula (1). A polyarylate resin containing inorganic fine particles.

(In the formula (1),
R ^{11 to} R ¹⁸ and R ^{21 to} R ²⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group, or an alkoxy group having 1 to 3 carbon atoms,
X is a single bond, an oxygen atom, a sulfur atom, or the following formula (2)

(In the formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group. In addition to these, R ³¹ and R ³² represent R ^{31 represents} a cycloalkylidene group or a fluorenylidene group formed by combining R and R ^32. )
The bivalent group which has a structure shown by these is shown. )

  As the inorganic fine particles in the present invention, all inorganic fine particles generally considered not to have conductivity can be used. For example, inorganic salts such as inorganic chlorides and bromides, some inorganic oxides, clays, Examples thereof include ceramics such as silicon nitride. Of these, inorganic oxides are preferable from the viewpoint of chemical stability of the compound. In particular, silica which is an oxide of silicon and alumina which is an oxide of aluminum are preferable. Moreover, these may be used independently or may be used in combination of 2 or more type.

  The average primary particle size of the inorganic fine particles used in the present invention is preferably 1.0 μm or less, and more preferably 0.3 μm or less, from the viewpoint of the transparency of the charge transport layer. Moreover, it is preferable that it is 0.02 micrometer or more from the point which provides mechanical strength effectively, and it is still more preferable that it is 0.05 micrometer or more.

  Further, fine particles obtained by hydrophobizing the surface of the inorganic fine particles may be used. Examples of the surface treatment agent include a silane coupling agent. Specific examples of the silane coupling agent include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N- β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, Examples include decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, and p-methylphenyltrimethoxysilane.

  The content of the inorganic fine particles in the surface layer is preferably 0.5% by mass or more based on the total mass of the solid content of the surface layer in terms of imparting strength, and 2% based on the total mass. More preferably, it is 0.0 mass% or more. In addition, if the surface layer contains excessive inorganic fine particles, it may cause deterioration in sensitivity and image quality due to a decrease in transmittance of image exposure light and light scattering, so the content of inorganic fine particles in the surface layer is It is preferable that it is 30 mass% or less with respect to the total mass of solid content of a surface layer.

  The polyarylate resin in the present invention is characterized by containing a structural unit represented by the following structural formula (1).

(In the formula (1),
R ^{11 to} R ¹⁸ and R ^{21 to} R ²⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group, or an alkoxy group having 1 to 3 carbon atoms,
X is a single bond, an oxygen atom, a sulfur atom, or the following formula (2)

(In the formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group. In addition to these, R ³¹ and R ³² represent R ^{31 represents} a cycloalkylidene group or a fluorenylidene group formed by combining R and R ^32. )
The bivalent group which has a structure shown by these is shown. )

Examples of the alkyl group of R ^{11 to} R ¹⁸ and R ^{21 to} R ^{28 in} the above formula (1) include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Especially, R < ¹¹ > -R < ¹⁸ > and R < ²¹ > -R < ²⁸ > in said formula (1) have a preferable methyl group, an ethyl group, a methoxy group, an ethoxy group, and a phenyl group.

Examples of the alkyl group of R ³¹ and R ^{32 in} the above formula (2) include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the fluorinated alkyl group include a trifluoromethyl group and a pentafluoroethyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the aryl group include a phenyl group and a naphthyl group. Among these, R ³¹ and R ³² in the above formula (2) are preferably a methyl group, an ethyl group, a propyl group (particularly isopropyl group), a trifluoromethyl group, or a pentafluoroethylene group.

Examples of the cycloalkylidene group formed by combining R ³¹ and R ³² in the above formula (2) include a cyclopentylidene group, a cyclohexylidene group, and a cycloheptylidene group. However, a cyclohexylidene group is preferred.

  Specific examples of the repeating structural unit represented by the above formula (1) are shown below.

The polyarylate resin used in the photosensitive layer of the electrophotographic photoreceptor of the present invention has a structural unit represented by the above formula (1), and the content ratio thereof is arbitrary. In particular, in terms such as improving dispersion stability of the inorganic fine particles, a structural unit represented by the above formula (1) in structural units constituting the polyarylate resin is preferably 80 mol% to 100 mol% .

  Further, the polyarylate resin having the structural unit represented by the above formula (1) used in the photosensitive layer of the electrophotographic photoreceptor according to the present invention may be a homopolymer or a polymer as long as it has the structural unit represented by the above formula (1). A copolymer may also be used. The copolymer is a structural unit selected from the above formula (1) that is different from the structural unit represented by the above formula (1) and the structural unit represented by the above formula (1). It may be a copolymer with a structural unit comprising a divalent carboxylic acid and a divalent organic residue. The polymerization form may be any polymerization form such as block copolymerization or random copolymerization, but a random copolymerization form is preferred.

  In the present invention, the structural unit represented by the above formula (1) and the structural unit selected from the above formula (1) different from the structural unit represented by the above selected formula (1), or The description that the copolymerization ratio of the copolymerized polyarylate resin having a structural unit composed of another divalent carboxylic acid and a divalent organic residue is A: B in terms of molar ratio is a dicarboxylic acid represented by the above formula (1). The acid ester moiety is (1-C), the bisphenol moiety is (1-B), the structural unit represented by the above formula (1) different from the structural unit selected from the above formula (1), or other divalent carvone When the dicarboxylic acid ester moiety represented by a structural unit comprising an acid and a divalent organic residue is (3-C) and the bisphenol moiety is (3-B), the dicarboxylic acid ester moiety (1- C): (3-C) is in molar ratio conversion A: a B, bisphenol sites (1-B) :( 3-B) is A in a molar ratio in terms of: means that it is B.

  Examples of the divalent carboxylic acid used in the structural unit composed of the other divalent carboxylic acid and divalent organic residue described above include aromatic divalent carboxylic acids, linear aliphatic divalent carboxylic acids, and cyclic aliphatic dicarboxylic acids. Carboxylic acids and the like. Examples of aromatic divalent carboxylic acids include terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, naphthalenedicarboxylic acid, 3,4'-diphenylether dicarboxylic acid, 3,3'-diphenyletherdicarboxylic acid, and the like. Examples of the linear aliphatic divalent carboxylic acids include succinic acid, adipic acid, sebacic acid, dodecanic acid and the like. Examples of the cycloaliphatic divalent carboxylic acids include cyclohexylene dicarboxylic acid. Among these, terephthalic acid, isophthalic acid, adipic acid, and sebacic acid are preferable as the divalent carboxylic acid used in the structural unit composed of the other divalent carboxylic acid and divalent organic residue. Examples of the divalent organic residue include bisphenols such as 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) and 2,2-bis (3-methyl-4-hydroxyphenyl) propane (bisphenol C), Biphenols such as 4,4′-hydroxybiphenyl are included. Examples of structural units composed of other divalent carboxylic acids and divalent organic residues are shown.

  When the weight average molecular weight (Mw) of the polyarylate resin having the structural unit represented by the above formula (1) used in the photosensitive layer of the electrophotographic photoreceptor of the present invention is arbitrary, but the weight average molecular weight is 80,000 or more In particular, the dispersion stability of the inorganic fine particles is improved.

  On the other hand, when the molecular weight of the polyarylate resin having the structural unit represented by the above formula (1) is too large, the coating property of the coating solution containing this may be deteriorated. For this reason, the weight average molecular weight of the polyarylate resin having the structural unit represented by the above formula (1) is preferably 300,000 or less, more preferably 200000 or less.

  The polyarylate resin having the structural unit represented by the above formula (1) used in the charge transport layer of the electrophotographic photosensitive member of the present invention or the coating solution for an electrophotographic photosensitive member is an ester of a dicarboxylic acid ester and a compound having a hydroxyl group. You may synthesize | combine by the exchange method. Alternatively, it may be synthesized by a polymerization reaction between a divalent acid halide such as dicarboxylic acid halide and a compound having a hydroxyl group such as bisphenol. In order to produce a polyarylate resin having a weight average molecular weight in the above range, it is preferably synthesized by the latter synthesis method.

(Synthesis Example 1)
Are shown below as Synthesis Examples, the total structural units of the polyarylate resin, 100% at a molar ratio in terms of the synthesis method of polyarylate resin is a structural unit represented by the above formula (1-2).

  Diphenyl ether dicarboxylic acid chloride having a structure represented by the following formula (1-2-1) was dissolved in dichloromethane to prepare an acid chloride solution.

  In addition to the acid chloride solution, 2,2-bis (3-methyl-4-hydroxyphenyl) propane having a structure represented by the following formula (1-2-2) is dissolved in a 10% aqueous sodium hydroxide solution. Let To this was added tributylbenzylammonium chloride as a polymerization catalyst and stirred to prepare a 2,2-bis (3-methyl-4-hydroxyphenyl) propane solution.

  Next, the acid chloride solution was added to the 2,2-bis (3-methyl-4-hydroxyphenyl) propane solution with stirring to initiate polymerization. The polymerization was carried out for 3 hours while maintaining the reaction temperature at 25 ° C. or lower and stirring.

  Thereafter, acetic acid was added to terminate the polymerization reaction, and washing with water was repeated until the aqueous phase became neutral.

  After washing, the solution was dropped into methanol with stirring to precipitate a polymer, and this polymer was vacuum-dried to obtain a polyarylate resin which is a structural unit represented by the above formula (1-2). This polyarylate resin had a weight average molecular weight in terms of polystyrene (hereinafter referred to as a weight average molecular weight (Mw)) of 130,000.

  In the present invention, the weight average molecular weight of the resin was measured as follows according to a conventional method.

  That is, the measurement target resin is put in tetrahydrofuran and allowed to stand for several hours, and then the measurement target resin and tetrahydrofuran are mixed well while shaking (mix until the measurement target resin is no longer united), and then allowed to stand for 12 hours or more. did.

  Then, the sample processing filter Myshoori disk H-25-5 by Tosoh Corporation was passed, and this was made into the sample for gel permeation chromatography (GPC).

  Next, the column is stabilized in a heat chamber at 40 ° C., tetrahydrofuran as a solvent is flowed to the column at this temperature at a flow rate of 1 mL / min, 10 μL of a GPC sample is injected, and the weight average molecular weight of the measurement target resin Was measured. A column TSKgel Super HM-M manufactured by Tosoh Corporation was used as the column.

  In measuring the weight average molecular weight of the measurement target resin, the molecular weight distribution of the measurement target resin was calculated from the relationship between the logarithmic value of the calibration curve prepared from several monodisperse polystyrene standard samples and the number of counts. Ten standard disperse polystyrenes (manufactured by Aldrich) having a molecular weight of 800 to 2,000,000 were used as standard polystyrene samples for preparing a calibration curve. An RI (refractive index) detector was used as the detector.

  When forming the surface layer of the present invention, the following may be performed. That is, inorganic fine particles are dispersed in a resin solution in which the polyarylate resin of the present invention is dissolved, and a charge transporting material, a leveling agent, a solvent, and the like are added to the dispersion solution according to a desired surface layer, and a coating solution is added. It is prepared and applied by a coating means to form a photoreceptor. Solvents used at this time include ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as methyl acetate and ethyl acetate, aromatic hydrocarbon solvents such as toluene, xylene and chlorobenzene, 1,4-dioxane, tetrahydrofuran and the like. Alternatively, a hydrocarbon solvent substituted with a halogen atom such as chloroform or the like may be used. These solvents may be used alone or in combination of two or more. Among these solvents, it is preferable to use at least an ether solvent from the viewpoint of resin solubility.

  As a method for preparing a coating solution for forming the surface layer of the electrophotographic photoreceptor of the present invention, an inorganic fine particle dispersion solution comprising the polyarylate resin of the present invention, inorganic fine particles, and a solvent is prepared in advance. You may produce a coating liquid by mixing the dispersion liquid with the solution which added the charge transport material, the leveling agent, the solvent, etc. according to the desired surface layer. Further, in addition to the polyarylate resin of the present invention, inorganic fine particles, and a solvent, a solution in which a charge transport material or a leveling agent corresponding to the desired characteristics of the surface layer is dissolved may be dispersed. As a method of dispersing the polyarylate resin of the present invention, the inorganic fine particles and the solvent, simple mixing and stirring may be used, but if necessary, dispersion means such as a ball mill, a roll mill, a sand mill, a high-pressure homogenizer, and a liquid collision type high-speed dispersion are used. May be. Among these, collision type high speed dispersion is preferable from the viewpoint of productivity.

  Next, the configuration of the electrophotographic photosensitive member of the present invention will be described.

  The electrophotographic photoreceptor of the present invention has a support and a photosensitive layer provided on the support. The electrophotographic photoreceptor according to the present invention may be a so-called single-layer photoreceptor having a photosensitive layer containing a charge generation material and a charge transport material. In addition, the photosensitive layer may be a so-called laminated type or function separation type photoconductor including a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. The electrophotographic photoreceptor according to the present invention is preferably a laminated photoreceptor in that it exhibits good photoreceptor properties. Among these, a normal photosensitive layer in which a charge generation layer and a charge transport layer are laminated in this order from the support side is preferable. Furthermore, a protective layer intended to protect the photosensitive layer may be provided on the charge transport layer.

  The outermost surface layer containing the polyarylate resin and inorganic fine particles in the present invention corresponds to the entire photosensitive layer in the single-layer type photoreceptor, and corresponds to the charge transport layer in the laminated type photoreceptor. In the photoreceptor having a protective layer, the outermost surface layer is a protective layer. When the electrophotographic photoreceptor according to the present invention has a protective layer, the protective layer contains a polyarylate resin and inorganic fine particles.

  As a support body, what is necessary is just the electroconductive support body which has electroconductivity, For example, metal (alloy-made) support bodies, such as aluminum, aluminum alloy, and stainless steel, can be used. Moreover, you may use the said metal support body and plastic support body which have the layer which formed the film by vacuum deposition of aluminum, an aluminum alloy, an indium oxide tin oxide alloy, etc. Further, a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles, and silver particles are impregnated with plastic or paper together with an appropriate binder resin, a plastic support having a conductive binder resin, etc. May be used. Examples of the shape of the support include a cylindrical shape and a belt shape, and a cylindrical shape is preferable.

  The surface of the support may be subjected to cutting treatment, roughening treatment, alumite treatment, etc. for the purpose of preventing interference fringes due to scattering of laser light or the like.

  Between the support and the photosensitive layer (charge generation layer, charge transport layer) or an intermediate layer described later, a conductive layer for the purpose of preventing interference fringes due to scattering of laser light or the like and covering the scratches on the support May be provided.

  The conductive layer can be formed by dispersing conductive particles such as carbon black, metal particles, and metal oxide particles in a binder resin.

  The thickness of the conductive layer is preferably 1 to 40 μm, and more preferably 2 to 20 μm.

  An intermediate layer having a barrier function or an adhesive function may be provided between the support or the conductive layer and the photosensitive layer (charge generation layer, charge transport layer). The intermediate layer is formed for the purpose of improving the adhesion of the photosensitive layer, improving the coating property, improving the charge injection property from the support, and protecting the photosensitive layer from electrical breakdown.

  The intermediate layer is acrylic resin, allyl resin, alkyd resin, ethyl cellulose resin, ethylene-acrylic acid copolymer, epoxy resin, casein resin, silicone resin, gelatin resin, phenol resin, butyral resin, polyacrylate resin, polyacetal resin, polyamideimide resin , Polyamide resin, polyallyl ether resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl alcohol resin, polybutadiene resin, polypropylene resin, urea resin, aluminum oxide, etc. It can be formed using the material.

  The thickness of the intermediate layer is preferably 0.05 to 5 μm, and more preferably 0.3 to 2.0 μm.

  Examples of the charge generating material used in the electrophotographic photosensitive member of the present invention include azo pigments such as monoazo, disazo, and trisazo, phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, indigo pigments such as indigo and thioindigo, Perylene pigments such as perylene acid anhydride and perylene imide, polycyclic quinone pigments such as anthraquinone, pyrenequinone, dibenzpyrenequinone, squarylium dyes, pyrylium salts and thiapyrylium salts, triphenylmethane dyes, selenium, Inorganic materials such as selenium-tellurium and amorphous silicon, quinacridone pigments, azurenium salt pigments, cyanine dyes such as quinocyanine, anthanthrone pigments, pyranthrone pigments, xanthene dyes, quinoneimine dyes, styryl Motoya, and cadmium sulfide, and zinc oxide. These charge generation materials may be used alone or in combination of two or more.

  When the photosensitive layer is a laminated photosensitive layer and the charge generation layer is not a surface layer of an electrophotographic photosensitive member, examples of the binder resin used for the charge generation layer include acrylic resins, allyl resins, and alkyd resins. , Epoxy resin, diallyl phthalate resin, silicone resin, styrene-butadiene copolymer, phenol resin, butyral resin, benzal resin, polyacrylate resin, polyacetal resin, polyamideimide resin, polyamide resin, polyallyl ether resin, polyarylate resin, polyimide resin , Polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl acetal resin, polybutadiene resin, polypropylene resin, methacrylic resin, urea resin, vinyl chloride Vinyl acetate copolymers, vinyl acetate resins, and vinyl chloride resins. In particular, the binder resin used for the charge generation layer is preferably a butyral resin. These may be used alone or in combination as a mixture or copolymer.

  The charge generation layer may be formed by applying a charge generation layer coating solution obtained by dispersing a charge generation material together with a binder resin and a solvent and drying the coating solution. Examples of the dispersion method include a method using a homogenizer, an ultrasonic disperser, a ball mill, a sand mill, a roll mill, a vibration mill, an attritor, a liquid collision type high-speed disperser, and the like. The ratio between the charge generating material and the binder resin is preferably in the range of 1: 0.3 to 1: 4 (mass ratio).

  The solvent used in the coating solution for the charge generation layer is selected from the solubility and dispersion stability of the binder resin and charge generation material to be used. As the organic solvent, alcohol, sulfoxide, ketone, ether, ester, aliphatic Examples thereof include halogenated hydrocarbons and aromatic hydrocarbons.

  The film thickness of the charge generation layer is preferably 5 μm or less, more preferably 0.1 to 2 μm.

  Further, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers and the like may be added to the charge generation layer as necessary.

  Examples of the charge transport material used in the electrophotographic photoreceptor of the present invention include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triarylmethane compounds. These charge transport materials may be used alone or in combination of two or more.

  When the charge transport layer is a surface layer, it contains at least inorganic fine particles and the polyarylate resin of the present invention, but other resins exemplified below may be used in combination as long as the effects of the present invention are not impaired. . In that case, the proportion of the polyarylate resin of the present invention in the charge transport layer is preferably 50% by mass or more based on the total mass of the binder resin contained in the charge transport layer. In particular, it is more preferably 70% by mass or more. Examples of resins that can be used in combination include acrylic resins, acrylonitrile resins, allyl resins, alkyd resins, epoxy resins, silicone resins, phenol resins, phenoxy resins, butyral resins, polyacrylamide resins, polyacetal resins, polyamideimide resins, polyamide resins, Polyallyl ether resin, polyarylate resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polystyrene resin, polysulfone resin, polyvinyl butyral resin, polyphenylene oxide resin, polybutadiene resin, polypropylene resin, methacrylic resin, Examples include urea resin, vinyl chloride resin, and vinyl acetate resin. In particular, polyarylate resin, polycarbonate resin and the like are preferable. These can be used singly or in combination of two or more as a mixture or a copolymer.

  When the charge transport layer is not a surface layer, it is not always necessary to contain the inorganic fine particles and the polyarylate resin of the present invention, and it contains a charge transport material and a resin selected from the above resins.

  The charge transport layer can be formed by applying a charge transport layer coating solution obtained by dissolving a charge transport material and a binder resin in a solvent and drying it. The ratio between the charge transport material and the binder resin is preferably in the range of 2: 1 to 1: 2 (mass ratio).

  Solvents used in the coating solution for the charge transport layer include ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as methyl acetate and ethyl acetate, aromatic hydrocarbon solvents such as toluene, xylene and chlorobenzene, 1,4- Ether solvents such as dioxane and tetrahydrofuran, and hydrocarbon solvents substituted with halogen atoms such as chloroform are used. These solvents may be used alone or in combination of two or more. Among these solvents, it is preferable to use an ether solvent or an aromatic hydrocarbon solvent from the viewpoint of resin solubility.

  The thickness of the charge transport layer is preferably 5 to 40 μm, and more preferably 10 to 35 μm.

  Moreover, you may add antioxidant, a ultraviolet absorber, a plasticizer, etc. to a charge transport layer as needed.

  Further, as described above, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. The protective layer can be formed by applying a protective layer coating solution obtained by dissolving a binder resin in a solvent and drying the coating solution. When the surface layer is a protective layer, it contains at least inorganic fine particles and the polyarylate resin of the present invention. In this protective layer, you may have a charge transport material, a leveling agent, antioxidant, etc. as needed.

  The thickness of the protective layer is preferably 0.5 to 10 μm, and more preferably 1 to 5 μm.

  When applying the coating liquid for each layer described above, for example, a coating method such as a dip coating method (dip coating method), a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, a blade coating method, or the like is used. May be.

  FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.

  In FIG. 1, reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is rotationally driven in a direction of an arrow about a shaft 2 at a predetermined peripheral speed.

  The surface of the electrophotographic photosensitive member 1 that is driven to rotate is uniformly charged to a predetermined positive or negative potential by a charging unit (primary charging unit: charging roller) 3. Next, exposure light (image exposure light) 4 output from exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the surface of the electrophotographic photosensitive member 1.

  The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner contained in the developer of the developing means 5 to become a toner image. Next, the toner image formed and supported on the surface of the electrophotographic photoreceptor 1 is transferred from the transfer material supply means (not shown) to the electrophotographic photoreceptor 1 by a transfer bias from a transfer means (transfer roller or the like) 6. The image is sequentially transferred to a transfer material (paper or the like) P fed between the means 6 (contact portion) in synchronization with the rotation of the electrophotographic photosensitive member 1.

  The transfer material P that has received the transfer of the toner image is separated from the surface of the electrophotographic photosensitive member 1 and introduced into the fixing means 8 to receive the image fixing, and is printed out as an image formed product (print, copy). Is done.

  The surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is cleaned by receiving a developer (toner) remaining after transfer by a cleaning means (cleaning blade or the like) 7. Further, the surface of the electrophotographic photoreceptor 1 is subjected to charge removal processing by pre-exposure light (not shown) from pre-exposure means (not shown), and then repeatedly used for image formation. As shown in FIG. 1, when the charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not necessarily required.

  Among the above-described components such as the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, the transfer unit 6, and the cleaning unit 7, a plurality of components may be housed in a container and integrally combined as a process cartridge. Good. The process cartridge may be configured to be detachable from the main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. In FIG. 1, an electrophotographic photosensitive member 1, a charging unit 3, a developing unit 5, and a cleaning unit 7 are integrally supported to form a cartridge, and an electrophotographic apparatus is provided using a guide unit 10 such as a rail of the electrophotographic apparatus main body. The process cartridge 9 is detachable from the main body.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these. In the examples, “part” means “part by mass”. “Mw” means “weight average molecular weight”.

Example 1
(Coating solution preparation)
10 parts of silica fine particles (average primary particle size 0.1 μm, trade name: KMPX-100, manufactured by Shin-Etsu Chemical Co., Ltd.) as inorganic fine particles and a polyarylate resin having a structural unit represented by the above formula (1-2) (Mw: 130000) 50 parts and 450 parts of tetrahydrofuran (THF) as a solvent were mixed to dissolve the polyarylate resin. Thereafter, using a high-speed liquid collision type dispersion machine (manufactured by Microfluidics Corporation), dispersion is performed twice at a dispersion pressure of 600 kgf / cm ² , and 20 parts of the charge transport material represented by the following structural formula (4) is added to the dispersion liquid. Dissolved to prepare coating solution A.

This coating liquid A was put into a cylindrical container having an inner diameter of 20 cm, and after stirring for 100 hours at 1 rotation / second using a roll base, the coating liquid A was allowed to stand for 24 hours to prepare coating liquid B.

(Photoconductor production)
An aluminum cylinder having a diameter of 30 mm and a length of 357.5 mm was used as a support.

  Next, the coating liquid for conductive layers was prepared using the following components.

SnO ₂ Coated barium sulfate (conductive particles) 10 parts Titanium oxide (resistance resistance pigment) 2 parts Phenol resin (binder resin) 6 parts Silicone oil (leveling agent) 0.001 part Methanol 4 parts / Methoxypropanol 16 parts Mixed solvent

  This conductive layer coating solution was dip-coated on a support and thermally cured at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 15 μm.

  Next, 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon were dissolved in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol to prepare an intermediate layer coating solution.

  This intermediate layer coating solution was dip coated on the conductive layer and dried at 100 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.7 μm.

  Next, strong peaks at 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 ° with a Bragg angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction 10 parts of a crystalline hydroxygallium phthalocyanine (charge generating material) having benzene is added to a solution obtained by dissolving 5 parts of polyvinyl butyral resin (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 250 parts of cyclohexanone. Then, dispersion was performed in a sand mill apparatus using glass beads having a diameter of 1 mm in an atmosphere of 23 ± 3 ° C. for 1 hour. After dispersion, 250 parts of ethyl acetate was added to prepare a coating solution for charge generation layer.

  This charge generation layer coating solution was dip coated on the intermediate layer and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.26 μm.

  A coating liquid A containing the above-mentioned inorganic fine particles and the polyarylate resin according to the present invention is dip-coated on the charge generation layer, dried at 120 ° C. for 1 hour, and a surface layer (charge transport layer) having a thickness of 32 μm. And an electrophotographic photosensitive member (1-A) was produced.

  Further, the above coating solution B is dip coated on the charge generation layer and dried at 120 ° C. for 1 hour to form a surface layer (charge transport layer) having a film thickness of 32 μm. B) was prepared.

  Next, evaluation will be described.

  Evaluation of the dispersibility of the inorganic fine particles was analyzed using a surface image obtained by observing the surface of the photoreceptor (1-A) with a surface observation microscope (VE-7800: manufactured by Keyence Corporation). That is, the number of inorganic fine-particle aggregates (lumps formed by contacting a plurality of fine particles) present in a 100 × 100 μm square on the surface 180 mm from the upper end of the photoreceptor is measured, and the same measurement is performed. The photoconductor was rotated 90 ° in the direction, a total of 4 points were measured, and the average value was calculated (rounded off after the decimal point).

  Evaluation of the dispersion stability of the inorganic fine particles was analyzed using a surface image obtained by observing the surface of the photoreceptor (1-B) with a surface observation microscope (VE-7800: manufactured by Keyence Corporation). That is, the number of inorganic fine-particle aggregates (lumps formed by contacting a plurality of fine particles) present in a 100 × 100 μm square on the surface 180 mm from the upper end of the photoreceptor is measured, and the same measurement is performed. The photoconductor was rotated 90 ° in the direction, a total of 4 points were measured, and the average value was calculated (rounded off after the decimal point).

  The evaluation of scratches on the photoconductor during repeated use of the photoconductor is based on Canon Co., Ltd. copier iR400 using the photoconductor (1-B) as a photoconductor (charged in contact with the electrophotographic photoconductor). An AC / DC charging method in which a DC voltage superimposed with an AC voltage is applied from the member to charge the electrophotographic photosensitive member is used. Copying 20000 sheets in an intermittent mode in which A4-size plain paper is stopped once for each copy, and then measuring the surface roughness of the surface at a position 180 mm from the upper end of the photoreceptor (Surfcoder SE-3400). , Manufactured by Konishi Laboratories Co., Ltd.) was evaluated (evaluation length: 10 mm) in accordance with 10-point average roughness (Rzjis) evaluation in JIS B 0601: 2001. Table 12 shows the inorganic fine particles used in the surface layer and the types of the polyarylate resin of the present invention, and Table 13 shows the evaluation results.

(Examples 2 to 5)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the polyarylate resin contained in the outermost surface layer was changed as shown in Table 12. The results are shown in Table 13.

(Examples 6 to 10)
In Example 1, alumina (average primary particle size: 0.1 μm, trade name: LS-231, manufactured by Nippon Light Metal Co., Ltd.) was used as the inorganic fine particles contained in the outermost surface layer, and the poly contained in the outermost surface layer. An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the arylate resin was changed as shown in Table 12. The results are shown in Table 13.

(Examples 11 to 15)
In Example 1, silica (average primary particle size: 0.08 μm, trade name: Nanotek-SiO ₂ ; manufactured by C-I Kasei Co., Ltd.) is used as the inorganic fine particles contained in the outermost surface layer, and contained in the outermost surface layer. An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the polyarylate resin was changed as shown in Table 12. The results are shown in Table 13.

(Examples 16 and 17)
In Example 1, silica (average primary particle size 0.1 μm, trade name: Silica Doll-30G-100, manufactured by Nippon Chemical Industry Co., Ltd.) was used for the inorganic fine particles contained in the outermost surface layer. An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the polyarylate resin contained was as shown in Table 12. The results are shown in Table 13.

(Example 18)
In Example 1, 40 parts of polyarylate resin (Mw: 130000) having a structural unit represented by the above formula (1-2) as a resin contained in the outermost surface layer and a polycarbonate resin represented by the following structural formula (5) An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that 10 parts (Iupilon Z400, manufactured by Mitsubishi Engineering Plastics) were mixed and used. The results are shown in Table 13.

(Example 19)
In Example 1, 40 parts of a polyarylate resin (Mw: 130000) having a structural unit represented by the above formula (1-2) as the resin contained in the outermost surface layer The above structural formulas (3-2) and (3- An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that 10 parts of 5: 5 copolymer polyarylate (Mw: 130000) of 13) was used. The results are shown in Table 13.

(Example 20)
The charge generation layer was fabricated in the same manner as in Example 1.

  40 parts of the charge transport material represented by the above formula (4) and 50 parts of the polycarbonate resin (Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) represented by the above structural formula (5) are converted into 500 parts of 1,4-dioxane. A charge transport layer coating solution was prepared by dissolution, dip coated on the charge generation layer, and dried at 120 ° C. for 1 hour to prepare a charge transport layer having a thickness of 15 μm.

  Furthermore, the coating liquid A containing the inorganic fine particles described in Example 1 and the polyarylate resin of the present invention was dip coated on the charge transport layer, dried at 120 ° C. for 1 hour, and a surface layer having a thickness of 5 μm ( Protective layer) was formed to produce an electrophotographic photoreceptor (1-A).

  Further, the above coating solution B is dip coated on the charge generation layer and dried at 120 ° C. for 1 hour to form a surface layer (protective layer) having a thickness of 5 μm. ) Was produced.

  Evaluation similar to Example 1 was performed. The results are shown in Table 13.

(Example 21)
In Example 20, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the polyarylate resin contained in the outermost surface layer was changed as shown in Table 12. The results are shown in Table 13.

(Comparative Example 1)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the polyarylate resin contained in the outermost surface layer was changed as shown in Table 12. The results are shown in Table 13.

(Comparative Example 2)
In Example 6, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the polyarylate resin contained in the outermost surface layer was changed as shown in Table 12. The results are shown in Table 13.

(Comparative Example 3)
In Example 1, except that 50 parts of polyarylate resin (Mw = 110000: terephthalic acid / isophthalic acid = 5/5) represented by the following structural formula (6) was used as the resin contained in the outermost surface layer. An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 13.

(Comparative Example 4)
In Example 6, the electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 50 parts of the polyarylate resin (Mw = 110000) represented by the above formula (6) was used as the resin contained in the outermost surface layer. Prepared and evaluated. The results are shown in Table 13.

(Comparative Example 5)
In Example 1, except that 50 parts of 7: 3 copolymer polyarylate (Mw = 120,000) of the above structural formulas (3-10) and (3-21) were used as the resin contained in the outermost surface layer. An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 13.

(Comparative Example 6)
In Example 1, the electrophotographic photoreceptor is the same as Example 1 except that 50 parts of the polyarylate resin (Mw = 130,000) represented by the following structural formula (7) is used as the resin contained in the outermost surface layer. Were made and evaluated. The results are shown in Table 13.

  From the comparison between the example and the comparative example, when the inorganic fine particles and the polyarylate resin of the present invention are used in the outermost surface layer of the photoreceptor, secondary aggregation of the inorganic fine particles can be reduced, and as a result, on the photoreceptor. It has been shown to reduce scratches. Observation of the photoreceptor surface shows that not only the dispersion stability in the photoreceptor coating solution can be improved, but also the occurrence of aggregation during the production of the coating film can be suppressed. This is because the dispersion stability of the inorganic fine particles is enhanced by the specific structure of the resin of the present invention. Although the factor is not clear, it is considered that the inorganic fine particles are included by the structure of the dicarboxylic acid portion of the polyarylate resin of the present invention, and this leads to suppression of aggregation. This indicates that the significant improvement in dispersibility and dispersion stability is not due to a change in the partial structure of the bisphenol moiety of the polyarylate resin, but a change in the dicarboxylic acid moiety, as compared with Examples and Comparative Examples 1 to 5. This has a great effect. Further, by comparing the example and the comparative example 6, if the dicarboxylic acid site is changed, the dispersibility and dispersion stability are not necessarily improved, and the diphenyl ether dicarboxylic acid structure of the polyarylate resin of the present invention is specific. The results show that this is effective. It is considered that these results support that a remarkable effect can be achieved by combining the polyarylate resin according to the present invention and inorganic fine particles.

FIG. 2 is a diagram illustrating an example of a contact charging type process cartridge and an electrophotographic apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Cleaning means 8 Fixing means 9 Process cartridge 10 Guide means P Transfer material

Claims (7)

Conductive support and Te electrophotographic photoreceptor odor having a photosensitive layer formed on the electrically conductive substrate, the outermost surface layer of the electrophotographic photosensitive member has a structural unit represented by the following structural formula (1) An electrophotographic photoreceptor comprising a polyarylate resin and inorganic fine particles, wherein the inorganic fine particles are silica or alumina.
(In the formula ^{(1), R 21, R} 23, R 26 and R ²⁸ each independently represent a hydrogen atom or a methyl group, X is a divalent having the structure represented by the following following formula (2) Indicates a group.
(In the formula ^{(2), R 31} and ^{R 32} each independently represent a hydrogen atom or a methyl group, or, ^{R 31} and ^{R 32,} cyclo-hex that the ^{R 31} and ^{R 32} are formed by combining shows the isopropylidene group.)) The content of the outermost surface layer of the inorganic fine particles, wherein the total mass of the solid content of the outermost surface layer, the electrophotographic according to Der Ru請 Motomeko 1 0.5% by weight to 30% by weight Photoconductor. The structural formula (1) structural unit represented by the wherein said poly entire structure in forming a unit of polyarylate resin, electrophotographic photosensitive member according to Der Ru請 Motomeko 1 or 2 80 mol% to 100 mol%. Wherein the poly weight average molecular weight of polyarylate resin (Mw) is an electrophotographic photosensitive member according to any one of 請 Motomeko 1 to 3 Ru der 80000 or 300,000. A method for producing an electrophotographic photosensitive member according to any one of claims 1 to 4, before Kipo Riarireto resin, the outermost layer by using a coating liquid containing the inorganic fine particles and tetrahydrofuran formed And a method for producing an electrophotographic photosensitive member. An electrophotographic photosensitive member according to any one of claims 1 to 4, charging means, and at least one means selected from the group consisting of the transfer means and a cleaning means integrally supported, in an electrophotographic apparatus main body A process cartridge that is detachable. The electrophotographic photosensitive member according to any one of claims 1 to 4, charging means, exposure means, developing means, transfer means, and an electrophotographic apparatus characterized by having a cleaning unit.