JP6455025B2 - Electrophotographic photoreceptor - Google Patents

Description

  The present invention relates to an electrophotographic photoreceptor using a polyarylate resin.

  Currently, electrophotographic photoreceptors are widely applied to copying machines, laser printers, fax machines, and the like.

  As an electrophotographic photoreceptor using an organic photoconductive material, a single-layer photoreceptor or a laminated photoreceptor in which a charge generation layer and a charge transport layer are laminated is known.

  When an organic photoconductive substance is used in the electrophotographic photosensitive member, characteristics such as sensitivity, residual potential, and electric characteristics depend on the charge generating substance, charge transporting substance, additive, and binder resin.

  A polyarylate resin is used as a binder resin used in a photosensitive layer, particularly a charge transport layer (Patent Document 1).

The photoreceptor is subjected to various mechanical and chemical actions in the repeated processes of charging, exposure, development, transfer, and cleaning in the image forming apparatus, and the mechanical characteristics and electrostatic characteristics are deteriorated.

  As the electrophotographic photosensitive member increases in speed and size, the rubber hardness and contact pressure are inevitably increased in order to sufficiently clean the rubber blade in the cleaning unit as the diameter of the photosensitive member decreases.

  Conventional photoconductors with polymer charge transporting materials can store minute cracks on the film surface or inside the film when stored in a high temperature and high humidity environment or when the photoconductor surface is in contact with paper, rubber, hands, fingers, etc. (Chemical cracks) and scratches occur, and abnormal images corresponding to the scratches are generated during image formation, and the photosensitive layer is peeled off. In addition to this, in an image forming apparatus using a belt-shaped photosensitive member conveyed by a small-diameter driving and supporting roller, a large tension is applied to the belt photosensitive member during driving or on the small-diameter roller, and microcracks are generated. It was easy to use and had the drawback of significantly shortening the life of the photoreceptor.

JP 2011-170041 A

  It is an object of the present invention to provide an electrophotographic photoreceptor having a low residual potential and few cracks.

<1>
An electrophotographic photosensitive member having a photosensitive layer on a conductive substrate,
Electrophotographic photosensitivity using polyarylate resin obtained by using dihydric phenol, aromatic dicarboxylic acid or acid halide, and terminal blocker represented by general formula (1) as raw materials as binder resin for the photosensitive layer body.

(In the formula, Y represents a hydroxyl group or an acid chloride. N represents an integer of 1 to 3. X represents

R ₁ represents an alkyl group having 5 to 20 carbon atoms which may be branched, and R _{2 to} R ₄ each represents an alkyl group having 4 to 20 carbon atoms which may be branched.

<2>
The compound represented by the general formula (1) is composed of para-t-octylphenol, paranonylphenol, paradodecylphenol, butyl 4-hydroxybenzoate, 2-ethylhexyl 4-hydroxybenzoate, and dodecyl 4-hydroxybenzoate. The electrophotographic photosensitive member according to <1>, which is one or more selected from the group.

<3>
The dihydric phenol component is 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) ether, 4,4 ′-[1,3- Phenylenebis (1-methylethylidene)] bisphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis 1 selected from the group consisting of (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, and 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane The electrophotographic photosensitive member according to <1> or <2>, which is a seed or more.

<4>
The electrophotographic photosensitive member according to any one of <1> to <3>, wherein the polystyrene equivalent weight average molecular weight measured by gel permeation chromatography of polyarylate is 20,000 or more and less than 300,000.

<5>
The electrophotographic photosensitive member according to any one of <1> to <4>, wherein the photosensitive layer has a charge transport layer and a charge generation layer, and a binder resin is used for the charge transport layer.

  An electrophotographic photosensitive member having a low residual potential and few cracks can be obtained.

  The electrophotographic photoreceptor of the present invention has a photosensitive layer on a conductive substrate.

(1) Conductive substrate As the conductive substrate of the electrophotographic photoreceptor of the present invention, a metal material such as aluminum, stainless steel or nickel, or a conductive layer such as aluminum, palladium, tin oxide or indium oxide on the surface is used. The provided polyester film, phenol resin, paper or the like is used.

(2) Photosensitive layer Examples of the photosensitive layer of the electrophotographic photosensitive member include a single layer type composed of a single photoconductive layer and a function separated layer type. The laminated type is composed of two layers of a charge generation layer that generates charges by exposure and a charge transport layer that transports charges. In recent years, electrophotographic photoreceptors using a laminated photosensitive layer have become mainstream. The photosensitive layer of the electrophotographic photoreceptor of the present invention may be either a single layer type or a multilayer type, but is preferably a multilayer type.
The electrophotographic photosensitive member of the present invention may be provided with an undercoat layer, a protective layer, an adhesive layer and the like, if necessary, in addition to the conductive substrate and the photosensitive layer.

When the photosensitive layer of the electrophotographic photoreceptor of the present invention is a single layer type, the polyarylate resin is used as a binder resin for the photosensitive layer (photoconductive layer). In this case, the mixing ratio of the charge generating material / charge transporting material and the binder resin is preferably in the range of 10: 1 to 1:20. The thickness of the photoconductive layer is 2 to 100 μm, preferably 5 to 30 μm.
Examples of the charge generating substance include fine particle organic pigments such as azoxybenzene, disazo, trisazo, benzimidazole, polycyclic quinoline, indigoid, quinacridone, phthalocyanine, perylene, and methine. Can be used. These charge generation materials are used in the form of fine particles dispersed in a binder resin.
Examples of the charge transport material include polytetracyanoethylene; fluorenone compounds such as 2,4,7-trinitro-9-fluorenone; nitro compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; Triphenylmethane compounds; oxadiazole compounds such as 2,5-di (4-dimethylaminophenyl) -1,3,4-oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene Carbazole compounds such as poly-N-vinylcarbazole; pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline; 4,4 ′, 4 ″ -tris (N, N-diphenylamino); Triphenylamine, N, N′-bis (3-methylphenyl) -N, N′-bis ( Benzyl) amine derivatives such as benzidine; conjugated unsaturated compounds such as 1,1-bis (4-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene; 4- (N, N-diethylamino) benzaldehyde-N, Hydrazone compounds such as N-diphenylhydrazone; nitrogen-containing compounds such as indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds, triazole compounds Examples thereof include condensed polycyclic compounds, etc. The above charge transport materials may be used alone or in combination of two or more.

  In the electrophotographic photoreceptor having the laminated photosensitive layer, the charge generation layer is formed on a conductive substrate by a known method using a binder resin in which a charge generation material is dispersed. Examples of the charge generating substance include fine-grained organic pigments such as azoxybenzene, disazo, trisazo, benzimidazole, polycyclic quinoline, indigoid, quinacridone, phthalocyanine, perylene, and methine. Can be used. These charge generation materials are used in the form of fine particles dispersed in a binder resin.

In the case of the laminated type, as the binder resin of the charge generation layer, polyvinyl butyral resin, polyvinyl formal resin, silicone resin, polyamide resin, polyester resin, polystyrene resin, polycarbonate resin, polyvinyl acetate resin, polyurethane resin, phenoxy resin, epoxy resin, Various celluloses and the like can be mentioned, and polyvinyl butyral resin is preferably used.
The mixing ratio of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:20. The charge generation layer has a thickness of 0.01 to 20 μm, preferably 0.1 to 2 μm.

  The charge transport layer is formed on the charge generation layer using a binder resin in which a charge transport material is dispersed by a known method. Examples of the charge transport material include polytetracyanoethylene; fluorenone compounds such as 2,4,7-trinitro-9-fluorenone; nitro compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; Triphenylmethane compounds; oxadiazole compounds such as 2,5-di (4-dimethylaminophenyl) -1,3,4-oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene Carbazole compounds such as poly-N-vinylcarbazole; pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline; 4,4 ′, 4 ″ -tris (N, N-diphenylamino); Triphenylamine, N, N′-bis (3-methylphenyl) -N, N′-bi Amine derivatives such as (phenyl) benzidine; conjugated unsaturated compounds such as 1,1-bis (4-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene; 4- (N, N-diethylamino) benzaldehyde-N Hydrazone compounds such as N-diphenylhydrazone; including indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds, triazole compounds, etc. Examples thereof include nitrogen cyclic compounds, condensed polycyclic compounds, etc. The above charge transport materials may be used alone or in combination.

As the binder resin for the charge transport layer, the polyarylate resin is used. Other resins than the polyarylate may be used in combination. Examples of other resins include polycarbonate resin, polyvinyl butyral resin, polyvinyl formal resin, silicone resin, polyamide resin, polyester resin, polystyrene resin, polycarbonate resin, polyvinyl acetate resin, polyurethane resin, phenoxy resin, epoxy resin, and various celluloses. The
The mixing ratio of the polyarylate and the other resin in the binder resin is preferably in the range of 10: 0 to 5: 5.
The mixing ratio of the charge transport material and the binder resin is preferably in the range of 10: 1 to 1:10. The thickness of the charge transport layer is 2 to 100 μm, preferably 5 to 30 μm.

(3) Polyarylate resin The binder resin used in the photosensitive layer according to the invention contains polyarylate.
This polyarylate is a polyarylate obtained using a dihydric phenol, an aromatic dicarboxylic acid or derivative, and an end-capping agent as a raw material, and a compound represented by the general formula (2) is used as the end-capping agent. It is a polyarylate characterized by being made.

(In the formula, Y represents a hydroxyl group or an acid chloride. N represents an integer of 1 to 3. X represents

R ₁ represents an alkyl group having 5 to 20 carbon atoms which may be branched, and R _{2 to} R ₄ each represents an alkyl group having 4 to 20 carbon atoms which may be branched. )

  As a method for producing the polyarylate of the present invention, an interfacial polymerization method, a solution polymerization method, a melt polymerization method or the like can be used. Among these, a polyarylate resin produced by an interfacial polymerization method is preferable because it has good color tone and physical properties.

  In the present invention, the compound represented by the general formula (2) includes ortho-t-amylphenol, para-t-amylphenol, parahexylphenol, para-t-octylphenol, paranonylphenol, paradodecylphenol, 2, Monophenols such as 4-di-t-amylphenol; butyl 4-hydroxybenzoate, 4-hydroxybenzoate-n-pentyl, 4-hydroxybenzoate-n-hexyl, 4-hydroxybenzoate-2-ethylhexyl, Monohydroxybenzoic acids such as 4-hydroxybenzoic acid-n-octyl, 4-hydroxybenzoic acid-n-nonyl, 4-hydroxybenzoic acid-n-dodecyl; 4-n-pentylbenzoyl chloride, 4-n-hexylbenzoyl Chloride, 4--2-ethylhexylbenzoy Chloride, 4-n-octyl benzoyl chloride, 4-n-nonyl benzoyl chloride, 4-n-dodecyl benzoyl chloride, acid chlorides such as 4-n-stearyl benzoyl chloride are exemplified. Two or more of these may be used in combination. Of these, para-t-octylphenol, paranonylphenol, paradodecylphenol, butyl 4-hydroxybenzoate, 2-ethylhexyl 4-hydroxybenzoate, and dodecyl 4-hydroxybenzoate are preferable.

  Specific examples of the dihydric phenol that can be used in the polyarylate of the present invention include 2,2-bis (4-hydroxyphenyl) propane = (bisphenol A), 1,1′-biphenyl-4,4′-diol, 1,1′-biphenyl-3,3′-dimethyl-4,4′-diol, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4 -Hydroxy-3-methylphenyl) propane, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxy-3-methylphenyl) sulfone, Bis (4-hydroxyphenyl) ketone, 2,2-bis (4-hydroxy-3-tert-butylphenyl) propane, , 1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 1-bis (4-hydroxyphenyl) cyclododecane, 2,2-bis (4-hydroxy) Phenyl) hexafluoropropane, bis (4-hydroxyphenyl) diphenylmethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxy-3-methylphenyl) -1- Phenylethane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, α, ω-bis [2- (p-hydroxyphenyl) ethyl] poly Dimethylsiloxane, α, ω-bis [3- (o-hydroxyphenyl) propyl] polydimethylsiloxane Xanthine, 4,4 ′-[1,4-phenylenebis (1-methylethylidene)] bisphenol, bis (4-hydroxyphenyl) ether, 4,4 ′-[1,3-phenylenebis (1-methylethylidene)] Bisphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) decane, 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) -2-methylpropane, 2,2-bis (4-hydroxyphenyl) octane, 1,1-bis (4-hydroxyphenyl) propane, 3,3-bis (4-hydroxyphenyl) pentane 1,1-bis (4-hydroxyphenyl) -3-methylbutane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexene 2,2-bis (4-hydroxyphenyl) decane, 1,1-bis (4-hydroxyphenyl) dodecane, 2,2-bis (4-hydroxyphenyl) tridecane, 2,2-bis (4-hydroxy) -3-sec-butylphenyl) propane and the like are shown. Two or more of these may be used in combination. Among these, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) ether, 4,4 ′-[1,3- Phenylenebis (1-methylethylidene)] bisphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (4-Hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, and 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane are preferred.

  In the polyarylate according to the present invention, the compound represented by the general formula (2) is a molar ratio of the compound of the general formula (2) to the dihydric phenol, specifically, to the total divalent phenol used. And preferably in the range of 50: 1 to 5: 1 (all dihydric phenol used: compound of general formula (2)). Within that range, it is possible to achieve both fluidity and mechanical strength, particularly in injection molding. More preferably, it is in the range of 25: 1 to 7: 1.

  Examples of the aromatic dicarboxylic acid or acid halide that can be used in the polyarylate of the present invention include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 3-tert-butylisophthalic acid, diphenic acid, 4 4,4'-dicarboxylic acids and their acid chlorides. These divalent dicarboxylic acids can be used alone or in combination of two or more. Aromatic dicarboxylic acids which can be used particularly preferably are terephthalic acid and isophthalic acid and their acid chlorides.

  When the polyarylate of the present invention is produced by the interfacial polymerization method, the dihydric phenol, the compound represented by the general formula (2), the alkali, the aqueous phase in which the polymerization catalyst is dissolved, and the aromatic dicarboxylic acid component are dissolved. A polyarylate can be obtained by mixing the organic phase and conducting an interfacial polycondensation reaction with stirring.

  In this case, the polymerization catalyst is preferably a quaternary ammonium salt. Specifically, tri-n-butylbenzylammonium chloride, tri-n-butylbenzylammonium bromide, tri-n-butylbenzylammonium hydroxide, Examples thereof include n-butylbenzylammonium hydrogen sulfate, tetra n-butylammonium chloride, tetra n-butylammonium bromide, tetra n-butylammonium hydroxide, and tetra n-butylammonium hydrogen sulfate.

  Examples of the alkali used in the aqueous phase include sodium hydroxide and potassium hydroxide.

  As the solvent used for the organic phase, a solvent which is incompatible with water and dissolves the polyarylate resin to be produced is used. Specifically, methylene chloride, 1,2-dichloroethane, chloroform, tetrachloride Carbon, chlorobenzene, 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene and other chlorinated solvents, toluene, benzene, xylene, etc. Aromatic hydrocarbons can be mentioned.

  In addition, in order to adjust the molecular weight of the polyarylate of the present invention, the compound represented by the general formula (2) is used as a terminal terminator, but other terminal terminators are used in combination as long as such performance is maintained. It is also possible to do. Examples include monovalent phenols such as phenol, cresol, p-tert-butylphenol, methyl 4-hydroxybenzoate, n-butyl 4-hydroxybenzoate, benzoyl chloride, hydroxybenzoic acid, acid chloride, and the like. . Even when these are used in combination, it is preferable to use less than 50 mol% of the compound represented by the general formula (2).

  The polyarylate of the present invention preferably has a polystyrene equivalent weight average molecular weight (Mw) of 20,000 or more and less than 300,000 as measured by gel permeation chromatography (hereinafter abbreviated as “GPC”). The number average molecular weight (Mn) in terms of polystyrene is preferably from 4,000 to less than 600,000.

  Further, other components may be added as desired. For example, antioxidants, branching agents such as phloroglucin, isatin bisphenol, and trisphenol ethane, mold release agents, antistatic agents, ultraviolet absorbers, and dyes may be added in small amounts.

(4) Method for Producing Electrophotographic Photoreceptor The electrophotographic photoreceptor of the present invention is produced by forming a photosensitive layer (a charge generation layer and a charge transport layer in the case of a laminated type) on a conductive substrate. The photosensitive layer is prepared by dissolving the charge generation material or charge transport material in a suitable solvent together with a binder resin (in the case of a laminate type, a binder resin for each layer of the charge generation layer and the charge transport layer), and immersing the solution in a dip coating method or It can be formed by applying on a conductive substrate by a spray method or the like and drying.

  The solvent can be roughly classified into two types, a halogen-based organic solvent and a non-halogen-based solvent. In the polyarylate resin of the present invention, a non-halogen-based solvent can be used. Conventionally, halogen-based solvents with low flammability have been frequently used, but in recent years, the proportion of non-halogen-based solvents used is increasing from the viewpoint of safety and environmental protection. Since the polyarylate resin of the present invention is well soluble in a non-halogen solvent mainly composed of tetrahydrofuran (sometimes abbreviated as THF), it is possible to produce a photosensitive layer using a non-halogen solvent. .

  The non-halogen solvent in the present invention is mainly composed of tetrahydrofuran, and other components such as toluene, xylene and other aromatic hydrocarbons, acetone, methyl ethyl ketone, cyclohexanone, isophorone, etc. for viscosity adjustment and evaporation rate adjustment of the solution. Ketones, dioxane, ethers such as ethylene glycol diethyl ether (except THF), esters such as methyl acetate, ethyl acetate, ethyl cellosolve, alcohols such as methanol, ethanol, isopropanol, other dimethylformamide, dimethyl sulfoxide, Examples include diethylformamide. In the present invention, these solvents / poor solvents / non-solvents can be used alone or in combination of two or more in combination with THF to make non-halogen solvents. The proportion of THF in the non-halogen solvent is preferably 50% by weight or more, more preferably 60% by weight or more in the total non-halogen solvent.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
<Example 1>

  To 2.3 liters of 5 w / w% aqueous sodium hydroxide solution, 0.5 g of hydrosulfite and 1,1-bis (4-hydroxyphenyl) cyclohexane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as “BPZ”) 268 g (1 mol) is dissolved, 2.1 g of tri-n-butylbenzylammonium chloride is added as a polymerization catalyst, and 205 g of a terephthalic acid chloride / isophthalic acid chloride = 1/1 mixture (manufactured by Tokyo Chemical Industry Co., Ltd.) and Add 2.7 liters of methylene chloride solution in which 4.1 g of paradodecylphenol represented by (3) (manufactured by Yuka Schenectady Co., Ltd., hereinafter abbreviated as “PDP”) is added, and at about 20 ° C. for 2 hours An interfacial polycondensation reaction was performed. After completion of the reaction, the reaction solution was separated into an aqueous phase and an organic phase, the organic phase was neutralized with phosphoric acid, and washing with water was repeated until the conductivity of the washing solution (aqueous phase) was 10 μS / cm or less. The obtained polymer solution was dropped into warm water maintained at 60 ° C., and the solvent was removed by evaporation to obtain a white powdery precipitate. The obtained precipitate was filtered and dried at 105 ° C. for 24 hours to obtain a polymer powder.

The molecular weight obtained by GPC measurement of this polymer was Mw = 132100 and Mn = 34600. The results obtained polymer was analyzed by infrared absorption spectrum, absorption by a carbonyl group or an ester group at a position near 1750 cm ^-1, observed absorption by ether bond position near 1220 cm ^-1, polyarylate having an ester bond It was confirmed that.

<Preparation of photoreceptor sheet>
Next, a photoreceptor sheet for evaluating the obtained polyarylate was prepared.

<Preparation of coating solution for undercoat layer formation>
A polyamide resin (“Alamin CM-8000” manufactured by Toray Industries, Inc.) is stirred and mixed in a mixed solvent with a methanol / 1-butanol weight ratio of 7/3 while being heated, and a coating solution for forming an undercoat layer with a solid content concentration of 5%. Was made.

<Preparation of charge generation layer forming coating solution>
As a charge generation substance, 10 parts of Y-type oxytitanium phthalocyanine (manufactured by SENSIENT TECNOLOGY), 20 parts of tetrahydrofuran and 2 parts of water were mixed and dissolved by stirring with a roller mill. Subsequently, 5 parts of alkyl acetalized polyvinyl butyral (trade name “Denka Butyral” BX-1) manufactured by Sekisui Chemical Co., Ltd. and 300 parts of tetrahydrofuran were mixed with this micronized treatment liquid to prepare a coating solution for forming a charge generation layer. .

<Preparation of coating solution for charge transport layer formation>
100 parts of the resulting polyarylate resin (PAR) (35 parts of a compound represented by the following formula (4) as a charge transport material (manufactured by Takasago International Corporation), 8 parts of dibutylhydroxytoluene as an antioxidant, In addition, 0.05 part of silicone oil (trade name: KF96, manufactured by Shin-Etsu Silicone Co., Ltd.) as a leveling agent was dissolved in 750 parts of a tetrahydrofuran mixed solvent to prepare a coating solution for forming a charge transport layer.

  The undercoat layer forming coating solution obtained as described above was applied on an aluminum plate with a wire bar so that the film thickness after drying was about 0.5 μm, and dried at room temperature to provide an undercoat layer. Subsequently, the above-described coating solution for forming a charge generation layer was applied onto the undercoat layer with a wire bar so that the film thickness after drying was about 0.3 μm, and dried at room temperature to provide a charge generation layer.

Subsequently, the coating solution for forming a charge transport layer obtained as described above was applied onto the charge generation layer with an applicator so that the film thickness after drying was about 25 μm, and dried at 125 ° C. for 20 minutes. Thus, a photoreceptor sheet was produced.

An eraser (PE-01A manufactured by Dragonfly Pencil Co., Ltd.) was placed on the prepared photoreceptor sheet, and a 100 g weight was placed on the eraser, and allowed to stand at 50 ° C. for 24 hours. After removing 100 g weight and eraser, the presence or absence of cracks on the surface of the photoreceptor sheet was observed with a microscope. Evaluation was made based on the number of cracks having a diameter of 50 μm or more in 1 cm ³ .

○: No crack Δ: One or two cracks ×: Three or more cracks

Next, the charging characteristics of the photoreceptor sheet were examined with an EPA-8100 electrostatic charging test apparatus manufactured by Kawaguchi Electric Co., Ltd.
The initial potential is the initial charge amount (−V) when the DC charger is adjusted so that a 50 μA current flows.
The residual potential is a residual potential (−V) after 4 seconds after exposure (static elimination 10 Lux).
The physical property measurement results are shown in Table 1.

<Example 2>
Instead of BPZ, 2,2-bis (4-hydroxy-3-methylphenyl) propane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as “BPC”) 256 g, and instead of PDP, the following structural formula (5) The same procedure as in Example 1 was conducted except that 3.5 g of para-t-octylphenol (manufactured by DIC Corporation, hereinafter abbreviated as “PTOP”) was used, and a polyarylate having Mw = 128100 and Mn = 31900 was obtained. It was. Using the obtained polyarylate, the same photoreceptor sheet molding and performance evaluation as in Example 1 were performed.

<Example 3>
In place of BPZ, 296 g of 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as “OCZ”) and the following structural formula (6) instead of PDP A polyarylate having Mw = 126100 and Mn = 30700 was obtained in the same manner as in Example 1 except that 3.5 g of butyl paraoxybenzoate (manufactured by AIP Corporation, hereinafter abbreviated as “POBB”) was used. It was. Using the obtained polyarylate, the same photoreceptor sheet molding and performance evaluation as in Example 1 were performed.

<Example 4>
Example 1 was used except that 214 g of 1,1-bis (4-hydroxyphenyl) ethane (Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as “BPE”) and 0.6 g of POBB were used instead of BPZ. The polyarylate having Mw = 213700 and Mn = 31600 was obtained. The same photoreceptor sheet molding and performance evaluation as in Example 1 were performed.

<Example 5>
In place of BPZ, 270 g of 2,2-bis (4-hydroxyphenyl) -4-methylpentane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter abbreviated as “MIBK”) and the following structural formula (7) instead of PDP Except for using 13.9 g of paranonylphenol (Oilized Schenectady Co., Ltd., hereinafter abbreviated as “PNP”), a polyarylate having Mw = 56800 and Mn = 15500 was obtained. Obtained. Using the obtained polyarylate, the same photoreceptor sheet molding and performance evaluation as in Example 1 were performed.

<Example 6>
Instead of BPZ, 101 g of bis (4-hydroxyphenyl) ether (manufactured by DIC Corporation, hereinafter abbreviated as “DHPE”) and 4,4 ′-[1,3-phenylenebis (1-methylethylidene)] bisphenol (Mitsui 173 g of Fine Chemical Co., Ltd. (hereinafter abbreviated as “BPM”) and 0.5 g of dodecyl paraoxybenzoate represented by the following structural formula (8) instead of PDP (manufactured by API Corporation, hereinafter abbreviated as “PODB”) The polyarylate having Mw = 281500 and Mn = 36600 was obtained in the same manner as in Example 1 except that was used. Using the obtained polyarylate, the same photoreceptor sheet molding and performance evaluation as in Example 1 were performed.

<Example 7>
Instead of BPZ, 114 g of bisphenol A (manufactured by Mitsubishi Chemical Corporation, hereinafter abbreviated as “BPA”) and 1,1-bis (4-hydroxyphenyl) -1-phenylethane (manufactured by Honshu Chemical Industry Co., Ltd., hereinafter “BPAP”) ”And 145 g, and 4-hydroxybenzoic acid-2-ethylhexyl (Ueno Pharmaceutical Co., Ltd., hereinafter abbreviated as“ EHPB ”) represented by the following structural formula (9) was used instead of PDP. Otherwise, the same procedure as in Example 1 was performed to obtain a polyarylate having Mw = 171900 and Mn = 26900. Using the obtained polyarylate, the same photoreceptor sheet molding and performance evaluation as in Example 1 were performed.

<Comparative Example 1>
Example 1 except that BPA 228g and PDP were changed to 2.2 g of paratertiary butylphenol (DIC Corporation, hereinafter abbreviated as “PTBP”) represented by the following structural formula (10) instead of BPZ. In the same manner, polyarylate having Mw = 134100 and Mn = 33900 was obtained. Using the obtained polyarylate, the same photoreceptor sheet molding and performance evaluation as in Example 1 were performed.

<Comparative Example 2>
Except having changed PTOP into 8.7 g PTBP, it carried out like Example 2 and obtained polyarylate of Mw = 62400 and Mn = 16900. The obtained polyarylate was subjected to the same photoreceptor sheet molding and performance evaluation as in Example 1.

<Comparative Example 3>
Except having changed PDP into phenol (henceforth "PH") 1.3g, it carried out similarly to Example 1 and obtained the polyarylate of Mw = 135300 and Mn = 34400. Using the obtained polyarylate, the same photoreceptor sheet molding and performance evaluation as in Example 1 were performed.

In addition, the symbol of Table 1 is as follows.
ST conversion: polystyrene conversion weight average molecular weight BPZ: 1,1-bis (4-hydroxyphenyl) cyclohexane BPC: 2,2-bis (4-hydroxy-3-methylphenyl) propane OCZ: 1,1-bis (4- Hydroxy-3-methylphenyl) cyclohexane BPE: 1,1-bis (4-hydroxyphenyl) ethane MIBK: 2,2-bis (4-hydroxyphenyl) -4-methylpentane DHPE: bis (4-hydroxyphenyl) ether BPM: 4,4 ′-[1,3-phenylenebis (1-methylethylidene)] bisphenol BPA: 2,2-bis (4-hydroxyphenyl) propane BPAP: 1,1-bis (4-hydroxymethylphenyl) -1-phenylethane PDP: paradodecylphenol PTOP: para-t-o Cutylphenol POBB: butyl paraoxybenzoate PNP: paranonylphenol PODB: dodecyl paraoxybenzoate EHPB: 2-ethylhexyl 4-hydroxybenzoate PH: phenol

Claims (4)

An electrophotographic photoreceptor having a photosensitive layer on a conductive substrate,
As the binder resin of the photosensitive layer, a divalent phenol, aromatic dicarboxylic acid or acid halide, and an electrophotographic photosensitive member of the terminal blocking agent using a polyarylate resin obtained as the raw material,
The dihydric phenol is 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) ether, 4,4 ′-[1,3 -Phenylenebis (1-methylethylidene)] bisphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1- Selected from the group consisting of bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, and 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane One or more,
The aromatic dicarboxylic acid or acid halide is terephthalic acid and isophthalic acid and their acid chlorides,
An electrophotographic photosensitive member , wherein the terminal blocking agent is at least one selected from the group consisting of butyl 4-hydroxybenzoate, 2-ethylhexyl 4-hydroxybenzoate, and dodecyl 4-hydroxybenzoate . The dihydric phenol is 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane or 1,1-bis (4-hydroxyphenyl) ethane,
The electrophotographic photoreceptor according to claim 1 , wherein the end-capping agent is butyl paraoxybenzoate ( butyl 4-hydroxybenzoate) . 3. The electrophotographic photosensitive member according to claim 1, wherein a polystyrene-reduced weight average molecular weight measured by gel permeation chromatography of polyarylate is 20,000 or more and less than 300,000. 4. Photosensitive layer has a charge generation layer and a charge transport layer, the electrophotographic photosensitive member according to claim 1 to 3 in which the binder resin is used in the charge transport layer.