JP2008069363A - Polyester resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester resin which excels in both abrasion resistance and sliding properties, and an electrophotographic photoreceptor using the polyester resin in its photosensitive layer. <P>SOLUTION: The polyester resin comprises an ester containing diphenol which is combined at an m- and p-positions with respect to each phenol by the diphenol combined with a single bond or a divalent connecting group and dicarboxylic acid having a divalent aromatic group or aliphatic group, as a repeating unit, and has a viscosity average molecular weight of 10,000-200,000, and is used as a binder resin for the photosensitive layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyester resin having a specific structure and an electrophotographic photoreceptor using the polyester resin as a binder for a photosensitive layer.

In recent years, the electrophotographic technology has been widely applied not only to the field of copying machines but also to various fields of printers because high quality images can be obtained immediately.
Photoreceptors used in electrophotographic technology (electrophotographic photoreceptors) are repeatedly used in electrophotographic processes, that is, cycles such as charging, exposure, development, transfer, cleaning, and charge removal. Deteriorate. As such deterioration, for example, strong oxidizing ozone or NOx generated from a corona charger commonly used as a charger may cause chemical damage to the photosensitive layer, or a carrier generated by image exposure ( Chemical, electrical, and optical degradation due to the fact that (current) flows in the photosensitive layer or the photosensitive layer composition is decomposed by static elimination light or external light. Another example is mechanical deterioration such as abrasion of the photosensitive layer surface, generation of scratches, and film peeling due to rubbing with a cleaning blade or a magnetic brush, contact with a developer or paper, and the like.

  In particular, the latter mechanical deterioration such as damage on the surface of the photosensitive layer tends to affect the copy image and directly impairs the image quality, which is a major factor limiting the life of the photoreceptor. ing. Therefore, in order to develop a long-life photoconductor, in addition to enhancing chemical, electrical, and optical durability, it is essential to increase the strength against a mechanical load.

  In the case of a laminated type photoreceptor, it is a charge transfer layer (hereinafter sometimes referred to as a charge transport layer) that is generally subjected to such a mechanical load. The charge transfer layer is usually composed of a binder resin and a charge transfer material (hereinafter sometimes referred to as a charge transport material), and the binder resin substantially determines the strength against a mechanical load.

However, since the amount of the charge transfer material added to the charge transfer layer is considerably large, it is not easy to select an appropriate binder resin to give the photoreceptor sufficient mechanical strength.
Conventionally, binder resins for charge transfer layers of electrophotographic photoreceptors include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride and copolymers thereof, polycarbonate, polyester, polysulfone, phenoxy, epoxy, silicone resin, and the like. Thermoplastic resins and various thermosetting resins are used.

  Among such many binder resins, the polycarbonate resin has relatively excellent performance, and various polycarbonate resins have been developed and put into practical use. For example, JP-A-50-98332 discloses bisphenol P-type polycarbonate, JP-A-59-71057 discloses bisphenol Z-type polycarbonate, JP-A-59-184251 discloses bisphenol P and bisphenol. A copolymer type polycarbonate of A and a polycarbonate copolymer containing a bis (4-hydroxyphenyl) ketone type structure are disclosed in JP-A-5-21478 as binder resins.

  However, many of the conventional organic photoreceptors including those using polycarbonate resin as a binder resin have a surface due to practical loads such as development with toner, friction with paper, and friction with a cleaning member (blade). Has the disadvantage of being worn or scratched on the surface, so it currently has limited printing performance.

  On the other hand, there is an example in which aromatic polyester is used as a binder resin in order to increase the mechanical strength of the photoreceptor. For example, Japanese Patent Laid-Open No. 56-135844 discloses a technique of an electrophotographic photoreceptor using a polyarylate (aromatic polyester) resin marketed under the trade name “U-polymer” as a binder. Among them, it is shown that the sensitivity is particularly excellent as compared with polycarbonate. Japanese Patent Application Laid-Open No. 3-6567 discloses an electrophotographic photoreceptor comprising a polyarylate (aromatic polyester) copolymer having a structure using tetramethylbisphenol F and bisphenol A as a bisphenol component. Has been.

  However, these aromatic polyesters have the drawbacks that the solubility of the photosensitive layer in the coating solvent and the stability of the solution are poor, and that when these are used as a binder for the photosensitive layer, the electrical properties are deteriorated. In particular, although the technique described in the former publication shows a slight improvement in terms of wear resistance and sensitivity, the coating solution is poorly stable, so that it is impossible to manufacture the coating or slip even if possible. The sex is poor. Further, in the technique described in the latter publication, an improvement is seen in the wear resistance in comparison with the conventional polycarbonate, but a superiority in the slipping aspect is not recognized in comparison with the polycarbonate.

  In addition, in order to increase the mechanical strength of the photoreceptor, for example, a method of providing an overcoat layer (Japanese Patent Laid-Open No. 61-72256), a method of using a binder polymer having high wear resistance (Japanese Patent Laid-Open No. 63-63). No. 148263 and Japanese Patent Laid-Open No. Hei 3-221962) have been proposed, but none of them are effective enough or have problems such as adversely affecting electrical characteristics and other characteristics. It is.

That is, none of the conventional techniques described above satisfy both of sufficient abrasion resistance (scratch resistance) and surface slipperiness of the electrophotographic photosensitive member at the same time. Therefore, a material excellent in both wear resistance and slipperiness is desired as a material for a binder resin for an electrophotographic photoreceptor.
An object of the present invention is to provide a polyester resin that solves the above-mentioned problems and is excellent in both wear resistance and slipperiness, and an electrophotographic photoreceptor using the polyester resin in a photosensitive layer.

  Therefore, as a result of detailed studies on the binder resin used in the photosensitive layer, the present inventors have found that a polyester resin produced by copolymerization or homopolymerization of a repeating unit having a specific structure has a very excellent slip property and high resistance. It was found that the coating solution had good storage stability because it was not only wearable but also highly soluble in non-halogen solvents, and the present invention was achieved.

・・・一般式（１）
（一般式（１）において、Ｒ₁〜Ｒ₈はそれぞれ独立に水素原子または置換基を表す。また、Ｘは単結合もしくは２価の連結基を、Ｙは２価の有機連結基を表す。） That is, the gist of the present invention is a polyester resin comprising a repeating unit represented by the following general formula (1) in the structural formula and having a viscosity average molecular weight of 10,000 to 200,000, and the polyester resin. The object is to provide an electrophotographic photosensitive member used as a binder resin for a photosensitive layer.

... General formula (1)
(In General Formula (1), R _{1 to} R ₈ each independently represents a hydrogen atom or a substituent. X represents a single bond or a divalent linking group, and Y represents a divalent organic linking group. )

  The polyester resin having a specific structure of the present invention can be suitably used as a binder resin for an electrophotographic photosensitive member because it exhibits excellent wear resistance and slipperiness and is excellent in solubility in an organic solvent. . Further, by using the polyester resin of the present invention as a binder resin, it is possible to obtain an electrophotographic photosensitive member that has excellent durability and can cope with high image quality.

Hereinafter, the present invention will be described in detail.
(Polyester resin)
The polyester resin of the present invention is mainly used as a binder resin for electrophotographic photoreceptors, but as other applications, sliding materials, molding materials, optical materials, transparent film materials, coating materials, antiwear agents, optical functions It can also be used for an adhesive resin, a resist material, and the like.

The polyester resin of the present invention has a repeating unit having a structure represented by the general formula (1).
R _{1 to} R ₈ in the two aromatic rings in the general formula (1) are each independently a hydrogen atom or a substituent. As the substituent, one that does not impair the properties of the target polyester resin in the present invention can be selected. Specifically, each independently, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and the like. Carbons such as alkyl groups having about 1 to 10 carbon atoms such as groups, isobutyl groups, tert-butyl groups, n-pentyl groups, n-hexyl groups, n-heptyl groups and n-octyl groups, methoxy groups and ethoxy groups. Examples thereof include an alkoxy group having a number of about 1 to 10, a halogen group such as fluorine, chlorine and bromine, and a nitro group. However, most preferably, all of R _{1 to} R ₈ are hydrogen atoms. In other words, these two aromatic rings are most preferably each an unsubstituted divalent benzene ring.

などの、アルキレン基，シクロアルキレン基を含む２価の有機連結基が挙げられる。これらの２価の連結基の中でも、−ＣＨ₂−、または

が好ましい。
一般式（１）中のＹは、２価の有機連結基であって、本発明で目的とするポリエステル樹脂の特性を損なわないものが選択できる。具体的には、例えば、１，４−フェニレン基、１，３−フェニレン基、１，２−フェニレン基、ナフチレン基、ビフェニレン基などの２価の芳香族基、−ＣＨ₂−、−（ＣＨ₂）₂−、−（ＣＨ₂）₃−、−（ＣＨ₂）₄−、−（ＣＨ₂）₅−、−（ＣＨ₂）₆−、−（ＣＨ₂）₇−、−（ＣＨ₂）₈−、−ＣＨ＝ＣＨ−などの２価の脂肪族基が挙げられる。中でも、２価の芳香族基が好ましい。具体的には、好ましいものとして１，４−フェニレン基、１，３−フェニレン基、ナフチレン基、ビフェニレン基、−ＣＨ＝ＣＨ−が、さらに好ましいものとして１，４−フェニレン基、１，３−フェニレン基が挙げられる。
最も好ましくは、一般式（１）の繰り返し単位は化学式（１）である。

・・・化学式（１）
本発明のポリエステル樹脂の粘度平均分子量は１万〜２０万であるが、好ましくは１万５千〜１０万、さらに好ましくは１万８千〜５万である。粘度平均分子量が小さすぎると、機械的強度及び耐摩耗性が低下する。また、粘度平均分子量が大きすぎると、塗布溶液の粘度が高く塗布が困難になる。 X in the general formula (1) is a single bond or a divalent linking group. As the divalent linking group, one that does not impair the properties of the target polyester resin in the present invention can be selected. Specifically, divalent element groups such as —O— and —S—, —CH ₂ —, — (CH ₂ ) ₂ —, — (CH ₂ ) ₃ —,

And a divalent organic linking group containing an alkylene group or a cycloalkylene group. Among these divalent linking groups, —CH ₂ —, or

Is preferred.
Y in the general formula (1) can be selected from divalent organic linking groups that do not impair the properties of the target polyester resin in the present invention. Specifically, for example, a divalent aromatic group such as a 1,4-phenylene group, a 1,3-phenylene group, a 1,2-phenylene group, a naphthylene group, a biphenylene group, —CH ₂ —, — (CH ₂ ) ₂ -,-(CH ₂ ) ₃ -,-(CH ₂ ) ₄ -,-(CH ₂ ) ₅ -,-(CH ₂ ) ₆ -,-(CH ₂ ) ₇ -,-(CH ₂ ) _And divalent aliphatic groups such as ₈ -and -CH = CH-. Among these, a divalent aromatic group is preferable. Specifically, 1,4-phenylene group, 1,3-phenylene group, naphthylene group, biphenylene group, and —CH═CH— are preferable, and 1,4-phenylene group and 1,3-phenylene group are more preferable. A phenylene group is mentioned.
Most preferably, the repeating unit of general formula (1) is chemical formula (1).

... Chemical formula (1)
The viscosity average molecular weight of the polyester resin of the present invention is 10,000 to 200,000, preferably 15,000 to 100,000, and more preferably 18,000 to 50,000. When the viscosity average molecular weight is too small, the mechanical strength and the wear resistance are lowered. On the other hand, if the viscosity average molecular weight is too large, the viscosity of the coating solution is high and coating becomes difficult.

Further, the content of the structural unit represented by the general formula (1) with respect to the entire polyester resin of the present invention is 1 to 100% by weight, preferably 5 to 90% by weight, more preferably 10 to 70% by weight. It is.
In the polyester resin of the present invention, the dihydric alcohol or dihydric phenol that is a constituent component other than the repeating component of the general formula (1) specifically includes hydroquinone, resorcinol, 1,3-dihydroxynaphthalene as an aromatic diol. 1,4-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, bis- (4-hydroxyphenyl) ) Methane (BPF), bis- (2-hydroxyphenyl) methane, (2-hydroxyphenyl) (4-hydroxyphenyl) methane, 1,1-bis- (4-hydroxyphenyl) ethane (BPE), 1,1 -Bis- (4-hydroxyphenyl) propane 2,2-bis- (4-hydroxyphenyl) propane (BPA), bis- (4-hydroxy-3,5-dimethylphenyl) methane (TmBPF), 2,2-bis- (4-hydroxyphenyl) butane, 2,2-bis- (4-hydroxyphenyl) pentane, 2,2-bis- (4-hydroxyphenyl) -3-methylbutane, 2,2-bis- (4-hydroxyphenyl) hexane, 2,2-bis -(4-hydroxyphenyl) -4-methylpentane, 1,1-bis- (4-hydroxyphenyl) cyclopentane, 1,1-bis- (4-hydroxyphenyl) cyclohexane (BPZ), bis- (3- Phenyl-4-hydroxyphenyl) methane, 1,1-bis- (3-phenyl-4-hydroxyphenyl) ethane, 1,1-bis- (3-phenyl) 4-hydroxyphenyl) propane, 2,2-bis- (3-phenyl-4-hydroxyphenyl) propane (BPQ), bis- (4-hydroxy-3-methylphenyl) methane (Cof), 1,1 -Bis- (4-hydroxy-3-methylphenyl) ethane (Ce), 2,2-bis- (4-hydroxy-3-methylphenyl) propane (BPC), 2,2-bis- (4-hydroxy- 3-ethylphenyl) propane, 2,2-bis- (4-hydroxy-3-isopropylphenyl) propane, 2,2-bis- (4-hydroxy-3-sec-butylphenyl) propane, 1,1-bis -(4-hydroxy-3,5-dimethylphenyl) ethane (Xe), 2,2-bis- (4-hydroxy-3,5-dimethylphenyl) propane (Tma), Bis- (4-hydroxy-3,6-dimethylphenyl) methane (Xf), 1,1-bis- (4-hydroxy-3,6-dimethylphenyl) ethane, bis- (4-hydroxyphenyl) phenylmethane, 1,1-bis- (4-hydroxyphenyl) -1-phenylethane (BPP), 1,1-bis- (4-hydroxyphenyl) -1-phenylpropane, bis- (4-hydroxyphenyl) diphenylmethane, bis -(4-hydroxyphenyl) dibenzylmethane, 4,4'-dihydroxydiphenyl ether (BPO), 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenyl sulfide, phenolphthalein, 4,4 '-[ 1,4-phenylenebis (1-methylvinylidene)] bisphenol, 4,4 ′-[1,4 Phenylene bis (1-methyl vinylidene)] can be mentioned bis [2-methylphenol]. Among these, preferred examples include bis- (4-hydroxyphenyl) methane (BPF), 1,1-bis- (4-hydroxyphenyl) ethane (BPE), and 2,2-bis- (4-hydroxyphenyl). ) Propane (BPA), bis- (4-hydroxy-3,5-dimethylphenyl) methane (TmBPF), 2,2-bis- (3-phenyl-4-hydroxyphenyl) propane (BPQ), bis- (4 -Hydroxy-3-methylphenyl) methane (Cof), 1,1-bis- (4-hydroxyphenyl) cyclohexane (BPZ), 1,1-bis- (4-hydroxy-3-methylphenyl) ethane (Ce) 2,2-bis- (4-hydroxy-3-methylphenyl) propane (BPC) bis- (4-hydroxy-3,5-dimethylphenyl) meta (Tmf), 1,1-bis- (4-hydroxy-3,5-dimethylphenyl) ethane (Xe), 2,2-bis- (4-hydroxy-3,5-dimethylphenyl) propane (Tma), Bis- (4-hydroxy-3,6-dimethylphenyl) methane (Xf), 1,1-bis- (4-hydroxyphenyl) -1-phenylethane (BPP) may be mentioned. Particularly preferred are 2,2-bis- (4-hydroxyphenyl) propane (BPA), bis- (4-hydroxy-3,5-dimethylphenyl) methane (TmBPF), 1,1-bis- (4- Hydroxyphenyl) cyclohexane (BPZ), 2,2-bis- (4-hydroxy-3-methylphenyl) propane (BPC). Aliphatic dihydroxy compounds include ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-pentanediol, pentamethylenediol, 2,4-pentanediol, 1,5-hexanediol, and hexamethylene glycol. 1,5-heptanediol, heptamethylenediol, octamethylenediol, 1,9-nonanediol, 1,10-decamethylene glycol, 1,6-cyclohexanediol, etc., preferably ethylene glycol, propylene Examples include glycol and 1,4-butanediol.

・・・一般式（２）
（一般式（２）において、Ｒ’₁〜Ｒ’₈はそれぞれ独立に水素原子または置換基を表す。また、Ｘ’は単結合もしくは２価の連結基を、Ｙ’は２価の有機連結基を表す。）
一般式（２）において、Ｒ’₁〜Ｒ’₈はそれぞれ独立に、水素原子または置換基である。置換基としては、本発明で目的とするポリエステル樹脂の特性を損なわないものが選択できるが、具体的には、一般式（１）のＲ₁〜Ｒ₈と同様に、それぞれ独立に炭素数１〜１０程度のアルキル基、炭素数１〜１０程度のアルコキシ基、ハロゲン基などが挙げられる。 In particular, the constituent component other than the repeating component of the general formula (1) in the polyester resin of the present invention is preferably a repeating unit represented by the following general formula (2).

... General formula (2)
(In General Formula (2), R ′ _{1 to} R ′ ₈ each independently represents a hydrogen atom or a substituent. X ′ represents a single bond or a divalent linking group, and Y ′ represents a divalent organic linking group. Represents a group.)
In the general formula (2), R ′ _{1 to} R ′ ₈ are each independently a hydrogen atom or a substituent. As the substituent, one that does not impair the properties of the target polyester resin in the present invention can be selected. Specifically, like R _{1 to} R _{8 in} the general formula (1), each independently has 1 carbon atom. An alkyl group having about 10 to 10 carbon atoms, an alkoxy group having about 1 to 10 carbon atoms, a halogen group, and the like.

  Further, X ′ in the general formula (2) is a single bond or a divalent linking group. As the divalent linking group, those which do not impair the properties of the target polyester resin in the present invention can be selected. Specifically, as with X in the general formula (1), —O— and —S— And a divalent organic linking group such as an alkylene group or a cycloalkylene group.

Furthermore, Y ′ in the general formula (2) can be selected from divalent organic linking groups that do not impair the properties of the polyester resin intended in the present invention. Specifically, a divalent aromatic group, a divalent aliphatic group, etc. are mentioned similarly to Y of General formula (1).
The content of components other than the repeating unit of the general formula (1) with respect to the entire polyester resin of the present invention is usually 1 to 99% by weight, preferably 10 to 95% by weight, more preferably 30 to 90%. % By weight.

  Further, the polyester resin of the present invention may be a copolymer with other resins. The copolymerization type may be any of block, graft, and multiblock copolymerization. Examples of other resin structures copolymerized here include various resins such as polysulfone, polyether, polyketone, polyamide, polysiloxane, polyimide, polystyrene, and polyolefin. The amount of the other resin, which is a copolymer component other than the polyester of the present invention, is usually 50 mol% or less, preferably 30 mol% or less, and most preferably 10 mol% or less in the entire copolymer.

  The polyester resin of the present invention can be mixed with other resins and used for electrophotographic photoreceptors and the like. Examples of other resins mixed here include vinyl polymers such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, and copolymers thereof, thermoplastic resins such as polycarbonate, polyester, polysulfone, phenoxy, epoxy, and silicon resin, and various types. And thermosetting resin. Among these, polycarbonate resin is preferable. The amount of the other resin used in combination with the polyester resin of the present invention is usually 50% by weight or less, preferably 30% by weight or less, and most preferably 10% by weight or less based on the total binder resin. Further, when the polyester resin of the present invention is used as a surface slip modifier or a flame retardant, etc., it is 50% by weight or less, preferably 20% by weight or less, most preferably 5% by weight or less based on the total resin. May be mixed with polyester or other resin not containing a polysiloxane structure.

As a method for producing the polyester resin of the present invention, a known polymerization method can be used. Specific examples include an interfacial polymerization method, a melt polymerization method, and a solution polymerization method.
For example, in the case of production of a polyester resin by the interfacial polymerization method, a halogenated solution in which one or more bifunctional phenol components or bisphenol components are dissolved in an alkaline aqueous solution and one or more aromatic dicarboxylic acid chloride components are dissolved. Mix with hydrocarbon solution. At this time, a quaternary ammonium salt or a quaternary phosphonium salt may be present as a catalyst. From the viewpoint of productivity, the polymerization temperature is usually preferably in the range of 0 to 40 ° C., and the polymerization time is preferably in the range of 2 to 12 hours. After the completion of the polymerization, the water phase and the organic phase are separated, and the polymer dissolved in the organic phase is washed and recovered by a known method to obtain the intended resin.

Examples of the alkali component used here include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide. As the usage-amount of an alkali, the range of 1.0-3 times equivalent of the phenolic hydroxyl group contained in a reaction system is preferable.
Examples of the halogenated hydrocarbon used here include dichloromethane, chloroform, 1,2-dichloroethane, trichloroethane, tetrachloroethane, dichlorobenzene and the like.

  Quaternary ammonium salts or quaternary phosphonium salts used as catalysts include tertiary alkylamines such as tributylamine and trioctylamine, such as hydrochloric acid, bromic acid, iodic acid, benzyltriethylammonium chloride, benzyltrimethylammonium chloride, Examples include benzyltributylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, trioctylmethylammonium chloride, tetrabutylphosphonium bromide, triethyloctadecylphosphonium bromide, N-laurylpyridinium chloride, laurylpicolinium chloride.

Specific examples of the bifunctional phenol component or bisphenol component include the above-mentioned aromatic diols, but one or more of these may be used in combination.
In addition, as a molecular weight regulator during polymerization, phenol, o, m, p-cresol, o, m, p-ethylphenol, o, m, p-propylphenol, o, m, p-tert-butylphenol, pentyl Alkylphenols such as phenol, hexylphenol, octylphenol, nonylphenol, monofunctional phenols such as o, m, p-phenylphenol, 2,4,6-trimethylphenol, 2,3,6-trimethylphenol, acetate chloride, Monofunctional acid halides such as butyric acid chloride, octylic acid chloride, benzoyl chloride, benzenesulfonyl chloride, benzenesulfinyl chloride, sulfinyl chloride, benzenephosphonyl chloride and their substitutes may be present.

  As a method for purifying the resin after polymerization, the resin solution is washed with an aqueous alkali solution such as sodium hydroxide or potassium hydroxide, an acid aqueous solution such as hydrochloric acid, nitric acid or phosphoric acid, water, etc., and then left to stand and centrifuged. It may be separated by, for example. Also, by the method of precipitating the generated resin solution in a solvent in which the resin is insoluble, the method of dispersing the resin solution in warm water and distilling off the solvent, or the method of circulating the resin solution through an adsorption column, etc. The resin may be purified.

  The purified resin may be precipitated in water, alcohol or other organic solvent in which the resin is insoluble, the solvent of the resin is distilled off in warm water or in a dispersion medium in which the resin is insoluble, or the solvent is removed by heating, decompression, etc. It can be taken out by distilling it off. When the produced resin is in the form of a slurry, it can be taken out as a solid by a centrifuge, a filter or the like.

  The obtained resin is usually dried at a temperature not higher than the decomposition temperature of the resin, but is preferably dried under reduced pressure within the range of 20 ° C. to the melting temperature of the resin. The drying is performed until the purity of impurities such as the residual solvent becomes a certain level or lower. Usually, the drying is performed until the residual solvent becomes 1000 ppm or less, preferably 300 ppm or less, more preferably 100 ppm or less.

(Electrophotographic photoreceptor)
Next, the electrophotographic photoreceptor, which is an application of the polyester resin of the present invention, will be described in detail below.
The electrophotographic photosensitive member using the resin of the present invention usually has a photosensitive layer on a conductive support. Examples of the conductive support include aluminum, aluminum alloy, stainless steel, copper, nickel and the like. Metal materials, resin materials that are made conductive by adding conductive powders such as metal, carbon, and tin oxide, and conductive materials such as aluminum, nickel, and ITO (indium tin oxide alloy) on the surface Vapor deposited or coated resin, glass, paper, etc. are mainly used. As a form, a drum shape, a sheet shape, a belt shape or the like is used. A conductive material having an appropriate resistance value may be coated on a conductive support made of a metal material in order to control conductivity and surface properties and to cover defects.

When a metal material such as an aluminum alloy is used as the conductive support, it may be used after being subjected to anodizing treatment, chemical conversion coating treatment, or the like. When the anodizing treatment is performed, it is desirable to perform a sealing treatment by a known method.
The surface of the support may be smooth, or may be roughened by using a special cutting method or performing a polishing treatment. Further, it may be roughened by mixing particles having an appropriate particle diameter with the material constituting the support.

An undercoat layer may be provided between the conductive support and the photosensitive layer in order to improve adhesion and blocking properties.
As the undercoat layer, a resin, a resin in which particles such as a metal oxide are dispersed, and the like are used.
Examples of the metal oxide particles used for the undercoat layer include metal oxide particles containing one kind of metal element such as titanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zinc oxide, iron oxide, calcium titanate, and titanium. Examples thereof include metal oxide particles containing a plurality of metal elements such as strontium acid and barium titanate. Only one type of particles may be used, or a plurality of types of particles may be mixed and used. Among these metal oxide particles, titanium oxide and aluminum oxide are preferable, and titanium oxide is particularly preferable. The surface of the titanium oxide particles may be treated with an inorganic material such as tin oxide, aluminum oxide, antimony oxide, zirconium oxide, or silicon oxide, or an organic material such as stearic acid, polyol, or silicon. As the crystal form of the titanium oxide particles, any of rutile, anatase, brookite and amorphous can be used. A thing of a several crystalline state may be contained.

In addition, various particle sizes of the metal oxide particles can be used. Among these, from the viewpoint of characteristics and liquid stability, the average primary particle size is preferably 10 to 100 nm, and particularly preferably 10 to 25 nm. is there.
The undercoat layer is preferably formed in a form in which metal oxide particles are dispersed in a binder resin. The binder resin used in the undercoat layer may be phenoxy, epoxy, polyvinyl pyrrolidone, polyvinyl alcohol, casein, polyacrylic acid, celluloses, gelatin, starch, polyurethane, polyimide, polyamide, etc. alone or cured with a curing agent. Among them, alcohol-soluble copolymerized polyamides, modified polyamides and the like are preferable because they exhibit good dispersibility and coating properties.

The addition ratio of the inorganic particles to the binder resin can be arbitrarily selected, but it is preferably used in the range of 10 to 500% by weight from the viewpoint of the stability and applicability of the dispersion.
The thickness of the undercoat layer can be arbitrarily selected, but is preferably from 0.1 to 20 μm from the viewpoint of photoreceptor characteristics and applicability. Moreover, you may add a well-known antioxidant etc. to an undercoat layer.

As a specific configuration of the photosensitive layer of the electrophotographic photoreceptor,
A laminate type photoreceptor in which a charge generation layer mainly composed of a charge generation material, a charge transport material and a charge transport layer mainly composed of a binder resin are laminated in this order on a conductive support.
A reverse two-layer type photoreceptor in which a charge transport layer mainly composed of a charge transport material and a binder resin and a charge generation layer composed mainly of a charge generation material are laminated in this order on a conductive support.
A single layer type (dispersion type) photoreceptor in which a layer containing a charge transport material and a binder resin is laminated on a conductive support, and the charge generation material is dispersed in the layer.
Etc. are examples of basic configurations.

  In the case of a multilayer photoreceptor, examples of charge generation materials used in the charge generation layer include selenium and its alloys, cadmium sulfide, other inorganic optical materials, phthalocyanine pigments, azo pigments, quinacridone pigments, indigo pigments, and perylene. Various photoconductive materials such as organic pigments such as pigments, polycyclic quinone pigments, anthanthrone pigments, and benzimidazole pigments can be used, and organic pigments, phthalocyanine pigments, and azo pigments are particularly preferable.

Among them, metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium and other metals or oxides thereof, phthalocyanines coordinated with chloride, monoazo, bisazo, trisazo, polyazos and other azo pigments preferable.
When a phthalocyanine compound is used as the charge generating material of the electrophotographic photosensitive member, specifically, a metal such as metal-free phthalocyanine, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, germanium, or an oxide thereof, halogen Coordinated phthalocyanines such as compounds are used. Examples of the ligand to a metal atom having 3 or more valences include a hydroxyl group and an alkoxy group in addition to the oxygen atom and chlorine atom shown above. Particularly preferred are X-type, τ-type metal-free phthalocyanine, α-type, β-type, Y-type titanyl phthalocyanine, vanadyl phthalocyanine, chloroindium phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, and the like. Of the crystal forms of titanyl phthalocyanine mentioned here, α type and β type are described in W.C. It is shown as a phase II and a phase I by Heller et al. (Zeit. Kristallogr. 159 (1982) 173), respectively, and the β type is known as a stable type. The Y type most preferably used is a crystal type characterized in that a diffraction angle 2θ ± 0.2 ° shows a clear peak at 27.3 ° in powder X-ray diffraction using CuKα rays. As the phthalocyanine compound, only a single compound may be used, or several mixed states may be used. As the mixed state that can be placed in the phthalocyanine compound or crystal state here, the respective constituent elements may be mixed and used later, or the mixed state may be used in the manufacturing and processing steps of the phthalocyanine compound such as synthesis, pigmentation, and crystallization. It may be generated. As such treatment, acid paste treatment, grinding treatment, solvent treatment and the like are known.

  These charge generating materials include, for example, polyester resin, polyvinyl acetate, polyacrylate ester, polymethacrylate ester, polycarbonate, polyvinyl acetoacetal, polyvinyl propional, polyvinyl butyral, phenoxy resin, epoxy resin, urethane resin, cellulose ester, Used in a form bound with various binder resins such as cellulose ether. In this case, the charge generation material is used in an amount of usually 20 to 2000 parts by weight, preferably 30 to 500 parts by weight, and more preferably 33 to 500 parts by weight with respect to 100 parts by weight of the binder resin.

Moreover, you may contain another organic photoconductive compound, dye pigment | dye, and an electron withdrawing compound as needed.
The thickness of the charge generation layer is usually 0.05 to 5 μm, preferably 0.1 to 2 μm, more preferably 0.15 to 0.8 μm.
The charge transport layer of the electrophotographic photoreceptor is mainly composed of a charge transport material and a binder resin. As the binder resin, the above-described polyester resin is mainly used.

  These charge transport materials include aromatic nitro compounds such as 2,4,7-trinitrofluorenone, cyano compounds such as tetracyanoquinodimethane, electron withdrawing materials such as quinones such as diphenoquinone, carbazole derivatives, indoles. Derivatives, imidazole derivatives, oxazole derivatives, pyrazole derivatives, oxadiazole derivatives, pyrazoline derivatives, thiadiazole derivatives and other heterocyclic compounds, aniline derivatives, hydrazone compounds, aromatic amine derivatives, stilbene derivatives, butadiene derivatives, enamine compounds, these compounds And an electron-donating substance such as a polymer having a group consisting of these compounds in the main chain or side chain. Among these, a carbazole derivative, a hydrazone derivative, an aromatic amine derivative, a stilbene derivative, a butadiene derivative, and a combination of these derivatives are preferable, and a plurality of aromatic amine derivatives, stilbene derivatives, and butadiene derivatives are combined. Those are particularly preferred.

These charge transport materials may be used alone or in combination. The charge transport layer is formed in such a form that these charge transport materials are bound to the binder resin. The charge transport layer may be composed of a single layer, or may be a stack of a plurality of layers having different constituent components or composition ratios.
The ratio of the binder resin and the charge transport material in the charge transport layer is usually 30 to 200 parts by weight of the charge transport material with respect to 100 parts by weight of the binder resin, preferably 40 to 150 parts by weight or less, most preferably the upper limit. 90 parts by weight is advantageous in maintaining the mechanical properties of polyarylate. The film thickness is generally 10 to 60 μm, preferably 10 to 45 μm, and more preferably 27 to 40 μm.

The charge transport layer has well-known plasticizers, antioxidants, UV absorbers, and electron withdrawing properties to improve film formability, flexibility, coatability, contamination resistance, gas resistance, and light resistance. You may contain additives, such as a compound, a leveling agent, and a sensitizer.
Examples of the electron-withdrawing compound include quinones such as chloranil, 2,3-dichloro-1,4-naphthoquinone, 1-nitroanthraquinone, 1-chloro-5-nitroanthraquinone, 2-chloroanthraquinone, and phenanthrenequinone; Aldehydes such as nitrobenzaldehyde; 9-benzoylanthracene, indandione, 3,5-dinitrobenzophenone, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 3,3 ′, 5 , 5′-tetranitrobenzophenone and other ketones; acid anhydrides such as phthalic anhydride and 4-chloronaphthalic anhydride; tetracyanoethylene, terephthalalmalononitrile, 9-anthrylmethylidenemalononitrile, 4-nitroben Zalmalononitrile, 4- (p-nitrobenzoy Cyano compounds such as oxy) benzalmalononitrile; 3-benzalphthalide, 3- (α-cyano-p-nitrobenzal) phthalide, 3- (α-cyano-p-nitrobenzal) -4,5,6,7-tetrachloro Examples thereof include electron-withdrawing compounds such as phthalides such as phthalide.

Examples of the antioxidant include hindered phenol compounds and hindered amine compounds.
Examples of dye pigments optionally added to the photosensitive layer of the electrophotographic photoreceptor include triphenylmethane dyes such as methyl violet, brilliant green, and crystal violet, thiazine dyes such as methylene blue, quinone dyes such as quinizarin, cyanine dyes, and bililium. Salt, thiabililium salt, benzobililium salt and the like.

  The photosensitive layer of the electrophotographic photosensitive member is dissolved in a suitable solvent together with a binder resin containing a polyarylate resin in accordance with a conventional method, and if necessary, an appropriate charge generating material, sensitizing dye, electron aspiration. It is produced by forming a photosensitive layer by applying a coating solution obtained by adding a known compound such as a conductive compound, another charge transporting material, or a plasticizer or a pigment to a conductive support and drying it. be able to. In the case of a photosensitive layer comprising two layers of a charge generation layer and a charge transport layer, the charge generation layer is formed on the charge transport layer obtained by applying the coating solution on the charge generation layer or by applying the coating solution. Can be produced.

  Solvents for preparing the coating solution include ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; N, N-dimethylformamide, acetonitrile, N- Examples include aprotic polar solvents such as methyl pyrrolidone and dimethyl sulfoxide; esters such as ethyl acetate, methyl formate and methyl cellosolve acetate; and solvents that dissolve amine compounds such as chlorinated hydrocarbons such as dichloroethane and chloroform. Of course, it is necessary to select one that dissolves the binder.

  In addition, the photosensitive layer of the electrophotographic photosensitive member may contain a known plasticizer in order to improve the film forming property, flexibility, and mechanical strength. For this purpose, examples of the plasticizer added to the coating solution include aromatic compounds such as phthalic acid esters, phosphoric acid esters, epoxy compounds, chlorinated paraffins, chlorinated fatty acid esters, and methylnaphthalene. The coating liquid in the case of using an arylamine compound as the charge transport material in the charge transport layer may be of the above composition, but the photoconductive particles, dye pigments, electron withdrawing compounds, etc. may be excluded or a small amount may be added. . In this case, the charge generation layer is obtained by dissolving and dispersing in a solvent such as a binder polymer, another organic photoconductive substance, a dye pigment, or an electron-withdrawing compound, if necessary, in addition to the photoconductive particles. Examples thereof include a thin layer obtained by coating and drying the coating solution, or a layer obtained by forming the photoconductive particles by means such as vapor deposition.

A protective layer may be provided on the photosensitive layer for the purpose of preventing the photosensitive layer from being worn out or preventing or reducing the deterioration of the photosensitive layer due to a discharge product generated from a charger or the like.
Further, for the purpose of reducing frictional resistance and wear on the surface of the photoreceptor, the surface layer may contain a fluorine-based resin, a silicon resin, or the like. Moreover, the particle | grains which consist of these resin, and the particle | grains of an inorganic compound may be included.

Furthermore, it is needless to say that layers for improving electrical characteristics and mechanical characteristics such as an intermediate layer such as a barrier layer, an adhesive layer and a blocking layer, and a transparent insulating layer may be provided as necessary.
Examples of the photosensitive layer coating method include spray coating, spiral coating, ring coating, and dip coating.

  Spray coating methods include air spray, airless spray, electrostatic air spray, electrostatic airless spray, rotary atomizing electrostatic spray, hot spray, and hot airless spray. Considering the degree of conversion, adhesion efficiency, etc., in the rotary atomizing electrostatic spray, the conveying method disclosed in the republished Japanese Patent Publication No. 1-805198, that is, the cylindrical workpiece is rotated while the axial direction is spaced. By continuously transporting the electrophotographic photosensitive member, an electrophotographic photosensitive member excellent in film thickness uniformity can be obtained with a comprehensively high adhesion efficiency.

  Examples of the spiral coating method include a method using a liquid injection coating machine or a curtain coating machine disclosed in Japanese Patent Laid-Open No. 52-119651, and paint from a minute opening disclosed in Japanese Patent Laid-Open No. 1-2231966. There are a method of continuously flying in a streak shape, a method using a multi-nozzle body disclosed in JP-A-3-193161, and the like.

Hereinafter, the dip coating method will be described.
Using a charge transport material (preferably the above-mentioned compound), polyarylate resin, solvent, etc., a charge transport layer having a total solid concentration of usually 25 to 40% and a viscosity of usually 50 to 300 centipoise, preferably 100 to 200 centipoise Adjust the coating solution for forming. Here, the viscosity of the coating solution is substantially determined by the type and molecular weight of the binder polymer, but if the molecular weight is too low, the mechanical strength of the polymer itself is reduced, so that the binder has a molecular weight that does not impair this. It is preferred to use a polymer. A charge transport layer is formed by a dip coating method using the coating solution thus adjusted.

  Thereafter, the coating film is dried, and the drying temperature time may be adjusted so that necessary and sufficient drying is performed. The drying temperature is usually in the range of 100 to 250 ° C, preferably 110 to 170 ° C, more preferably 120 to 140 ° C. As a drying method, a hot air dryer, a steam dryer, an infrared dryer, a far infrared dryer, or the like can be used.

  The electrophotographic photoreceptor thus obtained has high sensitivity, low residual potential, high chargeability, small fluctuation due to repetition, and particularly good charging stability that affects image density. Therefore, it can be used as a highly durable photoconductor. Further, since the sensitivity in the region of 750 to 850 nm is high, it is particularly suitable for a photoreceptor for a semiconductor laser printer.

  An electrophotographic apparatus such as a copying machine or a printer using the electrophotographic photosensitive member of the present invention includes at least charging, exposure, development, and transfer processes, and any process that is usually used is used for any of the processes. It doesn't matter. Specifically, as a charging method (charger), for example, any of ordinary methods such as corotron or scorotron charging using corona discharge, contact charging with a conductive roller, brush, film, or the like is used. Also good. Among these, in the charging method using corona discharge, scorotron charging is often used to keep the dark portion potential constant. As a developing method, a general method is used in which development is performed by bringing a magnetic or non-magnetic one-component developer or two-component developer into contact or non-contact. The transfer method may be any of a method using corona discharge, a method using a transfer roller or a transfer belt, and the like. As a transfer method, the transfer may be performed directly on paper, an OHP film, or the like, or after being transferred to an intermediate transfer body (belt shape or drum shape), the image may be transferred onto paper or an OHP film. .

Usually, after the transfer, a fixing process for fixing the developer onto paper or the like is used, and as the fixing means, commonly used thermal fixing, pressure fixing, or the like can be used.
In addition to these processes, processes such as normally used cleaning and static elimination may be provided.

Specific embodiments of the present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist.
Example 1
[Production of polyester resin (A)]
Sodium hydroxide (5.21 g) and H ₂ O (400 ml) were weighed in a 1 L beaker and stirred and dissolved while bubbling nitrogen. There p-tert-butylphenol (0.2179 g), benzyltriethylammonium chloride (0.0639 g), 2,2-bis- (4-hydroxyphenyl) propane [BPA] (5.72 g) and 3- [1- (4-Hydroxyphenyl) -1-methylethyl] phenol [3,4′-BPA] (5.72 g) was added and stirred in this order, and the aqueous alkaline solution was transferred to a 2 L reaction vessel.

Separately, isophthalic acid [IPA] chloride (10.37 g) was dissolved in dichloromethane (200 ml) and transferred into a dropping funnel.
While maintaining the external temperature of the polymerization tank at 20 ° C. and stirring the alkaline aqueous solution in the reaction tank, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 3 hours, acetic acid (1.72 ml), dichloromethane (160 ml) and water (80 ml) were added and stirred for 30 minutes. Then, stirring was stopped and the organic layer was separated. The organic layer was washed with 0.1N aqueous sodium hydroxide solution (307 ml), then washed twice with 0.1N hydrochloric acid (307 ml), and further washed with H ₂ O (307 ml). Was performed twice.

ａ／ｂ＝５／５
・・・ポリエステル樹脂（Ａ） The washed organic layer was diluted with 360 ml of methylene chloride, poured into methanol (1800 ml), and the resulting precipitate was taken out by filtration and dried to obtain the desired polyester resin (A). The viscosity average molecular weight of the obtained polyester resin (A) was about 19,500. The structural formula of the obtained polyester resin (A) is shown below.

a / b = 5/5
... Polyester resin (A)

[Measurement of viscosity average molecular weight]
The polyester resin was dissolved in dichloromethane to prepare a solution having a concentration C of 6.00 g / L. The flow time t of the sample solution was measured in a constant temperature water bath set at 20.0 ° C. using an Ubbelohde capillary viscometer with a flow time t ₀ of the solvent (dichloromethane) of 136.16 seconds. The viscosity average molecular weight Mv was calculated according to the following formula.
a = 0.438 × η _sp +1 η _sp = t / t ₀ −1
b = 100 × η _sp / C C = 6.00 (g / L)
η = b / a
Mv = 3207 × η ^1.205

・・・β型オキシチタニウムフタロシアニン［１］
また、ポリビニルブチラール（電気化学工業（株）製、商品名デンカブチラール＃６０００Ｃ）の５％ １，２−ジメトキシエタン溶液１００部及びフェノキシ樹脂（ユニオンカーバイド社製、商品名ＰＫＨＨ）の５％ １，２−ジメトキシエタン溶液１００部を混合してバインダー溶液を作製した。 [Manufacture of photoconductor]
(Manufacture of charge generation layer)
10 parts by weight of β-type oxytitanium phthalocyanine [1] having the following structure was added to 150 parts by weight of 4-methoxy-4-methylpentanone-2 and pulverized and dispersed in a sand grind mill.

... β-type oxytitanium phthalocyanine [1]
Moreover, 5% of 5% 1,2-dimethoxyethane solution of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name Denkabutyral # 6000C) and 5% of phenoxy resin (trade name PKHH, manufactured by Union Carbide) 1, A binder solution was prepared by mixing 100 parts of a 2-dimethoxyethane solution.

100 parts by weight of the binder solution and an appropriate amount of 1,2-dimethoxyethane were added to 160 parts by weight of the previously prepared pigment dispersion to finally prepare a dispersion having a solid content concentration of 4.0%.
The dispersion thus obtained was applied onto a polyethylene terephthalate film having aluminum deposited on the surface so as to have a film thickness of 0.4 μm to provide a charge generation layer.

・・・電荷輸送材料［１］
およびポリエステル樹脂（Ａ）１００部、およびレベリング剤としてシリコーンオイル０．０３部をトルエン／テトラヒドロフラン（重量比２／８）の混合溶媒に溶解させた液を塗布し、１２５℃で２０分間乾燥し、乾燥後の膜厚が２０μｍとなるように電荷輸送層を設けた。このときポリエステル樹脂の溶解性は良好であった。こうして得られた感光体で以下の評価を行なった。 (Manufacture of charge transport layer)
Next, on this film, 60 parts of the charge transport material [1] shown below,

... Charge transport materials [1]
And 100 parts of polyester resin (A) and 0.03 part of silicone oil as a leveling agent were applied in a mixed solvent of toluene / tetrahydrofuran (weight ratio 2/8) and dried at 125 ° C. for 20 minutes. The charge transport layer was provided so that the film thickness after drying was 20 μm. At this time, the solubility of the polyester resin was good. The following evaluation was performed on the photoreceptor thus obtained.

[Friction test]
The surface of the photosensitive member prepared above is uniformly loaded with 0.1 mg / cm ² and contacted with urethane rubber made of the same material as the cleaning blade, and used at an angle of 45 degrees. The dynamic friction coefficient at the 100th time when the urethane rubber was moved 100 times with a load of 200 g, a speed of 5 mm / sec and a stroke of 20 mm was measured with a fully automatic friction and wear tester DFPM-SS manufactured by Kyowa Interface Chemical Co., Ltd. The results are shown in Table 1 below.

[Abrasion test]
The photoreceptor film was cut into a circle having a diameter of 10 cm, and the wear was evaluated by a Taber abrasion tester (manufactured by Toyo Seiki Co., Ltd.). The test conditions were as follows: the wear amount after 1000 rotations without load (self-weight of the wear wheel) using a wear wheel CS-10F in an atmosphere of 23 ° C. and 50% RH, and comparing the weight before and after the test. It was measured. The results are shown in Table 1 below.

Example 2
[Production of polyester resin (B)]
Sodium hydroxide (7.82 g) and H ₂ O (600 ml) were weighed in a 1 L beaker, and stirred and dissolved while bubbling nitrogen. To this, p-tert-butylphenol (0.3269 g), benzyltriethylammonium chloride (0.0959 g), 2,2-bis- (4-hydroxyphenyl) propane [BPA] (8.58 g) and 3- [1- (4-Hydroxyphenyl) -1-methylethyl] phenol [3,4′-BPA] (8.58 g) was added and stirred in this order, and the aqueous alkaline solution was transferred to a 2 L reaction vessel.

Separately, terephthalic acid [TPA] chloride (15.56 g) was dissolved in dichloromethane (300 ml) and transferred into a dropping funnel.
While maintaining the external temperature of the polymerization tank at 20 ° C. and stirring the alkaline aqueous solution in the reaction tank, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 3 hours, acetic acid (2.58 ml), dichloromethane (240 ml) and water (120 ml) were added and stirred for 30 minutes. Then, stirring was stopped and the organic layer was separated. This organic layer was washed with 0.1N aqueous sodium hydroxide solution (460 ml), then washed twice with 0.1N hydrochloric acid (460 ml), and further washed twice with H ₂ O (460 ml). I did it.

ａ／ｂ＝５／５
・・・ポリエステル樹脂（Ｂ） The washed organic layer was diluted with 540 ml of methylene chloride, poured into methanol (2700 ml), and the resulting precipitate was removed by filtration and dried to obtain the desired polyester resin (A). The viscosity average molecular weight of the obtained polyester resin (B) was 30,800. The structural formula of the obtained polyester resin (B) is shown below.

a / b = 5/5
... Polyester resin (B)

[Testing and Evaluation for Photoconductor Using Polyester Resin (B)]
A photoconductor was produced in the same manner as in Example 1 using the polyester resin (B). At this time, the solubility of the polyester resin was good. The obtained photoreceptor was subjected to a friction test, a wear test, and an evaluation of electrical characteristics under the same conditions as in Example 1. The results are shown in Table 1 below.

Comparative example 1
[Production of polyester resin (C)]
Sodium hydroxide (5.84 g) and H ₂ O (400 ml) were weighed in a 1 L beaker and stirred and dissolved while bubbling nitrogen. To this was added p-tert-butylphenol (0.2179 g), benzyltriethylammonium chloride (0.0639 g), 2,2-bis- (4-hydroxyphenyl) propane [BPA] (12.83 g) in this order and stirred. Thereafter, this alkaline aqueous solution was transferred to a 2 L reaction vessel.

Separately, terephthalic acid [TPA] chloride (10.37 g) was dissolved in dichloromethane (200 ml) and transferred into a dropping funnel.
While maintaining the external temperature of the polymerization tank at 20 ° C. and stirring the alkaline aqueous solution in the reaction tank, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 3 hours, acetic acid (2.62 ml), dichloromethane (100 ml) and water (50 ml) were added and stirred for 30 minutes. Then, stirring was stopped and the organic layer was separated. This organic layer was washed with 0.1N aqueous sodium hydroxide solution (450 ml), then washed twice with 0.1N hydrochloric acid (450 ml), and further washed twice with H ₂ O (450 ml). I did it.

・・・ポリエステル樹脂（Ｃ） The washed organic layer was diluted with 540 ml of methylene chloride, poured into methanol (2700 ml), and the resulting precipitate was filtered off and dried to obtain the desired polyester resin (C). The obtained polyester resin (C) became insoluble in methylene chloride, and the viscosity could not be measured. The structural formula of the obtained polyester resin (C) is shown below.

... Polyester resin (C)

[Evaluation of polyester resin (C)]
The polyester resin (C) was insoluble in a THF / toluene (8/2 weight ratio) mixed solvent.
Comparative example 2
[Production of polyester resin (D)]
Sodium hydroxide (2.15 g) and H ₂ O (200 ml) were weighed in a 1 L beaker and stirred and dissolved while bubbling nitrogen. To this, p-tert-butylphenol (0.089 g), benzyltriethylammonium chloride (0.0264 g), 2,2-bis- (4-hydroxyphenyl) propane [BPA] (2.36 g) and 3- [1- (4-Hydroxyphenyl) -1-methylethyl] phenol [3,4′-BPA] (2.36 g) was added and stirred in this order, and the aqueous alkaline solution was transferred to a 2 L reaction vessel.
Separately, 4,4′-biphenyldicarboxylic acid [Bp] chloride (5.88 g) was dissolved in dichloromethane (100 ml) and transferred into a dropping funnel.

While maintaining the external temperature of the polymerization tank at 20 ° C. and stirring the alkaline aqueous solution in the reaction tank, the dichloromethane solution was dropped from the dropping funnel over 1 hour. After further stirring for 3 hours, acetic acid (0.71 ml), dichloromethane (80 ml) and water (40 ml) were added and stirred for 30 minutes. Then, stirring was stopped and the organic layer was separated. This organic layer was washed with 0.1N aqueous sodium hydroxide solution (153 ml), then washed twice with 0.1N hydrochloric acid (153 ml), and further washed twice with H ₂ O (153 ml). I did it.

ａ／ｂ＝５／５
・・・ポリエステル樹脂（Ｄ）
［ポリエステル樹脂（Ｄ）の評価］
ポリエステル樹脂（Ｄ）はＴＨＦ／トルエン（８／２ 重量比）混合溶媒に不溶であった。 The washed organic layer was diluted by adding 180 ml of methylene chloride, poured into methanol (900 ml), and the resulting precipitate was filtered off and dried to obtain the desired polyester resin (D). The viscosity average molecular weight of the obtained polyester resin (D) was 9,200. The structural formula of the obtained polyester resin (D) is shown below.

a / b = 5/5
... Polyester resin (D)
[Evaluation of polyester resin (D)]
The polyester resin (D) was insoluble in a THF / toluene (8/2 weight ratio) mixed solvent.

ａ／ｂ＝５／５
・・・ポリカーボネート樹脂（Ｅ）
［ポリカーボネート樹脂（Ｅ）を用いた感光体に対する試験および評価］
得られた感光体の摩擦試験、摩耗試験及び電気特性の評価を実施例１と同様の方法により同条件で行なった。結果を表１に示す。

１）テトラヒドロフラン／トルエン＝８０／２０（重量比）に対する溶解性
２）粘度平均分子量
３）テーバー摩耗試験
４）動摩擦係数
以上の結果より、本発明のポリエステル樹脂は優れた耐摩耗性及び滑り性を示すとともに、電子写真感光体の電荷輸送層の塗布溶媒に対する溶解性に優れていることがわかる。 Comparative example 3
[Production of photoconductor using polycarbonate resin (E)]
Example 1 is the same as Example 1 except that 100 parts of the polyester resin in [Production of photoreceptor] (production of charge transport layer) in Example 1 is replaced with 100 parts of polycarbonate resin (E) having the structure shown below. A photoreceptor was prepared.

a / b = 5/5
... Polycarbonate resin (E)
[Test and Evaluation for Photoconductor Using Polycarbonate Resin (E)]
The obtained photoreceptor was subjected to a friction test, a wear test, and an evaluation of electrical characteristics under the same conditions as in Example 1. The results are shown in Table 1.

1) Solubility in tetrahydrofuran / toluene = 80/20 (weight ratio) 2) Viscosity average molecular weight 3) Taber abrasion test 4) Dynamic friction coefficient From the above results, the polyester resin of the present invention has excellent abrasion resistance and slipperiness. It can be seen that the solubility of the charge transport layer of the electrophotographic photosensitive member in the coating solvent is excellent.

Claims (1)

A polyester resin comprising a repeating unit represented by the following general formula (1) in a structural formula and having a viscosity average molecular weight of 10,000 to 200,000.

... General formula (1)
(In General Formula (1), R _{1 to} R ₈ each independently represents a hydrogen atom or a substituent. X represents a single bond or a divalent linking group, and Y represents a divalent organic linking group. )