JP2007079555A - Electrophotographic photoreceptor, process cartridge, and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having high durability, high sensitivity and excellent potential stability during repeated use, and hardly causing decrease in the sensitivity even when light at a wavelength of 380 to 450 nm is used as exposure light. <P>SOLUTION: The electrophotographic photoreceptor comprises a conductive support, and from the support side, a charge generating layer and a charge transport layer layered in this order on the conductive support, wherein the charge transport layer contains a polyarylate resin having a specific repeating structure and a charge transport substance having a specific structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus.

  Photoconductive materials (charge generation materials and charge transport materials) used for electrophotographic photoreceptors mounted on electrophotographic apparatuses include inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide. Therefore, organic photoconductive substances have been actively developed from the viewpoint of pollution-free, high productivity, and ease of material design.

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

  An electrophotographic photoreceptor using an organic photoconductive material has the above-mentioned advantages, but does not satisfy all of the characteristics required as an electrophotographic photoreceptor at a high level. Further improvement in image quality and durability of output images is desired.

  In recent years, with regard to the improvement of image quality, in order to further increase the resolution of an output image, as exposure light (image exposure light) irradiated to an electrophotographic photosensitive member, light having a shorter wavelength than conventionally used light (for example, wavelength) Has been proposed (Patent Document 1, etc.).

  In addition, since the transmittance of the layer with respect to the exposure light affects the sensitivity of the electrophotographic photosensitive member, for example, Patent Document 2 discloses that a charge transport layer of a stacked type (normal layer type) photosensitive layer is used for exposure light with a short wavelength. A technique for forming a layer with high transmittance is disclosed. Specifically, a compound having a specific structure is used as the charge transporting substance, and a polycarbonate resin (bisphenol Z-type polycarbonate) is used as the binder resin, thereby forming a charge transporting layer having a high transmittance for exposure light having a short wavelength. is doing.

  On the other hand, with regard to the improvement of durability, polycarbonate resin has been often used as a binder resin for the surface layer of the electrophotographic photosensitive member. However, in recent years, as a binder resin for the surface layer, more than polycarbonate resin. A proposal has been made to further improve the durability of an electrophotographic photosensitive member by using a polyarylate resin having high mechanical strength (Patent Document 3, etc.). The polyarylate resin is one type of aromatic dicarboxylic acid polyester resin.

As a higher strength polyarylate resin, a polyarylate resin in which a diphenyl ether dicarboxylic acid structure is introduced into the dicarboxylic acid structure of the polyarylate resin has been proposed (Patent Document 4, etc.).
Japanese Patent Laid-Open No. 09-240051 JP 2000-105471 A Japanese Patent Laid-Open No. 10-039521 JP-A-10-020514

  However, the polyarylate resin disclosed in Patent Document 3 or the like, or the polyarylate resin disclosed in Patent Document 4 has high mechanical strength, and when this is used for the surface layer of an electrophotographic photoreceptor, Although a highly durable electrophotographic photosensitive member can be obtained, a resin capable of producing a higher-strength surface layer is desired in order to satisfy the demand for the electrophotographic photosensitive member. In particular, the polyarylate resin disclosed in Patent Document 4 is excellent in mechanical strength, but on the other hand, due to factors such as a decrease in solubility of the resin in the solvent or a decrease in compatibility with the charge transporting substance contained in the surface layer. It may cause deterioration of characteristics. Moreover, in the coating liquid containing the polyarylate resin currently disclosed by patent document 4, the stability of the coating liquid which produces an aggregate and turbidity with time after preparation of a coating liquid may be inferior. The change in the coating solution over time may be visually recognized, or it may appear as a change in sensitivity or mechanical strength of the electrophotographic photosensitive member coated with the coating solution.

  Further, when the polyarylate resin disclosed in Patent Document 3 or the like is used for the surface layer of the electrophotographic photosensitive member, it can be a highly durable electrophotographic photosensitive member, but the polyarylate resin was used. The layer has a relatively low transmittance for light having a short wavelength, particularly light having a wavelength of 380 to 450 nm, and the sensitivity of the electrophotographic photosensitive member may be lowered. In particular, when a polyarylate resin having a terephthalic acid moiety (having a dicarboxylic acid group at the para position on the phenyl group) as a constituent element in the polyarylate resin is contained in the charge transport layer, the transmittance for light of 380 to 450 nm is obtained. This decrease in the transmittance for light of 380 to 450 nm is thought to be due to charge transfer between the terephthalic acid portion of the polyarylate resin and the charge transporting material used in the photoreceptor, It is speculated that this will be noticeable with terephthalic acid having a low unoccupied orbit (LUMO orbit).

  On the other hand, the electrophotographic photosensitive member specifically disclosed in Patent Document 2 has a high transmittance for light having a short wavelength on the surface layer (charge transport layer), and has a short wavelength as exposure light for improving the image quality. Although it is difficult to reduce the sensitivity when light is used, it is sufficient in terms of durability because it uses a polycarbonate resin whose mechanical strength is inferior to that of polyarylate resin as the binder resin for the surface layer. Absent.

  An object of the present invention is an electrophotographic photosensitive member that is highly durable and that is less susceptible to lowering of sensitivity even when light having a short wavelength, particularly light having a wavelength of 380 to 450 nm, is used as exposure light, and An object of the present invention is to provide a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

  The present invention relates to an electrophotographic photosensitive member in which a charge generation layer and a charge transport layer are laminated in this order on a conductive support from the support side. The charge transport layer contains at least a repeating structural unit represented by the following formula (1): And a structural unit represented by the following formula (1) is 60 in terms of molar ratio in all the structural units of the polyarylate resin. The electrophotographic photosensitive member is characterized by being −100%.

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

In formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group, or R ³¹ and R ³² are bonded to each other. A cycloalkylidene group or a fluorenylidene group to be formed is shown. )

(In the formula (4), Ar ⁴¹ and Ar ⁴² each independently represent a substituted or unsubstituted monovalent aromatic hydrocarbon ring group, and R ^{51 to} R ⁵⁷ each independently represent a hydrogen atom, a halogen atom, An alkyl group having 1 to 4 carbon atoms, an aryl group, and an alkoxy group having 1 to 3 carbon atoms, and R ⁶¹ and R ⁶² are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group, This indicates that R ⁶¹ and R ⁶² are bonded to each other by a C 1-3 alkoxy group or a divalent group having a structure represented by the following formula (5).

In the formula (5), R ⁷¹ and R ⁷² each independently represent a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group, or a cycloalkylidene formed by combining R ⁷¹ and R ⁷² Indicates a group. )

  The present invention also provides a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

  According to the present invention, it is possible to produce a coating solution for an electrophotographic photosensitive member having excellent solution stability. In addition, an electrophotographic photosensitive member having high durability, high sensitivity, low residual potential, and excellent potential stability upon repeated use, and a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member can be provided.

  In addition, according to the present invention, an electrophotographic photosensitive member that is less susceptible to a decrease in sensitivity even when light having a short wavelength, particularly light having a wavelength of 380 to 450 nm, is used as exposure light, and the electrophotographic photosensitive member. A process cartridge and an electrophotographic apparatus can be provided.

  As described above, the electrophotographic photosensitive member of the present invention includes an electrophotographic photosensitive member in which a charge generation layer and a charge transport layer are laminated in this order on a conductive support from the support side. ) And a polyarylate resin containing a repeating structural unit represented by formula (4) and a charge transporting material represented by the following formula (4), and the structural unit represented by the following formula (1) comprises all of the polyarylate resin In the structural unit, the molar ratio is 60 to 100%.

(In Formula (1), R ^{11 to} R ²⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group, or an alkoxy group having 1 to 3 carbon atoms. X represents a single bond, oxygen An atom, a sulfur atom, or a divalent group having a structure represented by the following formula (2) is shown.

In formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group, or R ³¹ and R ³² are bonded to each other. A cycloalkylidene group or a fluorenylidene group to be formed is shown. )

(In the formula (4), Ar ⁴¹ and Ar ⁴² each independently represent a substituted or unsubstituted monovalent aromatic hydrocarbon ring group, and R ^{51 to} R ⁵⁷ each independently represent a hydrogen atom, a halogen atom, An alkyl group having 1 to 4 carbon atoms, an aryl group, and an alkoxy group having 1 to 3 carbon atoms, and R ⁶¹ and R ⁶² are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group, This indicates that R ⁶¹ and R ⁶² are bonded to each other by a C 1-3 alkoxy group or a divalent group having a structure represented by the following formula (5).

In the formula (5), R ⁷¹ and R ⁷² each independently represent a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group, or a cycloalkylidene formed by combining R ⁷¹ and R ⁷² Indicates a group. )

Examples of the alkyl group represented by R ^{11 to} R ^{28 in} the above formula (1) include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. Examples of the aryl group include a phenyl group and a naphthyl group. Among these, a methyl group, an ethyl group, a methoxy group, an ethoxy group, and a phenyl group are preferable.

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

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

Examples of the substituted or unsubstituted monovalent aromatic hydrocarbon ring group represented by Ar ⁴¹ and Ar ⁴² in the above formula (4) include a phenyl group, a naphthyl group, and a pyrenyl group. Of these, a phenyl group is preferred. When they do not have a substituent, or as a substituent, these are alkyl groups having 1 to 8 carbon atoms, alkoxy groups having 1 to 8 carbon atoms, halogen atoms, fluorine atoms. When having an alkyl group, a cyano group, a nitro group, etc., among them, when they have no substituent, or when they have a substituent, a methyl group, an ethyl group, a methoxy group, a fluorine atom, a chlorine atom, The case where it has a bromine atom and a trifluoromethyl group is preferred.

Examples of the halogen atom represented by R ^{51 to} R ⁵⁷ in the above formula (4) include a fluorine atom, a chlorine atom, and a bromine atom. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. Among these, a methyl group and an ethyl group are preferable.

Examples of the alkyl group represented by R ⁶¹ and R ⁶² in the above formula (4) include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the aryl group include a phenyl group and a naphthyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group, and among these, a methyl group and an ethyl group are preferable.

Examples of the alkyl group represented by R ⁷¹ and R ⁷² in the above formula (5) include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Among these, a methyl group and an ethyl group are preferable.

Examples of the cycloalkylidene group formed by combining R ⁷¹ and R ⁷² include a cyclopentylidene group, a cyclohexylidene group, a cycloheptylidene group, and among these, a cyclohexylidene group Is preferred.

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

  The polyarylate resin having the repeating structural formula represented by the above formula (1) used for the charge transport layer of the electrophotographic photosensitive member of the present invention is such that the repeating structural formula represented by the above formula (1) is all in the polyarylate resin. In the structural unit, the molar ratio is 60 to 100%. More preferably, it is 80% or more in terms of molar ratio in all structural units, and more preferably 90% or more in terms of molar ratio in all structural units from the viewpoint of improving mechanical strength.

  In addition, the polyarylate resin having a repeating structural formula represented by the above formula (1) used for the charge transport layer of the electrophotographic photosensitive member of the present invention includes a repeating structural formula represented by the above formula (1) and the above formula ( As a copolymer of a repeating structural unit represented by the above formula (1) different from the repeating structural formula selected in 1) or a repeating structural unit composed of another divalent carboxylic acid and a divalent organic residue Can also be used. In that case, the polymerization form may be a polymerization form such as block copolymerization or random copolymerization, and is arbitrary, but is preferably a random copolymerization form.

  Further, in the present invention, the repeating structural unit represented by the above formula (1) different from the repeating structural formula represented by the above formula (1) and the repeating structural formula selected from the above formula (1), or The description that the copolymerization ratio in terms of molar ratio of the copolymerized polyarylate resin having a repeating structural unit composed of another divalent carboxylic acid and a divalent organic residue is A: B is shown in the above formula (1). A repeating structural unit represented by the above formula (1) different from the repeating structural formula selected in the above formula (1), wherein the dicarboxylic acid ester moiety is (1-C), the bisphenol moiety is (1-B), or When the dicarboxylic acid ester moiety shown in the repeating structural unit consisting of another divalent carboxylic acid and a divalent organic residue is (3-C) and the bisphenol moiety is (3-B), Dicarboxylic acid Steal moiety (1-C) :( 3-C) is A: B in terms of molar ratio, and bisphenol moiety (1-B) :( 3-B) in terms of molar ratio is in molar ratio A: B. Is shown.

  Examples of the divalent carboxylic acid used in the above repeating structural unit composed of another divalent carboxylic acid and a divalent organic residue include aromatic diesters such as terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, and naphthalenedicarboxylic acid. Straight chain aliphatic dicarboxylic acids such as succinic acid, succinic acid, adipic acid, sebacic acid and dodecanic acid, and cyclic aliphatic divalent carboxylic acids such as cyclohexylene dicarboxylic acid. Among them, terephthalic acid, isophthalic acid, etc. Acid, adipic acid and sebacic acid are preferred. Examples of the divalent organic residue include bisphenols such as 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) and 2,2-bis (3-methyl-4-hydroxyphenyl) propane (bisphenol C), Biphenols such as 4,4′-hydroxybiphenyl are included. The structural example of the repeating structural unit which consists of another bivalent carboxylic acid and a bivalent organic residue is shown.

  The polyarylate resin having a repeating structural formula represented by the above formula (1) used for the charge transport layer of the electrophotographic photosensitive member of the present invention preferably has a weight average molecular weight of 80000 or more. Among the polyarylate resins having the repeating structural formula represented by the above formula (1), those having a weight average molecular weight of less than 80000 have low mechanical strength and are insufficient for improving the durability of the electrophotographic photosensitive member. Furthermore, it is preferable that a weight average molecular weight is 90000 or more.

  On the other hand, when the molecular weight of the polyarylate resin having the repeating structural formula represented by the above-described structural formula (1) is too large, the coating properties of the coating liquid containing this may deteriorate, so the above formula The weight average molecular weight of the polyarylate resin having the repeating structural formula represented by (1) is preferably 300,000 or less, and more preferably 200000 or less.

  The polyarylate resin having the repeating structural formula represented by the above formula (1) used in the charge transport layer of the electrophotographic photoreceptor of the present invention can be synthesized by a transesterification method between a dicarboxylic acid ester and a compound having a hydroxyl group. It can also be synthesized by a polymerization reaction of a divalent acid halide such as a dicarboxylic acid halide and a compound having a hydroxyl group such as bisphenol, but the weight average molecular weight is within the above range. For this purpose, the latter synthesis method is preferably used.

(Synthesis Example 1)
Hereinafter, as a synthesis example, a method for synthesizing a polyarylate resin in which 100% in terms of molar ratio among all the structural units in the polyarylate resin is a repeating structural unit represented by the above formula (1-2) is shown.

  The following formula (1-2-1)

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

  In addition to the acid chloride solution, the following formula (1-2-2)

2,2-bis (3-methyl-4-hydroxyphenyl) propane having a structure represented by the following formula is dissolved in a 10% aqueous sodium hydroxide solution, and tributylbenzylammonium chloride as a polymerization catalyst is added thereto and stirred: A 2,2-bis (3-methyl-4-hydroxyphenyl) propane solution was prepared.

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

  Thereafter, the polymerization reaction was terminated by addition of acetic acid, and washing with water was repeated until the aqueous phase became neutral.

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

(Synthesis Example 2)
Hereinafter, as a synthesis example, in all the structural units in the polyarylate resin, 70% in terms of molar ratio is a repeating structural unit represented by the above formula (1-2), and 30% is represented by the above formula (3-9). The synthesis method of the polyarylate resin which is a repeating unit shown by is shown.

  The following formula (1-2-1)

Diphenyl ether dicarboxylic acid chloride having a structure represented by the following formula (3-9-1):

Was mixed at a molar ratio of 7: 3 and dissolved in dichloromethane to prepare a mixed solution of diphenyl ether dicarboxylic acid chloride and terephthalic acid chloride.

  In addition to the acid chloride solution, the following formula (1-2-2)

2,2-bis (3-methyl-4-hydroxyphenyl) propane having a structure represented by the following formula (3-9-2)

Is mixed at a molar ratio of 7: 3, dissolved in a 10% aqueous sodium hydroxide solution, tributylbenzylammonium chloride as a polymerization catalyst is added and stirred, and 2,2-bis (3 -Methyl-4-hydroxyphenyl) propane and tetramethylbiphenol mixed solution was prepared.

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

  Thereafter, the polymerization reaction was terminated by the addition of acetic acid, and washing with water was repeated until the aqueous phase became neutral.

  After washing, the solution is dropped into methanol with stirring to precipitate a polymer, and this polymer is vacuum-dried. In all the structural units in the polyarylate resin, 70% is converted into the above formula (1-2). ), And a polyarylate resin having 30% of the repeating unit represented by the above formula (3-9) was obtained. The weight average molecular weight (Mw) of this polyarylate resin was 130,000.

(Synthesis Example 3)
Below, as a synthesis example, in all the structural units in the polyarylate resin, 70% in terms of molar ratio is a repeating structural unit represented by the above formula (1-2), and 30% is represented by the above formula (3-13). The synthesis method of the polyarylate resin which is a repeating unit shown by is shown.

  The following formula (1-2-1)

Diphenyl ether dicarboxylic acid chloride having a structure represented by the following formula (3-13-1)

Were mixed at a molar ratio of 7: 3 and dissolved in dichloromethane to prepare a mixed solution of diphenyl ether dicarboxylic acid chloride and isophthalic acid chloride.

  In addition to the acid chloride solution, the following formula (1-2-2)

2,2-bis (3-methyl-4-hydroxyphenyl) propane having a structure represented by the following formula is dissolved in a 10% aqueous sodium hydroxide solution, and tributylbenzylammonium chloride as a polymerization catalyst is added thereto and stirred: A 2,2-bis (3-methyl-4-hydroxyphenyl) propane solution was prepared.

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

  Thereafter, the polymerization reaction was terminated by addition of acetic acid, and washing with water was repeated until the aqueous phase became neutral.

  After washing, the solution is dropped into methanol with stirring to precipitate a polymer, and this polymer is vacuum-dried. In all the structural units in the polyarylate resin, 70% is converted into the above formula (1-2). ), And a polyarylate resin having 30% of the repeating unit represented by the above formula (3-13) was obtained. The weight average molecular weight (Mw) of this polyarylate resin was 120,000.

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

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

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

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

  In the measurement of the weight average molecular weight of the measurement target resin, the molecular weight distribution of the measurement target resin was calculated from the relationship between the logarithmic value of the calibration curve prepared by several kinds of monodisperse polystyrene standard samples and the count number. As the standard polystyrene sample for preparing a calibration curve, ten points of monodisperse polystyrene manufactured by Aldrich having molecular weights of 3500, 12000, 40000, 75000, 98000, 120,000, 240000, 500,000, 800,000 and 1800000 were used. An RI (refractive index) detector was used as the detector.

The confirmation of the copolymerization ratio of the resin which is copolymerized with the resin of the present invention is performed by a conversion method based on the peak area ratio of the hydrogen atoms constituting the resin by ¹ H-NMR measurement of the resin, which is a general technique. Confirmation of the copolymerization ratio.

The confirmation of the copolymerization ratio of the resin which is copolymerized with the resin of the present invention is performed by a conversion method based on the peak area ratio of the hydrogen atoms constituting the resin by ¹ H-NMR measurement of the resin, which is a general technique. Confirmation of the copolymerization ratio.

  Specific examples of the charge transport material represented by the above formula (4) are shown below.

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

  As described above, the electrophotographic photosensitive member of the present invention is a laminated type separated into a support and a charge generation layer containing a charge generation material provided on the support and a charge transport layer containing a charge transport material. It is a (functional separation type) and is a normal layer type photosensitive layer in which a charge generation layer and a charge transport layer are laminated in this order from the support side.

  Further, a protective layer intended to protect the photosensitive layer may be provided on the charge transport layer.

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

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

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

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

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

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

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

  The thickness of the intermediate layer is preferably 0.05 to 5 μm, and more preferably 0.3 to 1 μm.

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

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

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

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

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

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and the like can be added to the charge generation layer as necessary.

  In the electrophotographic photoreceptor of the present invention, at least the charge transporting material represented by the above formula (4) is used, but may contain other charge transporting materials shown below as long as the effects of the present invention are not impaired. Is possible. Examples thereof include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triarylmethane compounds, and the like. These charge transport materials may be used alone or in combination of two or more. When the charge transporting material represented by the above formula (4) of the present invention is mixed with another charge transporting material, the present invention is used with respect to the total amount of the charge transporting material contained in the charge transporting layer. The ratio of the charge transporting substance is preferably 30% by mass or more, and more preferably 50% by mass or more.

  For the charge transport layer, a polyarylate resin containing at least 60 to 100% in terms of molar ratio of the repeating structural formula represented by the above formula (1) in terms of the molar ratio in all the structural units of the polyarylate resin is used as the binder resin. . Other resins exemplified below can be used in combination as long as the effects of the present invention are not impaired. In that case, the repeating structural formula represented by the above formula (1) in the charge transport layer is changed to the entire polyarylate resin. In the structural unit, the proportion of the polyarylate resin contained in 60-100% in terms of molar ratio is preferably 50% by mass or more based on the total mass of the binder resin contained in the charge transport layer. Furthermore, it is preferable that it is 70 mass% or more. Examples of resins that can be used in combination include acrylic resins, acrylonitrile resins, allyl resins, alkyd resins, epoxy resins, silicone resins, phenol resins, phenoxy resins, butyral resins, polyacrylamide resins, polyacetal resins, polyamideimide resins, polyamide resins, Polyallyl ether resin, polyarylate resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polystyrene resin, polysulfone resin, polyvinyl butyral resin, polyphenylene oxide resin, polybutadiene resin, polypropylene resin, methacrylic resin, Examples include urea resin, vinyl chloride resin, and vinyl acetate resin. In particular, polyarylate resin, polycarbonate resin and the like are preferable. These can be used singly or in combination of two or more as a mixture or copolymer.

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

  The coating solution for the charge transport layer for producing the electrophotographic photoreceptor of the present invention preferably contains a cyclic ether or an acyclic ether as a solvent. Specific examples of the cyclic ether include tetrahydrofuran, tetrahydropyran, oxepane, 1,3-dioxolane, 1,4-dioxane, 1,3-dioxane, etc. Among them, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane is preferred. Specific examples of the acyclic ether include 1-propoxypropane, 2-isopropoxypropane, dimethoxymethane, dimethoxyethane, dimethoxypropane, dimethoxybutane, diethoxymethane, diethoxyethane, diethoxypropane and the like. Of these, dimethoxymethane and dimethoxyethane are preferred. The coating solution may be mixed with other solvents. The solvent in the coating solution preferably contains 30% or more of cyclic ether or acyclic ether. Examples of other solvents include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, and aromatic hydrocarbons such as toluene, xylene, and chlorobenzene.

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

  In addition, an antioxidant, an ultraviolet absorber, a plasticizer, and the like can be added to the charge transport layer as necessary. Further, a fluorine atom-containing resin or a silicone-containing resin may be contained. Moreover, you may contain the microparticles | fine-particles comprised with the said resin. Further, metal oxide fine particles and inorganic fine particles may be contained.

  Further, as described above, a protective layer may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer. The protective layer can be formed by applying a protective layer coating solution obtained by dissolving a binder resin in a solvent and drying the coating solution.

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

  When applying the coating liquid for each of the above layers, for example, a coating method such as a dip coating method (dip coating method), a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, a blade coating method, or the like should be used. Can do.

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

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

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

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

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

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

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

  FIG. 2 shows an example of a schematic configuration of a color electrophotographic apparatus (in-line system) provided with a process cartridge having the electrophotographic photosensitive member of the present invention.

  In FIG. 2, 1Y, 1M, 1C, and 1K are cylindrical electrophotographic photosensitive members (first to fourth color electrophotographic photosensitive members), and the directions of the arrows are about axes 2Y, 2M, 2C, and 2K, respectively. Are rotated at a predetermined peripheral speed.

  The surface of the first color electrophotographic photoreceptor 1Y that is rotationally driven is uniformly charged to a predetermined positive or negative potential by a first color charging means (primary charging means: charging roller or the like) 3Y, and then slits Exposure light (image exposure light) 4Y output from exposure means (not shown) such as exposure and laser beam scanning exposure is received. The exposure light 4Y is exposure light corresponding to a first color component image (for example, a yellow component image) of a target color image. Thus, a first color component electrostatic latent image (yellow component electrostatic latent image) corresponding to the first color component image of the target color image is sequentially formed on the surface of the first color electrophotographic photoreceptor 1Y.

  The transfer material conveyance member (transfer material conveyance belt) 14 stretched by the tension roller 12 has substantially the same peripheral speed as the first to fourth color electrophotographic photoreceptors 1Y, 1M, 1C, 1K in the direction of the arrow ( For example, it is rotationally driven at 97 to 103% of the peripheral speeds of the first to fourth color electrophotographic photoreceptors 1Y, 1M, 1C, and 1K. Further, the transfer material (paper or the like) P fed from the transfer material supply means 17 is electrostatically carried (adsorbed) on the transfer material transport member 14, and the electrophotographic photoreceptor 1Y for the first to fourth colors. 1M, 1C, 1K and the transfer material conveyance member (contact portion) are sequentially conveyed.

  The first color component electrostatic latent image formed on the surface of the first color electrophotographic photoreceptor 1Y is developed with the toner of the first color developing means 5Y to become a first color toner image (yellow toner image). . Next, the first color toner image formed and supported on the surface of the first color electrophotographic photosensitive member 1Y is transferred to the first color electrophotographic image by the transfer bias from the first color transfer means (transfer roller or the like) 6Y. The image is sequentially transferred onto the transfer material P carried on the transfer material conveying member 14 that passes between the photoreceptor 1Y and the first color transfer means 6Y.

  The surface of the first color electrophotographic photosensitive member 1Y after the transfer of the first color toner image is cleaned by removing the transfer residual toner by the first color cleaning means (cleaning blade or the like) 7Y, and then repeatedly. Used for first color toner image formation.

  First color electrophotographic photoreceptor 1Y, first color charging means 3Y, first color exposure means for outputting exposure light 4Y corresponding to the first color component image, first color development means 5Y and first color The transfer unit 6Y is collectively referred to as a first color image forming unit.

  Second color electrophotographic photoreceptor 1M, second color charging means 3M, second color exposure means for outputting exposure light 4M corresponding to the second color component image, second color developing means 5M, and second color A second color image forming portion having a transfer means 6M, a third color electrophotographic photosensitive member 1C, a third color charging means 3C, and a third color output device that outputs exposure light 4C corresponding to the third color component image. Third color image forming unit having exposure means, third color developing means 5C and third color transfer means 6C, fourth color electrophotographic photoreceptor 1K, fourth color charging means 3K, fourth color component The operation of the fourth color image forming unit having the fourth color exposure unit that outputs the exposure light 4K corresponding to the image, the fourth color development unit 5K, and the fourth color transfer unit 6K is the first color image. The operation is the same as that of the forming unit. The second color toner image (magenta toner image), a third color toner image (cyan toner image), a fourth color toner image (black toner image) are sequentially transferred. In this way, a synthetic toner image corresponding to the target color image is formed on the transfer material P carried on the transfer material conveying member 14.

  The transfer material P on which the synthetic toner image is formed is separated from the surface of the transfer material conveying member 14, introduced into the fixing means 8, and subjected to image fixing to be printed out of the apparatus as a color image formed product (print, copy). Be out.

  Further, the first to fourth color electrophotographic photoconductors 1Y, 1M, 1C and 1K after the transfer residual toner is removed by the first to fourth color cleaning means 7Y, 7M, 7C and 7K As shown in FIG. 3, the first to fourth color charging units 3Y, 3M, 3C, and 3K are contact charging units using a charging roller or the like. In this case, pre-exposure is not always necessary.

  Among the above-described components such as the electrophotographic photosensitive member, charging unit, developing unit, transfer unit, and cleaning unit, a plurality of components are housed in a container and integrally combined as a process cartridge. Or an electrophotographic apparatus main body such as a laser beam printer. In FIG. 3, for each image forming unit, an electrophotographic photosensitive member, a charging unit, a developing unit, and a cleaning unit are integrally supported to form a cartridge, and a guide unit (not shown) such as a rail of an electrophotographic apparatus main body is provided. The process cartridges 9Y, 9M, 9C, and 9K are detachable from the main body of the electrophotographic apparatus.

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

(Example 1-1)
An aluminum plate having a length of 150 mm and a width of 150 mm was used as a support.

  Next, an intermediate layer coating solution was prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol.

  This intermediate layer coating solution was applied onto a support with a Meyer bar and dried at 100 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.7 μm.

  Next, the following formula (CGM-1)

20 parts of an azo pigment (charge generating material) having a structure represented by the following formula and 10 parts of butyral resin (degree of butyralization: 65 mol%) are added to 400 parts of tetrahydrofuran, and the atmosphere is 23 ± 3 ° C. in a sand mill using glass beads having a diameter of 1 mm The coating solution for charge generation layers was prepared by dispersing for 20 hours.

  The charge generation layer coating solution was applied onto the intermediate layer with a Meyer bar and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.4 μm.

  Next, 8 parts of a charge transporting substance having a structure represented by the above formula (4-1) and 10 parts of a polyarylate resin (Mw: 70000) having a repeating structural unit represented by the above formula (1-1) A coating solution for a charge transport layer was prepared by dissolving in 80 parts of 1,4-dioxane.

  This charge transport layer coating solution was applied onto the charge generation layer with a Meyer bar and dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 24 μm.

  Next, evaluation will be described.

  As an evaluation apparatus, an electrostatic copying paper test apparatus EPA-8100 manufactured by Kawaguchi Electric Co., Ltd. was used.

The surface potential of the electrophotographic photosensitive member is charged to −600 V (dark portion potential) with a corona charger, and then light (exposure) is irradiated with light having wavelengths of 400 nm, 430 nm, and 450 nm with an LED, and the surface potential is − The amount of light necessary to attenuate to 300 V (bright part potential) was measured, and the half exposure sensitivity (E _1/2 ) was calculated at each wavelength.

The results are shown in Table 2. In Table 2, the sensitivity to light with a wavelength of 400 nm is E _{1/2 (400)} , the sensitivity to light with a wavelength of 430 nm is E _{1/2 (430),} and the sensitivity to light with a wavelength of 450 nm is E _{1/2 ( 450)} .

(Examples 1-2 to 1-32)
In Example 1-1, an electrophotographic photosensitive member in which the charge transport layer is a surface layer was produced in the same manner as in Example 1-1, except that the binder resin of the charge transport layer was changed as shown in Table 1. evaluated. The results are shown in Table 2.

(Example 1-33)
In Example 1-2, the charge transporting layer is a surface layer in the same manner as in Example 1-2 except that the charge transporting material represented by the above formula (4-6) is used as the charge transporting material. Photoconductors were prepared and evaluated. The results are shown in Table 2.

(Examples 1-34 to 1-37)
In Example 1-33, an electrophotographic photosensitive member having a charge transport layer as a surface layer was produced in the same manner as in Example 1-33 except that the binder resin for the charge transport layer was as shown in Table 1. evaluated. The results are shown in Table 2.

(Comparative Examples 1-1 to 1-7)
In Example 1-1, an electrophotographic photosensitive member having a charge transport layer as a surface layer was prepared in the same manner as in Example 1-1, except that the binder resin for the charge transport layer was as shown in Table 1. evaluated. The results are shown in Table 2.

  From the comparison between Examples and Comparative Examples, even when the resin of the structural unit of the present invention is used, when the resin configured within the molar ratio range of the present invention is used, image exposure in the short wavelength region is used. In this case, the characteristics are good, indicating that the photoreceptor of the present invention is suitable for an electrophotographic photoreceptor using short wavelength image exposure. In particular, an electrophotographic photosensitive member containing a conventional resin having a terephthalic acid structure as the resin structure used for the charge transporting layer is shown by comparison between Example and Comparative Example [1-5] or Comparative Example [1-7]. The comparison shows that the electrophotographic photosensitive member of the present invention has significantly improved characteristics.

FIG. 2 is a diagram illustrating an example of a contact charging type process cartridge and an electrophotographic apparatus. 1 is a diagram illustrating an example of a full-color contact charging type electrophotographic apparatus. FIG. The process cartridge shown in FIG. 2 is a system in which yellow, magenta, cyan, and black are arranged in the vertical order from the bottom in a tiedem manner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Support body 104 Photosensitive layer 1041 Charge generation layer 1042 Charge transport layer 105 Protective layer 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Cleaning means 8 Fixing means 9 Process cartridge 10 Guide means P Transfer Material 1Y First color electrophotographic photosensitive member 1M Second color electrophotographic photosensitive member 1C Third color electrophotographic photosensitive member 1K Fourth color electrophotographic photosensitive member 2Y Axis 2M Axis 2C Axis 2K Axis 3Y For first color Charging means 3M Second color charging means 3C Third color charging means 3K Fourth color charging means 4Y Exposure light 4M Exposure light 4C Exposure light 4K Exposure light 5Y First color developing means 5M Second color developing means 5C Third color developing means 5K Fourth color developing means 6Y First color transfer means 6M Second color transfer means 6C Third color transfer means 6K Fourth color transfer means 7Y First color cleaning means 7 The two-color cleaning device 7C third color cleaning means 7K for the fourth color cleaning means 9Y process cartridge 9M process cartridge 9C process cartridge 9K process cartridge 12 tension roller 14 the transfer material transport member

Claims (8)

In an electrophotographic photosensitive member in which a charge generation layer and a charge transport layer are laminated in this order on a conductive support from the support side, the polyarylate wherein the charge transport layer contains at least repeating structural units represented by the following formula (1) The resin and the charge transporting material represented by the following formula (4), and the structural unit represented by the following formula (1) is 60-100% in terms of molar ratio in all the structural units of the polyarylate resin. An electrophotographic photoreceptor, characterized in that

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

In formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group, or R ³¹ and R ³² are bonded to each other. A cycloalkylidene group or a fluorenylidene group to be formed is shown. )

(In the formula (4), Ar ⁴¹ and Ar ⁴² each independently represent a substituted or unsubstituted monovalent aromatic hydrocarbon ring group, and R ^{51 to} R ⁵⁷ each independently represent a hydrogen atom, a halogen atom, An alkyl group having 1 to 4 carbon atoms, an aryl group, and an alkoxy group having 1 to 3 carbon atoms, wherein R ⁶¹ and R ⁶² are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group, R ⁶¹ and R ⁶² are bonded to each other through a C 1-3 alkoxy group or a divalent group having a structure represented by the following formula (5).

In the formula (5), R ⁷¹ and R ⁷² each independently represent a hydrogen atom, an alkyl group, an alkoxy group, or an aryl group, or a cycloalkylidene formed by combining R ⁷¹ and R ⁷² Indicates a group. )   2. The electrophotographic photosensitive member according to claim 1, wherein the constituent unit represented by the formula (1) is 80 to 100% in terms of molar ratio in all the constituent units of the polyarylate resin.   The weight average molecular weight (Mw) of the polyarylate resin according to any one of claims 1 and 2 is 80000 ≦ Mw ≦ 300,000. Electrophotographic photoreceptor. The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein R ²¹ and R ²⁶ of the polyarylate resin according to any one of claims 1 to 3 are methyl groups.   5. The electrophotographic photosensitive member according to claim 1 and at least one means selected from the group consisting of a charging means, a developing means and a cleaning means are integrally supported and detachably attached to the main body of the electrophotographic apparatus. Process cartridge characterized by being.   An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit.   The electrophotographic apparatus according to claim 6, wherein the exposure unit is a unit for irradiating the electrophotographic photosensitive member with light having a wavelength of 380 to 450 nm as exposure light.   The electrophotographic apparatus according to claim 7, wherein the exposure unit includes a laser having an oscillation wavelength in a range of 380 to 450 nm.