JP2680599B2 - Electrophotographic photoreceptor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more specifically, it maintains excellent mechanical strength and electrophotographic characteristics for a long period of time, and is used in various electrophotographic fields. The present invention relates to an electrophotographic photosensitive member that can be preferably used.

[Conventional technology]

Recent electrophotographic photoreceptors are mainly organic electrophotographic photoreceptors of a stacked type in which a photosensitive layer has at least two layers: a charge generation layer that generates charges by exposure and a charge transport layer that transports charges. . In this laminated organic photoreceptor, a polycarbonate resin using bisphenol A as a raw material is widely used as a binder resin for the charge transport layer.

A polycarbonate resin using bisphenol A as a raw material has good compatibility with the charge transporting material, and thus has good electric properties when produced as a photoreceptor, and has relatively high mechanical strength.

However, when the charge transport layer was formed using a polycarbonate resin using bisphenol A as a raw material as the binder resin, it became clear that there were the following problems.

At the time of applying the charge transport layer during photoconductor production,
Depending on the solvent used, the coating solution may whiten (gel),
The charge transport layer may easily crystallize. There is no light decay in the crystallized portion, and the charge remains as a residual potential, which appears as a defect in image quality.

Depending on the solvent used at the time of applying the charge transport layer, a phenomenon called solvent crack of a polycarbonate resin using bisphenol A as a raw material occurs. That is, a phenomenon occurs in which the mechanical strength of the charge transport layer is significantly reduced by exposing the once applied charge transport layer to another solvent. When such a photoreceptor is used and rotated in a copying machine for a long time, a crack is generated in the charge transport layer, which appears as a crack pattern on the copy.

The charge transport layer using a polycarbonate resin made of bisphenol A has poor adhesion to the base and is easily peeled, and thus has a drawback that the printing life is eventually shortened. The term “underlayer” as used herein generally refers to a charge generation layer. However, when a charge transport layer and a charge generation layer are sequentially laminated on a conductor, such as a positively charged electrophotographic photoreceptor, the conductor is When a blocking layer or an intermediate layer is provided between a conductor and a charge transport layer or between a charge generation layer and a charge transport layer for the purpose of improving electrophotographic characteristics, those layers serve as a base. .

[Problems to be solved by the invention]

 The present invention has been made based on the above circumstances.

An object of the present invention is to solve the above-mentioned problems observed in a conventional electrophotographic photoreceptor using a polycarbonate resin made of bisphenol A as a binder resin for a charge transporting layer, and to apply the coating during the preparation of the electrophotographic photoreceptor. An object of the present invention is to provide an electrophotographic photoreceptor which is practically remarkably excellent in maintaining excellent mechanical strength and electrophotographic properties for a long period of time without causing whitening (gelling) of the solution or generating solvent cracks.

[Means for solving the problem]

The present inventor has conducted extensive studies to solve the above-mentioned problems, and as a result, an electrophotographic photoreceptor using a polycarbonate resin having a specific structure as a binder resin in a photosensitive layer, particularly a charge transport layer constituting the photosensitive layer, has been developed. However, there is no problem as described above which is observed in a conventional electrophotographic photoreceptor using a polycarbonate resin made of bisphenol A as a binder resin, and the coating liquid is whitened (gelled) during the production of the photoreceptor. Without generating solvent cracks
Moreover, they have found that they maintain excellent mechanical strength and electrophotographic characteristics over a long period of use, and have completed the present invention based on this finding.

That is, the present invention provides an electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate, wherein [Where X ¹ in the formula (I) is (However, R ¹ and R ² each independently represent a hydrogen atom, a methyl group or an ethyl group.), CH _{2 p} (where p is 2 to 1).
Represents an integer of 0. ), Single bond, -O-, -S-, -SO-
Or -SO ₂ - represents a. In addition, Y ¹ and Y ² in the formula [I]
Each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and s and t each independently represent an integer of 0 to 3. A polycarbonate comprising a repeating unit represented by the following general formula (I): Wherein R ³ and R ⁴ in the formula [II] each independently represent a halogen atom or an alkyl group having 1 to 6 carbon atoms, k and m each independently represent an integer of 0 to 4, X ² has the same meaning as X ¹ in the formula [I]. However, X ¹ and X ² may be the same as each other or may be different. ] It is an electrophotographic photoreceptor characterized by using a polycarbonate copolymer comprising a repeating unit represented by the following as a binder resin.

Said Specific examples of R ¹ and R ² therein include a hydrogen atom, a methyl group, and an ethyl group. Of these, a methyl group is particularly preferable. R ¹ and R ² may be the same group or different groups.

Said Among them, as particularly preferred, for example, And the like.

The - (- CH ₂ -) Specific examples of _p groups such as methylene group, dimethylene group, trimethylene group, tetramethylene group, hexamethylene group, octamethylene group, and the like decamethylene.

Among these, a dimethylene group and the like are particularly preferable.

Specific examples of R ³ and R ⁴ include, for example, halogen atoms such as fluorine atom, chlorine atom and bromine atom, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, 1- Examples thereof include a methylpropyl group, a 2-methylpropyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group and an isohexyl group.

Note that R ³ and R ⁴ may be the same group as each other,
It may be a different group.

Also, if the repeating unit represented by the formula [II] has a plurality of R ³ groups, these R ³ groups may be the same group or may be different, a plurality of R ⁴ When having a group, these R ⁴ groups may be the same group or may be different.

K and m each independently represent an integer of 0 to 4, and particularly preferably k = m = 0.

Specific examples of each of Y ¹ and Y ² include R ³
And various groups exemplified as R ⁴ , or phenyl group, tolyl group, xylyl group, ethylphenyl group, naphthyl group and the like.

Note that Y ¹ and Y ² may be the same group as each other,
Alternatively, they may be different.

Further, the repeating unit represented by the formula [I] has a plurality of Y ¹
When having a group, these Y ¹ groups may be the same group or may be different, and when having a plurality of Y ² groups, these Y ² groups are the same group. Or they may be different.

Although s and t each independently represent an integer of 0 to 3, it is particularly preferable that s = t = 0.

Polycarbonate comprising a repeating unit represented by the general formula [I] [hereinafter may be abbreviated as polycarbonate (I). ] Is, for example, one or more of the following general formulas (However, in the formula, X ¹ , Y ¹ , Y ² , s, and t each have the same meaning as described above.) A dihydric phenol [hereinafter,
This is sometimes abbreviated as dihydric phenol (I '). ] And a carbonate precursor such as phosgene in the presence of a suitable acid binder in a suitable solvent by polycondensation, or by a transesterification reaction of a dihydric phenol (I ′) with a bisaryl carbonate. Obtainable.

Further, a polycarbonate copolymer comprising a repeating unit represented by the general formula [I] and a repeating unit represented by the general formula [II] [hereinafter may be abbreviated as a polycarbonate copolymer (II). . ] Is one or two
One or more of two or more of the above dihydric phenols (I ′)
The following general formula over the species (Where X ² , R ³ , R ⁴ , k and m in the formula are
It has the same meaning as above. ) [Hereinafter, these may be abbreviated as dihydric phenols (II '). ] With a carbonate precursor such as phosgene in the presence of a suitable acid binder in a suitable solvent, or with dihydric phenols (I ′) and (I
It can be obtained by transesterification reaction of I ') with bisaryl carbonate.

Specific examples of the dihydric phenols (I ′) include, for example, 2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane and 3,3-bis (3-cyclohexyl-4-hydroxyphenyl) pentane. , Bis (3-cyclohexyl-4-hydroxyphenyl) sulfone, 3,
3'-dicyclohexyl-4,4'-dihydroxybiphenyl, bis (3-cyclohexyl-4-hydroxyphenyl) methane, 1,1-bis (3-cyclohexyl-4-hydroxyphenyl) ethane, 1,2-bis (3 -Cyclohexyl-4-hydroxyphenyl) ethane, 1,3-bis (3-cyclohexyl-4-hydroxyphenyl) propane, 2,2-bis (3-cyclohexyl-4-hydroxyphenyl) butane, 1,4-bis ( 3-cyclohexyl-4-hydroxyphenyl) butane, 1,8-bis (3-
Cyclohexyl-4-hydroxyphenyl) octane,
Bis (3-cyclohexyl-4-hydroxyphenyl)
Ether, bis (3-cyclohexyl-4-hydroxyphenyl) sulfide, bis (3-cyclohexyl-4)
-Hydroxyphenyl) sulfoxide, 2,2-bis (2
-Cyclohexyl-4-hydroxyphenyl) propane, 2,2-bis (3-methyl-4-hydroxy-5-cyclohexylphenyl) propane, 2,2-bis (2,3-dimethyl-4-hydroxy-5-cyclohexyl) Examples thereof include phenyl) propane, 2,2-bis (3-chloro-4-hydroxy-5-cyclohexylphenyl) propane, and 2,2-bis (3-phenyl-4-hydroxyphenyl) propane.

Among these, especially 2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane, 3,3-bis (3-cyclohexyl-4-hydroxyphenyl) pentane, bis (3-cyclohexyl-4-hydroxyphenyl) Sulfone and the like are preferably used.

Specific examples of the dihydric phenols (II ′) include, for example, bis (4-hydroxyphenyl) methane, 1,1-
Bis (4-hydroxyphenyl) ethane, 1,2-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-
Hydroxyphenyl) propane, 2,2-bis (3-methyl-4-hydroxyphenyl) butane, 2,2-bis (4
-Hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, 4,4-bis (4-hydroxyphenyl) heptane, 1,1-bis (4-hydroxyphenyl-1,1-diphenyl) methane , 1,1- (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4
-Hydroxyphenyl) -1-phenylmethane, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) cyclopentane , 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (3-methyl-4-)
Hydroxyphenyl) propane, 2- (3-methyl-4)
Hydroxyphenyl) -2- (4-hydroxyphenyl) -1-phenylethane, bis (3-methyl-4-hydroxyphenyl) sulfide, bis (3-methyl-4)
-Hydroxyphenyl) sulfone, bis (3-methyl-)
4-hydroxyphenyl) methane, 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane, 4,
4'-dihydroxybiphenyl, 2,2-bis (2-methyl-4-hydroxyphenyl) propane, 1,1-bis (2
-Butyl-4-hydroxy-5-methylphenyl) butane, 1,1-bis (2-tert-butyl-4-hydroxy-
3-methylphenyl) ethane, 1,1-bis (2-tert-
Butyl-4-hydroxy-5-methylphenyl) propane, 1,1-bis (tert-butyl-4-hydroxy-5-
Methylphenyl) butane, 1,1-bis (2-tert-butyl-4-hydroxy-5-methylphenyl) isobutane, 1,1-bis (2-tert-butyl-4-hydroxy-
5-methylphenyl) heptane, 1,1-bis (2-tert
-Butyl-4-hydroxy-5-methylphenyl) -1
-Phenylmethane, 1,1-bis (2-tert-amyl-4
-Hydroxy-5-methylphenyl) butane, bis (3
-Chloro-4-hydroxyphenyl) methane, bis (3,
5-dibromo-4-hydroxyphenyl) methane, 2,2-
Bis (3-chloro-4-hydroxyphenyl) propane, 2,2-bis (3-fluoro-4-hydroxyphenyl) propane, 2,2-bis (3-bromo-4-hydroxyphenyl) propane, 2,2 -Bis (3,5-difluoro-
4-hydroxyphenyl) propane, 2,2-bis (3,5-
Dichloro-4-hydroxyphenyl) propane, 2,2-
Bis (3,5-dibromo-4hydroxyphenyl) propane, 2,2-bis (3-bromo-4-hydroxy-5-chlorophenyl) propane, 2,2-bis (3,5-dichloro-propane
4-hydroxyphenyl) butane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) butane, 1,1-bis (3-fluoro-4-hydroxyphenyl-1-phenylethane, bis (3- Examples thereof include fluoro-4-hydroxyphenyl) ether, 3,3'-difluoro-4,4'-dihydroxybiphenyl, etc. Among these, 2,2-bis (4-hydroxyphenyl) propane and the like are particularly preferable.

As the acid binder, various types such as known ones can be used, and specifically, for example, sodium hydroxide, alkali metal hydroxides such as potassium hydroxide, organic bases such as pyridine or a mixture thereof and the like. Used.

As the solvent, for example, methylene chloride, chlorobenzene, xylene, etc. are used. Further, in order to accelerate the polycondensation reaction, a catalyst such as a tertiary amine such as triethylamine or a quaternary ammonium salt is used, and in order to adjust the degree of polymerization, such as pt-butylphenol and phenylphenol. It is desirable to add a molecular weight regulator to carry out the reaction. If desired, a small amount of an antioxidant such as sodium sulfite or hydrosulfide may be added. The reaction is usually carried out at a temperature in the range of 0 to 150 ° C, preferably 5 to 40 ° C. The reaction time depends on the reaction temperature, but is usually 0.5 minutes to 10 hours, preferably 1 minute to 2 hours. Also, during the reaction, adjust the pH of the reaction system.
It is desirable to keep at 10 or more.

On the other hand, in the latter transesterification method, the dihydric phenol compound and the bisaryl carbonate are mixed and reacted at a high temperature under reduced pressure. Reaction is usually 150
The reaction is carried out at a temperature in the range of ~ 350 ° C, preferably 200-300 ° C, and the degree of reduced pressure is finally preferably 1 mmHg or less, and phenols derived from the bisaryl carbonate produced by the transesterification reaction are taken out of the system. Distill off. The reaction time depends on the reaction temperature and the degree of pressure reduction, but is usually about 1 to 4 hours. The reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen or argon, and the reaction may be carried out by adding the above-mentioned molecular weight regulator, antioxidant and the like, if desired.

The polycarbonate (I) and the polycarbonate copolymer (II) used in the photosensitive layer of the electrophotographic photoreceptor of the present invention are each measured at 20 ° C. in a 0.5 g / dl solution using methylene chloride as a solvent. Reduced viscosity [ηs
p / c] is usually 0.25 dl / g or more, preferably in the range of 0.3 to 4.0 dl / g.

The polycarbonate (I) is one kind of the formula [I]
It may be a homopolymer composed of the repeating unit (U-1) represented by or a copolymer composed of two or more kinds of (U-1) in an arbitrary ratio. One of these may be used alone, or two or more of them may be used in combination at any ratio as a mixture or the like.

The polycarbonate copolymer (II) is a copolymer composed of one or more kinds of (U-1) and one or more kinds of repeating units (U-II) represented by the formula [II]. Polymers can be used. The ratio of the repeating units (U-1) and (U-II) in the polycarbonate copolymer (II) is not particularly limited, but (U-
I) is usually 1 mol% or more, preferably 5 mol% or more. These polycarbonate copolymers (II) may be used alone or in combination of two or more at an arbitrary ratio as a mixture or the like.

Further, the polycarbonate (I) and the polycarbonate copolymer (II) may be used in combination of two or more kinds in an arbitrary ratio.

Further, the polycarbonate (I) and / or the polycarbonate copolymer (II) may be used in combination with other known binder resins such as other known polycarbonates as a mixture or separately as long as the object of the present invention is not impaired. You can also do it.

The electrophotographic photoreceptor of the present invention has a photosensitive layer having a charge generation layer and a charge transport layer on a conductive substrate, and a charge transport layer may be laminated on the charge generation layer. A charge generation layer may be laminated on the charge transport layer. In addition, a conductive or insulating protective film may be formed on the surface layer as necessary. Further, an intermediate layer such as an adhesive layer for improving the adhesion between the layers or a blocking layer serving as a charge blocking layer may be formed.

The electrophotographic photoreceptor of the present invention comprises at least the above-mentioned polycarbonate (I) or polycarbonate copolymer (II) as a binder resin in its photosensitive layer, preferably in the charge transport layer in the photosensitive layer. It is a thing.

As the conductive base material used for the electrophotographic photoreceptor of the present invention, various materials such as known materials can be used, and specifically, for example, aluminum, brass,
Conduction treatment was performed by coating a conductive material such as aluminum, nickel, chromium, palladium, and graphite on a metal plate or metal sheet such as copper, nickel, steel, or a black sheet by vapor deposition, sputtering, or coating. A material obtained by subjecting a substrate such as glass, plastic plate, cloth, paper, or the like to a conductive treatment can be used.

The charge generation layer has at least a charge generation material, and the charge generation layer is obtained by forming a layer in which the charge generation material is bound using a binder resin on a base substrate. You can As a method for forming the charge generation layer, various methods such as a known method can be used, and usually, for example, a coating solution in which a charge generation material is dispersed or dissolved in a suitable solvent together with a binder resin is applied to a predetermined base. A method of applying the composition on a substrate to be dried and drying the composition can be suitably used.

As the charge generation material in the charge generation layer, various materials such as known materials can be used, and specifically, for example, selenium units such as amorphous selenium and trigonal selenium, and selenium such as selenium-tellurium alloy, selenide or selenium-containing compositions, such as As ₂ Se _3, zinc oxide, CdS-Se
Inorganic materials comprising Group II and Group IV elements such as, oxide-based semiconductors such as titanium oxide, various inorganic materials such as silicon-based materials such as amorphous silicon, metal or metal-free phthalocyanine, cyanine, anthracene, pyrene,
Examples include various organic materials such as perylene, pyrylium salt, thiapyrimim salt, polyvinyl carbazole, and squarium pigment.

These may be used alone or in a combination of two or more.

The binder resin in the charge generation layer is not particularly limited and various known ones can be used, and specifically, for example, polystyrene, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl. It is possible to use thermoplastic resins such as acetal, alkyd resin, acrylic resin, polyacrylonitrile, polycarbonate, polyamide, polyketone, polyacrylamide, butyral resin and polyester, and thermosetting resins such as polyurethane, epoxy resin and phenol resin. it can.

The polycarbonate (I) or the polycarbonate copolymer (II) can be used as the binder resin in the charge generation layer.

Note that these binder resins may be used alone or in a combination of two or more.

The charge transport layer can be obtained by forming a layer, which is an underlayer of the charge transport material, by binding a charge transport material to a binder resin.

As a method for forming the charge transport layer, various methods such as a known method can be used. Usually, for example, a coating solution prepared by dispersing or dissolving a charge transport material in a suitable solvent together with a binder resin, It is possible to preferably use a method of coating on a substrate which is a predetermined base and drying.

The electrophotographic photoreceptor of the present invention comprises at least the above polycarbonate (I) or a polycarbonate copolymer as a binder resin in its photosensitive layer, and the binder resin in the charge transport layer does not necessarily have the above polycarbonate (I). Although not limited to those using the polycarbonate copolymer (II), in order to fully exert the effects of the present invention, the binder resin in the charge transport layer may be the above-mentioned polycarbonate (I) or polycarbonate copolymer (II). It is desirable to use the combination (II).

As the charge-transporting material in the charge-transporting layer, any of conventionally used electron-transporting substances and hole-transporting substances can be used.

Specific examples of the electron transporting substance include, for example, chloroanyl, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9- Electron withdrawing substances such as tetrafluorenone, 2,4,7-trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-tetranitroxanthone, 2,4,9-trinitrothioxanthone There are polymerized products. These may be used alone or in a combination of two or more.

As hole transport substances, pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N
-Phenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine,
N, N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-pyrrolidino Benzaldehyde-N, N-
Diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, p
Hydrazones such as -diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1-phenyl-3- (p -Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [quinolyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [repidyl (2) ] -3- (p-Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1- [6-methoxy-pyridyl (2)]-3- (p-diethylaminostyryl) -5-
(P-diethylaminophenyl) pyrazolin, 1- [pyridyl (5)]-3- (p-diethylaminophenyl)
Pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1- [pyridyl (2)]-3- (p
-Diethylaminostyryl) -4-methyl-5- (p-
Diethylaminophenyl) pyrazolin, 1- [pyridyl (2)]-3- (α-methyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazolin, 1-phenyl-3- (p-diethylaminostyryl)- 4-methyl-5- (p-diethylaminophenyl) pyrazolin, 1-phenyl-3 (α-benzyl-p
-Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, pyrazolines such as spiropyrazolin, 2- (p-diethylaminostyryl) -δ)-
Oxazole compounds such as diethylaminobenzoxazole, 2- (p-diethylaminophenyl) -4- (p-dimethylaminophenyl) -5- (2-chlorophenyl) oxazole, 2- (p-diethylaminostyryl) -6-diethylaminobenzo A thiazole compound such as thiazole, a triarylmethane compound such as bis (4-diethylamino-2-methylphenyl) -phenylmethane, 1,1-bis (4-N, N-diethylamino-2-methylphenyl) heptane, 1,1,2,2-tetrakis (4-
Polyarylamines such as (N, N-dimethylamino-2-methylphenyl) ethane, N, N'-diphenyl-N, N'-
Bis (methylphenyl) benzidine, N, N'-diphenyl-N, N'-bis (ethylphenyl) benzidine, N, N '
-Diphenyl-N, N'-bis (propylphenyl) benzidine, N, N'-diphenyl-N, N '-(butylphenyl) benzidine, N, N'-diphenyl-N, N'-bis (isopropylphenyl) Benzidine, N, N'-diphenyl-N, N'-bis (secondary butylphenyl) benzidine,
Benzidine compounds such as N, N'-diphenyl-N, N'-bis (tertiary butylphenyl) benzidine, N, N'-diphenyl-N, N'-bischlorophenyl) benzidine, triphenylamine, poly- Examples thereof include N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin and ethylcarbazole-formaldehyde resin.

These may be used alone or in a combination of two or more.

The charge generation layer, specific examples of the solvent used in the formation of the charge transport layer, for example, benzene, toluene, xylene, aromatic solvents such as chlorobenzene, acetone, methyl ethyl ketone, ketone such as cyclohexanone, methanol, Ethanol, alcohols such as isopropanol, ethyl acetate, esters such as methyl cellosolve, carbon tetrachloride, carbon tetrabromide, halogenated hydrocarbons such as chloroform, dichloromethane and tetrachloroethane,
Examples thereof include ethers such as tetrahydrofuran and dioxane, dimethylformamide, dimethylsulfoxide, and diethylformamide.

These solvents may be used alone or in combination of two or more as a mixed solvent.

The application of each layer can be performed using various coating apparatuses such as known ones, and specifically, for example, can be performed using an applicator, a spray coater, a bar coater, a dip coater, a roll coater, a doctor blade, or the like. it can.

The electrophotographic photoreceptor of the present invention has excellent mechanical strength without whitening (gelling) of the coating solution or generation of solvent crack at the time of its production, and even when used repeatedly for a long time. Further, it is an electrophotographic photoreceptor excellent in practical use which maintains electrophotographic characteristics, and can be suitably used in various electrophotographic fields.

〔Example〕

Example 1 100 g of 2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane (0.25 mol
A solution prepared by dissolving l) in 600 ml of a 3 N aqueous potassium hydroxide solution and 250 ml of methylene chloride were added, and phosgene was blown thereinto at a rate of 340 ml / min for 30 minutes while keeping the liquid temperature at about 10 ° C by external cooling. 0.7 g of p-tert-butylphenol
And 0.5 M triethylamine aqueous solution (2 ml) were added and the mixture was stirred for 1 hour to polymerize. After the polymerization was completed, methylene chloride 50 was added to the organic phase.
0 ml was added to dilute, washed with water, diluted hydrochloric acid, and water in this order, and then poured into methanol to obtain a polycarbonate.

The concentration of this polymer is 0.5 g / dl using methylene chloride as a solvent.
Solution has a reduced viscosity [ηsp / c] of 0.60dl / g at 20 ℃.
The Tg was 128 ° C. ¹ H-NMR spectrum analysis confirmed that the polymer consisted of the following repeating units.

The following hydrazone compound is used as a charge transport material in an amount of 50 wt.
A 10 wt% solution of the above polycarbonate in tetrahydrofuran was prepared. Even when this coating solution was allowed to stand for 10 months, no cloudiness or gel generation was observed. Using aluminum as the conductive substrate, the following disazo pigments were used.
This coating solution was applied on a 0.5 μm charge generation layer by a dip coating method, dried and then provided with a 20 μm charge transport layer to produce a laminated electrophotographic photosensitive member. The charge transport layer did not crystallize during coating. Further, regarding the electrophotographic characteristics of this electrophotographic photosensitive member, such as the receptive potential immediately after corona charging, the surface potential after 5 seconds in the dark, the residual potential after light irradiation, and the half-exposure amount, bisphenol A polycarbonate was used as the binder resin. Almost same as the electrophotographic photoreceptor (Comparative Example 1). The surface hardness of this charge transport layer (pencil hardness; JIS-
K-5400) was H.

Example 2 2,2-bis (3-cyclohexyl-4) as a monomer
-Hydroxyphenyl) propane 100 g (0.25 mol) instead of 2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane 80 g (0.2 mol) and 2,2-bis (4-hydroxyphenyl) propane 11.4 g ( The same procedure as in Example 1 except that 0.05 mol) was used, and a polycarbonate copolymer ([ηsp / c] = 0.58dl / g, Tg = Tg =
132 ° C.) was obtained.

Using this copolymer, a laminated electrophotographic photosensitive member was produced in the same manner as in Example 1.

The evaluation results of the stability of the coating liquid, the amount of crystal during coating, the electrophotographic characteristics, and the surface hardness were the same as in Example 1.

Example 3 2,2-bis (3-cyclohexyl-4) as a monomer
-Hydroxyphenyl) pentane 85.6g (0.2mol) and 2,2
-Bis (3-methyl-4-hydroxyphenyl) propane 21.4 g (0.05 mol) was used in the same manner as in Example 1, except that a polycarbonate copolymer ([ηsp / c] = 0.59) having the following structural units was used. dl / g, Tg = 126 ° C.).

Using this copolymer, a laminated electrophotographic photosensitive member was produced in the same manner as in Example 1.

The stability of the coating liquid, the crystallization during coating, the electrophotographic characteristics, and the evaluation results of the surface hardness were the same as in Example 1.

Comparative Example 1 A bisphenol-based polycarbonate having the following structural unit ([ηsp / c]) was prepared in the same manner as in Example 1 except that 57 g (0.25 mol) of 2,2-bis (4-hydroxyphenyl) propane was used as a monomer. = 0.62dl / g, Tg = 148 ℃)
I got

Using this polymer, an attempt was made to produce a laminated electrophotographic photosensitive member in the same manner as in Example 1.

As a result, the coating liquid became cloudy on the second day and gel was generated. In addition, part of the charge transport layer is crystallized (whitened) during coating.
did. The surface hardness of the charge transport layer was B.

〔The invention's effect〕

According to the present invention, since a polycarbonate having a specific structure is used as a binder resin in the photosensitive layer, particularly in the electron transport layer in the photosensitive layer, the coating liquid is whitened (gelled) during the production of the electrophotographic photosensitive member. The present invention can provide an electrophotographic photoreceptor that is practically remarkably advantageous in that it does not cause solvent cracks and maintains excellent mechanical strength and electrophotographic characteristics even after repeated use for a long time. The industrial value is extremely large.

Claims (1)

(57) [Claims] 1. An electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer has the following general formula: [Where X ¹ in the formula (I) is (However, R ¹ and R ² each independently represent a hydrogen atom, a methyl group or an ethyl group.), CH _{2 p} (where p is 2 to 1).
Represents an integer of 0. ), Single bond, -O-, -S-, -SO-
Or -SO ₂ - represents a. In addition, Y ¹ and Y ² in the formula [I]
Each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and s and t each independently represent an integer of 0 to 3. A polycarbonate comprising a repeating unit represented by the following general formula (I): Wherein R ³ and R ⁴ in the formula [II] each independently represent a halogen atom or an alkyl group having 1 to 6 carbon atoms, k and m each independently represent an integer of 0 to 4, X ² has the same meaning as X ¹ in the formula [I]. However, X ¹ and X ² may be the same as each other or may be different. An electrophotographic photoreceptor characterized in that a polycarbonate copolymer comprising a repeating unit represented by formula (1) is used as a binder resin.