JP3009523B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member which maintains excellent mechanical strength and electrophotographic characteristics over a long period of time and can be suitably used in various electrophotographic fields. About the body.

[0002]

2. Description of the Related Art In a recent electrophotographic photoreceptor, a lamination type electrophotographic photoreceptor, that is, a photosensitive layer has a charge generation layer (CGL) for generating charges by exposure and a charge transport layer (CTL) for transporting charges. Or an organic electrophotographic photoreceptor (OPC) having at least two layers, wherein the photosensitive layer has a charge generation material and a charge transport material dispersed in a binder resin.
A single-layer type electrophotographic photosensitive member composed of layers has been proposed and used. As the binder resin of the charge transport layer of the laminated electrophotographic photosensitive member and the photosensitive layer of the single-layer electrophotographic photosensitive member,
In both cases, polycarbonate resins using bisphenol A as a raw material are widely used.

A polycarbonate resin made of bisphenol A has a good compatibility with a charge transporting material. Therefore, when a photosensitive member having a photosensitive layer using the binder resin as a binder is used, the polycarbonate resin has good electric characteristics, It has the feature of high mechanical strength.

However, when a photosensitive layer is formed using a polycarbonate resin made of bisphenol A as a binder resin, the following problems have been found. In producing the photoreceptor, when applying the photosensitive layer, the coating liquid may be whitened (gelled) or the photosensitive layer may be easily crystallized depending on the solvent used. In the portion where the crystallization occurs, there is no light decay, and the charge remains as a residual potential, which appears as a defect in image quality. Also,
When such a photoreceptor is used repeatedly, the residual potential is accumulated and remains largely, causing deterioration of the photoreceptor. In the case of a normal negative charge type electrophotographic photoreceptor, the photosensitive layer using a polycarbonate resin made of bisphenol A has poor adhesion to the base and is easily peeled off, or is damaged due to insufficient surface hardness, and the surface is worn. And the printing life is shortened. The term “underlayer” as used herein generally refers to a charge generation layer in the case of a laminated photoreceptor and a conductive substrate in the case of a single-layered photoreceptor. In the case of a positively charged electrophotographic photosensitive member, the conductive substrate serves as a base, but the adhesion is similarly poor. When a blocking layer or an intermediate layer is provided between the conductive substrate and the charge transport layer or between the charge generation layer and the charge transport layer for the purpose of improving the electrophotographic properties, those layers serve as a base.

[0005]

SUMMARY OF 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 photosensitive layer. Without whitening (gelling)
Another object of the present invention is to provide an electrophotographic photosensitive member that can maintain excellent mechanical strength such as printing durability and excellent electrophotographic characteristics including a decrease in residual potential over a long period of time, and is extremely excellent in practical use.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, an electrophotographic photosensitive member using a polycarbonate resin having a specific structure as a binder resin of a photosensitive layer has been developed. There is no such a problem as 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. The present inventors have found that excellent electrophotographic characteristics with little mechanical strength and little residual potential can be maintained over a long period of use, and based on this finding, the present invention has been completed.

That is, the present invention provides an electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer has the following general formula (I) or (II):

Embedded image Wherein R ¹ and R ² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms; a
And b are each independently an integer from 0 to 4, and X is

Embedded image Wherein R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, a cyano group, a nitro group,
An alkyl group, a cycloalkyl group having 5 to 7 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxyl group having 1 to 6 carbon atoms. ) And Y are —CR ⁵ R ⁶ — (where R ⁵ and R ⁶ are each independently a hydrogen atom, a trifluoromethyl group, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms). ), A 1,1-cycloalkylene group having 5 to 11 carbon atoms, an α, ω-alkylene group having 2 to 10 carbon atoms, a single bond, —O—, —S—, —SO— or —SO ₂ —. .
However,

Embedded image Except in the case of. And a repeating unit represented by the general formula (I) and a repeating unit represented by the general formula (II) Characterized in that a polycarbonate resin in a range represented by the following formula: 0.01 ≦ [(I) / {(I) + (II)}] ≦ 0.9 is used as the binder resin. The present invention provides an electrophotographic photoreceptor to be used.

The polycarbonate resin used in the electrophotographic photoreceptor of the present invention comprises a repeating unit represented by the general formula (I) and a repeating unit represented by the general formula (II). The repeating unit represented by the formula (I) is represented by the following formula 0.01 ≦ [(I) in a molar ratio to the total of the repeating unit represented by the formula (I) and the repeating unit represented by the formula (II). /{(I)+(II)}]≦0.9.

When the molar ratio of the repeating unit represented by the general formula (I) is less than 0.01, the effect of the present invention cannot be obtained, the coating solution is whitened (gelled), and the crystal of the charge transport layer is not formed. It is impossible to prevent the occurrence of printing and improve the printing life. on the other hand,
When this molar ratio exceeds 0.9, crystallization occurs in a part of the polycarbonate resin, which is not suitable for a binder resin for an electrophotographic photosensitive member.

A preferred content of the repeating unit represented by the formula (I) is 0.05 ≦ [(I) / {(I) + (II)}] ≦ 0.5.

The polycarbonate resin used in the present invention may have other repeating units other than those described above as long as the object of the present invention is not hindered. It can be used by appropriately adding and blending.

The polycarbonate resin used in the present invention preferably has a reduced viscosity [η _sp / c] at 20 ° C. of a solution having a concentration of 0.5 g / dl using methylene chloride as a solvent, and preferably has a reduced viscosity of 0.2 to 5.0 dl / c. g, more preferably 0.3 to
It is in the range of 3.0 dl / g. If the reduced viscosity [η _sp / c] is less than 0.2 dl / g, the mechanical strength of the polycarbonate resin is low. In particular, the surface hardness of the layer using the polycarbonate resin as a binder resin is insufficient, and the photoreceptor is abraded due to wear. The printing life may be shortened. On the other hand, the reduced viscosity [η
_{When [sp} / c] exceeds 5.0 dl / g, the solution viscosity of the polycarbonate resin increases, and it may be difficult to produce a photoconductor by a solution coating method.

The polycarbonate resin used in the present invention is a dihydroxyaryl represented by the following general formula (III): HO—X—OH (III) (wherein X has the same meaning as described above). Compound (III) and the following general formula (IV)

Embedded image (Wherein R ¹ , R ² , Y, a and b have the same meanings as described above), and a carbonate-forming compound such as phosgene, It can be obtained by polycondensation in the presence of a suitable acid binder, or by a method such as transesterification of a dihydroxyaryl compound (III) or a bisphenol compound (IV) with a bisaryl carbonate.

Typical examples of the dihydroxyaryl compound represented by the general formula (III) include the following compounds.

[0015]

Embedded image

Particularly preferably, hydroquinone, 1,4
-Dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, and 2,7-dihydroxyanthracene are used. As the bisphenol compound represented by the general formula (IV), specifically, 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-diphenylmethane, 1,1-bis (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, 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-t
tert-butyl-4-hydroxy-5-methylphenyl) propane, 1,1-bis (2-tert-butyl-
4-hydroxy-5-methylphenyl) butane, 1,1
-Bis (2-tert-butyl-4-hydroxy-5-
Methylphenyl) isobutane, 1,1-bis (2-te
rt-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-4-hydroxyphenyl) propane, 2,2-bis (3-bromo-
4-hydroxy-5-chlorophenyl) propane, 2,
2-bis (3,5-dichloro-4-hydroxyphenyl) butane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) butane, 1-phenyl-1,1-bis (3-fluoro- 4-hydroxyphenyl) ethane,
Bis (3-fluoro-4-hydroxyphenyl) ether, 1,1-bis (3-cyclohexyl-4-hydroxyphenyl) cyclohexane, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-3,3'- Dimethylbiphenyl, 4,4'-dihydroxy-2,2'-
Dimethylbiphenyl, 4,4'-dihydroxy-3,
3'-dicyclohexylbiphenyl, 3,3'-difluoro-4,4'-dihydroxybiphenyl and the like can be mentioned. One of these bisphenol compounds can be used alone, or both can be used in combination. Particularly preferably, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, and 1,1-bis (4-hydroxyphenyl) -1,1-diphenylmethane are used. .

Representative examples of the carbonate-forming compound include, for example, various carbonyl halides such as phosgene, haloformates such as a chloroformate compound, carbonate ester compounds and the like.

The proportion of the carbonate-forming compound used is as follows:
What is necessary is just to adjust suitably considering the stoichiometric ratio (equivalent) of reaction. When a gaseous carbonate-forming compound such as phosgene is used, a method of blowing the compound into the reaction system can be suitably employed.

Examples of the acid binder include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.
An alkali metal carbonate such as sodium carbonate or potassium carbonate, an organic base such as pyridine, or a mixture thereof is used. Similarly to the above, the ratio of the acid binder used may be appropriately determined in consideration of the stoichiometric ratio (equivalent) of the reaction.
Specifically, the dihydroxyaryl compound (I
It is preferred to use 2 equivalents or a slight excess of the acid binder relative to the total number of moles of II) and the bisphenol compound (IV) (1 mole usually corresponds to an equivalent).

As the solvent, various solvents such as those used in the production of known polycarbonates may be used alone or as a mixed solvent. Representative examples include, for example, hydrocarbon solvents such as xylene, and halogenated hydrocarbon solvents such as methylene chloride and chlorobenzene. The interfacial polycondensation reaction may be performed using two types of solvents that do not mix with each other.

In order to accelerate the polycondensation reaction, a catalyst such as a tertiary amine such as triethylamine or a quaternary ammonium salt is used.
It is desirable to carry out the reaction by adding a molecular weight regulator such as p-tert-butylphenol or phenylphenol. If desired, a small amount of an antioxidant such as sodium sulfite or hydrosulfide may be added.
The reaction is usually performed at a temperature in the range of 0 to 150C, preferably 5 to 40C. The reaction pressure can be any of reduced pressure, normal pressure, and pressurized pressure. Usually, the reaction can be suitably performed at normal pressure or about the self-pressure of the reaction system. The reaction time depends on the reaction temperature and the like, but is usually about 0.5 minute to 10 hours, preferably about 1 minute to 2 hours.

Further, first, a part of the reaction raw material comprising the dihydroxyaryl compound (III) and the bisphenol compound (IV) is reacted with a carbonate-forming substance to form an oligomer, and then the remaining reaction raw materials are added. A two-step method for completing the polycondensation can also be used. According to such a two-step method, the control of the reaction is easy and the molecular weight can be controlled with high accuracy.

The latter dihydroxyaryl compound (II)
When the transesterification method between I) and the bisphenol compound (IV) and the bisaryl carbonate is used, a reaction type such as a melt polycondensation method or a solid phase polycondensation method is suitable. When the melt polycondensation method is carried out, the above three monomers are mixed and reacted in a molten state at a high temperature under reduced pressure.
The reaction is usually performed at 150 to 350 ° C, preferably 200 to 3C.
It is performed at a temperature in the range of 00 ° C. When the solid-phase polycondensation method is performed, the above-mentioned three types of monomers are mixed, and the mixture is heated to a temperature equal to or lower than the melting point of the produced polycarbonate resin in a solid state to perform polycondensation. In any case, at the final stage of the reaction, the degree of reduced pressure is preferably adjusted to 1 mmHg or less, and phenols derived from the bisaryl carbonate generated by the transesterification are distilled out of the system. 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 reduced viscosity [η _sp / c] of the obtained polycarbonate resin can be adjusted to the above range by various methods such as selection of the reaction conditions and adjustment of the amount of the molecular weight modifier used. . In some cases, the obtained polycarbonate resin is subjected to appropriate physical treatment (mixing,
Fractionation) and / or a chemical treatment (polymer reaction, cross-linking treatment, partial decomposition treatment, etc.) to give a predetermined reduced viscosity [η
_sp / c] can also be obtained as a polycarbonate resin.

The obtained reaction product (crude product) can be subjected to various post-treatments such as a known separation and purification method and recovered as a polycarbonate resin having a desired purity (purity).

The electrophotographic photoreceptor of the present invention is not limited to any known electrophotographic photoreceptor of various types, as long as the above polycarbonate resin is used as a binder resin in a single-layer type and a laminated type photoreceptor. However, it is preferable that the photosensitive layer is used as a binder resin of the charge transport layer in a laminated electrophotographic photosensitive member having at least one charge generation layer and at least one charge transport layer.

In the electrophotographic photoreceptor of the present invention, the polycarbonate resin of the present invention may be used alone or in combination of two or more. If desired, other binder resin components such as polycarbonate may be contained as long as the object of the present invention is not impaired. Further, additives such as an antioxidant may be contained.

As the conductive substrate material used in the electrophotographic photoreceptor of the present invention, various materials such as known materials can be used.
Conductive by coating conductive material such as aluminum, nickel, chromium, palladium, graphite, etc. on metal plate or metal sheet such as brass, copper, nickel, steel, metal drum, plastic sheet by vapor deposition, sputtering, coating etc. It is possible to use a material which has been subjected to a chemical treatment, a material which has been subjected to a conductive treatment on a substrate such as glass, a plastic plate, a cloth, a paper, or a material which has been subjected to a metal oxide treatment by a metal such as electrolytic oxidation. .

The charge generating layer of the multi-layer type electrophotographic photoreceptor has at least a charge generating substance. This charge generating layer is formed by forming a layer of the charge generating substance on a base substrate by vacuum deposition, sputtering, or the like. Or by forming a layer formed by binding a charge generating substance using a binder resin on a substrate serving as an underlayer. As a method of forming the charge generation layer using a binder resin, various methods such as a known method can be used, and usually, for example, a coating liquid in which a charge generation material is dispersed or dissolved in a suitable solvent together with a binder resin is used. ,
A method in which the composition is applied on a substrate serving as a predetermined base and dried is preferably used.

As the charge-generating substance, various substances such as known substances can be used. Specifically, for example, selenium alone such as amorphous selenium and trigonal selenium, and selenium such as selenium-tellurium alloys, selenium compounds such as As ₂ Se ₃ or selenium-containing compositions, zinc oxide, CdS-
Inorganic materials consisting of Group II and Group IV elements such as Se,
Various inorganic materials such as oxide-based semiconductors such as titanium oxide, silicon-based materials such as amorphous silicon, metal or metal-free phthalocyanine, cyanine, anthracene, pyrene, perylene, pyrylium salt, thiapyrylium salt, polyvinylcarbazole, squarium pigment, etc. And various organic materials. These are 1
Species may be used alone or in combination of two or more.

The binder resin in the charge generation layer is not particularly limited, and various resins such as known ones can be used. Specifically, for example, polystyrene, polyvinyl chloride, polyvinyl acetate, vinyl chloride-acetic acid Vinyl copolymer, polyvinyl acetal, alkyd resin, acrylic resin, polyacrylonitrile, polycarbonate,
Thermoplastic resins such as polyamide, polyketone, polyacrylamide, butyral resin, and polyester, and thermosetting resins such as polyurethane, epoxy resin, and phenol resin can be used.

The polycarbonate resin can be used as a binder resin in the charge generation layer.

Next, the charge transporting layer can be obtained by forming a layer formed by binding a charge transporting substance with a binder resin on a base substrate. As a method for forming the charge transport layer, various methods such as a known method can be used.In general, a coating solution obtained by dispersing or dissolving a charge transport material in an appropriate solvent together with the above polycarbonate resin is used. For example, a method of applying the composition on a substrate serving as an underlayer and drying the applied composition.

In the charge transport layer, the above-mentioned polycarbonate resin may be used alone or may be used alone.
Mixtures of more than one species can be used. Further, other binder resins can be used in combination with the polycarbonate resin of the present invention as long as the object of the present invention is not impaired.

As the charge transporting substance that can be used in the present invention, for example, there are a conventionally used electron transporting substance and hole transporting substance. Specific examples of the electron transporting substance include, for example, chloroanil, bromoanil,
Tetracyanoethylene, tetracyanoquinodimethane,
2,4,7-trinitro-9-fluorenone, 2,4
5,7-tetranitro-9-tetrafluorenone, 2,
4,7-trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-tetranitroxanthone, 2,
There are electron withdrawing substances such as 4,9-trinitrothioxanthone, and those obtained by polymerizing these electron withdrawing substances. These may be used alone or in a combination of two or more.

Examples of the hole transporting substance include pyrene, N-ethylcarbazole, N-isopropylcarbazole,
-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-pyrrolidinobenzaldehyde-N, N-diphenylhydrazone,
1,3,3-trimethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 1-phenyl-1,2,3,4- Hydrazones such as tetrahydroquinoline-6-carboxaldehyde-1 ', 1'-diphenylhydrazone, 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) pyrazoline, 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) pyrazoline, 1-phenyl-3- (α-benzyl-
pyrazolines such as p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline and spiropyrazoline, 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-
Polyarylamines such as 2-methylphenyl) heptane and 1,1,2,2-tetrakis (4-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'-bis (butylphenyl) benzidine, N, N'-diphenyl-N, N'-bis (isopropylphenyl) benzidine, N, N ' -Diphenyl-
N, N'-bis (secondary butylphenyl) benzidine,
N, N'-diphenyl-N, N'-bis (tert-butylphenyl) benzidine, N, N'-diphenyl-N,
Benzidine compounds such as N'-bis (chlorophenyl) benzidine, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylacridine, poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, ethylcarbazole- Formaldehyde resin and the like can be mentioned. These may be used alone or in a combination of two or more.

Specific examples of the solvent used for forming the charge generation layer and the charge transport layer include, for example, benzene,
Aromatic solvents such as toluene, xylene and chlorobenzene, ketones such as acetone, methyl ethyl ketone and cyclohexanone, alcohols such as methanol, ethanol and isopropanol, esters such as ethyl acetate and ethyl cellosolve, carbon tetrachloride, carbon tetrabromide, chloroform, Dichloromethane, halogenated hydrocarbons such as tetrachloroethane, tetrahydrofuran, ethers such as dioxane,
Examples thereof include dimethylformamide, dimethylsulfoxide, and diethylformamide. These solvents may be used alone or in combination of two or more.

The coating of each layer can be performed using various coating apparatuses such as known ones, and specifically, for example, an applicator, a spray coater, a bar coater, a chip coater, a roll coater, a dip coater, a doctor blade, etc. Can be performed.

The photosensitive layer of the single-layer type electrophotographic photosensitive member contains at least the above-mentioned charge generating substance and the above-mentioned charge transporting substance in the above-mentioned polycarbonate as a binder resin. Although various methods can be used, for example, usually, for example, a coating solution in which a charge generating substance and a charge transporting substance are dispersed or dissolved in a suitable solvent together with a binder resin is applied to a predetermined base substrate. , A method of drying, etc. can be suitably used.

In addition, as long as the object of the present invention is not impaired,
Other binder resins can be used in combination with the polycarbonate resin of the present invention.

The electrophotographic photoreceptor of the present invention does not cause whitening (gelling) of the coating solution during its production, and has excellent mechanical strength and electrophotographic properties even when used repeatedly over a long period of time. This is an electrophotographic photoreceptor which is extremely excellent in practical use and maintains the above conditions, and can be suitably used in various electrophotographic fields.

[0042]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples, and various modifications are possible without departing from the spirit of the present invention. And applications are possible. Example 1 2,2-bis (4-hydroxyphenyl) propane 74
of phosgene gas in the solution under cooling with stirring while mixing a solution prepared by dissolving g in 550 ml of a 6% aqueous sodium hydroxide solution and 250 ml of methylene chloride.
Per minute for 15 minutes. Next, this reaction solution was allowed to stand and separated, and a methylene chloride solution of an oligomer of 2,2-bis (4-hydroxyphenyl) propane having a degree of polymerization of 2 to 4 in an organic phase and having a chloroformate group at a molecular end was used. I got Methylene chloride was added to the obtained oligomer solution to make the total amount 450 ml, and then mixed with a solution in which 10.8 g of 2,7-dihydroxynaphthalene was dissolved in 150 ml of an 8% aqueous sodium hydroxide solution. 2. p-tert-butylphenol which is
0 g was added. Then, while stirring this mixture vigorously, a 7% aqueous solution of triethylamine was used as a catalyst for 2 m.
l, and reacted at 28 ° C. for 1.5 hours under stirring. After completion of the reaction, the obtained reaction product is diluted with methylene chloride 1
Diluted with 1.5 liters, twice with 1.5 liters of water, 0.01
The mixture was washed once with 1 liter of N hydrochloric acid and twice with 1 liter of water, and the organic phase was poured into methanol for reprecipitation purification. The polymer thus obtained had a reduced viscosity [η _sp / c] at 20 ° C. of a solution having a concentration of 0.5 g / dl in methylene chloride as a solvent, of 0.72 dl / g. When the structure and composition of the obtained polymer were analyzed by ¹ H-NMR spectrum, it was confirmed that the polymer was a polycarbonate polymer having the following repeating units and composition.

[0043]

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A 50% by weight solution of the following hydrazone derivative in tetrahydrofuran was prepared as a charge transporting substance.
This coating solution did not show any white turbidity or gel formation even after being left for one month. Using a conductive substrate of aluminum, a thickness of about 0.5 μm of oxotitanium phthalocyanine
This coating solution was applied on the charge generation layer of m by a dip coating method, dried, and then provided with a charge transport layer having a thickness of 20 μm to produce a laminated electrophotographic photosensitive member. The charge transport layer did not crystallize during coating.

The charge transport material (1-phenyl-1,2,2,
3,4-tetrahydroquinoline-6-carboxaldehyde-1 ', 1'-diphenylhydrazone)

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The electrophotographic characteristics were measured using an electrostatic charging tester EP.
Using A-8100 (Kawaguchi Electric Co., Ltd.)-6
A corona discharge of kV was performed to measure an initial surface potential (V ₀ ), a residual potential (V _R ) after light irradiation (10 lux 5 sec), and a half-life exposure amount (E _1/2 ). Table 1 shows the results. Suga abrasion tester NUS-ISO-
Evaluation was performed using a Model 3 (manufactured by Suga Test Instruments Co., Ltd.). The test conditions were as follows: 12 samples on abrasion paper with a load of 200 g.
The sample was reciprocated 00 times, and the change in the amount of wear was measured. Table 2 shows the results.

Example 2 2,7-dihydroxynaphthalene 1 used in Example 1
0.8 g of 2,7-dihydroxyanthracene 14.1
g, and 2,2-bis (4-hydroxyphenyl)
The same operation as in Example 1 was performed except that 74 g of propane was changed to 1,1 bis (4-hydroxyphenyl) cyclohexane, and a polycarbonate polymer composed of the following repeating units ([η _sp /c]=0.75 dl / g) was obtained.

[0048]

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Using this polycarbonate polymer, a laminated electrophotographic photosensitive member was prepared in the same manner as in Example 1.
The stability of the coating solution and the evaluation results of crystallization during coating were all the same as in Example 1. Tables 1 and 2 show the evaluation results of the electrophotographic characteristics and the abrasion resistance, respectively.

Comparative Example 1 Commercially available polycarbonate comprising the following repeating units starting from 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) ([η _sp /c]=0.78)
dl / g) to prepare 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 a gel was generated. In addition, part of the charge transport layer crystallized (whitened) during coating. Tables 1 and 2 show the evaluation results of the electrophotographic characteristics and the abrasion resistance, respectively.

[0051]

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Comparative Example 2 74 g of 2,2-bis (4-hydroxyphenyl) propane used in Example 1 was added to 87 g of 1,1-bis (4-hydroxyphenyl) cyclohexane and 10.8 g of 2,7-dihydroxynaphthalene. Was replaced with 35 g of 1,1-bis (4-hydroxyphenyl) cyclohexane in the same manner as in Example 1 to obtain a polycarbonate polymer comprising the following repeating units ([η _sp /c]=0.84 dl /
g) was obtained.

[0053]

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Using this polycarbonate resin as a binder resin, a laminated electrophotographic photosensitive member was produced in the same manner as in Example 1. The stability of the coating solution and the evaluation results of crystallization during coating were all the same as in Example 1. Also,
Tables 1 and 2 show the evaluation results of the electrophotographic characteristics and the abrasion resistance, respectively.

[0055]

[Table 1] ─────────────────────────────────── Initial surface potential V ₀ (V) Residual potential V _R (V) Half-exposure E _1/2 (lux · sec) ────────────────────────────────── Example 1 -735 -1 0.78 2 -728 -2 0.80 Comparative Example 1 -752 -3 0.84 2 -732 -4 0.85 ──────────────────────

[0056]

[Table 2]

[0057]

According to the present invention, since a polycarbonate resin having a specific structure is used as a binder resin for a photosensitive layer of an electrophotographic photosensitive member, the coating liquid is whitened (gelled) during the preparation of the electrophotographic photosensitive member. The adhesion between the conductive substrate and the photosensitive layer is improved, the life of the electrophotographic photoreceptor can be extended, and the abrasion resistance of the photoreceptor surface is improved. It is possible to provide an electrophotographic photoreceptor excellent in printing durability that maintains excellent electrophotographic characteristics.

Continuation of front page (56) References JP-A-5-72751 (JP, A) JP-A-4-1799961 (JP, A) JP-A-4-274434 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G03G 5/00 101

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 formulas (I) and (II): Wherein R ¹ and R ² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms; a
And b are each independently an integer from 0 to 4, and X is Wherein R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, a cyano group, a nitro group,
An alkyl group, a cycloalkyl group having 5 to 7 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an alkoxyl group having 1 to 6 carbon atoms. ) And Y are —CR ⁵ R ⁶ — (where R ⁵ and R ⁶ are each independently a hydrogen atom, a trifluoromethyl group, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms). ), A 1,1-cycloalkylene group having 5 to 11 carbon atoms, an α, ω-alkylene group having 2 to 10 carbon atoms, a single bond, —O—, —S—, —SO— or —SO ₂ —. .
However, Except in the case of. And a repeating unit represented by the general formula (I) and a repeating unit represented by the general formula (II), wherein the content of the repeating unit represented by the general formula (I) is Characterized in that a polycarbonate resin in a range represented by the following formula: 0.01 ≦ [(I) / {(I) + (II)}] ≦ 0.9 is used as the binder resin. Electrophotographic photoreceptor.