JPH0784378A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To eliminate the generation of free halogen by exposure inside a photoreceptor, maintain a long-term charge characteristic and suppress pinhole and fog phonomena so as to prolong the service life of the photoreceptor itself by specifying the content of a halogen group organic solvent in a photoconductive layer. CONSTITUTION:In an electrophotographic photoreceptor, a photoconductive layer with polycarbonate, wet-formed by a chlorine group organic solvent, as binder resin is provided on a conductive support body, and the content of a halogen group organic solvent in the photoconductive layer is to be less than 1wt%. This electrophotographic photoreceptor can be either a type of having a single photoconductive layer on the conductive support body or a laminated type with separate functions. Lately, a laminated type electrophotographic photoreceptor formed of two layers, that is, a charge generating layer for generating charge by exposure and a charge transport layer for transporting charge is a leading type. An undercoating layer, a protecting layer, an adhesive layer, and the like can be also provided as occasion calls.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor. More specifically, the present invention relates to an electrophotographic photoreceptor containing less halogen-based organic solvent.

[0002]

2. Description of the Related Art Conventional methods and their problems Currently, electrophotographic technology is
Due to its high speed and high image quality, it is widely applied to copying machines and various printers. As the electrophotographic photosensitive member in this electrophotographic technique, conventionally, selenium,
Inorganic photoconductive materials such as selenium / tellurium alloys, selenium / arsenic alloys, and cadmium sulfide have been mainly used.

However, in view of toxicity, safety, cost, productivity, etc., an electrophotographic photoreceptor using an organic photoconductive substance has been recently developed. When the organic photoconductive material is a low molecular weight material, it is usually mixed with a binder resin to form a coating film. As binder resin, vinyl polymers such as polymethylmethacrylate, polystyrene, polyvinyl chloride, and their copolymers, polycarbonate, polyester, polysulfone, phenoxy resin, epoxy resin, silicone resin, and other various thermoplastic resins and thermosetting Resins have been used. Among these various resins, polycarbonate resin has relatively excellent properties and is often used.

As one using a polycarbonate resin as a binder resin, for example, JP-A-59-71057.
The polycarbonate resin derived from bisphenol Z is disclosed in JP-A-63-170647, and the polycarbonate resin derived from bisphenol A is disclosed in JP-A-63-170647.
Polycarbonate resin derived from dimethylbisphenol A is disclosed in JP-A-4-44048.
Discloses that a polycarbonate resin derived from bisphenol AP is used as a binder resin.

However, in the electrophotographic photosensitive member using these known organic photoconductive substances (OPC) and various binder resins, the electrophotographic photosensitive member using the inorganic photoconductive substance in terms of sensitivity and the like. Has been obtained that is comparable to. These OPCs can be easily formed into a thin film by a cast film forming method, are suitable for mass production, and are relatively inexpensive. OPC has such excellent aspects, but on the other hand, compatibility with the charge transfer agent, stability of the casting solution,
There are problems such as low molecular weight substances in polymers, and various improvements have been required.

[0006] Among them, there is a phenomenon called a minute black spot (pinhole) when an image is transferred onto plain paper. This is observed as small black spots on the copy paper when copying the white base paper, and as minute white spots on the copy paper when the black base paper is used.The cause is dust adhesion to the photoconductor, scratches, abnormal charging, etc. Conceivable. Also, a phenomenon similar to this, called fog, does not sufficiently remove the charge over a wide range,
Smear-like background stains occur on the back of the copy paper image.

Although it is possible to remove dust adhesion and fine scratches to some extent with a cleaning blade, cleaning the surface has almost no effect on abnormal charging, and improvements have been required. As one of the causes of this, there is an electrophotographic photosensitive member in which the low molecular weight substance in the binder resin has been removed because the low molecular weight substance in the binder resin has an influence. (Japanese Patent Publication No. 4-43265) However, although this method is effective for reducing the initial charging failure, it has almost no effect for the abnormal charging after long-term exposure.

[0008]

SUMMARY OF THE INVENTION Therefore, the present invention provides an electrophotographic photosensitive member which suppresses the generation of minute black spots and which is free from the fog phenomenon due to abnormal charging and the smear on the copy paper image. is there.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made extensive studies as to an electrophotographic photosensitive member which has improved the above-mentioned drawbacks, and as a result, have found that the residual solvent in the binder resin is associated with abnormal charging. Reached

That is, the present invention relates to an electrophotographic photoreceptor having a photoconductive layer containing a polycarbonate as a binder resin wet-molded with a chlorine-based organic solvent on a conductive support, and a halogen-based organic solvent in the photoconductive layer. Relates to an electrophotographic photoconductor characterized by being less than 1% by weight.

The electrophotographic photosensitive member of the present invention may have a single-layer photoconductive layer on a conductive support, or may have a function-separated laminated type. Recently, a laminated electrophotographic photoreceptor having two layers of a charge generation layer that generates a charge upon exposure and a charge transport layer that transports the charge has become mainstream.
Further, if necessary, an undercoat layer, a protective layer, an adhesive layer, etc. may be provided.

The conductive support of the present invention means a metal material such as aluminum, stainless steel or nickel, or a polyester film having a conductive layer such as aluminum, palladium, tin oxide or indium oxide on its surface, or phenol. Resin, paper, etc. are used.

The charge generation layer of the present invention is formed by a known method.
It is formed on a conductive support. As the charge generating substance,
For example, azoxybenzene-based, disazo-based, trisazo-based, benzimidazole-based, polycyclic quinoline-based, indigoid-based, quinacridone-based, phthalocyanine-based, perylene-based, and methine-based organic pigments can be used. These charge-generating substances include fine particles of polyvinyl butyral resin, polyvinyl formal resin, silicone resin, polyamide resin, polyester resin, polystyrene resin, polycarbonate resin, polyvinyl acetate resin, polyurethane resin, phenoxy resin, epoxy resin, various celluloses, etc. It is used in the form of being dispersed in a binder resin.

The charge transport layer of the present invention is formed on the charge generation layer by a known method by dispersing the charge transport substance using the polycarbonate resin of the present invention as a binder resin.

Examples of the charge transport material include polytetracyanoethylene; fluorenone compounds such as 2,4,7-trinitro-9-fluorenone; nitro compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromoanhydride. Maleic acid; triphenylmethane compound; 2,5-di (4-dimethylaminophenyl)-
Oxadiazole compounds such as 1,3,4-oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene; carbazole compounds such as poly-N-vinylcarbazole; 1-phenyl-3-
Pyrazoline compounds such as (p-dimethylaminophenyl) pyrazolin; amine derivatives such as 4,4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine;
1,1-bis (4-diethylaminophenyl) -4,4
-Conjugated unsaturated compounds such as diphenyl-1,3-butadiene; hydrazone compounds such as 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone; indole compounds, oxazole compounds, isoxazole compounds , Thiazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, pyrazole-based compounds, pyrazoline-based compounds, triazole-based compounds and the like nitrogen-containing cyclic compounds; condensed polycyclic compounds and the like. The above charge transport substances may be used alone or in combination of two or more.

The polycarbonate resin of the present invention can be produced by a normal interfacial polycondensation reaction of bisphenol and phosgene. As the polycarbonate resin of the present invention, various polycarbonate resins such as homo- and co-polycarbonate resins using ordinary bisphenols, and further branched resins can be used. From the viewpoint of solution stability, solubility, film-forming property, workability, etc. during layer formation, bisphenols suitable for these include, for example, 2,2-bis (4-hydroxyphenyl) propane, 2, 2-bis (3,5-dibromo-4-hydroxyphenyl) propane (= tetrabromobisphenol A), 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (3-t -Butyl-4-
Hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,
2-bis (3-bromo-4-hydroxyphenyl) propane, 2,2-bis (3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis (3-phenyl-
4-hydroxyphenyl) propane, 2,2-bis (3
Ortho-substituted bisphenols exemplified by -cyclohexyl-4-hydroxyphenyl) propane; 1,1-
Bis (hydroxyaryl) arylalkanes exemplified by bis (4-hydroxyphenyl) -1-phenylethane and bis (4-hydroxyphenyl) diphenylmethane; 1,1-bis (4-hydroxyphenyl) cyclopentane, 1 , 1-bis (4-hydroxyphenyl) cyclohexane and the like, bis (hydroxyaryl) cycloalkanes; 4,4′-dihydroxydiphenyl ether 4,4′-dihydroxy-3,3 ′
A combination system of dihydroxy diaryl ethers exemplified by dimethyldiphenyl ether and bis (hydroxyaryl) alkanes; 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxy-3,
Examples thereof include a combination system of dihydroxydiarylsulfides exemplified by 3′-dimethyldiphenylsulfide and bis (hydroxyaryl) alkanes. Of these, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) diphenylmethane, 1 , 1-bis (4-
(Hydroxyphenyl) cyclohexane, a combined system of 4,4'-dihydroxydiphenyl ether and 2,2-bis (4-hydroxyphenyl) propane, 4,4'-dihydroxydiphenylsulfide and 2,2-bis (4-hydroxyphenyl) A combination system with propane is preferred.

The charge generating layer and the charge transporting layer are formed by dissolving the above charge generating substance or the charge transporting substance in a binder resin and a suitable solvent, coating the solution, and drying. it can.

This solvent can be roughly classified into two types, a halogen type organic solvent and a non-halogen type solvent. Generally, a halogen type solvent which is not flammable or a combination type of a halogen type solvent and a non-halogen type solvent is frequently used. To be done. For example, in non-halogen solvents, benzene, toluene, aromatic solvents such as xylene, acetone, methyl ethyl ketone, ketone solvents such as cyclohexanone, tetrahydrofuran, dioxane, ether solvents such as ethylene glycol diethyl ether, methyl acetate, ethyl acetate, Examples thereof include ester solvents such as ethyl cellosolve, alcohol solvents such as methanol, ethanol and isopropanol, and dimethylformamide, dimethylsulfoxide, diethylformamide and the like. Examples of the halogen-based solvent include methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, tetrachloroethane, chlorobenzene, etc., and these solvents may be used alone or contain a halogen-based solvent. You may use together 2 or more types as a solvent for mixing.

In the present invention, in order to reduce the amount of the halogen-based organic solvent in the electrophotographic photosensitive member to less than 1% by weight, a method of using the electrophotographic photosensitive member manufactured in a process using no halogen-based solvent or a halogen-containing solvent is used. A method of using the system solvent and thoroughly drying it to remove the dehalogenation solvent can be mentioned. The method that does not use a halogen-based solvent at all is not preferable because it has a strong flammability, is troublesome to handle, and has an economical problem in that the molding apparatus and the like must have an explosion-proof structure. The method using a halogen-based solvent is an inexpensive process because it has low flammability and does not require an economically expensive explosion-proof structure. However, it is desirable to prevent external diffusion by treating the generated halogen with adsorption of activated carbon in consideration of environmental problems.

If the photoconductive layer of the electrophotographic photosensitive member contains more than 1% by weight of the halogen-based solvent, the halogen-based solvent is decomposed by long-term exposure or thermal history to generate free chlorine. Free chlorine affects the charging characteristics of the generated part and causes pinholes and fog. If it is less than 1% by weight, pinholes and fog phenomena are suppressed, and if it is less than 0.5% by weight, pinholes and fog phenomena are hardly observed.

The mixing ratio of the charge generating substance and the binder resin is preferably in the range of 10: 1 to 1:20. The thickness of the charge generation layer is 0.01 to 20 μm, preferably 0.1.
1-2 μm is suitable. The mixing ratio of the charge transport material and the binder resin is preferably in the range of 10: 1 to 1:10. The thickness of the charge transport layer is 2 to 100 μm, preferably 5 to 30 μm.

[0022]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples.

Synthesis Example 1 3.7 kg of sodium hydroxide was dissolved in 42 liters of water, and 1,1-bis (4-hydroxyphenyl) cyclohexane (hereinafter referred to as "BPZ") was maintained at 20 ° C.
8.5 kg and 8 g of hydrosulfite were dissolved.
To this, 28 liters of methylene chloride was added and stirred, 130 g of pt-butylphenol (hereinafter referred to as "PTBP") was added, and then 4.0 kg of phosgene was added to 6 g.
Introduced in 0 minutes. After completion of the introduction of phosgene, the reaction solution was emulsified by vigorous stirring. After emulsification, 8 g of triethylamine was added and stirring was continued for about 1 hour to polymerize. The polymerization solution is separated into an aqueous phase and an organic phase, the organic phase is neutralized with phosphoric acid, and then repeatedly washed with water until the pH of the washing solution becomes neutral. Then, 35 liters of isopropanol is added to precipitate the polymer. Let The precipitate was filtered and then dried to obtain a powdery polycarbonate resin having an intrinsic viscosity of 0.49 (hereinafter referred to as "P-1").

Synthesis Example 2 In Synthesis Example 1, instead of BPZ 8.5 kg, 2,
8.2 kg of 2-bis (4-hydroxy-3-methylphenyl) propane (hereinafter referred to as "BPC") was added to PTBP.
The same procedure as in Synthesis Example 1 was carried out except that 150 g of PTBP was used instead of 130 g. The intrinsic viscosity of the obtained powdery polycarbonate resin (hereinafter referred to as "P-2") was 0.64.

Synthesis Example 3 In Synthesis Example 1, instead of BPZ 8.5 Kg, 2,
The same procedure as in Synthesis Example 1 was performed except that 7.2 kg of 2-bis (4-hydroxyphenyl) propane (hereinafter referred to as “BPA”) was used instead of 130 g of PTBP, and 300 g of PTBP was used. The intrinsic viscosity of the obtained powdery polycarbonate resin (hereinafter referred to as "P-3") is 0.38.
Met.

Example 1 τ-type copper phthalocyanine 10 was formed on a polyethylene terephthalate film on which aluminum was vapor-deposited to a thickness of about 50 nm.
Parts and phenoxy resin 5 parts, polyvinyl butyral resin 5
And 100 parts of dimethoxyethane were mixed, and the resulting mixture was pulverized and dispersed in a sand grind mill to apply a coating solution, which was then dried to form a charge generation layer having a thickness of about 0.5 μm.

Then, 50% of 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone was added.
Part, Polycarbonate resin P obtained in Synthesis Example-1
50 parts of -1 and 350 parts of chloroform were used to prepare a coating solution, which was coated on the charge generation layer and air-dried to 100 parts.
After drying at 8 ° C. for 8 hours, a charge transport layer having a thickness of about 20 μm was provided to prepare a laminated electrophotographic photoreceptor. A part of this photoconductor was scraped off and the concentration of the halogen-based solvent was confirmed by gas chromatography.

Evaluation of this electrophotographic photosensitive member was repeated 50,000 times and 80,000 times using a commercially available copying machine having a blade cleaning system and a scorotron charger, and pinholes were obtained from the obtained copies. The presence or absence of fog was examined. The results are shown in Table 1.

Example 2 Example 2 was repeated except that chloroform was changed to monochlorobenzene and the drying conditions were 120 ° C. and 10 hours.

Example 3 Example 3 was repeated except that chloroform was changed to monochlorobenzene and the drying conditions were 120 ° C. and 4 hours.

Example 4 The procedure of Example 2 was repeated except that the polycarbonate of Synthesis Example 2 was used.

Example 5 The procedure of Example 1 was repeated except that the polycarbonate of Synthesis Example 3 was used and chloroform was changed to dichloromethane.

Example 6 350 parts by weight of chloroform was added to tetrahydrofuran 175.
The same procedure as in Example 1 was repeated except that the parts were changed to 175 parts by weight and chloroform.

Comparative Example 1 Example 2 except that the drying condition was 120 ° C. for 2 hours.
I went the same way.

Comparative Example 2 Example 5 except that the drying conditions were 100 ° C. and 2 hours.
I went the same way. The results of Examples and Comparative Examples are shown in Table 1.
Shown in. (Below margin)

[Table 1] Table 1

The description in Table 1 is as follows. P-1: Polycarbonate resin obtained in Synthesis Example 1 P-2: Polycarbonate resin obtained in Synthesis Example 2 P-3: Polycarbonate resin obtained in Synthesis Example 3 CH: Chloroform THF: Tetrahydrofuran MCB: Monochlorobenzene DCM : Dichloromethane Halogen-based organic solvent concentration: Halogen-based organic solvent concentration in the charge transport layer measured by gas chromatography (% by weight) Electrophotographic characteristics: Pinholes and fog after 50,000 and 80,000 copyings. Large (x); 10 or more of the bin area, 10% or more of the total area (△); 1-9, 10% or less None (○); Not confirmed, not confirmed "Actual" is an example, "ratio" Is a comparative example.

[0037]

In the electrophotographic photoreceptor of the present invention, since the content of the halogen-based organic solvent in the photoconductive layer is less than 1% by weight, there is almost no generation of free halogen due to exposure inside the photoreceptor, Along with maintaining long-term charging characteristics, the phenomenon of pinholes and fogging is suppressed, the life of the photoconductor itself is extended, and a beautiful electrophotographic image is obtained.

Claims (3)

[Claims] 1. An electrophotographic photoreceptor having a photoconductive layer containing a polycarbonate as a binder resin, which is wet-molded with a chlorine-based organic solvent on a conductive support, and a content of a halogen-based organic solvent in the photoconductive layer. Is less than 1% by weight. 2. The halogen-based organic solvent is selected from dichloromethane, chloroform and monochlorobenzene.
The electrophotographic photosensitive member described. 3. The electrophotographic photosensitive member according to claim 1, wherein the content of the halogen-based organic solvent is less than 0.5% by weight.