JPH04291348A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve durability by using specific cross-linking polycarbonate as a binder resin of a photosensitive layer. CONSTITUTION:The binder resin is a polycarbonate cross-linked body which allows a polycarbonate containing an aliphatic unsaturated hydrocarbon group in the molecule to cross-link by light or heat reaction. The polycarbonate cross- liked body is made by cross-linking the carbonate containing repeating unit selected from the formula I and II. In this case, each of R1, R2, R3 and R4 is 2-8C univalent aliphatic unsaturated hydrocarbon group, each of (m) and (n) is 0.1 and 2 and (m+n) is >=1 and in the formula II, (m) is 1-2, X is 1-8C saturated hydrocarbon group or aromatic hydrocarbon group.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor using a specific crosslinked polycarbonate resin as a binder resin.

0002

2. Description of the Related Art Electrophotographic technology is widely used in fields such as copying machines, laser beam printers, and facsimile machines because of its high speed and high print quality. As electrophotographic photoreceptors used in these electrophotographic techniques, those using inorganic photoconductive materials such as selenium-based materials have been widely known, but recently electrophotographic photoreceptors using these inorganic photoconductive materials have been used. Research on electrophotographic photoreceptors using organic photoconductive materials, which are inexpensive and have superior advantages in terms of manufacturing and disposal, has become mainstream.

The surface of the photosensitive layer of an electrophotographic photoreceptor is directly subjected to electrical, thermal, and mechanical external forces during processes used, such as corona charging, toner development, transfer, and cleaning treatment, and therefore, it is subjected to repeated electrophotographic processes. By doing this, the following problems arise. Durability against external mechanical forces, i.e. problems such as image defects caused by abrasion or damage to the surface of the photosensitive layer due to direct loads from toner, developer, paper, cleaning materials, etc.; ozone generated by corona discharge; There are problems such as image fading in a high humidity environment caused by low resistance substances such as nitrogen oxides being deposited and accumulated on the surface of the photosensitive layer.

These problems are largely due to the binder resin of the photosensitive layer, so selection of the binder resin is very important. Conventionally, single products, copolymers, and mixtures of methacrylic resin, acrylic resin, polystyrene, polyester, polycarbonate, polyarylate, polysulfone, and the like have been proposed as binder resins. Among these, polycarbonate resin is comprehensively superior and has been put into practical use. However, the current situation is that it is still unsatisfactory in terms of direct defects caused by wear and damage on the surface of the photosensitive layer, and it has been desired to develop a binder resin that can form a photosensitive layer with high surface hardness. .

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide an electrophotographic photoreceptor having a photosensitive layer with high surface hardness.

[0006] In order to achieve the above object, the present inventor conducted intensive studies on binder resins, and found that a polycarbonate crosslinked product having a specific structure has high surface hardness,
The inventors have discovered that the defects caused by abrasion and damage on the surface of the photosensitive layer can be eliminated and the life of the electrophotographic photoreceptor can be significantly improved, and the present invention has been completed.

[0007]

[Means for Solving the Problems] The present invention provides an electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive substrate, in which a binder resin of the photosensitive layer has the following general formula [1].

[0008]

[In the formula, R1 and R2 are the same or different carbon numbers 2 to
8 monovalent aliphatic unsaturated hydrocarbon group, m and n are each 0
, 1 or 2, and m+n is 1 or more, and X is

000
9]

[Formula 6] (where Ra and Rb are a saturated hydrocarbon group or an aromatic hydrocarbon group having 1 to 8 carbon atoms, which may have the same or different hydrogen atoms or halogen atoms, and Rc is a saturated hydrocarbon group having 4 to 10 carbon atoms. divalent saturated hydrocarbon group), alkylene group having 2 or more carbon atoms, phenylene group, cycloalkylene group, aralkylene group, -O-, -S-, -SO2 -,

001
0]

[Chemical 7] (Here, Ar has 6 to 1 carbon atoms, which may be substituted on the nucleus
2 aromatic hydrocarbon group, Z is an alkylene group having 2 to 4 carbon atoms)] and the following general formula [2]

[0011]

[Chemical formula 8] [Wherein R3 is a monovalent aliphatic unsaturated hydrocarbon group of 2 to 8, m is 1 or 2] A crosslinked polycarbonate resin containing 5 mol% or more of units selected from This invention relates to an electrophotographic photoreceptor characterized by the following.

The conductive substrate in the electrophotographic photoreceptor of the present invention is, for example, a metal plate such as aluminum, brass, copper, nickel, or steel, or a metal sheet or plastic sheet with aluminum, nickel, chromium, titanium, or palladium on it. It is possible to use materials coated with conductive substances such as indium oxide, tin oxide, graphite, etc. by vapor deposition, sputtering, coating, etc., or materials made of glass, plastic plates, etc. that have been treated to become conductive. can.

[0013] A photosensitive layer of a dispersed type, a laminated type, etc. is provided on the conductive substrate. An undercoat layer having a barrier function or an adhesive function may be provided between the photosensitive layer and the conductive substrate, if necessary. Examples of materials constituting the undercoat layer include polyvinyl butyral, polyvinyl alcohol, polyamide, cellulose, gelatin, polyurethane,
Resins such as polyester and metal oxides such as aluminum oxide can be used.

The photosensitive layer formed on the conductive substrate may have a single-layer structure or a laminated structure in which a charge generation layer and a charge transport layer are functionally separated. In the case of a laminated structure, the charge generation layer and the charge transport layer may be laminated in any order. The photosensitive layer is composed of a coating film containing a charge generating substance, a charge transporting substance, or both in a binder resin.

Examples of the charge generating substance include various alloy materials containing selenium as a main component such as amorphous selenium, crystalline selenium, selenium-tellurium alloy, selenium-arsenic alloy, zinc oxide,
Inorganic photoconductors such as titanium oxide, organic pigments and dyes such as phthalocyanine, squarium, anthrone, perylene, azo, anthracene, pyrene, pylithium salts, and thiapyrylium salts are used.

Examples of the charge transport substance include heterocyclic compounds such as carbazole, indole, imidazole, thiazole, osadiazole, pyrazole, and pyrazoline;
Electron-donating substances such as aniline derivatives, hydrazine derivatives, hydrazone derivatives, stilbene derivatives, or polymers having basic side chains consisting of these compounds are used, and hydrazone derivatives, aniline derivatives, and stilbene derivatives are particularly preferred.

The binder resin used in the present invention is a crosslinked polycarbonate obtained by crosslinking polycarbonate containing an aliphatic unsaturated hydrocarbon group in its molecule by photo or thermal reaction. Such a crosslinked polycarbonate is one obtained by crosslinking polycarbonate (hereinafter referred to as crosslinkable polycarbonate) containing repeating units selected from the following general formulas [1] and [2].

[0018]

[Chemical formula 9]

[0019]

embedded image In the formula, preferred examples of the monovalent aliphatic unsaturated hydrocarbon group represented by R1, R2, and R3 include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a 1,4-butadienyl group, Examples include 1,3-pentadienyl group. Also, represented by X in the formula

[0020]

Preferred examples of the saturated hydrocarbon group represented by Ra and Rb in [Chemical Formula 11] include methyl group, ethyl group, propyl group, isopropyl group, isobutyl group, etc. Preferred examples of Rc are
When expressed as a cyclic divalent group including the number of bonded carbon atoms, examples include cyclopentylidene group, cyclohexylidene group, bicyclo[2,2,1]heptylidene group, etc.
Preferred examples include phenylene group, cycloalkylene group,
Aralkylene group, -O-, -S-, -SO2-,

0
021]

[Chemical formula 12] etc. General formula containing these unsaturated groups [1]
At least one type of repeating unit selected from [2] and [2] is contained in the crosslinkable polycarbonate in an amount of at least 5 mol %, preferably 10 mol % or more. If the proportion of units containing unsaturated groups is 5 mol % at the ends, the degree of crosslinking will not be sufficient, which is not preferable. In the present invention, these units may be used alone or in combination.

[0022] Repeating units other than general formulas [1] and [2] are repeating units that do not contain unsaturated groups, such as those of general formula [1]
, [2] from which R1, R2, and R3 are removed. For example, the following formula,

[0023]

[Chemical formula 13]

[0024]

[Chemical formula 14]

[0025]

[Chemical formula 15]

[0026]

Examples include repeating units represented by: The phenylene group in these repeating units may be substituted with a saturated group, halogen, or the like.

The crosslinkable polycarbonate used in the present invention can be prepared by a conventionally well-known reaction (Nikkan Kogyo Shimbun, Plastic Materials Course [5], Polycarbonate Resin, 9-
(see page 14). An example of this is (
1) Reaction shown by the following formula using phosgene

0028
]

[Chemical formula 17] (2) Reaction using bischloroformate of dioxy compound

[0029]

[Chemical formula 18] (3) Reaction expressed by the following formula using carbonic acid diester

[0030]

[Chemical formula 19] etc. In these formulas, R1, R2, Ra
, Rb, m, and n have the same definitions as in the general formula [1], R4 represents an arylene group, and R5 represents any one of an alkyl group, a cycloalkyl group, and an aryl group. Phosgene is used because the resulting crosslinked polycarbonate has excellent transparency and can be produced at low cost (1)
The most preferred reaction is

The crosslinking reaction of the crosslinkable polycarbonate can be carried out thermally or by photochemical reaction. The thermal crosslinking reaction is easily achieved by heating the polymer in the presence of a radical initiator, optionally adding a crosslinking agent. As a radical initiator,
Those having a half-life of 1 to 10 hours at 50 to 100°C are preferred from the viewpoint of the process, such as benzoyl peroxide, diisopropyl peroxide, t-butyl peroxypivalate, octanoyl peroxide, lauroyl peroxide, acetyl peroxide. , peroxides such as cyclohexane peroxide, and azo compounds such as azobisisobutyronitrile and azobisisovaleronitrile. Examples of the crosslinking agent include diallyl compounds such as diallyl phthalate, diallylamine hydrochloride, and diallyl ether, and polyfunctional acrylates such as trimethylolpropane triacrylate, ethylene dimethacrylate, and pentaerythritol tetraacrylate.

[0032] When crosslinking polycarbonate thermally, the temperature is 50 to 150°C, preferably 70 to 150°C after coating.
Perform at °C. Temperatures below 50°C are not preferred because the thermosetting reaction does not proceed sufficiently. Further, if the temperature is higher than 150°C, constituent components other than the crosslinkable polycarbonate in the conductive substrate and photosensitive layer will deteriorate, which is not preferable. The curing time is usually 5 minutes to 10 hours, preferably 10 minutes to 5 hours.

When the crosslinking reaction is carried out by irradiation with ultraviolet light, it is carried out by irradiating ultraviolet light after coating, preferably in the coexistence of a crosslinking agent in addition to a photoradical initiator. Examples of the crosslinking agent used here include polyallyl compounds, polyfunctional acrylates, polymercaptans, and polyfunctional azide compounds.

[0034] Examples of polyallyl compounds include diallyl compounds such as diallyl phthalate, diallylamine hydrochloride, and diallyl ether, and examples of polyfunctional acrylates include trimethylolpropane triacrylate, ethylene glycol dimethacrylate, and pentaerythritol tetraacrylate. can give. Examples of the polymercaptan include pentaerythritol tetra(3-mercaptopropionate) and 1,4-dimercaptohexane. As the polyfunctional azide compound, aromatic azides having relatively good thermal stability are preferably used, such as 4,4'-diazidobenzalacetone, 2,6-di(4'-azidobenzal)cyclohexanone, 2, 6-di(4'-azidobenzal)-4-methylcyclohexanone, di[4-(4'-azidophenyl)butadienyl]ketone, 4,4'-diazidochalcone, 4,4'-diazidostilbene-2 , 2'-disulfonic acid, etc. In the photocrosslinking reaction using polyallyl compounds, polyfunctional acrylates, and polymercaptans among the above crosslinking agents, the coexistence of a photoradical initiator is preferable.

Examples of the photoradical initiator include benzophenone compounds such as benzophenone and Michler's ketone, diketone compounds such as benzyl and phenylmethoxydiketone, benzoin compounds such as benzoin ethyl ether and benzyl dimethyl ketal, and 2,4-diethylthioxanthone. Thioxanthone compounds such as, 2-methylanthraquinone, quinone compounds such as camphorquinone, etc. are preferably used. Furthermore, a photocrosslinking reaction accelerator other than the above-mentioned initiator, such as an N,N-diethylaminobenzene derivative, can be used in combination as necessary.

As the irradiation source, a mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, methyl halide lamp, etc. are preferably used. The power of the light source is 1mw/cm2 ~1kw/cm2
The irradiation time depends on the power of the light source and the photoreaction rate, and is usually 1 second to 1 hour, preferably 1 second to 10 seconds.
It is a minute.

When the photosensitive layer has a laminated structure in which a charge generation layer and a charge transport layer are functionally separated, the above-mentioned crosslinkable polycarbonate is used as a binder resin for at least the layer forming the surface. Of course, it can also be used as a binder resin for either the charge generation layer or the charge transport layer. For example, when the surface layer is a charge transport layer, the charge generation layer can be formed by dispersing or dissolving the above charge generation substance and binder resin in a suitable solvent, applying a coating solution, and drying. Can be done. The binder resin used here may be any one such as polystyrene, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl acetal, alkyd resin, acrylic resin, polyacrylonitrile, polycarbonate,
Thermoplastic resins such as polyamide, polyketone, polyacrylamide, butyral resin, and polyester, thermocoil resins such as polyurethane, epoxy resin, and phenol resin can be used. The thickness of this charge generation layer is usually 0.05 to 40 μm, preferably 0.05 to 25 μm.
is set to

The charge transport layer, which is a surface layer, is prepared by applying a solution in which the above charge transport substance, the above crosslinkable polycarbonate, a crosslinking agent and an initiator are dissolved in a suitable solvent, and after drying,
It can be formed by crosslinking with heat or light. Many useful organic solvents can be used as the solvent used to form the charge transport layer. Typical examples include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene, ketones such as acetone and 2-butanone, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and ethylene chloride, and tetrahydrofuran. , dioxane, ethylene glycol, cyclic or linear ethers such as diethyl ether, or mixed solvents thereof. The thickness of the charge transport layer is usually 2 to 100 μm.
, preferably set to 10 to 40 μm.

When the photosensitive layer has a dispersed single structure, a solution of the above-mentioned crosslinkable polycarbonate, charge generating material, charge transporting material, crosslinking agent and initiator dissolved in a suitable solvent is coated and dried. After that, it can be formed by crosslinking with heat or light. As the solvent used here, many useful organic solvents can be used. Typical examples include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, and ethylene chloride; Examples include cyclic or linear ethers such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether, and mixed solvents thereof. The thickness of the photosensitive layer is usually 2 to 100μ.
m, preferably set to 10 to 40 μm.

[0040]

[Examples] The present invention will be explained in more detail below with reference to Examples. Parts represent parts by weight, and % represents weight %. Evaluation,
After the obtained electrophotographic photoreceptor was installed in a copying machine equipped with a blade cleaning member and 50,000 copies were made, the amount of surface abrasion (μm) of the electrophotographic photoreceptor and the occurrence of image defects due to this abrasion and scratches were determined. According to research, the surface hardness is JISK5
400 (Pencil: Mitsubishi Uni, Pencil angle: 45 degrees, Load: 1.0±0.05 kg).

Binder resin (3,3'-diallylbisphenol A-bisphenol Z copolycarbonate)
Production: Add 53.7 parts of a 48.5% aqueous solution of caustic soda and 230 parts of water while flowing dry nitrogen gas into a three-neck round-bottomed flask equipped with a stirrer, thermometer, gas inlet tube, and reflux condenser.
．． 8 parts, 3,3'-diallylbisphenol A31.4
1 part, and 27.3 parts of bisphenol Z were charged and dissolved. This solution was cooled to 20° C. in an ice bath, and 26.2 parts of phosgene gas was gradually introduced over 1 hour while stirring. After that, 8.4 parts of 48.5% caustic soda aqueous solution was added,
Furthermore, after adding 0.61 part of p-tert-butylphenol as a reaction terminator, the polymerization reaction was continued at 30°C for 1 hour. After the reaction was completed, the methylene chloride layer was separated, acidified with hydrochloric acid, and washed with water repeatedly to remove dissolved salts. Thereafter, methylene chloride was evaporated to obtain a solid (yield 99%). The specific viscosity of the obtained polymer measured in methylene chloride at 20°C was 0.21. This stuff is methylene chloride,
It is 10% soluble in chloroform, toluene, tetrahydrofuran, cyclohexanone, etc., and as a result of hydrogen nuclear magnetic resonance spectroscopy, the following formula

[0042]

It was confirmed that it was a 1:1 copolymerized polycarbonate of 2,2'-diallylbisphenol A and bisphenol Z represented by the following formula.

[0043]

[Example 1] The following formula

[0044]

100 parts of dimethoxyethane was added to 10 parts of the bisazo compound represented by the following formula and 10 parts of polyvinyl butyral resin, and the mixture was pulverized and dispersed using a sand grind mill. A mirror-finished aluminum cylinder was immersed in the resulting solution to obtain a charge generation layer of 0.15 μm.

Next, the following formula

[0046]

10 parts of a hydrazone compound represented by the following formula, 10 parts of the allyl-substituted polycarbonate copolymer obtained in the reference example as a binder resin, and pentaerythritol tetra (3
-mercaptopropiocate) and 0.0 parts of Irgacure 907 (manufactured by Ciba Geigy) as a photopolymerization initiator.
1 part to 30 parts of monochlorobenzene and 25 parts of dichloromethane
It was dissolved in parts. This solution was applied onto the electricity generating layer by a dipping method, and after drying, it was irradiated for 5 seconds with a high-pressure mercury lamp with an irradiation energy of 80 W/cm2 to cure it.
A charge transport layer having a thickness of 0 μm was formed to obtain an electrophotographic photoreceptor. The evaluation results are shown in Table 1.

[0047]

[Comparative Example] In place of the allyl-substituted polycarbonate copolymer used as the binder resin in Example 1, polycarbonate of bisphenol Z with a viscosity average molecular weight of 20,000 [Panlite TS-2020 manufactured by Teijin Kasei Ltd.] was used as the binder resin.
] 10 parts was used, and the evaluation results are shown in Table 1.

[0048]

[Table 1]

[0049]

[Effects of the Invention] The present invention provides an electrophotographic photoreceptor with excellent durability and less occurrence of image defects due to abrasion or scratches on the photosensitive layer, since a photosensitive layer with excellent surface hardness and abrasion resistance is obtained. It has a special effect of making it possible.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive substrate, wherein the binder resin of the photosensitive layer is
The following general formula [1] [Formula 1] [In the formula, R1 and R2 are the same or different, having 2 to 2 carbon atoms]
8 monovalent aliphatic unsaturated hydrocarbon group, m and n are each 0
, 1 or 2, and m+n is 1 or more; group or aromatic hydrocarbon group, Rc is a divalent saturated hydrocarbon group having 4 to 10 carbon atoms), alkylene group having 2 or more carbon atoms, phenylene group, cycloalkylene group, aralkylene group, -O-, -S- , -SO2 -, [Chemical formula 3] (where Ar is a carbon number of 6 to 1 which may be substituted with a nucleus)
2 aromatic hydrocarbon group, Z is an alkylene group having 2 to 4 carbon atoms)] and the following general formula [2] [Formula, R3 is a monovalent aliphatic unsaturated hydrocarbon group having 2 to 8 carbon atoms] An electrophotographic photoreceptor characterized in that it is made by crosslinking a polycarbonate resin containing 5 mol % or more of units selected from the group consisting of 1 and 2].