JPH0418298B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor using a photoconductive photosensitive layer, and more particularly to an electrophotographic photoreceptor comprising an intermediate resin layer between a conductive support and a zinc oxide dispersed photosensitive layer. . An electrophotographic photoreceptor, in which an electrophotographic photosensitive layer consisting of photoconductive zinc oxide dispersed in a resin binder is provided on a conductive support, with an intermediate layer interposed if necessary, can be used as a copying machine or as an electrophotographic lithography material. Widely used. As described in numerous documents and patents, the importance of the intermediate layer is the adhesion between the support and the photosensitive layer, sensitivity, stains in non-image areas, and white spots in image areas (no toner adhesion in dots). In particular, when used as an electrophotographic lithographic material, it may be exposed to dampening water during printing, so an intermediate layer is required to strongly adhere the support and the photosensitive layer. In recent years, more than 10,000 sheets of high-quality electrophotographic printing materials have been produced.
Although it is desired in the printing industry, the adhesion between the support and the photosensitive layer cannot necessarily be said to be perfect using the intermediate layer that has been proposed in the past.
Sometimes it peeled off. As a result of intensive research into this improvement, the inventors of the present invention found that the intermediate layer contains an organic solvent-soluble resin containing polymer (a) as a main component, colloidal silica or colloidal alumina, and an isocyanate compound as components of the intermediate layer. We were able to solve this problem. The present invention will be described in detail below. The conductive support used in the present invention includes metal, conductive treated paper, conductive plastic sheet,
There are plastic sheets with vapor-deposited Al, etc., and paper laminated with conductive plastic. Among these, a support made of paper laminated with electrically conductive plastic is particularly suitable. Conductive plastic laminated papers are constructed by providing a base paper with a polyolefin laminate layer containing a conductive agent on one or both sides. Polyethylene and polypropylene are suitable as the polyolefin, and polyethylene has a density of 0.92 to 0.96, an average molecular weight of 20,000 to 50,000, a softening point of 110 to 130°C, a tensile strength of 130 to 300 Kg/cm ² , and a volume resistivity of 10 ^{to 15} Ωcm or more. Polypropylene has a density of 0.85 to 0.92 and a softening point of 75 to 75.
170℃, tensile strength 280-420Kg/cm ² , volume resistivity
Particularly preferred are those with a resistance of 10 ¹⁵ Ωcm or more, and among these, polyethylene is the most preferred. Such polyolefin inlaminate layers include
The electronically conductive substance is contained so that the volume resistivity of the support finally obtained is 10 ¹⁰ Ω or less.
The volume resistance here is 2.5cm radius on both sides of the support.
This is the resistance value when two circular electrodes are placed facing each other in contact and a DC voltage is applied between the electrodes. This makes it possible to suppress changes in photographic performance due to changes in humidity (particularly when the humidity is low), and to stably obtain a lithographic printing plate with excellent image quality and high printing durability. Particularly preferred electronically conductive materials include French patent No.
2277136 and U.S. Pat. No. 3,597,272, in particular oxides of metals selected from zinc, magnesium, tin, barium, indium, molybdenum, aluminum, titanium, silicon, preferably Fine particles of a crystalline oxide or a composite oxide thereof, or carbon black are used. Among these, conductive carbon black is advantageous because it is inexpensive and easily miscible with polyolefin. Such an electronically conductive substance is used in an amount such that the volume resistance of the support is 10 ¹⁰ Ω or less, more preferably 10 ⁸ Ω or less. The amount used to achieve such a resistance value cannot be determined unconditionally because it varies depending on the type of base paper, polyolefin, and electronically conductive material, but as a general guideline, it is 5% for polyolefin. ~30% by weight. The polyolefin as described above is coated on at least one side, more preferably both sides, of the base paper by a lamination method. As the lamination method, methods well known in the art such as a wet method, a dry method, a hot melt method, and an extrusion method can be used, but the extrusion method is particularly preferred. The extrusion method is a method in which polyolefin is melted, formed into a film, immediately pressed onto a base paper, cooled and laminated, and various devices are known. The thickness of the polyolefin layer laminated in this manner is suitably in the range of 5 to 50 microns. If it is thinner than 5μ, the waterproofness against the base paper will be insufficient, while if it is thicker than 50μ, no further improvement in performance can be expected and the cost will only increase. Therefore, the preferred thickness is 10-30μ. In order to improve the adhesive strength between the base paper and the above polyolefin laminate layer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid ester copolymer, or ethylene-acrylic acid are applied on the base paper in advance. Copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylonitrile-acrylic acid copolymer, ethylene-acrylonitrile-methacrylic acid copolymer, and other polyethylene derivatives are applied, or the surface of the base paper is treated with corona discharge. It is preferable to leave it there. Alternatively, JP-A-49-24126, JP-A-52-36176, JP-A-52-
The surface treatments described in Japanese Patent Publications No. 121683, No. 53-2612, No. 54-111331, and Japanese Patent Publication No. 51-25337 can also be applied to the base paper. On the other hand, as the base paper used in the present invention, any conductive base paper conventionally used in electrophotographic light-sensitive materials can be used, such as ion-conductive materials and those described in US Pat. No. 3,597,272 and French Patent No. 2,277,136. Paper impregnated with electronically conductive substances such as inorganic metal compounds and carbon as described in each specification, or mixed during paper making, and
Synthetic papers described in Publications No. 4239, No. 53-19031, and No. 53-19684 can be used. One of the components of the intermediate layer used in the present invention includes structural units represented by the following formulas () and (),
This is an organic solvent-soluble resin whose main component is a polymer (a) with an acid value of 10 to 100. (R ₁ H or CH ₃ ; R ₂ is H, CH ₃ , C ₂ H ₅ or chloromethyl group; n represents an integer from 1 to 10) (R ₃ represents H or CH ₃ ). The polymer (a) is, for example, a compound represented by the following general formula (), acrylonitrile or methacrylonitrile, an α,β unsaturated carboxylic acid, and if necessary, another addition polymerizable unsaturated compound. elementary, quaternary or multi-component copolymers; (In the formula, R ₁ , R ₂ and n have the same meanings as in the general formula ()) and a compound represented by the above general formula () and acrylonitrile or methacrylonitrile and, if necessary, other addition-polymerizable unsaturated A copolymer prepared by reacting a cyclic acid anhydride with an acid ester is encapsulated into a binary, ternary or multi-component copolymer with a compound. As α,β unsaturated carboxylic acids, acrylic acid,
Methacrylic acid, ethacrylic acid, maleic anhydride,
Methyl maleic anhydride, phenyl maleic anhydride, crotonic acid, itaconic acid, vinyl benzoic acid,
Representative examples include sorbic acid, cinnamic acid, allylsulfonic acid, vinylsulfonic acid, and vinylbenzenesulfonic acid. Other addition polymerizable unsaturated compounds that can be copolymerized as necessary include, for example, acrylic esters,
Examples include acrylamides, methacrylic esters, methacrylamides, allyl compounds, vinyl ethers, vinyl esters, styrenes, and crotonic esters, which are selected from compounds having one addition-polymerizable unsaturated bond. in particular,
For example, acrylic esters such as alkyl acrylates (e.g. methyl acrylate) ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, ethylhexyl acrylate, octyl acrylate, t-octyl acrylate, chloroethyl acrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, glycidyl acrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate); aryl acrylate ( methacrylic acid esters, such as alkyl methacrylates (such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate); , 4-hydroxybutyl methacrylate, 5-
Hydroxypentyl methacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate,
glycidyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl acrylate, etc.), aryl methacrylates (e.g., phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate, etc.); acrylamides,
For example, acrylamide, N-alkylacrylamide (the alkyl group includes, for example, a methyl group,
Examples include ethyl group, propyl group, butyl group, t-butyl group, heptyl group, octyl group, cyclohexyl group, hydroxyethyl group, and benzyl group. ), N-arylacrylamide (such aryl groups include phenyl, tolyl, nitrophenyl, naphthyl, hydroxyphenyl, etc.), N,N-dialkylacrylamide (such as methyl ), N,N-diarylacrylamide (such aryl groups include, for example, phenyl group), N-methyl-N- Phenyl acrylamide, N-hydroxyethyl-N-methylacrylamide, N-2-acetamidoethyl-N-acetylacrylamide, etc.; methacrylamides, such as methacrylamide, N-alkylmethacrylamide (the alkyl group includes a methyl group, ethyl group, t-butyl group, ethylhexyl group, hydroxyethyl group, cyclohexyl group, etc.), N-arylmethacrylamide (such aryl group includes phenyl group, etc.), N,N-dialkylmethacrylamide (The alkyl group includes ethyl group, propyl group, butyl group, etc.), N,N-diarylmethacrylamide (the aryl group includes:
There are phenyl groups. ), N-hydroxyethyl-N-methyl methacrylamide, N-methyl-N
-Phenyl methacrylamide, N-ethyl-N-
phenyl methacrylamide, etc.; allyl compounds,
For example, allyl esters (such as allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetone acetate, allyl lactate, etc.), allyloxyethanol, etc.; vinyl ethers, For example, alkyl vinyl ethers (e.g. hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethylhexyvinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethyl butyl ether, hydroxyethyl vinyl ether, diethylene glycol vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether, etc.), vinyl aryl ether (such as vinyl phenyl ether, vinyl tolyl ether, vinyl chlorophenyl ether, vinyl -2,4-dichlorophenyl ether, vinyl naphthyl ether, vinyl anthrani ether, etc.); vinyl esters, such as vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl valerate, vinyl caproate , vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxy acetate, vinyl butoxy acetate, vinyl phenyl acetate, vinyl acetoacetate, vinyl lactate, vinyl-
β-phenylbutyrate, vinylcyclohexylcarboxylate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, vinyl naphthoate, etc.; styrenes, such as styrene, alkylstyrenes (such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene,
isopropylstyrene, butylstyrene, hexylstyrene, cyclohexylstyrene, decylstyrene, benzylstyrene, chloromethylstyrene, trifluoromethylstyrene, ethoxymethylstyrene, acetoxymethylstyrene, etc.),
Alkoxystyrene (e.g. methoxystyrene,
4-methoxy-3-methylstyrene, dimethoxystyrene, etc.), halogenostyrenes (e.g. chlorstyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromstyrene, dibromstyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene, etc.); crotonic acid esters, e.g.
Alkyl crotonate (e.g. butyl crotonate,
hexyl crotonate, glycerin monocrotonate, etc.); dialkyl itaconates (e.g. dimethyl itaconate, diethyl itaconate, dibutyl itaconate, etc.); dialkyl maleates or fumarates (e.g. dimethyl maleate,
dibutyl fumarate, etc.). In addition, addition polymerizable unsaturated compounds that are generally copolymerizable with the compound represented by the general formula () and acrylonitrile or methacrylonitrile may be used. However, β-hydroxyethyl (meth)
Addition-polymerizable unsaturated compounds having a functional group that reacts with the hydroxyl group of acrylate at room temperature and polyfunctional addition-polymerizable unsaturated compounds having two or more polymerizable vinyl groups per molecule are not desirable. Examples of the cyclic acid anhydride to be half-esterified into a copolymer of the compound represented by the general formula () with acrylonitrile or methacronitrile and, if necessary, other addition-polymerizable unsaturated compounds, include phthalic anhydride, tetrahydrophthalic anhydride,
Hexahydrophthalic anhydride, 3,6-endomethylene-△ ⁴ -tetrahydrophthalic anhydride, 3,6
-Endoxy-△ ⁴ -Tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, succinic anhydride, n-
Examples include dodecyl succinic anhydride. The acid value of the above polymer is preferably 10 to 100, and more preferably
15-40. If the acid value is 100 or more, white spots (a phenomenon in which toner does not adhere in the form of dots) tend to occur in the image area when toner is developed, and if the acid value is less than 10,
Adhesion between the support and the intermediate layer tends to deteriorate. The content of acrylonitrile or methacrylonitrile structural units, that is, structural units represented by the above general formula () in the polymer (a) used in the present invention is 5 to 60% by weight, more preferably 10 to 40% by weight. be. The content of the structural unit represented by the general formula () is preferably 30 to 80% by weight.
It is 40-60% by weight. Outside these ranges, any or several of the evaluation items such as adhesion to the support, white spots in the image area, stains in the non-image area (toner adhesion to the non-image area), and amount of toner adhering to the image area are evaluated. Performance deteriorates due to this. The colloidal silica or alumina used in the present invention preferably has a particle size of 5 x 10 ^-5 to 10 ^-7 cm.
When preparing the intermediate layer coating solution, it is most suitable to use a solution that has been previously dispersed in a dispersion solvent such as methanol. The ratio to the organic solvent soluble resin is the resin solid content.
A solid content of 30 to 300 parts by weight per 100 parts by weight is effective in improving adhesion and reducing stains in non-image areas (hereinafter referred to as "background stains"). Below 30 parts by weight,
Adhesion is weak and scumming may occur300
If the weight part or more is used, adhesion and scumming are good, but the resin intermediate layer after coating and drying becomes brittle and prone to cracking, and the maximum surface potential decreases during charging, resulting in a decrease in toner adhesion. I end up. Particularly preferably 50 to 200 parts by weight. Further, the isocyanate compound may contain two or more isocyanate groups in one molecule, but examples of particularly preferred isocyanate compounds include those whose main component is hexamethylene diisocyanate (product name: Coronate HL, Nippon Polyurethane). company products), The main ingredient is (product name: Desmodyur L)
Bayer products),

[Formula] and

[Formula] (Product name: Desmodyur T-65, Desmodyur T-80, Desmodyur T-100, products of Nippon Polyurethane Co., Ltd.),

Examples include those consisting of the formula (trade name: Millionate MT, a product of Nippon Polyurethane Co., Ltd.). The range of addition amount of isocyanate compound is organic solvent soluble resin.
The amount is preferably 1 to 5 parts by weight per 100 parts by weight, and if it is less than 1 part by weight, the adhesive force is insufficient, and if it exceeds 5 parts by weight, the adhesive force is sufficient, but there is a tendency for scumming to increase. The coating weight of the intermediate layer according to the present invention is 1.5~
10.0 g/m ² is effective, 4.0-6.0 g/m ² is most preferred. If it is less than 1.5 g/m ² , white spots tend to appear in the image area, and if it is more than 10.0 g/m ² , background stains may occur. Inorganic photoconductive substances used in the photosensitive layer of the present invention include cadmium sulfide, zinc oxide, and zinc sulfide, and organic substances include azo pigments such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and Algol Yellow, and indigo pigments. , phthalocyanine pigments, etc. As the binder for the photoconductive pigment, polyurethane resin, muramin resin, silicone resin, alkyd resin, epoxy resin, single or copolymer resin of acrylic acid ester or methacrylic acid ester, polyester, polyamide, epoxy resin, styrene-butadiene copolymer can be used. There are mixtures of polymers, polyethylene, polystyrene, and combinations thereof. Other sensitizing dyes such as rose bengal, auramine, bromophenol blue, and fluorescein are added. The dry coating weight of the photosensitive layer is usually 15 to 35 g/m ² for inorganic materials and 1 to 10 g/m 2 for organic materials.
g/ ^m2 . Examples of the present invention will be described below. Example 1 300g of dioxane was heated to 100°C under a nitrogen stream, and 150g of 2-hydroxyethyl methacrylate,
60g acrylonitrile, methyl methacrylate
A mixture of 79.5 g of methacrylic acid, 10.5 g of methacrylic acid, and 1.2 g of benzoyl peroxide was added dropwise over 2 hours. 15 minutes after the completion of the dropwise addition, 300 g of dioxane and 0.3 g of benzoyl peroxide were added, and the mixture was allowed to react for 4 hours.
After the reaction was completed, the copolymer was diluted with methanol and poured into water to precipitate the copolymer, followed by vacuum drying at 70°C. The acid value of this 2-hydroxyethyl methacrylate copolymer (2) was 20. A 5% aqueous solution of polyvinylbenzyltrimethylammonium chloride was coated at 2 to 3 g/m ² on a high-quality paper having a basis weight of 100 g/m ² as a support, and then dried to obtain conductive treated paper. Ethylene-methyl acrylate-acrylic acid copolymer (weight ratio 65:
30:5) water-based latex with a dry coverage of 0.2
After coating and drying so as to give g/m ² , polyethylene (density 0.92, average molecular weight 22000, softening point 112℃)
A conductive support was obtained by laminating on both sides to a thickness of 25 μm per side by extrusion using pellets (melt index: 3) obtained by melt-kneading 85% of conductive carbon and 15% of conductive carbon. The surface of the polyethylene laminate layer on one side of the support was then
After corona discharge treatment under the conditions of 5 KVA·sec/m ² , a coating solution having the following composition was coated thereon with a wire bar so that the dry coating amount was 4.5 g/m ² and dried to form an intermediate layer. 2-hydroxyethyl methacrylate copolymer
10 parts by weight methanol/silica gel (methanol 30wt
%: Nissan Chemical Co., Ltd. product) 28 〃 Hexamethylene diisocyanate 0.25 parts by weight Methylene glycol 30 〃 Methyl ethyl ketone 18 〃 Methyl cellosolve acetate 42 〃 The particle size of silica in methanol silica sol was measured using a particle size distribution analyzer Nanosizer (UK; Coulter) The center of the particle size distribution was 0.18 μm when measured using
It was hot. A photoconductive layer was provided by coating and drying a coating solution having the following composition on this intermediate layer so that the dry coating amount was 20 g/m ² to obtain an electrophotographic lithographic printing material. Photoconductive zinc oxide (Sazetx 2000 manufactured by Sakai Chemical Industry Co., Ltd.) 100 parts by weight Dianal LR018 (manufactured by Mitsubishi Rayon Co., Ltd.)
35 〃 Rose Bengal 0.1 〃 Fluorescein 0.2 〃 Methanol 10 〃 Toluene 150 〃 The electrophotographic printing material thus obtained was plate-made using an ELP280 plate-making machine (manufactured by Fujifilm). This was desensitized using ELP etchant (manufactured by Fujifilm), and then printed using an offset printing machine.
As a result of printing with Hamada Star 700, 25,000 good prints were obtained. Example 2 A 2-hydroxyethyl methacrylate copolymer (2) was synthesized in the same manner as in Example 1. 2
The composition of the -hydroxyethyl methacrylate copolymer (2) was 2-hydroxyethyl methacrylate/acrylonitrile/methyl methacrylate/methacrylic acid=60/10/27.5/2.5% by weight. Using this as an organic solvent soluble resin,
An electrophotographic lithographic printing material was obtained in the same manner as in Example 1, and as a result of printing, 23,000 pieces of good printed matter were obtained. Example 3 The following resin intermediate layer coating solution was prepared using Ultramid IC (product of BASF), which is a polyamide resin, as an organic solvent-soluble resin. Ultramid IC 10 parts by weight methanol/silica sol (methanol 30wt
%; Nissan Chemical Company product) 22 parts by weight Desmodyur L (manufactured by Bayer) 0.20 〃 Methanol 100 〃 This was mixed with conductive polyethylene in the same manner as in Example 1.
Coated and printed on a laminate support
23,000 good prints were obtained. Example 4 Among the resin intermediate layer components used in Example 1, methanol and silica were replaced with alumina sol and a solution was prepared according to the following formulation. 2-Hydroxy ethyl methacrylate copolymer 10 parts by weight Alumina Sol 200 (water 10wt%; manufactured by Nissan Chemical Co., Ltd.) 80 〃 Millionate MT (manufactured by Nippon Urethane Co., Ltd.)
0.25 〃 Methylene glycol 30 〃 Methyl ethyl ketone 18 〃 Methyl cellosolve acetate 42 〃 These were coated on the same conductive support as in Example 1, and the photosensitive layer was also coated in the same manner to prepare an electrophotographic photoreceptor. When this was plate-made and printed in the same manner as in Example 1, 22,000 good prints were obtained.

Claims (1)

[Scope of Claims] 1. In an electrophotographic photoreceptor constructed by providing an intermediate layer and a photoconductive photosensitive layer in this order on a conductive support, components of the intermediate layer include the following formulas () and (). Contains the structural unit shown and has an acid value of 10 to
An electrophotographic photoreceptor characterized by containing an organic solvent-soluble resin whose main component is a polymer of 100, colloidal silica or colloidal alumina, and a compound containing two or more isocyanate groups in one molecule: (R ₁ is H or CH ₃ ; R ₂ is H, CH ₃ , C ₂ H ₅ or a chloromethyl group; n represents an integer from 1 to 10) ( _R3 represents H or _CH3 ) 2. The conductive support is made by laminating one or both sides of paper containing a conductive agent with polyethylene containing 5 to 30% by weight of carbon to a thickness of 5 to 50 μm. An electrophotographic photoreceptor according to claim 1, which is an electrophotographic photoreceptor.