JPH0683078A - Photoconductive composition and electrophotographic sensitive body using the same - Google Patents

Abstract

PURPOSE:To obtain a photoconductive compsn. (coating liquid) less in cohesion and excellent in can-stability by introducing polar groups into copolymers, and to obtain an electrophotographic sensitive body having high sensitivity and stability for repeated use by using the compsn. as the charge generating layer material of the electrophotographic sensitive body consisting of a charge generating layer and a charge transfer layer. CONSTITUTION:This photoconductive compsn. contains vinyl chlorideacryl copolymer resin binder and an org. pigment. This copolymer resin binder is obtd. by copolymn. of three components (a), (b) and (c). (a) 70-95wt.% vinyl chloride monomer, (b) 5-20wt.% vinyl monomer containing hydroxyl groups expressed by formula I, and (c) 0.1-10wt.% polar group-contg. vinyl monomer having polar groups expressed by formula II or III. In the formulae, I, II and III, R1 and R3 are hydrogen atoms or methyl groups, R2 and R4 are bivalent org. residue selected from alkylene, arylene, vinylene and heterocyclic groups, and Z is a polar group.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a photoconductive composition containing a specific vinyl chloride-acrylic copolymer resin binder and an organic pigment, and an electrophotographic photosensitive member comprising a charge generating layer and a charge transporting layer. The present invention relates to an electrophotographic photoreceptor using the above-mentioned photoconductive composition as the charge generation layer.

[0002]

BACKGROUND OF THE INVENTION In the electrophotographic process, the role of the charge generation layer is important and has a great influence on the generation efficiency of charge carriers, the life, injection into the charge transport layer, outflow to the base and the like.

The charge generating layer is basically composed of an organic pigment, which is a charge generating material, and a resin binder. The ratio of the resin binder is as large as 20 to 70%. Have a great impact on. In other words, the basic structure of the resin binder, the molecular weight,
Purity and the like affect basic electrophotographic characteristics of the photoconductor, such as sensitivity, potential characteristics and durability.

In the conventional electrophotographic photoreceptor, light fatigue, potential fluctuation, residual potential sensitivity, etc. are not sufficient, and
As a binder for the charge generation layer, even if the electrophotographic characteristics are good, the dispersibility of the charge generation material may be poor or the storage stability may be poor when used as a coating liquid.

Vinyl chloride-based copolymer resin binders include vinyl chloride-vinyl acetate, vinyl chloride-vinyl acetate-vinyl alcohol, vinyl chloride-ethylene vinyl acetate, vinyl chloride-ethylene copolymer resin, vinyl chloride-acrylic acid. Copolymer resins composed of an ester or ether or an amide-hydroxyl group-containing vinyl monomer are known, but none of them is sufficient in terms of sensitivity, adhesiveness and the like.

[0006]

The object of the present invention is to introduce a polar group into the copolymer to obtain a coating liquid with less aggregation and excellent storage stability, and to obtain a highly sensitive and repetitively stable coating liquid. Another object of the present invention is to provide a photoconductive composition and an electrophotographic photosensitive member, in which the above electrophotographic photosensitive member is obtained and the above-mentioned drawbacks existing in the known art are improved.

[0007]

In order to achieve the above-mentioned object, according to the present invention, (a) 70 to 95% by weight of vinyl chloride monomer (b) a general formula

[Chemical 7] In the hydroxyl group-containing vinyl monomer 5-20% by weight, expressed (wherein, R ₁ represents a hydrogen atom or a methyl group, R ₂ is 1 to the number of carbon atoms
It represents a divalent organic residue selected from the group consisting of 15 alkylene, arylene, vinylene and heterocyclic groups. ) (C) General formula

[Chemical 8] And the general formula

[Chemical 9] 0.1 to 10% by weight of one or more polar group-containing vinyl monomers selected from the group (wherein R ₃ is a hydrogen atom or a methyl group, R ₄ is an alkylene having 1 to 15 carbon atoms, arylene, vinylene and A vinyl chloride-acrylic copolymer resin binder obtained by copolymerizing a divalent organic residue selected from the group of heterocyclic groups, Z represents a polar group),
A photoconductive composition comprising an organic pigment, and an electron using the photoconductive composition as a charge generation layer of an electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer. It is a photographic photosensitive member.

The present invention will be described in detail below. The vinyl chloride monomer of the above (a) in the present invention imparts appropriate hardness and flexibility as a resin binder together with other structural units, and if it is too much, the solubility in a solvent tends to decrease. And the content is preferably 70 to 95% by weight.

The hydroxyl group-containing vinyl monomer (b) in the present invention is a compound having the general formula (1), specifically 2-hydroxyethyl acrylate,
2-vidroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and the like can be mentioned. These are used alone or in combination as a constitutional unit of the copolymer.
If the amount of the hydroxyl group-containing vinyl monomer used is too large, the solvent resistance and moisture resistance of the copolymer will be deteriorated, and if it is too small, the dispersibility will be decreased. Therefore, it is necessary to crosslink with an isocyanate compound, a melamine compound, etc. described later, and the content thereof is preferably 5 to 20% by weight as the content in the copolymer.

The polar group-containing vinyl monomer (c) in the present invention is one or more selected from the group of the above formulas (2) and (3), and specifically, a carboxyl group , At least one of a tertiary amine, a quaternary ammonium salt, a sulfonic acid and its salt, a phosphoric acid and its salt, and a polar group.

The carboxyl group-containing vinyl monomer means a vinyl monomer having a carboxyl group in the molecule,
Specific examples thereof include 5 in a molecule such as acryloxypentenoic acid, succinic acid monoacryloyloxyethyl ester, and phthalic acid monoacryloyloxyethyl ester.
Examples thereof include substances having a single carboxyl group and substances having a plurality of carboxyl groups in the molecule, such as maleic acid and fumaric acid, and maleic acid is particularly preferable in terms of dispersibility.

The amino acid-containing vinyl monomer is a vinyl monomer having an amino group in the molecule, and specific examples thereof include acryl such as dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate and diethylaminoethyl methacrylate. Acid esters, dimethylaminoethyl acrylamide,
Examples thereof include acrylamides such as dimethylaminopropyl acrylamide and acrylic amines.

The quaternary ammonium salt group-containing vinyl monomer is a vinyl monomer having a quaternary ammonium salt group in the molecule, and specific examples thereof include 2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride and methacryloyloxy. Ethyl trimethyl ammonium chloride etc. are mentioned as a suitable example.

The phosphoric acid group-containing vinyl monomer is a vinyl monomer having a phosphoric acid group in the molecule, and examples thereof include acid phosphoxyethyl acrylate, acid phosphoxyethyl methacrylate, and acid phosphoxypropyl acrylate. , 3-chloro-2-acid phosphoroxypropyl acrylate and the like.

The sulfo group-containing vinyl monomer is a vinyl monomer having a sulfo group in the molecule, such as 2-
Acrylamide-2-methylpropanesulfonic acid, 2-
Examples include sodium acrylamido-2-methylpropane sulfonate, acrylic sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, and the like.

These polar group-containing vinyl monomers greatly contribute to the improvement of the adhesiveness to the substrate and the dispersibility of the pigment, but if the content is too large, the moisture resistance of the copolymer deteriorates, and at the time of crosslinking. The reaction is accelerated and the pot life of the paint is shortened, so the content is preferably 0.1 to 10% by weight in the copolymer. The composition of the present invention may further contain ethylene, propylene, vinyl acetate, ethylene vinyl acetate or the like as a constitutional unit of the copolymer, if necessary, and a homopolymer or a copolymer thereof may be used in the present invention. May be used together with the copolymer of Further, another compatible resin such as polyvinyl acetal may be used together. Further, the resin binder according to the present invention may be cross-linked with an isocyanate compound, a melamine compound or the like, if necessary, in addition to the above (a), (b) and (c).

The binder of the charge generation layer preferably has a small content of the binder as a result in order to smoothly move the charge carriers generated in the layer.
From the practical point of view such as adhesion to the substrate, the range is preferably 20% to 70%. The film thickness is 5μ or less, preferably 0.01 to 1.0
A film thickness of μ is good.

The charge generation layer used in the present invention is zinc oxide,
Cadmium sulfide, pyrylium, thiapyrylium dye,
An inorganic or organic dye or pigment selected from charge generating substances such as anthanthuron pigment, perylene, indigo, quinacridone pigment, azo dye, azo pigment and phthalocyanine pigment is used together with the copolymer of the present invention.

The physical constitution of the electrophotographic photosensitive member of the present invention is as follows:
It may be in any known form. A charge generation layer containing a charge dense substance, the vinyl chloride-acrylic copolymer resin binder of the present invention as a main component, and a charge transporting layer containing a charge transporting substance as a main component may be laminated on a conductive support. A photosensitive layer in which a charge generating substance is dispersed in a charge transport layer may be provided. Since these may be provided via the intermediate layer, the following patterns are possible.

I) support / charge generation layer / charge transport layer ii) support / charge transport layer / charge generation layer iii) support / charge transport layer containing charge generation material iv) support / intermediate layer / charge generation Layer / charge transport layer v) support / intermediate layer / charge transport layer / charge generation layer vi) support / intermediate layer / charge transport layer containing charge generation material

Here, the intermediate layer is a barrier layer or an adhesive layer. It is also possible to provide a thin layer on the photoreceptor having the above structure for the purpose of surface protection or the like. The charge-generating substance includes a substance that transports electrons and a substance that transports holes, and both can be used for forming the photoreceptor of the present invention.

The electrophotographic photosensitive member of the present invention can be manufactured by a conventional method according to the technique known for manufacturing a photosensitive member using an organic photoconductive substance. For example, the charge generation layer forming the two-layered photosensitive layer is prepared by finely dividing the charge generation substance alone or with a binder in a suitable solvent and coating it directly or through an intermediate layer on a conductive support, or It is applied on the formed charge transport layer and dried. The size of the fine particles is 5 μm or less, preferably 3 μm or less and optimally 1 μm or less.

The charge-transporting layer can be formed by dispersing or dissolving a charge-transporting substance in a suitable solvent, applying it, and drying. It is preferable to use a binder unless the charge transport material is a substance such as poly-N-vinylcarbazole or poly-N-glycidylcarbazole which also functions as a binder. The amount of the binder used is preferably 0.2-5 times the weight of the charge transport material.
The thickness of the charge transport layer is 1 to 50 μ, preferably 10 to 30 μ.

On the other hand, in order to form a dispersion type photoreceptor layer, a charge transport material may be dispersed or dissolved in the above-mentioned dispersion liquid for charge generation and applied on a conductive support. The charge transport material can be arbitrarily selected, but it is generally preferable to use a binder, except for the case where a substance which itself serves as a binder is used as described above.

When an intermediate layer is provided between the above-mentioned laminated type or dispersion type photoreceptor layer on a conductive support, the intermediate layer may be one or two of a charge generating substance, a charge transporting substance, a binder additive and the like. It is possible to use a commonly used material as a mixture of one or more kinds as long as it does not impair the function of the intermediate layer. The film thickness is 10 μm or less, preferably 1 μm or less.

Other known techniques can be applied to the electrophotographic photosensitive member of the present invention. For example, the photosensitive layer may contain a sensitizer. Suitable sensitizers include Lewis acids and dye pigments that form a charge transfer complex with a photoconductive substance. Further, in order to improve the film-forming property, flexibility, mechanical strength, etc. of the photoconductor layer, a plasticizer, an ultraviolet absorber, an oxidant, etc. may be added as necessary within the range not impairing the electrophotographic photoconductor characteristics aimed at by the present invention. Additives such as inhibitors, materials, adhesion promoters, dispersants and leveling agents may be added.

In the present invention, a charge generation layer, a charge transport layer,
Furthermore, as a method of forming the intermediate layer and the surface layer, dip coating, spray coating, spinner coating,
A coating method such as bead coating, Meyer bar coating, blade coating, roller coating, or curtain coating can be used.

The electrophotographic photosensitive member of the present invention is excellent in charging characteristics, sensitivity characteristics, image forming property, etc., as will be apparent from the following specific examples, and the fluctuations in sensitivity and charging characteristics during repeated use are small and durability is improved. Excel.

Next, the present invention will be specifically described with reference to examples. Comparative Example 1 2 parts of bisazo pigment with the following structure

[Chemical 10] 1 part of vinyl chloride-vinyl acetate-vinyl alcohol copolymer (manufactured by Union Carbide Co., VAGH) and 50 parts of tetrahydrofuran are sufficiently dispersed by a ball mill, and the dispersion is applied on an aluminum plate by a Heuer coater, 120 ° C
Was dried with hot air for 30 minutes to form a charge generation layer having a thickness of 0.3 μm. Furthermore, 5 parts of P-diethylaminobenzaldehyde-N-phenyl-N-benzylhydrazone and a polycarbonate resin (manufactured by Teijin Chemicals, Panlite L125
A solution obtained by dissolving 5 parts of 0) in 70 parts of 1,2 dichloroethane was applied and dried with warm air of 60 ° C. for 3 hours to form a charge transport layer having a thickness of 20 μm. JIS K5400 (General test method for paints) 8.
It was 60/100 when evaluated by the base tape method of 5.2.

The obtained photoconductor was corona-charged by a static method using an electrostatic copying paper tester (SP-428 manufactured by Kawaguchi Denki Seisakusho) so that the surface potential was -700 V, and then placed in a dark place.
After holding it for 10 seconds, it was exposed to a sample surface illuminance of 5.0 lux using a Dangsten lamp as a light source, and the electrophotographic characteristics were evaluated to obtain the following results. _VO (initial charging potential) = -700 V V10 (potential holding ratio in dark place) = 89% E1 / 2 (half-exposure amount) 2.7 Lux · sec

[0031]

Example 1 The same results as in Comparative Example 1 were obtained except that the vinyl chloride-acrylic copolymer resin of the present invention having the following composition was used, and the following results were obtained. Acrylic copolymer resin of vinyl chloride - vinyl chloride: 83.5 2-hydroxyethyl acrylate: 16 methacryloyloxyethyltrimethylammonium - ammonium Niu chloride: 0.5 Adhesion Test: 95/100 electrophotographic characteristics V _O (initial charging potential ) =-700 V V10 (potential holding ratio in the dark) = 85% E1 / 2 (half exposure amount) 1.5 Lux · sec

Comparative Example 2 The same evaluation as in Comparative Example-1 was carried out except that a vinyl chloride-acrylic copolymer resin having the following composition was used, and the following results were obtained. Vinyl chloride - acrylic copolymer resin of vinyl chloride: 85 methyl acrylate: 10 2-hydroxyethyl acrylate: 5 Adhesion Test: 70/100 electrophotographic characteristics V _O (initial charging potential) = - 700 volts V10 (dark Potential holding rate) = 93% E1 / 2 (half-exposure amount) 2.5 Lux · sec

[0033]

Example 2 The same results as in Comparative Example 1 were obtained except that the vinyl chloride-acrylic copolymer resin of the present invention having the following composition was used, and the following results were obtained. Vinyl chloride-acrylic copolymer resin composition Vinyl chloride: 82 2-hydroxypropyl acrylate: 17 Dimethylaminopropyl acrylate: 1 Adhesion test: 90/100 Electrophotographic characteristics V _O (initial charging potential) = -700 V V10 ( Potential retention rate in the dark) = 83% E1 / 2 (half-exposure amount) 1.6 Lux · sec

[0034]

Example 3 Comparative Example-1 except that the vinyl chloride-acrylic copolymer resin of the present invention having the following composition was used and the compound represented by the following general formula (1) was used as a charge transport material.
The same result was obtained and the following results were obtained. Vinyl chloride-acrylic copolymer resin composition Vinyl chloride: 78 2-hydroxyethyl methacrylate: 20 Acid phosphoxyethyl methacrylate: 2 Charge transport material 9-ethylcarbazole-3-carbaldehyde-N,
N- diphenyl hydrazone adhesion test: 90/100 electrophotographic characteristics V _O (initial charging potential) = - 700 volts V10 (voltage holding ratio at a dark place) = 85% E1 / 2 (half decay exposure) 1.8 Lux · sec

[0035]

[Embodiment 4] Charging-discharging of the photoconductor of Embodiment-1
The characteristic change was examined 1000 times. The results are as follows, and it was found that the repeated stability was excellent. First times 100 th 1000 th V _O (bolt) -700 -710 -680 V10 (%) 85 85 83 E1 / 2 (L ux · sec) 1.5 1.5 1.4

When this photoreceptor was corona charged to -7 Kv in a dark place, exposed at a surface illuminance of 30 lux, developed by a magnetic brush method and then transferred, an image with sufficient contrast and clear gradation was obtained. was gotten. Even if this copying test was repeated 10,000 times, the image was good and no change was observed.

[0037]

As described above, according to the present invention, by introducing a polar group into a copolymer, a photoconductive composition (coating liquid) having less aggregation and excellent storage stability can be obtained. This is used as a charge generating layer material of an electrophotographic photosensitive member comprising a charge generating layer and a charge transporting layer to obtain an electrophotographic photosensitive member having high sensitivity and stability.

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[Procedure amendment]

[Submission date] March 23, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

The amino group- containing vinyl monomer is a vinyl monomer having an amino group in the molecule, and specific examples thereof include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate and diethylaminoethyl methacrylate. Examples thereof include acrylic acid esters, acrylamides such as dimethylaminoethyl acrylamide and dimethylaminopropyl acrylamide, and acrylic amines.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

Next, the present invention will be specifically described with reference to examples. Comparative Example 1 2 parts of bisazo pigment with the following structure

[Chemical 10] Vinyl chloride - vinyl acetate - vinyl alcohol copolymer (Union Carbide Co., VAGH) placed 1 part of tetrahydrofuran 50 parts by thoroughly dispersing in a ball mill was applied on an aluminum plate a dispersion in word ear coater ,
The film was dried with hot air at 120 ° C. for 30 minutes to form a charge generation layer having a thickness of 0.3 μm. Then, a solution prepared by dissolving 5 parts of P-diethylaminobenzaldehyde-N-phenyl-N-benzylhydrazone and 5 parts of a polycarbonate resin (manufactured by Teijin Chemicals, Panlite L1250) in 70 parts of 1,2 dichloroethane was applied, It was dried with hot air at 60 ° C. for 3 hours to form a charge transport layer having a film thickness of 20 μm. According to JIS K5400, the photo-sensitive member thus produced is adhered to an aluminum plate.
(General Test Method for Paint) The result was 60/100 as evaluated by the base tape method of 8.5.2.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

[0034]

Example 3 The same results as in Comparative Example 1 were obtained except that the vinyl chloride-acrylic copolymer resin of the present invention having the following composition was used and the following charge transport material was used, and the following results were obtained. . Vinyl chloride-acrylic copolymer resin composition Vinyl chloride: 78 2-hydroxyethyl methacrylate: 20 Acid phosphoxyethyl methacrylate: 2 Charge transport material 9-ethylcarbazole-3-carbaldehyde-N,
N-diphenylhydrazone Adhesion test: 90/100 Electrophotographic characteristics V ₀ (initial charging potential) =-700 V 10 (potential holding ratio in dark place) = 85% E1 / 2 (half exposure amount) 1.8 L _ux・ Second

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

[0035]

[Embodiment 4] Electrostatic copying paper test for the photoreceptor of Embodiment-1
Charging-discharging was repeated 1000 times using the test apparatus SP / 428 to examine characteristic changes. The results are as follows, and it was found that the repeated stability was excellent.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norio Tanaka 2-14-22 Chuohonmachi, Adachi-ku, Tokyo (72) Inventor Masaru Hasegawa 5-52-12 Yoyogi, Shibuya-ku, Tokyo (72) Inventor Nakaji Komiyama 1-12-7 East Ryoke, Kawaguchi City, Saitama Prefecture (72) Inventor Shoichi Takahashi 4-2-8 Ryoke, Kawaguchi City, Saitama Prefecture

Claims (8)

[Claims] (A) Vinyl chloride monomer 70 to 95% by weight (b) General formula: In the hydroxyl group-containing vinyl monomer 5-20% by weight, expressed (wherein, R ₁ represents a hydrogen atom or a methyl group, R ₂ is 1 to the number of carbon atoms
It represents a divalent organic residue selected from the group consisting of 15 alkylene, arylene, vinylene, and heterocyclic groups. ) (C) General formula And the general formula: 0.1 to 10% by weight of one or more polar group-containing vinyl monomers selected from the group (wherein R ₃ is a hydrogen atom or a methyl group, R ₄ is an alkylene having 1 to 15 carbon atoms, arylene, vinylene and A vinyl chloride-acrylic copolymer resin binder obtained by copolymerizing a divalent organic residue selected from the group of heterocyclic groups, Z represents a polar group),
A photoconductive composition containing an organic pigment. 2. The polar group Z in the general formulas (2) and (3) is selected from the group of carboxylic acids, salts thereof, tertiary amines, quaternary ammonium, sulfonic acids, salts thereof, phosphoric acid and salts thereof. The photoconductive composition according to claim 1, which is one. 3. The photoconductive composition according to claim 2, wherein the carboxylic acid according to claim 2 is maleic acid. 4. The photoconductive composition according to claim 1, wherein the weight ratio of the organic pigment to the resin binder is 0.5 / 1.0 or more. 5. As a charge generation layer of an electrophotographic photosensitive member comprising a charge generation layer and a charge transport layer (a) 70 to 95% by weight of vinyl chloride monomer (b) General formula: 5 to 20% by weight of a hydroxyl group-containing vinyl monomer represented by (wherein R ₁ is a hydrogen atom or a methyl group, and R ₂ has 1 to 1 carbon atoms).
It represents a divalent organic residue selected from the group consisting of 15 alkylene, arylene, vinylene, and heterocyclic groups. ) (C) General formula And the general formula: 0.1 to 10% by weight of one or more polar group-containing vinyl monomers selected from the group (wherein R ₃ is a hydrogen atom or a methyl group, R ₄ is an alkylene having 1 to 15 carbon atoms, arylene, vinylene and A vinyl chloride-acrylic copolymer resin binder obtained by copolymerizing a divalent organic residue selected from the group of heterocyclic groups, and Z represents a polar group.
An electrophotographic photoreceptor comprising a photoconductive composition containing an organic pigment. 6. The polar group Z in the general formulas (2) and (3) of claim 5 is a carboxylic acid, a salt thereof, a tertiary amine, a quaternary ammonium, a sulfonic acid, a salt thereof, a phosphoric acid or a salt thereof. The electrophotographic photosensitive member according to claim 5, which is selected from the group. 7. The electrophotographic photosensitive member according to claim 6, wherein the carboxylic acid according to claim 6 is maleic acid. 8. The electrophotographic photosensitive member according to claim 5, wherein the weight ratio of the organic pigment to the resin binder is 0.5 / 1.0 or more.