JPH02207268A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve durability by using a layer contg. an alcohol-soluble resin and a finely powdered electrically conductive metal compd. as a protective layer. CONSTITUTION:A photosensitive layer 2 and a protective layer 4 are formed on a substrate 1 and an alcohol-soluble resin such as polyvinyl butyral or polyvinylprovidine and a finely powdered electrically conductive metal compd. such as tin oxide or vanadium oxide are incorporated into the protective layer 4. An electrophotographic sensitive body having high durability and resistance to surface wear and scratch due to friction and giving a high grade image free from blur is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor having a protective layer on a photosensitive layer.

2. Description of the Related Art Electrophotographic copying machines are becoming faster and faster year by year, and machines that can copy a variety of paper sizes are being developed. Along with this, high performance photoreceptors are required to meet this demand.

In addition, in recent years, functionally separated electrophotographic photoreceptors in which photoreceptor functions are shared among multiple members have improved charge retention, cyclic stability,
Many proposals have been made to improve electrophotographic properties such as photoresponsiveness, spectral properties, and mechanical strength. One of them is drilled or improved in durability.

Durability can be roughly divided into durability of electrophotographic physical properties such as sensitivity, residual potential, charging ability, and image blur, and mechanical durability such as wear and scratches on the photoreceptor surface due to friction. Poor mechanical durability is a major factor determining the lifespan of a photoreceptor, and the development of a photoreceptor with excellent mechanical durability is desired. In addition, the surface layer of the photoreceptor is a factor that causes image quality deterioration, such as adhesion of low-resistance substances generated by ozone generated during corona charging, or filming and fusion due to poor toner cleaning, especially at high temperatures. In addition to the above-mentioned mechanical durability, mold releasability against various deposits is also required.

In order to meet these requirements, we have improved mechanical durability against abrasion and scratches, added mold releasability and potability, and added a protective layer to the surface of the photoconductor to prevent toner fusion. It is known that it is effective when provided in

Problems to be Solved by the Present Invention However, in such an electrophotographic photoreceptor, sensitivity may decrease due to its electrical characteristics, and when charging exposure is repeated, the bright area potential fluctuates and stability may deteriorate. At present, problems such as chipping occur, making it difficult to put into practical use photoreceptors that are highly durable, highly sensitive, and have stable characteristics during repeated use.

The present invention provides an electrophotographic photoreceptor having high durability that meets the above requirements. That is, an object of the present invention is to provide an electrophotographic photoreceptor that has high durability and is resistant to surface abrasion and scratches caused by friction, and is capable of producing high-quality images without image blurring. It's about doing. Another object of the present invention is to provide an electrophotographic photoreceptor that has high durability and does not accumulate residual potential during repeated electrophotographic processes and can always produce high-quality images.

Means for Solving the Problems The present inventors have discovered that the above objects can be achieved by using specific resins and metal compounds on the surface of the photosensitive layer, and have completed the present invention.

The present invention is an electrophotographic photoreceptor having a photosensitive layer and a protective layer on a substrate, and is characterized in that the protective layer contains at least an alcohol-soluble resin and a finely divided conductive metal compound.

The present invention will be explained in detail below.

The drawing is a schematic cross-sectional view for explaining the layer structure of the electrophotographic photoreceptor of the present invention. 1 and 2 show a case where the photosensitive layer is a single layer WI structure, and in FIG. 1, a photosensitive layer 2 and a protective layer 4 are provided on a substrate 1, and
In FIG. 2, an undercoat layer 3 is further provided between the conductive substrate 1 and the photosensitive layer 2. Further, in each of FIGS. 3 to 8, a photosensitive layer having a laminated layer 'M4 structure in which a charge generation layer 21 and a charge transport layer 22 are functionally separated is formed on the substrate 1, and the photosensitive layer is further formed on the surface. A protective layer 4 is provided. 5 and 6 show a case in which an undercoat layer 3 is provided on the substrate 1, and in FIGS. A case in which an intermediate layer 5 is provided is shown.

As the substrate, any known substrate used in electrophotographic photoreceptors can be used.

An undercoat layer may be provided on the substrate as desired. Materials for forming the undercoat layer include polyvinyl butyral, silane coupling agent, polyvinylpyridine, polyvinylpyrrolidone, phenol resin, polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, and ethylene acrylate copolymer. Known materials such as , casein, polyamide, glue, and seratin can be used.

They are each dissolved in a suitable solvent and applied onto the substrate. The thickness of the undercoat layer is generally 0.2 to 2 μm.
is set to

In the present invention, the photosensitive layer may have a single layer structure or a laminated structure. In the case of a single layer structure, a dye-sensitized ZnO photosensitive layer, a C, dS photosensitive layer, a photosensitive layer in which a charge generating substance is dispersed in a charge transporting substance, etc. can be used.

In the case of a laminated structure, a charge generation layer and a charge transport layer may be separated in function. The charge generation layer and the charge transport layer may be stacked on the substrate in any order.

The charge generation layer is formed by dispersing a charge generation substance in a binder resin as required. Examples of charge generating substances include selenium and selenium alloys; CdS, CdSe, Cd5Se.
, ZnO, ZnS, and other non-sightseeing conductors; metal or metal-free phthalocyanine pigments: azo pigments such as bisazo pigments and trisazo pigments; squareium compounds eA niazulenium compounds; perylene pigments; indigo pigments; quinacridone pigments; polycyclic quinone pigments cyanine dyes: xanthene dyes: charge transfer complexes consisting of poly N-vinylcarbazole and trinitrofluorenone; eutectic complexes consisting of pyrylium salt dyes and polycarbonate resins.

As the binder resin, well-known ones such as polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylic acid ester polymer or copolymer, #acid vinyl polymer or copolymer, cellulose ester or ether, polybutadiene, polyurethane are used. , epoxy resin, etc. are used.

The charge transport layer is composed mainly of a charge transport substance.

The charge transfer substance is not particularly limited as long as it is transparent to visible light and has charge transport ability, and specific examples include imidazole, pyrazoline, thiazole, oxadiazole, and oxazole. , hydrazone, ketazine, azine, carbazole, polyvinylcarbazole, etc., and derivatives thereof, triphenylamine derivatives, stilbene derivatives, benzidine derivatives, etc. A binder resin may be used in combination as necessary. Examples of the binder resin include polycarbonate, polyarylate, polyester, polystyrene, styrene-acrylonitrile copolymer, polysulfone, polymethacrylate ester, and styrene-nysdel methacrylate. Copolymers etc. can be opened.

An intermediate layer may be formed on the photosensitive layer, if desired. The intermediate layer is made of a material that serves as a charge injection blocking layer. Examples of polymer compounds include epoxy resin, polyester resin, polyamide resin, polyurethane resin, nitrified cotton, vinylidene chloride resin, silicone resin,
Fluororesins, cured products of zirconium alkoxide and silane coupling agents, etc. can be used, and examples of inorganic compounds include zinc oxide, zirconium oxide, silica, Se
, S, AS 203, etc., can be formed by a known method, and its thickness is set to 3 μm or less, preferably 1 μm or less.

A protective layer is formed on the surface of the electrophotographic photoreceptor.

In the present invention, the alcohol-soluble resin used for the protective layer includes polyvinyl acetals such as polyvinyl butyral, polyvinylpyridine, polyvinylpyrrolidone,
Examples include polyvinyl methyl ethers, phenol resins, polyvinyl alcohol, polyN-vinylimitazole, polyethylene oxide, cellulose ethers, polystyrene, polyacrylamide, polyamide resins, and the like.

Solvents for dissolving these resins include alcohols such as methanol, ethanol, butanol, propatool, mixed solvents of these, water, benzene, toluene, xylene, chloroform, #ethyl acid,
A mixed solvent to which pencil alcohol, tetrahydrofuran, dimethylformamide, etc. are added as necessary can be used.

In the present invention, the first advantage of using an alcohol-soluble resin is that since alcohol can be used as a solvent, the dispersion stability of the particulate conductive metal compound is good. The second advantage is that when the protective layer is laminated, there is less harm to the underlying photosensitive layer.

That is, by using alcohol as a solvent, erosion of the photosensitive layer and diffusion of the material constituting the photosensitive layer from the photosensitive layer can be prevented.

Examples of the particulate conductive metal compound used in the present invention include metal oxides such as tin oxide, vanadium oxide, titanium oxide, zinc oxide, and indium oxide. Specifically, tin oxides include S-1 and T-1 manufactured by Mitsubishi Metals ■, and product name: ELCOHTL- manufactured by Catalyst Kasei ■.
Examples of the vanadium oxide include vanadium trioxide, vanadium dioxide, vanadium trioxide manufactured by Shinko Kagaku (■), and ET300W (manufactured by Ishihara Sangyo ■) as the titanium oxide.

These metal oxides preferably have an average particle size of 0.3 μm or less.

The mixing weight ratio of the alcohol-soluble resin and the particulate conductive metal compound is 1:9 to 8:2, preferably 2-8 to 8:2.
A range of 6:4 is suitable. If the proportion of the alcohol-soluble resin is less than the above range, the mechanical strength of the protective layer will be significantly reduced, while if the proportion is greater than the above range, electrical properties will deteriorate, including an increase in residual potential.

The thickness of the protective layer is 0.1 to 10 μm, preferably 2 to 6 μm.
A range of μm is suitable. If the film thickness is thinner than the above range, the mechanical strength of the protective layer, including its abrasion resistance, will decrease, while if it is thicker, it will lack cyclic stability and environmental stability in terms of electrophotographic properties. .

In order to form the protective layer in the present invention, it is necessary to adjust the dispersion coating liquid. A conductive metal compound is added to and mixed with the resin solution containing alcohol as a main solvent and uniformly dispersed. As a dispersion method, general dispersion means,
i.e. paint shaker, homogenizer, ultrasonic,
A ball mill, sand mill, attritor, roll mill, etc. can be used.

To apply the obtained dispersion, coating methods can be used, for example, dip coating method, spray coating method, blade coating method, spinner coating method, beat coating method, curtain coating method, but dip coating method This is most suitable for taking advantage of the features of the present invention. Drying at 10-100°
C2 Preferably at a temperature in the range of 20 to 150°C for 5 to 5 minutes
It can be carried out in a blow dryer or under static drying for a period of time, preferably from 10 minutes to 2 hours.

Example 1 Aluminum pipe (outer diameter 84n++n, length 360m
Using m) as a substrate, a 0.5 μm thick undercoat layer of a polyvinyl acetal resin having the following structural formula (5% n-propyl alcohol/water mixture (mol %)) was provided thereon.

A solution prepared by dissolving 87 parts by weight of granular trigonal selenium and 13 parts by weight of vinyl chloride-vinyl acetate copolymer (trade name: Trusion Vinyl VMCH, manufactured by Union Carbide) in 200 parts by weight of n-butyl acetate was mixed into an attritor. The mixture was dispersed for 24 hours. Next, 57 parts by weight of n-butyl #acid was added to 30 parts by weight of this dispersion to dilute it, thereby preparing a dip coating solution.

This dip coating solution was applied onto an aluminum pipe on which an undercoat layer had been formed. That is, 100+ in a dip coating bath.
It was pulled up at a speed of nm/min and dried by heating at 100° C. for 5 minutes to form a charge generation layer with a thickness of 0.1 μm.

Next, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4
10 parts by weight of '-diamine, 10 parts by weight of polycarbonate Z resin
Parts by weight were dissolved in 80 parts by weight of monochlorobenzene to prepare a charge transport coating solution. This liquid was applied onto the charge generation layer and dried with hot air at 100° C. for 60 minutes to form a charge transport layer with a thickness of 25 μm.

Prepare the coating solution for the protective layer as follows.

45 parts by weight of a mixed solvent of 220 parts by weight of methanol, 150 parts by weight of n-butanol and 40 parts by weight of water in advance.
To a resin solution in which parts by weight of polyamide resin (trade name: T-8 nylon, manufactured by Unitika ■) were dissolved, 55 parts by weight of tin oxide (s-i, manufactured by Mitsubishi Metals ■) was added and mixed.

1/16 inch diameter stainless steel shot was added to this and dispersed in pane 1 using a shaker for 4 hours. This dispersion coating solution was applied onto the charge transport layer by dip coating, and dried at 100° C. for 10 minutes to form a protective layer with a thickness of 5 layers.

The electrophotographic photoreceptor manufactured in this way was installed in a copying machine (a modified copying machine 5030 manufactured by Fuji Serox ■), and after adjusting the dark area potential V to be 1800V, 2erc+/
-The bright area potential V[ was measured when exposure was applied. Thereafter, a durability test of 100,000 copies was conducted, and changes in dark potential VD and light potential VL were measured.

At the same time, image quality was evaluated. The results are shown in Table 1.

Example 2 A phenol resin (trade name: Pryophen J-325, manufactured by Dainippon Ink & Chemicals, non-volatile content: 59%) was prepared in advance.
%) was mixed with 220 parts by weight of methanol and 150 parts by weight of n-butanol to prepare a resin solution. To this was added and mixed 55 parts by weight of tin oxide (T-1, manufactured by Mitsubishi Metals@) to prepare a dispersion coating liquid for a protective layer in the same manner as in Example 1.

An electrophotographic photoreceptor including a protective layer was prepared in the same manner as in Example 1.
evaluated. The results are not shown in Table 1.

Example 3 A resin solution was prepared by mixing 45 parts by weight of polyvinyl butyral resin (trade name: S-LEC BM-1, manufactured by Tansui Chemical Industry Co., Ltd.) with 270 parts by weight of methanol and 150 parts by weight of n-butanol. To this, 55 parts by weight of titanium oxide (ET30014, manufactured by Ishihara Sangyo ■) was added and mixed, and the mixture was dispersed and prepared in the same manner as in Example 1 to obtain a dispersion coating liquid for a protective layer. An electrophotographic photoreceptor including a protective layer was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 An electrophotographic photoreceptor was produced and evaluated in the same manner as in Example 1 except that the protective layer was not provided.

The results are shown in Table 1.

Comparative Example 2 In advance, 45 parts by weight of polyurethane resin (Rethane 4000, manufactured by Kansai Paint Co., Ltd.) was added to Cellosolve Acetate) 41
A resin solution was prepared by dissolving 0 parts by weight.

In the same manner as in Example 1, the above resin was used instead of the polyamide resin, and 55 parts by weight of tin oxide (1 part by weight) was similarly added and mixed. An electrophotographic photoreceptor including a protective layer was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Effects of the Invention Since the electrophotographic photoreceptor of the present invention uses a protective layer containing an alcohol-soluble resin and a finely divided conductive metal compound, it is resistant to surface wear and scratches caused by friction. It is highly durable, and has the excellent effect of not accumulating residual potential in repeated electrophotographic processes, so that high-quality images without image blurring can always be obtained.

[Brief explanation of the drawing]

1 to 8 are schematic cross-sectional views of the electrophotographic photoreceptor of the present invention, respectively. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Photosensitive layer, 21... Charge generation layer, 22... Charge transport layer, 3... Undercoat layer, 4...
Protective layer, 5.--Intermediate layer. Patent applicant Fuji Serox Co., Ltd. Agent
Patent Attorney Tsuyoshi LiquidbeFigure 2Figure 4

Claims (1)

[Claims] (1) An electrophotographic photoreceptor having a photosensitive layer and a protective layer on a substrate, wherein the protective layer contains at least an alcohol-soluble resin and a particulate conductive metal compound.