JPH0146871B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an electrophotographic photoreceptor having a surface protective layer used in an electrophotographic method known as the Carlson method. Photoreceptors in which ZnO powder is dispersed in an organic resin binder have long been put to practical use as photoreceptors for electrophotography because they are inexpensive, non-toxic, and can be dye-sensitized. However, when a ZnO photoreceptor is used repeatedly, discoloration of the dye, dielectric breakdown of the photosensitive layer, clogging of the toner, etc. occur, and the lifespan of the ZnO photoreceptor is limited to about 1,000 copies at most.
In order to improve this drawback, many attempts have been made to provide a protective layer on the surface of the photoreceptor, but when forming the protective layer by coating, the protective layer solution is
Penetrates inside the photosensitive layer and attacks the binder,
It was inevitable that the contact conditions between the ZnO particles would deteriorate, leading to deterioration of the characteristics. Attempts have also been made to provide a sealing layer to prevent penetration, but no effective means have been found.

Further, electrophotographic photoreceptors made of organic semiconductors have features such as flexibility and high sensitivity, but are unsatisfactory in terms of mechanical strength. Attempts have been made to provide a surface protective layer to improve this problem, but when the protective layer is applied with a solution, the organic semiconductor is attacked and the characteristics deteriorate.

Additionally, as a conductive protective layer that can be used in the Carlson process, there is a method of applying a resin film containing fine metal oxide particles dispersed in a binder resin to the surface of the photoconductor using a spray or dip coating method. However, since a coating liquid in which metal oxide powder is dispersed in a resin solution is used during coating, the dispersion of metal oxide particles within the resin film after coating is difficult in the film thickness direction. The metal oxide particles become non-uniform in the film, the secondary bonding of the metal oxide particles within the film is insufficient, the formation of an electric path does not go well, and a favorable state for imparting conductivity to the resin film is not necessarily obtained. Since the metal oxide particles are dispersed, it has been difficult to obtain a protective layer with a uniform thickness.

The present invention improves the conventional method of manufacturing an electrophotographic photoreceptor, and provides a surface protective layer on the electrophotographic photosensitive layer so as not to adversely affect its properties, and the surface protective layer has an appropriate resistance value. The present invention provides a material that is transparent and can be used in an electrophotographic method known as the Carlson process.

The surface protective layer of the photoreceptor of the present invention has excellent mechanical strength and is effective in significantly extending the life of the photoreceptor by protecting the photoreceptor from contamination by toner and chemical reactions caused by corona.

In addition, its surface protective layer is thermally and chemically stable.
It also has excellent solvent resistance, and the surface can be cleaned with a solvent.

The present invention is based on the discovery that a film obtained by dispersing metal oxides with an average particle size of 0.1 μm or less in a heated molten resin has appropriate resistance and transparency. a support, a photoconductive layer on the support, and an average particle size on the photoconductive layer
The present invention relates to a method for producing an electrophotographic photoreceptor comprising a protective layer in which a metal oxide of 0.1 μm or less is dispersed in a resin.

The details of the present invention will be described below.

As shown in FIG. 1, the electrophotographic photoreceptor of the present invention is manufactured by coating a photoconductive layer 2 on a film 1 in which a metal oxide with an average particle size of 0.1 μm or less is dispersed in a resin, and then applying a photoconductive layer 2. This method is characterized by adhering or coating the conductive support 4 from the electroconductive layer side. Metal oxides include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide,
Bismuth oxide, tin-doped indium oxide,
Antimony-doped tin oxide, zirconium oxide, etc. can be used. Polyester, polycarbonate, fluororesin, cellulose, polyethylene, polypropylene, vinyl chloride, etc. can be used as the resin film in which metal oxide fine particles are dispersed. By extruding it into a shape and then biaxially stretching it, a product with excellent mechanical strength can be obtained. The thickness of the metal oxide dispersed film is preferably between 2 and 20 μm. In order to apply the photoconductive layer to the metal oxide dispersed film, known techniques such as a spray method, a diping method, a blade method, etc. can be used. Photoconductive materials include inorganic photoconductors such as ZnO and CdS, organic photoconductors such as phthalocyanine pigments and diazo pigments dispersed in an organic resin binder, or polymeric organic semiconductors such as polyvinylcarbazole, or polymeric organic semiconductors such as polyvinylcarbazole. It is possible to use dye-sensitized materials, and also materials in which organic low-molecular semiconductors such as triphenylmethane derivatives and pyrazoline derivatives are molecularly dispersed in a resin binder.

The conductive support is provided by coating a conductive substance such as carbon dispersed in a resin, or by bonding a metal such as Al or conductive treated paper with an adhesive. At this time, it is necessary that the conductive layer or adhesive does not contain any solvent that would attack the photoconductive layer. For this purpose, the conductive layer may be applied in the form of an aqueous solution, a water-based adhesive, or a solvent-free adhesive may be used. The thickness of the metal oxide dispersed layer is preferably between 2 and 20 μm, particularly between 5 and 15 μm.

Desired transparency can be obtained if the average particle size of the metal oxide is 0.1 μm or less. The amount of metal oxide added to the resin is preferably between 3 and 65% by weight.

The thickness of the photoconductive layer varies depending on the type of material, but is preferably between 4 and 80 μm.

According to the method for manufacturing an electrophotographic photoreceptor of the present invention,
Metal oxide particles are dispersed in a relatively high viscosity resin that is directly heated and melted without using a solvent, and this is formed into a film as a protective layer, and a photoconductive layer is provided on this layer by coating. Unlike the conventional method, the dispersion state of the metal particles in the protective layer does not change during the production of the photoreceptor, and therefore, the film is transparent, has an appropriate resistance value, has a uniform thickness, and can be used for both the protective layer and the photoconductive layer. A photoreceptor with a protective layer that does not accumulate charge at the interface can be easily obtained.

The present invention will be explained below with reference to Examples.

Example 1 Powder prepared by fusing antimony oxide to tin oxide with an average particle size of 0.05 μm in a heated molten state to a polyethylene terephthalate resin obtained by heating polycondensation of dimethyl ester of terephthalic acid and ethylene glycol in the presence of a catalyst. Disperse 25% by weight. This is formed into a sheet using an extrusion method, then rapidly cooled, heated again, stretched approximately three times in both length and width directions at 90° to 120°C, and further heat-fixed at around 250°C to obtain a film with a thickness of 8 μm. Ta.

Next, zinc oxide powder (manufactured by Sakai Chemical Co., Ltd., Sazex4000)
80 parts by weight, acrylic resin (Dianal HR-
116, manufactured by Mitsubishi Rayon Co., Ltd.), 0.1 parts by weight of rose bengal, 10 parts by weight of ethyl alcohol, and 75 parts by weight of toluene were dispersed in a ball mill for 16 hours, and then applied to the above film by date ping.
After drying, a photosensitive layer with a thickness of 20 μm was obtained. Furthermore, after applying an aqueous solution of polyvinyl alcohol to the photosensitive layer, a polyester film on which Al was vapor-deposited was adhered and dried to obtain an electrophotographic photoreceptor. Using this, 20,000 good images were obtained by repeating the steps of negative charging, image exposure, development, transfer, and cleaning according to the usual electrophotographic method. During this period, no background fog due to desensitization was observed. In contrast, when images were formed in the same manner using a ZnO photoreceptor without a surface protective layer for comparison, an increase in fog was observed in approximately 800 images.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the method for manufacturing the electrophotographic photoreceptor of the present invention. Codes in the figure: 1... Metal oxide dispersion layer; 2... Photoconductive layer; 3... Adhesive layer; 4... Conductive support;
5... Release film.

Claims (1)

[Claims] 1. A method for producing an electrophotographic photoreceptor, which includes a step of dispersing a metal oxide having an average particle size of 0.1 μm or less in a resin in a heated molten state to obtain a transparent resin film, and a step of applying a photoconductive layer to the resin film. Production method.