JPH0317655A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a stable protective layer having high transparency and mechanical strength and preventing deterioration of resolution due to image trailing at the time of high humidity by using a specified bisphenol A polycarbonate for the binder resin of the surface protective layer of the electrophotographic sensitive body. CONSTITUTION:The electrophotographic sensitive body is formed by laminating on a conductive substrate a photoconductive layer and the surface protective layer made of the binder resin of the bisphenol A polycarbonate represented by the formula and having a fine metal or metal oxide powder powder dispersed into it. This surface protective layer can be formed by mixing or dispersing the powder into the resin, and dip or spray coating the photoconductive layer, or forming it into a film and sticking it to the layer, thus permitting the obtained electrophotographic sensitive body not to cause deterioration of resolution under high temperature and high humidity and to exhibit superior image characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor provided with a specific surface protective layer.

[Prior Art] Conventionally, photoreceptors for frame photography have been prepared by providing a photoconductive layer mainly made of selenium or selenium alloy on a conductive support, or by using inorganic photoconductive materials such as zinc oxide or cadmium sulfide. Some methods are generally known, such as those dispersed in a binder, those using organic photoconductive materials such as poly-N-vinyl rubazole and trinitrofluorenone or azo pigments, and those using non-quality silicone.

The demand for the reliability of these photoreceptors to maintain high image quality over a long period of time is increasing year by year. However, when the photoconductive layer is exposed, damage caused by corona discharge during the charging process and physical or chemical damage caused by contact with other members during the copying process shorten the life of the photoreceptor.

As a method for eliminating such drawbacks, a technique is known in which a protective layer is provided on the surface of the photoreceptor. Specifically, Hohiro (Special Publication No. 38-154), which provided an organic film on the surface of the photosensitive layer,
46), Hohiro who provides an inorganic oxide (Special Publication Publication No. 43-14)
517), a method of laminating an insulating layer after providing an adhesive layer (Japanese Patent Publication No. 43-27591), or a plasma CVD method,
A method of laminating a-Si layer, a-Si:N:H layer, a-St:O:H layer, etc. by photo-CVD method etc.
179859, Japanese Patent Application Laid-Open No. 59-58437).

However, the protective layer has a high electrophotographic resistance (10I4Ω
- CI1 or higher) causes problems such as an increase in residual potential and accumulation during repetition, which is undesirable from a practical standpoint.

A method of using a photoconductive layer as a protective layer as a technique to compensate for the above drawbacks (Japanese Patent Publication No. 48-38427, Japanese Patent Publication No. 43-18198)
, Special Publication No. 48-10258, U.S. Patent No. 2901
348), a method of adding a transfer agent such as a dye or a Lewis acid into the protective layer (Japanese Patent Publication No. 44-834, Japanese Patent Application Laid-Open No. 1986-53)
-133444), or a method of controlling the resistance of a protective layer by adding metal or metal oxide fine particles (Japanese Patent Application Laid-open No. 1983-133-
3338) etc. have been proposed.

However, in such a case, light is absorbed by the protective layer and the amount of light reaching the photosensitive layer is reduced, resulting in a problem that the sensitivity of the photoreceptor is reduced.

From this point of view, as proposed in JP-A No. 57-30846, by dispersing fine metal oxide particles with an average particle size of 0.3 μm or less as a resistance control agent in the protective layer, it is possible to substantially reduce the There is a way to make it transparent. A photoreceptor having such a protective layer has less decrease in sensitivity, has increased mechanical strength of the protective layer, and has improved durability. However, it has been found that when used for a long period of time, it has the disadvantage that image deletion occurs in environments with high humidity or rapid changes in humidity.

This is because discharge products (nitrate ions, ammonium ions, etc.) generated by corona discharge are adsorbed on the surface of the protective layer.
When this discharge product absorbs moisture from the atmosphere, the electrical resistance toward the surface of the protective layer decreases, resulting in static electricity? ? This is because the I image cannot be maintained. As a method for preventing this image blurring, a method of water-repellent treatment of metal and metal oxide fine powder dispersed in the protective layer has been proposed, as proposed in JP-A-295008/1985, but the effect is not sufficient. , side effects such as an increase in residual potential occur.

Furthermore, as disclosed in JP-A No. 63-43182, a protective layer mainly composed of a binder resin having a water contact angle of 80° or more has been proposed, and the binder resin may be polyethylene, polybutylene, polystyrene, or fluororesin. , polyacrylate,
Although polycarbonate and the like have been disclosed, they are not sufficiently effective, and no technology to solve this problem has been completed yet.

[Problems to be Solved by the Invention] The present invention provides electrophotography with high image quality and durability by providing a stable protective layer that has high transparency and strong strength and does not cause a decrease in resolution due to image blurring in high humidity. The purpose is to provide a photoreceptor.

[Means for Solving the Problems] The structure of the present invention for solving the problems described above has a photoconductive layer and a surface protective layer on a conductive support, as described in the claims. An electrophotographic photoreceptor in which the material of the protective layer is a binder resin in which fine powder of metal or metal oxide is dispersed, characterized in that the binder resin is a bisphenol A polycarbonate resin represented by the following general formula. This is a photoreceptor for electrophotography.

general formula however, n is an integer from 50 to 400.

The metal or metal oxide fine powder used in the present invention includes metals such as copper, tin, aluminum, and indium;
Alternatively, metal oxide fine powders such as tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, and tin-doped indium oxide can be used.

Two or more of these metal or metal oxide fine powders may be mixed. The average diameter of these fine powders is 0.3μ
m or less, preferably 0.1 μm or less, from the viewpoint of transmittance of the protective layer.

The specific resistance of the protective layer is 10' to 1o1]Ωcan,
The film thickness is 0.5 to 30 μm, preferably 1-10 μm. If the thickness is less than 0.5 μm, the mechanical strength of the protective layer will be weak and the abrasion resistance will be low, making the protective layer ineffective for long-term use, and if it exceeds 30 μm, electrical GI will accumulate in the protective layer. Residual potential increases when used repeatedly.

This protective layer is formed by mixing or dispersing metal or metal oxide fine powder in the polycarbonate resin, dipping or spray coating on the photoconductive layer, or forming the mixture into a film and then adhering it.

Furthermore, as a photoconductive layer, Se, Se-Te, AS2Se can be used.
), etc., II- such as ZnO, CdS, CdSe, etc.
Used are particles of a Vl group compound dispersed in a resin, an organic photoconductive material such as polyvinylcarbazole, or a-Si.

There are no particular restrictions on the structure of the photoconductive layer, and it may be a single layer or a stack of a charge generation layer and a charge transport layer.

Further, an adhesive layer for increasing adhesion and an electrical barrier layer for preventing charge injection may be provided between the protective layer and the photoconductive layer.

As the conductive support, a conductor or an insulator treated for conductivity is used. For example, A1, Ni, Fe, Cu,
AI on an insulating substrate such as metal or alloy such as Au, polyester, polycarbonate, polyimide, glass, etc.
Examples include thin films of metals such as , Ag, and Au, or conductive materials such as In203 and Sn02, and paper that has been subjected to conductive treatment.

Further, there are no particular restrictions on the shape of the conductive support, and plate-like, drum-like, or belt-like ones may be used as required.

The actual cutting in the present invention will be shown below.

[Example] Aluminum raw tube (80■φX 340IIIL)
After pretreatment (cleaning), the substrate was placed in a vacuum evaporation apparatus, and the AszSe3 alloy was subjected to resistance heating evaporation under the following conditions so that the film thickness on the support was 60 μm, thereby producing a photoconductive layer.

Vapor deposition conditions Vacuum degree: 3X to' Torr Support temperature: 200°C Boat temperature: 450°C Next, a silicone resin (Toray Silicone Co., Ltd. v AY42-441) glue groin solution was applied to the photoconductive layer so that the thickness after drying was 0.2 μm. An intermediate layer was prepared by applying the following coatings to form an intermediate layer.

Furthermore, 5 parts by weight of bisphenol A1 polycarbonate resin represented by the following structural formula (1), 3 parts by weight of tin oxide, and 12 parts by weight of cyclohexanone were added thereto, and dispersed in a ball mill for 100 hours to obtain a dispersion branch.

Furthermore, 40 parts by weight of dichloromethane was added to this dispersion,
A 3 μm protective layer was applied by spray coating to prepare an electrophotographic photoreceptor.

However, n is approximately 150.A photoreceptor was prepared in the same manner as in the Example, except that the binder resin of Comparative Example was replaced with a bisphenol Z polycarbonate resin represented by the following structural formula (II).

However, n is approximately 350. Using the photoreceptor of the present invention obtained as described above and the photoreceptor for comparison, the number of copies was 10,000 at 30°C and 9a% environment.
A 0-image test was conducted and the resolution was rated at 5. These mucilages are shown in Table 1.

Table 1 From these results, it can be seen that the present invention exhibits good image characteristics without causing a decrease in resolution in an environment of high temperature and high humidity.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain an electrophotographic photoreceptor having a highly reliable protective layer that can prevent image fading that occurs under high humidity during long-term use.

Claims (1)

[Scope of Claims] Electrophotography comprising a photoconductive layer and its surface protective layer on a conductive support, and the material of the surface protective layer is a binder resin in which fine powder of metal or metal oxide is dispersed. In the photoreceptor for
A photoreceptor for electrophotography, characterized in that the binder resin is a bisphenol A polycarbonate resin represented by the following general formula. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ However, n is an integer from 50 to 400.