JPH02167558A - Image flowing preventing method - Google Patents

Abstract

PURPOSE:To prevent nitric acid ions, ammonium ions, etc., from being desorbed to the surface of a protection layer and to prevent an image flowing by forming a thin film of petroleum-based aliphatic hydrocarbon on the surface of the surface protection layer. CONSTITUTION:An electrostatic charger 2, an exposure slit 3, a development part 4, a transfer charger 5, a cleaning unit 6, and a liquid film formation unit 7 are arranged around a photosensitive drum 1 in this order. Then a petroleum-based aliphatic hydrocarbon isoperm H is supplied to the protection layer surface of the liquid film formation unit 7 through a sponge roller 8, a blade 9 forms the thin liquid film, and this process is carried out in each copying process. Consequently, the protection layer surface is always covered with the liquid film to prevent the adsorption discharge products which is the main cause of the image flowing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for preventing image deletion in an electrophotographic copying machine, and particularly to a method for preventing image deletion when a photoreceptor having a surface protective layer is used.

[Prior Art] Conventionally, electrophotographic photoreceptors have been prepared by providing a photoconductive layer mainly made of selenium or selenium alloy on a conductive support, or by using an inorganic photoconductive material such as zinc oxide or cadmium sulfide as a binder. Generally known are those using organic photoconductive materials such as poly-N-vinylcarbazole and trinitrofluorenone or azo pigments, and those using amorphous silicon.

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 parts 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, a method of providing an organic film on the surface of a photosensitive layer (Japanese Patent Publication No. 38-1544
6), Method of providing inorganic oxide (Japanese Patent Publication No. 43-1451
．． 7), method of laminating an insulating layer after providing an adhesive layer (Japanese Patent Publication No. 43-27591), or plasma CVD method, optical C
aSi layer, a-3t:N:H layer, a-
Method of laminating St:O:H layers etc.
859, Japanese Patent Application Laid-Open No. 59-58437).

However, the protective layer has a high electrophotographic resistance (1014Ω).
・If the distance is 0 m or more, problems such as an increase in residual potential and accumulation during repetition will occur, which is not preferred in practice.

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. 43-16198)
, Japanese Patent Publication No. 48-10258, U.S. Patent No. 29013
48), a method of adding a transfer agent such as a dye or a Lewis acid to the protective layer (Japanese Patent Publication No. 44-834, Japanese Patent Application Laid-open No. 1987-1
．． 33444), or a method of controlling the resistance of the protective layer by adding metal or metal oxide fine particles (Japanese Unexamined Patent Publication No. 53-3)
338) 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. 57-30848, 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, there is a substantial resistance to visible light. 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.
This is because when this discharge product absorbs moisture from the atmosphere, the electrical resistance in the surface direction of the protective layer decreases, making it impossible to maintain the electrostatic latent image. As a method for preventing image blurring, a method of water-repelling the metal and metal oxide fine powder dispersed in the protective layer, as proposed in JP-A-6L-295066, has been proposed, but the effect is not sufficient. However, side effects such as an increase in residual potential occur.

Also, JP-A-51-85941, JP-A-52-1294
34. As disclosed in Japanese Patent Application Laid-Open No. 53-32744, a method has been proposed in which the surface of the photoreceptor is heated to a high temperature using a heater to scatter adsorbed moisture and prevent image blurring. This causes the inconvenience that toner sticks to the surface.

Furthermore, JP-A-61-11.2153, JP-A-62-11
9587, JP-A-63-10477, a method of removing discharge products using an abrasive has also been proposed, but in a photoreceptor having the protective layer, active metals can be removed by polishing. Alternatively, metal oxides may appear on the surface, resulting in the disadvantage that adsorption of discharge products is likely to occur and image blurring is likely to occur.

[Problems to be Solved by the Invention] In order to solve the problems of the prior art described above, the present invention provides a durable electrophotographic photoreceptor having a surface preservation layer with excellent transparency and mechanical strength. The purpose of this invention is to provide a method for preventing image deletion in the copying method used.

[Means for Solving the Problems] The structure of the present invention for solving the above problems is as described in the claims: (1) A photoconductive layer and a surface protection layer are sequentially laminated on a conductive support. An electrostatic latent image forming means, a developing means for developing the electrostatic latent image, a means for transferring the developed image, and a means for cleaning the toner remaining on the surface of the photoreceptor after transfer are arranged around the electrophotographic photoreceptor. A method for preventing image blurring, the method comprising forming an image using an image forming apparatus in which a thin film of petroleum-based aliphatic hydrocarbon is formed on the surface of the surface protective layer.

(2) Claim (1) above, wherein the surface protective layer comprises a layer in which fine powder of metal or metal oxide is dispersed in a binder resin.
This is the image blur prevention method described above.

The present invention will be explained in more detail below.

The electrophotographic photoreceptor used in the present invention has a structure in which a photoconductive layer and a surface protective layer are sequentially laminated on a conductive support, and the surface protective layer binds metal or metal oxide powder. Consists of a layer dispersed in a binder resin.

The metal or metal oxide fine powder used in the present invention includes metals such as copper, tin, aluminum, indium, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, antimony-doped tin oxide, A metal oxide fine powder such as indium oxide doped with tin can be used. Two or more of these metal or metal oxide fine powders may be mixed. The average particle diameter of these fine powders is preferably 0.3 μm or less, preferably 0.1 μm or less, from the viewpoint of the transmittance of the protective layer.

Examples of the binder resin used in the present invention include silicone resin, polyurethane resin, acrylic resin, polyester resin, polycarbonate resin, polystyrene resin, and epoxy resin.

It can be obtained by dispersing metal oxide fine powder in a binder resin solution, coating the photoconductive layer and drying it. Note that various additives may be added to the protective layer for the purpose of improving dispersibility, adhesion, or smoothness.

The photoconductive layer used in the present invention is Se.

Se alloy such as 5e-TeSAS2 Se3, ZnO, C
Used are particles of a ■-■ group compound such as dS and CdSe dispersed in a resin, an organic photoconductive material such as polyvinylcarbazole, or aSl.

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, Fe5CuS
AI on an insulating substrate such as metal or alloy such as Au, polyester, polycarbonate, polyimide, glass, etc.
,Ag.

Examples include those formed with a thin film of a metal such as Au or a conductive material such as In20z or 5n02, or 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.

Examples of the petroleum aliphatic hydrocarbons used in the method for preventing image blurring of the present invention include cyclohexane, n-hexane, n-heptane, n-octane, isooctane, n-nonane, isododecane, ligroin, and mixtures thereof.

The method for forming a thin film on the surface of the surface protective layer in the image deletion prevention method of the present invention is, for example, by changing the blade pressure of the cleaning blade in a wet copying machine.
Furthermore, in a dry type copying machine, this is made possible by arranging means for forming a liquid film around the photoreceptor.

According to the present invention, since a liquid film is formed on the surface of the protective layer during each copying process, adsorption of nitrate ions, ammonium ions, etc., which cause image blurring, to the surface of the protective layer is prevented, and the image blurring can be prevented.

Note that in the above explanation, a liquid film is formed on the surface of the protective layer before discharge to prevent adsorption of generated ions, but for example,
After discharging, a petroleum-based aliphatic hydrocarbon may be applied to the surface of the photoreceptor using a sponge roller brush or the like to dissolve and remove discharge products adhering to the surface of the photoreceptor.

[Examples] The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples.

Aluminum tube (80mmφX 340mm L)
After pretreatment (cleaning), the substrate was placed in a vacuum evaporation apparatus, and the AS2Se3 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 10' Torr Support temperature: 200°C Boat temperature: 450°C Next, a silicone resin (AY42-441 manufactured by Toshi Silicone Co., Ltd.) was glued onto the photoconductive layer to form a groin solution with a dry thickness of 0. An intermediate layer was prepared by coating to a thickness of 2 μm.

Furthermore, styrene-methacrylate-acrylic acid-N-methylolacrylamide resin liquid (solid content 40w)
t%), 10 parts by weight of tin oxide, and an appropriate amount of solvent were added and dispersed in a ball mill for 100 hours.The dispersion was applied by dip coating, dried at 120°C for 30 minutes, and a protective layer with a thickness of 5 μm was formed. It was used as a photoreceptor for electrophotography.

FIG. 1 is an example of a schematic configuration diagram of a copying machine that performs cleaning and removal of discharge products adhering to the surface of a protective layer according to the present invention.

There is a charger 2 around this photoreceptor drum t.
, an exposure slit 3, a developing section 4, a transfer charger 5, a cleaning unit 1-6, and a liquid film forming unit 7 are arranged in this order.

In the liquid film forming unit, petroleum-based aliphatic hydrocarbon Isopar H (manufactured by Exxon Chemical Co., Ltd.) is supplied to the surface of the protective layer via a sponge roller 8, and is thinned by a blade 9 to form a liquid film. By performing this step for each copying process, the surface of the protective layer is always covered with a liquid film, and adsorption of discharge products, which is the main cause of image deletion, can be prevented.

The photoreceptor is used in the copying process under high temperature and high humidity (30
When a copying test was conducted on 300,000 copies at a temperature of 90% (°C, 90%), it was confirmed that no image blurring occurred.

[Effects of the Invention] As explained above, according to the present invention, a liquid film is always formed on the surface of the protective layer, so that adsorption of discharge products, which is the main cause of image deletion, is less likely to occur, and image deletion can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of a copying machine implementing the present invention. 1... Photosensitive drum, 2... Charger, 3...
...Exposure slit, 4...Developing section, 5...Transfer charger, 6...Cleaning unit, 7...Liquid film forming unit, 8...Sponge roller 9...Blade, 10...・Petroleum-based aliphatic hydrocarbons. Figure 1 Patent source: Ricoh Co., Ltd. Agent Patent attorney: Hide Komatsu

Claims (2)

[Claims] (1) An electrostatic latent image forming means, a developing means for developing this electrostatic latent image, a developed image A method of forming an image using an image forming apparatus equipped with a means for transferring the toner and a means for cleaning the toner remaining on the surface of the photoreceptor after the transfer, wherein a thin film of petroleum-based aliphatic hydrocarbon is formed on the surface of the surface protective layer. A method for preventing image blurring, characterized by: (2) The method for preventing image blurring according to claim 1, wherein the surface protective layer comprises a layer in which fine powder of metal or metal oxide is dispersed in a binder resin.