JPS62295066A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To form a long-life photosensitive body which withstands repetitive uses by forming a protective layer of a layer formed by dispersing pulverized metal powder or pulverized metal oxide powder subjected to a water repelling treatment into a binder resin. CONSTITUTION:The protective layer consists of the layer formed by dispersing the pulverized metal powder or pulverized metal oxide powder subjected to the water repelling treatment into the binder resin. The binder resin usable for the protective layer is preferably the resin which is transparent to visible light and has an excellent electrical insulating characteristic, mechanical strength and adhesiveness. Such binder resin is exemplified by a polyester resin, etc. Any metal or metal oxide powders which have <=10<11>OMEGA.cm specific volumetric resistivity and <=0.3mu average grain size are usable as the metal or metal oxide to be used.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, specifically, to a conductive support used in an electrophotographic method known as the Carlson process. The present invention relates to an electrophotographic photoreceptor in which a photoconductive layer and a surface protective layer are sequentially provided.

[Conventional technology]

Conventionally used electrophotographic photoreceptors include those formed by vapor-depositing Se, 5e-Te alloy, 5e-As alloy, etc. as a photosensitive layer on a conductive substrate, plasma CVD of silane derivatives, photoCVD, etc. a-3i formed by or PVK (polyvinylcarbazole)-TNF (2,4
, 7-) linitrofluorenone) or a pigment such as phthalocyanine dispersed in a resin. However, when using these photoreceptors repeatedly, they are easily damaged due to peeling of the transfer paper or cleaning of residual toner (also, the photosensitive layer is easily worn out, and the photoreceptor is exposed to light at a relatively early stage before the characteristics deteriorate. I had to exchange bodies.

[Problems to be Solved by the Invention] In order to improve this point, it is known to provide a surface layer on the surface of the photoreceptor. One of the surface layers is an insulating layer made of a material with relatively high electrical insulation. This insulating layer has the advantage that it can be made thick and has high mechanical strength, but in order to repeatedly use this type of photoreceptor, it is necessary to Special latent image formation processes such as secondary f-electrification → image exposure or primary charging → secondary charging simultaneous image exposure → uniform exposure are required, and these processes can be performed twice in one copying process. This requires more than one charging process, which complicates the device, resulting in unstable characteristics and increased costs. On the other hand, there is a semiconductive protective layer that does not require the above-mentioned special latent image forming process and can be used in the so-called Carlson process of charging→image exposure. This protective layer has low insulating properties (
It is necessary to prevent charge from accumulating on or inside the protective layer. The method that has been adopted so far is to add quaternary ammonium salts, etc. to the protective layer, but the conductivity of these materials generally fluctuates significantly due to moisture absorption, and the conductivity of the protective layer decreases when dry. When the humidity is high, the conductivity increases more than necessary, causing the charge to move in the creeping direction, causing blur in the image. Furthermore, in order to use conventional protective layers in the Carlson process, they must be relatively thin, with a thickness of several microns or less, and are difficult to satisfy in terms of mechanical strength.
In addition, the protective layer may be colored by the substance added to lower the insulation, which may have an undesirable effect on the spectral sensitivity of the photoreceptor, or poor dispersion may deteriorate the surface properties and cause poor cleaning. The purpose of the invention is to overcome the drawbacks of conventional photoreceptors with protective layers used in the aforementioned Carlson process, to avoid charge accumulation during repeated use, to be stable under changing environmental conditions, and to have favorable optical properties. It has sufficient mechanical strength, prevents or suppresses scratches on the photoconductor from being printed out, has a smooth surface and good cleaning properties, and prevents the adhesion or accumulation of toner and paper dust. It is an object of the present invention to provide a long-life photoreceptor that can prevent or suppress defects in image quality such as image blurring and black spots due to image blurring, and can withstand repeated use.

[Means for solving problems]

As a result of extensive research, the present inventors have found that conductive or semiconductive particles with an average particle size of 0.3 μm or less that have been surface-treated with a water repellent are added to the protective layer made of a substantially insulating binder resin. By dispersing fine powder of a metal or metal oxide, it is possible to maintain the protective layer substantially transparent at the film thickness at the time of use, while improving its conductivity, moisture resistance,
The present invention was completed based on the discovery that it is possible to obtain a photoreceptor with excellent durability and cleanability.

That is, the present invention provides an electrophotographic photoreceptor in which a photoconductive layer and a protective layer are sequentially laminated on a support, in which the protective layer contains water-repellent fine metal powder or metal oxide fine powder in a binder resin. The present invention provides an electrophotographic photoreceptor having a dispersed layer.

The binder resin that can be used in the protective layer of the present invention is preferably one that is substantially transparent to visible light and has excellent electrical insulation, mechanical strength, and adhesion. Examples of such binder resins include polyester resins, polycarbonate resins, polyarylate resins, polyurethane resins, epoxy resins,
Examples include acrylic resin, vinyl chloride-vinyl acetate copolymer, silicone resin, alkyd resin, polyvinyl chloride resin, chlorinated butadiene rubber, fluororesin, and melamine resin. These resins can be used alone or as a mixture of two or more.

When solvent resistance of the protective layer is required, it is desirable to use a curable resin.

As the metal or metal oxide used in the present invention, any metal or metal oxide powder can be used as long as it has a specific volume resistivity of 10110.mu. or less and an average particle size of 0.3 μm or less. Examples include gold, silver, aluminum,
Examples include metals such as iron, copper, nickel, silicon, and germanium, and metal oxides such as zinc oxide, titanium oxide, tin oxide, bismuth oxide, indium oxide, and antimony oxide. In this case, a mixture of several metals and metal oxides can also be used.

In the present invention, the water repellent for surface treatment of the metal or metal oxide includes, for example, a silicide used as a silane coupling agent.

Specific examples of silane coupling agents include the following compounds.

1) γ-Aminopropyltriethoxysilane H1NCs
Ha S i (OC*Hs) s2) γ-methacryloxypropyltrimethoxysilane CH.

CH, = C-C-0-C, H, St (OCH,).

3) Vinyltris(βmethoxyethoxy)silane CH,=CH5i (QC, H40CH,).

4) γ-chloropropyltrimethoxysilane CLCs
He Si (OCHs)S5) N-β(aminoethyl)γ-aminopropyltrimethoxysilane H,NC,H4NHC,H6Si (OCHl).

6) N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane H3H,NC2H4NHClH65i (OCH8).

As a silicone water repellent, for example, there is KC-89 manufactured by Shin-Etsu Chemical Co., Ltd. This is oily methyl methoxy silicone, which has the property of reacting with water and curing while volatilizing methanol to form a water-repellent film. Another similar silicone water repellent is Po1on A.

KC-88, Po1on C, etc. (manufactured by Shin-Etsu Chemical Co., Ltd.)
There is.

Surface treatment of metal or metal oxide powder with water repellent is
This is carried out by dissolving a water repellent in a large amount of a soluble solvent, mixing and stirring a metal or metal oxide powder therein, stirring thoroughly, and then distilling off the solvent and drying.

For example, when processing with a silane coupling agent, water is generally used as a solvent.

The amount of the silane coupling agent used is about 0.1 to 10% by weight, preferably 0.1 to 10% by weight relative to the metal or metal oxide powder.
．． Approximately 1 to 3.0% by weight is appropriate. This is because if it is less than 0.1% by weight, it is not effective (and if it is more than 3.0% by weight, it causes a decrease in dispersibility.

The silane coupling agent other than the aminosilane type is used after being dissolved in an aqueous solution having an acetic acid concentration of 0.01 to 0.1% by weight.

In order to fully bring out the effects of the silane coupling agent, select the appropriate type depending on the type of binder resin and metal or metal oxide used, and apply the optimal amount of silane coupling agent to achieve the desired performance. It is necessary to determine accordingly.

In addition, when using silicone water repellent, soluble solvent 1
The treatment is carried out by dissolving the solution and diluting it to about 10%, and mixing 1 to 200 parts of the metal or metal oxide powder to be treated with 100 parts of this solution. Solvents used here include toluene, xylene, trichlene, carbon tetrachloride,
Industrial gasoline, esters, ketones, methanol,
There are ethanol, etc. When using industrial gasoline,
10 parts of curing catalyst is mixed with 100 parts of solution.

Metal or metal oxide powders treated with these water repellents have a broken organic film formed on their surfaces, and as a result, the following properties are imparted to them.

1) Excellent water repellency.

2) Good mold releasability.

3) Improved dispersibility.

4) Excellent heat resistance and weather resistance.

The composition ratio of the binder resin and water-repellent-treated metal or metal oxide in the protective layer varies depending on the combination of materials, but the surface-treated metal or metal oxide may be added in an amount of 5 to 500 parts by weight per 100 parts by weight of the binder resin. Use within the range of parts by weight. The thickness of the protective layer can be set between 1 and 30 microns as required.

Metals or metal oxides treated with a silane coupling agent or a water repellent such as silicone are thermally and chemically stable, and by dispersing them in the protective layer, the protective layer has the following properties: Granted.

1) Improved moisture resistance, 2) Improved surface smoothness, 3) Non-adhesion and mold releasability, 4) Improved durability.In addition, the properties are less affected by environmental changes (
Become.

Since in the present invention photogeneration of charge carriers takes place in the originally conductive layer, the protective layer must not be substantially transparent to the wavelength range to which the photoconductive layer is originally sensitive.

Further, in the photoreceptor of the present invention, an intermediate layer may be provided between the protective layer and the photoconductive layer to improve adhesiveness and charge retention characteristics, if necessary. The thickness of the intermediate layer at this time is preferably 1 μm or less.

To apply the surface protective layer, a bar coater, applicator,
A spray coater, doctor blade, dip coater, etc. are used.

〔Effect of the invention〕

The electrophotographic photoreceptor according to the present invention has the following advantages when compared with conventional ones.

1) It is possible to prevent dust, paper powder, etc. from adhering to the surface of the protective layer.

2) Cleanability is improved.

3) A good copy image can be obtained even under changing environmental conditions.

4) A protective layer with high mechanical strength can be provided.

〔Example〕

Next, examples of the present invention will be described while comparing them with comparative examples.

Comparative Example 1 Aa2Se3 alloy vapor deposited film (6
0μ thickness), 1 part by weight of zirconium tetrabutoxide (manufactured by Matsumoto Bunmen Co., Ltd., ZA60) and γ-acryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM50).
3) A solution consisting of 1 part by weight and 20 parts by weight of n-butanol was applied by dip coating, and dried with a 40' CJ trowel for 2 hours to give a 0.
A photoreceptor was prepared with an intermediate layer having a thickness of 5 μm. Next, apply acrylic polyol (manufactured by Kansai Paint Co., Ltd., Letare 4) on top of this.
000) 100 parts by weight, solvent (manufactured by Kansai Paint Co., Ltd.,
Fine powder consisting of 45 parts by weight of rethane thinner, 3n0285 parts by weight, and 0.15 parts by weight of Sb (average particle size 0.
3μ or less) in a stainless steel carbonyl mill.
After dispersing and mixing for 0 hours, 280 parts by weight of a solvent was added to dilute it, and a solution was prepared by adding 14.5 parts by weight of hexamethylene diisocyanate (Buret type) (manufactured by Kansai Paint Co., Ltd., urethane curing agent) as a curing agent. It was coated and dried to obtain a photoreceptor having a protective layer with a thickness of about 3 μm.

This photoconductor is used in a plain paper copier (FX-X manufactured by Fuji Xerox).
5870) and conducted a copying test according to the usual method, good copied images were obtained, but at 30°C 9
After repeated use in a high temperature and high humidity environment of 0% RH, 5
Blurred images and missing parts occurred after around 0,000 copies.

Example 1 γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-5) was used as a silane coupling agent.
03) and tin oxide (manufactured by Mitsubishi Metals Co., Ltd., 5-1) as the metal oxide, a photoreceptor was prepared in the following manner.

The silane coupling agent is added to water at a weight ratio of about 1/100 so that the silane coupling agent is 1% by weight based on the tin oxide to be treated, and acetic acid is added at a weight ratio of about 1/100 to the water. A silane coupling solution was prepared by adding 1% by weight. This solution was added at least 10 times the amount of tin oxide and dispersed in a ball mill for about 50 hours.
The mixture was dried in an oven at 0.degree. C. for about 2 hours and pulverized in a blender to obtain powdered tin oxide whose surface was coated with a silane coupling agent.

10,000, on an As2Se3 alloy susceptor having an intermediate layer of 0.5 μm thickness obtained in the same manner as in the comparative example, 100 parts by weight of acrylic polyol, 45 parts by weight of solvent and tin oxide particles treated with the above cyan coupling agent were applied. After 50 parts by weight of the powder was placed in a stainless steel ball mill and dispersed and mixed, the solution was prepared, coated, and dried in the same manner as in the comparative example to obtain a photoreceptor having a protective layer about 3 μm thick. When copying tests were conducted on the photoreceptor having this protective layer in the same manner as in the comparative example, good images were repeatedly produced.
No image deterioration was observed even after repeated use of 0.000 copies, and a good image with a porosity of 4.6 tp/mm was obtained.

Example 2 Silicone water repellent (Shin-Etsu Chemical Co., Ltd. i KC-89) 1
A treatment solution was prepared by stirring and mixing 0 parts by weight of ethanol and 90 parts by weight at room temperature for about 30 minutes. 70 parts of this solution and 20 parts of tin oxide as a metal oxide were dispersed in a ball mill for about 50 hours, then dried in an oven at 180°C for about 1 hour, and finely ground in a blender to coat the surface with the silicone water repellent. A powdered tin oxide was obtained.

An electrophotographic photoreceptor was formed using this tin oxide in the same manner as in Example 1. When this photoreceptor was subjected to the same test as in Comparative Example 1, a good image was obtained, and no deterioration was observed in the image after so and ooo copying in an environment of 30° C. and 901 RH.

Claims (1)

[Claims] In an electrophotographic photoreceptor in which a photoconductive layer and a protective layer are sequentially laminated on a support, the protective layer is a layer formed by dispersing water-repellent metal fine powder or metal oxide fine powder in a binder resin. An electrophotographic photoreceptor characterized by: