JPH0353628B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor having a protective layer.

Many photoreceptors have been put into practical use as photoreceptors used in electrophotography, which includes processes such as charging, exposure, and development (for example, U.S. Patent No.
2297619). For example, by coating or vapor depositing an organic photoconductive material on a suitable conductive substrate,
Directly deposited, or the above materials together with a suitable organic binder, or inorganic photoconductive materials such as ZnO, CdS, TiO ₂ dispersed in the binder, or amorphous selenium or its alloys deposited by vapor deposition. photoconductive layers, or those in which two or more of the various photoconductive layers described above are laminated (for example, Japanese Patent Publication No. 45-5394, Japanese Patent Publication No. 46
-3005, Special Publication No. 49-14271). In order to make these photoreceptors compatible with their electrical and optical properties and mechanical properties, or to further improve and stabilize these properties, in some cases, properties in processes such as development are improved. In order to improve this, it has been proposed to provide a surface layer on the surface of the photoreceptor. One of these surface layers is called a protective layer, and for example, a resin thin film is provided on the surface and a latent image is formed by charging and image exposure (Carlson process). However, when a photoreceptor provided with such a protective layer is used, a high residual potential and a significant increase in its cycle are often observed. This high residual potential and increased cycling can cause the protective layer to
A significant improvement can be achieved by reducing the thickness to 1μ or less, but the film will peel off easily and will not be able to withstand long-term use. Another surface layer is a resin layer with high electrical resistance called an insulating layer, and a latent image is formed by a special method including a static elimination process (for example, see U.S. Pat. No. 3,041,167). It is. However, photoreceptors with this insulating layer require the use of a special latent image formation process.
Since at least two charging steps are required, there is a problem in that the device becomes complicated.

The present invention relates to the former type of photoreceptor provided with a protective layer, and more particularly, to a photoreceptor in which a latent image can be formed by a so-called Carlson process without using a special latent image forming process. The present applicant previously proposed a low resistance protective layer as a solution to the above-mentioned drawbacks (Japanese Patent Application No. 54-42118,
No. 54-65671, No. 54-65672 and No. 54-65673
(see issue). However, with these methods, 10 ⁶ to
10 by providing a low resistance protective layer of ¹³ Ωcm.
Although it can be made into a ~20μ protective layer and prevents high residual potential and significant cycle increase,
Sometimes, the chargeability of the entire photoreceptor decreases, resulting in the disadvantage that images with sufficient contrast cannot be obtained, and this tendency is particularly noticeable when the photoconductive layer is of high sensitivity. There was found.

An object of the present invention is to provide an electrophotographic photoreceptor that can reliably eliminate these drawbacks.

The object of the present invention is to sequentially laminate a photoconductive layer, an intermediate layer containing an organic metal compound (excluding organic titanium compounds and organic zirconium compounds) as a main component, and a low-resistance protective layer on a conductive support. This can be achieved using an electrophotographic photoreceptor.

The structure of the electrophotographic photoreceptor of the present invention is shown in the accompanying drawings. In the figure, 1 is a low-resistance transparent protective layer made of an organic polymer compound added with a suitable organic compound, 2 is an intermediate layer containing an organometallic compound, 3 is a photoconductive layer, and 4 is a conductive support.

At least the intermediate layer 2 must not be immersed in the solvent used to apply the upper protective layer. In addition to its role as a barrier layer, this intermediate layer can also function as an adhesive layer between the photoconductor and the protective layer. Organometallic compounds suitable for this intermediate layer 2 include aluminum tris(acetylacetonate), iron tris(acetylacetonate), cobalt bis(acetylacetonate), steel bis(acetylacetonate), magnesium -bis(acetylacetonate), manganese()bis(acetylacetonate), nickel()-bis(acetylacetonate), panadium tris-(acetylacetonate), zinc bis(acetylacetonate), tin bis- Metal acetylacetonate compounds such as (acetylacetonate), aluminum isopropylate, mono
sec-butoxyaluminum diisopropylate,
Metal alcoholate compounds such as aluminum sec-butyrate, vanadium ethylate, vanadyl n-propylate, vanadium isobutyrate,
and aluminum di-n-butoxide mono-ethylacetoacetate, aluminum oxide octate, aluminum oxide stearate, aluminum oxide acrylate, and the like. These compounds can be used alone or as a mixture of two or more. Furthermore, it can also be used as a mixture of the above organometallic compounds and other organic resin compounds for improving adhesion, controlling resistance, and for other reasons.

The thickness of the intermediate layer 2 can be set arbitrarily, but it is 10 μm.
Below, 1 μm or less is particularly suitable.

This intermediate layer can be formed by coating by an appropriate method such as spray coating, dip coating, knife coating, roll coating, or the like.

The photoconductive layer of the photoreceptor of the present invention includes Se, Se-
Te alloy, Se-As alloy, or a multilayer vacuum-deposited film made of an appropriate combination of these, organic photoconductors such as polyvinylcarbazole/2,4,7-trinitro-9-fluorenone (PVK/TNF), ZnO, etc.
A material in which an inorganic photoconductor such as CdS is dispersed in a binder, or a material in which a charge generation layer and a charge transport layer are laminated can be used.

In addition, as a protective layer, a material prepared by adding an appropriate organic compound or an inorganic compound to an organic polymer compound can generally be used. A remarkable effect can be obtained when an electron conductive material is used, or when an electron conductive material in which a metal oxide with a particle size of 0.3 μm or less is dispersed in an organic polymer is used. Specifically, materials used for such a protective layer include metallocene and compounds having at least one metallocene skeleton in its molecular structure; tetrazole and compounds having at least one tetrazole skeleton in its molecular structure. Compounds: Metal powders such as gold, silver, aluminum, iron, copper, and nickel with an average particle size of 0.3μ or less, and powders of metal oxides such as zinc oxide, titanium oxide, tin oxide, bismuth oxide, indium oxide, and antimony oxide. ; Examples include powder containing tin oxide and antimony oxide in a single particle.

As the low resistance protective layer, one having a resistance of 10 ⁶ to 10 ¹³ Ωcm can be used.

Next, the electrophotographic photoreceptor of the present invention will be explained with reference to comparative examples and examples.

Comparative Example 1 80 parts by weight of polycarbonate and 20 parts by weight of dimethylferrocene were dissolved in dichloromethane, and this solution was applied onto an As ₂ Se ₃ vapor-deposited film (55 μm thick) provided on an Al substrate, dried, and a 10 μm protective layer was formed. A photoreceptor having the following was obtained. The As ₂ Se ₃ vapor deposited film before applying the above protective layer was positively charged to an initial potential of 800 V.
The operation of exposing to light with a wavelength of 460 nm was repeated at a rate of 40 times per minute. At this time, the residual potential was stable at 0V. On the other hand, when the As ₂ Se ₃ vapor-deposited film with the protective layer was charged and exposed under the above conditions, the initial potential was 200 V.
The residual potential was stable at 100V.

Therefore, an As ₂ Se ₃ photoreceptor with a protective layer is
The electrostatic contrast was significantly smaller than that of a photoreceptor without a protective layer.

Example 1 An As ₂ Se ₃ vapor deposited film was formed on an Al substrate in the same manner as in the comparative example. Next, apply ethyl acetoacetate aluminum diisopropylate (trade name) on top of it.
ALCH, manufactured by Kawaken Huain Chemical Co., Ltd.) 1
A resin solution consisting of 1 part by weight and 10 parts by weight of isopropyl alcohol was applied by dip coating and dried at 50°C for 2 hours to form an intermediate layer with a thickness of 0.5 μm. Next, the same protective layer as in the comparative example was provided thereon to a thickness of 10 μm. When this photoreceptor was repeatedly charged and exposed in the same manner as in Comparative Example 1, the initial potential was 910V and the residual potential was 105V. Therefore, the electrostatic contrast was 805V, which was a significantly improved characteristic compared to a photoreceptor with only a protective layer, and was equal to the value of a photoreceptor without a protective layer.

Example 2 An As ₂ Se ₃ vapor deposited film was formed on an Al substrate in the same manner as in Comparative Example 1. Next, on top of that, a resin solution consisting of 2 parts by weight of zinc bis(acetylacetonate), 1 part by weight of a silane coupling agent (trade name, KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.) and 20 parts by weight of n-butyl alcohol. Spray and heat at 100℃.
Dry for 30 minutes to provide a 0.5μ thick intermediate layer. Next, the same protective layer as in Comparative Example 1 was provided thereon to a thickness of 10 μm. When this photoreceptor was repeatedly charged and exposed in the same manner as in Comparative Example 1, the initial potential was 900V and the residual potential was 105V. Therefore, the electrostatic contrast of this photoreceptor was 795V, which was a value equivalent to that of a photoreceptor without a protective layer.

Example 3 As in Comparative Example 1, an As ₂ Se ₃ vapor deposited film was formed on an Al substrate. Next, a solution consisting of 1 part by weight of cobalt () acetylacetonate and 10 parts by weight of n-butyl alcohol is spray applied thereon.
It was dried at 50° C. for 2 hours to form an intermediate layer with a thickness of 0.3 μm. Next, 10μ of the same protective layer as in Comparative Example 1 was applied on top of this.
Made thick.

When this photoreceptor was repeatedly charged and exposed in the same manner as in Comparative Example 1, the initial potential was 910V, and the residual potential was
It was 100V. Therefore, the electrostatic contrast of this photoreceptor was 810V, which further improved the electrostatic contrast of a photoreceptor without a protective layer.

Comparative Example 2 80 parts by weight of polyarylate resin (trade name, U Polymer, manufactured by Unitika) and 20 parts by weight of ferrocene were dissolved in dichloromethane. Apply this solution to a length of 300 mm.
Se (50μ thick) vapor deposited film and Se-Te on Al cylinder
It was coated on a two-layer photoconductor made of a vapor-deposited alloy film (1 μm thick) and dried to obtain a photoreceptor having a 15 μm thick protective layer. When this photoreceptor was charged and exposed repeatedly in the same manner as in Comparative Example 1, the initial potential was 400V and the residual potential was stable at 90V.

On the other hand, when a photoreceptor made of the same Se/Se-Te double-layer vapor deposited film as above was charged and exposed under the above conditions without coating with a protective layer, the initial potential was 900V and the residual potential was 10V. therefore has a protective layer
The Se/Se-Te two-layer photoreceptor had significantly lower electrostatic contrast than the photoreceptor without a protective layer.

Example 4 Se/Se- was deposited on an Al cylinder in the same manner as Comparative Example 2.
A photosensitive layer consisting of a two-layer deposited Te alloy film was formed.
A solution consisting of 1 part by weight of zinc bis(acetylacetonate) and 10 parts by weight of n-butanol was then spray coated onto the layer and dried at 40 DEG C. for 3 hours to form an intermediate layer having a thickness of 0.3 .mu.m. Next, the same protective layer as in Comparative Example 2 was provided thereon to a thickness of 15 μm. When this photoreceptor was repeatedly charged and exposed in the same manner as in Comparative Example 2, the initial potential was 990V and the residual potential was 100V. Therefore, the electrostatic contrast of this photoreceptor is
The voltage was 890V, which was the same as that of a photoreceptor without a protective layer. When a copy test was conducted using this photoreceptor using a magnetic brush development method, an extremely detailed image identical to the exposed pattern was obtained.

Comparative Example 3 A polyurethane resin (manufactured by Kansai Paint Co., Ltd., Rethane 4000) having a particle size of 70 parts by weight solids was placed on a photoreceptor made of the same Se/Se-Te double-layer vapor deposited film as in Comparative Example 2.
A resin solution containing 30 parts by weight of tin oxide having a particle diameter of 0.1 μm or less was applied and dried to form a protective layer of 10 μm. When this photoreceptor was repeatedly charged and exposed in the same manner as in Comparative Example 1, the initial potential was 150 V, the residual potential was 85 V, and the electrostatic contrast was significantly low.

Example 5 1 part by weight of ethyl acetate aluminum diisopropylate (trade name: ALCH, manufactured by Kawaken Fine Chemical Co., Ltd.) and 10 parts by weight of n-butanol were placed on the same Se/Se-Te double-layer photosensitive layer as in Comparative Example 2. A 0.5 μm thick intermediate layer was provided by dip coating a solution consisting of 1.5 μm. Next, 10 μm of the same protective layer as in Comparative Example 3 was applied on top of this.
Made thick. When this photoreceptor was repeatedly charged and exposed in the same manner as in Comparative Example 1, the initial potential was 990V,
The residual potential was stable at 100V. Therefore, the electrostatic contrast was 890V, which was equivalent to a photoreceptor without a protective layer.

When a copy test was conducted using this photoreceptor using a magnetic brush development method, an extremely clear image identical to the exposed pattern was obtained.

[Brief explanation of drawings]

The drawings show the structure of the electrophotographic photoreceptor of the present invention. Symbols in the figure: 1...Low resistance transparent protective layer; 2...Intermediate layer; 3...Photoconductive layer; 4...Electroconductive support.

Claims (1)

[Claims] 1 Electrophotography formed by sequentially laminating a photoconductive layer, an intermediate layer containing an organic metal compound (excluding organic titanium compounds and organic zirconium compounds) as a main component, and a low-resistance protective layer on a conductive support. Photoreceptor for use.