JPH0353625B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, and more specifically, to an improvement in an electrophotographic photoreceptor in which a protective layer is provided on the surface of a photoconductive 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, an organic photoconductive material is directly provided on a suitable conductive substrate by coating or vapor deposition, or the above material is provided together with a suitable organic binder, or an inorganic material such as ZnO, CdS, or TiO ₂ is provided in the binder. These include those in which photoconductive materials are dispersed, those in which amorphous selenium or its alloys are vapor-deposited, or those in which two or more of the various photoconductive layers listed above are laminated (for example, −5394, Special Publication No. 1977
-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, in processes such as development, etc. In order to improve the characteristics, 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). but,
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 cycle increase can be significantly improved by reducing the protective layer to 1μ or less.
The film may peel off easily and cannot 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, although these methods can provide a protective layer with a thickness of 10 to 20μ by providing a low-resistance protective layer, and can prevent high residual potential and large cycle increases, sometimes the chargeability of the entire photoreceptor may be reduced. It has been found that this tendency is particularly noticeable when the photoconductive layer has a high sensitivity.

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

An object of the present invention is to provide an electrophotographic photoreceptor in which a photoconductive layer, an intermediate layer, and a protective layer are sequentially laminated on a conductive support, in which the intermediate layer is formed using at least one organic titanium compound. This can be achieved by using an electrophotographic photoreceptor characterized by:

The structure of the electrophotographic photoreceptor of the present invention is shown in the accompanying drawings. In the figure, 1 is an organic polymer compound or metal oxide (average particle size
2 is an intermediate layer containing an organic titanium 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.

Examples of the organic titanium compound suitable for the intermediate layer 2 include organic derivatives of orthotitanic acid such as titanium orthoester, polyorthotitanate ester, and titanium chelate.

Titanium orthoester has the following general formula () (In the formula, R ₁ , R ₂ , R ₃ , and R ₄ are each independent of each other, and each represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a cresyl group. ) group, stearyl group, hexyl group, nonyl group, cetyl group.) Polyorthotitanate is a compound represented by the following general formula () (In the formula, R ₁ , R ₂ , R ₃ , and R ₄ each have the same meaning as in the above formula.) Titanium chelate is a compound represented by the following general formula () Ti (L) _o X _4-o () (In the formula, L is a chelate group, Glycols such as octylene glycol and hexanediol; β such as acetylacetone
-Diketones; hydroxycarboxylic acids such as lactic acid, malic acid, tartaric acid, and salicylic acid; ketoesters such as acetoacetate; and ketoalcohols such as diacetone alcohol.

These compounds can be used alone or as a mixture of two or more. Furthermore, the organic titanium compound described above and another organic resin compound can be used as a mixture for improving adhesion, controlling resistance value, and other reasons.

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

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. Significant effects can be obtained when an electron conductive material is used, or when an electron conductive material in which metals and metal oxides with a particle size of 0.3 μm or less are dispersed in an organic polymer is used. That is, if the particle size is 0.3 μm or more, it is opaque, but if it is 0.3 μm or less, it becomes substantially transparent, and light transmission is not hindered.

Specifically, materials used for such a protective layer include merocene and a compound having at least one metallocene skeleton in its molecular structure; tetrazole and a compound having at least one or more tetrazole skeleton in its molecular structure. A compound having;
Gold, silver, aluminum, with an average particle size of 0.3 μ or less,
Metal powders such as iron, copper, and nickel, and powders of metal oxides such as zinc oxide, titanium oxide, tin oxide, bismuth oxide, indium oxide, and antimony oxide; powders containing tin oxide and antimony oxide in a single particle, etc. There is.

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 (55μ thick) provided on an Al substrate, dried, and protected by 10μ. A photoreceptor having layers 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, a resin solution consisting of 1 part by weight of tetra-n-butyl titanate (trade name: Orga Cheeks TA25, manufactured by Matsumoto Trading Co., Ltd.) and 10 parts by weight of isopropyl alcohol was applied by dip coating thereon.
It was dried at 100°C for 2 hours to form a 0.5μ thick intermediate layer. Next, apply a 10μ protective layer the same as the comparative example 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
The voltage was 900V, and the residual potential was 105V. Therefore, the electrostatic contrast was 795V, which was a significantly improved characteristic compared to a photoreceptor with only a protective layer, and a value similar to that of a photoreceptor without a protective layer.

Example 2 An As ₂ Se ₃ vapor deposited film was formed on an Al substrate using the same method as in Comparative Example 1. Next, add 1 part by weight of tetra-n-butyl titanate, 1 part by weight of methyl(trimethoxy)silane, and 30 parts by weight of isopropyl alcohol.
A resin solution consisting of 1 part by weight and 5 parts by weight of n-butyl alcohol was spray applied, hydrolyzed in a high humidity environment of 50°C and 80% RH, and then dried at 100°C for 2 hours to form a 0.3μ thick medium. Layers were set up. Next, the same protective layer as in Comparative Example 1 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 1, the initial potential was 935V, and the residual potential was 140V.
It was hot. Therefore, the electrostatic contrast of this photoreceptor was 795V, which was the same value as 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, 2 parts by weight of diisopropoxy titanium bis(acetylacetonate),
γ-Acryloxypropyltrimethoxysilane (trade name KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by weight, n
- A solution consisting of 20 parts by weight of butanol was spray applied and dried at 100° C. for 2 hours to provide an intermediate layer with a thickness of 0.6 μm. 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 920V, and the residual potential was
It was 120V. Therefore, the electrostatic contrast of this photoreceptor was 800V, which was the same as that of a photoreceptor without a protective layer.

Comparative Example 2 Polyurethane resin (manufactured by Kansai Paint Co., Ltd.) was placed on a two-layer photoconductor consisting of a Se (50μ thick) vapor-deposited film and a Se-Te alloy vapor-deposited film (1μ thick) provided on an Al cylinder with a length of 300 mm. , Rethane 4000) A resin solution prepared by adding and dispersing 30 parts by weight of tin oxide with a particle size of 0.1 μm or less to 70 parts by weight of the solid content was applied and dried to form a 10 μm protective layer. 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 4 2 parts by weight of diisopropoxy titanium bis(acetylacetonate) and 1 part by weight of silicone epoxy resin (trade name SR2115, manufactured by Toray Silicon Co., Ltd.) were placed on the same Se/Se-Te double-layer photosensitive layer as in Comparative Example 2. A solution consisting of 20 parts by weight of butyl acetate was spray applied and dried at 40° C. for 3 hours to provide an intermediate layer with a thickness of 0.5 μm.

Next, the same protective layer as in Comparative Example 2 was provided thereon to a thickness of 20 μm. When this photoreceptor was repeatedly charged and exposed in the same manner as in Comparative Example 2, the initial potential was 1000V and the residual potential was 200V. Therefore, the electrostatic contrast of this photoreceptor was 800V, which was the same as that of a photoreceptor without a protective layer. When we conducted a copy test using this photoreceptor using the magnetic brush development method, we found that
A highly detailed image identical to the exposure 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 protective layer; 2...Intermediate layer; 3...Photoconductive layer; 4...Electroconductive support.

Claims (1)

[Claims] 1. In an electrophotographic photoreceptor formed by sequentially laminating a photoconductive layer, an intermediate layer, and a protective layer on a conductive support, the intermediate layer contains at least one organic titanium compound.
1. A photoreceptor for electrophotography, characterized in that it is formed by forming layers using different types of materials.