JPH02984A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the contamination and damage of a photosensitive layer by foreign matter without spoiling various characteristics of the photosensitive layer at all by providing a surface protective layer consisting of alkoxyorganosilanol and acryl polyol on the photosensitive layer. CONSTITUTION:This photosensitive body has the photosensitive layer 2a consisting of a vapor deposited As2Se3 film on a conductive base body 1 consisting of an aluminum alloy and has further the surface protective layer 5 thereon. The surface protective layer 5 is formed by coating the mixture composed of the alkoxyorganosilanol and the acryl polyol on the photosensitive layer. The acryl polyol is capable of forming a film which has good wettability with the underlying photosensitive layer, sticks securely thereto and has high hardness and the specific resistance of the film can be regulated by adding the alkoxyorganosilanol thereto. The surface protective layer which sticks securely to the underlying photosensitive layer without impairing the characteristics of the photosensitive layer at all and has good printing resistance is obtd. in this way.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an electronic photosensitive layer provided with a surface protective layer on a photosensitive layer made of an inorganic photoconductive material or an organic photoconductive material provided on a conductive substrate. Related to photographic photoreceptors.

[Conventional technology]

Photoreceptors used in electrophotographic devices using the Carlson process are broadly classified into those with a functionally separated multilayer structure and those with a single layer structure, depending on the structure of their photosensitive layers. In the former, the basic structure is a charge generation layer in which pairs of electrons and holes are generated by the incidence of light to form a latent image, and a charge transport layer that transports the generated charges.In the latter, charge generation.

The basic structure is a single layer with charge transport ability.

FIG. 4 shows a schematic cross-sectional view of the basic structure of these photoreceptors. Figure 4(a) shows a single photosensitive layer 2 on a conductive substrate l.
a was formed. FIG. 4(b) shows a charge transport layer 4 on a conductive substrate 1. A photosensitive layer 2b is formed in which a charge generation layer 3 is laminated in this order, and is normally used in a negative charging method. FIG. 4(C) shows a charge generation layer 3 on a conductive substrate 1. A photosensitive layer 2C is formed in which a charge transport layer 4 is laminated in this order, and is normally used in a positive charging system.

Most of the electrophotographic devices developed in the past had the photoreceptor installed in this basic configuration. recently,
Requirements for the quality of images obtained with electrophotographic devices are becoming increasingly strict, and in order to meet these requirements, prevent damage and deterioration of the photosensitive layer surface, and stably obtain high-quality images over a long period of time, we have developed It has been proposed to further provide a surface protective layer. In particular, when the photosensitive layer has a functionally separated multilayer structure as shown in Figure 4(b), in which a thin charge generation layer is formed on a charge transport layer, such a surface protective layer is extremely important. . As the surface protective layer, for example, JP-A-58-139154, JP-A-5821794,
2 and JP-A-57-16459, a method of providing a cross-linked polymer or copolymer as a protective layer, JP-A-57-204559 and JP-A-56-38.
Fluororesin, as known from publication No. 055.

Silicone resin 1 Method of providing polyester resin, aromatic polyamide resin, etc. as a protective layer, JP-A-59-15
The method of providing an inorganic layer as known in JP-A No. 940, JP-A-59-15941, JP-A-59-21134, and JP-A-58-130343, JP-A-57-30846. As is known in the literature, a method has been proposed in which a polymer resin layer containing an inorganic substance such as a metal or a metal oxide is provided.

[Problem to be solved by the invention]

However, few conventional surface protective layers have yielded satisfactory results, and there have also been cases of property deterioration due to the provision of surface protective layers. In other words, the method of using a polymer resin layer as a protective layer requires a condensation catalyst, which complicates the process, and the substance used for the catalyst may have an adverse effect on the underlying photosensitive layer, or may cause problems with the cured film. In this case, a baking process is required, the wettability between the photosensitive layer and the resin is poor, and advanced coating techniques are required, and the presence of a protective layer may reduce the sensitivity of the photoconductor and cause background fogging. There is a problem in that the toner filming cycle is accelerated. Furthermore, in the method of using an inorganic layer as a protective layer, the technology for uniformly applying the inorganic layer is generally very sophisticated, and it also requires a lot of equipment, which inevitably leads to high costs. On the other hand, the method of using a polymer resin layer containing an inorganic substance is the most practical, but unless the inorganic substance to be dispersed and the base resin are carefully examined and the blending ratio etc. are not carefully controlled, toner filming may occur. Not only may this lead to premature image failure, but also the film quality may deteriorate due to the addition of inorganic substances, leading to image defects and film peeling.

This invention has been made in view of the above-mentioned problems, and can be easily formed on a photosensitive layer with good wettability and adhesion, without impairing the properties of the photosensitive layer at all. An object of the present invention is to provide an electrophotographic photoreceptor that has a surface protective layer that prevents contamination and damage to the photosensitive layer due to foreign substances and is less likely to cause toner filming, and that can form high-quality images over a long period of time.

[Means to solve the problem]

In order to achieve the above object, according to the present invention, an electrophotographic photoreceptor is provided with a film made of an alkoxyorganosilanol and an acrylic polyol as a surface protective layer on a photosensitive layer provided on a conductive substrate. shall be.

[Effect]

Acrylic polyol can form a highly hard film that firmly adheres to the underlying photosensitive layer with good wettability, and by adding alkoxyorganosilanol, the specific resistance of the film can be adjusted, allowing for appropriate electrical properties. It can be made into a film. The film made of alkoxyorganosilanol and acrylic polyol is a surface protective layer with good printing durability that firmly adheres to the underlying photosensitive layer without impairing the properties of the photosensitive layer, preventing contamination and damage of the photosensitive layer from foreign matter. In addition, there is no background fog, and no image blurring occurs even in a high humidity atmosphere.

〔Example〕

Example 1 FIG. 1 is a schematic cross-sectional view of an example of the photoreceptor of the present invention, in which a conductive substrate 1 made of an aluminum alloy is coated with
Photosensitive layer 2a consisting of a vapor-deposited film of ^52Se with a film thickness of 53 μm
, and further has a surface protective layer 5 thereon. The surface protective layer 5 is formed by applying a mixture of alkoxyorganosilanol (OCD Type 7.85R, manufactured by Tokyo Ohka Kogyo ■) and acrylic polyol (Kansai Paint side rethane PG-60).

The film thickness of this surface protective layer and the blending ratio (weight ratio) of alkoxyorganosilanol and acrylic polyol are
Example 1-1 was modified as shown in the table. 1-2
．． Thirteen photoreceptors were produced. Further, as Comparative Example 1, a photoreceptor without a surface protective layer was produced. Table 1 shows the results of examining the mechanical properties of these photoreceptors. Here, the charged potential is the initial surface potential when the photoreceptor surface is charged by corona discharge in the dark, and the dark decay rate is the surface potential decay rate for 1 second immediately after corona discharge is stopped in the dark, and half-attenuation exposure. The amount is the exposure amount required to irradiate the photoreceptor surface with white light of 0.51 ux to attenuate the initial surface potential to 172, the residual potential is the surface potential after 2 Lux-5 ec exposure with white light, and the adhesion is the amount of light that is required to attenuate the initial surface potential to 172. The adhesion strength of the surface protective layer to the surface was examined using adhesive tape. indicates the presence or absence of image blur on an image obtained in a cloud atmosphere at a temperature of 35° C. and a relative humidity of 85%.

The photoreceptor of Example 11 in Table 1 has a small increase in residual potential, and the adhesion of the film is at a nearly satisfactory level.

However, when this photoreceptor is installed in a copying machine with a blade cleaning mechanism, the surface protective layer wears out quickly in an electrophotographic process where relatively strong stress is applied to the photoreceptor, so the cleaning mechanism and It is necessary to understand the compatibility with the photoreceptor.

Although the photoreceptor of Example 13 had a slightly high residual potential, it operated without any problems in actual use. Further, since the surface protective layer itself has a very firmly attached base layer, it has excellent damage resistance and can be compatible with various copying processes.

In the photoreceptor of Example 12, the increase in residual potential was small, and the film was very firmly attached to the underlayer. In addition, the protective layer is hard and suffers little wear during use, making it suitable for high-speed copying processes.

In terms of background fogging and moisture resistance, Example 111-2.
Each photoreceptor of No. 13 is almost equivalent to the photoreceptor of Comparative Example 1,
Insulating properties of each surface protective layer in Example 1.

It can be seen that the hygroscopicity is not so high as to cause any practical problems.

Furthermore, it was observed that each photoreceptor of Example 1 was slow in forming toner filming.

Embodiment 2 FIG. 2 shows a schematic cross-sectional view of another embodiment of the present invention, which is an example in which a surface protective layer is further provided on the conventional example shown in FIG. conductive substrate 1
1 phenyl-3-(p-diethylaminostyryl) 2-pyrazoline (ASPP) as a charge transport material and polymethyl methacrylate polymer (PMM) as a binder.
A) A charge transport layer consisting of 4. A charge generation layer 3 consisting of a phthalocyanine pigment as a charge generation substance and a polyester resin as a binder is stacked in this order to form a film with a thickness of 17 μm.
m photosensitive layer 2C is provided, and alkoxyorganosilanol (Tokyo Ohka Kogyo OCD Ty
pe 7. 85R) and acrylic polyol (Kansai Paint (ml Rethan PG-60), film thickness 1.5μ
This is a photoreceptor on which a surface protective layer 5 of m is formed.

The blending ratio (weight ratio) of alkoxyorganosilanol and acrylic polyol in this surface protective layer was changed as shown in Table 2, and Examples 2-1 and 2-2. Photoreceptors 2-3 were produced. Further, as Comparative Example 2, a photoreceptor without a surface protective layer was produced.

Table 2 shows the results of examining the physical characteristics of these photoreceptors. Here, the charged potential is the initial surface potential when the photoreceptor surface is charged by corona discharge in the dark, and the dark decay voltage is the surface potential decay value for 1 second immediately after corona discharge is stopped in the dark, and half-attenuation exposure. The amount indicates the exposure 1 required to attenuate the initial surface potential to 172 by irradiating light with a wavelength of 780 nm, and the residual potential indicates the surface potential after exposure at 5 μJ/ci with light with a wavelength of 780 nm.

The photoreceptor of Example 2-1 in Table 2 operates without any problems in actual use, although some image blurring occurs at a high temperature and high humidity of 85%, for example, at 35°C. Furthermore, the surface protective layer 5 itself is very firmly attached to the base layer, and therefore has excellent damage resistance.

The photoreceptor of Example 2-3 operates without any problems in actual use, although it causes some background fogging at a low temperature and low humidity of 20%, for example, at 5°C. However, in this case, the surface protective layer 5 wears out quickly in an electrophotographic process where relatively strong stress is applied to the photoreceptor, such as when installed in a copying machine with a blade cleaning mechanism. Therefore, it is necessary to understand the compatibility between the cleaning mechanism and the photoreceptor.

The photoreceptor of Example 2-2 operates well without image blurring under high temperature and high humidity conditions and without background fogging under low temperature and low humidity conditions. In addition, the membrane is hard and there is little membrane wear during operation.
It can be used as a photoreceptor compatible with high-speed copying processes. Furthermore, toner filming was less likely to occur in the photoreceptors of each example. On the other hand, Comparative Example 2 without a surface protective layer
With the photoconductor, scratches were seen on the images after several copies were made.

FIG. 3 shows an example in which a surface protective layer 5 containing alkoxyorganosilanol and acrylic polyol is provided on a negatively charged organic hemofluoride as shown in FIG. 4(C). The charge transport layer was not worn out, the printing durability was improved, and the properties were stabilized.

In the above embodiment, a case was described in which an organic photoconductive material was used as an example of a photoreceptor having a functionally separated multilayer structure. But it is effective. Furthermore, it is also effective when an inorganic material and an organic material are used together.

〔Effect of the invention〕

According to the present invention, a photoreceptor is provided in which a surface protective layer made of an alkoxyorganosilanol and an acrylic polyol is provided on a photosensitive layer made of an inorganic photoconductive material or an organic photoconductive material. This surface protective layer is a highly rigid surface protective layer that firmly adheres to the photosensitive layer without impairing the properties of the underlying photosensitive layer. Since it does not cause any background fogging or image blurring in high cloud surroundings, it is possible to obtain an excellent electrophotographic photoreceptor that can form high-quality images over a long period of time. Become.

[Brief explanation of the drawing]

1, 2, and 3 are schematic sectional views of photoreceptors according to different embodiments of the present invention, and FIG. 4 shows a conventional photoreceptor. b) and (C) are schematic cross-sectional views of different conventional photoreceptors.

Claims (1)

[Claims] 1) An electrophotographic photoreceptor comprising a film made of alkoxyorganosilanol and acrylic polyol as a surface protective layer on a photosensitive layer provided on a conductive substrate.