JPH03141365A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance electrophotographic characteristics and printing resistance by forming a surface protective layer made of alkoxyorganosilanol and polyol acrylate and a polyamide resin on an organic photosensitive layer formed on a conductive substrate. CONSTITUTION:The electrophotographic sensitive body is formed by laminating on the conductive substrate 1 the organic photosensitive layer 4a composed of an electric charge transfer layer 2 and a charge generating layer 3 and the surface protective layer 5 made of alkoxyorganosilanol and polyolacrylate and the polyamide resin. These material mixture can form a film good in adhe sion to the under layer of the organic photosensitive layer 4a, and this film is very hard, and the layer 4a is not damaged at the time of forming the film 5, thus permitting the obtained electrophotographic sensitive body to be superior in electrophotographic characteristics and printing resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor used in an electrophotographic apparatus using the Carlson process, and more particularly to a surface protective layer of an electrophotographic organic photoreceptor.

[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 photosensitive layer is composed of 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. The photosensitive layer is composed of a single layer that also has transport ability.

Conventionally, most organic photoreceptors using organic photoconductive materials have a functionally separated multilayer structure consisting of a conductive substrate 1/charge generation layer 2/charge transport layer 3, as shown in the schematic cross-sectional view of FIG. It was a charged type. Some researchers are considering a positive charging type in which the layer structure is changed as shown in the schematic cross-sectional view of Figure 4, but this layer structure generates charges that are extremely thin compared to the charge transport layer 3. Since layer 2 is placed on the surface, damage to the photoreceptor and printing durability become major problems. For this purpose, as a positively charged photoreceptor, as shown in the schematic cross-sectional view of FIG.
The following configuration is being considered. The surface protective layer is fluororesin or silicone resin.

Various types of layers have been proposed, including layers formed by applying materials mainly composed of polyester resins, polyamide resin copolymers, and crosslinked polymers.

[Problem to be solved by the invention]

However, in the above-mentioned surface protective layer, the underlying photosensitive layer may be damaged due to the addition of a curing agent or heat treatment process to form a hardened film, and the wettability of the photosensitive layer surface is poor, requiring advanced techniques for coating. In addition, the presence of the protective layer may cause problems such as decreased sensitivity of the photoconductor, the occurrence of image fogging, and the occurrence of image defects due to the tendency to form toner filming, and furthermore, the material of the protective layer itself. There have been problems such as image blurring due to a decrease in surface resistance in high humidity environments.

In addition, recently, requirements for the quality of images obtained with electrophotographic devices have become increasingly strict, and even photoreceptors with the structure of conductive substrate 1/charge generation layer 2/charge transport layer 3 shown in FIG. It has become desirable to provide a surface protective layer on top of the layer.

This invention was made in view of the above points, and
An object of the present invention is to provide an electrophotographic photoreceptor with excellent electrophotographic properties and printing durability by providing a surface protective layer made of a new material.

[Means to solve the problem]

According to the present invention, the above-mentioned problem is solved by providing an electrophotographic photoreceptor having a film made of alkoxyorganosilanol, acrylic polyol, and polyamide resin as a surface protective layer on an organic photosensitive layer provided on a conductive substrate. This is solved by

[Effect]

Since the mixed material described in item 1 can be cured to form a film at a relatively low temperature, the underlying organic photosensitive layer will not be damaged when forming the surface protective layer.

In addition, among the film components, alkoxyorganosilanol is hard in itself and is effective in increasing the hardness of the entire film and ensuring abrasion resistance, and acrylic polyol has good wettability with the resin binder of the underlying photosensitive layer. It is effective in ensuring good film-forming and coating properties, has good adhesion and improves rigidity, and polyamide resin gives flexibility to the entire film, helping to improve mechanical strength and printing durability.

〔Example〕

FIGS. 1 and 2 are schematic cross-sectional views showing photoreceptors of different embodiments of the present invention. FIG. 1 shows a charge generation layer 2 on a conductive substrate 1 made of A1 alloy or the like. This photoreceptor has a structure in which a photosensitive layer 4a is formed by sequentially laminating charge transport layers 3, and a surface protective layer 5 is formed thereon, and is generally used for negative charging. This photoreceptor has a photosensitive layer 4b having a layer structure opposite to that shown in the figure, and is generally used for positive charging. The charge generation layer 2 is a coating film in which an organic charge generation substance is dispersed in a resin binder, the charge transport layer 3 is a coating film in which an organic charge transport substance is dispersed in a resin binder, and the surface protection layer 5 is a coating film in which an organic charge transport substance is dispersed in a resin binder. It is formed by applying a mixture of organosilanol, acrylic polyol, and polyamide resin.

Alkoxyorganosilanol (OC manufactured by Tokyo Ohka Kogyo)
D Type 7.85R) and acrylic polyol (
Rethane PG60 (manufactured by Kansai Paint@) was mixed at four different weight ratios as shown in Table 1, and polyamide resin (CM8000, manufactured by Toshi ■) was mixed with this mixture at the weight percentages shown in Table 1. In addition, a coating liquid was prepared by mixing with an alcoholic solvent 1 such as ethyl alcohol. This coating liquid was applied to a charge transport layer (19.5 μm) on the outer surface of an A1 alloy cylinder as a conductive substrate.

A charge generation layer (0.5 μm) was sequentially formed and coated,
A surface protective layer having a thickness of 1 .mu.m was formed by heating at a temperature of 50.degree. C. for 1 hour, thereby producing a photoreceptor of Example 1.2.degree. 3.4 having the structure shown in FIG.

For comparison, a photoreceptor of a comparative example was produced in the same manner as in the example except that a surface protective layer was not provided.

Electrophotographic properties of these photoreceptors were measured. The results are shown in Table 1 together with the compounding ratio of the surface protective layer materials.

The charged potential V is the surface potential when the photoreceptor surface is charged with a +5 kV corona discharge in the dark, dark decay ■. is the attenuation rate of the surface potential when left in the dark for 1 second after stopping corona discharge, the sensitivity El/2 is the half-reduction exposure amount required to attenuate the surface potential to 172 by irradiating light with a wavelength of 780 nm, and the residual potential Vr is The surface potential after irradiation with 5 μJ/cIII of light with a wavelength of 780 nm is shown.

Table 1 Table 2 In addition, the image output of these photoreceptors was evaluated using a commercially available plain paper copying machine. The evaluation results are shown in Table 2.

As can be seen from Tables 1 and 2, there is no difference in electrophotographic properties in Example 1 compared to Comparative Example in which no surface protective layer was provided. Although some image blurring occurs under high temperature and high humidity conditions such as a temperature of 35° C. and a relative humidity of 85%, it can be used practically without any problem. The surface protective layer firmly adheres to the base layer and has excellent printing durability.

In addition, Examples 3 and 4 have slightly worse sensitivity than Comparative Examples (although slight background fog occurs in images at low temperatures and low humidity such as 5°C and 20% relative humidity, they can be used in practice without any problems). It also has excellent printing durability.

In Example 2, very good image quality can be maintained without image blurring under high temperature and high humidity conditions and without background fogging under low temperature and low humidity conditions.

In addition, the surface protective layer has a hard film quality with little film abrasion and excellent printing durability, making it suitable for high-speed copying machine processes.

Almost the same resin binder is used for the charge generation layer and the charge transport layer of the organic photoreceptor. Therefore, the above-mentioned mixed material of alkoxyorganosilanol, acrylic polyol, and polyamide resin has good wettability with the charge transport layer and can form a film with good adhesion. It also becomes an excellent surface protective layer for bodies, and it is possible to obtain a negatively charged photoreceptor that can maintain good image quality for a longer period of time than conventional ones.

〔Effect of the invention〕

According to this invention, a photoreceptor is provided with a film made of alkoxyorganosilanol, acrylic polyol, and polyamide resin as a surface protective layer on an organic photosensitive layer provided on a conductive substrate. Such a mixed material can form a film with good adhesion to the underlying organic photosensitive layer, and the formed film is very hard. Furthermore, the underlying organic photosensitive layer is not damaged during film formation. By providing such a surface protective layer, an electrophotographic photoreceptor having excellent electrophotographic properties and printing durability can be obtained.

[Brief explanation of the drawing]

1 and 2 are schematic cross-sectional views showing different embodiments of the photoreceptor of the present invention, FIG. 3, FIG. 4, and FIG.
The figures are schematic cross-sectional views showing different conventional photoreceptors. 1 Conductive substrate, 2 Charge generation layer, 3 Charge wheel.

Claims (1)

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