JPH02242264A - Production of electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve the gradation of an image, to stabilize the image density and to inhibit the occurrence of fine black spots by forming an alumite layer of a prescribed thickness son an Al substrate, subjecting the layer to pore sealing treatment under prescribed conditions and using the resulting substrate. CONSTITUTION:When an electric charge generating layer and an electric charge transferring layer are successively laminated on an Al substrate to produce a sensitive body, an alumite layer of 100-200Angstrom thickness as a barrier layer is formed on the Al substrate by anodic oxidation and subjected to pore sealing treatment in pure water at >=80 deg.C for 1-5min. The electric charge generating layer contg. an org. pigment having high sensitivity to light of long wavelength as an electric charge generating material is then formed on the treated alumite layer. Since this alumite layer functions effectively as an electric charge blocking layer, an image nearly free from black spots and having superior gradation is stably obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a negatively charged organic electrophotographic method comprising forming a charge generation layer on an aluminum substrate and forming a charge transport layer thereon. The present invention relates to a method for manufacturing a photoreceptor.

[Conventional technology]

Conventionally, electrophotographic photoreceptors (hereinafter simply referred to as photoreceptors) used in electrophotographic application devices such as plain paper copiers and optical printers have mainly been photoreceptors made of inorganic photoconductive materials. However, in recent years, photoreceptors using organic photoconductive materials have come into use mainly in low-speed machines.

Compared to inorganic photoreceptors such as selenium, organic photoreceptors have
Although it has advantages such as film formability, thermal stability, transparency, and mass productivity,
There are problems with photosensitivity, chemical stability, and mechanical strength.

Therefore, the layer structure of the photoreceptor is a stack of functionally separated layers, such as a layer that mainly has the function of charge generation and a layer that has the function of retaining surface charges in the dark and transporting the generated charges. Practical progress has been made by selecting and using suitable materials to improve the physical properties of the photoreceptor as a whole. Among these, photoreceptors with a charge transport layer as an upper layer are used in large numbers because the relatively thick charge transport layer protects the thin charge generation layer, resulting in less fluctuation in the characteristics of the photoreceptor and relatively high reliability. It is becoming more and more common.

Most of the charge transport materials used in photoreceptors currently in practical use are electron-donating compounds with high hole mobility, and therefore the chargeability of the photoreceptor is negative.

Such photoreceptors are generally made by forming a film of an organic pigment as a charge-generating substance on a conductive substrate by vapor deposition, or by mixing an organic pigment and an organic polymer resin as a binder in a solvent. A method in which a charge-generating layer is formed by applying a coating liquid, and a charge-transporting layer is formed by applying a coating liquid containing an organic charge-transporting substance and an organic polymer resin as a binder in a solvent. Manufactured.

[Problem to be solved by the invention]

In recent years, demands on the quality of output images from electrophotographic application devices have become increasingly strict. In particular, when used in optical printers such as laser beam printers and LED printers, stable, high-quality images are required even for images formed using the reversal development method.For example, there is also a requirement to eliminate minute image black spots that occur on blank areas. be done.

It is known that the problem of the conductive substrate is a big problem with such image quality, and in Japanese Patent Application Laid-Open No. 63-116160, the thickness of the barrier layer is 100 to 1000.

A photoreceptor using an aluminum substrate on which an alumite layer with a porous layer thickness of 1 μm to 15 μm is formed has been proposed. Further, Japanese Patent Application Laid-open No. 116161/1983 proposes a photoreceptor using an aluminum substrate having an alumite layer in which the molar ratio of amorphous aluminum oxide to crystalline aluminum oxide is 50 to 1,500. However, these measures do not fully satisfy the increasingly strict requirements for image quality as described above.

This invention was made in view of the above points, and
An output image with good gradation and stable image density can be obtained.
It is an object of the present invention to provide a method for manufacturing a negatively charged organic electrophotographic photoreceptor that produces fewer minute image black spots on blank areas even when used in a reversal development system.

[Means to solve the problem]

According to the present invention, the above object is achieved by forming a barrier layer on an aluminum substrate by alumite treatment in a method for manufacturing an electrophotographic photoreceptor, which includes forming a charge generation layer on an aluminum substrate and then forming a charge transport layer. The film thickness is 10
After forming an alumite layer with a thickness in the range of 0 Å to 200 Å, and then sealing it in pure water at a temperature of 80°C or higher for 1 to 5 minutes, an organic layer is formed on the sealed alumite layer. This is achieved by forming a charge generation layer using a pigment as a charge generation substance.

[Effect]

By providing an alumite layer with a barrier layer of an appropriate thickness on the aluminum substrate, the fine organic pigment that is the charge-generating substance does not come into contact with the aluminum at the interface between the aluminum substrate and the charge-generating layer. , the leakage of charge that had occurred at the contact portion is eliminated, and it is possible to eliminate the black spots on the image that were occurring at the portions corresponding to the portions of the leakage of charge.

In addition, by using an alumite layer that has been subjected to the necessary sealing treatment, it is possible to charge the photoreceptor to the required value, making it possible to stably obtain output images with good gradation. .

〔Example〕

FIG. 3 shows a general cross-sectional structure of an alumite layer according to the present invention. In FIG. 3, ■ is an aluminum substrate, 2 is an alumite layer, the alumite layer 2 is made of aluminum oxide like the barrier layer 21 of aluminum oxide, and is made of a porous layer 22 having many pores 23, and 24 is a sealing layer. This is boehmite formed so as to close the holes 23 through processing.

A method for manufacturing an electrophotographic photoreceptor according to the present invention will be explained.

First, the surface of the aluminum cylindrical substrate, which has undergone the necessary machining and cleaning, is anodized with an electrolyte such as oxalic acid, sulfuric acid, or chromic acid, and then sealed with boiling pure water. Form an alumite layer using the same method. At this time, the electrolysis voltage was changed to change the film thickness of the barrier layer 21, the electrolysis time was changed to change the film thickness of the porous layer 22, and the sealing treatment time was changed to change the formation state of the boehmite 24. formed a layer. A charge-generating layer containing an organic pigment as a charge-generating substance is formed on the aluminum substrate on which various alumite layers are formed, and a charge-transporting layer containing an organic charge-transporting substance is further formed thereon to form a photoreceptor. After fabricating and examining its characteristics, it was found that the manufacturing conditions described below were excellent.

That is, these photoreceptors are printed using a reversal development type optical printer, and the number of image black spots that occur in bright areas,
Also, the double charge potential, which indicates the difference between the initial charging potential and the second and subsequent charging potentials, was investigated. Note that charging was controlled to 600V using a scorotron.

Figure 1 is a diagram showing the relationship between the barrier layer thickness and the number of image black spots and double charge voltage in relation to the electrolytic voltage during anodic oxidation, obtained from these survey results. The double charge voltage decreases rapidly as the thickness increases, and almost no longer decreases after about 400 degrees, and the double charge voltage increases up to 300 degrees of density in the Paris γ layer, and reaches saturation with almost no increase even if the thickness is further increased. shows.

Incidentally, FIG. 1 shows the results when the sealing treatment time was 4 minutes.

Figure 2 is a diagram showing the relationship between the sealing time and the number of image sunspots and double charge voltage for two types of alumite layers with barrier layer thicknesses of 150 and 200, where the number of image sunspots is the sealing time. The double charge potential increases in proportion to , and the double charge potential rapidly decreases as the sealing treatment time increases, and reaches saturation after approximately 6 minutes of treatment time, with almost no decrease. Image sunspot number is 50 or less, double charge voltage is 5
0V or less is considered to be the target for characteristics. Based on this, from Figure 1, the film thickness of the barrier layer is 100 Å or more2
A range of 00 Å or less is preferable, and it can be seen from FIG. 2 that the sealing treatment time using pure boiling water is preferably 1 minute to 5 minutes. It has been found that pure boiling water remains as effective as long as the temperature is 80°C or higher. It can be inferred from FIG. 2 that boehmite formed by the sealing process seems to be related to the formation of image black spots. Therefore, the sealing treatment is sufficient as long as the boehmite formed closes the openings of the pores in the porous layer, and a treatment of several minutes is desirable; as the treatment time becomes longer, the boehmite becomes thicker and black spots appear on the image. This is considered to be an undesirable increase. Note that the thickness of the porous layer, that is, the electrolytic time of anodic oxidation did not significantly affect the function of the alumite layer as a charge blocking layer.

〔Effect of the invention〕

According to the present invention, in the method for manufacturing an electrophotographic photoreceptor, which includes forming a charge generation layer on an aluminum substrate and then forming a charge transport layer, the film thickness of the barrier layer is 100 Å or more by anodizing the aluminum substrate. 200
After forming an alumite layer within the range of Å or less, and then performing a sealing treatment for 1 to 5 minutes in pure water at a temperature of 80°C or higher, an organic layer is formed on the sealed alumite layer. A charge generation layer is formed using a pigment as a charge generation substance.

The alumite layer formed on the aluminum substrate in this way and interposed between the aluminum substrate and the charge generation layer functions extremely effectively as a charge blocking layer, and outputs an image with good gradation and stable image density. Thus, even when used in a reversal development system, a negatively charged organic electrophotographic photoreceptor with few small image black spots in the blank area can be obtained.

According to this invention, a semiconductor laser is used as a charge generating substance;
A photoreceptor with good characteristics using an organic pigment that is highly sensitive to long wavelength light such as LEDs can be obtained, and it can be used for semiconductor lasers and LEDs.
The present invention is suitable for use in optical printers that use an exposure source such as the like, and the effects obtained are significant.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 show the relationship between the photoreceptor of the example manufactured by the method of the present invention and the alumite layer as a charge blocking layer, and show the relationship between the photoreceptor and the alumite layer as a charge blocking layer. I is a line diagram showing the relationship between the barrier layer thickness of the alumite layer, the number of image black spots, and the double charge potential, and Figure 2 is a line diagram showing the relationship between the sealing treatment time of the alumite layer, the number of image black spots, and the double charge potential. It is a diagram. FIG. 3 is a schematic cross-sectional view showing the structure of an alumite layer according to the present invention. Barrier layer thickness (in) Figure Sealing time (minutes) Figure

Claims (1)

[Claims] 1) In a method for manufacturing an electrophotographic photoreceptor, which includes forming a charge generation layer on an aluminum substrate and forming a charge transport layer thereon, the thickness of the barrier layer is 100 Å or more and 200 Å or more by alumite treatment on the aluminum substrate. After forming an alumite layer within the following range and then performing a sealing treatment for 1 to 5 minutes in pure water at a temperature of 80°C or higher, an organic pigment is applied on the sealed alumite layer. A method for producing an electrophotographic photoreceptor, which comprises forming a charge generation layer containing a charge generation substance.