JPH08248651A - Manufacture of electrophotographic photosensitive material - Google Patents

Abstract

PURPOSE: To improve the levelling ability on the surface of an under-coating layer by dipping a conductive substrate in coating liquid for the under-coating layer, pulling the conductive substrate up at a preset speed or slower and coating the under-coating layer. CONSTITUTION: A conductivity supporting substrate 1 is precisely finished into a preset dimension preciseness by aluminum extrusion, drawing or resin injection molding. For an under-coating layer 2, polyvinyl alcohol, melanin, copolymer polyamide, polyvinyl butylal, or, etc., is used in consideration of adhesion and coating onto the surface of the conductive substrate after cleaned by water based detergent. By mixing forming material for these under-coating layer 2 with organic solvent, coating liquid for the under-coating layer is made. The coating liquid is used to form the proper-thickness under-coating layer 2 by means of dipping for low-speed film formation (2mm/s or slower). A charge generation layer 3 is formed on the under-coating layer 2 and then a charge transport layer 4 is formed on the charge generation layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminated organic photoreceptor, and more particularly to a method for producing an electrophotographic photoreceptor having high sensitivity and excellent long-term printing durability.

[0002]

2. Description of the Related Art Generally, an electrophotographic process using a photoconductive photoconductor is one of the information recording means utilizing the photoconductive phenomenon of the photoconductor. The photoconductor is placed in a dark place and its surface is exposed by corona discharge. Is charged and then exposed to selectively erase the electric charge in the exposed portion to form an electrostatic latent image. Colored charged fine particles (toner) are attached to the obtained electrostatic latent image by electrostatic attraction or the like to form a visible image. The photoconductive electrophotographic photosensitive member used in the electrophotographic technique that undergoes these series of processes is required to have the following basic characteristics. (1) Be able to be uniformly charged to an appropriate potential in a dark place. (2) It has a high charge retention ability in the dark and discharges little charge. (3) It has excellent photosensitivity, and is capable of promptly extinguishing charges by light irradiation. Furthermore, (4) The surface of the photoconductor can be easily neutralized. (5) The residual potential is small.
(6) It has mechanical strength and is excellent in flexibility.
(7) The electrical characteristics, especially the charging property, the photosensitivity, the residual potential, etc., should not change when they are repeatedly used. (8) It is necessary to have characteristics such as high resistance to heat, light, temperature, humidity, ozone deterioration, etc., and high stability and durability.

At present, the electrophotographic photosensitive member which has been put into practical use is formed by forming a photosensitive layer on a conductive supporting substrate. In order to satisfy the following requirements, a conductive supporting substrate and a photosensitive layer are formed. An undercoat layer is provided between them. (1) To prevent unnecessary charges from being injected from the conductive supporting substrate to the photosensitive layer to eliminate surface charges on the photosensitive layer, or to prevent image defects due to development.

(2) To cover defects on the surface of the conductive supporting substrate. (3) To improve chargeability. (4) Improving the adhesiveness of the photosensitive layer. (5) Improving coatability. FIG. 1 is a cross-sectional view showing a photoconductor for electrophotography.

Examples of the resin used as the undercoat layer 2 include polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, silicone resin, polybutyral. Resin materials such as resins and polyamide resins, and copolymer resins containing two or more of these repeating units, such as vinyl chloride-vinyl acetate copolymer resins, acrylonitrile-styrene copolymer resins, casein, gelatin , Polyvinyl alcohol, ethyl cellulose, etc. are used. Among these resins, polyamide resin is said to be particularly preferable (Japanese Patent Publication No. 58-45707 and Japanese Patent Publication No. 60-168157).

[0006]

The undercoat layer is formed by immersing a conductive support substrate in a coating liquid for the undercoat layer, pulling it up to apply it, and drying it. However, in the photoconductors produced by these methods, good print quality and electrical characteristics can be obtained in the initial stage, charge accumulation occurs due to repeated use (for example, A4 size 10000 prints), and black spots and residual potentials occur. Defects such as rises in are recognized. Further, the adhesion with the charge generation layer deteriorates, causing problems such as defective printing due to peeling of the film and device failure.

The present inventor has conducted extensive studies on a method for producing an organic photoreceptor for reversal development. As a result, by improving the leveling property of the surface of the undercoat layer, the electrical characteristics are excellent, and it is excellent even after repeated at the initial stage. It has been found that a photoreceptor that can provide printing can be obtained. The present invention has been made in view of the above points, and an object thereof is to provide a method for producing an electrophotographic photoreceptor having excellent initial characteristics and repetitive characteristics by improving the leveling property of the surface of the undercoat layer.

[0008]

According to the present invention, the above object is to provide a coating for an undercoat layer in a method for producing an electrophotographic photosensitive member comprising a conductive substrate and an undercoat layer and a photosensitive layer sequentially laminated on the conductive substrate. It is achieved by immersing the conductive substrate in the working solution, pulling up the conductive substrate at a speed of 2 mm / s or less, and coating the undercoat layer.

[0009]

FUNCTION The deterioration of the leveling property of the undercoat layer is caused by the generation of Benard cells in the undercoat layer during dip coating of the undercoat layer. FIG. 2 is a perspective view showing a Benard cell.
The generation mechanism of the Benard cell is that the solvent evaporates from the coating film, the viscosity of the surface layer increases, the temperature decreases, the density and surface tension of the surface substance increase, and the Benned cells sink inside the coating film. A part with a large amount of solvent and a low surface tension rises from the inside of the coating film, spreads over the surface, and convection occurs. When low-speed film formation (2 mm / s or less) is performed by the dipping method so that convection is unlikely to occur, generation of Benard cells is reduced and surface leveling property is improved.

[0010]

EXAMPLE FIG. 1 shows a cross-sectional view of an essential part of an electrophotographic photosensitive member produced by the manufacturing method according to the present invention. The conductive support base 1 is an aluminum alloy JIS3003 series, 5
000 series, 6000 series alloys, conductive resins, etc. can be applied. These conductive support bases 1 are finished to a predetermined dimensional accuracy by extruding or drawing aluminum or injection molding resin.

If necessary, the surface of the conductive supporting substrate 1 is finished to have an appropriate surface roughness by cutting with a diamond, a cutting tool or the like. Then, the cutting oil used for processing is removed, and cleaning is performed to obtain a clean surface of the conductive support substrate 1. At this time, conventionally, trichlene,
Chlorine-based organic solvents such as CFCs have been used, but in recent years, water-based cleaning agents such as weak alkaline detergents have been used for the purpose of protecting the ozone layer.

Further, as the undercoat layer 2, in consideration of the adhesiveness to the surface of the conductive substrate and the coatability after washing with an aqueous detergent,
Polyvinyl alcohol, melamine, copolyamide,
Polyvinyl butyral or the like is used. The film thickness of the undercoat layer 2 using these materials is preferably 0.5 μm or more.
That is, when used in a laser beam printer, in order to prevent the occurrence of an interference pattern based on the combination of the refractive index of the photosensitive layer, the film thickness, and the light source wavelength, the conductive substrate 1 is processed to have a specific surface roughness or the light source wavelength is adjusted. Techniques such as the addition of an absorbing material that absorbs the light and the addition of fine particles that induce light scattering are used.

A coating liquid for the undercoat layer 2 is prepared by mixing these materials for forming the undercoat layer 2 (a curing agent, a conductivity-imparting agent, etc., in addition to the resin and the interference preventing agent) and an organic solvent. It The coating liquid is used to form the undercoat layer 2 having an appropriate thickness, which is a low-speed film formation (2 mm /
s or less) to suppress the generation of Benard cells and improve the leveling property of the surface.

After the undercoat layer 2 is formed, the film is dried and cured. In this step, an appropriate temperature and time are determined depending on the glass transition temperature of the resin used, the curing temperature when a curing agent is used, the boiling point of the organic solvent, and the like. In some cases, a two-step process is required. In the photoreceptor according to the present invention, the charge generation layer 3 is formed on the undercoat layer 2. The charge generating substance is not particularly limited as long as it is a material having photosensitivity to the wavelength of the laser light source such as metal-free phthalocyanine and various metal phthalocyanines.

The charge transport layer 4 according to the present invention is formed on the charge generation layer 3, and is made of, for example, polyvinylcarbazole,
Contains one or more charge transport materials such as oxadiazole, imidazole, pyrazoline, hydrazone, stilbene,
A resin containing a binder resin and, if necessary, an antioxidant and an ultraviolet absorber is used. Hereinafter, the present invention will be described in detail with reference to Example 1, but the present invention is not limited to this Example 1. Example 1 A conductive substrate 1 having a diameter of 30 mm and a length of 250 mm was obtained using an aluminum alloy having the following composition.

[0016]

[Table 1] (Unit: weight percent) Further, the substrate surface was diamond-finished to have a maximum surface roughness of 0.5 μm.

An aqueous detergent (Lion Co., Ltd. MF)
-10) Immerse in a 5% solution at a temperature of 50 ° C. for 3 minutes for ultrasonic cleaning, then use the same detergent for brush cleaning, city water rinsing (ultrasonic wave addition 3 minutes), pure water rinsing (ultrasonic wave). Addition 3
Min), ultrapure water rinsing, and hot water drying (70 ° C.) to clean the surface. Subsequently, a coating liquid for an undercoat layer having the following composition was prepared, and the substrate was dip coated to form 10
It was formed to a thickness of μm.

Melamine resin (Mitsui Toatsu Chemicals, Cordon 20HS) 50 parts by weight Iodine (Wako Pure Chemical Industries) 6 parts by weight Silicon oxide (hydrophobic silica gel P-212) 1 part by weight Methyl alcohol 700 parts by weight Film formation, drying and curing The conditions are as follows.

Film-forming speed 1 mm / s (no generation of Benard cells) Drying condition 90 ° C., 15 minutes Curing condition 140 ° C., 15 minutes For the charge generation layer 3, a coating solution having the following composition was prepared to a thickness of 0.1 μm. It was dip coated. X-type metal-free phthalocyanine 1 part by weight Polyvinyl butyral 1 part by weight Dichloromethane 98 parts by weight The charge transport layer 4 was prepared by preparing a coating solution having the following composition and dip-coating it to a thickness of 20 μm.

Hydrazone compound (Anan Fragrance: CTC191) 10 parts by weight Polycarbonate (Teijin: L-1225) 10 parts by weight Dichloromethane 80 parts by weight The photoconductor thus prepared is mounted on a laser beam printer for printing. When tested, initial print density was 1.40 (by Macbeth densitometer), blank paper density was 0.07
The number of black dots having a diameter of 0.1 mm or more (according to a Macbeth densitometer) was as good as 4 per drum. Moreover, as a result of the Gobangme test (JIS K5400), peeling was 0/1.
00 was good.

When a printing test was conducted after a running test was performed on 50,000 sheets with this drum, a print density of 1.40 was obtained.
No difference was found between the white paper density of 0.08 and the number of black dots of 5 and the initial value, and no film peeling occurred during the test. Comparative Example 1 A photoconductor was prepared in the same process as in Example 1 except that the amount of methyl alcohol in the undercoat layer was 1000 parts by weight and the film forming speed was 7 mm / s. At this time, a Benard cell (having a size of about 100 μm) is generated on the surface of the undercoat layer.

When a printing test was carried out by mounting the thus prepared photoconductor on a laser beam printer, an initial printing density of 1.40 (by a Macbeth densitometer), a white paper density of 0.05 (Macbeth density) The number of black spots with a diameter of 0.1 μm or more was 4 per drum, which was good, but as a result of the Gobangme test (JIS K5400), peeling was 70
/ 100, which was inferior to the low speed film-forming product.

A running test was attempted with this drum, but peeling occurred on the end face after printing 1000 sheets,
With 0 sheets, peeling occurred in the printed area.

[0024]

According to the method of manufacturing an electrophotographic photosensitive member of the present invention, by forming an undercoat layer at a low speed, generation of a Benard cell is eliminated and the leveling property of the surface is improved, and the undercoat layer and the charge generation layer are formed. As a result, the electrophotographic photoreceptor can be obtained in which the adhesion with and the charge injection efficiency are improved, so that film peeling and charge accumulation during long-term continuous printing do not occur.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a photoconductor for electrophotography.

FIG. 2 is a perspective view showing a Benard cell.

[Explanation of symbols]

 1 Conductive Support Substrate 2 Undercoat Layer 3 Charge Generation Layer 4 Charge Transport Layer

Claims (1)

[Claims] 1. A method for producing an electrophotographic photosensitive member comprising a conductive substrate and an undercoat layer and a photosensitive layer which are sequentially laminated on each other. A method for producing a photoreceptor for electrophotography, comprising: pulling up a conductive substrate at a rate of s or less to apply an undercoat layer.