JPH10186690A - Production of electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dropping of a liquid on the whole or a part of a conductive base body and to form a uniform coating film. SOLUTION: In the production method of an electrophotographic photoreceptor, a conductive base body is dipped in a coating liquid and drawn up from the liquid to form a coating film on the conductive base body. The temp. of the conductive base body is controlled in such a manner that both of the absolute difference of temp. between the upper part of the conductive body and the lower part of the body just before dipping and the absolute difference of temp. between the upper part of the body and the lower part of the body just after drawing are between 0 deg.C and 2 deg.C. The coating liquid contains one of a charge producing material, a charge transfer material or a binder resin for a base coating layer.

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 an electrophotographic photosensitive member in which a conductive substrate is immersed in a coating solution, and the conductive substrate is pulled up from the coating solution to form a coating film on the conductive substrate. About the method.

[0002]

2. Description of the Related Art A dip coating method has been widely used as a method for producing a drum-shaped electrophotographic photosensitive member because of its excellent productivity. In this dip coating method,
In general, a conductive substrate, which is an object to be coated, is lowered into a coating solution, and the conductive substrate is immersed to a point where it is desired to be coated, and then the conductive substrate is pulled up and dried, so that the conductive substrate is dried. Since a coating film is formed, it is important to prevent a dripping of the coating liquid and to form a uniform coating film.

[0003] In order to prevent coating liquid dripping, Japanese Patent Application Laid-Open
Japanese Patent Application Publication No. 50836 discloses a technique for promoting drying of a coating film by maintaining a high temperature of a conductive substrate. However, if only the temperature of the substrate is set high, the viscosity of the coating solution on the surface of the substrate increases, and liquid dripping sometimes occurs. Japanese Patent Application Laid-Open No. 7-319181 discloses a technique for preventing the liquid dripping by setting the temperature of the conductive substrate to be low and reducing the viscosity of the coating liquid on the surface of the conductive substrate. However, if the temperature of the substrate is set too low with respect to the liquid temperature, the substrate may blow out from the opening of the substrate during the immersion of the coating solution, resulting in significant defects in the coating film. In this way, the conventional technology prevents coating liquid dripping,
It was insufficient for the purpose of forming a uniform coating film.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in consideration of a problem that cannot be solved by the prior art, and prevents liquid dripping on the whole or a part of a conductive substrate and forms a uniform coating film. It is an object of the present invention to provide a method of manufacturing an electrophotographic photoreceptor capable of performing the above-described processes.

[0005]

Means for Solving the Problems As a result of extensive studies, the present inventors have controlled the difference between the temperature of the upper portion of the conductive substrate and the temperature of the lower portion before and after dip coating the conductive substrate with the coating solution. By doing so, we found that we could achieve the above objectives,
The invention has been completed.

That is, the present invention relates to a method for producing an electrophotographic photoreceptor in which a conductive film is formed on a conductive substrate by immersing the conductive substrate in a coating solution and pulling up the conductive substrate from the coating solution. The absolute value of the difference between the temperature of the upper portion of the conductive substrate immediately before immersion and the temperature of the lower portion of the conductive substrate immediately before immersion,
And the temperature of the conductive substrate is adjusted so that the absolute value of the difference between the temperature of the upper portion of the conductive substrate immediately after the pulling and the temperature of the lower portion of the conductive substrate immediately after the pulling is both greater than 0 ° C and less than 2 ° C. It is characterized by controlling.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

FIG. 1 shows an example of an electrophotographic photosensitive member supporting means used in a method of manufacturing an electrophotographic photosensitive member having a cylindrical conductive substrate 14. As shown in FIG. 1 (A), the supporting means includes a horizontally arranged rectangular plate-shaped pallet 10, and ventilation holes 16 are formed in the pallet 10 in a matrix. As shown in FIG. 1 (B), on the lower surface side of the pallet 10, a chuck 12 having a rubber tip 12A whose diameter can be changed by air pressure is attached to the axial direction of the chuck 12 and a ventilation hole 16A. Are fixed so that the axis direction of the is parallel to the axis direction.

The conductive base 14 is supported under the pallet 10 by press-fitting the distal end 12A into the conductive base 14 and pressing the distal end 12A against the conductive base 14. The conductive substrate 14 supported by the supporting means is put into a heating furnace (not shown) by a conveying means (not shown), and is heated there for a predetermined time. Next, the conductive substrate 14 supported by the support means is taken out of the drying furnace by a transport means (not shown), and blows downward from the cool air supply duct when it is disposed immediately below a cool air supply duct (not shown). The air is cooled by the cool air that has passed through the ventilation holes 16. Next, the conductive substrate 14 supported by the supporting means is immersed in a coating liquid in a coating bath (not shown) by a lifting means (not shown), and then pulled up.
It is dried by a drying means (not shown).

The method of controlling the temperature of the conductive substrate immediately before immersion by cooling after heating is merely an example of the method of controlling the temperature of the conductive substrate in the method of manufacturing an electrophotographic photosensitive member, and is used in the present invention. A possible method of controlling the temperature difference between the upper and lower portions of the conductive substrate is not limited to this.

In the present invention, the temperature of the upper portion of the conductive substrate 14 immediately before immersion and the temperature of the lower portion of the conductive substrate 14 immediately before immersion are adjusted by adjusting the temperature of the cold air, the intensity of the wind, and the cooling time. And the absolute value of the difference between the temperature of the upper portion of the conductive substrate 14 immediately after being raised and the temperature of the lower portion of the conductive substrate 14 immediately after being pulled are both larger than 0 ° C. and smaller than 2 ° C. Thus, the temperature of the conductive substrate 14 is controlled. As described above, by adjusting the upper and lower temperatures of the conductive substrate 14 before and after coating, dripping of the coating liquid is prevented, and a uniform coating film is formed. In the present invention, the upper portion of the conductive substrate 14 refers to a region from the upper end of the conductive substrate to 10% of the length of the conductive substrate, and the lower portion of the conductive substrate 14 refers to a region from the lower end of the conductive substrate to the conductive portion. Refers to a region of up to 10% of the length of the conductive substrate, and it is necessary that the absolute value of the temperature difference at any point in both regions is larger than 0 ° C and smaller than 2 ° C.

The coating solution is usually maintained at a predetermined temperature. In the present invention, the set temperature is preferably 15 ° C. to 30 ° C. If the coating liquid temperature is lower than 15 ° C,
Maintaining the relationship between the upper and lower temperatures of the conductive substrate 14 before and after the application as described above is too costly. On the other hand, when the temperature of the coating solution is higher than 30 ° C., the amount of the solvent of the coating solution evaporates, and the cost is too high in order to ensure environmental safety during manufacturing.

The electrophotographic photoreceptor produced by the method for producing an electrophotographic photoreceptor of the present invention comprises an undercoat layer, a charge generation layer, a charge transport layer, and other necessary layers on a conductive substrate in any order. The present invention may be used in any of the steps of forming these layers. Further, the electrophotographic photoreceptor manufactured by the method for manufacturing an electrophotographic photoreceptor of the present invention may have a single layer on a conductive substrate.

Examples of the conductive substrate include metals such as aluminum, nickel, chromium, and stainless steel, aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, and ITO.
And the like, such as a plastic film provided with a thin film such as the above, paper coated or impregnated with a conductivity imparting agent, and a plastic film.

If necessary, various surface treatments may be applied to the surface of the conductive support within a range that does not affect the image quality.
Oxidation treatment, chemical treatment, coloring treatment, irregular reflection treatment such as graining, etc. of the surface can be performed.

A binder resin is used for the undercoat layer. As the binder resin usable for the undercoat layer, polyethylene resin,
Polypropylene resin, acrylic resin, methacrylic resin,
Polyamide resin, vinyl chloride resin, vinyl acetate resin, phenol resin, polycarbonate resin, polyurethane resin, polyimide resin, vinylidene chloride resin, polyvinyl acetal resin, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol resin, water-soluble polyester resin, nitro Cellulose, casein, gelatin, polyglutamic acid, starch, starthiacetate, amino starch, polyacrylic acid, polyacrylamide, zirconium chelate compound, zirconium alkoxide compound, titanyl chelate compound, titanyl alkoxide compound, organic titanyl compound, silane coupling agent, etc. There are known materials, but the materials are not limited to these. These binder resins can be used alone or in combination of two or more.

The charge generation layer contains a charge generation material as a main component,
A binder resin and, if necessary, known binders, plasticizers and sensitizers can be used. Examples of the charge generation material include azo pigments, disazo pigments, quinone pigments, quinocyanine pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, phthalocyanine pigments, quinacridone pigments, pyrylium salts, azurenium salts, and tricrystalline selenium. However, the present invention is not limited to these. These charge generation materials can be used alone or in combination of two or more. Further, it can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane.

The binder resin usable for the charge generation layer can be selected from a wide range of insulating resins.
Preferred binder resins include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin And known insulating resins such as polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinylpyrrolidone resin, but are not limited thereto. These binder resins can be used alone or in combination of two or more.

The charge transport layer is formed by including a charge transport material in an appropriate binder resin. As a charge transport material, 2,5-bis (p-diethylaminophenyl)-
Oxadiazole derivatives such as 1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1-
Pyrazoline derivatives such as [pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline; aromatic tertiary amino compounds such as triphenylamine and dibenzylaniline; N '
-Diphenyl-N. Aromatic tertiary diamino compounds such as N'-bis- (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine; 3- (4'-diethylaminophenyl) -5,6 1,2-, 4-triamine derivatives such as -di- (4'-methoxyphenyl) -1,2,4-triazine, hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1'-diphenylhydrazone, 2-phenyl- Quinazoline derivatives such as 4-styrylquinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di (p-methoxyphenyl) benzofuran, p
Α-stilbene derivatives such as-(2,2′-diphenylvinyl) -N, N-diphenylaniline, “Journa
l of Imaging Science "29: 7
10 to (1985), an enamine derivative,
Poly-N-vinylcarbazole such as N-ethylcarbazole and derivatives thereof, poly-γ-carbazoleethylglutamate and derivatives thereof, pyrene, polyvinylpyrene, polyvinylanthracene, polyvinylacridine,
Known charge transport materials such as poly-9-biphenylanthracene, pyrene / formaldehyde resin, ethylcarbazole / formaldehyde resin can be used,
It is not limited to these. These charge transport materials can be used alone or in combination of two or more.

The binder resin used for the charge transport layer is a polycarbonate resin, a polyester resin, a methacrylic resin, an acrylic resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polystyrene resin, a polyvinyl acetate resin, a styrene-butadiene copolymer. , Vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly Known resins such as -N-vinylcarbazole may be mentioned, but not limited thereto. These binder resins can be used alone or in combination of two or more.

The solvent used for preparing the coating liquid for the undercoat layer, the charge generation layer and the charge transport layer includes, for example, methanol,
Alcohols such as ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; ethers such as tetrahydrofuran, dioxane and ethylene glycol monomethyl ether; and aliphatic halogenated carbons such as chloroform, dichloromethane, dichloroethane, carbon tetrachloride, and trichloroethylene. Hydrogens,
Generally, electrophotography of amides such as N, N-dimethylformamide and N, N-dimethylacetamide, esters such as methyl acetate and ethyl acetate, and aromatics such as benzene, toluene, xylene, monochlorobenzene, and dichlorobenzene. Known organic solvents used for preparing a coating solution for the photoreceptor can be mentioned, but are not limited thereto. These solvents can be used alone or in combination of two or more.

[0022]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. In addition, the composition of the compound and the composition of the coating solution used in Examples and Comparative Examples are as follows. Coating solution A (undercoat layer ) 20 parts by weight of zirconium compound of structural formula (1) 2 parts by weight of silane coupling agent of structural formula (2) 2 parts by weight of polyvinyl butyral resin of structural formula (3) 70 parts by weight of n-butanol

[0023]

Embedded image

Coating solution B1 (charge generation layer) Chlorgallium phthalocyanine 5 parts by weight Vinyl chloride-vinyl acetate copolymer of structural formula (4) 5 parts by weight n-butyl acetate 65 parts by weight Xylene 130 parts by weight The dispersion obtained by dispersing for 2 hours with a sand mill using glass beads was used as a coating liquid B1.

[0025]

Embedded image

Coating solution B2 (charge generation layer) Chlorgallium phthalocyanine 5 parts by weight Vinyl chloride-vinyl acetate copolymer of the structural formula (4) 5 parts by weight n-butyl acetate 195 parts by weight The above components were used with 1 mmφ glass beads. The dispersion obtained by dispersing with a sand mill for 2 hours was used as a coating liquid B2. Coating liquid C1 (charge transport layer) 1 part by weight of charge transport material of structural formula (5) 1 part by weight of polycarbonate resin of structural formula (6) 1 part by weight of monochlorobenzene 3 parts by weight of tetrahydrofuran 3 parts by weight

[0027]

Embedded image

Coating solution C2 (charge transport layer ) 1 part by weight of charge transport material of structural formula (5) 1 part by weight of polycarbonate resin of structural formula (6) 1 part by weight of monochlorobenzene 6 parts by weight (Examples 1-3) of 30 mmφ × 340 mmL The cylindrical aluminum substrate is fixed to the apparatus shown in FIG. 1 with a chuck, and the aluminum substrate is cooled by cooling air before coating,
The undercoat layer (coating liquid A) is applied to the aluminum substrate by pulling up the aluminum substrate at a pulling speed such that the average dry film thickness becomes 1.0 μm, and is naturally dried for 2 minutes. Dried for minutes. Coating solution temperature, upper part of aluminum substrate before and after coating (30 minutes from upper end)
mm) and the temperature at the lower part (the position 30 mm above the lower end) were set as shown in Table 1, respectively.

In the following Examples and Comparative Examples, the measurement positions of the temperature of the aluminum substrate are the same. (Comparative Examples 1 to 3) Coating was performed in the same manner as in Examples 1 to 3, except that the temperature of the coating solution and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 1, respectively.

[0030]

[Table 1]

(Examples 4 to 6) 30 mmφ × 340 mm
The cylindrical aluminum substrate of L is fixed to the apparatus shown in FIG. 1 with a chuck, and the aluminum substrate is cooled by cooling air before coating, and the charge generation layer (coating solution B1) is dried to a dry average film thickness of 0.2 μm. The composition was applied at a pulling rate as described above and allowed to dry naturally for 20 minutes. The coating solution temperature and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 2, respectively. (Comparative Examples 4 to 6) Coating was performed in the same manner as in Examples 4 to 6, except that the temperature of the coating solution and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 2, respectively.

[0032]

[Table 2]

Examples 7 to 9 Except that the temperature of the coating solution and the temperatures of the upper and lower portions of the aluminum substrate before and after the coating were set as shown in Table 3, and that the coating solution B1 was changed to B2, the same as in Examples 4 to 9 was used. 6 was applied. (Comparative Examples 7 to 9) The coating liquid temperature and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 3, respectively, and the coating liquid B1 was changed to B2.
The coating was performed in the same manner as in Examples 4 to 6, except that

[0034]

[Table 3]

(Examples 10 to 12) 30 mmφ × 340
The cylindrical aluminum substrate of mmL is fixed to the apparatus shown in FIG. 1 with a chuck, and before coating, the aluminum substrate is cooled by cooling air so that the charge transport layer (coating solution C1) has a dry average film thickness of 20 μm. The aluminum substrate was pulled up and applied at an appropriate pulling rate, air-dried for 2 minutes, and then dried at 135 ° C. for 60 minutes. Coating liquid temperature,
The temperatures of the upper and lower portions of the aluminum substrate before and after coating were set as shown in Table 4, respectively. (Comparative Examples 10 to 12) Coating was performed in the same manner as in Examples 10 to 12, except that the temperature of the coating solution and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 4, respectively.

[0036]

[Table 4]

(Examples 13 to 15) Examples 10 to 15 were repeated except that the temperature of the coating solution and the temperatures of the upper and lower portions of the aluminum base before and after coating were set as shown in Table 5, and the coating solution C1 was changed to C2. 12 was applied. (Comparative Examples 13 to 15) Example 10 except that the temperature of the coating solution and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 5, and the coating solution C1 was changed to C2.
-12.

[0038]

[Table 5]

(Examples 16 to 18) 30 mmφ previously coated with the charge generation layer (coating solution B1) in the same manner as in Example 4.
A 340 mmL cylindrical aluminum substrate was fixed to the apparatus shown in FIG. 1 with a chuck, and before coating, the aluminum substrate was cooled with cooling air to form a charge transport layer (coating solution C1).
The aluminum substrate was pulled up at a pulling rate such that the dry average film thickness became 20 μm, applied, air-dried for 2 minutes, and then dried at 135 ° C. for 60 minutes. The coating solution temperature and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 6, respectively. (Comparative Examples 16 to 18) Coating was carried out in the same manner as in Examples 16 to 18, except that the temperature of the coating solution and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 6, respectively.

[0040]

[Table 6]

(Examples 19 to 21) 30 mmφ × 3 previously coated with an undercoat layer (coating solution A) in the same manner as in Example 1.
A 40 mm cylindrical aluminum substrate is fixed to the apparatus shown in FIG. 1 with a chuck, and before coating, the aluminum substrate is cooled by cooling air, and the charge generation layer (coating solution B1) is dried to a dry average film thickness of 0.2 μm. The aluminum substrate was pulled up at such a pulling speed and applied, followed by natural drying for 20 minutes. The coating solution temperature and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 7, respectively. (Comparative Examples 19 to 21) Coating was performed in the same manner as in Examples 19 to 21, except that the temperature of the coating solution and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 7, respectively.

[0042]

[Table 7]

(Examples 22 to 24) A 30 mmφ × 340 mmL cylindrical aluminum substrate to which an undercoat layer (coating solution A) and a charge generation layer (coating solution B1) were applied in advance in the same manner as in Example 19 was prepared as shown in FIG. The aluminum base was cooled by a cooling air before coating,
The charge transport layer (coating solution C1) was dried at an average film thickness of 20 μm.
The aluminum substrate is pulled up at a pulling speed such that the coating is performed, and the coating is naturally dried for 2 minutes.
C. and dried for 60 minutes. The coating solution temperature and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 8, respectively. (Comparative Examples 22 to 24) Coating was performed in the same manner as in Examples 22 to 24, except that the temperature of the coating solution and the upper and lower temperatures of the aluminum substrate before and after coating were set as shown in Table 8, respectively.

[0044]

[Table 8]

The film thickness of the electrophotographic photosensitive members obtained in Examples 1 to 24 and Comparative Examples 1 to 24 was measured at a position 30 mm below the upper end and at a position 30 mm above the lower end to evaluate the uniformity of the coating film. did.

Examples 1 to 3 (undercoat layer) and Comparative Examples 1 to
In the evaluation of the coating property of No. 3 (undercoat layer), it was determined to be good when the absolute value of the difference between the film thicknesses of the upper and lower portions of the aluminum base was 0.1 μm or less.

The coating of Examples 4 to 9 (charge generation layer), Examples 19 to 21 (charge generation layer), Comparative Examples 4 to 9 (charge generation layer) and Comparative Examples 19 to 21 (charge generation layer) In the evaluation of the film properties, it was determined to be good when the absolute value of the difference between the film thicknesses of the upper and lower portions of the aluminum substrate was 0.02 μm or less.

Coating Properties of Examples 10 to 18 (Charge Transport Layer), Examples 22 to 24 (Charge Transport Layer), Comparative Examples 10 to 18 (Charge Transport Layer) and Comparative Examples 22 to 24 (Charge Transport Layer) In the evaluation of, it was determined that the sample was good when the absolute value of the difference between the film thicknesses of the upper and lower portions of the aluminum base was 2 μm or less.

The evaluation results are shown in Tables 1 to 8, respectively.

[0050]

The method for producing an electrophotographic photoreceptor of the present invention comprises:
Since the temperature difference between the upper part and the lower part of the conductive substrate immediately before immersion and immediately after lifting is within a certain range, it is possible to prevent liquid dripping in the whole or a part of the conductive substrate, and there is no coating defect. A uniform coating film can be obtained.

[Brief description of the drawings]

FIG. 1 shows an example of a schematic configuration of a support means of an electrophotographic photosensitive member for carrying out the present invention.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 10 Pallet 12 Chuck 12A Tip part 14 Conductive substrate 16 Ventilation hole

Claims (4)

[Claims] 1. A method for producing an electrophotographic photoreceptor in which a conductive substrate is immersed in a coating solution, and the conductive substrate is pulled up from the coating solution to form a coating film on the conductive substrate. The absolute value of the difference between the temperature of the upper portion of the conductive substrate and the temperature of the lower portion of the conductive substrate immediately before immersion, and the difference between the temperature of the upper portion of the conductive substrate immediately after the pulling and the temperature of the lower portion of the conductive substrate immediately after the pulling The absolute value of which is greater than 0 ° C. 2
A method for producing an electrophotographic photoreceptor, wherein the temperature of the conductive substrate is controlled so as to be lower than ℃. 2. The method according to claim 1, wherein the coating liquid contains a charge generating material. 3. The method according to claim 1, wherein the coating liquid contains a charge transporting material. 4. The method according to claim 1, wherein the coating liquid contains a binder resin for an undercoat layer.