JPH03113457A - Manufacture of electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance coating performance of a coating fluid for forming a photosensitive layer on an undercoat layer and to prevent occurrence of image defects by coating the undercoat layer with the coating fluid having surface tension stronger than the critical surface tension of the undercoat layer. CONSTITUTION:A conductive substrate is coated with a coating fluid for forming the undercoat layer, and this undercoat layer is coated with the coating fluid for forming the photosensitive layer having surface tension stronger than the critical surface tension of the undercoat layer, thus permitting wettability for coating to be improved, coating defects of the photosensitive layer to be eliminated, and adhesion between the photosensitive layer to be formed and the undercoat layer to be also improved, consequently, the coating performance for forming the photosensitive layer on the undercoat layer to be enhanced and occurrence of image defects to be prevented.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for manufacturing an electrophotographic photoreceptor.

Conventional technology Electrophotographic photoreceptors have a basic structure in which a photosensitive layer is formed on a conductive support. An undercoat layer is provided in order to prevent charge injection, protect against electrical breakdown, or cover defects on the support.

Conventionally, as the undercoat layer, for example, polyvinyl methyl ether, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose (-methyl cellulose,
Resins such as ethylene-acrylic acid copolymer, polyamide, casein, gelatin, polyethylene, polyester, phenol resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, polyvinylpyrrolidone, polyvinylpyridine, polyurethane, polyglutamic acid, polyacrylic acid, etc. It is known to use materials.

A photosensitive layer is formed on the undercoat layer, and as one of the methods for forming the photosensitive layer, a method is often adopted in which a coating M for forming a photosensitive layer is applied.

Problems to be Solved by the Invention Conventionally, when a subbing layer is formed on a conductive support and a coating solution for forming a photosensitive layer is applied thereon, coating film defects such as repelling (pinholes) and unevenness occur. may occur.

In particular, when repelling occurs, image defects such as white spots or black spots occur in the copied image. The cause of coating film defects is thought to be poor coating properties of the coating solution for forming the photosensitive layer, but in the past, efforts have been made to improve the coating properties of the coating solution for forming the photosensitive layer in relation to the undercoat layer. No attempt had been made to measure it.

Therefore, an object of the present invention is to provide a method for manufacturing an electrophotographic photoreceptor that improves the coating properties of a photosensitive layer forming coating liquid on an undercoat layer and that does not cause image defects.

Means for Solving the Problems As a result of studies, the inventors of the present invention have focused on the fact that if the wettability of the photosensitive layer forming coating liquid to the undercoat layer is insufficient, repellency and unevenness are likely to occur. Through these measurements, the present invention was completed.

The present invention provides a method for producing an electrophotographic photoreceptor in which a subbing layer forming coating liquid and a photosensitive layer forming coating liquid are sequentially applied onto a conductive support to form a subbing layer and a photosensitive layer. It is characterized in that a photosensitive layer forming coating liquid having a surface tension smaller than the critical surface tension of the undercoat layer is applied onto the undercoat layer.

The present invention will be explained in detail below.

In the present invention, the conductive support includes a drum or sheet of metal such as aluminum, copper, iron, zinc, nickel, etc., and aluminum, copper, gold, silver, platinum, palladium, titanium, etc. on paper, plastic or glass. Deposit metals such as nickel-chromium, stainless steel, copper-indium, or conductive metal compounds (e.g. In2O5, 5b).
A drum-shaped, sheet-shaped, blade-shaped material, etc., which has been subjected to a conductive treatment by dispersing 20° S n O, S n 02 , TiOx powder, metal powder, etc. in a binder resin and applying it, etc., can be used. The surface of these conductive supports may be roughened by honing treatment or the like.

A coating solution for forming a subbing layer is applied onto the conductive support to form a subbing layer. The coating liquid for forming the undercoat layer may be prepared by dissolving the conventionally known resin material described above in an appropriate solvent, but the surface tension may be higher than that of the coating liquid for forming the photosensitive layer applied thereon. Materials must be selected accordingly.

The critical surface tensions of the main materials used for the undercoat layer are as follows.

Polyvinyl methyl ether-29 dyne/am (hereinafter referred to as
Units omitted), polyethylene oxide = 43, methyl cellulose - 40, ethylene-acrylic acid copolymer - 41
~55, nylon 6-42, nylon 8. B-42,
Nylon L8-34, Nylon 10.10-32, Nylon 11-33, Nylon 8-33, Casein-43,
Phenol resin-52, epoxy resin-35 to 50, polyacrylic acid-29 to 35, etc.

The thickness of the undercoat layer is applied in a range of 0.01 to 10ρ. As a coating method, commonly used methods such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method can be employed.

A photosensitive layer is formed on the conductive layer support provided with the subbing layer, and the photosensitive layer formed may have a single layer structure or may be functionally separated into a charge generation layer and a charge transport layer. It may also have a laminated structure.

When the photosensitive layer has a single layer structure, a photoconductor such as 2.4.7-dolinitrofluorenone is contained in a binder resin, or an inorganic photoconductor such as ZnO or CdS is contained in a binder resin. Examples include dispersed materials and materials made of photoconductive film-forming materials such as polyvinylcarbazole.

In the case of a laminated structure, any known charge generation layer and charge transport layer can be used. The charge generation layer is made by dispersing a charge generation material in a binder resin, and examples of the charge generation material include azo pigments such as chlorodiane blue, quinone pigments such as anthotocan and pyrenequinone, and quinocyanine pigments. , perylene pigments, perinone pigments, indigo pigments, bisbenzimidazole pigments, phthalocyanine pigments such as copper phthalocyanine and vanadium phthalocyanine, azulenium salts, squareium pigments, quinacridone pigments, selenium or selenium alloy particles, and the like. Examples of the binder resin include polycarbonate, polystyrene, polyester, polyvinyl butyral, methacrylic acid ester polymer or copolymer, vinyl acetate polymer or copolymer, cellulose ester or ether, polybutadiene, polyurethane, epoxy resin, etc. Known materials can be used, but the material is not limited to these.

The charge transport layer is formed by containing a charge transport material in a binder resin, and examples of the charge transport material include polycyclic aromatic compounds such as a, anthracene, pyrene, and phenanthrene, or indole and carbazole. , compounds containing nitrogen-containing heterocycles such as imidazole, pyrazoline compounds,
Known compounds such as hydrazone compounds, triphenylmethane compounds, triphenylamine compounds, enamine compounds, and stilbene compounds are used. In addition, as the binder resin, methacrylic acid ester polymers or copolymers such as polyester, polysulfone, polycarbonate, and polymethyl methacrylate, acrylic acid ester polymers or copolymers, zeta vinyl chloride polymers or copolymers, vinylidene chloride polymers or copolymers, vinylidene chloride polymers or copolymers, etc. Polymer or copolymer, polystyrene, vinyl acetate polymer or copolymer, butylene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride Known materials such as copolymers, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, and poly-N-vinylcarbazole can be used.

In the present invention, regardless of whether the photosensitive layer has a single layer structure or a laminated structure, the coating liquid for forming the photosensitive layer applied on the undercoat layer has a critical surface tension smaller than the critical surface tension of the undercoat layer. It is necessary to have surface tension. This improves the wettability of the coating solution for forming a photosensitive layer, and as a result, it is possible to prevent the occurrence of repelling, unevenness, etc. In addition, the wettability is
It is also related to adhesion, and improved wettability also serves to strengthen the adhesion between the undercoat layer and the photosensitive layer.

The surface tension of the coating solution for forming a photosensitive layer is mainly determined by the solvent used, and the surface tension of commonly used solvents is as follows. Acetone-23,7 dyne/clT+
(Units are omitted below), 2-butanone-24, methyl isobutyl ketone-24, cyclohexanone-34,5,
Ethyl acetate-23,8, Lobutyl acetate-25, Anisole #35, Dioxane-37, Tetrahydrofuran =
m26, toluene=28, chlorobenzene-33,2-
Methoxyethanol 1-32, etc.

In the present invention, in order to make the surface tension of the coating solution for forming a photosensitive layer smaller than the critical surface tension of the subbing layer, The following methods can be used: (1) adding additives to the photosensitive layer coating solution to lower the surface tension, such as surfactants and oil-based compounds; Whichever method is used, it should be selected so as not to adversely affect electrophotographic properties.

Examples of the surfactants used include nonionic, cationic, anionic, and amphoteric types.
In consideration of electrical characteristics, nonionic types are preferred. Examples of nonionic surfactants include polyoxyethylene-polyoxypropylene condensate, linear alcohol ethoxylate, nonylphenol ethoxylate, octylphenol ethoxylate, polynuclear phenol ethoxylate, higher alcohol sulfate, higher alcohol ether sulfate, Examples include aromatic phosphate esters, aliphatic phosphate esters, polyoxyethylene glycol oleate, polyoxyethylene glycol stearate, and the like.

Further, examples of the oil-based compound include paraffin oil, paraffin wax, fluorinated paraffin oil, silicone oil, and a silicone-based leveling agent represented by the following general formula.

(In the formula, R represents a hydrogen atom, an alkyl group, an alkylaryl group, an alkoxy group, or an amino group, and n and m represent positive integers.) The surface tension of the additive added to the above solvent is: Usually 1
5 to 25 dynes/am, and these compounds are preferable because they collect on the surface of the solution and can lower the surface tension of the solution with a small amount of C1.

The coating solution for forming the photosensitive layer can be coated by the same coating method as described for the subbing layer.

In the case of a single layer structure, the thickness of the photosensitive layer is generally 0,01~
In addition, in the case of a laminated structure, the charge generation layer has a range of 0.01 to 10 knots, and the charge transport layer has a range of 2 to 100 knots.
The range of addition is appropriate.

Example Hereinafter, the present invention will be explained by examples.

Example 1.2 and Comparative Example 1 1 part of Nylon 8 (trade name Nidresin EF30T, manufactured by Teikoku Kagaku ■) was dissolved in 5 parts of methanol at 60°C, and this solution was dropped little by little into 45 parts of distilled water to dissolve the nylon. 8 was gradually precipitated. The precipitated nylon 8 was separated and 70
It was dried at ~80°C to obtain reprecipitated nylon.

This material had the best properties when combined with the next charge generation layer.

Dissolve 8 parts of the above Nylon 8 in 50 parts of methanol, and
- Prepare a coating solution by adding 42 parts of butanol to 84ml
It was coated on an aluminum pipe with a diameter of 310 mm and dried at 110° C. to form a subbing layer with a thickness of 0.55 mm. The critical surface tension of this undercoat layer is 33 dynes/clT.
It was +.

Next, 8 parts of dibromoanthanthrone pigment and 1 part of polyvinyl butyral resin (trade name 8M-1, manufactured by Sekisui Chemical ■) were added to and mixed with 19 parts of cyclohexanone, and the pigments were dispersed using a sand mill device. The following three coating solutions were prepared using the obtained dispersion.

That is, a coating solution (surface tension 33.6 dyne/cm) (comparative example 1) prepared by adding 20 parts of cyclohexanone to the above dispersion, 20 parts of cyclohexanone and a silicone compound (
Product name: 5l129PA, )-Made by Resilicone ■)
Coating solution with o, oooot added (surface tension 30.2 dyne/am) (Example 1), methyl ethyl ketone 1
8 parts of coating solution (surface tension 31.0 dynes/am)
(Example 2) was prepared.

Each coating solution was applied by dip coating onto the undercoat layer formed as described above, and dried at 100° C. to form a charge generation layer having a thickness of 0.8%. Thereafter, when the surface of the charge generation layer was observed, in the case of Comparative Example 1, repellency of 0.5 stop φ was observed in one out of five samples, whereas in Examples 1 and 2, repellency of 0.5 stop φ was observed. In this case, not a single repellent occurred among 20 samples.

Next, a charge transport layer was formed on this charge generation layer to produce an electrophotographic photoreceptor. That is, N.

4 parts of N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine was used as a charge transport material, and 40 parts of monochlorobenzene was used together with 6 parts of polycarbonate Z resin. The resulting solution was applied by dip coating and dried at 11.0° C. for 1 hour to form a charge transport layer with a thickness of 20 μs.

The electrophotographic photoreceptor obtained as described above was installed in a copying machine (product name: FX2700, manufactured by Fuji Xerox ■),
I performed a copy operation and investigated the image quality.

In the electrophotographic photoreceptor of Comparative Example 1, black spots were generated corresponding to the repelled portions, whereas in Examples 1 and 2, good quality images were obtained.

Example 3 and Comparative Example 2 The surface of an aluminum pipe of 40 nsφ x 310 mm was roughened by honing. The surface roughness after treatment was Ra: 0.18 m+. Copolymerized nylon resin (product 820M) is applied to the surface of this aluminum pipe.
A methanol/butanol solution of 8 (100, manufactured by Toshi ■) was applied using a ring coater to form a subbing layer of 0.6. The critical surface tension of this subbing layer is 34 dynes/c
It was IT+.

1 part of polyvinyl butyral resin (trade name BM-1, manufactured by Mikki Kagaku ■) was dissolved in 19 parts of cyclohexanone. Three parts of X-type metal-free phthalocyanine pigment were mixed into this solution. Next, dispersion was performed using a sand mill using 1 mmφ glass beads as a dispersion medium. Cyclohexanone was further added to the dispersion to prepare a coating solution for forming a charge generation layer with a solid content concentration of approximately 4% (surface tension: 34.2 dynes/am).
. This coating solution was applied onto the undercoat layer by dip coating and dried to form a pre-electrification generation layer with a thickness of 0.2 (
Comparative Example 2) On the other hand, n-butyl acetate was further added to this coating solution to prepare a coating solution with a solid content concentration of 3.5% (surface tension: 30.5 dynes/cm). This coating solution was applied onto the undercoat layer by dip coating to form a charge generation layer having a thickness of 0.2 mm (Example 3).

After that, when the surface of the charge generation layer was observed, it was found that Comparative Example 2
In the case of 0.6 to 0.8, the ratio is 1 per sample.
While repelling of the shaft φ was observed, in the case of Example 3, no repelling occurred at all.

On the charge generation layer formed as described above, a charge transport layer was formed in the same manner as in Example 1 to produce an electrophotographic photoreceptor.

Using these electrophotographic photoreceptors, we attached them to a laser beam printer with a dot density of 400 dpi and evaluated various printed images. However, in the case of the electrophotographic photoreceptor of Example 3, no similar image quality defects occurred.

Effects of the invention As is clear from the above comparison, in the present invention,
Since the coating was carried out using a coating solution for forming a photosensitive layer that has a surface tension lower than the critical surface tension of the undercoat layer, the coating has good wettability and there are no coating defects in the photosensitive layer.
Furthermore, the adhesion between the formed photosensitive layer and the subbing layer is also good, and as a result, the resulting electrophotographic photoreceptor provides copy images of excellent image quality without image defects.

Claims (4)

[Claims] (1) A method for manufacturing an electrophotographic photoreceptor in which a coating solution for forming an undercoat layer and a coating solution for forming a photosensitive layer are sequentially applied onto a conductive support to form an undercoat layer and a photosensitive layer. 1. A method for producing an electrophotographic photoreceptor, which comprises applying a coating liquid for forming a photosensitive layer having a surface tension smaller than the critical surface tension of the undercoat layer on the undercoat layer. (2) The method for manufacturing an electrophotographic photoreceptor according to claim 1, wherein the surface tension of the solvent of the coating liquid for forming the photosensitive layer is lower than the critical surface tension of the undercoat layer. (3) The method for producing an electrophotographic photoreceptor according to claim 1, wherein the coating liquid for forming the photosensitive layer contains a silicone additive. (4) Claim 1, wherein the photosensitive layer comprises a charge generation layer and a charge transport layer, and the surface tension of the coating solution for forming the charge generation layer is smaller than the critical surface tension of the undercoat layer. , the method for producing an electrophotographic photoreceptor according to item 2 or 3.