JPH10171141A - Production of electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress cracking and to form a satisfactory undercoat layer by incorporating DMF as a component of a coating soln. contg. a dissolved organometallic compd. SOLUTION: An undercoat layer 4 is formed on an electrically conductive substrate 1 with a coating soln. made of a soln. of an organometallic compd. in an org. solvent and a photosensitive layer 2, 3 is formed on the undercoat layer 4. In this case, DMF is used as a component of the soln. Since DMF is a high b.p. solvent having high polarity, it is liable to remain in a film after coating and drying, and because of low surface tension (about 1/2 of the surface tension of water), DMF temporarily generates OH<-> ions by solvation with water. The hydrolysis of the organometallic compd. is accelerated, and since power to shrink pores formed in a film during drying is reduced, cracking is suppressed.

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 comprising a conductive support, an undercoat layer and a photosensitive layer, and more particularly to the formation of an undercoat layer having excellent coating film formation stability. The present invention relates to a method for producing an electrophotographic photoreceptor using a coating liquid for electrophotography.

[0002]

2. Description of the Related Art A photosensitive member used in an electrophotographic image forming apparatus uses an organic compound as a charge generating material.
There have been problems such as low chargeability and lack of stability during repeated use. In addition, a defect on the surface of the conductive support, for example, a crystalline substance or the like found in an aluminum alloy may cause a non-uniform defect in the charge generation layer, resulting in black spots or white spots on an image.

As means for solving these problems, it is generally known to provide an undercoat layer between a conductive support and a charge generation layer. Materials for forming the undercoat layer include thermoplastic resins such as polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl methyl ether, polyamide, thermoplastic polyester, phenoxy resin, casein, gelatin, nitrocellulose, polyimide, and polyethyleneimine. Thermosetting resins such as epoxy resins, melamine resins, and phenol resins are known.

However, when the undercoat layer is formed using these resins, if the undercoat layer is made thicker in order to improve the charging property and to suppress coating defects and image quality defects, the sensitivity is lowered. Or the residual potential at the time of repeated use increases. On the other hand, if the undercoat layer is made thinner in order to improve these characteristics, it becomes impossible to sufficiently suppress charging properties, coating defects, and image defects. Further, in order to avoid the above-mentioned problem when the undercoat layer is thickened, a method of dispersing organic or inorganic conductive particles in a resin has been attempted, but the expected performance has not been obtained.

Therefore, a method of using an organometallic compound for the undercoat layer has been proposed (Japanese Patent Laid-Open No. 61-94057). According to this method, it is known that coating defects and image quality defects can be suppressed without causing a decrease in sensitivity and an increase in residual potential. However, when the undercoat layer is formed using an organometallic compound, particularly when 95% by weight or more of the components of the undercoat layer are an organometallic compound, cracks are likely to occur in the order of coating and drying, and good undercoating is achieved. There was a problem that a pulling layer could not be obtained.

As a method for suppressing the occurrence of cracks when an organometallic compound is used as a main component, an alkoxide-based coupling agent is contained, and water is added to a coating solution to preliminarily hydrolyze the solution. A method for performing polymerization has been proposed (Japanese Patent Application Laid-Open No. H4-253067). However, it was not easy to form a subbing layer having a thickness of 0.5 μm or more while suppressing the generation of cracks by this method.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems and provides an electrophotographic apparatus capable of sufficiently suppressing image quality defects without lowering sensitivity and increasing residual potential. It is an object of the present invention to provide a method for manufacturing a photoreceptor.

[0008]

As a result of various studies on the causes of cracks in the undercoat layer, the present inventor has found that dimethylformamide is contained in a coating solution for dissolving an organometallic compound, thereby reducing the occurrence of cracks. It has been found that generation can be suppressed and a good undercoat layer can be formed, and the present invention has been completed. That is, the configuration of the present invention is as follows.

(1) A method for producing an electrophotographic photoreceptor in which an undercoat layer is formed on a conductive support using a coating solution comprising an organic solvent solution of an organometallic compound, and a photosensitive layer is further formed. As a component of the organic solvent solution of the coating solution,
A method for producing an electrophotographic photoreceptor, comprising dimethylformamide.

(2) The method for producing an electrophotographic photosensitive member according to the above (1), wherein the content of dimethylformamide in the organic solvent solution is in the range of 1 to 80% by weight.

(3) The electrophotographic photoreceptor according to the above (1) or (2), wherein an organic compound containing a IV valent metal, a III valent metal or a II valent metal is used as the organometallic compound. Manufacturing method.

(4) As the organometallic compound, Zr, T
(3) The electron according to (3), wherein an organic compound containing at least one metal selected from the group consisting of i, Si, Al, In, Sb, B, Mn (II), Zn and Sn (II) is used. A method for manufacturing a photoreceptor.

(5) The method according to any one of (1) to (4), wherein when two or more kinds of the organometallic compounds are used, at least one of them is used as a silane coupling agent. A method for producing an electrophotographic photoreceptor.

(6) As the organic solvent, alcohols,
The above (1) to (5), wherein one or more solvents selected from aromatic hydrocarbons and esters are used.
The method for producing an electrophotographic photosensitive member according to any one of the above.

(7) The method for producing an electrophotographic photosensitive member according to any one of the above (1) to (6), wherein the organic solvent solution contains water.

(8) The above (1) to (7), wherein water is contained in an amount of 100 to 200 mol% based on the number of moles of the hydrolyzable functional group possessed by the organometallic compound. A method for producing the electrophotographic photosensitive member according to any one of the above.

(9) The method of producing an electrophotographic photosensitive member according to any one of the above (1) to (8), wherein the undercoat layer is formed by a dip coating method.

(10) The undercoat layer has a thickness of 0.5 to 2 μm.
The method for producing an electrophotographic photoreceptor according to any one of the above (1) to (9), wherein

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention uses an organic solvent solution of an organometallic compound containing dimethylformamide as a coating solution, forms an undercoat layer on a conductive support, and further forms a photosensitive layer. A method for producing an electrophotographic photoreceptor, as a component of an organic solvent solution of a coating solution for an undercoat layer,
By using dimethylformamide, it was possible to suppress the occurrence of cracks in the undercoat layer, and to form a good undercoat layer.

In the present invention, although the details of the action of dimethylformamide to suppress the generation of cracks in the undercoat layer are not clear, dimethylformamide has a high polarity,
Since it is a solvent with a high boiling point, it tends to remain in the film during coating and drying, and as a polar solvent, it has a small surface tension (approximately 1/2 of water). OH 2 ^- ions are generated, which promotes the hydrolysis of the organometallic compound and reduces the force for shrinking the pores formed in the film during the drying process, thereby suppressing the occurrence of cracks. It is considered something.

Hereinafter, the present invention will be described specifically.
The photoreceptor to which the present invention is applied is one in which an undercoat layer is provided on a conductive support, and a photosensitive layer is further provided on the undercoat layer. The photosensitive layer may be a single layer or a laminate. FIG. 1 is a schematic diagram showing a cross section of an electrophotographic photoreceptor having a general laminated structure, wherein 1 denotes a conductive support, 2 denotes a charge generation layer, 3 denotes a charge transport layer, and 4 denotes an undercoat layer. . Hereinafter, a description will be given of an example of the electrophotographic photosensitive member having the laminated structure.

The conductive support used in the present invention may be a metal drum or sheet of aluminum, copper, stainless steel or the like,
Drums and sheets obtained by laminating a metal foil such as aluminum on a plastic film or paper, and those obtained by forming a resin layer in which conductive particles are dispersed on a metal or resin drum are also available. The surface of the metal drum can be subjected to a roughening treatment for preventing interference fringes.

The undercoat layer according to the present invention is formed by applying a coating solution obtained by dissolving an organometallic compound in an organic solvent onto a conductive support.
Dry to form. The organometallic compound used in the undercoat layer coating solution of the present invention is a IV-valent metal such as Zr, Ti, or Si;
III-valent metal such as Al, In, Sb, B or Mn (I
Organic compounds having a II-valent metal such as I), Zn, and Sn (II) can be mentioned.

Examples of zirconium organic compounds include zirconium tetraacetylacetonate, zirconium dibutoxybisacetylacetonate, zirconium tributoxyacetylacetonate, zirconium tetrakisethylacetoacetate, zirconium butoxybisethylacetoacetate, zirconium butoxytrisethylacetoacetate, Zirconium tributoxy monoethyl acetoacetate, zirconium tributoxy monoethyl acetoacetate, zirconium tetrakis ethyl lactate, zirconium butoxy bisethyl lactate, bisacetylacetonate ethylsacetoacetate zirconium, monoacetylacetonate trisethylacetoacetate zirconium, bisacetyl Acetonate bisue Zirconium chelate compounds such as Le lactate zirconium; zirconium n- butyrate, can zirconium alkoxide such as zirconium n- propylate is exemplified.

As the titanium organic compound, a titanium orthoester represented by the following general formula (I);
The polyortho titanate represented by I) and the titanium chelate compound represented by the following general formula (III) can be exemplified.

[0026]

Embedded image

[0027]

Embedded image

Ti (L) _n X _4-n (III) (wherein L is a chelating group, X is an ester group, n is an integer of 1 to 4, and the compound having a chelating group is octylene glycol Β- such as acetylacetone
Examples include hydroxycarboxylic acids such as diketone, lactic acid, malic acid, tartaric acid, and salicylic acid; ketoesters such as acetoacetate; and ketoalcohols such as diacetone alcohol. )

Examples of the silicon organic compound include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (Aminoethyl) -γ
-Aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ- Aminopropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, monophenyltrimethoxysilane, monophenyltriethoxysilane, γ- (2-aminoethyl) amino Examples thereof include silane coupling agents such as propyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, and γ-methacryloxypropyltrimethoxysilane.

Examples of the aluminum organic compound include aluminum isopropylate, monoisobutoxyaluminum diisopropylate, aluminum isopropylate, and the like.
Aluminum alcoholates such as aluminum ethylate; aluminum chelate compounds such as aluminum ethyl ethyl acetoacetate diisopropylate, aluminum tris (ethyl acetoacetate), aluminum tris (acetylacetonate), aluminum bisethyl acetoacetate monoacetylacetonate, etc. Can be mentioned.

Examples of the indium organic compound include indium alcoholate such as indium methylate, indium ethylate, indium isopropylate, and indium n-butylate.

Examples of the antimony organic compound include antimony alcoholates such as antimony methylate, antimony ethylate, antimony isopropylate and antimony n-butyrate.

Examples of the boron organic compound include boron alcoholate such as boron methylate, boron ethylate, boron isopropylate, and boron n-ethylate.

Examples of the organic compound having a II-valent metal include manganese (II) bis- (acetylacetonate), zinc (II)
Bis- (acetylacetonate), tin (II) bis- (acetylacetonate) and the like can be mentioned.

The undercoat layer of the present invention is used alone or in combination of two or more of the above-mentioned organometallic compounds. Among them, it is preferable to use an organometallic compound having zirconium. Particularly good results can be obtained in terms of various characteristics. In the present invention, when two or more kinds of organometallic compounds are used in combination, it is preferable that at least one kind is a silane coupling agent, and an undercoat layer having particularly good adhesion to the conductive support is obtained. I can do it. At this time, of the “all” organometallic compounds,
The amount of the silane coupling agent can be arbitrarily selected in the range of 5 to 95% by weight.

The organic solvent used in the present invention contains dimethylformamide as an essential component, and further contains ethanol, methanol, n-propanol, isopropanol, n-
It is used by mixing with at least one selected from alcohols such as butanol; aromatic hydrocarbons such as toluene and xylene; and esters such as ethyl acetate and butyl acetate. The amount of dimethylformamide at that time is suitably in the range of 1 to 80% by weight, preferably 5 to 50% by weight based on the total amount of the organic solvent. If the amount is less than 1% by weight, the effect of suppressing the generation of cracks cannot be obtained. When the coating method is a dip coating method, if the amount exceeds 50% by weight, sagging of the coating film tends to occur, and if the amount exceeds 80% by weight, the sagging becomes remarkable and it becomes difficult to obtain a thick film. .

Further, water may be intentionally added to the coating solution to partially hydrolyze the organometallic compound in advance and partially polymerize the compound. Since dimethylformamide dissolves in water in a wide range, it is a suitable solvent for previously adding water to a coating solution. At this time, the amount of water added is 10 to the number of moles of the hydrolyzable functional group of the organometallic compound.
The content is preferably in the range of 0 to 200 mol%. If the amount of water is less than the above range, the polymerization is not started. If the amount is too large, hydrolysis proceeds excessively and the coating solution becomes cloudy, which is not preferable.

As a method of applying the above-mentioned coating solution on the conductive support, a spray coating method, a blade coating method, a spinner coating method, a bead coating method, a bar coating method, etc. can be used. Is most preferable in that the effects of the present invention can be exerted. The applied coating film is blow-dried or static-dried at a temperature in the range of 110 to 200 ° C, preferably 135 to 180 ° C, for 5 minutes to 6 hours, preferably 7 minutes to 1.5 hours. The thickness of the undercoat layer is in the range of 0.01 to 5 μm, but is preferably set in the range of 0.5 to 2 μm.

The charge generating layer is formed by applying a liquid in which a charge generating material is dispersed in an organic solvent in which a binder resin is dissolved by a spray coating method, a blade coating method, a spinner coating method, a bead coating method, a bar coating method, and the like. The charge generation material is formed directly by a method such as a vacuum evaporation method.

Examples of the charge generating material include azo pigments such as chlorodiane blue, quinone pigments such as anthrone and pyrenequinone, quinocyanine pigments, perylene pigments, perinone pigments, indigo pigments, bisbenzimidazole pigments, vanadyl phthalocyanine, titanyl phthalocyanine, and galium. Phthalocyanine pigments such as phthalocyanine, azurenium salts, squarium pigments, quinacridone pigments and the like can be used.

Examples of the binder resin of the charge generating material include polyvinyl butyral, polyarylate (polycondensate of bisphenol A and phthalic acid), polycarbonate resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, acrylic Insulating resins such as resin, polyacrylamide, polyamide resin, polyvinyl pyridine, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol, and polyvinyl pyrrolidone can be used.

The thickness of the charge generation layer is 0.01 to 5 μm.
Although it is arbitrarily set in a range of m, a range of 0.1 to 0.5 μm is preferable.

The charge transport layer is formed by dissolving a binder resin in an organic solvent and adding a charge transport material thereto, or a solution in which a polymerized charge transport material is dissolved in an organic solvent by a spray coating method. It is applied by a blade coating method, a spinner coating method, a bead coating method, a bar coating method, or the like, and dried to form.

Examples of the charge transport material include polycyclic aromatic compounds such as anthracene, pyrene and phenanthrene, or compounds having a nitrogen-containing heterocycle such as indole, carbazole and imidazole, pyrazoline compounds, hydrazone compounds and triphenylmethane compounds. Triphenylamine compounds, enamine compounds, stilbene compounds and the like are used.

The binder resin for the charge transport layer may be any resin as long as it has a film-forming property.
Polyester, polysulfone, polycarbonate, polymethyl methacrylate and the like are used. As the polymerized charge transport material, a pendant type material such as polyvinyl carbazole, a material containing an arylamine in the main chain, or the like can be used. The thickness of the charge transport layer is 5 to 4
It is arbitrarily set in the range of 0 μm, but is preferably in the range of 15 to 30 μm.

[0046]

The present invention will be described in more detail with reference to the following examples. [Example 1] Acetylacetone zirconium butoxide (13% by weight toluene solution) (Matsumoto Kosho Co., Ltd., Organix ZC540) 20 parts by weight γ-aminopropyltriethoxysilane 2 parts by weight Dimethylformamide (47% by weight) 16 parts by weight 40mm in diameter and 318m in length in solution consisting of components
m of aluminum pipe by dipping and applying
After drying at 10 ° C. for 10 minutes, an undercoat layer having a thickness of 0.5 μm was formed. Observation of this undercoat layer with an optical microscope (× 200) showed no occurrence of cracks.

X-type metal-free phthalocyanine 5 parts by weight Vinyl chloride-vinyl acetate copolymer (manufactured by Union Carbide Co., Ltd., VMCH) 5 parts by weight n-butyl acetate 200 parts by weight Next, the above components were mixed with glass beads having a diameter of 1 mm. A dispersion was prepared by dispersing with a used sand mill for 2 hours, dip-coated on the undercoat layer, and dried at 100 ° C. for 10 minutes to form a 0.2 μm-thick charge generation layer.

Next, the compound represented by the following chemical formula 1
A solution consisting of 1 part by weight of a polymer having a repeating unit represented by the following [Chemical Formula 2] and 6 parts by weight of monochlorobenzene was applied onto the charge generating layer by dip coating.
After drying at 5 ° C. for 1 hour, a charge transport layer having a thickness of 20 μm was formed to obtain a photoconductor for electrophotography. This electrophotographic photoreceptor is attached to a laser printer (XP-1 manufactured by Fuji Xerox Co., Ltd.).
When the image was evaluated by mounting it on 1), no defects such as fog and black spots were found.

[0049]

Embedded image

[0050]

Embedded image

Example 2 Acetylacetone zirconium butoxide (13% by weight toluene solution) (Matsumoto Kosho Co., Ltd., Organix ZC540) 20 parts by weight γ-aminopropyltriethoxysilane 2 parts by weight dimethylformamide (23% by weight) 8 8 parts by weight of isopropyl alcohol 8 parts by weight of electrophotographic photoreceptor in the same manner as in Example 1 except that the coating liquid was changed to a solution containing the above components to form a 0.7 μm-thick undercoat layer. Example 1
The undercoat layer was observed with an optical microscope (× 200) in the same manner as in Example 1. No cracks were observed and no defects such as fog and black spots were observed in the collected images.

Example 3 20 parts by weight of acetylacetone zirconium butoxide (13% by weight in toluene) (Orgatics ZC540, manufactured by Matsumoto Kosho Co., Ltd.) 2 parts by weight of γ-aminopropyltriethoxysilane 20 parts by weight of phenyltriethoxysilane Dimethylform Amide (18% by weight) 5 parts by weight Water 5 parts by weight A solution consisting of the above components was mixed and allowed to stand for 24 hours to form a coating solution for an undercoat layer. An electrophotographic photoreceptor was prepared in the same manner as in Example 1, and evaluated in the same manner as in Example 1. As a result, no crack was observed even by observation with an optical microscope (× 200), and no defects such as fog and black spots were observed in the collected images.

Comparative Example 1 The same coating solution as in Example 1 was used except that 16 parts by weight of dimethylformamide was used instead of 16 parts by weight of dimethylformamide.
An attempt was made to form an undercoat layer having a thickness of 0.4 μm, but after drying, cracks occurred on the entire surface and a part of the undercoat layer was detached from the aluminum pipe, so that the undercoat layer could be formed. Did not.

[Comparative Example 2] In Example 1, Comparative Example 1
A photoconductor for electrophotography was prepared in the same manner as in Example 1 except that the undercoat layer having a thickness of 0.07 μm was formed using the same coating liquid as in Example 1, and evaluated in the same manner as in Example 1. Optical microscope (2
(00 ×), no cracks were observed, but fog and black spots were observed in the obtained image.

Comparative Example 3 The same coating solution as in Example 2 was used except that 8 parts by weight of methanol was used instead of 8 parts by weight of dimethylformamide. I tried to form a pull layer, but after drying,
The undercoat layer could not be formed because cracks occurred on the entire surface and part of the undercoat layer was detached from the aluminum pipe.

Comparative Example 4 A coating solution was prepared in the same manner as in Example 3 except that 5 parts by weight of methanol was used instead of 5 parts by weight of dimethylformamide, but 24 hours after mixing. When this was done, the solution gelled, and an undercoat layer could not be formed.

[0057]

According to the present invention, by adopting the above structure, it is possible to obtain a thick undercoat layer while suppressing the occurrence of cracks. It is possible to form an excellent image without image quality defects such as the above.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an electrophotographic photosensitive member having a laminated structure.

Claims (3)

[Claims] An undercoating layer is formed on a conductive support using a coating solution comprising an organic solvent solution of an organometallic compound,
Further, in the method for producing an electrophotographic photoreceptor for forming a photosensitive layer, dimethylformamide is contained as a component of the organic solvent solution of the coating solution. 2. The method according to claim 1, wherein the content of dimethylformamide in the organic solvent solution is in the range of 1 to 80% by weight. 3. The method according to claim 1, wherein the organic solvent solution contains water.