JP2000171993A - Production of electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to exhibit the same brightness attenuation performance in any place of a latent image forming range. SOLUTION: The production of an electrophotographic photoreceptor by forming a charge transfer layer on a charge generating layer formed on a cylindrical substrate by subjecting the surface of the charge generating layer to dip coating of a coating liquid for forming the charge transfer layer in a coating application vessel 1 is executed in this process. In such a case, the cylindrical substrate formed with the charge generating layer is fixed to the coating application vessel 1 and the coating liquid for forming the charge transfer layer is supplied at a prescribed rate from an opening existing at the bottom end of the coating application vessel 1 and is filled in the coating application vessel 1. The coating application vessel 1 is then rotated 180 deg. in a vertical direction and the coating liquid for forming the charge transfer layer is discharged at the same rate as the supply rate from the opening existing at the bottom end of the rotated coating application vessel 1. As a result, the coating liquid comes into contact with the charge generating layer in any sections thereof for the time equal to the coating liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing an electrophotographic photosensitive member capable of forming an electrostatic latent image with less potential unevenness in an image forming area.

[0002]

2. Description of the Related Art A laminated electrophotographic photoreceptor has a structure of two or more layers. In general, in the case of a two-layer structure, a conductive substrate treated to prevent charge injection is generally used. A charge generation layer is formed thereon, and a charge transport layer is formed thereon. In the case of a three-layer structure, an undercoat layer for preventing charge injection is provided on the conductive substrate, It has a layer structure in which a charge generation layer and a charge transport layer are sequentially provided thereon, and a protective layer may be further provided on the surface.

[0003] Incidentally, the laminated photosensitive layer in these electrophotographic photosensitive members is prepared by dissolving or dispersing an organic photoconductive material together with a binder resin in an organic solvent to prepare a photosensitive member coating solution. The liquid is formed by successively dip-coating the liquid on the conductive substrate and drying it.In general, after laminating the respective functional layers to form the charge generation layer, finally the dip coating of the charge transport layer is performed. After forming and drying, the photosensitive drum is completed. However, the electrophotographic photoreceptor produced in this manner is placed in a full-color printer, and when an image with electronic information is reproduced, even when the involvement of development and the involvement of ROS writing are excluded,
A slight difference occurs in the density in one image print.

Such a subtle difference in density is hardly noticeable in the case of a black image, but in the case of a full-color image in which four colors are superimposed, the difference occurs sensitively particularly in a flesh color portion. In order to provide physical quantification, quantitative display is possible by using an index called color difference. Although the color difference will be briefly described later, when the value exceeds 3 in total due to the involvement of the electrophotographic photosensitive member and the printer, it is recognized that the difference in visual observation, that is, the so-called color tone is different.

[0005] Looking at the correspondence with the photosensitive drum, the upper and lower ends of the photosensitive drum have different colors.
It was found that there was almost no difference in the rotation direction of the photosensitive drum. This is presumed to be due to the difference in the developability of each color, so we investigated the potential of the photoconductor corresponding to the intermediate color and found that there was a gradient in the potential in the direction where this color was different. There was found. The fact that the extraction speed in the dip coating is involved in the formation of the potential gradient is that the difference in the potential in the image plane is reduced by changing the time of dipping in the coating solution for forming the charge transport layer. It was confirmed from the change. In particular, if the immersion time is 1
When the time is longer than a minute, the change is considerably eliminated. Therefore, it is considered that the difference in sensitivity on the surface of the photoconductor is greatly affected by the difference in immersion time.

The charge transport layer is formed by a process in which the drum on which the charge generation layer is formed is once submerged in a coating solution, and then the drum is gradually pulled up. In this case, immediately after submerging at the upper end portion of the drum, pulling up starts approximately several seconds later, the time at which the charge generation layer at the upper end portion of the drum is in contact with the coating solution for forming the charge transport layer, and the lower end portion Unlike the time when the charge generation layer is in contact with the coating solution for forming the charge transport layer, the time taken to divide the entire length of the drum by the drawing speed at the lower end of the drum, usually about several minutes, usually forms the charge transport layer more than the upper end. Long time immersed in coating liquid for use.

The photoreceptor drum manufactured by the above-described commonly-known manufacturing method has a slightly different light attenuation performance at each point on the surface of the drum. , The surface potential is not the same. In particular, the sensitivity substantially increases from the upper end portion to the lower end portion of the drum, and when the potentials at the same exposure are compared, a tendency that the potential is higher at the upper end and lower at the lower end is recognized. The value is -200 V to -3 at a charging potential around -600 V to -700 V used in a general color copying machine, printer, or the like.
In the case of the image range of 00 V, the potential difference between the maximum potential and the minimum potential is about 30 V, and this potential difference contributes to the occurrence of unevenness in the printed image, and particularly in the case of color printing, a delicate color difference within one printing surface. There is a problem that arises.

[0008]

As a result of various experiments and investigations, the present inventors have found that the above phenomenon is caused by the above-mentioned immersion time when the coating liquid for forming the charge transport layer is applied onto the charge generation layer. It was found that the difference was caused by the difference and that the improvement was achieved by eliminating the difference in the immersion time. By the way, at the time of forming the coating film of the drum, particularly at the time of forming the charge transport layer, a ring-like coating apparatus is used as a method of keeping the dipping time in the coating solution for forming the charge transport layer at any place on the drum surface constant. However, this method has problems in mass productivity and production stability.

As another method, a method of lengthening the immersion time in the coating solution for forming the charge transport layer to relatively eliminate the difference in the immersion time and reduce the difference between the upper and lower sensitivities is considered. There was a problem in terms of gender.

[0010] The present invention has been made in view of the above-mentioned problems in the conventional technology, and its object is to provide:
It is an object of the present invention to provide a method of manufacturing an electrophotographic photosensitive member that exhibits the same bright attenuation performance in a latent image forming area, that is, in any part of an image forming area.

[0011]

According to the method of manufacturing an electrophotographic photoreceptor of the present invention, a charge generation layer formed on a substrate is
A charge transport layer is formed by dip-coating a coating liquid for forming a charge transport layer in a coating tank. The substrate on which the charge generation layer is formed is immersed in the coating liquid, and then separated from the coating liquid. In this case, any part of the charge generation layer is brought into contact with the coating solution for the same time.

More specifically, in the method for producing an electrophotographic photoreceptor of the present invention, a charge transport layer forming coating solution is dip-coated in a coating tank on a charge generating layer formed on a cylindrical substrate. To form a charge transport layer,
The cylindrical substrate on which the charge generation layer is formed is fixed in a coating tank,
After supplying the coating liquid for forming the charge transport layer at a predetermined speed from the opening located at the lower end of the coating tank to fill the coating tank, the coating tank is rotated 180 degrees up and down, and the lower end of the rotated coating tank is The charge transport-forming coating solution is discharged from the opening located at the same speed as the supply speed of the coating solution, and any portion of the charge generating layer is brought into contact with the coating solution for the same time.

According to the manufacturing method of the present invention, the charge transport layer is formed in any part of the charge generation layer of the photosensitive drum so that the contact time with the coating solution for forming the charge transport layer is equal. Thus, the same bright attenuation performance is exhibited at any location in the latent image forming range of the photosensitive drum.

In the method for producing an electrophotographic photoreceptor of the present invention, as a coating apparatus for forming a charge transport layer, a conventional apparatus for immersing a substrate in an overflowing dip coating tank while circulating is used. Instead, a hollow coating tank having an opening in the center for fixing the cylindrical substrate and having a shape surrounding the cylindrical substrate is used. The coating tank has openings at the upper and lower ends for supplying and discharging the coating liquid. In order to carry out the present invention, the cylindrical substrate on which the charge generation layer is formed is inserted into the hollow portion of this coating tank, and both ends are fixed by applying a load with a movable contact device such as Teflon, and then the opening at the lower end is opened. , A coating solution for forming a charge transport layer is injected. When the coating tank is full, the valve of the pipe connected to the opening is closed to stop the supply of the coating liquid, and the entire coating tank is rotated 180 degrees. Next, the coating liquid is discharged from the opening located at the lower end. In that case, it is necessary to make the discharge speed of the coating liquid the same as the injection speed of the coating liquid.
Thereby, the time during which the charge generation layer is in contact with the coating solution for forming the charge transport layer becomes equal in any part of the photosensitive drum.

[0015]

Embodiments of the present invention will be described with reference to the drawings. 1 and 2 are schematic structural views of a coating apparatus used in the manufacturing method of the present invention. FIG. 1 shows a case where a charge transport layer forming coating liquid is injected, and FIG. 2 shows a charge transport layer forming coating liquid. FIG. 3 is a view for explaining operations of injecting and discharging the coating liquid for forming a charge transport layer. The coating tank 1 has a vertically and horizontally symmetrical structure. Openings for supplying and discharging a coating liquid are provided at upper and lower ends thereof, and pipes 2 and 3 are attached respectively. The coating liquid reservoir 4 contains a coating liquid 5 for forming a charge transport layer (hereinafter simply referred to as “coating liquid”). A pipe 6 for supplying a coating liquid is attached to a lower end of the coating liquid reservoir, and a return pipe 8 for connecting to a pipe 7 for returning a coating liquid discharged from the coating tank is provided at an upper portion thereof. An air vent tube 9 is provided. In addition,
In the figure, P1 to P3 are pumps, F is a filter, and 1
Reference numeral 0 denotes a circulation pipe for the coating liquid, 11 denotes a tray, and 12 to 15 denote valves that open and close electrically or by pressurized air. Also, a pipe 1 for supplying or collecting the charge transport liquid.
Numerals 6 and 17 are vertically movable so as to be freely joined to and separated from the coating tank. Note that 18 and 1
Reference numeral 9 denotes a movable contact device made of resin for fixing the cylindrical substrate 20 on which the charge generation layer is formed in a liquid-tight manner.

The cylindrical substrate 20 on which the charge generating layer is formed is inserted into the center of the hollow coating tank by a supporting device (not shown), and both ends thereof are moved by resin movable adhesion devices 18 and 19 made of Teflon or the like. Apply load and fix. The coating liquid is injected into the coating tank from the lower pipe 2. At this time, the valve 15 of the pipe 3 located on the upper side is opened, and the air and the solvent vapor existing in the coating tank are discharged. The speed at which the coating liquid is injected and rises on the charge generating layer surface of the cylindrical substrate is set to be equal to the speed at which the coating liquid is withdrawn, that is, the speed at which the thickness of the charge transport layer is determined. The liquid level of the coating liquid rises at a predetermined speed, and when the liquid level reaches the upper end of the coating tank, the injection of the coating liquid ends. More specifically, it ends when the charge transport layer liquid reaches the valve of the upper tube. At this time, the valve 1 of the upper pipe 3
5 and the valve 14 of the pipe 2 at the lower end on the supply side are closed. As a result, the cylindrical substrate and the coating tank have a configuration completely independent of other equipment.

Next, the coating tank is rotated 180 degrees by a central rotation shaft (not shown). Since the coating tank is in the opposite state to that before the coating, the valve 14 of the pipe 2 moved upward is released, and the valve 15 of the pipe 3 moved downward is released.
To release the coating liquid in the coating tank. Thereby, a charge transport layer is formed on the charge generation tank. FIG. 2 shows this case. The charge transport layer forming step is the same as the step of forming a coating film while pulling up the immersed cylindrical substrate in the dip coating step. It is inversely proportional to the drainage rate of the layer liquid. When the coating liquid is discharged, if it is connected to a pump circulation system, it becomes difficult to discharge a fixed amount at a fixed time due to pulsation, clogging of the filter over time, and the like. Therefore, in the present invention, the coating liquid is discharged from the coating liquid reservoir 5 independently of the coating liquid injection system, and is recovered in the coating liquid reservoir 5 by driving the pump P3 provided in the pipe 7. By doing so, the time during which the charge generation layer formed on the cylindrical support and the coating solution for forming the charge transport layer are in contact with each other is the same in any part of the formed charge transport layer. Become. As a result, the electrophotographic photoreceptor manufactured according to the present invention has almost no bias in light attenuation performance when the entire surface is uniformly exposed,
In particular, when used as a photoreceptor for a 4-tandem type full-color printer, there is no difference in image quality, especially color.

The color mentioned here is 1976 according to CIE.
Defined by L ^* , a ^* , b ^* , presented in the year. L ^*
Indicates lightness, and a ^* and b ^* indicate positions on a plane (two-dimensional) when a color space is sliced at a certain L ^* value. The distance in the color space is called a color difference and is represented by ΔE. The color difference is used when expressing the difference between two colors as a physical quantity, and is represented by the following equation.

[0019]

(Equation 1) (Where L ^* ₁ is the lightness of the reference color, a ^* ₁ and b ^* ₁ are the values in the color space of the reference color, L ^* ₂ is the lightness of the color to be compared,
a ^* ₂ and b ^* ₂ are values in the color space of the color to be compared. When ΔE shown here is 3.0 or less, it corresponds to almost no visible color difference.

The method for producing an electrophotographic photoreceptor of the present invention is effective for any photoreceptor structure, but the laminated type photoreceptor having a charge transport layer as a surface layer has a problem in terms of performance against repeated stability and environmental fluctuation. Since it is excellent, it will be described in detail mainly taking that case as an example.

The substrate used in the present invention includes copper,
In addition to conductive metals such as aluminum, nickel, and iron, cylindrical forms of plastic or paper that have been made conductive by depositing a metal on the surface or forming a coating film in which conductive powder is dispersed,
A belt-like or sheet-like material can be used.
In order to prevent interference fringes, the substrate surface can be subjected to a surface roughening treatment by a method such as etching, anodic oxidation, wet blasting, sand blasting, rough cutting, and centerless grinding.

In the present invention, it is preferable to form an undercoat layer on the surface of the substrate for the purpose of preventing image quality defects, improving chargeability and improving adhesion. Examples of the binder and other materials used for forming the undercoat layer include acetal resins such as polyvinyl butyral, polyvinyl alcohol resins, casein, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, and acrylic resins. , Polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin,
Phenol-formaldehyde resin, polymer compounds such as melamine resin, silane coupling agent, zirconium,
Organometallic compounds containing titanium, aluminum, manganese and the like are mainly used.

These compounds can be used alone or as a mixture of a plurality of compounds or as a condensation polymer thereof. Among them, the hydrolysis-condensation polymerizable compound has a high film-forming property, plays a role as a charge injection blocking layer, has a low residual potential of the produced electrophotographic photoreceptor, has little change due to the environment, and has a repetitive property. It is preferable because it has excellent performance such as a small change in potential due to use.

Examples of the hydrolytic condensation polymerizable compound include a silane coupling agent and an organometallic compound containing zirconium, titanium and aluminum. Specifically, as the silane coupling agent, for example, vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3,4-
Epoxycyclohexyl) ethyltrimethoxysilane,
γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (Β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane and the like. Among them, silane compounds particularly preferably used are vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxy Cyclohexyl) ethyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane,
N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane,
and γ-chloropropyltrimethoxysilane.

Examples of the organic zirconium compound include zirconium butoxide, zirconium triethanolamine, acetylacetone zirconium butoxide, ethyl zirconium butoxide acetoacetate, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium octoate, zirconium naphthenate, and lauric acid. Examples include zirconium, zirconium stearate, zirconium isostearate, butoxyzirconium methacrylate, butoxyzirconium stearate, and butoxyzirconium isostearate.

Examples of the organic titanium compound include tetraisopropyl titanate, tetra n-butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium octylene glycolate,
Titanium lactate ammonium salt, titanium lactate,
Ethoxy titanium lactate, titanium triethanol aminate, polyhydroxytitanium stearate and the like can be mentioned.

Examples of the organic aluminum compound include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, and ethyl acetoacetate aluminum diisopropylate.

These hydrolysis-condensation-polymerizable compounds require an appropriate amount of water at the time of the curing reaction, and the condensation reaction causes elimination of an alkoxy component such as a methoxy group, an ethoxy group, or a butoxy group, whereby the condensation polymerization reaction proceeds. . That is, in this curing reaction, a hydrolyzable component such as an alcohol component or a carboxylic acid component in the hydrolyzable polycondensable compound is eliminated, and the polycondensation reaction proceeds to form a cured film on the substrate. In order to accelerate the curing reaction, it is desirable to perform a heat treatment after the water immersion treatment, but the curing reaction can proceed to some extent even at room temperature. The temperature and conductivity of the water used for the water immersion treatment can be arbitrarily adjusted according to the degree of curing. Further, if necessary, a pH adjuster or the like can be added. The immersion time is sufficient as long as the coating film can sufficiently absorb moisture.

In the undercoat layer, various organic or inorganic fine powders can be mixed for the purpose of preventing interference fringes and improving the electrical characteristics. In particular, white pigments such as titanium oxide, zinc oxide, zinc sulfide, lead white, and lithopone; inorganic pigments as extenders such as alumina, calcium carbonate, and barium sulfate; and Teflon resin particles, benzoguanamine resin particles, and styrene resin particles. Molecular substances are effective.
These fine powders are added as necessary, but when added, the weight ratio is 10 to 8 with respect to the solid content of the undercoat layer.
The range of 0% by weight is suitable, preferably 30 to 70% by weight. The particle size of the added fine powder is in the range of 0.01 to 2 μm. If the particle size is too large, unevenness of the undercoat layer becomes severe, and the electrical nonuniformity becomes large, so that image quality defects are likely to occur. On the other hand, if the particle size is too small, a sufficient light scattering effect cannot be obtained.

In preparing the coating liquid for forming the undercoat layer,
The added fine powder is added to a solution in which the resin component is dissolved to perform a dispersion treatment. Means for dispersing the added fine powder in the resin include a roll mill, a ball mill, a vibration ball mill,
An attritor, a sand mill, a colloid mill, a paint shaker and the like can be used.

The undercoat layer is formed by increasing the film thickness.
Although the image quality defect tends to be reduced because the concealing property of the unevenness of the base is enhanced, the electrical repetition stability is deteriorated. Therefore, the film thickness is desirably in the range of 0.1 to 5 μm.

A charge generation layer is formed on the undercoat layer. The charge generation layer is formed by forming the charge generation material by vacuum evaporation or by dispersing and applying the charge generation material in a binder resin and an organic solvent. As the charge generating material, amorphous selenium, crystalline selenium, selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and selenium alloys, zinc oxide, inorganic photoconductive materials such as titanium oxide, metal-free phthalocyanine, Various organic pigments and dyes such as titanyl phthalocyanine, copper phthalocyanine, tin phthalocyanine, various phthalocyanine pigments such as gallium phthalocyanine, squarylium, anthantrone, perylene, azo, anthraquinone, pyrene, pyrylium salts, and thiapyrylium salts are used. Can be In addition, these organic pigments generally have several types of crystal forms, and in particular, phthalocyanine pigments are known in various types including α, β, etc., but sensitivity according to the purpose is obtained. As long as the pigment is used, any crystal type may be used.

The charge generating layer may contain a silane coupling agent or an organometallic alkoxide for various purposes such as preventing aggregation of the charge generating material, improving dispersibility, and improving electrical characteristics. Further, the charge generation material may be a material which has been previously surface-treated with a silane coupling agent or an organometallic compound containing zirconium, titanium or aluminum. Further, the silane coupling agent and the organometallic compound may be added to the coating solution. When these hydrolytic condensation polymerizable compounds are used, the hydrolysis and hardening reaction can be promoted by applying a water immersion treatment after applying the coating liquid for forming a charge generation layer.

As the binder resin for forming the charge generation layer,
For example, polycarbonate resin such as bisphenol A type, bisphenol Z type, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin And vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinyl carbazole and the like. These binder resins can be used alone or in combination of two or more. The compounding ratio of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10 by weight.

As a means for dispersing the charge generating material in the binder resin, a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill or the like can be used. The thickness of the charge generation layer is generally in the range of 0.01 to 5 μm, and preferably in the range of 0.1 to 5 μm.
The range is from 0.05 to 2.0 μm.

The charge transport layer is formed by preparing a coating solution comprising a charge transport material, a binder resin and a solvent, and then applying the solution on the charge generation layer by the above-described method.
Examples of the charge transport material include oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenylpyrazoline, 1- [ Pyridyl- (2)]-3,5-
Pyrazoline derivatives such as bis (p-diethylaminostyryl) pyrazoline; aromatic tertiary amino compounds such as triphenylamine, tri (p-tolyl) amine and dibenzylaniline; N, N'-diphenyl-N, N'- Screw (m
Aromatic tertiary diamino compounds such as -tolyl) benzidine; 1,2,4 such as 3- (p-dimethylaminophenyl) -5,6-bis (p-methoxyphenyl) -1,2,4-triazine; -Triazine derivatives, hydrazone derivatives such as 4-diethylaminobenzaldehyde 2,2-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styrylquinazoline, 6-hydroxy-2,3-
Benzofuran derivatives such as bis (p-methoxyphenyl) benzofuran, p- (β, β-diphenylvinyl)-
Hole transport substances such as α-stilbene derivatives such as N, N-diphenylaniline, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, poly-N-vinylcarbazole and derivatives thereof, chloranyl, bromoanil, anthraquinone Quinone-based compounds, tetracyanoquinodimethane-based compounds, 2,4,7-trinitrofluorenone, fluorenone-based compounds such as 2,4,5,7-tetranitro-9-fluorenone, xanthone-based compounds,
Examples thereof include a thiophene-based compound and the like, and a polymer having a group consisting of the above compound in the main chain or side chain. These electron transport materials can be used alone or in combination of two or more.

As the binder resin for forming the charge transport layer,
For example, acrylic resin, polyarylate resin, polyester resin, bisphenol A type, bisphenol Z
Types such as polycarbonate resin, polystyrene resin,
Insulating resin and rubber such as acrylonitrile-styrene copolymer resin, acrylonitrile-butadiene copolymer resin, polyvinyl butyral resin, polyvinyl formal resin, polysulfone resin, polyacrylamide resin, polyamide resin, chlorinated rubber, polyvinyl carbazole, polyvinyl anthracene And organic photoconductive polymers such as polyvinyl pyrene. These binder resins can be used alone or in combination of two or more.
The compounding ratio of the charge transport material and the binder resin is 10:
The range of 1-1: 5 is preferred.

Examples of the solvent used for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene and xylene, halogenated aromatic hydrocarbons such as chlorobenzene, and ketones such as acetone and methyl ethyl ketone. And halogenated aliphatic hydrocarbons such as methylene chloride, chloroform and ethylene chloride, and cyclic or linear ethers such as tetrahydrofuran, dioxane and ethylene glycol diethyl ether. These organic solvents can be used alone or in combination of two or more. The thickness of the charge transport layer is generally 5 to 50 μm.
m is appropriate and preferably in the range of 10 to 40 μm.

The electrophotographic photosensitive member according to the present invention contains an antioxidant and a light stabilizer in the photosensitive layer for the purpose of preventing the deterioration of the photosensitive member due to ozone, oxidizing gas, light or heat generated in the electrophotographic apparatus. And an additive such as a heat stabilizer. For example, as an antioxidant, hindered phenol, hindered amine, p-phenylenediamine,
Aryl alkane, hydroquinone, spirocumarone,
Examples include spiroidanone and derivatives thereof, organic sulfur compounds, organic phosphorus compounds, and the like. Examples of the light stabilizer include derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine.

Further, at least one kind of electron accepting substance can be contained for the purpose of improving sensitivity, reducing residual potential, and reducing fatigue when repeatedly used. Examples of the electron accepting substance include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, and m-dinitrobenzene. , Chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, phthalic acid and the like. Of these, fluorenone-based, quinone-based and benzene derivatives substituted with electron-withdrawing groups such as chlorine atom, cyano group and nitro group are particularly preferred.

[0041]

Next, the present invention will be described more specifically with reference to examples. In the following examples, "parts" means parts by weight. Example 1 170 parts of n-butyl acetate in which 4 parts of a polyvinyl butyral resin (Eslec BM-S, manufactured by Sekisui Chemical Co., Ltd.) was dissolved, 30 parts of acetylacetone zirconium butoxide and γ
-Aminopropyltrimethoxysilane (3 parts) was mixed and stirred to obtain a coating liquid for forming an undercoat layer. 40 m of this coating solution
The composition was applied on an aluminum substrate having a diameter of mφ and dried by heating at 170 ° C. for 10 minutes to form an undercoat layer having a thickness of 1 μm. The substrate on which the undercoat layer was formed was made to have a conductivity of 0.54 μS / cm,
It was immersed in pure water at a water temperature of 50 ° C. for 30 seconds, air-dried for 5 minutes, and then dried and cured at 170 ° C. for 10 minutes again.

Next, a mixture of 15 parts of x-type non-metallic phthalocyanine as a charge generating material, 10 parts of polyvinyl butyral resin (Eslec BM-S, manufactured by Sekisui Chemical Co., Ltd.) and 300 parts of n-butanol was treated with a sand mill for 4 hours. The charge generation material was dispersed in the resin solution. The obtained coating solution was applied onto the undercoating layer by dip coating and dried by heating to form a charge generation layer having a thickness of 0.2 μm.

Next, N, N'-diphenyl-N, N'-
4 parts of bis (m-tolyl) benzidine and 6 parts of a bisphenol Z-type polycarbonate resin having a molecular weight of 40,000 were added to and dissolved in 80 parts of chlorobenzene. The obtained coating solution was applied to the above-mentioned charge generation layer using a dip coating apparatus shown in FIG. 1 and dried by heating to form a charge transport layer having a thickness of 24 μm. The application conditions were as follows. That is, the coating liquid is supplied from the opening at the lower end so that the liquid level rises at a speed of 115 mm / min. After the coating liquid is completely filled, the coating tank is rotated by 180 ° so that the upper end and the lower end are reversed. I was in a state. Immediately thereafter, the coating liquid was discharged from the opening located at the lower end. The discharge was performed so as to maintain the same supply speed of the coating liquid. As a result, the contact time between the charge generation layer and the coating solution for forming the charge transport layer was equalized at any position on the drum. As described above, an electrophotographic photosensitive member having three layers was manufactured. Next, the electrical performance of the obtained electrophotographic photosensitive member was measured. 700 whole
After charging to V, an average value of 90 points in the circumferential direction was determined for 90 points every 5 mm in the axial direction when the entire surface was exposed to 3.7 mJ / m ² . The values are shown in FIG.

Example 2 30 parts of acetylacetone zirconium butoxide was added to a solution obtained by dissolving 3 parts of polyvinyl butyral resin (Eslec BM-1, manufactured by Sekisui Chemical Co., Ltd.), and mixed and stirred to obtain a coating solution for forming an undercoat layer. . The coating solution was applied on an aluminum substrate having a diameter of 40 mm and dried by heating to form an undercoat layer having a thickness of 1 μm. The substrate on which the undercoat layer was formed was placed in pure water having a conductivity of 0.51 μS / cm and a water temperature of 35 ° C. for 120 minutes.
After immersion in water for 5 seconds and air drying for 5 minutes, a dry curing treatment was performed again at 170 ° C. for 10 minutes.

Next, a mixture of 15 parts of titanyl phthalocyanine as a charge generating material, 10 parts of a vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Co., Ltd.) and 300 parts of n-butanol was treated with a sand mill for 4 hours. The charge generation material was dispersed in the resin solution. The obtained coating solution was applied on the undercoat layer and dried by heating to form a charge generation layer having a thickness of 0.2 μm.

Next, N, N'-diphenyl-N, N'-
4 parts of bis (m-tolyl) benzidine and 6 parts of a bisphenol Z type polycarbonate resin having a molecular weight of 40,000 were added to 80 parts of chlorobenzene and dissolved. The obtained coating solution was applied onto the above-mentioned charge generation layer using a dip coating apparatus shown in FIG. 1 and dried by heating to form a charge transport layer having a thickness of 20 μm. The application conditions were as follows. That is, the coating liquid is supplied from the opening at the lower end so that the liquid level rises at a speed of 130 mm / min. After the coating liquid is completely filled, the coating tank is rotated by 180 ° so that the upper end and the lower end are reversed. I was in a state. Immediately thereafter, the coating liquid was discharged from the opening located at the lower end. The discharge was performed such that the supply speed of the coating liquid was maintained at the same rate. As a result, the contact time between the charge generation layer and the coating solution for forming the charge transport layer was equalized at any position on the drum. As described above, an electrophotographic photosensitive member having three layers was manufactured. Next, the electrical performance of the obtained electrophotographic photosensitive member was measured in the same manner as in Example 1. The measured values are shown in FIG.

Comparative Example An electrophotographic photosensitive member was produced in exactly the same manner as in Example 1, except that a dip coating apparatus known as a method for forming a charge transport layer was used. Next, the electrical performance of the obtained electrophotographic photosensitive member was measured in the same manner as in Example 1.
The measured values are shown in FIG.

[0048]

According to the method of manufacturing an electrophotographic photoreceptor of the present invention, when the charge transport layer is formed after the formation of the charge generation layer, the immersion time in the coating solution for the charge transport layer is reduced. Since the sensitivity (bright decay ability) of the electrophotographic photoreceptor is almost equal in any place of the latent image forming range, when the photoreceptor is used as a color photoreceptor, In particular, it is possible to reduce the color difference.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a dip coating apparatus used in a production method of the present invention, showing a case where a coating liquid is injected into a dip coating tank.

FIG. 2 is a diagram illustrating a case where a coating liquid is discharged from a dip coating tank in the dip coating apparatus of FIG.

FIG. 3 is a diagram illustrating an operation of injecting and discharging a coating liquid.

FIG. 4 is a distribution diagram of an axial potential after exposure in Examples 1 and 2 and a comparative example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... dip coating tank, 2, 3 ... pipe, 4 ... coating liquid reservoir, 5 ... coating liquid for charge transport layer formation, 6, 7 ... pipe, 8 ... return pipe,
9 ... air vent pipe, 10 ... coating liquid circulation pipe, 11 ... receiving pan, 12-15 ... valve, 16, 17 ... pipe, 1
8, 19: movable contact device, 20: cylindrical substrate on which a charge generation layer is formed, F: filter, P1 to P3: pump.

Continued on front page F-term (reference) 2H068 AA37 AA54 EA16 EA36 FA12 FB11 4D075 AB02 AB13 AB16 AB41 DA15 DC19

Claims (2)

[Claims] 1. A method according to claim 1, wherein the charge generation layer is formed on a substrate.
In a method for producing an electrophotographic photoreceptor in which a charge transport layer is formed by dip-coating a charge transport layer forming coating solution in a coating tank, the substrate on which the charge generation layer is formed is immersed in the coating solution, and then coated. A method for producing an electrophotographic photosensitive member, characterized in that any part of the charge generation layer is brought into contact with the coating solution for the same period of time when separating from the liquid. 2. A method for producing an electrophotographic photoreceptor in which a charge transport layer is formed by dip coating a charge transport layer forming coating solution in a coating tank on a charge generation layer formed on a cylindrical substrate. After fixing the cylindrical substrate on which the charge generation layer is formed to the coating tank, and supplying the coating liquid for forming the charge transport layer at a predetermined speed from the opening located at the lower end of the coating tank to fill the coating tank , Rotate the coating tank up and down 180 degrees,
The charge transport forming coating liquid is discharged from the opening located at the lower end of the rotated coating tank at the same speed as the supply rate of the coating liquid. A method for producing an electrophotographic photoreceptor, comprising: