JPH10288844A - Manufacture of electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for manufacturing the electrophotographic photoreceptor prevented from occurrence of image defects by heat-treating a substrate at a specified temperature after washing it and before coating it with a photosensitive layer. SOLUTION: The aluminum substrate is washed with an aqueous rinsing solution and then heat treated at a temperature of >=125 deg.C, and after that, coated with the photosensitive layer. As the aqueous rinsing solution, water containing a surfactant, a mixture of water and a hydrophilic organic solvent, preferably, a 5-95 weight % organic solvent, especially, containing a dihydroxy compound or its derivative represented by the formula: R<3> -CH(OR<+> )-CH(OR<2> )-R<4> , in which each of R<1> and R<2> is, independently, an H atom or a 1-4C alkyl or acyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing an electrophotographic photosensitive member in which a photosensitive layer is formed by coating an aluminum substrate. In this specification, an aluminum substrate means a substrate made of aluminum in a broad sense including an aluminum alloy.

[0002]

2. Description of the Related Art Production of an electrophotographic photosensitive member by forming a photosensitive layer by coating on an aluminum substrate is one of the main methods for producing an electrophotographic photosensitive member. The aluminum substrate is usually made from an aluminum billet by using a porthole method or a mandrel method to produce an extruded tube, which is then drawn, impacted, ironed or cut to a surface having a predetermined thickness and external dimensions. Is manufactured by processing into a mirror-finished cylinder.

[0003] Oil and various dusts such as drawing oil, cutting oil, rust-preventive oil and the like adhere to the aluminum substrate manufactured in this manner. Therefore, the aluminum substrate is washed prior to coating the photosensitive layer. It is necessary to clean the surface. Conventionally, chlorine-based solvents such as trichloroethylene and fluorine-based solvents such as chlorofluorocarbons have been used for cleaning aluminum substrates.However, with the tightening of regulations on these solvents, the shift to cleaning methods using aqueous cleaning agents has progressed. I am doing it.

As a method of washing an aluminum substrate or anodized aluminum substrate with an aqueous cleaning agent, various solutions of a surfactant added to water or a solution of water and a hydrophilic organic solvent have been studied. For example, JP-A-6-3835 discloses an anionic surfactant such as a carboxylate, a sulfonate, a sulfate ester salt, a phosphate ester salt, an aliphatic amine salt or a fatty acid for washing an anodized aluminum substrate. Nonionic surfactants such as polyethers, polyetheresters and esters; cationic surfactants such as quaternary ammonium salts and quaternary salts of cyclic amines; amphoteric surfactants such as betaine, aminocarboxylic acid and imidazoline derivatives It is described that an aqueous solution containing an activator or the like is used.

[0005] JP-A-5-210246 discloses an aqueous solution containing a nonionic surfactant or an anionic surfactant, or an aqueous solution containing sodium carbonate, sodium tripolyphosphate, potassium pyrophosphate, sodium silicate, sodium sulfate, or the like. It describes that an aluminum substrate is washed with an aqueous solution to which an inorganic builder or an organic builder such as carboxymethylcellulose, methylcellulose, or an organic amine is added. JP-A-6-3831 discloses that
It is described that an aluminum substrate is washed with an aqueous solution containing sodium aliphatic higher alcohol sulfate, alkyltrimethylammonium chloride, alkyldimethylbetaine, an aliphatic higher alcohol ethylene oxide adduct, and the like.

[0006] Japanese Patent Application Laid-Open No. 6-3837 describes that an aqueous alcohol solution is used for cleaning an aluminum substrate which has been anodized. JP-A-7-219244
The publication describes washing an aluminum substrate using a solution containing a pyrrolidone compound such as N-methyl-2-pyrrolidone and water. In addition, Japanese Patent Application Hei 7
-258605 describes washing an aluminum substrate using a solution containing a dihydroxy compound represented by the following formula (1) or a derivative thereof and water.

[0007]

Embedded image R ³ —CH (OR ¹ ) —CH (OR ² ) —R ⁴ (1)

(Wherein R ¹ and R ² are each independently a hydrogen atom, an acyl group having 1 to 4 carbon atoms, or an acyl group having 1 to 4 carbon atoms)
And R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
However, the total number of carbon atoms of R ³ and R ⁴ is 2 or more. )

[0009]

As described above, various proposals have been made for water-based cleaning agents, and improvements are being made. However, electrophotographic photoreceptors using an aluminum substrate cleaned with the water-based cleaning agent have been developed. There is a problem that image defects such as black spots, white spots, and unevenness are likely to occur in a copied image. Above all, image defects often occur in an electrophotographic photosensitive member having a photosensitive layer with high sensitivity, and the resolution of this problem is urgently required with the increasing sensitivity of the photosensitive member.

[0010]

According to the present invention, an aluminum substrate is washed with an aqueous cleaning agent, and then a photosensitive layer is applied thereto to produce an electrophotographic photosensitive member. By subjecting the substrate to a heat treatment at a temperature of 125 ° C. or more before coating, the occurrence of image defects can be significantly reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail.
Various materials conventionally used for this purpose, for example, pure aluminum such as 1050 material, 1070 material, 1080 material, Al-Mg alloy, Al-Cu alloy, Al-
Si alloy, Al-Mg-Si alloy, Al-Cu-S
An aluminum alloy such as an i-based alloy can be used. Preferably, a 3003 material which is an Al-Mg alloy or a 6063 material which is an Al-Si alloy is used. Manufacture of an aluminum base from these materials can be performed by first processing these materials into an extruded tube and then appropriately applying a conventional processing method such as drawing, impact, ironing or cutting.

The aluminum substrate manufactured in this manner is washed with a water-based cleaning agent in order to remove oil and cutting powder adhering to its surface and various dusts.
As the aqueous detergent, various conventionally proposed ones such as a surfactant added to water and a solution of water and a hydrophilic organic solvent can be used. Preferably 5
A mixed solution of water and an organic solvent containing 95% by weight of an organic solvent is used. Particularly preferred aqueous detergents include the following.

A mixed solution of a pyrrolidone compound and water; examples of the pyrrolidone compound include 2-pyrrolidone, 3-pyrrolidone and derivatives thereof, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl- 2-
Pyrrolidone, N-methyl-3-pyrrolidone, N-ethyl-3-pyrrolidone, N-propyl-3-pyrrolidone, N
N-alkyl (or alkenyl) pyrrolidone such as -vinyl-2-pyrrolidone, 5-methyl-2-pyrrolidone and the like are used, but N-methyl-2-pyrrolidone is preferably used. The concentration of the pyrrolidone compound in the mixed solution is usually 50 to 90% by weight, preferably 70 to 80% by weight.
% By weight. It is preferable that the mixed solution contains an antioxidant in order to suppress the generation of peroxide.
Conventional antioxidants such as phenol, phosphite and sulfur can be used. The antioxidant is contained in the cleaning solution in an amount of 0.01 to 5% by weight, particularly 0.05 to 2%.
It is preferable that the content be contained so as to be in a percentage by weight. A mixed solution of a dihydroxy compound represented by the following formula (1) or a derivative thereof and water;

[0014]

Embedded image R ³ —CH (OR ¹ ) —CH (OR ² ) —R ⁴ (1)

(Wherein R ¹ and R ² are each independently a hydrogen atom; an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a butyl group or a formyl group, an acetyl group, a propionyl group, a butyryl group) .R ³ and R ⁴ indicates an acyl group having 1 to 4 carbon atoms such as groups, each independently, .R ³ showing a hydrogen atom or a methyl group, an ethyl group, an alkyl group having 1 to 4 carbon atoms such as butyl group And the total number of carbon atoms of R ⁴ is 2 or more, preferably one is an ethyl group and the other is hydrogen.)

Examples of the compound represented by the above formula include 1,2-butanediol, 1-methoxy-2-butanol, 2-methoxy-1-butanol, 1-ethoxy-2-butanol, and 2-ethoxy-1-butanol. Butanol, 1
-Acetoxy-2-butanol, 2-acetoxy-1-
Butanol and the like are used. The concentration of these compounds in the mixed solution is usually 40 to 95% by weight,
It is preferably from 50 to 90% by weight, especially from 60 to 85% by weight.

The step of cleaning the aluminum substrate with an aqueous cleaning agent to clean the surface is performed by cleaning the aluminum substrate by 30 to 9 times.
Main cleaning in which most of the deposits are removed by immersion in an aqueous cleaning agent at 5 ° C., preferably 40 to 80 ° C., and ultrasonic cleaning or brush cleaning; Finishing cleaning for removing the cleaning agent. The time for the main cleaning is usually 30 minutes or less, and preferably 1 to 10 minutes from the viewpoint of productivity.

In the final cleaning, the aluminum substrate is treated with pure water.
This can be done by rinsing 2-4 times. Preferably tartaric acid
Pure water to which is added. This makes the aluminum substrate
Can suppress hydration reaction with pure water. This
It is OH by the addition of tartaric acid ^-Reduced ions,
And tartaric acid adsorb on the aluminum surface and OH^-ion
It is thought to be due to mitigating attacks by Finish
At least the last stage of the washing is pure water with tartaric acid.
It is particularly preferred to use

The final washing is preferably performed in a rinsing step and a drying step. In the rinsing step, it is preferable to apply ultrasonic waves for the purpose of sufficiently removing residual deposits and aqueous cleaning agents. In the drying step, the purpose is to uniformly evaporate the moisture adhering to the aluminum substrate, thereby preventing the adhering water from being locally concentrated on the surface of the aluminum substrate and causing stains or the like. Usually, the aluminum substrate is immersed in cleaning water to which heating and tartaric acid have been added to raise the temperature, and then gradually pulled up so as not to disturb the interface between the cleaning water and the aluminum substrate. Immediately after leaving the water surface, the deposited water is evaporated by the retained heat. Washing water obtained by adding tartaric acid to pure water at a concentration of 0.3 to 10 ppm, particularly 0.5 to 1 ppm is preferably used at 50 to 95 ° C.,
0-85 ° C., and the aluminum substrate was kept at 5-1 ° C.
After immersion for 00 seconds, especially for 20 to 60 seconds, it is pulled up so as not to disturb the interface with the washing water.

The aluminum substrate that has been subjected to finish cleaning is dried with hot air or the like to sufficiently remove adhered water, and then subjected to the next step of heat treatment. If the final stage of the above-mentioned finish cleaning is performed at a high temperature, it is almost dried even if left alone. The heat treatment of the aluminum substrate is performed at 125 ° C. or more, preferably 140 ° C.
This is performed by heating the aluminum substrate to a temperature of at least ℃. Although the upper limit of the heat treatment temperature is not limited, it is usually 2
The intended purpose can be sufficiently achieved by heat treatment at a temperature of 00 ° C. or lower, preferably 180 ° C. or lower. The time required for the heat treatment is usually at least 5 minutes, and it is generally preferable to perform the heat treatment for 20 minutes or more. The upper limit of the heat treatment time is not limited, but is preferably 1 hour or less from the viewpoint of productivity. Generally, the desired heat treatment effect can be obtained in a shorter time at a higher temperature. The heat treatment can be performed by any conventional heating means such as hot air heating, infrared heating, and induction heating. The heat treatment may be performed in air, and the humidity of the atmosphere is preferably low.
When an electrophotographic photoreceptor is manufactured using an aluminum substrate that has undergone heat treatment, the details of the reason why image defects are significantly reduced are unknown, but the fact that heat treatment inactivates the surface of the aluminum substrate contributes greatly. It is considered something. That is, it is considered that aluminum forms a kind of passivation by forming a thin oxide film on its surface in the atmosphere. In the case of cleaning with a non-aqueous organic solvent, only the deposits are removed without adversely affecting the oxide film. In the case of cleaning with an aqueous cleaning agent, water acts on aluminum or the oxide film on the surface thereof. To partially alter the surface. When the photosensitive layer is applied thereto, it is considered that a coating defect occurs in the deteriorated portion or some reaction occurs between the substrate and the substance forming the photosensitive layer in this portion, and these cause image defects. . However, after washing with a water-based detergent, the temperature is 125 ° C. or higher, preferably 1
When the heat treatment is performed at 40 ° C. or more, the deteriorated portion is stabilized and inactivated, so that it is considered that image defects are reduced. This is because the time required for hydrogen generation when the aluminum substrate washed with an aqueous cleaning agent and then dried is immersed in ultrapure water at 80 ° C. varies greatly depending on whether or not heat treatment is performed after drying and the degree of the heat treatment. it is obvious.

For example, Table 1 shows that an aluminum base made of 1050 material is used as an aqueous cleaning agent containing 1,2-butanediol (Kasei Cleaner KC500, manufactured by Mitsubishi Chemical Corporation).
This is the result of measuring the time required for hydrogen generation in the case of washing, drying, and immersion in ultrapure water at 80 ° C. as it is or after heat treatment at 150 ° C. (aluminum having a clean surface). When immersed in hot water at 80 ° C., air bubbles are generated on the surface because aluminum hydrates with water to produce hydrogen.)

[0022]

Table 1 Time required for hydrogen generation Heat treatment time (minutes) Time required for hydrogen generation (seconds) 0 60 10 67 15 70 20 20 80 30 85 60 60 85

As is clear from Table 1, the surface of the aluminum substrate is gradually deactivated by heat treatment. In the present invention, the heat treatment is preferably performed until the time required for hydrogen generation becomes 70 seconds or more, particularly 80 seconds or more. The heat-treated aluminum substrate is then cooled and then coated with a photosensitive layer by a conventional method. Usually, the photosensitive layer is applied directly on the aluminum substrate, and in this case, the effect of the heat treatment is best exhibited, but if desired, the undercoat layer is applied first, and then the photosensitive layer is applied thereon. It may be.

As is well known, the photosensitive layer includes a laminated photosensitive layer containing a charge generating agent and a charge transfer agent in different layers, and a single layer photosensitive layer containing these in one layer. There is. The present invention can be applied to any type of photosensitive layer, but a laminated type photosensitive layer is preferred. To explain the laminated photosensitive layer, as the charge generating agent, selenium and its alloys, arsenic-selenium, cadmium sulfide, inorganic substances such as zinc oxide, phthalocyanine, azo, quinacridone, quinone, perylene, indigo And organic pigments such as benzimidazoles. Preferably, phthalocyanines or copper, indium chloride, gallium chloride, tin, titanium oxide, zinc, coordinated metal phthalocyanines such as oxides, oxides and halides thereof, such as vanadium, monoazo, bisazo, trisazo, polyazo and the like Is used.

The charge generating layer is usually formed in a state where these charge generating agents are dispersed in a binder in the form of fine particles. As the binder, polyvinyl butyral, phenoxy resin, epoxy resin, polyester, polyvinyl acetate, polyvinyl chloride, methyl cellulose, polycarbonate, polyacrylate, polymethacrylate and the like are used. The charge generator is preferably used in an amount of 20 to 300 parts by weight, particularly 30 to 150 parts by weight, based on 100 parts by weight of the binder. The thickness of the charge generation layer is usually 5 μm.
m, preferably 0.01 to 1 μm.

As the charge transfer agent, high molecular compounds such as polyvinyl carbazole, polyvinyl pyrene and polyacenaphthylene, and low molecular compounds such as pyrazoline derivatives, oxazole derivatives, hydrazone derivatives and stilbene derivatives are used. These charge transfer agents are also usually mixed with a binder and used for forming a charge transfer layer. Examples of the binder include polymers and copolymers of vinyl compounds such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, polycarbonate, polyester, polysulfone, phenoxy resins, epoxy resins, silicone resins, and the like. If desired, a crosslinking agent may be used in combination with the binder to crosslink the binder after the formation of the charge transfer layer. The compounding ratio of the charge transfer agent to the binder is usually 30 to 200 parts by weight of the charge transfer agent to 100 parts by weight of the binder, but preferably 50 to 150 parts by weight of the charge transfer agent to 100 parts by weight of the binder. The charge transfer layer may contain an auxiliary agent such as an antioxidant or a sensitizer, if desired, in addition to the charge transfer agent and the binder. The thickness of the charge transfer layer is usually 10 to 40.
μm, preferably in the range of 13 to 30 μm.

When a single-layer photosensitive layer is formed instead of the laminated photosensitive layer, the combination of the above-mentioned charge transfer agent and the binder for forming the charge transfer layer is further combined with the above-mentioned charge generation agent. May be combined. In this case, binder 1
A total of 20 parts by weight of the charge generating agent and the charge transfer agent
It is preferably in the range of from 200 to 200 parts by weight, particularly preferably in the range of from 40 to 150 parts by weight, and the charge generating agent preferably accounts for 1 to 20% by weight of the whole photosensitive layer.

The present invention can be widely applied to electrophotographic photoreceptors having any sensitivity, but when applied to a high-sensitivity electrophotographic photoreceptor, the effect is well exhibited. Therefore, normally, the half-life exposure amount (E _1/2 ) is 1.5 lux · sec or less,
In particular, it is advantageous to apply the present invention to an electrophotographic photosensitive member of 1.0 lux · sec or less. The half-reduction exposure amount is obtained by charging the photoreceptor surface to a predetermined potential with a corona charger while rotating the photoreceptor at a constant speed in a dark place, and then irradiating this with white light while rotating at the same speed. Is defined as the amount of exposure necessary to reduce the photoconductor surface potential by half from the initial charging potential.

[0029]

The present invention will be described more specifically with reference to the following examples. Example 1 Cleaning and heat treatment of aluminum substrate; aluminum tube made of 1050 material (length 348 mm, mirror-finished surface)
(65 mm in diameter, 1 mm in wall thickness) is immersed in a 65 ° C. water-based cleaning solution composed of 85% by weight of 1,2-butanediol and 15% by weight of pure water, and is subjected to a frequency modulation type ultrasonic oscillator (basic frequency of 39 kHz). Ultrasonic cleaning was performed for 5 minutes. This is 3
After leaving still for 0 seconds to drain the liquid, it was immersed in a 30 ° C. aqueous solution obtained by adding 0.5 ppm of tartaric acid to pure water, and was immersed in a 30 ° C. using a frequency modulation type ultrasonic oscillator (basic frequency 39 kHz).
Ultrasonic cleaning for 2 seconds. Next, brush cleaning was performed while sprinkling with pure water, and the above ultrasonic cleaning was repeated once again.
This aluminum substrate was immersed in an aqueous solution at 80 ° C. in which 0.5 ppm of tartaric acid was added to pure water for 60 seconds, pulled up, allowed to stand, and evaporated to remove attached water. The aluminum substrate that had undergone the above-described treatment was housed in an electric heating type clean oven DM-60S (manufactured by E & M Engineering Co., Ltd.), and heat-treated at 150 ° C. for 30 minutes.

Formation of charge generation layer; 10 parts by weight of a bisazo compound having the following structure (1) was added to 150 parts by weight of 4-methoxy-4-methyl-2-pentanone, and the mixture was pulverized and dispersed by a sand grind mill. The resulting dispersion is
To 100 parts by weight of a solution prepared by dissolving polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., # 6000-C) to a concentration of 5% in 1,2-dimethoxyethane, a solid concentration of 4%
Was obtained. The aluminum substrate subjected to the above-mentioned heat treatment is immersed in the dispersion and pulled up to obtain a dry film thickness of 0.63 μm.
Was formed.

[0031]

Embedded image

Formation of a charge transfer layer: 110 parts by weight of a hydrazone compound of the following (2), polycarbonate 10 having a repeating structure of the following (3) and having a viscosity average molecular weight of about 25,000
0 parts by weight and 8 parts by weight of the phenol compound were dissolved in 500 parts by weight of tetrahydrofuran. The aluminum substrate having a charge generation layer on the surface prepared above was immersed in this solution, pulled up, dried at 125 ° C. for 30 minutes,
A 7 μm charge transfer layer was formed. The half-life exposure amount of this electrophotographic photosensitive member was about 0.9 [lux · sec].

[0033]

Embedded image

Evaluation of Electrophotographic Photoreceptor The electrophotographic photoreceptor obtained above was mounted on a commercially available regular development-type copying machine (SF-2040, manufactured by Sharp Corporation) to perform copying, and the image was evaluated. Six electrophotographic photosensitive members were evaluated, and no image defects were found in any of them. Comparative Example 1 An electrophotographic photoreceptor was manufactured in exactly the same manner as in Example 1, except that the aluminum substrate after washing was not subjected to heat treatment. When the evaluation was performed on the six electrophotographic photosensitive members in the same manner as in Example 1, white streak-like image defects occurred in one of the electrophotographic photosensitive members.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaru Taguchi 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Pref.

Claims (9)

[Claims] 1. A step of cleaning an aluminum substrate with an aqueous cleaning solution to clean the surface.
A method of manufacturing an electrophotographic photoreceptor, comprising sequentially performing a heat treatment at the above temperature and a step of forming a photosensitive layer on a substrate by coating. 2. The method according to claim 1, wherein the step of cleaning the surface by washing with an aqueous cleaning agent comprises: mainly cleaning the aluminum substrate with a mixed solution of water and an organic solvent containing 5 to 95% by weight of an organic solvent;
2. The method for producing an electrophotographic photoreceptor according to claim 1, comprising at least two steps of finishing washing with pure water to which tartaric acid has been added and drying. 3. The step of cleaning the surface by washing with an aqueous cleaning agent is a step of mainly cleaning the aluminum substrate with a solution containing a pyrrolidone compound or a dihydroxy compound represented by the following formula (1) or a derivative thereof and water. 2. The method for producing an electrophotographic photoreceptor according to claim 1, comprising at least two steps: a step of finishing washing with pure water to which tartaric acid is added, and a step of drying. Embedded image R ³ —CH (OR ¹ ) —CH (OR ² ) —R ⁴ (1) (wherein R ¹ and R ² are each independently a hydrogen atom, an acyl having 1 to 4 carbon atoms. R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, provided that R ³ and R ⁴ have the same number of carbon atoms as R ³ and R ⁴ ; The total is 2 or more.) 4. A step of cleaning the surface by washing with an aqueous detergent, a step of mainly washing the aluminum substrate with an aqueous solution containing a surfactant, and a step of finishing washing with pure water to which tartaric acid is added and drying. 2. The method according to claim 1, wherein the method comprises at least two steps. 5. The method according to claim 1, wherein the step of heat-treating the cleaned aluminum substrate is performed at a temperature of 140 ° C. or higher. 6. The method according to claim 1, wherein the heat treatment of the cleaned aluminum substrate is performed so that the hydrogen generation time when the substrate is immersed in pure water at 80 ° C. becomes 70 seconds or more. The method for producing the electrophotographic photosensitive member according to any one of the above. 7. The method according to claim 1, wherein the photosensitive layer is formed in contact with the aluminum substrate. 8. An undercoat layer is formed on an aluminum substrate,
7. The method for producing an electrophotographic photoreceptor according to claim 1, wherein a photosensitive layer is formed thereon. 9. The photosensitive layer having a half-exposure amount of 1.0 [lux ·
[sec] or less.
The method for producing an electrophotographic photosensitive member according to any one of the above.