JPH07219244A - Production of electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To prevent the occurrence of image defects such as black spots, white spots and unevenness of a halftone image on a copied image by washing the surface of an electric conductive substrate with a washing liq. contg. a pyrrolidone compd. CONSTITUTION:The surface of an electric conductive substrate is washed with a washing liq. contg. at least a pyrrolidone compd., especially a washing liq. based on N-methyl-2-pyrrolidone and water. The pyrrolidone compd. is, e.g., 2-pyrrolidone, 3-pyrrolidone, N-alkyl-2-pyrrolidone, 5-alkyl-2-pyrrolidone, N- vinyl-2-pyrrolidone or N-alkyl-3-pyrrolidone but N-methyl-2-pyrrolidone is especially effective. In the washing liq., 5-100wt.%, preferably 50-95wt.% pyrrolidone and 0-95wt.%, preferably 5-50wt.% water are contained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrophotographic photosensitive member, and more particularly to a method for cleaning an electrophotographic photosensitive member.

[0002]

2. Description of the Related Art Generally, an electrophotographic photosensitive member is one in which a photoconductive layer is formed on a cylindrical conductive substrate. Materials used as the cylindrical conductive substrate include aluminum, iron,
Examples thereof include stainless steel, copper, zinc, nickel, conductive plastics, glass, and the like. Among them, aluminum is widely used because it is relatively inexpensive, lightweight, has good workability, and does not impair electrical characteristics.

When aluminum is usually used as a drum-shaped substrate, an aluminum billet is processed into an extruded tube by a porthole method, a mandrel method, or the like, and subsequently, a drum having a predetermined wall thickness and outer die size is drawn out. It can be made by processing, impact processing, ironing, or mirror finishing by cutting. Mist of drawing oil used for drawing oil and mirror finishing, dust in the air,
Since chips and the like adhere, the photoconductive layer is provided after cleaning and removing the surface of the substrate. As the photoconductive layer, various inorganic and organic photoconductive layers can be used, but it is extremely useful to use a laminated photoconductive layer including a charge generation layer and a charge transfer layer.

The charge-generating layer and the charge-transporting layer are prepared by immersing the drum-shaped conductive substrate in a coating method containing the substances constituting the charge-generating layer and the charge-transporting layer, respectively, by a known method. Formed on the surface of. The dip coating method carried out here is not particularly limited and known methods can be used. Examples thereof include the methods disclosed in JP-A-49-130736, JP-A-57-5047 and JP-A-59-46171. To be

If the surface of the conductive substrate, which is a pretreatment in the dip coating method, is insufficiently cleaned, oil, dust, etc. remain on the surface and cause defects such as coating irregularities and coating defects such as foreign substances during coating. become. The defects generated on the electrophotographic photosensitive member appear as black spots, white spots, and unevenness of a halftone image on the copy image, which adversely affects the image quality and is not suitable for practical use.

As the method for cleaning the surface of the substrate, dipping cleaning is usually carried out by dipping the substrate in an organic solvent or an organic solvent heated as necessary under the action of ultrasonic waves; Contact cleaning in which the solvent is physically contacted with a brush, sponge, etc. while being dipped in the solvent or sprinkling the solvent on the substrate; jet cleaning in which the solvent is jetted from the nozzle to the substrate surface under high pressure and vapor cleaning in which the substrate is inserted into solvent vapor The surface of the substrate is cleaned by using these alone or in combination.

Examples of the organic solvent used here include chlorine-based solvents such as methylene chloride, ethylene chloride, 1,1,1-trichloroethane, trichloroethylene and perchlorethylene, CFC-112 and CFC-113.
And the like, mixed solvents such as methanol, methylene chloride and the like, benzene, toluene, methanol, ethanol, isopropyl alcohol, petroleum hydrocarbons and mixtures thereof. However, these solvents have flammability and ignition properties,
Since it is harmful to the human body, it has a low permissible concentration for use and a low detergency. Most commonly used are 1,1,1-trichloroethane and trichloroethylene.

However, although these organic solvents have the advantages of high detergency and easy handling (nonflammability), the former is presumed to be one of the substances causing global warming, ozone layer depletion, etc. It has been decided to abolish it by 1995. The latter is also subject to stricter environmental regulations year after year,
It is required to provide an alternative cleaning solution for these organic solvents or to develop an alternative cleaning method.

Therefore, as an alternative to chlorine-based organic solvents such as 1,1,1-trichloroethane and trichlorethylene,
So-called water-based cleaning has been proposed in which immersion cleaning is performed in pure water or water containing a surfactant.

Further, although the oil content is removed by dissolution by the above-mentioned washing with the organic solvent, it is difficult to remove inorganic dirt such as Si and Ca. On the other hand, the aqueous cleaning liquid is effective for removing the above-mentioned inorganic dirt by removing the oil component by dispersing, emulsifying and solubilizing the surfactant contained therein.

However, in the case of an organic solvent, the contaminated cleaning liquid can be repeatedly used by distillation regeneration, but since the aqueous cleaning liquid is difficult to recover and regenerate, it is disposed of at the end of the liquid life, which is a cost disadvantage. .

Further, in the drying after washing with the organic solvent, the solvent is instantly evaporated by being released into the air and the drying is completed, but in the case of the conventional water-based washing, the components in the washing liquid and the dust in the air are used. Due to the influence of the adherence, the unevenness of drying and stains tend to be formed on the surface of the conductive substrate. An electrophotographic photosensitive member manufactured using this conductive substrate has a black spot on a copy image,
Image defects such as white spots and uneven halftone images often occur.

[0013]

Therefore, it is possible to provide a cleaning liquid which has a cleaning power equal to or higher than that of a chlorine-based organic solvent such as 1,1,1-trichloroethane or trichlorethylene, and which has a low cleaning cost, and further has conductivity. In electrophotographic photoreceptors in which a photosensitive layer is formed after washing a photosensitive substrate, it is strongly desired to develop a method for producing an electrophotographic photoreceptor that does not cause image defects such as black spots, white spots, and halftone image unevenness in copy images. It was rare.

[0014]

As a result of intensive studies by the present inventors, the surface of a conductive substrate is washed with a cleaning liquid containing at least a pyrrolidone compound, particularly a cleaning liquid containing N-methyl-2-pyrrolidone and water as main components. By doing 1, 1, 1
-It has a detergency equal to or higher than that of a chlorine-based organic solvent such as trichloroethane or trichlorethylene, and a long life of the washing liquid can be achieved. Further, they have found that the use of such a washed photoreceptor can solve the problem of image defects such as black spots, white spots, and unevenness of halftone images in the copy image, and reached the present invention.

The present invention will be described in detail below. The conductive substrate of the electrophotographic photosensitive member used in the present invention is not particularly limited as long as it is suitable for the present invention, but aluminum or aluminum alloy is mainly used. The aluminum substrate used in the present invention can be produced by impact processing, ironing processing, or mirror surface processing by cutting. Before the photoconductive layer is formed, the cleaning process shown below is mainly performed because mist of cutting oil, cutting oil used for mirror finishing, dust in the air, chips, etc. are attached to the substrate surface. However, it is (1) degreasing and washing step, (2)
It is divided into three steps, a water washing step and (3) a drying step.

(1) Degreasing cleaning: First, the aluminum substrate is treated in a degreasing tank. The degreasing tank is filled with the cleaning solution of the present invention as a cleaning solution, the cleaning solution is kept at a constant temperature by a heater, and an ultrasonic oscillator is provided in the lower part of the degreasing tank, and when the aluminum substrate is immersed. Ultrasonic waves are generated. During the immersion, the aluminum substrate may be swung if necessary.

The cleaning liquid used in the present invention is characterized by containing at least a pyrrolidone compound, and particularly preferably contains a pyrrolidone compound and water. As the pyrrolidone compound, 2-pyrrolidone, 3-pyrrolidone,
N-alkyl-2-pyrrolidone (for example, N-methyl-
Pyrrolidone, N-ethyl-2pyrrolidone, N-propyl-2-pyrrolidone), 5-alkyl-2-pyrrolidone (for example, 5-methyl-2-pyrrolidone), N-vinyl-
2-pyrrolidone, N-alkyl-3-pyrrolidone (for example, N-methyl-3-pyrrolidone, N-ethyl-3-pyrrolidone, N-propyl-3pyrrolidone) and the like are exemplified, but especially N-methyl-2. -Pyrrolidone is effective.
The above pyrrolidones may be used alone or as a mixture of two or more kinds.

The content ratio of the pyrrolidone compound and water in the cleaning liquid of the present invention is 5 to 100% by weight of pyrrolidone and 0 to 9 of water.
It can be selected from the range of 5% by weight, but preferably the content of pyrrolidone is 50 to 95% by weight, 50 to 90% by weight, more preferably 70 to 80% by weight, and water is 50 to 5% by weight, preferably 50 to 10% by weight, more preferably 3
It is preferable to contain 0 to 15% by weight. If the water content is too small, it becomes an emulsion and it is difficult to repeatedly use the detergent, and there is a risk of ignition. On the other hand, if there is too much water, the cleaning effect will be impaired. However, when the cleaning power may be low, the cleaning liquid may be diluted with water before use.

In addition, it is preferable to add an antioxidant to the cleaning liquid of the present invention in order to suppress the generation of peroxide. The antioxidant is 0.01 to 5.0% by weight, preferably 0.05 to 2.0%, more preferably 0.05 to 5.0% by weight in the cleaning liquid.
It is good to add 1.5%. Examples of the antioxidant include phenol antioxidants, phosphite-based antioxidants, and sulfur-based antioxidants as exemplified below.

(1) Phenolic antioxidant: 2,6-
Di-tert-butyl-4-methylphenol, 2,5
-Di-tert-butylhydroquinone, 2,6-di-t
ert-butyl-α-dimethylamino-P-cresol and other monophenolic compounds, 4,4′-bis (2,6
Di-tert-butylphenol), 2,2'-methylene-bis (4-methyl-6-tert-butylphenol), 4,4'-methylene-bis (2,6-di-ter)
t-butylphenol), 4,4′-butylidene-bis (3-methyl-6-tert-butylphenol), and other bisphenol compounds, 4,4′-thiobis (3-methyl-6-tert-butylphenol), 2, 2'-
Thiobis (6-tert-butyl-o-cresol),
Thiobisphenol compounds such as 2,2′-thiobis (4-methyl-6-tert-butylphenol), tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, Tris (2-methyl-4-hydroxy-5-ter
Trisphenol compounds such as t-butyl-phenol) butane.

(2) Phosphite antioxidants: triphenylphosphite, trisnonylphenylphosphite, trioctylphosphite, tris (mono and di-
Nonylphenyl) phosphite and the like. (3) Sulfur-based antioxidants: dilauryl thiodipropionate, distearyl thiodipropionate, etc. Further, the cleaning liquid of the present invention may contain a nonionic surfactant. Nonionic surfactants include polyoxyethylene stearyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene alkylphenyl ethers such as polyoxyethylene octyl phenyl ether, and polyoxyethylene alkylphenyl ethers. Examples thereof include oxyethylene fatty acid ester or amide, perfluoroalkyl group-containing ethylene oxide adduct, perfluoroalkyl group-containing oligomer, and other fluorine-containing nonionic surfactants. Among them, polyoxyethylene alkylphenyl ether is preferable, and in this case The number of moles of ethylene oxide added is usually 1 to 30, preferably 2-1.
It is 5. The above nonionic surfactants may be used alone or in a mixture of two or more.

The content of the nonionic surfactant in the cleaning solution is 0.001 to 20% by weight, preferably 0.01 to 5%.
It is advisable that the content be 0.01% to 2% by weight. The effect of containing the additive is exhibited even in a very small amount, and the additive can be contained in a relatively wide range. However, if the content is too large, no further improvement in cleaning effect is observed, and
It is not preferable because it may emulsify with the oil to increase the adhered oil. In addition, silicates such as sodium metasilicate and sodium orthosilicate may be added to the cleaning liquid of the present invention as pH adjusters. The amount of silicates added is preferably 0.001 to 20% by weight, more preferably 0.005 to 10% by weight, in the cleaning liquid.

The cleaning liquid of the present invention is, for example, Ka.
Sei cleaner (manufactured by Mitsubishi Kasei Co., Ltd.) can be used. The processing temperature of the degreasing tank is preferably set in the range of 30 to 80 ° C, preferably 40 to 60 ° C. When the treatment temperature is lower than 30 ° C., the degreasing property is poor, so that uneven cleaning easily occurs. When the treatment temperature exceeds 70 ° C., drying unevenness is likely to occur, which is not preferable.

The processing time of the degreasing tank is 10 seconds to 30 minutes, preferably 30 seconds to 5 minutes. If the treatment time is less than 10 seconds, the degreasing property is insufficient, so that uneven cleaning is likely to occur. If the treatment temperature exceeds 30 minutes, the throughput decreases, which is not preferable in actual production. (2) Washing step: The aluminum substrate after the degreasing treatment is rinsed in a washing tank. Although tap water may be used for washing with water, pure water or ion-exchanged water is preferably used. As a water washing method, a water washing tank may be filled with these waters, and the aluminum substrate may be immersed and rinsed, or the aluminum substrate may be showered by spraying. Further, washing with water by a combination of both may be used. In the case of immersing and rinsing, if treatment is carried out by the action of ultrasonic waves, water adhering to the substrate can be cut off from the substrate surface and diffused into water.

(3) Drying step: The aluminum substrate after being washed with water removes the moisture adhering to the surface of the substrate by a drying step. Examples of the drying means include hot water drying, hot air drying, and infrared drying, but any means can be used as long as it is a method of removing water on the surface of the substrate. In the case of hot water drying, pure water or ion-exchanged water is filled, the aluminum substrate is immersed in a tank kept at a constant temperature by a heater, and then the substrate is pulled up at a constant rate. In the case of hot air drying, the water on the surface of the substrate is removed by using air heated to a constant temperature by a heater. In the case of infrared drying, attach an infrared heater at a position facing the aluminum base,
The substrate is evenly heated to remove water.

When pure water or ion-exchanged water used for washing water and hot water drying is used, pure water having a specific resistance of at least 1 MΩcm is preferable. On the aluminum substrate washed as described above, the laminated photoconductor including the charge generation layer and the charge transfer layer is provided. The charge generation layer and the charge transport layer are formed on the surface of the aluminum substrate by a spray method, a dip coating method or the like with a coating solution containing each of the substances forming the charge generation layer and the charge transport layer.

Examples of the photoconductor used in the charge generation layer include selenium and its alloys, arsenic-selenium, cadmium sulfide, zinc oxide, other inorganic photoconductors, phthalocyanines, azo, quinacridones, polycyclic quinones, perylenes, indigo,
Various organic pigments such as benzimidazole can be used. In particular, metal-free phthalocyanines; phthalocyanines coordinated with metals such as copper, indium chloride, potassium chloride, tin, oxytitanium, zinc, vanadium, or oxides or chlorides thereof; monoazo, bisazo,
Azo pigments such as trisazo and polyazos are preferred.

The charge generation layer is formed as a uniform layer of these substances or in the state of fine particles dispersed in a binder. Examples of the binder resin used here include polyvinyl butyral, phenoxy resin, epoxy resin, polyester resin, acrylic resin, methacrylic resin, polyvinyl acetate, polyvinyl chloride, methyl cellulose, polycarbonate, and resin.

It is preferable to add 100 parts by weight of the binder resin and 20 to 300 parts by weight of the above-mentioned photoconductor, and particularly preferably 30 to 150 parts by weight. The thickness of such a charge generation layer is usually 5 μm or less, preferably 0.01 to 1 μm.
m is suitable.

As the charge transfer material used in the charge transfer layer, a polymer compound such as polyvinylcarbazole, polyvinylpyrene, polyacenaphthylene, or various pyrazoline derivatives, oxazole derivatives, hydrazone derivatives,
Low molecular weight compounds such as stilbene derivatives can be used.
A binder resin is blended with these charge transfer materials as needed. As a preferred binder resin,
Polymethyl methacrylate, polystyrene, vinyl polymers such as polyvinyl chloride and copolymers thereof, polycarbonate, polyester, polysulfone, phenoxy resin, epoxy resin, silicone resin and the like, and also partially cross-linked cured products thereof are used. It

The charge transfer material is replaced with a binder resin 10
It is preferable to add 30 to 200 parts by weight, especially 50 to 150 parts by weight in 0 part by weight. Further, the charge transfer layer may contain various additives such as an antioxidant and a sensitizer, if necessary. The thickness of the charge transfer layer is usually 10 to 40 μm.
m, preferably 10 to 25 μm.

As another example of the photoconductive layer, there is a dispersion type photoconductive layer in which the photoconductive particles as described above are dispersed in a binder made of a binder resin and the charge transfer material. In this case, the total content of the photoconductor and the charge transfer material is 20 to 100 parts by weight of the binder resin.
200 parts by weight is preferable, and 40 to 150 parts by weight is particularly preferable.

[0033]

According to the method of the present invention, a detergency equal to or higher than that of a chlorine-based organic solvent such as 1,1,1-trichloroethane or trichlorethylene can be obtained. Became possible. Further, the cleaning liquid of the present invention contains N-methyl-2-pyrrolidone as a main component, but since it is a high boiling solvent, there is no danger of explosion due to flammability and ignition. Furthermore, it has low toxicity and biodegradability, so it is environmentally friendly. Therefore, problems such as global warming, destruction of the ozone layer, and effects on the human body and the environment due to the use of chlorine-based organic solvents can be solved. In addition, by collecting and recycling the waste liquid generated in the degreasing and washing processes, it has become possible to significantly reduce the manufacturing cost. Further, the electrophotographic photosensitive member using the aluminum substrate washed with the cleaning liquid of the present invention has reduced image defects such as black spots and white spots, has little deterioration in characteristics even after long-term use, and has excellent environmental stability. Indicates.

[0034]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

A cylindrical aluminum substrate having a mirror-finished surface and a thickness of 1 mm was dipped in a cleaning liquid having the following composition, and degreased and cleaned at 60 ° C. for 2 minutes under ultrasonic irradiation. Subsequently, washing with water was performed using pure water having a specific resistance of 1 MΩcm or more. Further, the surface of the substrate was dried with hot air at 95 ° C. until the water content disappeared, and the cleaning treatment was completed.

(Cleaning liquid) N-methyl-2-pyrrolidone 8
20 parts by weight of water, 0.05 parts of antioxidant were added to 0 parts by weight, and sodium metasilicate was further added to adjust the pH to about 8.
Adjusted to 0.

1 part of a bisazo compound was used as a charge generating substance, 20 parts of dimethoxyethane was added to this, and a dispersion treatment was carried out with a sand grinder. Then, a polyvinyl acetal resin (trade name: Denka Butyral # 6000C, manufactured by Denki Kagaku Kogyo KK) was used. ) 0.5 part was added to a solution prepared by dissolving 10 parts of dimethoxyethane to obtain a charge generation layer forming dispersion liquid. An aluminum substrate, which had been previously washed, was applied by dip coating to this dispersion liquid, and a charge generation layer was provided so that the film thickness after drying was 0.63 μm. 110 parts of a hydrazone compound having the following structure as a charge transport material on the charge generation layer,

[0038]

[Chemical 1]

Polycarbonate resin having the following repeating structural unit (viscosity average molecular weight: about 22000) 100
Department,

[0040]

[Chemical 2]

A solution was prepared by dissolving 8 parts of the phenol compound in 500 parts of tetrahydrofuran, an aluminum substrate provided with a charge generation layer was applied by dip coating to the solution, and dried at 125 ° C. for 20 minutes. The film thickness after drying is 21
An electrophotographic photosensitive member was manufactured by providing a charge transfer layer so as to have a thickness of μm.

[0042]

[Comparative Example] Ultrasonic cleaning of a cylindrical aluminum substrate having a mirror-finished surface with a thickness of 1 mm in trichloroethylene 5
Min, rinse 3 minutes, and steam cleaning 3 minutes in the same order, except that the cleaning treatment was performed to manufacture an electrophotographic photoreceptor.

The obtained electrophotographic photosensitive member was first charged to −600 v by a corona charger in the dark and then exposed to a halogen lamp at 1 lux · sec and 5 lux · sec, respectively, and surface potentials VH and VR, respectively. Further -60
Dark decay D when left in the dark for 5 seconds while charged to 0v
The DR was measured and the electrical characteristics were evaluated.

Next, the electrophotographic photosensitive member was mounted on a commercially available copying machine, and image evaluation was carried out with white solid, black solid and halftone.

The results are shown in the table below.

[Table 1]

(Note) Regarding the number of white spots, black spots, and (halftone) unevenness in the table, the number of photoconductors having the defects is counted as a defective product. As a result, the electrophotographic photoreceptor using the cleaning liquid of the present invention retains the same electrical characteristics as conventional ones, and also has image defects such as black spots, white spots, and unevenness that occur on the surface during copy image formation. It can be seen that it is improved to the same level or higher.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Taguchi 1000, Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryo Kasei Co., Ltd.

Claims (10)

[Claims] 1. A method of manufacturing an electrophotographic photosensitive member comprising a conductive substrate and at least a photoconductive layer provided on the conductive substrate, the surface of the conductive substrate being washed with a cleaning liquid containing at least a pyrrolidone compound. Method for manufacturing electrophotographic photoreceptor. 2. The pyrrolidone compound is N-methyl-2.
-The method for producing an electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is pyrrolidone. 3. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the cleaning liquid contains at least a pyrrolidone compound and water. 4. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the surface of the electroconductive substrate is immersed and washed in the cleaning solution, washed with water and then dried. 5. The cleaning is carried out before the treatment for forming alumite on the surface of the conductive substrate.
Or the method for producing an electrophotographic photosensitive member according to item 3. 6. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the cleaning is performed after a treatment for forming alumite on the surface of the conductive substrate. 7. The surface of the conductive substrate is washed to remove stains attached to it during the production of the conductive substrate.
Or the method for producing an electrophotographic photosensitive member according to item 3. 8. The method for producing an electrophotographic photoreceptor according to claim 1, 2 or 3, wherein the cleaning liquid contains a nonionic surfactant. 9. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the cleaning liquid contains an antioxidant. 10. The method for producing an electrophotographic photosensitive member according to claim 1, 2 or 3, wherein the cleaning liquid contains a silicate.