JPH05216254A - Washing method for conductive base body for electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent the generation of spilling and staining due to washing failure by washing the surface of a conductive base body for an electrophotographic sensitive body with pure water, an ion-exchange water or surfactant-contg. water, then subjecting the base body to a rinsing treatment under air blowing. CONSTITUTION:A machined base body 1 is subjected to the washing treatment under the ultrasonic vibration by an ultrasonic oscillator 17 with the washing liquid 18 contg. a surfactant in a 1st washing tank 11. The base body is then subjected to the rinsing treatment with pure water or an ion-exchange water in respective 2nd, 3rd, 4th washing tanks 21, 31, 41. Bubble generating mechanisms by air blow are respectively mounted to the respective washing tanks 21, 31, 41, by which the surfactant, swarf dust, etc., sticking to the washed base body surface are completely removed. Ultrasonic waves are not used at the time of the rinsing treatment in such a manner and, therefore, the generation of pinholes by the cavitation generated by the ultrasonic waves is prevented and a non-defective rate is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a conductive substrate of an electrophotographic photoreceptor.

[0002]

2. Description of the Related Art Generally, an electrophotographic photosensitive member is one in which a photosensitive layer is formed on a drum-shaped conductive substrate. This drum-shaped conductive substrate is formed by mirror-finishing cylindrical aluminum or impact-molding plate-shaped aluminum. Cutting oil mist, dust in the air, chips, etc. adhere to the surface of the substrate during mirror processing or impact molding, so after removing the substrate surface by washing, condensation polycyclic pigments, azo pigments, etc. A charge generation layer composed of a charge generation material, a resin binder, etc. and a charge transport layer composed of a hydrazone or arylamine charge transport material, a resin binder, an antioxidant, etc. are successively applied, laminated and dried. To form a photosensitive 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 above-mentioned substances constituting the charge-generating layer and the charge-transporting layer by a known method. Formed in. 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. Be done.

In the dip coating method, if the surface of the conductive substrate, which is a pretreatment, is insufficiently cleaned, oil, dust and the like remain on the surface and cause coating defects such as cissing and stains during coating. .. Defects generated on such an electrophotographic photosensitive member appear as black spots, white spots, and halftone image unevenness in a copy image, and adversely affect image quality.
Such an electrophotographic photoreceptor is not suitable for practical use.

The surface of the substrate is usually washed by dipping the substrate in an organic solvent or, if necessary, in an organic solvent heated, or by sonication; dipping the substrate in a solvent. Contact cleaning in which the solvent is physically rubbed with a brush, sponge or the like while showering the solvent on the inside or the substrate; jet cleaning in which the solvent is jetted from the slit to the surface of the substrate under high pressure and vapor cleaning in which the substrate is inserted into the solvent vapor. The cleaning of the surface of the substrate is carried out singly or in combination.

Examples of the solvent used here include chlorine-based solvents such as methylene chloride, ethylene chloride, 1,1,1-trichloroethane, trichloroethylene and perchlorethylene, and fluorine-based solvents such as Freon-112 and Freon-113. Solvents, mixed solvents of the fluorine-based solvent with methanol, methylene chloride, etc., benzene, toluene, methanol, ethanol, isopropyl alcohol, petroleum hydrocarbons, etc., and mixtures thereof. These solvents include those that are flammable and ignitable, those that have a low permissible concentration because they are harmful to the human body, and those that have a low cleaning ability.The most commonly used solvents are:
It is 1,1,1-trichloroethane. However,
Although 1,1,1-trichloroethane has the advantages of high cleaning ability and easy handling, it is considered to be one of the substances that cause global warming and ozone layer depletion. The reduction has been decided in the world,
It is required to provide an alternative cleaning solution for 1,1-trichloroethane or to develop an alternative cleaning method.

As an alternative to cleaning using an organic solvent such as 1,1,1-trichloroethane, so-called water cleaning has been proposed in which immersion cleaning is performed in pure water or water containing a surfactant.

As the conductive substrate of the electrophotographic photoreceptor, a cylindrical substrate or thin film sheet of metal such as aluminum, copper, nickel, stainless steel, brass, or aluminum,
Examples include tin alloy, indium oxide, and the like deposited on a polyester film, paper, or a cylindrical substrate of a metal film, but aluminum is the most common from the viewpoints of low price, ease of processing, strength, and weight. is there. However, aluminum has a property of being highly reactive and soft, and this tendency is remarkable when the purity of aluminum becomes high. From the viewpoint of ease of processing and adhesion to the photosensitive layer, aluminum of high purity is a conductive substrate. It is used as a material for.

When such a conductive substrate made of high-purity aluminum is washed with water under ultrasonic irradiation, the surface tension of water is higher and the cavitation is stronger than that of an organic solvent washing solution, so that washing and rinsing with water for a long time are performed. By the treatment, pinholes are likely to be formed on the surface of the base material, and the surface of the base material is likely to be corroded by reacting with water. Therefore, an electrophotographic photoreceptor having a photosensitive layer formed on a conductive substrate that has been washed with water for a long time has a black spot.
May have white spot image defects.

[0010]

The substrate surface is sufficiently cleaned while suppressing the occurrence of pinholes in water cleaning and surface corrosion due to the reaction with the cleaning liquid, and image defects such as cissing and stains are hardly generated. There is a strong demand for development of a method for cleaning a conductive substrate to obtain an electrophotographic photosensitive member.

[0011]

Means for Solving the Problems As a result of intensive studies by the present inventors, in washing a conductive substrate for an electrophotographic photoreceptor with water,
When rinsing is performed in pure water or ion-exchanged water in which bubbles are generated by air blow, ultrasonic waves are not used, so there is almost no cavitation due to ultrasonic waves and pin holes do not occur, and the substrate surface It was found that an electrophotographic photosensitive member having almost no image defects such as cissing and stains can be obtained by sufficiently washing the above-mentioned, and based on this finding, the present invention has been accomplished.

[0012]

1 is a diagram showing the outline of the cleaning method of the present invention.

(I) "Cleaning step": The base body 1 cut or impact-formed is supported by a robot hand 2 arranged on a rail 3. The first cleaning tank 11 is filled with a cleaning liquid 18 of pure water or ion-exchanged water, preferably pure water or ion-exchanged water in which a surfactant is dissolved, and the cleaning liquid is heated to 40 to 60 ° C. by a heater 16. In addition, an ultrasonic oscillator 17 is provided at the bottom of the cleaning tank 11 so that ultrasonic waves oscillate when the substrate is immersed. A cleaning liquid is constantly fed into the cleaning tank 11 from a pipe (not shown) through a pipe 12. The cleaning liquid in which the oil, dust, and chips removed from the substrate surface by the cleaning is dispersed is supplied from the pipe 19 to the filter 1 by the pump 14.
It circulates after passing through 5, and dust, cutting chips, etc. are captured by the filter 15. The liquid that overflows due to the immersion of the substrate is discharged from the pipe 13. The discharged cleaning liquid is processed by a drainage processing device (not shown).

As the surfactant used in the present invention, nonionic surfactants and / or anionic surfactants that do not corrode the substrate can be used, and specific examples thereof include polyoxyethylene alkylphenyl. Ether, polyoxyethylene / polyoxypropylene / block copolymer type and nonylphenol polyoxyethylene ether nonionic surfactant and alkylbenzene,
Examples include anionic surfactants such as higher alcohols, sulfates such as α-olefins, silicates, carbonates or phosphates.

As a cleaning aid (builder), an inorganic builder such as sodium carbonate, sodium tripolyphosphate, potassium pyrophosphate, sodium silicate or sodium sulfate, or an organic builder such as carboxymethyl cellulose, methyl cellulose or organic amine is added to the cleaning liquid. You may.

The concentration of the surfactant in the cleaning solution of the present invention is 0.
It is 5 to 30%, preferably 4 to 15%.

The cleaning time (immersion time) in the present invention is
It is 0.5 to 10 minutes, preferably 1.5 to 5 minutes.
The substrate may be swung if necessary during the immersion.

(Ii) "Rinsing step": the second cleaning tank 21,
The third cleaning tank 31 and the fourth cleaning tank 41 are filled with pure water or ion-exchanged water as cleaning liquids 25, 35, 45, respectively, and rinsed. The cleaning liquid in each cleaning tank is supplied from the pipes 26, 36, 46 to the pumps 22, 3, respectively.
2, 42 circulate through the filters 23, 33, 43, and the filters trap dust, chips, and the like. The cleaning liquid is supplied from the tank 47 to the cleaning tank 41, the cleaning liquid is supplied to the third cleaning tank 31 by the overflow from the fourth cleaning tank 41, and the second cleaning tank is supplied by the overflow from the third cleaning tank 31. The cleaning liquid is supplied to 21 and the liquid overflowing from the second cleaning tank 21 is discharged from the pipe 27 and treated by the drainage treatment device.

Bubbles are generated in the second to fourth cleaning tanks by air blow, and the generated bubbles remove the deposits on the surface of the substrate.

2 and 3 are specific views of the bubble generating mechanism of the second to fourth cleaning tanks, and the means for generating bubbles in the rinsing liquid is not limited to these methods.

In FIG. 2, the cleaning liquid 25 in the cleaning tank 21 is extracted from the upper portion and introduced into the cleaning tank from the lower portion while being controlled by a flow meter. When the water is introduced into the lower portion of the cleaning tank, water is introduced into the replacement water tank 24 from the lower portion thereof to supply the air in the upper portion to the nozzle portion 44 to generate bubbles 34 in the rinsing liquid.

FIG. 3 shows another mode of the bubble generating mechanism, in which the cleaning liquid extracted from the bottom of the cleaning tank 21 is controlled obliquely from the liquid surface of the cleaning liquid 25 (30 to 60) while controlling the cleaning liquid with a flow meter.
Introduced at an angle of °. At the time of introduction to the liquid surface, water is introduced into the replacement water tank 24 from its lower portion to supply the air in the upper portion to the nozzle portion 44 and generate bubbles 34 in the rinsing liquid.

2 and 3, the pressure of the air (compressed air) supplied to the nozzle portion 44 is 1 to 10 kg / cm ² ·.
G, preferably ^{2~8kg / cm 2 · G, 10kg} / cm 2 ·
If compressed air exceeding G is introduced, pin holes may be generated due to compressed air pressure, and if it is less than 1 kg / cm ² · G, the rinsing effect is not sufficient.

A cleaning tank equipped with stirring blades is used.
If air blowing is performed while stirring, the rinsing effect is further improved.

Immersion times in the second to fourth cleaning tanks are respectively 0.5 to 10 minutes, preferably 1.5 to 5.0 minutes. Note that the base body may be rocked during dipping, if necessary.

(Iii) "Drying step": The substrate after the rinsing treatment is dried by a known method, for example, by blowing clean air of 80 ° C. in a clean booth 50 maintained at a clean degree of 100.

A photosensitive layer is formed on the surface of the conductive substrate that has been washed by a known method. For example, a charge generation layer is formed on the surface of the conductive substrate that has been subjected to the cleaning treatment by a dip coating method, a ring method coating method or a spray coating method, and then the charge transport layer is formed on the charge generating layer by a dip coating method or a spray coating method. Form the layers.

As the conductive substrate of the electrophotographic photosensitive member used in the present invention, a cylindrical substrate or a thin film sheet of a metal such as aluminum, copper, nickel, stainless steel or brass, or a polyester film of aluminum, tin alloy, indium oxide or the like is used. Alternatively, it may be vapor-deposited on paper or a cylindrical substrate of a metal film.

An undercoat layer may be provided for the purpose of improving the adhesion of the photosensitive layer, improving the coating property, covering defects on the substrate, improving the charge injection property from the substrate to the charge generating layer, and the like. Resins such as polyamide, copolymerized nylon, casein, polyvinyl alcohol, cellulose and gelatin are known as materials for the undercoat layer. These are dissolved in various organic solvents and coated on a conductive cylindrical substrate so that the film thickness is about 0.1 to 5 μm.

The charge generation layer contains a charge generation material which generates a charge upon irradiation with light as a main component, and if necessary, a known binder, plasticizer and sensitizer, and has a film thickness of 1.0 μm or less ( It is applied on the conductive cylindrical substrate or the undercoat layer so as to have a dry film thickness).

As the charge generating material, a perylene pigment,
Polycyclic quinone pigments, phthalocyanine pigments, metal phthalocyanine pigments, squarylium dyes, azurenium dyes, thiapyrylium dyes, and carbazole skeletons, styrylstilbene skeletons, triphenylamine skeletons, dibenzothiophene skeletons, oxadiazole skeletons, fluorenone skeletons, bis Examples thereof include azo pigments having a stilbene skeleton, a distyryl oxadiazole skeleton, or a distyryl carbazole skeleton.

The charge-transporting layer contains a charge-transporting material capable of receiving and transporting charges generated by the charge-generating material and a binder as essential components, and if necessary, known leveling agents, plasticizers and sensitizers. 5 to 70 including dry agent
It is coated on the charge generation layer so as to have a thickness of μm.

As the charge transport material, poly-N-vinylcarbazole and its derivative, poly-γ-carbazolylethylglutamate and its derivative, pyrene-formaldehyde condensate and its derivative, polyvinylpyrene, polyvinylphenanthrene, oxazole derivative, Electron donation of oxodiazole derivatives, imidazole derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, hydrazone derivatives, etc. Substances, or fluorenone derivatives, dibenzothiophene derivatives, indenothiophene derivatives, phenanthrenequinone derivatives, indenopyridine derivatives, thioxanthone derivatives, benzo [c] cinnoline derivatives Body, phenazine oxide derivatives, tetracyanoethylene, tetracyanoquinodimethane, Puromaniru, chloranil, electron-accepting substance such as benzoquinone, and the like.

As the binder constituting the charge transport layer, any binder having compatibility with the charge transport material may be used, and examples thereof include polycarbonate, polyvinyl butyral, polyamide, polyester, polyketone, epoxy resin, polyurethane, polyvinyl ketone and polystyrene. , Polyacrylamide, phenol resin, phenoxy resin and the like.

The electrophotographic photosensitive member produced by the method of the present invention has almost no black spots or white spots on the image due to cissing or stains, and has a high yield rate. Furthermore, since no organic solvent is used in the cleaning process, there is no risk of air pollution due to the use of organic solvent, effects on the human body, high flammability, and explosion due to ignition.

[0036]

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

Example 1 A cylindrical substrate that had been cut was washed by the method shown in FIG. In the method of FIG. 1, a 5% pure aqueous solution of Polar Clean 690 (Tanaka Import Group Co., Ltd.) was used as the cleaning liquid for the first cleaning tank, and pure water was used as the cleaning liquid for the second to fourth cleaning tanks. .. The cleaning liquid in the first cleaning tank was heated to 50 ° C, and the temperatures of the cleaning liquids in the second to fourth cleaning tanks were 25 ° C. The immersion time in each of the first to fourth cleaning tanks was 2 minutes. 2nd-4th
The cleaning tank has a structure as shown in FIG.
By blowing in compressed air of kg / cm ² · G, bubbles were generated in the cleaning liquid for cleaning.

The washed substrate was dried by blowing clean air at 80 ° C. in a clean booth maintained at a clean degree of 100.

The obtained cylindrical substrate was coated with the following solution A on the surface of the cylindrical substrate by a known dip coating method to obtain a film thickness of 0.
It is applied by dip coating to have a thickness of 5 μm and dried at a temperature of 75 ° C. for 1 hour. Further, the following liquid B is dip-coated on the surface of the cylindrical substrate coated with liquid A so that the film thickness after drying is 20 μm,
It was dried at a temperature of 75 ° C. for 1 hour.

2 parts by weight of liquid A dibromoanthanthrone, 2 parts by weight of butyral resin [S-REC BM-2, manufactured by Sekisui Chemical Co., Ltd.], and 230 parts by weight of cyclohexanone were mixed with a ball mill to obtain 8 parts.
Liquid obtained by time dispersion treatment.

Liquid B hydrazone type charge transport material [ABPH, Nippon Kayaku Co., Ltd.
1 part by weight, polycarbonate resin [Panlite L-
1250, manufactured by Teijin Chemicals Ltd.] 1 part by weight dissolved in 8 parts by weight of dichloroethane.

The obtained 30 electrophotographic photoconductors were mounted on a rotating jig, and a copying machine [SF-8100, manufactured by Sharp Corporation] was used.
The image was evaluated by making a copy of the product. The results are shown in Table 1.

Comparative Example 1 The cut cylindrical substrate was subjected to ultrasonic / warm bath cleaning treatment for 30 seconds by using 1,1,1-trichloroethane at 60 ° C. as an organic solvent. After cooling in 1,1,1-trichloroethane at 20 ° C. for 30 seconds, steam cleaning was performed for 30 seconds using 1,1,1-trichloroethane, and the mixture was allowed to cool in a clean room for 20 minutes. A photoreceptor layer was formed on the surface of the obtained cylindrical substrate by the same method as in Example 1.

Thirty electrophotographic photosensitive members thus obtained were used in Example 1.
Image evaluation was performed in the same manner as in. The results are shown in Table 1.

Comparative Example 2 A photoreceptor layer was formed on the surface of a cylindrical substrate which was not washed by the same method as in Example 1. Obtained electrophotographic photoreceptor 3
The image evaluation was performed on 0 of them in the same manner as in Example 1. The results are shown in Table 1.

Reference Example 1 Except that instead of air blowing in the second to fourth cleaning tanks, ultrasonic oscillators were provided in the second to fourth cleaning tanks and ultrasonic waves of 30 kHz were oscillated and rinsed for 2 minutes each. Then, the same cleaning treatment as in Example 1 was performed, and a photoreceptor was formed on the surface of the obtained substrate by the same method as in Example 1.

Thirty electrophotographic photoreceptors obtained were used in Example 1.
Image evaluation was performed in the same manner as in. The results are shown in Table 1.

[0048]

[Table 1]

[0049]

EFFECTS OF THE INVENTION The method of the present invention prevents repelling due to poor cleaning, stains, and pinholes due to cavitation due to ultrasonic oscillation during rinsing treatment, and the yield rate is 1,1,1- Almost the same as when using a trichloroethane cleaning solution, the reduction of the yield rate is prevented, and an electrophotographic photoreceptor can be obtained in a practically high yield. Furthermore, since an organic solvent is not used as a cleaning liquid, air pollution due to the use of an organic solvent, effects on the human body, explosion hazard due to high flammability and ignition, especially 1,1,1-trichloroethane, as a cleaning liquid for CFCs Problems such as global warming and ozone depletion due to use can be solved.

[Brief description of drawings]

FIG. 1 is a schematic view of a cleaning method of the present invention.

FIG. 2 is a detailed view of second to fourth cleaning tanks of the present invention.

FIG. 3 is a detailed view of another embodiment of second to fourth cleaning tanks of the present invention.

[Explanation of symbols]

 1 Conductive Substrate 11 First Cleaning Tank 17 Ultrasonic Oscillator for First Cleaning Tank 18 Cleaning Solution for First Cleaning Tank 21 Second Cleaning Tank 24 Replacement Water Tank 31 Third Cleaning Tank 41 Fourth Cleaning Tank 44 Nozzle part 50 clean booth

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masanori Matsumoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Kazuyuki Arai 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Co., Ltd. (72) Inventor Mitsuhiro Shinobu 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture

Claims (1)

[Claims] 1. The surface of a conductive substrate for an electrophotographic photoreceptor is washed with pure water, ion-exchanged water or water containing a surfactant, treated with a rinsing liquid in which bubbles are generated by air blowing, and dried. And a method for cleaning a conductive substrate for an electrophotographic photoreceptor.