JPH05232715A - Washing method for electroconductive base for electrophotographic sensitive member - Google Patents

Abstract

PURPOSE:To provide an electrophotographic sensitive member, i.e., photoreceptor, having excellent image forming ability by equipping a rinsing effect approx. the same as 1,1,1-trichlorethane, preventing formation of hydroxides, hydrates, etc., due to contact with water vapor in the drying process, and suppressing generation of uneven performance of drying, stains, etc. CONSTITUTION:Prior to formation of a sensitive layer, the surface of a base 1 is immersed in water containing surface active agent under application of ultrasonic waves, and after rinsing, the water vapor is condensed on the surface of warm water by a cooling means 53, or otherwise the water vapor on the surface of warm water is absorbed by an appropriate means furnished in a warm water bath, which is filled with a warm water 51 at 50-90 deg.C, followed by pulling up and drying.

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 generating material, a charge generating layer comprising a resin binder and a hydrazone or arylamine charge transporting material,
A charge transport layer composed of a resin binder, an antioxidant and the like is sequentially applied and 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 pretreatment of the surface of the conductive substrate is insufficient, oil, dust, etc. remain on the surface and cause coating defects such as cissing and spots during coating. .. Such defects on the electrophotographic photosensitive member appear as black spots, white spots, and halftone image unevenness on the copy image, and adversely affect the image quality. It is not suitable for.

For cleaning the surface of the substrate, dipping cleaning is usually carried out by dipping the substrate in an organic solvent or, if necessary, in an organic solvent heated and / or under the action of ultrasonic waves; Contact cleaning in which the solvent is physically rubbed with a brush, sponge, etc. while being immersed in the bath or showering the solvent to the substrate; jet cleaning in which the solvent is jetted from the slit to the substrate surface under high pressure and vapor cleaning in which the substrate is inserted into the solvent vapor The surface of the substrate is cleaned by using these alone 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. Examples thereof include solvents, mixed solvents of the fluorine-based solvent and 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 advantages such as high cleaning ability and easy handling, it is presumed that it is one of the substances causing global warming and ozone layer depletion. It has been decided to reduce the amount of chlorofluorocarbons worldwide, and it is required to provide an alternative cleaning solution for 1,1,1-trichloroethane or to develop an alternative cleaning method.

As an alternative to cleaning with 1,1,1-trichloroethane, a cleaning method using water containing a surfactant has been proposed. For example, in this method, which is a method of immersing dust or oil adhering to the surface of the conductive substrate in the surfactant-containing pure water under the action of ultrasonic waves, in this method, the surface of the conductive substrate is cleaned after the immersion cleaning. The adhering surfactant is washed off with pure water. However, although the drying process is performed after the rinsing process with pure water at room temperature, since the evaporation rate of water is slow, unevenness in drying, stains and the like tend to occur on the surface of the conductive substrate. The electrophotographic photosensitive member produced by using the electrophotographic photosensitive member often causes image unevenness such as black spots, white spots, and halftones in a copy image.

In order to quickly dry the surface of the conductive substrate that has been washed, a method of blowing air onto the surface of the substrate can be considered. However, the method of blowing air onto the surface of the substrate requires a large-scale device for uniformly blowing the air in the circumferential direction of the cylindrical substrate, which not only causes a high cost but also prevents the inner surface of the conductive substrate from being dried. This becomes insufficient, and as a result, residual water is mixed in the coating liquid, which causes deterioration of the coating liquid.

35 to 90 after the rinsing treatment in order to accelerate evaporation of water adhering to the surface of the conductive substrate during the rinsing treatment.
A method of accelerating the drying by immersing and pulling the substrate in warm water at ℃ has been proposed.

As the aluminum alloy as the conductive substrate material, an aluminum alloy having a relatively high purity is used in consideration of its workability and image forming ability. Aluminum with high purity has high reactivity, and the water vapor accumulated in the hot water immersion tank may react with the surface of the substrate to form a hydroxide, a hydrate or the like. Hydroxides, hydrates, etc. formed on this surface cause changes in physical properties such as wettability, which causes coating defects when coating photosensitive materials, and causes of image defects such as black spots and white spots in copy images. And also causes a decrease in the yield rate.

[0012]

In water washing without causing pollution, generation of hydroxides, hydrates and the like due to contact with water vapor during drying treatment is prevented, and there is no image defect, and it is a non-defective product. It is desired to establish a method for cleaning a conductive substrate to obtain an electrophotographic photosensitive member having a higher rate.

[0013]

As a result of earnest research by the present inventors, in cleaning the surface of a conductive substrate for an electrophotographic photoreceptor with water, a cooling means is provided on the hot water surface of a hot water dipping tank and the water is immersed in the tank. The condensed water vapor is condensed or the water vapor accumulated in the tank is sucked by a pump so that the water vapor does not come into contact with the surface of the electrically conductive substrate, and the electrically conductive substrate is immersed in warm water at 50 to 90 ° C.
Since water vapor does not come into contact with the surface of the conductive substrate immediately after pulling up with hot water when pulled up and dried, formation of hydroxides, hydrates, etc. on the surface of the conductive substrate due to reaction of aluminum of the conductive substrate material with water vapor It has been found that an electrophotographic photosensitive member can be manufactured with a high yield rate by preventing the occurrence of coating defects and image defects, and based on this finding, the present invention has been accomplished.

[0014]

2 is a diagram showing the outline of the cleaning method of the present invention. The base body 1 that has been cut or impact-molded 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, ion-exchanged water, or ion-exchanged water containing a surfactant or pure water, and the cleaning liquid is heated to 40 to 60 ° C. by a heater 16, and An ultrasonic oscillator 17 is provided at the bottom of the cleaning tank 11.
Is provided so that ultrasonic waves are oscillated 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 surface of the substrate by the cleaning is dispersed is circulated from the pipe 19 through the filter 15 by the pump 14, and the dust, chips, etc. are filtered by the filter 1.
5 is supplemented. 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).

The second cleaning tank 21, the third cleaning tank 31, and the fourth cleaning tank 41 have cleaning solutions 25, 35, and 45, respectively.
As a result, ion exchange water or pure water is filled and a rinsing process is performed. An ultrasonic oscillator 2 is installed at the bottom of each cleaning tank.
4, 34, 44 are provided, and the cleaning liquids in the respective cleaning tanks are pumps 22, 32, 42 from the pipes 26, 36, 46, respectively.
Circulates through the filters 23, 33, 43, and dust, chips, etc. are captured by the filter. The cleaning liquid is supplied to the cleaning tank 41 from the tank 60, 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 the pipe 21, and the liquid overflowing from the second cleaning tank 21 is supplied to the pipe 2
The liquid is discharged from No. 7 and is processed by the drainage processing device. In the method of FIG. 2, at least one cleaning tank may be filled with the cleaning liquid containing the surfactant-containing water.

As the surfactant used in the present invention, a nonionic surfactant and / or an anionic surfactant which does not corrode the substrate can be used. Specific examples thereof include polyoxyethylene alkylphenyl. Nonionic surfactants of ether, polyoxyethylene / polyoxypropylene / block copolymer type and nonylphenol polyoxyethyne ether, and alkylbenzene, higher alcohols, sulfates such as α-olefins, silicates,
Examples include carbonate or phosphate anionic surfactants.

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 first cleaning tank of the present invention is 0.5 to 10 minutes, preferably 1.5.
~ 5 minutes, the immersion time in the second to fourth cleaning tanks is also 0.5 to 10 minutes, preferably 1.5 to 5 minutes. Note that the base body may be rocked during dipping, if necessary.

The substrate 1 that has been rinsed in the cleaning tanks 21, 31, 41 is immersed in a warm water immersion tank 50 filled with warm pure water or ion-exchanged water, pulled up, and dried. A heating device (heater) 52 is attached to the bottom of the warm water immersion tank 50, and pure water or ion-exchanged water is maintained at 50 to 90 ° C, preferably 60 to 80 ° C. Pure water or ion-exchanged water is supplied from the supply device 53 to the immersion tank.

If the temperature of pure water or ion-exchanged water exceeds 90 ° C., the substrate (aluminum) is likely to be corroded by water, and if the temperature is less than 50 ° C., it takes a long time to dry and uneven drying and stains are likely to occur. Become. The immersion time in the warm pure water of the present invention is 0.5 to 5 minutes, preferably 1 to 3 minutes. The substrate may be rocked during the immersion if necessary.

FIG. 1 is a diagram showing a specific example of a warm water immersion tank 50 of the present invention. On the liquid surface of the hot water 51 of the hot water immersion tank 50, a cooling means consisting of a cooling pipe 53 through which a refrigerant is passed is provided around the vertically moving periphery of the substrate, and the rinsed conductive substrate 1 descends in the cooling means. It is immersed in warm pure water or warm ion-exchanged water at 50 to 90 ° C., and the inside of the cooling means is pulled up. A water drop tray 54 is provided at the bottom of the cooling pipe, so that the water vapor accumulated in the warm water immersion tank 50 can cool the cooling pipe 5.
3 is condensed to form water droplets in the water droplet receiving tray 54, so that water vapor does not come into contact with the ascending conductive substrate 1, and as a result, hydroxides and hydrates due to contact with water vapor in the drying process. Etc. do not occur on the surface of the conductive substrate 1. The temperature of the cooling medium is 5 to 25 ° C., and the distance between the cooling means and the surface of the substrate is 5 to 100 mm.

FIG. 3 is a diagram showing another specific example of the warm water immersion tank 50 of the present invention. From the suction port 55 on the inner wall of the warm water immersion tank at a position above the liquid surface of the warm water 51 of the warm water immersion tank 50 to the pump 5
6 draws water vapor and releases it to the outside.

The substrate pulled up from the warm water immersion tank is allowed to cool in a clean booth maintained at a cleanness of 100, for example.

A photosensitive layer is formed on the surface of the washed substrate by a known method. For example, the charge generation layer is formed on the surface of the cleaned cylindrical substrate by the dip coating method, the ring coating method or the spray coating method. Then, a charge transport layer is formed on the charge generation layer by a dip coating method or a spray coating method.

As the electroconductive 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. 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 and improving the charge injection property from the substrate to the charge generating layer. 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 charges 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 coated 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 having the ability to receive and transport the charge generated by the charge-generating material and a binder as essential components, and if necessary, known leveling agents, plasticizers, Contains a sensitizer and the like, and has a dry film thickness of 5 to 70.
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.

[0034]

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

Example 1 By the method shown in FIG. 2, the cut cylindrical substrate was washed. In the method of FIG. 2, 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.

The rinsed substrate was placed in the hot water immersion tank shown in FIG. 1 at a position 20 mm away from the substrate surface.
It was lowered in a cooling pipe at 0 ° C., immersed in pure water kept at 65 ° C. for 2 minutes, pulled up at 10 mm / sec, and allowed to cool in a clean booth kept at a clean degree of 100 for 20 minutes.

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 dibrom anthanthrone, 2 parts by weight of butyral resin [ESREC 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, Sharp Co., Ltd.] 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 wave / warm bath cleaning treatment using 1,1,1-trichloroethane at 60 ° C. as an organic solvent for 30 seconds. After cooling with 1,1,1-trichloroethane at 20 ° C. for 30 seconds, steam cleaning with 1,1,1-trichloroethane was performed for 30 seconds, 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.

Image evaluation was performed on 30 obtained electrophotographic photoconductors in the same manner as in the examples. 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
Image evaluation was carried out on 0 of them in the same manner as in the example. The results are shown in Table 1.

Reference Example Water was washed and dried in the same manner as in Example 1 except that it was immersed in a warm water dipping bath without a cooling pipe, and the obtained conductive substrate surface was treated in the same manner as in Example 1. Then, a photosensitive layer was formed, and image evaluation was performed by the same method as in Example 1. The results are shown in Table 1.

Example 2 A cylindrical substrate that had been machined was washed by the method shown in FIG. In the method of FIG. 2, 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.

The rinsed substrate was lowered into the warm water dipping tank shown in FIG. 3 while sucking the water vapor accumulated on the liquid surface by the pump 56, and then the pure water kept at 65 ° C.
Soak for 10 minutes, pull up at 10 mm / sec, cleanliness 100
It was left to cool in the clean booth kept at 20 minutes.

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.

30 electrophotographic photoconductors thus obtained were mounted on a rotating jig and used as a copying machine [SF-8100, manufactured by Sharp Corporation].
[Production] and made a copy for image evaluation. The results are shown in Table 1.

[0049]

[Table 1]

[0050]

EFFECTS OF THE INVENTION The method of the present invention prevents the occurrence of cissing, stains, drying unevenness, stains, etc. due to poor cleaning, and even in the non-defective rate, the conventional 1,1,1-trichloroethane cleaning solution is used. Almost the same, the reduction of the yield rate is prevented, and the electrophotographic photosensitive member can be obtained in a practically high yield. Furthermore, since no organic solvent is used as a cleaning liquid,
Air pollution due to the use of organic solvents, effects on humans, risk of explosion due to high flammability and ignition, especially 1,1,1
-The problems such as global warming and ozone layer depletion due to the use of trichloroethane and freon as a cleaning solution are solved.

[Brief description of drawings]

FIG. 1 is a schematic view of a hot water immersion tank of the present invention.

FIG. 2 is a schematic view of a cleaning method of the present invention.

FIG. 3 is a schematic view of another embodiment of the hot water immersion tank 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 31 Third Cleaning Tank 41 Fourth Cleaning Tank 50 Hot Water Soaking Tank 52 heating device 53 cooling pipe 55 absorption port 56 pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mayu Sakamoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Hiroshi Matsumoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Incorporation (72) Inventor Mitsuhiro Shinobu 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture

Claims (1)

[Claims] 1. A surface of a conductive substrate for an electrophotographic photoreceptor is immersed and washed in pure water, ion-exchanged water or water containing a surfactant,
After the rinsing treatment, a cooling means is provided on the hot water surface of the hot water immersion tank to condense the water vapor accumulated in the tank or to suck the water vapor accumulated in the tank by a pump so that the water vapor does not come into contact with the surface of the conductive substrate. A method for cleaning a conductive substrate for an electrophotographic photoreceptor, which comprises immersing in a hot water immersion tank at 50 to 90 ° C., pulling it up and drying.