JPH05210246A - Production of electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide the electrophotographic sensitive body which has decreased image defects, such as black spots, white spots and unequalness of halftone images even if a conductive base body for the electrophotographic sensitive body is subjected to a water washing treatment and has decreased characteristics defects at use for long time. CONSTITUTION:The conductive base body 1 for the electrophotographic sensitive body is washed with pure water, ion exchange water or surfactant-contg. water 18 and is subjected to a rinsing treatment; thereafter, the base body is immersed under the impression of ultrasonic wave into an aq. soln. 45 dissolved with a water-soluble resin and is pulled up under the non-impression of the wave to form an under coating layer. A photosensitive layer is formed thereon.

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.

[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.

In the drying after washing with the organic solvent described above, the solvent is instantly evaporated by opening to the air and the drying is completed. However, in the case of washing with water, the evaporation rate of water at room temperature is slow, There is a tendency for dust inside to adhere, drying unevenness, and spots to occur on the surface of the conductive base material.Electrophotographic photoreceptors produced using this conductive base material have black spots, white spots, and half spots on copy images. Image defects such as unevenness of a toned image often occur.

Further, in the conventional cleaning using trichloroethane, chlorofluorocarbon, etc., cavitation generated during ultrasonic oscillation is weak, so that damage to the conductive substrate is small. However, water has a higher surface tension, a higher vapor pressure, and a higher viscosity than the above-mentioned organic solvents, so that cavitation that occurs is strong, and especially when the substrate is made of a relatively soft material, the surface of the substrate may be washed during cleaning. Pinholes may occur.

Aluminum, which is most commonly used as a conductive substrate material from the viewpoints of cost, workability, strength, weight, etc., causes a reaction even if the cleaning liquid is neutral, and is more acidic or alkaline. In some cases, the reaction will accelerate. The reaction also accelerates when the temperature of the cleaning liquid is increased. Oxides, hydroxides, hydrates, etc. of aluminum are produced on the surface of the aluminum substrate by the reaction with such a cleaning liquid, and the substrate surface produced by the compound changes in physical wettability in a minute portion ( Difference in contact angle) occurs.

When a photoconductor layer of a charge generation layer and a charge transport layer is formed on the surface of such a conductive substrate, coating unevenness and coating missing occur, and the manufactured electrophotographic photoreceptor has a lowered dark area potential and potential. Variation, a decrease in the bright part potential, etc.
Image defects such as black spots and white spots may occur in the copy image.

As a method for drying the conductive substrate after the rinsing treatment, a hot air blowing method, a hot pure water immersion method, an isopropyl alcohol (IPA) vapor drying method and the like have been proposed. The dust that is generated becomes stains, the dust in the air adheres, and it reacts with the steam in hot water to form hydroxides, hydrates, etc., causing coating defects, and black images appear on the copy image. This has the drawback of causing image defects such as spots and color spots, lowering the rate of non-defective products, and making separation of water and IPA difficult, which causes a high cost.

[0013]

In the production of an electrophotographic photosensitive member in which a photosensitive layer is formed after cleaning a conductive substrate using pure water, ion-exchanged water or water containing a surfactant as a cleaning liquid, a black copy image is produced. It is strongly desired to develop a method for producing an electrophotographic photosensitive member that does not cause image defects such as spots, white spots, and unevenness of halftone images.

[0014]

As a result of intensive studies by the present inventors, the surface of a conductive substrate is immersed and washed in pure water, ion-exchanged water or water containing a surfactant, and rinsed with pure water or ion-exchanged water. After that, by immediately immersing the water-soluble resin in an aqueous solution in which the water-soluble resin is dissolved without drying treatment under the action of ultrasonic waves, and pulling up under the action of ultrasonic waves to form an undercoat layer,
It has been found that it is possible to solve the problem of image defects due to uneven drying due to water washing, and to suppress the variation in the surface potential and the film thickness of the photoconductor that is generated,
The present invention has been completed based on this finding.

[0015]

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

(I) "Cleaning step": The base body 1 that has been 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 waste liquid processing device (not shown).

(Ii) "Rinse step": The second cleaning tank 21 and the third cleaning tank 31 are filled with pure water or ion-exchanged water as the cleaning liquids 25 and 35, respectively, and a rinsing process is performed. An ultrasonic oscillator 24 is provided at the bottom of each cleaning tank,
34 is provided, and the cleaning liquid in each cleaning tank is connected to the pipe 2 respectively.
6,36 to pumps 22,32, filters 23,33
And is circulated, and dust, cutting chips, etc. are captured by the filter. The cleaning liquid is supplied from the tank 60 to the third cleaning tank 3
1, the cleaning liquid is supplied to the second cleaning tank 21 due to the overflow from the third cleaning tank 31, and the liquid overflowing from the second cleaning tank 21 is discharged from the pipe 27, and is discharged by the waste liquid treatment device. It is processed.

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

(Iii) "Undercoat layer forming step": The fourth dipping tank 41 is filled with an aqueous solution 45 in which a water-soluble resin is dissolved, and an ultrasonic oscillator 46 is installed at the bottom of the aqueous solution 45. The soluble resin aqueous solution is circulated from a pipe 46 by a pump 42 through a filter 43. The water-soluble resin aqueous solution is supplied from the tank 50 with the agitator 70 to the fourth immersion tank 41 while the sensor detects the liquid level of the fourth immersion tank 41.

When the rinsed substrate is immersed under the action of ultrasonic waves, the water adhering to the substrate surface can be separated from the substrate surface and diffused into the aqueous solution. When pulling up, the water-soluble resin is applied as a subbing layer on the surface of the substrate, so that uneven coating does not occur and vibration and waves do not occur in the liquid and the liquid surface so that the coating film thickness is not uneven Therefore, do not irradiate ultrasonic waves.

As the water-soluble binder resin for the undercoat layer,
A resin having high resistance to dissolution in the solvent (organic solvent) that constitutes the photosensitive layer forming coating liquid, such as casein, polyvinyl alcohol, polyvinyl ether, sodium polyacrylate,
Water-soluble resins such as polymethacrylic acid may be mentioned.

The thickness of the undercoat layer is 0.1 to 30 μm, preferably 0.2 to 20 μm. The thickness of the undercoat layer is 0.
If it is less than 1 μm, coating loss of the photosensitive layer may occur, resulting in 30 μm.
If it exceeds m, the residual potential may increase.

The ultrasonic waves emitted from the first to third cleaning tanks and the fourth immersion tank are 20 to 100 kHz.

A photosensitive layer is formed on the conductive substrate having the undercoat layer by a known method. For example, by a dip coating method or a spray coating method, a charge generation layer is formed on the surface of the conductive substrate coated with the undercoat layer, and then a charge transport layer is formed on the charge generation layer by a dip coating method or a spray coating method. Form.

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.

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 applied on 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 transport layer is a charge transport material capable of receiving and transporting charges generated by the charge generation material,
And a binder as an essential component, and if necessary, known leveling agents, plasticizers, sensitizers, etc. are contained, and 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, and an electron-accepting substance benzoquinone.

A known dip coating method can be applied to the method for producing the electrophotographic photosensitive member of the present invention. An example will be described below.

A charge generating material such as an azo pigment may be used together with a binder, a plasticizer and a sensitizer, if necessary, in a suitable solvent such as cyclohexanone, benzene, chloroform, dichloroethane, ethyl ether, acetone, chlorobenzene, and the like. A conductive substrate is dipped in a coating solution dispersed in methyl ethyl ketone or the like by a known method, pulled up and dried to form a charge generating layer on the conductive substrate coated with the undercoat layer.

Next, a charge transporting material such as a hydrazone compound and a binder, together with a leveling agent, a plasticizer, and a sensitizer, if necessary, a suitable solvent such as dichloroethane, benzene, chloroform, cyclohexanone, ethyl ether, A conductive substrate coated with a charge generation layer is dipped in a coating solution dissolved in acetone, dichlorobenzene, methyl ethyl ketone, or the like by a known method, pulled up, and dried to form a charge transport layer.

The electrophotographic photosensitive member produced by the method of the present invention has almost no image defects such as black spots and white spots, shows little deterioration in characteristics even after long-term use, and exhibits excellent environmental stability. Further, since the organic solvent is not used in the washing process, there is no risk of air pollution due to the use of the organic solvent, effects on the human body, high flammability and explosion due to ignition.

[0037]

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 machined by cutting was washed by the method shown in FIG. As the cleaning liquid for the first cleaning tank, CW-55
20% (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 5% pure water
Pure water was used as the cleaning liquid for the third cleaning tank. First
The cleaning liquid in the cleaning tank of No. 2 was heated to 40 ° C., and the temperatures of the cleaning liquids in the second and third cleaning tanks were 25 ° C., respectively. The immersion time in each of the first to third cleaning tanks was 2 minutes.

In the fourth immersion tank, 28% ammonia water 1
5 parts by weight, casein 10 parts by weight and pure water 250 parts by weight
It is filled with an aqueous solution that melts at 0 ° C and is cooled to room temperature. When it is immersed, it is irradiated with ultrasonic waves, and when it is pulled up, it is not irradiated with ultrasonic waves. ,
It was dried at 80 ° C. for an hour.

The ultrasonic waves emitted from the first to third cleaning tanks and the fourth immersion tank were 40 kHz.

Subsequently, the following A was applied by a known dip coating method.
Cylindrical substrate coated with liquid A is applied by dip coating to a cylindrical substrate coated with the undercoating coating liquid so that the dry film thickness is 0.3 μm, and dried at 90 ° C. for 30 minutes. Dip coating to a dry film thickness of 20 μm and apply at 80 ° C for 1
Dried for hours.

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 electrophotographic photosensitive member is mounted on a rotating jig.
Installed on a copier [SF-8100, manufactured by Sharp Corporation]
Then, a copy was taken and the image was evaluated. The results are shown in Table 1.
You Reference example 1 Immersion treatment in the fourth immersion tank of Example 1 to form an undercoat layer
Instead of rinsing, after rinsing,
Same as Example 1 except that it was dried with clean air for 30 minutes
An electrophotographic photosensitive member was manufactured.

Reference Example 2 A casein undercoat layer was formed on the surface of a conductive substrate dried in clean air at 80 ° C. for 30 minutes in Reference Example 1 so as to have a dry film thickness of 1 μm, and the same as in Example 1 above. An electrophotographic photoreceptor was manufactured by the method.

Image evaluation of the electrophotographic photosensitive members obtained in Reference Examples 1 and 2 was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0047]

[Table 1]

The dark potential, the bright potential and the residual potential were measured as follows.

Copier (SF-8100, Sharp Corporation)
Take out the development unit (made by
44, Trek Corp. probe was attached to the developing portion. The developing unit was set in a copying machine, copying was performed without turning on the optical system lamp, and the surface potential after charging was measured with a probe to obtain the dark part potential.

A blank sheet was placed on the platen of the copying machine, the optical system lamp was turned on, copying was performed, and the surface potential after charging and exposure was measured with a probe, which was defined as the bright portion potential.

[0051]

According to the method of the present invention, the undercoat layer is immediately formed without rinsing with pure water or ion-exchanged water in water washing and then with drying. It is possible to obtain an electrophotographic photosensitive member excellent in environmental stability with little variation in image quality, little image defects such as black spots, white spots, and unevenness in halftone images, and little deterioration in characteristics even after long-term use. it can. 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. Moreover, since the drying process can be omitted, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a method for cleaning a conductive substrate for an electrophotographic photoreceptor and a method for producing an undercoat layer according to the present invention.

[Explanation of symbols]

 1 Conductive Substrate 11 First Cleaning Tank 17 First Cleaning Tank Ultrasonic Oscillator 18 First Cleaning Tank Cleaning Solution 21 Second Cleaning Tank 31 Third Cleaning Tank 41 Fourth Immersion Tank 45 Water-Soluble Resin Aqueous Solution

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Matsumoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Ryuhiro Morita 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Kazuyuki Arai 22-22 Nagaike-cho, Abeno-ku, Osaka City, 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,
Rinse with pure water or ion-exchanged water, immerse in an aqueous solution in which water-soluble resin is dissolved under ultrasonic action, pull up under ultrasonic non-action to form an undercoat layer, and form a photoreceptor layer on it A method of manufacturing an electrophotographic photosensitive member, comprising: