JPH1138652A - Production of coating liquid for producing electrophotographic photoreceptor and electrophotographic photoreceptor using that coating liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method of a coating liquid for the production of an electrophotographic photoreceptor having a stable dispersion state of a pigment, which causes little coating failures during coating and little intrusion of impurities, and to provide an electrophotographic photoreceptor showing excellent characteristics when it is used in electrophotographic processes to use the coating liquid. SOLUTION: In the production of a coating liquid for the production of an electrophotographic photoreceptor to disperse pigment particles with a binder in a solvent, the dispersion process is carried out by a method of circulating a treating liquid. When pigment particles consist of an org. charge generating material, a primary dispersion process in the liquid circulating method is carried out without adding a binder, and in a dilution process or the succeeding processes, the binder is added and rest of dispersion processes are carried out. When the pigment particles consist of an org. charge generating material, the driving and contact part of a liquid supply pump to supply the treating liquid is made of zirconia or silicon carbide. Then the coating liquid thus prepared by this producing method is used to obtain an electrophotographic photoreceptor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly, to a method for producing a coating liquid in which a pigment for forming a layer constituting an electrophotographic photoreceptor is dispersed, and a method for preparing the coating liquid. The present invention relates to an electrophotographic photosensitive member having a layer formed by using the same.

[0002]

2. Description of the Related Art In recent years, electrophotographic photoreceptors having a photosensitive layer containing an organic photoconductive compound as a main component are relatively easy to manufacture, inexpensive, easy to handle, and generally used. Attention has been drawn in many respects, such as superior thermal stability compared to inorganic photoreceptors such as selenium. As such an organic photoconductive compound, poly-N-vinyl carbazole is well known.
An electrophotographic photosensitive member having a photosensitive layer mainly composed of a charge transfer complex formed with a Lewis acid such as -trinitro-9-fluorenone is described in JP-B-50-10469. However, this photoreceptor has sensitivity, film forming property,
And it is not always satisfactory in durability.

On the other hand, low molecular weight organic photoconductors represented by hydrazones and pyrazolines have been proposed. By combining these with an appropriate binder, the film-forming properties have been greatly improved, but the sensitivity and durability have not been sufficiently improved. For these reasons, a stacked photoreceptor has been proposed in recent years in which a carrier generating function and a carrier transporting function are shared by different substances. By adopting this structure, charging characteristics and sensitivity are greatly improved, and especially azo pigments and phthalocyanine pigments with high carrier generation ability are used for the charge generation layer, and charge transfer with high carrier transport ability such as hydrazone compound. By combining the substances, those having a sensitivity close to that of an inorganic photoreceptor such as selenium have appeared. As a result, in fields such as copiers and optical printers,
Electrophotographic photoreceptors containing these types of organic photoconductive compounds as main components have become mainstream.

In an electrophotographic photosensitive member, processes such as charging, exposure, and static elimination are repeated in a copying machine, a printer, and the like, and fluctuations in an initial potential after charging and a residual potential after static elimination affect an output image. It must be suppressed as much as possible. However, in general, these photoconductors have reduced chargeability and increased residual potential due to fatigue due to repeated charging and exposure.

In order to compensate for the above-mentioned disadvantages, a method has been proposed in which an undercoat layer is provided between a conductive support and a photosensitive layer.
The undercoat layer has a mainstream structure in which particles having an appropriate electric conductivity are contained in a binder resin in order to control electric resistance. For example, JP-A-58-58556 discloses an undercoat layer in which an oxide of aluminum or tin is dispersed in a resin.
No. 7363 discloses an undercoat layer in which conductive particles are dispersed in a resin, and JP-A-59-84257 and JP-A-60-32054 disclose TiO ₂ and SnO ₂ powder in a resin. An undercoat layer dispersed therein is disclosed.

When an organic charge generating substance pigment such as an azo pigment or a phthalocyanine pigment is used for a photosensitive layer, or when a metal oxide pigment is used for an undercoat layer, it is applied to a widely used coating method due to low film formation cost. In order to obtain good coating films, they must be stably dispersed in a solvent.
However, in general, it is difficult to obtain a stable dispersion state, a coating failure is likely to occur at the time of coating, and sedimentation and aggregation of dispersed particles are likely to occur during storage of the dispersion.

[0007] In addition, as a conventional apparatus for producing a pigment dispersion, when the liquid contact portion of the liquid feed pump is made of a material that is easily worn, such as a metal, as in the case of a conventional apparatus, the worn material is regarded as an impurity. The mixing state makes the dispersion state of the dispersion liquid unstable, and the electrophotographic photoreceptor using the same tends to have deteriorated characteristics when used in an electrophotographic process, and improvement has been desired.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a coating solution for producing an electrophotographic photoreceptor, which has a stable pigment dispersion state, has little coating failure during coating, and has less contamination with impurities. An object of the present invention is to provide an electrophotographic photosensitive member that exhibits excellent characteristics when used in an electrophotographic process using a coating solution for production.

[0009]

Means for Solving the Problems The present inventors have conducted various studies to achieve the above object, and as a result, have formed an electrophotographic photosensitive member having a layer containing pigment particles on a conductive support. A method for producing a coating liquid for producing an electrophotographic photoreceptor, comprising dispersing the pigment particles together with a binder in a solvent, wherein the production apparatus comprises at least a tank for storing a pigment-containing solvent (processing liquid), a dispersing machine, The manufacturing process comprises a dispersion step (primary dispersion step) at a concentration higher than the final coating liquid concentration, and a dilution step, which comprises a liquid sending pump and a filter for transferring the processing liquid from the tank to the disperser. After passing through several dispersion steps and dilution steps as needed,
The dispersing step (final dispersing step) at the coating liquid concentration and the dispersing treatment liquid filtering and removing step are combined, and in each of the dispersing steps, the treating liquid is sent from the tank to the dispersing machine using a liquid sending pump. It has been found that a coating solution for producing an electrophotographic photosensitive member having a stable pigment dispersion state and having few coating failures can be obtained by using a processing solution circulation system for returning the processing solution having undergone the dispersion treatment to the same tank.

When the pigment particles used in the coating liquid for producing an electrophotographic photoreceptor are organic charge generating substance pigments, the primary dispersion step is performed without adding a binder in the above-mentioned coating liquid production method using a treatment liquid circulation system. It has also been found that by adding a binder after the dilution step and performing the subsequent dispersion step, it is possible to obtain a coating liquid for producing an electrophotographic photoreceptor in which the dispersion state of the pigment is stable and coating failure during coating is small.

Further, when the pigment particles used in the coating liquid for producing an electrophotographic photosensitive member are organic charge generating substance pigments, the pigment particles are dispersed in a solvent together with a binder to produce a coating liquid for producing an electrophotographic photosensitive member. In the method, the manufacturing apparatus includes at least a tank for storing a pigment-containing solvent (processing liquid), a disperser, a liquid pump for transferring the processing liquid from the tank to the disperser, and a filter; It was also found that by using zirconia or silicon carbide as the material of the driving liquid contact portion, a coating liquid for producing an electrophotographic photoreceptor can be obtained in which the amount of impurities is small, the pigment dispersion state is stable, and coating failure during coating is small.

In addition, it has been found that by using the coating solution for producing an electrophotographic photosensitive member produced by each of the above methods, an electrophotographic photosensitive member exhibiting excellent characteristics when used in an electrophotographic process can be obtained. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The components of the present invention will be described below in detail. The production apparatus used for producing the coating liquid for producing an electrophotographic photosensitive member according to the present invention includes a tank for storing at least a processing liquid, a disperser, a liquid feed pump for transferring the processing liquid from the tank to the disperser, and a dispersed processing liquid. It is constituted by a filter. A plurality of tanks are used as needed. As a dispersing machine, a dispersing machine such as a vertical sand mill or a horizontal sand mill, which performs dispersion by stirring an enclosed dispersion medium and has an inlet and an outlet for a processing liquid and can continuously perform a dispersion treatment, is used. A plurality of dispersers are connected and used as needed to increase the dispersing efficiency.

The manufacturing process using the above-described manufacturing apparatus includes at least a dispersion step (primary dispersion step) at a concentration higher than the final concentration of the coating solution, a dilution step, and, if necessary, several dispersion steps and a dilution step. Thereafter, the dispersing step (final dispersing step) at the concentration of the coating liquid and the filtering and removing step of the dispersed treatment liquid are combined.

In each of the dispersion steps in the present invention, first, a pigment, a solvent, and a binder, if necessary, are charged into a tank as a processing liquid, and the processing liquid is sent from the tank to a dispersing machine using a liquid sending pump, and dispersed. By using a processing liquid circulation system in which the processing liquid that has undergone the dispersion treatment in the machine is returned to the same tank and the dispersion treatment is repeated, a coating liquid for producing an electrophotographic photosensitive member having excellent characteristics can be obtained.

When the processing liquid circulation system is not used in the dispersion step, for example, the processing liquid in the tank is sent to the disperser using a liquid feed pump, and the processing liquid that has been subjected to the dispersion treatment in the disperser is completely transferred to another tank. When using the receiving method of dispersion process,
The obtained coating liquid for producing an electrophotographic photosensitive member has an unstable pigment dispersion state and tends to cause many coating failures during coating. Further, the characteristics of an electrophotographic photosensitive member having a layer formed by coating the dispersion tend to deteriorate when used in an electrophotographic process.

When an organic charge-generating substance pigment is used as the pigment particles, in the step of producing the coating liquid for producing an electrophotographic photosensitive member of the present invention using a treatment liquid circulation system as the dispersion step, the primary dispersion step is carried out without adding a binder. Then, a binder is added after the dilution step, and the subsequent dispersion step is performed, whereby a coating liquid for producing an electrophotographic photosensitive member having excellent characteristics can be obtained.

When the primary dispersion step is performed by adding a binder in the step of producing a coating liquid for producing an electrophotographic photosensitive member using an organic charge generation substance pigment as the pigment particles and using a treatment liquid circulation system as the dispersion step, the resultant is obtained. In addition, the coating liquid for producing an electrophotographic photosensitive member has an unstable pigment dispersion state and tends to cause many coating failures during coating. Further, the characteristics of an electrophotographic photosensitive member having a layer formed by coating the dispersion tend to deteriorate when used in an electrophotographic process.

Various pumps can be used as the pump for transferring the processing liquid to the dispersing machine used in the dispersing apparatus of the present invention, but from the viewpoints of low pulsation, quantitative property, suitability for use of a high viscosity liquid, solvent resistance and the like. It is preferable to use a pump having a structure in which the rotating drive part in contact with the liquid directly transfers the processing liquid, such as an internal gear (inversion) gear pump or a lobe rotor pump.

When an organic charge generating substance pigment is used as the pigment particles, zirconia or silicon carbide is used as a material of the liquid contacting portion of the pump in the step of producing a coating liquid for producing an electrophotographic photosensitive member of the present invention. A coating liquid for producing an electrophotographic photoreceptor exhibiting excellent characteristics can be obtained.

When a material other than zirconia or silicon carbide is used as the material of the driving liquid contact portion of the pump, for example, in the case of a pump using a metal such as iron or copper alloy which has been conventionally used, the driving liquid contact of the pump with the processing liquid is used. Part of the abrasion material is mixed as impurities, and the resulting coating liquid for producing an electrophotographic photosensitive member has an unstable pigment dispersion state, and tends to have many coating failures during coating. Further, the characteristics of an electrophotographic photosensitive member having a layer formed by coating the dispersion tend to deteriorate when used in an electrophotographic process.

Also, the liquid supply hose used in the manufacturing apparatus, the sealing member such as an O-ring and packing used in the liquid contact part, and the filter for coating liquid filtration are made of polyethylene so as to prevent dissolved substances from entering the processing liquid as impurities. It is preferable to use a material having excellent solvent resistance, such as Teflon, Teflon, perfluoro rubber, and polypropylene.

As the conductive support on which the photoreceptor using the coating solution in the present invention is formed, any of the electrophotographic photoreceptors that are well-known can be used. In particular,
For example, gold, silver, platinum, titanium, aluminum, copper,
Drums, sheets and belts of zinc, iron, metal oxides and the like subjected to conductive treatment, and laminates and vapor-deposits of these thin films.

Further, metal powder, metal oxide, carbon black, carbon fiber, copper iodide, charge transfer complex, inorganic salt,
Drums, sheets, belts, etc. made of plastics, ceramics, papers, etc., which have been coated with a conductive material such as an ion-conductive polymer electrolyte together with a suitable binder and embedded in a polymer matrix and have been subjected to a conductive treatment. Drums, sheets, belts, and the like of plastics, ceramics, paper, and the like that contain conductive materials and are made conductive.

When the coating solution in the present invention is a coating solution for producing an undercoat layer, the coating solution for producing an undercoat layer comprises a pigment, a binder, and a solvent, and is coated on the conductive support to form an undercoat layer. It is formed. Examples of the pigment used include inorganic pigment particles such as various metal oxides, polymer particles, and the like. In the present invention, it is preferable to use titanium oxide particles.

The titanium oxide particles used in the present invention have a higher refractive index than other white pigments, are physically and chemically stable, have excellent hiding power, and are excellent in whiteness. It is used in other various fields, and as the crystal type, rutile type, anatase type, brookite type,
There is an amorphous type, and any of them can be used, and any of a needle crystal and a granular crystal can be used. Further, those whose surface is treated with an oxide such as aluminum, silicon or zirconium, or stearic acid or the like can be used.

In the present invention, as the binder used together with the titanium oxide particles, polymers or copolymers of vinyl compounds such as styrene, vinyl acetate, acrylates, methacrylates, silicone resins,
Various polymers such as phenoxy resin, polysulfone resin, polyvinyl butyral resin, polyvinyl formal resin, polyester resin, cellulose ester resin, cellulose ether resin, urethane resin, phenol resin, epoxy resin, polycarbonate resin, polyarylate resin, polyamide resin, and polyimide resin Can be used.

In the present invention, as a solvent for dispersing titanium oxide together with a binder to form a coating liquid for producing an undercoat layer, any solvent can be used as long as it dissolves the binder.

The ratio of titanium oxide to binder in the coating solution of the present invention is in the range of 1 to 1000 parts by weight, preferably 1 to 400 parts by weight, based on 100 parts by weight of titanium oxide. The thickness of the undercoat layer after coating is suitably 0.05 to 50 μm.

When the coating solution in the present invention is a coating solution for producing a photosensitive layer, the photosensitive layer of the photoreceptor using the coating solution is obtained by dispersing an organic charge generating substance pigment as a charge generating substance and embedding it in a binder. Pigment-dispersed single-layer type, or single-layer type in which an organic charge-generating substance pigment and a charge-transfer substance are dispersed and mixed and confined in a binder, laminated with a charge-generating layer containing an organic charge-generating substance pigment and a charge-transfer layer containing a charge-transfer substance The present invention can be applied to any system.

The organic charge generating substance pigments used include monoazo pigments, polyazo pigments, metal complex salt azo pigments,
Azo pigments such as pyrazolone azo pigments, stilbene azo pigments and thiazole azo pigments, perylene pigments such as perylene anhydride and perylene imide, anthraquinone derivatives, anthuanthrone derivatives,
Anthraquinone-based or polycyclic quinone-based pigments represented by dibenzpyrene quinone derivatives, pyranthrone derivatives, biolanthrone derivatives and isoviolanthrone derivatives,
Examples include phthalocyanine pigments represented by metal phthalocyanine, metal naphthalocyanine, metal-free phthalocyanine, metal-free naphthalocyanine, and the like, and pigments such as porphyrin derivatives.

Of these, those using bisazo pigments, trisazo pigments, and phthalocyanine pigments, which have particularly high carrier generation efficiency, are preferred because they provide high sensitivity and provide excellent photoreceptors. For example, in the case of a bisazo pigment, JP-A-62-286058, JP-A-63-32557, JP-A-63-243948, JP-A-64-21453, JP-A-64-21455, and JP-A-Hei. -94350, 1-20026
Compounds described in JP-A Nos. 7-202 and 1-202775 can be used. In the case of a phthalocyanine pigment, metal-free phthalocyanine, oxytitanium phthalocyanine, and the like can be used.

In the laminated type photoreceptor, the charge generation layer is constituted by at least a mixture of the organic charge generation substance pigment and the binder resin. As the binder resin, styrene, vinyl chloride, vinyl acetate, acrylic acid ester, methacrylic acid ester or the like of a vinyl compound polymer or copolymer,
Examples include silicone resins, phenoxy resins, butyral resins, formal resins, phenol resins, polycarbonates, polyarylates, polyesters, polyamides, polyimides, and the like, thermosetting resins such as epoxy resins and urethane resins, and photocurable resins. The binder is used in an amount of 1 to 1000 parts by weight, preferably 1 to 400 parts by weight, based on 100 parts by weight of the organic charge generation material pigment. The thickness of the charge generation layer is preferably from 0.1 to 20 μm.

The charge transfer material used includes a hole transfer material and an electron transfer material. Examples of the former include, for example, oxadiazoles disclosed in JP-B-34-5466, triphenylmethanes disclosed in JP-B-45-555, and JP-A-52-4188. Pyrazolines, hydrazones disclosed in JP-B-55-42380, JP-A-56-123544.
Oxadiazoles disclosed in Japanese Patent Publication No. Sho 58
And triarylamines described in JP-A-32372 and stilbenes described in JP-A-58-198043. On the other hand, examples of the electron transporting substance include chloranil, tetracyanoethylene, diphenoquinone, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 1,3,7-trinitrodibenzo. And thiophene. These charge transfer materials can be used alone or in combination of two or more.

Of these charge transfer materials, hydrazone compounds, stilbene compounds, and the like are preferable because they have high charge (hole) mobility and provide excellent photoreceptors. For example, in the case of a hydrazone compound, the aforementioned Japanese Patent Publication No. Sho 55
And Japanese Patent Laid-Open No. 1-100
555, 2-10367, 2-511
No. 63, No. 2-96767, No. 2-1832
No. 60, No. 2-184856, No. 2-184
The hydrazone compounds described in JP-A Nos. 858 and 2-184859 can be used.

In the laminated photoreceptor, a charge transfer layer is constituted by at least a mixture of these charge transfer materials and a binder resin. As the binder resin, use of an acrylic resin represented by polystyrene, polymethyl methacrylate, polycarbonate having a skeleton represented by bisphenol A or Z, polyarylate, polyester, polyphenylene ether, polyether sulfone, polyamide, polyimide, etc. Can be. The binder is used in an amount of 10 to 400 parts by weight based on 100 parts by weight of the charge transfer material. The thickness of the charge transfer layer is preferably from 5 to 100 μm.

In the electrophotographic photoreceptor of the present invention, various antioxidants may be added in order to prevent deterioration of the organic material of the constituent material due to oxidation. Further, a well-known plasticizer may be used in order to improve film forming property, flexibility, and mechanical strength. Further, a surface layer may be provided on the surface of the photosensitive layer in order to improve the durability of the photosensitive member.

Solvents used in the coating solution of the present invention include halogenated hydrocarbons such as chloroform, dichloromethane and dichloroethane, aromatic hydrocarbons such as benzene, toluene and xylene; ethers such as dioxane, tetrahydrofuran and dimethoxyethane; methyl ethyl ketone;
Solvents such as ketones such as methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolves such as methyl cellosolve, dimethyl cellosolve, and methyl cellosolve acetate may be used alone or in combination of two or more. Further, if necessary, a solvent such as alcohols, acetonitrile, N, N-dimethylformamide and the like can be further added and used. When coating the drum, a dip coating method or the like is used.

[0039]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 As a dispersing machine, a horizontal sand mill (Dynomill KDL-PILOT type manufactured by WAB, Switzerland) charged with zirconia beads having a diameter of 1 mm as a dispersion medium was used, and the following primary dispersion process was first performed. Was.

A mixed solvent of 490 parts by weight of 1,2-dichloroethane and 270 parts by weight of methanol was charged into a tank, and an alcohol-soluble nylon (Amilan CM8 manufactured by Toray) was added thereto.
000) After dissolving 1.5 parts by weight, a fine particle titanium oxide (STR-60N manufactured by Sakai Chemical Industry) is used as a titanium oxide pigment.
250 parts by weight were mixed. While stirring the inside of the tank, this liquid was gradually introduced from the processing liquid inlet of the operating mill at a flow rate of 100 parts by weight using a liquid sending pump, and dispersed from the processing liquid outlet of the mill. The treated liquid that had undergone the operation was returned to the tank. The dispersion operation of the treatment liquid circulation system described above was performed for 100 minutes to obtain a primary dispersion.

Next, as a dilution step, alcohol-soluble nylon (Amilan CM) was added to the tank containing the primary dispersion.
8000) 12 parts by weight of 1,2-dichloroethane 900
A solution dissolved in a mixed solvent of parts by weight and 480 parts by weight of methanol was added with stirring.

Next, as the final dispersion step, the flow rate of the liquid feed pump was set to 240 parts by weight per minute, and the same dispersion operation as that of the primary dispersion step was performed on the diluent for 30 minutes to obtain the final dispersion liquid. Was. Next, as a filtration take-out step, the final dispersion was taken out while being filtered using a filter having an effective pore size of 10 μm (Tocel TCPD-10 manufactured by Advantech Toyo) to obtain a coating liquid for forming an undercoat layer.

Next, the coating liquid for forming an undercoat layer is applied to an aluminum drum tube by a dip coating method.
After drying for 0 minutes, an undercoat layer having a dry film thickness of about 0.5 μm was formed. Table 1 shows the appearance of the undercoat layer visually and the presence or absence of sedimentation of the dispersed particles after the coating liquid for forming the undercoat layer was allowed to stand for 10 days.

Comparative Example 1 The following primary dispersion process was performed using a dyno mill having the same configuration as that of Example 1 as a disperser. A mixed solvent of 490 parts by weight of 1,2-dichloroethane and 270 parts by weight of methanol was charged into a tank, and 1.5 parts by weight of an alcohol-soluble nylon (Amilan CM8000) was dissolved therein. -60N) 25
0 parts by weight were mixed. At a flow rate of 100 parts by weight per minute using a liquid sending pump, the whole amount is gradually introduced from the processing liquid inlet of the operating mill and the dispersion operation is performed from the processing liquid outlet of the mill in an empty tank. The entire amount of the processing solution was received. The above operation of passing through the mill was repeated 10 times to obtain a primary dispersion.

Next, as a dilution step, alcohol-soluble nylon (Amilan CM8000) 12 was added to the primary dispersion.
A solution of 900 parts by weight of 1,2-dichloroethane and 480 parts by weight of methanol in a mixed solvent was added with stirring. Next, as a final dispersion step, the flow rate of the liquid sending pump was set to 240 parts by weight per minute, and the same liquid-passing operation as in the primary dispersion step was repeated three times. The obtained final dispersion was taken out in the same filtration taking-out step as in Example 1 to obtain a coating liquid for forming an undercoat layer.

Next, this coating solution was applied to an aluminum drum tube in the same manner as in Example 1, and the same test as in Example 1 was performed.
Table 1 shows the results.

[0048]

[Table 1]

Example 2 As a dispersing machine, a horizontal sand mill (Dynomill KDL manufactured by WAB) into which glass beads having a diameter of 1 mm were charged as a dispersion medium was used, and the following primary dispersion step was first performed.

90 parts by weight of methyl ethyl ketone was put into a tank, and 5 parts by weight of a vinyl chloride copolymer resin (MR-110 manufactured by Zeon Corporation) was dissolved therein. Then, τ-type metal-free phthalocyanine (TPA-891 manufactured by Toyo Ink) was dissolved. 5 parts by weight were mixed. While stirring the inside of the tank, this liquid was gradually supplied from the processing liquid inlet of the operating mill at a flow rate of sending 20 parts by weight using the liquid supply pump, and dispersed from the processing liquid outlet of the mill. The treated liquid that had undergone the operation was returned to the tank. The dispersion operation of the treatment liquid circulation system described above was performed for 30 minutes to obtain a primary dispersion.

Next, as a dilution step, 200 parts by weight of methyl ethyl ketone was added to the tank containing the primary dispersion while stirring. Next, as a final dispersion step, the flow rate of the liquid sending pump was set to 60 parts by weight per minute, and the same dispersion operation as the primary dispersion step was performed on the diluent for 10 minutes to obtain a final dispersion liquid. Next, as a filtration and removal step, the final dispersion was filtered out using a filter having an effective pore size of 1 μm (Tocel TCPD-1 manufactured by Advantech Toyo) to obtain a coating liquid for forming a charge generation layer.

Next, this coating solution for forming a charge generation layer was applied to an aluminum drum tube by a dip coating method, and dried at 80 ° C. for 5 minutes to form a charge generation layer having a dry film thickness of about 0.2 μm. Formed. Table 2 shows the appearance of the charge generation layer visually and the presence or absence of sedimentation of the dispersed particles after the coating liquid for forming the charge generation layer was allowed to stand for 10 days.

[0053]

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Next, 10 parts by weight of a styryl compound represented by the following chemical formula 1 and a polycarbonate resin (K-130 manufactured by Teijin Chemicals Ltd.)
0) 8 parts by weight, polyester resin (Vylon 2 manufactured by Toyobo)
90) Dissolve 2 parts by weight in 200 parts by weight of dichloromethane, apply this solution on the charge generation layer by dip coating, and dry at 80 ° C. for 60 minutes to obtain a charge transfer layer having a dry film thickness of 30 μm. Was formed.

The laminated electrophotographic photoreceptor thus prepared is supplied to a drum photoreceptor evaluation device (Cynthia 9 manufactured by Gentec).
After charging with -7.5 kV using the above method 0), the photosensitive member was irradiated with monochromatic light having a wavelength of 750 nm and an intensity of ² μW / cm 2 to measure the half-reduction exposure amount E1 / 2 of the photosensitive member. In addition, 5000 of charge and static elimination using tungsten array with the same device
Before and after the repetition, the potential and the residual potential of the photoconductor after charging were measured. Table 3 shows the results.

Example 3 Methyl isobutyl ketone was used instead of methyl ethyl ketone as the dispersing solvent, and a vinyl chloride copolymer resin (S-LEC M, manufactured by Sekisui Chemical) was used as the binder instead of the vinyl chloride copolymer resin (MR-110). A coating solution for forming a charge generation layer was prepared in the same manner as in Example 2, except that titanyl phthalocyanine (T-22S manufactured by Sanyo Dyestuff) was used instead of the τ-type metal-free phthalocyanine as the charge generation material. This coating solution was applied to an aluminum drum tube in the same manner as in Example 2, and the same test as in Example 2 was performed. Table 2 shows the results. An electrophotographic photoreceptor was prepared in the same manner as in Example 2 except that this coating solution for forming a charge generation layer was used instead of the coating solution for forming a charge generation layer in Example 2, and the same test as in Example 2 was performed. Was. Table 3 shows the results.

Comparative Example 2 The following primary dispersion step was performed using a dyno mill having the same configuration as that of Example 3 as a disperser. 90 parts by weight of methyl ethyl ketone was charged into a tank, and 5 parts by weight of a vinyl chloride copolymer resin (MR-110, manufactured by Zeon Corporation) was dissolved therein.
τ-type metal-free phthalocyanine (TPA-89 manufactured by Toyo Ink)
1) 5 parts by weight were mixed. This solution was pumped using a pump.
At a flow rate of 20 parts by weight per minute, the entire amount was gradually charged from the processing liquid inlet of the operating mill, and the entire amount of the processing liquid subjected to the dispersion operation was received from the processing liquid outlet of the mill in an empty tank. The above operation of passing through the mill was repeated six times to obtain a primary dispersion.

Next, as a dilution step, 200 parts by weight of methyl ethyl ketone was added to this primary dispersion while stirring.
Next, as a final dispersion step, the flow rate of the liquid sending pump was set to 60 parts by weight per minute, and the same liquid-passing operation as in the primary dispersion step was repeated twice. The obtained final dispersion was taken out in the same filtration taking-out step as in Example 2 to obtain a coating liquid for forming a charge generation layer.

This coating solution was applied to an aluminum drum tube in the same manner as in Example 2, and the same test as in Example 2 was performed. Table 2 shows the results. An electrophotographic photoreceptor was prepared in the same manner as in Example 2 except that this coating solution for forming a charge generation layer was used instead of the coating solution for forming a charge generation layer in Example 2, and the same test as in Example 2 was performed. Was. Table 3 shows the results.

Comparative Example 3 Methyl isobutyl ketone was used instead of methyl ethyl ketone as a dispersing solvent, and a vinyl chloride copolymer resin (S-LEC M, manufactured by Sekisui Chemical) was used as a binder instead of a vinyl chloride copolymer resin (MR-110). A coating solution for forming a charge generating layer was prepared in the same manner as in Comparative Example 2, except that titanyl phthalocyanine (T-22S manufactured by Sanyo Dye) was used instead of the τ-type metal-free phthalocyanine as the charge generating material. This coating solution was applied to an aluminum drum tube in the same manner as in Example 2, and the same test as in Example 2 was performed. Table 2 shows the results. An electrophotographic photoreceptor was prepared in the same manner as in Example 2 except that this coating solution for forming a charge generation layer was used instead of the coating solution for forming a charge generation layer in Example 2, and the same test as in Example 2 was performed. Was. Table 3 shows the results.

[0061]

[Table 2]

[0062]

[Table 3]

Examples 1, 2, and 3 correspond to claims 1 and 4 of the present invention and show characteristics superior to Comparative Examples 1, 2, and 3.

Example 4 As a dispersing machine, a horizontal sand mill (Dynomill KDL manufactured by WAB) into which glass beads having a diameter of 1 mm were charged as a dispersion medium was used, and the following primary dispersion step was first performed.

[0065]

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Into a tank, 95 parts by weight of methyl isobutyl ketone were charged, and 5 parts by weight of a bisazo pigment represented by Chemical formula 2 was mixed. While stirring the inside of the tank, this liquid was gradually supplied from the processing liquid inlet of the operating mill at a flow rate of sending 20 parts by weight using the liquid supply pump, and dispersed from the processing liquid outlet of the mill. The treated liquid that had undergone the operation was returned to the tank. The dispersion operation of the treatment liquid circulation system described above was performed for 30 minutes to obtain a primary dispersion.

[0067]

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Next, as a dilution step, 4 parts by weight of the compound represented by Chemical Formula 3 and a butyral resin (Eslec B manufactured by Sekisui Chemical Co., Ltd.)
MS) A solution obtained by dissolving 1 part by weight of 245 parts by weight of methyl isobutyl ketone was added to the tank containing the primary dispersion with stirring.

Subsequently, in the secondary dispersion step, the flow rate of the liquid sending pump was set to 50 parts by weight per minute, and the same dispersion operation as that of the primary dispersion step was performed on the diluent for 15 minutes. I got Further, as a dilution step, 50 parts by weight of cyclohexanone was added to the tank containing the secondary dispersion with stirring. In the final dispersion step, the flow rate of the liquid sending pump was set to 80 parts by weight per minute, and the same dispersion operation of the treatment liquid circulation system as in the primary dispersion step was performed on the diluted liquid for 10 minutes to obtain a final dispersion liquid. Finally, as a filtration and removal step, the final dispersion was filtered out using a filter having an effective pore size of 7 μm (Tocel TCPD-7 manufactured by Advantech Toyo) to obtain a coating liquid for forming a charge generation layer.

Next, this coating solution for forming a charge generation layer was applied onto the undercoat layer applied in Example 1 by the dip coating method.
After drying at 0 ° C. for 5 minutes, a charge generation layer having a dry film thickness of about 0.2 μm was formed. Table 4 shows the state of the charge generation layer visually and the presence or absence of sedimentation of the dispersed particles after the coating liquid for forming the charge generation layer was allowed to stand for 30 days.

[0071]

Embedded image

Next, the hydrazone compound 10 represented by the chemical formula 4
Parts by weight, 0.1 part by weight of α-tocopherol, 8 parts by weight of a polycarbonate resin (C-1400 manufactured by Teijin Chemicals), 2 parts by weight of a polyester resin (Vylon 290 manufactured by Toyobo)
The solution was dissolved in 200 parts by weight of dichloromethane, and the solution was applied on the charge generating layer by dip coating.
After drying for a minute, a charge transfer layer having a dry film thickness of 30 μm was formed.

The laminated electrophotographic photoreceptor thus prepared is supplied to a drum photoreceptor evaluation apparatus (Cynthia 9 manufactured by Gentec).
Using 0), the photosensitive member was charged with a charged voltage of -6.5 kV and irradiated with monochromatic light having a wavelength of 550 nm and an intensity of ² μW / cm 2 to measure the half-life exposure amount E1 / 2 of the photosensitive member. In addition, 5000 of charge and static elimination using tungsten array with the same device
Before and after the repetition, the potential and the residual potential of the photoconductor after charging were measured. Table 5 shows the results.

Example 5 Using a dyno mill having the same configuration as in Example 4, first, the following primary dispersion step was performed. 95 parts by weight of methyl isobutyl ketone was charged into a tank, and 4 parts by weight of the compound represented by Chemical Formula 3 and 1 part by weight of butyral resin (Eslec BM-S) were dissolved therein, and then 5 parts by weight of a bisazo pigment represented by Chemical Formula 2 Was mixed. While stirring the inside of the tank, this liquid was gradually supplied from the processing liquid inlet of the operating mill at a flow rate of sending 20 parts by weight using the liquid supply pump, and dispersed from the processing liquid outlet of the mill. The treated liquid that had undergone the operation was returned to the tank. The dispersion operation of the treatment liquid circulation system described above was performed for 30 minutes to obtain a primary dispersion.

Next, as a dilution step, 245 parts by weight of methyl isobutyl ketone was added to the tank containing the primary dispersion with stirring. Subsequently, as a secondary dispersion step, the flow rate of the liquid feed pump was set to 50 parts by weight per minute, and a dispersion operation of the treatment liquid circulation system similar to the primary dispersion step was performed on this diluent for 15 minutes.
For 2 minutes to obtain a secondary dispersion. Further, as a dilution step, 50 parts by weight of cyclohexanone was added to the tank containing the secondary dispersion with stirring. In the final dispersion step, the flow rate of the liquid sending pump was set to 80 parts by weight per minute, and the same dispersion operation of the treatment liquid circulation system as in the primary dispersion step was performed on the diluted liquid for 10 minutes to obtain a final dispersion liquid. The resulting final dispersion was taken out in the same filtration and take-out step as in Example 5 to obtain a coating liquid for forming a charge generation layer.

This coating solution was applied in the same manner as in Example 4, and the same test as in Example 4 was performed. Table 4 shows the results. An electrophotographic photoreceptor was prepared in the same manner as in Example 4 except that this coating solution for forming a charge generation layer was used instead of the coating solution for forming a charge generation layer in Example 4, and the same test as in Example 4 was performed. Was. Table 5 shows the results.

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[Table 4]

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[Table 5]

The fourth embodiment corresponds to claims 2 and 4 of the present invention, and the fifth embodiment corresponds to claims 1 and 4 of the present invention. Shows,
In comparison between the two, Example 4 is more excellent.

Example 6 As a disperser, a horizontal sand mill (Dynomill KDL manufactured by WAB) into which glass beads having a diameter of 1 mm were charged as a dispersion medium was used, and the following primary dispersion step was first performed.

A tank was charged with 90 parts by weight of methyl ethyl ketone, and a butyral resin (600 manufactured by Denki Kagaku Kogyo Kogyo)
After dissolving 5 parts by weight of 0-EP), 5 parts by weight of τ-type metal-free phthalocyanine (TPA-891 manufactured by Toyo Ink) was mixed. While agitating the inside of the tank, this liquid was used as a liquid sending pump, and an internal gear pump (a chemical gear pump GX-12 manufactured by Iwaki) whose driving liquid contact part was made of the material shown in Table 6 was used to remove 20 parts by weight per minute. The entire amount was gradually charged from the processing liquid inlet of the operating mill at the flow rate to be sent, and the entire amount of the processing liquid subjected to the dispersion operation was received from the processing liquid outlet of the mill in an empty tank. The above operation of passing through the mill was repeated six times to obtain a primary dispersion.

Next, as a dilution step, 300 parts by weight of methyl ethyl ketone was added to the primary dispersion while stirring.
Next, as a final dispersion step, the flow rate of the liquid sending pump was set to 80 parts by weight per minute, and the same liquid-passing operation as in the primary dispersion step was repeated twice. Next, as a filtration and removal step, the final dispersion was filtered out using a filter having an effective pore diameter of 3 μm (Tocel TCPD-3 manufactured by Advantech Toyo Co., Ltd.) to obtain a coating liquid for forming a charge generation layer.

This coating solution was applied to an aluminum drum tube in the same manner as in Example 2, and the same test as in Example 2 was performed. Table 6 shows the results. An electrophotographic photoreceptor was prepared in the same manner as in Example 2 except that this coating solution for forming a charge generation layer was used instead of the coating solution for forming a charge generation layer in Example 2, and the same test as in Example 2 was performed. Was. Table 7 shows the results.

Comparative Example 4 An inversion gear pump (Viking Pump C-43 made by Viking) having a liquid contacting pump whose driving liquid contact portion was made of the material shown in Table 6 was used.
A coating solution for forming a charge generation layer was produced in the same manner as in Example 6, except that the composition was changed to Type 2). This coating solution was applied to an aluminum drum tube in the same manner as in Example 2, and the same test as in Example 2 was performed.
Table 6 shows the results. An electrophotographic photoreceptor was prepared in the same manner as in Example 2 except that this coating solution for forming a charge generating layer was used instead of the coating solution for forming a charge generating layer of Example 2.
The same test was performed. Table 7 shows the results.

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[Table 6]

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[Table 7]

Example 6 corresponds to claims 3 and 4 of the present invention and is superior to comparative example 4.

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As is apparent from the above, according to the present invention, a method for producing a coating solution for producing an electrophotographic photoreceptor, which has a stable pigment dispersion state, has few coating failures during coating, and has little contamination with impurities. By using a coating solution for producing a photoreceptor, it is possible to provide an electrophotographic photoreceptor exhibiting excellent characteristics when used in an electrophotographic process.

Claims (4)

[Claims] 1. A method for producing a coating liquid for producing an electrophotographic photoreceptor comprising pigment particles dispersed in a solvent together with a binder, wherein the production apparatus comprises at least a tank for storing a pigment-containing solvent (treatment liquid), a dispersing machine, The manufacturing process comprises a dispersion step (primary dispersion step) at a concentration higher than the final coating liquid concentration, and a dilution step, which comprises a liquid sending pump and a filter for transferring the processing liquid from the tank to the disperser. After passing through several dispersion steps and dilution steps as required, a dispersion step (final dispersion step) at the concentration of the coating solution and a filtration and removal step of the dispersion of the treated liquid are combined. A processing liquid is sent from a tank to a disperser using a disperser, and a processing liquid that has been subjected to dispersion processing by the disperser is returned to the tank. Production method. 2. The method according to claim 1, wherein an organic charge generating material pigment is used as the pigment particles, the primary dispersion step is performed without adding a binder, the binder is added after the dilution step, and the subsequent dispersion step is performed. The method for producing a coating solution for producing an electrophotographic photosensitive member according to the above. 3. A method for producing a coating liquid for producing an electrophotographic photoreceptor, comprising using an organic charge-generating substance pigment as pigment particles and dispersing the pigment particles together with a binder in a solvent, wherein the production apparatus comprises at least a pigment-containing solvent. (Dispersing machine), a dispensing machine, a liquid sending pump and a filter for transferring the treating solution from the tank to the dispersing machine, and a material of a liquid contacting part of the liquid sending pump is zirconia or silicon. A method for producing a coating liquid for producing an electrophotographic photosensitive member, which is a carbide. 4. The method according to claim 1, 2 or 3.
An electrophotographic photoreceptor having a layer formed using the coating solution for producing an electrophotographic photoreceptor manufactured by the method described in the above.