JPH08166678A - Production of undercoating liquid for electrophotographic photoreceptor and electrophotographic photoreceptor using same - Google Patents

Abstract

PURPOSE: To produce an undercoating liq. having satisfactory dispersibility, excellent in aging stability as a coating liq. and coating performance to an electrically conductive substrate and capable of forming a uniform underlayer and to obtain an electrophotographic photoreceptor less liable to variation in electrification characteristics and residual potential due to repetition by using the undercoating liq. CONSTITUTION: When titanium oxide is dispersed in an org. solvent contg. at least a dissolved bonding resin to produce an undercoating liq. for an electrophotographic photoreceptor, all the titanium oxide to be dispersed is dispersed in an org. solvent in which <=30wt.% of all the bonding resin has been dissolved at a higher concn. of solid matter than the final concn. in a primary dispersing process. In a secondary dispersing process, an org. solvent in which the remainder of the bonding resin has been dissolved is added to the resultant primary dispersion liq. and further dispersion is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member, and more specifically, to a method for producing an undercoating coating liquid provided between a conductive substrate and a photosensitive layer, and charging characteristics and residual properties by repeated use thereof. The present invention relates to an electrophotographic photoreceptor having a small potential change.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photosensitive member,
Those having a photosensitive layer containing an inorganic photoconductor as a main component such as selenium, cadmium sulfide, zinc oxide, and silicon have been widely known. However, they are sensitive, heat stable, moisture resistant,
Durability and the like are not always satisfactory, and particularly selenium and cadmium sulfide are restricted in production and handling due to their toxicity.

On the other hand, an electrophotographic photosensitive member having a photosensitive layer containing an organic photoconductive compound as a main component is relatively easy to manufacture, inexpensive, easy to handle, and generally selenium photosensitive. It has many advantages such as superior thermal stability to the body, and has received much attention in recent years.

As such an organic photoconductive compound,
Poly-N-vinylcarbazole is well known, and an electrophotographic photosensitive material having a photosensitive layer containing as a main component a charge transfer complex formed from this and a Lewis acid such as 2,4,7-trinitro-9-fluorenone. The body is special Japanese Sho 50-10496
No., published in Japanese Unexamined Patent Publication No. However, this photoreceptor was not always satisfactory in sensitivity, film-forming property and durability.

On the other hand, an electrophotographic photosensitive material containing a low molecular weight organic photoconductive compound obtained by combining a charge transporting material represented by triphenylamines, stilbenes and hydrazones with a charge generating material such as phthalocyanine and azo pigments. The body is proposed. By combining these with an appropriate binder resin, and further combining a compound having a high charge generating ability and a compound having a high charge transporting ability, for example, as a laminated type photoreceptor, a compound having a sensitivity close to that of an inorganic photoreceptor such as selenium also appears. are doing. As a result, in the field of copying machines, printers, etc., photoconductors containing such an organic photoconductive compound as a main component have made great progress.

The laminated or dispersed function-separated type photoreceptor in which the charge generating function and the charge transporting function are shared by different substances has a wide selection range of each material, and the charging characteristics, sensitivity and durability are large. It has an advantage that an electrophotographic photosensitive member having arbitrary characteristics in terms of electrophotographic characteristics can be prepared relatively easily.

When such a function-separated type photoreceptor is applied to an electrophotographic process, dark decay is large due to generally poor charging characteristics and charge retention, and the above characteristics are largely deteriorated due to repetition. However, the residual potential is remarkably increased, and there is a defect that density unevenness, fog, etc. occur on the image. In order to improve the electrical characteristics of such a photoreceptor, it is effective to provide an undercoat layer between the conductive substrate and the photosensitive layer.

Generally, the purpose of providing the undercoat layer is to improve surface defects of the conductive substrate, improve adhesion between the photosensitive layer and the substrate, improve coatability of the photosensitive layer, and transfer the conductive substrate to the photosensitive layer. Examples include suppression of charge injection.

The undercoating layer that has been proposed in the past generally comprises a film of an electrically insulating high molecular polymer or an insulating inorganic compound such as Al ₂ O ₃ or SiO ₂ contained in a binder resin. Films have been used.

For example, JP-A-58-98739 and JP-A-60-66258 disclose a nylon resin undercoat layer, and JP-A-58-105155 discloses a polyvinyl alcohol resin undercoat layer. Has been done.

However, although these resin single-layer undercoat layers are excellent in adhesiveness, they have a drawback that the residual potential increases due to repeated electric resistance due to high electric resistance, and the background stain occurs on the image.

Therefore, an undercoat layer has been proposed in which a binder resin contains particles having an appropriate electric conductivity in order to control the electric resistance of the undercoat layer. For example, JP-A-58-5
Japanese Patent No. 8556 discloses an undercoat layer in which an oxide of aluminum or tin is dispersed in a resin, and Japanese Patent Laid-Open Nos. 58-9306 and 60-97363 disclose conductive particles in a resin. The undercoat layer is also disclosed in JP-A-59-84.
No. 257 and JP-A-60-32054 disclose T
An undercoat layer in which iO ₂ and SnO ₂ powder are dispersed in a resin is disclosed.

However, in the undercoat layer in which the particles having the appropriate electric conductivity are dispersed in the resin as described above, it is necessary to reduce the amount of the resin in order to improve the electrostatic characteristics of the electrophotographic photoreceptor. . Further, in order to produce a coating liquid for forming such an undercoat layer, a step of stably dispersing the particles in an organic solvent or the like in which a resin is dissolved is required.

In particular, when titanium oxide is dispersed in an organic solvent in which a binder resin is dissolved, the dispersibility varies greatly depending on the presence or absence of surface treatment of titanium oxide, the type of surface treatment, the type and amount of binder resin. However, there is a difference in the stability of the coating liquid and eventually in the electrical characteristics.

[0015]

The problem to be solved by the present invention is to form a uniform undercoat layer having good dispersibility, excellent stability over time as a coating liquid, and excellent coatability on a conductive substrate. PROBLEM TO BE SOLVED: To provide a method for producing an undercoating coating liquid for an electrophotographic photosensitive member, and to provide an electrophotographic photosensitive member having a small change in charging characteristics and residual potential by repeating the use of the undercoating coating liquid for an electrophotographic photosensitive member. To do.

[0016]

As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that undercoating for electrophotographic photoreceptors in which titanium oxide is dispersed in at least an organic solvent in which a binder resin is dissolved. In the method for producing a coating liquid, an organic solvent in which the undercoating liquid has a solid content concentration higher than the final concentration and the total amount of titanium oxide to be dispersed is 30% by weight or less of the total amount of the binding resin. A primary dispersion step of dispersing in,
Having a secondary dispersion step in which an organic solvent in which the remaining binder resin is dissolved is added to the primary dispersion coating liquid to obtain a final solid content concentration, and then further dispersed, and the undercoat coating liquid is applied to an electrophotographic photoreceptor. The inventors have found that the above problems can be solved by using them, and have reached the present invention.

The present invention will be described in detail below.

First, as the electroconductive substrate on which the photosensitive layer of the photoconductor is formed, any of those known in electrophotographic photoconductors can be used. Specifically, for example, gold, silver,
Examples include platinum, titanium, aluminum, copper, zinc, iron, drums, sheets and belts of metal oxides or the like that have been subjected to conductive treatment, laminates of these thin films, vapor depositions and the like.

Further, metal powder, metal oxide, carbon black, carbon fiber, copper iodide, charge transfer complex, inorganic salt,
Drums, sheets, belts, etc. made of plastics, ceramics, paper, etc., which are coated with a conductive substance such as an ion-conductive polymer electrolyte together with an appropriate binder resin and embedded in a polymer matrix and subjected to a conductive treatment Can be mentioned.

The undercoat layer is formed from a coating liquid in which titanium oxide is dispersed in an organic solvent in which at least a binder resin is dissolved, and the coating liquid has a solid content concentration higher than the final concentration and contains the total amount of titanium oxide to be dispersed. A primary dispersion step of dispersing 30% by weight or less of the total binder resin in an organic solvent in which the binder resin is dissolved, and an organic solvent in which the remaining binder resin is dissolved are added to the primary dispersion coating liquid to obtain a final solid content. It is manufactured by a secondary dispersion step of further dispersing after the concentration. The amount of binder resin in the primary dispersion step is 0% by weight or more and 30% by weight or less, preferably 5% by weight or more and 15% by weight or less, based on the total amount of the binder resin.

The titanium oxide used for the undercoat layer may be any of rutile type, anatase type, brookite type and amorphous. The shape of titanium oxide primary particles may be acicular or granular. In general, most of commercially available titanium oxides have surface-treated titanium oxides in order to improve dispersibility and dispersion stability. However, this surface treatment affects the electrical properties,
It may not be preferable for use in the undercoat layer. Therefore, the titanium oxide that has not been surface-treated can bring out the characteristics of the titanium oxide itself. In the present invention, the titanium oxide may or may not be surface-treated, but it is particularly effective in improving dispersibility and dispersion stability with respect to titanium oxide not surface-treated. .

The binder resin used in the undercoat layer is
Polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic acid ester, methacrylic acid ester, etc., silicone resin, phenoxy resin, polysulfone resin, polyvinyl butyral resin, polyvinyl formal resin, polyester resin, cellulose ester resin, cellulose ether Any of various polymers such as resin, urethane resin, phenol resin, epoxy resin, polycarbonate resin, polyarylate resin, polyamide resin, and polyimide resin can be used, but polyamide resin, particularly alcohol-soluble nylon resin is particularly preferable.

Alcohol-soluble nylon resins are soluble only in lower aliphatic alcohols such as methanol and ethanol. Therefore, as a coating solvent for forming a photosensitive layer on an undercoat layer made of these resins, a solvent other than lower alcohol is used. The solvent selection range can be widened. When the photosensitive layer is coated with a solvent capable of dissolving the undercoat layer, there arises inconveniences such as mixing with the undercoat layer to deteriorate the characteristics and non-uniformity of the coated surface depending on the coating method. Alcohol-soluble nylon resins can be roughly classified into two types, one is nylon 6, nylon 66, and nylon 61.
A type called so-called copolymer nylon, which is obtained by copolymerizing 0, nylon 11, nylon 12, etc., the other is N
It is a type called modified nylon obtained by chemically modifying nylon such as -alkoxymethyl modified nylon and N-alkoxyethyl modified nylon. The alcohol-soluble nylon resin used in the present invention can be used with both of them and exhibits excellent properties.

As the solvent used for the undercoating liquid, any solvent can be used as long as it dissolves the binder resin.
In particular, when the above alcohol-soluble nylon resin is selected as the binder resin, lower aliphatic alcohol is mainly used, but halogen-containing carbonization such as benzyl alcohol, dichloromethane, dichloroethane, 1,1,2-trichloroethane, carbon tetrachloride, etc. You may use the mixed solvent which added hydrogen etc.

In order to obtain an undercoat coating liquid, titanium oxide,
Binder resin contained in an appropriate organic solvent, ball mill, vertical sand mill, horizontal sand mill, paint shaker,
It can be obtained by processing with a dispersing means such as Dynomill or an attritor. At this time, in order to improve the dispersion efficiency and stability over time of the coating liquid, the primary dispersion step with a high concentration and a low binder resin content, and the remaining organic solvent and the binder resin were added to the primary dispersion liquid for the purpose. After the composition to be set, by dividing into two steps of the secondary dispersion step of dispersing again,
An undercoating liquid having good dispersion stability can be obtained.

The ratio of titanium oxide to the binder resin in the present invention is 1 to 500 parts by weight, preferably 1 to 100 parts by weight of the binder resin with respect to 100 parts by weight of titanium oxide.
Used in the range of parts by weight. The thickness of the undercoat layer is 0.05 to 20 μm, preferably 0.1 to 5 μm.

In the present invention, an undercoat layer is formed on a conductive substrate, and then a photosensitive layer is formed thereon to be used as an electrophotographic photoreceptor. The photosensitive layer is a pigment-dispersed single-layer type in which a charge-generating substance such as a pigment is dispersed and embedded in a binder resin, or a single-layer type in which a charge-generating substance and a charge-transporting substance are dispersed and mixed and enclosed in a binder resin. , A charge-generating substance and a charge-transporting substance are separated and sealed in a binder resin. The present invention can be applied to any system, but it is preferably used in a system of a function-separated layered photoreceptor in which the performance of a charge generating substance and a charge transporting substance can be maximized.

As the charge generating substance used in the photosensitive layer, azo pigments represented by monoazo pigments, bisazo pigments, polyazo pigments, metal complex salt azo pigments, pyrazolone azo pigments and thiazole azo pigments, perylene anhydrides and perylenes. Perylene pigments represented by acid imides, anthraquinone derivatives, anthanthrone derivatives, dibenzpyrenequinone derivatives, pyranthrone derivatives, anthraquinone or polycyclic quinone pigments represented by violanthrone derivatives, metal phthalocyanines, metal naphthalocyanines, Examples thereof include phthalocyanine-based pigments represented by metal-free phthalocyanine and metal-free naphthalocyanine. Examples of dyes that can be used include triphenylmethane dyes typified by methyl violet, quinone dyes such as quinizarin, pyrylium salts, thiapyrylium salts, and benzopyrylium salts.

Of these, bisazo pigments, trisazo pigments, and phthalocyanine pigments having high carrier generation efficiency are preferable because they give high sensitivity and provide an excellent photoreceptor. For example, in the case of a bisazo pigment, JP-A-62-286058 and JP-A-6-286058.
No. 3-32557, No. 63-243948,
The compounds described in JP-A 64-21453, 64-21455, JP-A-1-94350, 1-200267, 1-2202757, etc. can be used.

In the function-separated type laminated photoreceptor, the charge generation layer can be provided by adding at least the above-mentioned charge generation substance and the binder resin, dissolving or dispersing it in a suitable solvent, and coating it on a conductive substrate. As the binder resin for the charge generation layer used, conventionally known polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic acid ester, and methacrylic acid ester, silicone resin, phenoxy resin, polyvinyl formal. Examples thereof include resins, polyvinyl butyral resins, urethane resins, phenol resins, polyamide resins, polyimide resins, polycarbonate resins, polyester resins, and polyarylate resins, but are not limited thereto.

The binder resin for the charge generating layer is the charge generating substance 1
It is used in the range of 1 to 1000 parts by weight, preferably 1 to 400 parts by weight, relative to 00 parts by weight. The thickness of the charge generation layer is 0.05 to 20 μm, preferably 0.1.
To 2 μm.

Solvents used as necessary for preparing a coating solution for forming the charge generation layer include ethers such as 1,2-dimethoxyethane, tetrahydrofuran, 1,3-dioxolane, and 1,4-dioxane. Ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, aprotic polar solvents such as N, N-dimethylformamide, acetonitrile, N-methylpyrrolidone and dimethyl sulfoxide, alcohols such as methanol, ethanol and isopropanol. Kind,
Examples thereof include esters such as methyl acetate, ethyl acetate and methyl cellosolve acetate, halogenated hydrocarbons such as dichloroethane and chloroform.

Examples of the charge transport material used in the photosensitive layer include oxadiazoles disclosed in JP-B-34-5466 and triphenylmethanes disclosed in JP-B-45-555. Kosho 52-4188
Disclosed in Japanese Patent Publication No. 55-42
Hydrazones disclosed in Japanese Patent Laid-Open No. 380,380, JP-A-56
Oxadiazoles disclosed in JP-A-123544, triarylamines disclosed in JP-B-58-32372, and JP-A-58-198043. Examples thereof include stilbenes.
These charge transport materials may be used alone or in combination of two or more.

Among these charge transport materials, hydrazone compounds, stilbene compounds and the like are preferable because they have a high charge mobility and provide an excellent photoreceptor. For example, examples of the hydrazone compound include JP-B-55-42380 and JP-A-1-100555.
No. 2-10367, No. 2-511163, No. 2-96767, No. 2-183260, No. 2-184856, No. 2-184858,
The hydrazone compounds disclosed in JP-A-2-184859 and JP-A-2-226160 can be used.

The charge transport layer can be provided by adding the charge transport material and the binder resin as described above, dissolving in a suitable solvent, and coating.

The binder resin used is styrene,
Polymers and copolymers of vinyl compounds such as vinyl chloride, vinyl acetate, acrylic acid ester, methacrylic acid ester, polycarbonate resin, polyarylate resin, polyester resin, phenoxy resin, polysulfone, cellulose ester resin, cellulose ether resin, urethane resin , Various polymers such as epoxy resin and silicone resin.

Examples of the solvent used include tetrahydrofuran, 1,3-dioxolane, methyl ethyl ketone, benzene, toluene, monochlorobenzene, 1,2-dichloroethane, dichloromethane, chloroform and ethyl acetate.

The binder resin for the charge transport layer is the charge transport material 10
10 to 500 parts by weight, preferably 50 parts by weight, relative to 0 parts by weight
Used in the range of 200 to 200 parts by weight. The thickness of the charge transport layer is used in the range of 1 to 100 μm, preferably 10 to 50 μm.

A surface layer may be provided on the surface of the photosensitive layer in order to improve the durability of the photosensitive member.

Further, the photosensitive layer may contain a well-known plasticizer in order to improve film-forming property, flexibility and mechanical strength. Examples of the plasticizer include phthalic acid esters, phosphoric acid esters, chlorinated paraffins, chlorinated fatty acid esters, aromatic compounds such as methylnaphthalene, and the like.

Further, in order to improve the electrophotographic characteristics of the photoconductor, an additive such as an antioxidant may be contained.

[0042]

EXAMPLES The present invention will now be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

Example 1 1.5 parts by weight of an alcohol-soluble nylon resin (Amilan CM4000 manufactured by Toray Industries, Inc.) as a binder resin was mixed in a mixed solvent of 250 parts by weight of methanol, 100 parts by weight of n-butanol and 350 parts by weight of dichloroethane. Dissolved. Ultra fine particle titanium oxide as titanium oxide (Taipaque TTO-55 (N) surface treatment manufactured by Ishihara Sangyo Co., Ltd.)
250 parts by weight was added, and a polypropylene container was used to disperse beads of zirconia having a diameter of 0.6 mm for 2 hours with a paint shaker to obtain a primary dispersion liquid. Next, as a secondary dispersion, a solution of 11 parts by weight of alcohol-soluble nylon (Amilan CM4000) dissolved in a mixed solvent of 500 parts by weight of methanol, 200 parts by weight of n-butanol and 700 parts by weight of dichloroethane was added to this primary dispersion liquid, Disperse with a paint shaker for 30 minutes,
An undercoat coating liquid was prepared. Immediately after the dispersion of the undercoating liquid thus obtained and the change in viscosity after standing for 15 days at room temperature, an R-type viscometer (R100 type manufactured by Toki Sangyo Co., Ltd.) was examined.
The results shown in Table 1 were obtained. The measurement conditions of the viscosity were 20 ° C. and the cone rotation speed was 20 rpm. As can be seen, the change in viscosity with time is extremely small. Further, it was found that almost no precipitation of titanium oxide was observed and the dispersion stability was excellent. Further, this undercoat coating liquid was applied to an aluminum vapor-deposited PET film (Metal Me by Toray Industries, Inc.) with an applicator and dried at 80 ° C. for 15 minutes to form an undercoat layer having a thickness of about 0.8 μm.

[0044]

[Table 1]

[0045]

Embedded image

Next, 1 part by weight of the bisazo pigment represented by the above formula 1 and 1 part by weight of polyvinyl butyral resin (Denka Butyral # 3000-2 manufactured by Denki Kagaku Co., Ltd.) were added.
-Mixed with 100 parts by weight of dimethoxyethane and dispersed with glass beads for 4 hours with a paint shaker. The thus-obtained pigment dispersion is applied onto the undercoat layer with an applicator and dried at 80 ° C. for 15 minutes to give a film thickness of about 0.4 μm.
m charge generating layer was obtained.

[0047]

Embedded image

Next, 10 parts by weight of the hydrazone compound represented by the above formula 2, 10 parts by weight of a polycarbonate resin (Panlite C-1400 manufactured by Teijin Chemicals Ltd.), 0.1 part by weight of DL-α-tocopherol are added to 200 parts of dichloromethane. This solution was dissolved in 1 part by weight, and this solution was applied onto the charge generation layer by an applicator and dried at 80 ° C. for 60 minutes to form a charge transport layer having a dry film thickness of 20 μm.

The laminated electrophotographic photosensitive member thus produced was stored overnight at room temperature in a dark place, and then electrophotographic characteristics were evaluated by an electrostatic recording test apparatus (SP-428 manufactured by Kawaguchi Electric Co., Ltd.). The measurement conditions are: corona applied voltage: -5 kV,
Static mode No. 3 (Process speed 167 mm
/ Sec), illumination light (white light) illuminance: 2lux. As a result, the charging potential was −720 V and the half-exposure amount was 1.2 lux.
・ It showed a very high sensitivity value of seconds.

Next, this photoconductor was attached to an aluminum drum base tube, and the repeating characteristics of charging and photo-electrification were evaluated by a drum photoconductor evaluation device (Cynthia 90 manufactured by Gentec Co., Ltd.). Measured corona applied voltage: -5.2k
V, process speed 160 mm / sec, and 5000 times of charging and photo-erasing in TCCD2 mode were repeated. Photostatic elimination was performed using a tungsten lamp array. Table 2 shows the measurement results of the surface potential after charging, that is, the charging potential, and the surface potential after photo-eliminating, that is, the residual potential. It can be seen that the changes in charging potential and residual potential are extremely small.

[0051]

[Table 2]

Example 2 In the dispersion of the undercoating liquid of Example 1, alcohol-soluble nylon (Toresin EF-30T manufactured by Teikoku Chemical Industry Co., Ltd.) was used as a binder resin, and the dispersion medium had a diameter of 0.6.
The undercoating liquid was prepared in the same manner as in Example 1 except that the titania beads of mm were used, and the viscosity was measured to prepare a photoconductor, and the electrophotographic characteristics and the repeating characteristics were measured. The results are shown in Tables 3 and 4.

Example 3 In the dispersion of the undercoat coating liquid of Example 1, needle-shaped titanium oxide was used as titanium oxide (FTL-100 manufactured by Ishihara Sangyo Co., Ltd.).
Was used to prepare a subbing coating liquid in the same manner as in Example 1 except that the titania beads having a diameter of 1 mm were used as the dispersion medium.
The viscosity was measured to prepare a photoconductor, and the electrophotographic characteristics and the repeating characteristics were measured. The results are shown in Tables 3 and 4.

Example 4 An undercoat coating solution was prepared in the same manner as in Example 1 except that P-25 manufactured by Nippon Aerosil Co., Ltd. was used as titanium oxide in the dispersion of the undercoat coating solution of Example 1. The viscosity was measured to prepare a photoconductor, and the electrophotographic characteristics and the repeating characteristics were measured. The results are shown in Tables 3 and 4.

Example 5 As a binder resin, alcohol-soluble nylon (Toray Industries, Inc.)
Amilan CM8000) (1.5 parts by weight) was dissolved in a mixed solvent of 490 parts by weight of dichloroethane and 270 parts by weight of methanol. Fine titanium oxide (no surface treatment of STR-60N manufactured by Sakai Chemical Industry Co., Ltd.) as titanium oxide 2
50 parts by weight was added, and zirconia beads having a diameter of 1 mm were used as a dispersion medium for dispersion for 2 hours with a Dyno-mill to obtain a primary dispersion. Next, as secondary dispersion, alcohol-soluble nylon (Amilan CM8000) 12 was added to this primary dispersion.
900 parts by weight of dichloroethane and 48 parts by weight of methanol
A solution dissolved in 0 part by weight of a mixed solvent was added and further dispersed by a Dyno-mill for 30 minutes to prepare an undercoating liquid. Using this undercoat coating solution, the viscosity was measured in the same manner as in Example 1 and an undercoat layer was formed in the same manner. The results are shown in Table 3.

[0056]

Embedded image

Next, 1 part by weight of the bisazo pigment represented by the above formula 3 and a phenoxy resin (Union Carbide Co., Ltd.)
Manufactured by PKHJ) and 1 part by weight of methyl isobutyl ketone 10
The mixture was mixed with 0 parts by weight and dispersed with glass beads for 4 hours using a paint shaker. The pigment dispersion thus obtained was coated on the undercoat layer with an applicator and dried at 80 ° C. for 15 minutes to obtain a charge generation layer having a thickness of about 0.4 μm.

[0058]

[Chemical 4]

Next, 10 parts by weight of the hydrazone compound represented by the above formula 4, 7 parts by weight of a polycarbonate resin (Panlite K-1300 manufactured by Teijin Chemicals Ltd.), 3 parts by weight of a polyester resin (Vylon 290 manufactured by Toyobo Co., Ltd.) Section, DL-α
-0.1 parts by weight of tocopherol in 200 parts of dichloromethane
This solution was dissolved in 1 part by weight, and this solution was applied onto the charge generation layer by an applicator and dried at 80 ° C. for 60 minutes to form a charge transport layer having a dry film thickness of 20 μm.

The laminated electrophotographic photosensitive member thus produced was measured for electrophotographic characteristics and repetitive characteristics in the same manner as in Example 1. The results are shown in Table 4.

Example 6 An undercoating liquid was prepared in the same manner as in Example 5 except that titania beads having a diameter of 0.6 mm were used as the dispersion medium in the dispersion of the undercoating liquid in Example 5. The measurement was performed to prepare a photoconductor, and the electrophotographic characteristics and the repeating characteristics were measured in the same manner as in Example 1. The results are shown in Tables 3 and 4.

Example 7 In the dispersion of the undercoating liquid of Example 5, ultrafine titanium oxide (Taipaque T manufactured by Ishihara Sangyo Co., Ltd.) was used as titanium oxide.
(TO-55 (N) surface-treated) was used, and a subbing coating solution was prepared in the same manner as in Example 5 except that titania beads having a diameter of 1 mm were used as the dispersion medium, and the viscosity was measured. It was manufactured and electrophotographic characteristics and repetitive characteristics were measured in the same manner as in Example 1. The results are shown in Tables 3 and 4.

Example 8 An undercoat coating liquid was prepared in the same manner as in Example 5 except that alcohol-soluble nylon (Daiamide Chemical Co., Ltd. Daiamide 1874) was used as a binder resin in the dispersion of the undercoat coating liquid of Example 5. Is prepared, viscosity is measured, and a photoreceptor is prepared.
Electrophotographic characteristics and repetitive characteristics were measured in the same manner as in Example 1. The results are shown in Tables 3 and 4.

[0064]

[Table 3]

[0065]

[Table 4]

Comparative Example 1 Undercoating was carried out in the same manner as in Example 1 except that the binder resin in Example 1 was completely dissolved in the primary dispersion step and only the solvent was added in the secondary dispersion step. A coating liquid was prepared, the viscosity was measured, a photoreceptor was prepared, and electrophotographic characteristics and repetitive characteristics were measured. The results are shown in Tables 5 and 6.

Comparative Example 2 Undercoating was carried out in the same manner as in Example 1 except that the binder resin was completely dissolved in the primary dispersion step and only the solvent was added in the secondary dispersion step in dispersing the undercoating coating solution in Example 2. A coating liquid was prepared, the viscosity was measured, a photoreceptor was prepared, and electrophotographic characteristics and repetitive characteristics were measured. The results are shown in Tables 5 and 6.

Comparative Example 3 In the undercoating liquid dispersion of Example 3, the undercoating was carried out in the same manner as in Example 1 except that the binder resin was completely dissolved in the primary dispersion step and only the solvent was added in the secondary dispersion step. A coating liquid was prepared, viscosity was measured, a photoreceptor was prepared, and electrophotographic characteristics and repetitive characteristics were measured. The results are shown in Tables 5 and 6.

Comparative Example 4 Undercoating was carried out in the same manner as in Example 1 except that the binder resin was completely dissolved in the primary dispersion step and only the solvent was added in the secondary dispersion step in the dispersion of the undercoat coating solution of Example 4. A coating liquid was prepared, viscosity was measured, a photoreceptor was prepared, and electrophotographic characteristics and repetitive characteristics were measured. The results are shown in Tables 5 and 6.

Comparative Example 5 Undercoating was carried out in the same manner as in Example 5 except that all the binder resin was dissolved in the primary dispersion step and only the solvent was added in the secondary dispersion step in the dispersion of the undercoat coating liquid of Example 5. A coating liquid was prepared, viscosity was measured in the same manner as in Example 1, a photoreceptor was prepared in the same manner as in Example 5, and electrophotographic characteristics and repetitive characteristics were measured in the same manner as in Example 1. The results are shown in Table 5 and Table 6.
Shown in

Comparative Example 6 Undercoating was carried out in the same manner as in Example 5 except that the binder resin was completely dissolved in the primary dispersion step and only the solvent was added in the secondary dispersion step in the dispersion of the undercoat coating solution of Example 6. A coating liquid was prepared, viscosity was measured in the same manner as in Example 1, a photoreceptor was prepared in the same manner as in Example 5, and electrophotographic characteristics and repetitive characteristics were measured in the same manner as in Example 1. The results are shown in Table 5 and Table 6.
Shown in

Comparative Example 7 Undercoating was carried out in the same manner as in Example 5 except that the binder resin was completely dissolved in the primary dispersion step and only the solvent was added in the secondary dispersion step in the dispersion of the undercoat coating solution of Example 7. A coating liquid was prepared, viscosity was measured in the same manner as in Example 1, a photoreceptor was prepared in the same manner as in Example 5, and electrophotographic characteristics and repetitive characteristics were measured in the same manner as in Example 1. The results are shown in Table 5 and Table 6.
Shown in

Comparative Example 8 Undercoating was carried out in the same manner as in Example 5 except that all the binder resin was dissolved in the primary dispersion step and only the solvent was added in the secondary dispersion step in the dispersion of the undercoat coating liquid of Example 8. A coating liquid was prepared, viscosity was measured in the same manner as in Example 1, a photoreceptor was prepared in the same manner as in Example 5, and electrophotographic characteristics and repetitive characteristics were measured in the same manner as in Example 1. The results are shown in Table 5 and Table 6.
Shown in

Comparative Example 9 In the dispersion of the undercoat coating liquid of Example 1, except that the alcohol-soluble nylon resin in the primary dispersion step was 6 parts by weight and the alcohol-soluble nylon resin in the secondary dispersion step was 7 parts by weight. An undercoating liquid was prepared in the same manner as in Example 1, the viscosity was measured, and the electrophotographic characteristics and the repeating characteristics were measured. The results are shown in Tables 7 and 8.

Comparative Example 10 In the dispersion of the undercoating liquid of Example 1, except that the alcohol-soluble nylon resin in the primary dispersion step was 9 parts by weight and the alcohol-soluble nylon resin in the secondary dispersion step was 4 parts by weight. An undercoating liquid was prepared in the same manner as in Example 1, the viscosity was measured, and the electrophotographic characteristics and the repeating characteristics were measured. The results are shown in Tables 7 and 8.

Comparative Example 11 In the dispersion of the undercoat coating liquid of Example 5, the alcohol-soluble nylon resin in the primary dispersion step was 8 parts by weight and the alcohol-soluble nylon resin in the secondary dispersion step was 5.5 parts by weight. An undercoating liquid was prepared in the same manner as in Example 5 except for the above, and the viscosity was measured in the same manner as in Example 1 to measure electrophotographic characteristics and repetitive characteristics.
The results are shown in Tables 7 and 8.

Comparative Example 12 In the dispersion of the undercoat coating liquid of Example 5, the alcohol-soluble nylon resin in the primary dispersion step was 10 parts by weight, and the alcohol-soluble nylon resin in the secondary dispersion step was 3.5 parts by weight. An undercoating liquid was prepared in the same manner as in Example 5 except for the above, and the viscosity was measured in the same manner as in Example 1 to measure electrophotographic characteristics and repetitive characteristics.
The results are shown in Tables 7 and 8.

[0078]

[Table 5]

[0079]

[Table 6]

[0080]

[Table 7]

[0081]

[Table 8]

From these results, the undercoating coating liquid of the present invention shown in Examples is superior in stability over time to the coating liquids as compared with Comparative Examples, and the photoconductors produced using this coating liquid are It can be seen that the electrophotographic characteristics, particularly the stability of the charging potential and the residual potential due to repeated use, are superior to those of the comparative example.

[0083]

As is apparent from the above, according to the present invention, an undercoating coating liquid having excellent stability over time can be produced, and by using this coating liquid, high sensitivity, low residual potential, and It is possible to provide an electrophotographic photoreceptor having excellent repeatability.

Claims (2)

[Claims] 1. A method for producing an undercoating liquid for an electrophotographic photosensitive member, wherein titanium oxide is dispersed in an organic solvent in which at least a binder resin is dissolved, wherein the undercoating liquid has a solid content concentration higher than the final concentration. And a primary dispersion step in which the total amount of titanium oxide to be dispersed is dispersed in an organic solvent in which 30% by weight or less of the total amount of the binder resin is dissolved, and the remaining binder resin is dissolved in the primary dispersion coating liquid. The method for producing an undercoat coating liquid for an electrophotographic photoreceptor, which comprises a secondary dispersion step of adding the above organic solvent to a final solid content concentration and further dispersing. 2. An electrophotographic photosensitive member having an undercoat layer formed from the undercoat coating liquid produced by the method according to claim 1.