JP2002229236A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor in which defects on a conductive substrate are covered without degrading excellent electrophotographic characteristics and which is excellent in stability for repeated use and in environmental characteristics. SOLUTION: In the electrophotographic photoreceptor having a photosensitive layer formed a conductive supporting body via a base coating layer, the base coating layer essentially consists of a polyimide precursor having a unit component expressed by general formula [I] and contains a polyimide resin expressed by general formula [II]. In the formulae, R1 is a tetravalent aromatic hydrocarbon group, R2 is a bivalent polycyclic aromatic group in which the aromatic rings may be connected with different kinds of atoms, and n is an integer representing the polymerization degree.

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 used in an electrophotographic apparatus such as a copying machine or a laser beam printer, and more particularly to an electrophotographic photosensitive member using an organic photoconductive material having an undercoat layer formed thereon. It is related to.

[0002]

2. Description of the Related Art Generally, an electrophotographic process using a photosensitive member is performed as follows. That is, in a dark place, for example, charging is performed by a charging roller, and then image exposure is performed to selectively eliminate the charge of only the exposed portion to form an electrostatic latent image, and then visualized with a developer to form an image. It's being used. The basic characteristics required for such an electrophotographic photoreceptor include (i) that it can be charged to an appropriate potential in a dark place;
i) It has a function of eliminating surface charges by light irradiation. The electrophotographic photoreceptor currently in practical use has a basic structure in which a photosensitive layer is formed on a conductive support, but the photosensitive layer is formed due to unnecessary charge injection from the conductive support to the photosensitive layer. To prevent the occurrence of image defects such as dust and fog due to the disappearance or decrease of the surface charge, to cover the defects on the surface of the conductive support, to improve the chargeability, and to improve the adhesiveness of the photosensitive layer, the photosensitive support and the photosensitive support are used. It has been practiced to provide an undercoat layer between the layers. Conventionally, it has been known to use resin materials such as polyethylene, polypropylene, polystyrene, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, silicone resin, and polyamide resin as the undercoat layer. Of these, polyamide resins are particularly preferred.

[0003]

By the way, in the electrophotographic photosensitive member using a polyamide resin or the like for the undercoat layer as described above, the volume resistance value is 10 ¹² to 10 ¹⁵ Ω · cm.
Therefore, if the thickness of the undercoat layer is not reduced to about 1 μm or less, a residual potential is accumulated on the photoconductor, and fogging occurs in an image. On the other hand, when the thickness is reduced, not only is it impossible to cover the defects on the conductive support, but also there are problems such as the charging property of the photoreceptor being unstable. Further, there is a problem that not only the accumulation of the residual potential at the time of repeated use is remarkable, but also the light sensitivity is lowered, so that the image is fogged to deteriorate the image quality.

On the other hand, JP-A-8-30007 discloses that
An undercoat layer using a polyimide resin soluble in an organic solvent is described. Generally, polyimide resin has excellent heat resistance,
A solution of an intermediate polyamic acid formed by condensation polymerization of a tetracarboxylic dianhydride and an aromatic diamine is applied to an object, dried and baked usually at a temperature of 200 ° C. or higher. Become Many polyimide resins are stable at 300 ° C. for a long time. The publication discloses that the undercoat layer is dried at a high temperature of 200 ° C. However, when the undercoat layer in a completely polyimide state is used as described in the above publication, the residual potential after repeated use of the photoconductor increases,
There is a problem that dust fog occurs in the image.

An object of the present invention is to provide an electrophotographic photoreceptor which covers defects on a conductive substrate without impairing excellent electrophotographic characteristics and has excellent repetition stability and environmental characteristics.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the electrophotographic photosensitive member having a photosensitive layer formed on a conductive support via an undercoat layer has been developed. An electrophotographic photoreceptor in which the undercoat layer contains a specific polyimide precursor as a main component, and contains an imidized polyimide resin has no problems of the conventional technology, and is excellent over a long period of time. The inventors have found that the electrostatic characteristics are maintained, and have completed the present invention.

A commonly used polyimide varnish is imidized into a polyimide through the following baking step. That is, the formula [A] is a polyamic acid solution,
It is obtained by reacting an aromatic diamine with an aromatic carboxylic dianhydride. When this is heated, the solvent volatilizes and becomes an intermediate (precursor) before imidization (formula [B]). Further, it is imidized through a baking step of heating at a temperature of 200 ° C. to 300 ° C. to obtain a polyimide (formula [C]). As a result of intensive studies, the present inventors have found that, in the film state of the formula [C] in which the undercoat layer is completely polyimided, after repeated use, the residual potential is increased and dust fog is generated on an image. In the formula [B] before imidization, the photoreceptor characteristics are stable and the image is good even when used repeatedly, and even when the formula [C] and the formula [B] are mixed, the photoreceptor is repeatedly used. It was confirmed that the photosensitive member characteristics were stable and the image was good even when used. Further, it has been found that controlling the drying temperature as a condition for maintaining the mixed state of the formulas [C] and [B] improves the image quality.

[0008]

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That is, the present invention provides an electrophotographic photosensitive member having a photosensitive layer formed on a conductive support via an undercoat layer,
The undercoat layer has the general formula [I]

Embedded image [Wherein, R ₁ is a tetravalent aromatic hydrocarbon group, R ₂ is a divalent polycyclic aromatic group in which aromatic rings may be linked by different atoms, and n is an integer representing the degree of polymerization. It is. The above formula [A] ~
The same applies to [C] and the following general formula [II]. ] Containing as a main component a polyimide precursor having a unit component represented by the general formula [II]

Embedded image The present invention relates to an electrophotographic photosensitive member containing an imidized polyimide resin represented by the formula: The undercoat layer improves the film forming property, and covers defects such as pinholes of the conductive support even in the thin film, and the barrier function and the adhesive function of the photosensitive layer are much better than those of the conventional polyamide resin. And the state of the image is much better than that of the polyimide resin. The mixing ratio of the polyimide precursor and the polyimide resin is 20% to 7% of the total weight of the polyimide resin and the polyimide precursor.
The content is preferably 0%, more preferably 30% to 50%. If it is less than 20%, the undercoat layer will be dissolved in the organic solvent, and if it exceeds 70%, it will be in a state close to imidization, and the residual potential after repetition will be accumulated, resulting in image failure.

[0010] The molecular weight of the polyimide precursor and the polyimide resin is preferably in the range of 1,000 to 100,000, particularly 10,000 to 30,000. Such a polyimide precursor and a polyimide resin have unit components represented by the general formulas [I] and [II]. Specific examples of R ₁ and R ₂ are as follows.

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The drying temperature for forming the undercoat layer is preferably in the range of 110 ° C. to 170 ° C. 11
If the temperature is lower than 0 ° C., the undercoat layer is dissolved by the solvent, and thus cannot be applied to the photoreceptor. When dried at 110 ° C. or higher, it does not dissolve in the organic solvent. If the temperature exceeds 170 ° C., the residual potential after repeated use rises, which causes a problem that dust fog is generated on an image.

Further, the undercoat layer has a polyimide precursor having a unit component represented by the general formula [I] and a polyimide precursor having the general formula [II]:
By containing the polyimide resin represented by the formula and titanium oxide, the dielectric constant of the undercoat layer can be increased, the thickness can be increased, and the dispersibility can be improved.

Further, the undercoat layer has a polyimide precursor having a unit component represented by the general formula [I];
By providing a two-layer structure of a layer containing a polyimide resin represented by I] and a layer made of a thermosetting resin or a thermoplastic resin on the layer, even if the undercoat layer becomes thicker, the accumulation of the residual potential can be reduced. In addition, image quality is improved, and light interference due to laser exposure is also suppressed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the electrophotographic photosensitive member according to the present invention will be described below in detail. The present invention
For example, a function separation type electrophotographic photoreceptor in which a charge generation layer containing at least a charge generation agent is formed on a conductive support, and a charge transfer layer containing at least a charge transfer agent is formed thereon. Applicable. in this case,
A photosensitive layer is formed by the charge generation layer and the charge transfer layer.

Further, the present invention provides a single-layer electrophotographic photosensitive member in which a charge generating agent and a charge transfer agent are contained in the same layer, and a reverse-stacked electrophotographic photoconductor in which a charge transfer layer and a charge generation layer are stacked in this order. The invention can be applied to a photoreceptor and the like.

Examples of the conductive support usable in the present invention include simple metals such as aluminum, brass, stainless steel, nickel, chromium, titanium, gold, silver, copper, tin, platinum, molybdenum and indium, and alloys thereof. Processed products and conductive materials such as the above metals and carbon, which are treated by vapor deposition, plating, etc., to give conductive plastic plates and films, and conductive coated with tin oxide, indium oxide and aluminum iodide The conductive support can be formed by using various conductive materials, such as conductive glass, without being limited by the type or shape. The conductive support may be in the form of a drum, a rod, a plate, a sheet, or a belt.

As the charge generating agent that can be used in the present invention, disazo pigments and oxytitanium phthalocyanine are desirable in terms of good sensitivity compatibility, but are not limited thereto. Others, for example, selenium, selenium-tellurium, selenium-arsenic, amorphous silicon, metal-free phthalocyanine, other metal phthalocyanine pigments, monoazo pigments, trisazo pigments, polyazo pigments, indigo pigments,
Slen pigments, toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments, polycyclic quinone pigments, pyrylium salts and the like can be used.

These charge generating agents may be used alone or in combination of two or more to obtain an appropriate photosensitivity wavelength and sensitizing effect.

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor in which a photosensitive layer is formed via an undercoat layer, wherein the undercoat layer is formed of a unit represented by the general formulas (I) and (II). By containing a polyimide precursor and a polyimide resin having a component, the film formability is improved, the defects such as pinholes of the conductive support are covered even in the thin film, and the barrier function and the adhesion function of the photosensitive layer are excellent. I have. The film thickness is 0.01 to 2
It is used at 0 μm, preferably 0.1 to 10 μm.

The drying temperature for forming the undercoat layer is suitably in the range of 110 ° C. to 170 ° C., and preferably 1 to 170 ° C.
30 ° C to 150 ° C is good. If the temperature is lower than 110 ° C., the undercoat layer is dissolved by the solvent, so that it cannot be applied to the photoreceptor. In addition,
When dried at 110 ° C. or higher, it does not dissolve in organic solvents. 17
If the temperature exceeds 0 ° C., the residual potential after repeated use rises, and there is a slight problem that some dust fog is generated on the image.

Further, the undercoat layer contains a polyimide precursor having a unit component represented by the general formulas [I] and [II], a polyimide resin, and titanium oxide, so that a dielectric constant of the undercoat layer is obtained. Can be increased, a thick film can be formed, and the dispersibility is also improved.

Further, the undercoat layer comprises a layer containing a polyimide precursor and a polyimide resin having the unit components represented by the general formulas [I] and [II], and a thermosetting resin or a thermoplastic resin thereon. By providing the two-layer structure of the layers, the accumulation of the residual potential can be suppressed even when the thickness of the undercoat layer is increased, and the image quality is improved.

Examples of the binder resin that can be used for forming the photosensitive layer include polycarbonate resin, styrene resin, acrylic resin, styrene-acryl resin, ethylene-vinyl acetate resin, polypropylene resin, vinyl chloride resin, and chlorinated polystyrene. Ether, vinyl chloride-vinyl acetate resin, polyester resin, furan resin, nitrile resin, alkyd resin, polyacetal resin, polymethylpentene resin, polyamide resin, polyurethane resin, epoxy resin, polyarylate resin, diallylate resin, polysulfone resin, polyether Sulfone resin, polyallyl sulfone resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin, phenol resin,
EVA (ethylene / vinyl acetate / copolymer) resin, AC
Examples include S (acrylonitrile / chlorinated polyethylene / styrene) resin, ABS (acrylonitrile / butadiene / styrene) resin, and photocurable resins such as epoxy arylate. These may be used alone or in combination of two or more. It is more preferable to use a mixture of resins having different molecular weights because the hardness and abrasion resistance can be improved.

In the electrophotographic photosensitive member of the present invention, the undercoat layer may contain titanium oxide. The titanium oxide used in the present invention may be subjected to various treatments on the surface of the titanium oxide particles as long as the volume resistance is not reduced. For example, the surface of the particles can be coated with an oxide film by using aluminum, silicon nickel or the like as a treating agent. In addition, it is possible to impart water repellency such as a coupling material as needed. The average particle diameter of titanium oxide is preferably 1 μm or less, more preferably 0.01 to 0.5 μm.
The content of titanium oxide is preferably in the range of 1 to 4 times the amount of the polyimide precursor and the polyimide resin.

Further, as the undercoat layer, a two-layer structure of a layer composed of a polyimide precursor and a polyimide resin and a layer composed of a thermosetting resin or a thermoplastic resin may be provided thereon. Examples of the thermosetting resin include epoxy resin, polyurethane, phenol, melamine / alkyd resin, and unsaturated polyester resin. Examples of the thermoplastic resin include a styrene-based elastomer, an olefin-based elastomer, a urethane-based elastomer, and a polyvinyl chloride-based elastomer. The thickness of the resin layer provided on the polyimide precursor and the polyimide layer is 0.1 to 10.0 μm
m, preferably in the range of 0.8 to 5.0 μm.

A white pigment may be contained in both or one of the two layers for the purpose of suppressing light interference during semiconductor laser exposure. For example, titanium oxide, zinc oxide, silica and the like can be mentioned.

Further, another charge transfer agent can be added to the photosensitive layer of the electrophotographic photosensitive member of the present invention. In this case, the sensitivity of the photosensitive layer can be increased or the residual potential can be reduced, so that the characteristics of the electrophotographic photosensitive member of the present invention can be improved.

Examples of charge transfer agents that can be added to improve such properties include polyvinyl carbazole, halogenated polyvinyl carbazole, polyvinyl pyrene, polyvinyl indoloquinoxaline, polyvinyl benzothiophene, polyvinyl anthracene, polyvinyl acridine,
Polyvinyl pyrazoline, polyacetylene, polythiophene, polypyrrole, polyphenylene, polyphenylene vinylene, polyisothianaphthene, polyaniline, polydiacetylene, polyheptadiene, polypyridinediyl, polyquinoline, polyphenylene sulfide, polyferrosenylene, polyperinaphthylene, polyphthalocyanine And other conductive high molecular compounds can be used.

Examples of low molecular compounds include trinitrofluorenone, tetracyanoethylene, tetracyanoquinodimethane, quinone, diphenoquinone, naphthoquinone, anthraquinone and derivatives thereof, and polycyclic aromatic compounds such as anthracene, pyrene and phenanthrene. Indole, carbazole, nitrogen-containing heterocyclic compounds such as imidazole, fluorenone, fluorene, oxadiazole, oxazole, pyrazoline, triphenylmethane, triphenylamine, enamine, stilbene, butadiene other than the above, other hydrazone compounds other than the above It can be added as a transfer agent.

As a charge transfer agent for the same purpose, a polymer solid electrolyte in which a polymer compound such as polyethylene oxide, polypropylene oxide, polyacrylonitrile and polymethacrylic acid is doped with a metal ion such as Li (lithium) ion is used. It can also be added.

Further, as a charge transfer agent for the same purpose,
An organic charge transfer complex formed of an electron-donating substance and an electron-accepting substance represented by tetrathiafulvalene-tetracyanoquinodimethane can also be used.

The desired photoreceptor characteristics can be obtained by adding only one kind of the charge transfer agent or by mixing two or more kinds of compounds.

The electrophotographic photoreceptor of the present invention can prevent the property change and the crack due to the oxidative deterioration of the photoconductive material and the binder resin,
For the purpose of improving the mechanical strength, the photosensitive layer preferably contains an antioxidant or an ultraviolet absorber.

The antioxidants which can be used in the present invention include 2,6-di-tert-butylphenol,
2,6-di-tert-4-methoxyphenol, 2-
tert-butyl-4-methoxyphenol, 2,4-
Dimethyl-6-tert-butylphenol, 2,6-
Di-tert-butyl-4-methylphenol, butylated hydroxyanisole, stearyl propionate-β
-(3,5-di-tert-butyl-4-hydroxyphenyl), α-tocopherol, β-tocopherol,
n-octadecyl-3- (3'-5'-di-tert-
Monophenolic compounds such as butyl-4'-hydroxyphenyl) propionate and 2,2'-methylenebis (6-t
tert-butyl-4-methylphenol), 4,4'-
Butylidene-bis- (3-methyl-6-tert-butylphenol), 4,4'-thiobis (6-tert-
Butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,
6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] Polyphenols such as methane and the like are preferable, and one or more of these can be simultaneously contained in the photosensitive layer.

As the ultraviolet absorber, 2- (5-
Methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-di-tert-butyl) -2-hydroxyphenyl) benzotriazole, 2- (3-ter
t-butyl-5-methyl-2-hydroxyphenyl)-
5-chlorobenzotriazole, 2- (3,5-di-t
tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-tert-
Benzotriazoles such as amyl-2-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, phenyl salicylate, and p-tert salicylate
Salicylic acids such as -butylphenyl and salicylic acid-p-octylphenyl are preferred.
More than one species can be simultaneously contained in the photosensitive layer.

Further, an antioxidant and an ultraviolet absorber can be added simultaneously. These additives may be added to any layer in the photosensitive layer, but are preferably added to the outermost surface layer, particularly to the charge transfer layer.

The antioxidant is added to the binder resin by 3
The amount is preferably 3 to 30% by weight with respect to the binder resin. Furthermore, when both an antioxidant and an ultraviolet absorber are added, the addition amount of both components is preferably 5 to 40% by weight based on the binder resin.

In addition to the above antioxidants and ultraviolet absorbers,
Light stabilizers such as hindered amines and hindered phenol compounds, anti-aging agents such as diphenylamine compounds, surfactants and the like can also be added to the photosensitive layer.

As a method for forming the photosensitive layer, a method is generally used in which a coating solution is prepared by dispersing or dissolving a predetermined photosensitive material and a binder resin in a solvent, and then applied on a predetermined substrate.

The coating method may be dip coating, curtain flow, bar coating, roll coating, ring coating, spin coating, spray coating, etc., depending on the shape of the base and the state of the coating liquid. Further, the charge generation layer can be formed by a vacuum evaporation method.

The solvent used for the coating solution is methanol,
Alcohols such as ethanol, n-propanol, i-propanol, butanol, methylcellosolve and ethylcellosolve, saturated aliphatic hydrocarbons such as pentane, hexane, heptane, octane, cyclohexane and cycloheptane, and aromatics such as toluene and xylene Group hydrocarbons, chlorinated hydrocarbons such as dichloromethane, dichloroethane, chloroform and chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran (THF) and methoxyethanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, formic acid Esters such as ethyl, propyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, N, N-dimethylformamide,
Examples include dimethyl sulfoxide and N-methyl-2-pyrrolidone. These may be used alone or as a mixture of two or more solvents.

In the undercoat layer of the present invention, an intermediate layer in which a metal compound, metal oxide, carbon, silica, resin powder and the like are dispersed in a resin can be used. Further, various pigments, an electron accepting substance, an electron donating substance, and the like can be contained for improving characteristics.

In addition, on the surface of the photosensitive layer, an organic thin film such as a polyvinyl formal resin, a polycarbonate resin, a fluorine resin, a polyurethane resin, or a silicone resin, or a siloxane structure formed of a hydrolyzate of a silane coupling agent is formed. A surface protection layer may be provided by forming a thin film, and in that case, the durability of the photoconductor is improved, which is preferable. This surface protective layer may be provided in order to improve functions other than the improvement in durability.

[0044]

Hereinafter, examples of the electrophotographic photosensitive member according to the present invention will be described in detail along with comparative examples.

Example 1 On a cylindrical drum made of aluminum having a diameter of 30 mm,
N, N- dimethylformamide 100 general formula dissolved in parts by weight (I) wherein R ₁ is dried for 30 minutes polyimide precursor at 140 ° C. of [R ₁ -1], an undercoat layer having a film thickness of 1.0μm Formed. The undercoat layer component after the formation of the photosensitive layer is represented by the general formula [I] R
₁ polyimide precursor 6 parts by weight of [R ₁ -1], the general formula [II] R ₂ is a polyimide resin [R ₂ -1] was 4 parts by weight.

Next, a dispersion of oxytitanium phthalocyanine using polyvinyl butyral as a binder resin was applied by dip coating to a thickness of 0.1 μm to form a charge generation layer.

Next, a polycarbonate copolymer as a binder resin and 1-p-dibenzylaminophenyl-1-p-diethylaminophenyl-4,4 as a charge transfer agent.
-Diphenyl-1,3-butadiene and 2,6-di-tert-butyl-4-methylphenol as an antioxidant, polycarbonate copolymer = 1.0 / 0.8 /
It was dissolved in chloroform at a weight ratio of 0.18 to prepare a coating solution.

After this coating solution was applied by dip coating, the coating solution was dried at a temperature of 100 ° C. for 1 hour to form a charge transfer layer having a thickness of 20 μm. An electrophotographic photoreceptor was manufactured in the manner described above.

Example 2 In place of the polyimide precursor and the polyimide resin in the undercoat layer of Example 1, [R _{1 of the} general formulas [1] and [II] were used.
-2] and a polyimide precursor and the polyimide resin represented by [R ₂ -2], an electrophotographic photoreceptor was prepared in the same manner as in Example 1.

Example 3 In place of the polyimide precursor and the polyimide resin in the undercoat layer of Example 1, [R ₁ ] of the general formulas [1] and [II] were used.
-3] and a polyimide precursor and the polyimide resin represented by [R ₃ -3], an electrophotographic photoreceptor was prepared in the same manner as in Example 1.

Example 4 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the undercoat layer of Example 1 was mixed with 300 parts by weight of titanium oxide particles coated with alumina, a polyimide precursor and a polyimide resin. Produced.

Example 5 On the layer composed of the polyimide precursor and the polyimide resin of Example 1, a melamine alkyd resin and a titanium oxide in a ratio of 1: 3 as a thermosetting resin were dissolved in methyl ethyl ketone to form a coating solution. An electrophotographic photoreceptor was manufactured in the same manner as in Example 1, except that the layers were laminated.

Example 6 On the layer of the polyimide precursor and the polyimide resin of Example 1, a nylon resin and a titanium oxide in a ratio of 1: 3 as a thermoplastic resin were dissolved in methanol and laminated as a coating solution. Otherwise, an electrophotographic photosensitive member was produced in the same manner as in Example 1.

Example 7 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the drying temperature of the undercoat layer in Example 1 was changed to 110 ° C.

Example 8 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the drying temperature of the undercoat layer of Example 1 was changed to 170 ° C.

Example 9 Example 1 was repeated except that the drying temperature of the undercoat layer was changed to 180 ° C.
An electrophotographic photosensitive member was manufactured in the same manner as in Example 1.

Comparative Example 1 The drying temperature of the undercoat layer of Example 1 was set at 250 ° C., and a completely imidized polyimide resin was dissolved to prepare a coating liquid. Then, an electrophotographic photosensitive member was produced in the same manner as in Example 1.

Comparative Example 2 An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that polyester was used instead of the polyimide precursor and polyimide resin of Example 1.

Comparative Example 3 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that a melamine alkyd resin was dissolved in methyl ethyl ketone to prepare a coating solution instead of the polyimide precursor and polyimide resin of Example 1. The body was made.

Evaluation Method [Measurement of Electrostatic Characteristics] Using an electrophotographic photoreceptor evaluation apparatus (manufactured by Yamanashi Electronics Co., Ltd.), the initial values of the electrophotographic photoreceptors produced in Examples 1 to 9 and Comparative Examples 1 to 3 were evaluated. Electrostatic characteristics such as surface potential, sensitivity, residual potential, and dark decay rate were measured, and all were good characteristics.

[Repeated cycle test] Room temperature and normal humidity (24
C., 40% RH), using an electrophotographic photoreceptor evaluation apparatus (manufactured by Yamanashi Electronics Co., Ltd.), the cylindrical electrophotographic photoreceptors produced in Examples 1 to 9 and Comparative Examples 1 to 3 It was charged at an applied voltage of −5 KV, and the residual potential VR (−V) when the electrophotographic photosensitive member was exposed to light having a wavelength of 780 nm and an exposure light amount of 20 erg / cm ² was measured. Table 1 shows the results.

[0062]

[Table 1]

[Image Test] Examples 1 to 9 and Comparative Examples 1 to
The cylindrical electrophotographic photoreceptor produced in 3 was manufactured using a Xerox WorkCenter 665 printer.
The electrophotographic photoreceptor is negatively charged by the scorotron charging method, mounted on an electrophotographic apparatus that performs image formation by a LD exposure, a non-magnetic 1.5 component developing method, and a blade cleaning method, and continuously prints 10,000 sheets of A4 paper. The image after continuous printing was evaluated. Table 2 shows the results. The judgment is
“○” indicates good, “Δ” is fair but slightly problematic in practical use, and “×” indicates problematic image and other problems.

[0064]

[Table 2]

As is clear from Tables 1 and 2, Example 1
The electrophotographic photoreceptors No. to No. 8 exhibited good chargeability and light fatigue characteristics both in the initial stage and after 10,000 sheets of repetition, and no image defects such as fogging occurred in images after continuous printing. In Example 9, the drying temperature of the undercoat layer was high and the state was close to imidization, the residual potential after repetition was accumulated, and some dust fog was observed on the image, which caused a problem in practice.

In addition, as understood from Examples 4 to 6, when a titanium oxide was mixed with a polyimide precursor and a polyimide resin, or when a thermosetting resin or a thermoplastic resin was laminated on the polyimide precursor layer. Good results were obtained in all cases.

On the other hand, the electrophotographic photoreceptor of Comparative Example 1 had a large residual potential when only the polyimide resin was used.
Accompanying this, the image after continuous printing had many black spots on a white ground, white spots on a black ground, and streak-like defects, and a decrease in density was also observed.
In Comparative Examples 2 and 3, when a conventional polyester resin / melamine alkyd resin was used, residual potential was accumulated, and dust fog occurred on the image.

[0068]

The electrophotographic photoreceptor of the present invention has a very small residual potential without being affected by electrostatic properties such as surface potential and sensitivity, has no image defects at all, and has a repetition stability. Is also strong. Therefore, according to the present invention, it is possible to provide an electrophotographic photoreceptor having excellent electrophotographic properties, cleaning properties, and oil resistance and capable of simplifying maintenance.

Continued on the front page (72) Inventor Toshihiko Koizumi 1014 Miyahara-cho, Kofu City, Yamanashi Prefecture Inside Yamanashi Electronics Co., Ltd. (72) Inventor Masaki 1014 Miyahara-cho, Kofu City, Yamanashi Prefecture Inside Yamanashi Electronics Co., Ltd. (72 ) Inventor Ryoji Kobayashi 1014 Miyahara-cho, Kofu-shi, Yamanashi F-term in Yamanashi Electronics Co., Ltd.

Claims (5)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer formed on a conductive support via an undercoat layer, wherein the undercoat layer has the general formula [I]: [Wherein, R ₁ is a tetravalent aromatic hydrocarbon group, R ₂ is a divalent polycyclic aromatic group in which aromatic rings may be linked by different atoms, and n is an integer representing the degree of polymerization. It is. And a main component is a polyimide precursor having a unit component represented by the general formula [II]: [Wherein, R ₁ is a tetravalent aromatic hydrocarbon group, R ₂ is a divalent polycyclic aromatic group in which aromatic rings may be linked by different atoms, and n is an integer representing the degree of polymerization. It is. An electrophotographic photoreceptor comprising a polyimide resin represented by the following formula: 2. The method according to claim 1, wherein the undercoat layer comprises the polyimide resin in an amount of 20% to 20% of the total weight of the polyimide resin and the polyimide precursor.
2. The electrophotographic photoreceptor according to claim 1, comprising 70%. 3. The drying temperature for forming the undercoat layer is 11
The temperature is in the range of 0 ° C to 170 ° C.
Or the electrophotographic photosensitive member according to 2. 4. The electrophotographic photoconductor according to claim 1, wherein the undercoat layer further contains titanium oxide. 5. The undercoat layer according to claim 1, wherein the undercoat layer has a two-layer structure of a layer containing a polyimide precursor and a polyimide resin and a layer made of a thermosetting resin or a thermoplastic resin thereon. 5. The electrophotographic photosensitive member according to any one of items 1 to 4,