JP4688506B2 - Electrophotographic photosensitive member, image forming apparatus using the same, and process cartridge - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member, and more specifically, an electrophotographic photosensitive member that prevents image defects caused by intergranular corrosion caused by iron and copper contained in an aluminum support, and an image forming apparatus using the same. And a process cartridge.

Electrophotographic photoreceptors are used in various devices such as copying machines, printers, and facsimile machines. As seen in recent examples of electrophotographic copying machines, high speed and high durability are required for repeated use over a long period of time. There is a need for a highly reliable electrophotographic photoreceptor that can maintain image quality.
In general, when an electrophotographic photoreceptor is used repeatedly, it has technical problems such as various problems such as a decrease in chargeability, a deterioration in image characteristics, and a decrease in adhesion between the photosensitive layer and the support. Various countermeasures have been proposed to deal with various problems.

For example, by providing a first intermediate layer mainly composed of a resin and a second intermediate layer mainly composed of an inorganic pigment and a binder resin between the conductive support and the photoconductive layer, A method for stabilizing the potential of the electrophotographic photosensitive member has been proposed (see, for example, Patent Document 1).
According to this proposal, a decrease in charging performance at low humidity or high humidity is suppressed, but there is no description on the effectiveness in preventing the occurrence of image defects due to intergranular corrosion of the conductive support.

Alternatively, the relationship between the surface roughness Rmax of the conductive substrate and the thickness L of the undercoat layer satisfies Rmax / L ≦ 4, and the undercoat layer is composed mainly of a copolymerized polyamide, ie, copolymerization. There has been proposed a method for preventing image defects of the electrophotographic photoreceptor and improving the stability of the potential by setting polyamide / methoxymethylated nylon = 2/8 to 4/6 (for example, patents). Reference 2).
According to this proposal, the image defects, potential stability and environmental stability in the initial stage of the electrophotographic photoreceptor are improved, but the occurrence of image defects due to intergranular corrosion of the conductive substrate during repeated use is prevented. There is no description about the effectiveness against the above, and with this configuration, it is difficult to cope with image defects caused by intergranular corrosion of the conductive substrate.

In addition, a non-conductive titanium oxide particle and a polyamide resin were applied on a conductive support using a solution in which a mixed solvent composed of a chlorine solvent was dispersed, and the content of titanium oxide particles was 80 to 99% by weight. A method of maintaining repetitive stability and good image characteristics by controlling the film thickness to 0.5 to 4.8 μm, forming an undercoat layer, and further providing a recording layer to form an electrophotographic photoreceptor. It has been proposed (see, for example, Patent Document 3).
According to this proposal, an effect of suppressing image defects due to a decrease in charging property and an increase in residual potential during repeated use is expected. However, since titanium oxide particles have low dispersion stability in an alcohol solvent, and particularly when the content is 80 to 99% by weight, aggregation of titanium oxide particles is likely to occur. Therefore, an undercoat layer formed using this solution is used. When used for a long time, there is a problem that coating film defects occur and it becomes difficult to obtain good image characteristics. Furthermore, alcohol and chlorine solvents are used to dissolve the polyamide resin used for the undercoat layer, which is a problem for environmental measures.

Also, an electrophotographic photosensitive member in which a cured layer of an inorganic pigment, an alkyd resin, and a melamine resin is provided on a conductive substrate, a polyamide resin layer is further provided thereon, and a photoconductive layer is further provided thereon. Thus, there has been proposed a method that enables stable image formation over a long period of time without causing deterioration of the characteristics of the photoreceptor (see, for example, Patent Document 4).
According to this proposal, a certain effect of preventing deterioration of the characteristics of a photoreceptor having an intermediate layer in which an inorganic pigment is dispersed in a resin can be expected. However, as a polyamide-based resin, copolymer nylon (for example, CM8000: registered trademark) Is used. For this reason, there is a problem that the dependence on the environment is large, and the increase in the residual potential is particularly large in repeated use under low temperature and low humidity. In addition, since a polyamide-based resin is provided on the cured layer of an inorganic pigment, an alkyd resin, and a melamine resin, it is difficult for electrons to be injected into the conductive substrate during exposure of the electrophotographic photoreceptor, and after exposure during repeated use There is a drawback that the potential tends to rise.

Alternatively, an undercoat layer containing a binder resin mainly composed of methoxymethylated nylon cross-linked with an inorganic pigment and a photosensitive layer are laminated on a conductive support, and the wear rate of the outermost layer of the photoconductor By configuring the electrophotographic photosensitive member so that (amount of wear on the outermost layer / traveling distance of the photosensitive member) is 1.50 × 10 ⁻¹¹ or less, the abrasion resistance is improved and the durability is improved, that is, long There has been proposed a method that enables image formation without image density reduction and occurrence of abnormal images such as background stains even after repeated use (for example, see Patent Document 5).
According to this proposal, although it is possible to improve wear resistance and durability, acids such as tartaric acid added to crosslink methoxymethylated nylon remain in the undercoat layer on the conductive support. Therefore, there is a problem that problems such as sensitivity fluctuations occur during long-term storage of the photoreceptor.

JP-A 63-289554 JP-A-5-323645 Japanese Patent No. 2885609 JP-A-9-288367 JP 2002-131936 A

  The present invention has been made in view of the above prior art, and in a photoconductor provided with an aluminum support containing 0.3 wt% or more of iron and copper as a conductive substrate, aluminum can be used repeatedly. There is no occurrence of image defects such as black spots and white spots due to intergranular corrosion of the support or coating layer defects of the constituent layers on the support, and the deterioration of the charging performance is suppressed, so that fine granular background stains are prevented. Providing a highly reliable electrophotographic photosensitive member that is stable and has a stable potential after exposure of the photosensitive member during long-term storage, and is small in size and reproduces halftones and line images using the electrophotographic photosensitive member. It is an object of the present invention to provide an image forming apparatus satisfying the characteristics or solid portion density, and a process cartridge that can be attached to and detached from the main body of the image forming apparatus.

As a result of intensive studies, the inventors of the present invention have made an electrophotographic photosensitive member, an aluminum conductive support containing 0.3 wt% or more of iron and copper (hereinafter abbreviated as an aluminum support), a photosensitive layer, and the like. Between, a resin layer made of methoxymethylated nylon, and an undercoat layer made of an inorganic pigment and a thermosetting resin are provided in this order from the support side , and the residual solvent in the undercoat layer is 10 to 1000 ppm , The inventors have found that the above problems can be solved and have reached the present invention. Hereinafter, the present invention will be specifically described.

That is, the present invention is an electrophotographic photoreceptor having at least a photosensitive layer on an aluminum support containing 0.3 wt% or more of iron and copper in total.
Between the aluminum support and the photosensitive layer, a resin layer made of methoxymethylated nylon and an undercoat layer made of an inorganic pigment and a thermosetting resin are sequentially provided from the support side ,
The electrophotographic photoreceptor, wherein the residual solvent in the undercoat layer is 10 to 1000 ppm .
Here, the total content of iron and copper is preferably 0.3 to 10 wt%.

The electrophotographic photosensitive member according to any one of the above, wherein the aluminum support has a surface roughness (Rz) of 0.2 to 1.5 μm and a film thickness (d) of a resin layer made of methoxymethylated nylon. Is preferably 0.5 to 1.5 μm .

  Furthermore, in any of the above electrophotographic photoreceptors, the thermosetting resin in the undercoat layer is composed of an alkyd resin and a melamine resin, and the ratio of the inorganic pigment (P) to the thermosetting resin (R) ( P / R) is preferably 4/1 to 9/1 by weight ratio.

In the present invention, a charging unit, a developing unit, a transfer unit, and a cleaning unit are disposed around the electrophotographic photosensitive member, and at least one of the units abuts on the electrophotographic photosensitive member. An image forming apparatus comprising:
The electrophotographic photoreceptor is an image forming apparatus according to any one of the above-described electrophotographic photoreceptors.

Further, the present invention relates to a process cartridge in which an electrophotographic photosensitive member, a charging unit, a developing unit, and a cleaning unit are integrally supported and are detachable from the image forming apparatus main body.
The electrophotographic photosensitive member is a process cartridge according to any one of the above-described electrophotographic photosensitive members.

An aluminum support (support and support) containing a resin layer made of methoxymethylated nylon and an undercoat layer made of an inorganic pigment and a thermosetting resin in this order in a total of 0.3 wt% or more of iron and copper. Omitted ), and the residual solvent in the undercoat layer is 10 to 1000 ppm, thereby preventing the occurrence of image defects such as black spots and white spots caused by iron and copper in the support. At the same time, the occurrence of minute granular soiling during repeated use is prevented. Furthermore, the potential after exposure to the photoreceptor during long-term storage is stabilized. Here, if the total content of iron and copper is 0.3 to 10 wt%, mechanical strength and machinability can be obtained, and thin film weight can be reduced.
In addition, by controlling the surface roughness (Rz) of the support and the film thickness (d ) of Rz and the resin layer, the adhesion between the support and the resin layer is improved, resulting in coating film defects during repeated use. Occurrence of image defects (black spots, white spots, etc.) due to this is prevented.
Further, an alkyd resin and a melamine resin are used as the thermosetting resin composition for the undercoat layer, and the weight ratio (P / R) of the inorganic pigment (P) to the thermosetting resin (R) is 4/1 to 9/1. By controlling so as to prevent a decrease in charge during repeated use .
By adopting an apparatus configuration in which at least one charging unit, developing unit, transfer unit, or cleaning unit is disposed around the electrophotographic photosensitive member, downsizing and image quality requirements (halftone, line, etc.) are achieved. An image forming apparatus that satisfies image reproducibility, solid portion density, and the like is provided. In addition, by using a process cartridge that integrally supports the electrophotographic photosensitive member, the charging unit, the developing unit, and the cleaning unit, the unit can be reduced in size, operability, workability (attachment / removal), and the like. .

As described above, the electrophotographic photoreceptor of the present invention includes a resin layer made of methoxymethylated nylon between an aluminum support containing 0.3 wt% or more of iron and copper and a photosensitive layer, and an inorganic pigment. It is characterized by comprising an undercoat layer made of a thermosetting resin in order from the support side.
Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing a configuration example of an electrophotographic photosensitive member according to the present invention.
As shown in FIG. 1, the electrophotographic photoreceptor of the present invention has a structure in which a resin layer 2, an undercoat layer 3, a charge generation layer 4, and a charge transport layer 5 are sequentially laminated on an aluminum support 1 that is a conductive substrate. Become. In the example of FIG. 1, a photosensitive layer 6 is constituted by the charge generation layer 4 and the charge transport layer 5. In the layer configuration of FIG. 1, a protective layer can be further provided on the charge transport layer as necessary.

As the aluminum support 1, aluminum containing iron and copper is used, and in particular, those having a total content of iron and copper of 0.3 wt% or more, such as JIS 3003 and JIS 5052, are used. Aluminum is used.
These aluminum containing 0.3 wt% or more of iron and copper have superior mechanical strength under the same heat treatment conditions as compared with those containing less impurities such as JIS 1070. It has the advantage of being possible. However, the presence of metal impurities such as iron and copper in aluminum tends to cause intergranular corrosion. In the intergranular corrosion portion, the injection of electric charge from the aluminum support to the photosensitive layer side is likely to occur, and there is a problem that black spots, fine granular soiling, etc. occur due to repeated use of the photosensitive member.
As described above, if the total content of iron and copper in aluminum is 0.3 wt% or more, the mechanical strength necessary for reducing the weight of the thin film can be obtained. In particular, the total content of iron and copper is 0.00. It is preferable that it is 3-10 wt%. If it exceeds 10 wt%, the machineability such as extrusion, impact machining, and surface cutting will be affected, making it difficult to reduce the weight of the thin film. The surface roughness (Rz) of the aluminum support is preferably 0.2 to 1.5 μm in consideration of workability, moire due to reflection of the support, and the like.

In the present invention, it is possible to prevent the occurrence of image defects such as black spots, white spots, and fine granular background stains by adopting the configuration shown in FIG.
That is, the methoxymethylated nylon used for the resin layer 2 shown in FIG. 1 is provided to prevent charge injection from the aluminum support to the photosensitive layer side and to stabilize the charged potential of the photoreceptor.
The methoxymethylated nylon used is not limited. For example, it is obtained by reacting 6-nylon with formaldehyde and methanol to methoxymethylate, and the reaction catalyst is phosphoric acid, sodium phosphate, etc. Further, ammonia or the like is used for the neutralization treatment. After the reaction, those washed with water and dried are used, but chlorine ions, nitrate ions, ammonium ions, etc. remain in the resin, and their amounts are 100 to 300 ppm for anions and about 100 ppm for cations. It is. This residual ion reduces the environmental dependence of methoxymethylated nylon. The methoxymethylation degree is preferably 10 to 40%, and the polymerization degree is preferably 100 to 500.

  The film thickness of the resin layer 2 is preferably 0.5 to 1.5 μm. Here, the surface roughness (Rz) of the aluminum support and the ratio (Rz / d) of the film thickness (d) of the resin layer comprising (Rz) and methoxymethylated nylon are 0.3 to 2. Preferably, by controlling in this way, the adhesion between the aluminum support and the resin layer can be improved, and the resin layer can be uniformly applied to the surface of the support, resulting from coating film defects during repeated use. Generation of image defects such as black spots and white spots can be prevented.

  The methoxymethylated nylon used for the resin layer 2 is dissolved and applied in an alcohol solvent such as methanol, ethanol, propanol, and isobutanol. Furthermore, the coating liquid for forming a resin layer can be stabilized by adding 0.5-30 wt% of water in a solvent.

The undercoat layer 3 is provided for the purpose of preventing charge injection from the aluminum support side, improving adhesion, preventing moire, improving the coatability of the upper layer (charge generation layer 4 in FIG. 1), and reducing residual potential. It is done.
The undercoating layer 3 is a fine particle comprising a thermosetting resin and a metal oxide exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide, or the like, or an inorganic pigment such as metal sulfide or metal nitride. The powder can be formed by using a coating liquid prepared by dispersing and preparing a powder by using a ball mill, a sand mill, an attritor or the like, as appropriate, alone or in combination of two or more.

  As the inorganic pigment, high-purity titanium oxide is particularly preferable. The solvent for dispersing the inorganic pigment is preferably a ketone solvent, particularly cyclohexanone, cyclohexanol, methyl ethyl ketone, or methyl isobutyl ketone, in view of the solubility of the resin and the dispersibility of the inorganic pigment. By using these solvents, it is possible to disperse the inorganic pigment to the primary particle size and produce a uniform coating solution free from aggregates.

As the resin used for the undercoat layer 3, considering that the photosensitive layer 6 provided on the undercoat layer is applied and formed using a solvent, a resin having high resistance to a general organic solvent, for example, Thermal polymerization of a compound containing a plurality of active hydrogens (hydrogen such as —OH group, —NH ₂ group, —NH group, etc.) and a compound containing a plurality of isocyanate groups and / or a compound containing a plurality of epoxy groups The thermosetting resin made is illustrated.
Here, examples of the compound containing a plurality of active hydrogens include acrylic resins containing active hydrogen such as polyvinyl butyral, phenoxy resin, phenol resin, polyamide, polyester, and hydroxyethyl methacrylate group. Examples of the compound containing a plurality of isocyanate groups include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and prepolymers thereof. Examples of the compound having a plurality of epoxy groups include bisphenol A type epoxy resin. Can be mentioned. In particular, a thermosetting resin obtained by thermally polymerizing an alkyd resin and an amino resin, for example, an alkyd resin (for example, an oil-free alkyd resin) and a melamine resin (for example, a butylated melamine resin) is preferable.

  Formation of the undercoat layer 3 on the resin layer provided on the aluminum support can be performed by a roll coating method, a dip coating method, a spray coating method, a nozzle coating method, a blade coating method or the like using a coating solution. it can. After applying the coating liquid, the formed coating film is cured by drying or heating. The thickness of the undercoat layer 3 is suitably 0.1 to 20 μm, preferably 0.2 to 10 μm.

  By controlling the ratio (P / R) of the inorganic pigment (P) and the thermosetting resin (R) used for the undercoat layer 3 to 4/1 to 9/1 (weight ratio), the charge is reduced during repeated use. Can be prevented. In particular, it is preferable to use an alkyd resin and a melamine resin as the thermosetting resin in the composition. Here, when P / R is less than 4/1, the effect of preventing a decrease in charge during repeated use is small. On the other hand, when P / R exceeds 1 to 9/1, there is little effect for preventing the occurrence of minute granular soiling during repeated use.

  Further, the undercoat layer is formed by coating with a coating liquid in which an inorganic pigment and a thermosetting resin are dispersed in a ketone solvent, the drying conditions of the coating film are adjusted as appropriate, and the residual solvent in the undercoat layer is 10 to 10. By setting it to 1000 ppm, it is possible to prevent the occurrence of coating film defects and minute granular ground stains during repeated use, and it is possible to stabilize the potential after exposure of the photoreceptor during long-term storage.

  Next, the charge generation layer 4 is a layer mainly composed of a charge generation material, and a binder resin (binder-resin) can be used as necessary. As the charge generation substance, an inorganic material or an organic material can be used.

  Examples of inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, and selenium-arsenic compounds.

On the other hand, a known material can be used as the organic material.
For example, phthalocyanine pigments such as metal-free phthalocyanine and metal phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having a carbazole skeleton, azo pigments having a triphenylamine skeleton, azo pigments having a diphenylamine skeleton, dibenzo An azo pigment having a thiophene skeleton, an azo pigment having a fluorenone skeleton, an azo pigment having an oxadiazol skeleton, an azo pigment having a bisstilbene skeleton, an azo pigment having a distyryl oxadiazol skeleton, and a distyrylcarbazole skeleton Azo pigment, perylene pigment, anthraquinone or polycyclic quinone pigment, quinoneimine pigment, diphenylmethane and triphenylmethane pigment, benzoquinone and naphthoquinone pigment, cyanine and azomethine face , Indigoid pigments, bisbenzimidazo - such as Le based pigments. These charge generation materials can be used alone or as a mixture of two or more. For example, the various azo pigments may contain one or more other various pigments.

  Examples of the binder resin used for the charge generation layer 4 include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, and polyvinyl formal. , Polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide and the like. These binder resins can be used alone or as a mixture of two or more.

If necessary, a charge transport material may be added to the binder resin used for the charge generation layer 4. In addition to the binder resin described above, a polymer charge transport material is preferably used as the binder resin for the charge generation layer.
In this case, the ratio of the charge generation material and the resin of the charge generation layer is preferably 1/1 to 3/1 in weight ratio, and thus the adhesiveness between the photosensitive layer and the undercoat layer can be improved. And the post-exposure potential can be stabilized.

As a method of forming the charge generation layer 4, a casting method from a solution dispersion system can be mainly used. In order to provide the charge generation layer by the casting method, the above inorganic or organic charge generation material may be used together with a binder resin, if necessary, using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, ball mill, attritor. It can be formed by dispersing with a sand mill or the like and applying the prepared dispersion after appropriately diluting it. The coating can be performed by a dip coating method, spray coating, bead coating or the like.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

  Next, the charge transport layer 5 is a layer intended to hold a charged charge and to couple the charge generated and separated in the charge generation layer 4 by exposure to the charged charge held by movement. Further, the charge transport layer 5 is required to have a high electric resistance in order to achieve the purpose of holding a charged charge, and in order to achieve a high surface potential in the held charged charge, a dielectric constant is required. Is required to be small and have good charge mobility.

  The charge transport layer 5 for satisfying the above requirements is a coating prepared by dissolving a charge transport material and a binder resin in a cyclic ether solvent such as tetrahydrofuran, tetrahydropyran, 1,4-dioxane, dioxolane, toluene, and dimethoxymethane. It is formed by applying a working solution on the charge generation layer 4. By using a cyclic ether solvent, the adhesion between the photosensitive layer and the support or the undercoat layer can be improved. The amount of residual cyclic ether solvent in the charge transport layer is preferably 20 to 5000 ppm. If it is less than 20 ppm, the adhesion to the support or the undercoat layer is lowered, and if it exceeds 5000 ppm, the potential increases after exposure of the photoreceptor.

  If necessary, an appropriate amount of a plasticizer, an antioxidant, a leveling agent and the like can be added to the coating liquid in addition to the charge transport material and the binder resin. In addition, chlorinated solvents such as dichloromethane, chloroform, monochlorobenzene, trichloroethane, and trichloromethane are avoided from the environmental aspect.

Examples of the charge transport material used in the charge transport layer include a hole transport material and an electron transport material.
Examples of the electron transport material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2, 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4-one, 1,3,7-tri Examples thereof include electron accepting substances such as nitrodibenzothiophene-5,5-dioxide. These electron transport materials can be used alone or as a mixture of two or more. In addition, antioxidants such as monophenol compounds other than hydroquinone compounds, polymer phenol compounds, paraphenylenediamines, organic sulfur compounds, and organic phosphorus compounds may be used in combination.

  Examples of the paraphenylenediamines include N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl- Examples thereof include p-phenylenediamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine, and the like. Examples of organic sulfur compounds include dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate, and the like. Examples of the organic phosphorus compounds include triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

  Examples of the hole transporting material include the following electron donating materials, which are used favorably. For example, oxazole derivatives, oxadiazol derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene , Styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazol derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, and the like. These hole transport materials can be used alone or as a mixture of two or more. The thickness of the charge transport layer is suitably about 5 to 100 μm.

  As binder resins that can be used in the charge transport layer, polycarbonate (bisphenol A type, bisphenol Z type), polyester, methacrylic resin, acrylic resin, polyethylene, vinyl chloride, vinyl acetate, polystyrene, phenol Resin resin, epoxy resin, polyurethane, polyvinylidene chloride, alkyd resin, silicon resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, polyacrylate, polyacrylamide, phenoxy resin and the like are used. These binders can be used alone or as a mixture of two or more. The thickness of the charge transport layer is suitably about 5 to 100 μm.

  Moreover, as a plasticizer used as needed, what is generally used as a plasticizer, such as dibutyl phthalate, dioctyl phthalate, and a bisbenzylbenzene derivative, can be used as it is, and the amount used is 0 with respect to 100 parts by weight of the binder resin. About 30 parts by weight is appropriate.

Furthermore, what is illustrated below is used as antioxidant.
[Monophenol compound]: 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate, 3-t-butyl-4-hydroxynisol and the like.
[Bisphenol compounds]: 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4, 4'-thiobis- (3-methyl-6-t-butylphenol), 4,4'-butylidenebis- (3-methyl-6-t-butylphenol) and the like.
[High molecular phenolic compound]: 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] methane, bis [3 , 3′-bis (4′-hydroxy-3′-t-butylphenyl) butyric acid] glycol ester, tocophenols and the like.
[Paraphenylenediamines]: N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylene Diamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.
[Hydroquinones]: 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2 -(2-octadecenyl) -5-methylhydroquinone and the like.
[Organic sulfur compounds]: Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.
[Organic phosphorus compounds]: triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

  A leveling agent may be added to the charge transport layer. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers having a perfluoroalkyl group in the chain, or oligomers are used, and the amount used is 100 parts by weight of the binder resin. 0 to 1 part by weight is appropriate.

Further, a protective layer may be provided on the charge transport layer. The protective layer is a layer formed by dispersing fine particles of metal or metal oxide in a binder resin.
As the binder resin for the protective layer, a resin that is transparent to visible and infrared light and excellent in electrical insulation, mechanical strength, and adhesiveness is desirable. Examples of the binder resin include ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, poly Butylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polychlorinated Examples thereof include resins such as vinylidene and epoxy resins.
On the other hand, examples of the metal oxide include titanium oxide, tin oxide, potassium titanate, TiO, TiN, zinc oxide, indium oxide, and antimony oxide.

  In addition to the protective layer, a fluorine resin such as polytetrafluoroethylene, a silicone resin, and those obtained by dispersing an inorganic material in these resins may be added for the purpose of improving wear resistance. As a method for forming the protective layer, a normal coating method is employed. In addition, about 0.1-10 micrometers is suitable for the thickness of a protective layer.

Next, an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 2 is a schematic configuration diagram schematically showing an example of the electrophotographic apparatus according to the present invention.
In FIG. 2, reference numeral 11 denotes an electrophotographic photosensitive member (photosensitive drum) of the present invention. Around the photosensitive drum, a charging means (contact charging device) 12, a developing means 14, a transfer means (contact transfer means) 16 are provided. The apparatus is provided with a cleaning means 17.
In the case of this apparatus configuration, the photosensitive drum 11 is first charged by the contact charging device 12. After the photosensitive drum is charged, it receives image exposure 13 by laser light, and an electric charge is generated in the exposed portion, so that an electrostatic latent image is formed on the surface of the photosensitive drum. After forming an electrostatic latent image on the surface of the photosensitive drum 11, the toner image is formed by contacting the developer via the developing unit 14. The toner image formed on the surface of the photosensitive drum 11 is transferred to the transfer member 15 such as paper by the contact transfer unit 16 and passes through the fixing unit 19 to be a hard copy. Residual toner on the photosensitive drum 11 is removed by a cleaning unit 17 including a cleaning blade, and residual charges are removed by a neutralizing unit 18, and the next electrophotographic cycle is started.
The contact transfer means 16 is made of a material such as semiconductive foamed polyurethane and is devised so that the toner image can be efficiently transferred to the transfer member 15. Resin rollers (not shown) are provided at both ends in the longitudinal direction of the contact transfer means 16 in order to make the contact pressure with the photosensitive drum 11 constant. This roller may come into contact with the photosensitive layer at both ends in the longitudinal direction of the photosensitive drum 11. In particular, when the charge transport layer end is in contact with the roller, the charge generation layer resin type provided between the undercoat layer and the charge transport layer, or when the charge generation layer does not contain a resin, the charge transport layer end However, it peels off due to repeated use of the photosensitive drum 11.
With the above configuration, it is possible to provide an image forming apparatus that is small and satisfies the requirements of halftone, line image reproducibility, solid portion density, and the like.

  The image forming apparatus of the present invention constitutes a process cartridge in which a charging unit, a developing unit, a cleaning unit, and the like are integrated. That is, the electrophotographic photosensitive member of the present invention, the charging unit, the developing unit, and the cleaning unit are integrally supported so that the unit can be attached to and detached from the image forming apparatus main body. It becomes possible to be simple.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to this. Hereinafter, “parts” indicates parts by weight.

Example 1
φ30 mm, length 340 mm, thickness 0.75 mm, surface roughness (Rz) 1.1 μm JIS 3003 aluminum support (Fe: 0.7 wt%, Cu: 0.2 wt% contained), ie, aluminum drum A resin layer, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially formed on the surface in the following order to produce the electrophotographic photoreceptor of Example 1.

[Formation of resin layer]
First, dip coating was performed on an aluminum drum using a resin solution prepared according to the following composition, followed by drying at 130 ° C. for 10 minutes to form a resin layer having a thickness of 0.5 μm.
<Composition of resin solution>
Methoxymethylated nylon (FR-101: manufactured by Lead City) 10.9 parts Methanol 104.4 parts Butanol 28.9 parts Ion-exchanged water 14.9 parts

  As a result of analysis by ion chromatography, the amount of ions in methoxymethylated nylon (FR-101) was 150 ppm, 50 ppm, and 90 ppm for chlorine ion, nitrate ion, and ammonium ion, respectively.

[Formation of undercoat layer]
Subsequently, a mixture having the following composition was placed in a ball mill pot, and ball milled for 120 hours using an alumina ball having a diameter of 10 mm to prepare a milling solution for the undercoat layer.
<Composition of milling liquid for undercoat layer>
Titanium oxide (CR-60: manufactured by Ishihara Sangyo) 60 parts Alkyd resin (Beckolite M6401-50:
Dainippon Ink & Chemicals, Inc .; solid content 50 wt%) 18.5 parts Melamine resin (Super Becamine L-121-60:
Dainippon Ink & Chemicals, Inc .; solid content 60 wt%) 10.3 parts Methyl ethyl ketone (Kanto Chemical) 21 parts Cyclohexanone (Kanto Chemical) 9 parts

The prepared milling solution was dip-coated on a resin layer formed on an aluminum drum and dried at 130 ° C. for 20 minutes to form an undercoat layer having a thickness of 3.5 μm.
The average particle diameter of the titanium oxide in the milling solution was 0.39 μm as measured by a centrifugal particle size distribution analyzer (CAPA700: manufactured by Horiba, Ltd.).

[Formation of charge generation layer]
Next, a mixture of 2 parts of a charge generating material represented by the following chemical formula (I) and 60 parts of a polyvinyl butyral resin (BX-1: manufactured by Sekisui Chemical) with a solid content concentration of 2 wt% is placed in a ball mill pot. Then, ball milling was performed for 24 hours using a YTZ ball having a diameter of 2 mm to prepare a charge generation layer coating solution.
This coating solution was dip-coated on the formed undercoat layer and dried at 95 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.1 μm.

[Formation of charge transport layer]
Next, a charge transport layer coating solution is prepared with the following composition, and this coating solution is dip-coated on the charge generation layer formed above, dried at 135 ° C. for 25 minutes, and a charge transport layer having a thickness of 31 μm. Formed.
<Composition of coating solution for charge transport layer>
Charge transport material (the following chemical formula (II): manufactured by Ricoh) 7 parts Polycarbonate resin (TS-2050: manufactured by Teijin Chemicals) 10 parts Silicone oil (KF-50: manufactured by Shin-Etsu Chemical) 0.002 parts Tetrahydrofuran (manufactured by Kanto Chemical) 77 .4 parts

(Example 2)
In Example 1, the surface roughness (Rz) of the aluminum drum was changed from 1.1 μm to 0.75 μm, and the thickness of the resin layer was changed from 0.5 μm to 0.8 μm. Thus, an electrophotographic photosensitive member of Example 2 was produced.

(Example 3)
In Example 1, the surface roughness (Rz) of the aluminum drum was changed from 1.1 μm to 1 μm, and the film thickness of the resin layer was changed from 0.5 μm to 1 μm to form a resin layer.
Subsequently, a mixture having the following composition was placed in a ball mill pot and ball milled for 96 hours using φ10 mm alumina balls to prepare a milling solution for the undercoat layer.
<Composition of milling liquid for undercoat layer>
Titanium oxide (CR-60: manufactured by Ishihara Sangyo) 60 parts Alkyd resin (Beckolite M6401-50:
Dainippon Ink & Chemicals, Inc .; solid content 50 wt%) 12 parts Melamine resin (Super Becamine G821-60:
Dainippon Ink & Chemicals, Inc .; solid content 60 wt%) 6.7 parts Methyl ethyl ketone (Kanto Chemical) 21 parts Cyclohexanone (Kanto Chemical) 9 parts

  The charge generation layer was prepared in the same manner as in Example 1 except that the prepared milling solution was dip-coated on the resin layer and dried at 130 ° C. for 25 minutes to form an undercoat layer having a thickness of 3.5 μm. A charge transport layer was formed, and an electrophotographic photosensitive member of Example 3 was produced.

Example 4
In Example 3, the surface roughness (Rz) of the aluminum drum was changed from 1 μm to 0.6 μm, and the film thickness of the resin layer was changed from 1 μm to 0.75 μm. An electrophotographic photoreceptor was prepared.

(Example 5)
An electrophotographic photosensitive member of Example 5 was produced in the same manner as in Example 3 except that the surface roughness (Rz) of the aluminum drum was changed from 1 μm to 0.1 μm in Example 3.

(Example 6)
In Example 1, the composition of the milling liquid for the undercoat layer was changed to the following composition and ball milled for 96 hours.
<Composition of milling liquid for undercoat layer>
Titanium oxide (CR-60: manufactured by Ishihara Sangyo) 60 parts Alkyd resin (Beckolite M6401-50:
Dainippon Ink & Chemicals, Inc .; solid content 50 wt%) 7.2 parts Melamine resin (Super Becamine L-121-60:
Dainippon Ink & Chemicals, Inc .; solid content 60 wt%) 4 parts Methyl ethyl ketone (Kanto Chemical) 21 parts Cyclohexanone (Kanto Chemical) 9 parts

  The charge generation layer and the charge were exactly the same as in Example 1 except that the prepared milling solution was dip-coated on the resin layer and dried at 130 ° C. for 25 minutes to form an undercoat layer having a thickness of 3.5 μm. A transport layer was formed, and an electrophotographic photosensitive member of Example 6 was produced.

(Comparative Example 1)
An electrophotographic photosensitive member of Comparative Example 1 was produced in the same manner as in Example 1 except that the resin layer was not provided in Example 1.

(Comparative Example 2)
An electrophotographic photosensitive member of Comparative Example 2 was produced in the same manner as in Example 1 except that the undercoat layer was not provided in Example 1.

(Comparative Example 3)
In Example 3, the JIS 3003 series aluminum drum was changed to the JIS 1080 series (Fe: 0.15 wt%, Cu: 0.03 wt% contained) aluminum drum, the resin layer was not provided, and the undercoat layer was dip coated. An electrophotographic photosensitive member of Comparative Example 3 was produced in the same manner as in Example 3 except that it was dried at 130 ° C. for 20 minutes.

(Comparative Example 4)
An electrophotographic photosensitive member of Comparative Example 1 was produced in the same manner as in Example 1 except that the drying condition of the undercoat layer was changed to 10 minutes at 120 ° C. in Example 1.

For each of the electrophotographic photoreceptors prepared in Examples 1 to 6 and Comparative Examples 1 to 4, a unit in which the developing roller of the digital copying machine of reversal development type (IMAGIO 250 manufactured by Ricoh) was removed and the probe of the electrometer was attached The initial charging potential and the post-exposure potential were measured, and the image quality, that is, the reproducibility of granular ground stains and fine lines was evaluated.
The electrophotographic photoreceptors of Examples 1 to 6 and Comparative Examples 1 to 3 were stored for 6 months in an environment of 50 ° C., and then attached to the digital copying machine of the reversal development system, and charged potential and exposure. The post-potential was measured. In addition, 40,000 copies at room temperature and humidity, and 50,000 copies at 30 ° C, 85%, and 10 ° C, 15%, 50,000 copies each, for a total of 50,000 copies. The charging potential and post-exposure potential were measured, and the image quality (granular background stains, fine line reproducibility) was also evaluated. These results are shown in Table 1 below. For Comparative Example 4, only the initial characteristics were measured.
The evaluation of the black spots was made by measuring the size and number of black spots using a color image processor SPICCA (manufactured by Nippon Avionics Co., Ltd.) and judging the number of black spots with a diameter of 0.05 mm or more (per 1 cm ² ). The criteria for black spot evaluation are shown in Table 2 below. In the determination of Table 2, ○, ○, and Δ indicate that there is no practical problem, and × indicates that it is not suitable for practical use. Moreover, the reproducibility of the fine line was evaluated from a one-dot line image.
On the other hand, using the milling solution for the undercoat layer in Examples 1 to 6 and Comparative Examples 1 to 4, samples of only the undercoat layer applied to the aluminum drum in the same manner as the processing conditions in each Example and Comparative Example were used. The amount of residual solvent in the undercoat layer was measured using a pyrolysis-gas chromatograph (GC-15A: manufactured by Shimadzu Corporation). The total of the detected methyl ethyl ketone and cyclohexanone was defined as the residual solvent amount. The results are also shown in Table 1 below.

  As can be seen from the results in Table 1, the electrophotographic photosensitive member having the structure of the present invention has little fluctuations in the charging potential and the post-exposure potential even after copying 50,000 sheets, and also has granular background contamination and fine line reproducibility. Good results are shown, and even when an aluminum support (aluminum drum) containing metal impurities such as iron and copper is used, the occurrence of image defects such as black spots can be prevented during repeated use. On the other hand, in the case of Comparative Examples 1 to 3 that do not have the configuration of the present invention, the granular ground stain after copying 50,000 sheets is so severe that it cannot withstand repeated use. In the case of Comparative Example 4, the residual solvent was larger than the others, and defects in fine line reproducibility were recognized even in the initial stage. From this, when the residual solvent in the undercoat layer is 10 to 1000 ppm, the occurrence of minute granular scum during repeated use is prevented, and the potential after exposure to the photoreceptor during long-term storage is stabilized. I understand.

It is a schematic sectional drawing which shows the structural example of the electrophotographic photoreceptor in this invention. 1 is a schematic configuration diagram schematically illustrating an example of an electrophotographic apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum support body 2 Resin layer 3 Undercoat layer 4 Charge generation layer 5 Charge transport layer 6 Photosensitive layer 11 Photosensitive drum 12 Charging means (contact charging device)
13 Image exposure 14 Developing means 15 Transfer member 16 Transfer means (contact transfer means)
17 Cleaning means 18 Static elimination means 19 Fixing means

Claims (6)

An electrophotographic photosensitive member having at least a photosensitive layer on an aluminum support containing 0.3 wt% or more of iron and copper in total,
Between the aluminum support and the photosensitive layer, a resin layer made of methoxymethylated nylon and an undercoat layer made of an inorganic pigment and a thermosetting resin are sequentially provided from the support side ,
An electrophotographic photoreceptor, wherein the residual solvent in the undercoat layer is 10 to 1000 ppm .   The electrophotographic photosensitive member according to claim 1, wherein the total content of iron and copper is 0.3 to 10 wt%. The surface roughness (Rz) of the aluminum support is 0.2 to 1.5 μm, and the film thickness (d) of the resin layer made of methoxymethylated nylon is 0.5 to 1.5 μm. The electrophotographic photosensitive member according to claim 1 or 2.   The thermosetting resin in the undercoat layer is composed of an alkyd resin and a melamine resin, and the ratio (P / R) of the inorganic pigment (P) to the thermosetting resin (R) is 4/1 to 9 / by weight. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is one. An image forming apparatus in which a charging unit, a developing unit, a transfer unit, and a cleaning unit are disposed around an electrophotographic photosensitive member, and at least one of the units is in contact with the electrophotographic photosensitive member. There,
Said electrophotographic photosensitive member, an image forming apparatus, characterized in that an electrophotographic photosensitive member according to any one of claims 1-4. In the process cartridge in which the electrophotographic photosensitive member, the charging unit, the developing unit, and the cleaning unit are integrally supported and are detachable from the image forming apparatus main body.
Said electrophotographic photosensitive member, process cartridge, wherein an electrophotographic photosensitive member according to any one of claims 1-4.

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