JP2006071665A - Electrophotographic photoreceptor, and image forming apparatus and process cartridge using the photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor free from rise of residual potential even in long-term repetitive use in a severe environment, exhibiting stable post-exposure potential after storage at high temperature, also exhibiting stable potential by charge and post-exposure potential during use, and having improved adhesiveness of a photosensitive layer to a subbing layer. <P>SOLUTION: The electrophotographic photoreceptor is constituted by sequentially layering a subbing layer, a charge generating layer and a charge transport layer on a conductive support, wherein the subbing layer comprises titanium oxide, a thermosetting resin and a polyalkylene glycol or a derivative thereof, the charge generating layer contains a butyral resin containing ≤40 mol% of hydroxyl groups, and the charge transport layer is formed by applying a coating liquid containing at least a binder resin and a charge transport material in a cyclic ether solvent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photoreceptor, an image forming apparatus using the photoreceptor, and a process cartridge.

  Patent Document 1 (Japanese Patent Laid-Open No. 7-234529) discloses a charge generating layer or a lower layer as an electrophotographic photosensitive member in which a photoconductive layer composed of a charge generation layer and a charge transport layer is provided on a conductive substrate. The pulling layer contains polyalkylene glycol and / or its derivative, and the charge transport layer contains an antioxidant, so that the chargeability does not decrease even when used repeatedly, the increase in residual potential is small, and the charging characteristics are stable. It is disclosed that an electrophotographic photoreceptor is provided.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 6-138777) discloses an electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate, wherein biphenyl is contained in the charge transport layer. Alternatively, when the binder resin in the charge generation layer contains a butyral resin having a degree of butyralization of 68 mol% or more, there is no problem such as curling of the photoreceptor or peeling of the photosensitive layer, thereby improving mechanical durability. It is described that an electrophotographic photoreceptor excellent in durability and environmental stability at a low residual potential is provided.

  However, the electrophotographic photosensitive member described in Patent Document 1 (Japanese Patent Application Laid-Open No. 7-234529) is sufficiently improved since it does not take into account charging stability in harsh environments such as high temperature and high humidity and potential stability after exposure. It cannot be said that it is. In addition, in the disclosure of the electrophotographic photosensitive member of the above-mentioned Patent Document 2 (Japanese Patent Application Laid-Open No. 6-138777), it describes charging stability in a severe environment such as high temperature and high humidity, and improvement of potential stability after exposure. There is no description of improvement on high temperature storage stability.

JP-A-7-234529 Japanese Patent Laid-Open No. 6-138777

  Therefore, in view of the above prior art, the object of the present invention is to (1) when a charge transport layer formed using a cyclic ether solvent is formed, the residual potential is increased even in long-term repeated use in a harsh environment. In addition, the post-exposure potential after storage at high temperature is stable, (2) the charge potential during repeated use in harsh environments, the post-exposure potential is stable, and (3) adhesion between the photosensitive layer and the undercoat layer. And (4) to provide an electrophotographic photosensitive member in which a rise in residual potential during repeated use in a harsh environment is reduced, and (5) prevention of black spot-like background contamination and line images. In order to provide an image forming apparatus that achieves both halftone, line image reproducibility, and solid area density, (6) a small image processing process cartridge device with excellent maintainability is provided. There is to do.

  The above-mentioned problems are as follows: (1) In an electrophotographic photoreceptor in which an undercoat layer, a charge generation layer, and a charge transport layer are sequentially laminated on a conductive support, the undercoat layer comprises titanium oxide, a thermosetting resin, A coating comprising polyalkylene glycol or a derivative thereof, wherein the charge generation layer contains a butyral resin having a hydroxyl group of 40 mol% or less, and the charge transport layer contains at least a binder resin and a charge transport material in a cyclic ether solvent. And (2) “the polyalkylene glycol or derivative thereof contained in the undercoat layer is a polyoxy fatty acid ester, and the polyoxy fatty acid ester The electrophotographic photosensitive member according to (1) above, wherein the content is 0.5 to 10 wt% with respect to the thermosetting resin. ”, (3)“ The charge generation The electrophotographic photosensitive member according to (1) or (2) above, wherein the ratio P / R of the charge generating material P and the butyral resin R is 1/1 to 3/1 in weight ratio. 4) “The electrophotographic photosensitive member according to any one of (1) to (3) above, wherein the butyral group of the butyral resin of the charge generation layer is 50 mol% or more”, (5) “Electrophotography” In an image forming apparatus in which a contact charging means, an exposure means, a developing means, a transfer means, a cleaning means, and a static elimination means are arranged around a photoconductor by a DC voltage, the electrophotographic photoconductor is the above (1) to (4). 2. An image forming apparatus according to claim 1, wherein at least one of charging means, developing means, transfer means, and cleaning means is in contact with the photosensitive body. ”, (6)“ above (1 A process characterized in that the electrophotographic photosensitive member according to any one of (4) to (4) and at least one of a charging unit, a developing unit, and a cleaning unit are integrally supported and are detachable from the main body of the image forming apparatus. Achieved by cartridge. "

  According to the present invention, (1) the undercoat layer is made of titanium oxide, a thermosetting resin, and polyalkylene glycol or a derivative thereof, the charge generation layer contains a butyral resin having a hydroxyl group of 40 mol% or less, and charge transport The layer is formed by applying a coating liquid containing at least a binder resin and a charge transport material to a cyclic ether solvent, thereby forming a severe layer when a charge transport layer formed using the cyclic ether solvent is formed. Provided is an electrophotographic photosensitive member that does not increase in residual potential even after long-term repeated use in the environment and has a stable post-exposure potential after storage at high temperature, and (2) a polyalkylene glycol or a derivative thereof contained in the undercoat layer Is a polyoxy fatty acid ester, and the content of the polyoxy fatty acid ester may be 0.5 to 10 wt% with respect to the thermosetting resin. , An electrophotographic photosensitive member having a stable charge potential upon repeated use in a harsh environment and a post-exposure potential is provided. (3) The ratio P / R of the charge generation material P to the butyral resin R in the charge generation layer is a weight ratio. Therefore, an electrophotographic photosensitive member in which the adhesion between the photosensitive layer and the undercoat layer is improved and the potential after exposure is stabilized is provided. (4) Since the butyral group of the butyral resin in the charge generation layer is 50 mol wt% or more, an electrophotographic photoreceptor is provided in which the increase in residual potential during repeated use in a harsh environment is reduced, and (5) such an electron An image satisfying halftone, line image reproducibility, and solid density by providing charging means, exposure means, reversal developing type developing means, transfer means, cleaning means, and charge eliminating means around the photoconductor. A forming device is provided, (6) A process cartridge for image formation having a small size and excellent maintainability because it is a process cartridge in which such a photosensitive drum, charging means, developing means, and cleaning means are integrally supported and detachable from the apparatus main body. An extremely excellent effect is provided.

Hereinafter, the present invention will be described in detail.
In the present invention, as described above, 1) the undercoat layer is made of titanium oxide, a thermosetting resin, and polyalkylene glycol or a derivative thereof, the charge generation layer contains a butyral resin having a hydroxyl group of 40 mol% or less, and The charge transport layer is an electrophotographic photoreceptor formed by applying a coating liquid containing at least a binder resin and a charge transport material to a cyclic ether solvent,
2) The polyalkylene glycol or derivative thereof contained in the undercoat layer is a polyoxy fatty acid ester, and the content of the polyoxy fatty acid ester is 0.5 to 10 wt% with respect to the thermosetting resin. ,
3) The ratio P / R of the charge generation material P of the charge generation layer and the butyral resin R is 1/1 to 3/1 in weight ratio,
4) It is an electrophotographic photosensitive member in which the butyral group of the butyral resin of the charge generation layer is 50 mol% or more,
5) In an image forming apparatus in which contact charging means, exposure means, developing means, transfer means, cleaning means, and charge eliminating means are provided around such an electrophotographic photosensitive member, charging means, developing means, transfer means An image forming apparatus in which at least one of the cleaning means is in contact with the photosensitive member,
6) A process cartridge in which such a photosensitive member, a charging unit, a developing unit, and a cleaning unit are integrally supported and detachably attached to the apparatus main body is included.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows a cross-sectional view of the photosensitive layer of the present invention.
As shown in FIG. 1, the photosensitive layer of the present invention is basically composed of an undercoat layer (32), a charge generation layer (33) and a charge transport layer (34) on a support (31). It consists of a layer structure. Further, a protective layer can be provided on the charge transport layer as necessary.

The support (31) has a volume resistance of 10 ¹⁰ Ω · cm or less, a metal such as aluminum, nickel, chromium, nichrome, copper, silver, gold, platinum, and stainless steel, tin oxide, indium oxide, nickel oxide, and oxide. Metal or oxide such as aluminum coated by film or cylindrical plastic (polyethylene terephthalate, polybutylene terephthalate, phenol resin, polypropylene, nylon, polystyrene, etc.) or paper by vapor deposition or sputtering, or aluminum, aluminum alloy , Nickel, stainless steel plate and the like. I. , I. I. , Tube made by extruding, drawing, etc., then surface-treated by cutting, superfinishing, polishing, etc., or the above metal made into a film or cylinder by electroplating, etc., or conductive A film or cylindrical product obtained by dispersing and molding powder into plastic can be used. In addition to the above-mentioned support, a conductive material such as carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, silver or metal oxide such as titanium black, conductive tin oxide, ITO, etc. It is also possible to use a powder obtained by dispersing a functional powder in a suitable binder resin. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl galbazole, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic or thermosetting resins such as melamine resin, urethane resin, phenol resin, and alkyd resin, or a photocurable resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, methylene chloride, methylene ethyl ketone, and toluene. Furthermore, by a heat shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinyl chloride, polyethylene, bim chloride, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can be favorably used as the conductive substrate of the present invention.

In the present invention, the undercoat layer (32) is provided for the purpose of improving adhesiveness, preventing moire, improving the coatability of the upper layer, and reducing the residual potential. The undercoat layer is composed mainly of titanium oxide and a thermosetting resin, and further contains polyalkylene glycol or a derivative thereof.
Specific examples of the polyalkylene glycol derivative in the present invention include the following. However, the present invention is not limited to the following specific examples.

  Mono- or diesters of polyalkylene glycols represented by the following general formulas (II) and (III).

〔ここで、ｍ＝２〜４、ｎ＝１〜３０（平均付加モル数）、Ｒ_１，Ｒ_２は炭素数１〜３０のアルキル基またはアルケニル基、好ましくは１０〜２０のアルキル基またはアルケニル基を示す〕

[Where m = 2 to 4, n = 1 to 30 (average number of added moles), R ₁ and R ₂ are alkyl groups or alkenyl groups having 1 to 30 carbon atoms, preferably 10 to 20 alkyl groups or alkenyls. Show group)

  Examples thereof include polyethylene glycol monostearate, polyethylene glycol monooleate, polyethylene glycol distearate, polyethylene glycol dilaurate, and polyethylene glycol dioleate.

  The polyalkylene glycol monoether is a polyalkylene glycol monoether represented by the following formula (IV).

（式中ｍは２〜４、Ｒは炭素数１〜３０のアルキル基、好ましくは炭素数１０〜２０のアルキル基、置換もしくは無置換のアリール基、好ましくは炭素数１〜２０のアルキル基で置換されたフェニル基を、ｎは平均付加モル数を示し、１以上、好ましくは１〜１００の実数を表わす。）

(In the formula, m is 2 to 4, R is an alkyl group having 1 to 30 carbon atoms, preferably an alkyl group having 10 to 20 carbon atoms, a substituted or unsubstituted aryl group, preferably an alkyl group having 1 to 20 carbon atoms. (In the substituted phenyl group, n represents an average added mole number and represents a real number of 1 or more, preferably 1 to 100.)

  For example, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl phenyl ether and the like can be mentioned.

  Among these, mono- or diesters of polyalkylene glycols represented by the above general formula (III) are particularly preferable under high temperature and high humidity and low temperature and low humidity. The above polyalkylene glycol derivatives can be used alone or in combination of several kinds.

  When the polyalkylene glycol derivative is a polyoxy fatty acid ester, the charging potential during repeated use and the post-exposure potential can be stabilized. In particular, the polyalkylene glycol diester of the above general formula (II) has the molecular weight of the terminal group larger than that of H atoms, is stable under high temperature and high humidity, and provides the photoreceptor of the present invention with little fluctuation in potential after exposure. it can.

  The amount of polyoxy fatty acid ester added to the undercoat layer is optimized according to the number of hydrophilic groups in the molecule calculated from HLB (Hydrophine-Lifophile Balance) expressed as wt% x 1/5 of the hydrophilic group molecular weight in the molecule. Is done. The content of the polyoxy fatty acid ester is preferably 0.5 to 20 wt% of the undercoat layer resin. If it is less than 0.5 wt%, the photoreceptor of the present invention has little effect on the stability of the charging potential under low temperature and low humidity and the potential after exposure, and if it exceeds 20 wt%, it affects the stability of the potential after exposure under high temperature and high humidity. Will be given.

As the thermosetting resin used for the undercoat layer, considering that the photosensitive layer on the thermosetting resin is applied using a solvent, it is desirable to have high solubility resistance with respect to a general organic solvent. Such resins include 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 plurality of epoxy groups. And a thermosetting resin obtained by thermally polymerizing the compound to be cured. 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, hydroxyethyl methacrylate group, etc. Examples of the compound containing individual compounds include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate and the like, and prepolymers thereof, and examples of the compound having a plurality of epoxy groups include bisphenol A type epoxy resin.

  Further, a thermosetting resin obtained by thermally polymerizing an oil-free alkyd resin and an amino resin such as a butylated melamine resin can be used. These resins are used alone or in combination of two or more. These resins are used by dissolving in an appropriate solvent.

  Titanium oxide is used by being dispersed together with a solvent and a binder resin by a conventional method, for example, a ball mill, a sand mill, an attritor or the like. The polyalkylene glycol derivative is added later to the titanium oxide dispersion.

  The undercoat layer is formed on the conductive substrate by roll coating, dip coating, spray coating, nozzle coating, blade coating, or the like. After application, it is dried or cured by a curing process such as drying or heating. The thickness of the undercoat layer is 0.1 to 30 μm, preferably 0.2 to 10 μm.

  Further, the titanium oxide is preferably in a range of 0.5 / 1 to 3/1 by volume ratio with respect to the binder resin. In particular, since the polyalkylene glycol derivative is a polyoxy fatty acid ester and the content thereof is 0.5 to 20 wt% with respect to the thermosetting resin, the potential stability during repeated use in a harsh environment is excellent and the electrophotographic photosensitive member is The amount of change in the post-exposure potential before and after high temperature storage can be reduced. Although details of this mechanism are unknown, it is considered that the polyalkylene glycol derivative acts moderately on the thermosetting of the resin to form a stable undercoat layer even at high temperature storage.

  The charge generation layer (33) is composed of a charge generation material such as an azo pigment and a binder resin. Examples of the azo pigment include an azo pigment having a carbazole skeleton, an azo pigment having a triphenylamine skeleton, an azo pigment having a diphenylamine skeleton, an azo pigment having a dibenzothiophene skeleton, an azo pigment having a fluorenone skeleton, and an oxadiazol skeleton. Azo pigments having bis stilbene skeleton, azo pigments having distyryl oxadiazol skeleton, azo pigments having distyryl carbazole skeleton, metal phthalocyanine, metal-free phthalocyanine in addition to azo pigment Phthalocyanine pigments, azulenium salt pigments, squalic acid methine pigments, perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, Cyanine and azomethine pigments, indigoid pigments, bisbenzimidazo - Le pigment and may contain 1 or more.

  The general formula (a) and specific examples of suitable azo pigments are shown in (69) to (137).

  The binder resin used for the charge generation layer is preferably polyvinyl butyral. The butyral resin in the present invention is synthesized by reacting butyraldehyde with polyvinyl alcohol. The butyral resin has a repeating unit represented by the general formula (b) due to reaction in the polyvinyl alcohol synthesis process, butyral resin synthesis process, and production restrictions. ing.

  In general, a butyral resin changes its physical and chemical properties depending on its composition, and its thermal properties, mechanical properties and solution viscosity also change depending on its degree of polymerization. The reason why the butyral resin in the present invention is effective is not clear, but the particle size of the charge generating material such as an azo pigment can be dispersed relatively small, and there are few hydroxyl groups in the butyral resin in a severe environment such as high temperature and high humidity. This is considered to be due to the fact that the number of acting electrons and holes is small.

  The ratio P / R between the charge generation material P and the butyral resin R in the charge generation layer is 1/1 to 3/1 by weight, thereby improving the adhesion between the photosensitive layer and the undercoat layer and stabilizing the potential after exposure. Can be made.

Moreover, when the butyral group of the butyral resin in the charge generation layer is 50 mol wt% or more, it is possible to reduce an increase in residual potential during repeated use in a harsh environment.
If necessary, a charge transport material may be added to the charge generation layer.

  Methods for forming the charge generation layer include a vacuum thin film preparation method and a casting method from a solution dispersion system.

  For the former method, a vacuum deposition method, a glow discharge polymerization method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and an inorganic material film can be satisfactorily formed. A material film can be formed.

  In order to provide the charge generation layer (35) by the casting method described later, a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, or butanone is used together with the above-described inorganic or organic charge generation material together with a binder resin if necessary. Then, it can be formed by dispersing with a ball mill, an attritor, a sand mill or the like, and applying the solution after diluting the dispersion appropriately. The coating can be performed using a dip coating method, a spray coat, a bead coat method 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. 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.

  The charge transport layer (34) is a layer intended to hold a charged charge and to couple the charge generated and separated in the charge generation layer (33) by exposure to the charged charge held by movement. The charge transport layer (34) is required to have a high electric resistance in order to achieve the purpose of holding the charged charge, and in order to achieve the purpose of obtaining a high surface potential with the held charged charge, a dielectric constant is required. Is required to be small and have good charge mobility.

  The charge transport layer for satisfying these requirements is a coating liquid in which a charge transport material and a binder resin are dissolved in a cyclic ether solvent such as tetrahydrofuran, tetrahydropyran, 1,4-dioxane, dioxolane, toluene, and dimethoxymethane. It is formed by coating. If necessary, an appropriate amount of a plasticizer, an antioxidant, a leveling agent and the like can be added in addition to the charge transport material and the binder resin. Environmentally, chlorinated solvents such as dichloromethane, chloroform, monochlorobenzene, trichloroethane, and trichloromethane are avoided.

  Examples of the charge transport material include a hole transport material and an electron transport material.

  Examples of the electron transporting 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-trinitro Examples thereof include electron accepting substances such as dibenzothiophene-5,5-dioxide. These electron transport materials can be used alone or as a mixture of two or more. Moreover, you may use together with antioxidant like the following examples other than a hydroquinone type | system | group.

  Monophenolic compounds such as 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 such as 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4 '-Thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis- (3-methyl-6-tert-butylphenol) and the like.

  Large molecular phenolic compounds such as 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3 , 5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3, 3′-bis (4′-hydroxy-3′-t-butylphenyl) butyric acid] glycol ester, tocopherols and the like.

  Paraphenylenediamines such as N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine, and the like.

  Organic sulfur compounds such as dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate.

  Organic phosphorus compounds such as triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.

  Examples of the hole transporting material include the electron donating materials shown below and are used favorably. For example, oxazol derivatives, oxadiazol derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4-dibenzylaminophenyl) propane, styrylanthracene , Styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole 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 binder resin that can be used in combination with the charge transport layer is polycarbonate (bisphenol A type, bisphenol Z type), polyester, methacrylic resin, acrylic resin, polyethylene, vinyl chloride, vinyl acetate, polystyrene. , Phenol resin, epoxy resin, polyurethane, polyvinylidene chloride, alkyd resin, silicone resin, polyvinyl carbazole, polyvinyl butyral, polyvinyl formal, polyacrylate, polyacrylamide, phenoxy resin, etc. It is done. 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.

  As the plasticizer, those used as plasticizers such as dibutyl phthalate, dioctyl phthalate, and bisbenzylbenzene derivatives can be used as they are, and the amount used is about 0 to 30 parts by weight with respect to 100 parts by weight of the binder resin. Is appropriate.

  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 or oligomers having a perfluoroalkyl group in the chain are used, and the amount used is 100 parts by weight of binder resin. 0 to 1 part by weight is suitable.

A protective layer may be provided on the charge transport layer.
The protective layer is a layer in which fine particles of metal or metal oxide are dispersed in a binder resin. As the binder resin, a resin that is transparent to visible and infrared light and excellent in electrical insulation, mechanical strength, and adhesiveness is desirable. As the binder resin for the protective layer, 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. 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, fluorine resins such as polytetrafluoroethylene, silicone resins, and those obtained by dispersing inorganic materials such as these resins can 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.

FIG. 2 is a schematic cross-sectional view of an example of the electrophotographic apparatus of the present invention.
In the figure, reference numeral (11) denotes the photosensitive drum of the present invention. First, the photosensitive drum (11) having the undercoat layer and the photosensitive layer as described above is charged by a contact charging device (12) as a charging means. After the photosensitive drum (11) is charged, the photosensitive drum (11) is subjected to image exposure (13) with laser light from the exposure means. Electric charges are generated in the exposed portion, and an electrostatic latent image is formed on the surface of the photosensitive drum (11). Is formed. After an electrostatic latent image is formed on the surface of the photosensitive drum, the toner image is formed by contacting the developer via the developing means (14). The toner image formed on the surface of the photosensitive drum is transferred to a transfer member (15) such as paper by the contact transfer means (12), and passes through the fixing means (19) to become a hard copy. Residual toner on the photosensitive drum (11) is removed by a cleaning means (17) comprising a cleaning blade, and residual charges are removed by a charge eliminating means (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. The roller in the present invention may contact the photosensitive layer at both ends in the longitudinal direction of the photosensitive drum (11). In particular, when the edge of the charge transport layer is in contact with the roller, the resin type of the charge generation layer provided between the undercoat layer and the charge transport layer, or the edge of the charge transport layer is photosensitive when the charge generation layer does not contain a resin. It peels off by repeated use of the body drum (11).

  In the image forming apparatus of the present invention, at least one of a charging unit (12), a developing unit (14), a leaning unit (17), and the like is integrated with the photosensitive member (11) as described above. The present process cartridge (see FIG. 3) is mounted. By using the process cartridge, the image forming apparatus can be easily reduced in size, attached, and detached.

  Examples are shown below. “Parts” means parts by weight.

Example 1
[Production example of photosensitive drum]
(Underlayer)
A mixture having the following composition was placed in a ball mill pot and ball milled for 72 hours using φ10 mm alumina balls.

Titanium oxide (CR-60: manufactured by Ishihara Sangyo) 50 parts alkyd resin (Beckolite M6401-50 manufactured by Dainippon Ink and Chemicals, Inc .;
15 wt. Melamine resin (Super Becamine L-121-60, manufactured by Dainippon Ink & Chemicals, Inc.)
(Solid content 60 wt%) 8.3 parts methyl ethyl ketone (manufactured by Kanto Chemical) 31.7 parts

Methyl ethyl ketone (manufactured by Kanto Chemical Co., Inc.) 105 parts polyethylene glycol distearate (Ionet DS300; manufactured by Sanyo Chemical Co., Ltd., HLB = 7.3) 0.5 part is added to this milling liquid, and ball milling is further performed for 2 hours to form an undercoat layer coating liquid. Was made. This coating solution was dip-coated on an aluminum drum having a diameter of 30 mm, a length of 340 mm, and a thickness of 0.75 mm, and dried at 130 ° C. for 20 minutes to form an undercoat layer having a thickness of 4.5 μm.

(Charge generation layer)
Subsequently, the above-mentioned No. A mixture of 3 parts of (129) charge generation material (manufactured by Ricoh) and 80 parts of cyclohexanone (manufactured by Kanto Chemical) was taken in a ball mill pot and ball milled for 72 hours using a YTZ ball of φ10 mm, and then 78.4 parts of cyclohexanone. And then ball milling for 2 hours. Then, a polyvinyl butyral resin having a solid content concentration of 2 wt% (hydroxyl group 33 mol%, butyral group 64 mol%) / 60 parts of cyclohexanone solution and 88.9 parts of methyl ethyl ketone were added to form a charge generation layer coating solution. It was adjusted.

  This coating solution was dip coated on the undercoat layer and dried at 130 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.1 μm.

(Charge transport layer)
Next, a charge transport layer coating solution having the following composition was prepared, and this coating solution was dip coated on the charge generation layer and dried at 125 ° C. for 15 minutes to form a 31 μm thick charge transport layer.

Charge transport material (chemical formula (III)) (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, polyethylene glycol distearate Ionet DS300 as the undercoat layer was changed to 0.62 part of Ionet DS400; manufactured by Sanyo Kasei Co., Ltd. (HLB = 8.37), and the charge generation material of the charge generation layer was changed to No. (97) material (manufactured by Ricoh), polyvinyl butyral resin / cyclohexanone solid content concentration is changed to 2.5 wt% and added to the milling solution to adjust the charge generation layer coating solution and dip coating on the undercoat layer An electrophotographic photosensitive member was prepared in exactly the same manner as in Example 1 except that it was dried at 130 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.1 μm.

(Example 3)
A subbing layer was formed in the same manner as in Example 2 except that polyethylene glycol distearate Ionet DS400 in the subbing layer was changed to 0.063 part of Ionet DS4000; Sanyo Kasei (HLB = 17) in Example 2. Subsequently, the above-mentioned No. A mixture of (97) material (Ricoh) and NO129 (Ricoh) charge generation material 1.5 parts each and cyclohexanone (Kanto Chemical) 80 parts is placed in a ball mill pot, and a YTZ ball of φ10 mm is used. After ball milling for a period of time, a polyvinyl butyral resin / cyclohexanone solution having a solid content concentration changed to 1.67 wt% was added to the milling solution to prepare a charge generation layer coating solution, dip coated on the undercoat layer, 20 ° C. at 20 ° C. An electrophotographic photosensitive member was prepared in exactly the same manner as in Example 2 except that a charge generation layer having a thickness of 0.1 μm was formed by drying for a minute.

Example 4
Exactly the same as in Example 3, except that polyethylene glycol distearate Ionet DS4000 in the undercoat layer was changed to 0.1 part of polyethylene glycol dioleate (Ionet DO1000; manufactured by Sanyo Kasei, HLB = 12.9). An undercoat layer was formed. Subsequently, 60 parts of a polyvinyl butyral resin (hydroxyl group 25 mol%, butyral group 70 mol%) / cyclohexanone solution having a solid content concentration of 3.33 wt% was added to the charge generating material milling liquid of Example 3 and added thereto. After the above adjustment, dip coating was performed on the undercoat layer, followed by drying at 130 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.1 μm. Further, an electrophotographic photosensitive member was produced by changing the charge transport layer resin of Example 3 to polycarbonate resin (C-1400, manufactured by Teijin Chemicals) and the coating solvent to dioxolane (manufactured by Kanto Chemical).

(Example 5)
Exactly the same as in Example 3, except that polyethylene glycol distearate Ionet DS4000 in the undercoat layer was changed to 0.15 part of polyethylene glycol monooleate (Ionet MO400; manufactured by Sanyo Chemical Co., Ltd., HLB = 11.8). As a result, an undercoat layer was formed. Subsequently, 60 parts of a polyvinyl butyral resin (hydroxyl group 34 mol%, butyral group 63 mol%) / cyclohexanone solution having a solid content concentration of 5 wt% was added to the charge generating material milling solution of Example 3 to prepare a charge generating layer coating solution. Thereafter, an electrophotographic photosensitive member was produced in exactly the same manner as in Example 3 except that a charge generation layer having a thickness of 0.1 μm was formed by dip coating on the undercoat layer and drying at 130 ° C. for 20 minutes.

(Example 6)
Except that the undercoat layer polyethylene glycol distearate Ionet DS4000 was changed to 0.138 part of polyethylene glycol monotearate (Ionet MS400; HLB = 11.9 manufactured by Sanyo Kasei Co., Ltd.). A pulling layer was formed. Subsequently, the charge generation material milling solution of Example 3 was changed to a polyvinyl butyral resin having a hydroxyl group of 37 mol% and a butyral group of 60 mol% to prepare a charge generation layer coating solution, followed by dip coating on the undercoat layer, 130 ° C. An electrophotographic photosensitive member was prepared in exactly the same manner as in Example 3 except that drying was performed for 20 minutes to form a charge generation layer having a thickness of 0.1 μm.

(Example 7)
A subbing layer was formed in exactly the same manner as in Example 6 except that the polyethylene glycol mononetate ionet MS400 in the subbing layer was changed to 1.02 parts of polyethylene glycol distearate Ionet DS300 in Example 6. Subsequently, the charge generation material milling solution of Example 6 was changed to a polyvinyl butyral resin having a hydroxyl group of 26 mol% and a butyral group of 70 mol% to prepare a charge generation layer coating solution, followed by dip coating on the undercoat layer, 130 ° C. An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 6 except that drying was performed for 20 minutes to form a charge generation layer having a thickness of 0.1 μm.

(Example 8)
An electrophotographic photoreceptor was prepared in exactly the same manner as in Example 1, except that the amount of polyethylene glycol distearate ionet DS300 in the undercoat layer was changed to 1.5 parts.

Example 9
In Example 1, the solid content concentration of the polyvinyl butyral resin / cyclohexanone solution was changed to 10 wt%, and in addition to the above milling solution, the charge generation layer coating solution was adjusted and dip coated on the undercoat layer and dried at 130 ° C. for 20 minutes. Then, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that a charge generation layer having a thickness of 0.1 μm was formed.

(Example 10)
In Example 1, the solid content concentration of the polyvinyl butyral resin / cyclohexanone solution was changed to 1.25 wt%, and in addition to the milling solution, the charge generation layer coating solution was adjusted and dip coated on the undercoat layer at 130 ° C. for 20 minutes. An electrophotographic photosensitive member was prepared in exactly the same manner as in Example 1 except that it was dried to form a charge generation layer having a thickness of 0.1 μm.

(Comparative Example 1)
An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the polyethylene glycol distearate Ionet DS300 in the undercoat layer was omitted in Example 1.

(Comparative Example 2)
Preparation of charge generation layer coating solution by adding 60 parts of a polyvinyl butyral resin (hydroxyl group 53 mol%, butyral group 43 mol%) / cyclohexanone solution having a solid content concentration of 3.33 wt% to the charge generation material milling solution in Example 1 Thereafter, an electrophotographic photosensitive member was prepared in exactly the same manner as in Example 1 except that a dip coating was performed on the undercoat layer and drying was performed at 130 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.1 μm.

(Comparative Example 3)
An electrophotographic photosensitive member was prepared in the same manner as in Comparative Example 5 except that the polyethylene glycol distearate Ionet DS300 in the undercoat layer was omitted in Comparative Example 5.
The electrophotographic photosensitive member produced in this way is a unit in which the exposure part of a reversal development type digital copying machine (Imago 250 manufactured by our company) is modified to laser exposure at a wavelength of 665 nm, the developing roller is removed, and an electrometer probe is attached. The initial charging potential and the post-exposure potential were measured.

  This electrophotographic photosensitive member was stored for 6 months in an environment of 45 ° C. and 43%, and then mounted on the above-described reversal development type digital copier (Imagio 250 manufactured by our company), and the charged potential and the post-exposure potential were measured. Subsequently, 20,000 copies were made at room temperature and humidity, 10,000 copies at 35 ° C and 85%, and a total of 30,000 copies were made. After initial, high-temperature storage, the image quality after 30,000 copies (black, Fine line reproducibility) and potential were evaluated. In addition, the amount of wear was measured from the OPC film thickness before and after 30,000 copies measured with an eddy current film thickness meter (Fisher instruments mms).

  Further, the peel width of the charge transport layer at the end of the photosensitive drum was visually measured. These results are shown in Table 2.

  The evaluation of the black spot 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. Table 3 shows the criteria for black spot evaluation. In the determination, “○”, “◯”, “Δ” means that there is no practical problem, and “x” means that it is not suitable for practical use. Further, the reproducibility of fine lines was evaluated from a one-dot line image.

It is sectional drawing of the photosensitive layer of this invention. 1 is a schematic cross-sectional view of an electrophotographic apparatus of the present invention. It is a figure which shows the example of a process cartridge of this invention.

Explanation of symbols

11; Photoconductor 12; Contact-type charging roller (charging means)
13; writing light (exposure means)
14; developing means 15; transfer paper 16; transfer means 17; cleaning means 18; static elimination lamp 19; fixing roller 31; conductive substrate 32; undercoat layer 33; charge generation layer 34;

Claims (6)

In an electrophotographic photosensitive member in which an undercoat layer, a charge generation layer, and a charge transport layer are sequentially laminated on a conductive support, the undercoat layer is composed of titanium oxide, a thermosetting resin, and a polyalkylene glycol or a derivative thereof. The charge generation layer contains a butyral resin having a hydroxyl group of 40 mol% or less, and the charge transport layer is formed by applying a coating liquid containing at least a binder resin and a charge transport material to a cyclic ether solvent. An electrophotographic photosensitive member characterized by the above. The polyalkylene glycol or derivative thereof contained in the undercoat layer is a polyoxy fatty acid ester, and the content of the polyoxy fatty acid ester is 0.5 to 10 wt% with respect to the thermosetting resin. The electrophotographic photosensitive member according to claim 1. 3. The electrophotographic photosensitive member according to claim 1, wherein a ratio P / R of the charge generation material P and the butyral resin R of the charge generation layer is 1/1 to 3/1 by weight. 4. The electrophotographic photosensitive member according to claim 1, wherein the butyral group of the butyral resin of the charge generation layer is 50 mol% or more. 5. An image forming apparatus in which contact charging means, exposure means, developing means, transfer means, cleaning means, and static elimination means are arranged around the electrophotographic photosensitive member by a DC voltage, and the electrophotographic photosensitive member is any one of claims 1 to 4. An image forming apparatus, wherein at least one of a charging unit, a developing unit, a transfer unit, and a cleaning unit is in contact with the photosensitive unit. 5. The electrophotographic photosensitive member according to claim 1 and at least one of a charging unit, a developing unit, and a cleaning unit are integrally supported, and are detachable from an image forming apparatus main body. Process cartridge.

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