JP5411611B2 - Electrophotographic photoreceptor - Google Patents

Description

  The present invention relates to an electrophotographic photoreceptor using a photoreceptor binder resin composition containing a specific silicone resin.

  An organic photoreceptor (hereinafter abbreviated as OPC) is mainly used as an electrophotographic photoreceptor used in copying machines, laser beam printers (hereinafter abbreviated as LBP), fax machines, and the like.

  At present, the mainstream of OPC is a laminated electrophotographic photosensitive member in which a photosensitive layer has a charge generation layer and a charge transport layer, on a metal substrate such as a cylinder made of aluminum or stainless steel or a cylinder or belt made of aluminum-deposited polyester. In addition, a solution in which a binder resin such as polycarbonate or polyarylate and a charge generating agent or charge transporting agent are dissolved is prepared by wet molding.

  Conventionally, the outermost charge transport layer is in contact with toner, paper, a charging roller, a cleaning blade, and the like, and thus wear resistance is particularly required to have long-term durability. Silicone is a means for improving wear resistance. Methods have been reported in which a copolymerized acrylic resin and silicone oil are added as additives (Patent Documents 1 and 2). In addition, a technique of applying a hard coat using a curable silicone resin as a protective layer for the charge transport layer has been reported (see Patent Document 3).

  However, personal use LBP has been used mainly for printing photographs and images, and there are uses that require high-quality image printability with extremely fewer defects than durability. Furthermore, the use of the back side of printed copy paper is increasing in order to reduce the environmental load, and the load on the OPC surface and the toner transfer load tend to increase compared to unused paper. The cause of image defects in OPC may be several factors such as toner fusion, scratches on the OPC surface, toner detachment, poor toner cleaning, and poor toner transfer to paper. Among them, toner fusion and scratches on the OPC surface are major factors.

  As a method that is highly effective in eliminating toner fusion and scratches on the OPC surface, an OPC protective layer is provided, and the surface is renewed by actively scraping the surface with a cleaning blade or the like, and the defect factors are scraped off. There is a method (see Patent Document 4).

  The method has a drawback that a protective layer has to be provided and the number of manufacturing steps increases, and the conventional cleaning blade has to be changed or readjusted. For this reason, there has been a demand for a technique that positively imparts appropriate wearability (surface cleaning properties) to the charge transport layer itself, which is the outermost outer layer of the OPC, and improves self-cleaning properties.

JP-A-61-219049 Japanese Patent Application Laid-Open No. 64-03548 Japanese Patent Application Laid-Open No. 64-079756 Japanese Patent Application Laid-Open No. 07-225541

  The problem to be solved by the present invention is that the surface cleaning property of the outermost layer (charge transport layer) is improved, and a significant load is applied to the surface of the photoreceptor due to the use of the back side of printed copy paper or the repeated use of recycled recycled paper. It is also an object of the present invention to provide an electrophotographic photosensitive member having high image quality printability with very few image defects.

  As a result of intensive studies to solve the above problems, the present inventors have surprisingly found that electrophotographic photosensitive using a binder resin composition in which a small amount of a specific silicone resin having a phenylsiloxane structure is added to the photosensitive layer. As a result, it was found that the surface cleaning property was improved as compared with the electrophotographic photosensitive member using the conventional binder resin, and the present invention was completed. That is, the present invention relates to the following electrophotographic photosensitive member.

(1) In an electrophotographic photosensitive member having a photosensitive layer on a conductive substrate, the binder resin material of the photosensitive layer has a phenyl group content of 40 to 90 in all organic substituents bonded to silicon atoms in the molecule. An electrophotographic photoreceptor, which is a binder resin composition containing 0.05 to 10% by mass of a solid silicone resin at a normal temperature with a softening point of 60 ° C. or higher, based on the binder resin.

(2) The electrophotographic photosensitive member according to (1), wherein the silicone resin is a silicone resin represented by the following average composition formula (1).

[Chemical 1]
(C ₆ H ₅ ) _m R _n Si (OR ′) _p (OH) _q O _{(4-mnpq) / 2} (1)

(In formula (1), R is a monovalent hydrocarbon group having 1 to 6 carbon atoms which may have a substituent (excluding a phenyl group and an alkoxy group), and R ′ has a substituent. The monovalent hydrocarbon group having 1 to 6 carbon atoms, and m, n, p, and q are 0.5 ≦ m ≦ 2.0, 0.1 ≦ n ≦ 2.3, and 0 ≦ p ≦. 0.13, 0 ≦ q ≦ 0.17, 0.92 ≦ m + n + p + q ≦ 2.85 is a positive number and 0.4 ≦ m / (m + n) ≦ 0.9)

(3) The electrophotographic photosensitive member according to (1) or (2), wherein the silicone resin has a weight average molecular weight of 2,000 to 20,000 in terms of polystyrene of gel permeation chromatography.
(4) The electrophotographic photosensitive member according to any one of (1) to (3), wherein the binder resin is made of a polycarbonate resin or a polyarylate resin.
(5) The electrophotographic photosensitive member according to (4), wherein the polycarbonate resin is composed of one or more carbonate structural units represented by the following general formula (2).

(In formula (2), R _{1 to} R ₄ are hydrogen, fluorine, chlorine, bromine, iodine, an optionally substituted alkyl group having 1 to 20 carbon atoms, and an optionally substituted carbon number. It may have a 6-12 aryl group, an optionally substituted alkenyl group having 2 to 12 carbon atoms, an optionally substituted alkoxy group having 1 to 5 carbon atoms, and a substituent. A group selected from the group consisting of aralkyl groups having 7 to 17 carbon atoms, g is an integer of 1 or more, and X is a group selected from organic groups having the structure represented by the following formula (3). is there.

(In Formula (3), R ₅ and R ₆ may each have hydrogen, fluorine, chlorine, bromine, iodine, a C 1-20 alkyl group that may have a substituent, or a substituent. It represents a group selected from the group consisting of an alkoxy group having 1 to 5 carbon atoms and an aryl group having 6 to 12 carbon atoms which may have a substituent, or R ₅ and R ₆ are bonded to form a group having 5 to 5 carbon atoms. Represents a group that forms a carbocycle of 20 or a heterocycle of 5 to 12. R ₇ and R ₈ are each hydrogen, fluorine, chlorine, bromine, iodine, and optionally substituted 1 to 1 carbon atoms. An alkyl group having 9 carbon atoms, an alkoxy group having 1 to 5 carbon atoms that may have a substituent, an alkenyl group having 2 to 12 carbon atoms that may have a substituent, and a carbon number that may have a substituent represents a group selected from the group consisting of 6-12 aryl groups .R ₉ is an alkylene group having 1 to 9 which may have a substituent That .d represents an integer of 0 to 20, e is an integer of 1 to 500.)

(6) The polycarbonate resin is bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4 -Hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (4-hydroxyphenyl) The electron according to (4) or (5), which is derived from one or more bisphenols selected from the group consisting of -1-phenylethane and 1,1′-biphenyl-4,4′-diol. Photoconductor.

(7) The electrophotographic photosensitive member according to any one of (4) to (6), wherein the intrinsic viscosity of the polycarbonate resin is 0.3 to 2.0 dl / g.

  The electrophotographic photoreceptor using the binder resin composition containing the specific silicone resin of the present invention for the outermost layer (charge transport layer) is excellent in surface cleaning properties. That is, the charge transport layer has moderate wear (ease of scraping), and the charge transport layer itself can be easily and uniformly scraped (uses self-cleaning) with repeated printing, etc. It can be kept in a good state. Therefore, even after a significant load is applied to the surface of the photoconductor due to repeated use of backing paper or recycled recycled paper, deterioration of paper quality or usage environment, the surface of the photoconductor is actively scraped to promote surface renewal. By removing these defect factors, it is possible to repeatedly provide a high-quality printed matter with extremely few image defects.

  In addition, it is not necessary to form a new protective layer on the surface of the photoreceptor, and it can be used without changing the conventional manufacturing process, and it is not necessary to change or adjust the conventional cleaning blade. Therefore, it is extremely convenient for both the manufacturer side and the user side.

  The electrophotographic photoreceptor of the present invention uses a binder resin composition containing a small amount of a specific silicone resin as a binder resin material for a photosensitive layer.

1. Silicone Resin In the silicone resin of the present invention, the ratio of phenyl groups to the total amount of organic groups bonded to silicon atoms in the molecule is 40 to 90 mol%, particularly preferably 50 to 80 mol%. If it is less than 40 mol%, the compatibility with the binder resin is deteriorated, and film formation defects and white turbidity due to phase separation may increase. When it exceeds 90 mol%, the binder resin becomes too soft and appropriate wearability (surface cleaning properties) cannot be obtained. In addition, the content rate of a phenyl group can be calculated | required by < ¹ > H-NMR etc.

  The softening point of the silicone resin of the present invention is 60 ° C. or higher, particularly preferably 70 to 130 ° C., and is solid at room temperature. When the softening point is less than 60 ° C., the binder resin is likely to be sticky, and appropriate wear characteristics cannot be obtained.

  The weight average molecular weight of the silicone resin of the present invention is not particularly limited, but is preferably 2,000 to 20,000, and more preferably 3,000 to 10,000. When the weight average molecular weight is less than 2,000, moderate wear cannot be obtained, and when it exceeds 20,000, the compatibility with the binder resin may be deteriorated.

  The silicone resin used in the present invention is not particularly limited as long as it has the above-described characteristics. Specifically, the silicone resin of the present invention having such characteristics is represented by the following average composition formula (1). Can be mentioned. The average composition formula indicates the number of functional groups and substituents per Si.

[Chemical formula 4]
(C ₆ H ₅ ) _m R _n Si (OR ′) _p (OH) _q O _{(4-mnpq) / 2} (1)

  In said formula (1), R is a C1-C6 monovalent hydrocarbon group (however, except a phenyl group and an alkoxy group) which may have a substituent. Specific examples of R include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group and cyclohexyl group, alkenyl groups such as vinyl group, allyl group and hexenyl group, 3,3,3-trifluoro Illustrative are haloalkyl groups such as propyl and 3-chloropropyl, with methyl, ethyl and propyl being particularly preferred.

  In the above formula (1), R ′ is a monovalent hydrocarbon group having 1 to 6 carbon atoms which may have a substituent, specifically a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group. Examples thereof include alkyl groups such as isobutyl group, hexyl group and cyclohexyl group, and alkenyl groups such as vinyl group, allyl group and hexenyl group. In particular, methyl group or ethyl group is industrially used.

  In the above formula (1), m, n, p, and q are 0.5 ≦ m ≦ 2.0, 0.1 ≦ n ≦ 2.3, 0 ≦ p ≦ 0.13, and 0 ≦ q ≦ 0, respectively. .17, 0.92 ≦ m + n + p + q ≦ 2.85, and 0.4 ≦ m / (m + n) ≦ 0.9.

  The silicone resin of the present invention can be produced by a conventionally known method. For example, an organochlorosilane having a phenyl group, an organochlorosilane having an organic substituent R, and, if necessary, tetrachlorosilane are mixed and reacted with appropriate water, and then an organic solvent added as necessary is generated as a by-product. By removing hydrochloric acid and low boiling point components, a silicone resin having a phenyl group can be obtained. Also, phenyl group-containing alkoxysilanes and other alkyl group-containing alkoxysilanes corresponding to the above can be used instead of chlorosilane. In this case, it is preferable to carry out hydrolysis using an acid catalyst such as hydrochloric acid or acetic acid or a basic catalyst such as ammonia or sodium hydroxide. The silicone resin which has is obtained.

2. Binder resin The binder resin which is the main component of the binder resin material used in the photosensitive layer of the electrophotographic photoreceptor of the present invention is not particularly limited, and those used for ordinary binder resins can be used. Specifically, polycarbonate resin, polyarylate resin, polystyrene resin, polyester resin, acrylic resin, epoxy resin, or the like can be used. Of these, polycarbonate resins or polyarylate resins are preferred, and polycarbonate resins are most preferred.

(1) Polycarbonate resin What is preferable as a polycarbonate resin used for the binder resin of this invention has a structure represented by the said General formula (2).

In formula (2), R _{1 to} R ₄ are hydrogen, fluorine, chlorine, bromine, iodine, an optionally substituted alkyl group having 1 to 20 carbon atoms, and optionally having 6 carbon atoms. ˜12 aryl group, optionally substituted alkenyl group having 2 to 12 carbon atoms, optionally substituted alkoxy group having 1 to 5 carbon atoms, and optionally substituted carbon. It is a group selected from the group consisting of several 7 to 17 aralkyl groups. Preferred examples of R _{1 to} R ₄ include hydrogen, a methyl group, and a phenyl group.
In formula (2), g is 1 or more, preferably an integer of 30 to 200. X is a group selected from organic groups having a structure represented by the following formula (3).

In formula (3), R ₅ and R ₆ are each hydrogen, fluorine, chlorine, bromine, iodine, an optionally substituted alkyl group having 1 to 20 carbon atoms, and optionally substituted carbon. It represents a group selected from the group consisting of an alkoxy group having 1 to 5 carbon atoms and an aryl group having 6 to 12 carbon atoms which may have a substituent, or R ₅ and R ₆ are bonded to form a group having 5 to 20 carbon atoms. Represents a group forming a carbocyclic ring or a heterocyclic ring having 5 to 12 elements. Specific examples of R ₅ and R ₆ include hydrogen, methyl group, phenyl group and the like.

In formula (3), R ₇ and R ₈ are each hydrogen, fluorine, chlorine, bromine, iodine, an optionally substituted alkyl group having 1 to 9 carbon atoms, and optionally substituted carbon. A group selected from the group consisting of an alkoxy group having 1 to 5 carbon atoms, an alkenyl group having 2 to 12 carbon atoms which may have a substituent, and an aryl group having 6 to 12 carbon atoms which may have a substituent; Represent.
Specific examples of R ₇ and R ₈ include hydrogen, methyl group, phenyl group and the like.

In formula (3), R ₉ is an alkylene group of 1 to 9 which may have a substituent. Specific examples of R ₉ include ethylene group, propylene group, isopropylene group and the like.
In formula (3), d represents an integer of 0 to 20, preferably 0 to 5, and e represents an integer of 1 to 500, preferably 10 to 100. )

  The polycarbonate resin can be produced by a known method used for producing a polycarbonate from bisphenol A and a carbonic acid ester-forming compound, for example, a direct reaction between bisphenols and phosgene (phosgene method), or bisphenols and bisphenols. A method such as a transesterification reaction with an aryl carbonate (a transesterification method) can be employed.

  Specific examples of the raw material bisphenol used in the production of the polycarbonate resin of the present invention include 1,1′-biphenyl-4,4′-diol, bis (4-hydroxyphenyl) methane, and bis (4-hydroxyphenyl). Ether, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ketone, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4- Hydroxyphenyl) propane (bisphenol A; BPA), 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy-3-tert-butylphenyl) propane, 2,2-bis (4-Hydroxy-3-methylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclo 1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z; BPZ), 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) ) -3,3,5-trimethylcyclohexane, 1,1-bis (4-hydroxyphenyl) cyclododecane, 2,2-bis (4-hydroxy-3-allylphenyl) propane, 2,2-bis (4- Hydroxyphenyl) hexafluoropropane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) diphenylmethane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9- Bis (4-hydroxy-3-methylphenyl) fluorene, 4,4 '-[1,4-phenylenebis 1-methylethylidene)] bisphenol, 4,4 ′-[1,3-phenylenebis (1-methylethylidene)] bisphenol, 4,4′-butylidenebis (3-methyl-6-t-butyrylphenol), α , Ω-bis [3- (o-hydroxyphenyl) propyl] polydimethyldiphenyl random copolymer siloxane, α, ω-bis [3- (o-hydroxyphenyl) propyl] polydimethylsiloxane, and the like. Two or more of these may be used in combination.

  Among these, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) ) Cyclohexane, 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1 Bisphenols selected from phenylethane and 1,1′-biphenyl-4,4′-diol are preferred, in particular 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) cyclohexane Bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxy-3-methylphenyl) propyl Those selected from the pan is preferable.

  On the other hand, examples of the carbonate ester-forming compound include phosgene, triphosgene, and bisallyl carbonate such as diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, and dinaphthyl carbonate. It is done. Two or more of these compounds can be used in combination.

  In the phosgene method, the bisphenols and phosgene are usually reacted in the presence of an acid binder and a solvent. Examples of the acid binder include pyridine and alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and examples of the solvent include methylene chloride and chloroform.

Further, a tertiary amine catalyst such as triethylamine or a quaternary ammonium salt such as benzyltriethylammonium chloride is used to promote the condensation polymerization reaction.
Furthermore, it is preferable to add a monofunctional compound such as phenol, pt-butylphenol, p-cumylphenol, and long-chain alkyl-substituted phenol as a molecular weight regulator.
If desired, a small amount of an antioxidant such as sodium sulfite or hydrosulfite, or a branching agent such as phloroglucin, isatin bisphenol, or trisphenol ethane may be added.

  The reaction is usually in the range of 0 to 150 ° C, preferably 5 to 40 ° C. While the reaction time depends on the reaction temperature, it is generally 0.5 min-10 hr, preferably 1 min-2 hr. Further, during the reaction, it is desirable to maintain the pH of the reaction system at 10 or more.

  On the other hand, in the transesterification method, the bisphenols and bisaryl carbonate are mixed and reacted at a high temperature under reduced pressure. The reaction is usually carried out at a temperature in the range of 150 to 350 ° C., preferably 200 to 300 ° C., and the degree of vacuum is preferably at most 133 Pa or less, and the phenols derived from the bisaryl carbonate produced by the transesterification reaction Is distilled out of the system. The reaction time depends on the reaction temperature and the degree of reduced pressure, but is usually about 1 to 24 hours. The reaction is preferably carried out in an inert gas atmosphere such as nitrogen or argon. Moreover, you may react by adding a molecular weight regulator, antioxidant, and a branching agent as needed.

  The average molecular weight of the polycarbonate resin thus obtained is not particularly limited, but when the polycarbonate resin is used as a binder resin for a photosensitive layer of an electrophotographic photoreceptor, the electrophotographic photoreceptor formed by wet molding is a sufficient film. In order to obtain strength, the polycarbonate resin preferably has an intrinsic viscosity of 0.3 to 2.0 dl / g, particularly preferably 0.40 to 1.5 dl / g.

(2) Polyarylate resin The polyarylate resin used in the binder resin of the present invention is formed by polycondensation of bisphenols and a dibasic acid such as phthalic acid or carboxylic acid. For example, a method of causing an interfacial polycondensation reaction by dissolving aromatic dicarboxylic acid dichloride in an organic solvent and bisphenol in an alkali solvent, mixing and stirring at room temperature, aromatic dicarboxylic acid and bisphenol acetate or aromatic dicarboxylic acid It was manufactured using a method in which acid diphenyl ester and bisphenol are melted at a high temperature to cause a transesterification reaction, and a method in which aromatic dicarboxylic acid dichloride and bisphenol are polymerized using an amine compound as an acid acceptor. Is. Among these, it is preferable that the polymer is produced by interfacial polycondensation because a polymer is obtained.

  As the raw material bisphenol used for the polyarylate, those used for the polycarbonate resin can be used, among which 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-) It is preferably selected from 3-methylphenyl) propane, more preferably 2,2-bis (4-hydroxyphenyl) propane.

  Raw material aromatic dicarboxylic acids used for polyarylate include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 3-tert-butylisophthalic acid, diphenic acid, 4,4′-dicarboxylic acid, etc. And their dichlorides. These divalent dicarboxylic acids can be used alone or in combination of two or more. In particular, terephthalic acid and its dichloride are preferred.

  The average molecular weight of the polyarylate resin thus obtained is not particularly limited, but when the polyarylate resin is used as a binder resin for a photosensitive layer of an electrophotographic photoreceptor, an electrophotographic photoreceptor molded by wet molding is sufficient. In order to obtain a satisfactory film strength, the intrinsic viscosity of the polyarylate resin is preferably 0.1 to 10 dl / g, and particularly preferably 0.2 to 2.0 dl / g.

3. Binder resin composition The binder resin composition of this invention mix | blends the specific silicone resin of this invention with the said binder resin.
As a range in which the binder resin composition of the present invention has an adequate wear resistance (easiness to scrape), the silicone resin is preferably contained in an amount of 0.05 to 10% by mass with respect to the binder resin. It is preferable to contain 1-5 mass%. If the amount is less than 0.05% by mass, the wear resistance is insufficient, and if it exceeds 10% by mass, the compatibility is deteriorated, and film formation failure or white turbidity due to phase separation may be increased.

  The binder resin composition of the present invention includes a synthetic resin other than a silicone resin, for example, a vinyl polymer such as polymethyl methacrylate, polystyrene, and polyvinyl chloride, a copolymer thereof, and a polyester as long as the effect is maintained. It is possible to arbitrarily blend various thermoplastic resins such as polysulfone, phenoxy resin, epoxy resin, silicone resin other than the above silicone resin, and thermosetting resin. Various ultraviolet absorbers, antioxidants, mold release agents, lubricants, colorants and the like can be added as desired.

  The manufacturing method in particular of the binder resin composition of this invention is not restrict | limited, It can obtain by blending the binder resin, silicone resin, and the arbitrary component mix | blended as needed by a well-known method.

4). Electrophotographic Photoreceptor The electrophotographic photoreceptor of the present invention can be used for either a single-layer photosensitive layer on a conductive support or a functionally separated laminated type, but a binder that holds a charge transport material. It is preferable to use it for the charge transport layer of a laminated electrophotographic photosensitive member that can easily exhibit the characteristics of the resin.

  The conductive support of the present invention is a metal material such as aluminum, stainless steel, nickel, a polyester film provided with a conductive layer such as aluminum, palladium, tin oxide, zinc oxide, indium oxide on the surface, a phenol resin, Paper or the like is used.

  The charge generation layer of the present invention is formed on a conductive support by a known method. As the charge generation material, for example, organic pigments such as azoxybenzene, disazo, trisazo, benzimidazole, polycyclic quinoline, indigoid, quinacridone, phthalocyanine, perylene, and methine can be used. . These charge generation materials are made of fine particles such as polyvinyl butyral resin, polyvinyl formal resin, silicone resin, polyamide resin, polyester resin, polystyrene resin, polycarbonate resin, polyvinyl acetate resin, polyurethane resin, phenoxy resin, epoxy resin, and various celluloses. Used in a form dispersed in a binder resin.

  The charge transport layer of the present invention is formed by dispersing a charge transport material in the binder resin composition of the present invention using a known method on the charge generation layer. Examples of the charge transport material include polytetracyanoethylene; fluorenone compounds such as 2,4,7-trinitro-9-fluorenone; nitro compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; Triphenylmethane compounds; oxadiazole compounds such as 2,5-di (4-dimethylaminophenyl) -1,3,4-oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene A carbazole compound such as poly-N-vinylcarbazole; a pyrazoline compound such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline; 4,4 ′, 4 ″ -tris (N, N-diphenylamino); Triphenylamine, N, N′-bis (3-methylphenyl) -N, N′-bis (fluoro Benzyl) amine derivatives such as benzidine; conjugated unsaturated compounds such as 1,1-bis (4-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene; 4- (N, N-diethylamino) benzaldehyde-N, Hydrazone compounds such as N-diphenylhydrazone; nitrogen-containing compounds such as indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds, pyrazoline compounds, triazole compounds Examples thereof include condensed polycyclic compounds, etc. The above charge transport materials may be used alone or in combination of two or more.

  Using the binder resin composition of the present invention, after mixing with a charge transport material, etc., an electrophotographic photoreceptor is formed by known wet molding such as solution casting, casting, spraying, dip coating (dip method), etc. Is possible. In order that the electrophotographic photosensitive member molded by wet molding has sufficient film strength, when the binder resin is a polycarbonate resin, the intrinsic viscosity is preferably 0.3 to 2.0 dl / g. It is preferable that it is 40-1.5 dl / g.

  Solvents used in the wet molding include dichloromethane, chloroform, monochlorobenzene, 1,1,1-trichloroethane, monochloroethane, halogenated organic solvents such as carbon tetrachloride, aromatic hydrocarbons such as toluene and xylene, acetone , Ketones such as methyl ethyl ketone, cyclohexanone and isophorone, ethers such as tetrahydrofuran, 1,4-dioxane, ethylene glycol diethyl ether and ethyl cellosolve, esters such as methyl acetate and ethyl acetate, and other dimethylformamide, dimethylsulfoxide, diethylformamide, etc. Non-halogen organic solvents are mentioned. In the present invention, these solvents can be used alone or in combination of two or more. When the binder resin composition is dissolved in a solvent to form a charge transport layer, it is preferable to prepare and use a resin solution in the range of 1 to 30% by weight.

  The mixing ratio of the charge transport material and the binder resin composition is preferably within the range of 10: 1 to 1:10. The thickness of the charge transport layer is 2 to 100 μm, preferably 5 to 40 μm.

Hereinafter, it demonstrates concretely by an Example and a comparative example.
(Synthesis of silicone resin)
(Synthesis Example 1-1)
A 1 L glass flask equipped with a stirrer, a cooling device, and a thermometer was charged with 288 g (16 mol) of water and 93 g of toluene, and heated to an internal temperature of 80 ° C. in an oil bath. A mixture of 148 g (0.7 mol) of phenyltrichlorosilane, 51 g (0.2 mol) of diphenyldichlorosilane and 13 g (0.1 mol) of dimethyldichlorosilane was charged into the dropping funnel over 1 hour while stirring into the flask. After completion of the dropwise addition, aging was further performed at 80 ° C. for 1 hour. Next, 27 g (0.25 mol) of trimethylchlorosilane was added dropwise over 10 minutes, and after completion of the addition, aging was performed at an internal temperature of 80 ° C. for 30 minutes. After adding 100 g of toluene, the mixture was allowed to stand while cooling to room temperature and separated into two layers. The lower aqueous layer was separated and removed, and subsequently 200 g of 10% aqueous sodium sulfate solution was added and stirred for 10 minutes, and then left for 30 minutes. The washing operation of separating and removing the lower aqueous layer became neutral. Repeat until. An ester adapter was attached, and the mixture was heated to reflux until the internal temperature reached 110 ° C. to remove water. After confirming that water did not come out, the mixture was cooled to room temperature. The obtained toluene solution was filtered to remove insoluble matters such as sodium sulfate, and then toluene and a low-molecular siloxane component were removed by distillation under reduced pressure to obtain 135 g of a solid phenyl group-containing silicone resin S-1. The obtained silicone resin S-1 had a phenyl group content of 54 mol% by ¹ H-NMR measurement and a polystyrene-equivalent weight average molecular weight by GPC of 9,200. The softening point was 96 ° C.

(Synthesis Example 1-2)
360 g (20 mol) of Synthesis Example 1-1, 200 g of toluene, 84.5 g (0.4 mol) of phenyltrichlorosilane, 10 g (0.04 mol) of diphenyldichlorosilane, and 7. 68 g of solid phenyl group-containing silicone resin S-2 was obtained in the same manner as in Synthesis Example 1-1 except that 5 g (0.06 mol) and trimethylchlorosilane were replaced with 27 g (0.25 mol). The obtained silicone resin S-2 had a phenyl group content of 45 mol% by ¹ H-NMR measurement, and the polystyrene equivalent weight average molecular weight by GPC was 3,100. The softening point was 71 ° C.

(Synthesis Example 1-3)
324 g (18 mol) of water of Synthesis Example 1-1, 150 g of toluene, 169 g (0.8 mol) of phenyltrichlorosilane, 51 g (0.2 mol) of diphenyldichlorosilane, without using dimethyldichlorosilane, 131 g of solid phenyl group-containing silicone resin S-3 was obtained in the same manner as in Synthesis Example 1-1 except that 27.5 g (0.34 mol) of trimethylchlorosilane was replaced. The obtained silicone resin S-3 had a phenyl group content of 78 mol% by ¹ H-NMR measurement, and the polystyrene-equivalent weight average molecular weight by GPC was 5,600. The softening point was 120 ° C.

(Synthesis of polycarbonate resin)
(Synthesis Example 2-1)
1100 ml of 5 w / w% sodium hydroxide aqueous solution, 107.2 g (0.40 mol) of 1,1-bis (4-hydroxyphenyl) cyclohexane (hereinafter abbreviated as “BPZ”: manufactured by Taoka Chemical Co., Ltd.) and hydrosulfite 0.1 g was dissolved. To this, 500 ml of methylene chloride was added and stirred, while maintaining at 15 ° C., 60 g of phosgene was blown in over 60 minutes.
After completion of phosgene blowing, 1.67 g of pt-butylphenol (hereinafter abbreviated as “PTBP”: Dainippon Ink & Chemicals, Inc.) as a molecular weight regulator was added and stirred vigorously to emulsify the reaction solution. 0.4 ml of triethylamine was added, and the mixture was stirred at 20 to 25 ° C. for about 1 hour for polymerization.

After completion of the polymerization, the reaction solution was separated into an aqueous phase and an organic phase, the organic phase was neutralized with phosphoric acid, and washing with water was repeated until the conductivity of the previous solution (aqueous phase) became 10 μS / cm or less. The obtained polymer solution was dropped into warm water maintained at 45 ° C., and the solvent was removed by evaporation to obtain a white powdery precipitate. The obtained precipitate was filtered and dried at 110 ° C. for 24 hours to obtain a polymer powder.
The intrinsic viscosity of the solution having a concentration of 0.5 g / dl using methylene chloride as a solvent at 20 ° C. and a Haggins constant of 0.45 was 0.47 dl / g. The results obtained polymer was analyzed by infrared absorption spectrum, absorption by carbonyl group at the position in the vicinity of 1770 cm ^-1, observed absorption by ether bond position near 1240 cm ^-1, the polycarbonate resin (hereinafter PC having a carbonate bond -1).

(Synthesis Example 2-2)
Synthetic Example 2-1 except that 1,1-bis (4-hydroxyphenyl) ethane (hereinafter abbreviated as “BPE”: manufactured by Honshu Chemical Industry Co., Ltd.) 85.6 g (0.40 mol) was used instead of BPZ. Polymerization was carried out in the same manner as above to obtain a polycarbonate (inherent viscosity 0.50 dl / g: (hereinafter abbreviated as PC-10).

(Synthesis Example 2-3)
Instead of BPZ, 59.2 g (0.20 mol) of 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane (hereinafter abbreviated as “DMBPZ”: manufactured by Honshu Chemical Industry Co., Ltd.) and 2,2-bis Polymerization was carried out in the same manner as in Synthesis Example 2-1, except that the amount was changed to 45.6 g (0.20 mol) of (4-hydroxyphenyl) propane (hereinafter abbreviated as “BPA”: manufactured by Mitsui Chemicals, Inc.). Viscosity 0.48 dl / g: hereinafter abbreviated as PC-3).

(Synthesis Example 2-4)
Synthesis example except that bis (4-hydroxyphenyl) methane (hereinafter abbreviated as “BPF”: manufactured by Honshu Chemical Industry Co., Ltd.) 40 g (0.20 mol) and BPA 45.6 g (0.20 mol) were used instead of BPZ. Polymerization was carried out in the same manner as in 2-1, to obtain a polycarbonate (intrinsic viscosity 0.50 dl / g: hereinafter abbreviated as PC-4).

(Synthesis Example 2-5)
Instead of BPZ, 1,1′-biphenyl-4,4′-diol (hereinafter abbreviated as “BP”: manufactured by Honshu Chemical Industry Co., Ltd.) 37.2 g (0.20 mol) and BPA 45.6 g (0.20 mol) Polymerization was carried out in the same manner as in Synthesis Example 2-1 except that the polycarbonate was changed to an intrinsic viscosity of 0.52 dl / g (hereinafter abbreviated as PC-5).

(Synthesis Example 2-6)
Instead of BPZ, 51.2 g (0.20 mol) of 2,2-bis (4-hydroxy-3-methylphenyl) propane (hereinafter abbreviated as “BPC”: manufactured by Honshu Chemical Industry Co., Ltd.) and 45.6 g of BPA (0 Polymerization was carried out in the same manner as in Synthesis Example 2-1 except that the amount was changed to 20 mol) to obtain a polycarbonate (intrinsic viscosity 0.50 dl / g: hereinafter abbreviated as PC-6).

(Synthesis Example 2-7)
Instead of BPZ, BPC 20.5 g (0.08 mol), 1,1-bis (4-hydroxyphenyl) -1-phenylethane (hereinafter abbreviated as “BPAP”: manufactured by Honshu Chemical Industry Co., Ltd.) 11.6 g (0 0.04 mol) and BPA 63.8 g (0.28 mol), except that the polymerization was carried out in the same manner as in Synthesis Example 2-1 to obtain a polycarbonate (ultimate viscosity 0.50 dl / g: hereinafter abbreviated as PC-7). It was.

(Synthesis Example 2-8)
Polymerization was carried out in the same manner as in Synthesis Example 2-1 except that PTBP was changed to 0.82 g, to obtain a polycarbonate (intrinsic viscosity 0.74 dl / g: hereinafter abbreviated as PC-8).

Example 1
To a solution of 65 g of N, N′-bis (3-methylphenyl) -N, N′-bis (phenyl) benzidine (hereinafter abbreviated as “TPD type CT agent”: manufactured by SYNTEC) in 360 g of tetrahydrofuran, A resin composition obtained by adding 0.71 g of S-1 to 70 g of 1 polycarbonate resin was dissolved to prepare a charge transfer agent coating solution. The obtained resin solution was visually observed for white turbidity (solution transparency evaluation; see the evaluation method below).

  Next, the charge transport agent coating solution was applied by a dipping method to a commercially available LBP photoreceptor (LPA3ETC4 manufactured by Seiko Epson Corporation) from which the charge transport layer had been removed in advance, and dried at 100 ° C. for 8 hours after air drying. A charge transport layer having a thickness of about 25 μm was provided to produce a laminated electrophotographic photoreceptor (hereinafter abbreviated as “OPC”).

  The film thickness of the OPC thus prepared was measured in advance (using an eddy current film thickness meter manufactured by Fischer Instruments Co., Ltd., trade name “ISOSCOPE MP30E”), and then commercially available LBP (LBP-8400; (Seiko Epson Corporation).

  Next, using A4 recycled paper for OA (LBP-190R-A4B; manufactured by Ten Million Co., Ltd.), 10 sheets of continuous printing was performed by black printing on the entire surface. Immediately after continuous printing of 10 sheets in the form of overwriting on the back surface (the surface that has already been printed), one unprinted A4 recycled paper for OA was printed on the entire surface, and then printed on the entire surface in black (back surface printing load). The presence or absence of black spots in the black printed portion and the presence or absence of toner (black spots) on the unprinted portion were visually confirmed to evaluate the image quality (“initial image quality evaluation after loading recycled paper”; see the evaluation method below) ).

  After the “initial image quality evaluation after loading recycled paper”, OA A4 recycled paper is further added and 2500 sheets of the entire surface are black-printed. 10 sheets of black are printed continuously, and the back side of the 10 sheets is used for continuous printing, and then the back side (the already printed side) is overwritten. 1 sheet of paper is printed on the entire surface, then 1 sheet of black is printed on the entire surface, and the presence or absence of black spots on the black printed portion and the presence of toner on the unprinted portion (black spots) are visually confirmed. The image quality was evaluated ("Image quality evaluation after loading recycled paper after 2500 continuous printing"; see the evaluation method below).

  Further, the OPC film thickness after the “2,500-sheet continuous printing and post-loading image quality evaluation” is measured, the difference from the OPC film thickness before the initial image quality evaluation is calculated, and the OPC film thickness reduction amount (μm) is calculated. Obtained (OPC wear amount evaluation). Each evaluation result is shown in Table 1.

(Example 2)
OPCs were prepared in the same manner as in Example 1 except that S-2 was used instead of S-1, and physical properties were evaluated.

(Example 3)
OPC was prepared in the same manner as in Example 1 except that S-3 was used instead of S-1, and physical properties were evaluated.

Example 4
OPC was prepared in the same manner as in Example 1 except that PC-2 was used instead of PC-1, and the physical properties were evaluated.

(Example 5)
OPC was prepared in the same manner as in Example 1 except that PC-3 was used instead of PC-1, and the physical properties were evaluated.

(Example 6)
OPC was prepared in the same manner as in Example 1 except that PC-4 was used instead of PC-1, and the physical properties were evaluated.

(Example 7)
OPC was prepared in the same manner as in Example 1 except that PC-5 was used instead of PC-1, and the physical properties were evaluated.

(Example 8)
OPC was prepared in the same manner as in Example 1 except that PC-6 was used instead of PC-1, and the physical properties were evaluated.

Example 9
OPC was created in the same manner as in Example 1 except that PC-1 was changed to PC-7 and 3.7 g of S-1 was used, and physical properties were evaluated.

(Example 10)
OPC was prepared in the same manner as in Example 1 except that PC-1 was changed to PC-8 and 0.35 g of S-1 was used, and physical properties were evaluated.

(Example 11)
Example 1 and OPC were prepared and physical properties were evaluated except that commercially available polyarylate (U-100 manufactured by Unitika Ltd .; hereinafter abbreviated as PA-1) was used instead of PC-1.

(Comparative Example 1)
An OPC was prepared in the same manner as in Example 1 except that S-1 was not used, and the physical properties were evaluated.

(Comparative Example 2)
An OPC was prepared in the same manner as in Example 1 except that 0.03 g of S-1 was used, and the physical properties were evaluated.

(Comparative Example 3)
An OPC was prepared in the same manner as in Example 1 except that 9.5 g of S-1 was used, and the physical properties were evaluated.

(Comparative Example 4)
Cast film in the same manner as in Example 1 except that it was changed to a commercially available liquid phenyl group-containing silicone oil (trade name “KF56”; hereinafter abbreviated as S-4) manufactured by Shin-Etsu Chemical Co., Ltd.) instead of S-1. And OPC were created and the physical properties were evaluated.

(Comparative Example 5)
Except for changing to S-1 instead of commercially available phenyl group-containing solid silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KR-220L”; softening point 80 ° C .; hereinafter abbreviated as S-5) An OPC was prepared in the same manner as in Example 1, and the physical properties were evaluated.

(Comparative Example 6)
Except for changing to a commercially available phenyl group-free silicone acrylic resin (trade name “X-22-8004” manufactured by Shin-Etsu Chemical Co., Ltd .; softening point 90 ° C .; hereinafter abbreviated as S-6) instead of S-1. In the same manner as in Example 1, OPCs were prepared and evaluated for physical properties.

(Evaluation method)
1) Solution transparency evaluation:
The turbidity of the charge transport layer coating liquid prepared in Examples and Comparative Examples was visually determined in a 50 cc glass flask.
○: No cloudiness occurs.
X: Cloudiness is recognized.

2) Evaluation of initial image quality after loading recycled paper:
After installing OPC on a commercially available LBP, use A4 recycled paper for OA to print 10 continuous black pages, then use the back of the 10 continuous prints, and then overwrite the back (already printed) 10 sheets were continuously printed. After that, unprinted A4 recycled paper for OA is printed on the entire surface, then black printed on the entire surface, and then the presence or absence of white spots in the black printed portion with the major axis of 1 mm or more and the adhesion of the toner with the major axis of 1 mm or more to the unprinted portion. The presence or absence of (black spots) was visually confirmed and evaluated according to the following criteria.
○: No white spots or black spots can be confirmed.
X: White spots and black spots confirmed.

3) Evaluation of image quality after loading recycled paper after 2500 continuous printing:
After the initial image quality evaluation after loading the recycled paper, OA A4 recycled paper is added to make 2500 black prints on the entire surface. Further, as with the initial image quality evaluation after loading recycled paper, the OA A4 recycled paper is used to print the entire black image. 10 continuous prints, and using the back side of the 10 sheets, after the continuous print, and overwriting the back side (the surface that has already been printed), immediately after the 10 continuous prints, 1 unprinted A4 recycled paper for OA Print the entire surface without printing, then print the entire surface with black, and visually check for black spots on the black printed part with a major axis of 1 mm or more and adhesion of toner with a major axis of 1 mm or more (black spots) on the unprinted part. The evaluation was based on the following criteria.
○: No white spots or black spots can be confirmed.
X: White spots and black spots confirmed.

4) Evaluation of OPC wear:
The OPC film thickness before the initial image quality evaluation after the recycling paper load is measured, and then the image quality evaluation after the recycling paper load after the 2500 continuous printing is performed, and then the OPC film thickness is measured again. The amount of film thickness reduction (μm) was calculated, and the amount of OPC wear was evaluated. For measuring the OPC film thickness, an eddy current film thickness meter (trade name “ISOSCOPE MP30E” manufactured by Fisher Instruments Co., Ltd.) was used.

  The present invention can be applied to an electrophotographic photosensitive member that can maintain high image quality due to surface renewability even when the surface of the photosensitive member is damaged due to surface load caused by the use of recycled paper or the like.

Claims (7)

  In the electrophotographic photosensitive member having a photosensitive layer on a conductive substrate, the binder resin material of the photosensitive layer has a phenyl group content of 40 to 90 mol% in all organic substituents bonded to silicon atoms in the molecule. An electrophotographic photoreceptor, which is a binder resin composition containing 0.05 to 10% by mass of a solid silicone resin at a normal temperature with a softening point of 60 ° C. or higher with respect to the binder resin. The electrophotographic photosensitive member according to claim 1, wherein the silicone resin is a silicone resin represented by the following average composition formula (1).
[Chemical 1]
(C ₆ H ₅ ) _m R _n Si (OR ′) _p (OH) _q O _{(4-mnpq) / 2} (1)
(In formula (1), R is a monovalent hydrocarbon group having 1 to 6 carbon atoms which may have a substituent (excluding a phenyl group and an alkoxy group), and R ′ has a substituent. The monovalent hydrocarbon group having 1 to 6 carbon atoms, and m, n, p, and q are 0.5 ≦ m ≦ 2.0, 0.1 ≦ n ≦ 2.3, and 0 ≦ p ≦. 0.13, 0 ≦ q ≦ 0.17, 0.92 ≦ m + n + p + q ≦ 2.85 is a positive number and 0.4 ≦ m / (m + n) ≦ 0.9)   The electrophotographic photosensitive member according to claim 1 or 2, wherein the silicone resin has a weight average molecular weight of 2,000 to 20,000 in terms of polystyrene of gel permeation chromatography.   The electrophotographic photosensitive member according to claim 1, wherein the binder resin is made of a polycarbonate resin or a polyarylate resin. The electrophotographic photosensitive member according to claim 4, wherein the polycarbonate resin is composed of one or more of carbonate structural units represented by the following general formula (2).

(In formula (2), R _{1 to} R ₄ are hydrogen, fluorine, chlorine, bromine, iodine, an optionally substituted alkyl group having 1 to 20 carbon atoms, and an optionally substituted carbon number. It may have a 6-12 aryl group, an optionally substituted alkenyl group having 2 to 12 carbon atoms, an optionally substituted alkoxy group having 1 to 5 carbon atoms, and a substituent. A group selected from the group consisting of aralkyl groups having 7 to 17 carbon atoms, g is an integer of 1 or more, and X is a group selected from organic groups having the structure represented by the following formula (3). is there.

(In Formula (3), R ₅ and R ₆ may each have hydrogen, fluorine, chlorine, bromine, iodine, a C 1-20 alkyl group that may have a substituent, or a substituent. It represents a group selected from the group consisting of an alkoxy group having 1 to 5 carbon atoms and an aryl group having 6 to 12 carbon atoms which may have a substituent, or R ₅ and R ₆ are bonded to form a group having 5 to 5 carbon atoms. Represents a group that forms a carbocycle of 20 or a heterocycle of 5 to 12. R ₇ and R ₈ are each hydrogen, fluorine, chlorine, bromine, iodine, and optionally substituted 1 to 1 carbon atoms. An alkyl group having 9 carbon atoms, an alkoxy group having 1 to 5 carbon atoms that may have a substituent, an alkenyl group having 2 to 12 carbon atoms that may have a substituent, and a carbon number that may have a substituent represents a group selected from the group consisting of 6-12 aryl groups .R ₉ is an alkylene group having 1 to 9 which may have a substituent That .d represents an integer of 0 to 20, e is an integer of 1 to 500.)   The polycarbonate resin is bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl). ) Cyclohexane, 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1 The electrophotographic photosensitive member according to claim 4 or 5, wherein the electrophotographic photosensitive member is derived from one or more bisphenols selected from the group consisting of phenylethane and 1,1'-biphenyl-4,4'-diol.   The electrophotographic photosensitive member according to claim 4, wherein the polycarbonate resin has an intrinsic viscosity of 0.3 to 2.0 dl / g.