JP2007298952A - Electrophotographic photoreceptor, method for manufacturing the same, process cartridge and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charge transport layer optimum for use as a base for a surface protective layer, and to provide an electrophotographic photoreceptor having high durability and stable properties. <P>SOLUTION: A polyester (polyarylate) comprising a diphenyl ether dicarboxylic acid and bisphenol is used as a main component of a charge transport layer which is a base for a surface protective layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, a method for producing an electrophotographic photosensitive member, a process cartridge having an electrophotographic photosensitive member, and an electrophotographic apparatus.

  Photoconductive materials (charge generation materials and charge transport materials) used for electrophotographic photoreceptors mounted on electrophotographic apparatuses include inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide. However, organic photoconductive substances are actively developed from the viewpoints of pollution-free, high productivity, and ease of material design.

  An electrophotographic photosensitive member (organic electrophotographic photosensitive member) using an organic photoconductive substance is obtained by applying a coating liquid obtained by dissolving and dispersing an organic photoconductive substance or a binder resin in a solvent on a support, Those having a photosensitive layer formed by drying this are usually used. The layer structure of the photosensitive layer is generally a laminate type (normal layer type) in which a charge generation layer and a charge transport layer are laminated in this order from the support side.

An electrophotographic photoreceptor using an organic photoconductive material has the above-mentioned advantages, but does not satisfy all the characteristics required for an electrophotographic photoreceptor at a high level. In particular, the outermost surface layer of the electrophotographic photosensitive member is required to have durability against various external electrical and mechanical forces applied by the electrophotographic process. Specifically, the surface of the photoconductor deteriorates due to charging, so that there are problems such as deterioration in image characteristics and cleanability, and wear and scratches caused by rubbing against various members and paper. It is desired to further improve the durability of the layer. Here, as a method for improving the durability of the electrophotographic photosensitive member, a number of techniques for providing a surface protective layer on the outermost surface of the electrophotographic photosensitive member have been reported (for example, Patent Document 1). However, when providing a surface protective layer, the sensitivity decreases due to the decrease in transmittance as the film thickness increases, and the electrical characteristics decrease due to the increase in the interface as the constituent layers increase, especially during repeated use. Since adverse effects such as deterioration of potential stability occur, it is difficult to achieve both improvement in mechanical strength (durability) and electrical characteristics by laminating a surface protective layer.
JP 2001-166521 A

  By providing a surface protective layer to improve the durability of the electrophotographic photosensitive member, adverse effects such as deterioration of transmittance and potential stability occur. Accordingly, an object of the present invention is to provide an electrophotographic photosensitive member that does not have such an adverse effect even when a surface protective layer is provided and has both mechanical strength and electrical characteristics, that is, as a base for the surface protective layer. It is to realize an optimal charge transport layer. In the present invention, the surface protective layer means the outermost surface layer of the photoreceptor laminated on the charge transport layer regardless of the presence or absence of the charge transport material.

  Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member, and a manufacturing method thereof.

  The present invention provides an electrophotographic photosensitive member having a charge generation layer, a charge transport layer, and a surface protective layer in this order on a conductive support, wherein the charge transport layer has at least a repeating structural unit represented by the following formula (1): An electrophotographic photosensitive member comprising a polyarylate resin and a charge transporting substance.

(In Formula (1), R < ¹¹ > -R < ¹⁸ > and R < ²¹ > -R < ²⁸ > show a hydrogen atom, a C1-C4 alkyl group, an aryl group, or a C1-C3 alkoxy group each independently. X represents a single bond, an oxygen atom, a sulfur atom, or a divalent group represented by the following formula (2).)

(In Formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group. Alternatively, R ³¹ and R ³² are combined to form. A cycloalkylidene group or a fluorenylidene group.

  The present invention also provides a method for producing an electrophotographic photosensitive member having a charge generation layer, a charge transport layer, and a surface protective layer in this order on a conductive support, wherein the charge transport layer is at least represented by the above formula (1). It is a method for producing an electrophotographic photoreceptor, which is formed by a coating solution containing a polyarylate resin having a structural unit and a charge transporting substance.

  The present invention also provides a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

  According to the present invention, an electrophotographic photoreceptor excellent in mechanical strength and electrical characteristics, and a process cartridge and an electrophotographic apparatus having the electrophotographic photoreceptor can be provided.

  The polyarylate resin in the present invention is characterized by containing at least a repeating structural unit represented by the following formula (1).

(In Formula (1), R < ¹¹ > -R < ¹⁸ > and R < ²¹ > -R < ²⁸ > show a hydrogen atom, a C1-C4 alkyl group, an aryl group, or a C1-C3 alkoxy group each independently. X represents a single bond, an oxygen atom, a sulfur atom, or a divalent group represented by the following formula (2).)

(In Formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group. Alternatively, R ³¹ and R ³² are combined to form. A cycloalkylidene group or a fluorenylidene group.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^{11 to} R ¹⁸ and R ^{21 to} R ²⁸ in the above formula (1) include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkoxy group 1-3 include a methoxy group, an ethoxy group, and a propoxy group, and examples of the aryl group include a phenyl group and a naphthyl group. Among these, a methyl group, an ethyl group, and a methoxy group An ethoxy group and a phenyl group are preferable. In particular, R ²¹ and R ²⁶ are preferably methyl groups.

Examples of the alkyl group represented by R ³¹ and R ³² in the above formula (2) include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the fluorinated alkyl group include a trifluoromethyl group and a pentafluoro group. Examples include an ethyl group, examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the aryl group include a phenyl group and a naphthyl group. Among these, a methyl group , Ethyl group, propyl group (particularly isopropyl group), trifluoromethyl group, and pentafluoroethyl group are preferable.

Examples of the cycloalkylidene group formed by combining R ³¹ and R ³² in the above formula (2) include a cyclopentylidene group, a cyclohexylidene group, and a cycloheptylidene group. Among these, a cyclohexylidene group is preferable.

  Specific examples of the repeating structural unit represented by the above formula (1) are shown below.

  The polyarylate resin used in the charge transport layer of the electrophotographic photoreceptor of the present invention contains the repeating structural unit represented by the above formula (1), and the content ratio is arbitrary, but the charge transport material and various additions From the viewpoint of improving compatibility with the agent, the repeating structural unit represented by the above formula (1) is preferably 60% or more and 100% or less in terms of molar ratio in all repeating structural units in the polyarylate resin. It is more preferable that it is not less than 100% and not more than 100%.

  The polyarylate resin having a repeating structural unit represented by the above formula (1) used for the charge transport layer of the electrophotographic photosensitive member of the present invention is a specific repeating structural unit selected from the above formula (1). And other repeating structural units selected from the above formula (1), or a copolymer of another divalent carboxylic acid and a repeating structural unit composed of a divalent organic residue. . In this case, the polymerization form may be a polymerization form such as block copolymerization or random copolymerization and is arbitrary, but a random copolymerization form is preferred.

  Further, in the present invention, the specific repeating structural unit selected in the above formula (1), the other repeating structural units selected in the above formula (1), or other divalent carboxylic acids. The description that the copolymerization ratio in terms of molar ratio of the copolymerized polyarylate resin having a repeating structural unit composed of an acid and a divalent organic residue is A: B is a specific formula selected from the above formula (1). The dicarboxylic acid ester moiety shown in the repeating structural unit is (1-C), the bisphenol moiety is (1-B), another repeating structural unit selected from the above formula (1), or other divalent carboxylic acid When the dicarboxylic acid ester moiety shown in the repeating structural unit consisting of an acid and a divalent organic residue is (3-C) and the bisphenol moiety is (3-B), the dicarboxylic acid ester moiety in terms of molar ratio is (1-C) :( 3-C) is the copolymerization ratio A: B, and (1-B) :( 3-B) in the bisphenol moiety in terms of molar ratio is the copolymerization ratio A: B. It shows that there is.

  Examples of the divalent carboxylic acid used in the repeating structural unit composed of the other divalent carboxylic acid and the divalent organic residue include terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, naphthalenedicarboxylic acid, 3,4 Aromatic divalent carboxylic acids such as' -diphenyl ether dicarboxylic acid and 3,3'-diphenyl ether dicarboxylic acid, linear aliphatic divalent carboxylic acids such as succinic acid, adipic acid, sebacic acid and dodecanoic acid, and cyclic such as cyclohexylene dicarboxylic acid Aliphatic divalent carboxylic acids and the like can be mentioned, among which terephthalic acid, isophthalic acid, adipic acid and sebacic acid are preferable. Examples of the divalent organic residue include bisphenols such as 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) and 2,2-bis (3-methyl-4-hydroxyphenyl) propane (bisphenol C), Biphenols such as 4,4′-hydroxybiphenyl are included. Specific examples of repeating structural units composed of other divalent carboxylic acids and divalent organic residues are shown below.

  The weight average molecular weight (MW) of the polyarylate resin having the repeating structural unit represented by the above formula (1) used in the charge transport layer of the electrophotographic photoreceptor of the present invention is arbitrary, but the weight average molecular weight is 80000 or more. In some cases, the effect of improving the compatibility with the charge transporting substance and forming a good interface with the surface protective layer is exhibited.

  On the other hand, when the molecular weight of the polyarylate resin having the repeating structural unit represented by the above formula (1) is too large, the coating property of the coating liquid containing this may be deteriorated. The weight average molecular weight (MW) of the polyarylate resin having a repeating structural unit is preferably 300,000 or less, particularly preferably 200,000 or less.

  The polyarylate resin having a repeating structural unit represented by the above formula (1) used in the charge transport layer or the charge transport layer coating solution of the electrophotographic photosensitive member of the present invention has a hydroxyl group such as a dicarboxylic acid ester and bisphenol. It can be synthesized by a transesterification method with a compound, and can also be synthesized by a polymerization reaction between a divalent acid halide such as a dicarboxylic acid halide and a compound having a hydroxyl group such as bisphenol. In order to produce a product having a weight average molecular weight (MW) in the above range, the latter synthesis method is preferred.

[Synthesis Example 1]
Hereinafter, as a synthesis example, a method for synthesizing a polyarylate resin in which 100% in terms of molar ratio among all the repeating structural units in the polyarylate resin is a repeating structural unit represented by the above formula (1-2) is shown.

  The following formula (A)

Diphenyl ether dicarboxylic acid chloride having a structure represented by the following formula was dissolved in dichloromethane to prepare an acid chloride solution.

  In addition to the acid chloride solution, the following formula (B)

2,2-bis (3-methyl-4-hydroxyphenyl) propane having a structure represented by the following formula is dissolved in a 10% aqueous sodium hydroxide solution, and tributylbenzylammonium chloride as a polymerization catalyst is added thereto and stirred: A 2,2-bis (3-methyl-4-hydroxyphenyl) propane solution was prepared.

  Next, the acid chloride solution was added to the 2,2-bis (3-methyl-4-hydroxyphenyl) propane solution with stirring to initiate polymerization. The polymerization was carried out for 3 hours while maintaining the reaction temperature at 25 ° C. or lower and stirring.

  Thereafter, the polymerization reaction was terminated by the addition of acetic acid, and washing with water was repeated until the aqueous phase became neutral.

  After washing, the solution was dropped into methanol with stirring to precipitate a polymer, and this polymer was vacuum-dried to obtain a polyarylate resin having a repeating structural unit represented by the above formula (1-2). This polyarylate resin had a weight average molecular weight in terms of polystyrene (denoted as “weight average molecular weight (MW)” in the present specification) of 130,000.

[Synthesis Example 2]
Below, as a synthesis example, in all repeating structural units in the polyarylate resin, 70% in terms of molar ratio is a repeating structural unit represented by the above formula (1-2), and 30% is represented by the above formula (3-9). The synthesis method of the polyarylate resin which is a repeating structural unit shown by this is shown.

  Diphenyl ether dicarboxylic acid chloride having the structure represented by the above formula (A), and the following formula (C):

Was mixed at a molar ratio of 7: 3 and dissolved in dichloromethane to prepare a mixed solution of diphenyl ether dicarboxylic acid chloride and terephthalic acid chloride.

  In addition to the acid chloride solution, 2,2-bis (3-methyl-4-hydroxyphenyl) propane having the structure represented by the above formula (B) and the following formula (D)

Is mixed at a molar ratio of 7: 3, dissolved in a 10% aqueous sodium hydroxide solution, tributylbenzylammonium chloride as a polymerization catalyst is added and stirred, and 2,2-bis (3 -Methyl-4-hydroxyphenyl) propane and tetramethylbiphenol mixed solution was prepared.

  Next, the acid chloride solution was added to 2,2-bis (3-methyl-4-hydroxyphenyl) propane and tetramethylbiphenol mixed solution with stirring to initiate polymerization. The polymerization was carried out for 3 hours while maintaining the reaction temperature at 25 ° C. or lower and stirring.

  Thereafter, the polymerization reaction was terminated by the addition of acetic acid, and washing with water was repeated until the aqueous phase became neutral.

  After washing, the solution is added dropwise to methanol with stirring to precipitate a polymer, and this polymer is vacuum-dried. In all the repeating structural units in the polyarylate resin, 70% in terms of molar ratio is represented by the formula (1- A polyarylate resin having the repeating structural unit represented by 2) and 30% of the repeating structural unit represented by the above formula (3-9) was obtained. The weight average molecular weight (MW) of this polyarylate resin was 130,000.

[Synthesis Example 3]
Hereinafter, as a synthesis example, in all repeating structural units in the polyarylate resin, 70% in terms of molar ratio is a repeating structural unit represented by the above formula (1-2), and 30% is represented by the above formula (3-13). The synthesis method of the polyarylate resin which is a repeating structural unit shown by this is shown.

  Diphenyl ether dicarboxylic acid chloride having the structure represented by the above formula (A), and the following formula (E):

Were mixed at a molar ratio of 7: 3 and dissolved in dichloromethane to prepare a mixed solution of diphenyl ether dicarboxylic acid chloride and isophthalic acid chloride. Separately from the acid chloride solution, 2,2-bis (3-methyl-4-hydroxyphenyl) propane having the structure represented by the formula (B) is dissolved in a 10% aqueous sodium hydroxide solution. Then, tributylbenzylammonium chloride was added as a polymerization catalyst and stirred to prepare a 2,2-bis (3-methyl-4-hydroxyphenyl) propane solution.

  Next, the acid chloride solution was added to the 2,2-bis (3-methyl-4-hydroxyphenyl) propane solution with stirring to initiate polymerization. The polymerization was carried out for 3 hours while maintaining the reaction temperature at 25 ° C. or lower and stirring.

  Thereafter, the polymerization reaction was terminated by addition of acetic acid, and washing with water was repeated until the aqueous phase became neutral.

  After washing, the solution is added dropwise to methanol with stirring to precipitate a polymer, and this polymer is vacuum-dried. In all the repeating structural units in the polyarylate resin, 70% in terms of molar ratio is represented by the formula (1- A polyarylate resin having a repeating structural unit represented by 2) and 30% of a repeating structural unit represented by the above formula (3-13) was obtained. The weight average molecular weight (MW) of this polyarylate resin was 120,000.

  In the present invention, the weight average molecular weight of the resin is measured as follows according to a conventional method.

  That is, the measurement target resin is put in tetrahydrofuran and allowed to stand for several hours, and then mixed well with the measurement target resin and tetrahydrofuran while shaking (mixed until the measurement target resin is no longer united), and then allowed to stand for 12 hours or more. .

  Then, the sample processed filter Mysholy disk H-25-5 made by Tosoh Corporation was used as a sample for GPC (gel permeation chromatography).

  Next, the column is stabilized in a heat chamber at 40 ° C., tetrahydrofuran is flowed through the column at this temperature at a flow rate of 1 ml / min, 10 μl of GPC sample is injected, and the weight average molecular weight of the measurement target resin Was measured. A column TSKgel Super HM-M manufactured by Tosoh Corporation was used as the column.

  In measuring the weight average molecular weight (MW) of the measurement target resin, the molecular weight distribution of the measurement target resin was calculated from the relationship between the logarithmic value of the calibration curve created by several monodisperse polystyrene standard samples and the count number. . Ten standard polystyrene samples for preparing a calibration curve were used from Aldrich monodisperse polystyrene having a molecular weight of 800 to 2,000,000. An RI (refractive index) detector was used as the detector.

  The coating solution for forming the charge transport layer of the electrophotographic photoreceptor of the present invention is a mixture of the polyarylate resin of the present invention, a charge transporting substance, and a solvent mixed and stirred. Moreover, you may add various additives, such as a leveling agent, antioxidant, a plasticizer, to this coating liquid as needed.

  When the charge transport layer of the present invention is formed, the photoreceptor is formed by applying the above-described coating solution. Solvents used at this time include ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as methyl acetate and ethyl acetate, aromatic hydrocarbon solvents such as toluene, xylene and chlorobenzene, 1,4-dioxane, tetrahydrofuran and the like. And ether solvents, hydrocarbon solvents substituted with halogen atoms such as chloroform, and the like. These solvents may be used alone or in combination of two or more. Among these solvents, it is preferable to use at least an ether solvent from the viewpoint of resin solubility and the like.

  Next, the configuration of the electrophotographic photosensitive member of the present invention will be described.

  The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a support and a photosensitive layer provided on the support, and the structure thereof includes a charge generation layer containing a charge generation material and a charge transporting material. A layered type (functionally separated type) separated into a charge transporting layer, and a normal layered photosensitive layer in which a charge generating layer and a charge transporting layer are laminated in this order from the support side. Further, on the charge transport layer, a surface protective layer is provided for the purpose of protecting the photosensitive layer or imparting surface properties.

  The support is only required to have conductivity, and specifically, a support made of metal (made of alloy) such as aluminum, an aluminum alloy, and stainless steel can be used. Moreover, the said metal support body and plastic support body which have a layer in which aluminum, an aluminum alloy, an indium oxide tin oxide alloy etc. were formed into a film by vacuum deposition can also be used. In addition, a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles, and silver particles are impregnated into plastic or paper together with an appropriate binder resin, or a plastic support having a conductive binder resin, etc. Can also be used. In addition, examples of the shape of the support include a cylindrical shape and a belt shape, and a cylindrical shape is preferable.

  The surface of the support may be subjected to cutting treatment, roughening treatment, anodizing treatment, etc. for the purpose of preventing interference fringes due to scattering of laser light or the like.

  Between the support and the photosensitive layer (charge generation layer, charge transport layer) or an intermediate layer described later, there is a conductive layer for the purpose of preventing interference fringes due to scattering of laser light or the like and for coating the scratch on the support. It may be provided.

  The conductive layer can be formed by dispersing conductive particles such as carbon black, metal particles, and metal oxide particles in a binder resin.

  The thickness of the conductive layer is preferably 1 μm or more and 40 μm or less, and particularly preferably 2 μm or more and 20 μm or less.

  Further, an intermediate layer having a barrier function or an adhesive function may be provided between the support or the conductive layer and the photosensitive layer (charge generation layer, charge transport layer). The intermediate layer is formed for the purpose of improving the adhesion of the photosensitive layer, improving the coating property, improving the charge injection property from the support, and protecting the photosensitive layer from electrical breakdown.

  The intermediate layer is acrylic resin, allyl resin, alkyd resin, ethyl cellulose resin, ethylene-acrylic acid copolymer, epoxy resin, casein resin, silicone resin, gelatin resin, polyamide resin, phenol resin, butyral resin, polyacrylate resin, polyacetal resin, Polyamideimide resin, polyallyl ether resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl alcohol resin, polybutadiene resin, polypropylene resin, urea resin, aluminum oxide, etc. It can be formed using the material.

  The thickness of the intermediate layer is preferably 0.05 μm or more and 5 μm or less, and more preferably 0.3 μm or more and 1 μm or less.

  Examples of the charge generating material used in the electrophotographic photoreceptor of the present invention include azo pigments such as monoazo, disazo, and trisazo, phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine, indigo pigments such as indigo and thioindigo, Perylene pigments such as perylene anhydride, perylene imide, polycyclic quinone pigments such as anthraquinone, pyrenequinone, dibenzpyrenequinone, squarylium dyes, pyrylium salts and thiapyrylium salts, triphenylmethane dyes, selenium, Inorganic substances such as selenium-tellurium and amorphous silicon, quinacridone pigments, azurenium salt pigments, cyanine dyes such as quinocyanine, anthanthrone pigments, pyranthrone pigments, xanthene dyes, quinoneimine dyes, styryl Motoya, and cadmium sulfide, and zinc oxide. These charge generation materials may be used alone or in combination of two or more.

  Examples of the binder resin used for the charge generation layer include acrylic resin, allyl resin, alkyd resin, epoxy resin, diallyl phthalate resin, silicone resin, styrene-butadiene copolymer, polyamide resin, phenol resin, butyral resin, benzal resin, Polyacrylate resin, polyacetal resin, polyamideimide resin, polyallyl ether resin, polyarylate resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl acetal resin, polybutadiene resin, polypropylene resin Methacrylic resin, urea resin, vinyl chloride-vinyl acetate copolymer, vinyl acetate resin, vinyl chloride resin and the like. In particular, a butyral resin is preferable. These can be used singly or in combination of two or more as a mixture or copolymer.

  The charge generation layer can be formed by applying a charge generation layer coating solution obtained by dispersing a charge generation material together with a binder resin and a solvent and drying the coating solution. Examples of the dispersion method include a method using a homogenizer, an ultrasonic disperser, a ball mill, a sand mill, a roll mill, a vibration mill, an attritor, a liquid collision type high-speed disperser, and the like. The ratio between the charge generation material and the binder resin is preferably in the range of 1: 4 or more and 1: 0.3 or less (mass ratio).

  The solvent used in the coating solution for the charge generation layer is selected from the solubility and dispersion stability of the binder resin and charge generation material to be used. As the organic solvent, alcohol, sulfoxide, ketone, ether, ester, aliphatic Examples thereof include halogenated hydrocarbons and aromatic compounds.

  The thickness of the charge generation layer is preferably 5 μm or less, and more preferably 0.1 μm or more and 2 μm or less.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and the like can be added to the charge generation layer as necessary.

  Examples of the charge transporting substance used in the electrophotographic photosensitive member of the present invention include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triarylmethane compounds and the like. . These charge transport materials may be used alone or in combination of two or more.

  In the charge transport layer, at least a polyarylate resin having a repeating structural unit represented by the above formula (1) is used as a binder resin. Other resins exemplified below can be used in combination as long as the effects of the present invention are not impaired. In that case, the polyarylate resin having a repeating structural unit represented by the above formula (1) in the charge transport layer is used. The ratio is preferably 50% by mass or more, more preferably 70% by mass or more, based on the total mass of the binder resin contained in the charge transport layer. Examples of resins that can be used in combination include acrylic resins, acrylonitrile resins, allyl resins, alkyd resins, epoxy resins, silicone resins, polyamide resins, phenol resins, phenoxy resins, butyral resins, polyacrylamide resins, polyacetal resins, polyamideimide resins, Polyallyl ether resin, polyarylate resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polysulfone resin, polyvinyl butyral resin, polyphenylene oxide resin, polybutadiene resin, polypropylene resin, methacrylic resin, urea resin, A vinyl chloride resin, a vinyl acetate resin, etc. are mentioned. In particular, polyarylate resin, polycarbonate resin and the like are preferable. These can be used singly or in combination of two or more as a mixture or copolymer.

  The charge transport layer can be formed by applying a charge transport layer coating solution obtained by dissolving a charge transport material and a binder resin in a solvent, and drying it. The ratio between the charge transporting substance and the binder resin is preferably in the range of 1: 2 to 2: 1 (mass ratio).

  Solvents used in the coating solution for the charge transport layer include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, ethers such as 1,4-dioxane and tetrahydrofuran, Hydrocarbons substituted with halogen atoms such as chlorobenzene, chloroform and carbon tetrachloride are used.

  The thickness of the charge transport layer is preferably 5 μm or more and 40 μm or less, and more preferably 10 μm or more and 35 μm or less.

  In addition, an antioxidant, an ultraviolet absorber, a plasticizer, and the like can be added to the charge transport layer as necessary.

  A surface protective layer for protecting the photosensitive layer is laminated on the photosensitive layer. The surface protective layer can be formed by applying a coating solution for the surface protective layer obtained by dissolving the binder resin in a solvent, and drying or curing it, and also has a charge transporting function having a chain polymerizable functional group. It can also be formed by applying a coating solution for a surface protective layer obtained by dissolving a functional substance in a solvent and curing it.

  The thickness of the surface protective layer is preferably from 0.5 μm to 10 μm, and particularly preferably from 1 μm to 5 μm.

  When applying the coating liquid for each of the above layers, for example, a coating method such as a dip coating method (dip coating method), a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, a blade coating method, or the like should be used. Can do.

  FIG. 1 shows an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.

  In FIG. 1, reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is rotationally driven in a direction of an arrow about a shaft 2 at a predetermined peripheral speed.

  The surface of the electrophotographic photosensitive member 1 that is rotationally driven is uniformly charged to a predetermined positive or negative potential by a charging unit (primary charging unit: charging roller or the like) 3, and then subjected to slit exposure, laser beam scanning exposure, or the like. Exposure light (image exposure light) 4 output from exposure means (not shown) is received. In this way, electrostatic latent images corresponding to the target image are sequentially formed on the surface of the electrophotographic photosensitive member 1. The exposure means preferably has a laser having an oscillation wavelength in the range of 380 nm to 450 nm.

  The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner contained in the developer of the developing means 5 to become a toner image. Next, the toner image formed and supported on the surface of the electrophotographic photoreceptor 1 is transferred from a transfer material supply means (not shown) to the electrophotographic photoreceptor 1 and the transfer means by a transfer bias from a transfer means (transfer roller or the like) 6. 6 is transferred to a transfer material (paper or the like) 7 taken out and fed in synchronization with the rotation of the electrophotographic photosensitive member 1.

  The transfer material 7 that has received the transfer of the toner image is separated from the surface of the electrophotographic photosensitive member 1 and is introduced into the fixing means 8 to be image-fixed to be printed out as an image formed product (print, copy). Is done.

  The surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is cleaned by a cleaning means (cleaning blade or the like) 9 to remove the developer (toner) remaining after transfer, and further from a pre-exposure means (not shown). After being subjected to static elimination treatment with the pre-exposure light (10), it is repeatedly used for image formation. As shown in FIG. 1, when the charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not necessarily required.

  Among the above-described components such as the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, the transfer unit 6, and the cleaning unit 7, a plurality of components are housed in a container and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. In FIG. 1, an electrophotographic photosensitive member 1, a charging unit 3, a developing unit 5 and a cleaning unit 9 are integrally supported to form a cartridge, and an electrophotographic apparatus is used using a guide unit 12 such as a rail of the electrophotographic apparatus main body. The process cartridge 11 is detachable from the main body.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these. In the examples, “part” means “part by mass”. “MW” means “weight average molecular weight (MW)”.

[Example 1]
An aluminum cylinder having a diameter of 30 mm and a length of 260.5 mm was used as a support.

Next, SnO ₂ -coated barium sulfate (conductive particles) 10 parts, titanium oxide (resistance control pigment) 2 parts, phenol resin (binder resin) 6 parts, silicone oil (leveling agent) 0.001 part and methanol A conductive layer coating solution was prepared using a mixed solvent of 4 parts / 16 parts of methoxypropanol.

  This conductive layer coating solution was dip-coated on a support and thermally cured at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 15 μm.

  Next, an intermediate layer coating solution was prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol.

  This intermediate layer coating solution was dip-coated on the conductive layer and dried at 100 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.7 μm.

  Next, strong peaks at 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 ° with a Bragg angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction 10 parts of a crystalline form of hydroxygallium phthalocyanine (charge generating substance) having the following structure is added to a solution obtained by dissolving 5 parts of polyvinyl butyral resin (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 250 parts of cyclohexanone, Dispersion was performed in a 23 ± 3 ° C. atmosphere for 1 hour with a sand mill using glass beads having a diameter of 1 mm, and after dispersion, 250 parts of ethyl acetate was added to prepare a charge generation layer coating solution. This charge generation layer coating solution was dip coated on the intermediate layer and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.26 μm.

  Next, 50 parts of a polyarylate resin (MW: 130000) having a repeating structural unit represented by the above formula (1-2) and 40 parts of a charge transporting material represented by the following structural formula (F) were added to tetrahydrofuran (THF) 450. Then, a coating solution for charge transport layer was prepared. The charge transport layer coating solution was dip-coated on the charge generation layer and dried at 120 ° C. for 60 minutes to form a charge transport layer having a thickness of 30 μm.

  Furthermore, 25 parts of a polyarylate resin (MW: 130000) having a repeating structural unit represented by the above formula (1-2) and 20 parts of a charge transporting substance represented by the above structural formula (F) are mixed with 900 parts of tetrahydrofuran (THF). To obtain a coating solution for the surface protective layer. The surface protective layer coating solution was dip-coated on the charge transport layer and heat-treated at 120 ° C. for 60 minutes to form a surface protective layer having a thickness of 5 μm.

  This photoconductor (1) was subjected to a 20000 sheet endurance test using a copying machine GP-40 manufactured by Canon Inc. in a normal temperature and humidity environment (23 ° C./55% RH), and image defects were detected. The amount of wear of the photoreceptor was measured. The wear amount of the photoconductor was measured by eddy current measurement (film thickness meter: Fisher Permascope) and interference film thickness meter (manufactured by Otsuka Electronics). Further, the photodischarge characteristics before and after the durability test were measured, and the amount of variation (ΔVr) from the initial stage was obtained. The photodischarge characteristics were evaluated by adjusting the initial charging potential to −700 V, and then irradiating 100 lx white light and measuring the charging potential after 0.5 seconds. Separately, a coating solution for charge transport layer was applied onto a PET film with a Meyer bar so that the film thickness was 20 μm, and the dried film was peeled off, and V-570 (manufactured by JASCO Corporation) was used. The transmittance at a wavelength of 778 nm was measured. The results are shown in Table 2.

  From these results, the photoconductor (1) has a high transmittance, a small amount of wear during repeated use, and a small potential fluctuation, so that stable performance can be exhibited even during repeated use. . That is, it has become clear that a clear image can be stably obtained over a long period without occurrence of image defects such as ghost and fog.

[Example 2-3]
In Example 1, except that the polyarylate resin contained in the charge transport layer was changed to the one shown in Table 1, an electrophotographic photosensitive member and a transmittance measurement sample were prepared in the same manner as in Example 1 and evaluated in the same manner. did. The results are shown in Table 2.

[Comparative Example 1]
In Example 1, except that the polyarylate resin contained in the charge transport layer was changed to the one shown in Table 1, an electrophotographic photoreceptor and a transmittance measurement sample were prepared in the same manner as in Example 1, and the same Evaluated. The results are shown in Table 2.

[Example 4]
Up to the charge transport layer was prepared in the same manner as in Example 1. Next, 25 parts of the polyarylate resin represented by the following structural formula (G) and 20 parts of the charge transporting material represented by the structural formula (F) are dissolved in 900 parts of monochlorobenzene to prepare a coating solution for the surface protective layer. Then, this was dip-coated on the charge transport layer and heat-treated at 120 ° C. for 60 minutes to form a surface protective layer having a film thickness of 5 μm. Thus, a photoconductor 4 and a transmittance measurement sample were produced. This photoreceptor was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Example 5-6]
In Example 4, except that the polyarylate resin contained in the charge transport layer was changed to the one shown in Table 1, an electrophotographic photosensitive member and a transmittance measurement sample were prepared in the same manner as in Example 4 and evaluated in the same manner. did. The results are shown in Table 2.

[Comparative Example 2]
In Example 4, except that the polyarylate resin contained in the charge transport layer was changed to that shown in Table 1, an electrophotographic photosensitive member and a transmittance measurement sample were prepared in the same manner as in Example 4, and the same Evaluated. The results are shown in Table 2.

[Example 7]
Up to the charge transport layer was prepared in the same manner as in Example 1. Next, 1.25 parts of fluorine atom-containing resin (trade name: GF-300, manufactured by Toagosei Co., Ltd.) as a dispersant was added to 1,1,2,2,3,3,4-heptafluorocyclopentane ( Trade name: Zeolora H, manufactured by Nippon Zeon Co., Ltd. 37.5 parts and 1-propanol 37.5 parts, and then tetrafluoroethylene resin powder as lubricant (trade name: Lubron L-2, Daikin) 25 parts of Kogyo Co., Ltd.) was added, and the mixture was uniformly dispersed by applying three treatments at a pressure of 600 kgf / cm ² with a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, USA). This was subjected to pressure filtration with a 10 μm PTFE membrane filter to prepare a lubricant dispersion.

  Next, 100 parts of a charge transporting material represented by the following structural formula (H), 0.5 part of a thermal polymerization initiator represented by the following structural formula (I), 45 parts of a lubricant dispersion, 1, 1, 2, After mixing and stirring 66.7 parts of 2,3,3,4-heptafluorocyclopentane and 66.7 parts of 1-propanol, pressure filtration is performed with a 5 μm membrane filter made of PTFE, and the coating solution for the surface protective layer Was prepared. This coating solution is applied onto the charge transport layer by dip coating, and then heated and cured at 150 ° C. for 60 minutes to form a surface protective layer having a thickness of 5 μm. did. This photoreceptor was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Example 8-9]
In Example 7, except that the polyarylate resin contained in the charge transport layer was changed to that shown in Table 1, an electrophotographic photosensitive member and a transmittance measurement sample were prepared in the same manner as in Example 7, and evaluated in the same manner. did. The results are shown in Table 2.

[Comparative Example 3]
In Example 7, except that the polyarylate resin contained in the charge transport layer was changed to that shown in Table 1, an electrophotographic photoreceptor and a transmittance measurement sample were prepared in the same manner as in Example 7, and the same Evaluated. The results are shown in Table 2.

[Example 10]
Up to the charge transport layer was prepared in the same manner as in Example 1. Next, 1.25 parts of fluorine atom-containing resin (trade name: GF-300, manufactured by Toagosei Co., Ltd.) as a dispersant was added to 1,1,2,2,3,3,4-heptafluorocyclopentane ( Trade name: Zeolora H, manufactured by Nippon Zeon Co., Ltd. 37.5 parts and 1-propanol 37.5 parts, and then tetrafluoroethylene resin powder as lubricant (trade name: Lubron L-2, Daikin) 25 parts of Kogyo Co., Ltd.) was added, and the mixture was uniformly dispersed by applying three treatments at a pressure of 600 kgf / cm ² with a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, USA). This was subjected to pressure filtration with a 10 μm PTFE membrane filter to prepare a lubricant dispersion.

Next, 100 parts of the charge transport material represented by the structural formula (F), 0.5 part of the photopolymerization initiator represented by the following structural formula (J), 45 parts of the lubricant dispersion, 1, 1, 2, After mixing and stirring 66.7 parts of 2,3,3,4-heptafluorocyclopentane and 66.7 parts of 1-propanol, pressure filtration is performed with a 5 μm membrane filter made of PTFE, and the coating solution for the surface protective layer Was prepared. The coating solution is applied on the charge transport layer by a dip coating method, then cured for 60 seconds at a light intensity of 500 mW / cm ² using a metal halide lamp, and then subjected to heat treatment, whereby a surface having a thickness of 5 μm is obtained. A protective layer was formed, and a photoconductor 10 and a transmittance measurement sample were produced. This photoreceptor was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Examples 11-12]
In Example 10, an electrophotographic photosensitive member and a transmittance measurement sample were prepared in the same manner as in Example 10 except that the polyarylate resin contained in the charge transport layer was changed to that shown in Table 1, and evaluated in the same manner. did. The results are shown in Table 2.

[Comparative Example 4]
In Example 10, except that the polyarylate resin contained in the charge transport layer was changed to that shown in Table 1, an electrophotographic photosensitive member and a transmittance measurement sample were prepared in the same manner as in Example 10, and the same Evaluated. The results are shown in Table 2.

[Example 13]
Up to the charge transport layer was prepared in the same manner as in Example 1. Next, 1.25 parts of fluorine atom-containing resin (trade name: GF-300, manufactured by Toagosei Co., Ltd.) as a dispersant was added to 1,1,2,2,3,3,4-heptafluorocyclopentane ( Trade name: Zeolora H, manufactured by Nippon Zeon Co., Ltd. 37.5 parts and 1-propanol 37.5 parts, and then tetrafluoroethylene resin powder as lubricant (trade name: Lubron L-2, Daikin) 25 parts of Kogyo Co., Ltd.) was added, and the mixture was uniformly dispersed by applying three treatments at a pressure of 600 kgf / cm ² with a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, USA). This was subjected to pressure filtration with a 10 μm PTFE membrane filter to prepare a lubricant dispersion.

  Next, 100 parts of the charge transport material represented by the structural formula (H), 45 parts of the lubricant dispersion, 66.7 parts of 1,1,2,2,3,3,4-heptafluorocyclopentane, -After mixing and stirring 66.7 parts of propanol, pressure filtration was performed with a PTFE 5 μm membrane filter to prepare a coating solution for a surface protective layer. This coating solution is applied on the charge transport layer by a dip coating method, and then cured in nitrogen under the conditions of an acceleration voltage of 150 kV and an electron beam dose of 10 kGy, and subsequently the temperature of the photoreceptor is 120 ° C. for 90 seconds. Heat treatment was performed. The oxygen concentration at this time was 10 ppm. Further, the photoconductor was heat-treated in a hot air dryer adjusted to 100 ° C. in the atmosphere for 30 minutes to form a surface protective layer having a thickness of 5 μm, and a photoconductor 13 and a sample for measuring transmittance were produced. . This photoreceptor was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[Examples 14-15]
In Example 13, except that the polyarylate resin contained in the charge transport layer was changed to that shown in Table 1, an electrophotographic photosensitive member and a transmittance measurement sample were prepared in the same manner as in Example 13, and evaluated in the same manner. did. The results are shown in Table 2.

[Comparative Example 5]
In Example 13, except that the polyarylate resin contained in the charge transport layer was changed to that shown in Table 1, an electrophotographic photoreceptor and a transmittance measurement sample were prepared in the same manner as in Example 13, and the same Evaluated. The results are shown in Table 2.

  From the above experimental results, an electrophotographic photoreceptor having a charge transport layer containing a polyarylate resin having a specific structure and having a surface protective layer stably exhibits good performance, and can be used repeatedly. It is possible to supply a clear image.

1 is a schematic view showing an embodiment of a process cartridge having an electrophotographic photosensitive member of the present invention and an electrophotographic apparatus having the process cartridge. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Primary charging means 4 Image exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Image fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Rail

Claims (12)

In an electrophotographic photoreceptor having a charge generation layer, a charge transport layer, and a surface protective layer in this order on a conductive support, a polyarylate resin in which the charge transport layer has at least a repeating structural unit represented by the following formula (1): An electrophotographic photoreceptor comprising a charge transporting substance.

(In Formula (1), R < ¹¹ > -R < ¹⁸ > and R < ²¹ > -R < ²⁸ > show a hydrogen atom, a C1-C4 alkyl group, an aryl group, or a C1-C3 alkoxy group each independently. X represents a single bond, an oxygen atom, a sulfur atom, or a divalent group represented by the following formula (2).)

(In Formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group. Alternatively, R ³¹ and R ³² are combined to form. A cycloalkylidene group or a fluorenylidene group.   2. The electrophotographic photosensitive member according to claim 1, wherein the repeating structural unit represented by the formula (1) is 60% or more and 100% or less in terms of molar ratio in all repeating structural units of the polyarylate resin. .   The electrophotographic photosensitive member according to claim 1, wherein the polyarylate resin has a weight average molecular weight (MW) of 80,000 or more and 300,000 or less. The electrophotographic photosensitive member according to claim 1, wherein R ²¹ and R ^{26 in} the formula (1) are methyl groups.   The electrophotographic photosensitive member according to claim 1, wherein the surface protective layer has a thickness of 1 μm to 10 μm. In the method for producing an electrophotographic photosensitive member having a charge generation layer, a charge transport layer, and a surface protective layer in this order on a conductive support, the charge transport layer is a polymer having at least a repeating structural unit represented by the following formula (1). A method for producing an electrophotographic photosensitive member, comprising forming a coating solution containing an arylate resin and a charge transporting substance.

(In Formula (1), R < ¹¹ > -R < ¹⁸ > and R < ²¹ > -R < ²⁸ > show a hydrogen atom, a C1-C4 alkyl group, an aryl group, or a C1-C3 alkoxy group each independently. X represents a single bond, an oxygen atom, a sulfur atom, or a divalent group represented by the following formula (2).)

(In Formula (2), R ³¹ and R ³² each independently represent a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alkoxy group, or an aryl group. Alternatively, R ³¹ and R ³² are combined to form. A cycloalkylidene group or a fluorenylidene group.   The electrophotographic photosensitive member according to claim 6, wherein the repeating structural unit represented by the formula (1) is 60% or more and 100% or less in terms of molar ratio in all repeating structural units of the polyarylate resin. Manufacturing method.   The method for producing an electrophotographic photosensitive member according to claim 6, wherein the polyarylate resin has a weight average molecular weight (MW) of 80000 to 300,000. The method for producing an electrophotographic photosensitive member according to claim 6, wherein R ²¹ and R ^{26 in} the formula (1) are methyl groups.   6. The electrophotographic photosensitive member according to claim 1 and at least one unit selected from the group consisting of a charging unit, a developing unit, and a cleaning unit are integrally supported, and are detachable from the electrophotographic apparatus. A process cartridge characterized by that.   An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit.   The electrophotographic apparatus according to claim 11, wherein the exposure unit includes a laser having an oscillation wavelength in a range of 380 nm to 450 nm.