JP5065865B2 - Electrophotographic photosensitive member, image forming apparatus, and process cartridge for image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member having high durability and high image quality over a long period of time by using a photosensitive layer having high wear resistance and good electrical characteristics. The present invention also relates to an image forming apparatus and a process cartridge for the image forming apparatus using the long-life and high-performance photoconductor.

  In recent years, organic photoconductors (OPCs) have been widely used in copying machines, facsimiles, laser printers, and their combined machines instead of inorganic photoconductors because of their good performance and various advantages. This is because, for example, (1) optical characteristics such as the light absorption wavelength range and the amount of absorption, (2) electrical characteristics such as high sensitivity and stable charging characteristics, and (3) material selection range (4) Ease of manufacturing, (5) Low cost, (6) Non-toxicity, and the like.

On the other hand, the diameter of the photoreceptor has recently been reduced due to the downsizing of the image forming apparatus, and the high speed of the machine and the maintenance-free movement have been added. From this point of view, the organic photoreceptor is generally soft because the surface layer is mainly composed of a low molecular charge transport material and an inert polymer, and when it is repeatedly used in an electrophotographic process, it is a machine using a development system or a cleaning system. It has the disadvantage of being easily worn by a typical load. In addition, due to the demand for high image quality, the rubber hardness of the cleaning blade and the contact pressure must be increased for the purpose of improving the cleaning property as the particle size of the toner particles is reduced. As a result, it is a factor that promotes wear of the photoreceptor. Such abrasion of the photoreceptor deteriorates electrical characteristics such as sensitivity deterioration and chargeability, and causes abnormal images such as image density reduction and background stains. Also, locally worn scratches cause streak-like stain images due to poor cleaning. Under the present circumstances, the wear and scratches are rate-determined and the life of the photoconductor has been replaced.
Therefore, it is indispensable to reduce the above-mentioned wear amount in order to increase the durability of the organic photoreceptor, and this is the most pressing issue in this field.
Techniques for improving the abrasion resistance of the photosensitive layer include (i) using a curable binder for the surface layer (for example, see Patent Document 1), and (ii) using a polymer type charge transport material (for example, , Patent document 2), (iii) those in which an inorganic filler is dispersed in the surface layer (for example, see patent document 3), and the like.

  Among these techniques, the one using the curable binder (i) has poor compatibility with the charge transport material, or the residual potential increases due to impurities such as a polymerization initiator and unreacted residues, resulting in an image density. There is a tendency for the reduction to occur easily. In addition, the material using the polymer type charge transport material (ii) can improve the abrasion resistance to some extent, but to fully satisfy the durability required for the organic photoreceptor. Not reached. In addition, polymer charge transport materials are difficult to polymerize and purify, and it is difficult to obtain high-purity ones. Therefore, it is difficult to stabilize electrical characteristics between materials. Furthermore, production problems such as high viscosity of the coating solution may occur. The dispersion in which the inorganic filler of (iii) is dispersed exhibits higher wear resistance than a photoreceptor in which a normal low molecular charge transport material is dispersed in an inert polymer, but a trap present on the surface of the inorganic filler. As a result, the residual potential rises and the image density tends to decrease. In addition, when the unevenness of the inorganic filler and the binder resin on the surface of the photoconductor is large, defective cleaning may occur, which may cause toner filming and image flow. The technologies (i), (ii), and (iii) sufficiently satisfy the overall durability including the electrical durability and mechanical durability required for the organic photoreceptor. It has not reached.

Furthermore, in order to improve the abrasion resistance and scratch resistance of (i), a photoreceptor containing a polyfunctional acrylate monomer cured product is also known (see Patent Document 4).
However, in this photoreceptor, although there is a description that the polyfunctional acrylate monomer cured product is contained in the protective layer provided on the photosensitive layer, it is possible that the protective layer may contain a charge transport material. It is only described and there is no more specific description. Moreover, when a low-molecular charge transport material is simply included in the surface layer, there is a problem of compatibility with the cured product, which causes precipitation of a low-molecular charge transport material and white turbidity, resulting in mechanical strength. May also be reduced.
Furthermore, since this photoconductor specifically reacts with the monomer in a state containing a polymer binder, curing does not proceed sufficiently, and there is a problem that the compatibility between the cured product and the binder resin is poor. There was a tendency for surface irregularities due to phase separation during curing, leading to poor cleaning.

  As an alternative anti-wear technology for photosensitive layers, a charge transport layer using a coating solution comprising a monomer having a carbon-carbon double bond, a charge transport material having a carbon-carbon double bond, and a binder resin is known. (For example, see Patent Document 5). This binder resin includes those having a carbon-carbon double bond and having reactivity with the charge transport material, and those having no double bond as described above and not having reactivity. . This photoconductor has both wear resistance and good electrical properties. However, when a non-reactive binder resin is used, the reaction between the binder resin, the monomer and the charge transport material is performed. Due to the poor compatibility with the cured product produced by the above method, a charge transport layer having a uniform thickness cannot be formed, and the surface has irregularities, which tends to cause poor cleaning. In addition, as described above, in this case, the binder resin prevents a uniform curing reaction between the monomer and the charge transport material, and what is specifically described as the monomer used in the photoreceptor is bifunctional. belongs to. With this bifunctional monomer, the number of functional groups is small and a sufficient crosslinking density cannot be obtained, and these points have not yet been satisfactory in terms of wear resistance. Further, even when a reactive binder is used, it is difficult to achieve both the binding amount and the crosslinking density of the charge transport material because of the low number of functional groups contained in the monomer and the binder resin, Electrical properties and wear resistance are not sufficient.

  A photosensitive layer containing a compound obtained by curing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule is also known (see, for example, Patent Document 6). Also known is a photoreceptor for wet development of a charge transport material having a vinyl group and polycarbonate (for example, see Patent Document 7).

JP 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent No. 3262488 Japanese Patent No. 3194392 JP 2000-66425 A JP 2005-128491 A

  The present invention has high abrasion resistance, high scratch resistance and good electrical characteristics, and particularly excellent smoothness of the film by uniform curing over the entire cross-linked surface layer. By forming a layer, it is an object to provide an electrophotographic photoreceptor that has good cleaning characteristics, high durability, and high image quality over a long period of time. Another object of the present invention is to provide an image forming apparatus and a process cartridge for the image forming apparatus using the long-life and high-performance photoconductor.

The above-mentioned subject is made by the solving means of the present invention described below.
( 1 ) An electrophotographic photoreceptor comprising a layer formed by a cross-linking reaction between a charge transporting material having a vinyl group represented by the following general formula 1 and a polyester represented by the following general formula 2. .

(In the above formula, Ar ¹ represents a substituted or unsubstituted aryl group, and R ¹ and R ² each independently represents a branched or straight chain alkyl group, an allyl group, a halogen, a substituted or unsubstituted aryl group. H and i are integers of 0 to 2 (but they are not simultaneously 0), m and l are integers of 0 to 2, and n is 15 to 1000. )
( 2 ) An electrophotographic photoreceptor comprising a layer formed by a crosslinking reaction between a charge transport material having a vinyl group represented by the following general formula 3 and a polyester represented by the following general formula 2. .

(In the above formula, Ar ² and Ar ³ represent a substituted or unsubstituted aryl group, and R ¹ and R ² are each independently a branched or straight chain alkyl group, an allyl group, a halogen atom, a substituted or unsubstituted group. X represents a single bond, —O—, —CO—, or any one of the following general formula 4 (in general formula 4, R ³ represents hydrogen, 5 represents an alkyl group of 5 or a substituted or unsubstituted aryl group), a is an integer of 1 to 2, m and l are integers of 0 to 2, and n is 15 to 1000.

( 3 ) An electrophotographic photoreceptor comprising a layer formed by a crosslinking reaction between a charge transport material having a vinyl group represented by the following general formula 5 and a polyester represented by the following general formula 2. .

(In the above formula, Ar ⁴ represents a substituted or unsubstituted aryl group, and R ¹ and R ² each independently represents a branched or straight chain alkyl group, an allyl group, a halogen atom, a substituted or unsubstituted aryl group. And b and c are integers of 1 to 2, m and l are integers of 0 to 2, and n is an integer of 15 to 1000. Y and Z are each independently a single bond, —O. -, -CO-, or one represented by the following general formula 4 (in the general formula 4, R ³ represents either a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a substituted or unsubstituted aryl group. To express).)

( 4 ) An electrophotographic photosensitive member comprising a layer formed by a crosslinking reaction between a charge transport material having a vinyl group represented by the following general formula 6 and a polyester represented by the following general formula 2. .

(In the above formula, Ar ⁵ and Ar ⁶ each independently represent a substituted or unsubstituted aryl group, and R ¹ and R ² each independently represent a branched or straight chain alkyl group, allyl group, halogen, It represents either a substituted or unsubstituted aryl group, d and e are integers of 1 to 2, m and l are integers of 0 to 2, and n is 15 to 1000.)

( 5 ) The electrophotographic photosensitive member according to any one of (1) to ( 4 ), wherein the layer formed by the crosslinking reaction is a surface layer.
( 6 ) An image forming apparatus comprising at least a charging unit, an image exposing unit, a developing unit, a transferring unit, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is any one of (1) to ( 5 ). What is claimed is: 1. An image forming apparatus comprising:
(7 wherein (1) to (5) all the electrophotographic photosensitive member according to either charging means, developing means, integrally supports at least one more selected cleaning unit, detachably attached to the image forming apparatus main body A process cartridge for an image forming apparatus.

  As will be apparent from the disclosure of the specific invention described below, the present invention provides high wear resistance, high scratch resistance, good electrical properties, and particularly over the entire cured surface layer. Electrophotography that has excellent film smoothness due to uniform curing, has a clear cured surface layer, and has good cleaning characteristics, high durability, and high image quality over a long period of time A photoreceptor can be provided. Further, according to the present invention, it is possible to provide an image forming method, an image forming apparatus, and a process cartridge for the image forming apparatus using those long-life, high-performance photoconductors.

The electrophotographic photosensitive member of the present invention is provided with a layer (cured layer) formed by a crosslinking reaction between a charge transport material having a vinyl group and a polyester having a cyclohexyl group bonded to the main chain. . This hardened layer is preferably the outermost surface.
As a result of intensive studies, the inventors of the present invention have a layer formed by a crosslinking reaction (preferably a thermal crosslinking reaction) between a charge transport material having at least a vinyl group and a polyester having a cyclohexyl group bonded to the main chain. It has been found that the photosensitive film has high mechanical strength and is particularly useful as a surface layer of a photoreceptor. Although detailed examination of this cross-linking reaction has not been made, it is considered that the vinyl group and the 4-position of the cyclohexyl ring react with each other to form a cross-linking reaction between the polyesters. After the reaction, the formed film becomes insoluble in the solvent, washed with THF a coating solvent Looking Infrared absorption spectrum of the film, the absorption around 1740 cm ^-1 derived from polyester, and the charge transport material derived ^{1600 cm} -1, absorption near 1500 cm ^-1 is changed before and after reaction (see Figure 5-7).

[Charge transport material having a vinyl group represented by general formula 1]
The charge transport material having a vinyl group of the present invention is a compound represented by the following general formula 1.

(In the above formula, Ar ¹ represents a substituted or unsubstituted aryl group, and R ¹ and R ² each independently represents a branched or straight chain alkyl group, an allyl group, a halogen, a substituted or unsubstituted aryl group. H and i are integers of 0 to 2 (but they are not 0 at the same time).

  The charge transport material having a vinyl group represented by the general formula 1 includes, for example, an aldehyde introduced into an amine compound by a Vilsmeier reaction or a reduction reaction as shown in the following synthesis routes 1 and 2, and then a phosphonium salt. Can be produced by introducing (synthesizing) vinyl groups.

  In addition, by using the following compound (Compound 1 or Compound 2) instead of (II) or together with (II), 2 or 4 substituents at the m or p position (h and / or in the above general formula 1) Or 2 to 4 substituents having a vinyl group in which i is 1 to 2).

In the general formula 1, more specifically, examples of the aryl group include a non-fused carbocyclic group, a condensed polycyclic hydrocarbon group, and a heterocyclic group.
Non-condensed carbocyclic groups include monovalent hydrocarbon compounds such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether and diphenyl sulfone, or biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne, and triphenyl. Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as methane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane, and polyphenylalkene, or ring-assembled hydrocarbons such as 9,9-diphenylfluorene The monovalent group of a compound is mentioned.
The condensed polycyclic hydrocarbon group is preferably a group having 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group, s-indacenyl group, fluorenyl group, acenaphthylenyl group, pleyadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group, Examples include a chrycenyl group and a naphthacenyl group.
Specific examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

In the general formula 1, when the aryl group represented by Ar ¹ has a substituent, examples of the substituent include the following.
(1) Halogen atom, cyano group, nitro group.
(2) An alkyl group, preferably a linear or branched alkyl group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. These alkyl groups further include a fluorine atom, a hydroxyl group, a cyano group, A phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, a phenyl group or a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms may be contained. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, allyl group, 2-hydroxyethyl group, 2 -Ethoxyethyl group, 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group and the like can be mentioned.
(3) an alkoxy group ^(-OR 10): wherein ^{R 10} represents an alkyl group as defined above (2). Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group And a trifluoromethoxy group.
(4) Aryloxy group: The aryl group of the aryloxy group includes a phenyl group and a naphthyl group. This aryl group may contain an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a halogen atom as a substituent. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.
(5) Alkyl mercapto group or aryl mercapto group: Specific examples include a methylthio group, an ethylthio group, a phenylthio group, and a p-methylphenylthio group.
(6) Group represented by the following chemical formula:

In the formula, each of R ¹⁵ and R ¹⁶ independently represents a hydrogen atom, an alkyl group defined in the above (2), or an aryl group. Examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group. These groups (excluding a hydrogen atom) may contain an alkoxy group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or a halogen atom as a substituent. R ¹⁵ and R ¹⁶ may jointly form a ring.
Specifically, amino group, diethylamino group, N-methyl-N-phenylamino group, N, N-diphenylamino group, N, N-di (tolyl) amino group, dibenzylamino group, piperidino group, morpholino group And pyrrolidino group.
(7) An alkylenedioxy group or an alkylenedithio group such as a methylenedioxy group or a methylenedithio group.
(8) Substituted or unsubstituted styryl group, substituted and unsubstituted β-phenylstyryl group, diphenylaminophenyl group, ditolylaminophenyl group and the like.
Specific examples of the charge transport material represented by the general formula 1 are given below.

[Polyester having a cyclohexyl group bonded to the main chain represented by Formula 2]
The polyester having a cyclohexyl group bonded to the main chain of the present invention has the following general formula 2
It is a compound shown by these.

In the general formula 2, R ¹ and R ² each independently represents a branched or straight chain alkyl group, an allyl group, a halogen atom, a substituted or unsubstituted aryl group, and m and l are integers of 0 to 2. , N is represented by 15 to 1000.
Examples of the alkyl group, allyl group, halogen atom, and substituted or unsubstituted aryl group are the same as those described in the general formula 1. The molecular weight is a measurement using GPC (polystyrene equivalent molecular weight), and the range thereof is 3,000 to 500,000, desirably 5,000 to 300,000. The interfacial polymerization method is generally used for the polymerization. A polyester represented by the general formula 2 is obtained by polymerization using bisphenol having a cyclohexyl ring, terephthalic acid chloride and isophthalic acid chloride. In this case, the ratio of terephthalic acid to isophthalic acid is stoichiometrically, and the reaction is preferably performed at a ratio of 1: 1, but the film properties and solubility are good, but it is not limited thereto.
Specifically, the following can be mentioned.

Such a polyester is synthesized by the following scheme. However, the specific materials used in the following schemes are for explaining the substantial contents of the schemes and are merely examples.
Dissolve bisphenol Z monomer in aqueous sodium hydroxide solution, dissolve terephthalic acid chloride and isophthalic acid chloride in 1/2 mole of dichlorophenol to 1 mole of bisphenol Z monomer, add under strong stirring, 30 minutes The reaction is followed by emulsification with triethylamine, reaction at 27 ° C. for 2 hours, and dichloroethane is added to terminate the reaction. The organic layer is separated, washed with dilute hydrochloric acid aqueous solution, washed with ion exchange water several times, and poured into methanol for crystallization.

[Charge transport material having a vinyl group represented by general formula 3]
The charge transport material having a vinyl group of the present invention is a compound represented by the following general formula 3.

In the above formula, Ar ² and Ar ³ represent a substituted or unsubstituted aryl group, and X represents a single bond, —O—, —CO—, or any one of the following general formula 4 (general formula 4 R ³ represents hydrogen, an alkyl group having 1 to 5 carbon atoms, or a substituted or unsubstituted aryl group). a is an integer of 1-2. The aryl group and alkyl group are the same as described above.

  These charge transport materials having a vinyl group represented by the general formula 3 are synthesized according to the following scheme. However, the specific materials used in the following schemes are for explaining the substantial contents of the schemes and are merely examples.

Specific examples of the charge transport material having a vinyl group represented by the general formula 3 include the following.

[Charge transport material having a vinyl group represented by general formula 5]
The charge transport material having a vinyl group of the present invention is a compound represented by the following general formula 5.

In the charge transport material having a vinyl group represented by the general formula 5, Ar ⁴ represents a substituted or unsubstituted aryl group, and b and c represent integers of 1 to 2. Y and Z each independently represent a single bond, —O—, —CO—, or one represented by the aforementioned general formula 4. The alkyl group and aryl group are the same as described above.

  A method for synthesizing a charge transport material having a vinyl group represented by the general formula 5 is shown in the following scheme. However, the specific materials used in the following schemes are for explaining the substantial contents of the schemes and are merely examples.

  Here, vinylbenzylphosphonium chloride was derived from chloromethylstyrene mixed with m and p positions and triphenylphosphine.

  Further, in the general formula 5, the following synthesis scheme can be exemplified when the linking groups Y and Z are —O—.

  Specific examples of the charge transport material having a vinyl group represented by the general formula 5 include the following.

[Charge transport material having a vinyl group represented by general formula 6]
The charge transport material having a vinyl group of the present invention is a compound represented by the following general formula 6.

In the above general formula 6, Ar ⁵ and Ar ⁶ represent a substituted or unsubstituted aryl group, and d and e represent integers of 0 to 2 (provided that d and e are not 0 simultaneously). The aryl group is the same as described above.

  Specific examples of the charge transport material having a vinyl group represented by the general formula 6 include the following.

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor formed by curing using a charge transport material having a vinyl group and a polyester having a cyclohexyl group bonded to the main chain.
The ratio of the charge transport material having a vinyl group and the polyester having a cyclohexyl group bonded to the main chain is 7 to 15 parts by weight of the polyester having a cyclohexyl group bonded to the main chain with respect to 10 parts by weight of the charge transport material having a vinyl group. To form the charge transport layer.

In the present invention, the following thermal polymerization initiators can be used in combination for the purpose of improving the reaction rate.
Methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, acetyl acetone peroxide, methyl cyclohexanone peroxide, cyclohexanone peroxide, isobutyryl peroxide, 2,4-dichlorobenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide Oxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5- (t-butyloxy) -hexane, 1,3-bis (t-butylperoxide Oxy-isopropyl) benzene, t-butylcumyl peroxide, di-tbutyl peroxide, 2,5-dimethyl-2,5- (di-t-butylperoxy) hexane-3, tris- ( -Butylperoxy) triazine, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, 2,2-di (t-butylperoxy) ) Butane, 4,4-di-t-butylperoxyvaleric acid n-butyl ester, 2,2-bis (4,4-t-butylperoxycyclohexyl) propane, t-butylperoxyisobutyrate , Peroxides such as di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-3,5,5-trimethylhexaate, t-butylperoxybenzoate, di-t-butylperoxytrimethyladipate, or azo Such as bisisobutyronitrile, azobisdimethylvaleronitrile, azobiscyclohexylnitrile Azo is used for.
When an initiator is used in combination, these initiators are added in an amount of 0.5 to 10% based on the total weight of the charge transport material having a vinyl group and the polyester having a cyclohexyl group bonded to the main chain.

The electrophotographic photosensitive member of the present invention can be produced by coating and drying on a conductive support described later using a coating solution.
The coating solution used when producing the electrophotographic photosensitive member of the present invention is optionally made of various plasticizers (for the purpose of stress relaxation and adhesion improvement), leveling agents, and low molecular charges having no radical reactivity. Additives such as transport materials can be included.
As these additives, known ones can be used, and as plasticizers, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used, and the amount used is the total solids of the coating liquid. It can be used in an amount of 20% by weight or less, preferably 10% or less based on the minute. As leveling agents, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount used is based on the total solid content of the coating liquid. 3% by weight or less is appropriate.

Examples of the solvent used for preparing the coating liquid include ethers such as tetrahydrofuran and dioxane, halogens such as dichloromethane, dichloroethane, trichloroethane, and chlorobenzene, and aromatics such as benzene, toluene, and xylene. These solvents may be used alone or in combination of two or more.
The dilution ratio of the coating solution with the solvent varies depending on the solubility of the composition, the coating method, and the target film thickness, and can be arbitrarily set. The coating can be performed using a dip coating method, spray coating, bead coating, ring coating method or the like.

  In the present invention, one of the coating liquids contains a charge transport material having a vinyl group and a polyester having a cyclohexyl group bonded to the main chain. As a formation method in the case of forming a cross-linked surface layer by applying this coating liquid after application, a gas such as air, nitrogen, vapor, or various heat media, infrared rays, electromagnetic waves, the coating surface side or It is performed by heating from the support side. The heating temperature is preferably 80 ° C. or higher and 170 ° C. or lower. If it is less than 80 degreeC, reaction rate is slow and reaction does not complete | finish completely. Further, at a temperature higher than 170 ° C., the reaction proceeds non-uniformly and a large strain is generated in the crosslinked surface layer. In order to advance the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 50 ° C. and then heating to 100 ° C. or more.

  Hereinafter, the electrophotographic photosensitive member of the present invention will be described according to its layer structure.

<Layer structure of electrophotographic photoreceptor>
The electrophotographic photoreceptor of the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view showing an example of the electrophotographic photosensitive member of the present invention.
FIG. 1 is a cross-sectional view showing a layer structure of a single-layer type photoreceptor in which a photosensitive layer 33 having a charge generation function and a charge transport function at the same time is provided on a conductive support 31. FIG. 1A shows the case where the crosslinked surface layer is the entire photosensitive layer, and FIG. 1B shows the case where the crosslinked surface layer is the surface portion of the photosensitive layer.
FIG. 2 is a cross-sectional view showing an example of a photoreceptor having a laminated structure in which a charge generation layer 35 having a charge generation function and a charge transport layer 37 having a charge transport material function are laminated on a conductive support 31. It is. FIG. 2A shows the case where the cross-linked surface layer is the entire charge transport layer, and FIG. 2B shows the case where the cross-linked surface layer is the surface portion of the charge transport layer.

<Conductive support>
As shown in FIGS. 1 and 2, the following can be used as the conductive support 31. Evaporation or sputtering of a metal having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, or platinum, or a metal oxide such as tin oxide or indium oxide , Film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc., and extruding them into a tube by a method such as drawing, cutting, superfinishing, polishing, etc. A tube subjected to the above surface treatment can be used as the conductive support. Further, an endless nickel belt and an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can be used as the conductive support (31).

In addition, the conductive support dispersed in a suitable binder resin and coated on the support can also be used as the conductive support (31) of the present invention.
Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, silver, or conductive tin oxide, ITO (Indium-Tin-Oxide), etc. Metal oxide powder etc. are mentioned. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.
Further, the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, fluororesin (for example, Teflon (registered trademark)) on a suitable cylindrical substrate. What provided the electroconductive layer with the heat-shrinkable tube can also be used suitably as the electroconductive support body 31 of this invention.

<Photosensitive layer>
Next, the photosensitive layer will be described. The photosensitive layer may have a laminated structure or a single layer structure. Note that the laminated structure and the single layer structure here do not define the number of layers, and the laminated structure means that the photosensitive layer has a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. The single layer structure means that the photosensitive layer has a charge generation function and a charge transport function at the same time.
Hereinafter, each of the photosensitive layer having a laminated structure and the photosensitive layer having a single layer structure will be described.

<Photosensitive layer comprising a charge generation layer and a charge transport layer (photosensitive layer having a laminated structure)>
(Charge generation layer)
As shown in FIG. 2, the charge generation layer 35 is a layer mainly composed of a charge generation material having a charge generation function, and a binder resin can be used in combination as necessary. As the charge generation material, inorganic materials and organic materials can be used.
Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. In amorphous silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms, phosphorus atoms, or the like are preferably used.
On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having carbazole skeleton, azo pigments having triphenylamine skeleton, azo pigments having diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

  The binder resin used as necessary for the charge generation layer (35) is polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-. Examples thereof include vinyl carbazole and polyacrylamide. These binder resins can be used alone or as a mixture of two or more. In addition to the binder resin described above as a binder resin for the charge generation layer, a polymer charge transport material having a charge transport function, such as an arylamine skeleton, benzidine skeleton, hydrazone skeleton, carbazole skeleton, stilbene skeleton, pyrazoline skeleton, etc. Polymer materials such as polycarbonate, polyester, polyurethane, polyether, polysiloxane, and acrylic resin, polymer materials having a polysilane skeleton, and the like can be used.

  Specific examples of the former (binder resin used in the charge generation layer) include JP-A-01-001728, JP-A-01-009964, JP-A-01-013061, and JP-A-01-019049. JP, 01-241559, JP, 04-011627, JP, 04-175337, JP, 04-183719, JP, 04-2225014, JP, 04-230767, Japanese Utility Model Laid-Open No. 04-320420, Japanese Patent Application Laid-Open No. 05-232727, Japanese Patent Application Laid-Open No. 05-310904, Japanese Patent Application Laid-Open No. 06-234836, Japanese Patent Application Laid-Open No. 06-234837, Japanese Patent Application Laid-Open No. 06-234838, Japanese Patent Application Laid-Open No. 06. -234839, JP-A-06-234840, JP-A-06-234841 JP-A 06-239049, JP-A 06-236050, JP-A 06-236051, JP-A 06-295077, JP-A 07-056374, JP 08-176293, JP 08-208820, JP 08-21640, JP 08-253568, JP 08-269183, JP 09-062019, JP 09-038883, JP JP-A 09-71642, JP-A 09-87376, JP 09-104746, JP 09-110974, JP 09-110976, JP 09-157378, JP 09-09. No. 221544, JP 09-227669 A, JP 09-23536 A JP-A 09-241369, JP-A 09-268226, JP-A 09-272735, JP-A 09-302084, JP-A 09-302085, JP-A 09-328539. And the like.

  Specific examples of the latter (polymer charge transport material) include, for example, JP-A 63-285552, JP-A 05-19497, JP-A 05-70595, and JP-A 10-73944. The polysilylene polymer described in 1) is exemplified.

The charge generation layer (35) may contain a low molecular charge transport material.
Low molecular charge transport materials that can be used in combination with the charge generation layer (35) include hole transport materials and electron transport materials.

  Examples of the electron transporting material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more.

  Examples of the hole transporting material include the electron donating materials shown below and are used favorably. As hole transport materials, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triaryls Other known materials such as methane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and the like can be given. These hole transport materials can be used alone or as a mixture of two or more.

Methods for forming the charge generation layer (35) include a vacuum thin film preparation method and a casting method from a solution dispersion system.
As the former method, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and the above-described inorganic materials and organic materials can be satisfactorily formed.
In addition, in order to provide a charge generation layer by the casting method described later, if necessary, the inorganic or organic charge generation material together with a binder resin, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclohexane. Can be formed by dispersing with a ball mill, attritor, sand mill, bead mill, etc. using a solvent such as pentanone, anisole, xylene, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, etc. . Moreover, leveling agents, such as a dimethyl silicone oil and a methylphenyl silicone oil, can be added as needed. The coating can be performed using a dip coating method, spray coating, bead coating, ring coating method or the like.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

(Charge transport layer)
When the charge transport layer (37) is a layer having a charge transport function, the cross-linked surface layer of the charge transport material having a vinyl group of the present invention and a polyester having a cyclohexyl group linked to the main chain is the entire charge transport layer 37. (Example of FIG. 2 (A)), coating solution (crosslinking surface layer coating solution) is applied on the charge generation layer 35 as described in the method for preparing a crosslinked surface layer, and a curing reaction is started by external energy. To form a crosslinked surface layer. At this time, the film thickness of the crosslinked surface layer is 10 to 30 μm, preferably 10 to 25 μm. If it is thinner than 10 μm, a sufficient charging potential cannot be maintained, and if it is thicker than 30 μm, peeling from the lower layer tends to occur due to volume shrinkage during curing.

  When the cross-linked surface layer is formed on the surface portion of the charge transport layer 37 and the charge transport layer 37 has a laminated structure (example in FIG. 2B), the lower layer portion of the charge transport layer has a charge transport function. A transport material and a binder resin are dissolved or dispersed in a suitable solvent, and formed by coating and drying on the charge generation layer 35. The charge transport material having the above vinyl group and cyclohexyl in the main chain are formed thereon. A coating solution (coating solution for a crosslinked surface layer) with a polyester having a group connected thereto is applied and crosslinked and cured by external energy.

  As the charge transport material, the electron transport material, hole transport material, and polymer charge transport material described in the charge generation layer 35 can be used. As described above, the use of the polymer charge transport material can reduce the solubility of the lower layer when the surface layer is applied, and is particularly useful.

As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin And thermoplastic or thermosetting resins such as phenol resins and alkyd resins.
The amount of the charge transporting material is 20 to 300 parts by weight, preferably 40 to 150 parts by weight with respect to 100 parts by weight of the binder resin. However, when a polymer charge transport material is used, it can be used alone or in combination with a binder resin.

As the solvent used for coating the lower layer portion of the charge transport layer, the same solvent as that for the charge generation layer can be used, but a solvent that dissolves or disperses the charge transport material and the binder resin well is suitable. These solvents may be used alone or in combination of two or more. The lower layer portion of the charge transport layer can be formed by the same coating method as that for the charge generation layer 35.
If necessary, a plasticizer and a leveling agent can be added.
As a plasticizer that can be used in combination with the lower layer portion of the charge transport layer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 100 parts by weight of the binder resin. On the other hand, about 0 to 30 parts by weight is appropriate.
As a leveling agent that can be used in combination with the lower layer portion of the charge transport layer, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain are used. A value of about 0 (preferably greater than 0) to about 1 part by weight per 100 parts by weight of the binder resin is appropriate.

The thickness of the lower layer portion of the charge transport layer is appropriately about 5 to 40 μm, preferably about 10 to 30 μm.
When the cross-linked surface layer is the surface portion of the charge transport layer 37, as described in the above cross-linked surface layer preparation method, the charge transport material having a vinyl group and cyclohexyl in the main chain on the lower layer portion of the charge transport layer. A coating liquid (coating liquid for forming a crosslinked surface layer) containing a polyester having a group linked thereto is applied to form a crosslinked surface layer. At this time, the film thickness of the crosslinked surface layer may be thinner than in the case of the laminated structure in FIG. 2A, and is 1 to 20 μm, preferably 2 to 10 μm. If the thickness is less than 1 μm, the durability varies due to uneven film thickness. If the thickness is more than 20 μm, the entire thickness of the charge transport layer is increased, and the reproducibility of the image is reduced due to the diffusion of charges.

<Single layer photosensitive layer>
The photosensitive layer having a single layer structure is a layer having a charge generation function and a charge transport function at the same time. In the present invention, the cross-linked surface layer having a charge transport structure has a single layer structure by containing a charge generation material having a charge generation function. It is useful as a photosensitive layer. As described in the method for forming a charge generation layer described above, in the present invention, the charge generation material is a coating liquid (crosslinked surface) containing a charge transport material having a vinyl group and a polyester having a cyclohexyl group linked to the main chain. A cross-linked surface layer is formed by dispersing together with the coating liquid for layer), applying it onto the conductive support 31, and drying and curing reaction as necessary. In addition, you may add the charge generation substance to the above-mentioned coating liquid for bridge | crosslinking surface layers in the liquid disperse | distributed with the solvent previously. At this time, when the crosslinked surface layer is the entire photosensitive layer (example in FIG. 1A), the film thickness is 10 to 30 μm, preferably 10 to 25 μm. If the thickness is less than 10 μm, a sufficient charging potential cannot be maintained. If the thickness is more than 30 μm, peeling from the conductive substrate or the undercoat layer tends to occur due to volume shrinkage during curing.

  When the cross-linked surface layer is a surface portion of a photosensitive layer having a single layer structure (example in FIG. 1B), the lower layer portion of the photosensitive layer is a charge generating material having a charge generating function and a charge transporting function having a charge transport function. It can be formed by dissolving or dispersing the substance and the binder resin in an appropriate solvent, and applying and drying it. Moreover, a plasticizer, a leveling agent, etc. can also be added as needed. As the charge generation material dispersion method, the charge generation material, the charge transport material, the plasticizer, and the leveling agent may be the same as those already described in the charge generation layer 35 and the charge transport layer 37, respectively. As the binder resin, in addition to the binder resin previously mentioned in the section of the charge transport layer 37, the binder resin mentioned in the charge generation layer 35 may be mixed and used. In addition, the above-described polymer charge transport materials can also be used, which is useful in that contamination of the lower photosensitive layer composition into the crosslinked surface layer can be reduced. The film thickness of the lower layer portion of the photosensitive layer is suitably about 5 to 30 μm, preferably about 10 to 25 μm.

When the cross-linked surface layer is a surface portion of a photosensitive layer having a single layer structure, as described above, a polyester having a vinyl group-substituted charge transport material and a cyclohexyl group linked to the lower layer portion of the photosensitive layer and a charge generating material A coating solution containing is applied, and if necessary, dried and cured to form a crosslinked surface layer. At this time, the film thickness of the cross-linked surface layer may be thinner than in the case of the laminated structure in FIG. 1A, and is 1 to 20 μm, preferably 2 to 10 μm. When the thickness is less than 1 μm, the durability varies due to the film thickness unevenness. On the other hand, if the thickness exceeds 20 μm, the potential of the exposed area tends to increase, and the density of the image area tends to decrease. Further, differences in curability are likely to occur on the surface, inside, and substrate side, resulting in increased surface irregularities and wrinkles.
The charge generation material contained in the photosensitive layer having a single layer structure is preferably 1 to 30% by weight based on the total amount of the photosensitive layer, and the binder resin contained in the lower layer portion of the photosensitive layer is 20 to 80% by weight of the total amount. The transport material is preferably used in an amount of 10 to 70 parts by weight.

<Intermediate layer>
In the electrophotographic photoreceptor of the present invention, when the crosslinked surface layer becomes the surface portion of the photosensitive layer (example in FIG. 1B, example in FIG. 2B), between the crosslinked surface layer and the lower photosensitive layer. An intermediate layer can be provided. This intermediate layer can prevent inhibition of the curing reaction and unevenness of the crosslinked surface layer caused by mixing of the lower photosensitive layer composition in the crosslinked surface layer containing the radical polymerizable composition. It is also possible to improve the adhesion between the lower photosensitive layer and the surface cross-linked layer.
In the intermediate layer, a binder resin is generally used as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a generally used coating method is employed as described above. In addition, about 0.05-2 micrometers is suitable for the thickness of an intermediate | middle layer.

<Underlayer>
In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support 31 and the photosensitive layer. The undercoat layer generally contains a resin as a main component. As these resins, it is desirable to use a resin having high solvent resistance with respect to a general organic solvent, considering that a coating solution for a photosensitive layer to which a solvent is added is applied. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a metal oxide fine powder pigment exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moire and reduce residual potential.

These undercoat layers can be formed using an appropriate solvent and a coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, in the undercoat layer of the present invention, Al ₂ O ₃ is provided by anodization, organic substances such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ A material provided with an inorganic material such as a vacuum thin film can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

<Addition of antioxidant to each layer>
In the present invention, for the purpose of improving environmental resistance, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, a surface cross-linked layer, a photosensitive layer, a charge generation layer, a charge transport layer, an undercoat layer, an intermediate layer, etc. An antioxidant can be added to each layer.
The following are mentioned as antioxidant which can be used for this invention.

(Phenolic compounds)
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4, 4'-thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4 -Hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene- -(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butyric acid ] Cryol ester, tocopherols and the like.

(Paraphenylenediamines)
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.

(Hydroquinones)
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone and the like.

(Organic sulfur compounds)
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.

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

These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained.
The addition amount of the antioxidant in the present invention is 0.01 to 10% by weight based on the total weight of the layer to be added.

<Image Forming Method and Image Forming Apparatus>
Next, an image forming method and an image forming apparatus will be described in detail with reference to the drawings.
As an image forming method using the electrophotographic photosensitive member of the present invention, for example, at least after the photosensitive member is charged, exposed to an image, and developed, a toner image is transferred onto an image carrier (transfer paper), fixed, and fixed. It consists of cleaning the surface of the photoreceptor.
In some cases, an image forming method or the like in which an electrostatic latent image is directly transferred to a transfer member and developed does not necessarily include all the processes arranged on the photosensitive member.

  FIG. 3 is a schematic view showing an example of an image forming apparatus having the electrophotographic photosensitive member of the present invention. In the image forming apparatus of this example, a charging charger 3 as an example of a charging unit, an eraser 4, an image exposure unit 5, a developing unit 6, and a pre-transfer charger 7 are disposed around the photosensitive member 1. Separation charger 11, separation claw 12, pre-cleaning charger 13, and cleaning fur brush formed integrally with a transfer charger 10 for transferring a toner image onto a transfer paper 9 conveyed by a registration roller 8 from a transfer paper tray not shown. 14, a cleaning blade 15 and a charge removal lamp 2 are arranged. A charging charger 3 is used as a means for charging the photoreceptor 1 on average. As the charging means, a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or the like is used, and a known method can be used.

  The electrophotographic photosensitive member of the present invention is particularly effective when a charging unit such as a contact charging method or a non-contact proximity arrangement charging method in which a photosensitive member composition is decomposed by a proximity discharge from the charging unit is used. . The contact charging method referred to here is a charging method in which a charging roller, a charging brush, a charging blade, or the like is in direct contact with the photosensitive member. On the other hand, the proximity charging method is, for example, a type in which the charging roller is arranged in a non-contact state so as to have a gap of 200 μm or less between the surface of the photoreceptor and the charging means. If this gap is too large, the charging tends to become unstable, and if it is too small, the surface of the charging member may be contaminated when toner remaining on the photoreceptor exists. is there. Accordingly, the gap is suitably 10 to 200 μm, preferably 10 to 100 μm.

  Next, the image exposure unit 5 is used to form an electrostatic latent image on the uniformly charged photoreceptor 1. The light source includes at least one selected from fluorescent materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL). Can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

  Next, the developing unit 6 is used to visualize the electrostatic latent image formed on the photoreceptor 1. Development methods include a one-component development method using a dry toner, a two-component development method, and a wet development method using a wet toner. When the photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.

  Next, a transfer charger 10 is used to transfer the toner image visualized on the photosensitive member onto the transfer member 9. In addition, a pre-transfer charger 7 may be used for better transfer. As these transfer means, a transfer charger, an electrostatic transfer method using a bias roller, a mechanical transfer method such as an adhesive transfer method and a pressure transfer method, and a magnetic transfer method can be used. As the electrostatic transfer method, the charging means can be used.

  Next, as a means for separating the transfer body 9 from the photoreceptor 1, a separation charger 11 and a separation claw 12 are used. As other separation means, electrostatic adsorption induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like are used. As the separation charger 11, the charging means can be used.

  Next, a fur brush 14 and a cleaning blade 15 are used to clean the toner remaining on the photoconductor after transfer. Further, a pre-cleaning charger 13 may be used in order to perform cleaning more efficiently. Other cleaning means include a web method and a magnet brush method, but each may be used alone or a plurality of methods may be used together.

  Next, a neutralizing unit is used for the purpose of removing the latent image on the photoreceptor as required. As the charge removal means, the charge removal lamp 2 and the charge removal charger are used, and the exposure light source and the charging means can be used respectively.

  In addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.

The present invention has the electrophotographic photosensitive member according to the present invention as such an image forming means.
This image forming means may be fixedly incorporated in a copying apparatus, facsimile, or printer, and may be incorporated in these apparatuses, preferably in the form of a process cartridge, and detachable. An example of such a process cartridge is shown in FIG.

  The process cartridge for an image forming apparatus according to the present invention includes a photosensitive member 101, and at least one of a charging unit 102, a developing unit 104, a transfer unit 106, a cleaning unit 107, and a charge eliminating unit (not shown). Is a device (part) that can be attached to and detached from the main body of the image forming apparatus, and at least one of charging, developing, transferring, cleaning, and discharging means is integrated with a photoreceptor having a smooth charge transporting surface cross-linked layer. It has been made.

  The image forming process by the apparatus illustrated in FIG. 4 will be described. The photosensitive member 101 is charged in the direction of the arrow while being charged by the charging unit 102 and exposed by the exposure unit 103. A latent image is formed, and the electrostatic latent image is developed with toner by the developing unit 104. The toner image is transferred to the transfer member 105 by the transfer unit 106 and printed out. Next, the surface of the photoreceptor after the transfer of the toner image is cleaned by the cleaning unit 107, and is further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

  As is apparent from the above description, the electrophotographic photosensitive member of the present invention is not only used in electrophotographic copying machines, but also in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making. Can also be used widely.

Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not construed to be limited to the examples described below, and the present invention is construed within the scope described in the specification and the drawings. Here, the part is based on weight.
The polyesters used in the following examples were synthesized under the conditions described above by reacting a bisphenol compound having a structure corresponding to an acid chloride containing terephthalic acid chloride and isophthalic acid chloride in a ratio of 1: 1. Table 1 below shows the weight average molecular weight (Mw) in terms of polystyrene of the synthesized polyester.

<Example 1>
By coating and drying an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution in the following order on a φ30 mm aluminum cylinder in sequence, an undercoat layer of 3.5 μm Then, a 0.2 μm charge generation layer and a 22 μm charge transport layer were formed. Thereafter, it was dried at 150 ° C. for 30 minutes to obtain the electrophotographic photosensitive member of the present invention.

[Coating liquid for undercoat layer]
Alkyd resin 6 parts (Beckosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
Titanium oxide 40 parts Methyl ethyl ketone 50 parts

[Coating liquid for charge generation layer]
Bisazo pigment of the following structural formula (I) 2.5 parts Polyvinyl butyral (XYHL, manufactured by UCC) 0.5 part Cyclohexanone 200 parts Methyl ethyl ketone 80 parts

[Coating liquid for charge transport layer]

No. Compound shown in 19 10 parts THF 90 parts Silicone oil (KF50, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.02 parts

<Examples 2 to 10>
In the same manner as in Example 1, an undercoat layer and a charge generation layer were provided, and a 22 μm charge transport layer was formed using the charge transport layer coating liquid shown in Table 2 below. The electrophotographic photosensitive member of the present invention was obtained by drying at 150 ° C. for 30 minutes.

<Comparative Example 1>
In the same manner as in Example 1, an undercoat layer and a charge generation layer were provided, and the following charge transport layer (22 μm) having a thickness of 22 μm was provided.
[Coating liquid for charge transport layer]
Polyarylate (U polymer, trade name U-100, manufactured by Unitika) 10 parts Low molecular charge transport material (D-1) of the following structural formula (II) 10 parts Tetrahydrofuran 90 parts Silicone oil (KF50-100CS, Shin-Etsu Chemical Co., Ltd.) 0.02 parts)

<Comparative Examples 2-8>
In Comparative Examples 2 to 3, the charge transporting material is changed to D-1 which is the same as that of Comparative Example 1 in the arylamine (having no vinyl group) of the above structural formula (II), and Comparative Examples 4 to 5 are the following ( In place of D-2 of arylamine structural formula (III) having no vinyl group, and Comparative Examples 6 to 8 were changed to D-3 of arylamine structural formula (IV) (having no vinyl group) as a charge transport material. In the same manner as in Comparative Example 1 except that the polyesters of Comparative Examples 2 to 8 were replaced with those shown in Table 3, respectively, to obtain photoreceptors.

  Using the electrophotographic photosensitive members shown in Examples 1 to 10 and Comparative Examples 1 to 8, a paper passing test of 20,000 sheets in A4 size was performed. First, each photosensitive member of the examples and comparative examples was mounted on a process cartridge for an electrophotographic apparatus, and an initial dark portion potential was set to -700 V in a remodeled imagio Neo 270 manufactured by Ricoh using a 655 nm semiconductor laser as an image exposure light source. Set. Thereafter, a paper passing test was started, and the reduction in film thickness of each photoconductor after copying 20,000 sheets was measured. The film thickness of the photoconductor was measured with an eddy current film thickness meter Fischerscope MMS manufactured by Fischer Instruments. The results are shown in Tables 4-5. A photoconductor using a charge transport material having a vinyl group, although worn, is about half of the conventional photoconductor using a charge transport material having no vinyl group, and its durability is doubled. I can say that.

<Example 11>
By coating and drying an intermediate layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution of the following composition in sequence on a φ100 mm aluminum cylinder, a 3.5 μm intermediate layer, 0.2 μm And a charge transport layer of 20 μm were formed. Further, a crosslinked surface layer coating solution was applied thereon by a spray method, and then dried at 150 ° C. for 30 minutes to provide a cured charge transport layer having a thickness of 7 μm.

[Coating liquid for intermediate layer]
The following composition was dispersed and adjusted with a ball mill for 24 hours.
Alkyd resin (Beckosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals) 6 parts Melamine resin (Super Becamine G-821-60, manufactured by Dainippon Ink and Chemicals) 4 parts Titanium oxide (CREL, Ishihara Sangyo) 40 parts Methyl ethyl ketone 200 parts

[Coating liquid for charge generation layer]
The following composition was dispersed and adjusted with a ball mill for 24 hours.
Oxotinium phthalocyanine pigment 2 parts Polyvinyl butyral (UCC: XYHL) 0.2 part Tetrahydrofuran 50 parts

[Coating liquid for charge transport layer]
The following composition was dissolved and prepared.
Polystyrene (MW1C, manufactured by Toyo Styrene Co., Ltd.) 12 parts Low molecular charge transport material of the following structural formula (V) 12 parts THF 90 parts Silicone oil (KF50 Shin-Etsu Silicone Co., Ltd.) 0.02 parts

[Coating liquid for cross-linked surface layer]
The following composition was prepared by dissolving or dispersing.
No. 2 vinyl arylamines 1 part PE1 polyester 1 part Azobisisobutyronitrile (polymerization initiator) 0.05 parts tetrahydrofuran 30 parts

<Example 12>
In the same manner as in Example 11, an undercoat layer, a charge generation layer, and a charge transport layer were provided, and the following crosslinked surface layer was provided in the same manner as in Example 11.
[Coating liquid for cross-linked surface layer]
No. 7 vinylarylamine 1 part PE2 polycarbonate 1 part Azobisdimethylvaleronitrile (photopolymerization initiator) 0.05 part Tetrahydrofuran 30 parts

<Comparative Example 9>
Implemented except that unitary polyacrylate (U polymer trade name U-100) was used instead of polystyrene for the charge transport layer, the charge transport layer thickness was changed to 27 μm, and no cross-linked surface layer was provided. A photoconductor was prepared in the same manner as in Example 11.

  The photoconductors of Examples 11 and 12 and Comparative Example 9 were mounted on the apparatus shown in FIG. 3 (Imagio Neo1050 Pro, manufactured by Ricoh Co., Ltd.), and 500,000 sheets were tested. The results are shown in Table 6.

Originally, the comparative example has no cross-linked surface layer, but when the charge transport layer binder resin used is a polystyrene surface layer, it has no mechanical strength and is not suitable for a durability test, so a tough polyarylate was used. .
As a result of performing an image output test of 500,000 sheets, both Examples 11 to 12 and Comparative Example 9 were clear images. However, when the amount of wear was measured, Examples 11 to 12 showed twice the wear resistance as compared with that of Comparative Example 9. That is, it can be said that the photoconductors of Examples 11 to 12 are twice as durable as those of Comparative Example 9 which is a conventional photoconductor.

<Example 13>
A 15 cmφ ball mill pot is charged with 22 parts of the following charge generating material and 400 parts of cyclohexanone as a solvent, and ball milled for 48 hours using 10 mmφ zirconia media. Thereafter, 500 parts of cyclohexanone is further added to adjust the mill base to prepare pigment dispersion 1. Obtained (pigment dispersion 1).

(Pigment dispersion 1)
400 parts of cyclohexanone

  12 parts of the pigment dispersion 1 and 20 parts of the resin liquid 1 having the following composition were mixed and stirred to prepare a single layer coating liquid 1.

(Resin liquid 1)
Tetrahydrofuran (THF) 66 parts PE3 polyester 4 parts 18 vinyl arylamine 4 parts Polyethylene glycol (Ionette MC1400, manufactured by Sanyo Chemical Co., Ltd.) 0.2 part Silicone oil (KF50, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.01 part

  It is dip coated in a solution of 10 parts of polyamide resin (CM8000, manufactured by Toray Industries, Inc.), 220 parts of methanol, and 100 parts of n-butanol on a φ30 mm aluminum cylinder, dried at 100 ° C. for 10 minutes, and subtracted 0.3 μm. A layer was provided. On top of this, the single layer coating solution 1 was dip coated to provide a 20 μm single layer photoreceptor. The electrophotographic photosensitive member of the present invention was obtained by drying at 150 ° C. for 30 minutes.

<Comparative Example 10>
In Example 13, after similarly providing an undercoat layer, the following single-layer coating solution 2 was applied to obtain an electrophotographic photoreceptor in the same manner as in Example 13. The single-layer coating solution 2 was prepared by mixing the pigment dispersion 1 used in Example 13 and the following resin solution 2 in the same amount in Example 13.
(Coating fluid 3)
Tetrahydrofuran (THF) 66 parts PE3 polyester 4 parts

4 parts of the above compound Polyethylene glycol (Ionette MC1400, manufactured by Sanyo Chemical Co., Ltd.) 0.2 part Silicone oil (KF50, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.01 part

The photoreceptors of Example 13 and Comparative Example 10 were mounted on a process cartridge for an electrophotographic apparatus, initially used with a remodeled imagio Neo 270 manufactured by Ricoh with a 655 nm semiconductor laser as an image exposure light source and a positive charge polarity. The dark part potential was set to 700V. Thereafter, a paper passing test was started and a 1000 sheet copying test was conducted.
The photoreceptor of Example 13 was a clear image, but the photoreceptor of Comparative Example 10 was confirmed to generate white lines and black lines. This is considered to be due to the difference in surface hardness, and it is considered that the photoconductors of the examples were cross-linked, so that the scratch resistance was improved as the hardness increased and a clear image was obtained.

1 is a cross-sectional view of an example of an electrophotographic photosensitive member of the present invention. It is sectional drawing of the other example of the electrophotographic photoreceptor of this invention. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. FIG. 2 is a schematic diagram illustrating an example of a process cartridge for an image forming apparatus according to the present invention. It is the data of IR absorption spectrum of polyester PE1 before curing. The horizontal axis represents the wave number (cm ⁻¹ ), and the vertical axis represents the transmittance (T%: Transmittance%). No. It is data of IR absorption spectroscopy of 16 vinyl group-containing arylamine compounds (monomers). The horizontal and vertical axes are the same as in FIG. Polyester PE1 (before curing) and allyl arylamine compound No. 16 is a data of IR absorption spectrum after curing No. 16. The horizontal and vertical axes are the same as in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charger 4 Eraser 5 Image exposure part 6 Developing unit 7 Pre-transfer charger 8 Registration roller 9 Transfer paper 10 Transfer charger 11 Separation charger 12 Separation claw 13 Pre-cleaning charger 14 Fur brush 15 Cleaning blade 31 Conductivity Support 33 Photosensitive layer 35 Charge generation layer 37 Charge transport layer 39 Protective layer 101 Photosensitive drum 102 Charging device 103 Exposure device 104 Development device 105 Transfer body 106 Transfer device 107 Cleaning blade

Claims (7)

1. An electrophotographic photoreceptor comprising a layer formed by a crosslinking reaction between a charge transport material having a vinyl group represented by the following general formula 1 and a polyester represented by the following general formula 2.

(In the above formula, Ar ¹ represents a substituted or unsubstituted aryl group, and R ¹ and R ² each independently represents a branched or straight chain alkyl group, an allyl group, a halogen, a substituted or unsubstituted aryl group. H and i are integers of 0 to 2 (but they are not simultaneously 0), m and l are integers of 0 to 2, and n is 15 to 1000. ) 1. An electrophotographic photoreceptor comprising a layer formed by a crosslinking reaction between a charge transport material having a vinyl group represented by the following general formula 3 and a polyester represented by the following general formula 2.

(In the above formula, Ar ² and Ar ³ represent a substituted or unsubstituted aryl group, and R ¹ and R ² are each independently a branched or straight chain alkyl group, an allyl group, a halogen atom, a substituted or unsubstituted group. X represents a single bond, —O—, —CO—, or any one of the following general formula 4 (in general formula 4, R ³ represents hydrogen, 5 represents an alkyl group of 5 or a substituted or unsubstituted aryl group), a is an integer of 1 to 2, m and l are integers of 0 to 2, and n is 15 to 1000.

1. An electrophotographic photoreceptor comprising a layer formed by a crosslinking reaction of a charge transport material having a vinyl group represented by the following general formula 5 and a polyester represented by the following general formula 2.

(In the above formula, Ar ⁴ represents a substituted or unsubstituted aryl group, and R ¹ and R ² each independently represents a branched or straight chain alkyl group, an allyl group, a halogen atom, a substituted or unsubstituted aryl group. And b and c are integers of 1 to 2, m and l are integers of 0 to 2, and n is an integer of 15 to 1000. Y and Z are each independently a single bond, —O. -, -CO-, or one represented by the following general formula 4 (in the general formula 4, R ³ represents either a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a substituted or unsubstituted aryl group. To express).)

An electrophotographic photosensitive member comprising a layer formed by a crosslinking reaction of a charge transport material having a vinyl group represented by the following general formula 6 and a polyester represented by the following general formula 2.

(In the above formula, Ar ⁵ and Ar ⁶ each independently represent a substituted or unsubstituted aryl group, and R ¹ and R ² each independently represent a branched or straight chain alkyl group, allyl group, halogen, It represents either a substituted or unsubstituted aryl group, d and e are integers of 1 to 2, m and l are integers of 0 to 2, and n is 15 to 1000.) The electrophotographic photosensitive member according to any one of claims 1 to 4, the layer formed by the crosslinking reaction, characterized in that the surface layer. At least, a charging means, image exposure means, a developing means, an image forming apparatus including a transfer means and an electrophotographic photosensitive member, the electrophotographic photosensitive member is an electrophotographic photosensitive member according to any one of claims 1 to 5 An image forming apparatus. An electrophotographic photosensitive member according to any one of claims 1 to 5 charging means, developing means, and the support and at least one means selected from the cleaning means integrally, that is detachable to the image forming apparatus main body A process cartridge for an image forming apparatus.

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