JP4229808B2 - Electrophotographic photosensitive member, process cartridge, electrophotographic apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photoreceptor, and more particularly, to an electrophotographic photoreceptor having a specific cross-linked charge transport layer that is charged by contact charging means. The present invention also relates to a process cartridge and an electrophotographic apparatus having the charging unit and the electrophotographic photosensitive member.

  When an image is obtained by performing basic processes such as charging, exposure, development, transfer, fixing, and cleaning on an electrophotographic photosensitive member, most charging processes conventionally apply a high voltage (5 to 8 kV DC) to a metal wire. This is a so-called corona charging method in which charging is performed by the generated corona. However, in this method, corona products such as ozone and NOx adhere to the surface of the photoreceptor, image flow and image blur due to alteration of the photosensitive layer itself, and image blank due to wire contamination. And black streaks may occur. In particular, a photoconductor in which the photosensitive layer contains an organic photoconductor is less chemically stable than other photoconductors using inorganic photoconductors such as selenium and amorphous silicon, and is chemically exposed when exposed to corona products. Reaction (mainly oxidation reaction) tends to occur and tends to deteriorate.

  In corona charging, only 5 to 30% of the current directed to the photoconductor is present, and most of the current flows to the shield plate, and the charging means is inefficient in terms of power.

  As a method for solving such a problem, in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, and the like, a charging that is brought into contact with the surface of the photoreceptor without using a corona discharger. A so-called contact charging method has been proposed in which a photoreceptor is charged by applying a voltage to a member. Specifically, a charging member such as a conductive elastic roller is brought into contact with the surface of the photosensitive member, and a DC voltage of about 1 to 2 kV is externally applied to the charging member to charge the surface of the photosensitive member to a predetermined potential. Is.

  However, the contact charging method has a problem that charging tends to be uneven. The non-uniformity of charging is a phenomenon in which each portion of the surface of the photoconductor is not uniformly charged, causing spot-like or streaky charging unevenness with a width of about 0.5 mm or less in the longitudinal direction of the photoconductor. White spots and streaks that occur in the development method (a phenomenon in which white spots and streaks appear in a solid black image), or black spots and black streaks that occur in the case of a reversal development method (a phenomenon in which black spots and streaks appear in a solid white image) ).

  Therefore, in order to improve the uniformity of charging, a method has been proposed in which a voltage obtained by superimposing an alternating voltage (AC) on a direct current voltage (DC) is applied to a charging member (cited document 6 or the like). In this case, in order to maintain the uniformity of charging and prevent image defects such as white spots, white stripes, black spots and black stripes, the superimposed AC voltage has a peak-to-peak potential difference (Vpp) that is at least twice the DC voltage. It is necessary to set it to an appropriate value as an AC frequency.

  On the other hand, with respect to organic photoreceptors, the diameter of photoreceptors has recently been reduced due to the miniaturization of image forming apparatuses, and high durability of photoreceptors has been eagerly desired due to the addition of machine speed and maintenance-free movement. It is coming. From this point of view, organophotoreceptors are generally soft because they are based on low molecular charge transport materials and inert polymers in addition to the chemical stability described above, and when used repeatedly in an electrophotographic process, There is a drawback that wear is likely to occur due to a mechanical load by the system or the cleaning system. In addition, due to the demand for higher image quality, the cleaning blade is required to increase its rubber hardness and contact pressure for the purpose of improving the cleaning property as the particle size of the toner particles is reduced. This also promotes wear of the photoreceptor. It is a factor. 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. Further, scratches where wear is locally generated 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 (1) using a curable binder in the crosslinkable charge transport layer (see, for example, Patent Document 7), and (2) using a polymer charge transport material. (For example, refer to Patent Document 8), and (3) a structure in which an inorganic filler is dispersed in a cross-linked charge transport layer (for example, refer to Patent Document 9). Among these techniques, those using the curable binder (1) have poor compatibility with the charge transport material, and the residual potential increases due to impurities such as polymerization initiators and unreacted residues, resulting in a decrease in image density. Tends to occur. In addition, although the polymer charge transport material (2) can improve the abrasion resistance to some extent, the durability required for the organic photoreceptor is not fully satisfied. Not reached. In addition, polymer charge transport materials are difficult to polymerize and purify, and it is difficult to obtain a high-purity material. 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 of the inorganic filler (3) exhibits higher abrasion resistance than a photoreceptor in which a normal low molecular charge transport material is dispersed in an inert polymer, but the charge present on the surface of the inorganic filler. The residual potential increases due to the trap, 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. These technologies (1), (2), and (3) are sufficient to satisfy the overall durability including the electrical durability and mechanical durability required for the organic photoreceptor. Has not reached.

Furthermore, a photoreceptor containing a polyfunctional acrylate monomer cured product in order to improve the abrasion resistance and scratch resistance of (1) is also known (see Patent Document 10). 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, the protective layer may contain a charge transport material. However, there is a problem of compatibility with the cured product when a cross-linked charge transport layer contains a low-molecular charge transport material. As a result, precipitation of a low-molecular charge transport material and white turbidity occur, and not only the image density is lowered but also the mechanical strength is lowered due to the increase of the exposed portion potential.
Furthermore, since this photoconductor specifically reacts with the monomer in a state containing a polymer binder, the three-dimensional network structure does not proceed sufficiently, and the crosslink density becomes dilute, resulting in a dramatic wear resistance. Has not yet been able to demonstrate.

  As a wear resistance technology for a photosensitive layer that replaces these, a charge transport layer formed by using a coating liquid comprising a monomer having a carbon-carbon double bond, a charge transport material having a carbon-carbon double bond, and a binder resin. It is known to provide (for example, refer to Patent Document 11). This binder resin is thought to play a role of improving the adhesion between the charge generation layer and the curable charge transport layer, and further mitigating the internal stress of the film during thick film curing, and has a carbon-carbon double bond. These are broadly classified into those having reactivity with the charge transfer agent and those having no reactivity with the double bond. This photoconductor is remarkably compatible with wear resistance and good electrical properties, but when a non-reactive binder resin is used, the binder resin, the monomer and the charge transport agent are used. The compatibility with the cured product produced by this reaction is poor, and layer separation occurs in the cross-linked charge transport layer, which may cause scratches and sticking of external additives and paper powder in the toner. In addition, as described above, the three-dimensional network structure does not proceed sufficiently, and the cross-linking density becomes dilute. In addition, what is specifically described as the monomer used in this photoreceptor is bifunctional, and in these respects, it has not yet been satisfactory in terms of wear resistance. Even when a reactive binder is used, the molecular weight of the cured product is increased, but the number of intermolecular crosslinks is small, and it is difficult to achieve a balance between the amount of the charge transporting substance and the crosslink density. Abrasion was 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 (for example, see Patent Document 12). This photosensitive layer has high hardness because the crosslink density can be increased, but since the bulky hole transporting compound has two or more chain polymerizable functional groups, distortion occurs in the cured product and internal stress increases. In some cases, the crosslinked surface layer is liable to crack or peel off when used for a long period of time.

  Even in the conventional photoconductors having a cross-linked photosensitive layer in which a charge transporting structure is chemically bonded, it cannot be said that the present invention has sufficient comprehensive characteristics.

JP-A-57-178267 JP-A-56-104351 JP 58-40566 A JP 58-139156 A JP 58-150975 A JP-A 63-149668 JP 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent No. 3262488 Japanese Patent No. 3194392 JP 2000-66425 A

  In order to improve the uniformity of charging and prevent image defects, it is effective to increase the superimposed AC voltage, but the maximum applied voltage also increases accordingly, so only a few defective parts inside the photoconductor However, discharge breakdown is more likely to occur. In particular, when the photoreceptor is a photoreceptor using an organic photoconductor having a low withstand voltage, dielectric breakdown is very likely to occur. In this case, in the normal development method, the image is blank over the longitudinal direction of the contact portion, and in the reverse development method, a black belt is generated.

  In addition, since superimposing the AC voltage means contacting a charging member subjected to high frequency to the electrophotographic photosensitive member, noise may be generated during charging. In addition, since an excessive amount of alternating current flows to the electrophotographic photosensitive member, electrical deterioration such as an increase in residual potential occurs, or the surface of the photosensitive member is partially damaged, and toner or the like adheres to the portion. So-called filming sometimes occurred. It has also been found that superimposing an alternating voltage increases the hazard to the electrophotographic photosensitive member, increases the wear rate, and greatly reduces the life of the electrophotographic photosensitive member.

For this reason, a method of applying only a DC voltage without superimposing an AC voltage has been reviewed, but the problem of non-uniform charging as described above still remains.
In addition, with the recent increase in image quality, there is a problem of so-called transfer memory in which the capacity inside the photoconductor changes due to transfer charging, and the sensitivity changes between where the transfer charge is received and where it is not.
Furthermore, with regard to durability and wear resistance, the conventional organic photoreceptors and photoreceptors having a protective layer are not sufficient to meet the recent demand for high durability, and electrostatic durability There is also a need for a photoreceptor with film properties.

An object of the present invention is to provide an electrophotographic photosensitive member that does not cause spotted or streaky charging unevenness even when a DC voltage is applied and has a small potential fluctuation.
Another object of the present invention is to provide an electrophotographic photoreceptor having a small transfer memory. That is, in reversal development, a positively charged transfer may be performed in order to transfer toner when the photosensitive member is negatively charged. At this time, the surface of the photoconductor may be positively charged. If this effect is large, a charging potential difference will occur between the untransferred part and the transferred part, even if negatively charged during charging. Thus, a difference in potential after exposure occurs even during exposure. Such a phenomenon is called transfer memory.
Furthermore, another object of the present invention is high wear resistance and scratch resistance, and good electrical characteristics. In particular, the photosensitive layer is not easily cracked or peeled off, and has high durability and high performance. Is to provide a body.
It is a further object of the present invention to provide a process cartridge and an electrophotographic apparatus having the above electrophotographic photosensitive member and charging means.

As a result of intensive studies on the above problems, the present inventors have found that this can be achieved by satisfying the following configuration, and have completed the present invention.
[1] In an electrophotographic photosensitive member in which at least a charge generation layer, a charge transport layer, and a crosslinkable charge transport layer are sequentially laminated on a conductive support, the crosslinkable charge transport layer has at least a functional group having no charge transport structure. The radical polymerizable monomer and a radical polymerizable compound having a monofunctional charge transport structure are cured, and the film thickness of the crosslinkable charge transport layer is 2 μm or more and 8 μm or less. An electrophotographic photosensitive member characterized by being charged by applying a direct current voltage to a charging member in contact with the surface of the photosensitive member.

[2] The radical polymerizable functional group of the radically polymerizable monomer having a trifunctional or higher functional group having no charge transporting structure and the monofunctional charge transporting structure having a charge transporting structure used in the crosslinkable charge transporting layer is acryloyloxy The electrophotographic photosensitive member according to [ 1], which is a group and / or a methacryloyloxy group.
[3] In an electrophotographic photosensitive member in which at least a charge generation layer, a charge transport layer, and a crosslinkable charge transport layer are sequentially laminated on a conductive support, the crosslinkable charge transport layer has at least a trifunctional function having no charge transport structure. It is formed by curing the above radical polymerizable monomer and a radical polymerizable compound having a monofunctional charge transport structure, and the thickness of the crosslinkable charge transport layer is 2 μm or more and 8 μm or less, At least one or more selected from the group consisting of an electrophotographic photosensitive member charged by applying a DC voltage to a charging member in contact with the surface of the photographic photosensitive member, and a charging unit, a developing unit, and a cleaning unit having a charging member. The process cartridge is integrally supported and is detachable from the electrophotographic apparatus main body.
[4] In an electrophotographic apparatus having an electrophotographic photosensitive member, a charging means having a charging member, an image exposing means, a developing means, and a transferring means, the electrophotographic photosensitive member has at least a charge generation layer and a charge transport layer on a conductive support. An electrophotographic photosensitive member in which a layer and a crosslinkable charge transport layer are sequentially laminated, wherein the crosslinkable charge transport layer has at least a trifunctional or higher-functional radical polymerizable monomer and a monofunctional charge transport structure The cross-linkable charge transport layer has a thickness of 2 μm or more and 8 μm or less, and the charging member is in contact with the surface of the electrophotographic photosensitive member. An electrophotographic apparatus, wherein the electrophotographic photosensitive member is charged by applying an electric current.

The electrophotographic photosensitive member according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an electrophotographic photosensitive member of the present invention. On a conductive support (1), a charge generation layer (5) having a charge generation function and a charge transport layer having a charge transport material function. A photoconductor having a laminated structure in which (7) and a cross-linked charge transport layer (9) are further laminated.

<About conductive support>
As the conductive support (1), a material having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, oxidation Metal oxide such as indium is deposited or sputtered to form film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. After conversion, a tube that has been subjected to surface treatment such as cutting, superfinishing, or polishing can be used. Further, an endless nickel belt and an endless stainless steel belt disclosed in JP-A-52-36016 can be used as the conductive support (1).
In addition, the conductive support dispersed in a suitable binder resin and coated on the support can also be used as the conductive support (1) of the present invention.

  Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. Can be 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-vinyl carbazole, 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.

  Furthermore, it is electrically conductive by a heat-shrinkable tube containing the conductive powder in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the conductive support (1) of the present invention.

<About photosensitive layer>
(Charge generation layer)
The charge generation layer (5) 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 fluorenone skeleton, azo pigments having oxadiazole skeleton, azo pigments having bis-stilbene skeleton, azo pigments having distyryl oxadiazole skeleton, azo pigments having 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.

  Binder resins used as necessary for the charge generation layer (5) include 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 can be used. A polymer material having a polysilane skeleton can also be used.

  Specific examples of the former include JP-A-01-001728, JP-A-01-009964, JP-A-01-013061, JP-A-01-019049, JP-A-01-241559, Japanese Unexamined Patent Publication Nos. 04-011627, 04-175337, 04-183719, 04-2225014, 04-230767, 04-320420, 05 -232727, JP-A 05-310904, JP-A 06-234836, JP-A 06-234837, JP-A 06-234838, JP-A 06-234839, JP-A 06-234840. No. 1, JP-A 06-234841, JP-A 06-239049, Japanese Unexamined Patent Publication Nos. 06-236050, 06-236051, 06-295077, 07-0756374, 08-176293, 08-208820, 08 No. -21640, JP 08-253568, JP 08-269183, JP 09-062019, JP 09-043883, JP 09-71642, JP 09-87376. No. 1, JP-A 09-104746, JP 09-110974, JP 09-110976, JP 09-157378, JP 09-221544, JP 09-227669. JP 09-235367 A, JP 09-241369 A Charge transporting polymer materials described in JP 09-268226 A, JP 09-272735 A, JP 09-302084 A, JP 09-302085 A, JP 09-328539 A, etc. Can be mentioned.

  Specific examples of the latter include polysilylene polymers described in, for example, JP-A No. 63-285552, JP-A No. 05-19497, JP-A No. 05-70595, JP-A No. 10-73944, and the like. Illustrated.

The charge generation layer (5) may contain a low molecular charge transport material.
Low molecular charge transport materials that can be used in combination with the charge generation layer (5) 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.

The method for forming the charge generation layer (5) mainly includes 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.

(About charge transport layer)
The charge transport layer (7) is a layer having a charge transport function. A charge transport material having a charge transport function and a binder resin are dissolved or dispersed in an appropriate solvent, and this is coated on the charge generation layer (5) and dried. To form. Generally, there is a concern that the adhesiveness with the charge generation layer may be insufficient due to reasons such as the carrier mobility is small and the sensitivity is lowered only with the cross-linked charge transport layer. Therefore, a charge transport layer (7) is provided to maintain adhesion with the charge generation layer.
As the charge transport material, the electron transport material, hole transport material and polymer charge transport material described in the charge generation layer (5) can be used. As described above, the use of the polymer charge transport material can reduce the solubility of the lower layer when the cross-linked charge transport 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 transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 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 charge transport layer, the same solvent as that used for the charge generation layer can be used, but a solvent that dissolves 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 charge transport layer (7) can be formed by the same coating method as the charge generation layer (5).

If necessary, a plasticizer and a leveling agent can be added.
As a plasticizer that can be used in combination with 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 0 with respect to 100 parts by weight of the binder resin. About 30 parts by weight is appropriate.
Leveling agents that can be used in combination with the charge transport layer include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. The amount used is a binder resin. About 0 to 1 part by weight is appropriate for 100 parts by weight.
The thickness of the charge transport layer is suitably about 5 to 40 μm, preferably about 10 to 30 μm. On the charge transport layer thus formed, the above-described crosslinkable charge transport layer coating solution is applied, and after drying as necessary, a curing reaction is initiated by external energy of heat or light irradiation, and the crosslinkable A charge transport layer is formed.

<About the cross-linked charge transport layer (9)>
The crosslinkable charge transport layer (shown by hatching in FIG. 3) is a layer having a crosslink structure having a charge transport function, and at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a monofunctional charge transport property. The radically polymerizable compound having a structure is dissolved or dispersed in an appropriate solvent, and this is formed on the charge transport layer (7) by coating and drying.

The constituent material of the crosslinking type charge transport layer (9) coating solution of the present invention will be described.
The trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the present invention is a hole transport structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano. A monomer having no electron transport structure such as an electron-withdrawing aromatic ring having a group or a nitro group and having three or more radically polymerizable functional groups. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and is capable of radical polymerization. Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.
(1) Examples of the 1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = CH—X ₁ −... Formula 10
In the formula, X ₁ is an arylene group such as an optionally substituted phenylene group or naphthylene group, an alkenylene group optionally having a substituent, a —CO— group, a —COO— group, —CON (R ₁₀ ) — group (R ₁₀ represents an alkyl group such as hydrogen, methyl group or ethyl group, an aralkyl group such as benzyl group, naphthylmethyl group or phenethyl group, or an aryl group such as phenyl group or naphthyl group. Or -S- group.

Specific examples of these substituents include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamide group, and a vinyl thioether group.
(2) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = CH (Y) -X ₂ -... Formula 11
(In the formula, Y is an aryl group such as an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, or a naphthyl group. Group, halogen atom, cyano group, nitro group, alkoxy group such as methoxy group or ethoxy group, -COOR ₁₁ group (R ₁₁ is a hydrogen atom, an alkyl such as an optionally substituted methyl group or ethyl group) Group, an aralkyl group such as benzyl which may have a substituent, a phenethyl group or the like, an aryl group such as a phenyl group or a naphthyl group which may have a substituent, or -CONR ₁₂ R ₁₃ (R ₁₂ and R ₁₃ is a hydrogen atom, which may have a substituent an alkyl group such as methyl group and ethyl group, which may have a substituent group benzyl group, naphthylmethyl group, or a, such as a phenethyl group, Alkyl group or a substituent a phenyl group which may have a represents an aryl group such as phenyl or naphthyl, which may be the same or different from each other.) Further, X ₂ is the same as X ₁ in the formula 10 A substituent, a single bond, or an alkylene group, provided that at least one of Y and X ₂ is an oxycarbonyl group, a cyano group, an alkenylene group, and an aromatic ring.

Specific examples of these substituents include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.
In addition, examples of the substituent further substituted with the substituent for X and Y include, for example, a halogen atom, a nitro group, an alkyl group such as a cyano group, a methyl group, and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, Examples thereof include aryloxy groups such as phenoxy group, aryl groups such as phenyl group and naphthyl group, aralkyl groups such as benzyl group and phenethyl group.
Among these radical polymerizable functional groups, acryloyloxy group and methacryloyloxy group are particularly useful, and a compound having three or more acryloyloxy groups is, for example, a compound having three or more hydroxyl groups in the molecule and an acrylic group. It can be obtained by using an acid (salt), an acrylic acid halide, or an acrylic ester to cause an ester reaction or a transesterification reaction. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

Specific examples of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure include the following, but are not limited to these compounds.
That is, examples of the radical polymerizable monomer used in the present invention include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, HPA-modified trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, and PO-modified. Trimethylolpropane triacrylate, caprolactone-modified trimethylolpropane triacrylate, HPA-modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, ECH-modified glycerol triacrylate, EO-modified glycerol triacrylate , PO-modified glycerol triacrylate, Lith (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkyl-modified dipentaerythritol pentaacrylate, alkyl-modified dipentaerythritol tetraacrylate, alkyl Modified dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, EO modified phosphoric acid triacrylate, 2,2,5,5-tetrahydroxymethylcyclopentanone tetraacrylate, etc. These may be used alone or in combination of two or more.

  The trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the present invention has a molecular weight relative to the number of functional groups in the monomer in order to form a dense crosslink in the crosslinkable charge transport layer. The ratio (molecular weight / functional group number) is preferably 250 or less. Further, when this ratio is larger than 250, the cross-linked charge transport layer is soft and wear resistance is somewhat lowered. Therefore, among the monomers exemplified above, monomers having a modifying group such as HPA, EO, PO are extremely It is not preferable to use a compound having a long modifying group alone. Further, the proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the crosslinkable charge transport layer is 20 to 80% by weight, preferably 30 to 70% by weight based on the total amount of the crosslinkable charge transport layer. %. When the monomer component is less than 20% by weight, the three-dimensional crosslink density of the crosslinkable charge transport layer is small, and a drastic improvement in wear resistance is not achieved as compared with the case of using a conventional thermoplastic binder resin. On the other hand, if it is 80% by weight or more, the content of the charge transporting compound is lowered, and the electrical characteristics are deteriorated. The electrical characteristics and abrasion resistance required differ depending on the process used, and the film thickness of the cross-linked charge transport layer of the photoreceptor varies accordingly. A range of 70% by weight is most preferred.

  The radical polymerizable compound having a monofunctional charge transport structure used in the crosslinkable charge transport layer (9) of the present invention is a hole transport structure such as triarylamine, hydrazone, pyrazoline, carbazole, etc. It refers to a compound having an electron transport structure such as polycyclic quinone, diphenoquinone, an electron-withdrawing aromatic ring having a cyano group or a nitro group, and having one radical polymerizable functional group. Examples of the radical polymerizable functional group include those shown in the above radical polymerizable monomer, and acryloyloxy group and methacryloyloxy group are particularly useful. In addition, a triarylamine structure is highly effective as a charge transporting structure, and in particular, when a compound represented by the structure of the following general formula (1) or (2) is used, electrical characteristics such as sensitivity and residual potential are good. To last.

（式中、Ｒ_１は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ_７（Ｒ_７は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ_８Ｒ_９（Ｒ_８及びＲ_９は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ_１、Ａｒ_２は置換もしくは未置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ_３、Ａｒ_４は置換もしくは未置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル基、アルキレンオキシカルボニル基を表わす。ｍ、ｎは０〜３の整数を表わす。）

(In the formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen Carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ may have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Ar ₁ and Ar ₂ each represent a substituted or unsubstituted arylene group, and may be the same or different.Ar ₃ , which may be the same or different from each other. Ar ₄ may be substituted Represents an unsubstituted aryl group, which may be the same or different, X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, An oxygen atom, a sulfur atom, or a vinylene group, Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, or an alkyleneoxycarbonyl group, and m and n represent an integer of 0 to 3.)

Specific examples of general formulas (1) and (2) are shown below.
In the general formulas (1) and (2), in the substituent of R ₁ , examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. The aralkyl group includes a benzyl group, a phenethyl group, and a naphthylmethyl group, and the alkoxy group includes a methoxy group, an ethoxy group, a propoxy group, and the like. These include a halogen atom, a nitro group, a cyano group, and a methyl group. Substituted with an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group or a naphthyl group, an aralkyl group such as a benzyl group or a phenethyl group, etc. May be.
Of the substituents for R ₁ , particularly preferred are a hydrogen atom and a methyl group.
Substituted or unsubstituted Ar ₃ and Ar ₄ are aryl groups, and examples of the aryl group include condensed polycyclic hydrocarbon groups, non-fused cyclic hydrocarbon groups, and heterocyclic groups.
The condensed polycyclic hydrocarbon group preferably has 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, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group , A chrycenyl group, a naphthacenyl group, and the like.

  Examples of the non-fused cyclic hydrocarbon group include monovalent groups of monocyclic hydrocarbon compounds such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether and diphenyl sulfone, or biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne, Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane, and polyphenylalkene, or ring assemblies such as 9,9-diphenylfluorene And monovalent groups of hydrocarbon compounds.

Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.
The aryl group represented by Ar ₃ or Ar ₄ may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group and the like.
(2) Alkyl groups, preferably C ₁ -C _12, especially C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkyl groups, further including fluorine atoms , a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, which may have a phenyl group substituted by an alkoxy group C 1 -C ₄ alkyl or _C 1 -C ₄ Good. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl 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.
(3) An alkoxy group (—OR ₂ ), and R ₂ represents the alkyl group defined in (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) An aryloxy group, and examples of the aryl group include a phenyl group and a naphthyl group. It _may contain an alkoxy group having C 1 -C _4, alkyl group, or a halogen atom C 1 -C ₄ 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, and specific examples include methylthio group, ethylthio group, phenylthio group, p-methylphenylthio group and the like.
(6)

（式中、Ｒ_３及びＲ_４は各々独立に水素原子、前記（２）で定義したアルキル基、またはアリール基を表わす。アリール基としては、例えばフェニル基、ビフェニル基又はナフチル基が挙げられ、これらはＣ_１〜Ｃ_４のアルコキシ基、Ｃ_１〜Ｃ_４のアルキル基またはハロゲン原子を置換基として含有してもよい。Ｒ_３及びＲ_４は共同で環を形成してもよい）
具体的には、アミノ基、ジエチルアミノ基、Ｎ−メチル−Ｎ−フェニルアミノ基、Ｎ，Ｎ−ジフェニルアミノ基、Ｎ，Ｎ−ジ（トリール）アミノ基、ジベンジルアミノ基、ピペリジノ基、モルホリノ基、ピロリジノ基等が挙げられる。
（７）メチレンジオキシ基、又はメチレンジチオ基等のアルキレンジオキシ基又はアルキレンジチオ基等が挙げられる。
（８）置換又は無置換のスチリル基、置換又は無置換のβ−フェニルスチリル基、ジフェニルアミノフェニル基、ジトリルアミノフェニル基等。

(In the formula, R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group defined in (2) above, or an aryl group. Examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group. these may form a ring _C 1 -C ₄ alkoxy _groups, C 1 -C a alkyl group or a halogen atom ₄ which may contain as substituents .R ₃ and _{R 4} jointly)
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) A substituted or unsubstituted styryl group, a substituted or unsubstituted β-phenylstyryl group, a diphenylaminophenyl group, a ditolylaminophenyl group, and the like.

The arylene group represented by Ar ₁ and Ar ₂ is a divalent group derived from the aryl group represented by Ar ₃ and Ar ₄ .

X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group.
The substituted or unsubstituted alkylene group is a C ₁ -C ₁₂ , preferably C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkylene group, and these alkylene groups include a fluorine atom, a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, a phenyl group substituted with an alkyl group or a _C 1 -C ₄ alkoxy group C 1 -C ₄ It may be. Specifically, methylene group, ethylene group, n-butylene group, i-propylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxyethylene Group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group and the like.
The substituted or unsubstituted cycloalkylene _group, a cyclic alkylene group of C 5 -C _7, these are the cyclic alkylene group fluorine atom, a hydroxyl _group, an alkyl group of C 1 -C _4, a C 1 -C ₄ It may have an alkoxy group. Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.
The substituted or unsubstituted alkylene ether group represents ethyleneoxy, propyleneoxy, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, tripropylene glycol, alkylene ether group alkylene group is hydroxyl group, methyl group, ethyl group, etc. You may have the substituent of.
The vinylene group is

で表わされ、
Ｒ_５は水素、アルキル基（前記（２）で定義されるアルキル基と同じ）、アリール基（前記Ａｒ_３、Ａｒ_４で表わされるアリール基と同じ）、ａは１または２、ｂは１〜３を表わす。

Represented by
R ₅ is hydrogen, an alkyl group (same as the alkyl group defined in (2) above), an aryl group (same as the aryl group represented by Ar ₃ or Ar ₄ above), a is 1 or 2, and b is 1 to 2 3 is represented.

Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, or an alkyleneoxycarbonyl group.
Examples of the substituted or unsubstituted alkylene group include the same alkylene groups as those described above for X.
Examples of the substituted or unsubstituted alkylene ether group include the alkylene ether group represented by X.
Examples of the alkyleneoxycarbonyl group include a caprolactone-modified group.

  Further, the radical polymerizable compound having a monofunctional charge transport structure of the present invention is more preferably a compound having a structure of the following general formula (3).

（式中、ｏ、ｐ、ｑはそれぞれ０又は１の整数、Ｒａは水素原子、メチル基を表わし、Ｒｂ、Ｒｃは水素原子以外の置換基で炭素数１〜６のアルキル基を表わし、ｓ、ｔは０〜３の整数を表わす。ｓ、ｔが２又は３等の複数の場合は、Ｒｂ、Ｒｃが異なっても良い。Ｚａは単結合、メチレン基、エチレン基、

(Wherein, o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, s , T represents an integer of 0 to 3. When s and t are a plurality of 2 or 3, Rb and Rc may be different, Za is a single bond, a methylene group, an ethylene group,

を表わす。）
上記一般式で表わされる化合物としては、Ｒｂ、Ｒｃの置換基として、特にメチル基、エチル基である化合物が好ましい。
本発明で用いる上記一般式（１）及び（２）特に（３）の１官能性の電荷輸送構造を有するラジカル重合性化合物は、炭素−炭素間の二重結合が両側に開放されて重合するため、末端構造とはならず、連鎖重合体中に組み込まれ、３官能以上のラジカル重合性モノマーとの重合で架橋形成された重合体中では、高分子の主鎖中に存在し、かつ主鎖−主鎖間の架橋鎖中に存在（この架橋鎖には１つの高分子と他の高分子間の分子間架橋鎖と、１つの高分子内で折り畳まれた状態の主鎖のある部位と主鎖中でこれから離れた位置に重合したモノマー由来の他の部位とが架橋される分子内架橋鎖とがある）するが、主鎖中に存在する場合であってもまた架橋鎖中に存在する場合であっても、鎖部分から懸下するトリアリールアミン構造は、窒素原子から放射状方向に配置する少なくとも３つのアリール基を有し、バルキーであるが、鎖部分に直接結合しておらず鎖部分からカルボニル基等を介して懸下しているため立体的位置取りに融通性ある状態で固定されているので、これらトリアリールアミン構造は重合体中で相互に程よく隣接する空間配置が可能であるため、分子内の構造的歪みが少なく、また、電子写真感光体の表面層とされた場合に、電荷輸送経路の断絶を比較的免れた分子内構造を採りうるものと推測される。
本発明の１官能の電荷輸送性構造を有するラジカル重合性化合物の具体例を以下に示すが、これらの構造の化合物に限定されるものではない。

Represents. )
As the compound represented by the above general formula, a compound having a methyl group or an ethyl group as a substituent for Rb and Rc is particularly preferable.
The radically polymerizable compound having a monofunctional charge transport structure represented by the general formulas (1) and (2), particularly (3) used in the present invention is polymerized with the carbon-carbon double bond open on both sides. Therefore, in a polymer that is not a terminal structure but is incorporated in a chain polymer and crosslinked by polymerization with a tri- or higher functional radical polymerizable monomer, it exists in the main chain of the polymer, and Present in the cross-linked chain between the chain and the main chain (this cross-linked chain has an intermolecular cross-linked chain between one polymer and another polymer, and a site where the main chain is folded in one polymer. And other intramolecular cross-linked chains that are cross-linked with other sites derived from the polymerized monomer at positions away from this in the main chain), but even if they are present in the main chain, Even if present, the triarylamine structure suspended from the chain moiety is It has at least three aryl groups arranged in the radial direction and is bulky, but is not directly bonded to the chain part, but is suspended from the chain part via a carbonyl group, etc. Since these triarylamine structures can be arranged adjacent to each other in the polymer, there is little structural distortion in the molecule, and the surface of the electrophotographic photosensitive member is also fixed. In the case of a layer, it is presumed that an intramolecular structure that is relatively free from interruption of the charge transport pathway can be adopted.
Specific examples of the radically polymerizable compound having a monofunctional charge transporting structure of the present invention are shown below, but are not limited to the compounds having these structures.

  Further, the radical polymerizable compound having a monofunctional charge transport structure used in the present invention is important for imparting the charge transport performance of the crosslinked charge transport layer. -80% by weight, preferably 30-70% by weight. If this component is less than 20% by weight, the charge transport performance of the crosslinkable charge transport layer cannot be maintained sufficiently, and deterioration of electrical characteristics such as a decrease in sensitivity and an increase in residual potential will occur with repeated use. On the other hand, if it is 80% by weight or more, the content of the trifunctional monomer having no charge transport structure is lowered, and the crosslink density is lowered, so that high wear resistance is not exhibited. The electrical characteristics and abrasion resistance required differ depending on the process used, and the film thickness of the cross-linked charge transport layer of the photoreceptor varies accordingly. A range of 70% by weight is most preferred.

The crosslinkable charge transport layer of the present invention is obtained by curing at least a trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers are used in combination for the purpose of imparting functions such as viscosity adjustment during coating, stress relaxation of the cross-linked charge transport layer, lower surface energy and reduced friction coefficient. be able to. Known radical polymerizable monomers and oligomers can be used.
Examples of the monofunctional radical monomer include 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl carbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, and cyclohexyl acrylate. , Isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, styrene monomer, and the like.
Examples of the bifunctional radical polymerizable monomer include 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1, Examples include 6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, EO-modified bisphenol A diacrylate, EO-modified bisphenol F diacrylate, and neopentyl glycol diacrylate.
Examples of the functional monomer include those substituted with a fluorine atom such as octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, 2-perfluoroisononylethyl acrylate, No. 60503, JP-B-6-45770, siloxane repeating units: 20-70 acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, diacryloyl polydimethylsiloxane Examples include vinyl monomers having a polysiloxane group such as diethyl, acrylates and methacrylates.
Examples of the radical polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers. However, if a large amount of monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers are contained, the three-dimensional crosslink density of the crosslinkable charge transport layer is substantially decreased, leading to a decrease in wear resistance. For this reason, the content of these monomers and oligomers is limited to 50 parts by weight or less, preferably 30 parts by weight or less, with respect to 100 parts by weight of the tri- or higher functional radical polymerizable monomer.
The crosslinked charge transport layer of the present invention is obtained by curing at least a trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Accordingly, a polymerization initiator may be contained in the crosslinking type charge transport layer coating solution in order to allow the curing reaction to proceed efficiently.

  Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di ( Peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) B) Peroxide-based initiators such as propane, azo-based compounds such as azobisisobutylnitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 4,4′-azobis-4-cyanovaleric acid Initiators are mentioned.

Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2- Acetophenone-based or ketal-based photopolymerization initiators such as methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether Benzoin ether photopolymerization initiators such as benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthones such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Examples of photopolymerization initiators and other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoic acid. Phenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10 -Phenanthrene, an acridine type compound, a triazine type compound, an imidazole type compound is mentioned. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples thereof include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.
These polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is 0.5 to 40 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total content having radical polymerizability.

  Furthermore, the crosslinkable charge transport layer coating liquid of the present invention may contain additives such as various plasticizers (for the purpose of stress relaxation and adhesion improvement), leveling agents, and low molecular charge transport materials having no radical reactivity. Can be contained. As these additives, known additives 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 solid content of the coating liquid. To 20% by weight or less, preferably 10% or less. 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.

  The crosslinkable charge transport layer of the present invention will be described later with a coating liquid containing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. It is formed by coating and curing on the charge transport layer. When the radically polymerizable monomer is a liquid, such a coating liquid can be applied by dissolving other components in the liquid, but if necessary, it is diluted with a solvent and applied. Solvents used at this time include alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, tetrahydrofuran, dioxane and propyl ether. Ethers such as dichloromethane, halogens such as dichloromethane, dichloroethane, trichloroethane, and chlorobenzene, aromatics such as benzene, toluene, and xylene, and cellosolves such as methyl cellosolve, ethyl cellosolve, and cellosolve acetate. These solvents may be used alone or in combination of two or more. The dilution ratio with the solvent varies depending on the solubility of the composition, the coating method, and the target film thickness, and is arbitrary. The coating can be performed using a dip coating method, spray coating, bead coating, ring coating method or the like.

In the present invention, after applying such a crosslinkable charge transport layer coating solution, energy is applied from the outside and cured to form a crosslinkable charge transport layer. The external energy used at this time includes heat, light, and the like. , There is radiation. The heat energy is applied by heating from the coating surface side or the support side using a gas such as air or nitrogen, steam, various heat media, infrared rays, or electromagnetic waves. The heating temperature is preferably 100 ° C. or more and 170 ° C. or less, and if it is less than 100 ° C., the reaction rate is slow and the curing reaction is not completely completed. When the temperature is higher than 170 ° C., the curing reaction proceeds non-uniformly, and large strains, a large number of unreacted residues, and reaction termination terminals are generated in the cross-linked charge transport 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 100 ° C. and then heating to 100 ° C. or more. As the energy of light, UV irradiation light sources such as high-pressure mercury lamps and metal halide lamps, which mainly have an emission wavelength in ultraviolet light, can be used, but a visible light source can also be selected according to the absorption wavelength of radically polymerizable substances and photopolymerization initiators. Is possible. Irradiation light amount is 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, it takes time for the curing reaction is less than 50 mW / cm ^2. If it is higher than 1000 mW / cm ^2, the progress of the reaction becomes non-uniform, and local flaws are generated on the surface of the cross-linked charge transport layer, or many unreacted residues and reaction termination ends are generated. In addition, internal stress increases due to rapid crosslinking, which causes cracks and film peeling. Examples of radiation energy include those using electron beams. Among these energies, those using heat and light energy are useful because of the ease of reaction rate control and the simplicity of the apparatus.

  The film thickness of the crosslinked charge transport layer of the present invention is 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less. If it is thicker than 10 μm, cracks and film peeling are likely to occur as described above, and if it is 8 μm or less, the margin is further improved, so that the crosslink density can be increased, and material selection and curing that further increases wear resistance. Conditions can be set. On the other hand, the radical polymerization reaction is prone to oxygen inhibition, that is, the surface in contact with the air is not easily cross-linked or non-uniform due to the effect of radical trapping by oxygen. This effect is noticeable when the surface layer is 1 μm or less, and the cross-linked charge transport layer having a thickness of less than this thickness is liable to cause a decrease in wear resistance or uneven wear. In addition, mixing of the lower layer charge transport layer component occurs during the application of the crosslinkable charge transport layer. If the coating thickness of the crosslinkable charge transport layer is thin, contaminants spread throughout the layer, which inhibits the curing reaction and lowers the crosslink density. For these reasons, the cross-linked charge transport layer of the present invention has a good wear resistance and scratch resistance at a film thickness of 1 μm or more, but a portion that is locally scraped to the lower charge transport layer is formed in repeated use. And the wear of the portion increases, and the density unevenness of the halftone image is likely to occur due to the chargeability and sensitivity fluctuation. Therefore, it is desirable that the film thickness of the crosslinkable charge transport layer be 2 μm or more for a longer life and higher image quality.

  The composition of the crosslinkable charge transport layer coating liquid includes radical polymerization in addition to the above-described trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. When a large amount of additives such as binder resins, antioxidants, and plasticizers that do not have a functional functional group are included, the crosslinking density is reduced, the cured product resulting from the reaction and phase separation of the above additives occur, and the organic solvent It becomes soluble to. Specifically, it is important to suppress the total content to 20% by weight or less with respect to the total solid content of the coating liquid. Further, in order not to dilute the crosslinking density, the total content of monofunctional or bifunctional radical polymerizable monomers, reactive oligomers, and reactive polymers is 20% by weight or less based on the trifunctional radical polymerizable monomers. It is desirable. Further, when a large amount of a radical polymerizable compound having a bifunctional or higher functional charge transporting structure is contained, a bulky structure is fixed in the crosslinked structure by a plurality of bonds, so that distortion is likely to occur. It is easy to become an aggregate. This can cause solubility in organic solvents. Although different depending on the compound structure, the content of the radical polymerizable compound having a bifunctional or higher functional charge transporting structure is preferably 10% by weight or less based on the radical polymerizable compound having a monofunctional charge transporting structure. Furthermore, in a structure in which a charge generation layer, a charge transport layer, and a crosslinkable charge transport layer are sequentially laminated, it is possible to achieve wear resistance and scratch resistance when the outermost crosslinkable charge transport layer is insoluble in an organic solvent. To preferred. In the constitution of the present invention, in order to make the crosslinkable charge transport layer insoluble in the organic solvent, (1) composition of the crosslinkable charge transport layer coating solution, adjustment of the content ratio thereof, (2) crosslinkable charge Dilution solvent of transport layer coating solution, adjustment of solid content concentration, (3) Selection of coating method of crosslinkable charge transport layer, (4) Control of curing condition of crosslinkable charge transport layer, (5) Charge of lower layer It is important to control these, such as making the transport layer difficult to dissolve, but it is not achieved by a single factor.

  Regarding the diluting solvent of the crosslinkable charge transport layer coating solution, if a solvent with a low evaporation rate is used, the remaining solvent may interfere with curing or increase the amount of the lower layer component mixed, resulting in uneven curing. And the cured density is reduced. For this reason, it tends to be soluble in organic solvents. Specifically, tetrahydrofuran, a mixed solvent of tetrahydrofuran and methanol, ethyl acetate, methyl ethyl ketone, ethyl cellosolve and the like are useful, but are selected according to the coating method. Moreover, regarding the solid content concentration, if it is too low for the same reason, it tends to be soluble in an organic solvent. Conversely, the upper limit concentration is constrained by the limitations of film thickness and coating solution viscosity. Specifically, it is desirable to use in the range of 10 to 50% by weight. As the coating method for the cross-linked charge transport layer, for the same reason, the solvent content at the time of forming the coating film, the method of reducing the contact time with the solvent is preferable, specifically, the spray coating method, the amount of coating liquid A ring coat method in which the above is regulated is preferable. In order to suppress the amount of the lower layer component mixed, it is also effective to use a polymer charge transport material as the charge transport layer and to provide an insoluble intermediate layer for the coating solvent for the cross-linked charge transport layer.

As curing conditions for the cross-linked charge transport layer, if the energy of heating or light irradiation is low, the curing is not completely completed and the solubility in the organic solvent is increased. On the other hand, when cured with very high energy, the curing reaction becomes non-uniform, and it tends to increase the number of uncrosslinked parts and radical stopping parts and to form an aggregate of minute cured products. For this reason, it may become soluble in an organic solvent. In order to insolubilize in an organic solvent, the heat curing conditions are preferably 100 to 170 ° C. and 10 minutes to 3 hours, and the curing conditions by UV light irradiation are 50 to 1000 mW / cm ² and 5 seconds to 5 minutes. In addition, it is desirable to control the temperature rise to 50 ° C. or less to suppress non-uniform curing reaction.

In the structure of the present invention, an example of a method for making the crosslinkable charge transport layer insoluble in an organic solvent is, for example, an acrylate monomer having three acryloyloxy groups and a triaryl having one acryloyloxy group as a coating solution. In the case of using an amine compound, the ratio of use is 7: 3 to 3: 7, and a polymerization initiator is added in an amount of 3 to 20% by weight based on the total amount of these acrylate compounds, and a solvent is added to the coating solution. To prepare. For example, in the charge transport layer that is the lower layer of the cross-linked charge transport layer, when the surface layer is formed by spray coating using a triarylamine donor as the charge transport material and polycarbonate as the binder resin, the above coating is used. As the solvent of the liquid, tetrahydrofuran, 2-butanone, ethyl acetate and the like are preferable, and the use ratio is 3 to 10 times the total amount of the acrylate compound.
Next, for example, the prepared coating solution is applied by spraying or the like on a photoreceptor in which an undercoat layer, a charge generation layer, and the charge transport layer are sequentially laminated on a support such as an aluminum cylinder. Then, it is naturally dried or dried at a relatively low temperature for a short time (25 to 80 ° C., 1 to 10 minutes) and cured by UV irradiation or heating.
For UV irradiation, uses a metal halide lamp, illuminance 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, for example, the case of irradiation with UV light of 200 mW / cm ^2, for example upon curing, the drum of a plurality of lamps What is necessary is just to irradiate the circumferential direction uniformly for about 30 seconds. At this time, the drum temperature is controlled so as not to exceed 50 ° C.
In the case of thermosetting, the heating temperature is preferably 100 to 170 ° C. For example, when a blowing oven is used as a heating means and the heating temperature is set to 150 ° C, the heating time is 20 minutes to 3 hours.
After completion of curing, the electrophotographic photosensitive member of the present invention is obtained by further heating at 100 to 150 ° C. for 10 to 30 minutes to reduce residual solvent.

The following factors can be cited as reasons why the object can be achieved by using the electrophotographic photosensitive member of the present invention.
The electrophotographic photosensitive member is used in an environment where a series of processes of a charging unit, a developing unit, a transfer unit, a cleaning unit, and a static eliminating unit are repeated. Causes life. Factors that cause this wear and scratch are (1) charging, decomposition of the photoreceptor surface composition due to discharge during static elimination and chemical degradation due to oxidizing gas, (2) carrier adhesion during development, (3) during transfer (4) Friction with cleaning brush, cleaning blade and intervening toner or adhering carrier at the time of cleaning. In order to design a photoreceptor that is resistant to these hazards, it is important that the surface layer has high hardness, high elasticity, and uniformity. From the film structure, there is a method of forming a dense and homogeneous three-dimensional network structure. Promising. Since the cross-linked charge transport layer corresponding to the surface of the present invention has a cross-linked structure obtained by curing a tri- or higher functional radical polymerizable monomer, a three-dimensional network structure is developed, and a high hardness and high elastic surface layer having a very high cross-linking density is provided. High abrasion resistance and scratch resistance are achieved. In this way, it is important to increase the crosslink density on the surface of the photoreceptor, that is, the number of crosslink bonds per unit volume. However, since a large number of bonds are instantaneously formed in the curing reaction, internal stress due to volume shrinkage occurs. This internal stress increases as the thickness of the cross-linked layer increases. Therefore, when the entire charge transport layer is cured, cracks and film peeling tend to occur. Even if this phenomenon does not appear initially, it may be likely to occur over time due to repeated use in the electrophotographic process and the influence of charging, development, transfer, cleaning hazards and thermal fluctuations. As a method for solving this problem, (1) a polymer component is introduced into the crosslinked layer and the crosslinked structure, (2) a large amount of monofunctional and bifunctional radically polymerizable monomers are used, and (3) a flexible group is introduced. Although the directionality which makes a cured resin layer soft, such as using the polyfunctional monomer which has, is mentioned, the crosslink density of a bridge | crosslinking layer becomes thin in any case, and remarkable wear resistance is not achieved. On the other hand, the photoconductor of the present invention is provided with a cross-linked charge transport layer having a high cross-linking density and having a three-dimensional network structure developed on the charge transport layer with a film thickness of 1 μm or more and 10 μm or less. No film peeling occurs and very high wear resistance is achieved. By selecting a film thickness of the crosslinkable charge transport layer of 2 μm or more and 8 μm or less, in addition to further improving the margin for the above problem, a material selection for increasing the crosslink density that leads to further improvement in wear resistance. Is possible. The reason why the photoconductor of the present invention can suppress cracking and film peeling is that the cross-linked charge transport layer can be made thin, so that the internal stress does not increase, and since the charge transport layer is provided in the lower layer, the surface of the cross-linked charge transport layer This is because internal stress can be relaxed. For this reason, it is not necessary to contain a large amount of polymer material in the cross-linked charge transport layer, and the polymer material and radical polymerizable composition (radical polymerizable monomer or radical polymerizable compound having a charge transport structure) generated at this time. Scratches and toner filming due to incompatibility with the cured product resulting from this reaction are unlikely to occur. Further, when a thick film over the entire charge transport layer is cured by light energy irradiation, light transmission from the absorption by the charge transport structure to the inside is limited, and a phenomenon in which the curing reaction does not proceed sufficiently may occur. In the cross-linked charge transport layer of the present invention, the curing reaction proceeds uniformly from a thin film of 10 μm or less to the inside, and high wear resistance is maintained inside as well as the surface. In addition, in the formation of the outermost surface layer of the present invention, in addition to the above trifunctional radical polymerizable monomer, a radical polymerizable compound having a monofunctional charge transporting structure is contained, which is a trifunctional or higher functional group. Incorporated into the cross-linking during curing of the radical polymerizable monomer. On the other hand, when a low molecular charge transport material having no functional group is contained in the cross-linked surface layer, precipitation of the low molecular charge transport material and white turbidity occur due to its low compatibility, and the cross-linked surface layer The mechanical strength also decreases. On the other hand, when a bifunctional or higher-functional charge transporting compound is used as the main component, the crosslink structure is fixed by a plurality of bonds and the crosslink density is further increased. However, the charge transporting structure is very bulky, so that the cured resin structure is distorted. Becomes very large, which increases the internal stress of the cross-linked charge transport layer.

  Furthermore, the photoreceptor of the present invention has good electrical characteristics, and thus high image quality can be realized over a long period of time. This is because a radically polymerizable compound having a monofunctional charge transporting structure is used as a constituent material of the crosslinkable charge transport layer and is immobilized in a pendant shape between the crosslinks. As described above, the charge transport material having no functional group causes precipitation and clouding phenomenon, and the electrical characteristics are remarkably deteriorated in repeated use such as reduction in sensitivity and increase in residual potential. When a bifunctional or higher-functional charge transporting compound is used as the main component, it is fixed in the crosslinked structure with a plurality of bonds, so the intermediate structure (cation radical) during charge transport cannot be kept stable, Sensitivity decreases due to traps and residual potential increases. Such deterioration of the electrical characteristics appears as an image such as a decrease in image density and thinning of characters. Furthermore, in the photoreceptor of the present invention, the high charge design with less charge trapping of the conventional photoreceptor can be applied as the lower charge transport layer, and the electrical side effects of the crosslinked charge transport layer can be minimized. .

  The cross-linked charge transport layer of the present invention is formed by curing a tri- or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Although a three-dimensional network structure develops and has a high crosslinking density, it contains from other than the above components (for example, mono- or bifunctional monomers, polymer binders, antioxidants, leveling agents, plasticizers and other additives and lower layers) In some cases, the cross-linking density is locally dilute or the aggregate is formed of fine cured products cross-linked with high density. Such a crosslinkable charge transport layer has a weak bonding force between cured products and is soluble in an organic solvent, and is repeatedly used in an electrophotographic process. Elimination is likely to occur. By making the cross-linkable charge transport layer insoluble in an organic solvent as in the present invention, the original three-dimensional network structure is developed and has a high degree of cross-linking, and the chain reaction proceeds in a wide range to obtain a cured product. Since the polymer has a high molecular weight, dramatic wear resistance is achieved.

<About the intermediate layer>
In the photoreceptor of the present invention, an intermediate layer is provided between the charge transport layer and the cross-linked charge transport layer for the purpose of suppressing charge transport layer component mixing into the cross-linked charge transport layer or improving adhesion between the two layers. It is possible. For this reason, as the intermediate layer, those which are insoluble or hardly soluble in the cross-linked charge transport layer coating solution are suitable, and generally a binder resin is 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. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

<About the undercoat layer>
In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support (1) and the photosensitive layer. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. 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, Al2O3 is provided by anodic oxidation, organic substances such as polyparaxylylene (parylene), and inorganic substances such as SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ 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>
Further, in the present invention, in order to improve environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, a cross-linked charge transport layer, a charge transport layer, a charge generation layer, an undercoat layer, an intermediate layer 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.

  Next, an example of the arrangement of the electrophotographic photosensitive member and the charging means according to the present invention is shown in FIG. As shown in the drawing, the charging member 21 is in contact with the electrophotographic photosensitive member 22 and charges the photosensitive member 22 by applying a DC voltage from a connected external power source 23.

  The charging member used in the present invention may be any known charging member, and examples thereof include a blade, a brush, and a belt in addition to the roller shown in FIG. When the charging member is a roller or blade, molding a conductive resin such as a conductive resin or carbon black, a metal or a metal oxide around a conductive metal core such as a metal or alloy It can be created by drying after application. Examples of the brush include a magnetic brush using magnetic particles, and a fur brush using a brush of a resin having the above conductivity or a resin subjected to a conductive treatment.

  FIG. 3 shows a specific example of a charging unit for pressing the charging member against the photosensitive member. The roller-shaped charging member 21 can be pressed against the photoconductor by the action of a spring 35 via a fulcrum 34, and the core metal 36 at the center of the charging member 21 is supplied with a voltage by a power supply brush 37 that contacts the roller. The Reference numeral 38 denotes a power receiving connector from the main body, and reference numeral 39 denotes a support for supporting the charging member 21 for mounting on the main body along the main body side guide rail.

<Image Forming Method and Apparatus>
Next, the electrophotographic apparatus of the present invention will be specifically described.
An example of the configuration of the electrophotographic apparatus of the present invention is shown in FIG. This apparatus has a roller-shaped charging member 21, an image exposing means 45, a developing means 46, a feeding roller and feeding guide 47, a transfer belt means 48, a cleaning means 49, and a pre-exposing means on the peripheral surface of the electrophotographic photosensitive member 22. 50 is arranged. In the image forming method, first, a DC voltage is applied to the charging member 21 disposed in contact with the electrophotographic photosensitive member 22 to charge the surface of the photosensitive member 22, and an image corresponding to the original is imaged by the image exposure means 45. The photosensitive member 22 is image-exposed to form an electrostatic latent image. Next, the electrostatic latent image on the photosensitive member 22 is developed (visualized) by attaching toner to the photosensitive member 22 by the developing means 46. Further, the toner image formed on the photosensitive member 22 is transferred onto a transfer material such as paper supplied through a paper supply roller and a paper supply guide 47 by a transfer charger 48 and is not transferred to the transfer material by a cleaning unit 49. The residual toner remaining on the photosensitive member 22 is collected. In the case where residual charges remain inside the photoconductor, it is better to discharge light by applying light to the photoconductor 22 by the pre-exposure means 50. On the other hand, the transfer material on which the toner image is formed is sent to a fixing unit (not shown) by a conveyance unit (not shown) to fix the toner image. In this electrophotographic apparatus, the light source of the image exposure means 45 can use halogen light, fluorescent lamp, laser light, or the like. Moreover, you may add another auxiliary | assistant process as needed.

  In the present invention, a plurality of components such as the electrophotographic photosensitive member 22, the charging member 21, the developing unit 46, and the cleaning unit 49 described above are integrally coupled as a process cartridge. You may comprise so that attachment or detachment is possible with respect to image forming apparatus main bodies, such as a copying machine and a laser beam printer. For example, at least one of the charging member 21, the developing unit 46, and the cleaning unit 49 is integrally supported with the photosensitive member to form a cartridge, and the process cartridge can be attached to and detached from the apparatus main body using guide means such as a rail of the apparatus main body. Also good.

<Synthesis example of compound having monofunctional charge transport structure>
The charge transporting compound having a monofunctional radical polymerizable functional group in the present invention is synthesized, for example, by the method described in Japanese Patent No. 3164426. An example of this is shown below.
(1) Synthesis of hydroxy group-substituted triarylamine compound (the following structural formula B) 113.85 g (0.3 mol) of a methoxy group-substituted triarylamine compound (the following structural formula A) and 138 g (0.92 mol) of sodium iodide To this, 240 ml of sulfolane was added and heated to 60 ° C. in a nitrogen stream. In this liquid, 99 g (0.91 mol) of trimethylchlorosilane was added dropwise over 1 hour and stirred at a temperature of about 60 ° C. for 4 and a half hours to complete the reaction. About 1.5 L of toluene was added to the reaction solution, cooled to room temperature, and washed repeatedly with water and an aqueous sodium carbonate solution. Thereafter, the solvent was removed from the toluene solution, and purification was performed by column chromatography (adsorption medium: silica gel, developing solvent: toluene: ethyl acetate = 20: 1). Cyclohexane was added to the obtained pale yellow oil to precipitate crystals. In this way, 88.1 g (yield = 80.4%) of white crystals of the following structural formula B was obtained.
Melting point: 64.0-66.0 ° C

(2) Triarylamino group-substituted acrylate compound (Exemplary Compound No. 54 in Table 1)
82.9 g (0.227 mol) of the hydroxy group-substituted triarylamine compound (Structural Formula B) obtained in (1) above was dissolved in 400 ml of tetrahydrofuran, and an aqueous sodium hydroxide solution (NaOH: 12.4 g, Water: 100 ml) was added dropwise. The solution was cooled to 5 ° C., and 25.2 g (0.272 mol) of acrylic acid chloride was added dropwise over 40 minutes. Then, it stirred at 5 degreeC for 3 hours, and reaction was complete | finished. The reaction solution was poured into water and extracted with toluene. This extract was repeatedly washed with an aqueous sodium bicarbonate solution and water. Thereafter, the solvent was removed from the toluene solution, and purification was performed by column chromatography (adsorption medium: silica gel, developing solvent: toluene). N-Hexane was added to the obtained colorless oil to precipitate crystals. In this way, Exemplified Compound No. As a result, 80.73 g (yield = 84.8%) of 54 white crystals were obtained.
Melting point: 117.5-119.0 ° C

As described above, according to the present invention, as a cross-linked charge transport layer of a photoreceptor in which a charge generation layer, a charge transport layer, and a cross-linked charge transport layer are laminated, a tri- or higher functional radical polymerizable property having no charge transport structure. By using an electrophotographic photosensitive member obtained by curing a monomer and a radically polymerizable compound having a monofunctional charge transporting structure, spot-like or streaky charging unevenness is unlikely to occur, potential fluctuation is small, and transfer memory is used. It is possible to provide an electrophotographic photosensitive member with a low content, a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.
Furthermore, by setting the film thickness to 1 μm or more and 10 μm, a highly durable and high-performance photoreceptor that does not generate cracks or film peeling, has high wear resistance and scratch resistance, and has good electrical characteristics. Is obtained. Therefore, it is possible to provide a high-performance and highly reliable image forming process, an image forming apparatus, and a process cartridge for an image forming apparatus that can provide a good image over a long period of time by using this photoconductor.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. Note that “parts” used in the examples all represent parts by weight.
<Example 1>
A 5% methanol solution of polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) was applied onto an aluminum cylinder of φ30 mm × 350 mm by a dipping method to provide an undercoat layer having a thickness of 0.3 μm. The aluminum cylinder was subjected to a cutting process so that moire was not generated.

  Next, 10 parts of an oxytitanium phthalocyanine pigment having strong peaks at 9.0 °, 14.2 °, 23.9 °, and 27.1 ° at diffraction angles 2θ ± 0.2 ° in X-ray diffraction of CuKα, 10 parts of polycarbonate Z resin (weight average molecular weight 28,000) and 60 parts of cyclohexane were dispersed in a sand mill apparatus using 1φ glass beads for 20 hours. A solution obtained by adding 100 parts of methyl ethyl ketone to this dispersion was applied onto the undercoat layer and dried to form a charge generation layer. The film thickness was 0.12 μm.

で示されるトリアリールアミン化合物７部と、 Next,

7 parts of a triarylamine compound represented by:

で示されるスチリル化合物３部をポリカーボネートＺ樹脂（重量平均分子量２８，０００）１０部及びモノクロルベンゼン６０部に溶解した。この溶液を上記電荷発生層上に塗布し、乾燥することによって電荷輸送層を形成した。乾燥後の膜厚は２０μｍであった。
さらにこの電荷輸送層上に下記組成の架橋型電荷輸送層用塗工液をスプレー塗工し、２０分自然乾燥した後、メタルハライドランプ：１６０Ｗ／ｃｍ、照射強度：５００ｍＷ／ｃｍ^２、照射時間：６０秒の条件で光照射を行ない、更に１３０℃で２０分乾燥を加え４μｍの架橋型電荷輸送層を設け、本発明の電子写真感光体を得た。

Was dissolved in 10 parts of polycarbonate Z resin (weight average molecular weight 28,000) and 60 parts of monochlorobenzene. This solution was applied onto the charge generation layer and dried to form a charge transport layer. The film thickness after drying was 20 μm.
Further, a coating solution for a cross-linked charge transport layer having the following composition was spray-coated on this charge transport layer, and after natural drying for 20 minutes, a metal halide lamp: 160 W / cm, irradiation intensity: 500 mW / cm ² , irradiation time: Light irradiation was performed for 60 seconds, followed by drying at 130 ° C. for 20 minutes to provide a 4 μm cross-linked charge transport layer to obtain the electrophotographic photoreceptor of the present invention.

[Coating liquid for cross-linked charge transport layer]
Trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure 10 parts Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99
10 parts of a radically polymerizable compound having a monofunctional charge transporting structure (Exemplary Compound No. 54)
Photoinitiator 1 part 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 100 parts

<Reference Example 1>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the film thickness of the crosslinked charge transport layer in Example 1 was changed to 1.3 μm.

<Example 2>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the film thickness of the crosslinked charge transport layer of Example 1 was changed to 7.7 μm.

<Example 3>
A radical having a monofunctional charge transport structure is replaced with the following monomer in place of the trifunctional or higher radical polymerizable monomer having no charge transport structure, which is contained in the coating liquid for the crosslinkable charge transport layer of Example 1. The polymerizable compound was exemplified as Compound No. 1. Instead of 138 and 10 parts, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the thickness of the crosslinked charge transport layer was changed to 5.4 μm.
10 parts of a radically polymerizable monomer having a trifunctional or higher functionality without a charge transporting structure
Pentaerythritol tetraacrylate
(SR-295, manufactured by Kayaku Sartomer)
Molecular weight: 352, number of functional groups: 4 functions, molecular weight / number of functional groups = 88

<Reference Example 2>
An electrophotographic photosensitive member was produced in the same manner as in Example 3 except that the thickness of the crosslinked charge transport layer in Example 3 was changed to 1.4 μm.

<Example 4>
An electrophotographic photosensitive member was produced in the same manner as in Example 3 except that the thickness of the cross-linked charge transport layer in Example 3 was changed to 7.7 μm.

<Example 5>
The trifunctional or higher functional radical polymerizable monomer having no charge transport structure contained in the coating liquid for the crosslinkable charge transport layer of Example 1 is replaced with the following monomer, and the photopolymerization initiator is replaced with 1 part of the following compound: Instead, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the film thickness of the cross-linked charge transport layer was 5.0 μm.
10 parts of a radically polymerizable monomer having a trifunctional or higher functionality without a charge transporting structure
Caprolactone-modified dipentaerythritol hexaacrylate
(KAYARAD DPCA-60, manufactured by Nippon Kayaku)
Molecular weight: 1263, number of functional groups: 6 functions, molecular weight / number of functional groups = 211
Photopolymerization initiator 1 part
2,2-dimethoxy-1,2-diphenylethane-1-one
(Irgacure 651, manufactured by Ciba Specialty Chemicals)

<Reference Example 3>
An electrophotographic photosensitive member was produced in the same manner as in Example 5 except that the thickness of the crosslinked charge transport layer in Example 5 was changed to 9.6 μm.

<Reference Example 4>
An electrophotographic photosensitive member was produced in the same manner as in Example 5 except that the thickness of the crosslinked charge transport layer in Example 5 was changed to 1.9 μm.

<Example 6>
An electrophotographic photosensitive member was produced in the same manner as in Example 5 except that the thickness of the crosslinked charge transport layer in Example 5 was changed to 2.4 μm.

<Comparative Example 1>
An electrophotographic photosensitive member of Comparative Example 1 was produced in the same manner as in Example 1 except that the cross-linked charge transport layer was not provided and the charge transport layer thickness was 25 μm.

で示されるアクリル系硬化性モノマー２５部、２−メチルチオキサントン２．０部及びトルエン３００部を混合した溶液をスプレー塗布し、乾燥後、高圧水銀灯にて８００ｍＷ／ｃｍ²の光強度で２０秒間紫外線照射することによって膜厚２．０μｍの保護層を形成した以外は実施例１と同様にして比較例２の電子写真感光体を作製した。 <Comparative example 2>
In Example 1, the cross-linking charge transport layer was not provided on the charge transport layer, and the following structural formula

A solution obtained by mixing 25 parts of an acrylic curable monomer, 2.0 parts of 2-methylthioxanthone and 300 parts of toluene is spray-coated, dried, and then irradiated with ultraviolet light at a light intensity of 800 mW / cm ² for 20 seconds using a high-pressure mercury lamp. An electrophotographic photoreceptor of Comparative Example 2 was produced in the same manner as in Example 1 except that a protective layer having a thickness of 2.0 μm was formed by irradiation.

  The obtained electrophotographic photosensitive member was mounted on a laser jet III-Si (manufactured by Hewlett Packard) as an electrophotographic apparatus. First, a DC voltage is applied to the charging roller from the outside so that the photosensitive member charging potential is -700 V, and a halftone original of black and white repeated one dot at a time is used as a halftone original. As a manuscript, a manuscript of 1 dot black and 100 dots white horizontal lines was used repeatedly. When the obtained image is observed visually, streaks due to non-uniform charging on the image appear 5 or more in the image area for one round of the drum, x 4 to 1 are △, and those that do not appear are ◯. It was. (This evaluation was made at the initial stage and after 30,000 consecutive runs.)

  Further, in this state, the original is changed (character pattern with a printing rate of about 5%), 30,000 continuous images are taken out, the start and the last bright part potential (hereinafter abbreviated as VL) are measured, and the last VL |-| Starting VL | was defined as the VL change amount. Further, the film thickness of all layers after the initial copy and after copying 50,000 sheets was measured, and the wear amount was calculated from the difference. The results are shown in Table 4.

  Furthermore, the absolute value of the difference between VL when development and transfer were not performed and VL when development was not performed was defined as the transfer memory amount.

The results are shown in Table 4.

It is a figure which shows the example of a structure of the electrophotographic photoreceptor of this invention. It is a figure which shows the example of arrangement | positioning of the electrophotographic photoreceptor and charging means of this invention. FIG. 3 is a diagram illustrating an example of a charging unit for pressing a charging member against an electrophotographic photosensitive member. It is a figure which shows the example of a structure of the electrophotographic apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive support body 5 Charge generation layer 7 Charge transport layer 9 Crosslinkable charge transport layer 21 Charging member 22 Electrophotographic photosensitive member 23 External power supply 34 Support point 35 Spring 36 Core metal 37 Power supply brush 38 Power receiving connector 39 Support body 45 Image exposure means 46 Developing means 47 Paper feed roller and paper feed guide 48 Transfer charging means 49 Cleaning means 50 Pre-exposure means

Claims (4)

At least a charge generating layer on the conductive support, a charge-transporting layer and the crosslinked charge transporting layer sequentially in the laminated electrophotographic photoconductor, trifunctional or more radical without at least a charge transport structure is crosslinked charge transporting layer The electrophotographic photosensitive member is formed by curing a polymerizable monomer and a radical polymerizable compound having a monofunctional charge transporting structure, and the cross-linked charge transporting layer has a thickness of 2 μm or more and 8 μm or less. An electrophotographic photosensitive member charged by applying a DC voltage to a charging member in contact with the surface of the electrophotographic photosensitive member. The radical polymerizable functional group of the tri- or higher functional radical polymerizable monomer having no charge transport structure used in the cross-linked charge transport layer and the radical polymerizable compound having a monofunctional charge transport structure is an acryloyloxy group and / or The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is a methacryloyloxy group. In an electrophotographic photosensitive member in which at least a charge generation layer, a charge transport layer, and a crosslinkable charge transport layer are sequentially laminated on a conductive support, the crosslinkable charge transport layer has at least a trifunctional radical having no charge transport structure. The electrophotographic photosensitive member is formed by curing a polymerizable monomer and a radical polymerizable compound having a monofunctional charge transport structure, and the cross-linked charge transport layer has a thickness of 2 μm or more and 8 μm or less. At least one means selected from the group consisting of an electrophotographic photosensitive member that is charged by applying a DC voltage to a charging member that is in contact with the surface, a charging means having a charging member, a developing means, and a cleaning means. A process cartridge which is integrally supported and is detachable from an electrophotographic apparatus main body. In an electrophotographic apparatus having an electrophotographic photosensitive member, a charging means having a charging member, an image exposing means, a developing means, and a transferring means, the electrophotographic photosensitive member has at least a charge generation layer, a charge transport layer, and a crosslink on a conductive support. Electrophotographic photosensitive member in which type charge transport layers are sequentially laminated, wherein the crosslinkable charge transport layer has at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical having a monofunctional charge transport structure It is formed by curing a polymerizable compound, and the thickness of the cross-linked charge transport layer is 2 μm or more and 8 μm or less, and the charging member is in contact with the surface of the electrophotographic photosensitive member, and a direct current is applied. The electrophotographic photosensitive member is charged with the electrophotographic photosensitive member.

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