JP2006011014A - Electrophotographic photosensitive member, image forming method using the same, image forming apparatus, and process cartridge for image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high wear resistance, high scratch resistance, good electrical characteristics, excellent film smoothness by uniform curing over the entire crosslinked surface layer, good cleaning characteristics, and high durability. It is an object of the present invention to provide an electrophotographic photosensitive member having high image quality over a long period of time.
SOLUTION: A surface layer has at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure, a radical polymerizable compound having a monofunctional charge transport structure, and a crosslinked layer obtained by curing a radical polymerizable phenol compound. An electrophotographic photosensitive member comprising a photosensitive layer or a cross-linked layer obtained by curing a radically polymerizable hindered amine compound, an image forming method using the same, an image forming apparatus, and a process cartridge for the image forming apparatus are provided.
[Selection] Figure 2

Description

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

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

On the other hand, the diameter of the photoconductor has recently been reduced due to the downsizing of the image forming apparatus, and the high speed of the machine and the maintenance-free movement have been added to increase the durability of the photoconductor. From this point of view, organophotoreceptors are generally soft because the surface layer is mainly composed of low-molecular charge transport materials and inert polymers, and when used repeatedly in electrophotographic processes, they are mechanically driven by development systems and cleaning systems. There is a drawback that wear is likely to occur due to a typical load. 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 the 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 for the surface layer (see, for example, Patent Document 1), and (2) using a polymeric charge transport material ( For example, refer patent document 2), (3) what dispersed the inorganic filler in the surface layer (for example, refer patent document 3), etc. are mentioned. 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 wear resistance than a photoconductor in which a normal low molecular charge transport material is dispersed in an inert polymer, but traps present on the surface of the inorganic filler. As a result, the residual potential rises and the image density tends to decrease. In addition, when the unevenness of the inorganic filler and the binder resin on the surface of the photoconductor is large, defective cleaning may occur, which may cause toner filming and image flow. 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 4). However, in this photoreceptor, although there is a description that the polyfunctional acrylate monomer cured product is contained in the protective layer provided on the photosensitive layer, the protective layer may contain a charge transport material. However, when the surface layer contains a low-molecular charge transport material, there is a problem of compatibility with the cured product. In some cases, the molecular charge transport material is precipitated and the cloudiness phenomenon occurs, and the mechanical strength is also lowered.
Furthermore, since this photoconductor specifically reacts with a monomer in a state containing a polymer binder, there is a problem that the curing does not proceed sufficiently and there is a problem of compatibility between the cured product and the binder resin. There was a tendency for surface irregularities due to separation to cause poor cleaning.

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. The binder resin has a carbon-carbon double bond and is reactive with the charge transfer agent, and the double resin is known to be provided. Those having no bond and no reactivity are included. 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 was poor, and surface irregularities were generated during cross-linking from layer separation, and a tendency to cause poor cleaning was observed. In addition, as described above, in this case, the binder resin prevents the curing of the monomer, and what is specifically described as the monomer used in the photoreceptor is a bifunctional one. The monomer has a small number of functional groups and a sufficient crosslinking density cannot be obtained, and these points have not yet been satisfactory in terms of wear resistance. In addition, even when a reactive binder is used, it is difficult to achieve both the binding amount and the crosslinking density of the charge transport material due to the low number of functional groups contained in the monomer and the binder resin, and the electrical characteristics. In addition, the wear resistance 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 6).

However, in this photosensitive layer, the bulky hole transporting compound has two or more chain-polymerizable functional groups, so that distortion occurs in the cured product, resulting in high internal stress, resulting in rough surface layers and cracks over time. It may be easy to do.
Furthermore, it is unavoidable that the cured layer is deteriorated by a reactive gas such as ozone generated in the charging process of a copying machine or a printer, or the influence of the reactive gas at the interface between the charge generation layer and the charge transport layer. The repeated use of the body has the disadvantage that the charging potential is lowered and the residual potential is raised. In order to improve such a defect, it is known that a hydroquinone derivative is contained in the photosensitive layer (Patent Document 7), and a hindered amine compound is known (Patent Document 8). In addition, it is known that an electrophotographic photoreceptor using a polymer charge transport material for a charge transport layer contains a compound having a hindered phenol structure and a hindered amine structure in one molecule (Patent Document 9). It is known that a hindered amine compound is contained in an electrophotographic photoreceptor using a polymer charge transport material for a charge transport layer (Patent Document 10).

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 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent No. 3262488 Japanese Patent No. 3194392 JP 2000-66425 A JP-A-6-214416 JP-A-6-752036 JP 9-319106 A JP 9-319112 A

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

  As a result of intensive studies, the present inventors have found that the surface layer has at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure, a radical polymerizable compound having a monofunctional charge transport structure, and radical polymerizability. A photosensitive layer comprising a cross-linked layer obtained by curing a phenol compound, or a radical polymerizable compound having a trifunctional or higher functional radical monomer having a charge transport structure at least on a surface layer and a radical polymerizable compound having a monofunctional charge transport structure, and radical polymerization The present invention has been accomplished by discovering that the object can be achieved by a photosensitive layer comprising a crosslinked layer obtained by curing a conductive hindered amine compound.

  That is, the above-mentioned problem is (1) “a trifunctional or higher functional radical in which the surface layer of the photosensitive layer has at least a charge transporting structure in an electrophotographic photosensitive member having at least a photosensitive layer on a conductive support. An electrophotographic photosensitive member comprising a polymerizable monomer, a radical polymerizable compound having a monofunctional charge transport structure, and a crosslinked layer obtained by curing the radical polymerizable phenol compound, "(2)" conductive support. An electrophotographic photoreceptor having at least a photosensitive layer thereon, wherein the surface layer of the photosensitive layer has 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. And an electrophotographic photosensitive member comprising a crosslinked layer obtained by curing a radically polymerizable hindered amine compound, and (3) the crosslinked surface layer comprising: The electrophotographic photosensitive member according to the item (1) or (2) characterized by being cured by energy, thermal energy, or a combination thereof, and (4) “having a charge transporting structure used for the surface layer. The electrophotographic photosensitive member according to any one of (1) to (3) above, wherein the functional group of the radically polymerizable monomer having three or more functional groups is an acryloyloxy group and / or a methacryloyloxy group, (5) “The ratio of molecular weight to the number of functional groups (molecular weight / number of functional groups) in the trifunctional or higher-functional radical polymerizable monomer having no charge transport structure used for the surface layer is 250 or less” (1) to (4) the photosensitive member according to any one of items (6), (6) “functional group of radically polymerizable compound having a monofunctional charge transporting structure used for the surface layer” , An acryloyloxy group and / or a methacryloyloxy group, the electrophotographic photosensitive member according to any one of (1) to (5) above, (7) “monofunctional used in the surface layer” The electrophotographic photosensitive member according to any one of (1) to (6) above, wherein the charge transporting structure of the radical polymerizable compound having a charge transporting structure is a triarylamine structure ”, (8) “The radical polymerizable compound having a monofunctional charge transporting structure used for the surface layer is one or more of the following general formula (1) or (2): The electrophotographic photosensitive member according to any one of the above;

（式中、Ｒ₁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、−ＣＯＯＲ₇（Ｒ₇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ＣＯＮＲ₈Ｒ₉（Ｒ₈及びＲ₉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、Ａｒ₁、Ａｒ₂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。Ａｒ₃、Ａｒ₄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。）」、
（９）「前記表面層に用いられる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が下記一般式（３）の一種以上であること特徴とする前記（１）から（８）項のいずれか記載の電子写真感光体；

(Wherein R ₁ is 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 represents 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 Ali substituted or unsubstituted X may be the same or different, and X is 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, sulfur An 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). "
(9) “Any of the above-mentioned (1) to (8), wherein the radical polymerizable compound having a monofunctional charge transporting structure used for the surface layer is one or more of the following general formula (3): Or an electrophotographic photosensitive member according to claim 1;

（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、複数の場合は異なっても良い。ｓ、ｔは０〜３の整数を表わす。Ｚａは単結合、メチレン基、エチレン基；

を表わす。）」、（１０）「前記表面層に用いられる電荷輸送性構造を有しない３官能以上のラジカル重合性モノマーの成分割合が、架橋表面層全量に対し３０〜７０重量％であることを特徴とする前記（１）から（９）項のいずれかに記載の電子写真感光体」、（１１）「前記表面層に用いられるラジカル重合性フェノール化合物、あるいはラジカル重合性ヒンダードアミン化合物の成分割合が、架橋表面層全量に対し０．１〜１０重量％であることを特徴とする前記（１）から（１０）項のいずれかに記載の電子写真感光体」、（１２）「前記感光層が支持体側から電荷発生層、電荷輸送層、架橋表面層の積層構成であることを特徴とする前記（１）から（１１）項のいずれかに記載の電子写真感光体」、（１３）「前記感光層の電荷輸送層が高分子電荷輸送物質を含有することを特徴とする前記（１２）項に記載の電子写真感光体」、（１４）「前記高分子電荷輸送物質がトリアリールアミン構造を主鎖又は側鎖に有するポリカーボネートであることを特徴とする前記（１３）項に記載の電子写真感光体」により解決される。

(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, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group or an ethylene group;

Represents. ) ”, (10)“ The proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the surface layer is 30 to 70 wt% with respect to the total amount of the crosslinked surface layer. The electrophotographic photosensitive member according to any one of (1) to (9) above, (11) “the component ratio of the radical polymerizable phenolic compound or radical polymerizable hindered amine compound used in the surface layer is a cross-linked The electrophotographic photosensitive member according to any one of (1) to (10) above, wherein the photosensitive layer is 0.1 to 10% by weight relative to the total amount of the surface layer. The electrophotographic photosensitive member according to any one of (1) to (11) above, wherein the photosensitive layer is a laminated structure of a charge generation layer, a charge transport layer, and a crosslinked surface layer ”, (13)“ the photosensitive layer ” High charge transport layer The electrophotographic photosensitive member according to the above item (12), which contains a charge transport material, and (14) “The polymer charge transport material is a polycarbonate having a triarylamine structure in the main chain or side chain” This is solved by the electrophotographic photosensitive member according to item (13).

Further, the above-mentioned problem is (15) “Image formation characterized in that at least charging, image exposure, development and transfer are repeated using the electrophotographic photosensitive member according to any one of (1) to (14). Solved by “method”.
Further, the above problem is solved by (16) “an image forming apparatus comprising the electrophotographic photosensitive member according to any one of (1) to (14)”.
Further, the above-mentioned problem is selected from the group consisting of (17) “the electrophotographic photosensitive member according to any one of (1) to (14), a charging unit, a developing unit, a transfer unit, a cleaning unit, and a neutralizing unit. The image forming apparatus process cartridge has at least one means and is detachable from the main body of the image forming apparatus.

Hereinafter, the present invention will be described in detail.
The present invention relates to a radically polymerizable compound having a trifunctional or higher functional radical monomer and a monofunctional charge transportable structure, a radically polymerizable phenolic compound, or a radical having at least a surface layer of the photosensitive layer having no charge transportable structure. An electrophotographic photoreceptor comprising a cured cross-linked layer containing a polymerizable hindered amine compound, having high durability and realizing high image quality over a long period of time is achieved.

The reasons for this are as follows.
In the formation of the outermost surface layer of the photoreceptor of the present invention, a radically polymerizable monomer having three or more functional groups is used, whereby a three-dimensional network structure is developed and a high hardness surface layer having a very high degree of crosslinking is obtained. And high wear resistance is achieved.

  On the other hand, when only monofunctional and bifunctional radically polymerizable monomers are used, the cross-linking bond in the cross-linked surface layer becomes dilute, and a dramatic improvement in wear resistance cannot be achieved. When a polymer material is contained in the cross-linked surface layer, the development of the three-dimensional network structure is inhibited and the degree of cross-linking is lowered, so that sufficient wear resistance cannot be obtained as compared with the present invention. Furthermore, the compatibility between the polymer material and the cured product resulting from the reaction of the radical polymerizable composition (radical polymerizable monomer or radical polymerizable compound having a charge transporting structure) is poor, resulting in localized from phase separation. Wears and appears as a scratch on the surface. In addition, in the formation of the outermost surface phase 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. It is incorporated into the cross-linking bond when the radical polymerizable monomer is cured. 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, it is fixed in the cross-linked structure with a plurality of bonds, but the charge transporting structure is very bulky so that distortion occurs in the cured resin and cross-linking occurs. The internal stress of the surface layer increases, and cracks and scratches frequently occur due to carrier adhesion and the like.

  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 and is immobilized in a pendant shape between crosslinks. As described above, the charge transport material having no functional group causes precipitation and clouding phenomenon, and deterioration due to repeated use such as reduction in sensitivity and increase in residual potential is remarkable. 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 trapping 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.

  As described above, a highly durable photoconductor can be obtained by increasing the hardness of the surface, but charging deterioration and residual potential increase due to repeated use of the photoconductor occur. This is a reactive gas in the charging process. It is thought that this is due to the oxidation of the charge transporting material due to oxidization, the decomposition product due to the breakage of the binder resin chain, the reactive gas passing through the photosensitive layer and reaching the charge generating layer, and the resistance is lowered. Prevents intrusion from the surface into the inside or prevents reaction between the reactive gas and the charge transport material. Further, the radical polymerizable phenolic compound and the radical polymerizable hindered amine compound react and are incorporated into the crosslinked structure when cured, and do not decrease the hardness and mechanical strength of the cured layer.

Next, the constituent material of the outermost surface layer coating solution of the present invention will be described.
The trifunctional or higher functional radical polymerizable monomer having no charge transporting property used in the present invention is a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano group. And a monomer having no electron transport structure such as an electron-withdrawing aromatic ring having a nitro group and having three or more radical 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 a phenylene group or a naphthylene group which may have a substituent, an alkenylene group which may have 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 vinyl group, styryl group, 2-methyl-1,3-butadienyl group, vinylcarbonyl group, acryloyloxy group, acryloylamino group, vinylthioether group and the like.

(2) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = C (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 or phenethyl group which may have a substituent, an aryl group such as phenyl group or 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 an aralkyl group such as a phenethyl group, or, A phenyl group which may have a substituent, an aryl group such as a naphthyl group, which may be the same or different from each other.) Further, X ₂ is identical substituents and single and X ₁ of the formula 10 Represents a 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, or 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 ₁ , X ₂ , and Y include alkyl groups such as halogen atom, nitro group, cyano group, methyl group, and ethyl group, methoxy group, and ethoxy group. And an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group and a naphthyl group, and an aralkyl group such as a benzyl group and a phenethyl group.

Among the functional groups of these radical polymerizable monomers, acryloyloxy group and methacryloyloxy group are particularly useful, and compounds having three or more acryloyloxy groups are compounds having, for example, three or more hydroxyl groups in the molecule. And acrylic acid (salt), acrylic acid halide, and acrylic ester, and can be obtained by 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 is a ratio of molecular weight to the number of functional groups in the monomer in order to form a dense crosslink in the cross-linked surface layer. (Molecular weight / functional group number) is preferably 250 or less. Further, when this ratio is larger than 250, the crosslinked surface layer is soft and wear resistance is somewhat lowered. Therefore, among the monomers exemplified above, monomers having a modifying group such as HPA, EO, and PO are extremely long. It is not preferable to use one having a modifying group alone. In addition, the proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used for the surface layer is 20 to 80% by weight, preferably 30 to 70% by weight, based on the total amount of the crosslinked surface layer. Specifically, it depends on the ratio of the tri- or higher functional radical polymerizable monomer in the solid content of the coating liquid. When the monomer component is less than 20% by weight, the three-dimensional cross-linking density of the cross-linked surface 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 exceeds 80% by weight, the content of the charge transporting compound is lowered, and the electrical characteristics are deteriorated. Since the required wear resistance and electrical characteristics differ depending on the process used, it cannot be said unconditionally, but considering the balance of both characteristics, the range of 30 to 70% by weight is most preferable.

  The radical polymerizable compound having a monofunctional 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 group, A compound having an electron transport structure such as an electron-withdrawing aromatic ring having 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、Ｒ₁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、−ＣＯＯＲ₇（Ｒ₇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ＣＯＮＲ₈Ｒ₉（Ｒ₈及びＲ₉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、Ａｒ₁、Ａｒ₂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。Ａｒ₃、Ａｒ₄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, or a nitro 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), halogenated 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. Represents an aryl group, which may be the same or different from each other, and Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and 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. 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.

Among 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 fused 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, and these alkyl groups further contain 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、Ｒ₃及びＲ₄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Ｃ₁〜Ｃ₄のアルコキシ基、Ｃ₁〜Ｃ₄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。Ｒ₃及びＲ₄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。

(In the formula, R ₃ and R ₄ each independently represents 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 or Ar ₂ is a divalent group derived from the aryl group represented by Ar ₃ or 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 to} C ₁₂ , preferably C _{1 to} C ₈ , more preferably a C _{1 to} 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 is a C _{5 to} C ₇ cyclic alkylene group, and these cyclic alkylene groups include a fluorine atom, a hydroxyl group, a C _{1 to} C ₄ alkyl group, and a C _{1 to} C ₄ alkyl group. 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.

で表わされ、
Ｒ₅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Ａｒ₃、Ａｒ₄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。 The vinylene group is

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, 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.

（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、複数の場合は異なっても良い。ｓ、ｔは０〜３の整数を表わす。Ｚａは単結合、メチレン基、エチレン基、 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).
General formula (3)

(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, And s and t each represents an integer of 0 to 3. 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。

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.

また、本発明に用いられる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は、架橋表面層の電荷輸送性能を付与するために重要で、この成分は架橋表面層全量に対し２０〜８０重量％、好ましくは３０〜７０重量％である。この成分が２０重量％未満では架橋表面層の電荷輸送性能が充分に保てず、繰り返しの使用で感度低下、残留電位上昇などの電気特性の劣化が現れる。また、８０重量％を超えると電荷輸送構造を有しない３官能モノマーの含有量が低下し、架橋結合密度の低下を招き高い耐摩耗性が発揮されない。使用されるプロセスによって要求される電気特性や耐摩耗性が異なるため一概には言えないが、両特性のバランスを考慮すると３０〜７０重量％の範囲が最も好ましい。
本発明に用いられるラジカル重合性フェノール化合物は住友化学社からスミライザーＧＭ［下記（１）］、スミライザーＧＳ（Ｆ）［下記（２）］の商標で市販されている、またラジカル重合性ヒンダードアミン化合物は旭電化工業社からＬＡ−８７［下記（３）］，ＬＡ−８２［下記（４）］で市販されている。

Further, the radical polymerizable compound having a monofunctional charge transporting structure used in the present invention is important for imparting the charge transporting performance of the crosslinked surface layer, and this component is 20 to 80% by weight based on the total amount of the crosslinked surface layer. %, Preferably 30 to 70% by weight. When this component is less than 20% by weight, the charge transport performance of the crosslinked surface layer cannot be maintained sufficiently, and deterioration of electrical characteristics such as a decrease in sensitivity and an increase in residual potential appears with repeated use. On the other hand, if it exceeds 80% by weight, 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. Although the electrical characteristics and abrasion resistance required differ depending on the process used, it cannot be said unconditionally, but considering the balance of both characteristics, the range of 30 to 70% by weight is most preferable.
The radically polymerizable phenolic compound used in the present invention is commercially available from Sumitomo Chemical Co., Ltd. under the trademark of Sumilizer GM [following (1)], Sumilizer GS (F) [following (2)], and radically polymerizable hindered amine compounds are It is commercially available from Asahi Denka Kogyo Co., Ltd. as LA-87 [following (3)] and LA-82 [following (4)].

上記以外のヒンダードフェノール化合物は２，５−ジターシャリーブチルハイドロキノン、２，５−ジヒドロキシジフェニルメタン、２，５−ジヒドロキシジフェニール、２，６−ジメチルハイドロキノンなどのハイドロキノン誘導体をアルカリ溶液中、アクリルクロライド、あるいはメタクリルクロライドを反応させモノエステル化することで得られ、トルエン−酢酸エチル混合溶媒を展開溶媒としてカラムクロマトで単離される。

Hindered phenol compounds other than the above are hydroquinone derivatives such as 2,5-ditertiary butylhydroquinone, 2,5-dihydroxydiphenylmethane, 2,5-dihydroxydiphenyl, 2,6-dimethylhydroquinone in an alkaline solution, acrylic chloride, Alternatively, it is obtained by reacting methacryl chloride to make a monoester, and isolated by column chromatography using a toluene-ethyl acetate mixed solvent as a developing solvent.

Since these radically polymerizable phenolic compounds and hindered amine compounds react and are incorporated into the cured layer, they prevent deterioration of electrical characteristics without lowering mechanical strength. This component is 0.05 to 20% by weight, preferably 0.1 to 10% by weight, based on the total amount of the crosslinked surface layer. If it is 0.05% or less, the effect for preventing charging deterioration is low, and if it is 20% or more, a residual potential rise is not desired.
The surface layer of the present invention is obtained by curing 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. Monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers can be used in combination for the purpose of imparting functions such as viscosity adjustment at the time, stress relaxation of the cross-linked surface layer, lower surface energy and reduced friction coefficient. 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, when a large amount of monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers are contained, the three-dimensional cross-linking density of the cross-linked surface layer is substantially reduced, resulting in 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.
In addition, the surface layer of the present invention includes at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerization compound having a monofunctional charge transport structure and a photopolymerization initiator. Alternatively, examples of the thermal polymerization initiator and the photopolymerization initiator that are cured by using them together include the following.

  As thermal polymerization initiators, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, acetylacetone peroxide, methylcyclohexanone peroxide, cyclohexanone peroxide, isobutyryl peroxide, 2,4-dichlorobenzoyl peroxide, bis-3,5 , 5-trimethylhexanoyl peroxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5- (t-butyloxy) -hexane, 1,3 -Bis (t-butylperoxy-isopropyl) benzene, t-butylcumyl peroxide, di-tbutyl peroxide, 2,5-dimethyl-2,5- (di-t-butylperoxy) he Sun-3, tris- (t-butylperoxy) triazine, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, 2,2 -Di (t-butylperoxy) butane, 4,4-di-t-butylperoxyvaleric acid n-butyl ester, 2,2-bis (4,4-t-butylperoxycyclohexyl) propane, t-butylperoxyisobutyrate, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-3,5,5-trimethylhexaate, t-butylperoxybenzoate, di-t-butylperoxytrimethyladipate Peroxides such as azobisisobutyronitrile, azobisdimethylvaleronitrile, azobissi Azo-based, such as Russia hexyl nitrile is used.

  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 include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4'-dimethylaminobenzophenone, and the like.

These heat and photopolymerization initiators may be added to the coating solution, respectively, and one or more thermal polymerization initiators, or one or more photopolymerization initiators may be mixed and used. 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. The half-life of the thermal polymerization initiator is preferably 80 ° C. or higher, and if it is 50 ° C. or lower, the storage stability of the coating solution is deteriorated and the coating is cured.
Furthermore, the coating liquid of the present invention can 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 as required. 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 crosslinked surface layer of the present invention is formed by applying and curing 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. 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. And ethers such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene, aromatics such as benzene, toluene and xylene, 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 coating solution, energy is applied from the outside and cured to form a crosslinked surface layer. The external energy used at this time includes heat, light, and 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 80 ° C. or more and 170 ° C. or less, and if it is less than 80 ° C., the reaction rate is slow and the reaction is not completely completed. At a temperature higher than 170 ° C., the reaction proceeds non-uniformly and a large strain is generated in the crosslinked surface layer. In order to advance the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 50 ° C. and then heating to 100 ° C. or more. 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 the cross-linked surface layer becomes very rough. Examples of radiation energy include those using electron beams. Among these energies, those using heat and light energy are useful because of easy reaction rate control and simple apparatus.
Since the film thickness of the crosslinked surface layer of the present invention varies depending on the layer structure of the photoreceptor in which the crosslinked surface layer is used, it will be described later together with the layer structure.
In the present invention, in order to further improve the smoothness of the crosslinked surface layer, the crosslinked surface layer is uniformly cured, and a combination of photocuring and heat curing is preferred.
It has been found that those with poor surface smoothness tend to cause background staining due to poor cleaning, streak-like images, image flow in a high humidity environment, and thickening of characters. In order to improve the smoothness of the cross-linked surface layer of the present invention, it is desirable that the curing rate uniformly progresses without unevenness. It becomes yuzu skin-like, and is observed more noticeably as the film thickness is thicker.

  Although there is a mild improvement in the surface layer smoothness such as curing means and conditions with respect to these defects, it is worn out due to a decrease in hardness. A radically polymerizable compound having a bifunctional or higher charge transporting structure or a radically polymerizable compound having a bifunctional or higher functional charge transporting structure, although the addition of a binder resin can improve the smoothness of the photoreceptor surface. When it contains, internal stress will generate | occur | produce at the time of hardening reaction from the bulk of a charge transportable structure, and it will become easy to produce an unevenness | corrugation on the surface. In addition, when a polymer material such as a binder resin is included in the coating liquid, a polymer formed by a curing reaction of a radical polymerizable composition (radical polymerizable monomer and radical polymerizable compound having a charge transporting structure) is formed. Due to the poor compatibility, phase separation occurs and the surface of the crosslinked layer becomes uneven. Therefore, it is preferable not to use a radical polymerizable compound having a bifunctional or higher functional charge transporting structure or a binder resin.

  As for the dilution solvent of the coating solution, if a large amount of a solvent that dissolves the lower layer is used in a large amount, a composition such as a resin binder or a low molecular charge transport material in the lower layer is mixed into the outermost surface layer, which hinders the curing reaction Instead, it becomes the same state as when a large amount of the non-curing material is previously contained in the coating solution, which causes disorder of the crosslinked surface. On the other hand, when a solvent that does not dissolve the lower layer is used, the adhesion between the crosslinked surface layer and the lower layer is lowered, and crater-like repellency appears on the crosslinked surface layer due to volume shrinkage during the curing reaction, resulting in a severe surface roughness. These measures include using a mixed solvent to control the solubility of the lower layer, reducing the amount of solvent contained in the outermost coating layer by the liquid composition and coating method, and using a polymer charge transport material, etc., in the lower layer. For example, an intermediate layer having low solubility or an intermediate layer having good adhesion may be provided between the lower layer and the cross-linked surface layer.

In the cross-linked surface layer of the present invention, it is necessary to contain a bulky charge transporting structure in order to maintain electrical characteristics and to increase the cross-linking density in order to increase the strength. In curing after such surface layer coating, if very high energy is applied from the outside and the reaction proceeds rapidly, the curing proceeds unevenly and the unevenness of the cross-linked film surface becomes severe. For this reason, the thing using the heat | fever which can control reaction rate by heating conditions, the irradiation intensity | strength of light, and the amount of polymerization initiators, or the external energy of light is preferable.
In the case of using the crosslinked surface layer forming material of the present invention, for example, a technique for making the surface smooth is exemplified by, for example, an acrylate monomer having three acryloyloxy groups and one acryloyloxy group as a coating liquid. When the triarylamine compound having the above is used, the use ratio thereof is 7: 3 to 3: 7, and a photopolymerization initiator and a thermal polymerization initiator are used in combination, and these polymerization initiators are added to the total amount of these acrylate compounds. The coating solution is prepared by adding 3 to 20% by weight and further adding a solvent. For example, in the charge transport layer that is the lower layer of the cross-linked surface layer, when the surface layer is formed by spray coating using a triarylamine-based charge transport material as the charge transport material and polycarbonate as the binder resin, the above coating 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 dried at a relatively low temperature for a short time (25 to 80 ° C., 1 to 10 minutes), cured by UV irradiation, then thermally cured and uniformly cured in the film.
UV radiation curing is used a metal halide lamp, etc., 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, by rotating the drum All the surfaces may be uniformly irradiated for about 20 seconds. At this time, the drum temperature is controlled so as not to exceed 50 ° C. Next, in the heat curing, 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.

<About photosensitive layer>
Next, the photosensitive layer will be described. As shown in FIG. 1, the photosensitive layer may have a single layer structure (1-A) or a laminated structure (1-B).
In the case of a single layer structure, the photosensitive layer is a layer having a charge generation function and a charge transport function at the same time. In the case of the laminated structure (1-B), the photosensitive layer is composed of a charge generation layer having a charge generation function and a charge transport layer having a charge transport function.
Hereinafter, each of the photosensitive layer (33) having a laminated structure and the photosensitive layer (33) having a single layer structure will be described.

<Photosensitive layer comprising a charge generation layer and a charge transport layer>
(Charge generation layer)
As shown in FIG. 2, the charge generation layer (35) is a layer mainly composed of a charge generation material having a charge generation function, and a binder resin can be used in combination as required. 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.

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

Specific examples of the former include JP-A-01-001728, JP-A-01-009964, JP-A-01-013061, JP-A-01-019049, JP-A-01-241559, No. 04-011627, No. 04-175337, No. 04-183719, No. 04-2225014, No. 04-230767, No. 04-320420, No. 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. JP-A 09-104746, JP-A 09-110974, JP-A 09-110976, JP-A 09-157378, JP-A 09-221544, JP-A 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 (35) may contain a low molecular charge transport material.

Low molecular charge transport materials that can be used in combination with the charge generation layer (35) include hole transport materials and electron transport materials.
Examples of the electron transporting material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more.

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

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

(About charge transport layer)
The charge transport layer (37) is a layer having a charge transport function, and the crosslinked surface layer having a charge transport structure of the present invention is useful as a charge transport layer. When the cross-linked surface layer is the entire charge transport layer (37), the radical polymerizable composition (charge transport structure of the present invention is formed on the charge generation layer (35) as described in the above cross-linked surface layer preparation method. A coating solution containing a radically polymerizable monomer that does not have and a radically polymerizable compound having a monofunctional charge transporting structure; the same applies below) is applied, and if necessary, after drying, a curing reaction is initiated by external energy to cause crosslinking. A surface layer is formed. At this time, the film thickness of the crosslinked surface layer is 10 to 30 μm, preferably 10 to 25 μm. If it is thinner than 10 μm, a sufficient charging potential cannot be maintained, and if it is thicker than 30 μm, peeling from the lower layer tends to occur due to volume shrinkage during curing.
When the cross-linked surface layer is formed on the surface portion of the charge transport layer (37) and the charge transport layer (37) has a laminated structure, the lower layer portion of the charge transport layer has a charge transport material having a charge transport function and a binder. The resin is dissolved or dispersed in a suitable solvent, and this is formed on the charge generation layer (35) by coating and drying, and a coating solution containing the radical polymerizable composition of the present invention is coated thereon. Then, it is crosslinked and cured by external energy.

As the charge transport material, the electron transport material, hole transport material and polymer charge transport material described in the charge generation layer (35) can be used. As described above, the use of the polymer charge transport material can reduce the solubility of the lower layer when the surface layer is applied, and is particularly useful.
As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin And thermoplastic or thermosetting resins such as phenol resins and alkyd resins.

The amount of the charge 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 lower layer portion of the charge transport layer, the same solvent as that for the charge generation layer can be used, but a solvent that dissolves the charge transport material and the binder resin well is suitable. These solvents may be used alone or in combination of two or more. The lower layer portion of the charge transport layer can be formed by a coating method similar to that for the charge generation layer (35).
If necessary, a plasticizer and a leveling agent can be added.

As a plasticizer that can be used in combination with the lower layer portion of the charge transport layer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 100 parts by weight of the binder resin. On the other hand, about 0 to 30 parts by weight is appropriate.
As a leveling agent that can be used in combination with the lower layer portion of the charge transport layer, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain are used. About 0 to 1 part by weight is appropriate for 100 parts by weight of the binder resin.
The thickness of the lower layer portion of the charge transport layer is appropriately about 5 to 40 μm, preferably about 10 to 30 μm.
When the cross-linked surface layer is the surface portion of the charge transport layer (37), the radical polymerizable composition of the present invention is contained on the lower layer portion of the charge transport layer as described in the method for preparing a cross-linked surface layer. After the coating liquid is applied and dried as necessary, a curing reaction is initiated by external energy such as heat or light to form a crosslinked surface layer. At this time, the film thickness of the crosslinked surface layer is 1 to 20 μm, preferably 2 to 10 μm. If the thickness is less than 1 μm, the durability varies due to uneven film thickness. If the thickness is more than 20 μm, the entire thickness of the charge transport layer is increased, and the reproducibility of the image is reduced due to the diffusion of charges.

<Single photosensitive layer>
The photosensitive layer having a single layer structure is a layer having a charge generation function and a charge transport function at the same time, and the crosslinked surface layer having the charge transport structure of the present invention contains a charge generation material having a charge generation function, thereby providing a single layer structure. It is useful as a photosensitive layer. As described in the method for forming the charge generation layer, the charge generation material is dispersed together with the coating solution containing the radical polymerizable composition, applied onto the conductive support (31), and dried if necessary. Thereafter, a curing reaction is initiated by light and heat energy, and a crosslinked surface layer is formed. In addition, you may add the liquid in which the charge generation material was previously disperse | distributed with the solvent to this coating material for bridge | crosslinking surface layers. At this time, the film thickness of the crosslinked surface layer is 10 to 30 μm, preferably 10 to 25 μm. If the thickness is less than 10 μm, a sufficient charging potential cannot be maintained. If the thickness is more than 30 μm, peeling from the conductive substrate or the undercoat layer tends to occur due to volume shrinkage during curing.

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

When the cross-linked surface layer is the surface portion of the photosensitive layer having a single layer structure, the coating solution containing the radical polymerizable composition of the present invention and the charge generating material is applied onto the lower layer portion of the photosensitive layer as described above. After drying, if necessary, it is cured by external energy of heat and light to form a crosslinked surface layer. At this time, the film thickness of the crosslinked surface layer is 1 to 20 μm, preferably 2 to 10 μm. When the thickness is less than 1 μm, the durability varies due to the film thickness unevenness.
The charge generation material contained in the photosensitive layer having a single layer structure is preferably 1 to 30% by weight based on the total amount of the photosensitive layer, and the binder resin contained in the lower layer portion of the photosensitive layer is 20 to 80% by weight of the total amount. The transport material is preferably used in an amount of 10 to 70 parts by weight.

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

<About the undercoat layer>
In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support (31) 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, Al ₂ O ₃ is provided by anodic oxidation, organic substances such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ A material provided with an inorganic material such as a vacuum thin film can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

<Addition of antioxidant to each layer>
In the present invention, in order to improve environmental resistance, in order to prevent a decrease in sensitivity and an increase in residual potential, a surface cross-linked layer, a photosensitive layer, a charge generation layer, a charge transport layer, an undercoat layer, an intermediate layer An antioxidant can be added to each layer such as a 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] Crycol esters, tocopherols, etc.

(Paraphenylenediamines)
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.
(Hydroquinones)
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone and the like.
(Organic sulfur compounds)
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.
(Organic phosphorus compounds)
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.
These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained.
The addition amount of the antioxidant in the present invention is 0.01 to 10% by weight based on the total weight of the layer to be added.

<Image Forming Method and Apparatus>
Next, the image forming method and the image forming apparatus of the present invention will be described in detail with reference to the drawings.
The image forming method and the image forming apparatus of the present invention use a photoconductor having a smooth charge transporting surface cross-linked layer. For example, at least after the photoconductor is charged, exposed to an image, and developed, the image is held. An image forming method and an image forming apparatus including a process of transferring a toner image onto a body (transfer paper), fixing, and cleaning of the surface of a photoreceptor.
In some cases, an image forming method or the like in which an electrostatic latent image is directly transferred to a transfer member and developed does not necessarily have the above-described process arranged on a photosensitive member.

FIG. 3 is a schematic diagram illustrating an example of an image forming apparatus. A charging charger (3) is used as a means for charging the photoconductor on average. As the charging means, a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or the like is used, and a known system can be used.
In particular, the configuration of the present invention is effective when a charging unit such as a contact charging method or a non-contact proximity arrangement charging method is used in which the photosensitive composition is decomposed by proximity discharge from the charging unit. The contact charging method referred to here is a charging method in which a charging roller, a charging brush, a charging blade, or the like is in direct contact with the photosensitive member. On the other hand, the proximity charging method is, for example, a type in which the charging roller is arranged in a non-contact state so as to have a gap of 200 μm or less between the surface of the photoreceptor and the charging means. If this gap is too large, the charging tends to become unstable, and if it is too small, the surface of the charging member may be contaminated when toner remaining on the photoreceptor exists. is there. Accordingly, the gap is suitably 10 to 200 μm, preferably 10 to 100 μm.

Next, the image exposure unit (5) is used to form an electrostatic latent image on the uniformly charged photoreceptor (1). As the light source, all luminescent materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL) can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.
Next, the developing unit (6) is used to visualize the electrostatic latent image formed on the photoreceptor (1). Development methods include a one-component development method using a dry toner, a two-component development method, and a wet development method using a wet toner. When the photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.

Next, the transfer charger (10) is used to transfer the toner image visualized on the photosensitive member onto the transfer member (9). In addition, a pre-transfer charger (7) may be used for better transfer. As these transfer means, a transfer charger, an electrostatic transfer method using a bias roller, a mechanical transfer method such as an adhesive transfer method and a pressure transfer method, and a magnetic transfer method can be used. As the electrostatic transfer method, the charging means can be used.
Next, a separation charger (11) and a separation claw (12) are used as means for separating the transfer body (9) from the photoreceptor (1). As other separation means, electrostatic adsorption induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like are used. As the separation charger (11), the charging means can be used.
Next, a fur brush (14) and a cleaning blade (15) are used to clean the toner remaining on the photoreceptor after transfer. Further, a pre-cleaning charger (13) may be used in order to perform cleaning more efficiently. Other cleaning means include a web method, a magnet brush method, and the like, but each may be used alone or in combination.

Next, a neutralizing unit is used for the purpose of removing the latent image on the photoreceptor as required. As the charge removal means, a charge removal lamp (2) and a charge removal charger are used, and the exposure light source and the charging means can be used respectively.
In addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.
The present invention is an image forming method and an image forming apparatus using the electrophotographic photoreceptor according to the present invention for such image forming means.

The image forming means may be fixedly incorporated in a copying apparatus, facsimile, or printer, but may be incorporated in these apparatuses in the form of a process cartridge and detachable. An example of the process cartridge is shown in FIG.
The process cartridge for the image forming apparatus includes a photoreceptor (101), and in addition, a charging unit (102), a developing unit (104), a transfer unit (106), a cleaning unit (107), and a discharging unit (not shown). ), And an apparatus (part) that can be attached to and detached from the image forming apparatus main body.
Referring to the image forming process by the apparatus illustrated in FIG. 4, the surface of the photoconductor (101) is exposed by charging by the charging means (102) and exposure by the exposure means (103) while rotating in the direction of the arrow. An electrostatic latent image corresponding to the image is formed, and the electrostatic latent image is developed with toner by the developing means (104). The toner development is transferred to the transfer body (105) by the transfer means (106), and printed. Be out. Next, the surface of the photoconductor after the image transfer is cleaned by a cleaning unit (107), and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

The present invention provides a process cartridge for an image forming apparatus in which a photosensitive member having a smooth charge transporting surface cross-linked layer and at least one of charging, developing, transferring, cleaning, and neutralizing means are integrated.
As is apparent from the above description, the electrophotographic photosensitive member of the present invention is not only used in electrophotographic copying machines, but also in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making. Can also be used widely.

  As described above, as is clear from the detailed and specific description, according to the present invention, a trifunctional or higher functional radical polymerizable monomer having no charge transporting structure, a monofunctional charge transporting structure, and a radical polymerizable phenolic compound are provided. In addition, the surface cross-linked layer containing a radical polymerizable hindered amine compound has high wear resistance, high charge stability, good electrical characteristics, and a highly durable and high performance photoreceptor. 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 Next, 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>
By coating and drying an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution in the following order on a φ30 mm aluminum cylinder in sequence, an undercoat layer of 3.5 μm A 0.2 μm charge generation layer and an 18 μm charge transport layer were formed. On this charge transport layer, a coating solution for a cross-linked surface layer having the following composition is spray-coated, and a metal halide lamp: 160 W / cm, irradiation distance: 120 mm, irradiation intensity: 500 mW / cm ² , irradiation time: 30 seconds. This was irradiated with light, and further heated at 130 ° C. for 20 minutes to provide a 4 μm surface cross-linked layer to obtain the electrophotographic photosensitive member of the present invention.
[Coating liquid for undercoat layer]
Alkyd resin (Beckosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals) 6 parts Melamine resin (Super Becamine G-821-60, manufactured by Dainippon Ink and Chemicals) 4 parts Titanium oxide 40 parts Methyl ethyl ketone 50 parts [Charge Generation layer coating solution]
Bisazo pigment pigment of the following structural formula (I) 2.5 parts Polyvinyl butyral (XYHL, manufactured by UCC) 0.5 part Cyclohexanone 200 parts Methyl ethyl ketone 80 parts

［電荷輸送層用塗工液］
ビスフェノールＺポリカーボネート（パンライトＴＳ−２０５０、
帝人化成製） １０部
下記構造式（II）の低分子電荷輸送物質（Ｄ−１） ７部
テトラヒドロフラン １００部
１％シリコーンオイルのテトラヒドロフラン溶液（ＫＦ５０
−１００ＣＳ、信越化学工業製） ０．２部

[Coating fluid for charge transport layer]
Bisphenol Z polycarbonate (Panlite TS-2050,
10 parts low molecular charge transport material (D-1) of the following structural formula (II) 7 parts Tetrahydrofuran 100 parts 1% silicone oil in tetrahydrofuran solution (KF50)
-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.2 parts

[Coating liquid for cross-linked surface layer]
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure:
Trimethylolpropane triacrylate (KAYARAD
TMPTA, manufactured by Nippon Kayaku) Molecular weight: 296, number of functional groups: trifunctional,
Molecular weight / number of functional groups = 99 10 parts Radical polymerizable compound having a monofunctional charge transporting structure:
(Exemplary Compound No. 53) 10 parts Photopolymerization initiator: 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals) 2 parts Phenol compound: 2-tertiary butyl-6- (3 -Thiref Leaf Chill-2-Hitoxy-5
-Methylbenzyl) -4-methylphenyl acrylate (Sumilyzer GM, manufactured by Sumitomo Chemical Co., Ltd.) 2 parts Tetrahydrofuran 100 parts In the same manner, an undercoat layer, a charge generation layer, a charge transport layer are provided, and a phenol compound and a hindered amine in the crosslinked surface layer A photoconductor was prepared in the same manner except that the compounds were changed to those shown in Table 1.

実施例２ 住友化学社製 スミライザーＧＳ（Ｆ）
実施例３

Example 2 Sumitizer GS (F) manufactured by Sumitomo Chemical Co., Ltd.
Example 3

で合成される。
実施例４ 旭電化工業社製 ＬＡ８２
実施例５ 旭電化工業社製 ＬＡ８７

Is synthesized.
Example 4 LA82 manufactured by Asahi Denka Kogyo Co., Ltd.
Example 5 LA87 manufactured by Asahi Denka Kogyo Co., Ltd.

Comparative Example 1
A photoreceptor was prepared in the same manner as in Example 1 without adding the phenol compound and hindered amine compound of the crosslinked surface layer.
Example 6
The electrophotographic photoreceptor as in Example 1 except that the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the crosslinked surface layer coating solution of Example 1 was replaced with the following monomer. Was made.
Trifunctional or higher radical polymerizable monomer having no charge transport structure: ditrimethylolpropane tetraacrylate (SR-355,
(Manufactured by Kayaku Sartomer) Molecular weight: 466, number of functional groups: tetrafunctional, molecular weight / number of functional groups = 117 10 parts In Examples 7 and 8, trifunctional or higher functional radical polymerizable monomers having no charge transport structure are An electrophotographic photosensitive member was obtained in place of those shown in Table 2, and Comparative Example 2 used a bifunctional radically polymerizable monomer having no charge transporting structure.

（旭電化工業 ＬＡ８２） ２部
テトラヒドロフラン １００部 Example 9
In the same manner as in Example 1, an undercoat layer, a charge generation layer, and a charge transport layer were sequentially provided on the photoconductor, and coated with the following crosslinked surface layer coating solution to obtain an electrophotographic photoconductor.
[Coating liquid for cross-linked surface layer]
Trifunctional or more radically polymerizable monomer having no charge transporting structure: trimethylolpropane triacrylate (KAYARAD)
TMPTA, manufactured by Nippon Kayaku) Molecular weight: 296, number of functional groups: trifunctional,
Molecular weight / number of functional groups = 99 10 parts Radical polymerizable compound having monofunctional charge transport structure: (Exemplary Compound No. 47) 10 parts Photopolymerization initiator: 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, Ciba (Specialty Chemicals) 2 parts Radical polymerizable hindered amine compounds:

(Asahi Denka Kogyo LA82) 2 parts Tetrahydrofuran 100 parts

Example 10
In the same manner as in Example 1, the following charge transport layer was provided on the undercoat layer and the charge generation layer, and the following crosslinked surface layer was further provided thereon [Coating liquid for charge transport layer]
Polymer charge transport material (PD-1) having the following structural formula: 15 parts

熱重合開始剤：ｔ−ブチル−パーオキシ−２−エチルヘキサノエート
（カヤエステルＯ 化薬アクゾ製） ２部
テトラヒドロフラン １００部 Tetrahydrofuran 100 parts 1% silicone oil in tetrahydrofuran (KF50
-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.3 parts [Coating liquid for cross-linked surface layer]
Trifunctional or higher radical polymerizable monomer having no charge transporting structure: trimethylolpropane triacrylate (KAYARAD)
TMPTA, manufactured by Nippon Kayaku) Molecular weight: 296, number of functional groups: trifunctional,
Molecular weight / number of functional groups = 99 10 parts Radical polymerizable compound having monofunctional charge transport structure: (Exemplary Compound No. 45) 10 parts Photopolymerization initiator: 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, Ciba (Specialty Chemicals) 2 parts Radical polymerizable phenol compound 1 part

Thermal polymerization initiator: t-butyl-peroxy-2-ethylhexanoate (manufactured by Kayaester O Kayaku Akzo) 2 parts Tetrahydrofuran 100 parts

Comparative Example 3
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the cross-linked surface layer of Example 1 was not provided and the thickness of the charge transport layer was 22 μm.
The electrophotographic photosensitive members of Examples 1 to 10 and Comparative Examples 1 to 3 were subjected to a paper passing test of 40,000 A4 sizes. First, the photosensitive member was mounted on a process cartridge for an electrophotographic apparatus, and the initial dark portion potential was set to −700 V with a Ricoh imagio Neo 270 remodeling machine using a 655 nm semiconductor laser as an image exposure light source. Thereafter, a paper feeding test was started, and the darkness (VD) and exposure part potential (VL) after copying 50,000 sheets at the initial stage and the film thickness reduction after copying 50,000 sheets were measured. The results are shown in Table 3.

  From the results of the paper passing test shown in the table, the photoreceptor having the crosslinked surface layer of the present invention shown in Examples 1 to 10 has high wear resistance and good electrical characteristics, and a good image is obtained over time. It is done. On the other hand, the photoconductors of the crosslinked surface layers of Comparative Examples 1 to 3 are inferior in wear resistance or electrical characteristics and all have low durability.

1 is an example of a cross-sectional view of an electrophotographic photosensitive member of the present invention. It is another example of sectional drawing of the electrophotographic photosensitive member of this invention. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. FIG. 2 is a schematic diagram illustrating an example of a process cartridge for an image forming apparatus according to the present invention.

Explanation of symbols

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

Claims (17)

In an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, the surface layer of the photosensitive layer has at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a monofunctional charge transport structure. An electrophotographic photoreceptor comprising a radically polymerizable compound and a crosslinked layer obtained by curing a radically polymerizable phenolic compound. In an electrophotographic photoreceptor having at least a photosensitive layer on a conductive support, the surface layer of the photosensitive layer has at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a monofunctional charge transport structure. An electrophotographic photoreceptor comprising a radically polymerizable compound and a crosslinked layer obtained by curing a radically polymerizable hindered amine compound. 3. The electrophotographic photosensitive member according to claim 1, wherein the crosslinked surface layer is cured by light energy, thermal energy, or a combination thereof. The functional group of a tri- or more functional radical polymerizable monomer having no charge transport structure used for the surface layer is an acryloyloxy group and / or a methacryloyloxy group. The electrophotographic photosensitive member described. The ratio of the molecular weight to the number of functional groups (molecular weight / number of functional groups) in the trifunctional or higher functional radical polymerizable monomer not having a charge transporting structure used for the surface layer is 250 or less. A photoreceptor according to any one of the above. The functional group of the radically polymerizable compound having a monofunctional charge transporting structure used for the surface layer is an acryloyloxy group and / or a methacryloyloxy group. Electrophotographic photoreceptor. 7. The electrophotographic photoreceptor according to claim 1, wherein the charge transport structure of the radical polymerizable compound having a monofunctional charge transport structure used for the surface layer is a triarylamine structure. . The electron according to any one of claims 1 to 7, wherein the radical polymerizable compound having a monofunctional charge transporting structure used in the surface layer is one or more of the following general formula (1) or (2). Photoconductor.

(Wherein R ₁ is 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 represents 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 Ali substituted or unsubstituted X may be the same or different, and X is 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, sulfur An atom and a vinylene group, Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, and an alkyleneoxycarbonyl group, m and n represent an integer of 0 to 3) 9. The electrophotographic photosensitive member according to claim 1, wherein the radically polymerizable compound having a monofunctional charge transporting structure used for the surface layer is one or more of the following general formula (3).

(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, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

Represents. ) The component ratio of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used for the surface layer is 30 to 70% by weight based on the total amount of the crosslinked surface layer. The electrophotographic photosensitive member according to any one of the above. 11. The component ratio of the radical polymerizable phenol compound or radical polymerizable hindered amine compound used for the surface layer is 0.1 to 10% by weight based on the total amount of the crosslinked surface layer. An electrophotographic photoreceptor according to any one of the above. 12. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a laminated structure of a charge generation layer, a charge transport layer, and a crosslinked surface layer from the support side. The electrophotographic photosensitive member according to claim 12, wherein the charge transport layer of the photosensitive layer contains a polymer charge transport material. 14. The electrophotographic photoreceptor according to claim 13, wherein the polymer charge transport material is a polycarbonate having a triarylamine structure in the main chain or side chain. An image forming method, wherein at least charging, image exposure, development, and transfer are repeated using the electrophotographic photosensitive member according to claim 1. An image forming apparatus comprising the electrophotographic photosensitive member according to claim 1. An electrophotographic photosensitive member according to any one of claims 1 to 14, and at least one means selected from the group consisting of a charging means, a developing means, a transfer means, a cleaning means and a charge eliminating means, A process cartridge for an image forming apparatus, wherein the process cartridge is removable from a main body of the forming apparatus.

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