JP2004302450A - Electrophotographic photoreceptor, image forming method using the same, image forming apparatus and process cartridge for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which has high wear resistance and good electrical properties, prevents local sticking of an external additive or paper powder on a photosensitive layer surface and suppresses image degradation particularly by disposing a photosensitive layer with a crosslinked surface layer whose surface is highly elastic and homogeneous, prevents plastic deformation of the photoreceptor in image formation, improves durability, and achieves upgraded image quality over a prolonged period of time. <P>SOLUTION: In the electrophotographic photoreceptor including at least a photosensitive layer on a conductive support, a surface layer of the photosensitive layer comprises a crosslinked layer formed by curing at least a tri- or higher functional radical-polymerizable monomer not having a charge transporting structure and a monofunctional radical-polymerizable compound having a charge transporting structure, an elastic displacement rate τe of the crosslinked surface layer is ≥35%, and a standard deviation of the elasticity variation rate τe is within 2%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention has high durability and high image quality over a long period of time by using a surface photosensitive layer having high abrasion resistance, uniform high elasticity, and good electrical characteristics. The present invention relates to an electrophotographic photosensitive member. In addition, the present invention relates to an image forming method, an image forming apparatus, and a process cartridge for an image forming apparatus using such a long-life, high-performance photoconductor.

2. Description of the Related Art In recent years, organic photoconductors (OPCs) have been widely used in copiers, facsimile machines, laser printers, and multifunction machines thereof in place of inorganic photoconductors due to good performance and various advantages. The reasons are, for example, (1) optical characteristics such as the width of the light absorption wavelength range and the amount of absorption, (2) electrical characteristics such as high sensitivity and stable charging characteristics, and (3) selection range of materials. , (4) ease of manufacture, (5) low cost, (6) non-toxicity, and the like.
In recent years, the diameter of the photoconductor has been reduced due to the miniaturization of the image forming apparatus, and the high speed of the machine and the maintenance-free operation have been added, so that the durability of the photoconductor has been desired. Organic photoreceptors are generally soft because the surface layer is mainly composed of a low-molecular charge transport material and an inert polymer.When used repeatedly in an electrophotographic process, they are subject to abrasion due to the mechanical load of a developing system and a cleaning system. It has the disadvantage that it is easy to occur. In addition, the demand for higher image quality has necessitated an increase in the rubber hardness of the cleaning blade and an increase in the contact pressure for the purpose of improving the cleaning property in accordance with the reduction in the size of the toner particles, which also promotes the wear of the photoconductor. It is a factor. Such abrasion of the photoreceptor deteriorates electrical characteristics such as deterioration of sensitivity and chargeability, and causes abnormal images such as image density reduction and background stain. In addition, scratches where abrasion occurs locally cause streak-like dirt images due to poor cleaning. At present, the life of the photoconductor is limited by the wear and scratches, and the photoconductor has been replaced.

The first issue for improving the durability of the photoconductor is to reduce the above-mentioned abrasion loss. Techniques for improving the abrasion resistance of the photosensitive layer include (1) a technique using a curable binder for the surface layer (for example, see Patent Document 1), and (2) a technique using a polymer type charge transport material ( For example, Patent Document 2) and (3) a material in which an inorganic filler is dispersed in a surface layer (for example, see Patent Document 3) are exemplified. Among these techniques, those using the curable binder (1) have poor compatibility with the charge transporting substance, and the residual potential increases due to impurities such as a polymerization initiator and unreacted residues, and the image density decreases. Tends to occur. In the case of using the polymer type charge transport material of (2), although the abrasion resistance can be improved to some extent, it is not enough to fully satisfy the durability required for the organic photoreceptor. Not reached. In addition, since the polymer-type charge transporting substance is difficult to polymerize and purify the material, it is difficult to obtain a high-purity material, so that electrical characteristics between the materials are difficult to stabilize. Further, there may be a problem in production such as a high viscosity of the coating liquid. (3) In the case where the inorganic filler is dispersed, the abrasion resistance is higher than that of a photoreceptor in which a normal low-molecular charge transporting substance is dispersed in an inert polymer. , The residual potential increases, 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 photoreceptor is large, cleaning failure occurs, which may cause toner filming and image deletion. According to the techniques (1), (2) and (3), the overall durability including the electrical durability and the mechanical durability required for the organic photoreceptor is sufficiently satisfied. Has not been reached.
Further, Patent Document 4 discloses a technique of a protective layer containing a conductive filler in order to improve the electrical characteristics of (1). Although the increase in the residual potential due to repeated use of this photoreceptor can be suppressed, the resistance of the protective layer is reduced, so that there is a tendency that a decrease in resolution or image deletion in a high humidity environment tends to occur.

  As a technique for abrasion resistance of the photosensitive layer instead of these, a charge transporting layer containing a monomer having a carbon-carbon double bond, a charge transporting material having a carbon-carbon double bond, and a binder resin is provided. (For example, see Patent Document 5). The binder resin has a carbon-carbon double bond and is reactive with the charge transport agent, and the binder resin has a double bond. And those having no reactivity. This photoreceptor has attracted attention because it has both abrasion resistance and good electrical properties.However, when a non-reactive binder resin is used, the binder resin, the monomer and the charge transport agent are used. Poor compatibility with the cured product generated by the reaction of the above, phase separation occurs in the crosslinked surface layer, and locally low abrasion resistance is formed, which is caused by scratches on the photoreceptor surface, toner external additives and paper dust May cause sticking. When the fixation further proceeds, toner filming is caused, and there is a possibility that white spots may occur in the image area due to non-uniformity of light transmission. In this case, in addition to the binder resin preventing the curing of the monomer, those specifically described as the monomer used in the photoreceptor are bifunctional, and the number of functional groups in the bifunctional monomer is As a result, a sufficient crosslink density was not obtained, and from these points, the abrasion resistance was not yet satisfactory. Further, even when a binder having reactivity is used, it is difficult to achieve both the bonding amount of the charge transporting substance and the crosslink density due to the low number of functional groups contained in the monomer and the binder resin, and the electrical characteristics Also, the wear resistance was not sufficient.

Further, 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). This photosensitive layer has a high hardness because the cross-linking density can be increased. Easy to be. For this reason, the restoring force against external stress is locally reduced, and cracks and flaws may be easily generated due to stress such as carrier adhesion during long-term repeated use.
Even a photoreceptor having a cross-linked photoconductive layer in which these charge transporting structures are chemically bonded cannot be said to have sufficient overall characteristics at present.

JP-A-56-48637 JP-A-64-1728 JP-A-4-281461 JP-A-2002-6526 Japanese Patent No. 3194392 JP-A-2000-66425

  An object of the present invention is to provide a photosensitive layer having high abrasion resistance and good electrical properties, and particularly, by providing a photosensitive layer having a highly elastic and homogeneous crosslinked surface layer on its surface, thereby providing a localized surface on the photosensitive layer. To prevent image deterioration by preventing external toner additives or paper powder from sticking, and to prevent plastic deformation of the photoconductor during image formation, further improve durability and improve image quality over a long period of time 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 such a long-life, high-performance photoreceptor.

  As a result of intensive studies, the present inventors have found that the surface layer of the photosensitive layer cures at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a monofunctional charge polymerizable compound having a monofunctional charge transport structure. It has been found that the above-mentioned object can be achieved by a cross-linked surface layer having an elastic displacement rate τe of 35% or more and a standard deviation of the elastic displacement rate τe of 2% or less. The present invention has been completed.

  That is, the above-mentioned problem is solved by (1) an electrophotographic photosensitive member having at least a photosensitive layer on a conductive support, wherein a surface layer of the photosensitive layer has at least a trifunctional or higher functional radical having no charge transporting structure. A crosslinked layer obtained by curing a polymerizable monomer and a radical polymerizable compound having a monofunctional charge transporting structure, wherein the crosslinked surface layer has an elastic displacement rate τe of 35% or more, and has a standard elastic displacement rate τe. An electrophotographic photosensitive member characterized in that the deviation is within 2% ”, (2)“ functionality of a trifunctional or higher functional radical polymerizable monomer having no charge transporting structure and contained in the coating liquid for the surface layer ”. The group is an acryloyloxy group and / or a methacryloyloxy group, wherein the electrophotographic photoreceptor according to the above item (1), (3) has a charge transporting structure used in the surface layer. And The electrophotography according to the above (1) or (2), wherein the ratio of the molecular weight to the number of functional groups (molecular weight / number of functional groups) in the radically polymerizable monomer having three or more functional groups is 250 or less. (4) wherein the functional group of the radical polymerizable compound having a monofunctional charge transporting structure used in the surface layer is an acryloyloxy group or a methacryloyloxy group. (5) The electrophotographic photoreceptor according to any one of (3) to (3), and (5) that the radical polymerizable compound having a monofunctional charge transporting structure used in the surface layer has a charge transport structure of tria. The electrophotographic photoreceptor according to any one of the above items (1) to (4), which has a reelamine structure ", (6)" monofunctional charge transportability used in the surface layer " Construction Radical polymerizable compound is a compound represented by the following general formula (1) or characterized in that said at least one (2) subsection (1), second (5) The electrophotographic photosensitive member according to any one of Items having;

（式中、Ｒ_１は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ_７（Ｒ_７は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ_８Ｒ_９（Ｒ_８及びＲ_９は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ_１、Ａｒ_２は置換もしくは未置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ_３、Ａｒ_４は置換もしくは未置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル２価基、アルキレンオキシカルボニル２価基を表わす。ｍ、ｎは０〜３の整数を表わす。）」、（７）「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を特徴とする前記第（１）項乃至第（６）項のいずれかに記載の電子写真感光体；

(Wherein, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group optionally having a substituent, an aralkyl group optionally having a substituent, an aryl group optionally having 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 be 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 good an aryl group, or a may) also being the same or different, Ar _1, Ar ₂ represents a substituted or unsubstituted arylene group, optionally .Ar ₃ be the same or different, Ar ₄ is substituted or Represents an unsubstituted aryl group, which may be the same or different, X is a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted divalent alkylene ether group or an alkyleneoxycarbonyl divalent group, and m and n are each an integer of 0 to 3. (7) "The radical polymerizable compound having a monofunctional charge transporting structure used in the surface layer is one or more of the following general formula (3). (1) The electrophotographic photosensitive member according to any one of (1) to (6);

（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、

(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 represent an alkyl group having 1 to 6 carbon atoms. And s and t represent an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

を表わす。）」、（８）「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第（１）項乃至第（７）項のいずれかに記載の電子写真感光体」、（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第（１）項乃至第（８）項のいずれかに記載の電子写真感光体」、（１０）「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第（１）項乃至第（９）項のいずれかに記載の電子写真感光体」、（１１）「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第（１０）項に記載の電子写真感光体」、（１２）「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第（１１）項に記載の電子写真感光体」、（１３）「前記表面層の硬化手段が加熱又は光エネルギー照射手段であることを特徴とする前記第（１）項乃至第（１２）項のいずれかに記載の電子写真感光体」によって解決される。

Represents )), (8) wherein the component ratio of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the surface layer is 30 to 70% by weight based on the total amount of the crosslinked surface layer. The electrophotographic photoreceptor according to any one of the above items (1) to (7) ", (9) a component of a radical polymerizable compound having a monofunctional charge transporting structure used in the surface layer. (10) The electrophotographic photoreceptor according to any one of (1) to (8), wherein the proportion 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 items (1) to (9), 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. (11) that the charge transport layer of the photosensitive layer contains a polymer charge transport material; (12), wherein the polymer charge transporting material is a polycarbonate having a triarylamine structure in a main chain or a side chain. (11) The electrophotographic photoreceptor according to the above (11), (13) wherein the curing means for the surface layer is heating or light energy irradiation means. 12) The electrophotographic photosensitive member according to any one of the above items).

  In addition, the above object is achieved by repeating at least charging, image exposure, development, and transfer using the electrophotographic photosensitive member according to any one of the above items (1) to (13). (15) An image forming apparatus having the electrophotographic photosensitive member according to any one of the above items (1) to (13). Is done.

  In addition, the above object is achieved by providing (16) the electrophotographic photosensitive member according to any one of the above items (1) to (13), a charging unit, a developing unit, a transfer unit, a cleaning unit, and The problem is solved by a process cartridge for an image forming apparatus, which has at least one means selected from the group consisting of static elimination means, and is detachable from the image forming apparatus main body.

  According to the present invention, by curing a tri- or more functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure to form a crosslinked surface layer of the photosensitive layer, A highly elastic and homogeneous crosslinked surface having good abrasion resistance and electrical properties to the photoreceptor, and having an elastic displacement rate τe of the crosslinked surface layer of 35% or more and a standard deviation of 2% or less. By providing a layer on the surface of the photosensitive layer, it is possible to prevent local external additives or paper dust from adhering to the surface of the photosensitive layer, thereby suppressing image deterioration, and also causing the carrier to adhere to the surface of the photosensitive member due to carrier adhesion and the like. It is possible to prevent the plastic deformation caused by the heat energy that accumulates as heat energy inside the developing part or the stress applied in the developing part and the cleaning part, and it is possible to further improve the durability. It was. Therefore, according to the present invention, a highly durable and high-performance photoconductor can be provided, and a high-performance and highly reliable image forming process and an image forming apparatus capable of outputting a good image for a long time by using this photoconductor. And a process cartridge for an image forming apparatus.

Hereinafter, the present invention will be described in detail.
In the present invention, the surface layer of the photosensitive layer comprises a crosslinked layer obtained by curing a radical polymerizable monomer having at least three functional groups having no charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure. When the elastic displacement rate τe of the surface layer is 35% or more and the standard deviation of the elastic displacement rate τe is within 2%, high durability and high image quality can be realized for a long period of time. An electrophotographic photoreceptor is achieved.
In the photoreceptor of the present invention, by using a radical polymerizable monomer having three or more functional groups in the surface layer, a three-dimensional network structure is developed, and a high hardness surface layer having a very high degree of cross-linking is obtained, and a high degree of resistance is obtained. Abrasion is achieved. On the other hand, when only a monofunctional or bifunctional radical polymerizable monomer is used, the cross-linking in the cross-linked surface layer becomes thin, and a drastic improvement in wear resistance cannot be achieved. When a polymer material is contained in the crosslinked surface layer, the development of the three-dimensional network structure is inhibited, the degree of crosslinking is reduced, and sufficient abrasion resistance cannot be obtained as compared with the present invention. Further, the compatibility between the polymer material contained and the cured product produced by the reaction of the radical polymerizable composition (radical polymerizable monomer or compound having a charge transporting structure) is poor, and local abrasion due to phase separation occurs. And appear as surface scratches. Further, the coating liquid of the crosslinked surface layer of the present invention contains a radically polymerizable compound having a monofunctional charge transporting structure, which is incorporated into the crosslink when the above-mentioned trifunctional or more functional radically polymerizable monomer is cured. . On the other hand, when a low-molecular charge transport material having no functional group is contained in the crosslinked surface layer, precipitation of the low-molecular charge transport material and clouding phenomenon occur due to the low compatibility, and the mechanical properties of the crosslinked surface layer are reduced. The target strength also decreases. When a bifunctional or more charge-transporting compound is used as the main component, the compound is fixed in the crosslinked structure by a plurality of bonds, but the charge transporting structure is extremely bulky, causing distortion in the cured resin and causing a crosslinked surface layer. Internal stress increases, and cracks and scratches frequently occur due to carrier adhesion and the like.

  Further, the photoreceptor of the present invention has good electrical characteristics, and therefore, high image quality can be realized for a long period of time. This is due to the fact that a radical polymerizable compound having a monofunctional charge transporting structure was used and immobilized in a pendant manner between crosslinks. As described above, the charge transporting substance having no functional group causes precipitation and white turbidity, resulting in remarkable deterioration in repeated use such as a decrease in sensitivity and an increase in residual potential. When a bifunctional or more functional charge transporting compound is used as a main component, the intermediate structure (cation radical) during charge transport cannot be stably maintained because the compound is fixed in a crosslinked structure by a plurality of bonds. The trap lowers the sensitivity and increases the residual potential. The deterioration of these electrical characteristics appears as an image such as a decrease in image density and thinning of characters.

  Further, in the photoreceptor of the present invention, when the elastic displacement rate τe of the crosslinked surface layer is 35% or more and the standard deviation of the elastic displacement rate τe is within 2%, the above-mentioned effect is sufficiently obtained. Be demonstrated. When the elasticity change rate τe is less than 35%, the stress applied in the developing section and the cleaning section is accumulated inside, for example, as heat energy, and causes plastic deformation. This plastic deformation appears as wear of the photoreceptor, and the durability is reduced. Further, when the standard deviation of the elastic displacement rate τe is larger than 2%, even if the entire surface layer has high elasticity and high abrasion resistance, the toner external additive or When the fat powder adheres and this phenomenon progresses further, toner filming occurs, causing white spots in the image area and uneven density due to uneven light transmittance.

（ただし、式中、Ｘ_１は、置換基を有していてもよいフェニレン基、ナフチレン基等のアリーレン基、置換基を有していてもよいアルケニレン基、−ＣＯ−基、−ＣＯＯ−基、−ＣＯＮ（Ｒ_１０）−基（Ｒ_１０は、水素、メチル基、エチル基等のアルキル基、ベンジル基、ナフチルメチル基、フェネチル基等のアラルキル基、フェニル基、ナフチル基等のアリール基を表す。）、または−Ｓ−基を表わす。）
これらの置換基を具体的に例示すると、ビニル基、スチリル基、２−メチル−１，３−ブタジエニル基、ビニルカルボニル基、アクリロイルオキシ基、アクリロイルアミノ基、ビニルチオエーテル基等が挙げられる。
（２）１，１−置換エチレン官能基としては、例えば以下の式で表わされる官能基が挙げられる。

（ただし、式中、Ｙは、置換基を有していてもよいアルキル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいフェニル基、ナフチル基等のアリール基、ハロゲン原子、シアノ基、ニトロ基、メトキシ基あるいはエトキシ基等のアルコキシ基、−ＣＯＯＲ_１１基（Ｒ_１１は、水素原子、置換基を有していてもよいメチル基、エチル基等のアルキル基、置換基を有していてもよいベンジル、フェネチル基等のアラルキル基、置換基を有していてもよいフェニル基、ナフチル基等のアリール基、または−ＣＯＮＲ_１２Ｒ_１３（Ｒ_１２およびＲ_１３は、水素原子、置換基を有していてもよいメチル基、エチル基等のアルキル基、置換基を有していてもよいベンジル基、ナフチルメチル基、あるいはフェネチル基等のアラルキル基、または置換基を有していてもよいフェニル基、ナフチル基等のアリール基を表わし、互いに同一または異なっていてもよい。）、また、Ｘ_２は上記式１０のＸ_１と同一の置換基及び単結合、アルキレン基を表わす。ただし、Ｙ，Ｘ_２の少なくとも何れか一方がオキシカルボニル基、シアノ基、アルケニレン基、及び芳香族環である。）
これらの置換基を具体的に例示すると、α−塩化アクリロイルオキシ基、メタクリロイルオキシ基、α−シアノエチレン基、α−シアノアクリロイルオキシ基、α−シアノフェニレン基、メタクリロイルアミノ基等が挙げられる。
なお、これらＸ_１，Ｘ_２、Ｙについての置換基にさらに置換される置換基としては、例えばハロゲン原子、ニトロ基、シアノ基、メチル基、エチル基等のアルキル基、メトキシ基、エトキシ基等のアルコキシ基、フェノキシ基等のアリールオキシ基、フェニル基、ナフチル基等のアリール基、ベンジル基、フェネチル基等のアラルキル基等が挙げられる。
これらのラジカル重合性官能基の中では、特にアクリロイルオキシ基、メタクリロイルオキシ基が有用であり、３個以上のアクリロイルオキシ基を有する化合物は、例えば水酸基がその分子中に３個以上ある化合物とアクリル酸（塩）、アクリル酸ハライド、アクリル酸エステルを用い、エステル反応あるいはエステル交換反応させることにより得ることができる。また、３個以上のメタクリロイルオキシ基を有する化合物も同様にして得ることができる。また、ラジカル重合性官能基を３個以上有する単量体中のラジカル重合性官能基は、同一でも異なっても良い。 Next, the constituent materials of the outermost layer coating liquid of the present invention will be described.
The trifunctional or higher-functional radically polymerizable monomer having no charge transporting property used in the present invention includes, for example, a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, etc. Refers to a monomer that does not have an electron transporting structure such as an electron-withdrawing aromatic ring having a nitro group or a nitro group, and has three or more radically polymerizable functional groups. The radical polymerizable functional group may be any group having a carbon-carbon double bond and capable of undergoing radical polymerization.
Examples of these radical polymerizable functional groups include the following 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups.
(1) Examples of the 1-substituted ethylene functional group include a functional group represented by the following formula.

(Wherein, X ₁ represents 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. A —CON (R ₁₀ ) — group (R ₁₀ represents a hydrogen, an alkyl group such as a methyl group or an ethyl group, an aralkyl group such as a benzyl group, a naphthylmethyl group, a phenethyl group, an aryl group such as a phenyl group or a naphthyl group). ) Or -S- group.)
Specific examples of these substituents include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamino group, and a vinylthioether group.
(2) Examples of the 1,1-substituted ethylene functional group include a functional group represented by the following formula.

(Where Y is an aryl 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, and a naphthyl group. Group, a halogen atom, an alkoxy group such as a cyano group, a nitro group, a methoxy group or an ethoxy group, a —COOR ₁₁ group (R ₁₁ is a hydrogen atom, a methyl group which may have a substituent, an alkyl group such as an ethyl group, etc. Group, aralkyl group such as benzyl and phenethyl group which may have a substituent, aryl group such as phenyl group and 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 Ara such phenethyl group, Kill group or substituent a phenyl group which may have a, an aryl group such as a naphthyl group, which may be the same or different from each other.) Further, X ₂ is the same as X ₁ in the formula 10 Represents a substituent, a single bond, or an alkylene group, provided that at least one of Y and X ₂ is an oxycarbonyl group, a cyano group, an alkenylene group, or an aromatic ring.
Specific examples of these substituents include an α-acryloyloxy group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.
Examples of the substituent further substituted by the substituents for X ₁ , X ₂ and Y include, for example, an alkyl group such as a halogen atom, a nitro group, a cyano group, a methyl group and an ethyl group, a methoxy group, an ethoxy group and the like. 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 these radically polymerizable functional groups, an acryloyloxy group and a methacryloyloxy group are particularly useful. A compound having three or more acryloyloxy groups is, for example, a compound having three or more hydroxyl groups in the molecule and an acrylic compound. It can be obtained by performing an ester reaction or a transesterification reaction using an acid (salt), an acrylic acid halide, or an acrylic ester. Further, a compound having three or more methacryloyloxy groups can be obtained in the same manner. 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, as the radical polymerizable monomer used in the present invention, for example, trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, trimethylolpropanealkylene-modified triacrylate, trimethylolpropaneethyleneoxy-modified (hereinafter EO-modified) ) Triacrylate, trimethylolpropane propyleneoxy-modified (hereinafter PO-modified) triacrylate, trimethylolpropanecaprolactone-modified triacrylate, trimethylolpropanealkylene-modified trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate Glycerol epichlorohydrin modified (hereinafter ECH modified) Acrylate, glycerol EO modified triacrylate, glycerol PO modified triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone modified hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkylated diacrylate Pentaerythritol pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, phosphoric acid EO-modified triacrylate, 2,2,5,5 , -Tetrahydroxymethylcyclopentanone tetraacrylate And the like, which can be used in combination either alone or in combination.

  The trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the present invention has a functional group ratio (molecular weight / number of functional groups) of 250 in order to form a dense crosslink in the crosslinked surface layer. The following is desirable. When the functional group ratio is greater than 250, the crosslinked surface layer is soft and the abrasion resistance is somewhat reduced. Therefore, among the monomers exemplified above, EO, PO, a monomer having a modifying group such as caprolactone is extremely long. It is not preferable to use a compound having a modifying group alone. Further, the component ratio of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in 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 trifunctional or higher functional radical polymerizable monomer in the solid content of the coating liquid. When the amount of the monomer component is less than 20% by weight, the three-dimensional cross-linking density of the cross-linked surface layer is low, and no remarkable improvement in abrasion resistance is achieved as compared with the case where a conventional thermoplastic binder resin is used. On the other hand, when the content exceeds 80% by weight, the content of the charge transporting compound decreases, and the electrical characteristics deteriorate. Since the required abrasion resistance and electrical characteristics vary depending on the process used, it cannot be unconditionally determined. However, considering the balance between the two characteristics, the range of 30 to 70% by weight is most preferable.

  The radical polymerizable compound having a monofunctional charge-transporting structure used in the present invention includes, for example, a hole-transporting structure such as triarylamine, hydrazone, pyrazoline, and carbazole, such as a condensed polycyclic quinone, diphenoquinone, and a cyano group. A compound having an electron transporting structure such as an electron-withdrawing aromatic ring having a nitro group and having one radically polymerizable functional group. Examples of the radical polymerizable functional group include the functional groups represented by the above formulas 10 and 11. More specifically, those described above for the radically polymerizable monomer are exemplified, and an acryloyloxy group and a methacryloyloxy group are particularly useful. As the charge transporting structure, a triarylamine structure has a high effect. In particular, when a compound represented by the following general formula (1) or (2) is used, the electrical characteristics such as sensitivity and residual potential are good. Is maintained.

（式中、Ｒ_１は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ_７（Ｒ_７は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ_８Ｒ_９（Ｒ_８及びＲ_９は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ_１、Ａｒ_２は置換もしくは未置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ_３、Ａｒ_４は置換もしくは未置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル２価基、アルキレンオキシカルボニル２価基を表わす。ｍ、ｎは０〜３の整数を表わす。）

(Wherein, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group optionally having a substituent, an aralkyl group optionally having a substituent, an aryl group optionally having 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 be 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 good an aryl group, or a may) also being the same or different, Ar _1, Ar ₂ represents a substituted or unsubstituted arylene group, optionally .Ar ₃ be the same or different, Ar ₄ is substituted or Represents an unsubstituted aryl group, which may be the same or different, X is a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted divalent alkylene ether group or an alkyleneoxycarbonyl divalent group, and m and n are each an integer of 0 to 3. Represents.)

Hereinafter, specific examples of the general formulas (1) and (2) are shown.
In the general formulas (1) and (2), in the substituent of R ₁ , an alkyl group includes, for example, a methyl group, an ethyl group, a propyl group, a butyl group and the like, and an aryl group includes a phenyl group, a naphthyl group and the like. , Aralkyl groups include benzyl group, phenethyl group, naphthylmethyl group, and alkoxy groups include methoxy group, ethoxy group, propoxy group, etc., and these include a halogen atom, a nitro group, a cyano group, and a methyl group. And an alkyl group such as ethyl group, an alkoxy group such as methoxy group and ethoxy group, an aryloxy group such as phenoxy group, an aryl group such as phenyl group and naphthyl group, and an aralkyl group such as benzyl group and phenethyl group. 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 a condensed polycyclic hydrocarbon group, a non-condensed cyclic hydrocarbon group, and a heterocyclic group.
As the condensed polycyclic hydrocarbon group, those having preferably 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptalenyl group, a biphenylenyl group, an as-indacenyl group , S-indacenyl group, fluorenyl group, acenaphthylenyl group, preyadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrenyl group, triphenylenyl group, pyrenyl group , A chrysenyl group, and a naphthacenyl group.

  Examples of the non-fused cyclic hydrocarbon group include a monovalent group of a monocyclic hydrocarbon compound such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether and diphenyl sulfone, or biphenyl, polyphenyl, diphenyl alkane, diphenyl alkene, diphenyl alkyne, Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane, and polyphenylalkene, or ring assembly such as 9,9-diphenylfluorene Examples include a monovalent group of a hydrocarbon compound.

Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.
The aryl groups represented by Ar ₃ and Ar ₄ may have, for example, the following substituents.
(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 include a fluorine atom A hydroxyl group, a cyano group, a C ₁ -C ₄ alkoxy group, a phenyl group or a halogen atom, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxy group substituted phenyl group. Good. Specifically, methyl, ethyl, n-butyl, i-propyl, t-butyl, s-butyl, n-propyl, trifluoromethyl, 2-hydroxyethyl, 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 ), wherein R ₂ represents an 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) An alkylmercapto group or an arylmercapto group, specifically, a methylthio group, an ethylthio group, a phenylthio group, a p-methylphenylthio group and the like.
(6)

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

(Wherein R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group or an aryl group as defined in the above (2). Examples of the aryl group include a phenyl group, a biphenyl group and a naphthyl group, These may contain a C _{1 to} C ₄ alkoxy group, a C _{1 to} C ₄ alkyl group or a halogen atom as a substituent. R ₃ and R ₄ may form a ring together.
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 a pyrrolidino group.
(7) An alkylenedioxy group or an alkylenedithio group such as a methylenedioxy group or a methylenedithio group.
(8) Substituted or unsubstituted styryl groups, substituted or unsubstituted β-phenylstyryl groups, diphenylaminophenyl groups, ditolylaminophenyl groups 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. However, when m is 0, X is preferably not a single bond.
Examples of the substituted or unsubstituted alkylene group include C _{1 to} C ₁₂ , preferably C _{1 to} C ₈ , more preferably C _{1 to} C ₄ linear or branched alkylene groups. Further, it has a phenyl group substituted by a fluorine atom, a hydroxyl group, a cyano group, a C _{1 to} C ₄ alkoxy group, a phenyl group or a halogen atom, a C _{1 to} C ₄ alkyl group or a C _{1 to} C ₄ alkoxy group. May be. Specifically, methylene, ethylene, n-butylene, i-propylene, t-butylene, s-butylene, n-propylene, trifluoromethylene, 2-hydroxyethylene, 2-ethoxyethylene Groups, 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, a C _{1 to} C ₄ It may have an alkoxy group. Specific examples include a cyclohexylidene group, a cyclohexylene group and a 3,3-dimethylcyclohexylidene group.
Examples of the substituted or unsubstituted alkylene ether group include ethyleneoxy, propyleneoxy, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, and tripropylene glycol, and the alkylene ether group alkylene group is a hydroxyl group, a methyl group, an ethyl group, or the like. May have a substituent.
The vinylene group is

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

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

Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether divalent group, or an alkyleneoxycarbonyl divalent group.
Examples of the substituted or unsubstituted alkylene group include those similar to the aforementioned alkylene group for X.
Examples of the substituted or unsubstituted divalent alkylene ether group include the divalent groups of the alkylene ether group represented by X.
Examples of the alkyleneoxycarbonyl divalent group include a caprolactone-modified divalent group.

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

（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、

(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 represent an alkyl group having 1 to 6 carbon atoms. And s and t represent 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。
本発明で用いる上記一般式（１）及び（２）特に（３）の１官能性の電荷輸送構造を有するラジカル重合性化合物は、炭素−炭素間の二重結合が両側に開放されて重合するため、末端構造とはならず、連鎖重合体中に組み込まれ、３官能以上のラジカル重合性モノマーとの重合で架橋形成された重合体中では、高分子の主鎖中に存在し、かつ主鎖−主鎖間の架橋鎖中に存在（この架橋鎖には１つの高分子と他の高分子間の分子間架橋鎖と、１つの高分子内で折り畳まれた状態の主鎖のある部位と主鎖中でこれから離れた位置に重合したモノマー由来の他の部位とが架橋される分子内架橋鎖とがある）するが、主鎖中に存在する場合であってもまた架橋鎖中に存在する場合であっても、鎖部分から懸下するトリアリールアミン構造は、窒素原子から放射状方向に配置する少なくとも３つのアリール基を有し、バルキーであるが、鎖部分に直接結合しておらず鎖部分からカルボニル基等を介して懸下しているため立体的位置取りに融通性ある状態で固定されているので、これらトリアリールアミン構造は重合体中で相互に程よく隣接する空間配置が可能であるため、分子内の構造的歪みが少なく、また、電子写真感光体の表面層とされた場合に、電荷輸送経路の断絶を比較的免れた分子内構造を採りうるものと推測される。
本発明の１官能の電荷輸送性構造を有するラジカル重合性化合物の具体例を以下に示すが、これらの構造の化合物に限定されるものではない。

Represents )
As the compound represented by the above general formula, a compound having a methyl group or an ethyl group as a substituent of Rb or Rc is particularly preferable.
The radical polymerizable compound having a monofunctional charge transport structure of the above general formulas (1) and (2), particularly (3), used in the present invention, is polymerized by opening a carbon-carbon double bond on both sides. Therefore, in a polymer which is not formed into a terminal structure but is incorporated into a chain polymer and cross-linked by polymerization with a tri- or more functional radical polymerizable monomer, it is present in the main chain of the polymer and In the cross-linking chain between the chain and the main chain (the cross-linking chain includes an intermolecular cross-linking chain between one polymer and another polymer, and a site where the main chain is folded in one polymer) And there is an intramolecular cross-linked chain at a position distant from the main chain derived from the polymerized monomer), but even if it is present in the main chain, Even when present, the triarylamine structure hanging from the chain portion is a nitrogen atom Has at least three aryl groups arranged radially from it, and is bulky, but is not directly bonded to the chain part but is suspended from the chain part via a carbonyl group etc., so it can accommodate three-dimensional positioning Since these triarylamine structures are fixed in a neutral state, the spatial arrangement of these triarylamine structures in the polymer can be appropriately adjacent to each other, so that there is little structural distortion in the molecule, and the surface of the electrophotographic photosensitive member It is presumed that, when a layer is formed, it is possible to adopt an intramolecular structure which is relatively free from interruption of the charge transport pathway.
Specific examples of the radical polymerizable compound having a monofunctional charge transporting structure of the present invention are shown below, but the invention is not limited to compounds having these structures.

  Further, the radical polymerizable compound having a monofunctional charge transporting structure used in the present invention is important for imparting charge transporting performance of the crosslinked surface layer, and this component is 20 to 80% by weight based on the total weight of the crosslinked surface layer. %, Preferably 30 to 70% by weight. If this component is less than 20% by weight, the charge transporting performance of the crosslinked surface layer cannot be sufficiently maintained, and deterioration in electrical characteristics such as a decrease in sensitivity and an increase in residual potential will be caused by repeated use. On the other hand, when the content exceeds 80% by weight, the content of the trifunctional monomer having no charge transport structure is reduced, and the crosslink density is reduced, so that high abrasion resistance is not exhibited. The required electrical characteristics and abrasion resistance vary depending on the process to be used, so it cannot be said unconditionally. However, considering the balance between the two characteristics, the range of 30 to 70% by weight is most preferable.

The surface layer of the present invention is obtained by curing a radical polymerizable monomer having at least three functional groups having no charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure. Monofunctional and bifunctional radically polymerizable monomers and oligomers can be used in combination for the purpose of adjusting the viscosity at the time, relaxing the stress of the crosslinked surface layer, lowering the surface energy and reducing the 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, 6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A-EO modified diacrylate, bisphenol F-EO modified diacrylate, neopentyl glycol diacrylate, and the like.
Examples of the functional monomer include those substituted with a fluorine atom such as octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, and 2-perfluoroisononylethyl acrylate. No. 60503, JP-B-6-45770, siloxane repeating unit: 20 to 70 acryloylpolydimethylsiloxaneethyl, methacryloylpolydimethylsiloxaneethyl, acryloylpolydimethylsiloxanepropyl, acryloylpolydimethylsiloxanebutyl, diacryloylpolydimethylsiloxane Examples include vinyl monomers having a polysiloxane group such as diethyl, acrylate and methacrylate.
Examples of the radical polymerizable oligomer include epoxy acrylate-based, urethane acrylate-based, and polyester acrylate-based oligomers. However, when a large amount of a monofunctional or bifunctional radical polymerizable monomer or radical polymerizable oligomer is contained, the three-dimensional cross-linking density of the cross-linked surface layer is substantially reduced, resulting in a reduction in abrasion 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 based on 100 parts by weight of the trifunctional or more functional radical polymerizable monomer.
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 monofunctional charge polymerizable compound having a monofunctional charge transport structure. A polymerization initiator may be used to make the reaction proceed efficiently.

  Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, and 2,5-dimethyl-2,5-di ( Peroxybenzoyl) hexine-3, di-t-butyl peroxide, peroxide initiators such as t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, azobisisobutylnitrile, azobiscyclohexanecarbonitrile Azo initiators such as azobisisobutyrate, azobisisobutylamidine hydrochloride, and 4,4'-azobis-4-cyanovaleric acid.

Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 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 isobutylate Benzoin ether-based photopolymerization initiators such as benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoyl benzoate, 2-benzoyl naphthalene, 4-benzoyl biphenyl, 4-benzoyl phenyl ether, acrylated benzophenone, Benzophenone-based photopolymerization initiators such as 1,4-benzoylbenzene, and thioxanthones such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone Ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyl Phenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10 -Phenanthrene, acridine compounds, triazine compounds, imidazole compounds. Further, those having a photopolymerization accelerating effect can be used alone or in combination with the above photopolymerization initiator. For example, triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone and the like can be mentioned.
These polymerization initiators may be used alone or as a mixture of two or more. The content of the polymerization initiator is 0.5 to 40 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the total content having radical polymerizability.

  Further, the coating liquid of the present invention may contain additives such as various plasticizers (for the purpose of relaxing stress and improving adhesion), a leveling agent, and a low-molecular-weight charge-transporting substance having no radical reactivity, if necessary. Known additives can be used as these additives, and as plasticizers, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used. 20% by weight or less, preferably 10% or less. As the leveling agent, silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain can be used. 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 monofunctional radical polymerizable compound having a charge transport structure. Is done. When the radical polymerizable monomer is a liquid, such a coating liquid can be applied by dissolving other components in the liquid. However, if necessary, the liquid is diluted with a solvent and applied. As the solvent used at this time, 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, propyl ether Ethers, such as dichloromethane, dichloroethane, trichloroethane, and chlorobenzene; aromatics, such as benzene, toluene, and xylene; and cellosolves, such as methyl cellosolve, ethyl cellosolve, and cellosolve acetate. These solvents may be used alone or in combination of two or more. The dilution ratio with the solvent varies depending on the solubility of the composition, the coating method, and the intended film thickness, and is arbitrary. The coating can be performed by a dip coating method, a spray coat, a bead coat, a ring coat method, or the like.

In the present invention, after the application of the coating solution, energy is applied from the outside to cure the coating solution to form a crosslinked surface layer. The external energy used at this time includes heat, light, and radiation. As a method of applying heat energy, heating is performed from the coating surface side or the support side using a gas such as air or nitrogen, steam, or various heat media, infrared rays, or electromagnetic waves. The heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower. If the heating temperature is lower than 100 ° C., the reaction rate is low and the reaction is not completely completed. If the temperature is higher than 170 ° C., the reaction proceeds non-uniformly, and large distortion occurs in the crosslinked surface layer. In order to promote the curing reaction uniformly, it is also effective to heat at a relatively low temperature of less than 100 ° C. and then further heat it to 100 ° C. or more to complete the reaction. As the light energy, a UV irradiation light source such as a high-pressure mercury lamp or a metal halide lamp having an emission wavelength of mainly ultraviolet light can be used. It 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 uneven, and the crosslinked surface layer becomes rough. As the energy of the radiation, one using an electron beam can be used. Among these energies, those using heat and light energies are useful because of the ease of controlling the reaction rate and the simplicity of the apparatus.

Since the 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 is described below together with the layer structure.
The present invention is further characterized in that the elastic displacement rate τe of the crosslinked surface layer is 35% or more, and the standard deviation of the elastic displacement rate τe is within 2%.
The elastic displacement rate τe of the present invention is measured by a load-unloading test of a micro surface hardness tester using a diamond indenter. As shown in FIG. 1, the indenter is pushed in at a constant load speed from the point (a) where the indenter comes into contact with the sample (loading process). The indenter is raised at the unloading speed (unloading process), and a point at which the load is finally applied to the indenter is defined as a plastic displacement (c). At this time, the curve of the obtained indentation depth and load is recorded as shown in FIG. 2, and the maximum displacement (b) and the plastic displacement (c) elastic displacement rate τe are calculated by the following equations.

かかる弾性変位率測定は、一定温湿度下で行われ、本発明で弾性変位率とは、温度２２℃、相対湿度５５％の環境条件下で行なわれた上記試験の測定値を示す。
本発明では、ダイナミック微小表面硬度計ＤＵＨ−２０１（島津製作所製）、三角すい圧子（１１５゜）を用いているが、これと同等の性能を有するいかなる装置で測定された値でもよい。弾性変位率τｅの標準偏差はサンプル上の任意の１０箇所について弾性変位率τｅを測定し、この１０個の値より算出した。測定においては本発明の架橋表面層を有する感光体をアルミニウムシリンダー上に作製し、これを適宜切断して用いた。弾性変位率τｅは基板のバネ特性の影響を受けるため、基板としては剛直な金属版、スライドガラスなどが適当である。更に、架橋表面層の下層（例えば、電荷輸送層、電荷発生層など）の硬度や弾性の要素も影響するため、これらの影響を減らすように最大変位が架橋表面層膜厚の１／１０になるように規定加重を調整した。架橋表面層のみを単独で基板上に作製すると、下層成分の混入、下層との接着性が変わり、必ずしも感光体の表面架橋層を正確に再現できないため、好ましくない。
先に述べたように、架橋表面層の弾性変化率τｅが３５％未満では耐摩耗性が低く、その標準偏差が２％より大きいと、架橋表面層の局部的に弱い部分に、トナー外添剤や紙粉が固着しトナーフィルミングの原因となることが見出された。本発明の架橋表面層における弾性変位率とその標準偏差は、様々な条件が相互に関係しているため、一定の弾性変位率を得るための方向性は一様でないが、（１）架橋表面層用塗工液に含有される組成物、それらの含有割合、（２）塗工液の希釈溶媒、固形分濃度、（３）塗工方法、（４）硬化手段、条件、（５）下層の溶解性、などによって影響を受けることがわかっている。

The measurement of the elastic displacement rate is performed at a constant temperature and humidity. In the present invention, the elastic displacement rate indicates a measured value of the above-mentioned test performed under an environmental condition of a temperature of 22 ° C. and a relative humidity of 55%.
In the present invention, a dynamic micro surface hardness meter DUH-201 (manufactured by Shimadzu Corporation) and a triangular indenter (115 °) are used. The standard deviation of the elastic displacement rate τe was calculated from the measured values of the elastic displacement rates τe at arbitrary 10 points on the sample. In the measurement, a photoreceptor having the crosslinked surface layer of the present invention was prepared on an aluminum cylinder, and this was appropriately cut and used. Since the elastic displacement rate τe is affected by the spring characteristics of the substrate, a rigid metal plate, a slide glass, or the like is appropriate as the substrate. Furthermore, since the hardness and elasticity of the lower layer of the crosslinked surface layer (for example, the charge transport layer, the charge generation layer, etc.) are also affected, the maximum displacement is reduced to 1/10 of the thickness of the crosslinked surface layer so as to reduce these effects. The specified weight was adjusted to be as follows. If only the crosslinked surface layer is formed on the substrate alone, the mixing of the lower layer components and the adhesion to the lower layer change, and the surface crosslinked layer of the photoreceptor cannot always be reproduced accurately, which is not preferable.
As described above, when the elastic change rate τe of the crosslinked surface layer is less than 35%, the abrasion resistance is low, and when the standard deviation is more than 2%, the toner externally added to the locally weak portion of the crosslinked surface layer. It has been found that the agent and paper powder adhere and cause toner filming. The elastic displacement rate and its standard deviation in the crosslinked surface layer of the present invention are not uniform in the direction for obtaining a constant elastic displacement rate because various conditions are related to each other. Compositions contained in coating liquid for layer, their content ratio, (2) diluting solvent of coating liquid, solid content concentration, (3) coating method, (4) curing means, conditions, (5) lower layer Is known to be affected by the solubility of

  The composition contained in the surface layer coating solution may contain a radical polymerizable compound having a charge transporting structure of two or more functionalities or a binder resin, and may also provide smoothness, electrical properties, or durability of the photoreceptor surface. Is possible as long as it does not impair. However, when a radical polymerizable compound having a bifunctional or more charge-transporting structure is contained, the crosslink density can be increased, so that the elastic displacement rate τe has a relatively large value. Since they are entangled by bonding, the crosslinked surface layer is distorted and the curing reaction becomes non-uniform. Therefore, the restoring force against the external stress locally decreases, and the standard deviation of the elastic displacement rate τe increases. In addition, when a polymer material such as a binder resin is contained in the coating liquid, the polymer is formed from a curing reaction of a radical polymerizable composition (a compound having a trifunctional or higher functional radical polymerizable monomer and a monofunctional charge transporting structure). Phase separation occurs due to poor compatibility with the polymer, and similarly, the standard deviation of the elastic displacement rate τe increases. Further, when such a polymer material is contained in a large amount, the curing reaction is reduced and the cross-linking density is reduced, so that the value of the elastic displacement rate τe does not reach 35%. Therefore, it is preferable not to use a radical polymerizable compound having a bifunctional or higher charge transport structure or a binder resin.

  Regarding the diluting solvent for the coating liquid, if a large amount of solvent that easily dissolves the lower layer is used, the composition such as the resin binder and the low-molecular charge transport material in the lower layer will be mixed into the outermost surface layer and will only hinder the curing reaction. Instead, the state becomes the same as when a large amount of the non-cured material is previously contained in the coating liquid, and uneven curing of the crosslinked surface occurs. Conversely, if a solvent that does not dissolve the lower layer at all is used, the adhesiveness between the crosslinked surface layer and the lower layer will decrease, and crater-like repelling will appear on the crosslinked surface layer due to volume shrinkage during the curing reaction, and the lower layer will have a low elastic displacement rate. Is partially exposed. These measures include controlling the solubility of the lower layer by using a mixed solvent, reducing the amount of solvent contained in the coating surface layer by the liquid composition and coating method, and using a polymer charge transport material for the lower layer to lower the layer. Examples of such a method include suppressing the incorporation of components, and providing an intermediate layer having low solubility or an intermediate layer having good adhesiveness between the lower layer and the crosslinked surface layer.

  In the crosslinked surface layer of the present invention, it is necessary to include a bulky charge transporting structure in order to maintain electrical characteristics and to increase the crosslink density in order to increase strength. In such hardening after application of the surface layer, if a very high energy is applied from the outside and the reaction proceeds rapidly, the hardening proceeds unevenly and the standard deviation of the elastic displacement rate τe increases. For this reason, it is preferable to use heat or external energy of light that can control the reaction rate by heating conditions, light irradiation intensity, and the amount of polymerization initiator.

In the present invention, a specific method for obtaining a crosslinked surface layer having an elastic displacement rate τe of 35% or more and a standard deviation of 2% or less is exemplified. For example, an acrylate monomer having three acryloyloxy groups may be used as a coating liquid. When using a triarylamine compound having one acryloyloxy group, in addition to the acrylate compound, a polymerization initiator is added in an amount of 3 to 10% by weight based on the total amount of the acrylate compound, and a solvent is added to prepare a coating solution. . For example, in a charge transport layer that is a lower layer of a crosslinked surface layer, a triarylamine donor as a charge transport material, and polycarbonate as a binder resin are used, and when a surface layer is formed by spray coating, As the solvent, tetrahydrofuran, 2-butanone, ethyl acetate and the like are preferable, and the use ratio thereof is 2 to 8 times the total amount of the acrylate compound.
Next, for example, the above-prepared coating solution is applied by spraying or the like onto a photoconductor in which an undercoat layer, a charge generation layer, and the above-described 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. for 1 to 10 minutes), and cured by UV irradiation or heating.
For UV irradiation, uses a metal halide lamp, illuminance 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, for example, the case of irradiation with UV light of 500 mW / cm ^2, uniform illumination about 20 seconds from multiple directions do it. At this time, the drum temperature is controlled so as not to exceed 50 ° C.
In the case of heat curing, the heating temperature is preferably 100 to 170 ° C. For example, when a heating oven is used and the heating temperature is set to 150 ° C, the heating time is 20 minutes to 3 hours.
After completion of the curing, the photosensitive member of the present invention is obtained by heating at 100 to 150 ° C. for 10 to 30 minutes to reduce the residual solvent.

Hereinafter, the present invention will be described according to its layer structure.
<About the layer structure of the electrophotographic photosensitive member>
The electrophotographic photosensitive member used in the present invention will be described with reference to the drawings.
FIG. 3 is a cross-sectional view showing the electrophotographic photoreceptor of the present invention, and has a single-layer structure in which a photosensitive layer (33) having both a charge generation function and a charge transport function is provided on a conductive support (31). Photoreceptor. FIG. 3-A shows the case where the crosslinked surface layer is the entire photosensitive layer, and FIG. 3-B shows the case where the crosslinked surface layer is the surface portion of the photosensitive layer.
FIG. 4 shows a photoconductor having a laminated structure in which a charge generation layer (35) having a charge generation function and a charge transport layer (37) having a charge transport function are stacked on a conductive support (31). is there. FIG. 4-A shows the case where the crosslinked surface layer is the entire charge transport layer, and FIG. 4-B shows the case where the crosslinked surface layer is the surface portion of the charge transport layer.

<About conductive support>
As the conductive support (31), those exhibiting conductivity of not more than 10 ¹⁰ Ω · cm, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, oxide Metal oxides such as indium or the like coated by film or cylindrical plastic or paper by vapor deposition or sputtering, or plates made of aluminum, aluminum alloy, nickel, stainless steel, etc. After the formation, a tube or the like that has been subjected to surface treatment such as cutting, superfinishing, and polishing can be used. Further, an endless nickel belt and an endless stainless belt disclosed in JP-A-52-36016 can also be used as the conductive support (31).
In addition, those obtained by dispersing a conductive powder in a suitable binder resin on the above support and applying the same can also be used as the conductive support (31) of the present invention.

  Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, and metal oxide powder such as conductive tin oxide and ITO. No. The binder resins used simultaneously include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, and 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, Thermoplastic, thermosetting resin or photocurable resin such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing the conductive powder and the binder resin in an appropriate solvent, for example, tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene, or the like, and applying the dispersion.

  Further, a heat-shrinkable tube containing the above-mentioned conductive powder in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chloride rubber, and polytetrafluoroethylene-based fluororesin on a suitable cylindrical substrate. A conductive layer provided with a conductive layer can also be favorably used as the conductive support (31) of the present invention.

<About photosensitive layer>
Next, the photosensitive layer will be described. The photosensitive layer may have a laminated structure or a single-layer structure.
In the case of a laminated structure, 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. In the case of a single-layer structure, the photosensitive layer is a layer having both a charge generation function and a charge transport function.
Hereinafter, each of the photosensitive layer having the laminated structure and the photosensitive layer having the single-layer structure will be described.

<The photosensitive layer is composed of a charge generation layer and a charge transport layer>
(Charge generation layer)
The charge generation layer (35) is a layer containing a charge generation material having a charge generation function as a main component, and may optionally use a binder resin in combination. As the charge generation substance, an inorganic material and an organic material can be used.
Examples of the inorganic material include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, and amorphous silicon. As amorphous silicon, a material in which a dangling bond is terminated with a hydrogen atom or a halogen atom, or a material in which a boron atom, a phosphorus atom, or the like is doped, is suitably used.
On the other hand, as the organic material, a known material can be used. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulhenium salt pigment, methine squaric acid pigment, azo pigment having a carbazole skeleton, azo pigment having a triphenylamine skeleton, azo pigment having a diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyryl carbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinone imine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generating substances can be used alone or as a mixture of two or more kinds.

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

Specific examples of the former include JP-A-01-001728, JP-A-01-00964, JP-A-01-013061, JP-A-01-019049, JP-A-01-241559, JP-A-04-011627, JP-A-04-175337, JP-A-04-183719, JP-A-04-225014, JP-A-04-230767, JP-A-04-320420, JP-A-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 JP, JP-A-06-234841, JP-A-06-239049, JP-A-06-236050, JP-A-06-236051, JP-A-06-295077, JP-A-07-056374, JP-A-08-176293, JP-A-08-208820, JP-A-08-208 -21640, JP-A-08-253568, JP-A-08-269183, JP-A-09-062019, JP-A-09-043883, JP-A-09-71642, JP-A-09-87376 JP-A-09-104746, JP-A-09-110974, JP-A-09-110977, JP-A-09-157378, JP-A-09-221544, and JP-A-09-227669. JP-A-09-235367 and JP-A-09-241369. The charge-transporting polymer materials described in JP-A-09-268226, JP-A-09-272735, JP-A-09-302084, JP-A-09-300285, JP-A-09-328439 and the like are used. No.
Further, specific examples of the latter include, for example, polysilylene polymers described in JP-A-63-285552, JP-A-05-19497, JP-A-05-70595, JP-A-10-73944 and the like. Illustrated.

The charge generation layer (35) may contain a low-molecular charge transport material.
The low-molecular charge transporting material that can be used in combination with the charge generating layer (35) includes a hole transporting material and an electron transporting material.
Examples of the electron transporting substance include chloranil, bromanil, 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-trione Electron accepting substances such as nitrodibenzothiophene-5,5-dioxide, diphenoquinone derivatives and the like can be mentioned. These electron transport materials can be used alone or as a mixture of two or more.

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

As a method for forming the charge generation layer (35), a vacuum thin film preparation method and a casting method from a solution dispersion system are mainly mentioned.
As the former method, a vacuum evaporation 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-mentioned inorganic material and organic material can be favorably formed.
In addition, in order to provide a charge generation layer by a casting method described below, if necessary, the above-mentioned inorganic or organic charge generation material is used together with a binder resin together with tetrahydrofuran, dioxane, dioxolan, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclohexanone, or the like. It can be formed by dispersing using a solvent such as pentanone, anisole, xylene, methyl ethyl ketone, acetone, ethyl acetate, and butyl acetate by a ball mill, an attritor, a sand mill, a bead mill, or the like, appropriately diluting the dispersion, and coating. . If necessary, a leveling agent such as dimethyl silicone oil and methyl phenyl silicone oil can be added. The coating can be performed by a dip coating method, a spray coat, a bead coat, a ring coat method, or the like.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, and 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 the charge transport structure of the present invention is usefully used as a charge transport layer. When the crosslinked surface layer is the whole of the charge transport layer (37), the radical polymerizable composition of the present invention (the charge transportable structure is formed on the charge generation layer (35)) as described in the above-mentioned method for preparing the crosslinked surface layer. A coating solution containing a radical polymerizable monomer having no and a radical polymerizable compound having a monofunctional charge transporting structure; the same applies hereinafter), drying if necessary, starting a curing reaction by external energy, and crosslinking A surface layer is formed. At this time, the thickness of the crosslinked surface layer is 10 to 30 μm, preferably 10 to 25 μm. When the thickness is less than 10 μm, a sufficient charging potential cannot be maintained, and when the thickness is more than 30 μm, peeling from the lower layer tends to occur due to volume shrinkage during curing.
When the crosslinked surface layer is formed on the surface of the charge transport layer (37) and the charge transport layer (37) has a laminated structure, the lower layer 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 an appropriate solvent, and the resin is coated on the charge generation layer (35) and dried to form a coating liquid. The coating liquid containing the radically polymerizable composition of the present invention is coated thereon. Then, it is cross-linked and hardened by external energy.
As the charge transporting material, the electron transporting material, the hole transporting material, and the polymer charge transporting 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 at the time of coating the surface layer, 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 a thermoplastic or thermosetting resin such as phenolic resin and alkyd resin.
The amount of the charge transporting material is suitably 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 used in the charge generation layer can be used, but a solvent which 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. In addition, a coating method similar to that of the charge generation layer (35) can be used to form the lower layer portion of the charge transport layer.

If necessary, a plasticizer and a leveling agent may be added.
As the 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.
Examples of the leveling agent that can be used in combination with the lower layer of the charge transport layer include silicone oils such as dimethyl silicone oil and methyl phenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in a side chain. About 0 to 1 part by weight is appropriate for 100 parts by weight of the binder resin.
The thickness of the lower portion of the charge transport layer is suitably about 5 to 40 μm, and preferably about 10 to 30 μm.

  When the crosslinked 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 above-mentioned method for preparing the crosslinked surface layer. After applying the coating liquid and drying if necessary, a curing reaction is started by external energy such as heat or light to form a crosslinked surface layer. At this time, the 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 unevenness of the film thickness. If the thickness is more than 20 μm, the overall thickness of the charge transport layer is increased, and the reproducibility of the image is reduced due to the diffusion of the charge.

<Single-layer photosensitive layer>
The photosensitive layer having a single-layer structure is a layer having both a charge generating function and a charge transporting function, and the crosslinked surface layer having the charge transporting structure of the present invention has a single layer structure by containing a charge generating substance having a charge generating function. Useful as a photosensitive layer. As described in the above method for forming a charge generating layer by casting, the charge generating substance is dispersed together with the coating liquid containing the radical polymerizable composition, applied on the charge generating layer (35), and dried as necessary. The curing reaction is started by external energy, and a crosslinked surface layer is formed. Note that a liquid in which the charge generating substance is dispersed in advance with a solvent may be added to the coating liquid for the present crosslinked surface layer. At this time, the thickness of the crosslinked surface layer is 10 to 30 μm, preferably 10 to 25 μm. When the thickness is less than 10 μm, a sufficient charging potential cannot be maintained, and when the thickness is more than 30 μm, peeling from the conductive substrate or the undercoat layer easily occurs due to volume shrinkage during curing.

  When the crosslinked surface layer is the surface portion of the photosensitive layer having a single-layer structure, the lower layer portion of the photosensitive layer is formed by using a charge generating substance having a charge generating function, a charge transporting substance having a charge transporting function, and a binder resin in an appropriate solvent. Can be formed by dissolving or dispersing in water, coating and drying. If necessary, a plasticizer, a leveling agent, and the like can be added. As the method of dispersing the charge generating substance, the charge generating substance, the charge transporting substance, the plasticizer and the leveling agent can be the same as those already described for the charge generating layer (35) and the charge transporting layer (37). As the binder resin, in addition to the binder resin described in the section of the charge transport layer (37), the binder resin described in the charge generation layer (35) may be mixed and used. In addition, the above-described polymer charge transport materials can also be used, and are useful in that the incorporation of the lower photosensitive layer composition into the crosslinked surface layer can be reduced. The thickness of the lower part of the photosensitive layer is suitably about 5 to 30 μm, and preferably about 10 to 25 μm.

  When the crosslinked surface layer is a surface portion of a photosensitive layer having a single-layer structure, a coating solution containing the radical polymerizable composition of the present invention and a charge generating substance is applied to a lower layer portion of the photosensitive layer as described above. After drying, if necessary, it is cured by external energy such as heat or light to form a crosslinked surface layer. At this time, the 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 unevenness of the film thickness causes variations in durability.

  The amount of the charge generating substance 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 amount of the binder resin contained in the lower layer of the photosensitive layer is 20 to 80% by weight based on the total amount. 10 to 70 parts by weight of the transport substance is preferably used.

<About the middle layer>
In the photoreceptor of the present invention, when the crosslinked surface layer is the surface portion of the photosensitive layer, an intermediate layer may be provided for the purpose of suppressing the incorporation of the lower layer component into the crosslinked surface layer or improving the adhesiveness with the lower layer. It is possible.
The intermediate layer generally uses a binder resin 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 coating method generally used as described above is employed. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

<About the undercoat layer>
In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support (31) and the photosensitive layer. The undercoat layer generally contains a resin as a main component. However, considering that the photosensitive layer is coated thereon with a solvent, these resins may be resins having high solvent resistance to general organic solvents. desirable. Examples of such a resin include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, copolymer-soluble nylons, alcohol-soluble resins such as methoxymethylated nylon, polyurethane, melamine resins, phenol resins, alkyd-melamine resins, and epoxy resins. Curable resins that form a three-dimensional network structure, such as resins, are exemplified. Further, a fine powder pigment of a metal oxide 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 moiré and reduce residual potential.
These undercoat layers can be formed using an appropriate solvent and a coating method as in the above-described photosensitive layer. Further, 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, the undercoat layer of the present invention may be provided with Al ₂ O ₃ by anodic oxidation, an organic substance such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ Also, inorganic materials such as those provided by a vacuum thin film forming method can be used favorably. In addition, known materials can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

<Addition of antioxidant to each layer>
Further, in the present invention, in order to improve environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, a 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 antioxidants that can be used in the present invention include the following.
(Phenol compound)
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-t-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-t-butylphenol), 4, 4'-thiobis- (3-methyl-6-t-butylphenol), 4,4'-butylidenebis- (3-methyl-6-t-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 ] Clichol esters, tocopherols and the like.

(Paraphenylenediamines)
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N'-dimethyl-N, N'-di-tert-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 for rubber, plastics, fats and the like, 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.

<About Image Forming Method and Apparatus>
Next, an image forming method and an 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 according to the present invention use a photoreceptor having a smooth charge-transporting surface cross-linking layer. An image forming method and an image forming apparatus comprising a process of transferring and fixing a toner image to a body (transfer paper) and cleaning a 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 include the above-described process provided on a photosensitive member.

FIG. 5 is a schematic diagram illustrating an example of the image forming apparatus. As a means for charging the photoreceptor averagely, a charging charger (3) is used. 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, and the like are used, and a known method can be used.
In particular, the constitution of the present invention is effective when a charging means such as a contact charging method or a non-contact proximity arrangement charging method is used in which the photosensitive member composition is decomposed by proximity discharge from the charging means. Here, the contact charging method is a charging method in which a charging roller, a charging brush, a charging blade, or the like directly contacts a photosensitive member. On the other hand, the proximity charging system is of a type in which a charging roller is closely arranged in a non-contact state such that a charging roller has a gap of 200 μm or less between the surface of a photoreceptor and a charging unit. If the gap is too large, charging tends to be unstable, and if too small, there is a possibility that the surface of the charging member may be contaminated if toner remaining on the photoconductor exists. is there. Therefore, the space is suitably in the range of 10 to 200 μm, preferably 10 to 100 μm.
Next, an image exposure unit (5) is used to form an electrostatic latent image on the uniformly charged photoconductor (1). As the light source, any light-emitting material 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 electroluminescence (EL) can be used. To irradiate only light in a desired wavelength range, various 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.
Next, a developing unit (6) is used to visualize the electrostatic latent image formed on the photoconductor (1). As a developing method, there are a one-component developing method using a dry toner, a two-component developing method, and a wet developing method using a wet toner. When a positive (negative) charge is applied to the photoconductor and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photoconductor. If this is developed with a negative (positive) polarity toner (electric detection fine particles), a positive image can be obtained, and if it is developed with a positive (negative) polarity toner, a negative image can be obtained.
Next, a transfer charger (10) is used to transfer the toner image visualized on the photoconductor onto the transfer body (9). Further, a pre-transfer charger (7) may be used in order to perform the transfer more favorably. As these transfer means, a mechanical transfer method such as an electrostatic transfer method using a transfer charger or a bias roller, an adhesive transfer method, 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 photoconductor (1). Other separation means include electrostatic suction induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like. The charging means can be used as the separation charger (11).
Next, a fur brush (14) and a cleaning blade (15) are used to clean the toner remaining on the photoconductor after the transfer. In addition, a pre-cleaning charger (13) may be used to perform cleaning more efficiently. As other cleaning means, there are a web method, a magnet brush method and the like, but a single method or a plurality of methods may be used together.
Next, if necessary, a static eliminator is used to remove the latent image on the photoconductor. As the charge removing means, a charge removing lamp (2) and a charge removing charger are used, and the exposure light source and the charging means can be used, respectively.
In addition, known processes such as document reading, sheet feeding, fixing, and sheet discharging that are not in proximity to the photoconductor can be used.
As is apparent from the above description, the electrophotographic photoreceptor of the present invention is used not only 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 widely used.

The present invention is an image forming method and an image forming apparatus using the electrophotographic photosensitive member according to the present invention for such image forming means.
The image forming means may be fixedly incorporated in a copying machine, a facsimile, or a printer, or may be incorporated in a form of a process cartridge in such an apparatus and made detachable. FIG. 6 shows an example of the process cartridge.
The process cartridge for an image forming apparatus includes a photoconductor (101), and additionally includes a charging unit (102), a developing unit (104), a transfer unit (106), a cleaning unit (107), and a charge removing unit (not shown). ) Is a device (part) that is detachable from the image forming apparatus main body.
As shown in the image forming process by the apparatus illustrated in FIG. 6, the photoconductor (101) is rotated by the charging unit (102) while rotating in the direction of the arrow, and is exposed (103) by the exposure unit (not shown). An electrostatic latent image corresponding to the exposure image is formed on the surface, and the electrostatic latent image is developed with toner by a developing unit (104), and the toner development is transferred to a transfer body (105) by a transfer unit (106). Transcribed and printed out. Next, the surface of the photoreceptor after the image transfer is cleaned by the cleaning means (107), and is further discharged by the discharging means (not shown), and the above operation is repeated again.
The present invention provides a process cartridge for an image forming apparatus having a photoreceptor having a smooth charge transporting surface crosslinked layer and at least one of charging, developing, transferring, cleaning, and discharging means.

<Synthesis example of compound having monofunctional charge transporting structure>
The compound having a monofunctional charge transporting structure in the present invention is synthesized, for example, by the method described in Japanese Patent No. 3164426. An example is shown below.
(1) Synthesis of hydroxy-substituted triarylamine compound (Structural Formula B below) 113.85 g (0.3 mol) of a methoxy-substituted triarylamine compound (Structural Formula A below) and 138 g (0.92 mol) of sodium iodide Was added with 240 ml of sulfolane, and the mixture was heated to 60 ° C. in a nitrogen stream. To this solution, 99 g (0.91 mol) of trimethylchlorosilane was added dropwise over 1 hour, and the mixture was stirred at a temperature of about 60 ° C. for 4.5 hours to complete the reaction. About 1.5 L of toluene was added to the reaction solution, cooled to room temperature, and washed repeatedly with water and an aqueous solution of sodium carbonate. Thereafter, the solvent was removed from this toluene solution, and purification was performed by column chromatography (adsorption medium: silica gel, developing solvent: toluene: ethyl acetate = 20: 1). Cyclohexane was added to the obtained pale yellow oil to precipitate crystals. Thus, 88.1 g (yield = 80.4%) of white crystals of the following structural formula B were obtained.
Melting point: 64.0-66.0C

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

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. The “parts” used in the examples are all parts by weight.
<Example 1>
A coating liquid for an undercoat layer having the following composition, a coating liquid for a charge generation layer, and a coating liquid for a charge transport layer are sequentially coated and dried on an aluminum cylinder of φ30 mm to form a 3.5 μm undercoat layer. , A 0.2 μm charge generation layer and a 18 μm charge transport layer. A coating liquid for a crosslinked surface layer having the following composition is spray-coated on the charge transport layer, under the conditions of a metal halide lamp: 160 W / cm, an irradiation distance: 120 mm, an irradiation intensity: 500 mW / cm ² , and an irradiation time: 20 seconds. After irradiation with light, drying was further performed at 130 ° C. for 20 minutes to provide a surface crosslinked layer of 4 μm, thereby obtaining an electrophotographic photosensitive member of the present invention.
(Coating liquid for undercoat layer)
Alkyd resin 6 parts (Veccosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals, Inc.)
Melamine resin 4 parts (Super Beckamine G-821-60, manufactured by Dainippon Ink and Chemicals, Inc.)
Titanium oxide 40 parts Methyl ethyl ketone 50 parts [Coating liquid for charge generation layer]
Bisazo pigment of the following structural formula (I) 2.5 parts Polyvinyl butyral (XYHL, manufactured by UCC) 0.5 part Cyclohexanone 200 parts Methyl ethyl ketone 80 parts

〔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 １０部
（パンライトＴＳ−２０５０、帝人化成製）
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 １部
（ＫＦ５０−１００ＣＳ、信越化学工業製）

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

〔架橋表面層用塗工液〕
電荷輸送性構造を有さない３官能以上のラジカル重合性モノマー １０部
トリメチロールプロパントリアクリレート
（ＫＡＹＡＲＡＤ ＴＭＰＴＡ、日本化薬製）
分子量：２９６、官能基数：３官能、分子量／官能基数＝９９
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 １０部
（例示化合物Ｎｏ．５４）
光重合開始剤 １部
１−ヒドロキシ−シクロヘキシル−フェニル−ケトン
（イルガキュア１８４、チバ・スペシャルティ・ケミカルズ製）
テトラヒドロフラン １００部

(Coating liquid for crosslinked surface layer)
Trifunctional or higher functional radical polymerizable monomer having no charge transporting structure 10 parts Trimethylolpropane triacrylate (KAYARAD TMPTA, manufactured by Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99
Radical polymerizable compound having a monofunctional charge transporting structure 10 parts (exemplified compound No. 54)
Photopolymerization initiator 1 part 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
100 parts of tetrahydrofuran

<Example 2>
An electrophotographic photoreceptor in the same manner as in Example 1 except that the trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 1 was changed to the following monomer: Was prepared.
Trifunctional or higher functional radical polymerizable monomer having no charge transporting structure 10 parts Ditrimethylolpropanetetraacrylate (SR-355, manufactured by Kayaku Sartomer)
Molecular weight: 466, number of functional groups: 4 functions, molecular weight / number of functional groups = 117

<Example 3>
The trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 1 was changed to the following two kinds of mixed monomers, and the photopolymerization initiator was changed to the following compound. Except for the above, an electrophotographic photosensitive member was produced in the same manner as in Example 1.
Radical polymerizable monomer having 3 or more functional groups without charge transporting structure 6 parts Pentaerythritol tetraacrylate (SR-295, manufactured by Kayaku Sartomer)
Molecular weight: 352, number of functional groups: 4 functions, molecular weight / number of functional groups = 88
Radical polymerizable monomer having 3 or more functional groups without charge transporting structure 4 parts Alkyl-modified dipentaerythritol triacrylate (KAYARAD D-330, manufactured by Nippon Kayaku)
Molecular weight: 584, number of functional groups: trifunctional, molecular weight / number of functional groups = 195
Photopolymerization initiator 1 part 2,2-dimethoxy-1,2-diphenylethan-1-one (Irgacure 651, Ciba Specialty Chemicals)

<Example 4>
The same procedure as in Example 1 was carried out except that the trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 1 was changed to the following two kinds of mixed monomers. A photoreceptor was prepared.
Radical polymerizable monomer having three or more functional groups having no charge transporting structure 6 parts Dipentaerythritol hexaacrylate (KAYARAD DPHA, manufactured by Nippon Kayaku)
Molecular weight: 536, number of functional groups: 5.5, molecular weight / number of functional groups = 97
Radical polymerizable monomer having three or more functional groups having no charge transporting structure 4 parts Alkylated dipentaerythritol triacrylate (KAYARAD D-330, manufactured by Nippon Kayaku)
Molecular weight: 584, number of functional groups: trifunctional, molecular weight / number of functional groups = 195

<Example 5>
An electrophotographic photoreceptor in the same manner as in Example 1 except that the trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 1 was changed to the following monomer: Was prepared.
Trifunctional or higher functional radical polymerizable monomer having no charge transporting structure 10 parts Dipentaerythritol caprolactone-modified hexaacrylate (KAYARAD DPCA-60, manufactured by Nippon Kayaku)
Molecular weight: 1263, number of functional groups: 6 functions, molecular weight / number of functional groups = 211

<Example 6>
An electrophotographic photoreceptor in the same manner as in Example 1 except that the trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 1 was changed to the following monomer: Was prepared.
Trifunctional or higher functional radical polymerizable monomer having no charge transporting structure 10 parts Dipentaerythritol caprolactone-modified hexaacrylate (KAYARAD DPCA-120, manufactured by Nippon Kayaku)
Molecular weight: 1947, number of functional groups: 6 functions, molecular weight / number of functional groups = 325

<Example 7>
The radical polymerizable compound having a monofunctional charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 1 was exemplified by Compound No. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 127 and 10 parts were changed.

Example 8
The radical polymerizable compound having a monofunctional charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 1 was exemplified by Compound No. 94, and 10 parts, the photopolymerization initiator was changed to the following thermal polymerization initiator, and after coating on the charge transport layer in the same manner, heating was performed at 70 ° C. for 30 minutes using a blast oven, and further heated at 150 ° C. for 1 hour. A 4 μm crosslinked surface layer was provided to obtain a photoreceptor of the present invention.
Thermal polymerization initiator 1 part 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane (Percadox 12-EB20, manufactured by Kayaku Akzo)

<Example 9>
The radical polymerizable compound having a monofunctional charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 8 was exemplified by Compound No. An electrophotographic photosensitive member was prepared in the same manner as in Example 8, except that 138 and 10 parts were changed.

<Example 10>
6 parts of a trifunctional or higher functional radical polymerizable monomer not having a charge transporting structure, which is contained in the coating liquid for a crosslinked surface layer of Example 2, and 6 parts of a monofunctional charge transporting compound having a monofunctional charge transporting structure Was replaced with 14 parts to produce an electrophotographic photosensitive member in the same manner as in Example 2.

<Example 11>
14 parts of the amount of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for the crosslinked surface layer of Example 2 and the amount of the radical polymerizable compound having the monofunctional charge transporting structure Was replaced with 6 parts to prepare an electrophotographic photosensitive member in the same manner as in Example 2.

<Example 12>
A liquid containing a polymer charge transporting substance (PD-1) having the following composition was used as the coating liquid for the charge transporting layer of Example 1, and coated on the same charge generating layer and dried to form an 18 μm charge transporting layer. Formed. A surface cross-linking layer was provided on the charge transporting layer in the same manner as in Example 1 to produce an electrophotographic photosensitive member.
(Coating solution for charge transport layer)
15 parts of a polymer charge transport material having the following structural formula (PD-1)

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 ０．３部
（ＫＦ５０−１００ＣＳ、信越化学工業製）

Tetrahydrofuran 100 parts 1% silicone oil in tetrahydrofuran solution 0.3 part (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.)

<Example 13>
On the charge generation layer of Example 1, the same procedure as in Example 1 was carried out except that a coating liquid for a crosslinked surface layer having the following composition was spray-coated, and a 22 μm crosslinked surface layer was provided with a light irradiation time of 40 seconds. The photoreceptor of the present invention was produced.
(Coating liquid for crosslinked surface layer)
Radical polymerizable monomer having no charge transporting structure and having three or more functional groups 6 parts Dipentaerythritol caprolactone-modified hexaacrylate (KAYARAD DPCA-60, manufactured by Nippon Kayaku)
Molecular weight: 1263, number of functional groups: 6 functions, molecular weight / number of functional groups = 211
Trifunctional or higher radical polymerizable monomer having no charge transporting structure 4 parts Pentaerythritol tetraacrylate (SR-295, manufactured by Kayaku Sartomer)
Molecular weight: 352, number of functional groups: 4 functions, molecular weight / number of functional groups = 88
Radical polymerizable compound having a monofunctional charge transporting structure 10 parts (exemplified compound No. 54)
Photopolymerization initiator 2 parts 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
Tetrahydrofuran 60 parts Cyclohexanone 20 parts

<Comparative Example 1>
An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the coating solution for a crosslinked surface layer of Example 1 was changed to the following composition.
(Coating liquid for crosslinked surface layer)
Trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure 8 parts Trimethylolpropane triacrylate (KAYARAD TMPTA, manufactured by Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99
Polymer material 2 parts Bisphenol Z polycarbonate (Panlite TS-2050, manufactured by Teijin Chemicals)
Radical polymerizable compound having a monofunctional charge transporting structure 10 parts (exemplified compound No. 54)
Photopolymerization initiator 1 part 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
100 parts of tetrahydrofuran

<Comparative Example 2>
An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the coating solution for a crosslinked surface layer of Example 1 was changed to the following composition.
(Coating liquid for crosslinked surface layer)
Trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure 8 parts Trimethylolpropane triacrylate (KAYARAD TMPTA, manufactured by Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99
Polymer material 2 parts Polyarylate (U-Polymer U-100, manufactured by Unitika)
Radical polymerizable compound having a monofunctional charge transporting structure 10 parts (exemplified compound No. 54)
Photopolymerization initiator 1 part 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)
100 parts of tetrahydrofuran

<Comparative Example 3>
The radical polymerizable compound having a monofunctional charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 1 was replaced with 10 parts of a radical polymerizable compound having a bifunctional charge transporting structure represented by the following structural formula. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except for the above.
Radical polymerizable compound having a bifunctional charge transporting structure 10 parts

<Comparative Example 4>
A trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for a crosslinked surface layer of Example 1 was converted into a bifunctional radical polymerizable having no charge transporting structure of the following structural formula. An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that the monomer was changed to 10 parts.
Bifunctional radical polymerizable monomer having no charge transporting structure 10 parts 1,6-hexanediol diacrylate (manufactured by Wako Pure Chemical Industries, Ltd.)
Molecular weight: 226, number of functional groups: bifunctional, molecular weight / number of functional groups = 113

<Comparative Example 5>
A radical polymerizable compound having a monofunctional charge transport structure without containing a trifunctional or higher functional radical polymerizable monomer having no charge transport structure, which is a composition of the coating liquid for a crosslinked surface layer of Example 1. An electrophotographic photosensitive member was produced in the same manner as in Example 1, except that the amount was changed to 20 parts.

<Comparative Example 6>
A trifunctional or higher-functional radical polymerizable monomer having no charge transport structure without containing a monofunctional radical polymerizable compound having a monofunctional charge transport structure, which is a composition of the coating liquid for a crosslinked surface layer of Example 1. An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that the amount was changed to 20 parts.

<Comparative Example 7>
The composition does not contain a radically polymerizable compound having a monofunctional charge transporting structure which is a composition of the coating liquid for a crosslinked surface layer of Example 1. Instead, a low molecular charge transporting material having the following structural formula (D-2) An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that 10 parts were contained.
Low molecular charge transport material (D-2) 10 parts

<Comparative Example 8>
Same as Example 1 except that the diluting solvent (tetrahydrofuran: 100 parts) contained in the coating liquid for a crosslinked surface layer of Example 1 was changed to 45 parts of dichloromethane and the outermost surface layer was applied using a ring coater. An electrophotographic photosensitive member was produced.

<Comparative Example 9>
An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that the solvent tetrahydrofuran contained in the coating solution for a crosslinked surface layer in Example 7 was changed to 80 parts of butanol.

<Comparative Example 10>
Example 1 was repeated except that the curing conditions for the surface layer of Example 1 were changed to the conditions of an irradiation intensity of 40 mW / cm ² and an irradiation time of 5 minutes using the same light source as in Example 1, and a 4 μm crosslinked surface layer was provided. A 4 μm crosslinked surface layer was provided in the same manner as in the above to prepare an electrophotographic photosensitive member.

<Comparative Example 11>
An electrophotographic photosensitive member was produced in the same manner as in Example 8, except that the curing conditions for the surface layer in Example 8 were heated at 70 ° C. for 3 hours, and a crosslinked surface layer of 4 μm was provided.

<Comparative Example 12>
An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the crosslinked surface layer of Example 1 was not provided, and the thickness of the charge transport layer was changed to 22 μm.

<Comparative Example 13>
An electrophotographic photoreceptor was produced in the same manner as in Example 12, except that the crosslinked surface layer of Example 12 was not provided and the thickness of the charge transport layer containing the polymer charge transport material was changed to 22 μm.

このダイナミック微小硬度測定は、温度２２℃、相対湿度５５％の環境条件下で測定した。 The electrophotographic photosensitive members of Examples 1 to 13 and Comparative Examples 1 to 13 produced as described above were cut into appropriate sizes, a dynamic micro surface hardness meter DUH-201 (manufactured by Shimadzu Corporation), and a triangular indenter (115 °). ) Was used to measure the displacement-loading curve in the load-stationary-unload cycle. At this time, the set load was determined so that the maximum displacement was 1/10 of the crosslinked surface layer, the load and unloading speed were 0.0145 gf / sec, and the rest time of the maximum displacement was 5 seconds. The elastic displacement rate τe was calculated from the measured maximum displacement and plastic displacement by the following equation. The elastic displacement rate τe was measured at arbitrary 10 points on the sample, and the average was taken as the value, and the standard deviation of the elastic displacement rate was calculated from these 10 elastic change rates. Table 4 shows the results.

This dynamic microhardness measurement was performed under environmental conditions of a temperature of 22 ° C. and a relative humidity of 55%.

  Further, with respect to the electrophotographic photosensitive members of Examples 1 to 13 and Comparative Examples 1 to 13 similarly produced, a paper passing test of 30,000 sheets of A4 size was performed. First, the photosensitive member was mounted on a process cartridge for an electrophotographic apparatus, and the initial dark area potential was set to -700 V using a modified Ricoh image Neo 270 using a 655 nm semiconductor laser as an image exposure light source. Thereafter, a paper-passing test was started to evaluate the image at the initial stage and every 5,000 sheets, and to measure the potential of the dark portion and the exposed portion at the initial stage and after 30,000 copies, and the amount of decrease in the film thickness after 30,000 copies. Table 4 shows the results. The paper-passing test was stopped for the photoreceptor having a remarkable image defect from the beginning.

比較例１、２、７は測定位置による膜厚減少量の差が非常に大きい。比較例４は表面層が硬化していない。
表４の通紙試験結果より、実施例１〜１３で示される本発明の架橋表面層を有する感光体は、耐摩耗性が高く且つ良好な電気的特性を有し、経時において良好な画像が得られる。一方、比較例１、２、８〜１１の架橋表面層成分組成や硬化条件により架橋表面層の弾性変位率τｅが３５％未満またはその標準偏差が２％を越えている感光体は、全体または局部的な摩耗が激しく、初期または経時で画像不良が発生する。また、比較例３〜７のラジカル重合性組成物が本発明と異なる感光体は、表面の均一性、耐摩耗性または電気的特性が劣り、いずれも耐久性が低い。比較例１２の電荷輸送層に従来の熱可塑性バインダー樹脂を用いた感光体及び比較例１３の電荷輸送層に高分子電荷輸送物質を用いた感光体は、本発明の感光体に比べ耐摩耗性が低く、耐久性が劣る。

Comparative Examples 1, 2, and 7 have a very large difference in the amount of reduction in film thickness depending on the measurement position. In Comparative Example 4, the surface layer was not cured.
From the results of the paper passing test shown in Table 4, the photoreceptors having the crosslinked surface layers of the present invention shown in Examples 1 to 13 have high abrasion resistance and good electric characteristics, and have good images over time. can get. On the other hand, the photoconductors in which the elastic displacement rate τe of the crosslinked surface layer is less than 35% or the standard deviation thereof exceeds 2% depending on the composition and curing conditions of the crosslinked surface layer in Comparative Examples 1, 2, and 8 to 11, Intense local abrasion causes image failure at initial stage or over time. The photoreceptors of Comparative Examples 3 to 7 in which the radical polymerizable compositions are different from those of the present invention are inferior in surface uniformity, abrasion resistance or electric characteristics, and all have low durability. The photoreceptor using the conventional thermoplastic binder resin for the charge transport layer of Comparative Example 12 and the photoreceptor using the polymer charge transport material for the charge transport layer of Comparative Example 13 had higher abrasion resistance than the photoreceptor of the present invention. And low durability.

<Example 14>
The photoreceptor manufactured in the same manner as in Example 1 was mounted on a cyan photoreceptor unit of IPSIO Color 8000 manufactured by Ricoh, and 2,000 continuous prints of A4 horizontal feed cyan image area of 10% were performed. Later image evaluations were performed. As a result, no scratches or adhered matters were found on the drum surface, and a good image was obtained as in the initial stage even after the completion of 2,000 sheets.

<Comparative Example 14>
The photosensitive member manufactured in the same manner as in Comparative Example 1 was subjected to continuous printing of 2,000 sheets in the same manner as in Example 14, and the surface of the photosensitive member was observed, and the image was evaluated after 2,000 sheets. As a result, a large number of silica fixation of the toner external additive was observed on the drum surface. After 2,000 sheets, density unevenness of the halftone image occurred compared to the initial stage.

  The photoreceptor having a crosslinked surface layer of the present invention of Example 14 has no toner external additive adhered, and provides a good image with stability compared to the crosslinked surface layer photoreceptor of Comparative Example 14 having a large standard deviation of the elastic displacement rate. Is obtained.

  Therefore, the outermost surface layer of the photosensitive layer of the present invention is coated with a coating liquid containing a tri- or more functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure, By forming a cured cross-linked layer, and by setting the elastic displacement rate τe of the cross-linked surface layer to 35% or more and the standard deviation to 2% or less, a long-life and high-performance photosensitive element capable of maintaining a good image for a long time. It turned out that the body could be provided. In addition, it was also found that the image forming process, the image forming apparatus, and the process cartridge for the image forming apparatus using the photoreceptor of the present invention have high performance and high reliability.

It is a figure showing the micro hardness meter indenter schematic diagram for elastic displacement rate measurement of the present invention. It is the figure which showed the indentation depth-load curve for elastic displacement rate measurement of this invention. FIG. 2 is an example of a cross-sectional view of the electrophotographic photosensitive member of the present invention. FIG. 4 is another example of a cross-sectional view of the electrophotographic photosensitive member of the present invention. FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. FIG. 2 is a schematic view illustrating an example of a process cartridge for an image forming apparatus of the present invention.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 photoconductor 2 static elimination lamp 3 charging charger 4 eraser 5 image exposure unit 6 developing unit 7 pre-transfer charger 8 registration roller 9 transfer paper 10 transfer charger 11 separation charger 12 separation claw 13 pre-cleaner charger 14 fur brush 15 cleaning blade 31 conductivity Support 33 Photosensitive layer 35 Charge generation layer 37 Charge transport layer 101 Photosensitive drum 102 Charging device 103 Exposure 104 Developing device 105 Transfer member 106 Transfer device 107 Cleaning blade

Claims (16)

In an electrophotographic photosensitive member 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 transporting structure and a monofunctional charge transporting structure. An electron, comprising a crosslinked layer obtained by curing a radical polymerizable compound, wherein the crosslinked surface layer has an elastic displacement rate τe of 35% or more and a standard deviation of the elastic displacement rate τe is within 2%. Photoreceptor. 3. The functional group of a trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure contained in the surface layer coating liquid is an acryloyloxy group and / or a methacryloyloxy group. 2. The electrophotographic photoreceptor according to 1. The ratio of the molecular weight to the number of functional groups (molecular weight / number of functional groups) in the tri- or more-functional radical polymerizable monomer having no charge transporting structure used in the surface layer (molecular weight / number of functional groups) is 250 or less. 2. The electrophotographic photoreceptor according to 1. 4. The electron according to claim 1, wherein the functional group of the radical polymerizable compound having a monofunctional charge transporting structure used in the surface layer is an acryloyloxy group or a methacryloyloxy group. Photoreceptor. The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein the charge transport structure of the radical polymerizable compound having a monofunctional charge transport structure used in the surface layer is a triarylamine structure. . The radical polymerizable compound having a monofunctional charge transporting structure used for the surface layer is one or more of the following general formulas (1) and (2). The electrophotographic photosensitive member according to the above.

(Wherein, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group optionally having a substituent, an aralkyl group optionally having a substituent, an aryl group optionally having 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 be 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 good an aryl group, or a may) also being the same or different, Ar _1, Ar ₂ represents a substituted or unsubstituted arylene group, optionally .Ar ₃ be the same or different, Ar ₄ is substituted or Represents an unsubstituted aryl group, which may be the same or different, X is a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted divalent alkylene ether group or an alkyleneoxycarbonyl divalent group, and m and n are each an integer of 0 to 3. Represents.) 7. The electrophotograph according to claim 1, 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 (3). Photoconductor.

(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 represent an alkyl group having 1 to 6 carbon atoms. And s and t represent an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

Represents ) The component ratio of a trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in 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. The component ratio of the radical polymerizable compound having a monofunctional charge transporting structure used in the surface layer is 30 to 70% by weight based on the total amount of the crosslinked surface layer. 2. The electrophotographic photoreceptor according to 1. The electrophotographic photoreceptor according to any one of claims 1 to 9, 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 10, wherein the charge transport layer of the photosensitive layer contains a polymer charge transport material. The electrophotographic photoreceptor according to claim 11, wherein the polymer charge transport material is a polycarbonate having a triarylamine structure in a main chain or a side chain. 13. The electrophotographic photoreceptor according to claim 1, wherein the means for curing the surface layer is heating or light energy irradiation means. 14. An image forming method, wherein at least charging, image exposure, development, and transfer are repeatedly performed using the electrophotographic photosensitive member according to claim 1. An image forming apparatus comprising the electrophotographic photosensitive member according to claim 1. An electrophotographic photoreceptor according to any one of claims 1 to 13, and at least one unit selected from the group consisting of a charging unit, a developing unit, a transferring unit, a cleaning unit, and a discharging unit, A process cartridge for an image forming apparatus, which is detachable from an image forming apparatus main body.

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