JP5585814B2 - Electrophotographic photosensitive member, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member, an image forming apparatus that forms an image using the electrophotographic photosensitive member, and a process cartridge. The image forming apparatus and the process cartridge of the present invention are widely applied to a copying machine, a facsimile, a laser printer, a direct digital plate making machine, and the like.

  2. Description of the Related Art In recent years, image forming apparatuses such as electrophotographic laser printers and digital copying machines have been widely spread due to their improved image quality and stability. The electrophotographic photosensitive member used in these image forming apparatuses has a function of forming an electrostatic latent image on the surface by charging and exposure, and forming a visible image by developing the electrostatic latent image.

  Electrophotographic photoreceptors are broadly classified into inorganic photoreceptors and organic photoreceptors, but organic photoreceptors are widely used due to cost, productivity, freedom of material selection, and influence on the global environment. . The organic photoreceptor is composed of a photosensitive layer mainly containing a photosensitive material, a single layer type having a charge generation function and a charge transport function in one layer, a charge generation layer having a charge generation function, and a charge transport. It is roughly classified into a stacked type in which the function is separated into a charge transport layer having a function.

  The mechanism of electrostatic latent image formation in layered organic photoreceptors with separated functions is that when a uniformly charged organic photoreceptor is irradiated with light, the light passes through the charge transport layer and the charge generation material in the charge generation layer To generate a charge (charge pair). One of them is injected into the charge transport layer at the interface between the charge generation layer and the charge transport layer, and further moves through the charge transport layer by an electric field, reaches the surface of the organophotoreceptor, and neutralizes the surface charge provided by charging. Thus, an electrostatic latent image is formed. These organic photoreceptors having a laminated structure are advantageous in terms of stability and durability of electrostatic characteristics, and are currently mainstream in electrophotographic photoreceptors.

  Recently, image forming apparatuses using these organophotoreceptors are rapidly becoming full-color and speeding up, and the demand is diversifying from the general office area to the light printing area. In particular, in the light printing field, the printing volume is remarkably increased and the demand for image quality stability is increased. Therefore, it is indispensable to further increase the durability and stability of the organic photoreceptor.

  In order to increase the durability of the organic photoreceptor, it is necessary to increase the wear resistance of the organic photoreceptor. These conventionally known techniques include (1) using a curable binder for the surface layer (Patent Document 1), (2) using a polymer type charge transport material (Patent Document 2), (3) surface Examples include those in which an inorganic filler is dispersed in a layer (Patent Document 3), and (4) those in which filler fine particles are dispersed in a cured surface layer (Patent Document 4).

  However, if it is assumed that it is used in the light printing field, even if these technologies alone are insufficient in abrasion resistance, or even if abrasion resistance is not a problem, image blurring, filming, and foreign matter adhesion As a result, the electrophotographic photosensitive member has to be replaced relatively early. This is because the surface of the electrophotographic photosensitive member is less likely to be refaced when the abrasion resistance of the electrophotographic photosensitive member is increased, so that the decomposition products of the constituent materials are accumulated or foreign matters are fixed on the surface. It is thought to induce such abnormal images.

  Conventionally known techniques for preventing filming and adhesion of foreign matter on the surface of the electrophotographic photosensitive member include (1) a roughened surface of the electrophotographic photosensitive member (Patent Documents 5 and 6), and (2) electrophotographic photosensitive member. Techniques such as those in which a lubricant is added to the surface of the body (Patent Document 7) and (3) those in which a lubricant is applied to the surface of the electrophotographic photosensitive member (Patent Documents 8 and 9) are disclosed.

  These techniques are effective methods because the lubricity of the electrophotographic photosensitive member surface is improved. However, the technique of adding a lubricant to the surface of the electrophotographic photosensitive member has a big problem in the sustainability of the effect. It is difficult to suppress for a long time the contamination of the surface caused by repeating each process such as charging, developing or cleaning on the electrophotographic photosensitive member with a lubricant contained in the electrophotographic photosensitive member. On the other hand, the method of applying a lubricant to the surface of the electrophotographic photosensitive member has a very high sustainability because the lubricant is reliably supplied to the surface even if the surface of the electrophotographic photosensitive member is contaminated. As a result, the behavior of the cleaning blade is stabilized, cleaning defects are reduced, and foreign matter adhesion is suppressed. When used in the light printing field where high durability and stability are required for the electrophotographic photosensitive member, the technique of applying a lubricant is very effective and is also useful in the present invention.

  In addition, by repeatedly charging and exposing the electrophotographic photosensitive member, image blur may occur due to the influence of an oxidizing gas such as ozone gas generated from the charger or NOx gas existing in the environment where the image forming apparatus is used, or exposure may occur. There is also a problem that the electrostatic stability such as an increase in the partial potential and a decrease in the dark portion potential is remarkably reduced, and the image density fluctuates. Such an oxidizing gas does not adhere to the surface of the electrophotographic photosensitive member but penetrates into the film, and therefore cannot be solved by the means for applying the lubricating substance as described above.

  Techniques for adding various antioxidants to the photosensitive layer or the surface layer have been disclosed in order to suppress image blur due to oxidizing gas and to improve gas resistance (Patent Document 10 and Patent Document 11). However, conventionally known antioxidants have not only a small effect on image blur, but also have a side effect of increasing the exposed area potential. Therefore, in order to suppress the image blur in the long-term repeated use, a lot of antioxidants must be added. As a result, the exposed area potential is remarkably increased, and there is a problem in the stability of the image density. .

  Conventionally known techniques for reducing the exposed area potential include ionization potential and oxidation potential of the charge transport material contained in the crosslinkable charge transport layer, and ionization of the charge transport material contained in the charge transport layer formed thereunder. A photoreceptor having a potential or an oxidation potential or lower is disclosed (Patent Document 12). A charge transport material having a smaller ionization potential or oxidation potential has a smaller charge injection barrier at the layer interface, and is therefore effective in reducing the exposed portion potential. However, such charge transport materials generally lack chemical stability and are particularly susceptible to alteration with oxidizing gases, resulting in significant image blur. Therefore, simply reducing the ionization potential or oxidation potential of the charge transport material does not solve the problem.

  In addition, the cross-linked charge transport layer contains the same low-molecular charge transport material as the charge transport layer formed thereunder, and the charge transport material is formed such that the concentration decreases sequentially from the charge transport layer side. A photographic photoreceptor is disclosed (Patent Document 13). Thereby, the abrasion resistance of the electrophotographic photosensitive member is improved and the residual potential can be reduced. However, when the added low-molecular charge transport material inhibits curing in the cross-linked charge transport layer, or when ultraviolet light is used to cure the cross-linked charge transport layer, the added low-molecular charge transport material is decomposed. Therefore, it is not always effective to reduce the residual potential in long-term repeated use.

  In addition, the charge generation layer, the charge transport layer 1, the charge transport layer 2, and the charge transport cross-linked surface layer are laminated in order, and the thermoplastic resins contained in the charge transport layer 1 and the charge transport layer 2 are different. An electrophotographic photoreceptor in which the charge transport material content is greater than the charge transport material content of the charge transport layer 1 is disclosed (Patent Document 14). Thereby, an effect of suppressing the afterimage is obtained, but there is no description regarding image blur suppression which is one of the effects obtained by the present invention. In fact, increasing the charge transport material content of the charge transport layer 2 more than the charge transport layer 1 is often disadvantageous for image blur, and is a technology that is completely different in configuration and effect from the present invention.

  Also disclosed is an electrophotographic photoreceptor in which a charge transport layer containing a charge transport material and a charge transport layer containing a charge transport material having an oxidation potential higher than that of the charge transport material are laminated on the charge generation layer ( Patent Document 15). This is also the subject of image blurring and residual potential accumulation, but the present invention has a structure in which a cross-linked charge transport layer is provided on the surface for the purpose of realizing high durability at the same time. Of course, the structure and the size of the problem and effect differ greatly.

  On the other hand, techniques for adding a compound having an alkylamino group to the photosensitive layer or the surface layer for the same purpose have been disclosed (Patent Document 16, Patent Document 17, and Patent Document 18). These techniques are very effective for suppressing image blurring, and are less effective than the above-described antioxidants in terms of the influence of an increase in the potential of the exposed area. However, within the range of durability required for conventional electrophotographic photoreceptors, these conventionally known techniques may be able to solve the problem, but considering that they are used in the field of light printing, they are required. It is not enough to satisfy the characteristics.

  Image blur caused by repeated use of the electrophotographic photosensitive member is exposed to an oxidizing gas generated from the charger, and the constituent materials such as a charge transport material constituting the electrophotographic photosensitive member are altered. It is thought that this occurs. A compound having an alkylamino group is considered to be an effective factor due to its high ability to suppress alteration, but if the use frequency and period of use of an electrophotographic photosensitive member are increased accordingly, a compound having an alkylamino group Therefore, it is necessary to make it contain so much. In this case, the problem that the exposed portion potential of the electrophotographic photosensitive member increases with time is unavoidable.

  The problem of the exposure portion potential increase in the image forming apparatus used in the light printing field is that the printing is started and one job is finished, again than the exposure portion potential increase when printing is performed for a relatively long time. The increase in the potential of the exposed area when printing is started is larger as a problem. Hereinafter, the former is referred to as daily fluctuation of the exposure part potential, and the latter is referred to as intra-job fluctuation of the exposure part potential. In the case of daily fluctuations in the exposure part potential, the effect is not noticeable and the potential can be corrected in the apparatus. Therefore, the problem is not so great, but if the fluctuation in the job is large, the influence is conspicuous. If the potential fluctuates by several tens or several sheets in the job, it becomes difficult to correct the potential, which is a serious problem.

  In particular, in the light printing field, there is a demand for printing a large amount of the same image pattern with one job. In this case, if the fluctuation in the exposure portion potential in the job is large, the image density changes and the image quality consistency is lowered. become. If it is a character-based image pattern, it will not stand out so much, but if it is an image-based and full-color image pattern, not only the image density but also the color will change, leading to a very serious problem. That is, it is required to reduce the exposed portion potential of the photosensitive member and further suppress the exposed portion potential fluctuation in long-term repetitive printing, not only the daily fluctuation but also the intra-job fluctuation. At the same time, there must be no wear of images and no reduction in resolution, and filming, adhesion of foreign matter, defective cleaning, etc. can be suppressed, and wear resistance and scratch resistance must be achieved so that the life can be completed.

  As described above, in order to use in the light printing field, not only the wear resistance and scratch resistance are improved, but also the potential stabilization against repeated use of the electrophotographic photosensitive member and abnormal images such as image blurring, filming, and poor cleaning. It is necessary to simultaneously suppress image quality and improve image quality consistency. However, the conventional technology has not yet realized this, and a highly durable and highly stable electrophotographic photosensitive member capable of withstanding the demand in the light printing field has been eagerly desired.

  Even if the electrophotographic photosensitive member is repeatedly used for a long time, the present invention does not generate an abnormal image due to image blurring, filming, cleaning failure, or the like, and further suppresses not only the daily fluctuation of the exposed portion potential but also the fluctuation in the job. As a result, it is an object of the present invention to provide a highly durable and highly stable electrophotographic photosensitive member having always stable image density and excellent image quality consistency, and an image forming apparatus and a process cartridge using the same.

  The image blur that occurs due to repeated use is considered to be caused by the deterioration and alteration of the charge transport material by the oxidizing gas, and the influence increases as the oxidation potential of the charge transport material decreases. Therefore, the smaller the oxidation potential of the charge transport material, the greater the influence of image blur. However, although a charge transport material having a relatively large oxidation potential is advantageous for suppressing image blurring, the influence of an increase in the potential of the exposed portion is increased, and in particular, exposure within a job that is regarded as a problem in use in the light printing field. The partial potential increase is remarkably increased. Therefore, it is very difficult to achieve both suppression of image blur and suppression of exposure portion potential increase while maintaining a very long life.

  Since the oxidizing gas penetrates from the surface of the electrophotographic photoreceptor to the inside, conventionally, a method of increasing the oxidation potential of the charge transport material contained in the surface layer or adding an additive such as an antioxidant is generally used. It was the target. However, it has been found that when a cross-linked charge transport layer is formed on the surface layer of an electrophotographic photoreceptor, the surface layer does not necessarily cause image blur. Crosslinked charge transport layers generally have high gas permeability, and oxidizing gas generated by repeated use over a long period of time penetrates the inside of the crosslinkable charge transport layer and is contained in the charge transport layer formed thereunder It is considered that the charge transport material is oxidized and deteriorated. For this reason, it is considered that image blur occurs at the interface between the charge transport layer and the cross-linked charge transport layer.

  Therefore, as a result of investigations by the present inventors, in an electrophotographic photoreceptor having a crosslinkable charge transport layer formed on the surface, in order to suppress image blur, the charge formed under the crosslinkable charge transport layer is It was found that this can be realized by setting the oxidation potential of the transport material to be higher than 0.705 (V vs. SCE). However, when such a charge transport material is used, the charge injection property at the interface between the charge generation layer and the charge transport layer is lowered, and as a result, the exposed portion potential in the job is significantly increased. In view of this, the present inventors, in an electrophotographic photosensitive member using a crosslinkable charge transport layer on the surface, have two charge transport layers formed under the crosslinkable charge transport layer and formed on the charge generation layer side. The charge transport material contained in the charge transport layer 1 and the charge transport material contained in the charge transport layer 2 formed on the cross-linked charge transport layer side are selected so that their oxidation potentials satisfy a specific relationship As a result, it has been found that image blurring and an increase in potential of the exposed portion in the job can be suppressed, and the present invention has been completed.

That is, the present inventors have provided an electrophotographic photosensitive member in which at least a charge generation layer, a charge transport layer 1, a charge transport layer 2, and a crosslinkable charge transport layer are sequentially laminated on a conductive support. Comprises a cured product of at least a polymerizable compound having a charge transporting structure and a polymerizable compound not having a charge transporting structure, and the charge transporting layer 1 contains a charge transporting substance having an oxidation potential Eox (CTL1), The charge transport layer 2 contains a charge transport material having an oxidation potential Eox (CTL2), and the oxidation potential Eox (CTL1) and the oxidation potential Eox (CTL2) are expressed by the following formula: Eox (CTL1) <0.705 (V vs. SCE) <Eox (CTL2)
By the oxidation potential of less than and, and the polymerizable compound having a charge transport structure is, 0.750 (V vs. SCE) or more, or less 0.850 (V vs. SCE), the electrophotographic photosensitive member However, even when used repeatedly for a long time, the occurrence of image blur is reduced, and it is possible to reduce not only the daily fluctuation of the exposure part potential but also the fluctuation within the job. In addition, the present inventors have found that an electrophotographic photosensitive member that does not generate abnormal images such as poor cleaning and the like, that is, can output an image with excellent image quality consistency.

［上式（１）中、Ｒ_１〜Ｒ_４は、それぞれ、水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、フェニル基のいずれかを表し、各々同一でも異なっていても良い。フェニル基は無置換のものでも良いし、炭素数１〜４のアルキル基や炭素数１〜４のアルコキシ基を置換基として有していても良い。
Ａは、置換もしくは無置換のアリーレン基、または下記一般式（１ａ）で表される基を表す。

（上式（１ａ）中、Ｒ_５、Ｒ_６及びＲ_７は、それぞれ、水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、フェニル基を表し、フェニル基の場合は無置換でも良いし、炭素数１〜４のアルキル基や炭素数１〜４のアルコキシ基を置換基として有していても良い。）
Ｂ及びＢ’は、それぞれ、置換もしくは無置換のアリール基、または下記一般式（１ｂ）で表される基を表す。Ｂ及びＢ’は、同一であっても異なっていても良い。

（上式（１ｂ）中、Ａｒ_１はアリーレン基を表わし、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。また、Ａｒ_２及びＡｒ_３は、それぞれアリール基を表し、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。）
但し、Ａ、Ｂ及びＢ’の少なくとも一つにトリアリールアミン構造を有する。］
（４）前記酸化電位Ｅｏｘ（ＣＴＬ１）の電荷輸送物質及び／または酸化電位Ｅｏｘ（ＣＴＬ２）の電荷輸送物質が、下記一般式（２）で表されるトリアリールアミン化合物であることを特徴とする（２）に記載の電子写真感光体。

[上式中、Ａｒ_４、Ａｒ_５、Ａｒ_７、Ａｒ_８は水素原子、炭素数１〜４のアルキル基やアルコキシ基、アリール基を表わし、アリール基の場合は炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。また、Ａｒ_６はアリーレン基を表し、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。Ｒ_８は、水素原子、炭素数１〜４のアルキル基や炭素数１〜４のアルコキシ基を表す。また、ｎは０または１の整数を表す。]
（５）前記酸化電位Ｅｏｘ（ＣＴＬ１）の電荷輸送物質及び／または酸化電位Ｅｏｘ（ＣＴＬ２）の電荷輸送物質が、下記一般式（３）で表されるトリアリールアミン化合物であることを特徴とする（２）に記載の電子写真感光体。

[上式中、Ａｒ_９、Ａｒ_１０はアリール基を表わし、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。また、Ａｒ_１１はアリーレン基を表し、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。Ｘは置換もしくは無置換のアリール基、または下記一般式（３ａ）で表される基を表す。]

[上式中、Ａｒ_１２、Ａｒ_１３はアリール基を表わし、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。また、Ａｒ_１４はアリーレン基を表し、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。]
（６）前記酸化電位Ｅｏｘ（ＣＴＬ１）の電荷輸送物質及び／または酸化電位Ｅｏｘ（ＣＴＬ２）の電荷輸送物質の分子量が、３００以上、８００以下の範囲内であることを特徴とする（１）〜（５）のいずれかに記載の電子写真感光体。
（７）前記電荷輸送性構造を有する重合性化合物の官能基数が１であり、前記電荷輸送性構造を有さない重合性化合物の官能基数が３以上であることを特徴とする（１）〜（６）のいずれかに記載の電子写真感光体。
（８）前記電荷輸送性構造を有さない重合性化合物が、官能基数の異なる複数の重合性化合物の混合物であることを特徴とする（７）に記載の電子写真感光体。
（９）前記電荷輸送性構造を有する重合性化合物及び／又は電荷輸送性構造を有さない重合性化合物の官能基が、アクリロイルオキシ基及び／又はメタクリロイルオキシ基であることを特徴とする（１）〜（８）のいずれかに記載の電子写真感光体。
（１０）前記電荷輸送性構造を有する重合性化合物の電荷輸送性構造が、トリアリールアミン構造であることを特徴とする（１）〜（９）のいずれかに記載の電子写真感光体。
（１１）前記電荷輸送性構造を有する重合性化合物が、下記一般式（４）又は（５）で表される化合物の一種以上であることを特徴とする（１０）に記載の電子写真感光体。

[上式中、Ｒ₁は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ₇（Ｒ₇は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ₈Ｒ₉（Ｒ₈及びＲ₉は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ₁、Ａｒ₂は置換もしくは無置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ₃、Ａｒ₄は置換もしくは無置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル基、アルキレンオキシカルボニル基を表わす。ｍ、ｎは０〜３の整数を表わす。]
（１２）前記架橋型電荷輸送層が、フィラーを含有していることを特徴とする（１）〜（１１）のいずれかに記載の電子写真感光体。
（１３）少なくとも電子写真感光体と、該電子写真感光体を帯電させる帯電手段と、該電子写真感光体に静電潜像を形成する静電潜像形成手段と、該電子写真感光体上にトナーを用いて可視像を形成する現像手段とを有し、該電子写真感光体が（１）〜（１２）のいずれかに記載の電子写真感光体であることを特徴とする画像形成装置。
（１４）前記画像形成装置において、少なくとも前記電子写真感光体と、前記帯電手段、前記静電潜像形成手段、前記現像手段から選択される少なくとも一つが複数備えられたタンデム方式であることを特徴とする（１３）に記載の画像形成装置。
（１５）前記画像形成装置において、前記電子写真感光体表面に、潤滑性物質を付着させる潤滑性物質塗布手段を有することを特徴とする（１３）または（１４）に記載の画像形成装置。
（１６）前記潤滑性物質が、少なくともステアリン酸亜鉛を含有していることを特徴とする（１５）に記載の画像形成装置。
（１７）帯電手段、静電潜像形成手段、現像手段、転写手段、クリーニング手段、除電手段、潤滑性物質塗布手段の少なくとも１つと、（１）〜（１２）のいずれかに記載の電子写真感光体とが一体化し、画像形成装置本体に対し着脱可能であることを特徴とするプロセスカートリッジ。 That is, the present invention relates to an electrophotographic photosensitive member as described in the following (1) to (17), an image forming apparatus using the same, and a process cartridge.
(1) In an electrophotographic photosensitive member in which at least a charge generation layer, a charge transport layer 1, a charge transport layer 2, and a crosslinkable charge transport layer are sequentially laminated on a conductive support, the crosslinkable charge transport layer is at least a charge transport layer. The charge transport layer 1 comprises a charge transport material having an oxidation potential Eox (CTL1), comprising a cured product of a polymerizable compound having a conductive structure and a polymerizable compound having no charge transport structure. 2 contains a charge transporting substance having an oxidation potential Eox (CTL2), the oxidation potential Eox (CTL1) and the oxidation potential Eox (CTL2) satisfy the following formula and have the charge transporting structure The electrophotographic photosensitive member is characterized by having an oxidation potential of 0.750 (V vs. SCE) or more and 0.850 (V vs. SCE) or less.
Eox (CTL1) <0.705 (V vs. SCE) <Eox (CTL2)
(2) The electrophotographic photosensitive member according to (1), wherein the charge transport material having the oxidation potential Eox (CTL1) and / or the charge transport material having the oxidation potential Eox (CTL2) has a triarylamine structure. .
(3) The charge transport material having the oxidation potential Eox (CTL1) and / or the charge transport material having the oxidation potential Eox (CTL2) is a triarylamine compound represented by the following general formula (1): The electrophotographic photosensitive member according to (2).

[In the above formula (1), R _{1 to} R ₄ each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group. May be. The phenyl group may be unsubstituted, or may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms as a substituent.
A represents a substituted or unsubstituted arylene group or a group represented by the following general formula (1a).

(In the above formula (1a), R ₅ , R ₆ and R ₇ each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group. May be unsubstituted or may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms as a substituent.)
B and B ′ each represent a substituted or unsubstituted aryl group or a group represented by the following general formula (1b). B and B ′ may be the same or different.

(In the above formula (1b), Ar ₁ represents an arylene group and may have an alkyl group or alkoxy group having 1 to 4 carbon atoms as a substituent. Ar ₂ and Ar ₃ are each an aryl group. And may have a C 1-4 alkyl group or alkoxy group as a substituent.
However, at least one of A, B and B ′ has a triarylamine structure. ]
(4) The charge transport material having the oxidation potential Eox (CTL1) and / or the charge transport material having the oxidation potential Eox (CTL2) is a triarylamine compound represented by the following general formula (2): The electrophotographic photosensitive member according to (2).

[In the above formula, Ar ₄ , Ar ₅ , Ar ₇ , Ar ₈ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or an aryl group, and in the case of an aryl group, an alkyl group having 1 to 4 carbon atoms] Or an alkoxy group as a substituent. Ar ₆ represents an arylene group and may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. R ₈ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. N represents an integer of 0 or 1. ]
(5) The charge transport material having the oxidation potential Eox (CTL1) and / or the charge transport material having the oxidation potential Eox (CTL2) is a triarylamine compound represented by the following general formula (3): The electrophotographic photosensitive member according to (2).

[In the above formula, Ar ₉ and Ar ₁₀ represent an aryl group, which may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. Ar ₁₁ represents an arylene group and may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. X represents a substituted or unsubstituted aryl group, or a group represented by the following general formula (3a). ]

[In the above formula, Ar ₁₂ and Ar ₁₃ represent an aryl group, which may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. Ar ₁₄ represents an arylene group and may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. ]
(6) The molecular weight of the charge transport material having the oxidation potential Eox (CTL1) and / or the charge transport material having the oxidation potential Eox (CTL2) is in the range of 300 to 800. (5) The electrophotographic photoreceptor according to any one of (5).
(7) The number of functional groups of the polymerizable compound having the charge transporting structure is 1, and the number of functional groups of the polymerizable compound not having the charge transporting structure is 3 or more. The electrophotographic photosensitive member according to any one of (6).
(8) The electrophotographic photosensitive member according to (7), wherein the polymerizable compound having no charge transporting structure is a mixture of a plurality of polymerizable compounds having different numbers of functional groups.
(9) The functional group of the polymerizable compound having the charge transporting structure and / or the polymerizable compound not having the charge transporting structure is an acryloyloxy group and / or a methacryloyloxy group (1) The electrophotographic photosensitive member according to any one of (8) to (8).
(10) The electrophotographic photosensitive member according to any one of (1) to (9), wherein the charge transporting structure of the polymerizable compound having the charge transporting structure is a triarylamine structure.
(11) The electrophotographic photosensitive member according to (10), wherein the polymerizable compound having a charge transporting structure is one or more of the compounds represented by the following general formula (4) or (5): .

[In the above formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, A nitro group, an alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), Halogenated carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. And Ar ₁ and Ar ₂ each represents a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, or an alkyleneoxycarbonyl group. m and n represent an integer of 0 to 3. ]
(12) The electrophotographic photosensitive member according to any one of (1) to (11), wherein the crosslinkable charge transport layer contains a filler.
(13) At least an electrophotographic photoreceptor, charging means for charging the electrophotographic photoreceptor, electrostatic latent image forming means for forming an electrostatic latent image on the electrophotographic photoreceptor, and on the electrophotographic photoreceptor An image forming apparatus comprising: a developing unit that forms a visible image using toner; and the electrophotographic photosensitive member according to any one of (1) to (12). .
(14) The image forming apparatus is a tandem system including at least one selected from at least the electrophotographic photosensitive member, the charging unit, the electrostatic latent image forming unit, and the developing unit. The image forming apparatus according to (13).
(15) The image forming apparatus according to (13) or (14), wherein the image forming apparatus further includes a lubricating substance applying unit that adheres a lubricating substance to the surface of the electrophotographic photosensitive member.
(16) The image forming apparatus according to (15), wherein the lubricating substance contains at least zinc stearate.
(17) At least one of a charging unit , an electrostatic latent image forming unit, a developing unit, a transfer unit, a cleaning unit, a charge eliminating unit, and a lubricating substance applying unit, and the electrophotography according to any one of (1) to (12) A process cartridge which is integrated with a photoconductor and is detachable from a main body of an image forming apparatus.

  According to the present invention, the occurrence of image blur is reduced even in repeated use over a long period of time, and it is possible to reduce not only the daily fluctuation of the exposure part potential but also the fluctuation in the job. It is possible to provide an electrophotographic photosensitive member that is small and does not generate abnormal images such as filming and cleaning defects, that is, can output an image with excellent image quality consistency. Furthermore, the image forming apparatus and a process cartridge for the image forming apparatus can be provided.

It is a figure showing an example of the structure of the electrophotographic photoreceptor which concerns on this invention. 1 is a diagram illustrating an example of an outline of an image forming apparatus according to the present invention. It is a figure showing an example of an electrophotographic photoreceptor and a non-contact type charging roller. It is a figure showing an example of the multi-beam exposure means used for the image forming apparatus of this invention. It is a figure showing an example of a lubricous substance application means. 1 is a diagram illustrating an example of a full-color image forming apparatus using a tandem method according to the present invention. It is a figure showing an example of the process cartridge of this invention. It is a figure which shows the X-ray-diffraction spectrum of titanyl phthalocyanine preferably used as a charge generation substance.

Next, the electrophotographic photoreceptor and the manufacturing method thereof will be described in detail below.
<About the layer structure of the electrophotographic photoreceptor>
The electrophotographic photosensitive member produced according to the present invention will be described with reference to FIG. In FIG. 1A, a charge generation layer (32) having a charge generation function, a charge transport layer 1 (33) having a charge transport function, and a charge transport function are also provided on a conductive support (31). This is a photoreceptor in which the charge transport layer 2 (34) and a cross-linked charge transport layer (35) having a charge transport function are further laminated. As in (B), an undercoat layer (36) may be provided between the conductive support (31) and the charge generation layer (32). Although not shown, the undercoat layer may have a two-layer structure.

<About conductive support>
Examples of the conductive support include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, oxidation Metal oxide such as indium coated on film or cylindrical plastic or paper by vapor deposition or sputtering; aluminum, aluminum alloy, nickel, stainless steel plates and the like, and extruding, drawing, etc. After pipe formation, a surface-treated pipe such as cut, superfinished or polished can be used. For example, an endless nickel belt and an endless stainless steel belt disclosed in Patent Document 19 can also be used as the conductive support.

  Furthermore, what formed the electroconductive layer (it formed using coating etc.) by disperse | distributing electroconductive powder to binder resin on said electroconductive support body can also be used as an electroconductive support body. Examples of such conductive powders include carbon black, acetylene black; metal powders such as aluminum, nickel, iron, nichrome, copper, zinc, silver, and metal oxide powders such as conductive tin oxide and ITO. It is done. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, Polyvinyl acetate, polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly (N-vinylcarbazole), acrylic resin, silicone resin, epoxy resin, melamine Examples thereof include thermoplastic resins such as resins, urethane resins, phenol resins, and alkyd resins, thermosetting resins, and photocurable resins. The conductive layer can be provided by dispersing conductive powder and a binder resin in a solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, or toluene and applying the conductive powder and the binder resin. Furthermore, using a heat-shrinkable tube containing conductive powder in materials such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, polytetrafluoroethylene fluororesin, etc. Those provided with a conductive layer can also be used as a conductive support.

  Of these, a cylindrical support made of aluminum that can be easily subjected to the anodic oxide film treatment can be used favorably. This aluminum includes either a pure aluminum system or an aluminum alloy. Specifically, JIS 1000, 3000, and 6000 series aluminum or aluminum alloy is most suitable. Anodized films are anodized various metals and various alloys in an electrolyte solution. Among them, a film called anodized aluminum or aluminum alloy that has been anodized in an electrolyte solution has an increase in residual potential. It is less effective and has a high effect of preventing scumming when reversal development is used.

The anodizing treatment is performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid. Of these, treatment with a sulfuric acid bath is most suitable. For example, sulfuric acid concentration: 10 to 20%, bath temperature: 5 to 25 ° C., current density: 1 to 4 A / dm ² , electrolytic voltage: 5 to 30 V, treatment time: treatment in the range of about 5 to 60 minutes However, the present invention is not limited to this. Since the anodic oxide film produced in this way is porous and has high insulation, the surface is very unstable. For this reason, there is a change with time after fabrication, and the physical property value of the anodized film is likely to change. In order to avoid this, it is preferable to further seal the anodized film. Examples of the sealing treatment include a method of immersing the anodized film in an aqueous solution containing nickel fluoride and nickel acetate, a method of immersing the anodized film in boiling water, and a method of treating with pressurized steam. Among these, the method of immersing in the aqueous solution containing nickel acetate is the most preferable. Subsequent to the sealing treatment, the anodic oxide film is washed. The main purpose of this is to remove excess metal salts and the like attached by the sealing treatment. If this remains excessively on the surface of the support (anodized film), it not only adversely affects the quality of the coating film formed on this surface, but also generally low resistance components remain, resulting in the occurrence of soiling. It can also be a cause. Cleaning may be performed with pure water only once, but usually, multistage cleaning is performed. At this time, it is preferable that the final cleaning liquid is as clean as possible (deionized). Moreover, it is preferable to perform physical rubbing cleaning with a contact member in one of the multi-stage cleaning processes. The thickness of the anodized film formed as described above is preferably about 5 to 15 μm. If it is too thin, the barrier effect as an anodic oxide film is not sufficient, and if it is too thick, the time constant as an electrode becomes too large, resulting in the generation of residual potential and the response of the photoreceptor. There is a case.

<About photosensitive layer>
Next, the photosensitive layer will be described. The photosensitive layer in the present invention is formed by a laminated structure of a charge generation layer, a charge transport layer 1 and a charge transport layer 2.

<About the charge generation layer>
The charge generation layer is a layer mainly composed of a charge generation material. A known charge generation material can be used for the charge generation layer. For example, monoazo pigments, disazo pigments, asymmetrical disazo pigments, trisazo pigments, azo pigments having a carbazole skeleton (see, for example, Patent Document 20), azo pigments having a distyrylbenzene skeleton (see, for example, Patent Document 21), tri An azo pigment having a phenylamine skeleton (for example, see Patent Document 22), an azo pigment having a diphenylamine skeleton, an azo pigment having a dibenzothiophene skeleton (for example, see Patent Document 23), an azo pigment having a fluorenone skeleton (for example, Patent Document) 24), an azo pigment having an oxadiazol skeleton (see, for example, Patent Document 25), an azo pigment having a bis-stilbene skeleton (see, for example, Patent Document 26), an azo pigment having a distyryl oxadiazol skeleton (for example, , Patent Document 27), distyrylcarbazole Azo pigments such as azo pigments having a rating (see, for example, Patent Document 28), azulenium salt pigments, squaric acid methine pigments, perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenyl Methane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, indigoid pigments, bisbenzimidazole pigments, and phthalocyanine pigments such as metal phthalocyanines and metal-free phthalocyanines represented by the following general formula (6) Is mentioned.

  In the above formula (6), M (central element) represents a metal or non-metal (hydrogen) element. M (central element) mentioned here is H, Li, Be, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga , Ge, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, TI , La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, Pa, U, Np, Am, etc., or oxide, chloride It consists of two or more elements such as fluoride, fluoride, hydroxide and bromide. The central metal is not limited to these elements.

  The charge generation material having a phthalocyanine skeleton may have a multimeric structure such as a dimer or trimer, or may have a higher order polymer structure. In addition, the basic skeleton may have various substituents. Of these various phthalocyanines, titanyl phthalocyanine having TiO as a central metal, metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, and the like are particularly preferable in terms of photoreceptor characteristics. These phthalocyanines are known to have various crystal systems. For example, in the case of titanyl phthalocyanine, α, β, γ, m, Y type, etc., in the case of copper phthalocyanine, α, β, γ, etc. It has a polycrystal system. Even in the phthalocyanine having the same central metal, various characteristics change as the crystal system changes. It has been reported that the characteristics of photoreceptors using phthalocyanine pigments having these various crystal systems also change accordingly (Journal of Electrophotographic Society, Vol. 29, No. 4, 1990). Therefore, the selection of the phthalocyanine crystal system is very important in terms of the photoreceptor characteristics.

  Among these phthalocyanine pigments, a titanyl phthalocyanine crystal having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (1.542 °) of CuKα is particularly It has a high sensitivity and can be used particularly effectively in the present invention because it enables high-speed image formation. Further, among them, it has a maximum diffraction peak at 27.2 °, and further has main peaks at 9.4 °, 9.6 °, and 24.0 °, and the diffraction peak at the lowest angle side is 7.3. A titanyl phthalocyanine crystal having a peak at °, no peak between the peak at 7.3 ° and the peak at 9.4 °, and no peak at 26.3 ° has a charge generation efficiency. It can be used very effectively as a charge generating material of the present invention, such as being large, having good electrostatic properties, and being less likely to cause scumming. These charge generation materials can be used alone or as a mixture of two or more.

  The above-mentioned charge generating material contained in the electrophotographic photosensitive member of the present invention is effective because the effect may be enhanced by making the particle size finer. In particular, in the phthalocyanine pigment, the average particle size is preferably 0.25 μm or less, and more preferably 0.2 μm or less. As a method for controlling the particle size of the charge generation material contained in the charge generation layer, there is a method of removing coarse particles larger than 0.25 μm after dispersing the charge generation material, which is useful.

  Next, a method for removing coarse particles after dispersing the charge generation material will be described. That is, it is a method of preparing a dispersion with as fine a particle as possible and then filtering with a suitable filter. For the preparation of the dispersion, a general method is used, and the charge generating substance is obtained by dispersing it in a suitable solvent together with a binder resin, if necessary, using a ball mill, attritor, sand mill, bead mill, ultrasonic wave or the like. It is what At this time, the binder resin may be selected depending on the electrostatic characteristics of the photoreceptor, and the solvent may be selected depending on the wettability to the pigment, the dispersibility of the pigment, and the like.

  This method is a very effective means from the viewpoint that it can be observed visually (or cannot be detected by particle size measurement), can remove the remaining trace amount of coarse particles, and has a uniform particle size distribution. Specifically, the dispersion prepared as described above is filtered through a filter having an effective pore diameter of 5 μm or less, more preferably 3 μm or less, thereby completing the dispersion. Also by this method, a dispersion containing only a charge generating substance having a small particle size (0.25 μm or less, preferably 0.2 μm or less) can be prepared, and by using this, a static property such as sensitivity and chargeability can be obtained. The electric characteristics are improved and the effect can be sustained.

  At this time, when the particle size of the dispersion to be filtered is too large or the particle size distribution is too wide, the loss due to filtration becomes large or the filtration becomes clogged and filtration becomes impossible. There is a case. For this reason, in the dispersion before filtration, it is desirable to perform dispersion until the average particle size reaches 0.3 μm or less and the standard deviation reaches 0.2 μm or less. When the average particle size is 0.3 μm or more, the loss due to filtration increases, and when the standard deviation is 0.2 μm or more, there may be a problem that the filtration time becomes very long.

  The charge generation material has an extremely strong intermolecular hydrogen bonding force, which is a characteristic of charge generation materials exhibiting highly sensitive characteristics. For this reason, the interaction between the dispersed pigment particles is very strong. As a result, there is a great possibility that the charge generation material particles dispersed by a disperser or the like are re-aggregated by dilution or the like. Such agglomerates can be removed. At this time, since the dispersion is in a thixotropic state, particles having a size smaller than the effective pore size of the filter to be used are removed. Or the liquid which shows structural viscosity can also be changed into the state close | similar to Newton property by a filter process. In this way, by removing the coarse particles of the charge generation material, not only high sensitivity can be achieved, but it is also effective in reducing dirt and fog.

Among the azo pigments, azo pigments represented by the following general formula (7) are effectively used. In particular, an asymmetric disazo pigment in which Cp ₁ and Cp ₂ of the azo pigment are different from each other has a large carrier generation efficiency and is effective for speeding up, and is preferably used as the charge generation material of the present invention.

In the above formula (7), Cp ₁ and Cp ₂ represent coupler residues. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, and may be the same or different. Cp ₁ and Cp ₂ are represented by the following general formula (7a), and an asymmetric disazo pigment can be obtained by giving different structures to each other.

In the above formula (7a), R ₂₀₃ represents a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group. R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ and R ₂₀₈ are each a hydrogen atom, a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine or iodine, a halogenated alkyl group such as a trifluoromethyl group, methyl Represents an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, a dialkylamino group or a hydroxyl group, and Z represents a substituted or unsubstituted carbocyclic aromatic group or an aromatic carbocyclic ring or a substituted or unsubstituted group. Heteroaromatic group represents a group of atoms necessary for constituting an aromatic heterocycle. These charge generation materials may be used alone or in combination of two or more.

  The binder resin used as necessary for the charge generation layer includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, Poly-N-vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone Etc. Among these, polyvinyl butyral is preferably used. These binder resins can be used alone or as a mixture of two or more.

  Moreover, as a solvent to be used, generally used organic materials such as isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin, etc. Among them, it is preferable to use a ketone solvent, an ester solvent, or an ether solvent. These may be used alone or in combination of two or more.

  The charge generation layer is obtained by dispersing the charge generation material in a solvent using a known dispersion method such as a ball mill, an attritor, a sand mill, a bead mill, or an ultrasonic wave together with a binder resin as necessary. Can do. The binder resin may be added before or after the charge generating material is dispersed. The coating solution for the charge generation layer is mainly composed of a charge generation material, a solvent, and a binder resin, and it contains additives such as a sensitizer, a dispersant, a surfactant, and silicone oil. May be. In some cases, it is also possible to add a charge transport material described later to the charge generation layer. The addition amount of the binder resin is usually 0 to 500 parts by mass, preferably 10 to 300 parts by mass with respect to 100 parts by mass of the charge generating material.

  The charge generation layer is formed by coating on a conductive support or an undercoat layer using the coating solution and drying. As the coating method, known methods such as dip coating, spray coating, bead coating, nozzle coating, spinner coating, ring coating, and the like can be used. The film thickness of the charge generation layer is usually about 0.01 to 5 μm, preferably 0.1 to 2 μm. Further, drying after coating is performed by heating using an oven or the like. The drying temperature of the charge generation layer is preferably 50 to 160 ° C, more preferably 80 to 140 ° C.

<About the charge transport layer>
The charge transport layer in the present invention is formed by a laminated structure of the charge transport layer 1 and the charge transport layer 2. The charge transport layer 1 (CTL1) and the charge transport layer 2 (CTL2) in the present invention are different from each other in the charge transport material contained in the charge transport layer, and the oxidation potential Eox ( Any configuration is acceptable as long as CTL1) and oxidation potential Eox (CTL2) of charge transport layer 2 (CTL2) satisfy the following formula.
Eox (CTL1) <0.705 (V vs. SCE) <Eox (CTL2)
For example, even if the charge transport layer 1 and the charge transport layer 2 are not completely separated from each other, or in the interface region between the charge transport layer 1 and the charge transport layer 2, there are regions where the respective charge transport materials are mixed. Even if it is made, the oxidation potential of the charge transport material in the charge transport layer 1 formed on the charge generation layer side and the oxidation potential of the charge transport material in the charge transport layer 2 formed on the cross-linked cross-linked charge transport layer side However, if the above formula is satisfied, the effects of the present invention can be obtained, and thus all are included in the present invention.

The charge transport layer including the charge transport layer 1 and the charge transport layer 2 in the present invention will be described below.
The charge transport layer in the present invention contains a charge transport material and a binder resin as main components. As the charge transport material, a hole transport material is used.

  Specific charge transport materials include poly (N-vinylcarbazole) and derivatives thereof, poly (γ-carbazolylethyl glutamate) and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, and polysilane. , Oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, aminobiphenyl derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives , Divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., distyrylbenzene derivatives, enamine derivatives, or polymer charges Examples include transport materials. These charge transport materials may be used alone or in combination of two or more.

  In the present invention, among the above charge transport materials, charge transport materials having a triarylamine structure are effective. Among these, a charge transport material represented by the following general formula (1) is particularly effective. These charge transport materials have a relatively large molecular structure and are characterized by the fact that the π-conjugated system spreads throughout the molecule. is there.

［上式（１）中、Ｒ_１〜Ｒ_４は、それぞれ、水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、フェニル基のいずれかを表し、各々同一でも異なっていても良い。フェニル基は無置換のものでも良いし、炭素数１〜４のアルキル基や炭素数１〜４のアルコキシ基を置換基として有していても良い。
Ａは、置換もしくは無置換のアリーレン基、または下記一般式（１ａ）で表される基を表す。

（上式（１ａ）中、Ｒ_５、Ｒ_６及びＲ_７は、それぞれ、水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、フェニル基を表し、フェニル基の場合は無置換でも良いし、炭素数１〜４のアルキル基や炭素数１〜４のアルコキシ基を置換基として有していても良い。）
Ｂ及びＢ’は、それぞれ、置換もしくは無置換のアリール基、または下記一般式（１ｂ）で表される基を表す。Ｂ及びＢ’は、同一であっても異なっていても良い。

（上式（１ｂ）中、Ａｒ_１はアリーレン基を表わし、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。また、Ａｒ_２及びＡｒ_３は、それぞれアリール基を表し、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。）
但し、Ａ、Ｂ及びＢ’の少なくとも一つにトリアリールアミン構造を有する。］

[In the above formula (1), R _{1 to} R ₄ each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group. May be. The phenyl group may be unsubstituted, or may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms as a substituent.
A represents a substituted or unsubstituted arylene group or a group represented by the following general formula (1a).

(In the above formula (1a), R ₅ , R ₆ and R ₇ each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group. May be unsubstituted or may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms as a substituent.)
B and B ′ each represent a substituted or unsubstituted aryl group or a group represented by the following general formula (1b). B and B ′ may be the same or different.

(In the above formula (1b), Ar ₁ represents an arylene group and may have an alkyl group or alkoxy group having 1 to 4 carbon atoms as a substituent. Ar ₂ and Ar ₃ are each an aryl group. And may have a C 1-4 alkyl group or alkoxy group as a substituent.
However, at least one of A, B and B ′ has a triarylamine structure. ]

  As an example, a distyryl compound represented by the following general formula (8) is particularly effective, effective and useful in the present invention.

上式（８）中、Ｒ_８〜Ｒ_３３は水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、置換もしくは無置換のフェニル基を表わし、それぞれ同一でも異なっていてもよい。

In the above formula (8), R _{8 to} R ₃₃ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group, and they may be the same or different. Also good.

  In addition, a charge transport material represented by the following general formula (9) is also effective in the present invention.

上式（９）中、Ｒ_３４〜Ｒ_５７は水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、置換もしくは無置換のフェニル基を表わし、それぞれ同一でも異なっていてもよい。

In the above formula (9), R _{34 to} R ₅₇ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group, and they may be the same or different. Also good.

[上式中、Ａｒ_４、Ａｒ_５、Ａｒ_７、Ａｒ_８は水素原子、炭素数１〜４のアルキル基やアルコキシ基、アリール基を表わし、アリール基の場合は炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。また、Ａｒ_６はアリーレン基を表し、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。Ｒ_８は、水素原子、炭素数１〜４のアルキル基や炭素数１〜４のアルコキシ基を表す。また、ｎは０または１の整数を表す。] In addition, a charge transport material represented by the following general formula (2) is also very effective in the present invention.

[In the above formula, Ar ₄ , Ar ₅ , Ar ₇ , Ar ₈ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or an aryl group, and in the case of an aryl group, an alkyl group having 1 to 4 carbon atoms] Or an alkoxy group as a substituent. Ar ₆ represents an arylene group and may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. R ₈ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. N represents an integer of 0 or 1. ]

As an example, an α-phenylstilbene compound represented by the following general formula (10) is particularly effective in the present invention, and is effective and useful.

In the above formula (10), R _{58 to} R ₇₈ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group, and they may be the same or different. Also good.

[上式中、Ａｒ_９、Ａｒ_１０はアリール基を表わし、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。また、Ａｒ_１１はアリーレン基を表し、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。Ｘは置換もしくは無置換のアリール基、または下記一般式（３ａ）で表される基を表す。]

[上式中、Ａｒ_１２、Ａｒ_１３はアリール基を表わし、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。また、Ａｒ_１４はアリーレン基を表し、炭素数１〜４のアルキル基やアルコキシ基を置換基として有していても良い。] In addition, a charge transport material represented by the following general formula (3) is also very effective in the present invention.

[In the above formula, Ar ₉ and Ar ₁₀ represent an aryl group, which may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. Ar ₁₁ represents an arylene group and may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. X represents a substituted or unsubstituted aryl group, or a group represented by the following general formula (3a). ]

[In the above formula, Ar ₁₂ and Ar ₁₃ represent an aryl group, which may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. Ar ₁₄ represents an arylene group and may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. ]

As an example, a benzidine compound and an aminobiphenyl compound represented by the following general formula (11) are particularly effective, effective and useful in the present invention.

In the above formula (11), R _{79 to} R ₁₀₀ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group, and they may be the same or different. Also good.

In the above formula (12), R _{101 to} R _{116 each} represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group, and they may be the same or different. Also good.

Among these charge transport materials, compounds having a molecular weight in the range of 300 or more and 800 or less are particularly effective in the present invention. When a charge transport layer or a cross-linked charge transport layer is laminated, the charge transport material contained in the lower layer may ooze out into the upper layer. If the leaching is moderate, an effect may be obtained for reducing the residual potential, but if the leaching is large, the effect of the present invention may be reduced. In particular, it is not preferable that a large amount of the charge transport material contained in the charge transport layer 1 having a low oxidation potential leaks into the charge transport layer 2 because the effect of suppressing image blur is reduced. The molecular weight of the charge transporting material preferable for obtaining the effect of the present invention with little leaching into the upper layer is in the range of 300 or more and 800 or less, and more preferably in the range of 450 or more and 750 or less. .
If the molecular weight is larger than this, the leaching of the charge transport material into the upper layer is further reduced, but the solubility is lowered, and it may be precipitated as crystals or cracks may occur. On the other hand, if the molecular weight is smaller than this, the influence of oozing into the upper layer increases, and the image blur suppression effect may be reduced.

  Specific examples of these compounds used as charge transport materials in the present invention are shown below. However, these are merely examples, and the present invention is not limited to these specific examples.

As described above, the charge transport layer in the present invention is formed by the laminated structure of the charge transport layer 1 and the charge transport layer 2, and the charge transport layer 1 contains a charge transport material having an oxidation potential Eox (CTL1), 2 needs to contain a charge transport material having an oxidation potential Eox (CTL2) and satisfy the following formula.
Eox (CTL1) <0.705 (V vs. SCE) <Eox (CTL2)

The oxidation potential of the charge transport material can be measured as follows.
A charge transport material to be measured is dissolved by adding a predetermined amount of acetonitrile and an irrelevant salt (supporting electrolyte) such as tetrabutylammonium perchlorate or tetraethylammonium perchlorate to obtain a test solution. This test solution is measured for the oxidation potential of the target substance by an electrochemical analysis means such as polarograph or cyclic voltammetry. Regarding the electrochemical analysis, A.I. J. et al. Bard, L .; R. He is familiar with books such as “Electrochemical Methods” by Faulkner published in 1980 by Wiley. In the present invention, a dropping mercury electrode is used as a working electrode, platinum is used as a counter electrode, a saturated sweet potato electrode (SCE) is used as a reference electrode, and measurement is performed by a potential scanning method using a potentiostat.

  Examples of the binder resin for the charge transport layer include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, poly Vinyl acetate, polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly (N-vinylcarbazole), acrylic resin, silicone resin, epoxy resin, melamine resin And thermoplastic or thermosetting resins such as urethane resin, phenol resin, and alkyd resin. Among these, polycarbonate and polyarylate are preferably used.

  The content of the charge transport material is usually 20 to 300 parts by mass and preferably 40 to 150 parts by mass with respect to 100 parts by mass of the binder resin. It is also possible to use two or more kinds of charge transport materials or a mixture of two or more binder resins.

  As the solvent used as the coating solution for the charge transport layer, tetrahydrofuran, dioxane, dioxolane, toluene, cyclohexanone, cyclopentanone, methyl ethyl ketone, xylene, acetone, diethyl ether, methyl ethyl ketone and the like are used. Of these, tetrahydrofuran, toluene, xylene, cyclopentanone, and the like are preferably used as solvents that are effectively used. These may be used singly or in combination of two or more.

  Moreover, you may add additives, such as a plasticizer, a leveling agent, antioxidant, a lubricant, etc. individually or in 2 types or more to the coating liquid of a charge transport layer as needed. Addition of the plasticizer has an effect of improving the gas resistance of the charge transport layer and preventing the occurrence of cracks. As an example of the plasticizer, plasticizers such as dibutyl phthalate and dioctyl phthalate can be used and are effective. As addition amount, 0-30 mass% is preferable with respect to binder resin, and 1-10 mass% is more preferable. Addition of an antioxidant is effective in suppressing dark portion potential reduction, improving gas resistance, and suppressing image blur. As an example of the antioxidant, conventionally known materials such as phenol compounds, paraphenylenediamines, hydroquinones, organic sulfur compounds, organic phosphorus compounds, hindered amines and the like can be used. By adding a leveling agent, the film quality of the charge transport layer is improved and the occurrence of coating film defects can be prevented. Further, the film thickness unevenness is reduced, and a smooth film can be obtained. As an example of the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers having a perfluoroalkyl group in the side chain, oligomers and the like are used, and the amount used is 0 to 1 with respect to the binder resin. % By mass is preferable, and 0.01% by mass to 0.5% by mass is more preferable.

  As a method for coating the charge transport layer, known methods such as dip coating, spray coating, bead coating, nozzle coating, spinner coating, and ring coating can be used, and among these, dip coating is more preferable. After coating, it is manufactured by drying with the touch and then heating and drying in an oven or the like. Although the drying temperature of a charge transport layer changes with kinds of solvent contained in the coating liquid of a charge transport layer, it is preferable that it is 80-150 degreeC, and 100-140 degreeC is more preferable. The thickness of the charge transport layer thus obtained is usually 10 to 50 μm, and more preferably 15 to 35 μm.

<About the cross-linked charge transport layer>
Next, the crosslinkable charge transport layer will be described. Crosslinked charge transporting layer in the present invention, Ri Do a cured product of the polymerizable compound and the polymerizable compound having no charge transport structure having at least a charge transport structure, the polymerizable compound having a charge transport structure The oxidation potential of is not less than 0.750 (V vs. SCE) and not more than 0.850 (V vs. SCE) .

  Next, the binder resin for the crosslinkable charge transport layer will be described. Any resin can be used as the binder resin of the crosslinkable charge transport layer as long as it is cured. For example, phenol resin, epoxy resin, melamine resin, alkyd resin, urethane resin, amino resin, polyimide resin, siloxane resin, acrylic resin, etc. are mentioned, and urethane resin, phenol resin, acrylic / methacrylic resin, siloxane resin are particularly suitable. Used.

  As described above, the crosslinkable charge transport layer of the present invention is formed by curing a polymerizable compound having a charge transporting structure and a polymerizable compound having no charge transporting structure. Thereby, the charge transport performance of the electrophotographic photosensitive member can be maintained without impairing the wear resistance and scratch resistance. Polymerization refers to the former polymerization reaction form in which the formation reaction of the polymer compound is largely divided into chain polymerization and sequential polymerization, and the form is mainly reacted via an intermediate such as radical or ion. It refers to proceeding unsaturated polymerization, ring-opening polymerization, isomerization polymerization and the like. Moreover, a polymeric compound means the compound which has a functional group in which the said reaction form is possible. In general, curing means that monomers and oligomers having the above functional groups are bonded (for example, shared) between molecules by applying energy such as heat, light such as visible light or ultraviolet light, radiation such as electron beams and γ rays. Reaction) to form a three-dimensional network structure.

  Examples of the curable resin include a thermosetting resin that is polymerized by heat, a photocurable resin that is polymerized by light such as ultraviolet rays and visible light, an electron beam curable resin that is polymerized by an electron beam, and a curing agent as necessary. Or a catalyst, a polymerization initiator, or the like.

  In order to obtain a cross-linked charge transport layer, it is necessary that a polymerizable compound (for example, a monomer or an oligomer) has a functional group that causes a polymerization reaction. As the functional group, any functional group that causes a polymerization reaction can be used, but generally, an unsaturated polymerizable functional group or a ring-opening polymerizable functional group is known. This is also effective in the invention. The unsaturated polymerizable functional group is a reaction in which an unsaturated group is polymerized by radicals or ions. For example, a functional group such as C═C, C≡C, C═O, C═N, C≡N Can be mentioned. A ring-opening polymerizable functional group is a reaction in which an unstable cyclic structure having a strain such as a carbocyclic ring, an oxo ring, or a nitrogen heterocycle repeats polymerization at the same time as the ring opening to generate a chain polymer. Most of these act as active species.

  Examples of these include groups having a carbon-carbon double bond such as acryloyl group, methacryloyl group and vinyl group, groups that cause ring-opening polymerization such as silanol group and cyclic ether group, or reaction of two or more kinds of molecules. Things. Further, in the curing reaction, the larger the number of functional groups in one molecule of the reactive monomer, the stronger the three-dimensional network structure becomes, and the trifunctional or higher functionality is particularly effective. As a result, the curing density is increased, the hardness is high, the elasticity is high, the uniformity is uniform, and the smoothness is improved. This is effective for improving the durability and image quality of the electrophotographic photosensitive member.

  The crosslinkable charge transport layer in the present invention is composed of a cured product of a polymerizable compound having no charge transport structure and a polymerizable compound having a charge transport structure. Conventionally known materials can be used for them. High effects can be obtained regardless of the material and means. In the present invention, among many curable resins, acrylic / methacrylic resins can be used satisfactorily because they are strong in wear resistance and scratch resistance, have good electrostatic characteristics, and easily obtain the effects of the present invention. Note that these cross-linked charge transport layers have a three-dimensional network structure and are insoluble in organic solvents. Therefore, in the present invention, the state in which the curable resin is cured can be determined to be cured if, for example, the film does not dissolve even when an alcohol-based organic solvent is attached.

  When the crosslinked charge transport layer is cured, a three-dimensionally developed network structure is formed by a curing reaction between the polymerizable compound having no charge transporting structure and the polymerizable compound having the charge transporting structure. In this case, it is possible to further increase the degree of curing by previously mixing a curing agent, a catalyst, a polymerization initiator and the like, which is particularly effective in the present invention. As a result, the wear resistance and scratch resistance of the cross-linked charge transport layer are further improved, and unreacted functional groups are less likely to remain, which is effective in improving wear resistance and suppressing deterioration of electrostatic characteristics. In addition, since the reaction is uniform, cracks and distortions are less likely to occur, and the cleaning property can be improved. For example, it is possible to obtain high effects for improving the durability and image quality of the photoreceptor.

  On the other hand, the polymerizable compound having a charge transporting structure is not particularly limited as long as it has a structure exhibiting charge transporting properties and has a functional group for reacting with the curable resin, and a conventionally known material is used. be able to. The charge transporting structure is a structure contained in the charge transporting substance, and thereby refers to a structure that expresses the charge transporting property. The charge transport structure is mainly classified into a structure that transports holes and a structure that transports electrons, and both are included in the present invention.

  There may be one or more charge transporting structures, that is, a hole transporting structure or an electron transporting structure in the compound, and a plurality of structures are more preferable because of excellent charge transporting properties. Alternatively, the reactive compound having a charge transporting structure may have a bipolar property in which both a hole transporting structure and an electron transporting structure are included in the molecule.

  Among the charge transport structures, examples of the hole transport structure include poly-N-vinyl carbazole, poly-γ-carbazolyl ethyl glutamate, pyrene-formaldehyde condensate, polyvinyl pyrene, polyvinyl phenanthrene, polysilane, oxazole, oxa Diazole, imidazole, monoarylamine, diarylamine, triarylamine, stilbene, α-phenylstilbene, benzidine, diarylmethane, triarylmethane, 9-styrylanthracene, pyrazoline, divinylbenzene, hydrazone, indene, butadiene, pyrene, Examples of the structure generally show electron donating properties such as bisstilbene and enamine.

On the other hand, examples of the electron transporting structure include chloroanil, bromoanil, 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-trinitrodibenzothiophene-5,5-dioxide, condensed polycyclic quinone, diphenoquinone, benzoquinone, naphthalenetetracarboxylic acid diimide, aromatic ring having cyano group or nitro group, etc. Can be mentioned.
In the present invention, the most preferable charge transporting structure of the polymerizable compound having these charge transporting structures is a triarylamine structure, whereby an effect of suppressing an increase in potential of the exposed portion is obtained. This is effective in reducing the increase in potential of the exposed area.

Next, the acrylic resin will be described in detail as an example of the curable resin.
The polymerizable compound having no charge transporting property used in the present invention has a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano group or nitro group. It is a compound having no electron transporting structure such as an electron-withdrawing aromatic ring and having a polymerizable functional group. The polymerizable functional group may be any group as long as it has a carbon-carbon double bond and can be polymerized. Examples of these polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.
As the 1-substituted ethylene functional group, for example, a functional group represented by the following general formula (13) is preferably exemplified.

(In the general formula (13), X ₁ is an arylene group such as a phenylene group or a naphthylene group which may have a substituent, an alkenylene group which may have a substituent, or a —CO— group. , —COO— group, —CON (R ₃₀ ) — group (wherein R ₃₀ is a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, an aralkyl group such as a benzyl group, a naphthylmethyl group or a phenethyl group, a phenyl group) , Represents an aryl group such as a naphthyl group), or represents an —S— group.
Specific examples of these substituents include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamide group, and a vinyl thioether group.

  As the 1,1-substituted ethylene functional group, for example, a functional group represented by the following general formula (14) is preferably exemplified.

(However, in the said General formula (14), Y is the alkyl group which may have a substituent, the aralkyl group which may have a substituent, the phenyl group which may have a substituent, An aryl group such as a naphthyl group, a halogen atom, a cyano group, a nitro group, an alkoxy group such as a methoxy group or an ethoxy group, and —COOR ₃₁ group (where R ₃₁ is a hydrogen atom or a methyl group optionally having a substituent) Group, an alkyl group such as an ethyl group, an optionally substituted benzyl, an aralkyl group such as a phenethyl group, an optionally substituted phenyl group, an aryl group such as a naphthyl group) or -CONR _{32 R} 33 _(provided that, R ₃₂ and R ₃₃ are hydrogen atoms, 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 aralkyl groups such as phenethyl group, or a substituent a phenyl group which may have a represents an aryl group such as a naphthyl group, may be the same or different from each other.) Further, X ₂ is the formula ( 13) represents the same substituent as X ₁ , a single bond, and an alkylene group, provided that at least one of Y and X ₂ is an oxycarbonyl group, a cyano group, an alkenylene group, and an aromatic ring.

Examples of these substituents include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.
In addition, examples of the substituent further substituted with the substituent for X ₁ , X ₂ , and Y include, for example, a halogen atom, a nitro group, a cyano group, a methyl group, an alkyl group such as 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 radical polymerizable functional groups, acryloyloxy group and methacryloyloxy group are particularly useful.

  The number of functional groups of the polymerizable compound (monomer or oligomer) having no charge transporting structure is preferably more multifunctional, and more preferably trifunctional or more. When a tri- or higher functional polymerizable monomer is cured, a three-dimensional network structure develops, and a high hardness and high elasticity layer with a very high crosslink density is obtained, and it is uniform and has high smoothness and high wear resistance. Scratch resistance is achieved. However, depending on the curing conditions and the materials used, a large number of bonds are instantaneously formed in the curing reaction, so that internal stress due to volume shrinkage occurs, and cracks and film peeling may easily occur. In that case, it may be improved by using a monofunctional or bifunctional polymerizable monomer, or by mixing them.

Hereinafter, a polymerizable compound having no tri- or higher functional charge transport structure effective for improving the wear resistance will be described.
A compound having 3 or more acryloyloxy groups may be subjected to an ester reaction or a transesterification reaction using, for example, a compound having 3 or more hydroxyl groups in the molecule and acrylic acid (salt), acrylic acid halide, or acrylic ester. Can be obtained. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

Specific examples of the trifunctional or higher functional polymerizable compound (a) having no charge transporting structure include the following, but are not limited to these compounds.
Examples of the radical polymerizable compound (A) used in the present invention include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, HPA-modified (alkylene-modified) trimethylolpropane triacrylate, EO-modified (ethyleneoxy-modified). ) Trimethylolpropane triacrylate, PO modified (propyleneoxy modified) trimethylolpropane triacrylate, caprolactone modified trimethylolpropane triacrylate, HPA modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol Triacrylate, ECH-modified (epichlorohydrin-modified) glycerol triacrylate , EO-modified glycerol triacrylate, PO-modified glycerol triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkyl-modified di Pentaerythritol pentaacrylate, alkyl-modified dipentaerythritol tetraacrylate, alkyl-modified dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, EO-modified phosphate triacrylate, 2, 2, 5, 5 , -Tetrahydroxymethylcyclopentanone tetraacrylate etc. The recited, it can be used in combination either alone or in combination. The reason for the modification is to reduce the viscosity of these compounds and make them easier to handle.

  The polymerizable compound (a) having no charge transporting structure used in the present invention has a molecular weight ratio (molecular weight / weight) to the number of functional groups in the monomer in order to form a dense crosslink in the crosslinkable charge transport layer. The number of functional groups) is preferably 250 or less. Further, when this ratio is larger than 250, the crosslinked surface layer is soft and wear resistance is somewhat lowered. Therefore, among the compounds exemplified above, monomers having a modifying group such as HPA, EO, and PO are extremely long. It is not preferable to use one having a modifying group alone.

  The component ratio of the polymerizable compound (a) having no charge transporting structure used in the crosslinkable charge transport layer is 20 to 80% by mass, preferably 30 to 70% by mass with respect to the total amount of the crosslinkable charge transport layer. When the monomer component is less than 20% by mass, the three-dimensional cross-linking density of the cross-linked surface layer is small, and a drastic improvement in wear resistance is not achieved as compared with the case where a conventional thermoplastic binder resin is used. On the other hand, if it exceeds 80% by mass, the content of the charge transporting compound is lowered and the electrical characteristics are deteriorated. Since the required wear resistance and electrical characteristics differ depending on the process used, it cannot be said unconditionally, but considering the balance of both characteristics, the range of 30 to 70% by mass is most preferable.

Next, the polymerizable compound having a charge transporting structure will be described.
The polymerizable compound (b) having a charge transporting structure used in the present invention is a hole transporting structure such as a triarylamine structure, a hydrazone structure, a pyrazoline structure, or a carbazole structure, such as a condensed polycyclic quinone, diphenoquinone, or cyano. A compound having an electron transport structure such as an electron-withdrawing aromatic ring having a group or a nitro group and having a radical polymerizable functional group. Examples of the radical polymerizable functional group include those previously shown for the radical polymerizable compound, and acryloyloxy group and methacryloyloxy group are particularly useful.

  Any number of functional groups can be used as the polymerizable compound having a charge transporting structure used in the cross-linked charge transport layer of the present invention. It is more preferable from the point. In the case of bifunctional or higher, a plurality of bonds are fixed in the cross-linked structure and the cross-link density is further increased. Become. In addition, the intermediate structure (cation radical) at the time of charge transport cannot be kept stable, and there is a risk that a decrease in sensitivity due to charge trapping and an increase in residual potential are likely to occur.

  As the charge transporting structure of the polymerizable compound having a charge transporting structure, any material can be used as long as it can provide a charge transporting function. Among them, the triarylamine structure is highly effective and useful. . For example, when a compound represented by the structure represented by the following general formula (4) or (5) is used, the exposure portion potential increase is reduced, and the influence of image blurring on the oxidizing gas can be reduced.

In general formulas (4) and (5), R ₁ may have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Aryl group, cyano group, nitro group, alkoxy group, —COOR ₂ (R ₂ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. An aryl group), a carbonyl halide group or CONR ₃ R ₄ (R ₃ and R ₄ are a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or Represents an aryl group which may have a substituent and may be the same or different from each other), Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, and may be the same or different May be. Ar _{3 and} Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group, and Z represents a substituted or unsubstituted alkylene. Represents a group, a substituted or unsubstituted alkylene ether group or an alkyleneoxycarbonyl group, and m and n each represents an integer of 0 to 3;

In the general formulas (4) and (5), examples of the alkyl group in R ₁ include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. As benzyl group, phenethyl group, naphthylmethyl group, and alkoxy groups include methoxy group, ethoxy group, propoxy group, etc., which are halogen atom, nitro group, cyano group, methyl group, ethyl group, respectively. May be substituted with an alkyl group such as methoxy group, ethoxy group, etc., aryloxy group such as phenoxy group, aryl group such as phenyl group, naphthyl group, aralkyl group such as benzyl group, phenethyl group, etc. . Particularly preferred among R ₁ are a hydrogen atom and a methyl group.

In the general formulas (4) and (5), Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group. In the present invention, the aryl group includes a condensed polycyclic hydrocarbon group, a non-condensed cyclic hydrocarbon group, and a heterocyclic group, and includes the following groups.

  The condensed polycyclic hydrocarbon group preferably has 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an As-indacenyl group, s-indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group, Examples include a chrycenyl group and a naphthacenyl group.

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

  Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

In the general formulas (4) and (5), the aryl group represented by Ar ₃ or Ar ₄ may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group and the like.
(2) An alkyl group.
Preferably, it is a C ₁ -C _12, especially C ₁ -C ₈ , more preferably a C ₁ -C ₄ linear or branched alkyl group, and these alkyl groups further include a fluorine atom, a hydroxyl group, a cyano group , _C 1 -C ₄ alkoxy group which may have a phenyl group or a halogen _atom, C 1 -C ₄ alkyl or C ₁ -C ₄ phenyl group substituted with an alkoxy group. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-ethoxyethyl Group, 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group and the like.
(3) an alkoxy group _(-OR a).
R _a represents an alkyl group defined in (2) above. Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group And a trifluoromethoxy group.

(4) Aryloxy group.
Examples of the aryl group include a phenyl group and a naphthyl group. It _may contain an alkoxy group having C 1 -C _4, alkyl group, or a halogen atom C 1 -C ₄ as a substituent. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.
(5) Alkyl mercapto group or aryl mercapto group.
Specific examples include a methylthio group, an ethylthio group, a phenylthio group, and a p-methylphenylthio group.
(6) A group represented by the following general formula (15).

In the formula, R ₁₀ and R ₁₁ each independently represent a hydrogen atom, an alkyl group defined in (2) above, or an aryl group. Examples of the aryl group include a phenyl group, biphenyl group or a naphthyl group, and these may contain an alkoxy group of C ₁ -C _4, alkyl group, or a halogen atom C ₁ -C ₄ as a substituent. R ₁₀ and R ₁₁ may jointly form a ring.
Specifically, amino group, diethylamino group, N-methyl-N-phenylamino group, N, N-diphenylamino group, N, N-di (tolyl) amino group, dibenzylamino group, piperidino group, morpholino group And pyrrolidino group.

(7) An alkylenedioxy group or an alkylenedithio group such as a methylenedioxy group or a methylenedithio group.
(8) A substituted or unsubstituted styryl group, a substituted or unsubstituted β-phenylstyryl group, a diphenylaminophenyl group, a ditolylaminophenyl group, and the like.

In the general formulas (4) and (5), 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 .
In the general formulas (4) and (5), X is a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or vinylene. Represents a group.

The alkylene group for X is a C _{1 to} C ₁₂ , preferably C _{1 to} C ₈ , more preferably a C _{1 to} C ₄ linear or branched alkylene group. fluorine atom, a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, have a phenyl group substituted with an alkyl group or a _C 1 -C ₄ alkoxy group C 1 -C ₄ May be. Specifically, methylene group, ethylene group, n-butylene group, i-propylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxyethylene. Group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group and the like.

The cycloalkylene group in X is a C _{5 to} C ₇ cyclic alkylene group, and these cyclic alkylene groups include a fluorine atom, a hydroxyl group, a C _{1 to} C ₄ alkyl group, and a C _{1 to} C ₄ alkoxy group. And the like. Specific examples of the cycloalkylene group include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.

The alkylene ether group in X represents ethyleneoxy, propyleneoxy, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, tripropylene glycol, and the alkylene group of the alkylene ether group includes a hydroxyl group, a methyl group, an ethyl group, and the like. You may have a substituent.
The vinylene group in X is represented by the following two general formulas.

However, in the above formula _{(16), R 12} represents hydrogen, an alkyl group [wherein the same as the alkyl group, as defined (2)], an aryl group (same as the aryl group represented by _Ar 3, Ar _4), a Represents 1 or 2, and b represents 1-3.

  In the above formulas (4) and (5), Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, or an alkyleneoxycarbonyl group. Examples of the substituted or unsubstituted alkylene group include the same alkylene groups as those described above for X. Examples of the substituted or unsubstituted alkylene ether divalent group include the divalent group of the alkylene ether of X. Examples of the alkyleneoxycarbonyl divalent group include a caprolactone-modified divalent group.

  More preferably, the polymerizable compound (b) having a charge transport structure of the present invention includes a compound having the structure of the following general formula (17).

のいずれかを表す。 In the formula (17), o, p and q are each an integer of 0 or 1, R ₅ represents a hydrogen atom or a methyl group, and R ₆ and R ₇ are a substituent other than a hydrogen atom and an alkyl having 1 to 6 carbon atoms. Represents a group, and a plurality of groups may be different. s and t represent an integer of 0 to 3. Z ₂ is a single bond, a methylene group, an ethylene group, or

Represents one of the following.

As the compound represented by the general formula (17), compounds having a methyl group or an ethyl group are particularly preferable as substituents for R ₆ and R ₇ .

  The polymerizable compound (b) having the charge transport structure represented by the general formulas (4) and (5), particularly (17), used in the present invention is polymerized by opening a carbon-carbon double bond on both sides. Therefore, in the polymer that does not become a terminal structure, is incorporated in the chain polymer, and is crosslinked by polymerization with a tri- or higher functional radical polymerizable monomer, it exists in the main chain of the polymer, and It exists in the cross-linked chain between the main chain and the main chain (this cross-linked chain includes an intermolecular cross-linked chain between one polymer and another polymer, and a main chain folded in one polymer. There is an intramolecular cross-linked chain that crosslinks a certain site and another site derived from the polymerized monomer at a position away from this in the main chain). Even if present in the chain, the triarylamine structure suspended from the chain moiety It has at least three aryl groups arranged in the radial direction from and is bulky, but it is not directly bonded to the chain part and is suspended from the chain part via a carbonyl group, etc. Since these triarylamine structures can be arranged adjacent to each other in the polymer, the structural distortion in the molecule is small, and the electrophotographic photosensitive member has a small amount of structural distortion. In the case of a surface layer, it is presumed that an intramolecular structure that is relatively free from interruption of the charge transport pathway can be taken.

  In the present invention, the specific acrylic ester compound represented by the following general formula (19) can also be favorably used as the radical polymerizable compound (b) having a charge transporting structure.

In the above formula (19), Ar ₅ represents a monovalent group or a divalent group composed of a substituted or unsubstituted aromatic hydrocarbon skeleton. Examples of the aromatic hydrocarbon skeleton include benzene, naphthalene, phenanthrene, biphenyl, 1,2,3,4-tetrahydronaphthalene and the like. Examples of the substituent include an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a benzyl group, and a halogen atom. The alkyl group and alkoxy group may further have a halogen atom or a phenyl group as a substituent.

In the above formula (19), Ar ₆ is a monovalent group or divalent group comprising an aromatic hydrocarbon skeleton having at least one tertiary amino group, or a heterocyclic group having at least one tertiary amino group. A monovalent group or a divalent group composed of a compound skeleton is represented. Here, the aromatic hydrocarbon skeleton having a tertiary amino group is represented by the following general formula (20).

In the above formula (20), R ₁₃ and R ₁₄ represent an acyl group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Ar ₇ represents an aryl group. w represents an integer of 1 to 3.
Examples of the acyl group for R ₁₃ and R ₁₄ include an acetyl group, a propionyl group, and a benzoyl group. The substituted or unsubstituted alkyl group for R ₁₃ and R ₁₄ is the same as the alkyl group described for the substituent for Ar ₅ in the above formula (19).
The substituted or unsubstituted aryl group of R ₁₃ and R ₁₄ is a phenyl group, a naphthyl group, a biphenylyl group, a terphenylyl group, a pyrenyl group, a fluorenyl group, a 9,9-dimethyl-2-fluorenyl group, an azulenyl group, an anthryl group, In addition to the triphenylenyl group and the chrysenyl group, a group represented by the following general formula (21) can be exemplified.

In the above formula (21), B is selected from —O—, —S—, —SO—, —SO ₂ —, —CO— and a divalent group represented by the following formula (22).

Here, in formula (21), R ₂₁ represents a hydrogen atom, a substituted or unsubstituted alkyl group defined by Ar ₅ in the above formula (19), an alkoxy group, a halogen atom, R ₁₃ in the above formula (20). Represents a substituted or unsubstituted aryl group, amino group, nitro group, or cyano group defined in formula (22), wherein in formula (22), R ₂₂ represents a hydrogen atom, a substituent defined by Ar ₅ in formula (19) or An unsubstituted alkyl group, a substituted or unsubstituted aryl group defined by R ₁₃ in the above formula (20), i represents an integer of 1 to 12, and j represents an integer of 1 to 3.

Specific examples of the alkoxy group represented by R ₂₁ in the formula (21) include methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, s-butoxy group, t- Examples include butoxy group, 2-hydroxyethoxy group, 2-cyanoethoxy group, benzyloxy group, 4-methylbenzyloxy group, trifluoromethoxy group and the like.
Examples of the halogen atom for R ₂₁ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the amino group of R ₂₁ include a diphenylamino group, a ditolylamino group, a dibenzylamino group, and a 4-methylbenzyl group.

As the aryl group of Ar ₇ in the above formula (20), phenyl group, naphthyl group, biphenylyl group, terphenylyl group, pyrenyl group, fluorenyl group, 9,9-dimethyl-2-fluorenyl group, azulenyl group, anthryl group, triphenylenyl group And a chrysenyl group.
Ar ₇ , R ₁₃ and R ₁₄ may have an alkyl group, an alkoxy group or a halogen atom defined by Ar ₅ in the above formula (19) as a substituent.

Heterocyclic compound skeletons having tertiary amino groups include amine structures such as pyrrole, pyrazole, imidazole, triazole, dioxazole, indole, isoindole, benzimidazole, benzotriazole, benzisoxazine, carbazole, and phenoxazine. The heterocyclic compound which has. These may have an alkyl group, an alkoxy group or a halogen atom defined by Ar ₅ in the above formula (19) as a substituent.

B ₁ and B ₂ in the above formula (19) have an acryloyloxy group, a methacryloyloxy group, a vinyl group, an acryloyloxy group, a methacryloyloxy group, a vinyl group, an alkyl group, an acryloyloxy group, a methacryloyloxy group, or a vinyl group. Represents an alkoxy group. As the alkyl group and alkoxy group, those described for Ar ₅ in the general formula (19) are similarly applied. Only _{one of} these B ₁ and B ₂ is present, and the presence of both is excluded.
As a more preferable structure in the acrylic ester compound of the general formula (19), a compound of the following general formula (23) can be exemplified.

In the above formula (23), R ₈ and R _{9 each} represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group or a halogen atom, and Ar ₇ and Ar ₈ represent a substituted or unsubstituted aryl group or An arylene group represents a substituted or unsubstituted benzyl group. As the alkyl group, alkoxy group and halogen atom, those described for Ar ₅ in the formula (19) are similarly applied.
The aryl group is the same as the aryl group defined by R ₁₃ and R ₁₄ in the general formula (20). An arylene group is a divalent group derived from the aryl group.
_B 1 .about.B in the above formula (23) ₄ is the same as _B 1, _{B 2} in the general formula (19). u represents an integer of 0 to 5, and v represents an integer of 0 to 4.

  The specific acrylic ester compound has the following characteristics. It is a tertiary amine compound having a stilbene-type conjugated structure, and has a developed conjugated system. By using such a charge transporting compound with a conjugated system, the charge injection property at the interface part of the crosslinkable charge transport layer becomes very good. The action is not easily inhibited, and the charge mobility has good characteristics. Further, it has an acryloyloxy group or a methacryloyloxy group having high radical polymerizability in the molecule, so that it rapidly gels during radical polymerization and does not cause excessive crosslinking distortion. The double bond at the stilbene structure in the molecule partially participates in the polymerization, and the polymerization is lower than the acryloyloxy group or methacryloyloxy group. In addition, since the number of cross-linking reactions per molecular weight can be increased due to the use of double bonds in the molecule, the cross-linking density can be increased, and further improvement in wear resistance can be realized. . In addition, the degree of polymerization of this double bond can be adjusted depending on the crosslinking conditions, and an optimum crosslinked film can be easily produced. Such cross-linking participation in radical polymerization is a specific feature of the acrylate compound and does not occur in the α-phenylstilbene type structure as described above.

From the above, the use of a charge transporting compound having a radical polymerizable functional group represented by the general formula (19), particularly the general formula (23), while maintaining good electrical characteristics and generating cracks and the like. A film having an extremely high crosslink density can be formed without causing it.
Regarding the number of radically polymerizable functional groups, those having a small number of functional groups are preferable for the uniformity of the crosslinked structure, and those having a large number of functional groups are preferable for wear resistance. In the present invention, it is possible to select and use it well from the balance of both.

Polymerizable compound having such a charge transport structure, the oxidation potential of 0.750 (V vs. SCE) or more. In the cross-linked charge transport layer, the effect of image blur tends to be reduced due to the cross-linking of the charge transport material, but when the oxidation potential is less than 0.750 (V vs. SCE) The impact may increase. On the other hand, the oxidation potential of the polymerizable compounds having a charge transport structure is below 0.850 (V vs. SCE). Beyond this, an increase in the potential of the exposed area is observed, and in particular, an increase in the potential of the exposed area in the job may be noticeable. As a method for measuring the oxidation potential of the polymerizable compound having a charge transporting structure contained in the cross-linked charge transport layer, the method for measuring the oxidation potential of the charge transport material contained in the charge transport layer described above may be used. it can.

  Specific examples of the radical polymerizable compound having a charge transporting structure used in the present invention are shown below, but are not limited to the compounds having these structures.

  The polymerizable compound (b) having a charge transporting structure used in the present invention is important for imparting the charge transport performance of the crosslinkable charge transport layer, and this component is 20 to 80 with respect to the total amount of the crosslinkable charge transport layer. Content of a coating liquid component is adjusted so that it may become mass%, Preferably 30-70 mass%. If this component is less than 20% by mass, the charge transport performance of the crosslinkable charge transport layer cannot be maintained sufficiently, the sensitivity decreases with repeated use, and deterioration of electrical characteristics such as an increase in the exposed area potential appears. On the other hand, if it exceeds 80% by mass, the content of the polymerizable compound having no charge transport structure is lowered, resulting in a decrease in the cross-linking density and high wear resistance is not exhibited. Although the electrical characteristics and abrasion resistance required differ depending on the process used, it cannot be said unconditionally, but the range of 30 to 70% by mass is most preferable in consideration of the balance of both characteristics.

  The crosslinkable charge transport layer used in the present invention is formed by reacting a polymerizable compound (a) having no charge transport structure with a polymerizable compound (b) having a charge transport structure and curing. In addition to this, monofunctional and bifunctional radically polymerizable monomers, functional monomers and radicals for the purpose of imparting functions such as viscosity adjustment during coating, stress relaxation of the crosslinked surface layer, low surface energy and reduction of friction coefficient, etc. A polymerizable oligomer can be used in combination. Known radical polymerizable monomers and oligomers can be used.

  Examples of the monofunctional radically polymerizable monomer include 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl carbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, Examples include cyclohexyl acrylate, isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, and styrene monomer.

  Examples of the bifunctional radical polymerizable monomer include 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1, Examples include 6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A-EO modified diacrylate, bisphenol F-EO modified diacrylate, neopentyl glycol diacrylate, and the like.

  Examples of functional monomers include those substituted with fluorine atoms such as octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, 2-perfluoroisononylethyl acrylate, No. 60503, JP-B-6-45770, siloxane repeating units: 20-70 acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, diacryloyl polydimethylsiloxane Examples thereof include vinyl monomers having a polysiloxane group such as diethyl, acrylates and methacrylates.

  Examples of the radical polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers.

  When a large amount of monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers are contained, the three-dimensional cross-linking density of the cross-linked surface layer is substantially lowered, and wear resistance may be lowered. For this reason, it is preferable to limit the content of these monomers and oligomers to 50 parts by mass or less, preferably 30 parts by mass or less with respect to 100 parts by mass of the tri- or higher functional radical polymerizable monomer.

  The crosslinkable charge transport layer used in the present invention uses a polymerization initiator (for example, a thermal polymerization initiator or a photopolymerization initiator) in the coating liquid in order to efficiently advance the crosslinking reaction as necessary. May be.

  Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di ( Peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, peroxide initiators such as lauroyl peroxide, azobisisobutylnitrile, azobiscyclohexanecarbonitrile Azo initiators such as methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, and 4,4′-azobis-4-cyanovaleric acid.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2- Acetophenone-based or ketal-based photopolymerization initiators such as methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether Benzoin ether photopolymerization initiators such as benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, 1 Benzoxanthone photopolymerization initiators such as 2-benzoylbenzene, thioxanthone such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Examples of the photopolymerization initiator and other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylpheny Ethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10- Examples include phenanthrene, acridine compounds, triazine compounds, and imidazole compounds. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.

  These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.5-40 mass parts with respect to 100 mass parts of total inclusions which have radical polymerizability, Preferably it is 1-20 mass parts.

  The crosslinkable charge transport layer of the present invention can contain a filler, and is extremely effective because it has a remarkable effect in abrasion resistance, scratch resistance, filming, cleaning properties, and the like.

The following can be used as the filler.
Examples of the organic filler material include fluorine resin powder such as polytetrafluoroethylene, silicone resin powder, and carbon fine particles. The carbon fine particles are particles having a structure mainly composed of carbon. Particles having a structure such as amorphous, diamond, graphite, amorphous carbon, fullerene, zeppelin, carbon nanotube, carbon nanohorn, and the like. Among these structures, particles containing hydrogen-containing diamond-like carbon or amorphous carbon structure have good mechanical and chemical durability. The diamond-like carbon or amorphous carbon film containing hydrogen is a particle in which similar structures such as a diamond structure having an SP3 orbit, a graphite structure having an SP2 orbit, and an amorphous carbon structure are mixed. Diamond-like carbon or amorphous carbon fine particles are not limited to carbon, but may contain other elements such as hydrogen, oxygen, nitrogen, fluorine, boron, phosphorus, chlorine, bromine and iodine. Absent.

  Inorganic filler materials include metal powders such as copper, tin, aluminum and indium, silicon oxide, tin oxide, zinc oxide, titanium oxide, alumina, zirconia, indium oxide, antimony oxide, bismuth oxide and other metal oxides, titanium Examples include inorganic materials such as potassium acid and boron nitride. In particular, it is advantageous to use an inorganic material among them from the viewpoint of the hardness of the filler. Metal oxides are particularly good, and silicon oxide, alumina, and titanium oxide can be used effectively. Also, fine particles such as colloidal silica and colloidal alumina can be used effectively.

As a filler that hardly causes image blur, a filler having a high specific resistance is preferable. When the conductive filler is contained in the cross-linked charge transport layer of the photoreceptor, the lateral resistance is lowered due to a decrease in surface resistance, and image blurring is likely to occur. In particular, the specific resistance of the filler is preferably 10 ¹⁰ Ω · cm or more from the viewpoint of resolution, and examples of such a filler include alumina, zirconia, and titanium oxide. Above all, α-type alumina, which is a hexagonal dense structure with high light transmission, high thermal stability and excellent wear resistance, suppresses image blur and improves wear resistance, coating quality, and light transmission. It can be used particularly effectively in view of the above. It is also possible to use a mixture of two or more of these fillers, whereby the surface resistance can be controlled. The specific resistance of the filler can be measured using, for example, a powder resistance measuring device. Specifically, the metal oxide powder is put in a cell and sandwiched between electrodes, the load is applied, the amount of the metal oxide powder is adjusted so that the thickness is about 2 mm, and then a voltage is applied between the electrodes. The specific resistance can be obtained by measuring the current flowing at that time.

  Moreover, these fillers can be surface-treated with at least one kind of surface treatment agent, and may be preferable for enhancing the dispersibility of the filler. Lowering the dispersibility of the filler not only raises the potential of the exposed area, but also lowers the transparency of the coating film, causes defects in the coating film, and lowers the abrasion resistance. There is a possibility that it will develop into a big problem. As the surface treatment agent, a conventionally known surface treatment agent can be used.

  The average primary particle size of the filler is preferably 0.01 to 1.0 μm from the viewpoint of light transmittance and wear resistance, and more preferably 0.1 to 0.5 μm. If the average primary particle size of the filler is smaller than this, the filler is likely to agglomerate and wear resistance is decreased, and the surface area of the filler increases, which may increase the potential of the exposed area. Further, when the average primary particle size of the filler is larger than this, the sedimentation property of the filler may be promoted, or the image quality may be deteriorated or an abnormal image may be generated due to the aggregation of the filler.

  Moreover, as addition amount of a filler, 0.1 mass%-50 mass% are preferable with respect to the total solid contained in a bridge | crosslinking type charge transport layer, More preferably, 3 mass%-30 mass%, More preferably It is 5 mass%-20 mass%. If the amount of filler added is less than this, the required wear resistance may not be obtained, and if the amount of filler added is greater than this, the image quality such as an increase in exposed area potential or a decrease in resolution may occur. The effect of deterioration tends to increase. In particular, if the crosslinkable charge transport layer contains more filler than necessary, it may cause curing inhibition, so it is desirable to avoid excessive addition.

  By including a filler in the cross-linked charge transport layer, wear resistance and scratch resistance can be improved, but the influence of an increase in the exposed area potential may increase, and the exposed area potential in the job tends to increase as well. Is seen. This is due to the fact that charge trap sites are included on the filler surface, and in particular, in the case of a hydrophilic metal oxide, the effect tends to increase. Addition of a dispersant having an acid value is effective for suppressing this potential increase in the exposed area. The acid value is defined as the number of milligrams of potassium hydroxide necessary to neutralize the carboxyl group contained in 1 g of resin. The dispersant having an acid value can be expected to adsorb on the surface of a filler, particularly a hydrophilic metal oxide, and fill a trap site causing a residual potential increase. Thereby, even if it contains a hydrophilic filler, the synergistic effect which can suppress the exposure part electric potential raise and can also increase the dispersibility of a filler can be acquired. Improvement of the dispersibility of the filler is effective for preventing filming and improving cleaning properties.

  The dispersant having the acid value is preferably a polycarboxylic acid type dispersant having a carboxyl group in the structure. The carboxylic acid site in the dispersing agent plays an important role of imparting an acid value and enhancing dispersibility. A hydrophilic inorganic filler has low affinity with an organic solvent or a binder resin, and dispersion does not proceed sufficiently as it is. On the other hand, the dispersant has a high affinity with the inorganic filler at the carboxylic acid site and a high affinity with the binder resin or organic solvent at the other polymer sites, so the organic solvent or the binder resin is used via the dispersant. And the like can be increased. This makes it possible to greatly increase the dispersibility of the filler. Even if the above dispersant has one carboxyl group, the effect is recognized, but the polycarboxylic acid derivative having more carboxyl groups improves the dispersibility of the filler and reduces the exposed portion potential. Is effective. Not only the affinity between the dispersant and the filler is further increased, but also by maintaining the affinity between the dispersants, it is possible to improve the dispersibility of the filler and at the same time obtain an effect for preventing sedimentation of the filler. it can.

  The acid value of the dispersant is preferably 10 to 700 mgKOH / g, more preferably 30 to 400 mgKOH / g. If the acid value is higher than necessary, image blurring may appear, and if the acid value is too low, the effect of reducing the exposed area potential cannot be obtained. However, the acid value of the dispersant can be determined by the balance with the amount of the dispersant added. Further, it is preferable to appropriately select the acid value and the addition amount of the dispersant depending on the structure and molecular weight of the dispersant to be used, the kind of filler, the particle size, and the like. In the present invention, the addition amount of the dispersant preferably satisfies the following relational expression, but it is more preferable to set it to the necessary minimum amount.

    1 <(addition amount of dispersing agent × acid value of dispersing agent) / (addition amount of filler) <40

  If the addition amount is increased more than necessary, the influence of image blur may appear, and the dispersibility may also decrease. On the other hand, if the addition amount is too small, the dispersibility becomes insufficient, or the effect of reducing the potential of the exposed area cannot be obtained, resulting in the occurrence of an abnormal image. These techniques are disclosed in Patent Document 29.

  The filler material can be dispersed by using a conventional method such as a ball mill, an attritor, a sand mill, or an ultrasonic wave together with at least an organic solvent, more preferably a dispersant. As the material of the media used, conventionally used media such as zirconia, alumina, and agate can be used, but it is more preferable to use alumina from the viewpoint of filler dispersibility and residual potential reduction effect. Α-type alumina having excellent wear resistance is particularly preferable. Zirconia may increase the amount of media wear during dispersion. Not only does the residual potential increase significantly due to the mixing of these media, but the dispersibility of the zirconia decreases due to the mixing of the wear powder, and the settling of the filler is greatly increased. May decrease. On the other hand, when alumina is used as the medium, the wear amount of the medium during dispersion can be kept low, and the influence of the mixed wear powder on the residual potential is very small. Even if wear powder is mixed, the influence on dispersibility is small compared to other media. Therefore, it is more preferable to use alumina as a medium used for dispersion.

  The dispersant is preferably added before the dispersion together with the filler and the organic solvent, since it suppresses the aggregation of the filler in the coating liquid and further suppresses the sedimentation property of the filler and remarkably improves the dispersibility of the filler. On the other hand, a polymerizable compound, an additive, and the like can be added before dispersion, but in this case, the dispersibility is slightly lowered. Accordingly, these are preferably added after dispersion in a state dissolved in an organic solvent.

  The crosslinkable charge transport layer in the present invention is mainly composed of a polymerizable compound having no charge transporting structure and a polymerizable compound having a charge transporting structure. Various materials such as an agent, a plasticizer, a leveling agent, a lubricant, and an ultraviolet absorber can be added.

  Examples of antioxidants added to the cross-linked charge transport layer include phenolic compounds, hindered phenolic compounds, hindered amine compounds, paraphenylenediamines, hydroquinones, organic sulfur compounds, and organic phosphorus compounds. It is possible to use a known material. Although the effect of further suppressing the image blur can be obtained by the addition of the antioxidant, if it is added more than necessary, the influence of the increase in the potential of the exposed portion in the job may increase. Further, since there is a possibility of causing inhibition of curing, it is preferable to keep the antioxidant to the minimum necessary.

  It is also effective in the present invention to contain a plasticizer in the crosslinkable charge transport layer. By adding a plasticizer, the gas permeability of the crosslinkable charge transport layer can be reduced, the stress applied to the crosslinkable charge transport layer can be relaxed, cracks can be prevented, and the adhesion can be improved. it can. As these additives, known additives can be used, and as plasticizers, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used, and the amount used is the total solid content of the coating liquid. To 20% by mass or less, preferably 10% by mass or less. However, if added in a large amount, it inhibits curing, and there is a risk that wear resistance, scratch resistance and electrostatic characteristics will be lowered.

  It is also effective in the present invention to include a leveling agent in the cross-linked charge transport layer. By adding a leveling agent, the occurrence of coating film defects is reduced, the film thickness is made uniform, and the lubricity of the surface is increased, which is also effective in preventing filming and adhesion of foreign matter. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain can be used. In particular, a leveling agent having a polymerizable functional group is more preferable. The amount used is suitably 3% by mass or less based on the total solid content of the coating solution.

  The coating method for the cross-linked charge transport layer of the present invention may be any method, and conventionally known methods such as a spray coating method, a dip coating method, a ring coating method, and a bead coating method are used. Among these, it is most preferable to apply a spray coating method to uniformly apply a thin film thickness. The coating solution can also be applied by diluting with a solvent. At this time, the solvent used includes alcohols such as methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopenta Non-ketone type, ester type such as ethyl acetate, butyl acetate, ether type such as tetrahydrofuran, dioxane, propyl ether, halogen type such as dichloromethane, dichloroethane, trichloroethane, chlorobenzene, aromatic type such as benzene, toluene, xylene, Examples include cellosolve such as methyl cellosolve, ethyl cellosolve, cellosolve acetate, and the like. These solvents may be used alone or in combination of two or more. The solid content concentration of the coating liquid can be arbitrarily set depending on the solubility of the composition and the target film thickness, but is preferably approximately 15% or more.

  The film thickness of the cross-linked charge transport layer is preferably 1 μm to 10 μm, more preferably 2 μm to 6 μm. If the film thickness is thinner than this, the influence of image blur may increase, and if the film thickness is thicker than this, a significant increase in the exposed area potential is caused. growing.

  The crosslinkable charge transport layer of the present invention is formed by applying energy from the outside and curing it after coating on the surface. At this time, the external energy used includes heat, light, and radiation, and any method can be used.

  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, various heat media, infrared rays or electromagnetic waves. The heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower. When the heating temperature is lower than 100 ° C., the reaction rate is slow and the reaction is not completely completed. When the temperature is higher than 170 ° C., the reaction proceeds non-uniformly and a large strain is generated in the cross-linked charge transport layer. In order to proceed the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 100 ° C. and then heating to 100 ° C. or more.

As the energy of light, a UV irradiation light source such as a high-pressure mercury lamp or a metal halide lamp having an emission wavelength mainly in ultraviolet light can be used, but a visible light source can also be selected according to the absorption wavelength of the radical polymerizable substance or photopolymerization initiator. Is possible. Irradiation light amount is 50 mW / cm ² or more, preferably 500 mW / cm ² or more, more preferably 1000 mW / cm ² or more. By using irradiation light having an illuminance higher than 1000 mW / cm ² , the progress rate of the polymerization reaction is significantly increased, and a more uniform cross-linked charge transport layer can be formed.
Examples of radiation energy include those using electron beams.

  When the crosslinkable charge transport layer is cured by light energy or radiation energy, drying is preferably performed to remove the residual solvent after curing. The drying temperature and time can be arbitrarily selected depending on the solvent used in the coating liquid for the crosslinkable charge transport layer, but are preferably about 100 ° C. to 150 ° C. and about 10 minutes to 30 minutes.

<About the undercoat layer>
In the method for producing an electrophotographic photosensitive member of the present invention, an undercoat layer can be provided between the conductive support and the charge generation layer. The role of the undercoat layer has many roles such as suppressing injection of reverse polarity charges induced on the conductive support during charging of the photosensitive member, preventing moire, and concealing defects in the tube. doing. The injection of the reverse polarity charge induced in the conductive support causes the occurrence of soiling. Moire is a type of image defect in which interference fringes called moire are formed in an image by optical interference when writing with coherent light such as laser light. Thus, the undercoat layer is very effective in suppressing the occurrence of abnormal images.

  The undercoat layer generally comprises a binder resin and an inorganic pigment as main components, thereby preventing charge injection with a reverse polarity. These binder resins are preferably resins having a high solvent resistance with respect to general organic solvents, considering that a charge generation layer and a charge transport layer are applied thereon with a solvent. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin.

  However, the undercoat layer not only suppresses injection of reverse polarity charges, but also has a function of transporting electrons generated in the charge generation layer to the conductive support. Will cause. Therefore, the undercoat layer contains an inorganic pigment. As the inorganic pigment, those having a function of transferring a charge having the same polarity as the charge charged on the surface of the photoreceptor from the charge generation layer to the conductive support side are preferable because they are effective for reducing the potential of the exposed area. For example, in the case of a negatively charged photoconductor, the undercoat layer has electronic conductivity, so that the exposed portion potential can be greatly reduced. As these inorganic pigments, metal oxides are effectively used. Examples thereof include titanium oxide, zinc oxide, calcium fluoride, calcium oxide, silicon oxide, magnesium oxide, aluminum oxide, tin oxide, zirconium oxide, and indium oxide. It is done.

Moreover, said inorganic pigment is a white pigment, The effect which prevents said moire can be acquired by containing these in an undercoat layer. In order to prevent the occurrence of moire by scattering the incident laser light by the undercoat layer, a material having a large refractive index is more preferable as the metal oxide. In the present invention, titanium oxide is most preferably used as the inorganic pigment because of the influence on the exposed area potential and the moire prevention effect.
The average primary particle diameter of the inorganic pigment is 0.01 to 1.0 μm, preferably 0.2 to 0.5 μm. It is also possible to use a mixture of inorganic pigments having different average primary particle diameters, which may be effective for reducing the exposed area potential and suppressing the afterimage. In particular, by mixing an inorganic pigment having an average primary particle size of 1 μm or more and an inorganic pigment of less than 1 μm, the inorganic pigment is densely configured, so that it is possible to realize background suppression and reduction of the exposed portion potential. is there.

  The content ratio of the inorganic pigment to the binder resin needs to be adjusted depending on the type of inorganic pigment used, the layer configuration, and the film thickness, but the volume ratio of the inorganic pigment to the binder resin is preferably in the range of 1/1 to 3/1. When the volume ratio of both is less than 1/1, not only the moire prevention ability is lowered, but there is a possibility that the exposure portion potential increase in repeated use is further increased. On the other hand, in the region where the volume ratio is 3/1 or more, not only the binding ability of the binder resin is lowered, but also the coating film surface property is deteriorated, which may adversely affect the film forming property of the charge generation layer. Furthermore, when the volume ratio between the two is 3/1 or more, there is a case where the soiling is adversely affected.

  These undercoat layers are mainly composed of a binder resin and an inorganic pigment (metal oxide), and can be wet-dispersed in a state including a solvent to obtain a coating dispersion. Examples of the solvent used include acetone, methyl ethyl ketone, methanol, ethanol, butanol, cyclohexanone, dioxane, and the like, and mixed solvents thereof. A coating liquid can be obtained by dispersing the inorganic pigment together with a solvent and a binder resin by a conventionally known method such as a ball mill, a sand mill, or an attriler. The binder resin may be added before dispersion or may be added as a resin solution after dispersion. Further, if necessary, a dispersant may be added for the purpose of enhancing the dispersibility of the chemicals, additives, curing accelerators, and inorganic pigments necessary for curing (crosslinking). Using these coating liquids, they are formed on a conductive substrate using a conventionally known method such as dip coating, spray coating, ring coating, beat coating, or nozzle coating. After the application, it can be produced by drying or heating, and if necessary, drying or curing by a curing treatment such as light irradiation. Although the film thickness of an undercoat layer changes with kinds of inorganic pigment to contain, 1-20 micrometers is preferable and 2-10 micrometers is more preferable. If the film thickness is less than 1 μm, the effect of preventing moire may be reduced, or the decrease in dark part potential due to fatigue may increase, and if it is thicker than necessary, the exposure part potential may be increased. However, when a conductive metal oxide is used as the inorganic pigment, even if the film thickness is increased, the influence on the exposed portion potential is small, and it is possible to form 10 to 20 μm. However, in this case, since the influence of soiling is remarkably increased, it is necessary to use an intermediate layer described later.

  In long-term repetitive use, scumming may become a factor in determining the lifetime, so it is necessary to enhance the scumming suppression effect. However, the occurrence of scumming and the exposure portion potential increase are in a trade-off relationship. Therefore, when the effect of suppressing scumming is enhanced, the increase in potential of the exposed area increases, and when it is attempted to reduce the increase in potential of the exposed area, scumming increases. It is difficult to do. In that case, it is also possible to provide an intermediate layer between the conductive support and the undercoat layer or between the undercoat layer and the charge generation layer, which is effective in realizing a long life. is there.

  The intermediate layer generally uses a binder resin as a main component, and is intended to suppress the injection of holes from the conductive support and prevent soiling. Examples of the resin used for the intermediate layer include polyamide, alcohol-soluble polyamide (soluble nylon), water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. Among them, N-methoxymethylated nylon, which is a polyamide resin, is most suitable because it has a greatly reduced environmental dependency and can always maintain stable image quality even when the use environment of the image forming apparatus changes. Used. In addition, when N-methoxymethylated nylon is used, the exposure portion potential is less dependent on the film thickness and can be used effectively.

As the coating solvent for the intermediate layer, a solvent that dissolves the resin to be used is used. In the case of polyamide, an alcohol solvent such as methanol, ethanol, propanol, butanol, or a mixed solvent thereof is used.
As a method for forming the intermediate layer, a known coating method is employed. For example, the coating is performed by a dip coating method, a spray coating, a ring coating, a beat coating, a nozzle coating method, or the like. After coating, the film formation is completed by drying by heating. However, in the case of curing, a curing treatment such as heating or light irradiation can be performed as necessary. The thickness of the intermediate layer is suitably 0.05-2 μm. Since the intermediate layer does not have a function of transporting charges, it is formed thin. If the film thickness is thicker than this, a significant increase in the potential of the exposed portion is caused, and in particular, the increase in the potential of the exposed portion in Job is noticeable. On the other hand, if the film thickness is thinner than this, scumming may occur with the passage of time and the life of the electrophotographic photosensitive member may be reduced.

  Due to the formation of the intermediate layer, the undercoat layer has a two-layer structure, and the occurrence of background contamination is suppressed even when used repeatedly over a long period of time. This is an effective method for extending the life of the body. However, it is necessary to control the resistance of the undercoat layer depending on whether the intermediate layer is formed on or under the undercoat layer. In the present invention, it is possible to provide the intermediate layer either under the undercoat layer or over the undercoat layer, but it is effective in enhancing the antifouling effect and the moire prevention effect. Therefore, it is more preferable to provide the intermediate layer under the undercoat layer.

<Additives to each layer>
In the present invention, in order to improve environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, a cross-linked charge transport layer, charge transport layer 2, charge transport layer 1, charge generation layer, subbing Additives such as an antioxidant, a plasticizer, a lubricant, and an ultraviolet absorber can be added to each layer such as a layer and an intermediate layer.

Examples of antioxidants that can be used in the present invention include, but are not limited to, the following.
(A) Phenol compound 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl-3- (4′- Hydroxy-3 ′, 5′-di-tert-butylphenol), 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4- Ethyl-6-tert-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1 , 3-Tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4 -Hydroxybenzyl) benzene, te Lakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3′-t-butyl) Phenyl) butyric acid] cricol ester, tocopherols and the like.

(B) Paraphenylenediamines N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylene Diamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.

(C) 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.

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

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

Examples of the plasticizer that can be added to each layer include, but are not limited to, the following.
(A) Phosphate ester plasticizer Triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, Triphenyl phosphate and the like.

(B) Phthalate ester plasticizers Dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, phthalate Dinonyl acid, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, dioctyl fumarate etc.

(C) Aromatic carboxylic acid ester plasticizers Trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate and the like.
(D) Aliphatic dibasic ester plasticizer dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, adipic acid n-octyl-n-decyl , Diisodecyl adipate, dicapryl adipate, di-2-ethylhexyl azelate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2 sebacate -Ethoxyethyl, dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, di-n-octyl tetrahydrophthalate and the like.

(E) Fatty acid ester derivatives butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, tributyrin and the like.
(F) Oxyacid ester plasticizers Methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, tributyl acetyl citrate and the like.

(G) Epoxy plasticizer Epoxidized soybean oil, epoxidized linseed oil, epoxy butyl stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, etc. .
(H) Dihydric alcohol ester plasticizers such as diethylene glycol dibenzoate and triethylene glycol di-2-ethylbutyrate.

(I) Chlorinated plasticizer Chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxychlorinated fatty acid methyl, and the like.
(J) Polyester plasticizer Polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester and the like.

(K) Sulfonic acid derivatives p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide and the like.
(L) Citric acid derivatives Triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, acetyl citrate-n-octyldecyl and the like.
(M) Others Terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, methyl abietate and the like.

Examples of the lubricant that can be added to each layer include, but are not limited to, the following.
(A) Hydrocarbon compound Liquid paraffin, paraffin wax, microwax, low-polymerized polyethylene and the like.
(B) Fatty acid compounds Lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid and the like.

(C) Fatty acid amide compounds Stearylamide, palmitylamide, oleinamide, methylenebisstearamide, ethylenebisstearamide and the like.
(D) Ester compounds Fatty acid lower alcohol esters, fatty acid polyhydric alcohol esters, fatty acid polyglycol esters, and the like.

(E) Alcohol compounds Cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol and the like.
(F) Metal soap Lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate and the like.

(G) Natural wax Carnauba wax, candelilla wax, beeswax, whale wax, ibota wax, montan wax and the like.
(H) Others Silicone compounds, fluorine compounds, etc.

Examples of the ultraviolet absorber that can be added to each layer include, but are not limited to, the following.
(A) Benzophenone series 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4- Methoxybenzophenone etc.

(B) Salsylates Phenyl salsylates, 2,4 di-t-butylphenyl 3,5-di-t-butyl 4-hydroxybenzoate, and the like.

(C) Benzotriazole series (2′-hydroxyphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy3) '-Tert-butyl 5'-methylphenyl) 5-chlorobenzotriazole and the like.
(D) Cyanoacrylate-based ethyl-2-cyano-3,3-diphenyl acrylate, methyl 2-carbomethoxy 3 (paramethoxy) acrylate, and the like.

(E) Quencher (metal complex)
Nickel (2,2′thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate and the like.
(F) HALS (hindered amine)
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6 6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy- 2,2,6,6-tetramethylpiperidine and the like.

<About image forming apparatus>
Next, the image forming apparatus of the present invention will be described in detail with reference to FIG. The image forming apparatus of the present invention can include a charging unit, an electrostatic latent image forming unit, a developing unit, a transfer unit, a fixing unit, a cleaning unit, a charge eliminating unit, a lubricating substance applying unit, and the like as necessary. Alternatively, other means can be added. This is one representative example, and the present invention is not limited to this example. For example, all modifications described later are included in the present invention. The electrophotographic photosensitive member (21) has a drum shape, but is not limited thereto, and may be, for example, a sheet shape or an endless belt shape. (22) is a static elimination lamp, (23) is a charging charger, (24) is an image exposure unit, (25) is a developing unit, (26) is a pre-transfer charger, (27) is a registration roller, and (28) is a registration roller. Transfer paper, (29) is a transfer charger, (30) is a separation charger, (31) is a separation claw, (32) is a charger before cleaning, (33) is a fur brush, and (34) is a blade.

  As charging means, for example, a corona discharge system that applies a high voltage to a wire typified by corotron, scorotron, etc., a solid discharge system that applies high-frequency and high-pressure to a planar electrode that sandwiches an insulating plate instead of a wire, a roller Contact-type roller charging method in which a high voltage is applied to a shaped member and charged in contact with the electrophotographic photosensitive member, and a proximity arrangement type in which the roller has a shape and is charged through a gap of 100 μm or less in the image forming area Conventionally known chargers such as a roller charging method, a contact charging method in which charging is performed in contact with the electrophotographic photosensitive member using a brush, a film, a blade, or the like can be used.

  In the corona charging method, a high voltage is applied to a wire having a diameter of 50 to 100 [mu] m, the surrounding air is ionized and moved to an electrophotographic photosensitive member to be charged. Corona discharge systems are roughly classified into corotron and scorotron. The scorotron has a configuration in which screen electrodes (grids) are arranged on the corotron. The screen electrodes are arranged at a pitch of 1 to 3 mm and are spaced from the electrophotographic photosensitive member by 1 to 2 mm. As a result, even if the charging time becomes long, the charging potential is regulated by the voltage applied to the grid electrode, and the surface potential is saturated. Therefore, the charging potential can be controlled by the grid voltage, and uniform charging is possible. In order to cope with high speed, a double wire type in which two wires are stretched is particularly effective. Of the double wire types, a type in which two wires are partitioned is also effectively used. However, in order to prevent discharge between the wires or between the wire and the casing, it is necessary to provide a gap of 1.5 mm or more per 1 kV.

  The roller-shaped charging method is a method in which a voltage is applied to a conductive roller and brought into contact with an electrophotographic photosensitive member to give an electric charge. Compared with the corona charging method, the applied voltage is low, which is advantageous for downsizing of the apparatus, and has an advantage that the amount of generated ozone is very small. However, if it is used at a very high speed, there is a risk that the chargeability may decrease due to contamination of the roller or the life of the roller. Further, even in the roller-shaped charging method, a proximity arrangement method in which the image forming region is not in contact with the electrophotographic photosensitive member is also effectively used. As a result, the charging roller is contaminated by the developer, paper powder, and the like through repeated use, and it is possible to suppress the occurrence of charge reduction, abnormal image generation, and wear. As a method for disposing the electrophotographic photosensitive member and the charging roller close to each other in the image forming region, there is a method in which a gap is provided in the non-image forming region of the charging roller or the electrophotographic photosensitive member.

  For example, as shown in FIG. 3, by providing a gap tape (gap forming member 51) having a uniform thickness in the non-image forming region of the charging roller (56), the gap can be maintained. Here, (55) is an electrophotographic photosensitive member, (52) is a metal shaft, (53) is an image forming area, and (54) is a non-image forming area. The gap between the electrophotographic photosensitive member and the charging roller is preferably small, and is 100 μm or less, more preferably 50 μm or less. By adopting a configuration in which the charging roller is not brought into contact with the electrophotographic photosensitive member, the discharge becomes non-uniform and the charging of the electrophotographic photosensitive member may become unstable. On the other hand, it is preferable that the applied bias is charged by superimposing an alternating current component (AC) on a direct current component (DC), thereby significantly improving the charging stability.

  As the electrostatic latent image forming means, any exposure means can be used as long as it has light absorbed by the charge generating material of the electrophotographic photosensitive member. The charged electrophotographic photosensitive member is exposed by an electrostatic latent image forming means, and the light is absorbed by the charge generating material to generate a charge pair, which moves to the surface and cancels the surface charge. An electrostatic latent image is formed on the surface of the photographic photoreceptor.

  As a light source used as an exposure means, a light emitting diode (LED), a semiconductor laser (LD), an electroluminescence (EL), a tungsten lamp, a halogen lamp, a mercury lamp, a fluorescent lamp, a sodium lamp, etc. are used if the above conditions are satisfied. be able to. Among these, light emitting diodes and semiconductor lasers are effective from the viewpoint of speeding up and downsizing the apparatus, and are most suitable for further enhancing the effects of the present invention. In addition, these light sources are combined with various filters such as sharp cut filters, band pass filters, near infrared cut filters, dichroic filters, interference filters, and color temperature conversion filters in order to emit light in the desired wavelength range. It can also be used.

  As the exposure means, a multi-beam exposure means, particularly a surface emitting laser, is effectively used in the present invention. In order to cope with the high speed of the image forming apparatus, it is necessary to increase the rotation speed of the polygon mirror of the rotating multi-specular body and increase the image scanning frequency in the sub-scanning direction. However, the rotational speed of the polygon mirror is also limited. In this case, a multi-beam scanning exposure method using a multi-beam recording head is used in which a plurality of beam light sources are arranged in the sub-scanning direction and a plurality of beams are scanned by one scan in the main scanning direction. In this method using a multi-beam recording head, for example, the number of rotations of the polygon mirror of the rotating polyhedral body that is necessary when only one beam light source is obtained by using n beam light sources may be 1 / n. Thus, the speed can be increased by n times as compared with the case of the single beam light source. Further, there is a margin in the scanning speed, and there is a great merit that the scanning density is increased by that amount, and high-speed and high-definition image output becomes possible.

  FIG. 4 shows an example of the multi-beam exposure means used in the present invention. A plurality of laser beams emitted from a light source (301) in which a plurality of light emitting points (301a) are arranged one-dimensionally or two-dimensionally are converted into a parallel light beam or a substantially parallel light beam by a collimating lens (302), and a cylindrical lens (303), an aperture It is deflected in the main scanning direction by a rotary polygon mirror (polygon mirror) (305) via (304). The laser beam deflected by the rotary polygon mirror becomes convergent light by the scanning lens 1 (306a) and the scanning lens 2 (306b), and passes through the reflecting mirrors 1, 2, and 3 (307a, 307b, 307c) to the surface of the photoreceptor (308). ) And is scanned (309) in the main scanning direction.

  As the light source of the multi-beam exposure means, an edge emitting laser and a surface emitting laser can be used. In particular, the surface emitting laser can form a laser array in which the light emitting points are two-dimensionally arranged, and is effective in increasing the speed and size of the image forming apparatus and improving the resolution of the image. A combination of (302), (303), and (304) is referred to as a coupling optical system. (A) is an enlarged view of a light source, and (b) is an enlarged view of a scanning line.

  Thus, when the multi-beam exposure means is used, the speed of the electrophotographic photosensitive member can be increased without being limited to the rotational speed of the polygon mirror. In addition, since the influence due to the overlap of a plurality of laser beams can be reduced, the present invention is particularly effectively used in combination with multi-beam exposure.

  The developing means is a step of developing the electrostatic latent image formed by the electrostatic latent image forming means with toner to form a toner image on the electrophotographic photosensitive member. A negative image (reversal development) can be obtained by developing using a toner having the same polarity as the charged polarity of the electrophotographic photosensitive member, and a positive image can be obtained by developing using a toner having a different polarity. Development includes a one-component development system that uses only toner and a two-component development system that uses a mixture of toner and carrier, and both can be used satisfactorily in the present invention. Also, when developing a full-color image by superimposing a plurality of color toner images on the electrophotographic photosensitive member, using the method of developing in contact with the electrophotographic photosensitive member disturbs the previously developed toner image. There is a risk that. For this purpose, for example, a jumping development system that can be developed without contact with the electrophotographic photosensitive member is preferably used.

  The transfer means is a step of transferring the toner image formed on the electrophotographic photosensitive member to a transfer material (transfer medium such as paper). As the transfer means, a charger can be used. For example, a transfer charger (29) or a combination of the separation charger (30) is effective. As a transfer method, a toner image is directly transferred from the electrophotographic photosensitive member to a transfer medium such as paper using the above-mentioned transfer means, and a toner image on the electrophotographic photosensitive member is once transferred to an intermediate transfer member and then intermediate There is an intermediate transfer method for transferring from a transfer body to a transfer medium such as paper, and either method can be used favorably. The latter intermediate transfer method is effective for high image quality and effective for full-color image forming apparatuses, but it is disadvantageous for speeding up and downsizing of the apparatus. It is necessary to use properly.

  Further, there are a constant voltage method and a constant current method at the time of transfer, and either method can be used. However, the constant current method which can keep the transfer charge amount constant and is excellent in stability is more preferable. The higher the transfer current is, the higher the transferability becomes. In particular, when the linear velocity is increased, the transferability is lowered, so that an increase in the transfer current is effective.

  The fixing unit is a step of fixing the toner image transferred to a transfer medium such as paper on the transfer medium by heating and pressing. As a fixing method, any method may be used as long as the toner can be fixed to the transfer medium. Specific examples include a method of heating and / or pressing, and there are also a combination of a heating roller and a pressing roller, and a method of combining an endless belt.

  The cleaning means is a process in which the toner developed on the electrophotographic photosensitive member by the developing means is transferred to the transfer medium by the transferring means, and the toner remaining on the electrophotographic photosensitive member is removed. Any method may be used as long as these residual toners can be removed from the electrophotographic photosensitive member. As specific means, a fur brush, a blade, or a combination thereof is often used. In addition, a magnetic brush, an electrostatic brush, a magnetic roller, etc. are also used effectively. The cleaning process is contaminated by the adhesion of many foreign substances such as developer components, paper dust, and discharge products in addition to residual toner on the electrophotographic photosensitive member, which greatly affects the image quality. It has a role to remove. In that respect, a cleaning blade is most preferably used.

  If the electrostatic latent image contrast remains on the electrophotographic photosensitive member even if the residual toner is removed by the cleaning unit, the neutralization unit may be visualized as an afterimage or a ghost image in the next cycle. Therefore, it is a process of removing them. As the charge eliminating means, any means may be used as long as the charge generating substance can absorb the light emitted from it. For example, light emitting diodes (LEDs), semiconductor lasers (LD), electroluminescence (EL), tungsten lamps, halogen lamps, xenon lamps, mercury lamps, fluorescent lamps, sodium lamps and the like, and optical filters mentioned as exposure means And may be used in combination. In addition to the light irradiation method, there is also a method of removing electricity by applying a reverse bias, which is preferable for suppressing electrostatic fatigue.

  In the present invention, a lubricating substance applying means may be provided on the surface of the electrophotographic photosensitive member, which is very effective. By applying a lubricating material to the surface of the electrophotographic photosensitive member, it is possible to prevent the cleaning blade from turning over and accompanying cleaning failure. In addition, since the lubricating material is applied to the surface of the electrophotographic photosensitive member, the surface of the electrophotographic photosensitive member is prevented from being deteriorated due to charging. That is, it is an effective method that can achieve both a long life and high image quality. Since the electrophotographic photosensitive member can be further improved in wear resistance, scratch resistance and cleaning property, it is used very effectively.

  Lubricating substance application means solidifies the lubricating substance, scrapes it with a brush and applies it to the electrophotographic photosensitive member, applies the lubricating substance directly to the electrophotographic photosensitive member, and applies it to the developer. There are many methods such as a method in which a lubricating substance is mixed in the form of powder, and the developing means supplies and coats the surface of the electrophotographic photoreceptor. In the present invention, any method can be used as long as a lubricating material is applied to the surface of the electrophotographic photosensitive member, but the method of scraping and applying with a brush is most preferably used.

  For example, the lubricating substance applying means (30) shown in FIG. 5 presses the fur brush of (31), the lubricating substance of (32), and the lubricating substance of (33) in the direction of the fur brush as application members. The pressure spring is provided. The lubricious substance (32) is a solid lubricant formed in a bar shape, and is pressed against the pressure spring (33) with a predetermined pressure, and the fur brush (31) rotates to cause the lubricious substance (32). Is scraped off and applied to the surface of the image carrier. The pressure spring (33) is effective in always supplying the same amount of the lubricating material by the fur brush (31) to the surface of the image carrier even if the lubricating material decreases over time.

  In addition, in order to uniformly apply the electrophotographic photosensitive member surface, a method in which a blade is brought into contact and the applied lubricating substance is spread is also effective and preferably used. In this case, the blade may be used together with the cleaning blade, or a coating blade dedicated to the lubricating material may be provided separately from the cleaning blade. It is preferable that the lubrication substance application mechanism is disposed in a subsequent process of the cleaning means.

  As the lubricating substance used in the present invention, any substance can be used as long as it is a substance that uniformly adheres to the surface of the electrophotographic photosensitive member and as a result can impart lubricity to the surface of the electrophotographic photosensitive member. For example, materials such as waxes and lubricants can be used satisfactorily. For example, lead oleate, zinc oleate, copper oleate, zinc stearate, cobalt stearate, iron stearate, copper stearate, calcium stearate, aluminum stearate, zinc palmitate, copper palmitate, zinc linolenate, etc. Fatty acid metal salts, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polytrifluorochloroethylene, dichlorodifluoroethylene, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-oxafluoropropylene copolymer, etc. And fluororesin. Waxes can also be used, and ester or olefin types are effective. The ester wax has an ester bond, and examples thereof include natural waxes such as carnauba wax, candelilla wax and rice wax, and montan wax. Examples of the olefin wax include synthetic waxes such as polyethylene wax and polypropylene wax. Among these, a high effect is obtained with a small amount of coating, and the effect of protecting the surface of the image carrier is high with respect to charging, and metal stearate, and further zinc stearate can be mentioned as the most usable in the present invention. It is done.

<Tandem type image forming apparatus>
The tandem type image forming apparatus is provided with the same number of electrophotographic photosensitive members corresponding to the developing units that hold a plurality of color toners independently, thereby developing each color independently in parallel. The apparatus forms a full-color image by processing and then superimposing toner images of respective colors. Specifically, it is provided with a developing unit and electrophotographic photosensitive member of at least four colors of yellow (Y), magenta (M), cyan (C), and black (K) required for full-color printing. Compared with the conventional single drum system that outputs the process repeatedly, it achieves extremely high speed full-color printing, which is a particularly effective method in the present invention.

  FIG. 6 is a typical schematic diagram for explaining the full-color image forming apparatus according to the tandem system of the present invention. In FIG. 6, reference numerals (1C, 1M, 1Y, 1K) denote drum-shaped electrophotographic photosensitive members, and the electrophotographic photosensitive member of the present invention is used. This electrophotographic photosensitive member (1C, 1M, 1Y, 1K) rotates in the direction of the arrow in the figure, and at least in that order in the order of rotation, charging means (2C, 2M, 2Y, 2K), developing means (4C, 4M, 4Y) 4K) and cleaning means (5C, 5M, 5Y, 5K) are arranged.

  From the back side of the electrophotographic photosensitive member between the charging means (2C, 2M, 2Y, 2K) and the developing means (4C, 4M, 4Y, 4K), laser light (3C, 3M, 3Y, 3K) and an electrostatic latent image is formed on the electrophotographic photosensitive member (1C, 1M, 1Y, 1K). The four image forming elements (6C, 6M, 6Y, 6K) centering on the electrophotographic photoreceptors (1C, 1M, 1Y, 1K) are the transfer conveyance belt (10) as the transfer material conveyance means. Are juxtaposed along. The transfer conveyance belt (10) is electrophotographic photosensitive between the developing means (4C, 4M, 4Y, 4K) and the cleaning means (5C, 5M, 5Y, 5K) of each image forming unit (6C, 6M, 6Y, 6K). Transfer brushes (11C, 11M, 11M, 1M, 1K, 1K) for applying a transfer bias to the surface (back surface) of the transfer conveyance belt (10) that is in contact with the back side of the electrophotographic photosensitive member side. 11Y, 11K) are arranged. Each image forming element (6C, 6M, 6Y, 6K) is different in the color of the toner inside the developing device, and the others are the same in configuration.

  In the full-color image forming apparatus having the configuration shown in FIG. 6, the image forming operation is performed as follows. First, in each image forming element (6C, 6M, 6Y, 6K), the charging means (2C) in which the electrophotographic photosensitive member (1C, 1M, 1Y, 1K) rotates in the direction of the arrow (the direction along with the electrophotographic photosensitive member). 2M, 2Y, 2K), and then corresponding to each color image created by laser light (3C, 3M, 3Y, 3K) with an exposure unit (not shown) placed outside the electrophotographic photosensitive member An electrostatic latent image is formed. Next, the electrostatic latent image is developed by developing means (4C, 4M, 4Y, 4K) to form a toner image. Developing means (4C, 4M, 4Y, 4K) are developing means for developing with toners of C (cyan), M (magenta), Y (yellow), and K (black), respectively. 1C, 1M, 1Y, 1K) toner images of respective colors are superimposed on the transfer paper. The transfer paper (7) is fed out of the tray by a paper feed roller (8), temporarily stopped by a pair of registration rollers (9), and transferred and conveyed (10) in synchronism with the image formation on the electrophotographic photosensitive member. ). The transfer paper (7) held on the transfer conveyance belt (10) is conveyed, and the toner images of the respective colors are transferred at contact positions (transfer portions) with the electrophotographic photosensitive members (1C, 1M, 1Y, 1K). Is done.

  The toner image on the electrophotographic photosensitive member is generated by an electric field formed by a potential difference between the transfer bias applied to the transfer brush (11C, 11M, 11Y, 11K) and the electrophotographic photosensitive member (1C, 1M, 1Y, 1K). And transferred onto the transfer paper (7). Then, the transfer paper (7) on which the toner images of four colors are superimposed through the four transfer portions is conveyed to the fixing device (12), where the toner is fixed, and is discharged to a paper discharge portion (not shown). Further, residual toner that is not transferred by the transfer unit and remains on the electrophotographic photosensitive members (1C, 1M, 1Y, 1K) is collected by a cleaning device (5C, 5M, 5Y, 5K).

  In the example of FIG. 6, the image forming elements are arranged in the order of C (cyan), M (magenta), Y (yellow), and K (black) from the upstream side to the downstream side in the transfer paper conveyance direction. However, it is not limited to this order, and the color order is arbitrarily set. Further, when a black-only document is created, it is particularly effective to use the present invention to provide a mechanism that stops the image forming elements (6C, 6M, 6Y) other than black. Furthermore, in FIG. 6, the charging means is in contact with the electrophotographic photosensitive member, but by providing a suitable gap (about 10 to 200 μm) between the two with the charging mechanism as shown in FIG. Fewer toner filming on the charging means is required, and it can be used well.

<About process cartridges>
The image forming means as described above may be fixedly incorporated in a copying machine, facsimile, or printer, and each image forming element may be incorporated in the apparatus in the form of a process cartridge. . The process cartridge includes an electrophotographic photosensitive member and, in addition, at least one of means selected from a charging unit, an electrostatic latent image forming unit, a developing unit, a transfer unit, a cleaning unit, a charge eliminating unit, a lubricating substance applying unit, and the like. One device (part) including one, and is detachable from the image forming apparatus main body. The shape or the like of the process cartridge is not limited, but a general example is shown in FIG.

  The process cartridge for an image forming apparatus includes an electrophotographic photosensitive member 101, and further includes at least one of a charging unit 102, a developing unit 104, a transfer unit 106, a cleaning unit 107, and a charge eliminating unit (not shown). An apparatus (part) that can be attached to and detached from the image forming apparatus main body. The image forming process by the apparatus illustrated in FIG. 7 will be described. The electrophotographic photosensitive member 101 is charged by the charging unit 102 and exposed by the electrostatic latent image forming unit 103. An image is formed, and the electrostatic latent image is developed with toner by the developing unit 104, and the toner development is transferred to the transfer member 105 by the transfer unit 106 and printed out. Next, the surface of the electrophotographic photosensitive member after the image transfer is cleaned by the cleaning unit 107 and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited to a following example. All parts are parts by mass.

<Synthesis of titanyl phthalocyanine crystal>
First, a method for synthesizing the titanyl phthalocyanine crystal used in the examples will be described. The synthesis was in accordance with the synthesis method described in Patent Document 30 (Japanese Patent Application Laid-Open No. 2004-83859). That is, 292 parts of 1,3-diiminoisoindoline and 1800 parts of sulfolane are mixed, and 204 parts of titanium tetrabutoxide are added dropwise under a nitrogen stream. After completion of the dropping, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while keeping the reaction temperature between 170 ° C. and 180 ° C. After the reaction is completed, the mixture is allowed to cool, and then the precipitate is filtered, washed with chloroform until the powder turns blue, then washed several times with methanol, further washed several times with hot water at 80 ° C. and dried. Crude titanyl phthalocyanine was obtained. Crude titanyl phthalocyanine is dissolved in 20 times the amount of concentrated sulfuric acid, added dropwise to 100 times the amount of ice water with stirring, the precipitated crystals are filtered, and then ion-exchanged water (pH: 7.) until the washing solution becomes neutral. 0, specific conductivity: 1.0 μS / cm) Repeated washing with water (pH value of ion-exchanged water after washing was 6.8, specific conductivity was 2.6 μS / cm), wet of titanyl phthalocyanine pigment A cake (water paste) was obtained.

  40 parts of this wet cake (water paste) thus obtained was put into 200 parts of tetrahydrofuran and stirred vigorously (2000 rpm) with a homomixer (Kennis, MARKIIf model) at room temperature, and the dark blue color of the paste turned pale blue. When changed (20 minutes after the start of stirring), stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filtration device were washed with tetrahydrofuran to obtain a wet cake of pigment. This was dried under reduced pressure (5 mmHg) at 70 ° C. for 2 days to obtain 8.5 parts of titanyl phthalocyanine crystals. This is designated as Pigment 1. The solid content concentration of the wet cake was 15% by mass. The crystal conversion solvent was used in a mass ratio of 33 times that of the wet cake. Note that a halogen-containing compound is not used as a raw material in this synthesis example. When the obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions, the Bragg angle 2θ with respect to CuKα ray (wavelength 1.542１．５) was 27.2 ± 0.2 °, and the maximum peak and the minimum angle 7.3. Has a peak at ± 0.2 °, and further has major peaks at 9.4 ± 0.2 °, 9.6 ± 0.2 °, 24.0 ± 0.2 °, and 7.3 A titanyl phthalocyanine powder having no peak between the peak at 0 ° and the peak at 9.4 ° and further having no peak at 26.3 ° was obtained. The result is shown in FIG.

<X-ray diffraction spectrum measurement conditions>
X-ray tube: Cu
Voltage: 50 kV
Current: 30 mA
Scanning speed: 2 ° / min Scanning range: 3 ° -40 °
Time constant: 2 seconds

<Synthesis of azo pigments>
It produced according to the method as described in patent document 31 (patent 3026645 gazette).

<Synthesis Example of Radical Polymerizable Compound Having Charge Transporting Structure>
The compound having a charge transporting structure in the present invention is synthesized, for example, by the method described in Patent Document 32 (Japanese Patent No. 3164426). An example of a method for producing a compound having a charge transporting structure is shown below.

(Synthesis of radically polymerizable compound having triarylamine structure)
(1) Synthesis of hydroxy group-substituted triarylamine compound (the following structural formula B) 113.85 g (0.3 mol) of a methoxy group-substituted triarylamine compound (the following structural formula A) and 138 g (0.92 mol) of sodium iodide To this, 240 ml of sulfolane was added and heated to 60 ° C. in a nitrogen stream. In this solution, 99 g (0.91 mol) of trimethylchlorosilane was added dropwise over 1 hour and stirred at a temperature of about 60 ° C. for 4 and a half hours to complete the reaction. About 1.5 L of toluene was added to the reaction solution, cooled to room temperature, and washed repeatedly with water and an aqueous sodium carbonate solution. Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (adsorption medium: silica gel, developing solvent: toluene: ethyl acetate = 20: 1). Cyclohexane was added to the obtained pale yellow oil to precipitate crystals. In this way, 88.1 g (yield = 80.4%, melting point: 64.0-66.0 ° C., elemental analysis value (%): shown in Table 2) of the following structural formula B was obtained. .

(2) Synthesis of Triarylamino Group-Substituted Acrylate Compound (Exemplary Compound No. 54 in Table 1-8) Hydroxy Group-Substituted Triarylamine Compound (Structural Formula B) Obtained in (1) above 82.9 g (0 .227 mol) was dissolved in 400 ml of tetrahydrofuran, and an aqueous sodium hydroxide solution (NaOH: 12.4 g, water: 100 ml) was added dropwise in a nitrogen stream. The solution was cooled to 5 ° C., and 25.2 g (0.272 mol) of acrylic acid chloride was added dropwise over 40 minutes. Then, it stirred at 5 degreeC for 3 hours, and reaction was terminated. The reaction solution was poured into water and extracted with toluene. This extract was repeatedly washed with an aqueous sodium bicarbonate solution and water. Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (adsorption medium: silica gel, developing solvent: toluene). N-Hexane was added to the obtained colorless oil to precipitate crystals. Thus, Exemplified Compound Nos. As a result, 80.73 g of 54 white crystals (yield = 84.8%, melting point: 117.5 to 119.0 ° C.) was obtained. The elemental analysis results (%) are shown in Table 3 below.

<Synthesis example of acrylic ester compound>
(1) Preparation of diethyl 2-hydroxybenzylphosphonate 38.4 g of 2-hydroxybenzyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 80 ml of o-xylene were placed in a reaction vessel equipped with a stirrer, thermometer, and dropping funnel, Under an air stream, 62.8 g of triethyl phosphite (manufactured by Tokyo Chemicals) was slowly dropped at 80 ° C., and the reaction was further carried out at the same temperature for 1 hour. Thereafter, the produced ethanol, the solvent o-xylene, and the unreacted triethyl phosphite were removed by distillation under reduced pressure to obtain 66 g of diethyl 2-hydroxybenzylphosphonate (boiling point 120.0 ° C./1.5 mmHg). (Yield 90%).

(2) Preparation of 2-hydroxy-4 ′-(N, N-bis (4-methylphenyl) amino) stilbene Into a reaction vessel equipped with a stirrer, a thermometer and a dropping funnel, 14.8 g of potassium tert-butoxide. A solution of 9.90 g of diethyl 2-hydroxybenzylphosphonate and 5.44 g of 4- (N, N-bis (4-methylphenyl) amino) benzaldehyde in tetrahydrofuran was added under a nitrogen stream. The solution was slowly added dropwise at room temperature, and then reacted at the same temperature for 2 hours. Thereafter, water was added under water cooling, and then 2N hydrochloric acid aqueous solution was added for acidification. Tetrahydrofuran was removed by an evaporator, and the crude product was extracted with toluene. The toluene phase was washed with water, an aqueous sodium hydrogen carbonate solution and saturated brine in this order, and dehydrated by adding magnesium sulfate. After filtration, toluene was removed to obtain an oily crude product, which was further purified with silica gel and then crystallized in hexane to give 5.09 g of 2-hydroxy-4 ′-(N, N-bis). (4-Methylphenyl) amino) stilbene was obtained (yield 72%, melting point 136.0-138.0 ° C.).

(3) Preparation of 4 ′-(N, N-bis (4-methylphenyl) amino) stilben-2-yl acrylate In a reaction vessel equipped with a stirrer, thermometer and dropping funnel, 2-hydroxy-4′- (N, N-bis (4-methylphenyl) amino) stilbene (14.9 g), tetrahydrofuran (100 ml), 12% strength aqueous sodium hydroxide solution (21.5 g) were added, and acrylic acid chloride (5.17 g) was added at 5 ° C. under a nitrogen stream. It was added dropwise over 30 minutes. Then, it was made to react at the same temperature for 3 hours. The reaction solution was poured into water, extracted with toluene, concentrated and subjected to column purification with silica gel. The obtained crude product was recrystallized with ethanol, and yellow needle-like 4 ′-(N, N-bis (4-methylphenyl) amino) stilben-2-yl acrylate (exemplified compounds in Table 1-19) No. 109) 13.5 g was obtained. (Yield 79.8%, melting point 104.1-105.2 ° C.) Elemental analysis (%) results are shown in Table 4 below.

  As described above, a number of 2-hydroxystilbene derivatives are synthesized by reacting 2-hydroxybenzylphosphonic acid ester derivatives with various amino-substituted benzaldehyde derivatives, and acrylation or methacrylation is carried out to produce various acrylic acids. An ester compound can be synthesized.

Example 1
Using an intermediate layer coating solution, undercoat layer coating solution, charge generation layer coating solution, and charge transport layer 1 coating solution having the following composition on an aluminum cylinder having an outer diameter of 60 mm, by a dip coating method. Application was performed sequentially, followed by drying in an oven to form an intermediate layer of about 0.5 μm, an undercoat layer of about 3.0 μm, a charge generation layer of about 0.2 μm, and a charge transport layer 1 of about 15 μm. . The drying conditions for each layer were 130 ° C. and 10 minutes for the intermediate layer, 130 ° C. and 20 minutes for the undercoat layer, 90 ° C. and 20 minutes for the charge generation layer, and 120 ° C. and 20 minutes for the charge transport layer 1. On top of that, a charge transport layer 2 coating solution having the following composition was applied by spray coating, followed by drying in an oven to form a charge transport layer 2 of about 10 μm. The drying conditions for the charge transport layer 2 were 120 ° C. and 20 minutes. The oxidation potential of the charge transport material was determined from the first oxidation half-wave potential by cyclic voltammetry. The measurement uses a three-electrode cell, the electrode is platinum as a counter electrode and a counter electrode, the reference electrode is a saturated calomel electrode, and the electrolyte contains tetra-n-butylammonium perchlorate as a supporting electrolyte. A 1M acetonitrile solution was used.

(Intermediate layer coating solution)
N-methoxymethylated nylon: 5 parts (FR101: manufactured by Lead City Corporation)
Methanol: 70 parts n-Butanol: 30 parts

(Coating liquid for undercoat layer)
Titanium oxide A: 50 parts (CR-EL, average primary particle size: about 0.25 μm, manufactured by Ishihara Sangyo Co., Ltd.)
Titanium oxide B: 20 parts (PT-401M, average primary particle size: about 0.07 μm, manufactured by Ishihara Sangyo Co., Ltd.)
Alkyd resin: 14 parts (Beckolite M6401-50, solid content: 50%, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin: 8 parts (L-145-60, solid content: 60%, manufactured by Dainippon Ink & Chemicals, Inc.)
2-butanone: 70 parts

(Coating solution for charge generation layer)
Titanylphthalocyanine showing the X-ray diffraction spectrum of FIG. 8: 8 parts (ionization potential 5.27 eV)
Polyvinyl butyral: 4 parts (BX-1, manufactured by Sekisui Chemical Co., Ltd.)
2-butanone: 400 parts Using a PSZ ball having a diameter of 0.5 mm in a commercially available bead mill disperser, a 2-butanone solution in which polyvinyl butyral was dissolved and a pigment were charged, and the rotor rotation speed was 3000 r. p. m. Dispersion was performed for 120 minutes to prepare a dispersion.

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： ０．２部
（ＫＦ５０−１００ＣＳ、信越化学工業製） (Coating liquid for charge transport layer 1)
Polycarbonate: 10 parts (Z Polyca, manufactured by Teijin Chemicals Ltd.)
Charge transport material represented by CTM14 (molecular weight: 700.97): 10 parts (Oxidation potential: 0.690 V vs. SCE)
Antioxidant A represented by the following structural formula: 0.5 part

Tetrahydrofuran: 100 parts 1% silicone oil in tetrahydrofuran: 0.2 parts (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.)

(Coating liquid for charge transport layer 2)
Polycarbonate: 10 parts (Z Polyca, manufactured by Teijin Chemicals Ltd.)
Charge transport material represented by CTM17 (molecular weight: 700.97): 10 parts (oxidation potential: 0.770 V vs. SCE)
Tetrahydrofuran: 400 parts 1% silicone oil in tetrahydrofuran: 0.2 parts (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.)

A crosslinkable charge transport layer was further formed on the charge transport layer 2 by a spray coating method using a coating liquid for a crosslinkable charge transport layer having the following composition. The filler was dispersed in a 70 cc glass pot by placing an alumina ball having a diameter of 5 mm, and further filled with the following filler, polycarboxylic acid compound and cyclopentanone, and dispersed for 24 hours (150 rpm) with a ball mill. Thereafter, a mill base obtained by adding tetrahydrofuran and stirring the mixture and a solution in which other materials were mixed in advance were mixed to prepare a coating solution for a crosslinkable charge transport layer.
Spray coating was performed on the charge transport layer 2 using the coating solution, and natural drying was performed for 5 minutes while rotating. Then, after naturally drying for 3 minutes, UV irradiation was performed using a Fusion UV lamp system using a metal halide lamp while rotating the support at 50 rpm. A V bulb was used for the ultraviolet irradiation lamp, the distance between the ultraviolet lamp and the photosensitive member surface was 52 mm, the irradiation intensity was 500 mW / cm ^2, and the ultraviolet irradiation was performed for 60 seconds to cure. After the ultraviolet irradiation, drying was performed at 130 ° C. for 15 minutes, and a cross-linked charge transport layer having a total film thickness of 3 μm was provided to produce an electrophotographic photosensitive member. The oxidation potential of the polymerizable compound having a charge transport structure was measured in the same manner as the charge transport material.

(Mill base)
Alumina filler: 8 parts (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Polycarboxylic acid compound: 0.2 part (BYK-P104, non-volatile content 50%, manufactured by BYK Chemie)
Cyclopentanone: 8 parts Tetrahydrofuran: 12 parts

(Coating liquid for crosslinkable charge transport layer)
Millbase: 7 parts Radical polymerizable compound having no charge transporting structure: 5 parts (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 no charge transporting structure: 5 parts caprolactone-modified dipentaerythritol hexaacrylate (KAYARAD DPCA-60, manufactured by Nippon Kayaku Co., Ltd.)
Molecular weight: 1263, number of functional groups: 6 functions, molecular weight / number of functional groups = 211
Radical polymerizable compound having a charge transporting structure: 12 parts
(Exemplary Compound No. 143 in Table 1-26) (Oxidation Potential: 0.805 Vvs. SCE)
Photopolymerization initiator: 1 part (1-hydroxy-cyclohexyl-phenyl-ketone,
(Irgacure 184, manufactured by Ciba Specialty Chemicals)
Leveling agent: 0.2 part BYK-UV3570 (by Big Chemie)
Tetrahydrofuran: 140 parts

(Example 2)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM10 (molecular weight: 700.97): 10 parts (oxidation potential: 0.740 Vvs. SCE)

(Example 3)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM54 (molecular weight: 615.80): 10 parts (oxidation potential: 0.758 V vs. SCE)

Example 4
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM65 (molecular weight: 451.62): 10 parts (oxidation potential: 0.760 Vvs. SCE)

(Example 5)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM70 (molecular weight: 479.66): 10 parts (oxidation potential: 0.725 V vs. SCE)

(Example 6)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM82 (molecular weight: 477.65): 10 parts (oxidation potential: 0.710 Vvs. SCE)

(Example 7)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM100 (molecular weight: 363.49): 10 parts (oxidation potential: 0.785 V vs. SCE)

(Example 8)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by the above CTM99 (molecular weight: 379.49): 10 parts (oxidation potential: 0.765 V vs. SCE)

Example 9
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM115 (molecular weight: 516.67): 10 parts (oxidation potential: 0.735 V vs. SCE)

(Example 10)
In Example 4, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 1 was changed to the following charge transport material.
Charge transport material represented by CTM67 (molecular weight: 483.60): 10 parts (oxidation potential: 0.620 Vvs. SCE)

(Example 11)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 10 was changed to the following charge transport material.
Charge transport material represented by CTM115 (molecular weight: 516.67): 10 parts (oxidation potential: 0.735 V vs. SCE)

(Example 12)
In Example 5, an electrophotographic photoreceptor was produced in the same manner as in Example 5 except that the charge transport material contained in the charge transport layer 1 was changed to the following charge transport material.
Charge transport material represented by CTM12 (molecular weight: 700.97): 10 parts (oxidation potential: 0.695 Vvs. SCE)

(Example 13)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 12 was changed to the following charge transport material.
Charge transport material represented by CTM82 (molecular weight: 477.65): 10 parts (oxidation potential: 0.710 Vvs. SCE)

(Example 14)
In Example 13, an electrophotographic photosensitive member was produced in the same manner as in Example 13 except that the charge transport material contained in the charge transport layer 1 was changed to the following charge transport material.
Charge transport material represented by CTM66 (molecular weight: 467.61): 10 parts (oxidation potential: 0.700 V vs. SCE)

(Example 15)
In Example 14, an electrophotographic photosensitive member was produced in the same manner as in Example 14 except that the charge transport material contained in the charge transport layer 2 was changed to the following charge transport material.
Charge transport material A represented by the following structural formula (molecular weight: 287.40): 10 parts (oxidation potential: 0.760 Vvs. SCE)

(Example 16)
In Example 2, electrophotography was carried out in the same manner as in Example 2 except that the polymerizable compound having a charge transporting structure contained in the coating liquid for the crosslinkable charge transporting layer was changed to the following polymerizable compound. A photoconductor was prepared.
Radical polymerizable compound having a charge transporting structure: 12 parts (Exemplary compound No. 54 in Table 1-8) (Oxidation potential: 0.821 V vs. SCE)

(Example 17)
In Example 2, electrophotography was carried out in the same manner as in Example 2 except that the polymerizable compound having a charge transporting structure contained in the coating liquid for the crosslinkable charge transporting layer was changed to the following polymerizable compound. A photoconductor was prepared.
Radical polymerizable compound having a charge transporting structure: 12 parts (Exemplary Compound No. 144 in Table 1-26) (Oxidation potential: 0.802 V vs. SCE)

(Example 18)
In Example 2, electrophotography was carried out in the same manner as in Example 2 except that the polymerizable compound having a charge transporting structure contained in the coating liquid for the crosslinkable charge transporting layer was changed to the following polymerizable compound. A photoconductor was prepared.
Radical polymerizable compound having a charge transporting structure: 12 parts (Exemplary Compound No. 150 in Table 1-28) (Oxidation Potential: 0.771 V vs. SCE)

( Reference Example 1 )
In Example 2, electrophotography was carried out in the same manner as in Example 2 except that the polymerizable compound having a charge transporting structure contained in the coating liquid for the crosslinkable charge transporting layer was changed to the following polymerizable compound. A photoconductor was prepared.
Radical polymerizable compound having a charge transporting structure: 12 parts (Exemplary Compound No. 148 in Table 1-27) (Oxidation Potential: 0.855 V vs. SCE)

(Comparative Example 1)
In Example 1, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the thickness of the charge transport layer 1 was 25 μm and the charge transport layer 2 was not provided.

(Comparative Example 2)
In Example 1, except that the charge transport material contained in the charge transport layer 1 is changed to the following charge transport material, the thickness of the charge transport layer 1 is 25 μm, and the charge transport layer 2 is not provided. An electrophotographic photosensitive member was produced in the same manner as in Example 1.
Charge transport material represented by CTM17 (molecular weight: 700.97): 10 parts (oxidation potential: 0.770 V vs. SCE)

(Comparative Example 3)
In Example 1, except that the charge transport material contained in the charge transport layer 1 is changed to the following charge transport material, the thickness of the charge transport layer 1 is 25 μm, and the charge transport layer 2 is not provided. An electrophotographic photosensitive member was produced in the same manner as in Example 1.
Charge transport material represented by CTM70 (molecular weight: 479.66): 10 parts (oxidation potential: 0.725 V vs. SCE)

(Comparative Example 4)
In Example 1, except that the charge transport material contained in the charge transport layer 1 is changed to the following charge transport material, the thickness of the charge transport layer 1 is 25 μm, and the charge transport layer 2 is not provided. An electrophotographic photosensitive member was produced in the same manner as in Example 1.
Charge transport material represented by CTM82 (molecular weight: 477.65): 10 parts (oxidation potential: 0.710 Vvs. SCE)

(Comparative Example 5)
In Example 1, except that the charge transport material contained in the charge transport layer 1 is changed to the following charge transport material, the thickness of the charge transport layer 1 is 25 μm, and the charge transport layer 2 is not provided. An electrophotographic photosensitive member was produced in the same manner as in Example 1.
Charge transport material represented by CTM67 (molecular weight: 483.60): 10 parts (oxidation potential: 0.620 Vvs. SCE)

(Comparative Example 6)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM12 (molecular weight: 700.97): 10 parts (oxidation potential: 0.695 Vvs. SCE)

(Comparative Example 7)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 2 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM66 (molecular weight: 467.61): 10 parts (oxidation potential: 0.700 V vs. SCE)

(Comparative Example 8)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge transport material contained in the charge transport layer 1 in Example 1 was changed to the following charge transport material.
Charge transport material represented by CTM82 (molecular weight: 477.65): 10 parts (oxidation potential: 0.710 Vvs. SCE)

(Comparative Example 9)
An electrophotographic photosensitive member was produced in the same manner as in Comparative Example 8 except that the charge transport material contained in the charge transport layer 2 in Comparative Example 8 was changed to the following charge transport material.
Charge transport material represented by CTM67 (molecular weight: 483.60): 10 parts (oxidation potential: 0.620 Vvs. SCE)

(Comparative Example 10)
In Example 1, an electrophotographic photosensitive member was produced in the same manner as Example 1 except that the cross-linked charge transport layer was not provided.

テトラヒドロフラン： ５００部
シクロヘキサノン： １５０部
上記実施例及び比較例において作製した感光体における電荷輸送層１、２及び架橋型輸送層で用いた電荷輸送材料を表５に示す。 (Comparative Example 11)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the crosslinkable charge transport layer was changed to the following protective layer in Example 1.
(Coating liquid for protective layer)
Mill base: 7 parts Polycarbonate: 10 parts (Z polycarbonate, manufactured by Teijin Chemicals Ltd.)
Charge transport material represented by CTM17 (Molecular weight: 700.97): 7 parts (Oxidation potential: 0.770 V vs. SCE)
Antioxidant A represented by the following structural formula: 1 part

Tetrahydrofuran: 500 parts Cyclohexanone: 150 parts Table 5 shows the charge transport materials used in the charge transport layers 1 and 2 and the crosslinked transport layer in the photoreceptors produced in the above examples and comparative examples.

  Subsequently, the photoconductor produced as described above was evaluated. The electrophotographic photosensitive members of Examples and Comparative Examples were set in a process cartridge and mounted on a tandem-type full-color digital copier Rigoh's imagio MPC7500 modified machine. As the charging means, a proximity-arranged roller charging method shown in FIG. 3 was used, and a semiconductor laser having a wavelength of 780 nm was used as the exposure means as the electrostatic latent image forming means. Further, as the toner filled in the developing means, polymerized toner having an average particle diameter of about 6 μm was used, an intermediate transfer belt was used as the transfer means, and a blade was used as the cleaning means. Further, as the lubricating substance of the lubricating substance application means, zinc stearate solidified in a bar shape is used, and a pressure spring and a fur brush are attached as shown in FIG. 5, and the zinc stearate is scraped off by the fur brush. The structure is such that it is supplied to the surface of the photoreceptor. Further, after zinc stearate adhered to the surface of the photoreceptor, a coating blade was provided so that the zinc stearate did not adhere excessively and was uniformly applied to the surface of the photoreceptor. Further, a potential sensor is attached between the electrostatic latent image forming means and the developing means so that the exposure portion potential can always be measured.

  First, for each electrophotographic photosensitive member, an initial image was output using the evaluation machine. At that time, the exposed portion potential (VL) of the electrophotographic photosensitive member measured by the potential sensor was read. Continuously, 100 sheets of continuous printing is set to 1 Job, and this is repeated 5 times to measure the exposure portion potential over time. The difference between the exposure portion potential at the start of Job and the exposure portion potential at the end of Job after 5 iterations is calculated. Evaluation was performed as the amount of potential fluctuation (ΔVL) in the exposed portion of the job. Thereafter, the first sheet at the beginning of the job and the image density fluctuation at the end after repeating the job five times were evaluated. Evaluation was performed in an environment of 23 ° C. and 55% RH.

Next, a forced deterioration test was performed by exposing these electrophotographic photoreceptors to NOx gas. The exposure conditions were NO / NO ₂ = 60/15 ppm, the temperature and humidity were set at 35 ° C. and 60% RH, and exposure was performed for 4 days. After the exposure was completed, the electrophotographic photosensitive member was set in the evaluation machine, an image was output, and the image blur was evaluated. Thereafter, 100,000 sheets were continuously run, the image was output again, and the obtained image was evaluated. These results are shown in Table 6.

(Initial image evaluation criteria)
◎: Image density difference is small and very good level ○: Image density difference is slightly recognized, but good level △: Image density difference is identified, level slightly exceeding allowable range ×: Image density difference clearly Identified and problematic level

(Criteria for image evaluation after exposure to NOx and after printing 100,000 sheets)
◎: Abnormal image is not observed, very good level ○: When the image is enlarged, the resolution is slightly lower than the initial level, but it is a good level △: Image quality deterioration is visually recognized, and the level slightly exceeds the allowable range ×: Level at which image quality degradation is clearly recognized and regarded as a problem

  In the electrophotographic photoreceptor of the present invention, there was little fluctuation in the exposed area potential in the job, and almost no density fluctuation was observed after repeating the first and 100th jobs five times. Further, after that, almost no image blur was observed in the accelerated deterioration test due to NOx exposure, and good image quality was maintained even after printing 100,000 sheets. On the other hand, those in which the oxidation potential of the charge transporting material does not fall within the scope of the present invention have very low image quality stability, such as significant image density fluctuations and severe image blurring caused by NOx exposure. The lifetime of the photographic photoreceptor was very short. Further, the electrophotographic photosensitive member having a short lifetime and lacking in image quality consistency was also obtained in the case where the crosslinkable charge transport layer of the present invention was not provided.

(Figure 1)
31 Conductive Support 32 Charge Generation Layer 33 Charge Transport Layer 1
34 Charge Transport Layer 2
35 Crosslinkable charge transport layer 36 Undercoat layer

(Figure 2)
DESCRIPTION OF SYMBOLS 21 Electrophotographic photosensitive member 22 Static elimination lamp 23 Charger charger 24 Image exposure part 25 Developing unit 26 Charger before transfer 27 Registration roller 28 Transfer paper 29 Transfer charger 30 Separation charger 31 Separation claw 32 Charger before cleaning 33 Fur brush 34 Blade

(Figure 3)
51 Gap forming member 52 Metal shaft 53 Image forming area 54 Non-image forming area 55 Electrophotographic photosensitive member 56 Charging roller

(Fig. 4)
301 Light source 301a Light emitting point 302 Correlation lens 303 Cylindrical lens 304 Aperture 305 Rotating polygon mirror (polygon mirror)
306a Scanning lens 1
306b Scanning lens 2
307a Reflector 1
307b Reflector 2
307c Reflector 3
308 Photosensitive member surface 309 Scan direction scanning direction

(Fig. 5)
30 Lubricating substance application means 31 Fur brush 32 Lubricating substance 33 Pressure spring

(Fig. 6)
1C, 1M, 1Y, 1K Electrophotographic photosensitive member 2C, 2M, 2Y, 2K Charging unit 3C, 3M, 3Y, 3K Laser light 4C, 4M, 4Y, 4K Developing unit 5C, 5M, 5Y, 5K Cleaning unit 6C, 6M , 6Y, 6K Image forming unit 7 Transfer paper 8 Feed roller 9 Registration roller 10 Transfer conveyor belt 11C, 11M, 11Y, 11K Transfer brush 12 Fixing device

(Fig. 7)
DESCRIPTION OF SYMBOLS 101 Electrophotographic photoreceptor 102 Charging means 103 Electrostatic latent image forming means 104 Developing means 105 Transfer body 106 Transfer means 107 Cleaning means

JP 56-48637 A JP-A 64-1728 JP-A-4-281461 JP 2005-99688 A Japanese Patent Laid-Open No. 2-139666 JP-A-2-150850 Japanese Patent Laid-Open No. 2-144551 JP 2002-287567 A JP 2007-79244 A JP 59-136744 A Japanese Patent No. 419476 JP 2000-292959 A Japanese Patent Laid-Open No. 2006-13895 JP 2008-70676 A Japanese Patent Publication No. 4-80381 Japanese Patent No. 4112444 JP 2007-233425 A JP 2007-279678 A Japanese Examined Patent Publication No. 52-36016 JP-A-53-95033 JP-A-53-133445 JP-A-53-132347 Japanese Patent Laid-Open No. 54-21728 JP 54-22834 A JP 54-12742 A JP 54-17733 A JP 54-2129 A Japanese Patent Laid-Open No. 54-14967 Japanese Patent No. 3802787 JP 2004-83859 A Japanese Patent No. 3026645 Japanese Patent No. 3164426

Claims (17)

In an electrophotographic photoreceptor in which at least a charge generation layer, a charge transport layer 1, a charge transport layer 2, and a crosslinkable charge transport layer are sequentially laminated on a conductive support, the crosslinkable charge transport layer has at least a charge transport structure. The charge transport layer 1 contains a charge transport material having an oxidation potential Eox (CTL1), and the charge transport layer 2 is oxidized. An oxidation potential of a polymerizable compound containing a charge transport material having a potential Eox (CTL2), wherein the oxidation potential Eox (CTL1) and the oxidation potential Eox (CTL2) satisfy the following formula and have the charge transport structure: Is an electrophotographic photosensitive member characterized by having an A of 0.750 (V vs. SCE) or more and 0.850 (V vs. SCE) or less.
Eox (CTL1) <0.705 (V vs. SCE) <Eox (CTL2)   2. The electrophotographic photoreceptor according to claim 1, wherein the charge transport material having the oxidation potential Eox (CTL1) and / or the charge transport material having the oxidation potential Eox (CTL2) has a triarylamine structure. 3. The charge transport material having the oxidation potential Eox (CTL1) and / or the charge transport material having the oxidation potential Eox (CTL2) is a triarylamine compound represented by the following general formula (1). The electrophotographic photoreceptor described in 1.

[In the above formula (1), R _{1 to} R ₄ each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group. May be. The phenyl group may be unsubstituted, or may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms as a substituent.
A represents a substituted or unsubstituted arylene group or a group represented by the following general formula (1a).

(In the above formula (1a), R ₅ , R ₆ and R ₇ each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a phenyl group. May be unsubstituted or may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms as a substituent.)
B and B ′ each represent a substituted or unsubstituted aryl group or a group represented by the following general formula (1b). B and B ′ may be the same or different.

(In the above formula (1b), Ar ₁ represents an arylene group and may have an alkyl group or alkoxy group having 1 to 4 carbon atoms as a substituent. Ar ₂ and Ar ₃ are each an aryl group. And may have a C 1-4 alkyl group or alkoxy group as a substituent.
However, at least one of A, B and B ′ has a triarylamine structure. ] 3. The charge transport material having an oxidation potential Eox (CTL1) and / or the charge transport material having an oxidation potential Eox (CTL2) is a triarylamine compound represented by the following general formula (2). The electrophotographic photoreceptor described in 1.

[In the above formula, Ar ₄ , Ar ₅ , Ar ₇ , Ar ₈ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or an aryl group, and in the case of an aryl group, an alkyl group having 1 to 4 carbon atoms] Or an alkoxy group as a substituent. Ar ₆ represents an arylene group and may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. R ₈ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. N represents an integer of 0 or 1. ] 3. The charge transport material having the oxidation potential Eox (CTL1) and / or the charge transport material having the oxidation potential Eox (CTL2) is a triarylamine compound represented by the following general formula (3): The electrophotographic photoreceptor described in 1.

[In the above formula, Ar ₉ and Ar ₁₀ represent an aryl group, which may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. Ar ₁₁ represents an arylene group and may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. X represents a substituted or unsubstituted aryl group, or a group represented by the following general formula (3a). ]

[In the above formula, Ar ₁₂ and Ar ₁₃ represent an aryl group, which may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. Ar ₁₄ represents an arylene group and may have an alkyl group having 1 to 4 carbon atoms or an alkoxy group as a substituent. ]   6. The molecular weight of the charge transport material having the oxidation potential Eox (CTL1) and / or the charge transport material having the oxidation potential Eox (CTL2) is in the range of 300 or more and 800 or less. An electrophotographic photoreceptor according to any one of the above. The number of functional groups of the polymerizable compound having the charge transporting structure is 1, and the number of functional groups of the polymerizable compound not having the charge transporting structure is 3 or more. An electrophotographic photoreceptor according to any one of the above.   The electrophotographic photoreceptor according to claim 7, wherein the polymerizable compound having no charge transporting structure is a mixture of a plurality of polymerizable compounds having different numbers of functional groups.   The functional group of the polymerizable compound having the charge transporting structure and / or the polymerizable compound not having the charge transporting structure is an acryloyloxy group and / or a methacryloyloxy group. The electrophotographic photosensitive member according to any one of the above. The electrophotographic photosensitive member according to claim 1, wherein the charge transporting structure of the polymerizable compound having the charge transporting structure is a triarylamine structure. The electrophotographic photoreceptor according to claim 10, wherein the polymerizable compound having a charge transporting structure is at least one compound represented by the following general formula (4) or (5).

[In the above formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, A nitro group, an alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), Halogenated carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. And Ar ₁ and Ar ₂ each represents a substituted or unsubstituted arylene group, which may be the same or different. Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, or an alkyleneoxycarbonyl group. m and n represent an integer of 0 to 3. ] The electrophotographic photosensitive member according to claim 1, wherein the cross-linked charge transport layer contains a filler.   At least an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, an electrostatic latent image forming unit for forming an electrostatic latent image on the electrophotographic photosensitive member, and a toner on the electrophotographic photosensitive member. An image forming apparatus comprising: a developing unit that forms a visible image, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.   The image forming apparatus is a tandem system including a plurality of at least one selected from the electrophotographic photosensitive member, the charging unit, the electrostatic latent image forming unit, and the developing unit. Item 14. The image forming apparatus according to Item 13.   15. The image forming apparatus according to claim 13, further comprising a lubricating substance applying unit that adheres a lubricating substance to the surface of the electrophotographic photosensitive member.   The image forming apparatus according to claim 15, wherein the lubricating substance contains at least zinc stearate. The at least one of charging means , electrostatic latent image forming means, developing means, transfer means, cleaning means, static elimination means, and lubricating substance applying means, and the electrophotographic photosensitive member according to any one of claims 1 to 12 are integrated. And a process cartridge that is removable from the main body of the image forming apparatus.

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