JP2009300765A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and an image forming method in which, in order to form a high-definition image with high durability, the rise of residual potential and the rise of exposed part potential are suppressed during repeated use of a photoreceptor having a protective layer, and which enable high-speed image output with high durability. <P>SOLUTION: The image forming apparatus includes an electrophotographic photoreceptor and includes at least a negative charging means, an exposure means, a developing means, a transfer means, a cleaning means and a discharging means, and further includes a positive charging means, wherein positive charges are applied by the positive charging means so that the surface potential of the photoreceptor becomes a positively charged state, and the photoreceptor is a photoreceptor obtained by sequentially laying at least a charge generating layer, a charge transport layer and a crosslinked charge transport layer on a conductive support. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that reduces a residual potential of a photosensitive member (potential after static elimination) and suppresses an increase in exposure part potential (exposure part potential during solid black printing) and has good repeated stability.

  Conventionally, selenium (Se), amorphous silicon (a-Si), and cadmium sulfide (CdS) have been mainly used as photosensitive materials for electrophotographic photoreceptors. However, in recent years, low cost, non-toxicity, ease of manufacture, It has been replaced by organic photoreceptor materials that are advantageous in terms of the wide range of light absorption wavelength and the amount of absorption, electrical characteristics such as high-sensitivity and stable charging characteristics, and the wide selection range of materials. It is often used in facsimile machines, laser printers, and their combined machines.

  The above-mentioned image forming apparatus has been colorized, and its functions have been improved year by year, and high durability, high stability, and high image quality are required. Tandem color image using multiple image forming elements each of which is equipped with a single member required for image formation such as charging, exposure, development, cleaning, static elimination, etc. Forming equipment is the current mainstream. For this reason, unless the photosensitive member and the members around it are made compact, the image forming apparatus becomes very large. Therefore, it is essential to reduce the diameter of the photosensitive member arranged at the center of the image forming element. . Even if the image forming apparatus is made compact by reducing the diameter of the photosensitive member, it is meaningless if the durability is extremely deteriorated compared with the case of a large diameter. For this reason, it is necessary to improve the durability over the conventional photoconductor.

  There are two rate-limiting processes in the life of the photoreceptor, one is electrostatic fatigue and the other is film wear. Both are major problems for the current mainstream organic photoreceptors. The former is a change in the surface potential of the photoreceptor (charging potential (unexposed portion potential) and exposed portion potential) due to repeated use in image formation such as charging / exposure, and the charge potential decreases when organic materials are used. Alternatively, an increase in exposed portion potential or residual potential becomes a problem. The latter is a phenomenon in which a layer located on the outermost layer constituting the photoconductor is mechanically worn by rubbing of a cleaning member or the like. When the film thickness on the surface of the photoconductor decreases due to this abrasion, scratches on the surface, an increase in electric field strength due to the decrease in the photoconductor film thickness, acceleration of electrostatic fatigue, etc., may be caused. It becomes. Therefore, in order to improve the life of the photoreceptor, the above two problems must be solved simultaneously.

  Also, at present, electrophotographic image forming apparatuses are entering the printing field by realizing high speed, and high image quality and high stability are demanded. Regarding the former, 600 dpi is the lowest quality as the resolution in image writing, and the resolution has been greatly improved. In the latter, taking advantage of the characteristics of electrophotography that can directly print manuscript information, it is now possible to add information that print contents differ one by one in output manuscripts that are good at large-volume printing. Sex has come to be strongly demanded. For this, the stability in repeated use of the imaging element is very important.

  On the other hand, a curable charge transport layer formed using a coating solution comprising a monomer having a carbon-carbon double bond, a charge transport agent having a carbon-carbon double bond, and a binder resin as an abrasion resistance technique for the photosensitive layer. (For example, Patent Document 1: Japanese Patent No. 3194392) is known. This binder resin is thought to play a role of improving the adhesion between the charge generation layer and the curable charge transport layer, and further mitigating the internal stress of the film during thick film curing, and has a carbon-carbon double bond. These are broadly classified into those having reactivity with the charge transfer agent and those having no reactivity with the double bond. This photoconductor is remarkably compatible with wear resistance and good electrical properties, but when a non-reactive binder resin is used, the binder resin, the monomer and the charge transport agent are used. The compatibility with the cured product produced by this reaction is poor, and layer separation occurs in the charge transport layer, which may cause scratches and adhesion of external additives and paper powder in the toner. In addition, as described above, the three-dimensional network structure does not proceed sufficiently, and the cross-linking density becomes dilute. In addition, what is specifically described as the monomer used in this photoreceptor is bifunctional, and in these respects, it has not yet been satisfactory in terms of wear resistance. Even when a reactive binder is used, the molecular weight of the cured product is increased, but the number of intermolecular crosslinks is small, and it is difficult to achieve a balance between the amount of the charge transporting substance and the crosslink density. Abrasion was not sufficient.

  In addition, a photosensitive layer containing a compound obtained by curing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule is also known (for example, Patent Document 2: JP 2000-66425 A). ). However, this photosensitive layer has high hardness because the crosslink density can be increased, but since the bulky hole transporting compound has two or more chain polymerizable functional groups, distortion occurs in the cured product and internal stress is reduced. In some cases, the cross-linked surface layer tends to crack and peel off when used for a long time. Even in the conventional photoconductors having a cross-linked photosensitive layer in which a charge transporting structure is chemically bonded, it cannot be said that the present invention has sufficient comprehensive characteristics.

  Further, a photoreceptor having a protective layer has a problem that accumulation of residual potential occurs when it is used repeatedly, and image quality such as image density reduction, loss of detail, and background contamination is deteriorated. This is thought to be due to the small injection efficiency of holes or electrons into the protective layer and the low mobility in the film.

  The conditions around the photoconductor from the copying process are limited for photoconductors that have residual potential in long-term use and photoconductors that have insufficient charging potential stability, such as photoconductors that increase the exposed area potential. As a study, (i) a conductive flexible member to which an AC bias voltage is applied between the cleaning step and the uniform charging step is brought into contact with the a-Si photosensitive member to release the trapping (Patent Literature). 3: JP-A-60-42355), (ii) a conductive flexible member to which an AC or DC bias voltage is applied and heated between the cleaning step and the uniform charging step is referred to as an a-Si type photosensitive member. The trapping is released by bringing it into contact with the body (Patent Document 4: Japanese Patent Laid-Open No. 60-156068), and (iii) an alternating electric field is applied to the surface of the photoreceptor before uniform charging. The surface of the photosensitive member is charged before and after the waveform peak of one polarity, and the trapping can be released by the generated electric field (Patent Document 5: Japanese Patent Laid-Open No. 60-03964). (Iv) Uniform charging and / or charge removal Before performing the charging, precharging with the same polarity as the uniform charging is performed (Patent Document 6: Japanese Patent Laid-Open No. 61-65764), and (v) discharging is performed by DC corona charging with the opposite polarity to the uniform charging (Patent Document 6). 7: JP-A-60-10266), (vi) A photosensitive member having a diamond-like carbon protective layer is used, and a charge having a polarity opposite to that of the main charging is applied to the photosensitive member between the cleaning step and the main charging step. At the same time of application, exposure is performed immediately before or immediately after, and charging is performed under at least two different charging conditions in the main charging step (Patent Document 8: Japanese Patent Laid-Open No. 06-2144). 7 No.), and the like.

Among these, (i), (ii), (iii) and (iv) are all a-Si type photoreceptors without a protective layer, and holes and / or electrons trapped in the photoreceptor are used in the charging step. Before entering, an AC bias (and photo neutralization, heating) is applied to open the circuit, and the electrical resistance and capacitance are restored to repeatedly reduce the charging potential and improve the memory phenomenon.
In the method (v), 40 to 90% of the current required for reverse polarity charging is applied to correct the decrease in charging potential. The method (vi) is a photoconductor having a diamond-like carbon protective layer, which effectively reduces the residual potential and the accumulation generated on the photoconductor, while lowering the charge potential accompanying charge fatigue and reducing the image quality. It is intended to make it difficult for the drop to occur.

However, in the case of (i), (ii), (iii) and (iv), since there is no surface protective layer, the bias voltage due to AC acts relatively easily and the expected effect can be obtained. In the case of a high surface protective layer, the effect is difficult to achieve, so almost no effect can be expected.
On the other hand, in the case of (v), although there is an effect for the purpose of preventing the image density from being lowered, if the reverse charge is applied before the cleaning process, the characteristics are obtained in the case of the photoreceptor having no protective layer. Even in the case of a photoreceptor provided with a protective layer, fog development may occur due to poor cleaning of the toner, and image quality may be significantly degraded. In the case of (vi), although it is effective for a photoreceptor having a diamond-like carbon protective layer, it cannot be expected for a photoreceptor using a cross-linked charge transport layer as a protective layer.

  In addition, as an image forming apparatus using a photosensitive member having a cross-linked charge transport layer, which is provided with a means for applying a charge having a polarity opposite to that of the charging means, is provided for collecting toner in a cleanerless process (Patent Document) 9: Japanese Patent Application Laid-Open No. 2002-082464), but none of them describes the residual potential and the exposure portion potential increase.

Japanese Patent No. 3194392 JP 2000-66425 A JP-A-60-42355 JP-A-60-156068 Japanese Patent Laid-Open No. 60-03964 JP 61-65764 A Japanese Patent Laid-Open No. 60-10266 Japanese Patent Laid-Open No. 06-214497 JP 2002-082464 A

An object of the present invention is to solve the conventional problems and achieve the following objects.
That is, the present invention forms a highly durable and high-definition image, and therefore suppresses a rise in residual potential and a rise in the rear portion potential in the repeated use of a photoreceptor having a protective layer, and is a highly durable and high-speed image output. An object is to provide a forming apparatus and an image forming method.

The above problems are solved by the present invention described below.
(1) “In an image forming apparatus comprising an electrophotographic photosensitive member and at least a negative charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a charge eliminating unit, and a positive charging unit, by the positive charging unit, A positive charge is applied to the photoconductor so that the surface potential of the photoconductor is in a positive charge state, and the photoconductor has at least a charge generation layer, a charge transport layer, and a cross-linked charge transport layer on a conductive support. An image forming apparatus characterized by being a photoreceptor in which layers are sequentially laminated ”,
(2) “The image forming apparatus according to item (1), including a heating unit that heats the photoconductor”;
(3) According to the above (1) or (2), the positive charge is applied so that the surface potential of the photoconductor becomes + 100V to + 800V. Image forming apparatus ",
(4) “The image forming apparatus according to (2) or (3), wherein the photosensitive member is heated to a temperature of 40 ° C. to 60 ° C. by the heating unit”;
(5) “The cross-linked charge transport layer is formed by curing at least a trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. The image forming apparatus according to any one of (1) to (4), wherein:
(6) “The functional group of the tri- or higher functional radical polymerizable monomer having no charge transporting structure has at least one functional group selected from an acryloyloxy group and a methacryloyloxy group” The image forming apparatus according to any one of (1) to (5),
(7) “The functional group of the radically polymerizable compound having a monofunctional charge transporting structure is an acryloyloxy group or a methacryloyloxy group,” according to any one of (1) to (6). Image forming apparatus ",
(8) “The image forming apparatus according to any one of (1) to (7) above, wherein the curing unit of the crosslinkable charge transport layer is a heating or light energy irradiation unit”,
(9) “Image formation according to any one of items (1) to (8), wherein at least charging, image exposure, development, and transfer are repeated using the electrophotographic photosensitive member. apparatus".

  According to the present invention, in the image forming apparatus comprising the electrophotographic photosensitive member and at least a negative charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a positive charging unit and a heating unit, the positive charging unit Thus, the surface potential of the photoconductor is positively charged, and the positive charging unit is disposed immediately before the negative charging unit. The image forming apparatus heats the photoconductor by the heating unit. The photosensitive layer of the photosensitive member having a conductive support and a photosensitive layer has a structure in which a charge generation layer, a charge transport layer, and a crosslinkable charge transport layer are sequentially laminated from the conductive support side, and the crosslinkable charge transport layer is at least a charge. Using a radical-polymerizable monomer having a trifunctional or higher functionality not having a transporting structure and a radical-polymerizing compound having a monofunctional charge-transporting structure. This reduces the residual potential of the photoconductor and suppresses the increase in the potential of the exposed area, has good repeatability with respect to electrical characteristics, and also has good wear resistance and scratch resistance, and has high durability and high performance. A forming device is obtained. Therefore, it is possible to provide a high-performance and highly reliable image forming apparatus that can provide a good image over a long period of time by using this photoconductor.

Hereinafter, the present invention will be described in detail.
The present invention relates to an image forming apparatus comprising an electrophotographic photosensitive member and at least a negative charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a positive charging unit, and a heating unit. An image forming apparatus in which the surface potential of the photoconductor is positively charged, the positive charging unit is disposed immediately before the negative charging unit, and the photoconductor is heated by the heating unit. A support and a photosensitive layer, wherein the photosensitive layer of the photoreceptor has a structure in which a charge generation layer, a charge transport layer, and a crosslinkable charge transport layer are sequentially laminated from the conductive support side, and the crosslinkable charge transport layer is at least By forming a radical polymerizable monomer having a trifunctional or higher functional group having no charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure, A highly durable and high-performance image forming apparatus is achieved that reduces the residual potential and suppresses the increase in the potential of the exposed area, has good repeated stability in terms of electrical characteristics, and has good wear resistance and scratch resistance. Is.

The reasons for this are as follows.
The electrophotographic photosensitive member is used in an environment where a series of processes of a charging unit, a developing unit, a transfer unit, a cleaning unit, and a neutralizing unit are repeated. In this process, the photosensitive member deteriorates and a residual potential is generated. The potential increases. The causes of the generation of the residual potential and the increase in the exposed area potential are as follows: (1) Charge and charge due to decomposition of the composition of the charge generation layer and charge transport layer of the photoreceptor due to discharge during static elimination and chemical degradation due to oxidizing gas. Inhibition of charge transfer caused by trapping. (2) Inhibition of charge cancellation caused by charge trapping easily at the interface between each layer constituting the photoconductor and the interface between the fine powder and the resin in the undercoat layer in which the fine powder of the metal oxide is dispersed Is mentioned.

  For the photoconductor in which the residual potential is generated and the photoconductor in which the stability of the uniform charging potential is insufficient, the conditions around the photoconductor from the copying process are examined. (I) The cleaning process and the uniform charging process A conductive flexible member to which an AC bias voltage is applied is brought into contact with the a-Si photoconductor to release trapping. (Ii) AC or DC bias voltage between the cleaning process and the uniform charging process To release the trapping by contacting the heated and flexible conductive flexible member to the a-Si photoconductor, and (iii) applying an alternating electric field to the surface of the photoconductor before uniform charging. Thus, the surface of the photosensitive member is charged before and after the waveform peak of one polarity applied, and the trapping can be released by the generated electric field. (Iv) Before performing uniform charging and / or charge removal (V) Performing static charge with the same polarity as that of the uniform charge, (v) Performing neutralization by direct current corona charge having the opposite polarity to the uniform charge, (vi) Cleaning process and main charge using a photoconductor having a diamond-like carbon protective layer During the process, exposure is performed at the same time or immediately before or after applying a charge having a polarity opposite to that of the main charging, and charging is performed under at least two different charging conditions in the main charging process. It is done. However, in the case of (i), (ii), (iii) and (iv), since there is no surface protective layer, the bias voltage due to AC acts relatively easily and the expected effect can be obtained. In the case of a high surface protective layer, the effect is difficult to achieve, so almost no effect can be expected.

  On the other hand, in the case of (v), although there is an effect for the purpose of preventing the decrease in image density, if reverse charge is applied before the cleaning process, there is an effect in the case of a photoreceptor having no protective layer. Even in the case of a photoconductor provided with a protective layer, fog development may occur due to poor cleaning of the toner, and image quality may be significantly deteriorated. In the case of (vi), although it is effective for a photoreceptor having a diamond-like carbon protective layer, it cannot be expected for a photoreceptor using a cross-linked charge transport layer as a protective layer. Also, as an image forming apparatus using a photosensitive member having a cross-linked charge transport layer, which is equipped with a means for applying a charge having a polarity opposite to that of the charging means, provided for collecting toner in a cleanerless process (for example, Patent Document 9: Japanese Patent Application Laid-Open No. 2002-082464), but none of them describe a residual potential or an exposure portion potential increase.

On the other hand, in the present invention, a positive charging unit that imparts a positive charge immediately before the negative charging unit and a unit that heats the photosensitive member are provided, and the positive charging unit sets the photosensitive member to a positive charging state. Further, the residual potential can be reduced by heating the photosensitive member temperature, preferably 40 ° C. to 60 ° C., the rise of the exposed portion potential can be suppressed, and the stability of electrical characteristics can be maintained repeatedly. In order to suppress the increase in the residual potential and the exposed portion potential as described above, the object can be achieved by a method in which the photosensitive member is brought into a positively charged state by a positive charging unit prior to the negative charging unit. In the negatively charged photoconductor, charges are trapped in the photoconductor after exposure, transfer or charge removal, and the subsequent negative charging is performed as it is, so that charge accumulation increases. As a result, a residual potential and an exposed portion potential are increased. Therefore, by applying a positive charge immediately before the negative charge, the trapped charge is expelled from the photoconductor, thereby suppressing an increase in residual potential and exposure portion potential. Further, the effect can be further increased by heating the photoreceptor to 40 ° C. to 60 ° C. By heating the photoreceptor, the molecular motion of molecules present in each organic layer constituting the photoreceptor is activated, the burden on the photoreceptor such as charge fatigue is reduced, and charge trapping is further eased. Thereby, stabilization of the image quality over a long period of time can be achieved.
The structure of the photoreceptor will be described below.

First, the constituent materials of the crosslinkable charge transport layer coating solution used in the present invention will be described.
Examples of the trifunctional or higher functional radical polymerizable monomer having no charge transport property used in the present invention include a hole transport structure such as triarylamine, hydrazone, pyrazoline, carbazole, condensed polycyclic quinone, diphenoquinone, cyano group. And a monomer having no electron transport structure such as an electron-withdrawing aromatic ring having a nitro group and having three or more radical polymerizable functional groups. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and is capable of radical polymerization.

Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.
(1) Examples of the 1-substituted ethylene functional group include functional groups represented by the following formulas.
_{CH 2 = CH-X 1 -} ···· formula (10)
(In the formula, X ₁ is an arylene group such as a phenylene group or a naphthylene group which may have a substituent, an alkenylene group which may have a substituent, a —CO— group, a —COO— group. , —CON (R ₁₀ ) — group (R ₁₀ represents an alkyl group such as hydrogen, methyl group or ethyl group, an aralkyl group such as benzyl group, naphthylmethyl group or phenethyl group, or an aryl group such as phenyl group or naphthyl group. Or the —S— group.)
Specific examples of these substituents include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamide group, and a vinyl thioether group.

(2) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
_{CH 2 = C (Y) -X} 2 - ···· formula (11)
(In the formula, Y is an aryl group such as an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, or a naphthyl group. Group, halogen atom, cyano group, nitro group, alkoxy group such as methoxy group or ethoxy group, -COOR ₁₁ group (R ₁₁ is a hydrogen atom, an alkyl such as an optionally substituted methyl group or ethyl group) Group, an aralkyl group such as benzyl which may have a substituent, a phenethyl group or the like, an aryl group such as a phenyl group or a naphthyl group which may have a substituent, or -CONR ₁₂ R ₁₃ (R ₁₂ and R ₁₃ is a hydrogen atom, which may have a substituent an alkyl group such as methyl group and ethyl group, which may have a substituent group benzyl group, naphthylmethyl group, or Ara such phenethyl group, Kill group or substituent a phenyl group which may have a, an aryl group such as a naphthyl group, which may be the same or different from each other.) Further, X ₂ and X ₁ in the formula (10) Represents the same substituent, 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.)

  Specific examples of these substituents include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.

In addition, examples of the substituent further substituted with the substituent for X ₁ , X ₂ , and Y include, 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, and a compound having three or more acryloyloxy groups is, for example, a compound having three or more hydroxyl groups in the molecule and an acrylic group. It can be obtained by using an acid (salt), an acrylic acid halide, or an acrylic ester to cause an ester reaction or a transesterification reaction. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

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

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

  The radical polymerizable compound having a monofunctional charge transport structure used in the crosslinked charge transport layer of the present invention is, for example, a hole transport structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone. , A compound having an electron transport structure such as diphenoquinone, an electron-withdrawing aromatic ring having a cyano group or a nitro group, and having one radical polymerizable functional group. Examples of the radical polymerizable functional group include functional groups represented by the above formula (10) or formula (11). More specifically, those shown in the above radical polymerizable monomer can be mentioned, and acryloyloxy group and methacryloyloxy group are particularly useful. In addition, a triarylamine structure is highly effective as a charge transporting structure, and in particular, when a compound represented by the structure of the following general formula (1) or (2) is used, electrical characteristics such as sensitivity and residual potential are good. To last.

（式中、Ｒ_１は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ_７（Ｒ_７は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基）、ハロゲン化カルボニル基若しくはＣＯＮＲ_８Ｒ_９（Ｒ_８及びＲ_９は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい）を表わし、Ａｒ_１、Ａｒ_２は置換もしくは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。Ａｒ_３、Ａｒ_４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。）

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

Specific examples of general formulas (1) and (2) are shown below.
In the general formulas (1) and (2), in the substituent of R ₁ , examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. The aralkyl group includes a benzyl group, a phenethyl group, and a naphthylmethyl group, and the alkoxy group includes a methoxy group, an ethoxy group, a propoxy group, and the like. These include a halogen atom, a nitro group, a cyano group, and a methyl group. Substituted with an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group or a naphthyl group, an aralkyl group such as a benzyl group or a phenethyl group, etc. May be.
Of the substituents for R ₁ , particularly preferred are a hydrogen atom and a methyl group.

Ar ₃ and Ar ₄ represent a substituted or unsubstituted aryl group, and examples of the aryl group include a condensed polycyclic hydrocarbon group, a non-fused cyclic hydrocarbon group, and a heterocyclic group.
The condensed polycyclic hydrocarbon group preferably has 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group. , S-indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group , A chrycenyl group, a naphthacenyl group, and the like.

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

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

The aryl group represented by Ar ₃ or Ar ₄ may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group and the like.
(2) Alkyl groups, preferably C1-C12, especially C1-C8, more preferably C1-C4 linear or branched alkyl groups, and these alkyl groups further include a fluorine atom, a hydroxyl group, a cyano group, It may have a phenyl group substituted with a C1-C4 alkoxy group, a phenyl group or a halogen atom, a C1-C4 alkyl group, or a C1-C4 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 ₂ ), and R ₂ represents the alkyl group defined in (2). Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group And a trifluoromethoxy group.
(4) An aryloxy group, and examples of the aryl group include a phenyl group and a naphthyl group. This may contain a C1-C4 alkoxy group, a C1-C4 alkyl group or a halogen atom as a substituent. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.
(5) Alkyl mercapto group or aryl mercapto group, and specific examples include methylthio group, ethylthio group, phenylthio group, p-methylphenylthio group and the like.
(6)

（式中、Ｒ_３及びＲ_４は各々独立に水素原子、前記（２）で定義したアルキル基、またはアリール基を表わす。アリール基としては、例えばフェニル基、ビフェニル基又はナフチル基が挙げられ、これらはＣ１〜Ｃ４のアルコキシ基、Ｃ１〜Ｃ４のアルキル基またはハロゲン原子を置換基として含有してもよい。Ｒ_３及びＲ_４は共同で環を形成してもよい）
具体的には、アミノ基、ジエチルアミノ基、Ｎ−メチル−Ｎ−フェニルアミノ基、Ｎ，Ｎ−ジフェニルアミノ基、Ｎ，Ｎ−ジ（トリール）アミノ基、ジベンジルアミノ基、ピペリジノ基、モルホリノ基、ピロリジノ基等が挙げられる。

(In the formula, R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group defined in (2) above, or an aryl group. Examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group. These may contain a C1-C4 alkoxy group, a C1-C4 alkyl group, or a halogen atom as a substituent. R ₃ and R ₄ may form a ring together)
Specifically, amino group, diethylamino group, N-methyl-N-phenylamino group, N, N-diphenylamino group, N, N-di (tolyl) amino group, dibenzylamino group, piperidino group, morpholino group And pyrrolidino group.

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

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

X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group.
The substituted or unsubstituted alkylene group is a C1-C12, preferably C1-C8, more preferably a C1-C4 linear or branched alkylene group, and these alkylene groups further include a fluorine atom, a hydroxyl group, It may have a cyano group, a C1-C4 alkoxy group, a phenyl group or a halogen atom, a C1-C4 alkyl group, or a phenyl group substituted with a C1-C4 alkoxy group. Specifically, methylene group, ethylene group, n-butylene group, i-propylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxyethylene Group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group and the like.

The substituted or unsubstituted cycloalkylene group is a C5-C7 cyclic alkylene group, and these cyclic alkylene groups have a fluorine atom, a hydroxyl group, a C1-C4 alkyl group, and a C1-C4 alkoxy group. May be. Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.
The substituted or unsubstituted alkylene ether group represents ethyleneoxy, propyleneoxy, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, tripropylene glycol, and the alkylene group of the alkylene ether group is a hydroxyl group, a methyl group, an ethyl group And the like.
The vinylene group is

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

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

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

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

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

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

を表わす。）

Represents. )

  As the compound represented by the above general formula, a compound having a methyl group or an ethyl group as a substituent for Rb and Rc is particularly preferable.

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

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

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

The crosslinkable charge transport layer of the present invention is obtained by curing at least a trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Monofunctional and bifunctional radically polymerizable monomers, functional monomers, and radical polymerization for the purpose of imparting functions such as viscosity adjustment during coating, stress relaxation of the cross-linked charge transport layer, lower surface energy and reduced friction coefficient Can be used in combination. Known radical polymerizable monomers and oligomers can be used.
The described siloxane repeating units: vinyl monomers having a polysiloxane group, such as 20 to 70 acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, diacryloyl polydimethylsiloxane diethyl, Examples include acrylates and methacrylates.

Examples of the radical polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers.
However, if a large amount of monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers are contained, the three-dimensional crosslink density of the crosslinkable charge transport layer is substantially decreased, leading to a decrease in wear resistance. For this reason, the content of these monomers and oligomers is limited to 50 parts by weight or less, preferably 30 parts by weight or less, with respect to 100 parts by weight of the tri- or higher functional radical polymerizable monomer.

  The crosslinked charge transport layer of the present invention is obtained by curing at least a trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Accordingly, a polymerization initiator may be contained in the crosslinking type charge transport layer coating solution in order to allow the curing reaction to proceed efficiently.

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

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2 -Hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2- Acetophenone-based or ketal-based photopolymerization initiators such as methyl-2-morpholino (4-methylthiophenyl) propan-1-one and 1-phenyl-1,2-propane-dione-2- (o-ethoxycarbonyl) oxime , Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether Benzoin ether photopolymerization initiators such as ter, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthones such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Examples of other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzo Ruphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9, Examples thereof include 10-phenanthrene, acridine compounds, triazine compounds, and imidazole compounds. Moreover, what has a photopolymerization promotion 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. The content of the polymerization initiator is 0.5 to 40 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total content having radical polymerizability.

  Furthermore, the crosslinkable charge transport layer coating liquid of the present invention may contain additives such as various plasticizers (for the purpose of stress relaxation and adhesion improvement), leveling agents, and low molecular charge transport materials having no radical reactivity. Can be contained. As these additives, known additives can be used, and as plasticizers, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used, and the amount used is the total solid content of the coating liquid. To 20 wt% or less, preferably 10 wt% or less. As leveling agents, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount used is based on the total solid content of the coating liquid. 3% by weight or less is appropriate.

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

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

  The film thickness of the crosslinked charge transport layer of the present invention is 1 μm or more and 15 μm or less, more preferably 2 μm or more and 8 μm or less. If it is thicker than 15 μm, cracks and film peeling are likely to occur as described above, and if it is 8 μm or less, the margin is further improved, so that the crosslink density can be increased, and material selection and curing that further increases wear resistance. Conditions can be set. On the other hand, the radical polymerization reaction is prone to oxygen inhibition, that is, the surface in contact with the air is not easily cross-linked or non-uniform due to the effect of radical trapping by oxygen. This effect is noticeable when the surface layer is 1 μm or less, and the cross-linked charge transport layer having a thickness of less than this thickness is liable to cause a decrease in wear resistance or uneven wear. In addition, mixing of the lower layer charge transport layer component occurs during the application of the crosslinkable charge transport layer. If the coating thickness of the crosslinkable charge transport layer is thin, contaminants spread throughout the layer, which inhibits the curing reaction and lowers the crosslink density. For these reasons, the cross-linked charge transport layer of the present invention has a good wear resistance and scratch resistance at a film thickness of 1 μm or more, but a portion that is locally scraped to the lower charge transport layer is formed in repeated use. And the wear of the portion increases, and the density unevenness of the halftone image is likely to occur due to the chargeability and sensitivity fluctuation. Therefore, it is desirable that the film thickness of the crosslinkable charge transport layer be 2 μm or more for a longer life and higher image quality.

  In the present invention, the charge generation layer, the charge transport layer, and the crosslinkable charge transport layer are sequentially laminated. When the outermost crosslinkable charge transport layer is insoluble in the organic solvent, the wear resistance, scratch resistance, It is characterized by achieving sex. As a method for testing the solubility in an organic solvent, a drop of an organic solvent having high solubility in a polymer substance, for example, tetrahydrofuran, dichloromethane, or the like, is dropped on the surface layer of the photoconductor, and the surface shape of the photoconductor is dried after natural drying. It can be determined by observing the change with a stereomicroscope. Dissolving photoconductors have a phenomenon that the central part of the droplet becomes concave and the surroundings swell in reverse, the charge transport material precipitates and the turbidity and cloudiness due to crystallization occur, and the surface swells and then shrinks, causing wrinkles Changes such as the phenomenon to be seen. In contrast, an insoluble photoconductor does not exhibit the above-described phenomenon, and does not change at all as before dropping.

  In the constitution of the present invention, in order to make the crosslinkable charge transport layer insoluble in the organic solvent, (1) composition of the crosslinkable charge transport layer coating solution, adjustment of the content ratio thereof, (2) crosslinkable charge Dilution solvent of transport layer coating solution, adjustment of solid content concentration, (3) Selection of coating method of crosslinkable charge transport layer, (4) Control of curing condition of crosslinkable charge transport layer, (5) Charge of lower layer It is important to control these, such as making the transport layer difficult to dissolve, but it is not achieved by a single factor.

  The composition of the crosslinkable charge transport layer coating liquid includes radical polymerization in addition to the above-described trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. When a large amount of additives such as binder resins, antioxidants, and plasticizers that do not have a functional functional group are included, the crosslinking density is reduced, the cured product resulting from the reaction and phase separation of the above additives occur, and the organic solvent It becomes soluble to. Specifically, it is important to suppress the total content to 20% by weight or less with respect to the total solid content of the coating liquid. Further, in order not to dilute the crosslinking density, the total content of monofunctional or bifunctional radical polymerizable monomers, reactive oligomers, and reactive polymers is 20% by weight or less based on the trifunctional radical polymerizable monomers. It is desirable. Further, when a large amount of a radical polymerizable compound having a bifunctional or higher functional charge transporting structure is contained, a bulky structure is fixed in the crosslinked structure by a plurality of bonds, so that distortion is likely to occur. It is easy to become an aggregate. This can cause solubility in organic solvents. Although different depending on the compound structure, the content of the radical polymerizable compound having a bifunctional or higher functional charge transporting structure is preferably 10% by weight or less based on the radical polymerizable compound having a monofunctional charge transporting structure.

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

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

Hereinafter, the electrophotographic photosensitive member of the present invention will be described according to its layer structure.
<About the layer structure of the electrophotographic photoreceptor>
The electrophotographic photosensitive member used in the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an electrophotographic photoreceptor of the present invention. On a conductive support (31), a charge generation layer (35) having a charge generation function and a charge transport layer having a charge transport function ( 37) and a cross-linked charge transport layer (39).

<About conductive support>
As the conductive support (31), a material having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, a metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, oxidation Metal oxide such as indium is deposited or sputtered to form film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. After conversion, a tube that has been subjected to surface treatment such as cutting, superfinishing, or polishing can be used. Further, an endless nickel belt and an endless stainless steel belt disclosed in Japanese Patent Application Laid-Open No. 52-36016 can be used as the conductive support (31).
In addition, the conductive support dispersed in a suitable binder resin and coated on the support can also be used as the conductive support (31) of the present invention.

  Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. Can be mentioned. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

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

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

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

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

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

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

(About charge transport layer)
The charge transport layer (37) is a layer having a charge transport function. A charge transport material having a charge transport function and a binder resin are dissolved or dispersed in an appropriate solvent, and this is coated on the charge generation layer (35) and dried. To form.
As the charge transport material, the electron transport material, hole transport material and polymer charge transport material described in the charge generation layer (35) can be used. As described above, the use of the polymer charge transport material can reduce the solubility of the lower layer when the cross-linked charge transport layer is applied, and is particularly useful.

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

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

If necessary, a plasticizer and a leveling agent can be added.
As a plasticizer that can be used in combination with the charge transport layer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 0 with respect to 100 parts by weight of the binder resin. About 30 parts by weight is appropriate.
Leveling agents that can be used in combination with the charge transport layer include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. The amount used is a binder resin. About 0 to 1 part by weight is appropriate for 100 parts by weight.

  The thickness of the charge transport layer is suitably about 5 to 40 μm, preferably about 10 to 30 μm. On the charge transport layer thus formed, the above-described crosslinkable charge transport layer coating solution is applied, dried as necessary, and a curing reaction is started by external energy of heat or light irradiation, thereby crosslinkable charge. A transport layer is formed.

<About the intermediate layer>
In the photoreceptor of the present invention, an intermediate layer is provided between the charge transport layer and the cross-linked charge transport layer for the purpose of suppressing charge transport layer component mixing into the cross-linked charge transport layer or improving adhesion between the two layers. It is possible. For this reason, as the intermediate layer, those which are insoluble or hardly soluble in the cross-linked charge transport layer coating solution are suitable, and generally a binder resin is used as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a generally used coating method is employed as described above. The thickness of the intermediate layer is suitably about 0.05 to 2 μm.

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

These undercoat layers can be formed using an appropriate solvent and a coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, for the undercoat layer of the present invention, Al ₂ O ₃ provided by anodization, organic substances such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO _2, etc. Those provided with an inorganic material by a vacuum thin film forming method can also be used satisfactorily. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

<Addition of antioxidant to each layer>
Further, in the present invention, in order to improve environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, a cross-linked charge transport layer, a charge transport layer, a charge generation layer, an undercoat layer, an intermediate layer An antioxidant can be added to each layer.

<Image Forming Method and Apparatus>
Next, the image forming method and the image forming apparatus of the present invention will be described in detail with reference to the drawings.
The image forming apparatus of the present invention uses a laminated type photoconductor having a cross-linked charge transport layer with very high wear resistance and scratch resistance on the surface, for example, at least the process of negative charging, image exposure, and development on the photoconductor. After that, the image forming apparatus includes a process of transferring a toner image to an image holding member (transfer paper), fixing, cleaning of the surface of the photosensitive member, charge removal and positive charging, and further provided with a photosensitive member heating unit. In some cases, an image forming method or the like in which an electrostatic latent image is directly transferred to a transfer member and developed does not necessarily have the above-described process arranged on a photosensitive member.

FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus.
A charging charger (3) is used as a means for charging the photoconductor on average. As the charging means, a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or the like is used, and a known system can be used.

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

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

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

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

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

Next, static elimination means is used for the purpose of removing the latent image on the photosensitive member.
As the charge removal means, a charge removal lamp (2) and a charge removal charger are used, and the exposure light source and the charging means can be used respectively.

Next, a positive charging means is used for the purpose of bringing the surface potential of the photosensitive member into a positive polarity state.
As the positive charging means, a positive charging charger (16) is used, and an apparatus equivalent to the negative charging means can be used.

  The charging potential of the photoconductor that is positively charged by the positive charging means is preferably + 100V to + 800V.

  The photoconductor heating means is not particularly limited and may be appropriately selected according to the purpose. (1) A method for forcibly blowing hot air into the surface of the photoconductor or the inside of the photoconductor drum; Examples include a direct heating method provided with a heating means, and among these, the direct heating method in which the photoconductor itself of (2) is provided with a heating means is preferable.

Examples of the direct heating method (2) include a method of directly heating from the inside of the photosensitive drum by incorporating a sheet heating element or a ceramic heating element sandwiching the heating element.
Examples of the heating element include a laminated metal sheet, a polyethylene terephthalate resin or the like as a support, and a heating element such as a nichrome wire.
This makes it possible to heat the photoreceptor uniformly even if any position on the photoreceptor drum stops just below the belt electrode. In addition, since the relative humidity on the surface of the photoconductor can be reduced by heating the photoconductor, a good image can be obtained over the entire image even in a high humidity environment. Therefore, direct heating in which the photoreceptor itself is provided with heating means is most effective. Further, the heating effect can be further enhanced by using an external heater in combination on the photosensitive member.

  As the heating means, a mode in which the photosensitive member is built in the photoreceptor and the photoreceptor is heated from the inside by the heating means is preferable. For example, FIG. 3 is a schematic sectional view showing an example of the electrophotographic photoreceptor of the present invention. This photoreceptor has a photosensitive layer (205) comprising at least a charge generation layer, a charge transport layer and a cross-linked charge transport layer on a support (201), and is in contact with the inner surface of the support (201). A heating means (207) formed by winding a planar heater in a coil shape in a partially contacted state is provided.

  The surface temperature of the photoreceptor is preferably 30 ° C to 65 ° C, more preferably 40 ° C to 60 ° C. It is effective to rotate the photoconductor while keeping the temperature of the photoconductor within the above temperature range from when the power is turned on until image formation.

  The surface temperature of the photoconductor heated by the photoconductor heating means needs to be controlled by attaching one or more sensors at arbitrary locations around the drum. In order to make the temperature of the photoconductor uniform, it is preferable to install the sensors at the central portion and at the three ends along the longitudinal direction of the photoconductor. A commercially available temperature sensor can be used as the sensor. In addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.

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

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

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. Note that “parts” used in the examples all represent parts by weight.

  As an evaluation device, the Ricoh digital copying machine “imageio MP 1350” is modified with a photoconductor unit, and a positive charging device is installed between the static eliminator (static discharge lamp) and the charging device, and a device provided with a photoconductor heating device is used. It was. In the heating device, a planar heating element in which a heating element made of nichrome wire was sandwiched between polyethylene terephthalate resin was inserted inside the support of the obtained photoreceptor, and heating was possible from the inner surface.

Using the evaluation device (photosensitive linear velocity = 630 mm / sec), the charging member is charged with a scorotron charging member (the discharge wire is a tungsten-molybdenum alloy plated with gold having a diameter of 50 μm) under the following charging conditions. 780 nm LD light (image writing by polygon mirror, resolution 1200 dpi) as image exposure light source, development is performed with two-component development using black toner, transfer belt is used as a transfer member, and charge removal is performed using a charge-removing lamp. The member was the same as the charging member and was positively charged under the charging conditions shown in the table below, and 200,000 sheets were continuously printed using a 6% writing rate chart under the following charging conditions. The printing environment is 23 ° C.-55% RH.
(Charging conditions)
Applied voltage to the wire: -6.0 KV
Grid voltage: -860V (the charged potential of the photoreceptor is -850V)
(Positive charging condition)
The battery was positively charged under the conditions shown in the following table.

Before and after printing, an exposed area potential (in this evaluation, an exposed area potential when exposed at a light amount = 0.42 μJ / cm ² ) and a residual potential (potential after neutralization) were measured. For measurement, write light is LD light quantity = 0.42 μJ / cm ² , charging is grid voltage = −860 V, and the applied voltage is set so that the initial charging potential is −850 V, and then black solid writing is continuously printed on 5 sheets. The exposed portion potential of the fifth sheet and the residual potential after printing the fifth sheet were measured. Further, the film thickness of the photoconductor before printing and the film thickness of the photoconductor after printing were measured using an eddy current film thickness measuring apparatus, and the wear amount was calculated from the difference.

<Example 1>
[Conductive layer formation]
An Al cylinder having a diameter of 100 mm and a length of 380 mm was used as a support, and a coating composed of the following materials was applied to the support by a dipping method and heat-cured at 140 ° C. for 30 minutes to form a 15 μm conductive layer.
Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance adjusting pigment: Titanium oxide 2 parts Binder resin: Phenol resin 6 parts Leveling material: Silicone oil 0.001 part Solvent: Methanol / methoxypropanol (0.2 / 0. 8) 20 copies

[Intermediate layer formation]
Next, a solution obtained by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol was applied on this conductive layer by a dipping method, and an intermediate of 0.5 μm was applied. A layer was formed.

[Charge generation layer formation]
Next, 4 parts of oxytitanium phthalocyanine (TiOPc) having strong peaks at 9.0, 14.2, 23.9, and 27.1 degrees with a Bragg angle 2θ ± 0.2 degrees in X-ray diffraction of CuKα And polyvinyl butyral (trade name: ESREC BM2, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone were dispersed in a sand mill apparatus using φ1 mm glass beads for 4 hours, and then 100 parts of ethyl acetate was added to prepare a dispersion for charge generation layer. Prepared. This was applied by an immersion method to form a 0.3 μm charge generation layer.

[Charge transport layer formation]
Next, 9 parts of an amine compound of the following structural formula:

下記構造式のアミン化合物１部、

1 part of an amine compound of the structural formula

とビスフェノールＺポリカーボネート（パンライトＴＳ−２０５０、帝人化成製）１０部をモノクロロベンゼン５０部／ジクロロメタン５０部の混合溶媒に溶解した。なお重量平均分子量は、ＧＰＣ（ゲルパーミエーションクロマトグラフィー）により測定されるポリスチレン換算値とした。この塗料を浸漬法で塗布し１２０℃、２時間乾燥し２０μｍの電荷輸送層を形成した。

And 10 parts of bisphenol Z polycarbonate (Panlite TS-2050, manufactured by Teijin Chemicals) were dissolved in a mixed solvent of 50 parts monochlorobenzene / 50 parts dichloromethane. In addition, the weight average molecular weight was made into the polystyrene conversion value measured by GPC (gel permeation chromatography). This paint was applied by an immersion method and dried at 120 ° C. for 2 hours to form a 20 μm charge transport layer.

[Formation of cross-linked charge transport layer]
On this charge transport layer, a coating solution for a cross-linked charge transport layer having the following composition is spray-coated and naturally dried for 20 minutes, and then a metal halide lamp: 160 W / cm, irradiation distance: 120 mm, irradiation intensity: 500 mW / cm ^2. Irradiation time: Light irradiation was performed under the condition of 60 seconds to cure the coating film. Further, drying was performed at 130 ° C. for 20 minutes, and a 5 μm cross-linked charge transport layer was provided to obtain the electrophotographic photoreceptor of the present invention.

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

  The electrophotographic photosensitive member was mounted on the image forming apparatus, and the photosensitive member charged potential after charging by the positive charging means was evaluated as + 400V.

<Example 2>
The same electrophotographic photosensitive member as in Example 1 was heated to 60 ° C. by the photosensitive member heating means, and the photosensitive member charging potential after charging by the positive charging means was evaluated as + 400V.

<Example 3-1>
Using the same electrophotographic photoreceptor as in Example 1, the photoreceptor was heated to 60 ° C., and the photoreceptor charge potential after charging by the positive charging means was evaluated as + 50V.

<Example 3-2>
Using the same electrophotographic photoreceptor as in Example 1, the photoreceptor was heated to 60 ° C., and the photoreceptor charge potential after charging by the positive charging means was evaluated as + 100V.

<Example 3-3>
Using the same electrophotographic photoreceptor as in Example 1, the photoreceptor was heated to 60 ° C., and the photoreceptor charge potential after charging by the positive charging means was evaluated as + 800V.

<Example 3-4>
Using the same electrophotographic photoconductor as in Example 1, the photoconductor was heated to 60 ° C., and the photoconductor charge potential after charging by the positive charging means was evaluated as + 850V.

<Example 4-1>
Using the same electrophotographic photoconductor as in Example 1, the photoconductor charge potential after charging by the positive charging means was set to +400 V, and the photoconductor was heated to 35 ° C. for evaluation.

<Example 4-2>
Using the same electrophotographic photoconductor as in Example 1, the photoconductor charge potential after charging by the positive charging means was set to +400 V, and the photoconductor was heated to 40 ° C. for evaluation.

<Example 4-3>
Using the same electrophotographic photosensitive member as in Example 1, the photosensitive member charged potential after charging by the positive charging means was set to +400 V, and the photosensitive member was heated to 65 ° C. for evaluation.

<Example 5-1>
A trifunctional or higher functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for a crosslinkable charge transporting layer of Example 1 is converted into a bifunctional radical polymerizable compound having no charge transporting structure described below. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 10 parts of the monomer was used.
10 parts of bifunctional radically polymerizable monomer having no charge transporting structure (1,6-hexanediol diacrylate, manufactured by Wako Pure Chemical Industries, Ltd.)
Molecular weight: 226, number of functional groups: bifunctional, molecular weight / number of functional groups = 113

  Using the obtained electrophotographic photosensitive member, the surface potential after charging by the positive charging means was evaluated as + 400V.

<Example 5-2>
The trifunctional or higher functional radical polymerizable monomer having no charge transport structure contained in the coating liquid for the crosslinkable charge transport layer of Example 1 is replaced with the following monomer, and the photopolymerization initiator is replaced with 1 part of the following compound: An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the above was changed.
Trifunctional or more radical polymerizable monomer having no charge transport structure 10 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
Photoinitiator 1 part 2,2-Dimethoxy-1,2-diphenylethane-1-one (Irgacure 651, manufactured by Ciba Specialty Chemicals)

  Using the obtained electrophotographic photosensitive member, the surface potential after charging by the positive charging means was evaluated as + 400V.

<Example 5-3>
Electrophotography as in Example 1 except that the trifunctional or higher functional radical-polymerizable monomer having no charge transporting structure contained in the coating liquid for the crosslinkable charge transporting layer of Example 1 is replaced with the following monomer. A photoconductor was prepared.
Trifunctional or more radical polymerizable monomer having no charge transport structure 10 parts Caprolactone-modified dipentaerythritol hexaacrylate (KAYARAD DPCA-120, manufactured by Nippon Kayaku Co., Ltd.)
Molecular weight: 1947, number of functional groups: 6 functions, molecular weight / number of functional groups = 325

  Using the obtained electrophotographic photosensitive member, the surface potential after charging by the positive charging means was evaluated as + 400V.

<Example 6>
The radical polymerizable compound having a monofunctional charge transporting structure contained in the coating liquid for a crosslinkable charge transporting layer of Example 1 is exemplified by Compound No. 1. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 144 parts and 10 parts were used.

  Using the obtained electrophotographic photosensitive member, the surface potential after charging by the positive charging means was evaluated as + 400V.

<Comparative Example 1>
The electrophotographic photosensitive member of Example 1 was evaluated without being charged by a positive charging means.

<Comparative Example 2-1>
An Al cylinder having a diameter of 100 mm and a length of 380 mm was used as a support, and a coating composed of the following materials was applied to the support by a dipping method and heat-cured at 140 ° C. for 30 minutes to form a 15 μm conductive layer.
Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance adjusting pigment: Titanium oxide 2 parts Binder resin: Phenol resin 6 parts Leveling material: Silicone oil 0.001 part Solvent: Methanol / methoxypropanol (0.2 / 0. 8) 20 copies

Next, a solution obtained by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol was applied onto this conductive layer by a dipping method, and an intermediate of 0.5 μm was applied. A layer was formed.
Next, 4 parts of oxytitanium phthalocyanine (TiOPc) having strong peaks at 9.0, 14.2, 23.9, and 27.1 degrees with a Bragg angle 2θ ± 0.2 degrees in X-ray diffraction of CuKα And polyvinyl butyral (trade name: ESREC BM2, manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone were dispersed in a sand mill apparatus using φ1 mm glass beads for 4 hours, and then 100 parts of ethyl acetate was added to prepare a dispersion for charge generation layer. Prepared. This was applied by an immersion method to form a 0.3 μm charge generation layer.
Next, 9 parts of an amine compound of the following structural formula:

下記構造式のアミン化合物１部

1 part of amine compound of the following structural formula

とビスフェノールＺポリカーボネート（パンライトＴＳ−２０５０、帝人化成製）１０部をモノクロロベンゼン５０部／ジクロロメタン５０部の混合溶媒に溶解した。なお重量平均分子量は、ＧＰＣ（ゲルパーミエーションクロマトグラフィー）により測定されるポリスチレン換算値とした。この塗料を浸漬法で塗布し１２０℃、２時間乾燥し２５μｍの電荷輸送層を形成した。
これによって得られた架橋型電荷輸送層を有しない感光体を、正帯電手段による帯電後の表面電位を＋４００Ｖとして評価した。

And 10 parts of bisphenol Z polycarbonate (Panlite TS-2050, manufactured by Teijin Chemicals) were dissolved in a mixed solvent of 50 parts monochlorobenzene / 50 parts dichloromethane. In addition, the weight average molecular weight was made into the polystyrene conversion value measured by GPC (gel permeation chromatography). This paint was applied by an immersion method and dried at 120 ° C. for 2 hours to form a 25 μm charge transport layer.
The photoreceptor without the cross-linked charge transport layer thus obtained was evaluated with a surface potential after charging by a positive charging means of + 400V.

<Comparative Example 2-2>
Using the electrophotographic photoreceptor used in Comparative Example 2-1, the surface potential after charging by the positive charging means was set to +400 V, and the photoreceptor temperature was evaluated to be 60 ° C.

<Comparative Example 3>
Using the electrophotographic photosensitive member used in Example 1, the positive charging means was not used, and the photosensitive member temperature was evaluated as 60 ° C.

The result of Examples 1-6 and Comparative Examples 1-3 is shown.
〔Evaluation criteria〕
A: Very good B: Practical use is possible.
X: Not sufficient for long-term repeated stability.

  As described above in detail and clearly from the specific description, according to the present invention, in the image forming apparatus including at least the negative charging unit, the exposure unit, the developing unit, the transfer unit, and the photoconductor, the negative charging unit is provided. A positive charging means for imparting a positive charge having a polarity opposite to that of the means to the photosensitive member and a photosensitive member heating means. The positive charging means causes the charging potential of the photosensitive member to be in a positively charged state. A positive charge is applied to the photosensitive member, and the photosensitive member is a photosensitive member in which at least a charge generating layer, a charge transporting layer, and a cross-linked charge transporting layer are sequentially laminated on a conductive support. A highly durable and high-performance image forming apparatus having high electrical properties and good electrical characteristics can be obtained.

  The image forming apparatus using the electrophotographic photosensitive member of the present invention is widely used in full-color copying machines, full-color laser printers, full-color plain paper fax machines and the like using a direct or indirect electrophotographic multicolor image developing system.

1 is an example of a cross-sectional view of an electrophotographic photosensitive member of the present invention. 1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. It is a schematic sectional drawing which shows an example of the heating means of the image forming apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charge charger 5 Image exposure part 6 Developing unit 7 Pre-transfer charger 8 Registration roller 9 Transfer body 10 Transfer charger 11 Separation charger 12 Separation claw 13 Pre-cleaning charger 14 Fur brush 15 Cleaning blade 16 Positive charging charger 31 Conductive support 33 Photosensitive layer 35 Charge generation layer 37 Charge transport layer 39 Cross-linked charge transport layer 201 Support 205 Photosensitive layer 207 Heating means

Claims (9)

An image forming apparatus comprising an electrophotographic photosensitive member and at least a negative charging unit, an exposure unit, a developing unit, a transfer unit, a cleaning unit, a neutralizing unit, and a positive charging unit. A positive charge is applied to the photoconductor so that the potential is in a positive charge state, and the photoconductor is formed by sequentially laminating at least a charge generation layer, a charge transport layer, and a crosslinkable charge transport layer on a conductive support. An image forming apparatus which is a photoconductor. The image forming apparatus according to claim 1, further comprising a heating unit configured to heat the photosensitive member. 3. The image forming apparatus according to claim 1, wherein a positive charge is applied by the positive charging unit so that a surface potential of the photosensitive member becomes +100 V to +800 V. 4. The image forming apparatus according to claim 2, wherein the photosensitive member is heated to a temperature of 40 ° C. to 60 ° C. by the heating unit. The crosslinkable charge transport layer is formed by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. 6. The functional group of a tri- or higher functional radical polymerizable monomer having no charge transport structure has at least one functional group selected from an acryloyloxy group and a methacryloyloxy group. The image forming apparatus according to any one of the above. The image forming apparatus according to claim 1, wherein the functional group of the radical polymerizable compound having a monofunctional charge transporting structure is an acryloyloxy group or a methacryloyloxy group. The image forming apparatus according to claim 1, wherein the curing unit of the cross-linked charge transport layer is a heating or light energy irradiation unit. The image forming apparatus according to claim 1, wherein at least charging, image exposure, development, and transfer are repeatedly performed using the electrophotographic photosensitive member.

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