JP2005107401A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having high sensitivity, high electrostatic stability even when the photoreceptor is repeatedly used, and little environmental dependency and realizing both of image quality stability and high durability, and to provide an electrophotographic apparatus and a process cartridge using the photoreceptor. <P>SOLUTION: In the electrophotographic photoreceptor having a charge generation layer, a charge transport layer and a crroslinked charge transport layer sequentially layered on at least a conductive support, the photoreceptor is characterized in that: the charge generation layer contains a titanyl phthalocyanine crystal having a specified grain size and showing a specified diffraction peak in terms of a diffraction peak (±0.2°) of the Bragg angle 2θ to CuKα rays (at 1.542 Å wavelength); the crroslinked charge transport layer is formed by curing at least a radical polymerizable monomer having three or more functional groups and no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure; and the layer has 1 μm to 10 μm film thickness. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photosensitive member in which a charge generation layer containing at least a specific titanyl phthalocyanine crystal, a charge transport layer, and a cross-linked charge transport layer are sequentially laminated on the photosensitive layer, an image forming apparatus using the same, and an image The present invention relates to a process cartridge for a forming apparatus.

  In recent years, the development of information processing system machines using electrophotography has been remarkable, and in particular, laser printers and digital copiers that record information using light by converting information into digital signals have significantly improved print quality and reliability. . These laser printers and digital copiers that are rapidly spreading are required to have higher speed and smaller size as well as higher image quality. Furthermore, recently, the demand for full-color laser printers and full-color digital copiers capable of full-color printing is rapidly increasing. When full-color printing is performed, it is necessary to superimpose toner images of at least four colors. In particular, speeding up and downsizing of the apparatus are even more important issues. In order to realize high speed and downsizing of the apparatus, it is necessary to improve the sensitivity of the electrophotographic photosensitive member used for them and to reduce the diameter of the photosensitive member. However, in this case, since the photoconductor is used in a severer situation, the replacement speed of the conventional photoconductor is greatly increased. Therefore, in order to realize high speed and downsizing of the apparatus, it is indispensable to make the photoconductor used at the same time highly durable or highly stable. The durability of the photoconductor is determined by the image quality. In particular, in laser printers and digital copiers using reversal development that are used today, the background contamination that counts innumerable black dots on a white background is the biggest factor that determines the service life. ing. Therefore, in order to realize high speed and downsizing of the apparatus, it is necessary to increase the life of the photoconductor by suppressing the occurrence of background stains at the same time as increasing the sensitivity of the photoconductor.

  A charge generating material having a high quantum efficiency is indispensable for increasing the sensitivity of the photoreceptor required to cope with the higher speed of the apparatus. As an organic high-sensitivity photoconductor, the charge generation material has an XRD (diffractive peak (± 0.2 °) with a Bragg angle 2θ in CuKα ray (wavelength 1.542 mm)) having a maximum diffraction peak at least 27.2 °. Having titanyl phthalocyanine is widely used and is very effective.

For example, the above titanyl phthalocyanine crystal is described in Patent Document 1, and further, a photoconductor and an image forming apparatus using the same as a charge generating substance are disclosed. By using this titanyl phthalocyanine crystal, it is possible to obtain a stable electrophotographic photosensitive member by reducing charging and reducing the environmental dependency of the dark part potential or the exposed part potential even by repeated use without losing high sensitivity.
However, by using the titanyl phthalocyanine crystal in the charge generation layer, high sensitivity, suppression of background contamination, and stabilization of charging can be realized, but if the electric field strength increases due to repeated use of the photoreceptor, the background contamination will be reduced. The suppressive effect and charging stability are drastically reduced, and a long life has not been achieved. In particular, when used in a high-speed machine or a color machine, the usage environment of the photoconductor is severe and the influence of wear is remarkably increased, so that the background stain is likely to occur and the image quality stability is poor. The conventional methods for improving the wear resistance of the photoreceptor can improve the wear resistance, but can cause a sudden increase in residual potential, or image defects and blurring due to poor cleaning. Since the photoconductor must be replaced due to the influence, it has not been possible to extend the service life.

  As described above, the photoreceptor using the titanyl phthalocyanine has a concern that the background stains are remarkably generated due to aggregation of the titanyl phthalocyanine or a decrease in charge due to fatigue. In particular, background contamination is a major factor that determines the life of a photoconductor as described above, and a photoconductor using the above-mentioned titanyl phthalocyanine increases the influence of background contamination even if the speed of the apparatus can be increased. The stability was poor, and both high speed and long life were not realized. Further, the titanyl phthalocyanine tends to cause charge deterioration and residual potential increase after repeated use, and has a tendency to have a large environmental dependency, and the image quality stability is not sufficient. For this reason, conventional photoconductors using the above-mentioned titanyl phthalocyanine have accelerated image quality deterioration when used in high-speed machines, and the replacement frequency of photoconductors has become faster, and it has not been possible to provide stable images over a long period of time. It was.

  On the other hand, in order to increase the life of an electrophotographic photoreceptor, a method is known in which a protective layer is formed on the surface of the photoreceptor to increase the wear resistance. Background contamination that determines the life of the photoreceptor is promoted by fatigue or wear of the photoreceptor due to repeated use. By forming a protective layer on the surface of the photoconductor, suppressing wear of the photoconductor due to repeated use can suppress an increase in the electric field strength caused by the use, thereby reducing the occurrence of background stains. This is a very effective means for extending the service life.

  Techniques for improving the abrasion resistance of the photosensitive layer include (i) using a curable binder in the crosslinkable charge transport layer (see, for example, Patent Document 2), and (ii) using a polymer charge transport material. (For example, refer to Patent Document 3), and (iii) a structure in which an inorganic filler is dispersed in a crosslinked charge transport layer (for example, refer to Patent Document 4). Among these technologies, those using the curable binder (i) have poor compatibility with the charge transport material, and the residual potential increases due to impurities such as polymerization initiators and unreacted residues, resulting in a decrease in image density. Tends to occur. In addition, although the polymer type charge transport material (ii) can improve the abrasion resistance to some extent, the durability required for the organic photoreceptor is not fully satisfied. Not reached. In addition, polymer charge transport materials are difficult to polymerize and purify, and it is difficult to obtain a high-purity material. Therefore, it is difficult to stabilize electrical characteristics between materials. Furthermore, production problems such as high viscosity of the coating solution may occur. The dispersion of the inorganic filler (iii) exhibits higher abrasion resistance than a photoreceptor in which a normal low molecular charge transport material is dispersed in an inert polymer, but the charge present on the surface of the inorganic filler. The residual potential increases due to the trap, and the image density tends to decrease. In addition, when the unevenness of the inorganic filler and the binder resin on the surface of the photoconductor is large, defective cleaning may occur, which may cause toner filming and image flow. With the technologies (i), (ii), and (iii), the total durability including the electrical durability and mechanical durability required for the organic photoreceptor is sufficiently satisfied. Has not reached.

Furthermore, a photoreceptor containing a polyfunctional acrylate monomer cured product for improving the wear resistance and scratch resistance of (i) is also known (see Patent Document 5). However, in this photoreceptor, although there is a description that the polyfunctional acrylate monomer cured product is contained in the protective layer provided on the photosensitive layer, the protective layer may contain a charge transport material. However, there is a problem of compatibility with the cured product when a cross-linked charge transport layer contains a low-molecular charge transport material. As a result, precipitation of a low-molecular charge transport material and white turbidity occur, and not only the image density is lowered but also the mechanical strength is lowered due to the increase of the exposed portion potential.
Furthermore, since this photoconductor specifically reacts with the monomer in a state containing a polymer binder, the three-dimensional network structure does not proceed sufficiently, and the crosslink density becomes dilute, resulting in a dramatic wear resistance. Has not yet been able to demonstrate.

  As a wear resistance technology for a photosensitive layer that replaces these, a charge transport layer formed by using a coating liquid comprising a monomer having a carbon-carbon double bond, a charge transport material having a carbon-carbon double bond, and a binder resin. It is known to provide (for example, refer to Patent Document 6). This binder resin is thought to play a role of improving the adhesion between the charge generation layer and the curable charge transport layer, and further mitigating the internal stress of the film during thick film curing, and has a carbon-carbon double bond. These are broadly classified into those having reactivity with the charge transfer agent and those having no reactivity with the double bond. This photoconductor is remarkably compatible with wear resistance and good electrical properties, but when a non-reactive binder resin is used, the binder resin, the monomer and the charge transport agent are used. The compatibility with the cured product produced by this reaction is poor, and layer separation occurs in the cross-linked charge transport layer, which may cause scratches and sticking of external additives and paper powder in the toner. In addition, as described above, the three-dimensional network structure does not proceed sufficiently, and the cross-linking density becomes dilute. In addition, what is specifically described as the monomer used in this photoreceptor is bifunctional, and in these respects, it has not yet been satisfactory in terms of wear resistance. Even when a reactive binder is used, the molecular weight of the cured product is increased, but the number of intermolecular crosslinks is small, and it is difficult to achieve a balance between the amount of the charge transporting substance and the crosslink density. Abrasion was not sufficient.

A photosensitive layer containing a compound obtained by curing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule is also known (see, for example, Patent Document 7). This photosensitive layer has high hardness because the crosslink density can be increased, but since the bulky hole transporting compound has two or more chain polymerizable functional groups, distortion occurs in the cured product and internal stress increases. In some cases, the crosslinked surface layer is liable to crack or peel off when used for a long period of time.
Even in the conventional photoconductors having a cross-linked photosensitive layer in which a charge transporting structure is chemically bonded, it cannot be said that the present invention has sufficient comprehensive characteristics.

As described above, even when the device can cope with speeding up of the apparatus by using the photoconductor including the titanyl phthalocyanine having high sensitivity in the charge generation layer, the image quality is deteriorated due to the occurrence of background contamination, and the photoconductor is frequently used. Even if it is necessary to replace it, or a protective layer is formed to improve wear resistance, the effects of increased residual potential and image quality degradation due to poor cleaning may increase, resulting in high speed and color machines. It has not been possible to achieve both the required high sensitivity and long life of the photoreceptor. Accordingly, there has been a strong demand for an electrophotographic photosensitive member and an electrophotographic apparatus capable of outputting a stable image over a long period of time in response to the recent demand for high speed or colorization in laser printers and digital copying machines.
JP 2001-187794 A JP 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent No. 3262488 Japanese Patent No. 3194392 JP 2000-66425 A JP-A-6-293769 JP-A-8-110649 Japanese Patent Publication No. 5-60503 Japanese Examined Patent Publication No. 6-45770 JP 52-36016 A JP-A-1-299874 (Patent No. 2512081) Japanese Patent Laid-Open No. 3-269064 (Japanese Patent No. 2854682) Japanese Patent Laid-Open No. 2-8256 (Japanese Patent Publication No. 7-91486) JP-A 64-17066 (Japanese Patent Publication No. 7-97221) Japanese Patent Laid-Open No. 11-5919 (Patent No. 3003664) Japanese Patent Laid-Open No. 3-255456 (Patent No. 3005052) JP-A-5-134437 (Patent No. 3196260) Japanese Patent Laid-Open No. 61-239248 Moser et al., “Phthalocyanine Compounds” (1963) Moser et al., “The Phthalocyanines” (1983) Japan Hardcopy '89 Proceedings p. 103 1989

  The object of the present invention is to increase the speed, color and size of the device, so that it has high sensitivity, high electrostatic stability even when used repeatedly, and less environmental dependency, thereby stabilizing the image quality. It is an object of the present invention to provide an electrophotographic photosensitive member that achieves both high performance and high durability, an electrophotographic apparatus using the same, and a process cartridge for an electrophotographic apparatus.

  As a result of intensive investigations to obtain an electrophotographic photosensitive member capable of high-speed correspondence, high image quality stability even with repeated use, and having a long life, the following configuration is obtained. It has been found that this can be achieved by satisfying the requirements, and the present invention has been completed.

(1) In an electrophotographic photosensitive member in which a charge generation layer, a charge transport layer, and a cross-linked charge transport layer are sequentially laminated on at least a conductive support, a Bragg angle with respect to CuKα rays (wavelength: 1.542 mm) in the charge generation layer As the 2θ diffraction peak (± 0.2 °), it has a maximum diffraction peak at least 27.2 °, and further has major peaks at 9.4 °, 9.6 °, 24.0 °, and The lowest diffraction peak has a peak at 7.3 °, no peak between the peak at 7.3 ° and the peak at 9.4 °, and a peak at 26.3 ° A trifunctional or higher-functional radically polymerizable monomer containing a titanyl phthalocyanine crystal having an average primary particle size of 0.25 μm or less, and the crosslinked charge transport layer does not have a charge transport structure, and a monofunctional charge transport Radicals with sexual structure An electrophotographic photosensitive member formed by curing a polymerizable compound, wherein the cross-linked charge transport layer has a thickness of 1 μm or more and 10 μm or less.

(2) In the titanyl phthalocyanine crystal, the peak intensity at 26.3 ° is in the range of 0.1 to 5% with respect to the peak intensity at the maximum diffraction peak of 27.2 °. Electrophotographic photoreceptor.

(3) Dispersion was carried out until the average particle size of the titanyl phthalocyanine crystal particles was 0.3 μm or less and the standard deviation thereof was 0.2 μm or less, and then filtered through a filter having an effective pore size of 3 μm or less. The electrophotographic photoreceptor according to (1) or (2), wherein the electrophotographic photoreceptor is used and coated with a charge generation layer.

(4) The titanyl phthalocyanine crystal particle has a maximum diffraction peak at 7.0 to 7.5 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542 波長) of CuKα. A crystalline peak of amorphous titanyl phthalocyanine or low crystalline titanyl phthalocyanine having an average particle size of 0.1 μm or less and a half-width of the diffraction peak of 1 ° or more is converted with an organic solvent in the presence of water, (1) or (2) above, wherein titanyl phthalocyanine after crystal conversion is fractionated and filtered from an organic solvent before the average particle size after conversion grows larger than 0.25 μm. Electrophotographic photoreceptor.

(5) The electrophotographic photosensitive member according to any one of (1) to (4), wherein the crosslinkable charge transport layer is insoluble in an organic solvent.

(6) The functional group of a tri- or higher functional radical polymerizable monomer having no charge transport structure used in the cross-linked charge transport layer is an acryloyloxy group and / or a methacryloyloxy group ( The electrophotographic photosensitive member according to any one of 1) to (5).

(7) The ratio of the molecular weight to the number of functional groups (molecular weight / number of functional groups) in the trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure used for the crosslinkable charge transporting layer is 250 or less. The electrophotographic photosensitive member according to any one of (1) to (6).

(8) The functional group of the radical polymerizable compound having a monofunctional charge transporting structure used in the crosslinkable charge transporting layer is an acryloyloxy group or a methacryloyloxy group. 7) The electrophotographic photoreceptor according to any one of 7).

(9) The charge transport structure of the radically polymerizable compound having a monofunctional charge transport structure used in the crosslinkable charge transport layer is a triarylamine structure. The electrophotographic photosensitive member according to any one of the above.

(10) The radical polymerizable compound having a monofunctional charge transporting structure used in the crosslinkable charge transporting layer is at least one of the following general formula (1) or (2): The electrophotographic photosensitive member according to any one of 1) to (9).
(Wherein R ₁ is a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen A carbonyl group or —CONR ₈ R ₉ (R ₈ and R ₉ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Ar ₁ and Ar ₂ each represent a substituted or unsubstituted arylene group and may be the same or different.Ar ₃ may be the same or different from each other. , Ar ₄ is a substituted or unsubstituted a X is a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, A sulfur atom or 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.)

(11) The radically polymerizable compound having a monofunctional charge transporting structure used for the crosslinkable charge transporting layer is at least one of the following general formula (3): The electrophotographic photosensitive member according to any one of 10).

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

(12) The proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the crosslinkable charge transport layer is 30 to 70% by weight based on the total amount of the crosslinkable charge transport layer. The electrophotographic photosensitive member according to any one of (1) to (11).

(13) The component ratio of the radical polymerizable compound having a monofunctional charge transporting structure used in the crosslinkable charge transport layer is 30 to 70% by weight based on the total amount of the crosslinkable charge transport layer. The electrophotographic photosensitive member according to any one of (1) to (12).

(14) The electrophotographic photosensitive member according to any one of (1) to (13), wherein the curing means for the crosslinkable charge transport layer is a heating or light energy irradiation means.

(15) The electrophotographic photosensitive member according to any one of (1) to (14), wherein the charge transport layer contains a polymer charge transport material.

(16) In an image forming apparatus comprising at least a charging unit, an exposure unit, a developing unit, a transfer unit, and an electrophotographic photosensitive member, the electrophotographic photosensitive member according to any one of (1) to (15). An image forming apparatus characterized by being an electrophotographic photosensitive member.

(17) The image forming apparatus as described in (16) above, wherein a plurality of image forming elements comprising at least charging means, exposure means, developing means, transfer means, and electrophotographic photosensitive member are arranged.

(18) A cartridge in which an electrophotographic photosensitive member and at least one means selected from charging means, exposure means, developing means, and cleaning means are mounted, and the cartridge is detachable from the apparatus main body. The image forming apparatus as described in (16) or (17) above.

(19) In a process cartridge for an image forming apparatus in which at least one unit selected from a charging unit, an exposure unit, a developing unit, and a cleaning unit and an electrophotographic photosensitive member are integrated, the electrophotographic photosensitive member is (1 A process cartridge for an image forming apparatus, which is the electrophotographic photosensitive member according to any one of (1) to (15).

  According to the present invention, even if it is used repeatedly over a long period of time, the abnormal image due to defective cleaning, cracks, scratches, film peeling, etc. is not generated according to the present invention in order to stabilize the image quality and increase the life required for high-speed machines and color machines. In addition, the electrophotographic photosensitive member can suppress background stains, increase the potential stability, and maintain image quality stability under any environment, and as a result, can stably provide high-quality images over a long period of time. Is obtained. As a result, not only the electrophotographic photosensitive member but also a process cartridge for an electrophotographic apparatus using the same and an electrophotographic apparatus can be provided with a long life and high stability.

Hereinafter, the electrophotographic photoreceptor of the present invention will be described in detail.
The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member in which a charge generation layer, a charge transport layer, and a cross-linked charge transport layer are sequentially laminated on at least a conductive support, and CuKα rays (wavelength 1) are included in the charge generation layer. As a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to .542 Å), it has a maximum diffraction peak at least 27.2 ° and is further dominant at 9.4 °, 9.6 °, and 24.0 °. It has a peak and has a peak at 7.3 ° as the lowest diffraction peak, no peak between the 7.3 ° peak and the 9.4 ° peak, and 26.3 A trifunctional or higher functional radical-polymerizable monomer having a peak at ° and containing a titanyl phthalocyanine crystal having an average primary particle size of 0.25 μm or less, and wherein the cross-linked charge transport layer does not have at least a charge transport structure And monofunctional charge transport It is formed by curing a radically polymerizable compound having a structure, and the film thickness of the crosslinkable charge transport layer is 1 μm or more and 10 μm or less.

  In the present invention, the charge generation layer contains the titanyl phthalocyanine crystal (pigment), which is the specific crystal type, to reduce the charge and environmental dependence as well as to increase the sensitivity, and in the method as described below, By reducing the size of the pigment (average particle size is 0.25 μm or less) and reducing aggregates, the effect of background stains is reduced. In addition, the wear resistance is improved while being electrostatically stable and poorly cleaned. By combining with the above-mentioned cross-linked charge transport layer that can suppress the effect of image blur, it is possible to suppress background stains by repeated use over a long period of time, and to achieve both electrostatic stability and image quality stability. As a result, it has become possible to provide stable image quality over a long period of time even when used in high-speed and color machines.

Below, the manufacturing method of the titanyl phthalocyanine crystal | crystallization contained in a charge generation layer among the components of this invention is demonstrated in detail.
First, a synthetic method for synthesizing a titanyl phthalocyanine crystal having a specific crystal type used in the present invention will be described.
Methods for synthesizing phthalocyanines have been known for a long time, and are described in Non-Patent Document 1, Non-Patent Document 2, Patent Document 8, and the like. For example, as a first method, a mixture of phthalic anhydrides, metal or metal halide and urea is heated in the presence or absence of a high boiling point solvent. In this case, a catalyst such as ammonium molybdate is used in combination as necessary. As a second method, phthalonitriles and metal halides are heated in the presence or absence of a high boiling point solvent. This method is used for phthalocyanines that cannot be produced by the first method, such as aluminum phthalocyanines, indium phthalocyanines, oxovanadium phthalocyanines, oxotitanium phthalocyanines, zirconium phthalocyanines, and the like. The third method is to first react phthalic anhydride or phthalonitrile with ammonia to produce an intermediate such as 1,3-diiminoisoindoline, and then react with a metal halide in a high boiling solvent. It is a method to make it. The fourth method is a method in which phthalonitriles and a metal alkoxide are reacted in the presence of urea or the like. In particular, the fourth method does not cause chlorination (halogenation) to the benzene ring, and is a very useful method for synthesizing an electrophotographic material, and can be used effectively in the present invention.

  As described above, as a method for synthesizing the titanyl phthalocyanine crystal used in the present invention, a method in which titanium halide is not used as a raw material is preferably used as described in Patent Document 8. This method makes it possible to synthesize halogenated free titanyl phthalocyanine crystals. If a titanyl phthalocyanine crystal contains a halogenated titanyl phthalocyanine crystal as an impurity, the electrostatic characteristics of a photoreceptor using the crystal often have adverse effects such as a decrease in photosensitivity and a decrease in chargeability (see Non-Patent Document 3). . In the present invention, in order to suppress the occurrence of background stains and realize both high sensitivity and high durability, the halogenated-free titanyl phthalocyanine crystal as described in Patent Document 1 is mainly targeted. These materials are effectively used.

  Next, a method for synthesizing amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) will be described. In this method, phthalocyanines are dissolved in sulfuric acid, diluted with water and reprecipitated, and an acid paste method or an acid slurry method can be used. As a specific method, the above synthetic crude product is dissolved in 10-50 times the amount of concentrated sulfuric acid, and if necessary, insoluble matter is removed by filtration or the like, and this is sufficiently cooled to 10-50 times the amount of sulfuric acid. Slowly throw it into water or ice water to reprecipitate titanyl phthalocyanine. The precipitated titanyl phthalocyanine is filtered, washed with ion-exchanged water and filtered, and this operation is sufficiently repeated until the filtrate becomes neutral. Finally, after washing with ion-exchanged water, filtration is performed to obtain a water paste having a solid concentration of about 5 to 15 wt%. The amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) used in the present invention is produced by the above method. In this case, the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) is at least 7.0 to 7 as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (wavelength 1.542Å) of CuKα. It is preferable to have a maximum diffraction peak at 5 °. In particular, the half width of the diffraction peak is more preferably 1 ° or more. Further, the average particle size of the primary particles is preferably 0.1 μm or less.

  Next, a crystal conversion method will be described. In the present invention, titanyl phthalocyanine crystals are synthesized from at least two crystal conversion steps.

  First, the first crystal conversion method will be described. In the first crystal conversion, the amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) is used as a diffraction peak (± 0.2 °) of Bragg angle 2θ with respect to the characteristic X-ray of CuKα (wavelength 1.542 mm). It has a maximum diffraction peak at 2 °, a major peak at 9.4 °, 9.6 ° and 24.0 °, and a peak at 7.3 ° as the lowest diffraction peak. And a titanyl phthalocyanine crystal having no peak between the peak at 7.3 ° and the peak at 9.4 ° and not having a peak at 26.3 °.

  As a specific method, the amorphous form of the titanyl phthalocyanine (low crystalline titanyl phthalocyanine) is mixed and stirred with an organic solvent in the presence of water without drying, thereby obtaining the crystal form.

  At this time, any organic solvent can be used as long as the desired crystal form can be obtained. In particular, tetrahydrofuran, toluene, methylene chloride, carbon disulfide, orthodichlorobenzene, 1,1, Good results are obtained when one selected from 2-trichloroethane is selected. These organic solvents are preferably used alone, but two or more of these organic solvents may be mixed or used in combination with other solvents.

  It is desirable that the amount of the organic solvent used for crystal conversion is 10 times or more, preferably 30 times or more the weight of amorphous titanyl phthalocyanine. This is because crystal conversion is caused quickly and sufficiently, and an effect of sufficiently removing impurities contained in amorphous titanyl phthalocyanine is exhibited. The amorphous titanyl phthalocyanine used here is prepared by the acid paste method, but it is desirable to use one obtained by sufficiently washing sulfuric acid as described above. When crystal conversion is performed under conditions where sulfuric acid remains, sulfate ions remain in the crystal particles, and the completed crystals cannot be completely removed even by an operation such as washing with water. When sulfate ions remain, preferable results cannot be obtained, such as a decrease in sensitivity and a decrease in chargeability of the photoreceptor. For example, Patent Document 9 (Comparative Example) describes a method in which titanyl phthalocyanine dissolved in sulfuric acid is added to an organic solvent together with ion-exchanged water to perform crystal conversion. At this time, although a crystal similar to the X-ray diffraction spectrum of the titanyl phthalocyanine crystal used in the present invention can be obtained, since the sulfate ion concentration in titanyl phthalocyanine is high and the light attenuation characteristic (photosensitivity) is poor, The method for producing titanyl phthalocyanine of the present invention is not good.

  The crystal conversion method described above is a crystal conversion method according to Patent Document 1 described above. In the charge generation material contained in the photoconductor used in the electrophotographic apparatus of the present invention, by making the particle size of the titanyl phthalocyanine crystal finer, the effect of suppressing scumming is enhanced, and the stability of the image quality and the extension of the lifetime are achieved. It becomes effective.

  There are two main methods for controlling the particle size of titanyl phthalocyanine crystals contained in the photosensitive layer. One is a method of synthesizing a crystal containing no particles larger than 0.25 μm when synthesizing titanyl phthalocyanine crystal particles, and the other is a coarse particle larger than 0.25 μm after the titanyl phthalocyanine crystal is dispersed. It is a method to remove. Of course, using both in combination has a greater effect.

First, a method for synthesizing fine-particle titanyl phthalocyanine crystals will be described.
In order to make the particle size of the titanyl phthalocyanine crystal finer, the inventors have observed that the above-mentioned amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine) has a primary particle size of 0.1 μm or less (its Fig. 1 shows an example of a TEM image of amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine), where the scale bar in the figure is 0.2 µm. ), It was found that during crystal conversion, the crystal was converted as the crystal grew. Usually, in this type of crystal conversion, a sufficient crystal conversion time is ensured due to fear of remaining of the raw material, and after the crystal conversion is sufficiently performed, filtration is performed to obtain a titanyl phthalocyanine crystal having a desired crystal type. Is what you get. For this reason, even though a raw material having sufficiently small primary particles is used as a raw material, a crystal having a large primary particle (approximately 0.3 to 0.5 μm) is obtained as a crystal after crystal conversion. FIG. 2 shows an example of a TEM image of a crystal of ruphthalocyanine in the crystal after the crystal conversion. Note that the scale bar in the figure indicates 0.2 μm.

  On the other hand, in the present invention, the range in which crystal growth hardly occurs at the time of crystal conversion (the size of the amorphous titanyl phthalocyanine particles observed in FIG. 1 is kept in a small size, approximately 0.2 μm or less after crystal conversion. In other words, it is intended to obtain a titanyl phthalocyanine crystal having the smallest primary particle size as much as possible by determining when the crystal conversion is completed. The particle size after crystal conversion increases in proportion to the crystal conversion time. For this reason, as described above, it is important to increase the efficiency of crystal conversion and complete it in a short time. There are several important points for this.

  One is to select an appropriate crystal conversion solvent as described above to enhance the crystal conversion efficiency. The other is to use strong agitation to bring the solvent into contact with the titanyl phthalocyanine aqueous paste (raw material prepared as described above) in order to complete the crystal conversion in a short time. Specifically, it is possible to achieve crystal conversion in a short time by using a propeller with a very strong stirring force or using a strong stirring (dispersing) means such as a homogenizer (homomixer). is there. Under these conditions, it is possible to obtain a titanyl phthalocyanine crystal in a state in which crystal conversion is sufficiently performed and crystal growth does not occur without remaining raw materials.

  In addition, since the crystal grain size and the crystal conversion time are in a proportional relationship as described above, a method of immediately stopping the reaction when a predetermined reaction (crystal conversion) is completed is also an effective means. As the above-mentioned means, it is possible to immediately add a large amount of a solvent in which crystal conversion hardly occurs after crystal conversion as described above. Examples of the solvent that hardly causes crystal transformation include alcohol-based and ester-based solvents. Crystal conversion can be stopped by adding about 10 times these solvents to the crystal conversion solvent.

  The crystals produced in this way have a smaller primary particle size, which is advantageous for suppressing background stains. However, when considering the next step for pigment preparation (pigment filtration step) and the dispersion stability in the dispersion liquid. If it is too small, side effects may occur. That is, when the primary particles are very fine, there arises a problem that the filtration time becomes very long in the step of filtering the primary particles. In addition, if the primary particles are too small, the surface area of the pigment particles in the dispersion increases, so the possibility of reaggregation of the particles increases, and conversely, the occurrence of soiling may be promoted. . Therefore, the suitable particle size of the pigment particles is in the range of about 0.05 μm to 0.2 μm.

  FIG. 3 shows a TEM image of a titanyl phthalocyanine crystal when crystal conversion is performed in a short time. In addition, the scale bar in a figure shows 0.2 micrometer. Unlike the case of FIG. 2, the particle size is small and almost uniform, and no coarse particles as observed in FIG. 2 are observed.

  The average particle size referred to here is a volume average particle size obtained by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba Seisakusho), which corresponds to 50% of the cumulative distribution. It is calculated as a particle size (Median system). However, this method may not be able to detect a very small amount of coarse particles. Therefore, in order to obtain more details, it is important to observe the titanyl phthalocyanine crystal powder or dispersion directly with an electron microscope and determine its size. It is.

  As a result of further examination of the micro-defects by further observation of the dispersion, the above phenomenon is explained as follows. Usually, in the method of measuring the average particle size, when an extremely large particle is present in several% or more, the presence can be detected, but it is about 1% or less of the whole. If the amount becomes too small, the measurement will be below the detection limit. As a result, the presence of coarse particles is not detected only by measuring the average particle size, making it difficult to interpret the above minute defects.

  4 and 5 show photographs observing the state of two types of dispersions in which only the dispersion time is changed while fixing the dispersion conditions. A photograph of a dispersion liquid having a short dispersion time under the same conditions is shown in FIG. 4, and it is observed that coarse particles remain as compared with FIG. 5 having a long dispersion time (the black particles in FIG. 4 are coarse particles). ).

  The average particle size and particle size distribution of these two types of dispersions were measured according to a known method using a commercially available particle size distribution measuring device (manufactured by Horiba: ultracentrifugal automatic particle size distribution measuring device, CAPA700). The result is shown in FIG. “A” in FIG. 6 corresponds to the dispersion shown in FIG. 4, and “B” corresponds to the dispersion shown in FIG. When both are compared, there is almost no difference in the particle size distribution. In addition, the average particle diameter values of the two are “A” of 0.29 μm and “B” of 0.28 μm, and taking into account measurement errors, there is no difference between the two.

  Therefore, it is understood that the remaining amount of coarse particles cannot be detected only by the definition of the known average particle size (average particle size), and it is not possible to cope with the recent high-resolution negative / positive development. . It was found that the presence of this minute amount of coarse particles can be recognized for the first time by observing the coating solution with a microscope or the like.

  When dispersing a titanyl phthalocyanine crystal having a large particle size, in order to reduce the particle size after dispersion (0.25 μm or less, preferably 0.2 μm or less), dispersion is performed by giving a strong share. If necessary, dispersion is performed by applying strong energy for pulverizing the primary particles. As a result, a part of the particles are easily transferred to a crystal form which is not a desired crystal form.

  In response to this fact, producing as small primary particles as possible during the first crystal conversion is an effective means for reducing the particle size after dispersion. For this purpose, in order to complete the crystal conversion in a short time while selecting the appropriate crystal conversion solvent as described above and improving the crystal conversion efficiency, the solvent and titanyl phthalocyanine water paste (the raw material prepared as described above) are used. ) Is effective to use strong agitation in order to sufficiently bring

  By employing such a crystal conversion method, a titanyl phthalocyanine crystal having a small primary particle size (0.25 μm or less, preferably 0.2 μm or less) can be obtained. In addition to the technique described in Patent Document 1, the use of the above-described technique (crystal conversion method for obtaining a fine titanyl phthalocyanine crystal) as necessary is effective for enhancing the effect of the present invention. Means.

  Subsequently, the crystallized titanyl phthalocyanine crystal is immediately filtered to be separated from the crystal conversion solvent. This filtration is performed by using a filter of an appropriate size. At this time, it is most preferable to use vacuum filtration.

  Thereafter, the separated titanyl phthalocyanine crystal is heat-dried as necessary. Any known dryer can be used for heating and drying, but a blower-type dryer is preferable when the drying is performed in the atmosphere. Furthermore, drying under reduced pressure is a very effective means in order to increase the drying speed and to exhibit the effects of the present invention more remarkably. In particular, this is an effective means for a material that decomposes at a high temperature or changes its crystal form. In particular, it is effective to dry in a state where the degree of vacuum is higher than 10 mmHg.

  The thus obtained titanyl phthalocyanine crystal having a specific crystal type is extremely useful as a charge generating material for an electrophotographic photoreceptor. However, as described above, the crystal form is unstable, and the crystal form is easily transferred when a dispersion is prepared. However, by synthesizing primary particles into infinitely small particles as in the present invention, a dispersion with a small average particle diameter can be prepared without giving an excessive share during the preparation of the dispersion, and the crystal type is also extremely high. It can be produced stably (without changing the synthesized crystal form).

  Next, the second crystal conversion method will be described. The second crystal conversion is a step of further crystal conversion using the titanyl phthalocyanine crystal (dry powder) prepared by the first crystal conversion. Specific methods include two methods.

  One is a method of treating the previously prepared titanyl phthalocyanine crystal in an organic solvent. The organic solvent used is a solvent that can convert a crystal form having a maximum diffraction peak at 27.2 ° and no peak at 26.3 ° into a crystal form having a diffraction peak at 26.3 °. Any one can be used, but aromatic hydrocarbons such as toluene and xylene, ketones such as acetone and 2-butanone, halogenated hydrocarbons such as methylene chloride and chloroform, and cyclic ethers such as tetrahydrofuran are preferably used. It is done. Regarding the treatment of the organic solvent, the titanyl phthalocyanine crystal may be simply immersed in the organic solvent as it is, but the treatment time can be shortened by using auxiliary means such as stirring and ultrasonic application together. ,It is valid. After the treatment with an organic solvent, the target titanyl phthalocyanine crystal can be obtained by separating by filtration and drying again.

  As another method, a crystal transformation is performed by applying a mechanical shearing force to the previously prepared titanyl phthalocyanine crystal. At this time, an organic solvent may be used in combination, but it is desirable to perform the treatment in a dry state without using it together. As a method to be used, dry milling using a ball mill, attritor, vibration mill, kneader, or the like, or simply dry milling using a mixer is also effective. Moreover, you may use inorganic salts, such as salt, as an adjuvant in the case of dry milling. When an auxiliary agent is used, a washing step for removing inorganic salts is necessary after the crystal conversion treatment. Thus, the target titanyl phthalocyanine crystal can be obtained.

  Whichever method is used, it is important that the peak intensity at 26.3 ° is in the range of 0.1 to 5% with respect to the peak intensity at the maximum diffraction peak of 27.2 °. The peak intensity of 26.3 ° is determined by the treatment time in the solvent or the treatment time giving mechanical shearing force, but the state of the raw material used (the titanyl phthalocyanine crystal produced by the first crystal conversion) (for example, It is desirable to determine the treatment time through preliminary experiments because it varies depending on the size and hardness of the powder.

  The thus obtained titanyl phthalocyanine crystal having a specific crystal type is extremely useful as a charge generating material for an electrophotographic photoreceptor. As described above, when a titanyl phthalocyanine crystal having a large primary particle is dispersed, it is dispersed with a strong share, so that it has a defect that the crystal form is easily transferred. However, by synthesizing primary particles into infinitely small particles as in the present invention, a dispersion with a small average particle diameter can be prepared without giving an excessive share during the preparation of the dispersion, and the crystal type is also extremely high. It can be produced stably (without changing the synthesized crystal form).

  A general method is used for the preparation of the dispersion, and the titanyl phthalocyanine crystal is dispersed in a suitable solvent together with a binder resin as necessary by using a ball mill, an attritor, a sand mill, a bead mill, an ultrasonic wave, or the like. It is obtained. At this time, the binder resin may be selected depending on the electrostatic characteristics of the photoreceptor, and the solvent may be selected depending on the wettability to the pigment, the dispersibility of the pigment, and the like.

  A titanyl phthalocyanine crystal having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to CuKα rays (wavelength 1.542 mm) is caused by stress such as thermal energy and mechanical share. It is known to easily undergo crystal transition to other crystal types. This tendency does not change in the titanyl phthalocyanine crystal used in the present invention. In other words, in order to produce a dispersion containing fine particles, it is necessary to devise a dispersion method, but the stability of the crystal form and the micronization tend to be in a trade-off relationship. Although there are methods for avoiding this by optimizing the dispersion conditions, all of them make the manufacturing conditions extremely narrow, and a simpler method is desired. In order to solve this problem, the following method is also an effective means.

Next, a method for removing coarse particles after dispersing titanyl phthalocyanine crystals will be described.
That is, it is a method in which a dispersion liquid in which particles are made as fine as possible within a range in which crystal transition does not occur is prepared and then filtered through an appropriate filter. This method is a very effective means in that it can remove a minute amount of coarse particles that cannot be visually observed (or cannot be detected by particle size measurement), and that the particle size distribution is uniform. Specifically, the dispersion prepared as described above is filtered through a filter having an effective pore size of 3 μm or less, more preferably 1 μm or less, thereby completing the dispersion. Also by this method, a dispersion containing only titanyl phthalocyanine crystals having a small particle size (0.25 μm or less, preferably 0.2 μm or less) can be produced, and a photoreceptor using this is mounted on an electrophotographic apparatus. As a result, it is possible to increase the margin against soiling, which is effective for enhancing the durability of the photoreceptor.

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

  The filter for filtering the dispersion varies depending on the size of coarse particles to be removed, but according to the study by the present inventors, as a photoreceptor used in an electrophotographic apparatus that requires a resolution of about 600 dpi. The presence of coarse particles exceeding 3 μm at least affects the image. Therefore, a filter with an effective pore size of 3 μm or less should be used. More preferably, a filter having an effective pore size of 1 μm or less is used. Regarding this effective pore size, the finer the particle, the more effective the removal of coarse particles, but there is an appropriate size. If the effective pore size is too small, it will take time to filter, the filter will be clogged, too much load will be applied when using a pump, etc. Cannot sort the necessary pigment particles. As a matter of course, a material having resistance to the solvent used in the dispersion to be filtered is used as the material of the filter used here.

  By adding such an operation of filtering the dispersion, coarse particles can be removed, and as a result, background contamination generated on the photoconductor using the dispersion can be reduced. As described above, the finer the filter, the greater the effect (reliable), but there are cases where the pigment particles themselves are filtered. In such a case, using the titanyl phthalocyanine primary particles described above in combination with the technique for refining and synthesizing the particles produces a very large effect.

  That is, (i) by synthesizing and using refined titanyl phthalocyanine, the dispersion time can be shortened and the dispersion stress can be reduced, and the possibility of crystal transition in dispersion is reduced. (Ii) Since the size of the coarse particles remaining after dispersion is smaller than that in the case where the particles are not refined, a smaller filter can be used, and the effect of removing the coarse particles becomes more reliable. In addition, the amount of titanyl phthalocyanine particles to be removed is reduced, and there is little change in the composition of the dispersion before and after filtration, which enables stable production. (Iii) As a result, the manufactured photoreceptor is stably manufactured with high resistance to soiling.

  The intensity ratio of the 26.3 ° peak intensity to the 27.2 ° peak intensity in the titanyl phthalocyanine crystal of the present invention will be described.

An X-ray diffraction spectrum is measured with a general X-ray diffractometer in a powder state of the titanyl phthalocyanine crystal to be used. Baseline correction is performed on the obtained spectrum, and then a peak intensity of 26.3 ± 0.2 ° and a peak intensity of 27.2 ± 0.2 ° are obtained. Using the value, the value obtained by dividing the peak intensity of 26.3 ± 0.2 ° by the peak intensity of 27.2 ± 0.2 ° is the peak intensity ratio in the present invention.
Peak intensity ratio (%) =
(26.3 ± 0.2 ° peak intensity / 27.2 ± 0.2 ° peak intensity) × 100

  When the peak intensity ratio is 1% or less, it may be difficult to correct the baseline in measurement over a wide range. In that case, the intensity ratio can be obtained more accurately by narrowing the measurement range (for example, measuring within a range of 25 to 30 °) and performing remeasurement.

Next, the other cross-linked charge transport layer in the present invention will be described.
The cross-linked charge transport layer reduces the effects of abrasion caused by repeated use of the photoconductor, increases the aging stain stability, and further increases the electrostatic stability and image quality stability to improve aging stability and durability. It is formed for the purpose of achieving both.

  Scratches formed on the surface of the photosensitive member and foreign matters (toner, toner external additives, carrier, paper dust, etc.) adhering to the surface decrease the cleaning property of the photosensitive member and significantly reduce the image quality stability. Therefore, in order to achieve high durability of the photoconductor, it is important not only to increase the wear resistance, but also to minimize the effects of scratches and filming on the surface of the photoconductor. It is preferable to form a highly elastic and smooth surface layer.

  Since the cross-linked charge transport layer formed on the surface of the present invention has a cross-linked structure obtained by curing a tri- or higher functional radical polymerizable monomer, a three-dimensional network structure is developed, and the cross-link density is very high. An elastic surface layer can be obtained, and it is uniform and smooth, and high wear resistance and scratch resistance are achieved. In this way, it is important to increase the crosslink density on the surface of the photoreceptor, that is, the number of crosslink bonds per unit volume. However, since a large number of bonds are instantaneously formed in the curing reaction, internal stress due to volume shrinkage occurs. Since this internal stress increases as the film thickness of the crosslinkable charge transport layer increases, cracks and film peeling tend to occur when the entire charge transport layer is cured. Even if this phenomenon does not appear initially, it may be likely to occur over time due to repeated use in the electrophotographic process and the influence of charging, development, transfer, cleaning hazards and thermal fluctuations.

  Methods for solving this problem include (i) introducing a polymer component into the crosslinked layer and the crosslinked structure, (ii) using a large amount of monofunctional and bifunctional radically polymerizable monomers, and (iii) forming a flexible group. Although the directionality which makes a cured resin layer soft, such as using the polyfunctional monomer which has, is mentioned, the crosslink density of a bridge | crosslinking layer becomes thin in any case, and remarkable wear resistance is not achieved. On the other hand, the photoconductor of the present invention is provided with a cross-linked charge transport layer having a high cross-linking density and having a three-dimensional network structure developed on the charge transport layer with a film thickness of 1 μm or more and 10 μm or less. No film peeling occurs and very high wear resistance is achieved. By selecting a film thickness of the crosslinkable charge transport layer of 2 μm or more and 8 μm or less, in addition to further improving the margin for the above problem, a material selection for increasing the crosslink density that leads to further improvement in wear resistance. Is possible.

  The reason why the photoconductor of the present invention can suppress cracking and film peeling is that the cross-linked charge transport layer can be made thin, so that the internal stress does not increase, and since the charge transport layer is provided in the lower layer, the surface of the cross-linked charge transport layer This is because internal stress can be relaxed. For this reason, it is not necessary to contain a large amount of polymer material in the cross-linked charge transport layer, and the polymer material and radical polymerizable composition (radical polymerizable monomer or radical polymerizable compound having a charge transport structure) generated at this time. Scratches and toner filming due to incompatibility with the cured product resulting from this reaction are unlikely to occur. Further, when a thick film over the entire charge transport layer is cured by light energy irradiation, light transmission from the absorption by the charge transport structure to the inside is limited, and a phenomenon in which the curing reaction does not proceed sufficiently may occur. In the crosslinked charge transport layer of the present invention, since it is a thin film having a thickness of 10 μm or less, the curing reaction proceeds uniformly to the inside, and high wear resistance is maintained inside as well as the surface. In addition, in the formation of the crosslinkable charge transport layer of the present invention, in addition to the trifunctional radical polymerizable monomer, a radical polymerizable compound having a monofunctional charge transporting structure is contained, which is the trifunctional Incorporated into the cross-linking bond at the time of curing the above radical polymerizable monomer. On the other hand, when a low molecular charge transport material having no functional group is contained in the cross-linked surface layer, precipitation of the low molecular charge transport material and white turbidity occur due to its low compatibility, and the cross-linked surface layer The mechanical strength also decreases. On the other hand, when a bifunctional or higher-functional charge transporting compound is used as the main component, the crosslink structure is fixed by a plurality of bonds and the crosslink density is further increased, but the charge transporting structure is very bulky, so that the cured resin structure is distorted. Becomes very large, which increases the internal stress of the cross-linked charge transport layer.

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

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

Next, the constituent materials of the crosslinkable charge transport layer coating solution of the present invention will be described.
The trifunctional or higher functional radical polymerizable monomer having no charge transporting property used in the present invention is a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano group. And a monomer having no electron transport structure such as an electron-withdrawing aromatic ring having a nitro group and having three or more radical polymerizable functional groups. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and is capable of radical polymerization. Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.

(I) 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 represents an —S— group.)

  Specific examples of these substituents include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamide group, and a vinyl thioether group.

(Ii) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = C (Y) -X ₂ -... Formula 11
(In the formula, Y is an aryl group such as an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, or a naphthyl group. Group, halogen atom, cyano group, nitro group, alkoxy group such as methoxy group or ethoxy group, -COOR ₁₁ group (R ₁₁ is a hydrogen atom, an alkyl such as an optionally substituted methyl group or ethyl group) Group, an aralkyl group such as benzyl or phenethyl group which may have a substituent, an aryl group such as phenyl group or naphthyl group which may have a substituent, or -CONR ₁₂ R ₁₃ (R ₁₂ and R ₁₃ is a hydrogen atom, which may have a substituent an alkyl group such as methyl group and ethyl group, which may have a substituent group benzyl group, naphthylmethyl group or an aralkyl group such as a phenethyl group, or, A phenyl group which may have a substituent, an aryl group such as phenyl or naphthyl, which may be the same or different from each other.) Further, X ₂ is identical substituents and single and X ₁ of the formula 10 Represents a bond or an alkylene group, provided that at least one of Y and X ₂ is an oxycarbonyl group, a cyano group, an alkenylene group, 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 alkyl groups such as halogen atom, nitro group, cyano group, methyl group, and ethyl group, methoxy group, and ethoxy group. And an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group and a naphthyl group, and an aralkyl group such as a benzyl group and a phenethyl group.

  Among 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, as the radical polymerizable monomer used in the present invention, for example, trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, HPA modified trimethylolpropane triacrylate, ethylene oxide (EO) modified trimethylolpropane tri Acrylate, propylene oxide (PO) modified trimethylolpropane triacrylate, caprolactone modified trimethylolpropane triacrylate, HPA modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, epichlorohydrin (ECH) ) Modified glycerol triacrylate, EO modified Lyserol triacrylate, PO-modified glycerol triacrylate, tris (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 phosphate triacrylate, 2,2,5,5, -tetrahydroxy Methylcyclopentanone tetraacrylate, etc. These are, may be used in combination alone or two or more types.

  The trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the present invention has a molecular weight relative to the number of functional groups in the monomer in order to form a dense crosslink in the crosslinkable charge transport layer. The ratio (molecular weight / functional group number) is preferably 250 or less. Further, when this ratio is larger than 250, the cross-linked charge transport layer is soft and wear resistance is somewhat lowered. Therefore, among the monomers exemplified above, monomers having a modifying group such as HPA, EO, PO are extremely It is not preferable to use a compound having a long modifying group alone. Further, the proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the crosslinkable charge transport layer is 20 to 80% by weight, preferably 30 to 70% by weight based on the total amount of the crosslinkable charge transport layer. %. When the monomer component is less than 20% by weight, the three-dimensional crosslink density of the crosslinkable charge transport layer is small, and a drastic improvement in wear resistance is not achieved as compared with the case of using a conventional thermoplastic binder resin. On the other hand, if it 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 those shown in the above radical polymerizable monomer, and acryloyloxy group and methacryloyloxy group are particularly useful. In addition, a triarylamine structure has a high effect 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 Is well maintained.

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

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

Ar ₃ and Ar ₄ are substituted or unsubstituted aryl groups, and examples of the aryl group include fused polycyclic hydrocarbon groups, non-fused cyclic hydrocarbon groups, and heterocyclic groups.

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

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

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

The aryl group represented by Ar ₃ or Ar ₄ may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group and the like.

(2) Alkyl groups, preferably C ₁ -C _12, especially C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkyl groups, and these alkyl groups further contain fluorine atoms , a hydroxyl group, a cyano group, an alkoxy group of C ₁ -C _4, a phenyl group or a halogen atom, which may have a phenyl group substituted by an alkoxy group C ₁ -C ₄ alkyl or C ₁ -C ₄ Good. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-ethoxyethyl Group, 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group and the like.

(3) An alkoxy group (—OR ₂ ), and R ₂ represents the alkyl group defined in (2). Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group And a trifluoromethoxy group.

(4) An aryloxy group, and examples of the aryl group include a phenyl group and a naphthyl group. It may contain an alkoxy group having C ₁ -C _4, alkyl group, or a halogen atom C ₁ -C ₄ as a substituent. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.

(5) Alkyl mercapto group or aryl mercapto group, and specific examples include methylthio group, ethylthio group, phenylthio group, p-methylphenylthio group and the like.

(6)
(In the formula, R ₃ and R ₄ each independently represents a hydrogen atom, an alkyl group defined in (2) above, or an aryl group. Examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group. these C ₁ -C ₄ alkoxy groups, C ₁ -C good .R ₃ and R ₄ may contain as alkyl group or a halogen atom substituents ₄ may be linked to form a ring.)
Specifically, amino group, diethylamino group, N-methyl-N-phenylamino group, N, N-diphenylamino group, N, N-di (tolyl) amino group, dibenzylamino group, piperidino group, morpholino group And pyrrolidino group.

(7) An alkylenedioxy group or an alkylenedithio group such as a methylenedioxy group or a methylenedithio group.

(8) Substituted or unsubstituted styryl group, substituted or unsubstituted β-phenylstyryl group, diphenylaminophenyl group, ditolylaminophenyl group, and the like.

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

  X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group.

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

The substituted or unsubstituted cycloalkylene group is a C _{5 to} C ₇ cyclic alkylene group, and these cyclic alkylene groups include a fluorine atom, a hydroxyl group, a C _{1 to} C ₄ alkyl group, and a C _{1 to} C ₄ alkyl group. It may have an alkoxy group. Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.

  The substituted or unsubstituted alkylene ether group represents ethyleneoxy, propyleneoxy, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, tripropylene glycol, alkylene ether group alkylene group is hydroxyl group, methyl group, ethyl group, etc. You may have the substituent of.

The vinylene group is
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 those similar to the alkylene ether group of 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).

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

  As the compound represented by the general formula (3), compounds having a methyl group or an ethyl group as substituents for Rb and Rc are 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 radically polymerizable 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 An oligomer can be used in combination. Known radical polymerizable monomers and oligomers can be used.

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

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

  Examples of the functional monomer include those substituted with a fluorine atom such as octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, 2-perfluoroisononylethyl acrylate, Patent Document 10, Siloxane repeating unit described in Patent Document 11: 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 vinyl monomers, acrylates and methacrylates.

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

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

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

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

  These polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is 0.5 to 40 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total content having radical polymerizability.

  Furthermore, the crosslinkable charge transport layer coating liquid of the present invention may contain additives such as various plasticizers (for the purpose of stress relaxation and adhesion improvement), leveling agents, and low molecular charge transport materials having no radical reactivity. Can be contained. As these additives, known additives can be used, and as plasticizers, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used, and the amount used is the total solid content of the coating liquid. To 20 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. The amount is preferably 3% by weight or less.

  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. And ethers such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene, aromatics such as benzene, toluene and xylene, cellosolves such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These solvents may be used alone or in combination of two or more. The dilution ratio with the solvent varies depending on the solubility of the composition, the coating method, and the target film thickness, and is arbitrary. The coating can be performed using a dip coating method, spray coating, bead coating, ring coating method or the like.

In the present invention, after applying such a 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 distortion, a large number of unreacted residues, and reaction termination terminals are generated in the cross-linked charge transport layer. In order to advance the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 100 ° C. and then heating to 100 ° C. or more. As the energy of light, UV irradiation light sources such as high-pressure mercury lamps and metal halide lamps, which mainly have an emission wavelength in ultraviolet light, can be used, but a visible light source can also be selected according to the absorption wavelength of radically polymerizable substances and photopolymerization initiators. Is possible. Irradiation light amount is 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, it takes time for the curing reaction is less than 50 mW / cm ^2. If it is higher than 1000 mW / cm ^2, the progress of the reaction becomes non-uniform, and local flaws are generated on the surface of the cross-linked charge transport layer, or many unreacted residues and reaction termination ends are generated. In addition, internal stress increases due to rapid crosslinking, which causes cracks and film peeling. Examples of radiation energy include those using electron beams. Among these energies, those using heat and light energy are useful because of the ease of reaction rate control and the simplicity of the apparatus.

  The film thickness of the crosslinked charge transport layer of the present invention is 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less. If it is thicker than 10 μm, cracks and film peeling are likely to occur as described above, and if it is 8 μm or less, the margin is further improved, so that the crosslink density can be increased, and material selection and curing that further increases wear resistance. Conditions can be set. On the other hand, the radical polymerization reaction is prone to oxygen inhibition, that is, the surface in contact with the air is not easily cross-linked or non-uniform due to the effect of radical trapping by oxygen. This effect appears remarkably when the surface layer is less than 1 μm, and a cross-linked charge transport layer having a thickness less than this thickness tends 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-linkable charge transport layer of the present invention has good wear resistance and scratch resistance at a film thickness of 1 μm or more, but it can be locally scraped to the lower charge transport layer in repeated use. The wear of the portion increases, and the density unevenness of the halftone image tends 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 up, the charge transport material precipitates and becomes cloudy or cloudy due to crystallization, and the surface swells and then shrinks, causing wrinkles Changes such as phenomena are observed. 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, (i) composition of the crosslinkable charge transport layer coating solution, adjustment of the content ratio thereof, (ii) crosslinkable charge Dilution solvent of transport layer coating solution, adjustment of solid content concentration, (iii) Selection of coating method of crosslinkable charge transport layer, (iv) Control of curing condition of crosslinkable charge transport layer, (v) 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 an 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. To insolubilize in an organic solvent, the heat curing conditions are preferably 100 to 170 ° C. and 10 minutes to 3 hours, and the curing conditions by UV light irradiation are 50 to 1000 mW / cm ² and 5 seconds to 5 minutes. In addition, it is desirable to control the temperature rise to 50 ° C. or less to suppress non-uniform curing reaction.

  In the structure of the present invention, an example of a method for making the crosslinkable charge transport layer insoluble in an organic solvent is, for example, an acrylate monomer having three acryloyloxy groups and a triaryl having one acryloyloxy group as a coating solution. In the case of using an amine compound, the ratio of use is 7: 3 to 3: 7, and a polymerization initiator is added in an amount of 3 to 20% by weight based on the total amount of these acrylate compounds, and a solvent is added to the coating solution. To prepare. For example, in the charge transport layer that is the lower layer of the cross-linked charge transport layer, when the surface layer is formed by spray coating using a triarylamine donor as the charge transport material and polycarbonate as the binder resin, the above coating is used. As the solvent of the liquid, tetrahydrofuran, 2-butanone, ethyl acetate and the like are preferable, and the use ratio is 3 to 10 times the total amount of the acrylate compound.

  Next, for example, the prepared coating solution is applied by spraying or the like on a photoreceptor in which an undercoat layer, a charge generation layer, and the charge transport layer are sequentially laminated on a support such as an aluminum cylinder. Thereafter, it is naturally dried or dried at a relatively low temperature for a short time (25 to 80 ° C., 1 to 10 minutes) and cured by UV irradiation or heating.

For UV irradiation, it uses a metal halide lamp, illuminance 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, for example, the case of irradiation with UV light of 200 mW / cm ^2, for example upon curing, the drum of a plurality of lamps What is necessary is just to irradiate the circumferential direction uniformly for about 30 seconds. At this time, the drum temperature is controlled so as not to exceed 50 ° C.

In the case of thermosetting, the heating temperature is preferably 100 to 170 ° C. For example, when a blowing oven is used as a heating means and the heating temperature is set to 150 ° C, the heating time is 20 minutes to 3 hours.
After completion of curing, the photosensitive member of the present invention is obtained by further heating at 100 to 150 ° C. for 10 to 30 minutes to reduce the residual solvent.

Next, the electrophotographic photoreceptor of the present invention will be described in detail with reference to the drawings.
FIG. 7 is a cross-sectional view showing a configuration example of the electrophotographic photosensitive member of the present invention. On the conductive support 31, a charge generation layer 35 mainly composed of a charge generation material and a charge transport material as a main component. The charge transport layer 37 is laminated, and the cross-linked charge transport layer 39 is laminated on the outermost surface of the photoreceptor. An intermediate layer may be laminated between the crosslinkable charge transport layer 39 and the charge transport layer 37, and an undercoat layer may be laminated between the conductive support 31 and the charge generation layer 35. Effective for stabilizing image quality.

Examples of the conductive support 31 include those having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, indium oxide, etc. The metal oxide of the above is coated with film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate made of aluminum, aluminum alloy, nickel, stainless steel or the like and extruded by drawing or drawing. After pipe formation, surface treatment pipes such as cutting, superfinishing, and polishing can be used. Further, the endless nickel belt and the endless stainless steel belt disclosed in Patent Document 12 can also be used as the conductive support 31.

  Of these, a cylindrical support made of aluminum, which can be easily subjected to the anodic oxide film treatment, can be most preferably used. As used herein, aluminum includes both pure aluminum and aluminum alloys. Specifically, JIS 1000, 3000, and 6000 series aluminum or aluminum alloy is most suitable. The anodized film is obtained by anodizing various metals and various alloys in an electrolyte solution. Among them, a film called anodized aluminum or an aluminum alloy that has been anodized in an electrolyte solution is used in the present invention. Is the most suitable. In particular, it is excellent in preventing point defects (black spots, background stains) that occur when used in reversal development (negative / positive development).

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

  In addition, the conductive support 31 of the present invention can be used in which conductive powder is dispersed in a suitable binder resin and coated on the support. 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. It is done. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  Furthermore, it is electrically conductive by a heat shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the conductive support 31 of the present invention.

  Next, the photosensitive layer will be described. As described above, the laminated type composed of the charge generation layer 35 and the charge transport layer 37 exhibits excellent characteristics in sensitivity and durability, and is used favorably.

  The charge generation layer 35 has, as a charge generation material, a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to a characteristic X-ray (wavelength 1.542 mm) of CuKα. Furthermore, it has major peaks at 9.4 °, 9.6 °, and 24.0 °, and has a peak at 7.3 ° as the lowest diffraction peak, and a peak at 7.3 °. A titanyl phthalocyanine crystal having no peak between the peaks at 9.4 ° and having a peak at 26.3 ° and an average primary particle size of 0.25 μm or less is preferably used. A titanyl phthalocyanine crystal having a ratio of a peak intensity of 3 ° to a peak intensity of 27.2 ° of 0.1 to 5% is particularly preferably used. The details of these titanyl phthalocyanine crystals are as described above.

  In the charge generation layer 35, the pigment is dispersed in a suitable solvent together with a binder resin, if necessary, using a ball mill, an attritor, a sand mill, an ultrasonic wave, etc., and this is coated on a conductive support and dried. Is formed.

  As the binder resin used for the charge generation layer 35 as necessary, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicon resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly-N -Vinylcarbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulosic resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. Can be mentioned. The amount of the binder resin is 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generation material.

  Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. As a coating method for the coating solution, a dip coating method, spray coating, beat coating, nozzle coating, spinner coating, ring coating, or the like can be used. The film thickness of the charge generation layer 35 is preferably about 0.01 to 5 μm, more preferably 0.1 to 2 μm.

  The charge transport layer 37 can be formed by dissolving or dispersing a charge transport material and a binder resin in a suitable solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.

Charge transport materials include hole transport materials and electron transport materials.
Examples of the electron transporting material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

  Examples of hole transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc. Other known materials may be mentioned. These charge transport materials may be used alone or in combination of two or more.

  Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarate, 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, phenol resin And thermoplastic or thermosetting resins such as alkyd resins.

  For the charge transport layer 37, a polymer charge transport material having a function as a charge transport material and a function of a binder resin is also preferably used. A charge transport layer composed of these polymer charge transport materials is particularly useful because it can reduce the solubility of the lower layer when the crosslinked charge transport layer is applied. As the polymer charge transport material, known materials can be used, and in particular, a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used. Among these, polymer charge transport materials represented by the formulas (I) to (X) are preferably used, and these are exemplified below and specific examples are shown.

In the formula, R ₁ , R ₂ and R ₃ are each independently a substituted or unsubstituted alkyl group or a halogen atom, R ₄ is a hydrogen atom or a substituted or unsubstituted alkyl group, and R ₅ and R ₆ are substituted or unsubstituted. Substituted aryl group, o, p and q are each independently an integer of 0 to 4, k and j are compositions, 0.1 ≦ k ≦ 1, 0 ≦ j ≦ 0.9, and n is the number of repeating units Represents an integer of 5 to 5000. X represents an aliphatic divalent group, a cycloaliphatic divalent group, or a divalent group represented by the following general formula. In the formula (I), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

R ₁₀₁ and R ₁₀₂ each independently represents a substituted or unsubstituted alkyl group, aryl group or halogen atom. l and m are integers of 0 to 4, Y is a single bond, a linear, branched or cyclic alkylene group having 1 to 12 carbon atoms, —O—, —S—, —SO—, —SO ₂ —. , -CO-, -CO-O-Z-O-CO- (wherein Z represents an aliphatic divalent group) or
(A represents an integer of 1 to 20, b represents an integer of 1 to 2000, R ₁₀₃ and R ₁₀₄ represent a substituted or unsubstituted alkyl group or aryl group). Here, R ₁₀₁ and R ₁₀₂ , and R ₁₀₃ and R ₁₀₄ may be the same or different.

In the formula, R ₇ and R ₈ represent a substituted or unsubstituted aryl group, and Ar ₁ , Ar ₂ , and Ar ₃ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (II), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In the formula, R ₉ and R ₁₀ represent a substituted or unsubstituted aryl group, and Ar ₄ , Ar ₅ , and Ar ₆ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (III), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In the formula, R ₁₁ and R ₁₂ are substituted or unsubstituted aryl groups, Ar ₇ , Ar ₈ and Ar ₉ are the same or different arylene groups, and p represents an integer of 1 to 5. X, k, j and n are the same as those in the formula (I). In the formula (IV), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In the formula, R ₁₃ and R ₁₄ are substituted or unsubstituted aryl groups, Ar ₁₀ , Ar ₁₁ and Ar ₁₂ are the same or different arylene groups, X ₁ and X ₂ are substituted or unsubstituted ethylene groups, or substituted or unsubstituted Represents a substituted vinylene group. X, k, j and n are the same as those in the formula (I). In the formula (V), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In the formula, R ₁₅ , R ₁₆ , R ₁₇ , R ₁₈ are substituted or unsubstituted aryl groups, Ar ₁₃ , Ar ₁₄ , Ar ₁₅ , Ar ₁₆ are the same or different arylene groups, Y ₁ , Y ₂ , Y ₃ are 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 may be the same or different. X, k, j and n are the same as those in the formula (I). In the formula (VI), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In the formula, R ₁₉ and R _{20 each} represent a hydrogen atom or a substituted or unsubstituted aryl group, and R ₁₉ and R ₂₀ may form a ring. Ar ₁₇ , Ar ₁₈ and Ar ₁₉ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (VII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In the formula, R ₂₁ represents a substituted or unsubstituted aryl group, and Ar ₂₀ , Ar ₂₁ , Ar ₂₂ , and Ar ₂₃ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (VIII), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In the formula, R ₂₂ , R ₂₃ , R ₂₄ and R ₂₅ represent a substituted or unsubstituted aryl group, and Ar ₂₄ , Ar ₂₅ , Ar ₂₆ , Ar ₂₇ and Ar ₂₈ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (IX), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

In the formula, R ₂₆ and R ₂₇ represent a substituted or unsubstituted aryl group, and Ar ₂₉ , Ar ₃₀ and Ar ₃₁ represent the same or different arylene groups. X, k, j and n are the same as those in the formula (I). In the formula (X), two copolymer species are described in the form of an alternating copolymer, but a random copolymer may be used.

The amount of the charge transport material is 20 to 300 parts by weight, preferably 40 to 150 parts by weight with respect to 100 parts by weight of the binder resin.
As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used. Among them, the use of a non-halogen solvent is desirable for the purpose of reducing the environmental load. Specifically, cyclic ethers such as tetrahydrofuran, dioxolane and dioxane, aromatic hydrocarbons such as toluene and xylene, and derivatives thereof are preferably used.

  In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer 37. As the plasticizer, 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 preferably about 0 to 30% by weight based on the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 0 with respect to the binder resin. 1% by weight is preferred.

  The thickness of the charge transport layer 37 is preferably about 5 to 40 μm, more preferably about 10 to 30 μm.

  On the charge transport layer 37 formed in this manner, 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, and the crosslink A type charge transport layer 39 is formed. The details of the cross-linked charge transport layer 39 are as described above.

  In the photoreceptor of the present invention, an intermediate layer is provided between the charge transport layer 37 and the crosslinkable charge transport layer 39 for the purpose of suppressing charge transport layer component mixing into the crosslinkable charge transport layer or improving adhesion between the two layers. Can be provided. 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 preferably about 0.05 to 2 μm.

  In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support 31 and the charge generation layer 35. 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 a 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 coating method as in the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, in the undercoat layer of the present invention, Al ₂ O ₃ is provided by anodic oxidation, organic substances such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ A material provided with an inorganic material such as a vacuum thin film can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is preferably 0 to 5 μm.

  In the present invention, in order to improve environmental resistance, in order to prevent a decrease in sensitivity and an increase in residual potential, a crosslinkable charge transport layer, a charge transport layer, a charge generation layer, an undercoat layer, an intermediate layer, etc. Antioxidants can be added to each layer.

The following are mentioned as antioxidant which can be used for this invention.
(Phenolic compounds)
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4, 4'-thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4 -Hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene- -(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butyric acid] Crycol esters, tocopherols, etc.

(Paraphenylenediamines)
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.

(Hydroquinones)
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone and the like.

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

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

  These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained. The addition amount of the antioxidant in the present invention is 0.01 to 10% by weight based on the total weight of the layer to be added.

Next, 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 is an electrophotographic photosensitive member in which a charge generation layer, a charge transport layer, and a cross-linked charge transport layer are sequentially laminated on at least a conductive support, and CuKα rays (wavelength 1) are included in the charge generation layer. As a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to .542 Å), it has a maximum diffraction peak at least 27.2 ° and is further dominant at 9.4 °, 9.6 °, and 24.0 °. It has a peak and has a peak at 7.3 ° as the lowest diffraction peak, no peak between the 7.3 ° peak and the 9.4 ° peak, and 26.3 A trifunctional or higher functional radical-polymerizable monomer having a peak at ° and containing a titanyl phthalocyanine crystal having an average primary particle size of 0.25 μm or less, and wherein the crosslinked charge transport layer does not have at least a charge transport structure; Monofunctional charge transport structure A photosensitive member formed by curing a radically polymerizable compound having a thickness of 1 to 10 μm, and for example, charging means, exposure means, and development for charging at least the photosensitive member. An image forming apparatus comprising: a transfer means for transferring a toner image to an image holding member (transfer paper); a fixing means; and a means for cleaning the surface of the photoreceptor. In some cases, an image forming apparatus or the like that directly transfers an electrostatic latent image to a transfer member and develops it does not necessarily have the above-described process arranged on a photosensitive member.

  FIG. 8 is a schematic view showing an example of the image forming apparatus of the present invention. A charging charger 2 is used as means for charging the photosensitive member on average. As the charging means, a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or the like is used, and a known system can be used.

  In particular, the configuration of the present invention is particularly effective when a charging unit such as a contact charging method or a non-contact proximity arrangement charging method is used in which the photosensitive composition is decomposed by proximity discharge from the charging unit. The contact charging method referred to here is a charging method in which a charging roller, a charging brush, a charging blade, or the like is in direct contact with the photosensitive member. On the other hand, the proximity charging method is, for example, a type in which the charging roller is arranged in a non-contact state so as to have a gap of 200 μm or less between the surface of the photoreceptor and the charging means. If this gap is too large, the charging tends to become unstable, and if it is too small, the surface of the charging member may be contaminated when toner remaining on the photoreceptor exists. is there. Accordingly, the gap is in the range of 10 to 200 μm, preferably 10 to 100 μm.

  Next, the image exposure unit 3 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. Among these light sources, light emitting diodes and semiconductor lasers have high irradiation energy and long wavelength light of 600 to 800 nm, so that the above-mentioned titanyl phthalocyanine pigment, which is a charge generation material, exhibits high sensitivity and is used well. Is done.

  Next, the developing unit 4 is used to visualize the electrostatic latent image formed on the photoreceptor 1. Development methods include a one-component development method using a dry toner, a two-component development method, and a wet development method using a wet toner. When the photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.

  Next, a transfer charger 11 is used to transfer the toner image visualized on the photosensitive member onto the transfer member 7. In addition, a pre-transfer charger 13 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 14 and a separation claw 15 are used as means for separating the transfer body 7 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 14, the charging means can be used.

  Next, a fur brush 17 and a cleaning blade 18 are used to clean the toner remaining on the photoreceptor after transfer. Further, a pre-cleaning charger 16 may be used in order to perform cleaning more efficiently. Other cleaning means include a web method, a magnet brush method, and the like, but each may be used alone or in combination.

  Next, a neutralizing unit is used for the purpose of removing the latent image on the photoreceptor as required. As the charge removal means, a charge removal lamp 19 and a charge removal charger are used, and the exposure light source and the charging means can be used, respectively.

  In addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.

  The present invention is an image forming apparatus using the electrophotographic photoreceptor according to the present invention for such image forming means.

  The image forming means may be fixedly incorporated in a copying apparatus, facsimile, or printer, but may be incorporated in these apparatuses in the form of a process cartridge and detachable. An example of the process cartridge is shown in FIG.

  The process cartridge for an image forming apparatus includes a photosensitive member 101, and further includes at least one of a charging unit 102, a developing unit 104, a transfer unit 110, a cleaning unit 105, and a charge eliminating unit (not shown). An apparatus (part) that is detachable from the forming apparatus main body.

  Referring to the image forming process by the apparatus illustrated in FIG. 9, the photosensitive member 101 is charged in the direction of the arrow while being charged by the charging unit 102 and exposed by the exposure 103. An image is formed, and the electrostatic latent image is developed with toner by the developing unit 104. The toner development is transferred to the transfer body 107 by the transfer unit 110 and printed out. Next, the surface of the photoconductor after the image transfer is cleaned by the cleaning unit 105 and is further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

  As is apparent from the above description, the electrophotographic photosensitive member of the present invention is not only used in electrophotographic copying machines, but also in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making. Can also be used widely.

  FIG. 10 illustrates a tandem-type full-color electrophotographic apparatus which is an example of an image forming apparatus in which a plurality of image forming elements including at least a charging unit, an exposure unit, a developing unit, a transfer unit, and a photoreceptor of the present invention are arranged. The following modifications also belong to the category of the present invention. The tandem electrophotographic apparatus is a very effective system for realizing high-speed full-color printing, and the effectiveness obtained by using the photoconductor of the present invention having high sensitivity, high durability and high stability is further increased. Get higher.

  In FIG. 10, reference numerals 1C, 1M, 1Y, and 1K denote drum-shaped photoconductors. The photoconductor 1 is an electron in which a charge generation layer, a charge transport layer, and a cross-linkable charge transport layer are sequentially stacked on at least a conductive support. In the photographic photoreceptor, the charge generation layer has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to CuKα rays (wavelength 1.542 mm). It has major peaks at .4 °, 9.6 ° and 24.0 °, and has a peak at 7.3 ° as the lowest diffraction peak, a peak at 7.3 ° and 9.4 °. Including a titanyl phthalocyanine crystal having no peak between 2 ° peaks and having a peak at 26.3 ° and an average primary particle size of 0.25 μm or less. Trifunctional without charge transport structure It is formed by curing the above radical polymerizable monomer and a radical polymerizable compound having a monofunctional charge transport structure, and the film thickness of the crosslinkable charge transport layer is 1 μm or more and 10 μm or less.

  The photoreceptors 1C, 1M, 1Y, and 1K rotate in the direction of the arrow in the drawing, and at least around them, the charging members 2C, 2M, 2Y, and 2K, the developing members 4C, 4M, 4Y, and 4K, the cleaning member 5C, 5M, 5Y, 5K are arranged. The charging members 2C, 2M, 2Y, and 2K are charging members that constitute a charging device for uniformly charging the surface of the photoreceptor. The surface of the photoreceptor between the charging members 2C, 2M, 2Y, and 2K and the developing members 4C, 4M, 4Y, and 4K is irradiated with laser beams 3C, 3M, 3Y, and 3K from an exposure member (not shown), and the photoreceptor 1C. Electrostatic latent images are formed on 1M, 1Y, and 1K. The four image forming elements 6C, 6M, 6Y, and 6K centering on the photoreceptors 1C, 1M, 1Y, and 1K are juxtaposed along the transfer conveyance belt 10 that is a transfer material conveyance unit. The transfer conveyance belt 10 contacts the photoreceptors 1C, 1M, 1Y, and 1K between the developing members 4C, 4M, 4Y, and 4K and the cleaning members 5C, 5M, 5Y, and 5K of the image forming units 6C, 6M, 6Y, and 6K. Transfer brushes 11 </ b> C, 11 </ b> M, 11 </ b> Y, and 11 </ b> K for applying a transfer bias are disposed on a surface (back surface) that is in contact with the back side of the transfer conveyance belt 10 on the photoconductor side. Each of the image forming elements 6C, 6M, 6Y, and 6K is different in the color of the toner inside the developing device, and the others are the same in configuration.

  In the color electrophotographic apparatus having the configuration shown in FIG. 10, the image forming operation is performed as follows. First, in each of the image forming elements 6C, 6M, 6Y, and 6K, the photoreceptors 1C, 1M, 1Y, and 1K are charged by charging members 2C, 2M, 2Y, and 2K that rotate in the direction of the arrow (the direction along with the photoreceptor). Next, an electrostatic latent image corresponding to each color image to be created is formed by laser light 3C, 3M, 3Y, 3K in an exposure unit (not shown). Next, the latent image is developed by the developing members 4C, 4M, 4Y, and 4K to form a toner image. The developing members 4C, 4M, 4Y, and 4K are developing members that perform development with toners of C (cyan), M (magenta), Y (yellow), and K (black), respectively, and the four photosensitive members 1C, 1M, and 1Y. The toner images of each color created on 1K are superimposed on the transfer paper. The transfer paper 7 is sent out from the tray by a paper feed roller 8, temporarily stopped by a pair of registration rollers 9, and sent to the transfer conveyance belt 10 in synchronism with the image formation on the photosensitive member. The transfer paper 7 held on the transfer conveyance belt 10 is conveyed, and the color toner images are transferred at the contact positions (transfer portions) with the photoconductors 1C, 1M, 1Y, and 1K. The toner image on the photoconductor is transferred onto the transfer paper 7 by an electric field formed from a potential difference between the transfer bias applied to the transfer brushes 11C, 11M, 11Y, and 11K and the photoconductors 1C, 1M, 1Y, and 1K. The Then, the recording paper 7 on which the four color toner images are passed through the four transfer portions is conveyed to the fixing device 12, where the toner is fixed, and is discharged to a paper discharge portion (not shown). In addition, the residual toner that is not transferred by the transfer unit and remains on the photosensitive members 1C, 1M, 1Y, and 1K is collected by the cleaning devices 5C, 5M, 5Y, and 5K. In the example of FIG. 10, the image forming elements are arranged in the order of Y (yellow), M (magenta), C (cyan), and K (black) from the upstream side to the downstream side in the transfer paper conveyance direction. However, it is not limited to this order, and the color order is arbitrarily set. Further, when a black-only document is created, it is particularly effective to use the present invention to provide a mechanism that stops the image forming elements (6C, 6M, 6Y) other than black. Further, in FIG. 10, the charging member is in contact with the photosensitive member, but by providing an appropriate gap (about 10 to 200 μm) between them, the wear amount of both can be reduced and the charging member can be applied to the charging member. Less toner filming and good use.

  The image forming means as described above may be fixedly incorporated in a copying apparatus, facsimile, or printer, but each electrophotographic element may be incorporated in the apparatus in the form of a process cartridge.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not restrict | limited by an Example. The “parts” used in the examples all represent parts by weight.

  First, a synthesis example of titanyl phthalocyanine, which is a charge generation material used for the charge generation layer in the present invention, will be described.

Comparative Synthesis Example 1
A pigment was produced according to Patent Document 1. That is, 292 g of 1,3-diiminoisoindoline and 2000 ml of sulfolane are mixed, and 20.4 g of titanium tetrabutoxide is added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After completion of the reaction, the mixture was allowed to cool, and then the precipitate was filtered, washed with chloroform until the powder turned blue, then washed several times with methanol, further washed several times with hot water at 80 ° C., and dried. Crude titanyl phthalocyanine was obtained.
Dissolve the crude titanyl phthalocyanine in 20 times the amount of concentrated sulfuric acid, add dropwise to 100 times the amount of ice water with stirring, filter the precipitated crystals, and then repeat washing with water until the washing solution becomes neutral. (Water paste) was obtained. 50 g of the obtained wet cake (water paste) was put into 500 g of tetrahydrofuran, stirred for 4 hours, filtered and dried to obtain titanyl phthalocyanine crystals.
Further, 30 g of this titanyl phthalocyanine crystal was immersed in 300 g of tetrahydrofuran, and a second crystal conversion was performed. After leaving it immersed for 12 hours, it was separated by filtration and dried under reduced pressure under the same conditions as above to obtain titanyl phthalocyanine crystals. This is designated as Pigment 1.

Synthesis example 1
In accordance with the method of Comparative Synthesis Example 1, a titanyl phthalocyanine pigment water paste was synthesized, and crystal conversion was performed as follows to obtain phthalocyanine crystals having smaller primary particles than Comparative Synthesis Example 1.
To 60 parts of the water paste before crystal conversion obtained in Comparative Synthesis Example 1, 1500 parts of tetrahydrofuran was added and stirred vigorously (2000 rpm) with a homomixer (Kennis, MARKIIf model) at room temperature. When the color changed to light blue (20 minutes after the start of stirring), stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filtration device were washed with tetrahydrofuran to obtain a wet cake of pigment. This was dried under reduced pressure (5 mmHg) at 70 ° C. for 2 days to obtain 58 parts of titanyl phthalocyanine crystals.
Further, 30 g of this titanyl phthalocyanine crystal was immersed in 300 g of tetrahydrofuran, and a second crystal conversion was performed. After leaving it immersed for 12 hours, it was separated by filtration and dried under reduced pressure under the same conditions as above to obtain titanyl phthalocyanine crystals. This is designated as Pigment 2.

Synthesis example 2
A titanyl phthalocyanine crystal was obtained in the same manner as in Synthesis Example 1 except that the second crystal conversion operation in Synthesis Example 1 was changed to the following conditions. This is designated as Pigment 3.
(Second crystal conversion process)
30 g of titanyl phthalocyanine crystals subjected to the first crystal conversion treatment were subjected to mechanical shearing force for 5 minutes by a commercially available mixer, and then the powder was taken out.

Synthesis example 3
A titanyl phthalocyanine crystal was obtained in the same manner as in Synthesis Example 1 except that the second crystal conversion operation in Synthesis Example 1 was changed to the following conditions. This is designated as Pigment 4.
(Second crystal conversion process)
30 g of titanyl phthalocyanine crystals subjected to the first crystal conversion treatment were put into a φ90 mm glass pot together with 2 kg of φ6 mm zirconia balls, and after dry milling for 10 minutes, the powder was taken out.

Comparative Synthesis Example 2
A titanyl phthalocyanine crystal was obtained in the same manner as in Comparative Synthesis Example 1 except that the second crystal conversion solvent in Comparative Synthesis Example 1 was changed from tetrahydrofuran to methanol. This is designated as Pigment 5.

Comparative Synthesis Example 3
In Comparative Synthesis Example 1, treatment was performed in the same manner as in Comparative Synthesis Example 1 except that 2-butanone was used instead of tetrahydrofuran as the first crystal conversion solvent and the second crystal conversion was not performed, and the titanyl phthalocyanine crystals were obtained. Obtained. This is designated as Pigment 6.

A part of the water paste obtained in Comparative Synthesis Example 1 was dried at 80 ° C. under reduced pressure (5 mmHg) for 2 days to obtain a low crystalline titanyl phthalocyanine powder.
X-ray diffraction spectra of the dry powder of the water paste obtained as described above and the titanyl phthalocyanine crystals obtained in Synthesis Examples 1 to 3 and Comparative Synthesis Examples 1 to 3 were measured under the following conditions. An X-ray diffraction spectrum of the dry powder of the water paste is shown in FIG.
X-ray tube: Cu
Voltage: 40kV
Current: 20mA
Scanning speed: 1 ° / min Scanning range: 3 ° -40 °
Time constant: 2 seconds

  As for Comparative Synthesis Example 1 and Synthesis Examples 1 to 3, since the same X-ray diffraction spectrum was shown in each case except for the peak intensity of 26.3 °, the titanyl phthalocyanine obtained in Synthesis Example 2 as a representative example. The X-ray diffraction spectrum of the crystal is shown in FIG. 12 (the arrow in the figure is a peak at 26.3 °, and the peak intensity ratio is 8%).

  The X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Comparative Synthesis Example 2 is shown in FIG. 13, but it did not show a peak at 26.3 °.

  The X-ray diffraction spectrum of the titanyl phthalocyanine crystal obtained in Comparative Synthesis Example 3 is shown in FIG. 14, and the lowest angle exists at 7.5 °.

Comparative Synthesis Example 4
A pigment was produced according to the method described in Patent Document 13 and Example 1. That is, the wet cake produced in the previous Comparative Synthesis Example 1 was dried, 1 g of the dried product was added to 50 g of polyethylene glycol, and sand milling was performed with 100 g of glass beads. After the crystal transition, the mixture was washed successively with dilute sulfuric acid and aqueous ammonium hydroxide and dried to obtain a pigment. This is designated as Pigment 7.

Comparative Synthesis Example 5
A pigment was produced according to the method described in Patent Document 14 and Production Example 1. That is, the wet cake prepared in Comparative Synthesis Example 1 was dried, and 1 g of the dried product was stirred (50 ° C.) in a mixed solvent of 10 g of ion-exchanged water and 1 g of monochlorobenzene for 1 hour, and then methanol and ion-exchanged water. The pigment was obtained by washing and drying. This is designated as Pigment 8.

Comparative Synthesis Example 6
A pigment was produced according to the method described in the production example of Patent Document 15. That is, 9.8 g of phthalodinitrile and 75 ml of 1-chloronaphthalene are stirred and mixed, and 2.2 ml of titanium tetrachloride is added dropwise under a nitrogen stream. After completion of the dropping, the temperature was gradually raised to 200 ° C., and the reaction was carried out by stirring for 3 hours while maintaining the reaction temperature between 200 ° C. and 220 ° C. After completion of the reaction, the mixture was allowed to cool to 130 ° C. and filtered while hot, then washed with 1-chloronaphthalene until the powder turned blue, then washed several times with methanol, and further with hot water at 80 ° C. After washing twice, it was dried to obtain a pigment. This is designated as Pigment 9.

Comparative Synthesis Example 7
A pigment was prepared according to the method described in Patent Document 16 and Synthesis Example 1. That is, 5 parts of α-type TiOPc was subjected to crystal conversion treatment at 100 ° C. for 10 hours with a sand grinder together with 10 g of sodium chloride and 5 g of acetophenone. This was washed with ion-exchanged water and methanol, purified with dilute sulfuric acid aqueous solution, washed with ion-exchanged water until the acid content disappeared, and dried to obtain a pigment. This is designated as Pigment 10.

Comparative Synthesis Example 8
A pigment was produced according to the method described in Patent Document 17 and Example 1. That is, after 20.4 parts of O-phthalodinitrile and 7.6 parts of titanium tetrachloride were heated and reacted in 50 parts of quinoline at 200 ° C. for 2 hours, the solvent was removed by steam distillation, followed by a 2% aqueous chloride solution, The product was purified with a 2% aqueous sodium hydroxide solution, washed with methanol and N, N-dimethylformamide, and then dried to obtain titanyl phthalocyanine. 2 parts of this titanyl phthalocyanine is dissolved little by little in 40 parts of 98% sulfuric acid at 5 ° C., and the mixture is stirred for about 1 hour while maintaining the temperature at 5 ° C. or less. Subsequently, the sulfuric acid solution is slowly poured into 400 parts of ice water stirred at a high speed, and the precipitated crystals are filtered. The crystals are washed with distilled water until no acid remains, and a wet cake is obtained. The cake was stirred in 100 parts of THF for about 5 hours, filtered, washed with THF and dried to obtain a pigment. This is designated as Pigment 11.

Comparative Synthesis Example 9
A pigment was produced according to the method described in Patent Document 18 and Synthesis Example 2. That is, 10 parts of the wet cake prepared in Synthesis Example 1 above was mixed with 15 parts of sodium chloride and 7 parts of diethylene glycol, and milled for 60 hours with an automatic mortar under heating at 80 ° C. Next, sufficient washing was performed to completely remove sodium chloride and diethylene glycol contained in the treated product. After drying this under reduced pressure, 200 parts of cyclohexanone and glass beads having a diameter of 1 mm were added, and the mixture was treated with a sand mill for 30 minutes to obtain a pigment. This is designated as Pigment 12.

Comparative Synthesis Example 10
A pigment was prepared according to the method described in Patent Document 17 and Example 4. That is, the wet cake obtained in the previous Comparative Synthesis Example 7 was washed with 5% hydrochloric acid, washed with water and filtered until neutral, and dried. Further, this was dispersed with THF in a ball mill for 10 hours, filtered and dried to obtain a pigment powder. This is designated as Pigment 13.

Comparative Synthesis Example 11
A pigment was produced according to the method described in Production Example 1 and Production Example 2 of Patent Document 19.
That is, 97.5 g of phthalodinitrile is added to 750 ml of α-chloronaphthalene, and then 22 ml of titanium tetrachloride is added dropwise under a nitrogen atmosphere. After dropping, the temperature was raised, and the mixture was reacted at 200 to 220 ° C. for 3 hours with stirring, then allowed to cool, filtered hot at 100 to 130 ° C., and washed with 200 ml of α-chloronaphthalene heated to 100 ° C. Furthermore, the hot-washing process (100 degreeC, 1 hour) was performed 3 times with 200 ml N-methylpyrrolidone. Subsequently, the suspension was washed with 300 ml of methanol at room temperature, and further washed with 500 ml of methanol for 1 hour. This is designated as phthalocyanine 1.
Next, phthalocyanine 1 was ground in a sand grind mill for 20 hours, then placed in a suspension of 400 ml of water and 40 ml of o-dichlorobenzene, and heat-treated at 60 ° C. for 1 hour. This is designated as phthalocyanine 2.
Furthermore, according to Example 1 of Patent Document 19, 6 parts by weight and 4 parts by weight of phthalocyanine 1 and phthalocyanine 2 were mixed, 200 parts by weight of n-propanol was added, and the mixture was pulverized and atomized by a sand grind mill for 10 hours. Processed. This was dried to obtain phthalocyanine powder. This is designated as Pigment 14.

Comparative Synthesis Example 12
A pigment was produced according to the method for producing a titanyl phthalocyanine crystal of Patent Document 9. That is, 58 g of 1,3-diiminoisoindoline and 51 g of tetrabutoxytitanium were reacted in 210 mL of α-chloronaphthalene at 210 ° C. for 5 hours, and then washed with α-chloronaphthalene and dimethylformamide (DMF) in this order. Thereafter, it was washed with hot DMF, hot water and methanol and dried to obtain 50 g of titanyl phthalocyanine. 4 g of titanyl phthalocyanine was added to 400 g of sulfuric acid cooled to 0 ° C., followed by stirring at 0 ° C. for 1 hour. After confirming that phthalocyanine was completely dissolved, it was added to a 800 mL water / 800 mL toluene mixture cooled to 0 ° C. After stirring at room temperature for 2 hours, the precipitated phthalocyanine crystal was separated from the mixture and washed with methanol and water in this order. After confirming the neutrality of the washing water, the phthalocyanine crystal was separated from the washing water and dried to obtain 2.9 g of titanyl phthalocyanine crystal. This is designated as Pigment 15.

  A portion of titanyl phthalocyanine (water paste) before crystal transformation prepared in Comparative Synthesis Example 1 was diluted with ion-exchanged water to approximately 1% by weight, and the surface was scooped with a copper net having been subjected to conductive treatment. The particle size of phthalocyanine was observed with a transmission electron microscope (TEM, Hitachi: H-9000NAR) at a magnification of 75000 times. The average particle size was determined as follows.

The TEM image observed as described above is taken as a TEM photograph, and 30 titanyl phthalocyanine particles (a shape close to a needle shape) projected are arbitrarily selected, and the size of each major axis is measured. The arithmetic average of the major diameters of the 30 individuals measured was determined as the average particle size.
The average particle size in the water paste in Synthesis Example 1 determined by the above method was 0.06 μm.

  In addition, the titanyl phthalocyanine crystal after crystal conversion just before filtration in Comparative Synthesis Example 1 and Synthesis Example 1 was diluted with tetrahydrofuran to about 1% by weight, and observed in the same manner as the above method. The average particle size determined as described above is shown in Table 2. In addition, the titanyl phthalocyanine crystal produced in Comparative Synthesis Example 1 and Synthesis Example 1 did not necessarily have the same shape of all crystals (a shape close to a triangle, a shape close to a square, etc.). For this reason, the calculation was performed with the length of the largest diagonal line of the crystal as the major axis.

  From Table 2, the pigment 1 produced in Comparative Synthesis Example 1 not only has a large average particle size but also contains coarse particles. On the other hand, it can be seen that the pigment 2 produced in Synthesis Example 1 has not only a small average particle size but also almost the same size of individual primary particles.

  In addition, the pigments prepared in Comparative Synthesis Examples 4 to 12 were measured for X-ray diffraction spectra by the same method as described above, and confirmed to be the same as the spectra described in the respective patent documents. Table 3 shows the characteristics of the X-ray diffraction spectra and the peak positions of the X-ray diffraction spectra of the pigments obtained in Comparative Synthesis Examples 1 to 3 and Synthesis Examples 1 to 3.

  The peak intensity ratio of 26.3 ° in Table 3 is the ratio of the peak intensity of 27.2 ° to the peak intensity of 26.3 ° as described above. In this calculation, when the peak at 26.3 ° was not clearly observed as shown in FIG. 16, the calculation was performed with the peak intensity = 0.

Next, a synthesis example of a compound having a monofunctional charge transporting structure used for the crosslinkable charge transporting layer will be described.
Example of Synthesis 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. The melting point of the obtained compound is 64.0 to 66.0 ° C., and the results of elemental analysis are as shown in Table 4.

(2) Synthesis Example of Triarylamino Group-Substituted Acrylate Compound (Exemplary Compound No. 54 in Table 1) Hydroxy Group-Substituted Triarylamine Compound (Structural Formula B) Obtained in (1) above (2.9. 227 mol) was dissolved in 400 ml of tetrahydrofuran, and an aqueous sodium hydroxide solution (NaOH: 12.4 g, water: 100 ml) was added dropwise in a nitrogen stream. The solution was cooled to 5 ° C., and 25.2 g (0.272 mol) of acrylic acid chloride was added dropwise over 40 minutes. Then, it stirred at 5 degreeC for 3 hours, and reaction was 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. The melting point of the obtained compound is 117.5 to 119.0 ° C., and the results of elemental analysis are as shown in Table 5.

(Dispersion Preparation Example 1)
Pigment 1 prepared in Comparative Synthesis Example 1 was dispersed under the following composition under the following conditions to prepare a dispersion as a charge generation layer coating solution.
Titanyl phthalocyanine pigment (Pigment 1) 15 parts Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 10 parts 2-butanone 280 parts A commercially available bead mill disperser was used to dissolve polyvinyl butyral using PSZ balls having a diameter of 0.5 mm. All butanone and pigment were added, and the rotor rotation speed was 1200 r. p. m. And dispersion was performed for 30 minutes to prepare a dispersion (referred to as dispersion 1).

(Dispersion Preparation Examples 2 to 15)
In place of Pigment 1 used in Dispersion Preparation Example 1, pigments 2 to 15 prepared in Synthesis Examples 1 to 3 and Comparative Synthesis Examples 2 to 12 were used, respectively, and dispersed under the same conditions as Dispersion Preparation Example 1. Liquids were prepared (corresponding to the pigment numbers, dispersions 2 to 15, respectively).

(Dispersion Preparation Example 16)
The dispersion 1 prepared in Dispersion Preparation Example 1 was filtered using a cotton wind cartridge filter, TCW-1-CS (effective pore size 1 μm) manufactured by Advantech. In the filtration, a pump was used and filtration was performed under pressure (referred to as dispersion liquid 16).

(Dispersion Preparation Example 17)
Dispersion was performed by pressure filtration in the same manner as in Dispersion Preparation Example 16 except that the filter used in Dispersion Preparation Example 16 was changed to a cotton wind cartridge filter manufactured by Advantech, TCW-3-CS (effective pore size 3 μm). A liquid was prepared (referred to as dispersion liquid 17).

(Dispersion Preparation Example 18)
Dispersion was performed by pressure filtration in the same manner as in Dispersion Preparation Example 16, except that the filter used in Dispersion Preparation Example 15 was changed to an Advantech Co., Ltd. cotton wind cartridge filter, TCW-5-CS (effective pore size 5 μm). A liquid was prepared (referred to as dispersion 18).

(Dispersion Preparation Example 19)
Dispersion was carried out by changing the dispersion conditions in Dispersion Preparation Example 1 as follows (referred to as Dispersion 19).
Rotor rotation speed: 1000 r. p. m. For 20 minutes.

(Dispersion Preparation Example 20)
The dispersion prepared in Dispersion Preparation Example 19 was filtered using a cotton wind cartridge filter, TCW-1-CS (effective pore size 1 μm) manufactured by Advantech. During filtration, a pump was used and filtration was performed in a pressurized state. During the filtration, the filter was clogged, and it was not possible to filter all the dispersions. Therefore, the following evaluation has not been conducted.
The particle size distribution of the pigment particles in the dispersion prepared as described above was measured by HORIBA, Ltd .: CAPA-700. The results are shown in Table 6.

Comparative Example 1
An undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition were sequentially applied and dried on an aluminum cylinder (JIS1050) having a diameter of 60 mm, and an undercoat layer of 3.5 μm, A charge generation layer and an 18 μm charge transport layer were formed. The film thickness of the charge generation layer was set so that the transmittance of the charge generation layer at 780 nm was 20%. The transmittance of the charge generation layer was determined by applying a charge generation layer coating solution having the following composition to an aluminum cylinder wrapped with a polyethylene terephthalate film under the same conditions as those for producing the photoreceptor, and a commercially available spectrophotometer (Shimadzu: UV- 3100), the transmittance at 780 nm was evaluated. Further, a coating solution for a cross-linked charge transport layer having the following composition was spray-coated on the charge transport layer and naturally dried for 20 minutes, and then a metal halide lamp: 160 W / cm, irradiation distance: 120 mm, irradiation intensity: 200 mW / cm. ^2. Irradiation time: The coating film was cured by light irradiation under the condition of 60 seconds. Further, a drying process at 130 ° C. for 20 minutes was added to provide a 5.0 μm cross-linked charge transport layer to obtain an electrophotographic photoreceptor 1.

[Coating liquid for undercoat layer]
Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd.) 70 parts Alkyd resin 15 parts (Beckolite M6401-50-S (solid content 50%, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 10 parts (Super Becamine L-121-60 (solid content 60%, manufactured by Dainippon Ink & Chemicals, Inc.)
2-butanone 100 parts

[Coating liquid for charge generation layer]
The previously prepared dispersion 1 was used.

[Coating fluid for charge transport layer]
7 parts of charge transport material with the following structural formula
Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts dichloromethane 80 parts 1% silicone oil in methylene chloride 0.2 parts (KF50-100cs: manufactured by Shin-Etsu Chemical Co., Ltd.)

[Coating liquid for crosslinkable charge transport layer]
10 parts of radical polymerizable monomer having 3 or more functional groups not having a charge transporting structure (trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku Co., Ltd.), molecular weight: 296, functional group number: trifunctional, molecular weight / functional group number = 99)
10 parts of a radically polymerizable compound having a monofunctional charge transporting structure (Exemplary Compound No. 54)
Photopolymerization initiator 1 part (1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals))
Tetrahydrofuran 100 parts

Examples 1-5 and Comparative Examples 2-14
A photoconductor was prepared in the same manner as in Comparative Example 1 except that the charge generation layer coating solution (Dispersion 1) used in Comparative Example 1 was changed to Dispersions 2 to 19, respectively. The photoreceptor numbers are electrophotographic photoreceptors 2 to 19 corresponding to the dispersion numbers. As in Comparative Example 1, the thickness of the charge generation layer was adjusted so that the transmittance at 780 nm was 20% when all the coating liquids were used.

Example 6
An electrophotographic photosensitive member 20 was produced in the same manner as in Example 1 except that the thickness of the cross-linked charge transport layer in Example 1 was changed to 2.0 μm.

Example 7
An electrophotographic photosensitive member 21 was produced in the same manner as in Example 1 except that the thickness of the crosslinked charge transport layer in Example 1 was changed to 7.9 μm.

Example 8
A radical having a monofunctional charge transport structure is replaced with the following monomer in place of the trifunctional or higher radical polymerizable monomer having no charge transport structure, which is contained in the coating liquid for the crosslinkable charge transport layer of Example 1. The polymerizable compound was exemplified as Compound No. 1. Instead of 138 and 10 parts, an electrophotographic photosensitive member 22 was produced in the same manner as in Example 1 except that the thickness of the cross-linked charge transport layer was changed to 5.5 μm.
10 parts of tri- or higher functional radical polymerizable monomer having no charge transport structure (pentaerythritol tetraacrylate (SR-295, manufactured by Kayaku Sartomer)
(Molecular weight: 352, number of functional groups: tetrafunctional, molecular weight / number of functional groups = 88)

Example 9
The trifunctional or higher functional radical polymerizable monomer having no charge transport structure contained in the coating liquid for the crosslinkable charge transport layer of Example 1 is replaced with the following monomer, and the photopolymerization initiator is replaced with 1 part of the following compound: Instead, an electrophotographic photosensitive member 23 was produced in the same manner as in Example 1 except that the thickness of the cross-linked charge transport layer was 4.5 μm.
10 parts of radically polymerizable monomer having 3 or more functional groups having no charge transport structure (caprolactone-modified dipentaerythritol hexaacrylate
(KAYARAD DPCA-60, manufactured by Nippon Kayaku)
(Molecular weight: 1263, number of functional groups: 6 functions, molecular weight / number of functional groups = 211)
1 part of photopolymerization initiator (2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure 651, manufactured by Ciba Specialty Chemicals))

Example 10
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 film thickness of the crosslinkable charge transport layer is set to 9 An electrophotographic photosensitive member 24 was produced in the same manner as in Example 1 except that the thickness was changed to 2 μm.
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 10 parts (Caprolactone-modified dipentaerythritol hexaacrylate (KAYARAD DPCA-120, manufactured by Nippon Kayaku)
(Molecular weight: 1947, number of functional groups: 6 functions, molecular weight / number of functional groups = 325)

Example 11
An electrophotographic photosensitive member 25 was produced in the same manner as in Example 5 except that the coating liquid for the crosslinkable charge transport layer of Example 5 had the following composition and the thickness of the crosslinkable charge transport layer was 4.2 μm.
9 parts or more radical polymerizable monomer having no charge transport structure (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)
Photopolymerization initiator 1 part (1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals))
1 part of bisphenol Z polycarbonate (Panlite TS-2050, manufactured by Teijin Chemicals)
Tetrahydrofuran 100 parts

Example 12
The radical polymerizable compound having a monofunctional charge transporting structure contained in the coating liquid for a crosslinkable charge transport layer of Example 5 was converted into a monofunctional exemplified compound No. An electrophotographic photosensitive member 26 was produced in the same manner as in Example 5 except that 54 and 9 parts and 1 part of a bifunctional compound having the following structure were used and the film thickness of the cross-linked charge transport layer was 6.0 μm.
9 parts of a radically polymerizable compound having a monofunctional charge transporting structure
(Exemplary Compound No. 54)
1 part of a radical polymerizable compound having a bifunctional charge transport structure of the following structural formula

Example 13
6 parts of the amount of tri- or higher functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for the crosslinkable charge transporting layer of Example 5 and radical polymerization having a monofunctional charge transporting structure An electrophotographic photoreceptor 27 was produced in the same manner as in Example 5 except that the amount of the compound was changed to 14 parts and the thickness of the cross-linked charge transport layer was changed to 6.0 μm.

Example 14
14 parts of the amount of a tri- or higher functional radical polymerizable monomer having no charge transporting structure contained in the coating liquid for a crosslinkable charge transporting layer of Example 5 and radical polymerization having a monofunctional charge transporting structure An electrophotographic photosensitive member 28 was produced in the same manner as in Example 5 except that the amount of the compound was changed to 6 parts and the film thickness of the cross-linked charge transport layer was changed to 6.0 μm.

Example 15
The charge transport layer coating liquid of Example 4 was changed to a charge transport layer coating liquid having the following composition, and the radical polymerizable property having a monofunctional charge transport structure contained in the crosslinkable charge transport layer coating liquid was used. The compounds were exemplified by Compound No. An electrophotographic photosensitive member 29 was produced in the same manner as in Example 4 except that the thickness of the crosslinked charge transport layer was changed to 4.0 μm instead of 144 parts.
[Coating fluid for charge transport layer]
7 parts of charge transport material with the following structural formula
Polycarbonate (TS2050: manufactured by Teijin Chemicals Co., Ltd.) 10 parts methylene chloride 80 parts 1% silicone oil in methylene chloride 0.2 parts (KF50-100cs: manufactured by Shin-Etsu Chemical Co., Ltd.)

Example 16
The coating liquid having the same composition as in Example 4 was used on the charge transport layer in the same manner except that the photopolymerization initiator contained in the coating liquid for the crosslinked surface layer of Example 4 was replaced with the following thermal polymerization initiator. After coating and natural drying, heating was performed at 70 ° C. for 30 minutes using a blow-type oven, and further heating was performed at 150 ° C. for 1 hour to form a cross-linked charge transport layer having a thickness of 3.5 μm, and an electrophotographic photosensitive member 30 was produced. .
Thermal polymerization initiator 1 part (2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane (Perkadox 12-EB20, manufactured by Kayaku Akzo)

Example 17
A liquid containing a polymer charge transporting substance (PD-1) having the following composition was used as the charge transporting layer coating liquid of Example 4, and a 18 μm charge transporting layer was coated on the same charge generating layer and dried. Formed. On this charge transport layer, a cross-linked charge transport layer having a thickness of 4.0 μm was provided in the same manner as in Example 4 to produce an electrophotographic photoreceptor 31.
[Coating liquid for charge transport layer]
Polymer charge transport material (PD-1) having the following structural formula: 15 parts
Tetrahydrofuran 100 parts 1% silicone oil tetrahydrofuran solution 0.3 parts (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.)

Comparative Example 15
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 Comparative Example 13 is converted into a bifunctional radical having no charge transporting structure of the following structural formula An electrophotographic photoreceptor 32 was produced in the same manner as in Example 7 except that the thickness of the cross-linked charge transport layer was changed to 6.0 μm instead of 10 parts of the polymerizable monomer.
10 parts of bifunctional radically polymerizable monomer not having a charge transporting structure (6-hexanediol diacrylate (manufactured by Wako Pure Chemical Industries))
Molecular weight: 226, number of functional groups: bifunctional, molecular weight / number of functional groups = 113)

Comparative Example 16
The radically polymerizable compound having a monofunctional charge transporting structure contained in the coating liquid for a crosslinkable charge transporting layer of Example 1 is replaced with 10 parts of the radically polymerizable compound having a bifunctional charge transporting structure of Example 12. Instead of this, an electrophotographic photosensitive member 33 was produced in the same manner as in Example 1 except that the thickness of the crosslinked charge transport layer was 7.0 μm.

Comparative Example 17
A radical polymerization having a monofunctional charge transporting structure without containing a trifunctional or higher functional radical polymerizable monomer having no charge transporting structure, which is a composition of the coating liquid for a crosslinkable charge transporting layer of Example 1. The electrophotographic photosensitive member 34 was produced in the same manner as in Example 1 except that the amount of the conductive compound was changed to 20 parts and the film thickness of the cross-linked charge transport layer was changed to 6.5 μm.

Comparative Example 18
Trifunctional or higher functional radical polymerization that does not contain a monofunctional charge transporting structure and has no charge transporting structure, which is the composition of the coating liquid for the crosslinkable charge transporting layer of Example 1. The electrophotographic photosensitive member 5 was produced in the same manner as in Example 1 except that the amount of the conductive monomer was changed to 20 parts and the film thickness of the cross-linked charge transport layer was changed to 5.0 μm.

Comparative Example 19
It does not contain a radically polymerizable compound having a monofunctional charge transporting structure, which is a composition of the coating liquid for the crosslinkable charge transport layer of Example 1, and is used in the coating liquid for the charge transport layer instead. An electrophotographic photosensitive member 36 was produced in the same manner as in Example 1 except that 10 parts of the low molecular charge transport material was contained and the thickness of the cross-linked charge transport layer was 5.0 μm.

Comparative Example 20
An electrophotographic photosensitive member 37 was produced in the same manner as in Example 5 except that the thickness of the cross-linked charge transport layer in Example 5 was changed to 0.9 μm.

Comparative Example 21
An electrophotographic photoreceptor 38 was produced in the same manner as in Example 5 except that the film thickness of the cross-linked charge transport layer in Example 5 was 10.2 μm.

Comparative Example 22
The charge transport layer of Example 5 was not provided, but instead, the following crosslinkable charge transport layer coating solution was applied and cured in the same manner on the charge generation layer, and a 19.0 μm crosslinkable charge transport layer was provided. In the same manner as in Example 5, an electrophotographic photoreceptor 39 was produced.
[Coating liquid for cross-linked charge transport layer]
8 parts of radically polymerizable monomer having 3 or more functional groups having no charge transporting structure (pentaerythritol tetraacrylate (SR-295, manufactured by Kayaku Sartomer)
(Molecular weight: 352, number of functional groups: tetrafunctional, molecular weight / number of functional groups = 88)
2 parts of radically polymerizable monomer having 3 or more functional groups not having a charge transporting structure (caprolactone-modified dipentaerythritol hexaacrylate
(KAYARAD DPCA-60, manufactured by Nippon Kayaku)
10 parts of a radically polymerizable compound having a monofunctional charge transporting structure (Exemplary Compound No. 54)
Photopolymerization initiator 1 part (1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals))
Tetrahydrofuran 100 parts

Comparative Example 23
The charge transport layer of Example 5 was not provided, but instead the following crosslinkable charge transport layer coating solution was applied and cured in the same manner on the charge generation layer to provide a 15.0 μm crosslinkable charge transport layer. In the same manner as in Example 5, an electrophotographic photoreceptor 40 was produced.
[Coating liquid for cross-linked charge transport layer]
8 parts of a radically polymerizable trifunctional or higher functional monomer having no charge transport structure (trimethylolpropane triacrylate (KAYARAD TMPTA,
Nippon Kayaku Co., Ltd.) Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99))
Trifunctional or higher functional radical polymerizable monomer having no charge transport structure 2 parts (Caprolactone-modified dipentaerythritol hexaacrylate (KAYARAD DPCA-60, Nippon Kayaku))
10 parts of a radically polymerizable compound having a monofunctional charge transporting structure (Exemplary Compound No. 54)
Photopolymerization initiator 1 part (1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals))
Tetrahydrofuran 100 parts

Comparative Example 24
An electrophotographic photoreceptor 41 was produced in the same manner as in Example 4 except that the cross-linkable charge transport layer of Example 4 was not provided and the thickness of the charge transport layer was 24 μm.

Comparative Example 25
An electrophotographic photosensitive member 42 was produced in the same manner as in Example 4 except that the cross-linked charge transport layer of Example 4 was not provided, and a 5.2 μm protective layer having the following composition was provided instead.
[Coating liquid for protective layer]
α-alumina filler 5 parts (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.)
Unsaturated polycarboxylic acid polymer solution 0.1 part (BYK-P104, acid value 180 mgKOH / g, nonvolatile content 50%,
BYK Chemie)
10 parts of a polycarbonate resin having a structural unit represented by the following formula
7 parts of charge transport material of the following formula
Tetrahydrofuran 500 parts Cyclohexanone 150 parts

Comparative Example 26
An electrophotographic photosensitive member 43 was produced in the same manner as in Example 4 except that the coating liquid for the crosslinkable charge transport layer in Example 4 was changed to a coating liquid for the crosslinkable charge transport layer having the following composition.
[Coating liquid for cross-linked charge transport layer]
Silica 6 parts (KMP-X100, average primary particle size: 0.1 μm, manufactured by Shin-Etsu Chemical Co., Ltd.)
10 parts of a polycarbonate resin having a structural unit represented by the following formula
8 parts of charge transport material of the following formula
Tetrahydrofuran 500 parts Cyclohexanone 150 parts

  With respect to the electrophotographic photoreceptors 1 to 43 produced as described above, the appearance was visually observed to determine the presence or absence of cracks and film peeling. Next, as a solubility test for an organic solvent, one drop of tetrahydrofuran (hereinafter abbreviated as THF) and dichloromethane were dropped, and the change in the surface shape after natural drying was observed. The results are shown in Table 7.

  From the results of Table 7, the photoreceptor having the 1-10 μm cross-linked charge transport layer of the present invention described in the examples is free from cracks and film peeling during film formation, and has a good appearance. was gotten. On the other hand, a photoconductor using a radical polymerizable compound having a bifunctional charge transport structure as a crosslinkable charge transport layer component, or a photoconductor having a crosslinkable charge transport layer thicker than 10 μm is used as a crosslinkable charge transport layer. Cracks and film peeling occurred during the formation. The photoreceptors of the present invention described in the examples are slightly soluble or insoluble in organic solvents, indicating that a crosslinked charge transport layer having a high crosslinking density is obtained. The insolubilization with respect to the organic solvent was further improved when the thickness of the cross-linked charge transport layer was 2 μm or more. On the other hand, when the film thickness of the crosslinkable charge transport layer was less than 1 μm, the charge transport layer component spread over the entire crosslinkable charge transport layer and became soluble in the organic solvent. Further, even when a trifunctional or higher-functional radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure were not included, it was also soluble in an organic solvent.

Next, these electrophotographic photoreceptors were subjected to a paper passing test of 100,000 sheets of A4 size in an environment of 15 ° C., 20% RH and 28 ° C., 85% RH. First, the photoconductor is mounted on a process cartridge for an electrophotographic apparatus, and the exposure portion potential (VL) is measured at the initial stage of the photoconductor and the output image is measured with a Ricoh imagio Neo450 remodeling machine using a 780 nm semiconductor laser as an image exposure light source. Evaluation was performed in an environment of 25 ° C. and 55% RH. At this time, the applied voltage was set so that the dark portion potential (VD) was −800 V at the initial stage, and the developing bias was set to −550 V. Thereafter, a paper passing test was started in an environment of 15 ° C., 20% RH and 28 ° C., 85% RH, and VD and VL were measured at applied voltages set at the initial stage after copying 100,000 sheets. For the paper passing test at 28 ° C. and 85% RH, the film thickness of the entire photosensitive member was measured at 1 cm intervals before and after the paper passing test, and the wear amount was calculated from the average value of the film thickness differences. The image evaluation was divided into four levels, and the level was evaluated according to the type of image defect and the following criteria. The results are shown in Table 8.
◎: Extremely good level ○: Image quality slightly lower than the initial level, but no problem △: Level where image quality degradation is clearly recognized ×: Level where image quality degradation is noticeable

  From the above paper passing test results, the electrophotographic photosensitive member of the present invention shown in the examples has improved abrasion resistance and at the same time has stable potential characteristics in various environments, and also has a background stain that determines the life of the photosensitive member. As a result, stable high-quality images can be provided over a long period of time. In particular, the potential stability is improved by using the titanyl phthalocyanine crystal shown in the present invention, and in addition, the background contamination caused by the charge generation layer is greatly suppressed by making the pigment particles finer or eliminating the aggregated particles. It became possible. Further, by forming the 1-10 μm cross-linked charge transport layer shown in the present invention on the surface of the photoconductor, the wear resistance is improved without increasing the exposed portion potential and the side effects of various image defects. As a result of combination, it was possible to suppress the generation of background stains due to charge reduction or film scraping due to fatigue due to long-term use, and also to reduce the environmental dependency, and as a result, it was possible to realize a long life of the photoreceptor. .

  On the other hand, if the diffraction peak (± 0.2 °) of the Bragg angle 2θ with respect to the CuKα ray (wavelength 1.542 mm) does not fall within the scope of the present invention, the effect of background contamination due to charge reduction and the increase in potential of the exposed area, There was a tendency for environmental dependence to increase. In addition, when the average particle size of the titanyl phthalocyanine crystal particles was larger than 0.25 μm, the influence of background stains due to the aggregates was clearly increased. Furthermore, those using a bifunctional monomer or a low molecular charge transport material having no functional group as a crosslinkable charge transport layer component have low wear resistance due to low crosslink density and uneven curing reaction. Deterioration is remarkable. In addition, in the photoreceptor where the film thickness of the crosslinkable charge transport layer does not reach 1 μm, the charge transport material contained in the charge transport layer diffuses into the crosslinkable charge transport layer, causing uneven wear and abnormal wear due to crosslink inhibition, As a result, halftone density unevenness and background contamination due to poor cleaning occurred. A photoconductor in which the entire charge transport layer is replaced with a cross-linked charge transport layer cannot be provided with a long life due to film peeling due to a large internal stress. A photoconductor using a conventional thermoplastic binder resin in the charge transport layer without providing a cross-linked charge transport layer has lower wear resistance and lower durability than the photoconductor of the present invention. In the case where a protective layer containing a filler is provided instead of the cross-linked charge transport layer of the present invention, the effect of an increase in the potential of the exposed area is large due to repeated use over a long period of time, and image defects in which countless black spots occur frequently occur. did. When the surfaces of these photoreceptors were observed, it was found that many foreign substances that appeared to be toner components were adhered, which was due to defective cleaning. In addition, the effect of image blur is significantly increased depending on the filler type.

  Therefore, in the photoreceptor in which the charge generation layer, the charge transport layer, and the cross-linked charge transport layer of the present invention are laminated, as a charge generation layer, a diffraction peak (± 0.2) with respect to CuKα rays (wavelength 1.542Å) is used. (°) has a maximum diffraction peak at least 27.2 °, and further has main peaks at 9.4 °, 9.6 °, 24.0 °, and 7 as the lowest diffraction peak. Has a peak at .3 °, no peak between the peak at 7.3 ° and the peak at 9.4 °, and has a peak at 26.3 °, with an average primary particle size of 0. By using titanyl phthalocyanine crystal having a thickness of .25 μm or less, it is possible to improve the margin of the background stain, improve the electrostatic stability, and improve the environmental stability, and does not have a charge transporting structure as a cross-linked charge transporting layer. Trifunctional or higher radical polymerization It is formed by curing a functional polymerizable monomer and a radical polymerizable compound having a monofunctional charge transporting structure, and further by making the film thickness 1 μm or more and 10 μm, cracks and film peeling do not occur and wear resistance Only when combined with these photoconductors are they capable of suppressing the occurrence of background stains not only in the initial stage but also in repeated use over a long period of time, and stable in any environment. It became possible to obtain images, and it was found that high-quality images can be provided stably over a long period of time. In addition, it has become clear that the image forming process, the image forming apparatus, and the process cartridge for the image forming apparatus using the photoconductor of the present invention have high performance, high reliability, and can improve the life of the apparatus. .

  Finally, 7.3 ° which is the lowest angle peak of the Bragg angle θ, which is a feature of the titanyl phthalocyanine crystal used in the present invention, will be verified as to whether or not it is the same as the lowest angle 7.5 ° of known materials.

(Measurement Example 1)
3% by weight of the pigment obtained in Comparative Synthesis Example 2 (minimum angle 7.3 °) prepared in the same manner as the pigment described in Patent Document 20 (having a maximum diffraction peak at 7.5 °) was added, The mixture was mixed in a mortar, and the X-ray diffraction spectrum was measured as before. The X-ray diffraction spectrum of Measurement Example 1 is shown in FIG.

(Measurement example 2)
To the pigment obtained in Comparative Synthesis Example 3 (minimum angle 7.5 °), 3% by weight of a pigment prepared in the same manner as the pigment described in Patent Document 20 (having a maximum diffraction peak at 7.5 °) was added, The mixture was mixed in a mortar, and the X-ray diffraction spectrum was measured as before. The X-ray diffraction spectrum of Measurement Example 2 is shown in FIG.

  In the spectrum of FIG. 15, it can be seen that there are two independent peaks at 7.3 ° and 7.5 ° on the lower angle side, and at least the peaks at 7.3 ° and 7.5 ° are different. . On the other hand, in the spectrum of FIG. 16, the low angle side peak exists only at 7.5 °, which is clearly different from the spectrum of FIG.

  From the above, it can be seen that the minimum angle peak of 7.3 ° in the titanyl phthalocyanine crystal of the present invention is different from the 7.5 ° peak in the known titanyl phthalocyanine crystal.

It is a TEM image of amorphous titanyl phthalocyanine (low crystalline titanyl phthalocyanine). It is a TEM image of a titanyl phthalocyanine crystal when crystal conversion is performed over time. It is a TEM image of a titanyl phthalocyanine crystal when crystal conversion is performed in a short time. It is the photograph of the dispersion liquid which shortened the dispersion time when obtaining the crystal | crystallization of titanyl phthalocyanine. It is a photograph of the dispersion liquid which extended dispersion time when obtaining the crystal of titanyl phthalocyanine. The average particle size and particle size distribution of the two types of dispersions are measured with a commercially available particle size distribution measuring device in a graph. FIG. 3 is a cross-sectional view illustrating a configuration example of a photoreceptor of the present invention. 1 is a schematic cross-sectional view illustrating an example of an image forming apparatus of the present invention. It is a schematic sectional drawing which shows an example of the process cartridge of this invention. 1 is a schematic cross-sectional view showing an example of an image forming apparatus in which a plurality of image forming elements of the present invention are arranged. 2 is an X-ray diffraction spectrum of a dry powder of water paste obtained in Comparative Synthesis Example 1 of titanyl phthalocyanine. 3 is an X-ray diffraction spectrum of a crystal obtained in Synthesis Example 2 of titanyl phthalocyanine. 3 is an X-ray diffraction spectrum of a crystal obtained in Comparative Synthesis Example 2 of titanyl phthalocyanine. 3 is an X-ray diffraction spectrum of a crystal obtained in Comparative Synthesis Example 3 of titanyl phthalocyanine. 3 is an X-ray diffraction spectrum of Measurement Example 1. 4 is an X-ray diffraction spectrum of Measurement Example 2.

Explanation of symbols

1C, 1M, 1Y, 1K Photoconductor 2C, 2M, 2Y, 2K Charging member 3C, 3M, 3Y, 3K Laser light 4C, 4M, 4Y, 4K Developing member 5C, 5M, 5Y, 5K Cleaning member 6C, 6M, 6Y , 6K image forming element 10 transfer conveying belt 11C, 11M, 11Y, 11K transfer brush 12 fixing device 101 photoconductor 102 charging means 103 exposure 104 developing means 105 cleaning means 107 transfer body 110 transfer means

Claims (19)

  In an electrophotographic photosensitive member in which a charge generation layer, a charge transport layer, and a cross-linked charge transport layer are sequentially laminated on at least a conductive support, diffraction with a Bragg angle 2θ with respect to CuKα rays (wavelength 1.542 mm) in the charge generation layer As a peak (± 0.2 °), it has a maximum diffraction peak at least 27.2 °, and further has major peaks at 9.4 °, 9.6 °, 24.0 °, and the lowest angle. As a side diffraction peak, it has a peak at 7.3 °, has no peak between the 7.3 ° peak and the 9.4 ° peak, and has a peak at 26.3 °. A trifunctional or higher-functional radically polymerizable monomer containing a titanyl phthalocyanine crystal having an average particle size of 0.25 μm or less and the crosslinked charge transporting layer having no charge transporting structure and a monofunctional charge transporting structure. Has radical polymerizability An electrophotographic photosensitive member formed by curing a compound, wherein the cross-linked charge transport layer has a thickness of 1 μm or more and 10 μm or less.   2. The electrophotographic image according to claim 1, wherein the titanyl phthalocyanine crystal has a peak intensity of 26.3 ° in a range of 0.1 to 5% with respect to a peak intensity of a maximum diffraction peak of 27.2 °. Photoconductor.   Dispersion was carried out until the average particle size of the titanyl phthalocyanine crystal particles was 0.3 μm or less and the standard deviation thereof was 0.2 μm or less, and then the dispersion was filtered through a filter having an effective pore size of 3 μm or less. The electrophotographic photosensitive member according to claim 1, wherein a charge generation layer is applied.   The titanyl phthalocyanine crystal has a maximum diffraction peak at 7.0 to 7.5 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to CuKα characteristic X-ray (wavelength 1.542 mm), Amorphous titanyl phthalocyanine or low crystalline titanyl phthalocyanine having a half-width of the diffraction peak of 1 ° or more and an average particle size of 0.1 μm or less is subjected to crystal conversion with an organic solvent in the presence of water, and the average after crystal conversion The electrophotographic photosensitive member according to claim 1 or 2, wherein the titanyl phthalocyanine after crystal conversion is fractionated and filtered from an organic solvent before the grain size grows larger than 0.25 µm.   The electrophotographic photoreceptor according to claim 1, wherein the cross-linked charge transport layer is insoluble in an organic solvent.   6. The functional group of a tri- or higher functional radical polymerizable monomer having no charge transport structure used in the cross-linked charge transport layer is an acryloyloxy group and / or a methacryloyloxy group. The electrophotographic photosensitive member according to any one of the above.   The ratio of the molecular weight to the number of functional groups (molecular weight / number of functional groups) in a trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used for the crosslinkable charge transporting layer is 250 or less. The electrophotographic photosensitive member according to any one of 1 to 6.   The functional group of the radically polymerizable compound having a monofunctional charge transporting structure used for the crosslinkable charge transporting layer is an acryloyloxy group or a methacryloyloxy group. The electrophotographic photosensitive member according to Item.   The charge transport structure of the radical polymerizable compound having a monofunctional charge transport structure used for the cross-linked charge transport layer is a triarylamine structure. The electrophotographic photosensitive member described. 10. The radical polymerizable compound having a monofunctional charge transport structure used for the cross-linked charge transport layer is at least one of the following general formulas (1) or (2). The electrophotographic photosensitive member according to any one of the above.
(Wherein R ₁ is a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen A carbonyl group or —CONR ₈ R ₉ (R ₈ and R ₉ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Ar ₁ and Ar ₂ each represent a substituted or unsubstituted arylene group and may be the same or different.Ar ₃ may be the same or different from each other. , Ar ₄ is a substituted or unsubstituted a X is a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, A sulfur atom or 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.) The radically polymerizable compound having a monofunctional charge transporting structure used for the cross-linked charge transporting layer is at least one of the following general formula (3). The electrophotographic photosensitive member according to Item.
(Wherein, o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,
Represents. )   The proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the crosslinkable charge transport layer is 30 to 70% by weight based on the total amount of the crosslinkable charge transport layer. Item 12. The electrophotographic photosensitive member according to any one of Items 1 to 11.   2. The component ratio of the radical polymerizable compound having a monofunctional charge transporting structure used in the crosslinkable charge transport layer is 30 to 70% by weight based on the total amount of the crosslinkable charge transport layer. The electrophotographic photosensitive member according to any one of Items 1 to 12.   The electrophotographic photosensitive member according to any one of claims 1 to 13, wherein the curing means for the cross-linked charge transport layer is heating or light energy irradiation means.   The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer contains a polymer charge transport material.   The electrophotographic photosensitive member according to any one of claims 1 to 15, wherein the electrophotographic photosensitive member includes at least a charging unit, an exposing unit, a developing unit, a transfer unit, and an electrophotographic photosensitive member. An image forming apparatus characterized by being a body.   17. The image forming apparatus according to claim 16, wherein a plurality of image forming elements including at least a charging unit, an exposure unit, a developing unit, a transfer unit, and an electrophotographic photosensitive member are arranged.   A cartridge in which an electrophotographic photosensitive member and at least one means selected from a charging means, an exposure means, a developing means, and a cleaning means are mounted, and the cartridge is detachable from the apparatus main body. The image forming apparatus according to claim 16 or 17.   The process cartridge for an image forming apparatus in which at least one means selected from a charging means, an exposure means, a developing means, and a cleaning means and an electrophotographic photosensitive member are integrated, wherein the electrophotographic photosensitive member is defined in any one of claims 1 to 15. A process cartridge for an image forming apparatus, which is the electrophotographic photosensitive member according to any one of the above.