JP2010217612A - Electrophotographic photoreceptor, image forming apparatus, and process cartridge for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoreceptor having excellent wear resistance, suppressing potential increase in a bright portion, suppressing rapid potential increase in a bright portion when images are continuously output, and having a long lifetime and enhanced image quality stability. <P>SOLUTION: The photoreceptor includes at least: a charge generating layer 32, a first charge transporting layer 33 containing a charge transporting substance having a triarylamine structure and an arylamine compound having at least one substituted or unsubstituted alkylamino group, a second charge transporting layer 34 containing a charge transporting substance having a triarylamine structure and an arylamine compound, which is the same as contained in the first charge transporting layer, having at least one substituted or unsubstituted alkylamino group, and a specified crosslinked charge transporting layer 35, successively layered on a conductive support 31. The weight ratio C1 of the arylamine compound to the solid content weight in the first charge transporting layer and the weight ratio C2 of the arylamine compound to the solid content weight in the second charge transporting layer satisfies the following expression: 0≤C2<C1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a laser printer, and a facsimile, a process cartridge, and an electrophotographic photosensitive member used for them. Specifically, the present invention relates to an electrophotographic photoreceptor excellent in image quality stability and durability, a process cartridge for an image forming apparatus using the same, and an image forming apparatus.

  In recent years, organic photoreceptors have been widely used for electrophotographic photoreceptors (hereinafter also simply referred to as photoreceptors). For organic photoreceptors, it is easy to develop materials compatible with various exposure light sources from visible light to infrared light, to select materials that are less affected by environmental pollution, and to reduce manufacturing costs. There are many advantages. However, organic photoreceptors are weaker in physical and chemical strength than inorganic photoreceptors, and are subject to wear and scratches after long-term use, leaving significant problems in durability and image stability.

An electrophotographic image forming apparatus generally includes an electrophotographic photosensitive member, a charger for charging the electrophotographic photosensitive member, and a latent image for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charger. Forming device, developing device for attaching toner to the electrostatic latent image formed by the latent image forming device, transfer means for transferring the attached toner to the transfer object, and toner remaining on the surface of the photoreceptor without being transferred It is provided with a cleaning device or the like that removes water.
In the organic photoreceptor, the surface of the photoreceptor is chemically or physically deteriorated by repeating the steps such as charging, development, transfer, and cleaning as described above, and wear is promoted or scratches are formed. As a result, the image quality deteriorates at an early stage, so that the wear resistance of the organic photoreceptor has been regarded as one of the most important issues. On the other hand, many techniques for providing a protective layer for the purpose of improving the wear resistance of the organic photoreceptor are disclosed.

For example, many techniques for improving mechanical durability by providing a protective layer on the outermost surface of the photoreceptor and dispersing inorganic fine particles in the protective layer are disclosed. As an example, Patent Document 1 proposes an electrophotographic photoreceptor in which at least a photosensitive layer and a protective layer containing a filler are sequentially formed on a conductive support.
As another means, many techniques for improving by increasing the hardness of the photoreceptor surface have been disclosed. For example, in Patent Document 2 and Patent Document 3, when a magnetic brush type is applied as a charger, magnetic particles are involuntarily transferred onto the photoconductor, and the particles are transferred to the photoconductor in the transfer unit or the cleaning unit. It has been proposed to increase the hardness of the photoconductor protective layer in order to prevent scratching due to strong pressing. Further, Patent Document 4 proposes to increase the hardness of the photoconductor in order to suppress photoconductor surface wear when the blade-type cleaning method is applied.
As specific means for increasing the surface hardness of the photoreceptor as described above, it has been proposed to use a crosslinkable material such as a thermosetting resin or a UV curable resin as a constituent component of the photoreceptor protective layer. For example, Patent Documents 5 to 7 propose methods for improving the wear resistance and scratch resistance of the protective layer by applying a thermosetting resin as a binder component of the protective layer.

Patent Documents 8 to 10 disclose a technique for improving wear resistance and scratch resistance by incorporating a siloxane resin bonded with a charge transporting ability imparting group into a protective layer.
Further, in Patent Document 11, in order to improve wear resistance and scratch resistance, a charge transport layer is formed using a monomer having a carbon-carbon double bond, a charge transport material having a carbon-carbon double bond, and a binder resin. Techniques for making them have been reported.
Patent Document 12 describes a method of forming a charge transport layer 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. Has been. Further, Patent Document 22 discloses a method for forming a protective layer in which a trifunctional or higher functional radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a charge transporting structure are cured and further a filler is dispersed. Is described.
By using the above-described means, the wear resistance of the photoreceptor is dramatically improved. In particular, a photoreceptor using the curable resin described in Patent Document 12 or Patent Document 22 as a protective layer is excellent in wear resistance and scratch resistance.

  However, although the wear resistance and scratch resistance are remarkably improved by these techniques, the actual life as a photoreceptor is not improved as expected. This is because the provision of the protective layer increases the bright portion potential and causes image quality degradation such as image flow. In particular, an increase in the bright portion potential causes a decrease in image density. When the dark portion potential is increased to suppress the increase, the electric field strength is increased, thereby causing image defects such as background stains. Moreover, it is thought that the increase in the light portion potential leads to worsening the negative ghost. If the transfer bias polarity is opposite to the photoconductor charging polarity, and the negative ghost is charged to a polarity opposite to the photoconductor charging polarity by the transfer bias, this potential cannot be canceled by the photostatic discharge, It occurs when the history of the previous electrostatic latent image remains, and when the bright part potential rises, the history of the electrostatic latent image appears strongly, so the negative ghost is thought to deteriorate.

Therefore, in order to achieve high image quality stabilization, it is important to suppress the rise in the bright portion potential, but there are many problems associated therewith. Details are described below.
The cause of the bright portion potential increase is largely due to charge traps in the interface between the charge generation layer and the charge transport layer, the interface between the charge transport layer and the protective layer, or the bulk of the charge transport layer and the protective layer.
Among these charge trapping factors, the influence of the interface between the charge generation layer and the charge transport layer and the interface between the charge transport layer and the protective layer is particularly great. Therefore, as one means for reducing the bright portion potential, a material having a smaller ionization potential is used for the charge transport material contained in the charge transport layer, and the charge injection barrier from the charge generation layer to the charge transport layer can be reduced. Can be mentioned. As an example of these known techniques, Patent Document 13 and the like are disclosed, which is an effective method for reducing the light portion potential.
In particular, metal phthalocyanine pigments, in particular titanyl phthalocyanine, have a low ionization potential, and in order to reduce the light potential in a photoreceptor using this as a charge generation material, an ionization potential equal to or lower than that of metal phthalocyanine is required. It is necessary to include the charge transport material having the charge transport layer in the charge transport layer.

On the other hand, as another means for reducing the bright portion potential, it is disclosed that it is effective to reduce the charge injection barrier from the charge transport layer to the protective layer. For example, as described in Patent Document 14, the charge transporting material contained in the protective layer has a lower ionization potential than the charge transporting material contained in the photosensitive layer, so that the photosensitive layer / protective layer interface has a lower ionization potential. It is effective to improve the charge injection property. Further, as described in Patent Document 15, the ionization potential values of the charge generation material and the charge transport material are in an optimal relationship, and the ionization potential of the charge transport material in the protective layer is set to the ionization potential of the charge transport material in the charge transport layer. By making the following, the increase in the residual potential can be suppressed. As described above, it is known that the light-portion potential can be reduced by causing the charge transport material contained in the protective layer to have a lower ionization potential than the charge transport material contained in the charge transport layer. .
Moreover, the effect which can suppress generation | occurrence | production of a ghost can be acquired by reducing the electric charge injection barrier from a charge transport layer to a protective layer. For example, Patent Document 16 describes that ghosting can be suppressed by reducing the difference in ionization potential between the photosensitive layer and the protective layer. Japanese Patent Application Laid-Open No. H10-228561 describes that an increase in bright portion potential can be suppressed by reducing a difference in oxidation potential between the charge transport material of the photosensitive layer and the charge transport material of the protective layer.

Therefore, in order to achieve high image quality by reducing the bright part potential of the photoreceptor and suppressing ghosts based on the conventionally known technology, the charge transport layer has an ionization potential equal to or lower than that of the charge generation material. This can be achieved by including a charge transport material and further including a charge transport material having an ionization potential equal to or lower than that of the charge transport material contained in the charge transport layer in the protective layer.
However, when a phthalocyanine pigment having a low ionization potential is used as the charge generation material, the ionization potential of the charge transport material contained in the layer formed on the outermost surface of the photoreceptor is inevitably low. A new problem occurs that causes image flow. As described above, the surface of the photoreceptor is easily deteriorated by repeating processes such as charging, development, and cleaning. In particular, it is believed that when exposed to an oxidizing gas such as ozone generated by charging, the charge transport material contained on the surface of the photoreceptor is altered and the resistance is lowered. A charge transport material having a smaller ionization potential has a greater effect, and thus an image stream is generated by repeated use of the photoreceptor.

Patent Document 18 discloses a technique that defines the ionization potential difference between the photosensitive layer and the curable resin layer and the time response of the photoreceptor. This patent document describes that a good dot image can be formed even under high temperature and high humidity and low temperature and low humidity. Further, Y-type titanyl phthalocyanine is exemplified as the charge generation material of the examples. However, the ionization potential of the charge transport layer used in the examples is considerably larger than the ionization potential of the charge generation layer. That is, although an effect of suppressing the image flow can be obtained, it is difficult to reduce the bright part potential, and it is considered to be based on the sacrifice. In the comparative example, a charge transport layer having an ionization potential smaller than that of titanyl phthalocyanine is exemplified. However, since the charge transport layer is much smaller than the ionization potential of the protective layer, it is clear that the chargeability is significantly deteriorated.
Also in Patent Document 15, it is considered that the effect of suppressing the increase in residual potential is high by setting the ionization potential of the charge transport material in the protective layer to be equal to or lower than the ion transport potential of the charge transport material in the charge transport layer. If a charge transport material having a small ionization potential is included in the protective layer located on the body surface, it is considered that the problem of image flow occurs as described above. However, in the example of Patent Document 15, only the result of EPA for evaluating electrostatic characteristics is described, and the image is not confirmed. Even if the increase in the residual potential can be suppressed, the function as a photoconductor cannot be exhibited if an image flow occurs in an oxidizing gas atmosphere, and a fundamental solution has not been reached.

  As described above, the reduction of the bright part potential and the suppression of the bright part potential increase due to repeated use can be achieved by a conventionally known technique. However, when a metal phthalocyanine pigment having high sensitivity is used for the charge generation material, Since these generally have a low ionization potential, it is necessary to further reduce the ionization potential of the charge transport material contained in the charge transport layer or the protective layer in order to suppress the bright part potential rise. Even if it can be suppressed, new problems such as image flow are caused. For this reason, it is difficult to achieve both reduction of the bright area potential and high stabilization of the image quality in the photoreceptor using the metal phthalocyanine pigment, which is particularly advantageous in terms of sensitivity characteristics. Regardless, the reality is that high durability of the photoreceptor has not been realized.

On the other hand, a method for stabilizing the image quality by adding an additive to the photosensitive layer or the crosslinkable protective layer is known. For stabilizing the image quality, it is effective to contain an antioxidant in the photosensitive layer. However, when such an additive having only an antioxidant ability is used, its characteristic expression depends on the amount of antioxidant added, so that a considerable amount of addition is necessary to obtain a sufficient effect. May be. However, when the antioxidant does not have charge transportability, the charge transportability is likely to decrease in proportion to the amount added, and as a result, the bright part potential may increase.
In particular, when the ionization potential difference among the charge generation layer, the charge transport layer, and the protective layer is large and the injection barrier is large, the bright portion potential is likely to increase.

  Patent Documents 23 to 27 describe a method of stabilizing electrophotographic characteristics by combining a distyryl compound and an antioxidant. However, the evaluation result is limited only to the electrical characteristics, and no image is output. When a distyryl compound having a low ionization potential is present on the outermost surface, intense image flow may occur after exposure to NOx. Since it is often impossible to determine whether or not there is an image flow only by electrical characteristics, there is a possibility that the image quality cannot be sufficiently stabilized by the methods described in Patent Documents 23 to 27.

Patent Documents 19 to 21 describe a method for achieving high stabilization of image quality by adding an antioxidant having a charge transport function to a photosensitive layer or a crosslinked protective layer. Although such an additive is an antioxidant, it has a charge transporting property and is therefore used very effectively. That is, combining the cross-linkable protective layer described in Patent Documents 19 to 21 and an antioxidant having a charge transporting function greatly contributes to extending the life of the photoreceptor.
However, the combination of the crosslinkable protective layer described in Documents 19 to 21 and the antioxidant having a charge transport function may cause another problem of a sharp increase in the light potential in a short time. Specifically, when 100 sheets are output continuously, the light portion potential rapidly increases between the first sheet and the 100th sheet. The amount of increase in the bright portion potential tends to increase with the use of the photoreceptor. Since the potential increase amount reaches several tens of volts, the image densities of the first and 100th sheets are different. In order to maintain the image density, process control is performed in the main body. However, since the potential rises earlier than the process control timing, it is difficult to keep the image density constant. As described above, the rapid bright portion potential increase may be remarkably exhibited in the cross-linkable protective layer having excellent mechanical strength.

  Patent Documents 28 and 29 describe an electrophotographic photoreceptor in which a plurality of charge transport layers are stacked, and the charge transport layer on the outermost surface side contains a large amount of an antioxidant. This structure has an antioxidant on the surface that is easily influenced by NOx gas, and thus is effective for long-term image stabilization. However, when combined with the cross-linkable protective layer described in Patent Document 12 or Patent Document 22, this structure is abrupt. Bright part potential rise may occur. Patent Document 30 includes a combination of a tri- or higher functional radical polymerizable monomer, a crosslinked protective layer obtained by curing a radical polymerizable compound having a charge transport structure, and two charge transport layers. This is configured to facilitate the diffusion of the charge transport material into the crosslinkable protective layer. However, in this configuration, when a charge transport material having a low ionization potential is used, the charge transport material diffused in the cross-linked protective layer may cause image flow due to exposure to an oxidizing gas such as NOx.

As described above, by providing the crosslinkable protective layer described in Patent Document 12 or Patent Document 22, the wear resistance is drastically improved, but there is a problem that the bright portion potential is increased. In order to suppress the bright portion potential rise, the ionization potentials of the charge generation layer, the charge transport layer, and the crosslinkable protective layer need to be in an optimal relationship. Such a configuration makes it possible to extend the life of the photoreceptor, but in order to extend the life, it is possible to contain an antioxidant or an antioxidant having charge transporting property in the photosensitive layer. Necessary. Antioxidants having charge transporting properties are effective for long-term image quality stabilization and NOx gas exposure, but may have a side effect of a sharp increase in light potential.
Thus, when the life of the photoconductor is mechanically extended, the electrophotographic process is repeated numerous times, and the load on the photoconductor is increased. Antioxidants are often used for this purpose, but side effects can also occur. That is, a technique for producing an ultra-long life photoconductor has not yet been established.

  As mentioned above, it is extremely difficult to design an electrophotographic photoreceptor that suppresses the increase in bright area potential, and maintains excellent wear resistance and high image quality stability over a long period of time. At present, it is necessary to design the electrophotographic photosensitive member.

  Therefore, the present invention has been made in view of the above-described problems of the prior art, and is excellent in wear resistance, suppresses the bright part potential rise, and causes a sharp bright part potential rise when continuously outputting images. It is an object of the present invention to provide a long-life photoconductor that is suppressed and has improved image quality stability.

The above problems are solved by the following (1) to (24).
(1) At least a charge generating layer, a first charge transport layer, a second charge transport layer, a radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a charge transport structure on a conductive support. In the electrophotographic photosensitive member formed by sequentially laminating a crosslinkable charge transport layer,
The first charge transport layer contains a charge transport material having a triarylamine structure and an arylamine compound having at least one substituted or unsubstituted alkylamino group,
The second charge transport layer comprises a charge transport material having a triarylamine structure and an arylamine compound having at least one substituted or unsubstituted alkylamino group, the same as the compound contained in the first charge transport layer Containing
The weight ratio of the arylamine compound having at least one alkylamino group to the solid content weight of the first charge transport layer is C1,
When the weight ratio of the arylamine compound having at least one alkylamino group to the solid content weight of the second charge transport layer is C2,
The following equation (1) holds: 0 ≦ C2 <C1 (1)
An electrophotographic photosensitive member characterized by the above.
(2) Further, the following formula (2) holds for the C1 0.005 <C1 <0.15 (2)
(1) The electrophotographic photosensitive member according to (1).
(3) The functional group of the radical polymerizable monomer having no charge transporting structure and / or the functional group of the radical polymerizable compound having the charge transporting structure is an acryloyloxy group and / or a methacryloyloxy group. The electrophotographic photosensitive member according to (1) or (2), characterized in that it is characterized.
(4) The radical polymerizable monomer having no charge transporting structure has 3 or more functional groups, and the ratio of molecular weight to the number of functional groups (molecular weight / functional group number) is 250 or less (1) The electrophotographic photosensitive member according to any one of to (3).
(5) The electrophotographic photosensitive member according to any one of (1) to (4), wherein a charge transporting structure of the radical polymerizable compound having the charge transporting structure is a triarylamine structure.
(6) A radically polymerizable compound having the charge transporting structure is
The electrophotographic photosensitive member according to any one of (1) to (5), which is at least one of the compounds represented by the following general formula (1) or (2).

(Wherein R ₄₀ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, A group, an alkoxy group, —COOR ₄₁ (R ₄₁ represents 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. ), A halogenated carbonyl group or CONR ₄₂ R ₄₃ (R ₄₂ and R ₄₃ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or a substituent. Represents an aryl group which may be the same or different from each other. Ar ₂ and Ar ₃ represent a substituted or unsubstituted arylene group and may be the same or different. Ar ₄ and Ar ₅ are substituted. X represents an unsubstituted aryl group, which may be the same or different, and X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group. Represents 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 each represents an integer of 0 to 3. )
(7) The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the arylamine compound having at least one alkylamino group is represented by the following general formula (4-1).

(In the formula, R ₉₂ and R ₉₃ represent an aromatic ring group-substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, which may be the same or different. R ₉₂ and R ₉₃ are bonded to each other to form a nitrogen atom. And j and k each represent an integer of 0 to 3. However, j and k are not simultaneously 0. R ₉₄ and R ₉₅ are hydrogen atoms, substituted or unsubstituted. Represents an alkyl group having 1 to 11 carbon atoms and a substituted or unsubstituted aromatic ring group, which may be the same or different, and Ar ₅₁ and Ar ₅₂ each represent a substituted or unsubstituted aromatic ring group and are the same But it may be different.)
(8) The electrophotographic photosensitive member according to any one of (1) to (6), wherein the arylamine compound having at least one alkylamino group is represented by the following general formula (5-1): .

(In the formula, R ₉₆ and R ₉₇ represent a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted alkyl group, and may be the same or different, provided that at least one of R ₉₆ and R ₉₇ One is a substituted or unsubstituted alkyl group, and R ₉₆ and R ₉₇ may be bonded to each other to form a heterocyclic group containing a nitrogen atom, Ar ₅₃ and Ar ₅₄ are substituted or unsubstituted aromatic groups. (P and q each represent an integer of 0 to 3. However, p and q are not simultaneously 0. r represents an integer of 1 to 3)
(9) The electrophotographic photosensitive member according to any one of (1) to (6), wherein the arylamine compound having at least one alkylamino group is represented by the following general formula (5-2): .

(In the formula, R ₉₈ and R _{99 each} represents a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted alkyl group, and may be the same or different, provided that at least one of R ₉₆ and R ₉₇ One is a substituted or unsubstituted alkyl group, and R ₉₈ and R ₉₉ may be bonded to each other to form a heterocyclic group containing a nitrogen atom, and Ar ₅₅ and Ar ₅₆ are substituted or unsubstituted aromatic groups. S and t each represent an integer of 0 to 3. However, s and t are not simultaneously 0. u represents an integer of 1 to 3.)
(10) The electrophotographic photosensitive member according to any one of (1) to (6), wherein the arylamine compound having at least one alkylamino group is represented by the following general formula (6).

(In the formula, R ₁₀₁ and R ₁₀₂ represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic ring group, and may be the same or different. However, any one of R ₁₀₁ and R ₁₀₂ may be used. is a substituted or unsubstituted alkyl group. Further, R _101, R ₁₀₂ is bonded to each other, may .Ar ₅₇ also form a substituted or unsubstituted heterocyclic group containing a nitrogen atom of a substituted or unsubstituted Represents an aromatic ring group.)
(11) Any one of (1) to (10), wherein the charge transport material having a triarylamine structure contained in the first charge transport layer and the second charge transport layer is a distyryl compound. The electrophotographic photoreceptor described in 1.
(12) The electron according to any one of (1) to (11), wherein the distyryl compound having a triarylamine structure is a distyrylbenzene derivative represented by the general formula (3) having the following structure: Photoconductor.

[Wherein R _{1 to} R ₃₀ are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms. An aryl group substituted with an alkoxy group and an unsubstituted aryl group are represented and may be the same or different. ]
(13) The electrophotographic image described in (12), wherein at least one of R ₃ , R ₈ , R ₁₉ and R ₂₄ of the distyrylbenzene derivative represented by the general formula (3) is a methyl group. Photoconductor.
(14) The first charge transport layer and / or the second charge transport layer contains at least one antioxidant selected from a hindered phenol derivative and a hindered amine derivative (1) The electrophotographic photosensitive member according to any one of to (13).
(15) The electrophotographic photoreceptor as described in (14), wherein the antioxidant is a compound having a hindered phenol structure and a hindered amine structure in the same molecule.
(16) The charge generation layer contains one or more selected from titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine as a charge generation material. The electrophotographic photosensitive member according to any one of the above.
(17) The titanyl phthalocyanine has a maximum intensity diffraction peak at least 27.2 ° of the black angle (2θ ± 0.2 °) in an X-ray diffraction spectrum using CuKα characteristic X-rays (1.542 °). Having a main peak at 9.4 °, 9.6 °, 24.0 °, a diffraction peak with a minimum angle at 7.3 °, and a peak at 7.3 ° The electrophotographic photosensitive member according to (16), which is a titanyl phthalocyanine crystal having no diffraction peak between 2 ° and a diffraction peak at 26.3 °.
(18) The film thickness T1 of the first charge transport layer and the film thickness T2 of the second charge transport layer satisfy the relationship of the following formula (3): (1) to (17) The electrophotographic photosensitive member according to any one of the above.
T1> T2 × 2 Formula (3)
(19) The film thickness T1 of the first charge transport layer, the film thickness T2 of the second charge transport layer, and the film thickness T3 of the bridged charge transport layer satisfy the relationship of the following formula (4). The electrophotographic photosensitive member according to any one of (1) to (18).
T1 + T2> T3 × 2 Formula (4)
(20) The electrophotographic photosensitive member according to any one of (1) to (19), wherein the crosslinkable charge transport layer contains a filler.
(21) The method for producing an electrophotographic photosensitive member according to claim 1,
Forming a charge generation layer on a conductive support;
On the charge generation layer, a coating liquid containing a charge transport material having a triarylamine structure and an arylamine compound having at least one substituted or unsubstituted alkylamino group is applied to form a first charge. Forming a transport layer;
A charge transport material having a triarylamine structure on the first charge transport layer and an aryl having at least one substituted or unsubstituted alkylamino group identical to the compound contained in the first charge transport layer; Applying a coating liquid containing an amine compound to form a second charge transport layer;
A coating liquid containing a radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a charge transporting structure is applied on the second charge transporting layer and cured to form a cross-linked charge transporting layer. Forming a process,
The weight ratio of the arylamine compound having at least one alkylamino group to the solid content weight of the first charge transport layer is C1, and the aryl having at least one alkylamino group to the solid content weight of the second charge transport layer When the weight ratio of the amine compound is C2, the following formula (1) holds: 0 ≦ C2 <C1 (1)
A method for producing an electrophotographic photosensitive member, characterized in that it is configured as described above.
(22) 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 (20) An image forming apparatus which is an electrophotographic photosensitive member.
(23) 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, and the electrophotographic photosensitive member is any one of (1) to (20). An image forming apparatus which is an electrophotographic photosensitive member.
(24) A cartridge in which an electrophotographic photosensitive member and at least one means selected from a charging means, an exposure means, a developing means, a transfer means, and a cleaning means are integrated, and the cartridge is attached to and detached from the apparatus main body. The image forming apparatus according to (22) or (23), wherein the image forming apparatus is free.
(25) In a process cartridge for an image forming apparatus in which an electrophotographic photosensitive member is integrated with at least one unit selected from a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit, 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 (20) to (20).

  The electrophotographic photosensitive member of the present invention is excellent in wear resistance and scratch resistance by providing a crosslinkable charge transport layer on the surface, is stable with little increase in bright part potential even after repeated use, and repeats Even if the signal is continuously output after use, the rise in the bright portion potential is small. Therefore, it is possible to provide an electrophotographic photosensitive member, an image forming apparatus, and a process cartridge for an image forming apparatus that can stably output high image quality even when used repeatedly for a long time.

  According to the photoreceptor of the present invention, the first charge transport layer, the second charge transport layer, and the cross-linked charge transport layer are provided on the charge generation layer, and at least one of the first charge transport layer coating liquid is provided. The concentration of the arylamine compound having a substituted or unsubstituted alkylamino group is made larger than the concentration of the arylamine compound having at least one substituted or unsubstituted alkylamino group in the second charge transport layer coating solution. A long-life electrophotographic photosensitive member that has excellent wear resistance, suppresses the bright area potential rise, can suppress the rapid bright area potential rise when continuously outputting images, and has improved image quality stability. Realized.

It is sectional drawing which shows the structural example of the electrophotographic photoreceptor in this invention. 1 is a schematic diagram illustrating an example of an image forming apparatus according to the present invention. It is a figure which shows an example of the process cartridge in this invention. It is an X-ray diffraction spectrum diagram of the charge generation material used in the examples, the vertical axis represents the counts per second (cps: counts per second), and the horizontal axis represents the angle (2θ).

In the present invention, the reason why both the rapid bright portion potential increase suppression and the image density increase suppression due to NOx gas exposure can be achieved at the same time will be described. The increase in image density due to exposure to NOx gas can be suppressed by containing an arylamine compound having at least one substituted or unsubstituted alkylamino group in the charge transport layer. This arylamine compound diffuses into the crosslinkable charge transport layer due to heat applied in the drying step after coating the crosslinkable charge transport layer. When this arylamine compound is contained in the cross-linked charge transport layer, the reason is not clear, but when the image is continuously output, a sharp bright portion potential may increase. The bright part potential rise tends to worsen with repeated use.
That is, in order to suppress a rapid bright portion potential increase due to continuous image output, it is desirable that the content of the arylamine compound in the cross-linked charge transport layer is small. Therefore, the arylamine content in the second charge transport layer coating solution was made smaller than the arylamine content in the first charge transport layer coating solution. Thereby, it is considered that the diffusion amount of the arylamine compound was reduced in the drying step after the application of the crosslinkable charge transport layer, and a rapid bright portion potential increase due to continuous image output could be suppressed. Japanese Patent Application Laid-Open No. 2008-2008, in which a crosslinkable charge transport layer, a first charge transport layer, and a second charge transport layer are combined, and a charge transport material in the second charge transport layer is actively diffused into the crosslinkable charge transport layer This is a configuration different from the 70676 publication.

The image forming apparatus of the present invention will be described in detail below with reference to the drawings.
<< Configuration of electrophotographic photoreceptor >>
As shown in FIG. 1, the photoreceptor of this embodiment includes at least a charge generation layer 32, a first charge transport layer 33, a second charge transport layer 34, and a crosslinked charge transport layer on a conductive support 31. It is a laminated type characterized by having 35 in this order.

<About conductive support>
Examples of the conductive support include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, and platinum, tin oxide, and indium oxide. After metal oxide is deposited or sputtered, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. Pipes that have been subjected to surface treatment such as cutting, super-finishing, and polishing can be used. Further, endless nickel belts and endless stainless steel belts disclosed in JP-A-52-36016 can also be used as the conductive support.
In addition, those obtained by dispersing and coating conductive powder in an appropriate binder resin on the support can also be used as the conductive support of the present invention. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. Can be mentioned.

The binder resin used at the same time includes polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine Examples thereof include thermoplastic resins such as resins, urethane resins, phenol resins, and alkyd resins, thermally crosslinkable resins, and photocrosslinkable resins. Such a conductive layer can be provided by dispersing and applying these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.
Furthermore, a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, polytetrafluoroethylene-based fluororesin on a suitable cylindrical substrate. Those provided with a conductive layer can be used favorably as the conductive support of the present invention.

<< About photosensitive layer >>
Next, the charge generation layer and the charge transport layer will be described.
<About the charge generation layer>
The charge generation layer is a layer mainly composed of a charge generation material having a charge generation function, and a binder resin can be used in combination as necessary.
The charge generation layer is a layer mainly composed of a charge generation material. A known charge generation material can be used for the charge generation layer. For example, monoazo pigments, disazo pigments, asymmetrical disazo pigments, trisazo pigments, azo pigments having a carbazole skeleton (described in JP-A-53-95033), azo pigments having a distyrylbenzene skeleton (JP-A-53-133445) ), Azo pigments having a triphenylamine skeleton (described in JP-A-53-132347), azo pigments having a diphenylamine skeleton, and azo pigments having a dibenzothiophene skeleton (described in JP-A-54-21728) An azo pigment having a fluorenone skeleton (described in JP-A No. 54-22834), an azo pigment having an oxadiazole skeleton (described in JP-A No. 54-12742), an azo pigment having a bis-stilbene skeleton (special Described in Japanese Utility Model Laid-Open No. 54-17733), distyryloxadiazole skeleton Azo pigments such as azo pigments (described in JP-A No. 54-2129), azo pigments having a distyrylcarbazole skeleton (described in JP-A No. 54-14967), azulenium salt pigments, methine squaric acid Pigment, perylene pigment, anthraquinone or polycyclic quinone pigment, quinone imine pigment, diphenylmethane and triphenylmethane pigment, benzoquinone and naphthoquinone pigment, cyanine and azomethine pigment, indigoid pigment, bisbenzimidazole pigment, Examples thereof include phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine represented by the following general formula (7). These charge generation materials may be used alone or in combination of two or more.
Among these charge generation materials, metal phthalocyanine pigments and azo pigments represented by the following formula can be used effectively.

（式中Ｍ（中心金属）は、金属の元素を表す。ここであげられるＭ（中心金属）は、Ｌｉ、Ｂｅ、Ｎａ、Ｍｇ、Ａｌ、Ｓｉ、Ｋ、Ｃａ、Ｓｃ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｇａ、Ｇｅ、Ｙ、Ｚｒ、Ｎｂ、Ｍｏ、Ｔｃ、Ｒｕ、Ｒｈ、Ｐｄ、Ａｇ、Ｃｄ、Ｉｎ、Ｓｎ、Ｓｂ、Ｂａ、Ｈｆ、Ｔａ、Ｗ、Ｒｅ、Ｏｓ、Ｉｒ、Ｐｔ、Ａｕ、Ｈｇ、ＴＩ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ、Ｔｈ、Ｐａ、Ｕ、Ｎｐ、Ａｍ等の単体、もしく酸化物、塩化物、フッ化物、水酸化物、臭化物などの２種以上の元素からなる。中心金属は、これらの元素に限定されるものではない。） Examples of the metal phthalocyanine pigment include metal phthalocyanines represented by the following general formula (7). These charge generation materials can be used alone or as a mixture of two or more.

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

The metal phthalocyanine-based charge generation material in the present invention may have a basic skeleton as represented by the general formula (7) as an example, and has a multimeric structure such as a dimer and a trimer. It may have a higher order polymer structure. In addition, the basic skeleton may have various substituents. Of these various metal phthalocyanines, titanyl phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, etc. having TiO as the central metal are particularly preferred in terms of photoreceptor characteristics. In addition, these metal phthalocyanines are known to have various crystal systems. For example, in the case of titanyl phthalocyanine, α, β, γ, m, Y type, etc., in the case of copper phthalocyanine, α, β, γ, etc. It has the following polycrystal system. Even in a metal phthalocyanine having the same central metal, various properties change as the crystal system changes. It has been reported that the characteristics of a photoreceptor using these metal phthalocyanine pigments having various crystal systems also change accordingly (Electrophotographic Society Vol. 29, No. 4 (1990)). For this reason, the selection of the crystal system of metal phthalocyanine is very important in terms of photoreceptor characteristics.
Among these metal phthalocyanine pigments, titanyl phthalocyanine pigments are effectively used, and in particular, at least 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (1.542 °) of CuKα. The titanyl phthalocyanine crystal having the maximum diffraction peak has a particularly high sensitivity, and can be used particularly effectively in the present invention because the speed of image formation can be increased. Further, among them, it has a maximum diffraction peak at 27.2 °, and further has main peaks at 9.4 °, 9.6 °, and 24.0 °, and is 7.3 as the lowest diffraction peak. A titanyl phthalocyanine crystal having a peak at ゜, no peak between the 7.3 ° peak and the 9.4 ° peak, and no peak at 26.3 ° has a charge generation efficiency. It can be used very effectively as a charge generation material of the present invention, such as being large, having good electrostatic properties, and being less likely to cause soiling. These charge generation materials can be used alone or as a mixture of two or more.

  In the charge generation material, it is effective that the effect may be enhanced by making the particle size finer. In particular, in the phthalocyanine pigment, the average particle size is preferably 0.25 μm or less, and more preferably 0.2 μm or less. The manufacturing method is shown below. A method for controlling the particle size of the charge generating material contained in the photosensitive layer is a method of removing coarse particles larger than 0.25 μm after dispersing the charge generating material. The average particle size referred to here is a volume average particle size, and is determined by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba, Ltd.). At this time, the particle diameter (Median diameter) corresponding to 50% of the cumulative distribution was calculated. 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 charge generation material powder or dispersion directly with an electron microscope and determine the size. It is.

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

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

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

  The charge generation material has an extremely strong intermolecular hydrogen bonding force, which is a characteristic of charge generation materials exhibiting highly sensitive characteristics. For this reason, the interaction between the dispersed pigment particles is very strong. As a result, there is a great possibility that the charge generation material particles dispersed by a disperser etc. are re-aggregated by dilution or the like. Such agglomerates can be removed. At this time, since the dispersion is in a thixotropic state, particles having a size smaller than the effective pore size of the filter to be used are removed. Or the liquid which shows structural viscosity can also be changed into the state close | similar to Newton property by a filter process. Thus, the effect of the present invention can be further improved by removing the coarse particles of the charge generation material.

式中、Ｃｐ₁，Ｃｐ₂はカップラー残基を表す。Ｒ₂₀₁，Ｒ₂₀₂はそれぞれ、水素原子、ハロゲン原子、アルキル基、アルコキシ基、シアノ基のいずれかを表し、同一でも異なっていても良い。またＣｐ₁，Ｃｐ₂は下記式（１２）で表され、

式中、Ｒ₂₀₃は、水素原子、メチル基、エチル基などのアルキル基、フェニル基などのアリール基を表す。Ｒ₂₀₄，Ｒ₂₀₅，Ｒ₂₀₆，Ｒ₂₀₇，Ｒ₂₀₈はそれぞれ、水素原子、ニトロ基、シアノ基、フッ素、塩素、臭素、ヨウ素などのハロゲン原子、トリフルオロメチル基等のハロゲン化アルキル基、メチル基、エチル基などのアルキル基、メトキシ基、エトキシ基などのアルコキシ基、ジアルキルアミノ基、水酸基を表し、Ｚは置換もしくは無置換の芳香族炭素環または置換もしくは無置換の芳香族複素環を構成するのに必要な原子群を表す。 Among the azo pigments, azo pigments represented by the following formula (11) are effectively used. In particular, an asymmetric azo pigment in which Cp ₁ and Cp ₂ of the azo pigment are different from each other has high carrier generation efficiency and can be effectively used as the charge generation material of the present invention.

In the formula, Cp ₁ and Cp ₂ represent coupler residues. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, and may be the same or different. Cp ₁ and Cp ₂ are represented by the following formula (12):

In the formula, R ₂₀₃ represents a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group. R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ and R ₂₀₈ are each a hydrogen atom, a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine or iodine, a halogenated alkyl group such as a trifluoromethyl group, or methyl. Represents an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, a dialkylamino group or a hydroxyl group, and Z constitutes a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring Represents the atomic group necessary to

  As a binder resin used as necessary for the charge generation layer, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, Examples include polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, and polyvinyl pyrrolidone. These binder resins can be used alone or as a mixture of two or more. The amount of the binder resin is preferably 0 to 500 parts by weight, more preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generation material. The binder resin may be added before or after dispersion.

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

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

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

<About the charge transport layer>
The charge transport layer is a layer having a charge transport function, and is a layer mainly composed of a charge transport material and a binder resin. In the present invention, the first charge transport layer and the second charge transport layer laminated on the charge generation layer are referred to as a charge transport layer.
Further, the first charge transport layer coating solution contains a charge transport material having a triarylamine structure and an arylamine compound having at least one substituted or unsubstituted alkylamino group, and the second charge transport layer coating solution The liquid contains a charge transport material having a triarylamine structure and the same arylamine compound as the compound contained in the first charge transport layer, and at least at least the solid content weight of the first charge transport layer coating liquid When the weight ratio of the arylamine compound having one alkylamino group is C1, and the weight ratio of the arylamine compound having at least one alkylamino group to the solid content weight of the second charge transport layer coating solution is C2. The following equation (1) holds: 0 ≦ C2 <C1 (1)
More preferably, 0.005 <C1 <0.15 (2)
It is.
If C1 is too large, even if the relationship of (1) is established, depending on the drying conditions, the number of arylamine compounds having at least one substituted or unsubstituted alkylamino group in the cross-linked charge transport layer increases, and abruptly Bright area potential may increase.

The concentration of C2 is preferably 0.001 <C2 <0.1, and more preferably 0.01 <C2 <0.05.
Subsequently, a method for measuring the concentration of an arylamine compound having at least one substituted or unsubstituted alkylamino group in the charge transport layer (hereinafter referred to as arylamine compound) will be described.
In the charge transport layer, the arylamine compound concentration distribution can be measured by staining the arylamine compound and observing it using an electron microscope, performing surface analysis using ESCA, and measuring the surface of the photoreceptor in a small amount. Examples of the method include a method of quantitatively analyzing by shaving and scraping, and a method of quantitatively determining from the peak intensity ratio of the arylamine compound and the binder resin using the FT-IR ATR method.
Hereinafter, a method using the ATR method will be described. First, the protective layer and the charge transport layer of the photoreceptor can be cut obliquely, and the cut surfaces can be analyzed at regular intervals by the μ-ATR method. From the ratio of the peak intensity of the charge transport material, the peak intensity of the arylamine compound and the peak intensity of the binder resin in the obtained IR spectrum, the concentration of the arylamine compound can be quantified, and the concentration distribution of the arylamine compound is obtained. . In addition, the first charge transport layer and the second charge transport layer are prepared on the support, and after drying, the film is peeled off, and the front or back surface thereof can be analyzed by the ATR method. Thereby, the density | concentration of the arylamine compound in an interface can be quantified. In addition, the penetration depth of infrared rays at the time of analysis is about 1 μm when Si crystal is used. In the present invention, the concentration ratio of the arylamine compound at the interface is used as a value measured when the infrared penetration depth is about 1 μm, although other crystals can be used for the analysis.
The concentrations C1 and C2 of the arylamine compound in the first and second charge transport layers measured by this method were equivalent to the concentration of the arylamine compound in the first and second charge transport layer coating solutions. .

  The first charge transport layer and the second charge transport layer coating solution of the present invention contain a charge transport material having a triarylamine structure and an arylamine compound having at least one substituted or unsubstituted alkylamino group. However, it may contain an electron transport material and a hole transport material as necessary. Examples of each are shown below. The charge transport material means an electron transport material and a hole transport material.

Examples of the electron transporting substance include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4, 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide, diphenoquinone derivatives and naphthalenetetracarboxylic acid diimide derivatives. These electron transport materials can be used alone or as a mixture of two or more.
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, stilbene derivatives, α-phenylstilbene derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives And other known materials such as indene derivatives, butadiene derivatives, pyrene derivatives, distyryl derivatives, enamine derivatives, and the like. These hole transport materials may be used alone or in combination of two or more.

Among the charge transport materials having a triarylamine structure contained in the charge transport layer, a distyryl compound is effectively used in the present invention. A distyryl compound refers to a material having two styryl groups. These materials have large π conjugation and high mobility, so that charge transfer is likely to occur. As a result, it is considered that there is an effect of suppressing an increase in the bright portion potential as compared with a charge transport material having an equivalent ionization potential.
Further, among the distyryl compounds, the distyrylbenzene derivative represented by the general formula (3) is particularly preferable. The distyrylbenzene derivative represented by the general formula (3) has a plurality of triarylamine structures having a high charge transport function and a large π conjugation via the aromatic ring group at the center of the structural formula. Further, since the molecular skeleton is large and the triarylamine structures are separated from each other, charge transfer is likely to occur between molecules.
The distyrylbenzene derivative used in the present invention can be synthesized by a known method such as Japanese Patent No. 2552695.
The same charge transport material having a triarylamine structure contained in the first charge transport layer and the second charge transport layer is preferable. In the case of different structures, side effects such as an increase in bright part potential may occur depending on the difference in ionization potential between the two.

An example of the distyryl compound is given below. However, the present invention is not limited to these compounds.

Below, an example of the distyrylbenzene derivative represented by General formula (3) effective in this invention is given. However, the present invention is not limited to these compounds.

Among the above-mentioned distyrylbenzene derivatives, those in which at least one of R ₃ , R ₈ , R _19, and R _{24 in} the general formula (3) is a methyl group are particularly effective for reducing the bright part potential.

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, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, Examples thereof include thermoplastic or thermosetting resins such as phenol resins and alkyd resins.
The amount of the charge transport material having a triarylamine structure is preferably 20 to 300 parts by weight, more preferably 40 to 150 parts by weight, based on 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. These may be used alone or in combination of two or more.

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

It is desirable that the thickness of the charge transport layer has the following relationship, where T1 is the thickness of the first charge transport layer and T2 is the thickness of the second charge transport layer.
T1> T2 × 2
When T2 exceeds this range, the amount of arylamine compound having at least one substituted or unsubstituted alkylamino group in the entire charge transport layer is decreased, which may be disadvantageous for image density fluctuation after exposure to NOx gas.
T1 + T2 is preferably 30 μm or less, more preferably 25 μm or less from the viewpoint of resolution and responsiveness. Regarding the lower limit, although it differs depending on the system to be used (particularly the charging potential), it is preferably 5 μm or more.

The arylamine compound having at least one substituted or unsubstituted alkylamino group used in the present invention will be described. The arylamine compound having at least one substituted or unsubstituted alkylamino group used in the present invention is preferably the above general formula (4-1), the above general formula (5-1), or the above general formula (5-2). And (6). Each will be described below.
The compound represented by the general formula (4-1), the compound represented by the general formula (5-1), the compound represented by the general formula (5-2), the above general formula ( Use of the compound represented by 6) is effective in stabilizing the image quality when the photoreceptor is used repeatedly. The reason for this is not clarified at the present time, but the alkylamino group contained in the chemical structure is a strongly basic group. A neutralizing effect on the substance is assumed. In addition, it is known that the aromatic hydrocarbon ring group-substituted amino group is a functional group having excellent charge transporting ability [Takahashi et al., Electrophotographic Society, Vol. 25, No. 3, page 16, 1986], Since the diamine compound used for this invention contains this group, it turns out that it is a compound with high charge transport ability. Furthermore, it has also been found that high sensitivity, repeat stability, and the like are further increased when used in combination with other charge transport materials.

（式中、Ｒ_９２、Ｒ_９３は芳香環基置換もしくは無置換の炭素数１〜４のアルキル基を表わし、同一でも異なっていてもよい。また、Ｒ_９２、Ｒ_９３は互いに結合し窒素原子を含む複素環を形成してもよい。ｊ、ｋは０〜３の整数を表わす。ただしｊとｋが同時に０となることはない。Ｒ_９４、Ｒ_９５は水素原子、置換もしくは無置換の炭素数１〜１１のアルキル基、置換もしくは無置換の芳香環基を表わし、それぞれ同一でも異なっていてもよい。また、Ａｒ_５１、Ａｒ_５２は置換もしくは無置換の２価の芳香環基を表わし、それぞれ同一でも異なっていてもよい。） Examples of the compound represented by the following general formula (4-1) include compounds represented by the following general formulas (4-2) to (4-4).

(In the formula, R ₉₂ and R ₉₃ represent an aromatic ring group-substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, which may be the same or different. R ₉₂ and R ₉₃ are bonded to each other to form a nitrogen atom. And j and k each represent an integer of 0 to 3. However, j and k are not simultaneously 0. R ₉₄ and R ₉₅ are hydrogen atoms, substituted or unsubstituted. Represents an alkyl group having 1 to 11 carbon atoms and a substituted or unsubstituted aromatic ring group, which may be the same or different, and Ar ₅₁ and Ar ₅₂ represent a substituted or unsubstituted divalent aromatic ring group. Each may be the same or different.)

（式中、Ｒ_９２、Ｒ_９３は芳香環基置換もしくは無置換の炭素数１〜４のアルキル基を表わし、同一でも異なっていてもよい。また、Ｒ_９２、Ｒ_９３は互いに結合し窒素原子を含む複素環を形成してもよい。ｊ、ｋは０〜３の整数を表わす。ただしｊとｋが同時に０となることはない。Ｒ_９４は水素原子、置換もしくは無置換の炭素数１〜１１のアルキル基、置換もしくは無置換の芳香環基を表わす。
また、Ａｒ₅₁、Ａｒ₅₂、及びＡｒ₅₃は置換もしくは無置換の２価の芳香環基を表し、同一であっても異なっていてもよく、Ａｒ₅₄及びＡｒ₅₅は置換もしくは無置換の芳香環基を表わし、同一でも異なっていてもよい。また、Ａｒ₅₄、Ａｒ₅₃、もしくはＡｒ_５４、Ａｒ_５３は共同で窒素原子を含む複素環基を形成してもよい。）

(In the formula, R ₉₂ and R ₉₃ represent an aromatic ring group-substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, which may be the same or different. R ₉₂ and R ₉₃ are bonded to each other to form a nitrogen atom. And j and k each represent an integer of 0 to 3. However, j and k are not simultaneously 0. R ₉₄ is a hydrogen atom, substituted or unsubstituted carbon number 1 Represents an alkyl group of 11 or a substituted or unsubstituted aromatic ring group;
Ar ₅₁ , Ar ₅₂ , and Ar ₅₃ represent a substituted or unsubstituted divalent aromatic ring group, which may be the same or different, and Ar ₅₄ and Ar ₅₅ represent a substituted or unsubstituted aromatic ring. Represents a group, which may be the same or different. Ar ₅₄ and Ar ₅₃ , or Ar ₅₄ and Ar ₅₃ may form a heterocyclic group containing a nitrogen atom together. )

（式中、Ｒ_９２、Ｒ_９３は芳香環基置換もしくは無置換の炭素数１〜４のアルキル基を表わし、同一でも異なっていてもよい。また、Ｒ_９２、Ｒ_９３は互いに結合し窒素原子を含む複素環を形成してもよい。ｊ、ｋは０〜３の整数を表わす。ただしｊとｋが同時に０となることはない。Ｒ_９４は水素原子、置換もしくは無置換の炭素数１〜１１のアルキル基、置換もしくは無置換の芳香環基を表わす。
また、Ａｒ₅₁、Ａｒ₅₂、及びＡｒ₅₃は置換もしくは無置換の２価の芳香環基を表し、同一であっても異なっていてもよく、Ａｒ₅₄及びＡｒ₅₅は置換もしくは無置換の芳香環基を表わし、同一でも異なっていてもよい。また、Ａｒ₅₄、Ａｒ₅₃、もしくはＡｒ_５４、Ａｒ_５３は共同で窒素原子を含む複素環基を形成してもよい。）

(In the formula, R ₉₂ and R ₉₃ represent an aromatic ring group-substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, which may be the same or different. R ₉₂ and R ₉₃ are bonded to each other to form a nitrogen atom. And j and k each represent an integer of 0 to 3. However, j and k are not simultaneously 0. R ₉₄ is a hydrogen atom, substituted or unsubstituted carbon number 1 Represents an alkyl group of 11 or a substituted or unsubstituted aromatic ring group;
Ar ₅₁ , Ar ₅₂ , and Ar ₅₃ represent a substituted or unsubstituted divalent aromatic ring group, which may be the same or different, and Ar ₅₄ and Ar ₅₅ represent a substituted or unsubstituted aromatic ring. Represents a group, which may be the same or different. Ar ₅₄ and Ar ₅₃ , or Ar ₅₄ and Ar ₅₃ may form a heterocyclic group containing a nitrogen atom together. )

（式中、Ｒ_９２、Ｒ_９３は芳香環基置換もしくは無置換の炭素数１〜４のアルキル基を表わし、同一でも異なっていてもよい。また、Ｒ_９２、Ｒ_９３は互いに結合し窒素原子を含む複素環を形成してもよい。ｊは１〜３の整数を表わす。Ｒ_９４は水素原子、置換もしくは無置換の炭素数１〜１１のアルキル基、置換もしくは無置換の芳香環基を表わす。
また、Ａｒ₅₁、及びＡｒ₅₃は置換もしくは無置換の２価の芳香環基を表し、同一であっても異なっていてもよく、Ａｒ₅₄及びＡｒ₅₅は置換もしくは無置換の芳香環基を表わし、同一でも異なっていてもよい。また、Ａｒ₅₄、Ａｒ₅₃、もしくはＡｒ_５４、Ａｒ_５３は共同で窒素原子を含む複素環基を形成してもよい。）

(In the formula, R ₉₂ and R ₉₃ represent an aromatic ring group-substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, which may be the same or different. R ₉₂ and R ₉₃ are bonded to each other to form a nitrogen atom. And j represents an integer of 1 to 3. R ₉₄ represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 11 carbon atoms, or a substituted or unsubstituted aromatic ring group. Represent.
Ar ₅₁ and Ar ₅₃ represent a substituted or unsubstituted divalent aromatic ring group, which may be the same or different, and Ar ₅₄ and Ar ₅₅ represent a substituted or unsubstituted aromatic ring group. May be the same or different. Ar ₅₄ and Ar ₅₃ , or Ar ₅₄ and Ar ₅₃ may form a heterocyclic group containing a nitrogen atom together. )

In the general formulas (4-1) to (4-4), the aromatic ring group-substituted alkyl group represented by R ₉₂ and R ₉₃ is an alkyl group having 1 to 4 carbon atoms substituted with an aromatic ring group, Specific examples of the aromatic group-substituted or unsubstituted alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a benzyl group.
The aromatic ring groups of R ₉₂ , R ₉₃ and Ar _{51 to} Ar ₅₅ are aromatic hydrocarbon groups obtained from aromatic hydrocarbon rings such as benzene, biphenyl, naphthalene, anthracene, and pyrene, and pyridine, quinoline, thiophene. And aromatic heterocyclic groups obtained from aromatic heterocyclic rings such as furan, oxazole, oxadiazole and carbazole.
These substituents include those exemplified in the above specific examples of alkyl groups, alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group, or halogen atoms of fluorine atom, chlorine atom, bromine atom and iodine atom. An atom, an aromatic ring group, etc. are mentioned. Furthermore, specific examples of the heterocyclic group in which R ₉₂ and R ₉₃ are bonded to each other and contain a nitrogen atom include a pyrrolidinyl group, a piperidinyl group, and a pyrrolinyl group. In addition, examples of the heterocyclic group jointly containing a nitrogen atom include aromatic heterocyclic groups such as N-methylcarbazole, N-ethylcarbazole, N-phenylcarbazole, indole, and quinoline.

Specific examples of structures of the compounds represented by the general formulas (4-1) to (4-4) are shown below. However, the present invention is not limited to these compounds.

（式中、Ｒ₉₆、Ｒ₉₇は、置換もしくは無置換の芳香族炭化水素基、置換もしくは無置換のアルキル基を表わし、同一でも異なっていてもよい。ただし、Ｒ₉₆、Ｒ₉₇のうち少なくとも１つは置換もしくは無置換のアルキル基である。また、Ｒ₉₆、Ｒ₉₇は互いに結合し窒素原子を含む複素環基を形成してもよい。Ａｒ₅₃、Ａｒ₅₄は置換もしくは無置換の芳香環基を表わす。ｐ、ｑはそれぞれ０〜３の整数を表わす。ただし、ｐ、ｑが同時に０となることはない。ｒは１〜３の整数を表わす。） The compounds represented by general formula (5-1) and the following general formula (5-2) will be described.

(In the formula, R ₉₆ and R ₉₇ represent a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted alkyl group, and may be the same or different, provided that at least one of R ₉₆ and R ₉₇ One is a substituted or unsubstituted alkyl group, and R ₉₆ and R ₉₇ may be bonded to each other to form a heterocyclic group containing a nitrogen atom, Ar ₅₃ and Ar ₅₄ are substituted or unsubstituted aromatic groups. (P and q each represent an integer of 0 to 3. However, p and q are not simultaneously 0. r represents an integer of 1 to 3)

（式中、Ｒ₉₈、Ｒ₉₉は、置換もしくは無置換の芳香族炭化水素基、置換もしくは無置換のアルキル基を表わし、同一でも異なっていてもよい。ただし、Ｒ₉₆、Ｒ₉₇のうち少なくとも１つは置換もしくは無置換のアルキル基である。また、Ｒ₉₈、Ｒ₉₉は互いに結合し窒素原子を含む複素環基を形成してもよい。Ａｒ₅₅、Ａｒ₅₆は置換もしくは無置換の芳香環基を表わす。ｓ、ｔはそれぞれ０〜３の整数を表わす。ただし、ｓ、ｔが同時に０となることはない。ｕは１〜３の整数を表わす。）

(In the formula, R ₉₈ and R _{99 each} represents a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted alkyl group, and may be the same or different, provided that at least one of R ₉₆ and R ₉₇ One is a substituted or unsubstituted alkyl group, and R ₉₈ and R ₉₉ may be bonded to each other to form a heterocyclic group containing a nitrogen atom, and Ar ₅₅ and Ar ₅₆ are substituted or unsubstituted aromatic groups. S and t each represent an integer of 0 to 3. However, s and t are not simultaneously 0. u represents an integer of 1 to 3.)

In these general formulas (5-1) and (5-2), examples of the aromatic hydrocarbon group represented by R _{96 to} R ₉₉ include aromatic hydrocarbons such as benzene, naphthalene, anthracene, and pyrene. Examples of the substituted or unsubstituted alkyl group represented by R _{96 to} R ₉₉ include methyl, ethyl, propyl, butyl, hexyl, undecyl, and benzyl. Examples include groups. Examples of the aromatic ring group represented by Ar _{53 to} Ar ₅₆ include divalent aromatic hydrocarbon groups of aromatic hydrocarbon rings such as benzene, naphthalene, anthracene, and pyrene, and pyridine, quinoline, thiophene, furan, Examples thereof include divalent aromatic heterocyclic groups such as oxazole, oxadiazole, and carbazole. These substituents include those exemplified in the above specific examples of alkyl groups, alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group, or halogen atoms of fluorine atom, chlorine atom, bromine atom and iodine atom. An atom, an aromatic ring group, etc. are mentioned.

Preferred examples of the compound represented by the general formula (5-1) or (5-2) are given below. However, the present invention is not limited to these compounds.
The compounds represented by the general formulas (5-1) and (5-2) include compounds described in Japanese Patent Publication No. 58-5739, Japanese Patent No. 2529299, and the like. The compound represented by (5-1) can be produced by a so-called modified Wittig reaction or Wittig reaction by reacting a corresponding phosphonate compound or triphenylphosphonium salt compound with a corresponding aldehyde compound. Furthermore, the compound represented by the general formula (5-2) can be produced by reducing the compound represented by the general formula (5-1).

（式中、Ｒ₁₀₁、Ｒ₁₀₂は、置換もしくは無置換のアルキル基、置換もしくは無置換の芳香環基を表わし、同一でも異なっていてもよい。但し、Ｒ₁₀₁、Ｒ₁₀₂のいずれか１つは置換もしくは無置換のアルキル基である。また、Ｒ₁₀₁、Ｒ₁₀₂は互いに結合し、窒素原子を含む置換もしくは無置換の複素環基を形成してもよい。Ａｒ₅₇は置換もしくは無置換の芳香環基を表わす。）
上記一般式（６）で表わされるジアミン化合物は、特公昭６２−１３３８２号公報、米国特許第４２２３１４４号、第３２７１３８３号、第３２９１７８８号で染料中間体もしくは高分子化合物の前駆体として記載されている。 The arylamine compound having at least one alkylamino group used for the charge transport layer is represented by the following general formula (6).

(In the formula, R ₁₀₁ and R ₁₀₂ represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic ring group, and may be the same or different. However, any one of R ₁₀₁ and R ₁₀₂ may be used. is a substituted or unsubstituted alkyl group. Further, R _101, R ₁₀₂ is bonded to each other, may .Ar ₅₇ also form a substituted or unsubstituted heterocyclic group containing a nitrogen atom of a substituted or unsubstituted Represents an aromatic ring group.)
The diamine compound represented by the general formula (6) is described as a dye intermediate or a polymer compound precursor in JP-B-62-13382, US Pat. Nos. 4,223,144, 3,271,383, and 3,291,788. .

（式中、Ｒ₁₀₁、Ｒ₁₀₂は、置換もしくは無置換のアルキル基、置換もしくは無置換の芳香環基を表わし、同一でも異なっていてもよい。ただし、Ｒ₁₀₁、Ｒ₁₀₂のうち、少なくとも１つは置換もしくは無置換のアルキル基である。 The diamine compound represented by the general formula (6) can be easily produced by the method described in the literature (E. Elceand AS Hay, Polymer, Vol. 37 No. 9, 1745 (1996)). That is, by reacting a dihalide represented by the following general formula (8) and a secondary amine compound represented by the following general formula (9) at a temperature from room temperature to about 100 ° C. in the presence of a basic compound. Obtainable.
_{BH 2 C-Ar 57 CH 2} B (8)
(In the formula, Ar ₅₇ represents a substituted or unsubstituted aromatic ring group; B represents a halogen atom.)

(In the formula, R ₁₀₁ and R ₁₀₂ represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic ring group, and may be the same or different. However, at least one of R ₁₀₁ and R ₁₀₂ may be used. One is a substituted or unsubstituted alkyl group.

  Specific examples of the basic compound include potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, sodium hydride, sodium methylate, potassium t-butoxide and the like. Examples of the reaction solvent include dioxane, tetrahydrofuran, toluene, xylene, dimethyl sulfoxide, N, N-dimethylformamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile and the like.

Specific examples of the substituted or unsubstituted alkyl group represented by R ₁₀₁ and R ₁₀₂ in the description of the general formulas (6) and (9) include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. Group, undecanyl group, benzyl group and the like. The aromatic ring groups represented by R ₁₀₁ , R ₁₀₂ and Ar ₅₇ in the description of the general formulas (6) and (9) include aromatics such as benzene, biphenyl, naphthalene, anthracene, fluorene and pyrene. Examples include rings and aromatic heterocyclic groups such as pyridine, quinoline, thiophene, furan, oxazole, oxadiazole, and carbazole. These substituents include those exemplified in the above specific examples of alkyl groups, alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group, or halogen atoms of fluorine atom, chlorine atom, bromine atom and iodine atom. Atoms, the aromatic hydrocarbon groups, and heterocyclic groups such as pyrrolidine, piperidine, piperazine and the like can be mentioned.

Below, the preferable example of a compound represented by the said General formula (6) is given. However, the present invention is not limited to these compounds.

注）化合物Ｎｏ．３５〜３７において、Ｒ₁₀₁、Ｒ₁₀₂の欄に示した基は
−ＮＲ₁₀₁Ｒ₁₀₂基である。

Note) Compound No. 35 to 37, the groups shown in the columns of R ₁₀₁ and R ₁₀₂ are
-NR ₁₀₁ R ₁₀₂ group.

<About other additives>
In the present invention, in order to improve environmental resistance, in particular, for the purpose of improving the stability of image quality, each layer such as a cross-linked charge transport layer, a charge generation layer, a charge transport layer, an undercoat layer, an intermediate layer, etc. An antioxidant can be added to the. In the present invention, it was effective to add it to the charge transport layer.

The following are mentioned as antioxidant which can be used for this invention.
<Phenolic compound>
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-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- [meth -3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) buty Rick acid] glycol ester, tocopherols and the like.

<Paraphenylenediamines>
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-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 preferably 0.01 to 10 parts by weight with respect to the total weight of the layer to be added.

  Among the antioxidants used in the present invention, hindered phenol derivatives and hindered amine derivatives are effective, and particularly compounds having a hindered phenol structure and a hindered amine structure in the same molecule are effective.

<< Crosslinked charge transport layer >>
Next, the constituent material of the crosslinkable charge transport layer of the present invention will be described.
Since it is necessary to transport charges while maintaining wear resistance, the crosslinked charge transport layer is used by curing a radical polymerizable monomer having no charge transport function and a radical polymerizable compound having a charge transport function. . Curing is generally an intermolecular reaction of a low-molecular compound having a plurality of functional groups or a high-molecular compound is bonded (for example, covalent bond) between molecules by applying energy such as heat, light, electron beam, etc. This reaction forms an original network structure.

Examples of the curable resin include a thermosetting resin that is polymerized by heat, a photocurable resin that is polymerized by light such as ultraviolet rays and visible light, an electron beam curable resin that is polymerized by electronic properties, and a curing agent as necessary. Or a catalyst, a polymerization initiator, or the like.
In order to cure the curable resin, it is necessary that a reactive compound (for example, a monomer or an oligomer) has a functional group that causes a polymerization reaction. Examples of these functional groups include acryloyl groups and / or methacryloyl groups. Further, in the curing reaction, the larger the number of functional groups in one molecule of the reactive monomer, the stronger the three-dimensional network structure becomes, and the trifunctional or higher functionality is particularly effective. As a result, the curing density is increased, the hardness is high, the elasticity is high, the uniformity is smooth, and the smoothness is improved. This is effective for improving the durability and image quality of the photoreceptor.

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

  The radical polymerizable monomer having no charge transporting property is, for example, a hole transporting structure such as triarylamine, hydrazone, pyrazoline, and carbazole, for example, an electron withdrawing property having a condensed polycyclic quinone, diphenoquinone, a cyano group, or a nitro group. A monomer having no electron transport structure such as an aromatic ring and having a radical polymerizable functional group. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and is capable of radical polymerization. Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.

(1) 1-Substituted Ethylene Functional Group 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. , -CONR ₇₈ group (R ₇₈ represents an alkyl group such as hydrogen, methyl group or ethyl group, an aralkyl group such as benzyl group, naphthylmethyl group or phenethyl group, or an aryl group such as phenyl group or naphthyl group). Or -S- group.)
Specific examples of these substituents include vinyl group, styryl group, 2-methyl-1,3-butadienyl group, vinylcarbonyl group, acryloyloxy group, acryloylamide group, vinylthioether group and the like.

(2) 1,1-substituted ethylene functional group Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = CY-X ₂ −... (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 ₇₉ group (R ₇₉ is a hydrogen atom, an alkyl such as an optionally substituted methyl group or ethyl group) Group, an aralkyl group such as benzyl and phenethyl group which may have a substituent, an aryl group such as a phenyl group and a naphthyl group which may have a substituent, or -CONR ₈₀ R ₈₁ (R ₈₀ and R ₈₁ is a hydrogen atom, an alkyl group such as an optionally substituted methyl group, an ethyl group, an aralkyl group such as an optionally substituted benzyl group, naphthylmethyl group, or phenethyl group, or Place A phenyl group which may have a group, an aryl group such as phenyl or naphthyl, which may be the same or different from each other.) Further, X ₂ is X ₁ identical substituents and a single bond and the formula 10 Represents an alkylene group, provided that at least one of Y and X ₂ is an oxycarbonyl group, a cyano group, an alkenylene group, or an aromatic ring.)
Specific examples of these substituents include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.

In addition, examples of the substituent further substituted with the substituent for X ₁ , X ₂ , and Y include, for example, a halogen atom, a nitro group, a cyano group, a methyl group, an alkyl group such as an ethyl group, a methoxy group, an ethoxy group, and the like And an aryloxy group such as a phenyl group and a naphthyl group, an aralkyl group such as a benzyl group and a phenethyl group, and the like.

  Among these radical polymerizable functional groups, acryloyloxy group and methacryloyloxy group are particularly useful. The number of functional groups of the radically polymerizable monomer or oligomer having no charge transporting structure is preferably polyfunctional and more preferably trifunctional or higher. When trifunctional or higher-functional radically polymerizable monomers are cured, a three-dimensional network structure is developed, and a high hardness and high elasticity layer having a very high crosslink density is obtained. And scratch resistance are achieved. However, depending on the curing conditions and the materials used, a large number of bonds are instantaneously formed in the curing reaction, so that internal stress due to volume shrinkage occurs, and cracks and film peeling may easily occur. In that case, it may be improved by using a monofunctional or bifunctional radically polymerizable monomer or by mixing them.

Hereinafter, a radical polymerizable monomer having no trifunctional or higher functional charge transport structure effective for improving the wear resistance will be described.
A compound having three or more acryloyloxy groups is obtained by, for example, using a compound having three or more hydroxyl groups in the molecule, acrylic acid (salt), acrylic acid halide, or acrylic ester, and performing an ester reaction or a transesterification reaction. Obtainable. 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 radical polymerizable monomer having no charge transport structure include the following, but are not limited to these compounds.
That is, as the radical polymerizable monomer used in the present invention, trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, HPA-modified trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, PO-modified trimethylol. Propane triacrylate, caprolactone modified trimethylolpropane triacrylate, ECH modified trimethylolpropane triacrylate, HPA modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, ECH modified glycerol triacrylate , EO-modified glycerol triacrean , PO-modified glycerol triacrylate, tris (acryloxyethyl) isocyanurate, alkyl-modified dipentaerythritol tetraacrylate, alkyl-modified dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, EO-modified phosphorus Acid triacrylate, 2, 2, 5, 5, -tetrahydroxymethylcyclopentanone tetraacrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl carbitol acrylate , 3-methoxybutyl acrylate, benzyl acrylate, cyclohexyl acrylate , Isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, styrene monomer, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, EO-modified bisphenol A diacrylate, EO-modified bisphenol F diacrylate And neopentyl glycol diacrylate. Among them, trimethylol propylene Triacrylate (TMPTA), HPA-modified trimethylolpropane triacrylate, EO-modified trimethylolpropane triacrylate, PO-modified trimethylolpropane triacrylate, and ECH-modified trimethylolpropane triacrylate, but the present invention is not limited thereto. Is not to be done. In addition, ethyleneoxy modification is described as EO modification, propyleneoxy modification as PO modification, epichlorohydrin modification as ECH modification, and alkylene modification as HPA modification.
Examples of the radical polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers.
These may be used alone or in combination of two or more.

  The trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the present invention has a molecular weight relative to the number of functional groups in the monomer in order to form a dense crosslink in the crosslinkable charge transport layer. The ratio (molecular weight / functional group number) is preferably 250 or less. Further, when this ratio is larger than 250, the cross-linked charge transport layer is soft and wear resistance is somewhat lowered. Therefore, among monomers exemplified above, monomers having a modifying group such as EO, PO, caprolactone, etc. 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.

<Description of radical polymerizable compound having charge transporting structure>
Examples of the radically polymerizable compound having a charge transporting structure used in the present invention include hole transporting structures such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano group and nitro group. It refers to a compound having an electron transport structure such as an electron-withdrawing aromatic ring and having a radical polymerizable functional group. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and can be radically polymerized.

Any number of functional groups can be used as the radical polymerizable compound having a charge transport structure used in the cross-linked charge transport layer of the present invention. From the point of view, it is more preferable. In the case of bifunctional, the crosslink structure is fixed by a plurality of bonds and the crosslink density is further increased. However, since the charge transporting structure is very bulky, the distortion of the cured layer structure is increased and the internal stress of the layer may be increased is there. In addition, the intermediate structure (cation radical) at the time of charge transport cannot be kept stable, and there is a risk that a decrease in sensitivity due to charge trapping and an increase in residual potential are likely to occur. This tendency is particularly remarkable for those having three or more functional groups.
As the charge transporting structure of the radical polymerizable compound having a charge transporting structure, any material can be used as long as it can provide a charge transporting function. Among them, the triarylamine structure is highly effective and useful. is there. This is considered to be because there are many hopping sites and π conjugation spreads. Triarylamines are easily conjugated to each other in the radical cation state. For these reasons, the triarylamine structure is excellent in the charge transport function. In particular, when the compound represented by the formula (1) or (2) is used, electrical characteristics such as sensitivity and residual potential are favorably sustained.

〔式中、Ｒ₄₀は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基、置換基を有してもよいアリール基、シアノ基、ニトロ基、アルコキシ基、−ＣＯＯＲ₄₁（Ｒ₄₁は水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を表わす。）、ハロゲン化カルボニル基若しくはＣＯＮＲ₄₂Ｒ₄₃（Ｒ₄₂及びＲ₄₃は水素原子、ハロゲン原子、置換基を有してもよいアルキル基、置換基を有してもよいアラルキル基又は置換基を有してもよいアリール基を示し、互いに同一であっても異なっていてもよい。）を表わし、Ａｒ₂、Ａｒ₃は置換もしくは無置換のアリーレン基を表わし、同一であっても異なってもよい。Ａｒ₄、Ａｒ₅は置換もしくは無置換のアリール基を表わし、同一であっても異なってもよい。Ｘは単結合、置換もしくは無置換のアルキレン基、置換もしくは無置換のシクロアルキレン基、置換もしくは無置換のアルキレンエーテル基、酸素原子、硫黄原子、ビニレン基を表わす。Ｚは置換もしくは無置換のアルキレン基、置換もしくは無置換のアルキレンエーテル基、アルキレンオキシカルボニル基を表わす。ｍ、ｎは０〜３の整数を表わす。〕

[Wherein, R ₄₀ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, A group, an alkoxy group, —COOR ₄₁ (R ₄₁ represents 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. ), A halogenated carbonyl group or CONR ₄₂ R ₄₃ (R ₄₂ and R ₄₃ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or a substituent. Represents an aryl group which may be the same or different, and Ar ₂ and Ar ₃ represent a substituted or unsubstituted arylene group, which may be the same or different. . Ar ₄ and Ar ₅ represent a substituted or unsubstituted aryl group, and may be the same or different. X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group. Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, or an alkyleneoxycarbonyl group. m and n represent an integer of 0 to 3. ]

Specific examples of the substituents in the general formulas (1) and (2) are shown below.
In the general formulas (1) and (2), in the substituent of R ₄₀ , examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. The aralkyl group includes a benzyl group, a phenethyl group, and a naphthylmethyl group, and the alkoxy group includes a methoxy group, an ethoxy group, a propoxy group, and the like. These include a halogen atom, a nitro group, a cyano group, and a methyl group. Substituted with an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group or a naphthyl group, an aralkyl group such as a benzyl group or a phenethyl group, etc. May be.
Of the substituents for R ₄₀ , particularly preferred are a hydrogen atom and a methyl group.

Ar ₄ and Ar ₅ are substituted or unsubstituted aryl groups. In the present invention, the aryl group includes a condensed polycyclic hydrocarbon group, a non-fused cyclic hydrocarbon group, and a heterocyclic group.
The condensed polycyclic hydrocarbon group preferably has 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group. , S-indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group , A chrycenyl group, a naphthacenyl group, and the like. Examples of the non-condensed cyclic hydrocarbon group include monovalent groups of monocyclic hydrocarbon compounds such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether and diphenyl sulfone, or biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne, Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane, and polyphenylalkene, or ring assemblies such as 9,9-diphenylfluorene And monovalent groups of hydrocarbon compounds. Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

In addition, the aryl group represented by Ar ₄ or Ar ₅ may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group and the like.
(2) an alkyl group;
Preferably, it is a C1-C12, particularly C1-C8, more preferably a C1-C4 linear or branched alkyl group, and these alkyl groups further include a fluorine atom, a hydroxyl group, a cyano group, and a C1-C4 alkoxy group. , A phenyl group or a halogen atom, a C1-C4 alkyl group or a C1-C4 alkoxy group substituted with a phenyl group.
Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-ethoxyethyl Group, 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group and the like.

(3) an alkoxy group (—OR ₈₂ );
(In the formula, R ₈₂ represents an alkyl group defined in (2).)
Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group And a trifluoromethoxy group.
(4) aryloxy group;
Examples of the aryl group include a phenyl group and a naphthyl group. This may contain a C1-C4 alkoxy group, a C1-C4 alkyl group or a halogen atom as a substituent. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.
(5) an alkyl mercapto group or an aryl mercapto group;
Specific examples include a methylthio group, an ethylthio group, a phenylthio group, and a p-methylphenylthio group.

（式中、Ｒ_ｄ及びＲ_ｅは各々独立に水素原子、前記（２）で定義したアルキル基、またはアリール基を表わす。アリール基としては、例えばフェニル基、ビフェニル基又はナフチル基が挙げられ、これらはＣ１〜Ｃ４のアルコキシ基、Ｃ１〜Ｃ４のアルキル基またはハロゲン原子を置換基として含有してもよい。Ｒ_ｄ及びＲ_ｅは共同で環を形成してもよい。）
具体的には、アミノ基、ジエチルアミノ基、Ｎ−メチル−Ｎ−フェニルアミノ基、Ｎ、Ｎ−ジフェニルアミノ基、Ｎ、Ｎ−ジ（トリール）アミノ基、ジベンジルアミノ基、ピペリジノ基、モルホリノ基、ピロリジノ基等が挙げられる。 (6) a substituent represented by the following formula;

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

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

Examples of the arylene groups represented by Ar ₂ and Ar ₃ include divalent groups derived from the aryl groups represented by Ar ₄ and Ar ₅ .
X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group.
The substituted or unsubstituted alkylene group is a C1-C12, preferably C1-C8, more preferably a C1-C4 linear or branched alkylene group, and these alkylene groups further include a fluorine atom, a hydroxyl group, It may have a cyano group, a C1-C4 alkoxy group, a phenyl group or a halogen atom, a C1-C4 alkyl group, or a phenyl group substituted with a C1-C4 alkoxy group. Specifically, methylene group, ethylene group, n-butylene group, i-propylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxyethylene. Group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group and the like.

The substituted or unsubstituted cycloalkylene group is a C5-C7 cyclic alkylene group, and these cyclic alkylene groups have a fluorine atom, a hydroxyl group, a C1-C4 alkyl group, and a C1-C4 alkoxy group. May be. Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.
Examples of the substituted or unsubstituted alkylene ether group include alkyleneoxy groups such as ethyleneoxy group and propyleneoxy group, alkylenedioxy groups derived from ethylene glycol, propylene glycol, and the like, diethylene glycol, tetraethylene glycol, tripropylene glycol, and the like. Examples thereof include a derived di- or poly (oxyalkylene) oxy group, and the alkylene group of the alkylene ether group may have a substituent such as a hydroxyl group, a methyl group, or an ethyl group.

〔式中、Ｒ_fは水素、アルキル基（前記（２）で定義されるアルキル基と同じ）、アリール基（前記Ａｒ₄、Ａｒ₅で表わされるアリール基と同じ）、ａは１または２、ｂは１〜３を表わす。〕 Examples of the vinylene group include substituents represented by the following general formula.

[Wherein, R _f is hydrogen, an alkyl group (the same as the alkyl group defined in (2) above), an aryl group (the same as the aryl group represented by Ar ₄ or Ar ₅ above), a is 1 or 2, b represents 1-3. ]

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

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

を表わす。）
上記一般式（１０）で表わされる化合物としては、Ｒ_ｂ、Ｒ_ｃの置換基として、特にメチル基、エチル基である化合物が好ましい。 Further, the radically polymerizable compound having a monofunctional charge transport structure of the present invention is more preferably a compound having a structure represented by the following general formula (10).

(In the formula, o, p and q are each an integer of 0 or 1, R _a represents a hydrogen atom or a methyl group, and R _b and R _c represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms. In the case of plural, s and t each represent 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 (10), compounds having a methyl group or an ethyl group as substituents for R _b and R _c are particularly preferable.

  The radically polymerizable compound having a monofunctional charge transport structure represented by the general formulas (1) and (2), particularly (10) used in the present invention is polymerized by opening a carbon-carbon double bond on both sides. Therefore, it does not become a terminal structure, but is incorporated in a chain polymer and cross-linked by polymerization with a radical polymerizable monomer that does not have a charge transporting structure. And present in a cross-linked chain between the main chain and the main chain (this cross-linked chain includes an intermolecular cross-linked chain between one polymer and another polymer, and a main chain in a folded state in one polymer. There is an intramolecular cross-linked chain in which a site with a chain and another site derived from a polymerized monomer at a position away from this in the main chain are cross-linked). Triarylamines that hang from the chain portion even when present in the bridging chain The structure has at least three aryl groups arranged in a radial direction from the nitrogen atom and is bulky, but is not directly bonded to the chain part but suspended from the chain part via a carbonyl group or the like. Since these triarylamine structures can be arranged adjacent to each other in the polymer, the structural distortion in the molecule is small. In the case of a cross-linked charge transport layer of an electrophotographic photoreceptor, it is presumed that an intramolecular structure relatively free from interruption of the charge transport path can be taken.

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

  In the radical polymerizable compound having a charge transport structure used in the present invention, this component is 20 to 80% by weight, preferably 30 to 70% by weight, based on the total amount of the cross-linked charge transport layer. 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 radically polymerizable monomer having no charge transport structure is lowered, and the crosslinking density is lowered, so that high wear resistance is not exhibited. The required electrical characteristics and wear resistance differ depending on the process to be used, so it cannot be said unconditionally, but considering the balance of both characteristics, the range of 30 to 70% by weight is most preferable.

As described above, a product obtained by curing a tri- or higher functional radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a monofunctional charge transporting structure is particularly effective. It is also possible to use a bifunctional radically polymerizable monomer, a functional monomer and a radically polymerizable oligomer imparted with functionality to a radically polymerizable monomer that does not have a charge transporting structure, and may be very effective depending on the material. is there. 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 radically polymerizable monomer include 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1, Examples include 6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, bisphenol A-EO modified diacrylate, bisphenol F-EO modified diacrylate, neopentyl glycol diacrylate, and the like.

Examples of the functional monomer provided with functionality to a radically polymerizable monomer having no charge transporting structure include octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, and 2-perfluoro. Substituted fluorine atoms such as isononyl ethyl acrylate, siloxane repeating units described in JP-B-5-60503 and JP-B-6-45770: 20-70 acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, Vinyl monomers having polysiloxane groups, such as acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, diacryloyl polydimethylsiloxane diethyl, and acrylate And methacrylate.
Examples of the radical polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers.

<Description of initiator>
The crosslinkable charge transport layer of the present invention comprises a radical polymerizable monomer (preferably trifunctional or higher) having no charge transport structure and a radical polymerizable compound (preferably monofunctional) having a charge transport structure. , A cross-linked charge transport layer that is simultaneously cured using at least one of light and ionizing radiation. When forming a cross-linkable charge transport layer using thermal energy or light energy, In order to advance this crosslinking reaction efficiently, a polymerization initiator may be used in the crosslinked charge transport layer. When performing crosslinking using ionizing radiation, it is usually possible to obtain a crosslinking reaction without using a polymerization initiator, but in order to cure the uncured components remaining after irradiation with ionizing radiation, as a post-treatment Thermal energy and / or light energy can be applied, and even in that case, it is effective to add a polymerization initiator shown below.

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

  As photopolymerization initiators, 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-based photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthones such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone Photopolymerization initiator, bis (cyclopentadienyl) -di-chloro-titanium, bis (cyclopentadienyl) -di-phenyl-titanium, bis (cyclopentadienyl) -bis ( 3,4,5,6 pentafluorophenyl) titanium, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyrrol-1-yl) phenyl) titanium, and other titanocene photopolymerization initiators As other photopolymerization initiators, ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenyl Phosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine compound, imidazole compound Be .

  Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4'-dimethylaminobenzophenone, and the like. These polymerization initiators may be used alone or in combination of two or more. 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.

<Description of filler addition>
The crosslinkable charge transport layer of the present invention is a crosslinkable charge transport layer obtained by simultaneously curing a radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a charge transport structure. Filler fine particles can be contained for the purpose of improving the wearability.
The crosslinked fine particle-containing charge transport layer of the present invention has a high crosslinking density, and has higher abrasion resistance of the resin part than the non-crosslinked filler-containing binder resin layer, and the above uneven wear is suppressed. In addition to this, the filler fine particles dispersed in the resin are caught by the cured resin cross-linked matrix, and since the filler holding power of the cross-linked matrix is large, the filler is prevented from falling off. Therefore, it is considered that the wear resistance is greatly enhanced.

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

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

  The average primary particle size of the filler is preferably 0.01 to 0.9 μm from the viewpoint of light transmittance and wear resistance of the cross-linked charge transport layer, and more preferably 0.1 μm to 0.5 μm. When the average primary particle size of the filler is 0.01 μm or less, it causes a decrease in wear resistance, a decrease in dispersibility, etc., and when it is 0.9 μm or more, the sedimentation property of the filler is promoted in the dispersion liquid. In addition, toner filming may occur.

  The higher the filler material concentration in the cross-linked charge transport layer, the better the wear resistance, but if it is too high, the residual potential will increase, the writing light transmittance of the surface layer will decrease, causing side effects There is. Therefore, it is about 50% by weight or less, preferably about 30% by weight or less based on the total solid content. Furthermore, these fillers can be surface-treated with at least one kind of surface treatment agent, and it is preferable from the viewpoint of dispersibility of the fillers. Decreasing the dispersibility of the filler not only increases the residual potential, but also decreases the transparency of the coating, causes defects in the coating, and decreases the wear resistance. It can develop into a big problem.

As the surface treatment agent, a conventionally used surface treatment agent can be used, but a surface treatment agent capable of maintaining the insulating properties of the filler is preferable. For example, a titanate coupling agent, an aluminum coupling agent, a zircoaluminate coupling agent, a higher fatty acid, etc., or a mixed treatment of these with a silane coupling agent, Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Silicone, aluminum stearate, or the like, or a mixture thereof is more preferable from the viewpoint of filler dispersibility and image drift prevention. The treatment with the silane coupling agent has a strong influence on the image flow, but the influence may be suppressed by performing a mixing treatment of the surface treatment agent and the silane coupling agent. The surface treatment amount varies depending on the average primary particle size of the filler used, but is preferably 3 to 30% by weight, and more preferably 5 to 20% by weight. If the surface treatment amount is less than this, the filler dispersing effect cannot be obtained, and if the surface treatment amount is too much, the residual potential is significantly increased. These filler materials may be used alone or in combination of two or more.

<Description of other additives>
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. It is suppressed to 20 parts by weight or less, preferably 10 parts by weight or less with respect to 1 part by weight. Moreover, 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. On the other hand, 3 parts by weight or less is appropriate.

<About film production method>
The crosslinked charge transport layer of the present invention contains at least a radical polymerizable monomer (preferably trifunctional or higher) having no charge transport structure and a radical polymerizable compound (preferably monofunctional) having a charge transport structure. It is formed by applying and curing the coating liquid on the second charge transport layer described above. When the radically polymerizable monomer is a liquid, the coating liquid used for coating can be coated by dissolving other components in the liquid. However, if necessary, the coating liquid is diluted with a solvent and coated. The solvent used here is not particularly limited as long as it is usually used. For example, 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, ethers such as tetrahydrofuran, dioxane and propyl ether, dichloromethane And halogen series such as dichloroethane, trichloroethane and chlorobenzene, aromatic series such as benzene, toluene and xylene, and cellosolv series such as methyl cellosolve, ethyl cellosolve and cellosolve acetate. These solvents may be used alone or in combination of two or more.

The coating method used for forming the cross-linked charge transport layer is not particularly limited as long as it is a commonly used coating method. A coating method may be appropriately selected depending on the viscosity of the coating liquid, the desired thickness of the cross-linked charge transport layer, and the like. Examples include dip coating, spray coating, bead coating, ring coating, and the like.
In this invention, after apply | coating this coating liquid, the bridge | crosslinking type charge transport layer is hardened by giving energy from the outside. As the external energy used at this time, heat energy, light energy, or energy using ionizing radiation can be used. However, when ionizing radiation is used, the energy penetration depth and energy intensity are Therefore, since there is a concern about deterioration of electrophotographic characteristics accompanying deterioration of the constituent material of the electrophotographic photosensitive member, it is preferable to cure using thermal energy and light energy. In addition, since curing using light energy can be expected to reduce the amount of solvent used during production, reduce energy required for crosslinking, and further increase the strength of the crosslinked film, it is more preferable to use light energy and effectively Any two of the above means may be used in combination for crosslinking.

  As the thermal energy, air, nitrogen and other gases, steam, various heat media, infrared rays, and electromagnetic waves can be used, and heating is performed from the coated surface side or the support side. The heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower. When the temperature is lower than 100 ° C., the reaction rate is slow, so that productivity is lowered and unreacted material remains in the film. On the other hand, when the treatment is performed at a temperature higher than 170 ° C., the shrinkage of the film due to the cross-linking is increased, and the skin-like defects and cracks may be generated on the surface, or peeling may occur at the interface with the adjacent layer. Further, when the volatile component in the photosensitive layer is sprayed to the outside, it is not preferable because desired electrical characteristics may not be obtained. When using a resin having a large shrinkage due to crosslinking, it is also effective to complete the crosslinking at a high temperature of 100 ° C. or higher after preliminary crosslinking at a low temperature of less than 100 ° C.

As the light energy, a light source such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc metal halide lamp or the like may be used. The radical polymerizable compound (preferably monofunctional) having a charge transporting structure, and further, the absorption characteristics of the photopolymerization initiator used in combination are preferably selected. In general, the light emission illuminance of the light source used is preferably 50 to 2000 mW / cm ^{2 based on} a wavelength of 365 nm. Moreover, when the illuminance measurement in the vicinity of the maximum emission wavelength is possible, it is more preferable to expose in the illuminance range. When the illuminance is low, the time required for curing increases, which is not preferable from the viewpoint of productivity. On the other hand, when the illuminance is high, curing shrinkage is likely to occur, and the surface may have a skin-like defect or crack, or may peel at the interface with the adjacent layer.

  Ionizing radiation is radiation that can ionize a substance. Examples include direct ionizing radiation represented by alpha rays and electron beams, and indirect ionizing radiation represented by X rays and neutron rays. It is done. The ionizing radiation that can be used in the present invention is not particularly limited as long as it is generally used, but in view of the influence on the human body, an electron beam is preferable. As an electron beam irradiation device, when using a device using various electron beam accelerators such as a cockroft Walton type, a bandegraph type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, a high frequency type, etc. Good. The irradiation amount of the electron beam may be appropriately determined according to the material to be used and the thickness of the cross-linked charge transport layer, but it is usually preferable to irradiate electrons having energy of 100 to 1000 keV, preferably 100 to 3000 keV, about 0.1 to 30 Mrad. . When the irradiation amount is less than 0.1 Mrad, the electron beam cannot reach the inside of the cross-linked charge transport layer, and there is a possibility that poor curing of the deep layer may occur. On the other hand, if the irradiation amount exceeds 30 Mrad, the electron beam may reach the charge transport layer or the charge generation layer described above, which may affect the constituent materials of each layer.

During UV irradiation or ionizing radiation irradiation, the temperature of the photoreceptor cross-linked charge transport layer rises due to the influence of heat rays generated from the light source. If the photoreceptor surface temperature rises too much, cure shrinkage of the crosslinkable charge transport layer is likely to occur, and low molecular components contained in the adjacent layer migrate to the crosslinkable charge transport layer, which may cause curing inhibition. In addition, the electrical characteristics as an electrophotographic photosensitive member are not preferable. Therefore, the photoreceptor surface temperature during UV irradiation is 100 ° C. or less, preferably 80 ° C. or less. As a cooling method, it is possible to use an auxiliary cooling agent inside the photosensitive member, cooling with a gas or liquid inside the photosensitive member, or the like.
You may post-heat with respect to the bridge | crosslinking type charge transport layer after hardening as needed. For example, in the case where a large amount of residual solvent remains in the film, it may cause deterioration of electrical characteristics or deterioration with time. Therefore, it is preferable to volatilize the residual solvent by post-heating.

The thickness of the cross-linked charge transport layer is preferably 1 to 15 μm, more preferably 3 to 10 μm from the viewpoint of protecting the photosensitive layer. If the cross-linked charge transport layer is thin, not only will it not be possible to protect the photosensitive layer from mechanical wear due to the contact member to the photoreceptor or proximity discharge by a charger, etc., but it will be difficult to level during film formation. The film surface may be distorted. On the other hand, when the crosslinkable charge transport layer is thick, the entire photoreceptor layer becomes thick, and the reproducibility of the image due to the diffusion of charges is not preferable. However, if the thickness of the cross-linked charge transport layer is greater than the thickness of the charge transport layer, the tendency of the bright portion potential to increase is unfavorable. In the present invention, when the film thickness of the first charge transport layer is T1, the film thickness of the second charge transport layer is T2, and the film thickness of the crosslinkable charge transport layer is T3, the relationship of the following formula (4) Satisfying these conditions is more preferable because their influence can be suppressed.
T1 + T2> T3 × 2 Formula (4)

<About adhesive layer>
For the purpose of preventing delamination due to poor adhesion between the crosslinkable charge transport layer / second charge transport layer photosensitive layer, an adhesive layer may be provided between the two layers as necessary.
As the adhesive layer, the radical polymerizable monomer may be used, or a non-crosslinked polymer compound may be used. Non-crosslinked polymer compounds include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide, and polyvinyl benzal. , Polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, and the like, but are not limited thereto. In addition, the radical polymerizable monomer and the non-crosslinked polymer compound may be used either alone or as a mixture of two or more. Furthermore, a radical polymerizable monomer and a non-crosslinked polymer compound may be used in combination as long as sufficient adhesiveness is obtained. Of course, the charge transport materials described in the present specification may be used or used in combination. Moreover, if it aims at improving adhesiveness, you may use an additive suitably.

  The adhesive layer is formed by applying a coating solution prepared by dissolving or dispersing a compound formulated in a prescribed formulation in a solvent such as tetrahydrofuran, dioxane, dichloroethane, or cyclohexane by dip coating, spray coating, bead coating, or ring coating. it can. The thickness of the adhesive layer is suitably about 0.1 to 5 μm, preferably 0.1 to 3 μm is most suitable.

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

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

<About blocking layer>
It is also possible to further provide a blocking layer between the conductive support and the undercoat layer or between the undercoat layer and the charge generation layer. The blocking layer is added to suppress the injection of holes from the conductive support, and the main purpose is to suppress the soiling. In the blocking layer, a binder resin is generally used as a main component. Examples of these resins include polyamide, alcohol-soluble polyamide (soluble nylon), water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the blocking layer, the above-described method and a known coating method are employed. In addition, 0.05-2 micrometers is suitable for the thickness of a blocking layer. By adopting the two-layer configuration of the blocking layer and the undercoat layer, the background stain suppression effect is dramatically increased, but the influence of the residual potential increase tends to increase. Therefore, it is necessary to determine the composition and thickness of the blocking layer and the undercoat layer with sufficient consideration.

<Protective substances>
A protective substance may be applied to the surface of the electrophotographic photosensitive member for the purpose of improving the cleaning property by reducing the surface energy of the electrophotographic photosensitive member and protecting it from electrical and mechanical hazards. As the protective substance, various materials can be used as long as they can be uniformly applied to the surface of the electrophotographic photosensitive member, but materials such as wax, silicone oil, and fatty acid salts are effective. Fatty acid salts are particularly effective because they can be applied uniformly to a thin layer on the surface of the photoreceptor without causing deterioration of the electrical characteristics of the electrophotographic photoreceptor. Examples of fatty acids include undecyl acid, lauric acid, tridecyl acid, myristic acid, palmitic acid, pendadecyl acid, stearic acid, heptadecyl acid, arachidic acid, montanic acid, oleic acid, arachidonic acid, caprylic acid, capric acid, caproic acid, etc. Examples of the metal salt include salts with metals such as zinc, iron, copper, magnesium, aluminum and calcium.

Furthermore, it is preferable to use a lamellar crystal powder such as zinc stearate as a protective substance. A lamellar crystal has a layered structure in which amphiphilic molecules are self-organized, and when a shearing force is applied, the crystal breaks along the layers and is slippery. This action is effective for lowering the coefficient of friction, but when viewed from the viewpoint of protecting the photoreceptor surface from electric discharge, the characteristics of lamellar crystals that uniformly cover the photoreceptor surface under shearing force are as follows: Since the surface of the photoreceptor can be effectively covered with a small amount of protective material, it is desirable as a protective material.
The method for applying the protective substance is not particularly limited, and examples thereof include a method in which a protective substance is applied in advance to a member such as a cleaning member that contacts the photosensitive member, and a method in which a dedicated application member is integrated with the process cartridge. . Providing a dedicated application member is preferable because a stable amount can be applied over a long period of time.

<< Regarding Configuration of Image Forming Apparatus >>
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 uses the electrophotographic photosensitive member having the crosslinkable charge transport layer of the present invention. For example, at least after the photosensitive member is subjected to charging, image exposure, and development processes, an image holding member (transfer paper) ) And a means for fixing and cleaning the surface of the photoreceptor, if necessary. In some cases, an image forming apparatus that directly transfers an electrostatic latent image to a transfer body and develops the image forming apparatus does not necessarily include the above-described means disposed on the photoreceptor.

FIG. 2 is a schematic diagram illustrating an example of an image forming apparatus. A charging charger (3) is used as a means for charging the photoconductor on average. As the charging means, a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or the like is used, and a known system can be used.
Next, the image exposure unit (5) is used to form an electrostatic latent image on the uniformly charged photoreceptor (1). As the light source, all luminescent materials such as a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), and an electroluminescence (EL) can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.

Next, the developing unit (6) is used to visualize the electrostatic latent image formed on the photoreceptor (1). Development methods include a one-component development method using a dry toner, a two-component development method, and a wet development method using a wet toner. When the photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. If this is developed with toner of negative (positive) polarity (detection fine particles), a positive image can be obtained, and if developed with toner of positive (negative) polarity, a negative image can be obtained.
Next, the transfer charger (10) is used to transfer the toner image visualized on the photosensitive member onto the transfer member (9). In addition, a pre-transfer charger (7) may be used for better transfer. As these transfer means, a transfer charger, an electrostatic transfer method using a bias roller, a mechanical transfer method such as an adhesive transfer method and a pressure transfer method, and a magnetic transfer method can be used. As the electrostatic transfer method, the charging means can be used.
Next, a separation charger (11) and a separation claw (12) are used as means for separating the transfer body (9) from the photoreceptor (1). As other separation means, electrostatic adsorption induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like are used. As the separation charger (11), the charging means can be used.

Next, a fur brush (14) and a cleaning blade (15) are used to clean the toner remaining on the photoreceptor after transfer. Further, a pre-cleaning charger (13) may be used in order to perform cleaning more efficiently. Other cleaning means include a web method, a magnet brush method, and the like, but each may be used alone or in combination. Next, a neutralizing unit is used for the purpose of removing the latent image on the photoreceptor as required. As the charge removal means, a charge removal lamp (2) and a charge removal charger are used, and the exposure light source and the charging means can be used respectively. In FIG. 2, 4 is an eraser, and 8 is a registration roller.
In addition, known means can be used for reading, feeding, fixing, and discharging the document that are not close to the photosensitive member.
The image forming apparatus of the present invention may be configured such that 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.

The present invention also relates to an image forming method and an image forming apparatus process cartridge using the electrophotographic photoreceptor according to the present invention for such image forming means.
The image forming means may be fixedly incorporated in a copying apparatus, facsimile, or printer, but may be incorporated in these apparatuses in the form of a process cartridge and detachable. An example of the process cartridge is shown in FIG.
The process cartridge for the image forming apparatus includes a photoreceptor (101), and in addition, a charging unit (102), a developing unit (104), a transfer unit (106), a cleaning unit (107), and a discharging unit (not shown). ), And an apparatus (part) that can be attached to and detached from the image forming apparatus main body.

  Referring to the image forming method using the apparatus illustrated in FIG. 3, the surface of the photoconductor (101) is exposed by charging by the charging means (102) and exposure by the exposure means (103) while rotating in the direction of the arrow. An electrostatic latent image corresponding to the image is formed, and the electrostatic latent image is developed with toner by the developing means (104). The toner development is transferred to the transfer body (105) by the transfer means (106), and printed. Out. Next, the surface of the photoconductor after the image transfer is cleaned by a cleaning unit (107), and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. Parts and% are based on weight.
First, a synthesis example of a charge generation material (titanyl phthalocyanine crystal) will be described.

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

40 parts of this wet cake (water paste) thus obtained was put into 200 parts of tetrahydrofuran and stirred vigorously (2000 rpm) with a homomixer (Kennis, MARKIIf model) at room temperature, and the dark blue color of the paste turned pale blue. When changed (20 minutes after the start of stirring), stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filter were washed with tetrahydrofuran to obtain a pigment wet cake. This was dried under reduced pressure (5 mmHg) at 70 ° C. for 2 days to obtain 8.5 parts of titanyl phthalocyanine crystals. The solid content concentration of the wet cake was 15% by mass. The crystal conversion solvent was used in a mass ratio of 33 times that of the wet cake. In addition, the halogen-containing compound is not used for the raw material of the synthesis example 1. When the obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions, the Bragg angle 2θ with respect to CuKα ray (wavelength 1.542１．５) was 27.2 ± 0.2 °, and the maximum peak and the minimum angle 7.3. It has a peak at ± 0.2 °, and further has major peaks at 9.4 ± 0.2 °, 9.6 ± 0.2 °, 24.0 ± 0.2 °, and 7.3 A titanyl phthalocyanine powder having no peak between the peak at 0 ° and the peak at 9.4 ° and further having no peak at 26.3 ° was obtained. The result is shown in FIG.
<X-ray diffraction spectrum measurement conditions>
X-ray tube: Cu
Voltage: 50kV
Current: 30mA
Scanning speed: 2 ° / min Scanning range: 3 ° -40 °
Time constant: 2 seconds

(Dispersion 1)
Using a PSZ ball having a diameter of 0.5 mm in a commercially available bead mill disperser, a 2-butanone solution in which polyvinyl butyral was dissolved and titanyl phthalocyanine crystal were introduced, and the rotor rotation speed was 1200 r. p. m. For 30 minutes to prepare a charge generation layer coating solution.
Titanylphthalocyanine crystal 15 parts Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 10 parts 2-butanone 280 parts

(Synthesis Example 2)
In accordance with Japanese Patent No. 3166293, Synthesis Examples and Example 1, hydroxygallium phthalocyanine was synthesized.
That is, 30 parts of 1,3-diiminoisoindoline and 9.1 parts of gallium trichloride were added to 230 parts of quinoline and reacted at 200 ° C. for 3 hours, and then the product was filtered off. Subsequently, it was washed with acetone and methanol, and the wet cake was dried to obtain 28 parts of chlorogallium phthalocyanine crystals.
Subsequently, 3 parts of the chlorogallium phthalocyanine crystal was dissolved in 60 parts of concentrated sulfuric acid at 0 ° C., and then this solution was dropped into 450 parts of distilled water at 5 ° C. to precipitate a crystal. After washing with distilled water, dilute ammonia water or the like, it was dried to obtain 2.5 parts of hydroxygallium phthalocyanine crystal. Further, 0.5 parts of the hydroxygallium phthalocyanine crystal was milled for 24 hours together with 15 parts of dimethylformamide and 30 parts of glass beads having a diameter of 1 mm, and then the crystals were separated. Subsequently, it was washed with methanol and dried to obtain a target hydroxygallium phthalocyanine crystal.
When the obtained hydroxygallium phthalocyanine crystal was subjected to X-ray diffraction spectrum measurement under the same conditions as in Synthesis Example 1, the Bragg angle 2θ with respect to CuKα ray (wavelength 1.542Å) was 7.5 °, 9.9 °, 12.5 It had strong diffraction peaks at °, 16.3 °, 18.6 °, 25.1 ° and 28.3 °. The obtained spectrum was the same as the X-ray diffraction spectrum described in Japanese Patent No. 3166293 and FIG.

(Dispersion 2)
Using a PSZ ball having a diameter of 0.5 mm in a commercially available bead mill disperser, a 2-butanone solution in which polyvinyl butyral was dissolved and a hydroxygallium phthalocyanine crystal were introduced, and the rotor rotation speed was 1200 r. p. m. For 30 minutes to prepare a charge generation layer coating solution.
Hydroxygallium phthalocyanine crystal 15 parts Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 10 parts 2-butanone 280 parts

(Synthesis Example 3)
Chlorogallium phthalocyanine was synthesized according to Japanese Patent No. 3123185, Synthesis Example and Example 2.
That is, 30 parts of 1,3-diiminoisoindoline and 9.1 parts of gallium trichloride are added to 230 parts of quinoline and reacted at 200 ° C. for 3 hours, and then the product is filtered and washed with acetone and methanol. did. Next, the wet cake was dried to obtain chlorogallium phthalocyanine crystals. This chlorogallium phthalocyanine crystal is dry-ground for 3 hours in an automatic mortar, and further 0.5 part of chlorogallium phthalocyanine is mixed with 60 parts of 1 mmφ glass beads at room temperature in 20 parts of a mixed solvent of water / chlorobenzene 1:10. After ball milling for 24 hours, it was filtered off, washed with 10 parts of methanol, and dried to obtain chlorogallium phthalocyanine crystals.
The obtained chlorogallium phthalocyanine crystal was subjected to X-ray diffraction spectrum measurement under the same conditions as in Synthesis Example 1. As a result, the Bragg angle 2θ with respect to the CuKα ray (wavelength 1.542Å) was 7.4 °, 16.6 °, 25.5. It had strong diffraction peaks at ° and 28.3 °. The obtained spectrum was the same as the X-ray diffraction spectrum described in Japanese Patent No. 3123185 and FIG.

(Dispersion 3)
Using a PSZ ball having a diameter of 0.5 mm in a commercially available bead mill disperser, a 2-butanone solution in which polyvinyl butyral was dissolved and a chlorogallium phthalocyanine crystal were introduced, and the rotor rotation speed was 1200 r. p. m. For 30 minutes to prepare a charge generation layer coating solution.
Chlorogallium phthalocyanine crystal 15 parts Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 10 parts 2-butanone 280 parts

(Synthesis Example 4)
The following asymmetric azo pigments were prepared according to the methods described in Japanese Patent Publication No. 60-29109 and Japanese Patent No. 3026645, and dispersed by the following method.
Dispersion was carried out by the following dispersion method with a formulation having the following composition to prepare a dispersion as a charge generation layer coating liquid. This dispersion is referred to as dispersion 4.
(Dispersion 4)
Asymmetric azo pigment represented by the following chemical formula 5 parts Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 2 parts Cyclohexanone 250 parts 2-butanone 100 parts

<Distribution method>
Using a PSZ ball having a diameter of 10 mm for the ball mill disperser, all of the solvent and azo pigment in which polyvinyl butyral was dissolved were charged, and the rotational speed was 85 r. p. m. Was dispersed for 7 days to prepare a dispersion.

(Synthesis Example 5)
Next, a synthesis example of a compound having a monofunctional charge transporting structure used for a cross-linked charge transport layer in a photoreceptor preparation example described later will be described.
(Synthesis example of a compound having a monofunctional charge transporting 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 (following formula B) 113.85 parts (0.3 mol) of methoxy group substituted triarylamine compound (following formula A) and 138 parts (0.92 mol) of sodium iodide To this, 240 parts of sulfolane was added and heated to 60 ° C. in a nitrogen stream. In this liquid, 99 parts (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 1500 parts 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 parts (yield = 80.4%) of white crystals of the following formula B were obtained.
Melting point: 64.0-66.0 ° C

(2) Triarylamino group-substituted acrylate compound (Exemplary Compound No. 54) 82.9 parts (0.227 mol) of the hydroxy group-substituted triarylamine compound (Formula B) obtained in (1) above was dissolved in 400 ml of tetrahydrofuran. Then, an aqueous sodium hydroxide solution (NaOH: 12.4 parts, water: 100 ml) was added dropwise in a nitrogen stream. This solution was cooled to 5 ° C., and 25.2 parts (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 purified 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. 54.73 parts of white crystals (yield = 84.8%) were obtained.
Melting point: 117.5-119.0 ° C

<Example>
To an aluminum cylinder having a diameter of 100 mm as a conductive support, an undercoat layer coating solution, a charge generation layer coating solution, a first charge transport layer coating solution, a second charge transport layer coating solution, A cross-linked charge transport layer coating solution is sequentially applied and dried to form an undercoat layer of about 3.5 μm, a charge generation layer of about 0.2 μm, a first charge transport layer having a thickness described in Table 7, The charge transport layer and the cross-linked charge transport layer were formed to produce a laminated photoreceptor. After the coating of each layer, touch drying was performed, then the undercoat layer was 130 ° C., the charge generation layer was 95 ° C., and the first charge transport layer and the second charge transport layer were each dried at 120 ° C. for 20 minutes. Went.
The crosslinkable charge transport layer is formed by applying the crosslinkable charge transport layer coating solution onto the laminated photoreceptor comprising the conductive support / undercoat layer / charge generation layer / first charge transport layer / second charge transport layer. After application, UV crosslinking (bulb type H bulb) (FusionUV Systems Co., Ltd.) is used for crosslinking by light irradiation under conditions of lamp output 200 W / cm, illuminance: 450 mW / cm ² , irradiation time: 30 seconds. It was. Thereafter, by drying at 130 ° C. for 20 minutes, an electrophotography comprising a conductive support / undercoat layer / charge generation layer / first charge transport layer / second charge transport layer / crosslinked charge transport layer is formed. A photoreceptor was obtained.

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

The compositions of the charge generation layer, the first charge transport layer, the second charge transport layer, and the crosslinked charge transport layer are shown in the following table.
(Charge transport layer coating solution)
The materials used for the charge transport layer coating solution are as follows.
Charge transport material

Arylamine compound having a substituted or unsubstituted alkylamino group

・サノールＬＳ―７４４ 三共製・・・ＡＯ−２

・ＢＨＴ 関東化学製・・・ＡＯ−３

Antioxidant ・ Sanol LS-2626 Sankyo made ... AO-1

・ Sanol LS-744 Sankyo ... AO-2

・ BHT Kanto Chemical Co., Ltd .... AO-3

<Crosslinkable charge transport layer coating solution material>
The crosslinkable charge transport layer solution was prepared using the following materials. The parentheses indicate the abbreviations used in the recipe.
Radical polymerizable compound having charge transporting structure

(Radically polymerizable monomer without charge transport structure)
・ Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku Co., Ltd.) (AM-1)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99
・ 6-Hexanediol diacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) (AM-2)
Molecular weight: 226, number of functional groups: bifunctional, molecular weight / number of functional groups = 113
・ Dipentaerythritol caprolactone-modified hexaacrylate (KAYARAD DPCA-120, manufactured by Nippon Kayaku) (AM-3)
Molecular weight: 1947, number of functional groups: 6 functions, molecular weight / number of functional groups = 325

(Filler)
・ Alumina (average primary particle size: 0.3 μm, Sumiko Random AA03, manufactured by Sumitomo Chemical)
... (AA03)
(Polymerization initiator)
1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals) ... I-184

The prescription table of the electrophotographic photoreceptor used in the examples is shown below.
PC-Z is a bisphenol Z-type polycarbonate resin used for the charge transport layer.

<Real machine test>
For running paper using an actual machine, the electrophotographic photosensitive member is mounted on an electrophotographic process cartridge, and a maximum of 1 million actual machine paper feeding tests (A4, NBS Ricoh Co., Ltd.) are performed using a color station of a modified Ricoh imgioMP C6000. (Production of MyPaper, charging potential at start-700 V) was performed, and abrasion amount measurement, bright part potential measurement, image density evaluation, and background contamination evaluation were performed. Potential measurement and image output were performed at the black station.
Table 11 shows the measurement results of the characteristics of the photoconductor, such as wear amount measurement and bright portion potential measurement.

(Abrasion amount measurement)
After the running of 100,000 sheets, 300,000 sheets, and 1 million sheets, the photoreceptor was taken out, and the amount of wear was measured from the difference in film thickness of the photoreceptor before and after the running test. For film thickness measurement, an eddy current film thickness meter Fischer scope MMS (manufactured by Fischer) was used.
(Light area potential measurement)
The grid potential was adjusted so that the dark portion potential would be −700 (V), and then the black portion image was output to measure the bright portion potential before running. Further, the bright portion potential was measured in the same manner after 100,000 running, 300,000 running, and 1 million running. A TREKMODEL 344 was used as the surface electrometer.

<NOx gas exposure test>
An NOx gas exposure test was performed using an electrophotographic photosensitive member different from the electrophotographic photosensitive member used in the paper passing running. A 5 cm square tape was applied to the surface of the photoconductor to mask the photoconductor. Gas exposure was carried out by leaving still for 96 hours in a chamber adjusted to an atmosphere of NO gas concentration 40 ppm and NO ₂ gas concentration 10 ppm. After completion of the gas exposure, a halftone image having an image density of 50% was output using an imgio MP C6000 manufactured by Ricoh, and the image density difference between the gas exposed part and the masking part (unexposed part) was evaluated. Note that the masked part is considered not exposed to gas.
The image density difference was based on the following criteria.
5: Level where the density difference between the exposed area and the mask area cannot be confirmed with the naked eye 4: Level where the density difference between the exposed area and the mask area can be slightly confirmed 3: Although the density difference between the exposed area and the mask area can be confirmed, Level where there is no problem 2: Level at which the density difference between the exposed area and the mask area can be clearly confirmed 1: Level at which the density difference between the exposed area and the mask area is very large

Next, characteristics of the actual image were also evaluated using the following evaluation items.
(Image density evaluation)
A halftone image with an image density of 50% was output before running, after running 100,000, 300,000, and after 1,000,000, and the density change was confirmed before and after running.
(Earth dirt evaluation)
Before running, after running 100,000 sheets, 300,000 sheets, and after finishing 1,000,000 sheets, a solid white image (without optical writing) was output, and background stain was confirmed by visual observation.

(Negative ghost evaluation)
Before running, after running 100,000 sheets, 300,000 sheets, and after finishing 1 million sheets, a white solid image (without optical writing) was output, and negative ghost was confirmed by visual observation.
The background stain evaluation results and the negative ghost evaluation results are shown in Table XX.
Evaluation was performed according to the following criteria.
◎: No problem in both dirt and negative ghost ○: Slight deterioration is observed in either the dirt or negative ghost.

<Light part potential repeat measurement>
Using a black station of Ricoh's imgio MP C6000 remodeled machine, 1000 solid images were output continuously, and at the same time, the bright area potential was measured. The first and 1000th image densities were compared and evaluated according to the following criteria. After running 100,000 sheets, 300,000 sheets, and 1,000,000 sheets, 1000 solid images are output in the same way, and the bright part potential is measured at the same time. Comparison was made and evaluated according to the following criteria: Levels at which the density difference between the 5th and 1000th sheets cannot be confirmed with the naked eye.
Level at which the density difference between the 4th and 1000th sheets can be confirmed slightly. The level difference between the 3rd and 1st sheets and the 1000th sheet can be confirmed, but there is no problem with visual observation. 2nd and 1000th sheets Level that can clearly check the density difference between the 1: 1 and the 1000th sheet

  The test results are shown in the following table.

From the above results, a cross-linked charge transport layer formed by curing a radical polymerizable monomer that satisfies the relational expression (1) and does not have a charge transport structure and a radical polymerizable compound that has a charge transport structure. Sequentially laminated electrophotographic photoreceptors show little increase in bright area potential after running test, no image flow due to negative ghosting or NOx exposure, excellent wear resistance, and suppression of background stains. It was possible to suppress a sharp light potential increase during continuous output. From the above results, the compound represented by the general formula (4-1), the compound represented by the general formula (5-1), the compound represented by the general formula (5-2), It was confirmed that the image quality stability was further improved when the compound represented by the general formula (6) was contained.
As a result, high-quality images can be stably obtained even after long-term repeated use. In particular, the radical polymerizable monomer having no charge transporting structure has a functional group number of 3 or more and a molecular weight / functional group number of 250 or less and a radical polymerizable compound having a monofunctional charge transporting structure is cross-linked. The wear resistance was improved, and the wear resistance was greatly improved by adding a filler to the cross-linked charge transport layer.

From the above results, it was confirmed that when the charge transport material of the charge transport layer is a distyryl compound, particularly a distyrylbenzene derivative, there is a great effect in reducing the bright part potential. Furthermore, from the above results, when at least one of R ₃ , R ₈ , R _19, and R ₂₄ of the distyrylbenzene derivative represented by the general formula (3) is a methyl group, it is effective for reducing the bright part potential. It was confirmed.
It was also confirmed that if the charge transport layer contains a hindered amine antioxidant or a hindered phenol antioxidant, it is possible to suppress fluctuations in image density after exposure to NOx gas. An antioxidant having both a hindered amine and a hindered phenol skeleton in the same molecule was particularly effective in changing the image density after exposure to NOx gas.
Further, from the above results, it is confirmed that when the film thickness of the first charge transport layer is smaller than twice the film thickness of the second charge transport layer, the difference in image density after exposure to NOx is increased. It was confirmed that the film thicknesses of the charge transport layer and the second charge transport layer are also important factors for improving the image quality.
In addition, from the above results, when the film thickness of the charge transport layer is thinner than twice the film thickness of the cross-linked charge transport layer, it is confirmed that the bright portion potential tends to increase. It was confirmed that thickness is also an important factor for high image quality.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charger charger 4 Eraser 5 Image exposure part 6 Developing unit 7 Charger before transfer 8 Registration roller 9 Transfer body 10 Transfer charger 11 Separation charger 12 Separation claw 13 Charger before cleaning 14 Fur brush 15 Cleaning blade 31 Conductivity Support 32 Charge generation layer 33 First charge transport layer 34 Second charge transport layer 35 Cross-linked charge transport layer 101 Photoconductor 102 Charging means 103 Exposure means 104 Development means 105 Transfer body 106 Transfer means 107 Cleaning means

JP 2002-139659 A JP 2001-125286 A JP 2001-324857 A JP 2003-098708 A JP-A-5-181299 Japanese Patent Laid-Open No. 2002-006526 JP 2002-082465 A JP 2000-284514 A JP 2000-284515 A JP 2001-194413 A Japanese Patent No. 3194392 JP 2004-302451 A JP 2007-072139 A JP 2002-207308 A JP 2000-292959 A JP 2003-186222 A JP-A-4-28459 Japanese Patent Laid-Open No. 2001-255585 JP 2007-279678 A JP 2007-272191 A JP 2007-272192 A JP 2005-99688 A JP 2000-242008 Japanese Patent Laid-Open No. 11-352710 JP-A-8-082941 Japanese Patent No. 3287126 Japanese Patent Application Laid-Open No. 07-244389 JP 2005-047695 A JP 2002-207308 A JP 2008-70676 A

Claims (25)

Curing at least the charge generation layer, the first charge transport layer, the second charge transport layer, the radical polymerizable monomer having no charge transport structure and the radical polymerizable compound having the charge transport structure on the conductive support. In the electrophotographic photosensitive member formed by sequentially laminating a cross-linked charge transport layer,
The first charge transport layer contains a charge transport material having a triarylamine structure and an arylamine compound having at least one substituted or unsubstituted alkylamino group,
The second charge transport layer comprises a charge transport material having a triarylamine structure and an arylamine compound having at least one substituted or unsubstituted alkylamino group, the same as the compound contained in the first charge transport layer Containing
The weight ratio of the arylamine compound having at least one alkylamino group to the solid content weight of the first charge transport layer is C1,
When the weight ratio of the arylamine compound having at least one alkylamino group to the solid content weight of the second charge transport layer is C2,
The following equation (1) holds: 0 ≦ C2 <C1 (1)
An electrophotographic photosensitive member characterized by the above. Furthermore, the following formula (2) holds for the C1 0.005 <C1 <0.15 (2)
The electrophotographic photosensitive member according to claim 1. The functional group of the radical polymerizable monomer having no charge transport structure and / or the functional group of the radical polymerizable compound having the charge transport structure is an acryloyloxy group and / or a methacryloyloxy group. The electrophotographic photosensitive member according to claim 1. The number of functional groups of the radical polymerizable monomer having no charge transport structure is 3 or more, and the ratio of molecular weight to the number of functional groups (molecular weight / functional group number) is 250 or less. The electrophotographic photosensitive member according to any one of the above. The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein the charge transporting structure of the radical polymerizable compound having the charge transporting structure is a triarylamine structure. The radical polymerizable compound having the charge transporting structure,
The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor is at least one of compounds represented by the following general formula (1) or (2).

(Wherein R ₄₀ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, A group, an alkoxy group, —COOR ₄₁ (R ₄₁ represents 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. ), A halogenated carbonyl group or CONR ₄₂ R ₄₃ (R ₄₂ and R ₄₃ have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or a substituent. Represents an aryl group which may be the same or different from each other. Ar ₂ and Ar ₃ represent a substituted or unsubstituted arylene group and may be the same or different. Ar ₄ and Ar ₅ are substituted. X represents an unsubstituted aryl group, which may be the same or different, and X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group. Represents 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 each represents an integer of 0 to 3. ) The electrophotographic photoreceptor according to any one of claims 1 to 6, wherein the arylamine compound having at least one alkylamino group is represented by the following general formula (4-1).

(In the formula, R ₉₂ and R ₉₃ represent an aromatic ring group-substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, which may be the same or different. R ₉₂ and R ₉₃ are bonded to each other to form a nitrogen atom. And j and k each represent an integer of 0 to 3. However, j and k are not simultaneously 0. R ₉₄ and R ₉₅ are hydrogen atoms, substituted or unsubstituted. Represents an alkyl group having 1 to 11 carbon atoms and a substituted or unsubstituted aromatic ring group, which may be the same or different, and Ar ₅₁ and Ar ₅₂ each represent a substituted or unsubstituted aromatic ring group and are the same But it may be different.) The electrophotographic photoreceptor according to claim 1, wherein the arylamine compound having at least one alkylamino group is represented by the following general formula (5-1).

(In the formula, R ₉₆ and R ₉₇ represent a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted alkyl group, and may be the same or different, provided that at least one of R ₉₆ and R ₉₇ One is a substituted or unsubstituted alkyl group, and R ₉₆ and R ₉₇ may be bonded to each other to form a heterocyclic group containing a nitrogen atom, Ar ₅₃ and Ar ₅₄ are substituted or unsubstituted aromatic groups. (P and q each represent an integer of 0 to 3. However, p and q are not simultaneously 0. r represents an integer of 1 to 3) The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the arylamine compound having at least one alkylamino group is represented by the following general formula (5-2).

(In the formula, R ₉₈ and R _{99 each} represents a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted alkyl group, and may be the same or different, provided that at least one of R ₉₆ and R ₉₇ One is a substituted or unsubstituted alkyl group, and R ₉₈ and R ₉₉ may be bonded to each other to form a heterocyclic group containing a nitrogen atom, and Ar ₅₅ and Ar ₅₆ are substituted or unsubstituted aromatic groups. S and t each represent an integer of 0 to 3. However, s and t are not simultaneously 0. u represents an integer of 1 to 3.) The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the arylamine compound having at least one alkylamino group is represented by the following general formula (6).

(In the formula, R ₁₀₁ and R ₁₀₂ represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aromatic ring group, and may be the same or different. However, any one of R ₁₀₁ and R ₁₀₂ may be used. is a substituted or unsubstituted alkyl group aromatic group. Further, R _101, R ₁₀₂ may be bonded to each other, good .Ar ₅₇ also form a substituted or unsubstituted heterocyclic group containing a nitrogen atom is a substituted or Represents an unsubstituted aromatic ring group.)   11. The electrophotography according to claim 1, wherein the charge transport material having a triarylamine structure contained in the first charge transport layer and the second charge transport layer is a distyryl compound. Photoconductor. The electrophotographic photoreceptor according to any one of claims 1 to 11, wherein the distyryl compound having a triarylamine structure is a distyrylbenzene derivative represented by the general formula (3) having the following structure.

[Wherein R _{1 to} R ₃₀ are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms. An aryl group substituted with an alkoxy group and an unsubstituted aryl group are represented and may be the same or different. ] The electrophotographic photosensitive member according to claim 12, wherein at least one of R ₃ , R ₈ , R ₁₉ and R ₂₄ of the distyrylbenzene derivative represented by the general formula (3) is a methyl group.   14. The first charge transport layer and / or the second charge transport layer contains at least one antioxidant selected from hindered phenol derivatives and hindered amine derivatives. The electrophotographic photosensitive member according to any one of the above.   The electrophotographic photosensitive member according to claim 14, wherein the antioxidant is a compound having a hindered phenol structure and a hindered amine structure in the same molecule.   16. The charge generation layer according to claim 1, wherein the charge generation layer contains one or more selected from titanyl phthalocyanine, hydroxygallium phthalocyanine, and chlorogallium phthalocyanine as a charge generation material. Electrophotographic photoreceptor.   The titanyl phthalocyanine has a maximum intensity diffraction peak at least 27.2 ° of the black angle (2θ ± 0.2 °) in an X-ray diffraction spectrum using CuKα characteristic X-ray (1.542Å). , 9.4 °, 9.6 °, 24.0 °, major diffraction peak at 7.3 °, peak at 7.3 ° and peak at 9.4 ° The electrophotographic photosensitive member according to claim 16, wherein the electrophotographic photosensitive member is a titanyl phthalocyanine crystal having no diffraction peak between and 26.3 °. The film thickness T1 of the first charge transport layer and the film thickness T2 of the second charge transport layer satisfy the relationship of the following formula (3). Electrophotographic photoreceptor.
T1> T2 × 2 Formula (3) The film thickness T1 of the first charge transport layer, the film thickness T2 of the second charge transport layer, and the film thickness T3 of the bridged charge transport layer satisfy the relationship of the following formula (4). The electrophotographic photosensitive member according to claim 1.
T1 + T2> T3 × 2 Formula (4)   The electrophotographic photoreceptor according to claim 1, wherein the crosslinkable charge transport layer contains a filler. A method for producing an electrophotographic photosensitive member according to claim 1,
Forming a charge generation layer on a conductive support;
On the charge generation layer, a coating liquid containing a charge transport material having a triarylamine structure and an arylamine compound having at least one substituted or unsubstituted alkylamino group is applied to form a first charge. Forming a transport layer;
A charge transport material having a triarylamine structure on the first charge transport layer and an aryl having at least one substituted or unsubstituted alkylamino group identical to the compound contained in the first charge transport layer; Applying a coating liquid containing an amine compound to form a second charge transport layer;
A coating liquid containing a radical polymerizable monomer having no charge transporting structure and a radical polymerizable compound having a charge transporting structure is applied on the second charge transporting layer and cured to form a cross-linked charge transporting layer. Forming a process,
The weight ratio of the arylamine compound having at least one alkylamino group to the solid content weight of the first charge transport layer is C1, and the aryl having at least one alkylamino group to the solid content weight of the second charge transport layer When the weight ratio of the amine compound is C2, the following formula (1) holds: 0 ≦ C2 <C1 (1)
A method for producing an electrophotographic photosensitive member, characterized in that it is configured as described above.   21. An image forming apparatus comprising at least a charging unit, an exposure unit, a developing unit, a transfer unit, and an electrophotographic photosensitive member, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of claims 1 to 20. An image forming apparatus, comprising:   21. The electrophotographic photosensitive member according to claim 1, 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. An image forming apparatus, comprising:   A cartridge in which an electrophotographic photosensitive member and at least one means selected from charging means, exposure means, development means, transfer means, and cleaning means are mounted, and the cartridge is detachable from the apparatus main body. The image forming apparatus according to claim 22, wherein the image forming apparatus is an image forming apparatus.   In the process cartridge for an image forming apparatus in which the electrophotographic photosensitive member is integrated with at least one means selected from a charging unit, an exposing unit, a developing unit, a transferring unit, and a cleaning unit, the electrophotographic photosensitive unit is claimed in claim 1. 21. A process cartridge for an image forming apparatus, which is the electrophotographic photosensitive member according to any one of items 1 to 20.

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