JP2009276379A - Electrophotographic photoreceptor, image forming method using the same, image forming apparatus, and process cartridge for image forming apparatus - Google Patents

Abstract

An electronic device capable of forming a high-quality image over a long period of time without causing defects related to the output image quality of an image forming apparatus, such as wear and scratches due to repeated use of a photoconductor, and causing less unevenness of image density. An object is to provide a photographic photoreceptor.
In an electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, the charge transport layer contains at least a phenol derivative having a methylol group, a polycarbonate resin, and a charge transport material. An electron formed by using a coating solution for a charge transport layer and containing at least two components among the phenol derivative having a methylol group, a polycarbonate resin, and a charge transport material by heating. Photoconductor.
[Selection figure] None

Description

The present invention relates to an electrophotographic photosensitive member such as a copying machine, a laser printer, and a normal facsimile, and a process cartridge, an image forming apparatus, and an image forming method using the same.
Specifically, the present invention relates to an electrophotographic photosensitive member having a laminated charge transport layer excellent in wear durability, a process cartridge for an image forming apparatus using the same, an image forming apparatus, and an image forming method.

  In recent years, organic photoreceptors have been widely used for electrophotographic photoreceptors (hereinafter also simply referred to as photoreceptors). Organic photoreceptors are advantageous over inorganic photoreceptors due to the fact that materials that can be used for various exposure light sources from visible light to infrared light can be easily developed, materials that are free from environmental pollution can be selected, and manufacturing costs are low. There are many points. However, organic photoconductors have weak physical and chemical strengths, and have drawbacks such that wear and scratches are likely to occur due to long-term use.

  An electrophotographic image forming apparatus is generally 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. The image forming apparatus includes an image forming device, a developing device that attaches toner to the image portion of the electrostatic latent image formed by the latent image forming device, and a transfer unit that transfers the toner attached to the image portion to the transfer object. Some of them are equipped with a cleaning device that removes toner remaining on the surface of the photoreceptor without being transferred, if necessary. Since toner remaining on the surface of the photoconductor after the transfer contributes to image quality deterioration, a cleaning device is employed in many image forming apparatuses.

  As the cleaning device, a brush, a magnetic brush, a blade, or the like is generally used. For brush cleaning, polyester and acrylic fibers are used, and are used after optimization by changing the shape such as loop shape and straight hair shape, and the hardness and thickness of the fibers. However, brush cleaning makes it difficult to sufficiently remove the toner because fine toner passes through the fibers. In addition, a magnetic brush method that electrostatically removes toner by applying an electric field to the brush has been proposed. However, this method also causes a phenomenon that toner scattered by electrostatic force adheres to the photoconductor again. Thorough cleaning is difficult. Therefore, as the current cleaning means, blade cleaning using an elastic blade is mainly used from the standpoint of removal of residual toner, cost, and reduction in diameter. In blade cleaning, the photosensitive member surface layer slides in contact with the cleaning blade, toner, and the like, and therefore mechanical wear and scratches are likely to occur on the photosensitive member surface.

Due to the characteristics of the apparatus constituent members as described above, a physical external force is directly applied to the surface of the photoconductor, so that the photoconductor has been required to be durable.
On the other hand, many research examples have been reported in which a protective layer is provided on the outermost surface of the photoreceptor and inorganic fine particles are dispersed in the protective layer to improve mechanical durability. For 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 research examples have been reported that improve by increasing the hardness of the photoreceptor surface. 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 surface layer of the photoreceptor 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 surface layer. . For example, Patent Documents 5 to 7 propose methods for improving the wear resistance and scratch resistance of a surface layer by applying a thermosetting resin as a binder component of the surface layer. In Patent Documents 8 to 10 and the like, it is proposed to improve wear resistance and scratch resistance by using a siloxane resin having a crosslinked structure as a charge transport material. Further, in Patent Document 11 and Patent Document 12 and the like, in order to improve wear resistance and scratch resistance, both the binder and the charge transport material are monomers having a carbon-carbon double bond, and charge transport having a carbon-carbon double bond. Techniques using materials and binder resins have been reported.

  However, even those described in the report shown here have many problems such as insufficient mechanical durability and insufficient electrical properties to be provided as an electrophotographic photosensitive member. For example, Patent Document 12 describes that a polyfunctional acrylate monomer is used as a composition of the surface layer in order to improve wear resistance and scratch resistance. However, there is no specific description about the charge transporting material, and if a low molecular charge transporting material is simply included in the surface layer, there may be a problem in compatibility with the cured product of the monomer, In some cases, there may be problems such as bleed of low molecular components or a decrease in mechanical durability of the surface layer. In addition, there is a description that a polycarbonate resin is contained for improving the compatibility, but the content in the surface layer of the polyfunctional acrylic monomer is lowered, so that a desired mechanical durability cannot be obtained. There is no sufficient wear resistance. Further, there is a description that the surface layer can be a thin film when the surface layer does not contain a charge transporting material. However, in the case of a photoreceptor having a surface layer as shown here, the lifetime is taken as a measure of the life until the surface layer is worn away, and when the surface layer is a thin film, the time until the wear disappears. Is short, so it is difficult to call a long-life photoconductor.

  Further, in Patent Document 11, it is provided with a charge transport layer formed using a coating liquid comprising a monomer having a carbon-carbon double bond, a charge transporting material having a carbon-carbon double bond, and a binder resin. Are listed. In this patent document, the binder may be a compound having a carbon-carbon double bond and reactivity with a charge transporting material, or having no carbon-carbon double bond and having a charge transporting property. A compound that is not reactive with the material may be used. The photoreceptor described in this patent document has both wear resistance and electrical characteristics, and is notable. However, when a non-reactive compound is used as the binder resin, the monomer and the charge transport material The compatibility with the cured product produced by the reaction is poor, resulting in a decrease in surface smoothness due to layer separation or the like, a resulting poor cleaning property and a decrease in image quality. Moreover, even if it has reactivity, the compound shown as a specific example in this patent document is bifunctional, and it was difficult to obtain a sufficient crosslinking density. For these reasons, the wear resistance is still not satisfactory.

  Further, there is a problem with respect to forming the surface layer as described above on the photosensitive layer. For example, in the case of laminating a surface layer on the charge transport layer, it is necessary that the charge injection property is good at the interface between the charge transport layer and the surface layer, and charge transport in the surface layer is performed. Although it is necessary for the performance to be comparable to that of the charge transport layer, obtaining a surface layer that satisfies these two characteristics is a major issue. For example, when a compound having a charge transport structure is incorporated into a cross-linked structure, it is said that the charge transport property is lowered by reducing the mobility of the charge transport structure as compared with a non-cross-linked material. As for the injectability between the charge transport layer and the surface layer, it is necessary to adjust the ionization potential of the compound having the charge transport structure contained in each charge transport layer, but before and after the crosslinking of the compound having the charge transport structure. Since the ionization potential of may not be equivalent, care must be taken in material design.

Although a technique for crosslinking with a polycarbonate resin or a charge transport material by adding a phenol derivative in the charge transport layer as in the present invention has not been disclosed at present, an electrophotography in which a surface layer is provided on the charge transport layer. A technique of applying a phenol derivative to the surface layer of a photoreceptor is disclosed in Patent Document 13. In this patent document, a high hardness surface layer is applied to an electrophotographic photoreceptor for the purpose of improving wear durability, and the object can be achieved by using a phenol derivative and a charge transport material for the surface layer. Are listed. However, even in the technique described in the patent document, the above-mentioned problems peculiar to the surface layer remain, and care must be taken in selecting the material. Moreover, it is known that the phenol derivative used by this patent document is a crosslinking mechanism by a dehydration reaction, and there is a concern about the influence on the carbonate resin used in the charge transport layer in which the surface layer is laminated.
Thus, there are still many problems with the means for improving the mechanical durability, and the present situation is that further studies are being carried out.

JP 2002-139659 A JP 2001-125286 A JP 2001-324857 A JP 2003-98708 A JP-A-5-181299 JP 2002-6526 A JP 2002-82465 A JP 2000-284514 A JP 2000-284515 A JP 2001-194413 A Japanese Patent No. 3194392 Japanese Patent No. 3286704 JP 2006-301619 A

  The present invention has been made in view of the above-described problems of the prior art, and in order to improve the wear resistance and scratch resistance of an electrophotographic photoreceptor having a laminated structure, the charge transport layer itself located on the surface is crosslinked. By adopting a structure, it is possible to form a high-quality image over a long period of time without causing defects related to the output image quality of the image forming apparatus, such as wear and scratches due to repeated use of the photoconductor, and without causing uneven image density It is an object of the present invention to provide an electrophotographic photosensitive member that can be used.

  As a result of intensive studies to achieve the above object, the present inventors have found that in an electrophotographic photoreceptor having at least a charge generation layer and a charge transport layer in this order on a conductive support, the charge transport layer has at least a methylol group. It is formed using a coating liquid for a charge transport layer containing a phenol derivative having a polycarbonate resin and a charge transport substance, and further, by heating after layer formation, by crosslinking at least two components of the constituent components, It has been found that the mechanical strength of the charge transport layer of the electrophotographic photoreceptor can be greatly improved, and an electrophotographic photoreceptor excellent in wear durability can be formed without providing a surface layer. Thereby, an electrophotographic photosensitive member capable of forming a high-quality image over a long period of time can be provided.

That is, the present invention is as follows.
(1) In an electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, the charge transport layer contains at least a phenol derivative having a methylol group, a polycarbonate resin, and a charge transport material. It is formed using a coating liquid for charge transport layer, and is formed by crosslinking at least two components among the components of the phenol derivative having a methylol group, the polycarbonate resin, and the charge transport material by heating. An electrophotographic photoreceptor.
According to the present invention, an electrophotographic photoreceptor having mechanical durability can be formed without providing a surface layer on the charge transport layer, and an image forming apparatus such as wear and scratches caused by repeated use of the photoreceptor. There is provided an electrophotographic photosensitive member capable of forming a high-quality image over a long period of time without causing defects related to the output image quality.

(2) In the above (1), the content of the phenol derivative having a methylol group in the charge transport layer application working solution is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the polycarbonate resin. The electrophotographic photosensitive member described.
(3) The electrophotographic photosensitive member according to (1) or (2) above, wherein the polycarbonate resin has a weight average molecular weight (Mw) of 60,000 or more.
According to the present invention, an electrophotographic photoreceptor having mechanical durability can be efficiently formed by using the material and the composition ratio in the charge transport layer, and wear and scratches caused by repeated use of the photoreceptor. There is provided an electrophotographic photosensitive member capable of forming a high-quality image over a long period of time without causing defects related to the output image quality of the image forming apparatus.

(4) The electrophotographic photosensitive member according to any one of (1) to (3), wherein the charge transporting portion of the charge transporting material has a triarylamine structure.
According to the present invention, it is possible to form a charge transport layer excellent in charge transportability, and by using in combination with the technique described in any one of the above (1) to (3), excellent wear durability and It has been found that an electrophotographic photosensitive member that exhibits electrophotographic characteristics over a long period of time can be formed.

(5) The electrophotographic photosensitive member according to any one of (1) to (4), wherein the charge transport material has a hydroxyl group.
According to the present invention, by using a charge transport material having a hydroxyl group as a charge transport material, it is possible to efficiently form an electrophotographic photoreceptor having mechanical durability, such as wear and scratches due to repeated use of the photoreceptor. There is provided an electrophotographic photosensitive member capable of forming a high-quality image over a long period of time without causing defects related to the output image quality of the image forming apparatus.

(6) The electrophotographic photosensitive member according to any one of (1) to (5), wherein the elastic power of the charge transport layer is 40% or more.
According to the present invention, the charge transporting layer exhibiting the mechanical characteristics does not cause defects related to the output image quality of the image forming apparatus, such as wear and scratches due to repeated use of the photoreceptor, and provides a high quality image over a long period An electrophotographic photosensitive member capable of forming the film is provided.

(7) The electrophotographic photosensitive member according to any one of (1) to (6), wherein a heating temperature at the time of heating is 120 ° C. or higher and 160 ° C. or lower.
According to the present invention, it is possible to sufficiently crosslink the phenol derivative having a methylol group described in the present invention, and an electrophotographic photoreceptor having a charge transport layer having excellent wear durability can be obtained. . As a result, an electrophotographic photoreceptor capable of forming a high-quality image over a long period of time without causing defects related to the output image quality of the image forming apparatus such as wear and scratches due to repeated use of the photoreceptor is provided.

(8) A charging process for charging at least the electrophotographic photosensitive member using the electrophotographic photosensitive member according to any one of (1) to (7), and a surface of the electrophotographic photosensitive member charged by the charging process. A latent image forming process for forming an electrostatic latent image, a developing process for attaching toner to the electrostatic latent image formed by the latent image forming process, and a transfer for transferring the toner image formed by the developing process to a transfer target An image forming method comprising repeatedly performing a process and a cleaning process for removing toner remaining on the surface of the electrophotographic photosensitive member from the surface of the electrophotographic photosensitive member after transfer.

(9) The electrophotographic photosensitive member according to any one of (1) to (7), a charger for charging at least the electrophotographic photosensitive member, and the surface of the electrophotographic photosensitive member charged by the charger. A latent image forming device that forms a latent image, a developing device that attaches toner to the electrostatic latent image formed by the latent image forming device, and a transfer device that transfers the toner image formed by the developing device to a transfer medium. An image forming apparatus comprising: a cleaning device that removes toner remaining on the surface of the electrophotographic photosensitive member after transfer from the surface of the electrophotographic photosensitive member.

(10) to (7) The electrophotographic photosensitive member according to any one of the above, a charger for charging at least the electrophotographic photosensitive member, and forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charger. A latent image forming device, a developing device for attaching toner to the electrostatic latent image formed by the latent image forming device, a transfer device for transferring the toner image formed by the developing device to a transfer target, and an electron after transfer It has one means selected from the group consisting of a cleaning device for removing toner remaining on the surface of the photographic photoreceptor from the surface of the electrophotographic photoreceptor, and is detachable from the main body of the image forming apparatus. Process cartridge for image forming apparatus.

  According to the present invention, an electrophotographic photoreceptor having mechanical durability can be formed without providing a surface layer on the charge transport layer, and an image forming apparatus such as wear and scratches caused by repeated use of the photoreceptor. There is provided an electrophotographic photosensitive member capable of forming a high-quality image over a long period of time without causing defects related to the output image quality of the image and preventing unevenness in image density.

<Configuration of electrophotographic photosensitive member>
The electrophotographic photosensitive member will be described in detail below. The electrophotographic photoreceptor of the present invention is characterized by having at least a charge generation layer and a charge transport layer on a conductive support.
In this layer configuration, since the charge generation function and the charge transport function are independent layers, it is relatively easy to optimize each layer so that the respective functions can be maximized. Normally, the stacking order is not particularly limited, but many charge generating materials have poor chemical stability and are exposed to acid gases such as discharge products around the charger in the electrophotographic imaging process. It causes a decrease in charge generation efficiency. For this reason, it is preferable to laminate a charge transport layer on the charge generation layer. In addition, when the crosslinkable charge transport layer as described in the present invention is applied to an electrophotographic photosensitive member, an electrical hazard or toner applied to the electrophotographic photosensitive member from a charger or the like described later can be applied to the electrophotographic photosensitive member. It is preferable to dispose it so as to face a mechanical hazard applied from a cleaning member or the like to be removed from the photoreceptor, that is, dispose it farthest from the conductive support.

<Regarding the charge transport layer>
The charge transport layer is a layer having a charge transport function, and is a layer mainly composed of at least a charge transport material and a binder resin. The present invention is characterized by containing a phenol derivative having a methylol group, which will be described below, in addition to the above components.

<Regarding phenol derivatives>
The phenol derivative having a methylol group that can be used in the present invention is not particularly limited as long as it has at least one methylol group in the molecule. For example, a phenol derivative is reacted with formaldehyde to form a methylol. It can be obtained. Specifically, for example, monomethylol compound of phenolic monomer, dimethylol compound of phenolic monomer, trimethylol compound of phenolic monomer, monomethylol compound of phenolic dimer, dimethylol compound of phenolic dimer, trimethylol of phenolic dimer A methylol compound, a tetramethylol compound of a phenol dimer, a methylol compound of a trisphenol, or the like is used.

  More specifically, monomethylol compounds of phenolic monomers include 4-hydroxymethyl-2,5-dimethylphenol, 2-cyclohexyl-4-hydroxymethyl-5-methylphenol, 2-t-butyl-4- Hydroxymethyl-5-methylphenol, 4-hydroxymethyl-5-methyl-2-isopropylphenol and the like, and dimethylol compounds of phenolic monomers include 2,6-dihydroxymethyl-4-methylphenol, 2,4 -Dihydroxymethyl-6-methylphenol, 2,6-dihydroxymethyl-3,4-dimethylphenol, 4,6-dihydroxymethyl-2,3-dimethylphenol, 4-t-butyl-2,6-dihydroxymethylphenol 4-cyclohexyl-2,6-dihydride Xylmethylphenol, 2-cyclohexyl-4,6-dihydroxymethylphenol, 2,6-dihydroxymethyl-4-ethylphenol, 4,6-dihydroxymethyl-2-ethylphenol, 4,6-dihydroxymethyl-2-isopropyl Examples thereof include phenol and 6-cyclohexyl-2,4-dihydroxymethyl-3-methylphenol. Examples of the trimethylol compound as a phenolic monomer include 2,4,6-trihydroxymethylphenol.

  Examples of monomethylol compounds of phenolic dimers include 2,2′-dihydroxy-3-hydroxymethyl-3,5,5′-trimethyldiphenylmethane, 4,4′-dihydroxy-5-hydroxymethyl-3,3 ′. , 5-trimethyldiphenylmethane and the like, and dimethylol compounds of phenolic dimers include bis (2-hydroxy-3-hydroxymethyl-5-methylphenol) methane, bis (4-hydroxy-3-hydroxymethyl-5- Methylphenol) methane, bis (4-hydroxy-3-hydroxymethyl-2,5-dimethylphenol) methane, bis (4-hydroxy-5-hydroxymethyl-2,3-dimethylphenol) methane, bis (2-hydroxy) -3-hydroxymethyl-4,5-dimethylphenol And the like, and examples of the tetramethylol compound of a phenolic dimer include 2,2-bis (4-hydroxy-3,5-dihydroxymethylphenol) methane, 2,2-bis (4-hydroxy-3, Examples thereof include 5-dihydroxymethylphenol) propane.

  These phenol derivatives having a methylol group may be used alone or in combination of two or more. Furthermore, a phenol derivative selected from monomers, dimers, oligomers and the like may be selected according to the purpose.

<Binder resin>
Next, the polycarbonate resin described in the present invention will be described.
The polycarbonate resin used in the present invention is a compound having a carbonate group (—O— (C═O) —O—), and is a charge transport layer coating solution comprising at least a phenol derivative, a polycarbonate resin and a charge transport material. There is no particular limitation as long as the charge transport layer can be formed by using. In addition, the molecular weight of the polycarbonate resin may be appropriately selected from the structure of the polycarbonate resin, but if the molecular weight is too small, the viscosity of the coating solution used to form the charge transport layer becomes small, making it difficult to increase the film thickness. . On the other hand, if the molecular weight is too large, the viscosity of the coating solution used to form the charge transport layer becomes too large, or if a highly crystalline polycarbonate resin is used, the pot may be deposited due to precipitation of the polycarbonate resin. Since life becomes short, it is not preferable. The molecular weight of the polycarbonate resin is preferably 60000 or more and 250,000 or less, more preferably 80000 or more and 200000 or less, as the weight average molecular weight (Mw).

  Further, another resin may be used in combination with the polycarbonate resin for the purpose of assisting the charge transport function and enhancing the mechanical strength in the charge transport layer. For example, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, Heat of polyarylate resin, phenoxy resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, alkyd resin, etc. A plastic or thermosetting resin is mentioned. In addition, as a binder resin, a polymer charge transport material having a charge transport function, for example, a polycarbonate resin, polyester, polyurethane, polyether having an arylamine skeleton, a benzidine skeleton, a hydrazone skeleton, a carbazole skeleton, a stilbene skeleton, a pyrazoline skeleton, etc. Polymer materials such as polysiloxane and acrylic resin, polymer materials having a polysilane skeleton, and the like can be used and are useful.

<Regarding non-crosslinked charge transport materials>
Next, the charge transport material will be described.
Examples of the charge transport material include a hole transport material and an electron transport material.
Examples of the electron transporting material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more.

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

<For cross-linked charge transport materials>
Moreover, you may provide the functional group which can be bridge | crosslinked with a phenol derivative as a charge transport material used for a charge transport layer. Examples of the functional group include functional groups such as a hydroxyl group, an alkoxysilyl group, an epoxy group, and a carboxyl group, and a hydroxyl group is preferable.

（式中、Ｙは少なくとも１つの炭素原子に水酸基が結合した置換又は無置換の炭素数１〜６のアルキル基もしくはアルコキシ基、置換又は無置換のアリール基を表し、Ｘは電荷輸送性分子構造を含んでなる１〜４価の炭化水素結合を主とする有機残基を表す。ｎは１〜４の整数を表す。） The charge transport material having a hydroxyl group will be described below.
Examples of the charge transport material having a hydroxyl group include compounds represented by the following general formula (1).

(In the formula, Y represents a substituted or unsubstituted alkyl group or alkoxy group having 1 to 6 carbon atoms in which a hydroxyl group is bonded to at least one carbon atom, or a substituted or unsubstituted aryl group, and X represents a charge transporting molecular structure. Represents an organic residue mainly composed of 1 to 4 valent hydrocarbon bonds comprising n. N represents an integer of 1 to 4.)

Specific examples of the alkyl group for Y in the general formula (1) include an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an isopropyl group, and an isobutyl group.
Moreover, as an alkoxy group in Y of General formula (1), the alkoxy group which has the said C1-C6 substituted or unsubstituted alkyl group is represented, As the specific example, an ethoxy group, a propoxy group, a butoxy group Pentyloxy group, hexyloxy group, isopropoxy group, isobutyloxy group and the like.
Examples of these substituents include halogen atoms, nitro groups, nitrile groups, alkoxy groups such as methoxy groups and ethoxy groups, aryloxy groups such as phenoxy groups, aryl groups such as phenyl groups and naphthyl groups, benzyl groups and phenethyl groups. And an aralkyl group. The number of hydroxyl groups in Y is preferably 1-8.

X in the general formula (1) represents an organic residue mainly composed of a monovalent to tetravalent hydrocarbon bond comprising a molecular structure having electron donating property or electron accepting property, so-called charge transporting property.
As a molecular structure having an electron donating property, there are hole transport compounds such as triphenylamine derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis. -(4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, Etc.

Examples of molecular structures having electron accepting properties include electron transport compounds, such as chloranil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5, 7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene 4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide and the like.
In particular, a hole transport compound containing a nitrogen atom in the molecular structure (for example, a triarylamine structure) has a good charge transport ability and is preferably used.

  Specific examples of the charge transport material having a hydroxyl group are shown in Tables 1 to 4, but are not limited to compounds having these structures.

<Regarding the charge transport layer blending ratio>
In the present invention, the charge transport layer is characterized in that it is a charge transport layer containing at least the binder component, a phenol derivative having a methylol group, and a charge transport material, thereby being excellent in wear durability. It is possible to provide a charge transport layer. In order to effectively obtain a charge transport layer excellent in wear durability, it is necessary to appropriately select these blending ratios according to the materials to be selected.

  Since the phenol derivative becomes the core of the reaction in the present invention as described later, the blending ratio is important. According to the present inventors, a result suggesting that excellent wear durability is exhibited by the interaction with the polycarbonate resin is obtained, and therefore the blending ratio with respect to the polycarbonate resin is considered important. The blending ratio of the phenol derivative is preferably 10 to 100 parts by weight, more preferably 30 to 70 parts by weight with respect to 100 parts by weight of the polycarbonate resin. When the amount is less than 10 parts by weight, the cross-linking network in the charge transport layer becomes insufficient, so that sufficient wear durability cannot be obtained even through a heating step described later. When the amount exceeds 100 parts by weight, the cross-linked network in the charge transport layer is sufficiently formed, but excess phenol derivatives form a relatively large cross-linked domain in the charge transport layer. Since the amount of the charge transport material is extremely small compared with other portions, the charge transport property is impaired, and depending on the domain size, there is a risk of inducing image defects due to formation of relatively large irregularities, which is not preferable.

  As described above, the charge transport material is a component that contributes to the delivery of charges in the charge transport layer, and is important because the mixing ratio in the charge transport layer affects the charge transport property. The mixing ratio of the charge transport material is preferably 30 parts by weight to 150 parts by weight, more preferably 50 parts by weight to 140 parts by weight with respect to 100 parts by weight of the total amount of the binder component and the phenol derivative. When the blending ratio of the charge transport material to the binder component and the phenol derivative is less than 30 parts by weight, the charge transport property of the charge transport layer becomes insufficient, and image defects are likely to occur due to a decrease in sensitivity and an increase in residual potential. It is not preferable. On the other hand, when the amount exceeds 150 parts by weight, wear resistance, which is a feature of the present invention, may be poor when a non-crosslinked charge transport material is used. In addition, when a charge transporting material having a cross-linking functional group is applied, insufficient wear durability is unlikely to occur. However, depending on the charge transporting material used, an oxidizing material (NOX or ozone) generated from a charger or the like described later may be used. This is not preferable because the chargeability of the charge transport layer may be lowered.

<Film preparation method>
The coating liquid used for coating is preferably prepared by dissolving in a good solvent because many components are solid at room temperature. The solvent is not particularly limited as long as it can dissolve the polycarbonate resin and the charge transport material to form a homogeneous coating solution. For example, alcohols such as methanol, ethanol, propanol, and butanol, acetone, methyl ethyl ketone, methyl isobutyl Ketones such as ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran, dioxane and propyl ether, halogens such as dichloromethane, dichloroethane, trichloroethane and chlorobenzene, and aromatics such as benzene, toluene and xylene And cellosolves such as methyl cellosolve, ethyl cellosolve, cellosolve acetate and the like. These solvents 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 for the charge transport layer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 0 to 100 parts by weight of the binder resin. About 30 parts by weight 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.

The coating method used for forming the charge generation 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 surface layer thickness, and the like. Examples include dip coating, spray coating, bead coating, ring coating, and the like.
The thickness of the charge transport layer is preferably 30 μm or less, more preferably 25 μm or less, from the viewpoint of resolution and responsiveness. The lower limit is different depending on the system to be used (particularly charging potential), but is preferably 5 μm or more from the viewpoint of charging property and wear durability.

<Regarding heating>
By heating the charge transport layer formed by the above-described method to crosslink at least two kinds of charge transport layer constituent components containing a phenol derivative, a charge transport layer having excellent wear durability can be obtained. The heating temperature is preferably 120 ° C. or higher and 160 ° C. or lower. Depending on the phenol derivative and polycarbonate resin used, if the heating temperature is lower than 120 ° C, crosslinking may be insufficient, or the solvent used during film formation may remain in the film, resulting in desired mechanical properties. In many cases, the photoreceptor characteristics cannot be obtained, which is not preferable. On the other hand, when the heating temperature exceeds 160 ° C., alteration of the layers other than the charge transport layer such as the charge generation layer described in the present invention may occur.
Here, when the phenol derivative and the electrophotographic photosensitive member component are not cross-linked by appropriate means, a part of the methylol group possessed by the phenol derivative becomes an oxide such as a formyl group in the atmosphere. This is not preferable because it may cause a decrease in the amount of water. Also, when the phenol derivative has a low molecular weight, the phenol derivative plays a role as a plasticizer in the charge transport layer, thereby reducing the viscosity of the charge transport layer and bleeding out on the surface of the electrophotographic photoreceptor over time. Because it causes, it is also not preferable.

  As a crosslinking means, it is preferable to heat in a normal pressure atmosphere after forming the charge transport layer with the charge transport layer coating solution. Although the reason why a tough film can be obtained by heating after the film formation has not been clarified at present, the present inventor considers that the reason is as follows. That is, the phenol derivative contained in the charge transport layer undergoes a condensation reaction by post-heating, and starts crosslinking with each other. At the same time, the polycarbonate resin is hydrolyzed by the water formed in this reaction. The unpaired electrons formed during the hydrolysis react with the methylol group of the phenol derivative, and the polycarbonate resin itself is incorporated into the crosslinked structure of the phenol derivative, resulting in the formation of a charge transport layer having a three-dimensional crosslinked structure. . If this mechanism is valid, the condensation reaction of the phenol derivative triggers the reaction of the entire bulk, resulting in the formation of ether linkages in the bulk. When the above-mentioned heating process is inappropriate or when the phenol derivative having a methylol group to be applied is inappropriate, the present inventors reduce the amount of ether bond produced by the ATR method of FT-IR, which will be described later. Data supporting the above-described estimation mechanism, such as insufficient mechanical properties of the film such as elastic power (that is, insufficient crosslinking), has been obtained.

<Mechanical properties of charge transport layer>
In order for the charge transport layer prepared by the method described in the present invention to have sufficient wear durability in the present material system, the elastic power is preferably 40% or more. The elastic power is measured by a load / unload test of a microhardness meter using a diamond indenter. Specifically, unloading under a predetermined condition with respect to the maximum deformation work (A: work of plastic deformation + work of elastic deformation) when a diamond indenter is loaded on a measured object with a predetermined pressure and predetermined conditions It is represented by the ratio (B / A) of the restoration amount (B: work amount of elastic deformation) of the measured object at the time.
Since the hardness of the object to be measured can be measured simultaneously with the measurement of the elastic power, it can be used as a representative value of the mechanical characteristics of the object to be measured together with the elastic power.

This elastic power can be measured by any apparatus that can simultaneously measure the indenter movement and the indenter load when pressing the diamond indenter against the object to be measured. Examples of those capable of measuring this characteristic include Fischer scope H-100 commercially available from Fisher Instruments and dynamic micro hardness tester DUH-211 commercially available from SHIMAZU.
Although it depends on the measurement conditions of the elastic power, since the measurement is susceptible to the influence of the lower layer (conductive support and charge generation layer in the present invention), the measured object (in the present invention) The film thickness of the charge transport layer) should be sufficiently thick. Specifically, the amount of displacement of the diamond indenter in the measurement of the elastic power is preferably 1/6 or less, more preferably 1/10 or less of the film thickness of the measured object.
In the present invention, the above-described Fischer Instruments H-100 was used to measure the elastic power. The measurement conditions are shown below.

<Elastic power measurement conditions>
・ Measuring device: H-100 manufactured by Fischerscope
Measurement mode: dF / dt = const
・ Maximum load: 9.8mmN
・ Loading / unloading time: 30sec each
・ Creep time: 5 sec
In Examples and Comparative Examples described later, the elastic power of the charge transport layer was measured using the elastic power measuring device described above for the electrophotographic photosensitive members of Examples and Comparative Examples.

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

  The binder resin used as necessary for the charge generation layer is polyamide, polyurethane, epoxy resin, polyketone, polycarbonate resin, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole. , Polyacrylamide, 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. These binder resins can be used alone or as a mixture of two or more. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material. The binder resin may be added before or after dispersion.

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

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

These undercoat layers can be formed using an appropriate solvent and a coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, 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.

<Other additives>
In the present invention, in order to improve the environmental resistance, a photosensitive layer (at least a charge generation layer or a charge transport layer in the case of a laminated structure) An antioxidant can be added to each layer such as a 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) butyl Rick acid] cricol 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 this invention is 0.01-10 weight part with respect to the total weight of the layer to add.

《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, the conductive support dispersed in an appropriate binder resin on the support can 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 resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, Thermoplastic, thermally crosslinkable resin, or photocrosslinkable resin such as melamine resin, urethane resin, phenol resin, and alkyd resin can be used. 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.

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

<< Configuration of image forming apparatus >>
Next, the image forming apparatus and the process cartridge for 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 photoconductor having the cross-linked charge transport layer of the present invention. For example, at least after the photoconductor is charged, exposed to an image, and developed, the image is transferred to an image carrier (transfer paper). It consists of a process of transferring a toner image, fixing, and cleaning the surface of the photoreceptor.
In some cases, an image forming apparatus that directly transfers an electrostatic latent image to a transfer member and develops it does not necessarily have the above-described process arranged on a photosensitive member.

FIG. 1 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. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.

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

Next, a separation charger (11) and a separation claw (12) are used as means for separating the transfer body (9) from the photoreceptor (1). As other separation means, electrostatic adsorption induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like are used. As the separation charger (11), the charging means can be used.
Next, a fur brush (14) and a cleaning blade (15) are used to clean the toner remaining on the photoreceptor after transfer. Further, a pre-cleaning charger (13) may be used in order to perform cleaning more efficiently. Other cleaning means include a web method, a magnet brush method, and the like, but each may be used alone or in combination.

Next, 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 addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.
The present invention is an image forming method and an image forming apparatus using the electrophotographic photoreceptor according to the present invention for such image forming means.

The image forming means may be fixedly incorporated in a copying apparatus, facsimile, or printer, but may be incorporated in these apparatuses in the form of a process cartridge and detachable. An example of the process cartridge is shown in FIG.
The process cartridge for 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 process by the apparatus illustrated in FIG. 2, 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. Be 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 in detail, this invention is not limited to a following example. In addition, a part shows a weight part.

<Example 1>
By coating and drying an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution in the following order on a φ30 mm aluminum cylinder in sequence, an undercoat layer of 3.5 μm A 0.2 μm charge generation layer and a 20 μm charge transport layer were formed.
[Coating liquid for undercoat layer]
・ Alkyd resin 6 parts (Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink and Chemicals)
・ Titanium oxide 40 parts ・ Methyl ethyl ketone 50 parts [Coating liquid for charge generation layer]
・ Bisazo pigment of the following structural formula 2.5 parts ・ Polyvinyl butyral (XYHL, manufactured by UCC) 0.5 part ・ Cyclohexanone 200 parts ・ Methyl ethyl ketone 80 parts

次に、得られた電子写真感光体を常圧雰囲気下で１３５℃３０分間の加熱を行うことによって、本発明の電子写真感光体を得た。 [Coating liquid for charge transport layer]
-Bisphenol Z modified polycarbonate 10 parts (Panlite TS-2050, manufactured by Teijin Chemicals Ltd. (Mw: 160000))
-Charge transport material of the following structural formula: 7 parts-26DMPC (phenol derivative having a methylol group): 4 parts (Chemical name: 2,6-Dihydroxymethyl-4-methylphenol, manufactured by Asahi Organic Materials Co., Ltd. Tg: 131 ° C)
Tetrahydrofuran 100 parts 1% silicone oil tetrahydrofuran solution 1 part (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.)

Next, the obtained electrophotographic photoreceptor was heated at 135 ° C. for 30 minutes under an atmospheric pressure to obtain the electrophotographic photoreceptor of the present invention.

<Example 2>
An electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that the phenol derivative of Example 1 was changed to the following.
DM-BIPC-F (phenol derivative having a methylol group)
(Chemical name: Bis (2-hydroxy-3-hydroxymethyl-5-methylphenyl) methane, manufactured by Asahi Organic Chemicals Co., Ltd. Tg: 146 ° C)
<Example 3>
An electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that the phenol derivative of Example 1 was changed to the following.
DM-BIOC-F (phenol derivative having a methylol group)
(Chemical name: Bis (4-hydroxy-3-hydroxymethyl-5-methylphenyl) methane Asahi Organic Materials Co., Ltd. Tg: 157 ° C)

<Examples 4 to 6>
An electrophotographic photosensitive member was obtained in the same manner as in Examples 1 to 3 except that the charge transport material used in the charge transport layers of Examples 1 to 3 was changed to the Exemplified Compound D2-2.
<Examples 7 to 9>
An electrophotographic photosensitive member was obtained in the same manner as in Examples 1 to 3 except that the charge transport material used in the charge transport layers of Examples 1 to 3 was changed to the exemplified compound D3-2.

<Examples 10 to 12>
Electrophotographic images as in Examples 1 to 3 except that the binder component used in the charge transport layers of Examples 1 to 3 is changed to bisphenol A-modified polycarbonate (Panlite C1400: manufactured by Teijin Chemicals Ltd. (Mw: 86000)). A photoreceptor was obtained.
<Example 13>
An electrophotographic photosensitive member was obtained in the same manner as in Example 4 except that the amount of the phenol derivative having a methylol group to be blended in the charge transport layer coating solution of Example 4 was 0.5 part.
<Example 14>
An electrophotographic photoreceptor was obtained in the same manner as in Example 4 except that the amount of the phenol derivative having a methylol group blended in the charge transport layer coating solution of Example 4 was 1.5 parts.

<Example 15>
An electrophotographic photosensitive member was obtained in the same manner as in Example 4 except that the amount of the phenol derivative having a methylol group blended in the charge transport layer coating solution of Example 4 was 8 parts.
<Example 16>
An electrophotographic photoreceptor was obtained in the same manner as in Example 4 except that the amount of the phenol derivative having a methylol group to be blended in the charge transport layer coating solution of Example 4 was 12 parts.

<Example 17>
An electrophotographic photosensitive member was obtained in the same manner as in Example 4 except that a bisphenol Z-modified polycarbonate having a molecular weight (Mw) of 13500 prepared in the charge transport layer coating solution of Example 4 was prepared and used.
<Example 18>
An electrophotographic photosensitive member was obtained in the same manner as in Example 4 except that a molecular weight (Mw) of the bisphenol Z-modified polycarbonate to be blended in the charge transport layer coating solution of Example 4 was 88000, and that it was used.

<Example 19>
An electrophotographic photosensitive member was obtained in the same manner as in Example 4 except that the heating temperature in the heating step of Example 4 was 100 ° C.
<Example 20>
An electrophotographic photosensitive member was obtained in the same manner as in Example 4 except that the heating temperature in the heating step of Example 4 was changed to 150 ° C.
<Example 21>
An electrophotographic photosensitive member was obtained in the same manner as in Example 4 except that the heating temperature in the heating step of Example 4 was 170 ° C.

<Comparative Example 1>
An electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that the charge transport layer coating solution of Example 1 was a charge transport layer coating solution not containing a phenol derivative having a methylol group.
<Comparative Example 2>
An electrophotographic photosensitive member was obtained in the same manner as in Example 4 except that the charge transport layer coating solution of Example 4 was a charge transport layer coating solution not containing a phenol derivative having a methylol group.
<Comparative Example 3>
An electrophotographic photosensitive member was obtained in the same manner as in Example 7 except that the charge transport layer coating solution of Example 7 was a charge transport layer coating solution not containing a phenol derivative having a methylol group.

<Comparative Examples 4-5>
An electrophotographic photosensitive member was obtained in the same manner as in Examples 1 and 4 except that the phenol derivatives of Examples 1 and 4 were changed to the following.
・ Phenolic resin (Purified Phenol / Sigma Aldrich)
<Comparative Example 6>
An electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that the charge transport layer coating solution of Example 1 was a charge transport layer coating solution containing no charge transport material.
<Comparative Example 7>
An electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that the charge transporting layer coating solution of Example 1 was a charge transporting layer coating solution not containing bisphenol Z-modified polycarbonate.

<Comparative Examples 8 and 9>
An electrophotographic photoreceptor was obtained in the same manner as in Examples 1 and 4 except that the bisphenol Z-modified polycarbonate of Examples 1 and 4 was changed to the following.
・ Polystyrene (Average Mw ~ 200,000 / Sigma Aldrich)
<Comparative Examples 10 and 11>
The electrophotographic photoreceptors of Comparative Examples 10 and 11 were obtained in the same manner as in Examples 1 and 4 except that the heating step was not performed in Examples 1 and 4.

[Appearance of electrophotographic photoreceptor]
Table 5 shows the appearances of the electrophotographic photoreceptors obtained in Examples 1 to 21 and Comparative Examples 1 to 11.

  For Examples 1 to 3 using a charge transporting substance having no cross-linking reactive group, the charge transporting layer was slightly whitish, but there were no other appearance defects and the electrons maintained a good surface state. It was a photographic photoreceptor. Further, for the electrophotographic photoreceptors obtained in Examples 4 to 14, 18, 20 to 21, a very transparent charge transport layer was obtained, and the surface property was also good. Several small white domains were confirmed for the electrophotographic photosensitive member obtained in Example 15, but it was not a large defect visually and the surface property was not impaired. About the electrophotographic photosensitive member obtained in Example 16, several white domains of about φ2 mm were formed on the whole, and slightly convex portions were formed at the portions. In addition, for the electrophotographic photoreceptor obtained in Example 19, the charge transport layer was slightly whitish, but the whiteness was light compared to Examples 1 to 3, and other appearance defects were I couldn't see it. The electrophotographic photosensitive member obtained in Example 17 showed a streak pattern in the cylindrical direction of the photosensitive member. This is because the molecular weight of the polycarbonate resin used when forming this electrophotographic photosensitive member is too low, the viscosity of the coating solution for the charge transport layer is not appropriate, and a large amount of dripping occurs during coating. It has been done. Moreover, only this electrophotographic photoreceptor had a film thickness of 12 μm (other photoreceptors were 20 μm).

  In Comparative Examples 1 to 3 and 6, no abnormality in the appearance of the charge transport layer was observed, and good transparency and smoothness were obtained. With respect to Comparative Examples 4 to 5 using a phenol derivative having no methylol group, a phenomenon that the charge transport layer was entirely whitened occurred. Regarding Comparative Example 7, a film could not be formed by the coating method described in this Comparative Example, and as a result, the subsequent elastic power evaluation and the effect verification by running were abandoned. The electrophotographic photoreceptors obtained in Comparative Examples 8 to 9 using polystyrene as the binder and the electrophotographic photoreceptors in Comparative Examples 10 to 11 that were not subjected to the post-heating step were charged in the same manner as in Comparative Examples 4 to 5. The phenomenon that the transport layer was entirely whitened occurred.

[Elastic power of electrophotographic photosensitive member]
The electrophotographic photosensitive members obtained in Examples 1 to 21 and Comparative Examples 1 to 6 and 8 to 11 were evaluated for the elastic work rate of the charge transport layer under the following apparatus and conditions. Table 6 shows the average of five measurements.
<Elastic power measurement conditions>
・ Measuring device: H-100 manufactured by Fischerscope
Measurement mode: dF / dt = const
・ Maximum load: 9.8mmN
・ Loading / unloading time: 30sec each
・ Creep time: 5 sec

  For the electrophotographic photoreceptors shown in Examples 1 to 20, all the charge transport layers had a larger numerical value than that of the comparative example, and it was shown that the effect of improving the mechanical properties by adding the phenol derivative was great. About the effect, as shown in Examples 13-16, it was shown that it is addition amount dependence. Further, from the comparison between Examples 1 and 4 and Comparative Examples 10 to 11, when there is no post-heating, a great difference appears in the appearance and mechanical characteristics of the photoconductor, and the post-heating step at the time of producing the electrophotographic photoconductor Further, depending on the post-heating conditions, the elastic work rate is smaller than that in Example 4 when the post-heating temperature is not appropriate, as shown in Example 19, depending on the post-heating conditions. The importance of post-heating conditions was also shown.

[Verification of effects by running]
The electrophotographic photosensitive members produced in Examples 1 to 21 and Comparative Examples 1 to 6 and 8 to 11 were subjected to running tests of 50,000 sheets and 100,000 sheets, respectively, by the following methods.
-Running test and evaluation method-
As an actual machine, it was set in an IPSiO Color CX9000 remodeled machine manufactured by Ricoh. At this time, the lubricant bar was removed from the process cartridge, and it was modified in advance so as not to supply the lubricant from the outside. Ipsio toner type 9800 was used as the toner, and MyPaper (A4 size) manufactured by NBS Ricoh was used as the paper used in the actual machine test. The photoreceptor surface potential at the start was −700 V, the in-machine potential was evaluated at the end of running 50,000 sheets / 100,000 sheets, and the photoreceptor film thickness at the end of running 100,000 sheets was evaluated. The image used for paper passing was a 5% test chart. Table 7 shows the photoconductor wear amount calculated from the photoconductor film thickness at the end of 100,000 running sheets, and Table 8 shows the post-charge potential and post-exposure potential in the actual machine.

  Compared with Comparative Examples 1 to 3 (no addition of phenol derivative), the electrophotographic photoreceptors of Examples 1 to 12 have less wear on the charge transport layer due to running, and may have an effect of improving mechanical strength due to addition of phenol derivative and heating. Indicated. In addition, the amount of wear is relatively small in Examples 4 to 12 in which the elastic power shown in Table 6 is 40 or more, and can be an index for obtaining an electrophotographic photosensitive member having wear durability. Yes. Further, it is clear from the results of Examples 13 to 16 that there is a correlation between the addition amount of the phenol derivative and the photoreceptor wear amount as well as the elastic power.

  From the test results of Examples 17 to 18, it was shown that the molecular weight of the polycarbonate resin to be used also affects the wear durability. As shown in the results of this example, the wear amount increased when the molecular weight of the polycarbonate resin used was too small. In addition, when post-heating is not performed even when a phenol derivative is added, or when post-heating is insufficient, the mechanical strength is not improved or becomes insufficient. Comparative Examples 10 to 11 and Example 19 It was shown from the result of -21. This is presumably because the added phenol derivative is not crosslinked in the charge transport layer or is insufficiently crosslinked. It is considered that the electrophotographic photoreceptors obtained in Comparative Examples 10 to 11 and Example 19 are related to whiteness, and the phenol derivatives used in this example have high crystallinity and are crosslinked. This phenomenon seems to be a result of phase separation of phenol derivatives that do not contribute to the reaction in the charge transport layer. Further, interesting findings about the phenol derivatives to be added are shown in the results of Comparative Examples 4 to 5. In other words, even when phenol having no methylol group was added to the electrophotographic photoreceptor, there was no effect in improving the wear durability, and the result was that the photoreceptor wear progressed very quickly. It is shown in Comparative Examples 8 to 9 that when the binder type used in the charge transport layer is polystyrene, no effect is seen in improving wear durability. In Comparative Example 6, since the charge transport layer does not have a charge transport material, the charge transport layer does not have a light attenuation function and cannot be used for running using an actual machine.

  The electrophotographic photoreceptors of Examples 4 to 9 have numerical values that are comparable to both the post-charge potential and the post-exposure potential as compared with the electrophotographic photoreceptors of Comparative Examples 1 to 3. It is shown that the influence by is not large. This tendency is also shown from Examples 10-12. On the other hand, it can be seen that the electrophotographic photoreceptors of Examples 1 to 3 tend to have a higher post-exposure potential than the electrophotographic photoreceptors of Examples 4 to 12. Although the cause of this phenomenon is not yet clear, the present inventors have caused this because some charge transport materials were phase-separated because the charge transport materials were not incorporated during the crosslinking of the polycarbonate resin and the phenol derivative. I think it is a phenomenon. Therefore, it is considered preferable to apply a charge transporting material having a crosslinkable reactive group in order to achieve both wear durability and charge transportability.

  Moreover, it can be seen from the results of Examples 13 to 16 that there is a slight correlation between the addition amount of the phenol derivative used in this example and the post-exposure potential. That is, the post-exposure potential slightly tended to increase as the amount of the phenol derivative in the charge transport layer increased. The reason for this phenomenon is not clear, but the movement of the charge transport group (triarylamine structure in this example) is caused by the fact that the phenol derivative becomes an inhibiting factor for charge transport or the charge transport layer forms a crosslinked structure. Since the degree of freedom is small, it is considered that the charge transportability is lowered or for any reason.

From the results of Example 19, even if a phenol derivative is added to the charge transport layer, it is considered that the crosslinking is insufficient as described above when the heating is insufficient. Was shown. Although it is not yet clear regarding this reason, it is considered that the phenol derivative which has not been crosslinked is phase-separated and the charge transport property is lowered. This phenomenon indicates that not only the post-exposure potential but also the post-charge potential is at a low level, causing a significant decrease in potential due to running. Moreover, when post-heating temperature was high like Example 21, the tendency for post-exposure potential to become high was seen. This seems to be the result of the undercoat layer and the charge generation layer being affected by post-heating.
From the above, it is shown that by using the electrophotographic photosensitive member production method and the electrophotographic photosensitive member described in the present invention, an electrophotographic photosensitive member having not only wear durability but also excellent electrical characteristics can be obtained. It was.

1 is a schematic diagram illustrating an example of an image forming apparatus on which the electrophotographic photosensitive member of the present invention is mounted. FIG. 2 is a schematic view showing an example of a process cartridge on which the electrophotographic photosensitive member of the present invention is mounted.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charger charger 5 Image exposure part 6 Developing unit 7 Charger before transfer 9 Transfer body 10 Transfer charger 11 Separation charger 12 Separation nail 13 Charger before cleaning 14 Fur brush 15 Cleaning blade 101 Photoconductor 102 Charging means 103 Exposure Means 104 Developing means 105 Transfer body 106 Transfer means 107 Cleaning means

Claims (10)

  An electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are sequentially laminated on a conductive support, wherein the charge transport layer contains at least a phenol derivative having a methylol group, a polycarbonate resin, and a charge transport material. An electrophotographic film formed by using a layer coating solution and having at least two components cross-linked by heating, among the components of the phenol derivative having a methylol group, the polycarbonate resin, and the charge transport material. Photoconductor.   2. The charge transport layer coating solution according to claim 1, wherein the content of the phenol derivative having a methylol group is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the polycarbonate resin. Electrophotographic photoreceptor.   The electrophotographic photosensitive member according to claim 1, wherein the polycarbonate resin has a weight average molecular weight (Mw) of 60,000 or more.   4. The electrophotographic photosensitive member according to claim 1, wherein the charge transporting portion of the charge transport material has a triarylamine structure.   The electrophotographic photosensitive member according to claim 1, wherein the charge transport material has a hydroxyl group.   6. The electrophotographic photosensitive member according to claim 1, wherein the charge transport layer has an elastic power of 40% or more.   The electrophotographic photosensitive member according to claim 1, wherein a heating temperature at the time of heating is 120 ° C. or more and 160 ° C. or less.   A charging process for charging at least the electrophotographic photosensitive member using the electrophotographic photosensitive member according to any one of claims 1 to 7, and forming an electrostatic latent image on the surface of the electrophotographic photosensitive member charged by the charging process. A latent image forming process, a developing process for attaching toner to the electrostatic latent image formed by the latent image forming process, a transfer process for transferring the toner image formed by the developing process to a transfer target, and an electron after transfer An image forming method comprising repeatedly performing a cleaning process for removing toner remaining on the surface of the photographic photoreceptor from the surface of the electrophotographic photoreceptor.   8. The electrophotographic photosensitive member according to claim 1, a charger for charging at least 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. An image forming unit; a developing unit that attaches toner to the electrostatic latent image formed by the latent image forming unit; a transfer unit that transfers the toner image formed by the developing unit to a transfer target; and an electrophotographic photosensitive member after transfer An image forming apparatus comprising: a cleaning device that removes toner remaining on the surface of the body from the surface of the electrophotographic photosensitive member.   8. The electrophotographic photosensitive member according to claim 1, a charger for charging at least 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. An image forming unit; a developing unit that attaches toner to the electrostatic latent image formed by the latent image forming unit; a transfer unit that transfers the toner image formed by the developing unit to a transfer target; and an electrophotographic photosensitive member after transfer An image forming apparatus comprising one means selected from the group consisting of a cleaning device for removing toner remaining on the surface of the body from the surface of the electrophotographic photosensitive member, wherein the image forming apparatus body is removable. Process cartridge for equipment.

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