JP4420397B2 - Electrophotographic photosensitive member, image forming apparatus, and process cartridge for image forming apparatus - Google Patents

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 and an image forming apparatus for an image forming apparatus using the same. Specifically, the present invention relates to an electrophotographic photoreceptor excellent in image quality and durability stability, and a process cartridge for an image forming apparatus and an image forming apparatus using the same.

  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, the developing device for attaching the toner to the image portion of the electrostatic latent image formed by the latent image forming device, and the transfer means for transferring the toner attached to the image portion to the transfer object. In some cases, a cleaning device is provided to remove 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, in brush cleaning, it is difficult to sufficiently remove the toner because the fine powder toner slips between the fibers. The same applies to magnetic brushes, and in this method, attempts have been made to remove electrostatically by applying an electric field, but this is sufficient to cause a phenomenon such as toner scattered by electrostatic force reattaching to the photoreceptor. 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 photoreceptor, and thus durability against them has been required.
Many research examples have been reported for these problems by improving the hardness of the photoreceptor surface. For example, in Patent Document 1 and Patent Document 2, 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 3 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 4 to 6 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 7 to 9 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 Documents 10 and 11, etc., in order to improve wear resistance and scratch resistance, both the binder and the charge transport material have a monomer having a carbon-carbon double bond, a charge transport material having a carbon-carbon double bond, and A technique using a binder resin has been reported.

  These crosslinkable materials form a tough film by cross-linking molecules with each other. The characteristics of the crosslinkable material depend on the crosslinking conditions (temperature conditions, humidity conditions, etc. for thermosetting resins, light wavelengths, illuminance, light quantity, temperature conditions, humidity conditions, etc. for photocurable resins). Different characteristics can be developed even with the same material.

  In particular, the photo-curing resin is very quick to cure, and by changing the light irradiation conditions depending on the location, it is possible to obtain films with different characteristics even in the same plane. , Easy to express unique characteristics. Therefore, it is also used in industrial applications such as an adhesive tape having a partially different adhesive strength and an etching process used for fine processing. However, in order to constantly express desired characteristics, it is necessary to set and manage manufacturing conditions in detail. In addition, when applying a photocurable resin to a laminate, if the laminate is deteriorated by light, irradiation conditions such as the light emission wavelength of the light source used for curing, the selection of the corresponding initiator, illuminance, exposure dose, etc. Therefore, it is necessary to minimize the influence on the stacked body.

In order to obtain desired properties such as hardness by applying a photocrosslinkable material to the surface layer of the photoreceptor for the purpose of extending the life of the photoreceptor, processing means such as film formation method, film formation conditions, and crosslinking conditions, and processing It is possible to suppress wear and scratches on the surface of the photosensitive member for the long term only by processing the conditions appropriately.
However, since the charge generation material and charge transport material constituting the laminate (charge generation layer, charge transport layer, etc.) are easily damaged by light, the degree of crosslinking of the surface layer and the stability of the charge generation material and charge transport material Tends to be a reciprocal relationship. That is, while the hardness of the surface layer is increased by the polymerization reaction due to light irradiation, there is a concern that the electrical characteristics and stability may be decreased due to the deterioration of the constituent materials of the charge transport layer and the charge generation layer as the laminate. Is done.

  In order to make full use of these contradictory characteristics, it is considered effective to cure the surface layer with a small amount of light irradiation, but a simple reduction in the amount of light irradiation may cause a decrease in surface hardness due to poor curing. In addition, the electrical characteristics, wear resistance, scratch resistance, etc. are reduced due to the migration of low molecular components from the adjacent layers (referring to the photosensitive layer, charge transport layer, charge generation layer, etc. adjacent to the photoreceptor surface layer). Or cause

Furthermore, when curing is insufficient, safety problems such as mutagenicity and skin irritation due to unreacted functional groups arise. As another means, it is conceivable to select a photocrosslinkable material or an initiator having a high reactivity as a material, or to crosslink at a relatively high temperature as a reaction condition. While the resin can be sufficiently cross-linked, defects such as cracks due to excessive shrinkage of the resin are likely to occur. For this reason, there is a concern that the wear durability is lowered and the electrical properties are lowered due to the brittleness of the surface layer.
As described above, when applying the photocrosslinkable resin to the surface layer, there are so many items to be noted that it is very difficult to select the manufacturing conditions. However, the current situation is that the technique for using the photocurable resin has not been studied in detail.

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

  The present invention has been made in view of the above-described problems of the prior art, and in the case of using a photocrosslinkable material to improve the abrasion resistance and scratch resistance of the surface layer of the photoreceptor, poor curing and excessive shrinkage, Without causing physical problems such as migration of low-molecular components contained in adjacent layers, a film with the desired surface hardness is obtained, and the output image quality of the image forming apparatus, such as wear and scratches, due to repeated use of the photoreceptor is improved. It is an object of the present invention to provide an electrophotographic photoreceptor having excellent electrical characteristics by preventing the related defects from occurring and preventing deterioration of the photoreceptor material due to light irradiated to the photoreceptor during production.

As a result of intensive studies to achieve the above object, the present inventors have at least a charge generation layer, a charge transport layer , and a surface layer in this order on the conductive support, and the wear resistance and scratch resistance of the surface layer are improved. In the case of using a photocrosslinkable material for improvement, it is excellent in wear resistance by sufficiently crosslinking the surface layer by adding an ultraviolet absorber in the charge transport layer in the layer structure of the photosensitive layer. It has been found that it is possible to produce a photoconductor that can obtain the characteristics, prevent deterioration of the photoconductor material due to light used for curing the surface layer, and does not cause a decrease in electrical characteristics. According to the above method, it is possible to maximize the characteristics of materials having contradictory properties: charge generation materials and charge transport materials that are easily deteriorated by light, and surface layer constituent materials that require light irradiation for crosslinking. It is. As a result, it is possible to extremely reduce the occurrence of wear and scratches on the surface layer of the photoreceptor even by repeated use, and to prevent the occurrence of defects related to the output image quality of the image forming apparatus by suppressing the deterioration of the electrical characteristics during manufacture. An electrophotographic photoreceptor can be provided.

That is, the configuration of the present invention for solving the above-described problems is as described below.
(1) It has at least a charge generation layer, a charge transport layer , and a surface layer in this order on a conductive support, and the thickness of the charge transport layer is 5 to 30 μm, and the surface layer has at least a charge transport structure In an electrophotographic photosensitive member obtained by crosslinking a mixture containing a trifunctional or higher-functional radical polymerizable monomer having no cation and a monofunctional radical polymerizable compound having a charge transporting structure by light energy irradiation means , and the radical polymerizable compound of monofunctional with charge transport structure is one or more of the compounds represented by the following general formula (3), contains an ultraviolet absorber in the charge transport layer, the ultraviolet amount of absorbent, 0.2 parts by weight to 6 parts by weight based on the binder resin content 10 parts by weight of the charge transport layer, and has a maximum emission intensity of the light source used to crosslink the surface layer An electrophotographic photosensitive member in which the transmittance in the charge transporting layer of the head of the light, characterized in that an amount such that less than 70%.
However, the transmittance is to add an ultraviolet absorber to the binder resin content to form the charge transport layer, which in transmittance obtained by measuring the resin film obtained by depositing a thickness of 5μm is there.
(2) The functional group of a tri- or more functional radical polymerizable monomer having no charge transporting structure used for the surface layer is an acryloyloxy group and / or a methacryloyloxy group. Electrophotographic photoreceptor.

(3) The ratio of the molecular weight to the number of functional groups (molecular weight / number of functional groups) in the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used for the surface layer is 250 or less 1) The electrophotographic photosensitive member according to (2).

Represents. )
(4) The above-mentioned (1), wherein the proportion of the trifunctional or higher-functional radical polymerizable monomer having no charge transport structure used in the surface layer is 30 to 70% by weight with respect to the total amount of the crosslinked surface layer. ) To (3).
(5) The component ratio of the radical polymerizable compound having a monofunctional charge transporting structure used for the surface layer is 30 to 70% by weight based on the total amount of the crosslinked surface layer. (4) The electrophotographic photosensitive member according to (4).
(6) The electrophotographic photosensitive member according to the above (1) to (5) is provided, and at least a charging means for charging the electrophotographic photosensitive member and an electrostatic surface on the surface of the electrophotographic photosensitive member charged by the charging means. An image forming apparatus comprising: a latent image forming unit that forms a latent image; and a developing unit that attaches toner to an image portion of the electrostatic latent image formed by the latent image forming unit. Process cartridge.
(7) The electrophotographic photosensitive member according to the above (1) to (5) is provided, and at least a charging means for charging the electrophotographic photosensitive member, and an electrostatic surface on the surface of the electrophotographic photosensitive member charged by the charging means. Process for image forming apparatus integrally comprising one means selected from a latent image forming means for forming a latent image and a developing means for attaching toner to an image portion of an electrostatic latent image formed by a latent image forming device An image forming apparatus having a cartridge mounted thereon, wherein the process cartridge for the image forming apparatus is detachable.
(8) above (1) to (5) A method for producing an electrophotographic photosensitive member, wherein the amount of the ultraviolet absorber a UV absorber in the charge transport layer is, the binder resin content of the charge transport layer The transmittance of light having a wavelength of 0.2 to 6 parts by weight with respect to 10 parts by weight and having the maximum light emission intensity of the light source used for crosslinking the surface layer is less than 70% in the charge transport layer . And a step of irradiating the surface layer with light energy to crosslink the surface layer.
However, the transmittance is to add an ultraviolet absorber to the binder resin content to form the charge transport layer, the transmittance of the resin film having a thickness of 5μm obtained by deposition.

  As is clear from the above detailed and specific description, according to the present invention, at least a photosensitive layer and a surface layer are sequentially provided on a conductive support, and the surface layer does not have at least a charge transporting structure. An electrophotographic photosensitive member containing a functional polymerizable radical polymerizable monomer and a monofunctional radical polymerizable compound having a charge transporting structure and cured by light energy irradiation means. An ultraviolet absorber is contained in the layer farthest from the support, and the blending amount of the ultraviolet absorber is 0. 0 relative to the binder resin content of the layer farthest from the support. 2 to 6 parts by weight of light having a maximum light emission intensity of a light source used for cross-linking (curing) the surface layer (a layer disposed farthest from the conductive support) Used for The electrophotographic photosensitive member added with an ultraviolet absorber added to the binder component so that the transmittance of the formed 5 μm resin film is less than 70% is poor in curing, excessive shrinkage, and low molecular weight contained in the adjacent layer. Without causing physical problems such as component transfer, obtain a film with the desired surface hardness, and do not cause defects related to the output image quality of the image forming device, such as wear and scratches due to repeated use of the photoreceptor. By preventing deterioration of the photoreceptor material due to light irradiated on the photoreceptor during production, an electrophotographic photoreceptor having excellent electrical characteristics can be provided.

  In order to suppress the occurrence of wear and scratches due to repeated use, it is effective that the mechanical strength represented by the hardness and elastic work rate of the surface of the photoconductor is large. Various methods and materials are used to increase these characteristics. Has been developed. In order to increase the mechanical strength, it is generally known to use a crosslinkable material in which molecules are bonded to each other. The crosslinkable material can express various properties by selecting the functional group structure, molecular structure, number of functional groups, etc., and not only the desired mechanical strength but also the electrical properties required for electrophotographic photoreceptors. Recently, it has been attracting attention as a material for electrophotographic photoreceptors because it allows molecular design that also takes into account the physical characteristics.

  The crosslinkable material can be roughly divided into a heat crosslinkable material, a photocrosslinkable material, and an ionizing radiation crosslinkable material. Thermally crosslinkable materials are characterized in that intermolecular crosslinking gradually proceeds at room temperature or high temperature. Since the film is easily cross-linked by heat after film formation, the production equipment is simple and the influence on the human body and the environment is small, so it is widely used industrially. However, it takes a long time to cure and is easily affected by the manufacturing environment. Furthermore, since the curing time is relatively long and it is necessary to apply heat during that time, there may be a problem that a low molecular weight additive is transferred between the layers.

  The photocrosslinkable material and ionizing radiation crosslinkable material can easily crosslink the material by irradiating the material with predetermined light and ionizing radiation, and a highly crosslinked film can be obtained instantaneously. It is characterized by the fact that phenomena such as environmental dependence and low-molecular-weight material migration that occur when using thermally crosslinkable materials are less likely to occur. Photocrosslinkable materials are widely used in industrial applications because the apparatus configuration used for production is not complicated and the influence on the human body is relatively small. On the other hand, many ionizing radiation-crosslinking materials have complicated production facilities and are expensive, and since the influence of ionizing radiation itself on the human body cannot be denied, there are not many examples used industrially.

  For the above reasons, it is considered effective to use a photocrosslinkable material in order to develop excellent mechanical strength. However, as light used for crosslinking the photocrosslinkable material, short wavelength light having high energy is used. In many cases, a layered structure such as an electrophotographic photosensitive member is used, and it is necessary to consider the influence on other layers. The electrophotographic photosensitive member described in the present invention has a layer structure that is widely used. However, since the charge generation material and the charge transport material are easily deteriorated by light, the photocrosslinkable material is used for the surface layer. Requires special attention. When using low-energy light having a wavelength longer than that of visible light, it can be crosslinked by using a sensitizer such as a dye. However, when using a sensitizer, other characteristics, such as an electrophotographic photoreceptor If so, for example, there are few examples in use because there is a concern about the influence on electrical characteristics.

  In the case of using a material having a reciprocal relationship with respect to the development of characteristics, such as deterioration of the charge generation material and the charge transport material caused by light irradiation necessary for sufficiently crosslinking the surface layer, both It is conceivable to optimize the light irradiation amount so as to satisfy the required value of characteristics. Specifically, by cross-linking the surface layer under the minimum light irradiation conditions for the mechanical strength of the surface layer to satisfy the required value, and further, by setting relatively high as the temperature condition at the time of crosslinking, Measures such as promoting cross-linking are mentioned.

  However, when such a method is used, since the manufacturing margin is small, the cross-linking becomes insufficient due to the difference in material lots and the influence of impurities in the material, and the desired surface properties may not be obtained. When the temperature condition is adjusted to a high temperature range, there is a concern that various characteristics may be deteriorated due to a low molecular weight component such as an additive migrating between layers. In addition, even if the curing conditions are adjusted, deterioration of the charge transport layer and charge generation layer constituent materials is unavoidable, and as a result, the potential of the material initially cannot be fully reflected in the product, It may not be possible to obtain the specifications required for the product.

The present invention has been made to remedy these problems. In an electrophotographic photoreceptor using a photocrosslinkable material as a surface layer, the most preferable layer structure of the photosensitive layer is the conductive support. It is characterized in that an ultraviolet absorber is added in a layer disposed at a distance. Thereby, deterioration of the structural components of the charge transport layer and the charge generation layer can be suppressed, and there is no decrease in electrical characteristics or the like. In addition, it is possible to perform light irradiation necessary for obtaining sufficient crosslinking in the surface layer. As a result, it was found that the surface layer was cured well, there was no wear or scratches due to repeated use, excellent electrical characteristics, and no defects related to the output image quality of the image forming apparatus, and the present invention was completed. It came to do.
The present invention is described in detail below.

<< Configuration of electrophotographic photosensitive member >>
First, the photoconductor used in the present invention will be described.
The photoreceptor of this embodiment is a laminate having at least a photosensitive layer and a surface layer in this order on a conductive support. The photosensitive layer may have a single layer structure or a multilayer structure as long as it has a charge generation function and a charge transport function. In the case of a multilayer structure, the charge generation layer responsible for the charge generation function and the charge responsible for the charge transport function. What is functionally separated into the transport layer (functionally separated laminated structure) is generally used. In the case of adopting a function-separated layered structure, the order of stacking the charge generation layer and the charge transport layer on the conductive support is not particularly specified, but when the charge generation layer is on the surface layer side, it is generated by a charger or the like. In general, the charge generation layer is often laminated on the conductive support side because the charge generation layer is easily deteriorated by the acid gas and it is difficult to apply the charge generation layer without eroding the charge transport layer. .

<About UV absorber>
The ultraviolet absorber that can be used in the present invention is not particularly limited as long as it can effectively absorb ultraviolet rays within the emission wavelength of the light source used for photocrosslinking the surface layer. Representative UV absorbers include, but are not limited to, benzotriazole UV absorbers, benzophenone UV absorbers, salicylate UV absorbers, cyanoacrylate UV absorbers, nickel complex UV absorbers, etc. .

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) -benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) -benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) -benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'- Hydroxy-3 ', 5-di-t-butylphenyl) 5-chlorobenzotriazole, 2- (2'-hydroxy-3', 5'-di-t-butylphenyl) -benzotriazole, 2- (2 ' -Hydroxy-3 ', 5'-di-t-amylphenyl) -benzotriazole, 2- (2'-hydroxy-3', 5'-di-t-butylphenyl) Benzotriazole, 2- {2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydropentalimidamethyl) -5'-methylphenyl} -benzotriazole, 2- (5-methyl 2-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3,5-bisphenyl) benzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2- ( 3-t-butyl-5-methyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, methyl-3- {3-t-butyl- Use 5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl} -propionate-polyethylene glycol, etc. It can be.

  Examples of the benzophenone-based ultraviolet absorber include 2,4-di-hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone. 2-hydroxy-4-n-benzyloxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2,2'-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulphonic Acid, 2,2'-dihydroxy-4,4'-dimethoxy-benzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-benzophenone-5-acid, 4-dodeciloquine 2-hydroxybe Zofenon, 2-hydroxy-4-methoxy-2'-carboxy benzophenone may be used such as 2-hydroxy-4-methoxy-5-sulfobenzophenone.

As the salicylate ultraviolet absorber, for example, 4-t-butylphenyl salicylate, phenyl salicylate, or the like can be used.
As the cyanoacrylate ultraviolet absorber, ethyl-2-cyano-3,3-diphenyl acrylate, 2-ethylhexyl-2-cyano-3,3′-dihydroxyacrylate, or the like can be used.

As the nickel complex ultraviolet absorber, {2,2′-thiobis (4-t-octylbenzophenone)}-n-butylamine-nickel, {2,2′-thiobis (4-t-octylphenolate)} — 2-ethylhexylamine nickel, nickel dibutyldithiocarbamate, {2,2'-thiobis (4-t-octylphenolate)}-n-butylamine-nickel and the like can be used.
In addition, other ultraviolet absorbers such as benzoate and triazine may be used.

  Even among the ultraviolet absorbers, it is preferable that the light emission wavelength of the light source used for crosslinking the surface layer is close to the absorption property. Preferably, a light source having excellent absorption characteristics at a wavelength having the maximum light emission intensity of the light source is selected. Specifically, the spectral transmittance of the resin film produced as described below is measured, and the transmittance of the wavelength of light having the maximum emission intensity of the light source used is less than 70%, preferably less than 60%. It is good to select the ultraviolet absorber and determine the blending amount. When the transmittance is 70% or more, the light shielding effect is not sufficient, the constituent material of the photosensitive layer is deteriorated, and the physical properties of the photosensitive member such as electric characteristics are lowered.

<Measurement method of transmittance>
An ultraviolet absorber is added to the binder resin component used in the layer disposed farthest from the conductive support, and a resin film is produced on the transparent substrate so as to have a film thickness of 5 μm. As the base material, those having a low absorption at 300 nm to 700 nm and smooth and having solvent resistance are preferable. For example, a glass plate, a PET film and the like can be mentioned, but there is no particular limitation as long as a substrate suitable for film formation is appropriately selected. The transmittance of the resin layer / transparent substrate thus prepared is measured with a spectrophotometer, and the transmittance of the resin layer is obtained by subtracting the transmittance of the transparent substrate alone.

  The blending ratio of the ultraviolet absorber is preferably in the range of 0.2 to 6 parts by weight, preferably 0.4 to 5 parts by weight, more preferably 0.5 to 0.5 parts by weight with respect to the resin content of the layer to be added. It is good in the range of 4 parts by weight. Addition of less than 0.2 parts by weight has a poor effect of absorbing light for cross-linking the surface layer, and addition of more than 6 parts by weight does not improve the effect. Depending on the agent, the coloring becomes intense and it cannot be used, or the compatibility with the resin is poor and the resin surface bleeds out.

  Moreover, when the exposure amount of the light used when bridge | crosslinking a surface layer is large, you may use a hindered amine light stabilizer (HALS) together. When a hindered amine light stabilizer is added, the hindered amine light stabilizer prevents photodegradation of the ultraviolet absorber, and at the same time, the ultraviolet absorber functions effectively to prevent photodegradation of the hindered amine light stabilizer and its active species. Therefore, even when the exposure amount is large, the photodegradation of the photosensitive layer can be suppressed.

  Examples of the hindered amine light stabilizer include bis- (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis- (N-methyl, 2,2,6,6, -tetramethyl-4- Piperidinyl) sebacate, [dimethyl-1- (2-hydroxyethyl) succinate-1-hydroxy-2,2,6,6, -tetramethylpiperidine] condensate, poly {[6- (1,1,3, 3-tetramethylbutyl) imino] -1,3,5-triazine-2,4-diyl [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6 , 6-tetramethyl-4-piperidyl) iminol]} and the like.

<About the surface layer>
In order to improve the abrasion resistance and scratch resistance of the surface layer of the photoreceptor, means for improving the surface hardness of the surface layer is effective. The factors that determine the hardness of the surface layer of the photoreceptor are determined by the characteristics of the binder resin and the charge transport material. When the charge transport material does not have a crosslinked structure, the hardness is determined by the hardness of the binder resin and the amount of the charge transport material. For example, a high hardness surface layer can be obtained if the binder resin has a high hardness, and a high hardness surface layer can be obtained if the amount of the charge transport material is small.

  However, from the viewpoint of electrical characteristics required for the electrophotographic photoreceptor, it is not preferable that the amount of the charge transport material is reduced. On the other hand, when a charge transport material having a crosslinked structure as disclosed in the present invention is used, the surface hardness is determined by the hardness of the binder resin and the charge transport material. In this case, since the charge transport material also forms a three-dimensional structure, the hardness of the surface layer does not change significantly depending on the blending amount. For this reason, when a crosslinkable charge transport material is used, the material design of the charge transport layer for obtaining a photoconductor having high hardness and excellent electrical characteristics is easy.

  The trifunctional or higher functional radical polymerizable monomer having no charge transporting property in the present invention is a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, for example, condensed polycyclic quinone, diphenoquinone, cyano group or nitro group. A monomer that does not have an electron transport structure such as an electron-withdrawing aromatic ring having a group and has three or more radically polymerizable functional groups. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and is capable of radical polymerization. Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.

(1) Examples of the 1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = _{CH-X 2} -
(In the formula, X ₂ is an arylene group such as a phenylene group or a naphthylene group which may have a substituent, an alkenylene group which may have a substituent, a —CO— group, a —COO— group. , —CON (R ₃₆ ) — group (R ₃₆ represents an alkyl group such as hydrogen, methyl group or ethyl group, an aralkyl group such as benzyl group, naphthylmethyl group or phenethyl group, or an aryl group such as phenyl group or naphthyl group. Or represents an —S— group.)
Specific examples of these substituents include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamide group, and a vinyl thioether group.

(2) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
_{CH 2 = C (Y 4)} -X 3 -
(However, in the formula, Y ₄ represents an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, a naphthyl group, etc. Aryl group, halogen atom, cyano group, nitro group, alkoxy group such as methoxy group or ethoxy group, -COOR ₃₇ group (R ₃₇ is a hydrogen atom, an optionally substituted methyl group, ethyl group, etc. An alkyl group, an optionally substituted benzyl, an aralkyl group such as a phenethyl group, an optionally substituted phenyl group, an aryl group such as a naphthyl group, or -CONR ₃₈ R ₃₉ (R ₃₈ and R ₃₉ is a hydrogen atom, which may have a substituent an alkyl group such as methyl group and ethyl group, which may have a substituent group benzyl group, naphthylmethyl group, or a, such as a phenethyl group, Alkyl group or a substituent a phenyl group which may have a represents an aryl group such as phenyl or naphthyl, which may be the same or different from each other.) Further, X ₃ is the same as X ₂ in the formula 10 Represents a substituent, a single bond, or an alkylene group, provided that at least one of Y ₄ and X ₃ is an oxycarbonyl group, a cyano group, an alkenylene group, and an aromatic ring.)

Specific examples of these substituents include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.
In addition, examples of the substituent further substituted with the substituent for X ₂ , X ₃ , and Y ₄ include, for example, an alkyl group such as a halogen atom, a nitro group, a cyano group, a methyl group, and an ethyl group, a methoxy group, and an ethoxy group. And aryloxy groups such as phenoxy group, aryl groups such as phenyl group and naphthyl group, and aralkyl groups such as benzyl group and phenethyl group.

  Among these radical polymerizable functional groups, acryloyloxy group and methacryloyloxy group are particularly useful, and a compound having three or more acryloyloxy groups is, for example, a compound having three or more hydroxyl groups in the molecule and an acrylic group. It can be obtained by using an acid (salt), an acrylic acid halide, or an acrylic ester to cause an ester reaction or a transesterification reaction. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

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

  Moreover, the component ratio of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure used in the present invention is 20 to 80 parts by weight, preferably 30 to 70 parts by weight with respect to the total amount of the crosslinked surface layer. If the monomer component is less than 20 parts by weight, the three-dimensional cross-linking density of the cross-linked surface layer is small, and a drastic improvement in wear resistance is not achieved as compared with the case where a conventional thermoplastic binder resin is used. On the other hand, if it is 80 parts by weight or more, the content of the charge transporting compound is lowered, and the electrical characteristics are deteriorated. The required wear resistance and electrical characteristics differ depending on the process used, so it cannot be said unconditionally. However, in consideration of the balance of both characteristics, the range of 30 to 70 parts by weight is most preferable.

  The radical polymerizable compound having a charge transporting structure used in the present invention includes a hole transporting structure 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. Examples of the radical polymerizable functional group include those shown in the above radical polymerizable monomer, and acryloyloxy group and methacryloyloxy group are particularly useful.

In addition, as the radical polymerizable compound having a charge transporting structure, a polyfunctional compound having two or more functional groups can be used, but a monofunctional compound is preferable in terms of film quality and electrostatic characteristics. This is because when a bifunctional or higher functional charge transport compound is used, it is fixed in the crosslinked structure by a plurality of bonds. However, since the charge transport structure is very bulky, distortion occurs in the cured resin, resulting in a crosslinked surface layer. The internal stress increases, and it becomes easy to cause cracks and scratches due to carrier adhesion and the like. In the case of a film thickness of 5 μm or less, there is no particular problem, but when a film exceeding 5 μm is formed, the internal stress of the crosslinked surface layer becomes very high and cracks are likely to occur immediately after crosslinking.
In addition, in terms of electrostatic characteristics, when a bifunctional or higher functional charge transporting compound is used, it is fixed in the crosslinked structure with a plurality of bonds, so that the intermediate structure (cation radical) during charge transport is stably maintained. In other words, the sensitivity is lowered due to charge trapping, and the residual potential is likely to increase.

Such deterioration of the electrical characteristics appears as an image such as a decrease in image density and thinning of characters. For this reason, as a radical polymerizable compound having a charge transporting structure, a radical polymerizable compound having a monofunctional charge transporting structure is used, and is fixed in a pendant shape between crosslinks, thereby causing cracks and Scratches are less likely to occur and electrostatic characteristics are easily stabilized.
Further, the triarylamine structure is highly effective as a charge transporting structure. In addition, those having one functional group are preferable, and when a compound represented by the structure of the following general formula (1) or (2) is used, electrical characteristics such as sensitivity and residual potential are favorably sustained. .

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

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

Of the substituents for R ₁ , particularly preferred are a hydrogen atom and a methyl group.
Substituted or unsubstituted Ar ₃ and Ar ₄ are aryl groups, and examples of the aryl group include condensed polycyclic hydrocarbon groups, non-fused cyclic hydrocarbon groups, and heterocyclic groups.
The condensed polycyclic hydrocarbon group preferably has 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group. , S-indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group , A chrycenyl group, a naphthacenyl group, and the like.

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

The aryl group represented by Ar ₃ or Ar ₄ may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group and the like.
(2) Alkyl groups, preferably C ₁ -C _12, especially C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkyl groups, further including fluorine atoms , a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, which may have a phenyl group substituted by an alkoxy group C 1 -C ₄ alkyl or _C 1 -C ₄ Good. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-ethoxyethyl Group, 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group and the like.

(3) An alkoxy group (—OR ₂ ), and R ₂ represents the alkyl group defined in (2). Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group And a trifluoromethoxy group.
(4) An aryloxy group, and examples of the aryl group include a phenyl group and a naphthyl group. It _may contain an alkoxy group having C 1 -C _4, alkyl group, or a halogen atom C 1 -C ₄ as a substituent. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.
(5) Alkyl mercapto group or aryl mercapto group, and specific examples include methylthio group, ethylthio group, phenylthio group, p-methylphenylthio group and the like.
(6)

(In the formula, R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group defined in (2) above, or an aryl group. Examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group. these may form a ring _C 1 -C ₄ alkoxy _groups, C 1 -C a alkyl group or a halogen atom ₄ which may contain as substituents .R ₃ and _{R 4} jointly)
Specifically, amino group, diethylamino group, N-methyl-N-phenylamino group, N, N-diphenylamino group, N, N-di (tolyl) amino group, dibenzylamino group, piperidino group, morpholino group And pyrrolidino group.

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

The arylene group represented by Ar ₁ and Ar ₂ is a divalent group derived from the aryl group represented by Ar ₃ and Ar 4.
X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group.

The substituted or unsubstituted alkylene group is a C ₁ -C ₁₂ , preferably C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkylene group, and these alkylene groups include a fluorine atom, a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, a phenyl group substituted with an alkyl group or a _C 1 -C ₄ alkoxy group C 1 -C ₄ It may be. Specifically, methylene group, ethylene group, n-butylene group, i-propylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxyethylene Group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group and the like.
The substituted or unsubstituted cycloalkylene _group, a cyclic alkylene group of C 5 -C _7, these are the cyclic alkylene group fluorine atom, a hydroxyl _group, an alkyl group of C 1 -C _4, a C 1 -C ₄ It may have an alkoxy group. Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.

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

Represented by
R ₅ is hydrogen, an alkyl group (same as the alkyl group defined in (2) above), an aryl group (same as the aryl group represented by Ar ₃ or Ar ₄ above), a is 1 or 2, and b is 1 to 2 3 is represented.
Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, or an alkyleneoxycarbonyl group.
Examples of the substituted or unsubstituted alkylene group include the same alkylene groups as those described above for X.
Examples of the substituted or unsubstituted alkylene ether group include the alkylene ether group represented by X.
Examples of the alkyleneoxycarbonyl group include a caprolactone-modified group.
Further, the radical polymerizable compound having a monofunctional charge transport structure of the present invention is more preferably a compound having a structure of the following general formula (3).

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

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

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

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

  The radically polymerizable compound having a charge transporting structure used in the present invention is important for imparting the charge transport performance of the crosslinked surface layer, and this component is preferably 20 to 80 parts by weight based on the total amount of the crosslinked surface layer, preferably Is 30 to 70 parts by weight. If this component is less than 20 parts by weight, the charge transport performance of the crosslinked surface layer cannot be maintained sufficiently, and deterioration of electrical characteristics such as a decrease in sensitivity and an increase in residual potential appear with repeated use. On the other hand, when the amount is 80 parts by weight or more, the content of the trifunctional monomer having no charge transport structure is lowered, and the crosslink density is lowered, so that high wear resistance is not exhibited. Although the electrical characteristics and abrasion resistance required differ depending on the process used, it cannot be said unconditionally, but the range of 30 to 70 parts by weight is most preferable in consideration of the balance of both characteristics.

  The surface layer of the present invention is obtained by curing at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a charge transport structure. Monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers can be used in combination for the purpose of adjustment, stress relaxation of the cross-linked surface layer, lower surface energy, and reduction of friction coefficient. Known radical polymerizable monomers and oligomers can be used.

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

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

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

However, when a large amount of monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers are contained, the three-dimensional cross-linking density of the cross-linked surface layer is substantially reduced, resulting in a decrease in wear resistance. For this reason, the content of these monomers and oligomers is limited to 50 parts by weight or less, preferably 30 parts by weight or less, with respect to 100 parts by weight of the tri- or higher functional radical polymerizable monomer.
The surface layer of the present invention is obtained by crosslinking at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a charge transport structure by thermal polymerization or photopolymerization. In the crosslinking treatment, a crosslinking aid may be added in order to efficiently perform crosslinking.

  The crosslinking aid is not particularly limited as long as it is a polymerization initiator that easily generates radicals by heat and light, but examples include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone -1,2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione- Acetophenone-based or ketal-based photopolymerization initiators such as 2- (o-ethoxycarbonyl) oxime, benzoy Benzoin ether photopolymerization initiators such as benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl Benzophenone photopolymerization initiators such as 4-benzoylphenyl ether, acrylated benzophenone, 1,4-benzoylbenzene, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone Thioxanthone photopolymerization initiators such as 2,4-dichlorothioxanthone, and other photopolymerization initiators include ethyl anthraquinone, 2,4,6-to Methylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4- Examples include trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compounds, triazine compounds, and imidazole compounds.

Moreover, what has a photopolymerization promotion effect can be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.
These polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is 0.5 to 40 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total content having radical polymerizability.

  Furthermore, the coating liquid of the present invention can 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 as required. 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. 20 parts by weight or less, preferably 10 parts by weight or less. As leveling agents, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount used is based on the total solid content of the coating liquid. 3 parts by weight or less is appropriate.

  When forming the radically polymerizable monomer having a trifunctional or higher functionality and a radically polymerizable compound having a charge transporting structure on the photosensitive layer, it is preferable that the coating liquid has low viscosity and fluidity. If any material is a low-viscosity liquid, each material can be mixed to make a coating solution. However, due to the characteristics of the spray coating method, the coating solution is used for good atomization. Sufficient fluidity is required. For this reason, it is preferable to adjust viscosity by diluting the coating liquid with an organic solvent. Since the organic solvent used here is as described above, it will not be described in detail here. According to the present inventors, the boiling point of the organic solvent is preferably 90 ° C. or lower, preferably 60 ° C. or higher at 1 atm. It is 90 ° C. or lower, more preferably 60 ° C. or higher and 80 ° C. or lower. These solvents may be used alone or in combination of two or more. The dilution rate of the coating liquid with the organic solvent is determined by the characteristics of the constituent components of the coating liquid.

  In this invention, after apply | coating this coating liquid, a surface layer is hardened by giving energy from the outside. Examples of external energy used at this time include heat, light, and ionizing radiation.

  As the thermal energy, air, nitrogen or other gas, steam, various heat media, infrared rays, or electromagnetic waves can be used, and heating is performed from the coating surface side or the support side. The heating temperature is preferably 100 ° C. or more and 170 ° C. 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. 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 ultra-high pressure mercury lamp having a wavelength mainly in the ultraviolet region, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, or a xenon arc metal halide lamp may be used. Alternatively, a light source that emits light having an absorption wavelength of the polymerization initiator may be used. When curing by using ultraviolet light, it is preferable generally is exposed with 365nm illumination of 50mW ^/ cm ² ~1000mW ^/ cm 2 and wavelength as a reference. 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.

  The temperature of the photoreceptor surface layer rises due to the influence of heat rays generated by the light source during UV irradiation. If the surface temperature of the photoreceptor rises too much, curing shrinkage of the surface layer is likely to occur, and the low molecular component contained in the adjacent layer migrates to the surface layer, resulting in curing inhibition or the electrophotographic photoreceptor. It is not preferable because the electrical characteristics of the above are deteriorated. 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 a cooling agent sealed inside the photoconductor, cooling with a gas or liquid inside the photoconductor, or the like.

  The film thickness of the surface layer is preferably 1 to 20 μm, and preferably 3 to 15 μm from the viewpoint of protecting the photosensitive layer. When the surface layer is thin, not only the photosensitive layer cannot be protected from mechanical abrasion due to the contact member of the photosensitive member or proximity discharge due to a charger, but also the film surface becomes difficult to level because it is difficult to level during film formation. May be skin-like. On the other hand, when the surface layer is thick, the entire photoreceptor layer becomes thick, and the reproducibility of the image due to the diffusion of charges is not preferable.

<About photosensitive layer>
Next, the photosensitive layer will be described. As described above, the photosensitive layer may have a function separation type laminated structure or a single layer structure. In the case of a laminated structure, the photosensitive layer is generally formed from a charge generation layer and a charge transport layer. In the case of a single layer structure, the photosensitive layer is a layer having both a charge generation function and a charge transport function. Hereinafter, each of the photosensitive layer having a laminated structure and the photosensitive layer having a charcoal layer structure will be described.

《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 triphenylamine 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.

  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 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 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.
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 the hole transport material 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.

  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. In addition, as a binder resin, a polymeric charge transport material having a charge transport function, for example, polycarbonate, polyester, polyurethane, polyether, and polyamine having an arylamine skeleton, a benzidine skeleton, a hydrazone skeleton, a carbazole skeleton, a stilbene skeleton, a pyrazoline skeleton, or the like. Polymer materials such as siloxane and acrylic resins, polymer materials having a polysilane skeleton, and the like can be used and are useful.

The amount of the charge transport material is 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. However, when a polymer charge transport material is used, it may be used alone or in combination with a binder resin.
Examples of the solvent used here include tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, and acetone. 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 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 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. Regarding the lower limit, although it differs depending on the system to be used (particularly the charging potential), 5 μm or more is preferable.

<< When the photosensitive layer is a single layer >>
A photosensitive layer having a single layer structure is a layer having both a charge generation function and a charge transport function. The photosensitive layer can be formed by dissolving or dispersing a charge generating substance, a charge transporting substance, and a binder resin in a suitable solvent, and applying and drying them. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
As the binder resin, in addition to the binder resin previously mentioned in the charge transport layer, the binder resin mentioned in the charge generation layer may be mixed and used. Of course, the polymer charge transport materials mentioned above can also be used favorably. The amount of the charge generating material with respect to 100 parts by weight of the binder resin is preferably 5 to 40 parts by weight, and the amount of the charge transporting material is preferably 0 to 190 parts by weight, and more preferably 50 to 150 parts by weight. The photosensitive layer is formed by dip coating, spray coating, bead coating, ring coating using a charge generator, binder resin, and a charge transport material together with a solvent such as tetrahydrofuran, dioxane, dichloroethane, and cyclohexane. It can be formed by coating with a coat. The film thickness of the photosensitive layer is suitably about 5 to 25 μm.

《Light shielding layer》
In the present invention, as a layer to which an ultraviolet absorber is added, a light shielding layer may be specially provided separately from the charge generation layer, the charge transport layer and the like.
The composition of the light shielding layer comprises at least a binder, a charge transport material and an ultraviolet absorber, and the blending amount of the ultraviolet absorber is 0.2 to 6 parts by weight, preferably 0. It is preferable to be in the range of 4 to 5 parts by weight, more preferably 0.5 to 4 parts by weight. Addition of less than 0.2 parts by weight has a poor effect of absorbing light for cross-linking the surface layer, and addition of more than 8 parts by weight does not improve the effect. Depending on the agent, it is not preferable because the coloration is intense and it cannot endure use, or the compatibility with the resin is poor and the resin surface bleeds out. The binder, charge transport material and ultraviolet absorber used for the light shielding layer can be selected from the materials described above.

  The film thickness of the light shielding layer is 2 μm to 10 μm, preferably 2 μm to 5 μm. When the thickness of the light shielding layer is less than 2 μm, the light shielding effect used when the surface layer is cross-linked becomes poor, and photodegradation of the constituent components of the photosensitive layer occurs. Various characteristics deteriorate. On the other hand, if it exceeds 10 μm, the film thickness of the photosensitive layer becomes too large, so that a clear latent image cannot be obtained due to the repulsive force in the process of movement of charges in the photosensitive layer, which is not preferable. In addition, it is not preferable to reduce the thickness of the other layers constituting the photosensitive layer so as not to change the total film thickness of the photosensitive layer because various characteristics as an electrophotographic photosensitive member are deteriorated.

<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.

《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, 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, thermosetting resins, and photocurable resins such as resins, urethane resins, phenol resins, and alkyd 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.
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.

《About various additives》
In the present invention, the surface layer, photosensitive layer, charge generation layer, charge transport layer, subbing layer, intermediate layer are used for the purpose of improving the environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential. Further, an antioxidant can be added to each layer such as a light shielding 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.

<< Configuration of image forming apparatus >>
Next, an image forming apparatus and a process cartridge for an image forming apparatus according to the present invention will be described in detail with reference to the drawings.
The image forming apparatus of the present invention uses a photoconductor having the cross-linked surface layer. For example, at least after the photoconductor is charged, exposed to an image, and developed, the toner image is transferred to an image carrier (transfer paper). The process includes transfer, fixing, and cleaning of 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 method can be used.

  An 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.

  A 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.

  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.

  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.

  A fur brush (14) and a cleaning blade (15) are used to clean the toner remaining on the photoconductor after the 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.

A neutralizing means 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.

<< Method for producing photoconductor >>
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 an 18 μm charge transport layer were formed.

[Coating liquid for undercoat layer]
・ Alkyd resin 6 parts (Beccosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals)
・ 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 pigment of the following structural formula (I) 2.5 parts-Polyvinyl butyral (XYHL, manufactured by UCC) 0.5 part-Cyclohexanone 200 parts-Methyl ethyl ketone 80 parts

[Coating liquid for charge transport layer]
・ 10 parts of bisphenol Z polycarbonate (Panlite TS-2050, manufactured by Teijin Chemicals)
・ Low molecular charge transport material (D-1) of the following structural formula (II) 7 parts ・ Tetrahydrofuran 100 parts ・ Tetrahydrofuran solution of 1% silicone oil 1 part (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.)
-UV absorbers listed in Table 1 (see Table 1)

Next, after applying a surface layer coating solution having the following composition onto the laminate comprising the conductive support / undercoat layer / charge generation layer / charge transport layer, a high-pressure mercury lamp lamp (manufactured by Ushio Inc.) was used. The surface layer was crosslinked by performing UV irradiation at an illuminance of 700 mW / cm ² (based on 365 nm) and an irradiation time of 120 sec to obtain a 5.2 μm surface cured film. Thereafter, drying was performed at 130 ° C. for 30 minutes to obtain an electrophotographic photosensitive member comprising a conductive support / undercoat layer / charge generation layer / charge transport layer / surface layer.

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

<< Evaluation of transmittance >>
A 5 μm coating film was prepared by coating and drying the ultraviolet light absorber shown in Table 1 and the binder component (bisphenol Z polycarbonate) used in the charge transport layer on a transparent glass slide at the blending ratio shown in Table 1. The transmittance of the resin film / glass plate was measured at 300 nm to 400 nm with a spectrophotometer (UV3100; manufactured by Shimadzu Corporation). For the transmittance of the wavelength (365 nm in this example) having the maximum light emission intensity of the light source used to crosslink the surface layer, refer to the spectral transmittance data measured here, and obtain the transmittance at each compounding ratio. It was. The results are shown in Table 2.

<< Evaluation of photoconductor >>
Using the remodeled imgio Neo 270 machine (655 nm semiconductor laser as an image exposure light source), the produced electrophotographic photosensitive member was tested for 100,000 sheets through a real machine (A4, MyPaper made by NBS Ricoh, charged potential at start-700V). ) And the photoreceptor wear amount, the in-machine potential, and the image evaluation were performed. The results are shown in Tables 3, 4, and 5.

  Since the electrophotographic photoreceptor of the present invention can provide a good image for a long period of time, it can be effectively used in an image forming process of a copying machine, a facsimile, a laser printer or the like.

1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. FIG. 2 is a schematic diagram illustrating an example of a process cartridge for an image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charger 4 Eraser 5 Image exposure part 6 Developing unit 7 Pre-transfer charger 8 Registration roller 9 Transfer paper 10 Transfer charger 11 Separation charger 12 Separation claw 13 Pre-cleaning charger 14 Fur brush 15 Cleaning blade 101 Photosensitive drum 102 Charging device 103 Exposure 104 Developing device 105 Transfer body 106 Transfer device 107 Cleaning blade

Claims (8)

The conductive support has at least a charge generation layer, a charge transport layer , and a surface layer in this order. The thickness of the charge transport layer is 5 to 30 μm, and the surface layer does not have at least a charge transport structure. In the electrophotographic photoreceptor obtained by crosslinking a mixture containing a trifunctional or higher-functional radical polymerizable monomer and a monofunctional radical polymerizable compound having a charge transporting structure by means of light energy irradiation, radical polymerizable compound monofunctional with transport structure is at least one compound represented by the following general formula (3), contains an ultraviolet absorber in the charge transport layer, of the UV absorber the amount is 0.2 parts by weight to 6 parts by weight based on the binder resin content 10 parts by weight of the charge transport layer, and the wavelength having the maximum emission intensity of the light source used to crosslink the surface layer An electrophotographic photosensitive member in which the transmittance in said charge transport layer, characterized in that an amount such that less than 70% of the.
However, the transmittance is to add an ultraviolet absorber to the binder resin content to form the charge transport layer, which in transmittance obtained by measuring the resin film obtained by depositing a thickness of 5μm is there.

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

Represents. )   2. The electrophotographic photosensitive member according to claim 1, wherein the functional group of a tri- or higher functional radical polymerizable monomer having no charge transporting structure used in the surface layer is an acryloyloxy group and / or a methacryloyloxy group. body.   The ratio of the molecular weight to the number of functional groups (molecular weight / number of functional groups) in a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure used for the surface layer is 250 or less. The electrophotographic photoreceptor described in 1. Component proportion of trifunctional or more radical polymerizable monomer having no charge transport structure for use in the surface layer, according to claim 1 to 3, characterized in that 30 to 70 wt% with respect to the cross-linked surface layer the total amount The electrophotographic photosensitive member according to any one of the above. Component ratio of the radical polymerizable compound having one functionality and a charge transporting structure used for the surface layer, any one of claims 1-4, characterized in that 30 to 70 wt% with respect to the cross-linked surface layer the total amount The electrophotographic photoreceptor described in 1. Has an electrophotographic photosensitive member according to any one of claims 1 to 5, at least, a charging means for charging the electrophotographic photoreceptor, an electrostatic latent image on the electrophotographic photoconductor surface that has been allowed to charge by the charging means A process for forming an image, and a developing unit for attaching toner to an image portion of an electrostatic latent image formed by a latent image forming device. cartridge. Has an electrophotographic photosensitive member according to any one of claims 1 to 5, at least, a charging means for charging the electrophotographic photoreceptor, an electrostatic latent image on the electrophotographic photoconductor surface that has been allowed to charge by the charging means A process cartridge for an image forming apparatus, which is integrally provided with one means selected from a latent image forming means for forming a toner and a developing means for attaching toner to an image portion of an electrostatic latent image formed by a latent image forming device. An image forming apparatus, wherein the image forming apparatus is mounted and the process cartridge for the image forming apparatus is detachable. A method for producing an electrophotographic photosensitive member according to claim 1, the amount of the ultraviolet absorber a UV absorber in the charge transport layer is, the binder resin content 10 weight of the charge transport layer 0.2 parts by weight to 6 parts by weight per part, and transmittance in the charge transporting layer of the light of a wavelength having a maximum emission intensity of the light source used to crosslink the surface layer is less than 70% A method for producing an electrophotographic photosensitive member, comprising the step of containing such an amount and irradiating the surface layer with light energy to crosslink the surface layer.
However, the transmittance is to add an ultraviolet absorber to the binder resin content to form the charge transport layer, the transmittance of the resin film having a thickness of 5μm obtained by deposition.

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