JP5347348B2 - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoreceptor capable of achieving both high durability and enhanced image quality excellent in mechanical strength/abrasion resistance of its surface without adversely affecting the performance of the photoreceptor that has a photosensitive layer and a protective layer, successively layered on a conductive support, such as electrostatic charging property and sensitivity/residual potential, etc. <P>SOLUTION: In an electrophotographic photoreceptor that has a photosensitive layer and a protective layer successively layered on a conductive support, the protective layer contains a reaction-cured material of silsesquioxane represented by a general formula (I) wherein R represents an organic group that binds a reactive organic group and a 2-20C hydrocarbon group, a plurality of Rs being either the same or different, and n represents an integer of 2-20. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member used in an electrophotographic process in a copying machine, a laser beam printer, a facsimile, or the like.

  In recent years, there has been a remarkable development in information processing system machines using an electrophotographic process. In particular, laser printers and digital copiers that use electrophotographic photoreceptors (hereinafter also simply referred to as photoreceptors) for converting information into digital signals and recording information by light have improved print quality and reliability. It is remarkable. As photoconductors used in laser printers and digital copying machines for these electrophotographic processes, those using organic photosensitive materials are widely applied for reasons such as cost, productivity, and pollution-free property. .

  However, organic photoreceptors are more susceptible to film abrasion due to repeated use than inorganic photoreceptors. As film removal of the photosensitive layer progresses, there is a strong tendency to promote ground stain, image density reduction or image quality deterioration due to a decrease in charging potential or photosensitivity of the photosensitive member, scratches on the surface of the outermost layer of the photosensitive member, Conventionally, the abrasion resistance of the photosensitive layer has been cited as a major issue. Further, in recent years, with the increase in the speed of the electrophotographic apparatus or the reduction in the diameter of the photoreceptor accompanying the downsizing of the apparatus, it has become a more important issue to improve the durability of the photoreceptor.

  On the other hand, in recent years, with the demand for higher image quality in the market, the atomization of toner has been promoted. However, such atomized toner is liable to cause defective cleaning and the like, causing image deterioration due to toner filming and fusing, and cleaning is required to have higher accuracy.

  In addition, with the space saving of the apparatus, it is advantageous to employ cleaning with a blade in order to realize a simpler apparatus configuration. The blade cleaning has a simple configuration in which an elastic member such as plate-like polyurethane is abutted in the direction of the bus on the photoreceptor. However, in such a case, the outermost layer of the photoconductor is accelerated and the durability is lowered. In order to cope with this, it is effective to give the outermost layer of the photoreceptor a strength that can withstand frictional force, and many studies have been made so far.

  Since the photoreceptor is repeatedly subjected to the effects of charging, exposure, development, transfer, cleaning, charge removal, etc. in the electrophotographic process, it is particularly important to achieve both high image quality and durability as functions. ing. In particular, mechanical strength such as wear resistance and scratch resistance is the largest factor that determines the endurance life.

  However, the durability of the photoreceptor is greatly affected by the printing durability of the outermost layer of the photoreceptor. Usually, when the photoconductor is mounted and used in an electrophotographic apparatus, the outermost layer of the photoconductor is rubbed by a contact member such as a cleaning blade or a charging roller, and a part thereof is forced to be scraped off. If the amount of the outermost layer of the photoreceptor removed by rubbing, that is, the amount of film reduction is large, there arises a problem that the charge holding ability of the photoreceptor is lowered and the image quality is lowered. For this reason, the outermost layer of the photoreceptor is required to be hard to be scraped off by the contact member, that is, to have excellent printing durability.

  As a means for realizing high durability of a photoreceptor, a photosensitive layer (including a charge generation layer and a charge transport layer) is covered with a surface protective layer. As a method for imparting durability to the surface protective layer, for example, a method using a curable resin has been studied.

  For example, a photoconductor using a radiation curable resin having a reactive acryloyl group or methacryloyl group as a protective layer material on the surface of the photoconductor is disclosed (Patent Documents 1 and 2). In addition, a technique is known in which the surface protective layer of the photoreceptor contains at least a radiation crosslinking agent and a charge transport material, and radiation crosslinking is performed in an atmosphere having an oxygen concentration of 5% or less (Patent Document 3). Furthermore, in an electrophotographic photosensitive member in which a charge generation layer, a charge transport layer, and a protective layer are laminated in this order on a conductive support, the protective layer is formed of a reaction-cured film that is reactively cured by light irradiation of a pulsed light source. (Patent Document 4).

  However, when using a curable binder resin as shown above, reaction deterioration of the organic photoconductive material during curing, formation of impurity levels due to unreacted functional groups and polymerization initiator by-products, etc. As a result, sufficient photoconductive properties could not be obtained. In addition, although the wear resistance is improved, the reaction is not sufficient, and the closer to the surface of the photoreceptor, the more unreacted substances increase, so that filming of toner components and the like is likely to occur.

  As another method, for example, it has been proposed to provide a crosslinkable organopolysiloxane resin layer as a protective layer on the surface layer of the photoreceptor.

  However, such a method of providing a crosslinkable organopolysiloxane resin layer is not sufficient, although the mechanical strength and abrasion resistance of the surface are larger than those of conventional photoreceptors. Another problem is that the chargeability, sensitivity, residual potential, etc. of the photoconductor may be deteriorated, and that under such conditions as high temperature and high humidity, image flow may occur and a clear image cannot be obtained. It was.

  Further, as a technique for improving the durability of the charge transport layer without providing a surface protective layer, a technique using at least one charge transport layer containing at least one charge transport component and at least one silanol has been proposed. The abrasion resistance and image quality are insufficient (Patent Document 7).

From the above situation, the mechanical strength and abrasion resistance of the surface can be obtained without adversely affecting the chargeability, sensitivity, residual potential, etc. of the photoreceptor in which the photosensitive layer and protective layer are sequentially laminated on the conductive support. Development of a photoconductor that achieves both excellent durability and high image quality has been desired.
JP 2000-310871 A JP 2001-125297 A JP 2005-099188 A JP 2008-076465 A1 Japanese Patent Laid-Open No. 3-139655 JP-A-5-40359 JP 2008-20912 A

  The present invention has been made in view of the above circumstances, and its object is to adversely affect the performance of the photosensitive member in which a photosensitive layer and a protective layer are sequentially laminated on a conductive support, such as chargeability, sensitivity and residual potential. The present invention also provides a photoconductor that achieves both high durability and high image quality with excellent surface mechanical strength and wear resistance.

  The above object of the present invention has been achieved by the following constitution.

1. In an electrophotographic photosensitive member in which a photosensitive layer and a protective layer are sequentially laminated on a conductive support,
A ladder-structured silsesquioxane reaction cured product represented by the following general formula (II) or a cage structure represented by any of the following general formulas (III), (IV), or (V) An electrophotographic photoreceptor comprising a reaction cured product of silsesquioxane .

(In the formula, R1 is a group represented by any of the following formula (13), formula (14), formula (15), formula (19), formula (20) and formula (22)), and t is 1 Represents an integer of ˜30.)

(U in Formula (13), Formula (14), Formula (15), Formula (19), Formula (20), and Formula (22)) represents an integer of 1 to 19. X3 in Formula (22) and X4 is a methyl group, an ethyl group or a phenyl group, and X3 and X4 may be the same.)

(R2 in the general formula (III) is a group represented by any one of the following formula (25), formula (26), formula (31), formula (32), and formula (36)). (IV) and R2 in the general formula (V) are groups represented by any of the following formulas (25) and (31).

(V in the formula (25), the formula (26), the formula (31), the formula (32), and the formula (36) represents an integer of 1 to 19. X5 and X6 in the formula (36) are methyl groups, It is an ethyl group or a phenyl group, and X5 and X6 may be the same.)

2. In an electrophotographic photosensitive member in which a photosensitive layer and a protective layer are sequentially laminated on a conductive support,
A silsesquioxane having a ladder structure represented by the following general formula (II) or a silsesquioxane having a cage structure represented by any of the following general formulas (III), (IV), or (V) is provided in the protective layer. And a silsesquioxane having a ladder structure represented by the following general formula (II) or a silsesquioxane having a cage structure represented by any of the following general formulas (III), (IV), and (V): An electrophotographic photoreceptor comprising a reaction cured product with a compound having a reactive organic group.

(In the formula, R1 is a group represented by any of the following formula (13), formula (14), formula (15), formula (19), formula (20) and formula (22)), and t is 1 Represents an integer of ˜30.)

(U in Formula (13), Formula (14), Formula (15), Formula (19), Formula (20), and Formula (22)) represents an integer of 1 to 19. X3 in Formula (22) and X4 is a methyl group, an ethyl group or a phenyl group, and X3 and X4 may be the same.)

(R2 in the general formula (III) is a group represented by any one of the following formula (25), formula (26), formula (31), formula (32), and formula (36)). (IV) and R2 in the general formula (V) are groups represented by any of the following formulas (25) and (31).

(V in the formula (25), the formula (26), the formula (31), the formula (32), and the formula (36) represents an integer of 1 to 19. X5 and X6 in the formula (36) are methyl groups, It is an ethyl group or a phenyl group, and X5 and X6 may be the same.)

  Highly superior surface mechanical strength and wear resistance without adversely affecting the performance of the photosensitive member, which has a photosensitive layer and a protective layer laminated on a conductive support, in order to avoid adverse effects on the charging performance, sensitivity and residual potential. We were able to provide a photoreceptor that has both durability and high image quality.

  The present invention will be described in detail below.

[Photosensitive layer structure]
The photoreceptor of the present invention is obtained by sequentially laminating at least a photosensitive layer and a protective layer on a conductive support. The layer structure is not particularly limited, and specifically, as shown below. A layer structure can be mentioned.

1) A layer structure in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated as a photosensitive layer on a conductive support.
2) A layer structure in which a single layer containing a charge transport material and a charge generation material as a photosensitive layer and a protective layer are sequentially laminated on a conductive support.
3) Layer structure in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated as an intermediate layer and a photosensitive layer on a conductive support.
4) A layer structure in which an intermediate layer, a single layer containing a charge transport material and a charge generation material as a photosensitive layer, and a protective layer are sequentially laminated on a conductive support.

  The photoreceptor of the present invention may have any of the above-described layer structures, but among these, those prepared by providing an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer on a conductive support are preferable. .

[Protective layer]
The protective layer of the photoreceptor is a layer in which the photoreceptor is in contact with the air interface.

  The protective layer relating to the photoreceptor of the present invention contains a reaction cured product of silsesquioxane represented by the following general formula (I).

  The protective layer according to the photoreceptor of the present invention contains a reaction cured product of a silsesquioxane represented by the following general formula (I) and a compound having an organic group capable of reacting with the silsesquioxane. To do.

  In formula, R shows the organic group which combined the reactive organic group and the hydrocarbon group, Carbon number of a hydrocarbon group becomes like this. Preferably it is an integer of 1-20, Most preferably, it is an integer of 2-10. By setting the number of carbons within this range, it is possible to form a film having high mechanical strength and high wear resistance that satisfies both strength and flexibility.

  In addition, since the reaction cured product has a cross-linked structure, the mechanical strength and the wear resistance are improved. The plurality of organic groups R may all be the same organic group or different organic groups.

  N is preferably an integer of 2 to 20, particularly preferably an integer of 4 to 16. By setting the amount within this range, the compatibility with the solvent is not impaired, so that a homogeneous cured film excellent in coating properties compatible with mechanical strength and wear resistance can be obtained.

  The reactive organic group of the organic group R means an organic group that undergoes a hydrolysis reaction or a polymerization reaction by an external stimulus and is chemically bonded to the surrounding organic group, and is a thermosetting or active ray curable organic group. Groups are preferred. Examples of the reactive organic group include acryloyl group, methacryloyl group, vinyl group, epoxy group, 3,4-epoxycyclohexyl group, oxetanyl group and the like. Among them, an acryloyl group and a methacryloyl group are particularly preferable because the mechanical strength and wear resistance can be improved by increasing the crosslinking density.

  The organic group R preferably has an ether group or a siloxane group as a linking group. By controlling the flexibility by these linking groups, the crack resistance of the coating film can be enhanced. The specific structure of the organic group R is shown below.

  In the above structural formulas, X1 and X2 may be the same or different and each represents a methyl group, an ethyl group, or a phenyl group. m shows the integer of 1-20.

  Among the above structural formulas, (1) to (6) represent thermosetting organic groups, and (7) to (12) represent actinic radiation curable organic groups.

  The silsesquioxane relating to the photoreceptor of the present invention is a silsesquioxane having a ladder structure represented by the following general formula (II) or a silsesquioxane having a cage structure represented by the following general formulas (III) to (VII). preferable.

  In the formula, R1 has an ether bond and a siloxane bond having a reactive organic group (for example, acryloyl group, methacryloyl group, vinyl group, epoxy group, 3,4-epoxycyclohexyl group, oxetanyl group, etc.). The C2-C20 hydrocarbon group substituent which may be good is shown. A plurality of R may be the same. t shows the integer represented by 1-30.

  Specific structural formulas of R1 possessed by the silsesquioxane having a ladder structure represented by the general formula (II) are shown below.

  Among the above structural formulas, X3 and X4 may be the same and represent a methyl group, an ethyl group, or a phenyl group. u represents an integer of 1 to 19.

  Among the above structural formulas, (13) to (24) represent thermosetting organic groups, and (19) to (24) represent actinic radiation curable organic groups.

  In the formula, R2 has an ether bond having a reactive organic group (for example, acryloyl group, methacryloyl group, vinyl group, epoxy group, 3,4-epoxycyclohexyl group, oxetanyl group, etc.) or a siloxane bond. An optionally substituted hydrocarbon group substituent having 2 to 20 carbon atoms is shown. Several R2 may be the same. Specific structural formulas of R2 possessed by the silsesquioxane having the cage structure represented by the general formulas (III) to (VII) are shown below.

  Among the above structural formulas, X5 and X6 may be the same and represent a methyl group, an ethyl group, or a phenyl group. v represents an integer of 1 to 19.

  Of the above structural formulas, (25) to (30) represent thermosetting organic groups, and (31) to (36) represent actinic radiation curable organic groups.

  The ladder structure silsesquioxane represented by the general formula (II) and the cage structure silsesquioxane represented by the general formulas (III) to (VII) can be used alone or in a mixture.

  The use in a mixture means a mixture of a silsesquioxane having a ladder structure and a silsesquioxane having a cage structure or a mixture of silsesquioxanes having different cage structures. However, when mixed and used, mixing with silsesquioxanes having photocurable reactive organic groups or silsesquioxanes having thermosetting reactive organic groups can stabilize the reaction. It is preferable in terms of performance.

  The mixing ratio in the case of mixed use varies depending on the type of silsesquioxane to be used, so it is difficult to uniquely define it. It can be determined appropriately according to the required hardness of the protective film. Next, the compound having an organic group capable of reacting with silsesquioxane relating to the photoreceptor of the present invention will be described.

  The reactive organic group is preferably actinic ray curable or thermosetting. Examples of the actinic ray curable organic group include an acryloyl group, a methacryloyl group, and a vinyl group. Examples of the compound having a photocurable reactive organic group include isobornyl (meth) acrylate, bornyl (meth) methacrylate, dicyclopentenyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxy (Meth) acrylates such as propyl (meth) acrylate, (poly) propylene glycol mono (meth) acrylate, t-butyl (meth) acrylate, (meth) acrylamides such as morpholine (meth) acrylamide, N-vinylcaprolactone, Monofunctional radically polymerizable compounds such as styrene; trimethylopropane tri (meth) acrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol Cole (meth) acrylate, triethylene glycol (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di ( Examples thereof include polyfunctional radically polymerizable compounds such as (meth) acrylate, neopentyl glycol di (meth) acrylate, dicyclopentenyl di (meth) acrylate, diallyl phthalate, diallyl fumarate, and ethylene oxide-modified bisphenol A diacrylate.

  Examples of the thermosetting organic group include an epoxy group, an oxetanyl group, and an alicyclic epoxy group. Examples of these compounds having reactive organic groups include bisphenol F type epoxy compounds, bisphenol AD type epoxy compounds, hydrogenated bisphenol A and hydrogenated bisphenol F diglycidyl ether, bisphenol A propylene oxide addition type diglycidyl ether, Polyhydric glycidyl ethers obtained from polyhydric alcohols such as aliphatic diols and triols, alkyl monoglycidyl ethers such as butyl glycidyl ether, cyclohexene oxide, vinylcyclohexene dioxide, 3,4-epoxycyclohexylmethyl-3 ′, 4 '-Epoxycyclohexanecarboxylate, alicyclic epoxy compounds such as di (3,4-epoxycyclohexylmethyl) adipate, diethylene glycol divinyl ether, trie Glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, hydroxybutyl vinyl ether and dodecyl vinyl ether multifunctional heat polymerizable compound, and the like.

  The silsesquioxane relating to the photoreceptor of the present invention can be used alone, or a mixture of silsesquioxane and a compound having an organic group capable of reacting with silsesquioxane is used. You can also

  The mixing ratio of the compound having a photocurable or thermosetting organic group capable of reacting with the silsesquioxane shown above and the silsesquioxane of the present invention is the silsesquioxane used. And the kind of the compound having a photocurable or thermosetting organic group capable of reacting with silsesquioxane as the reactive organic group and the required hardness of the protective film, can be appropriately determined.

  As a method for forming a protective layer, a coating solution for forming a protective layer is dip coated, or a circular amount regulation type coating, or a combination of dip coating and a circular amount regulation type coating is applied on a photosensitive layer and then used. Although it can produce by performing the photocuring process and the thermosetting process according to the kind of applied coating liquid for protective layer formation, it is not limited to this. The circular amount regulation type application is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

The following effects can be obtained by using the photoreceptor of the present invention.
1. A high-quality image can be formed without adversely affecting the performance such as the chargeability, sensitivity, and residual potential of the photoreceptor.
2. In particular, a high-quality image can be formed without causing an image flow or the like in a high temperature and high humidity environment.
3. By increasing the mechanical strength of the surface of the photoreceptor, it is possible to prevent wear and scratches due to cleaning and the like, and to maintain a high quality image for a long period.

(Polymerization initiator)
The silsesquioxane or the compound having an organic group capable of reacting with silsesquioxane relating to the photoreceptor of the present invention is preferably reaction-cured in the presence of a polymerization initiator. Examples of the polymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl phenyl ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy- 2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-2 Acetophenone-based or ketal-based photopolymerization initiators such as morpholino (4-methylthiophenyl) propan-1-one and 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, benzoin, benzoinmethyl Ether, benzoin ethyl ether, benzoin isobutyl ether, benzo Benzoin ether photopolymerization initiators such as isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, 1,4 -Benzophenone photopolymerization initiators such as benzoylbenzene, thioxanthone photopolymerization initiators such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Is mentioned.

  Other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine Examples thereof include oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine compound, and imidazole compound. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.

These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.5-40 mass parts with respect to 100 mass parts of total contents which have radical polymerizability, Preferably it is 1-20 mass parts.
(Reaction cured product)
In the present invention, a reaction cured product is contained in the protective layer, but the “reaction cured product” is formed by polymerizing a polymerizable compound by irradiation of heat or active rays such as ultraviolet rays and electron beams. Reaction product. The reaction cured product is formed by a reaction of silsesquioxane and a reaction with an organic group capable of reacting with silsesquioxane, and the reaction may be thermal curing or active ray curing.

  In the case of actinic radiation curing, in the present invention, in the presence of a polymerization initiator, silsesquioxane related to the photoreceptor of the present invention or a compound having an organic group capable of reacting with silsesquioxane is irradiated with actinic radiation to generate radicals. To form a cross-linked bond between the molecules and within the molecule, and cure to form a reaction cured product. As the actinic ray, ultraviolet rays and electron beams are preferable.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² .

  As an electron beam source, there is no particular limitation on the electron beam irradiation device, and generally, an electron beam accelerator for such electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage at the time of electron beam irradiation is preferably 100 to 300 kV, and the absorbed dose is preferably 0.5 to 10 Mrad.

Silsesquioxane or a compound having an organic group capable of reacting with silsesquioxane relating to the photoreceptor of the present invention is preferably irradiated with actinic rays during or after coating and drying. The irradiation time for obtaining the necessary irradiation amount of active rays is preferably about 0.1 seconds to 3 minutes, and more preferably 1 to 60 seconds from the viewpoint of curing efficiency or work efficiency of the compound having a curable functional group. . The illuminance of these active ray irradiators is preferably 50 to 1000 mW / m ² .

  As an actinic ray, ultraviolet rays are preferred because they are easier to use than electron beams.

In addition to the silsesquioxane and the compound having an organic group capable of reacting with the silsesquioxane related to the photoreceptor of the present invention, the protective layer includes fillers, particulate additives such as lubricant particles, and oxidation as necessary. An inhibitor or the like can be contained.
(Particulate additive)
The particulate additive used in the present invention preferably has a number average primary particle size of 3 to 300 nm. Particularly preferred is 10 to 200 nm. Particles having a number average primary particle size in the above range can be uniformly dispersed in the coating solution, so that formation of aggregated particles and generation of large irregularities on the surface can be prevented, and the aggregated particles serve as charge traps and black spots. In addition, it is possible to form a good toner image without generation of transfer memory and generation of black spots due to the large unevenness. Further, the particles are less likely to settle in the coating solution, and the dispersion stability of the solution is also excellent. In the present invention, the particles to be added can include inorganic particles and organic particles.

  As for the ratio of an inorganic particle and an organic particle, 20-80 mass% of inorganic particles are preferable, and 30-70 mass is more preferable. Examples of the inorganic particles include those selected from titania particles, silica particles, alumina particles, and strontium titanate particles. Among these, titania particles, silica particles, and alumina particles are preferable.

  The inorganic particles are preferably surface-treated from the viewpoint of improving dispersibility and stability of electrophotographic characteristics. For example, inorganic particles are added to a solution obtained by dissolving or suspending a reactive organosilicon compound in an organic solvent or water, and the solution is stirred for several minutes to about 1 hour. And depending on the case, after heat-processing this liquid, it passes through processes, such as filtration, and is dried, and the inorganic particle which coat | covered the surface with the organosilicon compound is obtained. A reactive organosilicon compound may be added to a suspension in which inorganic particles are dispersed in an organic solvent or water.

  In order to form the protective layer, the constituent components, such as silsesquioxane related to the photoreceptor of the present invention, a compound having an organic group capable of reacting with silsesquioxane, a polymerization initiator and an antioxidant are dissolved. The selection of the solvent to be used is also important. That is, it is preferable to select a good solvent (a solvent that dissolves well) in these protective layer coating compositions and use it as a coating solvent for the protective layer. For example, it is preferable to use alcohols such as tetrahydrofuran (THF), toluene, various ketones, ethanol, isopropanol, and 1-propanol. The thickness of the protective layer is preferably 0.2 to 10 μm, more preferably 1.0 to 7.0 μm.

  Next, members other than the protective layer and each layer constituting the photoreceptor of the present invention will be described.

(Conductive support)
The conductive support for the roll-shaped photoreceptor is preferably cylindrical and has a specific resistance of 10 ³ Ωcm or less. As a specific example, cylindrical aluminum whose surface has been cleaned after cutting can be mentioned.

  Examples of the substrate of the belt-shaped photoreceptor include those in which aluminum vapor deposition or indium / tin oxide is formed on the surface of polyimide resin, polyester resin, polycarbonate resin or the like.

(Middle layer)
The intermediate layer is formed by applying and drying an intermediate layer forming coating solution composed of a binder, a dispersion solvent, and the like on a conductive substrate. Examples of the binder for the intermediate layer include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of these resin repeating units. Among these resins, a polyamide resin is preferable because it can reduce an increase in residual potential due to repeated use. In addition, for the purpose of improving potential characteristics, reducing black spot defects, reducing moire, etc., additives such as fillers and antioxidants such as titanium oxide and zinc oxide can be added to the intermediate layer as necessary. .

  As the solvent for preparing the coating solution for forming the intermediate layer, a solvent in which the inorganic particles to be added as needed are well dispersed and the polyamide resin is dissolved is preferable. Specifically, alcohols having 2 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol are excellent in solubility and coating performance of polyamide resin. preferable. These solvents are 30% by mass to 100% by mass, preferably 40% by mass to 100% by mass, and more preferably 50% by mass to 100% by mass in the total solvent. Examples of co-solvents that can be used in combination with the above-mentioned solvent to obtain preferable effects include benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran. The thickness of the intermediate layer is preferably 0.2 μm to 40 μm, and more preferably 0.3 μm to 20 μm.

(Photosensitive layer)
The photosensitive layer may have a single layer structure in which a charge generation function and a charge transport function are provided in one layer, but more preferably the function of the photosensitive layer is separated into a charge generation layer (CGL) and a charge transport layer (CTL). It is more preferable to take a layer structure. By adopting a configuration in which the functions are separated, it is possible to control an increase in residual potential due to repeated use, and to easily control other electrophotographic characteristics according to the purpose. In the negatively charged photoreceptor, a charge generation layer (CGL) is formed on the intermediate layer, and a charge transport layer (CTL) is formed thereon. In the positively charged photoreceptor, the order of the layer configuration is opposite to that in the negatively charged photoreceptor. A preferred layer structure of the photosensitive layer is a negatively charged photoreceptor having the function separation structure.

  Hereinafter, each layer of the photosensitive layer of the function-separated negatively charged photoreceptor will be described.

<Charge generation layer (CGL)>
The charge generation layer (CGL) contains a charge generation material (CGM). As other substances, a binder resin and other additives may be contained as necessary. As the charge generation material (CGM), oxytitanium phthalocyanine having a maximum diffraction peak at a Bragg angle (2θ ± 0.2) of 27.2 ° in X-ray diffraction by CuKα ray, which is a known charge generation material (CGM), 2θ However, CGM such as benzimidazole perylene, which has a maximum peak at 12.4 °, is hardly deteriorated by repeated use, and the increase in residual potential can be reduced.

  When a binder is used as a dispersion medium for the charge generation material (CGM) in the charge generation layer (CGL), a known resin can be used as the binder, but the most preferable resins are formal resin, butyral resin, silicone resin, silicone. Examples include modified butyral resins and phenoxy resins. The ratio of the binder resin to the charge generation material (CGM) is preferably 20 to 600 parts by mass of the charge generation material (CGM) with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer (CGL) is preferably 0.01 to 2 μm.

<Charge transport layer (CTL)>
The charge transport layer (CTL) contains a charge transport material (CTM) and a binder resin. Other substances may be formed by adding additives such as antioxidants as necessary.

  A known charge transport material (CTM) can be used as the charge transport material (CTM). For example, triphenylamine derivatives, hydrazone compounds, styryl compounds, benzidine compounds, butadiene compounds, and the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer.

  Examples of the resin used for the charge transport layer (CTL) include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, and polycarbonate. Resin, silicone resin, melamine resin, and copolymer resin containing two or more of the repeating units of these resins. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used.

  The most preferable binder for the charge transport layer (CTL) is a polycarbonate resin. The polycarbonate resin is most preferable in improving the dispersibility and electrophotographic characteristics of the charge transport material (CTM). The ratio between the binder resin and the charge transport material (CTM) is preferably 10 parts by mass to 200 parts by mass with respect to 100 parts by mass of the binder resin.

〔Antioxidant〕
When an antioxidant is applied to the constituent layers of the photoconductor, the influence of attack of an active gas such as NOx can be reduced, so that occurrence of image flow in a high temperature and high humidity environment can be suppressed.

The typical antioxidant used in the present invention is to prevent the action of oxygen on auto-oxidizing substances existing in the photoreceptor or on the photoreceptor surface under conditions of light, heat, discharge, etc. It is also a substance having a suppressing property. Specifically, the following compound groups can be mentioned.
(1) Radical chain inhibitor Phenolic antioxidants, hindered phenolic antioxidants, amine antioxidants, hindered amine antioxidants, diallyldiamine antioxidants, diallylamine antioxidants, hydroquinone antioxidants Agents and the like.
(2) Peroxide decomposing agent Sulfur-based antioxidants, thioethers, phosphoric acid-based antioxidants, phosphites and the like can be mentioned.

  The hindered phenol antioxidant (antioxidant having a hindered phenol structure) is a compound having a bulky organic group at the ortho position of the phenolic OH group or the alkoxylated group of the phenolic OH. A system antioxidant (an antioxidant having a hindered amine structure) is a compound having a bulky organic group near the N atom. The bulky organic group includes a branched alkyl group, for example, a t-butyl group is preferable.

  Among the above antioxidants, the radical chain inhibitor (1) is good, and among them, the antioxidant having a hindered phenol structure or a hindered amine structure reacts with the radical active species generated from the polymerization initiator and oxygen. In order to prevent this, the generated radical active species can be effectively contributed to the reaction, which is preferable.

  Two or more types may be used in combination, for example, a combination of (1) a hindered phenol antioxidant and (2) a thioether antioxidant.

  In the antioxidant used in the present invention, more preferable is that the hindered amine structure in the molecule is good for image quality improvement such as image blur prevention and black spot countermeasures, and as another aspect, a hindered phenol structural unit. Those having hindered amine structural units in the molecule are also preferred.

(Production of photoconductor)
Each layer (intermediate layer, photosensitive layer, charge generation layer, charge transport layer) relating to the photoreceptor of the present invention is produced by dip coating, circular amount regulation type coating, or dip coating and round amount regulation type coating in combination. Although it can produce by providing a coating film, it is not limited to this. The circular amount regulation type application is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following text, “part” means “part by mass”.

Example 1
(Preparation of conductive support)
The surface of the cylindrical aluminum support was cut to prepare a conductive support having a ten-point surface roughness RzJIS = 1.5 (μm), a diameter of 30 mm, and a length of 360 mm. The ten-point surface roughness RzJIS represents a value measured according to JIS B 0601-2001.

(Formation of intermediate layer)
A dispersion having the following composition was diluted twice with the same mixed solvent, and allowed to stand overnight, followed by filtration (filter; using a lime mesh 5 μm filter manufactured by Nihon Pall) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part Titanium oxide SMT500SAS (manufactured by Teika) 3 parts Methanol 10 parts Dispersion was carried out for 10 hours in a batch manner using a sand mill as a disperser.
It apply | coated by the dip coating method so that it might become a dry film thickness of 2 micrometers on the said support body using the said coating liquid.

(Formation of charge generation layer)
Charge generation material: titanyl phthalocyanine pigment (titanyl phthalocyanine pigment having a maximum diffraction peak at a position of at least 27.3 ± 0.2 ° as measured by Cu-Kα characteristic X-ray diffraction spectrum) 20 parts polyvinyl butyral resin (# 6000-C 10 parts t-butyl acetate 700 parts 4-methoxy-4-methyl-2-pentanone 300 parts were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm.

(Formation of charge transport layer)
Charge transport material (4,4′-dimethyl-4 ″-(β-phenylstyryl) triphenylamine) 25 parts Binder: Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts Antioxidant (Irganox 1010: Nippon Ciba-Geigy Corporation) 6 parts) THF 1600 parts Toluene 400 parts Silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part was mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 25 μm.

(Formation of protective layer)
(Preparation of protective layer coating solution 1)
Silsesquioxane (Exemplary Compound No. 1, t = 1) 3 parts Photopolymerization initiator: Irgacure 369 (manufactured by Ciba Japan Co., Ltd.) 0.2 part Solvent: n-propanol 15 parts A protective layer coating solution 1 was prepared.

Using the prepared protective layer coating solution 1, the coating was applied on the charge transport layer by a circular amount-regulating coating method, dried at 110 ° C. for 20 minutes, and integrated using a pulsed UV irradiation device RC-500B manufactured by Xenon. Photocuring was performed so that the amount of light was 10 J / cm ² , a protective layer was formed, and a photoconductor was prepared. Photoconductor 1 was obtained.

Examples 2-9
The process up to the formation of the charge transport layer was performed in the same manner as in Example 1.

  Next, in the formation of the protective layer, a photoconductor was prepared in the same manner as in Example 1 except that the type and amount of silsesquioxane of Example 1 and the ultraviolet curing conditions of the protective layer were changed as shown in Table 1. No. Photoconductors 2 to 9 were prepared.

  A comparative photoreceptor was prepared under the following conditions.

Comparative Example 1
The process up to the formation of the charge transport layer was performed in the same manner as in Example 1.

(Formation of comparative protective layer)
(Preparation of comparative protective layer coating solution 1)
M408 (ditrimethylolpropane tetraacrylate, manufactured by Toagosei Co., Ltd.) 1 part Photopolymerization initiator: Irgacure 369 (manufactured by Ciba Japan Co., Ltd.) 0.05 part Solvent: n-propanol 10 parts A layer coating solution 1 was prepared.

Using the prepared comparative protective layer coating solution 1 and coating on the charge transport layer by a circular amount-regulating coating method, drying at 110 ° C. for 20 minutes and using a pulsed UV irradiation device RC-500B manufactured by Xenon Photocuring was performed so that the integrated light amount was 10 J / cm ² , and a comparative photoconductor was prepared. A comparative photoreceptor 1 was obtained.

Example 10
The process up to the formation of the charge transport layer was performed in the same manner as in Example 1.

(Formation of protective layer)
(Preparation of protective layer coating solution 10)
Silsesquioxane (Exemplary Compound No. 9, t = 1) 3 parts Thermal polymerization initiator (dibenzoyl peroxide, manufactured by Kanto Chemical Co., Ltd.) 0.2 part Solvent: n-propanol 15 parts The above components are mixed and dissolved. A protective layer coating solution 10 was prepared.

  Using the prepared protective layer coating solution 10 and coating on the charge transport layer by a circular amount-regulating coating method, drying at 110 ° C. for 20 minutes, and 120 ° C. for 90 minutes with OVEN PH-201 made by Espec And a protective layer is formed to produce a photoconductor. Photoconductor 10 was obtained.

Examples 11-18
The process up to the formation of the charge transport layer was performed in the same manner as in Example 1.

  Next, in the formation of the protective layer, a photoconductor was prepared in the same manner as in Example 10 except that the type and amount of silsesquioxane of Example 10 and the thermosetting conditions of the protective layer were changed as shown in Table 2. No. Photoconductors 11 to 18 were used.

Comparative Example 2
The process up to the formation of the charge transport layer was performed in the same manner as in Example 1.

(Formation of protective layer)
(Preparation of comparative protective layer coating solution 2)
Epicoat 828 (Japan Epoxy Resin Co., Ltd.) 1 part Thermal polymerization initiator: Adeka Opton CP-66 (Asahi Denka Kogyo Co., Ltd.) 0.05 part Solvent: n-propanol 10 parts The above ingredients are mixed and dissolved. A comparative protective layer coating solution 2 was prepared. After using the prepared comparative protective layer coating solution 2 and coating on the charge transport layer by a circular amount-regulating coating method, it was dried at 110 ° C. for 20 minutes, and 120 ° C. with OVEN PH-201 manufactured by Espec Corporation. A 90-minute thermosetting is performed to form a protective layer to produce a photoreceptor. A comparative photoreceptor 2 was obtained.

Evaluation Each of the prepared photoreceptor Nos. In order to evaluate the durability and image quality of the photoconductors 1 to 18 and the comparative photoconductors 1 and 2, as representative characteristics, the hardness is evaluated as the protective layer, the image flow, the scratch resistance, and the wear resistance. Evaluation was performed according to the evaluation rank. The results are shown in Table 3.

(Method for evaluating hardness of protective layer)
For evaluation of film strength, Fischer Instruments (registered trademark) H100C manufactured by Fischer Instruments was used for each photoconductor, a Vickers indenter (square pyramid indenter, angle 136 °) was installed, and the indentation speed was 0.4 mN / sec. Universal hardness (HU) was measured under a load of 2 mN, a holding time of 5 seconds, a measurement environment of 23 ° C., and 60% RH.

(Image flow evaluation method)
Each photoconductor was mounted on a Kizina Minolta Business Technologies Co., Ltd. bizhub C352 modified machine, and 1000 A4 full-color images (each color printing rate of 1%) were printed continuously in a high-temperature, high-humidity environment (30 ° C, 85% RH). . Next, after standing for 8 hours, 10 character images with a printing rate of 5% were printed at A4, and the character images were visually evaluated according to the following criteria.

Evaluation rank of image flow: 1 to 10th image is good without image flow △: Image flow is at 1st image, but disappears at 10th image and has no practical problem ×: Image flow occurs even at 10th image (scratch resistance) Sex evaluation method)
Each photoconductor was mounted on a Kizina Minolta Business Technologies Co., Ltd. bizhub C352 modified machine, and 50,000 A4 full-color images (each color printing rate of 5%) were printed in a high-temperature, high-humidity environment (30 ° C, 85% RH). After that, an A3 full face halftone image was output. After the actual shooting test, the surface state of the photoreceptor and the halftone image were visually observed, and scratch resistance was evaluated according to the following evaluation rank.

  ◯: There is no noticeable scratch visually recognized on the surface of the photoreceptor, and no image defect corresponding to the photoreceptor scratch is recognized in the halftone image.

  Δ: Minor scratches are visually observed on the photoreceptor surface. In the halftone image, no image defect corresponding to the photoconductor scratch is recognized.

  X: A clear flaw is visually recognized on the surface of the photoreceptor. An image defect corresponding to the photoconductor scratch is observed in the halftone image.

(Abrasion resistance evaluation method)
Each photoconductor is mounted on a Konica Minolta Business Technologies multifunction machine bizhub C352, and 50,000 A4 full-color images (each color printing rate of 5%) are printed at room temperature and humidity (23 ° C, 60% RH). From the measurement of the film thickness of the photoreceptor before and after printing, the amount of wear of the protective layer was calculated and used as an index of wear resistance. When the wear amount was 3.5 μm or less, it was accepted, and when it was larger than 3.5 μm, it was rejected. The film thickness of the photoconductor was measured using a Fischer Scope (registered trademark) mms manufactured by Fischer Instruments.

  Photoconductors 1 to 3 in which a protective layer is formed using a photocurable ladder structure silsesquioxane compound, photoconductors 4 to 7 in which a protective layer is formed using a cage structure silsesquioxane compound, Photoconductor 8 in which a protective layer is formed by mixing a silsesquioxane compound having a ladder structure and a silsesquioxane compound having a cage structure, and a protective layer using a mixture of silsesquioxane compounds having different cage structures. As a comparison, the photoconductor 9 having a protective layer is compared with the comparative photoconductor 1 in which a protective layer is formed using a photocurable resin and the comparative photoconductor 2 in which a protective layer is formed using a thermosetting resin. It was confirmed that the layer hardness, image flow, scratch resistance, and abrasion resistance were excellent.

  Further, photoconductors 10 to 12 having a protective layer formed using a thermosetting ladder structure silsesquioxane compound, and photoconductors 13 to 13 having a protective layer formed using a silsesquioxane compound having a cage structure. 16. Ladder-structured silsesquioxane compound and cage-structured silsesquioxane compound are used to form a protective layer 17, and a mixture of different cage-structured silsesquioxane compounds is used. As a comparison, the photoconductor 18 having the protective layer formed thereon is compared with the comparative photoconductor 1 having a protective layer formed using a photocurable resin and the comparative photoconductor 2 having a protective layer formed using a thermosetting resin. In comparison, it was confirmed that the protective layer had excellent hardness, image flow, scratch resistance, and abrasion resistance.

  As described above, the effectiveness of the present invention was confirmed.

Example 19
The process up to the formation of the charge transport layer was performed in the same manner as in Example 1.

(Formation of protective layer)
(Preparation of protective layer coating solution 19)
Silsesquioxane (Exemplary Compound No. 1, t = 1) 2 parts Compound having organic group capable of reacting with silsesquioxane M402 (35:65 mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate: Toa Gosei Co., Ltd.) 2 parts Photopolymerization initiator: Irgacure 369 (Ciba Japan Co., Ltd.) 0.05 part Solvent: n-propanol 10 parts The above components are mixed and dissolved to prepare protective layer coating solution 19 did.

Using the prepared protective layer coating solution 19, it was coated on the charge transport layer by a circular amount-regulating coating method, dried at 110 ° C. for 20 minutes, and integrated using a pulsed UV irradiation apparatus RC-500B manufactured by Xenon. Photocuring was performed so that the amount of light was 10 J / cm ² , a protective layer was formed, and a photoconductor was prepared. Photoconductor 19 was obtained.

Examples 20-27
The process up to the formation of the charge transport layer was performed in the same manner as in Example 1.

  Next, in the formation of the protective layer, Table 4 shows the type and amount of the silsesquioxane of Example 19, the type and amount of the compound having an organic group that can react with the silsesquioxane, and the ultraviolet curing conditions of the protective layer. A photoconductor was prepared in the same manner as in Example 19 except that the procedure was changed as described above. Photoconductors 20 to 27 were produced.

Example 28
The process up to the formation of the charge transport layer was performed in the same manner as in Example 1.

(Formation of protective layer)
(Preparation of protective layer coating solution 28)
Silsesquioxane (Exemplary Compound No. 9, t = 1) 2 parts Compound having an organic group capable of reacting with silsesquioxane SR350 (trimethylolpropane trimethacrylate: manufactured by Sartomer) 2 parts Thermal polymerization initiator: Adeka Opton CP-66 (manufactured by Asahi Denka Kogyo Co., Ltd.) 0.05 part Solvent: 10 parts of n-propanol The above components were mixed and dissolved to prepare protective layer coating solution 28.

  Using the prepared protective layer coating solution 28, coating on the charge transport layer by a circular amount-regulating coating method, drying at 110 ° C. for 20 minutes, and 120 ° C. for 90 minutes with OVEN PH-201 manufactured by Espec. And a protective layer is formed to produce a photoconductor. Photoconductor 28 was obtained.

  28 was produced.

Examples 29-36
The process up to the formation of the charge transport layer was performed in the same manner as in Example 1.

  Next, in the formation of the protective layer, Table 5 shows the type and amount of the silsesquioxane of Example 28, the type and amount of the compound having an organic group capable of reacting with silsesquioxane, and the thermosetting conditions of the protective layer. A photoconductor was prepared in the same manner as in Example 28 except that the procedure was changed as described above. Photoconductors 29 to 36 were used.

Evaluation In order to evaluate the durability and image quality of the prepared photoconductors 19 to 35, the representative characteristics are the hardness of the protective layer, image flow, scratch resistance, and wear resistance, and are the same as the evaluation of the photoconductors 1 to 18. Evaluation was performed under conditions, and evaluation was performed according to the same evaluation rank as that of the photoconductors 1 to 18. The results are shown in Table 6.

  Photoconductors 19 to 27 having a protective layer formed using a compound having an organic group capable of reacting with a photocurable silsesquioxane, and a compound having an organic group capable of reacting with a thermosetting silsesquioxane. The photoconductors 28 to 35 having a protective layer formed by using the comparative photoconductor 1 and the thermosetting resin in which a protective layer is formed using a photocurable resin without using silsesquioxane for comparison. Thus, it was confirmed that the hardness, image flow, scratch resistance, and abrasion resistance of the protective layer were superior to those of the comparative photoreceptor 2 on which the protective layer was formed.

Claims (2)

In an electrophotographic photosensitive member in which a photosensitive layer and a protective layer are sequentially laminated on a conductive support,
A ladder-structured silsesquioxane reaction cured product represented by the following general formula (II) or a cage structure represented by any of the following general formulas (III), (IV), or (V) An electrophotographic photoreceptor comprising a reaction cured product of silsesquioxane .

(In the formula, R1 is a group represented by any of the following formula (13), formula (14), formula (15), formula (19), formula (20) and formula (22)), and t is 1 Represents an integer of ˜30.)

(U in Formula (13), Formula (14), Formula (15), Formula (19), Formula (20), and Formula (22)) represents an integer of 1 to 19. X3 in Formula (22) and X4 is a methyl group, an ethyl group or a phenyl group, and X3 and X4 may be the same.)

(R2 in the general formula (III) is a group represented by any one of the following formula (25), formula (26), formula (31), formula (32), and formula (36)). (IV) and R2 in the general formula (V) are groups represented by any of the following formulas (25) and (31).

(V in the formula (25), the formula (26), the formula (31), the formula (32), and the formula (36) represents an integer of 1 to 19. X5 and X6 in the formula (36) are methyl groups, It is an ethyl group or a phenyl group, and X5 and X6 may be the same.) In an electrophotographic photosensitive member in which a photosensitive layer and a protective layer are sequentially laminated on a conductive support,
A silsesquioxane having a ladder structure represented by the following general formula (II) or a silsesquioxane having a cage structure represented by any of the following general formulas (III), (IV), or (V) is provided in the protective layer. And a silsesquioxane having a ladder structure represented by the following general formula (II) or a silsesquioxane having a cage structure represented by any of the following general formulas (III), (IV), and (V): An electrophotographic photoreceptor comprising a reaction cured product with a compound having a reactive organic group.

(In the formula, R1 is a group represented by any of the following formula (13), formula (14), formula (15), formula (19), formula (20) and formula (22)), and t is 1 Represents an integer of ˜30.)

(U in Formula (13), Formula (14), Formula (15), Formula (19), Formula (20), and Formula (22)) represents an integer of 1 to 19. X3 in Formula (22) and X4 is a methyl group, an ethyl group or a phenyl group, and X3 and X4 may be the same.)

(R2 in the general formula (III) is a group represented by any one of the following formula (25), formula (26), formula (31), formula (32), and formula (36)). (IV) and R2 in the general formula (V) are groups represented by any of the following formulas (25) and (31).

(V in the formula (25), the formula (26), the formula (31), the formula (32), and the formula (36) represents an integer of 1 to 19. X5 and X6 in the formula (36) are methyl groups, It is an ethyl group or a phenyl group, and X5 and X6 may be the same.)