JP2012123238A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoreceptor having a small change amount of a surface potential even in repeated use, having no moisture memory phenomenon, and having high sensitivity and high durability with wear resistance.SOLUTION: The electrophotographic photoreceptor comprises at least a photosensitive layer and a protective layer, successively layered on a conductive support. The protective layer contains a polymerization product produced by using a compound (A) having 7 or more polymerizable functional groups, a compound (B) having 2 to 4 polymerizable functional groups and surface-treated metal oxide fine particles which are surface-treated with a surface treating agent having a polymerizable functional group. The photosensitive layer contains an adduct of butane diol and titanyl phthalocyanine. In the reflection spectrum of the photosensitive layer, a ratio of the reflectance at 700 nm to the reflectance at 780 nm is 0.8 or more and 1.3 or less.

Description

  The present invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member used in an electrophotographic image forming apparatus.

  In recent years, organic photoreceptors containing organic photoconductive materials have been widely used as electrophotographic photoreceptors. Organic photoconductors are advantageous for inorganic photoconductors because it is easy to develop materials compatible with various exposure light sources from visible light to infrared light, the ability to select materials without environmental pollution, and low manufacturing costs. Is a point.

  On the other hand, an electrophotographic photosensitive member (hereinafter also referred to as a photosensitive member) is directly charged with electrical or mechanical external force by charging, exposure, development, transfer, cleaning, etc., so that charging is stable even when image formation is repeated. The durability which maintains stably, such as a property and electric potential retention property is calculated | required.

  In recent years, especially in the digital trend, demand for high-definition and high-quality images has increased, and toners with small particle diameters by polymerization methods such as dissolved suspension toners and emulsion polymerization aggregation toners have become mainstream. The toner having a small particle size has a large adhesion force to the surface of the photoconductor, and the removal of residual toner such as transfer residual toner adhering to the surface of the photoconductor tends to be insufficient. In the cleaning method using a rubber blade, there are phenomena such as "toner slipping" where the toner passes through the blade, "blade curl" where the blade is reversed, or the generation of scratching noise between the photoconductor and the blade, so-called "blade squealing" Likely to happen. In order to solve the “toner slipping”, it is necessary to increase the contact pressure of the blade to the photosensitive member. However, the repeated use causes the problem that the surface of the organic photosensitive member is worn and the durability is insufficient. appear. Further, it is required to have sufficient durability against deterioration caused by ozone and nitrogen oxides generated during charging.

  For this reason, a technique for improving the mechanical strength by providing a protective layer on the surface of the photosensitive member has been proposed. Specifically, a polymerizable compound generally called a curable compound is used for the protective layer of the photoreceptor, and after coating, a curing reaction is performed, which is durable against surface abrasion and scratches caused by friction such as a cleaning blade. There has been proposed a technique for producing a photosensitive member having a certain property (see, for example, Patent Document 1).

  In addition, a technique using a monomer having three or more radical polymerizable groups in one molecule in order to improve the wear resistance of the protective layer is disclosed (for example, see Patent Document 2).

  Further, a technique has been proposed in which metal oxide fine particles such as silica are dispersed in a protective layer to improve mechanical strength (see, for example, Patent Document 3).

  On the other hand, a technique for reducing the surface energy of the surface of an electrophotographic photosensitive member has been proposed in order to impart a toner adhesion preventing function to the electrophotographic photosensitive member and excellent cleaning and transferability. As a technique for reducing the surface energy, a technique for adding a lubricant to the outermost protective layer of the electrophotographic photosensitive member has been proposed, and a technique for adding various fluororesins and silicone compounds as the lubricant is disclosed ( For example, see Patent Documents 4 and 5).

  Also disclosed is a technology that improves durability and image blur by introducing long-chain alkyl groups into the binder resin structure, thereby reducing surface friction resistance and preventing adhesion of ionic compounds that cause image quality degradation. (See, for example, Patent Document 6).

  On the other hand, as a charge generating material for realizing a high-sensitivity photoconductor, a titanyl phthalocyanine adduct of 2,3-butanediol having stereoregularity has been reported as having particularly excellent properties (for example, Patent Document 7). In particular, a titanyl phthalocyanine adduct of 2,3-butanediol and a mixed crystal of titanyl phthalocyanine have been reported as highly sensitive pigments (see, for example, Patent Document 8).

JP 11-288121 A JP 2009-251140 A JP 2002-333733 A JP-A-63-73267 JP-A-5-323646 JP 2008-146089 A Japanese Patent Laid-Open No. 8-82942 Japanese Patent Laid-Open No. 9-230615

  In order to improve the wear resistance and scratch resistance of the surface of an electrophotographic photoreceptor (hereinafter also referred to as a photoreceptor) and increase durability, it is effective to increase the crosslinking density of the polymerizable compound and increase the hardness of the surface protective layer. It is. In order to increase the crosslinking density and the hardness of the surface protective layer, it is considered effective to select a polymerizable compound having a large number of functional groups having a large number of polymerizable functional groups in the molecule.

  However, by providing a protective layer on the photoconductor, the wear resistance of the photoconductor is improved, but there is a drawback that the surface potential after exposure increases with repeated use. In order to suppress this increase in surface potential, it has been found that adding metal oxide fine particles to the protective layer is effective. Furthermore, by making the metal oxide fine particles into surface-treated metal oxide fine particles treated with a surface treatment agent having a polymerizable functional group, it is expected to crosslink the polymerizable compound and increase the coating strength of the protective layer.

  However, if the amount of the surface-treated metal oxide fine particles added is increased, an increase in the surface potential after exposure can be suppressed, but the protective layer becomes brittle and the film strength decreases. On the other hand, when the addition amount of the surface-treated metal oxide fine particles is reduced, the film strength of the protective layer is improved. However, the surface potential after exposure increases particularly under a low temperature and low humidity environment (LL) as it is repeatedly used. As described above, it has been extremely difficult to achieve both improvement in wear resistance and scratch resistance and prevention of increase in surface potential after exposure for enhancing the durability of the photoreceptor.

  The present invention has been made to solve the above problems, and provides a highly durable photoconductor having wear resistance and having a small amount of change in surface potential after exposure even when used repeatedly in a low temperature and low humidity environment. The purpose is that.

  It is another object of the present invention to provide a highly durable photoconductor that is free from humidity memory, has high sensitivity, and has wear resistance.

The above-described problems of the present invention are solved by the following configuration.
1.
In the electrophotographic photosensitive member formed by sequentially laminating at least a photosensitive layer and a protective layer on a conductive support, the protective layer comprises a compound (A) having 7 or more polymerizable functional groups and 2 polymerizable functional groups. A polymerization product produced using a compound (B) having at least 4 and at least 4 and a surface-treated metal oxide fine particle surface-treated with a surface-treating agent having a polymerizable functional group, and the photosensitive layer comprises It contains an adduct of 2,3-butanediol and titanyl phthalocyanine, and the ratio of the reflectance at 700 nm (R700) and the reflectance at 780 nm (R780) of the reflection spectrum of the photosensitive layer (R700 / R780). ) Is 0.8 or more and 1.3 or less.

However, the reflectance is a reflectance measured by forming a photosensitive layer (charge generation layer) on an aluminum support, and is a relative reflectance when the reflectance of the aluminum support is 100%.
2.
The polymerization product is prepared by setting the total of the compound (A) and the compound (B) to 100 parts by mass and the surface-treated metal oxide fine particles from 50 parts by mass to 250 parts by mass. 2. The electrophotographic photosensitive member as described in 1 above.
3.
3. The electrophotographic photoreceptor as described in 1 or 2 above, wherein the compound (A) having 7 or more polymerizable functional groups has 10 or less polymerizable functional groups.

  By adopting the above configuration, the present invention is excellent in wear resistance even when used repeatedly, and has a small potential change even when used repeatedly in a low temperature and low humidity environment. It is possible to provide a high-sensitivity and high-durability photoconductor that does not generate any environmental dependency.

FIG. 3 is a schematic diagram illustrating an example of a layer configuration of a photoreceptor according to the present invention. It is an example of the reflection spectrum of the photosensitive layer containing 2, 3- butanediol adduct titanyl phthalocyanine, (a) represents the reflection spectrum figure of R700 / R780 = 0.93, (b) represents R700 / R780 = 0. .72 represents a reflection spectrum diagram. In the X-ray diffraction spectrum of 2,3-butanediol adduct titanyl phthalocyanine, (1) (9.5 ° type) phthalocyanine having a characteristic peak at a Bragg angle 2θ (± 0.2 °) of 9.5 ° (2) Spectra of phthalocyanine (8.3 ° type) having a characteristic peak at 8.3 °. 1 is an example of a cross-sectional configuration diagram of a color image forming apparatus using an electrophotographic photosensitive member of the present invention. A spectrum diagram of Y-type titanyl phthalocyanine having a characteristic peak at a Bragg angle 2θ (± 0.2 °) of 27.2 ° in an X-ray diffraction spectrum.

  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 protective layer has a compound (A) having 7 or more polymerizable functional groups (hereinafter polymerizable compound (A). And a polymerization product of a compound (B) having 2 or more and 4 or less polymerizable functional groups (hereinafter also referred to as a polymerizable compound (B)). If only the compound (A) having 7 or more polymerizable functional groups is used, some polymerizable functional groups remain unreacted due to steric hindrance. Therefore, since the crosslinking density does not increase and a protective layer having insufficient film strength and sufficient film strength cannot be obtained, durability is inferior. Therefore, the crosslinking density is increased by adding a polymerizable compound having a small number of polymerizable functional groups, that is, a compound (B) having 2 to 4 polymerizable functional groups so that unreacted polymerizable functional groups do not remain. is there. That is, a polymerizable compound having a small number of polymerizable functional groups is less susceptible to steric hindrance because of its low molecular weight, so that no unreacted polymerizable functional groups remain, thereby increasing the crosslinking density and increasing the hardness. It is considered that a protective layer having film strength can be obtained.

  Further, the present invention contains surface-treated metal oxide fine particles (hereinafter also referred to as surface-treated metal oxide fine particles) that have been treated with a surface treatment agent having a polymerizable functional group for the purpose of improving the potential characteristics of the photoreceptor. The surface-treated metal oxide fine particles are added for the purpose of suppressing an increase in surface potential after exposure when repeatedly used, but by using metal oxide fine particles treated with a surface treatment agent having a polymerizable functional group, It also has an effect of improving abrasion resistance by crosslinking with the polymerizable compound. However, conventionally, when an amount capable of sufficiently improving the potential characteristic is added, the brittleness of the protective layer is increased, the film strength is lowered, and the wear resistance is inferior. However, in the present invention, by adding two kinds of polymerizable compounds as described above, unreacted polymerizable functional groups can be reduced and the crosslink density of the protective layer can be increased. This makes it possible to increase the amount of addition until a sufficient improvement in potential characteristics is obtained while maintaining the wear resistance. In the present invention, the protective layer having the above-described structure makes it possible to obtain a highly durable photoconductor that is excellent in wear resistance and has little change in potential characteristics even after repeated use.

  Furthermore, in the present invention, by using an adduct of 2,3-butanediol and titanyl phthalocyanine (hereinafter sometimes simply referred to as 2,3-butanediol adduct titanyl phthalocyanine or butanediol adduct) in the photosensitive layer, There is no generation of humidity memory, and the photoconductor can be highly sensitive and less dependent on the environment.

  By adopting the above-described configuration, the present invention has no environmental dependency that could not be obtained with the prior art, has little change in potential characteristics even after repeated use, has no humidity memory, and has high sensitivity and high durability. It has become possible to provide an electrophotographic photoreceptor.

  Hereinafter, the configuration of the present invention will be described in more detail.

<Polymerizable compound (A)>
Examples of the compound (A) having 7 or more polymerizable functional groups used in the present invention include tripentaerythritol octamethacrylate, tripentaerythritol heptamethacrylate, tripentaerythritol octaacrylate, tetrapentaerythritol decamethacrylate, tetrapentaerythritol decaacrylate. Multi-functional acrylates or methacrylates of tripentaerythritol or tetrapentaerythritol are preferably used.

  Here, the above-mentioned polyfunctional acrylate or methacrylate means a plurality (seven or more) of acrylate groups or methacrylate groups, for example, by a condensation reaction of tripentaerythritol or tetrapentaerythritol and acrylic acid or methacrylic acid. The polyfunctional acrylate or methacrylate produced | generated is said. The number of polymerizable functional groups is preferably 7 or more and 10 or less.

  By setting the number of polymerizable functional groups to 7 or more and 10 or less, the crosslink density is increased and a protective layer having high coating strength can be obtained.

  Specific examples of the polymerizable compound (A) used in the present invention are illustrated below, but the polymerizable compound (A) used in the present invention is not limited thereto.

  Exemplary compounds

  Among the above exemplary compounds, R and R ′ are acryloyl groups and methacryloyl groups represented by the following structures.

  In the present invention, the polymerizable compound (A) may be used alone or in combination of two or more. Moreover, 10 mass% or more and 95 mass% or less are preferable among polymerization compound (A) and (B) total, and the addition amount of polymeric compound (A) has more preferable 20 mass% or more and 90 mass% or less. If it is 10% by mass or less, sufficient film strength may not be obtained, and if it is 95% by mass or more, unreacted polymerizable functional groups may remain and sufficient abrasion resistance may not be obtained.

  The polymerizable compound (A) of the present invention can be synthesized by a known method.

<Polymerizable compound (B)>
The compound (B) having 2 to 4 polymerizable functional groups used in the present invention preferably has a functional group equivalent (molecular weight / number of polymerizable functional groups) of 60 to 300, more preferably 70 to 150. Further, acrylates or methacrylates having 2 to 4 functional groups of pentaerythritol or dipentaerythritol are preferable.

  When the number of polymerizable functional groups is one, a crosslinked structure cannot be obtained, and when it is five or more, there is a possibility that the reactivity is poor and the crosslinking density does not increase.

  Specific examples of the compound (B) having 2 or more and 4 or less polymerizable functional groups used in the present invention can include the following compounds, but the polymerizable compound (B) used in the present invention is these. It is not limited to.

  Exemplary compounds

  In the present invention, the polymerizable compound (B) may be used alone or in combination of two or more. The addition amount of the polymerizable compound (B) is preferably 5% by mass or more and 90% by mass or less, more preferably 10% by mass or more and 80% by mass or less in the total of the polymerizable compounds (A) and (B). If it is 5% by mass or less, unreacted polymerizable functional groups may remain, and if it is 90% by mass or more, sufficient wear resistance may not be obtained and durability may be deteriorated.

  About the polymeric compound (B) of this invention, a commercial item can be obtained, for example, brand names, such as SR-351S (m-4) and SR-350 (m-1) by Kayaku Sartomer Co., Ltd. It is sold at. Other polymerizable compounds can be synthesized by a known synthesis method of a general photocurable monomer.

  In the present invention, by using at least two kinds of polymerizable compounds (A) and polymerizable compounds (B), a protective layer having a high crosslink density and wear resistance can be obtained.

<Surface treated metal oxide fine particles>
The protective layer of the present invention contains surface-treated metal oxide fine particles that have been surface-treated with a surface treatment agent having a polymerizable functional group.

  The metal oxide fine particles of the present invention are added for the purpose of improving the mechanical strength of the protective layer, and at the same time, have the effect of suppressing an increase in surface potential after exposure when the photoreceptor is used repeatedly. When the surface potential after exposure rises, the difference between the surface potential of the unexposed area and the exposed area becomes small, and the image density gradually decreases in the image formation by the reversal development method generally performed in a digital copying machine. It causes a defect.

  Furthermore, by subjecting the metal oxide fine particles to a surface treatment with a polymerizable functional group, a crosslinking reaction occurs with the polymerizable compound (A) and the polymerizable compound (B) of the present invention, thereby providing a denser protective film. Thus, the wear resistance is improved and the potential fluctuation can be minimized, so that the durability of the photoreceptor can be greatly improved.

  The metal oxide fine particles used in the protective layer of the present invention are preferably metal oxide fine particles including transition metals. For example, silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, aluminum oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, Examples of the metal oxide fine particles include germanium oxide, tin oxide, titanium oxide, niobium oxide, molybdenum oxide, and vanadium oxide. Among these, particles such as titanium oxide, alumina, zinc oxide, and tin oxide are preferable.

  The metal oxide fine particles are preferably prepared by a known production method, for example, a general production method such as a gas phase method, a chlorine method, a sulfuric acid method, a plasma method, or an electrolytic method.

  The number average primary particle size of the metal oxide fine particles is preferably in the range of 1 to 300 nm. Especially preferably, it is 3-100 nm.

  The number average primary particle size of the metal oxide fine particles is a photographic image (excluding aggregated particles) obtained by taking an enlarged photograph of 10,000 times with a scanning electron microscope (manufactured by JEOL Ltd.) and randomly capturing 300 particles with a scanner. A) automatic image processing analyzer LUZEX AP (Nireco Corp.) software version Ver. The number average primary particle size was calculated using 1.32.

  The surface treatment agent having a polymerizable functional group used for the surface treatment of the metal oxide fine particles may be any surface treatment agent having reactivity with a hydroxyl group or the like present on the surface of the metal oxide fine particles. Examples thereof include a silane coupling agent having a functional group. As the polymerizable functional group, a vinyl group, an acryloyl group, and a methacryloyl group are preferable, and examples of the surface treatment agent having such a polymerizable functional group include compounds exemplified below.

_{S-1: CH 2 = CHSi} (CH 3) (OCH 3) 2
_{S-2: CH 2 = CHSi} (OCH 3) 3
S-3: CH ₂ = CHSiCl _{3
S-4: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5: CH 2 = CHCOO} (CH 2) 2 Si (OCH 3) 3
_{S-6: CH 2 = CHCOO} (CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
_{S-7: CH 2 = CHCOO} (CH 2) 3 Si (OCH 3) 3
_{S-8: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) Cl 2
_{S-9: CH 2 = CHCOO} (CH 2) 2 SiCl 3
_{S-10: CH 2 = CHCOO} (CH 2) 3 Si (CH 3) Cl 2
S-11: CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13: CH 2 = C} (CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17: CH 2 = C} (CH 3) COO (CH 2) 2 SiCl 3
_{S-18: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19: CH 2 = C} (CH 3) COO (CH 2) 3 SiCl 3
_{S-20: CH 2 = CHSi} (C 2 H 5) (OCH 3) 2
_{S-21: CH 2 = C} (CH 3) Si (OCH 3) 3
_{S-22: CH 2 = C} (CH 3) Si (OC 2 H 5) 3
_{S-23: CH 2 = CHSi} (OCH 3) 3
_{S-24: CH 2 = C} (CH 3) Si (CH 3) (OCH 3) 2
_{S-25: CH 2 = CHSi} (CH 3) Cl 2
_{S-26: CH 2 = CHCOOSi} (OCH 3) 3
_{S-27: CH 2 = CHCOOSi} (OC 2 H 5) 3
_{S-28: CH 2 = C} (CH 3) COOSi (OCH 3) 3
_{S-29: CH 2 = C} (CH 3) COOSi (OC 2 H 5) 3
_{S-30: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
_{S-31: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) 2 (OCH 3)
_{S-32: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCOCH 3) 2
_{S-33: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (ONHCH 3) 2
_{S-34: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OC 6 H 5) 2
_{S-35: CH 2 = CHCOO} (CH 2) 2 Si (C 10 H 21) (OCH 3) 2
_{S-36: CH 2 = CHCOO} (CH 2) 2 Si (CH 2 C 6 H 5) (OCH 3) 2
Moreover, as a surface treating agent, you may use the silane compound which has the reactive organic group which can be radically polymerized other than said S-1 to S-36. The polymerizable functional group of these surface treatment agents is a strong protective film that undergoes a crosslinking reaction with the compound (A) having 7 or more polymerizable functional groups and the compound (B) having 2 to 4 polymerizable functional groups. Can be formed.

  The amount of the surface-treated metal oxide fine particles is preferably 50 to 250 parts by mass with respect to 100 parts by mass in total of the polymerizable compounds (A) and (B).

  When the surface-treated metal oxide fine particles are 50 parts by mass or more, the electrical resistance of the protective layer does not become excessively high, and the increase in residual potential and fogging can be prevented. Can be secured. These surface treatment agents can be used alone or in admixture of two or more.

[Preparation of surface-treated metal oxide fine particles]
In carrying out the surface treatment, it is preferable to treat the surface treatment agent using 0.1 to 100 parts by weight of the metal oxide fine particles and 100 to 50 parts by weight of the solvent and 50 to 5000 parts by weight of the solvent using a wet media dispersion type apparatus. . Moreover, it can also process by a dry type.

  Hereinafter, a surface treatment method for producing metal oxide fine particles uniformly surface-treated with a surface treatment agent will be described.

  That is, by subjecting a slurry (suspension of solid particles) containing metal oxide fine particles and a surface treatment agent to wet pulverization, the metal oxide fine particles are refined and at the same time the surface treatment of the fine particles proceeds. Then, the metal oxide fine particles surface-treated with the surface treatment agent can be obtained uniformly by removing the solvent and pulverizing.

  The wet media dispersion type apparatus, which is a surface treatment apparatus used in the present invention, is filled with beads as a medium in a container, and further rotated at high speed a stirring disk attached perpendicularly to the rotation axis, thereby forming a metal oxide. It is an apparatus having a step of crushing and pulverizing / dispersing the aggregated particles, and the configuration is such that the metal oxide fine particles are sufficiently dispersed when the surface treatment is performed on the metal oxide fine particles and the surface treatment can be performed. For example, various types such as a vertical type, a horizontal type, a continuous type, and a batch type can be adopted without any problem. Specifically, a sand mill, ultra visco mill, pearl mill, glen mill, dyno mill, agitator mill, dynamic mill and the like can be used. These dispersion-type devices are pulverized and dispersed by impact crushing, friction, shearing, shear stress, etc., using a grinding medium (media) such as balls and beads.

  As the beads used in the wet media dispersion type apparatus, a pulverizing medium made of glass, alumina, zircon, zirconia, steel, flint stone or the like can be used, but those made of zirconia or zircon are particularly preferable. Further, as the size of the beads, those having a diameter of about 1 to 2 mm are usually used, but in the present invention, those having a diameter of about 0.1 to 1.0 mm are preferably used.

  Various materials such as stainless steel, nylon and ceramic can be used for the disk and container inner wall used in the wet media dispersion type apparatus. In the present invention, the disk and container inner wall made of ceramic such as zirconia or silicon carbide are particularly used. Is preferred.

  By the wet treatment as described above, metal oxide fine particles having a reactive organic group capable of reacting with a reactive acryloyl group and a reactive methacryloyl group can be obtained by surface treatment with a surface treating agent.

  Furthermore, the protective layer according to the present invention can be formed by using a known resin together with the compound obtained by the reaction. Known resins include polyester resins, polycarbonate resins, polyurethane resins, acrylic resins, epoxy resins, silicone resins, alkyd resins, and the like. In addition to these, the protective layer according to the present invention may be formed by containing a polymerization initiator, a filler, lubricant particles and the like as necessary.

<Polymerization product>
The polymerization product constituting the protective layer of the present invention is obtained by coating a coating solution containing a polymerizable compound (A), a polymerizable compound (B), and surface-treated metal oxide fine particles on the photosensitive layer. After forming, it is produced by a curing reaction. The curing reaction can be performed by a method using an electron beam cleavage reaction or a method using a radical polymerization initiator in the presence of light or heat. When the curing reaction is performed using a radical polymerization initiator, any of a photopolymerization initiator and a thermal polymerization initiator can be used as the polymerization initiator. Further, both light and heat initiators can be used in combination.

(Polymerization initiator)
Examples of the polymerization initiator that can be used in the present invention include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylazobisvaleronyl), 2,2′-azobis (2 Azo compounds such as -methylbutyronitrile), benzoyl peroxide (BPO), di-tert-butyl hydroperoxide, tert-butyl hydroperoxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, peroxide Examples thereof include thermal polymerization initiators such as peroxides such as lauroyl.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (Irgacure 369: manufactured by BASF Japan Ltd.), 2-hydroxy-2-methyl -1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, etc. Acetophenone or ketal photoinitiators, benzoin, benzoin methyl ether, Benzoin ether photopolymerization initiators such as zoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl Benzophenone photopolymerization initiators such as ether, acrylated benzophenone, 1,4-benzoylbenzene, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichloro Examples thereof include thioxanthone photopolymerization initiators such as thioxanthone.

  Other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine Oxide (Irgacure 819: manufactured by BASF Japan), bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine And imidazole compounds. 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.

  The polymerization initiator used in the present invention is preferably a photopolymerization initiator, preferably an alkylphenone compound or a phosphine oxide compound, more preferably an initiator having an α-hydroxyacetophenone structure or an acylphosphine oxide structure. preferable.

  These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.1-40 mass parts with respect to 100 mass parts of polymeric compounds, Preferably it is 0.5-20 mass parts.

[Lubricant particles]
It is also possible to contain various lubricant particles in the protective layer. For example, fluorine atom-containing resin fine particles can be added. Fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluorochloroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these One or two or more types are preferably selected from the copolymers, but tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

〔solvent〕
Solvents used for forming the protective layer include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methyl ethyl ketone, cyclohexane, ethyl acetate, Examples thereof include, but are not limited to, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1,3-dioxane, 1,3-dioxolane, pyridine and diethylamine.

(Formation of protective layer)
The protective layer is a photosensitive layer prepared by adding a coating solution prepared by adding a polymerizable compound, surface-treated metal oxide fine particles, and a known resin, a polymerization initiator, a lubricant particle, an antioxidant, and the like, if necessary. It can be prepared by applying to the surface, performing natural drying or heat drying, and then curing.

  As a coating method, a known method such as a dip coating method or a circular amount regulation type coating method can be used. Here, the circular amount regulation type coating method is most preferable.

  The thickness of the protective layer is preferably 0.2 to 10 μm, and more preferably 0.5 to 6 μm.

  In the present invention, the protective layer is cured by irradiating the coating film with active rays to generate radicals and polymerize, and then cure by forming a cross-linking bond between the molecules and within the molecule to form a cured resin. It is preferable to do. The active ray is preferably light such as ultraviolet light or visible light, or an electron beam, and ultraviolet light is particularly preferred from the standpoint of ease of use.

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, a flash (pulse) xenon, an ultraviolet LED, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 1 to 20 mJ / cm ² , preferably 5 to 15 mJ / cm ² . The output voltage of the light source is preferably 0.1 to 5 kW, and particularly preferably 0.5 to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.005 Gy to 100 kGy (0.5 to 10 Mrad).

  The irradiation time of the active ray is a time for obtaining the necessary irradiation amount of the active ray, specifically 0.1 seconds to 10 minutes is preferable, and 1 second to 5 minutes is more preferable from the viewpoint of curing efficiency or work efficiency. It is said.

  In the present invention, the protective layer can be dried before and after irradiation with active rays and during irradiation with active rays, and the timing of drying can be appropriately selected in combination with the irradiation conditions of active rays. The drying conditions for the protective layer can be appropriately selected depending on the type of solvent used in the coating solution and the thickness of the protective layer. The drying temperature is preferably from room temperature to 180 ° C, particularly preferably from 80 ° C to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes to 100 minutes.

<Butanediol adduct titanyl phthalocyanine>
The adduct of 2,3-butanediol and titanyl phthalocyanine used in the photosensitive layer of the present invention is titanyl phthalocyanine and (2R, 3R) -2,3-butanediol or (2S, 3S) -2,3- It can be obtained by reacting at least one of butanediol (hereinafter also referred to as a butanediol compound).

  The 2,3-butanediol adduct titanyl phthalocyanine of the present invention has two crystal forms depending on the difference in the addition ratio of butanediol.

  When titanyl phthalocyanine is excessively reacted with (2R, 3R) -2,3-butanediol or (2S, 3S) -2,3-butanediol, an X-ray diffraction spectrum shows a Bragg angle 2θ ( ± 0.2 °): A pigment having a characteristic peak at 9.5 ° (hereinafter abbreviated as 9.5 ° type) is obtained as shown in FIG. The 9.5 type butanediol-added titanyl phthalocyanine raw pigment has peaks at 16.4 °, 19.1 °, 24.7 °, and 26.5 ° in addition to 9.5.

Structure of the pigment Ti = O absorption near 970 cm ^-1 in the IR spectrum disappeared, 630 cm ^-1 of the absorption of the O-Ti-O appears in the vicinity about the 390 to 410 ° C. in a thermal analysis (TG) 11 % Mass loss (possibly due to the elimination of butylene oxide by thermal decomposition), and from the results of mass spectrometry, titanyl phthalocyanine and (2R, 3R) -2,3-butanediol or (2S, 3S ) -2,3-butanediol is considered to have a dehydration condensation ratio of 1: 1.

On the other hand, when a butanediol compound is reacted at 1 mol or less with respect to 1 mol of titanyl phthalocyanine, the powder X-ray diffraction spectrum has a characteristic peak at a Bragg angle 2θ: 8.3 ° (± 0.2 °) ( Hereinafter, the pigment shown in FIG. 3 (2) is obtained. The 8.3 ° butanediol-added titanyl phthalocyanine pigment has peaks at 24.7 °, 25.1 °, and 26.5 ° in addition to 8.3 °. The pigment shows both absorption of Ti = O near 970 cm ⁻¹ and O—Ti—O near 630 cm ⁻¹ in the IR spectrum. In addition, from the result of mass analysis that the mass loss is less than 11% at 390 to 410 ° C. by thermal analysis and from the result of mass analysis, butanediol / titanyl phthalocyanine = 1/1 adduct and titanyl phthalocyanine are mixed at a certain ratio ( It is simply assumed that two or more compounds are mixed in one pigment particle. The butanediol addition ratio is estimated to be 40 to 70 mol% from the mass loss of 390 to 410 ° C. in the thermal analysis.

  In the X-ray diffraction spectrum, the characteristic peak means a clearly different peak exceeding the background variation.

  In the present invention, the pigment has a characteristic peak at least at a Bragg angle (2θ ± 0.2 °) of 8.3 ° in the X-ray diffraction spectrum in that good sensitivity and repeated potential stability can be obtained. It is more preferable to use the 8.3 ° type.

[Method for producing 2,3-butanediol adduct titanyl phthalocyanine pigment]
A pigment containing an adduct of the titanyl phthalocyanine of the present invention and at least one of (2R, 3R) -2,3-butanediol or (2S, 3S) -2,3-butanediol is composed of titanyl phthalocyanine and (2R, It can be synthesized by reacting 3R) -2,3-butanediol or (2S, 3S) -2,3-butanediol in various solvents at room temperature or under heating. The starting material titanyl phthalocyanine is generally known, such as a synthesis method obtained from phthalonitrile and titanium tetrachloride, a synthesis method obtained from diiminoisoindoline and alkoxy titanium, a synthesis method obtained from phthalonitrile, urea and alkoxy titanium. Any synthetic method can be used, but high purity titanyl phthalocyanine with low chlorine content obtained from diiminoisoindoline and alkoxytitanium is particularly preferable. The titanyl phthalocyanine is preferably made amorphous by a method such as acid paste treatment and then reacted with a butanediol compound. In the addition reaction between amorphous titanyl phthalocyanine and a butanediol compound, usually 5 to 30 times the solvent is used. The solvent is not particularly limited, and aromatic solvents such as chlorobenzene, dichlorobenzene, anisole, chloronaphthalene and quinoline to ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and acetophenone, ether solvents such as tetrahydrofuran, dioxolane and diglyme, Furthermore, there can be mentioned a large number of aprotic polar solvents such as dimethylformamide, dimethylacetamide and dimethylsulfoxide, other halogen-based solvents and ester-based solvents.

The reaction of titanyl phthalocyanine and a butanediol compound is shown in the following reaction formula (1), but it can be carried out under a wide range of temperature conditions, the reaction temperature is preferably in the range of 25 to 300 ° C., and the BET specific surface area is 20 m ² / In order to synthesize a pigment of g or more, it is more preferably in the range of 30 to 100 ° C.

  Of the above, the reaction solvent is particularly preferably o-dichlorobenzene, and after hydrolysis, the reaction solvent is preferably replaced with alcohol or a mixed solvent of alcohol and water, and dried slowly at room temperature to 70 ° C. The ratio of alcohol and water at this time is preferably 0 to 100 parts by mass of water with respect to 100 parts by mass of methanol. As the alcohol, methanol, ethanol, propanol and butanol are preferable.

  The butanediol compound is usually added at a ratio of 0.2 to 2.0 mol with respect to 1 mol of titanyl phthalocyanine. In order to be an equimolar adduct, the diol compound must be used in an amount of 1.0 mol or more. When the diol compound is added in an amount of 1.0 mol or less in the above ratio, the obtained adduct becomes a mixed crystal with titanyl phthalocyanine. As long as the dispersion absorption of the present invention is satisfied, mixed crystals also fall within the scope of the present invention.

  Furthermore, it is preferable to treat the reaction product of titanyl phthalocyanine and a butanediol compound in a solvent in the presence of water. By performing the water treatment, a mixed crystal pigment containing 2,3-butanediol adduct titanyl phthalocyanine having a thermally stable diol addition ratio can be stably obtained.

  The 2,3-butanediol adduct titanyl phthalocyanine pigment obtained as described above has high sensitivity, excellent potential stability, is not dependent on humidity such as humidity memory, and has extremely excellent electrophotographic characteristics. .

[Dispersion of 2,3-butanediol adduct titanyl phthalocyanine pigment]
In order to make a dispersion liquid such as a charge generation layer using the pigment of the present invention (a pigment containing titanyl phthalocyanine and 2,3-butanediol adduct titanyl phthalocyanine), these pigments are dispersed in a solvent. There are no particular restrictions on the solvent, and ketone solvents such as methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, cyclohexanone, and acetophenone, ether solvents such as tetrahydrofuran, dioxolane, and diglyme, and alcohol solvents such as methyl cellosolve, ethyl cellosolve, and butanol Examples include many solvents such as solvents, ester solvents such as ethyl acetate and t-butyl acetate, aromatic solvents such as toluene and chlorobenzene, and halogen solvents such as dichloroethane and trichloroethane.

  A binder can be added to the dispersion. The binder can be selected widely as long as it is soluble in the solvent used. Examples include polyvinyl butyral, polyvinyl formal, polyvinyl acetate, polyvinyl chloride, polyamide, polycarbonate, polyester, and copolymers thereof. The ratio of the binder and the pigment is not particularly limited, but is usually 1/10 to 10/1. When the amount of the binder is small, the dispersion becomes unstable, and when the amount is too large, the electric resistance is increased, and when the electrophotographic photosensitive member is formed, the residual potential tends to increase repeatedly.

  The dispersion means preferably used in the present invention is the above-described low shear dispersion (low shear dispersion). Examples of the low shear dispersion include ultrasonic dispersion and media having a small specific gravity (glass (specific gravity: 2.5) beads. Etc.) is preferable.

  As an indicator of the dispersion state, the ratio of the reflection spectrum of the charge generation layer (R700 / R780) needs to be in the range of 0.8 to 1.3. Control of the ratio (R700 / R780) of these reflection spectra can be performed by adjusting the share applied to the dispersion during dispersion. Specifically, it can be controlled by the dispersion method, the diameter and amount of media used during dispersion, the dispersion time, and the like. The ratio of the reflection spectrum (R700 / R780) is shown in FIG.

  In the dispersion of the pigment of the present invention, the reflectance near 780 nm increases and the ratio (R700 / R780) decreases as the dispersion of secondary aggregation and the crushing of crystals progress.

  When the ratio (R700 / R780) is less than 0.8, it indicates that the pigment crystal was crushed due to excessive dispersion share, and the 2,3-butanediol adduct titanyl phthalocyanine tends to be decomposed at the defective portion of the crystal. As a result, sensitivity and repetitive characteristics deteriorate.

  On the other hand, when the ratio (R700 / R780) exceeds 1.3, it indicates that secondary aggregated particles or coarse particles with poor dispersion are present, and image defects such as a decrease in image density occur.

  In the present invention, the reflection spectrum of the photosensitive layer is measured with a sample in which a charge generation layer is formed on an aluminum support with a dry film thickness of 0.3 μm. The reflection spectrum is measured as a relative reflectance when the reflectance of the aluminum support is 100%. In order to remove irregularities due to interference fringes in the obtained reflection spectrum, the measurement data is approximated by a second order polynomial in the range of 685 to 715 nm and 765 to 795 nm, and the reflectance (R700) and reflectance (R780) are calculated. The ratio (R700 / R780) is calculated.

  The reflection spectrum was measured using an optical film thickness measuring device “Solid Lambda Thickness (Spectra Corp.)”.

<Production of photoconductor>
In producing the electrophotographic photoreceptor of the present invention, known techniques of organic photoreceptors can be used as they are. Hereinafter, the constitution of the organic photoreceptor used in the present invention will be described.

  In the present invention, the organic photoconductor means an electrophotographic photoconductor constituted by providing an organic compound with at least one of a charge generation function and a charge transport function essential to the configuration of the electrophotographic photoconductor. All known organic electrophotographic photoreceptors such as a photoreceptor composed of the above organic charge generating substance or organic charge transporting substance, a photoreceptor composed of a polymer complex with a charge generating function and a charge transporting function are contained.

The layer structure of the organic photoreceptor is not particularly limited, but examples include the following.
(1) Layer structure in which a photosensitive layer (charge generation layer and charge transport layer) and a protective layer are sequentially laminated on a conductive support. (2) A photosensitive layer (charge transport material and charge) on a conductive support. A single layer containing a generation material), and a layer structure in which a protective layer is sequentially laminated. (3) An intermediate layer, a photosensitive layer (a charge generation layer and a charge transport layer), and a protective layer are formed on a conductive support. Layer structure sequentially laminated (4) Layer structure in which an intermediate layer, a photosensitive layer (a single layer containing a charge transporting material and a charge generating material), and a protective layer are sequentially laminated on a conductive support. The body may have any one of the above-mentioned layer configurations (1) to (4). Among these, an intermediate layer, a photosensitive layer (a charge generation layer and a charge transport layer), and a protective layer are sequentially formed on a conductive support. A layer structure prepared by providing is particularly preferable.

  Hereinafter, a specific configuration of the photoreceptor used in the present invention will be described. An example of the layer structure is shown in FIG.

[Conductive support]
As the conductive support used in the photoreceptor of the present invention, a sheet-like or cylindrical conductive support is used.

  The cylindrical conductive support of the present invention means a cylindrical support that needs to be endlessly imaged by rotating, and has a straightness of 0.1 mm or less and a deflection of 0.1 mm or less. A conductive support is preferred. Exceeding the range of straightness and shake makes it difficult to form a good image.

As a material for the conductive support, a metal drum such as aluminum or nickel, a plastic drum on which aluminum, tin oxide, indium oxide or the like is deposited, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ω · cm or less at room temperature.

  As the conductive support used in the present invention, one having an alumite film that has been sealed on the surface thereof may be used. The alumite treatment is usually performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodizing in sulfuric acid, the sulfuric acid concentration is preferably 100 to 200 g / l, the aluminum ion concentration is 1 to 10 g / l, the liquid temperature is about 20 ° C., and the applied voltage is preferably about 20 V. It is not limited. The average film thickness of the anodized film is usually 20 μm or less, particularly preferably 10 μm or less.

[Middle layer]
In the present invention, an intermediate layer having a barrier function is preferably provided between the conductive support and the photosensitive layer, and particularly an intermediate layer in which titanium oxide particles are dispersed and contained in a binder resin such as polyamide is preferable. The average particle diameter of the titanium oxide particles is preferably in the range of 10 nm to 400 nm in terms of number average primary particle diameter, and is preferably 15 nm to 200 nm. If it is less than 10 nm, the effect of preventing the occurrence of moire by the intermediate layer is small. On the other hand, if it is larger than 400 nm, the titanium oxide particles in the intermediate layer coating solution are likely to settle, and as a result, the uniform dispersibility of the titanium oxide particles in the intermediate layer is poor, and the black spots are likely to increase. An intermediate layer coating liquid using titanium oxide particles having a number average primary particle size in the above range has good dispersion stability, and the intermediate layer formed from such a coating liquid has an environmental characteristic in addition to the function of preventing the occurrence of black spots. Is good and has cracking resistance.

  The shape of the titanium oxide particles used in the present invention includes a dendritic shape, a needle shape, a granular shape, and the like. The titanium oxide particles having such a shape are, for example, titanium oxide particles, anatase type, rutile as crystal types. There are types, amorphous types, and the like. Any crystal type may be used, or two or more crystal types may be mixed and used. Among them, the rutile type and granular type are the best.

  The titanium oxide particles of the present invention are preferably surface-treated. Among these, it is preferable to perform a plurality of surface treatments, and among the plurality of surface treatments, the last surface treatment is a surface treatment using a reactive organosilicon compound. In addition, at least one of the surface treatments is at least one surface treatment selected from alumina, silica, and zirconia, and finally a surface treatment using a reactive organosilicon compound. It is preferable to carry out.

  Alumina treatment, silica treatment, and zirconia treatment are treatments for precipitating alumina, silica, or zirconia on the surface of titanium oxide particles, and alumina, silica, and zirconia deposited on these surfaces are water of alumina, silica, and zirconia. Japanese products are also included. The surface treatment of the reactive organosilicon compound means using a reactive organosilicon compound in the treatment liquid.

  In this way, when the surface treatment of the titanium oxide particles is performed at least twice, the surface of the titanium oxide particles is uniformly coated (treated), and when the surface-treated titanium oxide particles are used for the intermediate layer, the intermediate layer It is possible to obtain a good photoconductor having good dispersibility of the titanium oxide particles therein and causing no image defects such as black spots.

  Preferable reactive organosilicon compounds used for the surface treatment include various alkoxysilanes such as methyltrimethoxysilane, n-butyltrimethoxysilane, n-hexycyltrimethoxysilane, dimethyldimethoxysilane, and methylhydrogenpolysiloxane.

(Photosensitive layer)
The structure of the photosensitive layer of the electrophotographic photoreceptor of the present invention may be a single-layered photosensitive layer structure in which a charge generation function and a charge transport function are provided in one layer on the intermediate layer. It is preferable that the function is separated into a charge generation layer (CGL) and a charge transport layer (CTL). By adopting a configuration in which the functions are separated, an increase in the residual potential due to repeated use can be controlled to be small, and other electrophotographic characteristics can be easily controlled according to the purpose. In the negatively charged photoconductor, it is preferable that a charge generation layer (CGL) is formed on the intermediate layer, and a charge transport layer (CTL) is formed thereon. In the positively charged photoconductor, the order of the layer configuration is the reverse of that in the negatively charged photoconductor. The most preferred photosensitive layer structure of the present invention is a negatively charged photoreceptor structure having the function separation structure.

  The structure of the photosensitive layer of the function-separated negatively charged photoreceptor will be described below.

(Charge generation layer)
The charge generation layer contains a charge generation material (CGM). Other substances may contain a binder resin and other additives as necessary.

  In the organophotoreceptor of the present invention, the above-mentioned butanediol adduct titanyl phthalocyanine is used as a charge generating material, but other phthalocyanine pigments, azo pigments, perylene pigments, azulium pigments and the like can be used in combination.

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass 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 is preferably 0.1 μm to 2 μm.

(Charge transport layer)
The charge transport layer contains a charge transport material (CTM) and a binder resin that disperses and forms a CTM. Other substances may contain additives such as antioxidants as necessary.

  A known charge transport material (CTM) can be used as the charge transport material (CTM). For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in an arbitrary binder resin to form a layer.

  The binder resin used for the charge transport layer (CTL) may be either a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used. Of these, polycarbonate resins are most preferred because of their low water absorption and good CTM dispersibility and electrophotographic characteristics.

  The ratio of the binder resin to the charge transport material is preferably 10 to 200 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the charge transport layer is preferably 10 to 40 μm.

  The most preferable layer structure of the photoconductor of the present invention has been exemplified above, but other photoconductor layer configurations may be used in the present invention.

  Examples of the solvent or dispersion medium used for forming the photosensitive layer include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, Benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, Examples include methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, and methyl cellosolve. The present invention is not limited to these, but toluene, tetrahydrofuran, dioxolane and the like are preferably used. These solvents may be used alone or as a mixed solvent of two or more.

  Next, as a coating processing method for manufacturing the organic photoreceptor, a coating processing method such as dip coating, spray coating, circular amount regulation type coating, etc. is used. In order to prevent dissolution as much as possible, and in order to achieve uniform coating processing, it is preferable to use a coating processing method such as spray coating or circular amount regulation type (circular slide hopper type is a typical example). It is most preferable to use the circular amount regulation type coating method for the protective layer. The circular amount regulation type coating is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

<Image forming device>
FIG. 4 is an example of a cross-sectional configuration diagram of a color image forming apparatus using an electrophotographic photosensitive member manufactured by the manufacturing method of the present invention.

  In this image forming apparatus, it is desirable to use a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 850 nm as an image exposure light source when an electrostatic latent image is formed on a photoconductor. By using these image exposure light sources, the exposure dot diameter in the writing principal direction is narrowed down to 10 to 100 μm, and digital exposure is performed on the organic photoreceptor, so that 600 dpi (dpi: number of dots per 2.54 cm) to 2400 dpi. Or higher-resolution electrophotographic images can be obtained.

The exposure dot diameter refers to the length of the exposure beam along the main scanning direction (Ld: the length is measured at the maximum position) in a region where the intensity of the exposure beam is 1 / e ² or more of the peak intensity.

The light beams used have a scanning optical system and LED solid scanner such as a semiconductor laser, there is a Gaussian distribution and Lorentz distribution, etc. also the light intensity distribution is in each 1 / e ² or more regions of peak intensity The exposure dot diameter according to the present invention is used.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging unit (charging step) 2Y, an exposure unit (exposure step) 3Y, and a developing unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A unit (developing step) 4Y, a primary transfer roller 5Y as a primary transfer unit (primary transfer step), and a cleaning unit 6Y. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk include charging means 2Y, 2M, 2C, and 2Bk that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk, and image exposure means 3Y, 3M, 3C and 3Bk, rotating developing means 4Y, 4M, 4C and 4Bk, and cleaning means 6Y, 6M, 6C and 6Bk for cleaning the photosensitive drums 1Y, 1M, 1C and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 6Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning unit 6Y or the cleaning blade 6Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure unit 3Y, a unit composed of LEDs and light-emitting elements in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y, a laser optical system, or the like is used.

  In this image forming apparatus, the above-described photosensitive member and components such as a developing device and a cleaning device are integrally combined as a process cartridge (image forming unit), and this image forming unit is detachable from the apparatus main body. You may comprise. In addition, at least one of a charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (image forming unit), which is detachable from the apparatus main body. A single image forming unit may be detachable using guide means such as a rail of the apparatus main body.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. An image support P as an image support (support for supporting a fixed final image: for example, plain paper, transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and is supplied to a plurality of image supports P. The intermediate rollers 22A, 22B, 22C, 22D, and the registration roller 23 are conveyed to a secondary transfer roller 5b as a secondary transfer unit, and are secondarily transferred onto the image support P to collectively transfer color images. . The image support P to which the color image has been transferred is subjected to fixing processing by the fixing means 24, is sandwiched between the paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a transfer support for a toner image formed on a photosensitive member such as an intermediate transfer member or an image support is collectively referred to as a transfer medium.

  On the other hand, the endless belt-shaped intermediate transfer body 70 obtained by transferring the color image to the image support P by the secondary transfer roller 5b as the secondary transfer means and then separating the curvature of the image support P is subjected to residual toner by the cleaning means 6b. Removed.

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the image support P passes through the secondary transfer roller 5b and the secondary transfer is performed.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. Consists of.

  This image forming apparatus is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter type printers, but also displays such as displays, recordings, light printing, plate making and facsimiles using electrophotographic technology. It can be applied to a wide range of devices.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the embodiment of the present invention is not limited to these examples.

(Synthesis example)
About the synthesis | combination of the said polymeric compound (A), it can carry out by a well-known method, and it describes below using the synthesis | combining method of exemplary compound M-1 as an example.

(Synthesis Example 1: Synthesis of M-1)
A reactor is charged with 100 g of tripentaerythritol, 181 g of acrylic acid, 18 g of acetic acid, 91 g of cyclohexane, 8.0 g of concentrated sulfuric acid, and 1.2 g of hydroquinone monomethyl ether, and 8 hours at 80 ° C. to 90 ° C. while blowing air at 10 ml / min. Reacted. After completion of the reaction, 530 g of toluene was added to the reaction mixture, and the resulting organic layer was washed with 25% by mass sodium hydroxide aqueous solution and then with 10% by mass sodium sulfate aqueous solution, dried using magnesium sulfate, and polymerization was prohibited. An agent (hydroquinone monomethyl ether) 0.2 g was added, concentrated and dried to obtain 153 g of “M-1”. The obtained “M-1” is usually obtained as a mixture of tripentaerythritol octaacrylate, tripentaerythritol hexaacrylate, etc., and each can be separated by fractional distillation.

(Production of surface-treated metal oxide)
(Preparation of surface-treated metal oxide fine particles 1)
100 parts by mass of “tin oxide” having a number average primary particle size of 17 nm as metal oxide fine particles, 30 parts by mass of “Exemplary Compound S-13” as a surface treatment agent, and 1000 parts by mass of methyl ethyl ketone were wet sand mill (alumina beads having a diameter of 0.5 mm). ) And mixed at 30 ° C. for 6 hours, and then methyl ethyl ketone and alumina beads were separated by filtration and dried at 60 ° C. to prepare “surface-treated metal oxide fine particles 1”.

(Preparation of surface-treated metal oxide fine particles 2)
In the preparation of the surface-treated metal oxide fine particles 1, “surface” was used in the same manner except that “alumina” having a number average primary particle size of 30 nm was used as the metal oxide fine particles and “Exemplary Compound S-13” was used as the surface treatment agent. Treated metal oxide fine particles 2 ”were prepared.

(Preparation of surface-treated metal oxide fine particles 3)
In the production of the surface-treated metal oxide fine particles 1, “surface-treated metal oxide fine particles 3” were produced in the same manner except that “titanium dioxide” having a number average primary particle diameter of 6 nm was used as the metal oxide fine particles.

(Preparation of surface-treated metal oxide fine particles 4)
“Surface-treated metal oxide fine particles 4” were produced in the same manner as in the preparation of the surface-treated metal oxide fine particles 1 except that the surface treatment agent was changed to “Exemplary Compound S-28”.

(Preparation of surface-treated metal oxide fine particles 5)
“Surface-treated metal oxide fine particles 5” were produced in the same manner as in the production of the surface-treated metal oxide fine particles 1 except that the surface treatment agent was changed to “Exemplary Compound S-29”.

(Synthesis Example 2: Synthesis of CG-1)
(1) Synthesis of amorphous titanyl phthalocyanine 1,3-diiminoisoindoline; 29.2 g was dispersed in 200 ml of o-dichlorobenzene, titanium tetra-n-butoxide; Heated at 160 ° C. for 5 hours. After allowing to cool, the precipitated crystals were filtered, washed with chloroform, washed with 2% aqueous hydrochloric acid, washed with water, washed with methanol, and dried to obtain 26.2 g (yield 91%) of crude titanyl phthalocyanine.

  Subsequently, the crude titanyl phthalocyanine was dissolved by stirring in 250 ml of concentrated sulfuric acid at 5 ° C. or less for 1 hour, and this was poured into 5 liters of water at 20 ° C. The precipitated crystals were filtered and sufficiently washed with water to obtain 225 g of a wet paste product.

  Subsequently, the wet paste product was frozen in a freezer, thawed again, filtered and dried to obtain 24.8 g (yield 86%) of a titanyl phthalocyanine-amorphous product.

(2) Synthesis of (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine (CG-1) A thermometer, a condenser tube and a mechanical stirrer were placed in a 1 liter four-necked flask, and the above-mentioned amorphous 200 g of o-dichlorobenzene (ODB) containing 10.0 g of titanyl phthalocyanine and 1.30 g of (2R, 3R) -2,3-butanediol (0.83 equivalent ratio) (equivalent ratio is equivalent ratio to titanyl phthalocyanine, hereinafter the same). The mixture was mixed and heated and stirred at 60 to 70 ° C. for 6.0 hours. )
Subsequently, the reaction solution was allowed to stand overnight, 100 ml of water was added to the reaction solution, and the mixture was heated and stirred at 60 to 70 ° C. for 6.0 hours to perform a hydrolysis reaction (hydrolysis step). The stirring speed in the addition reaction and hydrolysis step was 300 rpm.

After the hydrolysis reaction, the reaction solution is allowed to cool, and methanol is added to filter the resulting crystals. The filtered crystals are washed with methanol, filtered, and dried overnight in a 60 ° C. drying box. It was. 10.3 g of pigment CG-1 containing (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine was obtained. The X-ray diffraction spectrum of CG-1 is shown in (2) of FIG. There is a characteristic peak at 8.3 °. There is a peak in the 576 and 648 in the mass spectra, O-Ti-O both absorption appears Ti = O near 970 cm ^-1, around 630 cm ^-1 in the IR spectrum.

  In addition, since thermal analysis (TG) has a mass loss of about 7% at 390 to 410 ° C., a 1: 1 adduct of titanyl phthalocyanine and (2R, 3R) -2,3-butanediol (shown in Chemical Formula 1 above) A dehydrated condensation structure) and a non-adduct (not added) titanyl phthalocyanine mixed crystal.

(Synthesis Example 3: Synthesis of CG-2)
(3) Synthesis of (2S, 3S) -2,3-butanediol adduct titanyl phthalocyanine (CG-2) In the synthesis of CG-1 in Synthesis Example 2, (2R, 3R) -2,3-butanediol was synthesized. Except for changing to (2S, 3S) -2,3-butanediol, an addition reaction and a hydrolysis step were carried out in the same manner as in Synthesis Example 1, and after washing with methanol, a solvent of methanol / water = 7/3 was used. Methanol was replaced, and after filtration, dried in a drying box at 60 ° C. overnight to obtain 10.6 g of pigment CG-2 containing (2S, 3S) -2,3-butanediol adduct titanyl phthalocyanine. When the X-ray diffraction spectrum of CG-2 is measured, a characteristic peak is observed at 8.3 °, the mass spectrum has peaks at 576 and 648, and the IR spectrum has Ti = O around 970 cm ⁻¹ as in CG-1. Both absorptions of O—Ti—O appear in the vicinity of 630 cm ⁻¹ . In thermal analysis (TG), there is a mass loss of about 7% at 390 to 410 ° C., so that a 1: 1 adduct of titanyl phthalocyanine and (2S, 3S) -2,3-butanediol (the above reaction formula (1 ) And a non-adduct (not added) titanyl phthalocyanine mixed crystal.

(Synthesis Example 4: Synthesis of CG-3 (Y-type titanyl phthalocyanine))
A crude titanyl phthalocyanine was synthesized from diiminoisoindoline and titanium tetrabutoxide, dissolved in sulfuric acid, poured into water, and the resulting precipitate was filtered and washed thoroughly with water to obtain an amorphous titanyl phthalocyanine pigment-containing paste. This pigment hydrous paste (about 10 g in terms of solid content) was dispersed in a mixture of 100 ml of orthodichlorobenzene and 100 ml of water (the water layer was separated), heated at 70 ° C. for 6 hours, and then poured into methanol to form crystals. Was filtered and dried to obtain Y-type titanyl phthalocyanine.

<< Examples 1 to 19 >>
<Preparation of Photoreceptor 1>
(Preparation of conductive support)
The surface of the cylindrical aluminum support was cut to prepare a conductive support having a surface roughness Rz = 1.5 (μm).

(Formation of intermediate layer)
A dispersion having the following composition was diluted twice with the same mixed solvent, allowed to stand overnight, and then filtered (filter; using a lysh mesh 5 μm filter manufactured by Nippon Pole Co., Ltd.) to prepare an intermediate layer coating solution.

Polyamide resin (CM8000: manufactured by Toray Industries, Inc.) 1 part by mass Titanium oxide (SMT500SAS: manufactured by Teica) 3 parts by mass Methanol 10 parts by mass Using a sand mill as a disperser, dispersion was carried out for 10 hours in a batch system.

  The said coating liquid was apply | coated and dried by the dip coating method so that it might become a dry film thickness of 2 micrometers on the said electroconductive support body, and the "intermediate layer" was formed.

(Formation of charge generation layer)
[Charge generation layer coating solution CGL-1]
The following composition was mixed, dispersed with a circulating ultrasonic homogenizer RUS-600TCVP (manufactured by Nippon Seiki Seisakusho, 19.5 kHz, 600 W) at a circulating flow rate of 40 L / H for 0.5 hour, and the charge generation layer coating solution CGL- 1 was produced.

Charge generation material: CG-1 24 parts by mass Polyvinyl butyral resin “ESREC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts by mass 3-methyl-2-butanone / cyclohexanone = 4/1 (V / V) 400 parts by mass The charge generation layer coating solution CGL-1 was applied onto the intermediate layer by a dip coating method and dried to form a “charge generation layer” having a dry film thickness of 0.3 μm.

  The reflectance ratio of this charge generation layer was 1.00.

(Formation of charge transport layer)
The following composition was mixed and dissolved to prepare a charge transport layer coating solution.

Charge transport material (CTM-1 below) 225 parts by weight Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts by weight Antioxidant (Irganox 1010: manufactured by BASF Japan) 6 parts by weight Tetrahydrofuran 1600 parts by weight Toluene 400 parts by weight Silicone oil ( KF-54 (manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass This charge transport layer coating solution is applied onto the charge generation layer using a circular amount-regulating coating machine and dried to form a “charge transport layer having a dry film thickness of 20 μm. Formed.

(Formation of protective layer)
The following composition was dissolved and dispersed to prepare a protective layer coating solution.

Surface-treated metal oxide fine particles 1 100 parts by weight Polymerizable compound (A) (M-2) 30 parts by weight Polymerizable compound (B) (m-1) 70 parts by weight Polymerization initiator (Irgacure 819: manufactured by BASF Japan Ltd.) ) 15 parts by mass sec-butanol 500 parts by mass This protective layer coating solution was applied onto the charge transport layer using a circular amount-regulating coating device to form a protective layer.

  After drying the formed protective layer, using a metal halide lamp, the distance from the light source to the surface of the photoreceptor is set to 100 mm under a nitrogen stream, irradiated with ultraviolet light for 1 minute at a lamp output of 4 kW, and a dry film thickness of 2.0 μm. A “protective layer” was formed to produce “photoreceptor 1”.

<Preparation of photoconductors 2-7, 9, 10, 12-19>
In the production of the photoconductor 1, the types and addition amounts of the surface-treated metal oxide fine particles, the polymerizable compound (A), and the polymerizable compound (B) of the protective layer are set as shown in Table 1 as “photoconductors 2 to 7, 9”. 10, 12-19 ".

<Preparation of photoconductor 8>
“Photoreceptor 8” was produced in the same manner as in the production of photoconductor 1 except that the following charge generation layer coating solution CGL-2 was used as the charge generation layer.

[Charge generation layer coating solution CGL-2]
In the production of the charge generation layer coating solution CGL-1, the charge generation layer coating solution was similarly changed except that the dispersion condition was changed to 1.5 hours dispersion with an ultrasonic homogenizer (ultrasonic industry UH-3C, 25 kHz, 150 W). CGL-2 was produced.

<Preparation of Photoreceptor 11>
“Photoreceptor 11” was produced in the same manner as Photoreceptor 1, except that the following charge generation layer coating solution CGL-3 was used as the charge generation layer in preparation of Photoreceptor 1.

[Charge generation layer coating solution CGL-3]
A charge generation layer coating solution CGL-3 was prepared in the same manner except that the dispersion time was changed to 2.5 hours in the preparation of the charge generation layer coating solution CGL-1.

<< Comparative Examples 1-4 >>
<Preparation of Photoreceptor 20>
In the production of the photoconductor 1, the following “photoconductor” was used in the same manner as the photoconductor 1 except that the charge generation layer coating solution CGL-6 shown below was used and the polymerizable compound (A) was not added to the protective layer. 20 "was produced.

[Charge generation layer coating solution CGL-6]
A charge generation layer coating solution CGL-6 was prepared in the same manner as in the preparation of the charge generation layer coating solution CGL-1, except that CG-1 of the charge generation layer was replaced with CG-3 (Y-type titanyl phthalocyanine). Y-type titanyl phthalocyanine is a titanyl phthalocyanine pigment having a maximum peak at 27.2 ° in an X-ray diffraction spectrum (FIG. 5), and is a pigment synthesized by the following synthesis example.

<Preparation of Photoreceptor 21>
In the production of the photoconductor 1, the following photogenerating layer coating solution CGL-4 was used as the charge generating layer, and the polymerizable compound (A) was not added to the protective layer. 21 "was produced.

[Charge generation layer coating solution CGL-4]
A charge generation layer coating solution CGL-4 was prepared in the same manner except that the charge generation layer coating solution CGL-1 was changed to sand mill dispersion under the following conditions.

  Glass beads having an outer diameter of 1 mm were used as a dispersion medium, and dispersion was performed for 1 hour in a sand mill under conditions of a bead filling rate of 80% by volume and a rotation speed of 800 rpm.

<Preparation of Photoconductor 22>
In the production of the photoreceptor 1, the “photoreceptor 22” was produced in the same manner except that the charge generation layer coating solution CGL-5 was used as the charge generation layer and the polymerizable compound (A) was not added to the protective layer. did.

[Charge generation layer coating solution CGL-5]
In the preparation of the charge generation layer coating solution CGL-1, the charge generation layer coating solution CGL- was similarly prepared except that the dispersion condition was changed to dispersion for 30 minutes with an ultrasonic homogenizer (ultrasonic industry UH-3C, 25 kHz, 150 W). 5 was produced.

<Preparation of Photoconductor 23>
In the production of the photoreceptor 1, the charge generation layer coating solution CGL-4 is used as the charge generation layer, and M-8 having a polymerizable functional group number of 6 having the following structural formula is used as the polymerizable compound (A) in the protective layer. Otherwise, “Photoreceptor 23” was produced in the same manner.

(Evaluation methods)
The electrophotographic photoreceptors 1 to 23 produced as described above were evaluated as follows. In Examples 1 to 19, “Photoreceptors 1 to 19” were evaluated for the purpose of comparison, and “Photoreceptors 20 to 23” were evaluated for comparison.
<Evaluation>
<Environmental memory>
The digital copying machine bizhub 920 was left in a high temperature and high humidity (HH) environment (33 ° C .; 80%) for 24 hours, then placed in a low humidity and low temperature (LL: 10 ° C., 20 RH%), and copied after 30 minutes. Copy the halftone image with a density of 0.4 in the original image to a density of 0.4, determine the density difference (ΔHD = maximum density−minimum density) of the copy image, evaluate it according to the following evaluation criteria, and Shown as an indicator of memory.

A: ΔHD is 0.05 or less (good)
○: ΔHD is larger than 0.05 and smaller than 0.1 (no practical problem)
X: ΔHD is 0.1 or more (practical problem)
<Image evaluation after endurance test>
50,000 shots under high temperature and high humidity (HH) environment (33 ° C; 80%) and 50,000 shots under low temperature and low humidity (LL) environment (15 ° C; 30%) Evaluation was performed.

  Each evaluation item and criteria are as shown below. In addition, here, it was determined that “◯” or more was acceptable.

<Image density>
A solid black image was produced on white A4 paper, and the image density was measured using RD-918 manufactured by Macbeth. The relative reflection density was measured with the paper reflection density set to “0”. When the surface potential after exposure increases in a large number of copies, the image density decreases.

A: Image density of a solid black image is 1.2 or more (good)
○: The image density of a solid black image is less than 1.0 to 1.2 (no practical problem)
X: The image density of the solid black image is less than 1.0 (there is a practical problem)
<Abrasion resistance>
Evaluation was made based on the difference in film thickness before and after the printing and printing durability test for 500,000 sheets under environmental conditions of 30 ° C. and 80% RH. The photosensitive layer thickness is measured at 10 points at random on the uniform film thickness portion (the film thickness tends to be non-uniform at both ends of the photoreceptor, so at least 3 cm at both ends), and the average value is measured as the film thickness of the photosensitive layer. Thickness. The film thickness measuring device is an eddy current type film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO), and the difference in the photosensitive layer thickness before and after the printing test is defined as the film thickness depletion amount.

A: The amount of wear is 0.7 μm or less (good)
○: Amount of wear is 0.8 μm to 2 μm (no problem in practical use)
X: The amount of wear is larger than 2 μm (there is a practical problem)
The results are shown in Table 2.

  As is apparent from the above results, the photoconductors 1 to 19 of the present invention are more sensitive than the photoconductors 20 to 23 for comparison, and there is no generation of memory in a high-humidity environment. However, it can be seen that there is no increase in the residual potential, and as a result, the image density is stable and it has high durability with excellent wear resistance.

1A Conductive Support 2A Photosensitive Layer 3A Intermediate Layer 4A Charge Generation Layer 5A Charge Transport Layer 6A Protective Layer 7A Surface-treated Metal Oxide Fine Particles 1Y, 1M, 1C, 1Bk Photosensitive Drum 2Y, 2M, 2C, 2Bk Charging Means 3Y, 3M, 3C, 3Bk Image exposure means 4Y, 4M, 4C, 4Bk Developing means 6Y, 6M, 6C, 6Bk Cleaning means 10Y, 10M, 10C, 10Bk Image forming unit

Claims (3)

In the electrophotographic photosensitive member formed by sequentially laminating at least a photosensitive layer and a protective layer on a conductive support, the protective layer comprises a compound (A) having 7 or more polymerizable functional groups and 2 polymerizable functional groups. A polymerization product produced using a compound (B) having at least 4 and at least 4 and a surface-treated metal oxide fine particle surface-treated with a surface-treating agent having a polymerizable functional group, and the photosensitive layer comprises It contains an adduct of 2,3-butanediol and titanyl phthalocyanine, and the ratio of the reflectance at 700 nm (R700) and the reflectance at 780 nm (R780) of the reflection spectrum of the photosensitive layer (R700 / R780). ) Is 0.8 or more and 1.3 or less.
However, the reflectance is a reflectance measured by forming a photosensitive layer (charge generation layer) on an aluminum support, and is a relative reflectance when the reflectance of the aluminum support is 100%.   The polymerization product is prepared by setting the total of the compound (A) and the compound (B) to 100 parts by mass and the surface-treated metal oxide fine particles from 50 parts by mass to 250 parts by mass. The electrophotographic photosensitive member according to claim 1.   The electrophotographic photoreceptor according to claim 1 or 2, wherein the compound (A) having 7 or more polymerizable functional groups has 10 or less polymerizable functional groups.

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