JP2692246B2 - Electrophotographic photoreceptor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor using a polycarbonate-polysiloxane block copolymer as a binder resin.

2. Description of the Related Art In recent years, electrophotographic technology has the advantage that high-speed and high printing quality can be obtained, and thus has been remarkably applied in the fields of copiers, laser beam printers, and the like.

As an electrophotographic photoreceptor used in these electrophotographic techniques, those using inorganic photoconductive materials such as selenium, selenium-tellurium alloy, selenium-arsenic alloy, and cadmium sulfide have been widely known. On the other hand, as compared with electrophotographic photoreceptors using these inorganic photoconductive materials, research on electrophotographic photoreceptors using organic photoconductive materials, which are inexpensive and have excellent advantages in terms of manufacturability and disposal, has also been activated. For example, as disclosed in JP-A-61-132954, an electrophotographic photoreceptor using a polycarbonate-polysiloxane block copolymer as a binder resin for a charge generation layer or a charge transport layer is disclosed. Are known.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the electrophotographic photoreceptor using the polycarbonate-polysiloxane block copolymer as a binder resin for the charge generation layer or the charge transport layer, in terms of electrical characteristics such as sensitivity and chargeability. Shows good performance, but durability against mechanical external force, that is, a problem that image defects occur due to abrasion and scratches on the surface of the photoreceptor due to direct load from toner, developer, paper, cleaning member, or the like, or There is a problem of image deletion in a high humidity environment caused by low-resistance substances such as ozone and nitrogen oxides generated by corona discharge and paper dust generated by copy paper that accumulates on the surface of the photoconductor. You have limited body life.

Various measures have been studied in order to solve these problems. Firstly, it is possible to increase the hardness of the surface of the photoconductor, thereby suppressing the occurrence of wear and scratches, and secondly. May increase the lubricity of the surface of the photoconductor, thereby suppressing wear, and improving the releasability of the adhered buildup from the surface of the photoconductor to prevent the occurrence of image deletion. The current situation is that satisfactory performance has not yet been achieved. Therefore, conventionally, it has been desired to develop a binder resin capable of forming a photosensitive layer having high surface hardness and good surface lubricity.

The present invention has been made in view of the above situation, and has as its object to solve the above-described problems in the related art.

That is, an object of the present invention is to provide an electrophotographic photoreceptor having a photosensitive layer having both high surface hardness and good surface lubricity.

Means for Solving the Problems As a result of various studies on the binder resin of the photosensitive layer, the present inventors have found that a polycarbonate-polysiloxane block copolymer having a structural unit represented by the following general formula (I) and the following general formula: By using the polycarbonate resin represented by the formula (II) in combination and further containing the fluorine-based resin fine particles, the surface hardness and the surface lubrication are extremely excellent as compared with the case where the above polycarbonate-polysiloxane block copolymer is used alone. It also eliminates the above-mentioned problems, namely, image quality defects due to abrasion and scratches on the surface of the photosensitive layer, and the occurrence of image deletion due to the accumulation and accumulation of paper dust, and dramatically improves the life of the electrophotographic photoreceptor. The inventors have found that they can be made, and have completed the present invention.

The present invention relates to an electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer provided thereon, wherein the photosensitive layer is a binder resin and is a polycarbonate-polysiloxane block composed of structural units represented by the following general formula (I). One or more polymers [In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ each represent a hydrogen atom, a halogen atom or a lower alkyl group, and R ₉ and R ₁₀ are respectively Represents an alkyl group or an aryl group which may have a substituent, and A is (However, Ra and Rb each represent an alkyl group.), L and m represent (l / (l + m) = 0.1 to 0.9). ] And one or more polycarbonate resins comprising a structural unit represented by the following general formula (II) (Wherein, R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ , R _17, and R
₁₈ represents a hydrogen atom or a lower alkyl group,
R ₁₉ and R ₂₀ each represent a hydrogen atom, an alkyl group which may have a substituent or an aryl group, or R ₁₉ and R ₂₀ which are bonded together to form a carbocycle. ) It is characterized by containing and further dispersing fine particles of fluororesin.

 Hereinafter, the present invention will be described in detail.

As the conductive substrate in the electrophotographic photoreceptor of the present invention, aluminum, brass, copper, nickel, steel or other metal plate or metal sheet, plastic sheet, aluminum, nickel, chromium, titanium, palladium, indium oxide, oxide A conductive material such as tin, graphite, or the like, which is coated by vapor deposition, sputtering, coating, or the like, and subjected to a conductive treatment, or a material obtained by conducting a conductive treatment on glass, a plastic plate, cloth, paper, or the like can be used.

On the conductive substrate, a photosensitive layer of a dispersion type, a laminated type or the like is provided, and an undercoat layer having a barrier function or an adhesive function is provided between the photosensitive layer and the conductive substrate as necessary. You may. As a material constituting the undercoat layer, polyvinyl butyral, polyvinyl alcohol, casein,
Resins such as polyamide, cellulose, gelatin, polyurethane and polyester, and metal oxides such as aluminum oxide can be used.

The photosensitive layer formed on the conductive substrate may have a single-layer structure or a laminated structure in which a charge generation layer and a charge transport layer are functionally separated. In the case of a stacked structure, the charge generation layer and the charge transport layer may be stacked in any order.

These photosensitive layers are composed of a coating film containing a charge generating substance, a charge transporting substance, or both of them in a binder resin.

Examples of the charge generating material include amorphous selenium, crystalline selenium, selenium-tellurium alloy, selenium-arsenic alloy, other selenium compounds and alloys, inorganic photoconductors such as zinc oxide and titanium oxide, phthalocyanine, and squarium. And organic pigments and dyes such as anthracene, anthracene, perylene, azo, anthracene, pyrene, pyrylium salts, and thiapyrylium salts.

As the charge transport material, p-benzoquinone, chloranil, bromoanil, quinone compounds such as anthraquinone, tetracyanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone Compounds such as fluorenone compounds, fluorenone-9-malononitrile compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, and electron-withdrawing substances such as ethylene compounds, pyrazoline compounds, hydrazone compounds, oxazole compounds, and carbazole compounds. , Arylalkane-based compounds, triphenylamine-based compounds, aryl-substituted ethylene-based compounds, benzidine-based compounds, stilbene-based compounds, anthracene-based compounds, and polymers having a group consisting of these compounds in a main chain or a side chain. Electron donating substance It is used.

Among these, it is particularly preferable to use a triphenylamine-based compound represented by the following general formula (III).

(In the formula, R ₂₁ and R ₂₂ each represent H or CH ₃ ,
₂₃ represents H, CH ₃ , C ₂ H ₅ or Cl) In the present invention, as the binder resin, a polycarbonate composed of the structural unit represented by the general formula (I) is used.
The polysilosysan block copolymer is used in combination with the polycarbonate resin represented by the general formula (II), and the adhesive resin further contains fluorine resin fine particles. In the case where the photosensitive layer has a laminated structure in which the charge generation layer and the charge transport layer are functionally separated, the both resins can be used as a binder resin for both the charge generation layer and the charge transport layer. It is desirable to use it in at least the layer forming the surface. And it is particularly preferable to use it as a binder resin when the surface is made of a charge transport layer.

The polycarbonate-polysiloxane block copolymer comprising the structural unit represented by the general formula (I) used in the present invention has an average molecular weight of 10,000 to 300,000, particularly 2
Those in the range of 10,000 to 200,000 are preferable.

Specific examples of the polycarbonate-polysiloxane block copolymer represented by the general formula (I) that can be preferably used in the present invention include those having the following structural units as constituent components.

In the present invention, as the polycarbonate resin composed of the structural unit represented by the general formula (II), known resins are used. Usually, those having an average molecular weight in the range of 20,000 to 200,000 are used. Specific examples include those having the following structural units as constituent components.

In the present invention, the content ratio of the polycarbonate-polysiloxane block copolymer represented by the general formula (I) and the polycarbonate resin represented by the general formula (II) can be set arbitrarily, but the former: Latter = 90: 1
It is preferable to use the content ratio in the range of 5:95.

In the present invention, the fluororesin fine particles to be dispersed in the binder resin include, for example, tetrafluoroethylene polymer, vinylidene fluoride polymer, vinylidene chloride trifluoride polymer, tetrafluoroethylene-hexafluoride. Powders such as propylene copolymer and carbon fluoride can be used.
These fluororesin fine particles have an average particle diameter of 0.1 μm to 5 μm.
Those having a particle size in the range of m are preferred.

In the present invention, the mixing ratio of the fluororesin fine particles to the binder resin can be set arbitrarily, but the weight ratio of the fluororesin fine particles to the binder resin is preferably in the range of 0.01 to 1.

In the present invention, when the photosensitive layer has a laminated structure, the charge generation layer is formed by applying and drying a coating solution obtained by dispersing or dissolving the charge generation material and the binder resin in an appropriate solvent. be able to. As the binder resin, known resins, for example, polystyrene, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl acetal, alkyd resin, acrylic resin, polyacrylonitrile, polycarbonate, polyamide, polyketone, polyketone. Acrylamide, butyral resin, thermoplastic resin such as polyester, polyurethane,
A conventionally known resin such as a thermosetting resin such as an epoxy resin and a phenol resin can be used.

The thickness of the charge generation layer is usually 0.05 to 40 μm, preferably
It is set to 0.05 to 25 μm.

Further, the charge transport layer is prepared by dissolving the above charge transporting substance, the above polycarbonate-polysiloxane block copolymer and the polycarbonate resin in a suitable solvent, and further applying a solution in which fine particles of fluororesin are dispersed and drying. Can be formed by A large number of useful organic solvents can be used as the solvent used for forming the charge transport layer. Representative examples include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halogenated aliphatic carbons such as methylene chloride, chloroform and ethylene chloride. Hydrogens, cyclic or linear ethers such as tetrahydrofuran, dioxane, ethylene glycol, diethyl ether and the like, and mixed solvents thereof can be mentioned.

The thickness of the charge transport layer is 2 to 100 μm, preferably 10 to 4 μm.
It is set to 0 μm.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples.

Example 1 An aluminum pipe was used as a conductive substrate, and a coating solution composed of 10 parts by weight of an alcohol-soluble polyamide resin, 150 parts by weight of methanol, and 40 parts by weight of water was dip-coated on the aluminum pipe, dried, and dried. An undercoat layer was formed.

Next, granular trigonal selenium (manufactured by Xerox Co., USA) 90
Parts by weight, modified polyvinyl butyral resin 10 parts by weight, n-
A mixture of 300 parts by weight of butanol was dispersed, 2 parts by weight of n-butanol was added to 1 part by weight of the obtained dispersion, and the diluted solution was applied onto the above-mentioned undercoat layer by a dip coating method and dried. Then, a charge generation layer having a thickness of 0.2 μm was formed.

Next, N, N'-diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine 3
Parts by weight and a polycarbonate-polysiloxane block copolymer represented by the following structural formula (I-1 ′) (PS099, Pet
rarch Systems) 3 parts by weight and the following structural formula (II-1)
7 parts by weight of a polycarbonate resin (average molecular weight of about 30,000) consisting of the structural unit shown by the above was dissolved in a solvent containing 20 parts by weight of each of tetrahydrofuran and 1,4-dioxane. 1 part of tetrafluoroethylene resin fine particles (Lubron L-2, manufactured by Daikin Industries, Ltd.) was added to the obtained solution.
Parts by weight were added and dispersed by a sand mill for 48 hours. The resulting dispersion is dip coated on the above charge generation layer, dried,
A charge transport layer having a film thickness of 20 μm was formed to prepare an electrophotographic photoreceptor having three layers.

Presence or absence of image defects due to abrasion and scratches on the electrophotographic photosensitive member surface when the electrophotographic photosensitive member manufactured as described above is mounted on a copying machine having a blade cleaning member and a copy traveling of 50,000 sheets is performed. The amount of surface wear and the presence or absence of image deletion in a high temperature and high humidity environment were investigated, and the surface pencil hardness was also examined. The results are shown in Table 1.

Example 2 An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the amount of the tetrafluoroethylene resin fine particles in the charge transport layer was changed to 2 parts by weight. Was evaluated. Table 1 shows the results.

Example 3 In Example 1, as a binder resin for the charge transport layer, 5 parts by weight of a polycarbonate-polysiloxane block copolymer having the structural unit represented by the structural formula (I-1 ′) and the structural formula (II -1) except that a mixture with 5 parts by weight of a polycarbonate resin composed of the structural unit represented by -1) was used, an electrophotographic photosensitive member was produced by the same processing as in Example 1 and evaluated in the same manner. Table 1 shows the results.

Example 4 In Example 1, as a binder resin for the charge transport layer, 5 parts by weight of a polycarbonate-polysiloxane block copolymer having the structural unit represented by the structural formula (I-1 ′) and the structural formula (II -1) except that a mixture with 5 parts by weight of a polycarbonate resin (average molecular weight of about 30,000) consisting of the structural unit shown in -1) was used, and the amount of the tetrafluoroethylene resin fine particles was changed to 2 parts by weight. An electrophotographic photosensitive member was produced by treating in the same manner as in Example 1 and evaluated in the same manner. Table 1 shows the results.

Example 5 In Example 1, as the binder resin for the charge transport layer, 3 parts by weight of a polycarbonate-polysiloxane block copolymer having the structural unit represented by the structural formula (I-1 ′) and the following structural formula (II -2), except that a mixture with 7 parts by weight of a polycarbonate resin composed of the structural unit shown in -2) was used, an electrophotographic photosensitive member was produced by the same process as in Example 1 and evaluated in the same manner. Table 1 shows the results.

Example 6 In Example 1, as a binder resin for the charge transport layer, 3 parts by weight of a polycarbonate-polysiloxane block copolymer having the structural unit represented by the structural formula (I-1 ′) and the structural formula (II -2) A mixture with 7 parts by weight of a polycarbonate resin consisting of the structural unit shown in FIG. 2) was used, and the same procedure as in Example 1 was performed except that the amount of the tetrafluoroethylene resin fine particles was changed to 2 parts by weight. Then, an electrophotographic photosensitive member was produced and evaluated in the same manner. Table 1 shows the results.

Example 7 In Example 1, as a binder resin for the charge transport layer, 5 parts by weight of a polycarbonate-polysiloxane block copolymer having the structural unit represented by the structural formula (I-1 ′) and the structural formula (II -2), except that a mixture with 5 parts by weight of a polycarbonate resin composed of the structural unit shown in -2) was used, an electrophotographic photosensitive member was prepared in the same manner as in Example 1 above, and evaluated in the same manner. Table 1 shows the results.

Example 8 In Example 1, as the binder resin for the charge transport layer, 5 parts by weight of a polycarbonate-polysiloxane block copolymer having the structural unit represented by the structural formula (I-1 ′) and the structural formula (II -1) except that a mixture with 5 parts by weight of a polycarbonate resin (average molecular weight of about 30,000) consisting of the structural unit shown in -1) was used, and the amount of the tetrafluoroethylene resin fine particles was changed to 2 parts by weight. An electrophotographic photosensitive member was produced by treating in the same manner as in Example 1 and evaluated in the same manner. Table 1 shows the results.

Comparative Example As a binder resin for the charge transport layer, the above structural formula (I-
Polycarbonate comprising a structural unit represented by 1 ')
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that only 10 parts by weight of the polysiloxane block copolymer was used, and the same evaluation was performed. Table 1 shows the results.

EFFECTS OF THE INVENTION In the present invention, as a binder resin for the photosensitive layer, a polycarbonate-polysiloxane block copolymer comprising the structural unit represented by the general formula (I) and a structural unit represented by the general formula (II) is used. Since the mixture of the polycarbonate resin is further used, and the fine particles of the fluorine-based resin are further dispersed, the formed coating film has extremely excellent surface hardness and surface lubricity. Therefore, the electrophotographic photoreceptor of the present invention is Further, the durability is excellent, the occurrence of image defects due to abrasion and scratches on the surface of the photosensitive layer is suppressed, and at the same time, the occurrence of image deletion due to the adhesion and accumulation of paper powder is eliminated, and the life is dramatically improved.

Front page continuation (72) Inventor Koichi Yamamoto 1600 Takematsu, Minamiashigara City, Kanagawa Fujizerox Co., Ltd. Takematsu Plant (56) References JP-A-61-132954 (JP, A) JP-A-56-126838 (JP) , A) JP-A-51-120731 (JP, A)

Claims (3)

(57) [Claims] 1. An electrophotographic photoreceptor having a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer is a polycarbonate-polysiloxane block comprising a structural unit represented by the following general formula (I) as a binder resin. One or more copolymers [In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ each represent a hydrogen atom, a halogen atom or a lower alkyl group, and R ₉ and R ₁₀ are respectively Represents an alkyl group or an aryl group which may have a substituent, and A is (However, Ra and Rb each represent an alkyl group.), L and m represent (l / (l + m) = 0.1 to 0.9). ] And one or more polycarbonate resins comprising a structural unit represented by the following general formula (II) (Wherein, R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , R ₁₆ , R _17, and R
₁₈ represents a hydrogen atom or a lower alkyl group,
R ₁₉ and R ₂₀ each represent a hydrogen atom, an alkyl group which may have a substituent or an aryl group, or R ₁₉ and R ₂₀ which are bonded together to form a carbocycle. ) An electrophotographic photosensitive member characterized by containing and further dispersing fine particles of a fluororesin. 2. The content ratio of the polycarbonate-polysiloxane block copolymer comprising the structural unit represented by the general formula (I) and the polycarbonate resin comprising the structural unit represented by the general formula (II) is 90: The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is 10 to 5:95. 3. The electrophotographic photosensitive member according to claim 1, wherein the weight ratio of the fluororesin fine particles to the binder resin is 0.02 to 1.