JP2003029440A - Electrophotographic photoreceptor, image forming method, image forming apparatus and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having high resolution and not causing image defects such as black spots and to provide an image forming method, an image forming apparatus and a process cartridge each using the electrophotographic photoreceptor. SOLUTION: In the electrophotographic photoreceptor having an intermediate layer and a photosensitive layer on an electrically conductive support, the intermediate layer contains at least titanium oxide particles and an alkylene copolymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member) used in the field of copying machines and printers, and an electrophotographic photosensitive member using the same.
The present invention relates to an image forming method, an image forming apparatus and a process cartridge.

[0002]

2. Description of the Related Art Electrophotographic photoreceptors (hereinafter also simply referred to as photoreceptors) are Se, arsenic, arsenic / Se alloys, CdS, ZnO.
Inorganic photoconductors such as the above have been transferred to organic photoconductors that are excellent in advantages such as pollution and ease of production, and organic photoconductors using various materials have been developed.

In recent years, function-separated type photoconductors in which different materials are responsible for charge generation and charge transport functions have become the mainstream. Among them, a laminated photoconductor in which a charge generation layer and a charge transport layer are laminated is used. Widely used.

In addition, focusing on the electrophotographic process, latent image forming methods are roughly classified into analog image forming using a halogen lamp as a light source and digital image forming using an LED or a laser as a light source. Recently, a digital latent image forming method is rapidly becoming the mainstream as a printer for a hard copy of a personal computer, and also in an ordinary copying machine because of the ease of image processing and the ease of development to a multi-function peripheral.

In digital image formation, a laser, particularly a semiconductor laser or an LED, is used as a light source when writing image information converted into a digital electric signal on a photoreceptor as an electrostatic latent image. However, in forming a latent image with a laser beam, there is known a peculiar image problem that interference fringes are generated due to reflection on the substrate surface.

In digital writing, the writing speed is slow because the exposure beam diameter is small. Therefore, a combination with reversal development is mainly used as a developing method for the exposed portion, but as a problem peculiar to the image forming method using the reversal development, toner is originally formed on a portion where an image is to be formed as a white background portion. It is known that a black spot is generated due to a local defect of the photoconductor, which is a phenomenon in which the toner adheres to cause fog.

In order to solve these problems, a technique of using an intermediate layer in the photoconductor has been developed. For example, an electrophotographic photosensitive member is known in which an intermediate layer is provided between a conductive support and a photosensitive layer, and titanium oxide particles are dispersed in a resin in the intermediate layer. Further, a technique of an intermediate layer containing titanium oxide subjected to surface treatment is also known. For example, iron oxide disclosed in JP-A-4-303846, titanium oxide surface-treated with tungsten oxide, titanium oxide surface-treated with an amino group-containing coupling agent disclosed in JP-A-9-96916, and JP-A-9-258469. Examples thereof include titanium oxide surface-treated with an organic silicon compound and titanium oxide surface-treated with methylhydrogenpolysiloxane described in JP-A-8-328283.

However, even if these techniques are used, in a severe environment of high temperature and high humidity and low temperature and low humidity, the prevention of black spots is still insufficient, or the residual potential increases due to repeated use, and the exposed portion is exposed. There is a problem that the electric potential rises and the image density cannot be sufficiently obtained. Furthermore, JP-A-1
No. 1-344826 proposes an electrophotographic photoreceptor having an intermediate layer using a dendritic titanium oxide surface-treated with a metal oxide or an organic compound. However, according to the results of the additional test of the embodiment disclosed in this patent, the effect of preventing black spots at high temperature and high humidity and low temperature and low humidity is not sufficient.

[0009]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the present invention is to provide an electrophotographic photosensitive member having good potential stability and not causing image defects such as black spots, More specifically, it does not generate image defects such as black spots and has good potential stability even after repeated use, an electrophotographic photoreceptor having an intermediate layer, and an image forming method using the electrophotographic photoreceptor, an image forming apparatus, To provide a process cartridge.

[0010]

The object of the present invention is achieved by the following constitution.

1. An electrophotographic photoreceptor having an intermediate layer and a photosensitive layer on a conductive support, wherein the intermediate layer contains at least titanium oxide particles and an alkylene copolymer.

2. 2. The electrophotographic photosensitive member described in 1 above, wherein the titanium oxide particles are surface-treated.

3. 3. The surface treatment is a plurality of surface treatments, the first surface treatment is a surface treatment with an inorganic compound, and the last surface treatment is a surface treatment with a reactive organosilicon compound. Electrophotographic photoreceptor.

4. 4. The electrophotographic photoconductor according to the above 3, wherein the inorganic compound is at least one of silica and alumina, and the reactive organosilicon compound is methylhydrogenpolysiloxane.

5. 4. The electrophotographic photosensitive member according to the above 3, wherein the inorganic compound is at least one of silica and alumina, and the reactive organic silicon compound is an organic silicon compound represented by the general formula (1).

6. The electrophotography according to any one of 1 to 5 above, wherein the mass ratio of the titanium oxide particles and the alkylene copolymer is 100 to 500 parts of titanium oxide particles with respect to 100 parts of the alkylene copolymer. Photoconductor.

7. The titanium oxide particles have an average particle size of 10
1 or more and 200 nm or less
7. The electrophotographic photosensitive member according to any one of items 1 to 6.

8. 8. The electrophotographic photosensitive member according to any one of 1 to 7 above, wherein the alkylene copolymer is an ethylene copolymer.

9. 9. The electrophotographic photoreceptor according to any one of 1 to 8 above, wherein the photosensitive layer is composed of a charge generation layer and a charge transport layer.

10. 9. The charge generation layer contains a titanyl phthalocyanine pigment.
The electrophotographic photosensitive member according to 1.

11. In an image forming method comprising an electrophotographic photosensitive member and at least a charging step, an image exposing step, a developing step, a transferring step and a cleaning step, wherein the image is repeatedly formed, the electrophotographic photosensitive member is any one of 1 to 10 above. An image forming method, which is the electrophotographic photosensitive member according to the item 1.

12. An image forming apparatus using the image forming method described in 11 above.

13. 11. The electrophotographic photosensitive member according to any one of 1 to 10 and at least one of a charging unit, an image exposing unit, a developing unit, a transferring unit, and a cleaning unit are integrally provided, and the electrophotographic photosensitive member is placed in and out of the image forming apparatus. A process cartridge characterized by being configured as possible.

The present invention will be described in detail below. The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having an intermediate layer and a photosensitive layer on a conductive support, wherein the intermediate layer contains at least titanium oxide particles and an alkylene copolymer. .

The titanium oxide particles of the present invention are preferably surface-treated. Here, the surface treatment means coating the surface of the titanium oxide particles with an inorganic compound such as silica, a metal or a metal oxide, a reactive organosilicon compound, an organometallic compound or the like.

Further, in order to suppress image defects such as black spots and obtain an excellent high-resolution image, it is preferable that the titanium oxide particles are subjected to plural kinds of surface treatments, specifically, first. It is more preferable that the surface treatment is performed with an inorganic compound and, finally, the surface treatment is performed with a reactive organic silicon compound.

Specific examples of these surface treatment compounds include:
Examples of the inorganic compound include alumina, silica, zirconia, iron oxide, zinc oxide and the like. Among them, the treatment with alumina and silica is particularly preferable, and more preferably, the treatment with alumina is first, followed by the treatment with silica.
Inorganic treatment performed in stages is most suitable.

In the surface treatment of the reactive organosilicon compound, it is preferable to use the compound represented by the general formula (1).

In the organosilicon compound represented by the general formula (1), examples of the organic group in which carbon is directly bonded to silicon represented by R include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl and dodecyl. And other alkyl groups, phenyl, tolyl, naphthyl, biphenyl and other aryl groups, γ-glycidoxypropyl, β- (3,4
An epoxy-containing group such as -epoxycyclohexyl) ethyl,
γ-acryloxypropyl, γ-methacryloxypropyl-containing (meth) acryloyl group, γ-hydroxypropyl, 2,3-dihydroxypropyloxypropyl and other hydroxyl-containing groups, vinyl, propenyl and other vinyl-containing groups, γ-
Mercapto-containing groups such as mercaptopropyl, γ-aminopropyl, amino-containing groups such as N-β (aminoethyl) -γ-aminopropyl, γ-chloropropyl, 1,1,1-trifluoropropyl, nonafluorohexyl, Halogen-containing groups such as perfluorooctylethyl, other nitro,
Examples thereof include cyano-substituted alkyl groups. Examples of the hydrolyzable group of X include alkoxy groups such as methoxy and ethoxy, halogen groups, and acyloxy groups.

The organosilicon compound represented by the general formula (1) may be used alone or in combination of two or more kinds. Further, in a specific compound of the organosilicon compound represented by the general formula (1), when n is 2 or more, plural Rs may be the same or different. Similarly, when n is 2 or less, plural Xs may be the same or different. When two or more organosilicon compounds represented by the general formula (1) are used, R and X may be the same or different between the respective compounds.

The following compounds may be mentioned as examples of compounds with n = 0. Tetrachlorosilane, diethoxydichlorosilane, tetramethoxysilane, phenoxytrichlorosilane, tetraacetoxysilane, tetraethoxysilane, tetraallyloxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrakis (2-methoxyethoxy) silane, tetrabutoxysilane , Tetraphenoxysilane, tetrakis (2-ethylbutoxy) silane, tetrakis (2-ethylhexyloxy) silane and the like.

The following compounds may be mentioned as examples of compounds with n = 1. That is, methyltrichlorosilane, vinyltrichlorosilane, ethyltrichlorosilane, allyltrichlorosilane, propyltrichlorosilane, butyltrichlorosilane, chloromethyltriethoxysilane, methyltrimethoxysilane, mercaptomethyltrimethoxysilane, trimethoxyvinylsilane, ethyltrimethoxy. Silane, 3,3,4,4,5,5,6,6,6-nonafluorohexyltrichlorosilane, phenyltrichlorosilane, 3,3,3-trifluoropropyltrimethoxysilane, 3-chloropropyltrimethoxysilane ,
Butyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 2-aminoethylaminomethyltrimethoxysilane, benzyltrichlorosilane, methyltriacetoxysilane, chloromethyltriethoxysilane, ethyltriacetoxysilane , Phenyltrimethoxysilane, 3-
Allylthiopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-bromopropyltriethoxysilane, 3-allylaminopropyltrimethoxysilane, propyltriethoxysilane, hexyltrimethoxysilane, 3-aminopropyltriethoxysilane Examples thereof include silane, 3-methacryloxypropyltrimethoxysilane, bis (ethylmethylketoxime) methoxymethylsilane, pentyltriethoxysilane, octyltriethoxysilane, and dodecyltriethoxysilane.

The following compounds may be mentioned as examples of compounds having n = 2. Dimethyldichlorosilane, dimethoxymethylsilane, dimethoxydimethylsilane, methyl-3,
3,3-trifluoropropyldichlorosilane, diethoxysilane, diethoxymethylsilane, dimethoxymethyl-3,3,3-trifluoropropylsilane, 3-chloropropyldimethoxymethylsilane, chloromethyldiethoxysilane, diethoxydimethyl Silane, dimethoxy-3-mercaptopropylmethylsilane, 3,3
4,4,5,5,6,6,6-nonafluorohexylmethyldichlorosilane, methylphenyldichlorosilane,
Diacetoxymethylvinylsilane, diethoxymethylvinylsilane, 3-methacryloxypropylmethyldichlorosilane, 3-aminopropyldiethoxymethylsilane, 3- (2-aminoethylaminopropyl) dimethoxymethylsilane, t-butylphenyldichlorosilane,
3-methacryloxypropyldimethoxymethylsilane,
3- (3-cyanopropylthiopropyl) dimethoxymethylsilane, 3- (2-acetoxyethylthiopropyl) dimethoxymethylsilane, dimethoxymethyl-2-
Piperidinoethylsilane, dibutoxydimethylsilane,
3-dimethylaminopropyldiethoxymethylsilane,
Examples include diethoxymethylphenylsilane, diethoxy-3-glycidoxypropylmethylsilane, 3- (3-acetoxypropylthio) propyldimethoxymethylsilane, dimethoxymethyl-3-piperidinopropylsilane, and diethoxymethyloctadecylsilane. To be

The following compounds may be mentioned as examples of compounds in which n = 3. Trimethylchlorosilane, methoxytrimethylsilane, ethoxytrimethylsilane, methoxydimethyl-3,3,3-trifluoropropylsilane, 3-
Chloropropylmethoxydimethylsilane, methoxy-3
-Mercaptopropylmethylmethylsilane and the like.

Particularly, n = 1 and R is 4 to 8 carbon atoms.
Compounds of the following general formula (2) in which X is an alkyl group and X is an alkoxy group such as methoxy and ethoxy are preferred.

General formula (2) R-Si- (X) ₃ (R represents an alkyl group having 4 to 8 carbon atoms and X represents an alkoxy group) Preferred examples of the compound of the general formula (2) are as follows. The following compounds, trimethoxy-n-butylsilane, triethoxy-n-butylsilane, trimethoxy-i-butylsilane, trimethoxy-s-butylsilane, trimethoxyhexylsilane, trimethoxyoctylsilane trimethoxy-2-ethylhexylsilane can be mentioned.

In addition to the above, methylhydrogenpolysiloxane is particularly preferable. The surface treatment of the titanium oxide with the inorganic compound can be performed by a wet method. For example, the surface treatment of silica or alumina can be prepared as follows.

Titanium oxide particles (number average primary particle diameter: 50)
(nm) is dispersed in water at a concentration of 50 to 350 g / L to give an aqueous slurry, to which a water-soluble silicate or a water-soluble aluminum compound is added. After that, an alkali or an acid is added to neutralize, and silica or alumina is deposited on the surface of the titanium oxide particles. Subsequently, filtration, washing and drying are performed to obtain the target surface-treated titanium oxide. When sodium silicate is used as the water-soluble silicate, it can be neutralized with an acid such as sulfuric acid, nitric acid or hydrochloric acid. On the other hand, when aluminum sulfate is used as the water-soluble aluminum compound, it can be neutralized with an alkali such as sodium hydroxide or potassium hydroxide.

The subsequent surface treatment with the reactive organosilicon compound can be carried out by the following wet method.
That is, the reactive organosilicon compound is dissolved or suspended in an organic solvent or water, titanium oxide treated with the inorganic compound is added, and such a solution is stirred by mixing for about several minutes to one hour. Then, in some cases, after heat treatment, the titanium oxide surface is dried through a process such as filtration to coat the titanium oxide surface with a silicon compound group. The reactive organosilicon compound may be added to a suspension of titanium oxide dispersed in an organic solvent or water.

The surface treatment with methylhydrogenpolysiloxane can also be carried out by the same wet method as for the reactive organosilicon compound.

With respect to the amount of surface treatment, 0.1 to 50 parts by mass, more preferably 1 to 10 parts by mass of the surface treatment compound is preferably used with respect to 100 parts by mass of untreated titanium oxide in the charged amount at the time of the surface treatment. . When the amount of surface treatment is less than the above range, the surface treatment effect is not sufficiently imparted, and the dispersibility and the like are deteriorated, and the charging property of the photoreceptor is deteriorated. If the amount is more than the above range, the electrostatic characteristics of the photoconductor will be deteriorated and the residual potential will increase and the charging potential will decrease.

The surface treatment of the inorganic compound means a treatment of depositing an inorganic substance such as alumina, silica, or zirconia on the surface of titanium oxide particles. Alumina, silica or zirconia is deposited on these surfaces as alumina. ,
It also includes hydrates of silica and zirconia. Further, the surface treatment of the reactive organic silicon compound means that the reactive organic silicon compound is used in the treatment liquid.

Next, the average particle diameter of the titanium oxide particles used in the present invention is preferably in the range of 10 nm to 200 nm. An intermediate layer coating solution using titanium oxide particles having a number average primary particle size in the above range has good dispersion stability, and an intermediate layer formed from such a coating solution has sufficient potential stability and generation of black spots. Has a preventive function.

The particle size of the titanium oxide particles was magnified 10000 times by observation with a transmission electron microscope, and randomly increased to 1
This is a measurement value as an average diameter in the Feret direction by observing 00 particles as primary particles and performing image analysis.

The shape of the titanium oxide particles used in the present invention may be dendritic, acicular, granular, or the like. Titanium oxide having such a shape has anatase-type, rutile-type and amorphous-type crystal forms. However, rutile type titanium oxide is particularly preferable.

Next, an alkylene copolymer is used as the binder resin of the intermediate layer of the present invention. The alkylene copolymer used in the present invention is a copolymer using an alkylene monomer such as ethylene and propylene, and examples of the copolymerization component include vinyl acetate, acrylic acid, methacrylic acid, acrylic ester, and methacrylic acid. Examples thereof include acid esters, vinyl alcohol, vinyl chloride, vinylidene chloride, vinyl fluoride, acrylonitrile, vinyl acetal, maleic acid, maleic anhydride, hydroxystyrene, acrylamide and vinylpyrrolidone. Among them, ethylene is a preferred alkylene monomer, and preferred copolymerization components include vinyl acetate, acrylic acid, methacrylic acid, maleic acid, acrylic acid ester and methacrylic acid ester.

The proportion of the copolymer component in the ethylene copolymer is preferably 5 to 50% by mass, more preferably 10 to 40% by mass based on the whole (100% by mass). When the proportion of the copolymerization component is low, the solubility in the coating solvent, the coating property, etc. are lowered, and the adhesiveness with the support or the photosensitive layer is also lowered. On the other hand, when the proportion of the copolymerization component is high, the charge blocking property of the intermediate layer is lowered, and the effect of preventing the generation of black spots is reduced. As a measure of the molecular weight of this copolymer, M
FR (melt flow rate according to JIS-K6730-1981) is preferably 2 to 500 g / 10 min.

Specific examples of such an ethylene copolymer include the following commercially available resins.
That is, Sumitate HE-10, KA-10, KA-2
0, KA-30, KC-10, KE-10, Akhlift WH-302, WW-402, WM-506 (all manufactured by Sumitomo Chemical Co., Ltd.), Evaflex A-703, A-704,
Nucler N-010, N-035, N-1560
(Mitsui DuPont Chemical Co., Ltd.), Yucaron A-200
K, A-210M, A-210S, A-220M, A-
500W, A-510W (manufactured by Mitsubishi Yuka), Primacall 5980 (manufactured by Dow Chemical Co.), NUC6570,
6070, MB-730, 870 (all manufactured by Nippon Unicar Co., Ltd.) and the like.

Further, a binder resin other than the above ethylene copolymer may be used in combination in the intermediate layer of the present invention. Examples of such a binder resin include a vinyl chloride resin, a vinyl acetate resin, a polyamide resin, and a copolymer resin containing two or more of repeating units of these resins. In particular, a resin having good compatibility with the ethylene copolymer is preferable.

The amount of the surface-treated titanium oxide of the present invention dispersed in the binder resin is 50 to 1000 parts by mass, preferably 100 parts by mass with respect to 100 parts by mass of the binder resin.
To 500 parts by mass. By using the surface-treated titanium oxide in this range, the dispersibility of the titanium oxide can be kept good, and a good intermediate layer without black spots can be formed.

The thickness of the intermediate layer of the present invention is 0.1 to 15 μm.
Is preferable, and more preferably 0.5 to 7 μm. By using the film thickness within the above range, it is possible to form an intermediate layer having good electrophotographic characteristics without causing black spots.

Next, the constitution of the electrophotographic photosensitive member of the present invention other than the above-mentioned intermediate layer will be described. Conductive Support As the conductive support used in the photoreceptor of the present invention, either a sheet shape or a cylindrical shape may be used, but in order to design the image forming apparatus compactly, the cylindrical conductive support is used. Is preferred.

The cylindrical conductive support of the present invention means a cylindrical support required for endlessly forming an image by rotating, and has a straightness of 0.1 mm or less and a shake of 0.1 mm or less. Conductive supports in the range are preferred. When the circularity and the shake range are exceeded, good image formation becomes difficult.

As the conductive material, a metal drum of aluminum, nickel or the like, 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. It is preferable that the conductive support has a specific resistance of 10 ³ Ωcm or less at room temperature.

The conductive support used in the present invention may have a surface on which a sealed alumite film is formed. The alumite treatment is usually carried out in an acidic bath of 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 treatment in sulfuric acid, it is preferable that the sulfuric acid concentration is 100 to 200 g / l, the aluminum ion concentration is 1 to 10 g / l, the liquid temperature is around 20 ° C., and the applied voltage is about 20 V. It is not limited. The average thickness of the anodized film is usually 2
It is preferably 0 μm or less, and particularly preferably 10 μm or less.

Intermediate Layer In the present invention, the above-mentioned intermediate layer having a barrier function is provided between the conductive support and the photosensitive layer.

Photosensitive Layer The photosensitive layer structure of the photoconductor of the present invention may be a single-layer photosensitive layer structure in which one layer has a charge generating function and a charge transporting function on the above-mentioned intermediate layer, but more preferably, it is photosensitive. It is preferable that the function of the layer is separated into a charge generation layer (CGL) and a charge transport layer (CTL). By adopting a constitution in which the functions are separated, the increase in 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 negative charging photoreceptor, the charge generation layer (C
GL) and a charge transport layer (CTL) thereon. In the case of the photoconductor for positive charging, the order of the layers is the reverse of that of the photoconductor for negative charging. The most preferable photosensitive layer structure of the present invention is a negatively charged photosensitive member structure having the above-mentioned function separation structure.

The constitution 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). If necessary, a binder resin and other additives may be contained as other substances.

As the charge generating substance (CGM), a known charge generating substance (CGM) can be used. For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azurenium pigment or the like can be used. Among these, CGM that can minimize the increase in residual potential with repeated use
Has a steric structure and a potential structure capable of forming a stable aggregation structure among a plurality of molecules, and specific examples thereof include a phthalocyanine pigment and a perylene pigment CGM having a specific crystal structure. For example, the Bragg angle 2θ with respect to Cu-Kα rays
CGMs such as titanyl phthalocyanine having a maximum peak at 27.2 ° and benzimidazole perylene having a maximum peak at 22.4 at 27.2 have almost no deterioration due to repeated use, and the residual potential increase can be reduced.

When a binder is used as a CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferable resin is a formal resin, a butyral resin, a silicone resin, a silicone-modified butyral resin, or a phenoxy resin. Resin etc. are mentioned. The ratio of the binder resin to the charge generating substance 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 due to repeated use can be minimized. The thickness of the charge generation layer is preferably 0.01 μm to 2 μm.

Charge Transport Layer The charge transport layer contains a charge transport material (CTM) and a binder resin for dispersing CTM to form a film. Other substances may optionally contain additives such as antioxidants.

As the charge transport material (CTM), a known charge transport material (CTM) can be used. 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 a suitable binder resin to form a layer. Among these, CTM that can minimize the increase in residual potential due to repeated use has high mobility and has a characteristic that the difference in ionization potential with CGM to be combined is 0.5 (eV) or less, and preferably 0. It is 0.25 (eV) or less.

The ionization potentials of CGM and CTM are measured by a surface analyzer AC-1 (manufactured by Riken Keiki Co., Ltd.).

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

The most preferred binder for these CTLs is polycarbonate resin. Polycarbonate resin is most preferable in improving dispersibility of CTM 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 10-40 μm.

Surface Layer The photoreceptor of the present invention may be provided with a surface layer. As a preferable surface layer, a surface layer using a siloxane resin can be mentioned.

Although the most preferable layer constitution of the photoconductor of the present invention has been exemplified above, a photoconductor layer constitution other than the above may be used in the present invention.

The intermediate layer and the photosensitive layer of the present invention are formed by melting or dispersing the materials of the respective layers described above in a suitable solvent or dispersion medium and coating the solution. As the solvent or dispersion medium used, n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methylethylketone, methylisopropylketone, cyclohexanone, benzene, toluene,
Xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2
-Trichloroethane, 1,1,1-trichloroethane,
Examples include trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, 1-propanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cellosolve.

As the coating processing method for producing the electrophotographic photosensitive member of the present invention, coating processing methods such as dip coating, spray coating and circular amount regulation type coating are used. Does not dissolve the lower layer as much as possible,
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 (a circular slide hopper type is a typical example) coating. The spray coating is described in detail in, for example, JP-A-3-90250 and JP-A-3-269238, and the circular amount regulating coating is described in JP-A-58-1890.
This is described in detail in Japanese Patent No. 61.

FIG. 1 is a sectional view of an image forming apparatus as an example of the image forming method of the present invention. In FIG. 1, reference numeral 50 denotes a photosensitive drum (photosensitive member) which is an image bearing member, and is a photosensitive member in which an organic photosensitive layer is coated on the drum, and the resin layer of the present invention is coated thereon, which is grounded. It is driven and rotated clockwise. 52
Is a charging device (charging means) of the scorotron, which gives uniform charging to the peripheral surface of the photosensitive drum 50 by corona discharge. Prior to the charging by the charger 52, in order to eliminate the history of the photosensitive member in the pre-image formation, the pre-charging pre-exposure unit 51 using a light emitting diode or the like may be used to remove the charge on the peripheral surface of the photosensitive member.

After the photosensitive member is uniformly charged, an image exposing device 53 as an image exposing means performs image exposure based on an image signal. The image exposure device 53 in this figure uses a laser diode (not shown) as an exposure light source. Rotating polygon mirror 5
Scanning on the photosensitive drum is performed by the light whose optical path is bent by the reflection mirror 532 through the 31, f.theta.
An electrostatic latent image is formed.

Here, the reversal development process of the present invention means that the surface of the photoconductor is uniformly charged by the charger 52 to develop the image-exposed region, that is, the exposed portion potential (exposed portion region) of the photosensitive member. It is an image forming method that visualizes by a step (means). On the other hand, the unexposed portion potential is not developed by the developing bias potential applied to the developing sleeve 541.

The electrostatic latent image is then developed by the developing device 54 as a developing means. A developing device 54 containing a developer composed of toner and carrier is provided on the periphery of the photosensitive drum 50, and development is performed by a developing sleeve 541 that contains a magnet and holds the developer and rotates.
Inside the developing unit 54, the developer stirring and conveying members 544, 543,
The developer is constituted by a conveyance amount regulating member 542 and the like, and the developer is agitated and conveyed to be supplied to the developing sleeve, and the supply amount is controlled by the conveyance amount regulating member 542. The amount of the developer conveyed varies depending on the linear velocity of the applied organic electrophotographic photosensitive member and the specific gravity of the developer, but is generally 20 to 2
It is in the range of 00 mg / cm ² .

The developer is, for example, a carrier in which an insulating resin is coated around the above-mentioned ferrite core, a coloring agent such as carbon black and a charge control agent mainly composed of the above-mentioned styrene acrylic resin, and a charge control agent of the present invention. Colored particles consisting of low molecular weight polyolefin, and toner externally added with silica, titanium oxide, etc., the developer is transported to the developing zone with the layer thickness regulated by the transport amount regulating member, and development is carried out. . At this time, normally, a DC bias is applied between the photosensitive drum 50 and the developing sleeve 541, and if necessary, an AC bias voltage is applied to develop. Further, the developer is developed in a state of being in contact with or non-contacting with the photoreceptor. The potential sensor 547 measures the potential of the photoconductor.
Is provided above the developing position as shown in FIG.

After the image formation, the recording paper P is fed to the transfer area by the rotation operation of the paper feed roller 57 when the transfer timing is adjusted.

In the transfer area, a transfer electrode (transfer means: transfer device) 58 is pressed against the peripheral surface of the photosensitive drum 50 in synchronism with the transfer timing, and the supplied recording paper P is sandwiched and transferred. It

Then, the recording paper P is de-charged by a separating electrode (separator) 59 which is brought into pressure contact with the transfer roller almost at the same time, separated by the peripheral surface of the photoconductor drum 50 and conveyed to the fixing device 60, and heated by the heat roller. The toner is fused by heating and pressurizing the pressure roller 601 and the pressure roller 602, and then the toner is discharged to the outside of the apparatus through the paper discharge roller 61. The transfer electrode 58 and the separation electrode 59 are withdrawn from the peripheral surface of the photoconductor drum 50 after the recording paper P has passed and are prepared for the next toner image formation.

On the other hand, after the recording paper P is separated, the photosensitive drum 50 is subjected to pressure contact with a blade 621 of a cleaning device (cleaning means) 62 to remove and clean residual toner,
The pre-charging pre-exposure unit 51 again removes electricity and the charger 52 charges, and the next image forming process starts.

Reference numeral 70 denotes a removable process cartridge in which a photoconductor, a charger, a transfer device, a separator and a cleaning device are integrated.

The electrophotographic photoreceptor of the present invention is generally applied to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers and liquid crystal shutter type printers, but further, displays, recording and light printing to which electrophotographic technology is applied. It can also be widely applied to devices such as plate making and facsimile.

[0081]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto. In addition, "part" in a sentence represents a "mass part."

Example 1 Photoreceptor 1 was prepared as follows.

The following intermediate layer coating solution was dip-coated on a cylindrical aluminum conductive substrate having a diameter of 80 mm to form an intermediate layer having a dry film thickness of 4.0 μm.

<Intermediate Layer Coating Liquid> Ethylene-vinyl acetate-methacrylic acid copolymer (ELVAX4260: manufactured by Mitsui DuPont Chemical Co., Ltd.) 10 parts Titanium oxide “SMT500SAS” (first: silica / alumina treatment—second: methyl hydrogen Polysiloxane treatment: rutile type: manufactured by Teika Co., Ltd.) 30 parts Toluene 100 parts The above was dispersed using an ultrasonic homogenizer to prepare an intermediate layer coating solution.

Next, the following charge generation layer coating liquid was applied by a circular slide hopper to form a charge generation layer having a dry film thickness of 0.3 μm.

<Charge Generating Layer Coating Liquid> 12 parts of a charge generating substance (Y-type titanyl phthalocyanine pigment having prominent peaks at X-ray diffraction Bragg angles 2θ of 9.5 degrees, 24.1 degrees and 27.2 degrees). Polyvinyl butyral resin "ESREC BL-1" (manufactured by Sekisui Chemical Co., Ltd.) 24 parts t-butyl acetate 300 parts The above components were mixed and dispersed by a sand grinder to prepare a charge generation layer coating liquid.

The following charge transport layer coating liquid was applied onto the charge generation layer using a circular slide hopper to form 110
C .; heat-cured for 60 minutes to form a charge transport layer having a dry film thickness of 22 .mu.m, to prepare a photoreceptor 1.

[0088]   <Charge transport layer coating liquid>   200 parts of charge transport material (compound A below)   Polycarbonate "Upilon Z300" (manufactured by Mitsubishi Gas Chemical Company) 300 parts   2,6-di-t-butyl-4-phenylphenol 5 parts   1,2-dichloroethane 2000 parts The above materials were mixed and dissolved to prepare a charge generation layer coating liquid.

Examples 2 to 5 The titanium oxide shown in Table 1 was used in place of the titanium oxide used in Example 1 and the charge transport layer thickness and the intermediate layer thickness shown in Table 2 were used. Photoconductors 2 to 5 were prepared in the same manner as in 1.

[0090]

[Chemical 1]

Examples 6 to 10 The ethylene copolymer shown in Table 2 was used in place of the ethylene-vinyl acetate-methacrylic acid copolymer of the intermediate layer used in Example 1, and the charge transport layer shown in Table 2 was used. Photosensitive members 6 to 10 were prepared in the same manner as in Example 1 except that the film thickness and the thickness of the intermediate layer were changed.

Comparative Example 1 Instead of the ethylene-vinyl acetate-methacrylic acid copolymer of the intermediate layer of Example 1, a polyamide resin "CM8000" was used.
A photoconductor 11 was produced in the same manner as in Example 1 except that (Toray) was used.

Comparative Example 2 Photoreceptor 12 was prepared in the same manner as in Example 1 except that titanium oxide was removed from the intermediate layer of Example 1 so that the dry film thickness was 1.0 μm.
Was produced.

[0094]

[Table 1]

[0095]

[Table 2]

(Evaluation) Each of the photoconductors is attached to the Konica 7050.
Remodeling machine (corona charging method, laser exposure 400 dpi
(Dots per 2.54 cm) recording, average particle size 6.
5μm polymerized toner) at room temperature and normal humidity (20 ° C, 50%)
In RH), a continuous repeating cycle of charging, exposure, and static elimination was performed 6000 times, and the unexposed portion potential VH and the exposed portion potential VL were measured by the potential sensor set at the developing position at the start and immediately after the end. High temperature and high humidity (30 ℃, 8
3% RH), low temperature and low humidity (7 ° C, 21% RH)
Perform continuous image copying of 10,000 A4 sheets,
The presence or absence of black spots and other image defects was confirmed. The results are shown in Table 3.

[0097]

[Table 3]

As is clear from Table 3, the electrophotographic photosensitive member of the present invention remarkably improves the generation of black spots without impairing the electrostatic characteristics. On the other hand, in the electrophotographic photosensitive member having the intermediate layer other than the present invention, the generation of black spot image defects or the decrease in image density due to the increase in the exposed portion potential is observed.

[0099]

As is clear from the examples, the electrophotographic photosensitive member having the intermediate layer containing the titanium oxide particles and the alkylene copolymer of the present invention does not cause image defects such as black spots and is environmentally friendly. It can be seen that the electrophotographic characteristics are maintained well even when the values are changed.

[Brief description of drawings]

FIG. 1 is a sectional view of an image forming apparatus as an example of an image forming method of the present invention.

[Explanation of symbols]

50 photoconductor drum (or photoconductor) 51 Pre-charge exposure unit 52 Charger 53 Image exposure device 54 Developer 541 Development sleeve 543,544 developer stirring and conveying member 547 potential sensor 57 Paper Feed Roller 58 transfer electrode 59 Separation electrode (separator) 60 fixing device 61 Paper ejection roller 62 cleaning device 70 Process cartridge

Claims (13)

[Claims] 1. An electrophotographic photosensitive member having an intermediate layer and a photosensitive layer on a conductive support, wherein the intermediate layer contains at least titanium oxide particles and an alkylene copolymer. body. 2. The electrophotographic photosensitive member according to claim 1, wherein the titanium oxide particles are surface-treated. 3. The surface treatment is a plurality of surface treatments,
The first surface treatment is a surface treatment with an inorganic compound,
The electrophotographic photosensitive member according to claim 2, wherein the final surface treatment is a surface treatment with a reactive organosilicon compound. 4. The electrophotographic photosensitive member according to claim 3, wherein the inorganic compound is at least one of silica and alumina, and the reactive organosilicon compound is methylhydrogenpolysiloxane. 5. The inorganic compound is at least one of silica and alumina, and the reactive organosilicon compound is an organosilicon compound represented by the following general formula (1). Electrophotographic photoreceptor. General formula (1) (R) _n -Si- (X) _4-n (In the formula, R represents an organic group in which carbon is directly bonded to a silicon atom, X represents a hydrolyzable group, and n represents It represents an integer of 0 to 3.) 6. The mass ratio of the titanium oxide particles and the alkylene copolymer is 100 to 500 parts of titanium oxide particles to 100 parts of the alkylene copolymer, and the mass ratio of the titanium oxide particles to the alkylene copolymer is 100 to 500 parts. The electrophotographic photoreceptor according to the item. 7. The average particle size of the titanium oxide particles is 10 n.
It is m or more and 200 nm or less, Claim 1 characterized by the above-mentioned.
7. The electrophotographic photosensitive member according to any one of items 1 to 6. 8. The electrophotographic photosensitive member according to claim 1, wherein the alkylene copolymer is an ethylene copolymer. 9. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer comprises a charge generation layer and a charge transport layer. 10. The charge generation layer contains a titanyl phthalocyanine pigment.
The electrophotographic photosensitive member according to 1. 11. An image forming method comprising an electrophotographic photosensitive member and at least a charging step, an image exposing step, a developing step, a transferring step, and a cleaning step, wherein the electrophotographic photosensitive member is an image forming method in which the image is repeatedly formed. 10. An image forming method, which is the electrophotographic photosensitive member according to any one of items 10 to 10. 12. An image forming apparatus using the image forming method according to claim 11. 13. An electrophotographic photosensitive member according to claim 1 and at least one of a charging means, an image exposing means, a developing means, a transferring means, and a cleaning means, which are integrally provided. A process cartridge characterized in that it can be taken in and out of the image forming apparatus.