JP2012013750A - Organic photoreceptor, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic photoreceptor in which a protective layer composed of a composition using a radical polymerizable compound is increased in hardness, and an abrasion-resistant property and scratch resistance are improved, and the occurrence of a blurred image or a crack is prevented; an image forming apparatus using the same; and a process cartridge used for the apparatus.SOLUTION: There is provided an organic photoreceptor formed by laminating a photosensitive layer and a protective layer on a conductive support body, the organic photoreceptor being characterized in that the protective layer is formed by polymerizing a composition containing a compound having a hept- or more-functional polymerizable functional group and a compound having a polymerizable functional group whose viscosity is between 30 and 3000 mPa s at 25°C.

Description

  The present invention relates to an organic photoreceptor, an image forming apparatus, and a process cartridge used for electrophotographic image formation.

  Electrophotographic photoconductors move from inorganic photoconductors such as Se, arsenic, arsenic / Se alloys, CdS, ZnO, etc. to organic photoconductors with excellent advantages such as pollution and ease of manufacture, and various materials are used. Organic photoreceptors (hereinafter also simply referred to as photoreceptors) have been developed.

  However, the organophotoreceptor does not have sufficient wear resistance, and the active material such as ozone and NOx generated from the charging process deteriorates the charge transport material, resulting in image density due to deterioration of sensitivity and increase in residual potential. Deterioration and image blur are likely to occur.

  In order to improve the wear resistance of the organic photoreceptor, a photoreceptor having a curable protective layer formed from a radical polymerizable compound and a radical polymerizable compound having a charge transporting ability has been proposed (for example, patents). Reference 1). However, since the photoreceptor proposed in Patent Document 1 contains a group having a charge transporting ability that becomes a steric hindrance in the resin structure of the protective layer, the progress of the crosslinked structure is hindered, and sufficient wear resistance characteristics are obtained. It is difficult to form, and unreacted groups remain in the protective layer, and image blurring tends to occur.

  Patent Document 1 also describes that a trifunctional radically polymerizable compound and a pentafunctional or hexafunctional radically polymerizable compound are used in combination. However, the combination of these radically polymerizable compounds is also premised on the use of a radically polymerizable compound having charge transporting ability, and the protective layer formed from these combined compositions still has sufficient wear resistance characteristics, Scratch resistance, image blur, etc. cannot be solved sufficiently. Furthermore, the trifunctional radically polymerizable compound penetrates into the lower photosensitive layer during the formation of the protective layer and generates cracks in the photosensitive layer. However, there is no description of measures for preventing penetration into these lower layers.

JP 2009-251140 A

  The present invention has been made in view of the problems described above, and its purpose is to increase the hardness of a protective layer formed from a composition using a radical polymerizable compound, and to improve wear resistance and scratch resistance. Further, it is to provide an organic photoreceptor in which occurrence of image blurring and cracks is prevented, and to provide an image forming apparatus and a process cartridge using the organic photoreceptor.

  It is important for the inventors of the present application to reduce the residual unreacted groups after curing of the radical polymerizable compound in the protective layer in order to solve the above problems, and to the photosensitive layer of the radical polymerizable compound. As a result, in combination with a radical polymerizable compound, a radical polymerizable compound having 7 or more functional groups and a 2 to 4 functional radical having specific viscosity characteristics are required. The inventors have found that the combined use of a polymerizable compound is effective for solving the problems of the present invention, and achieved the present invention.

  The object of the present invention can be achieved by having the following configuration.

  1. Polymerization in which a photosensitive layer and a protective layer are laminated on a conductive support, and the protective layer has a compound having a polymerizable functional group having 7 or more functional groups and a viscosity at 25 ° C. of 30 to 3000 mPa · s. An organic photoreceptor, which is a protective layer formed by polymerizing a composition containing a compound having a functional functional group.

  2. 2. The organophotoreceptor according to 1 above, wherein the compound having a polymerizable functional group having 7 or more functional groups is tripentaerythritol or a polyfunctional acrylate or methacrylate of tetrapentaerythritol.

  3. 3. The organophotoreceptor according to 1 or 2, wherein the compound having a polymerizable functional group having a viscosity at 25 ° C. of 30 to 3000 mPa · s is a bifunctional to tetrafunctional polyfunctional acrylate or methacrylate.

  4). 4. The organophotoreceptor according to any one of items 1 to 3, wherein the protective layer contains at least metal oxide fine particles.

  5. 5. The organophotoreceptor according to any one of 1 to 4 above, wherein the metal oxide fine particles are alumina fine particles or tin oxide fine particles surface-treated with a reactive compound having a surface treatment group.

  6). 6. The organophotoreceptor according to 5 above, wherein the reactive compound having a surface treatment group described above is a compound containing either an acryloyloxy group or a methacryloyloxy group.

  7). Organic photoreceptor, charging means for charging the organic photoreceptor, exposure means for forming an electrostatic latent image on the organic photoreceptor by image exposure, developing means for developing the electrostatic latent image into a toner image, the toner In an image forming apparatus having a transfer means for transferring an image to a transfer medium and a cleaning means for removing toner remaining on the organic photoreceptor after the transfer, the organic photoreceptor has a photosensitive layer and a protective layer laminated on a conductive support. And a protective layer containing a compound having a polymerizable functional group having 7 or more functional groups and a compound having a polymerizable functional group having a viscosity at 25 ° C. of 30 to 3000 mPa · s. An image forming apparatus comprising a protective layer formed by polymerizing a product.

  8). The process cartridge used in the image forming apparatus described in item 7 integrally includes at least one of the organic photosensitive member described in any one of items 1 to 6 and a charging unit, an image exposing unit, and a developing unit. And a process cartridge configured to be removable from and into the image forming apparatus.

  By using the organophotoreceptor of the present invention, it is possible to provide an organophotoreceptor with improved wear resistance and scratch resistance and capable of obtaining a good electrophotographic image free from cracks and image blurring.

1 is a schematic view in which functions of an image forming apparatus of the present invention are incorporated. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention. 1 is a cross-sectional view of a color image forming apparatus using an organic photoreceptor of the present invention.

  The organic photoreceptor of the present invention is an organic photoreceptor obtained by laminating a photosensitive layer and a protective layer on a conductive support, and the protective layer has a compound having a polymerizable functional group having 7 or more functional groups and a viscosity at 25 ° C. It is a protective layer formed by polymerizing a composition containing a compound having a polymerizable functional group of 30 to 3000 mPa · s.

  By having the above structure, the organic photoreceptor of the present invention has improved wear resistance and scratch resistance, and can provide a good electrophotographic image free from cracks and image blurring.

  Hereinafter, the present invention will be described in detail.

  It describes about the protective layer concerning this invention.

  The protective layer according to the present invention is formed by polymerizing a composition containing a compound having a polymerizable functional group having 7 or more functional groups and a compound having a polymerizable functional group having a viscosity of 30 to 3000 mPa · s at 25 ° C. To do.

  Examples of the compound having a polymerizable functional group having 7 or more functional groups include tripentaerythritol such as tripentaerythritol octamethacrylate, tripentaerythritol heptamethacrylate, tripentaerythritol octaacrylate, tetrapentaerythritol decamethacrylate, tetrapentaerythritol dodecamethacrylate, etc. A polyfunctional acrylate or methacrylate of tetrapentaerythritol is preferably used.

  Here, the above-mentioned polyfunctional acrylate or methacrylate means a plurality (7 or more) of acrylate groups or methacrylate groups. For example, by a condensation reaction of tripentaerythritol or tetrapentaerythritol with acrylic acid or methacrylic acid. The polyfunctional acrylate or methacrylate produced | generated is said.

  The synthesis of the compound having a polymerizable functional group having 7 or more functional groups can be performed by the method exemplified below. Here, tripentaerythritol octaacrylate is described as an example.

  The reactor was charged with 100 g of tripentaerythritol, 162 g of acrylic acid, 91 g of cyclohexane, 8.0 g of concentrated sulfuric acid, and 1.2 g of hydroquinone monomethyl ether, and reacted at 80 ° C. to 90 ° C. for 8 hours while blowing air at 10 ml / min. After completion of the reaction, 530 g of toluene was added to the reaction mixture, and the resulting organic layer was washed with a 25% by mass aqueous sodium hydroxide solution and then with a 10% by mass aqueous sodium sulfate solution, dried using magnesium sulfate, and then a polymerization inhibitor ( Hydroquinone monomethyl ether) 0.2 g was added, concentrated, and dried to obtain 183 g of tripentaerythritol polyacrylate. The obtained tripentaerythritol acrylate is usually obtained as a mixture of tripentaerythritol hexaacrylate, tripentaerythritol pentaacrylate, tripentaerythritol octaacrylate, etc., but each can be separated by fractional distillation.

  On the other hand, as a compound having a polymerizable functional group having a viscosity at 25 ° C. of 30 to 3000 mPa · s, trimethylolpropane trimethacrylate (viscosity: 44 mPa · s), trimethylolpropane triacrylate (viscosity: 110 mPa · s), 2-4 functional acrylates or methacrylates such as pentaerythritol tetraacrylate (viscosity: 342 mPa · s), ethoxylated bisphenol A dimethacrylate (viscosity: 700 mPa · s), tricyclodecane dimethanol diacrylate (viscosity: 130 mPa · s) Can be mentioned as preferred.

  A compound having a polymerizable functional group having a viscosity at 25 ° C. of 30 to 3000 mPa · s can be synthesized by a known method, but a commercially available product can also be used.

  As described above, the present invention includes a polyfunctional acrylate or methacrylate having 7 or more functional groups and a 2 to 4 functional acrylate or methacrylate having a viscosity of 30 to 3000 mPa · s at 25 ° C. in the composition forming the protective layer, The composition is polymerized, for example, by chain polymerization to form a protective layer.

  The viscosity of the compound having a functional group having 7 or more functional groups and the compound having a functional group having 2 to 4 functional groups is an E-type rotational viscometer (manufactured by Tokyo Keiki Co., Ltd.) in which water in a thermostatic bath set at 25 ° C. is circulated. VISCONIC, ELD type).

  When the viscosity at 25 ° C. is less than 30 mPa · s, when the protective layer composition is applied on the photosensitive layer, the bifunctional or tetrafunctional acrylate or methacrylate penetrates into the photosensitive layer and cracks are formed in the photosensitive layer. generate. On the other hand, when it exceeds 3000 mPa · s, the polymerization reaction with a compound having a polymerizable functional group having 7 or more functional groups decreases, and the wear resistance and scratch resistance of the protective layer deteriorate.

  The protective layer according to the present invention preferably contains metal oxide particles. As the metal oxide particles, the following are preferable.

(Metal oxide particles)
The metal oxide particles are preferably metal oxide 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 include metal oxide particles such as 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 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 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 particles is a photographic image (excluding aggregated particles) taken with a scanning electron microscope (manufactured by JEOL Ltd.) with a magnification of 10000 times, and 300 particles randomly taken by 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 inorganic fine particles are preferably surface-treated with a surface treatment agent such as a silane coupling agent or a titanium coupling agent. Examples of the surface treatment agent include well-known silane cups such as t-butylphenyldichlorosilane, 3-methacryloxypropyldimethoxymethylsilane, 3- (3-cyanopropylthiopropyl) dimethoxymethylsilane, and hydrogenpolysiloxane compounds. A ring agent, a titanium coupling agent, or the like is used.

  It is also preferable to use metal oxide particles that have been surface treated with a reactive compound having a surface treatment group.

  That is, by reacting a reactive compound having a surface treatment group with metal oxide particles having a hydroxyl group on the surface (generally, metal oxide particles not subjected to surface treatment have a hydroxyl group on the surface), Metal oxide particles surface-treated with a reactive compound having a surface treatment group can be obtained.

  Examples of the reactive compound having a surface treatment group are given 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) 3 Si (CH 3) (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 (OC 2 H 5) (OCH 3) 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
When the polymerizable compound according to the present invention is reacted, a method of reacting by electron beam cleavage, a method of reacting with light or heat by adding a radical polymerization initiator or a cationic polymerizable initiator, and the like are used. As the polymerization initiator, either a photopolymerization initiator or a thermal polymerization initiator can be used. Further, both light and heat initiators can be used in combination.

As a radical polymerization initiator of these photocurable compounds, a photopolymerization initiator is preferable, and among them, an alkylphenone compound or a phosphine oxide compound is preferable. In particular, a compound having an α-hydroxyacetophenone structure or an acylphosphine oxide structure is preferable. The compound that initiates cationic polymerization, e.g., diazonium, ammonium, iodonium, sulfonium, aromatic onium compounds such as phosphonium ^{_{B (C 6 F 5) 4}} -, PF 6 -, AsF 6 -, SbF 6 - , CF ₃ SO ₃ ^- ionic polymerization initiator or sulfonic acid sulfonated materials that generate a such as salts, halides or generates hydrogen halide, can be mentioned nonionic polymerization initiator such as iron arene complex. In particular, a sulfonate that generates a sulfonic acid that is a nonionic polymerization initiator and a halide that generates a hydrogen halide are preferable.

The photoinitiator used preferably below is illustrated.
Examples of α-aminoacetophenone series

Examples of α-hydroxyacetophenone compounds

Examples of acylphosphine oxide compounds

  In order to form a protective layer by polymerizing a photopolymerizable compound, a protective layer coating solution (a composition containing a polymerizable compound or surface-treated metal oxide particles) is applied on the photosensitive layer, After the primary drying to the extent that the fluidity of the coating film is lost, the protective layer is cured by irradiating with ultraviolet rays, and further, the secondary drying is performed to make the amount of volatile substances in the coating film a specified amount. The method is preferred.

  As a device for irradiating ultraviolet rays, a known device used for curing an ultraviolet curable resin can be used.

The amount of ultraviolet rays (mJ / cm ² ) for curing the resin with ultraviolet rays is preferably controlled by the ultraviolet irradiation intensity and irradiation time.

  On the other hand, as the thermal polymerization initiator, ketone peroxide compounds, peroxyketal compounds, hydroperoxide compounds, dialkyl peroxide compounds, diacyl peroxide compounds, peroxydicarbonate compounds, peroxyester compounds Compounds and the like are used, and these thermal polymerization initiators are disclosed in company product catalogs.

  In the present invention, these thermal polymerization initiators are mixed with a composition containing a polymerizable compound, surface-treated metal oxide particles and the like in the same manner as the photopolymerization initiator, and a protective layer is applied. A coating solution is prepared, and the coating solution is coated on the photosensitive layer and then dried by heating to form the protective layer according to the present invention.

  Also, as for the coating method of the protective layer, the dip coating in which the entire photoreceptor is immersed in the protective layer coating solution increases the diffusion of the polymerization initiator to the lower layer, so that the photosensitive layer film under the protective layer is not dissolved as much as possible. Therefore, it is preferable to use a coating processing method such as a volume regulation type (a circular slide hopper type is a typical example). The circular amount regulation type coating is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

  These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.1-20 mass parts with respect to 100 mass parts of an acryl-type compound, Preferably it is 0.5-10 mass parts.

  The protective layer of the present invention can further contain various charge transport materials and antioxidants, and various lubricant particles can be added. For example, fluorine atom-containing resin 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. The ratio of the lubricant particles in the protective layer is preferably 5 to 70 parts by mass, more preferably 10 to 60% by mass with respect to 100 parts by mass of the acrylic resin. The average particle size of the lubricant particles is preferably 0.01 μm to 1 μm. Particularly preferably, it is 0.05 μm to 0.5 μm. The molecular weight of the resin can be appropriately selected and is not particularly limited.

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

  The protective layer of the present invention is preferably subjected to reaction by irradiation with actinic radiation after natural drying or heat drying after coating.

  As the coating method, a known method such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, and a slide hopper method can be used as in the case of the intermediate layer and the photosensitive layer. .

  The photoreceptor of the present invention is capable of generating a cured resin by irradiating actinic rays on the coating to generate radicals and polymerizing, and curing by forming a cross-linking bond between molecules and within the molecule. preferable. As the active ray, ultraviolet rays and electron beams are particularly preferable.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² . The power of the lamp is preferably 0.1 kW to 5 kW, particularly preferably 0.5 kW 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 0.5 to 10 Mrad.

  The irradiation time for obtaining the necessary irradiation amount of active rays is preferably 0.1 second to 10 minutes, and more preferably 0.1 second to 5 minutes from the viewpoint of work efficiency.

  As the actinic radiation, ultraviolet rays are easy to use and are particularly preferable.

  The photoreceptor of the present invention can be dried before and after irradiating active rays and during irradiation with active rays, and the timing of drying can be appropriately selected by combining them.

  Drying conditions can be appropriately selected depending on the type of solvent, film thickness, and the like. The drying temperature is preferably room temperature to 180 ° C, particularly preferably 80 ° C to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes to 100 minutes.

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

  Below, the structure of organic photoreceptors other than the said protective layer is 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 photoconductors such as a photoconductor composed of an organic charge generating material or an organic charge transport material, a photoconductor composed of a polymer complex with a charge generating function and a charge transport function are contained.

  The organophotoreceptor of the present invention is obtained by sequentially laminating at least a photosensitive layer and a protective layer as described above on a conductive support. Specifically, the layer structure as shown below is exemplified. Can do.

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

  The layer structure of the organic photoreceptor of the present invention will be described focusing on the above 1).

[Conductive support]
The support used in the present invention may be any one as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or a sheet, aluminum or copper Metal foils such as those laminated on plastic films, aluminum, indium oxide and tin oxide deposited on plastic films, metals with conductive layers applied alone or with a binder resin, plastic films and For example, paper.

[Middle layer]
In the present invention, an intermediate layer having a barrier function and an adhesive function may be provided between the conductive layer and the photosensitive layer.

  The intermediate layer can be formed by dip coating or the like by dissolving a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane and gelatin in a known solvent. Of these, an alcohol-soluble polyamide resin is preferred.

  Various conductive fine particles and metal oxides can be contained for the purpose of adjusting the resistance of the intermediate layer. For example, various metal oxides such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide. Ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide can be used.

  You may use these metal oxides 1 type or in mixture of 2 or more types. When two or more types are mixed, it may take the form of a solid solution or fusion. The average particle diameter of such a metal oxide is preferably 0.3 μm or less, more preferably 0.1 μm or less.

  As the solvent used for the intermediate layer, a solvent in which inorganic particles are well dispersed and the polyamide resin is dissolved is preferable. Specifically, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol and the like are excellent in solubility and coating performance of the polyamide resin. In addition, examples of co-solvents that can be used in combination with the above-described solvent to obtain favorable effects in order to improve storage stability and particle dispersibility include methanol, benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  The density | concentration of binder resin is suitably selected according to the film thickness and production rate of an intermediate | middle layer.

  When the inorganic particles are dispersed, the mixing ratio of the inorganic particles to the binder resin at the time is preferably 20 to 400 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

  As a means for dispersing the inorganic particles, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.

  The method for drying the intermediate layer can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  The thickness of the intermediate layer is preferably from 0.1 to 15 μm, more preferably from 0.3 to 10 μm.

(Charge generation layer)
The charge generation layer used in the present invention preferably contains a charge generation material and a binder resin, and is formed by dispersing and coating the charge generation material in a binder resin solution.

  Examples of the charge generation material include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and phthalocyanine pigments. It is not something. These charge generating substances can be used alone or in a form dispersed in a known resin.

  As the binder resin of the charge generation layer, a known resin can be used, for example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, Polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (eg, vinyl chloride-vinyl acetate copolymer resins, chlorides) Vinyl-vinyl acetate-maleic anhydride copolymer resin) and poly-vinylcarbazole resin, but are not limited thereto.

  The charge generation layer is formed by dispersing a charge generation material in a solution in which a binder resin is dissolved in a solvent using a disperser to prepare a coating solution, and applying the coating solution to a certain film thickness using a coating device. It is preferable to prepare the film by drying.

  Solvents for dissolving and coating the binder resin used in the charge generation layer include, for example, toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, Examples include butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine, but are not limited thereto.

  As a means for dispersing the charge generating material, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.

  The mixing ratio of the charge generating material to the binder resin is preferably 1 to 600 parts by weight, more preferably 50 to 500 parts by weight based on 100 parts by weight of the binder resin. The thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm. It should be noted that the coating solution for the charge generation layer can prevent the occurrence of image defects by filtering foreign matter and aggregates before coating. The pigment can also be formed by vacuum deposition.

(Charge transport layer)
The charge transport layer used in the photoreceptor of the present invention contains a charge transport material (CTM) and a binder resin, and is formed by dissolving and coating the charge transport material in a binder resin solution.

  Examples of charge transport materials include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds Oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1- Two or more kinds of vinylpyrene, poly-9-vinylanthracene, triphenylamine derivatives and the like may be mixed and used.

  A known resin can be used as the binder resin for the charge transport layer, and polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic ester resin, and styrene-methacrylic acid. Examples include ester copolymer resins, and polycarbonate is preferred. Further, BPA, BPZ, dimethyl BPA, BPA-dimethyl BPA copolymer and the like are preferable in terms of crack resistance, wear resistance, and charging characteristics.

  The charge transport layer is preferably formed by dissolving the binder resin and the charge transport material to prepare a coating solution, applying the coating solution to a certain film thickness with a coating machine, and drying the coating film.

  Examples of the solvent for dissolving the binder resin and the charge transport material include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, and tetrahydrofuran. 1,4-dioxane, 1,3-dioxolane, pyridine, diethylamine, and the like, but are not limited thereto.

  The mixing ratio of the charge transport material to the binder resin is preferably 10 to 500 parts by mass, more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the binder resin.

  The thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 5 to 40 μm, and more preferably 10 to 30 μm.

  An antioxidant, an electronic conductive agent, a stabilizer and the like may be added to the charge transport layer. For the antioxidant, those described in Japanese Patent Application No. 11-200135 and for the electronic conductive agent are described in Japanese Patent Application Laid-Open Nos. 50-137543 and 58-76483.

  Next, an image forming apparatus according to the embodiment of the present invention will be described.

  An image forming apparatus 1 shown in FIG. 1 is a digital image forming apparatus, and includes an image reading unit A, an image processing unit B, an image forming unit C, and a transfer paper transport unit D as a transfer paper transport unit. Yes.

  An automatic document feeder that automatically conveys the document is provided above the image reading unit A. The document placed on the document table 11 is separated and conveyed by the document conveyance roller 12 to the reading position 13a. The image is read. The document after the document reading is completed is discharged onto the document discharge tray 14 by the document transport roller 12.

  On the other hand, the image of the original when placed on the platen glass 13 is read at a speed v of the first mirror unit 15 including the illumination lamp and the first mirror constituting the scanning optical system, and the V-shaped first image is located. Reading is performed by the movement of the second mirror unit 16 including the two mirrors and the third mirror in the same direction at the speed v / 2.

  The read image is formed on the light receiving surface of the image sensor CCD, which is a line sensor, through the projection lens 17. The line-shaped optical image formed on the image sensor CCD is sequentially photoelectrically converted into an electric signal (luminance signal) and then A / D converted, and the image processing unit B performs processing such as density conversion and filter processing. Then, the image data is temporarily stored in the memory.

  In the image forming unit C, as an image forming unit, a drum-shaped photoconductor 21 as an image carrier, a charging means (charging step) 22 for charging the photoconductor 21 on the outer periphery thereof, and a surface potential of the charged photoconductor. Potential detecting means 220 for detecting the toner, developing means (developing process) 23, transfer / conveying belt device 45 serving as a transferring means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and light discharging means (light discharging process). PCL (precharge lamps) 27 are arranged in the order of operation. Further, on the downstream side of the developing means 23, a reflection density detecting means 222 for measuring the reflection density of the patch image developed on the photosensitive member 21 is provided. As the photosensitive member 21, the organic photosensitive member according to the present invention is used, and the photosensitive member 21 is driven and rotated in the clockwise direction shown in the drawing.

  After the rotating photosensitive member 21 is uniformly charged by the charging unit 22, an image based on an image signal called from the memory of the image processing unit B by an exposure optical system as an image exposure unit (image exposure step) 30 is used. Exposure is performed. The exposure optical system as the image exposure means 30 as the writing means uses a laser diode (not shown) as a light source, and the optical path is bent by the reflection mirror 32 via the rotating polygon mirror 31, the fθ lens 34, and the cylindrical lens 35, and main scanning is performed. Therefore, image exposure is performed on the photoconductor 21 at the position Ao, and an electrostatic latent image is formed by rotation (sub-scanning) of the photoconductor 21. In one example of the present embodiment, the character portion is exposed to form an electrostatic latent image.

  In the image forming apparatus of the present invention, a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm is used as an image exposure light source when an electrostatic latent image is formed on a photoreceptor. By using these image exposure light sources, the exposure dot diameter in the writing principal direction is narrowed down to 10 to 50 μm, and digital exposure is performed on the organic photoreceptor, so that it is 600 dpi (dpi: the number of dots per 2.54 cm) or more. A high-resolution electrophotographic image of 2500 dpi can be obtained.

The exposure dot diameter refers to the length of the exposure beam along the main scanning direction (Ld: measured at the maximum length) 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 solid scanner such as the scanning optical system and LED using 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.

  The electrostatic latent image on the photoconductor 21 is reversely developed by the developing unit 23, and a visible toner image is formed on the surface of the photoconductor 21.

  In the transfer paper transport section D, paper feed units 41 (A), 41 (B), and 41 (C) are provided below the image forming unit as transfer paper storage means for storing transfer paper P of different sizes. Further, a manual paper feeding unit 42 for manually feeding paper is provided on the side, and the transfer paper P selected from any of them is fed along the transport path 40 by the guide roller 43 and fed. The transfer paper P is temporarily stopped by a pair of paper feed registration rollers 44 that correct the inclination and bias of the transfer paper P to be transferred, and then fed again. The transport path 40, the pre-transfer roller 43a, and the paper feed path 46 The toner image on the photosensitive member 21 is transferred onto the transfer paper P by the transfer pole 24, the separation pole 25, the nail separation means 250, and the like at the transfer position Bo. Separated from the body, After the transfer sheet P is placed conveyed to the transfer conveying belt 454 of the transfer conveyor belt device 45, it is conveyed to the fixing unit 50 by the transfer conveyor belt device 45.

  The fixing unit 50 includes a fixing roller 51 and a pressure roller 52. By passing the transfer paper P between the fixing roller 51 and the pressure roller 52, the toner is fixed by heating and pressing. After the toner image has been fixed, the transfer paper P is discharged onto the paper discharge tray 64.

  The above describes the state in which image formation is performed on one side of the transfer paper. However, in the case of double-sided copying, the paper discharge switching member 170 is switched, the transfer paper guide 177 is opened, and the transfer paper P is indicated by a broken arrow. Conveyed in the direction.

  Further, the transfer paper P is transported downward by the transport mechanism 178 and switched back by the transfer paper reversing unit 179, and the rear end portion of the transfer paper P becomes the leading end portion and transported into the duplex copying paper supply unit 130. The

  The transfer paper P is moved in a paper feed direction by a conveyance guide 131 provided in the double-sided copy paper supply unit 130, the transfer paper P is re-fed by the paper supply roller 132, and the transfer paper P is guided to the conveyance path 40. .

  Again, as described above, the transfer paper P is conveyed in the direction of the photosensitive member 21, the toner image is transferred to the back surface of the transfer paper P, fixed by the fixing unit 50, and then discharged onto the paper discharge tray 64.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge, and this unit is configured to be detachable from the apparatus main body. Also good. In addition, a process cartridge is formed by integrally supporting at least one of a charger, an image exposure device, a developing device, a transfer or separation device, and a cleaning device together with a photosensitive member, and a single unit that is detachable from the apparatus main body. It is good also as a structure which can be attached or detached using guide means, such as a rail of an apparatus main body.

  FIG. 2 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

  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 means 3Y, the exposure means 3Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge (image forming unit), and this image forming unit is connected to the apparatus main body. It may be configured to be detachable. 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. A transfer material P as a transfer material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and a plurality of intermediates. After passing through rollers 22A, 22B, 22C, 22D and registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to transfer a color image all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between 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 a transfer material is collectively referred to as a transfer medium.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  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 transfer material P passes through the secondary transfer roller 5b.

  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.

  Next, FIG. 3 shows a color image forming apparatus according to another embodiment of the present invention (a copy having at least a charging means, an exposure means, a plurality of developing means, a transfer means, a cleaning means and an intermediate transfer member around the organic photoreceptor). FIG. The belt-shaped intermediate transfer body 70 uses an elastic body having a medium resistance.

  Reference numeral 1 denotes a rotary drum type photoconductor that is repeatedly used as an image forming body, and is rotationally driven in a counterclockwise direction indicated by an arrow at a predetermined peripheral speed.

  In the rotation process, the photoreceptor 1 is uniformly charged to a predetermined polarity and potential by a charging means (charging process) 2, and then time-series electric digital of image information by an image exposure means (image exposure process) 3 (not shown). An electrostatic latent image corresponding to the yellow (Y) color component image (color information) of the target color image is formed by receiving image exposure by scanning exposure light or the like by a laser beam modulated in accordance with the pixel signal. The

  Then, the electrostatic latent image is developed with yellow toner as the first color by yellow (Y) developing means: developing step (yellow color developing device) 4Y. At this time, the second to fourth developing means (magenta developer, cyan developer, black developer) 4M, 4C, and 4Bk are turned off and do not act on the photosensitive member 1. The first color yellow toner image is not affected by the second to fourth developing units.

  The intermediate transfer member 70 is stretched by rollers 79a, 79b, 79c, 79d, and 79e, and is driven to rotate in the clockwise direction at the same peripheral speed as the photosensitive member 1.

  The first color yellow toner image formed and supported on the photosensitive member 1 is applied to the intermediate transfer member 70 from the primary transfer roller 5a in the process of passing through the nip portion between the photosensitive member 1 and the intermediate transfer member 70. The intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer body 70 by the electric field formed by the primary transfer bias.

  The surface of the photoreceptor 1 after the transfer of the first color yellow toner image corresponding to the intermediate transfer body 70 is cleaned by the cleaning device 6a.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black (black) toner image are sequentially superimposed and transferred onto the intermediate transfer body 70 to correspond to the target color image. A superimposed color toner image is formed.

  The secondary transfer roller 5b is supported in parallel with the secondary transfer counter roller 79b so as to be separated from the lower surface of the intermediate transfer body 70.

  A primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive member 1 to the intermediate transfer member 70 is opposite in polarity to the toner and is applied from a bias power source. The applied voltage is, for example, in the range of +100 V to +2 kV.

  In the primary transfer process of the first to third color toner images from the photosensitive member 1 to the intermediate transfer member 70, the secondary transfer roller 5b and the intermediate transfer member cleaning means 6b can be separated from the intermediate transfer member 70. is there.

  When the superimposed color toner image transferred onto the belt-shaped intermediate transfer member 70 is transferred to the transfer material P, which is the second image carrier, the secondary transfer roller 5b is brought into contact with the belt of the intermediate transfer member 70. At the same time, the transfer material P is fed from the pair of paper registration rollers 23 through the transfer paper guide to the belt of the intermediate transfer body 70 to the contact nip with the secondary transfer roller 5b at a predetermined timing. A secondary transfer bias is applied to the secondary transfer roller 5b from a bias power source. By this secondary transfer bias, the superimposed color toner image is transferred (secondary transfer) from the intermediate transfer body 70 to the transfer material P as the second image carrier. The transfer material P that has received the transfer of the toner image is introduced into the fixing means 24 and heated and fixed.

  The image forming apparatus of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers. The present invention can be widely applied to such devices.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. In the following text, “part” means “part by mass”.

Production of Photoreceptor 1 Photoreceptor 1 was produced as follows.

  The surface of the cylindrical aluminum support was cut to prepare a conductive support having a surface roughness Rz = 0.8 (μm).

<Intermediate layer>
An intermediate layer coating solution having the following composition was prepared.
Polyamide resin X1010 (manufactured by Daicel Degussa Co., Ltd.) 1 part 20-titanium titanium SMT500SAS (manufactured by Teika) 1.1 parts ethanol 20 parts Dispersion was carried out for 10 hours in a batch manner using a sand mill as a disperser.

  It apply | coated by the dip coating method so that it might become a film thickness of 2 micrometers after drying for 20 minutes at 110 degreeC on the said support body using the said coating liquid.

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

<Charge transport layer>
Charge transport material: CTM (compound A below) 150 parts Binder: Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical) 300 parts Antioxidant (Irganox 1010: manufactured by Ciba Japan) 6 parts Toluene / tetrahydrofuran = 1/9% by volume 2000 Part silicone oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part was mixed and dissolved to prepare a charge transport layer coating solution. The coating liquid was dried on the charge generation layer by dip coating at 110 ° C. for 60 minutes to form a charge transport layer having a thickness of 20 μm.

<Protective layer>
Metal oxide particles (number average primary particle size 20 nm tin oxide surface-treated with S-13 of the same mass) 100 parts Compound having 7 or more functional functional groups (polymerizable compound A): tripentaerythritol octa Methacrylate 20 parts Compound having a polymerizable functional group having a viscosity of 30 to 3000 mPa · s at 25 ° C. (polymerizable compound B): Trimethylolpropane trimethacrylate (viscosity: 44 mPa · s) 80 parts Isopropyl alcohol 500 parts After dispersing for 10 hours using a sand mill,
30 parts of a polymerization initiator 1-6 was added, mixed and stirred under light shielding to dissolve, and a protective layer coating solution was prepared (light shielding during storage). A protective layer was applied using a circular slide hopper applicator on the photoreceptor on which the coating solution had been prepared up to the charge transport layer. After coating, after drying for 20 minutes at room temperature (solvent drying process), a metal halide lamp (500 W) is used for irradiation for 1 minute while rotating the photoreceptor at a position of 100 mm (ultraviolet curing process), and a protective layer having a thickness of 3 μm. Got.

Production of photoconductors 2 to 12 Photoconductors 2 to 12 were produced in the same manner except that the materials used for the protective layer of the photoconductor 1 were changed as shown in the list of Table 1.

Production of Photoreceptor 13 Photoreceptor 13 was produced in the same manner as in production of photoreceptor 1, except that the metal oxide particles were removed from the protective layer.
Photoconductor 14 (comparative example)
Photoconductor 1 was prepared in the same manner except that trimethylolpropane trimethacrylate (viscosity: 44 mPa · s) (M-7) was changed to ethylene glycol methacrylate (viscosity: 6 mPa · s) (M-12). 14 was produced.
Photoconductor 15 (comparative example)
In the production of the photoreceptor 1, except that: the addition amount of tripentaerythritol octamethacrylate (M-1) was changed to 100 parts, and: trimethylolpropane trimethacrylate (viscosity: 44 mPa · s) (M-7) was removed. In the same manner, a photoreceptor 15 was produced.
Photoconductor 16 (comparative example)
Photoreceptor 16 was produced in the same manner as in the production of photoreceptor 10, except that tetrapentaerythritol dodecamethacrylate (M-5) was excluded and the addition amount of trimethylolpropane triacrylate (M-8) was changed to 100 parts. .
Photoconductor 17 (comparative example)
Photoconductor 17 was prepared in the same manner as in preparation of photoconductor 2, except that tripentaerythritol heptamethacrylate (M-2) was changed to dipentaerythritol pentamethacrylate (M-13).

In Table 1,
M-1: Tripentaerythritol octamethacrylate M-2: Tripentaerythritol heptamethacrylate M-3: Tripentaerythritol octaacrylate M-4: Tetrapentaerythritol decamethacrylate:
M-5: Tetrapentaerythritol dodecamethacrylate M-7: Trimethylolpropane trimethacrylate M-8: Trimethylolpropane triacrylate M-9: Pentaerythritol tetraacrylate M-10: Ethoxylated bisphenol A dimethacrylate M-11: Tri Cyclodecane dimethanol diacrylate M-12: Ethylene glycol dimethacrylate M-13: Dipentaerythritol pentamethacrylate [Evaluation]
The photoreceptors 1 to 17 obtained as described above are basically a commercially available full-color multifunction machine bizhub PRO C6500 (manufactured by Konica Minolta Business Technologies, Inc .; 600 dpi, 780 nm semiconductor laser exposure light having the configuration shown in FIG. Was used). Since the full-color multifunction peripheral has four image forming units, the photosensitive members of each image forming unit are the same type of photosensitive member (for example, in the case of the photosensitive member 1, four photosensitive members 1 are provided. Prepared) and unified and evaluated. Each evaluation was performed under the conditions of 30 ° C. and 80% RH, and an A4 image with a YMCBk color printing ratio of 2.5% was printed on a neutral A4 sheet and subjected to a printing durability test. The environmental conditions were evaluated.

(Image blur)
Immediately after the printing endurance test for 500,000 sheets under environmental conditions of 30 ° C. and 80% RH, the main power supply of the actual machine was stopped. Immediately after the stop, the power was turned on and the image was ready for printing. Immediately after that, a halftone image (relative reflection density of 0.4 with a Macbeth densitometer) and a 6-dot lattice image of the entire A3 were printed on the entire A3 neutral paper. The state of the printed image was observed and the following evaluation was performed.

◎: No blurring in halftone and grid images (good)
○: A thin strip-like density decrease in the longitudinal direction of the photoreceptor is observed only in the halftone image (no problem in practical use)
X: Lattice image loss or line width narrowing due to image blurring (practical problem).

(Scratch resistance)
After the printing durability test, a halftone image was printed on the entire surface of A3 paper, and the following evaluation was performed.

A: There is no noticeable scratch on the surface of the photoconductor, and no image defect corresponding to the photoconductor is found in the halftone image (good).
○: The surface of the photoconductor is slightly scratched visually, but no image defect corresponding to the photoconductor is found in the halftone image (no problem in practical use).
X: The surface of the photoconductor is clearly scratched and an image defect corresponding to the scratch is observed in the halftone image (practically problematic).
(Amount of photoconductor wear)
Evaluation was made based on the difference in film thickness before and after the printing and printing durability test for 500,000 sheets under the 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)
(Crack resistance)
After the printing durability test, a halftone image was printed on the entire surface of A3 paper, and the following evaluation was performed.

A: No cracks are visually observed at the interface between the photosensitive layer and the protective layer, and no image defects corresponding to the cracks are found in the halftone image (good).
○: Minor cracks are visually observed at the interface between the photosensitive layer and the protective layer, but no image defects corresponding to the cracks are found in the halftone image (no problem in practical use).
×: Visually observed cracks at the interface between the photosensitive layer and the protective layer, and the occurrence of image defects corresponding to the cracks was also observed in halftone images (problems in practice)

  As is apparent from Table 2, the photoreceptors 1 to 13 in the invention of the present application have obtained practical results or more in each evaluation item. However, the protective layer of the photoreceptor is a photoreceptor 14 outside the present invention. In -17, there is a problem in practicality in any of the evaluation items.

10Y, 10M, 10C, 10Bk Image forming unit 1Y, 1M, 1C, 1Bk Photoconductor 2Y, 2M, 2C, 2Bk Charging unit 3Y, 3M, 3C, 3Bk Exposure unit 4Y, 4M, 4C, 4Bk Developing unit

Claims (8)

  Polymerization in which a photosensitive layer and a protective layer are laminated on a conductive support, and the protective layer has a compound having a polymerizable functional group having 7 or more functional groups and a viscosity at 25 ° C. of 30 to 3000 mPa · s. An organic photoreceptor, which is a protective layer formed by polymerizing a composition containing a compound having a functional functional group.   2. The organophotoreceptor according to claim 1, wherein the compound having a polymerizable functional group having 7 or more functional groups is tripentaerythritol or polyfunctional acrylate or methacrylate of tetrapentaerythritol.   The organophotoreceptor according to claim 1 or 2, wherein the compound having a polymerizable functional group having a viscosity at 25 ° C of 30 to 3000 mPa · s is a bifunctional to tetrafunctional polyfunctional acrylate or methacrylate. .   The organophotoreceptor according to claim 1, wherein the protective layer contains at least metal oxide fine particles.   The organophotoreceptor according to claim 1, wherein the metal oxide fine particles are alumina fine particles or tin oxide fine particles that have been surface-treated with a reactive compound having a surface treatment group.   6. The organophotoreceptor according to claim 5, wherein the reactive compound having a surface treatment group is a compound containing either an acryloyloxy group or a methacryloyloxy group.   Organic photoreceptor, charging means for charging the organic photoreceptor, exposure means for forming an electrostatic latent image on the organic photoreceptor by image exposure, developing means for developing the electrostatic latent image into a toner image, the toner In an image forming apparatus having a transfer means for transferring an image to a transfer medium and a cleaning means for removing toner remaining on the organic photoreceptor after the transfer, the organic photoreceptor has a photosensitive layer and a protective layer laminated on a conductive support. And a protective layer containing a compound having a polymerizable functional group having 7 or more functional groups and a compound having a polymerizable functional group having a viscosity at 25 ° C. of 30 to 3000 mPa · s. An image forming apparatus comprising a protective layer formed by polymerizing a product.   A process cartridge for use in the image forming apparatus according to claim 7 comprises at least one of the organic photosensitive member according to any one of claims 1 to 6 and at least one of a charging unit, an image exposing unit, and a developing unit. And a process cartridge configured to be removable from and into the image forming apparatus.

Images