JP2009086413A - Electrophotographic photoreceptor, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which can prevent rising of residual potential and the occurrence of image fuzziness by satisfying both of improving conflicting characteristics such as rising of residual potential and the image fuzziness occurring on a particle-containing protective layer, and has the protective layer excellent in wear-resistant characteristic without causing a crack or the like, and to provide a process cartridge and an image forming apparatus using the electrophotographic photoreceptor. <P>SOLUTION: In the electrophotographic photoreceptor having a photoreceptor layer and the protective layer on a conductive base, the protective layer comprises a resin and inorganic particles which satisfy the relation (1). ε<SB>1</SB>in the relation (1) denotes a dielectric constant of the resin, ε<SB>2</SB>denotes a dielectric constant of the inorganic particle and [C] denotes a volume fraction of the inorganic particle in the whole protective layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member used for a copying machine, a printer, and the like, and a process cartridge and an image forming apparatus using the electrophotographic photosensitive member.

In recent years, with the demand for wear resistance of photoreceptors, the life has been extended by putting particles in the protective layer, but in order to further satisfy the wear resistance, a cross-linked resin is used as the coating resin for the protective layer. Attempts have been made to use it. (Patent Document 1)
Certainly, the application of a curable material improves the durability against abrasion and scratches, and a long life of the photoreceptor is achieved in terms of film strength, but a curable material, particularly a radical polymerizable material, is used as a component of the protective layer. In this case, an image blur problem that the printed image becomes unclear in a high temperature and high humidity environment occurs. Image blur tends to deteriorate mainly in proportion to the amount of residual unreacted sites in the radical polymerizable material, so it is effective to improve the reaction rate, but it is an electrical insulating film by itself, and the residual potential increases significantly. Will cause.

  Therefore, until now, the organic photoconductive transport material has been added to the protective layer, or the organic photoconductive transport material to which the radical polymerizable functional group has been added is incorporated into the reaction film to maintain the potential stability of the photoreceptor. Attempts have been made, but in reality the deterioration of the organic photoconductive transport material due to heat or light irradiation during reaction curing is unavoidable, and the potential stability has been lacking.

An attempt to adjust the resistance of the film by incorporating conductive metal oxide particles is also disclosed. However, since it is a conductive metal oxide, it is inevitable that the resistance depends on the environment. To satisfy the stability and potential stability. (Patent Document 2)
JP 2001-125299 A JP 2006-106483 A

  The object of the present invention is to solve the problem in the protective layer. In other words, the improvement of the contradictory characteristics such as the increase of the residual potential generated in the particle-containing protective layer and the image blur are achieved, and the increase of the residual potential and the generation of image blur are improved, and the wear resistance characteristics in which cracks do not occur. It is to provide an electrophotographic photosensitive member having an excellent protective layer, and to provide a process cartridge and an image forming apparatus using the electrophotographic photosensitive member.

The above object of the present invention can be achieved by the following configuration.
1. An electrophotographic photosensitive member having a photosensitive layer and a protective layer on a conductive substrate, wherein the protective layer contains a resin satisfying the relationship of the following formula (1) and inorganic particles.

(In formula (1), ε ₁ represents the relative dielectric constant of the resin, ε ₂ represents the relative dielectric constant of the inorganic particles, and [C] represents the volume fraction of the inorganic particles in the entire protective layer.)
2. 2. The electrophotographic photosensitive member according to 1, wherein the formula 1 is 1.00 or more and 2.50 or less.
3. 3. The electrophotographic photosensitive member according to 1 or 2 above, wherein the resin of the protective layer forms a cured resin film obtained by reaction curing of a compound having a curable functional group.
4). 4. The electrophotographic photosensitive member according to any one of items 1 to 3, wherein the inorganic particles contained in the protective layer are titanium oxide.
5). Electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, latent image forming means for forming an electrostatic latent image, developing means for developing an electrostatic latent image on the electrophotographic, and the electrophotographic photosensitive member In a process cartridge used in an image forming apparatus having transfer means for transferring a toner image visualized thereon onto a transfer material and cleaning means for removing residual toner on the electrophotographic photosensitive member after transfer, The electrophotographic photosensitive member according to any one of 1 to 4 and at least one of a charging unit, a latent image forming unit, a developing unit, a transfer unit, a charge eliminating unit, and a cleaning unit are integrally supported to form an image. A process cartridge which can be detachably attached to an apparatus main body.
6). Electrophotographic photosensitive member, charging means for charging the electrophotographic, latent image forming means for forming an electrostatic latent image, developing means for developing an electrostatic latent image on the electrophotographic photosensitive member, and the electrophotographic photosensitive member An image forming apparatus comprising: a transfer unit that transfers a toner image visualized thereon onto a transfer material; and a cleaning unit that removes residual toner on the electrophotographic photosensitive member after transfer. An image forming apparatus using the electrophotographic photosensitive member according to claim 1.

  According to the present invention, it is possible to provide an electrophotographic photosensitive member that has sufficient wear resistance and suppresses a residual potential increase and image blur due to repeated use.

  Hereinafter, the present invention will be described in detail.

  The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a photosensitive layer and a protective layer on a conductive substrate, wherein the protective layer contains a resin satisfying the relationship of Formula 1 and inorganic particles. To do.

  The above equation 1 is derived from the document “Electromagnetics 1 of Landau-Lissitz Theoretical Physics Course (Tokyo Book), p61”, and is an equation related to the calculation of the dielectric constant of mixtures having different dielectric constants.

As described above, the present inventors added conductive metal oxide particles to increase the resistance of the protective layer to 10 ¹⁰ to 10 ¹⁵ Ω · cm against residual power rise and image blur. Although measures such as control and addition of a charge transport agent to the protective layer have been carried out, it has not been possible to obtain results that are sufficiently satisfactory for the intended problem.

  In addition, for this problem, the present inventors have selected, for example, the type of filler, its surface treatment, particle size, addition amount, by selecting light, heat, discharge products, and materials that improve moisture resistance for the protective layer. In addition, although it was thought that it could be achieved by selection including the type of charge transport agent and the combined use of an antioxidant, conventionally required methods could not obtain the required characteristics.

  As a result of further intensive studies, the present inventors have found that it is important to control the dielectric constant of the protective layer, and have reached the present invention. That is, it was found that it is important to control the dielectric constant of the resin used for the protective layer, the dielectric constant of the filler, and the volume concentration of the filler in the entire protective layer.

  The reason for this is that by blending a certain proportion of inorganic particles having a high dielectric constant into the protective layer, the dielectric constant of the entire protective layer is increased and the dielectric relaxation phenomenon is easily caused, thereby suppressing a residual potential increase, It is assumed that the potential stability has improved.

  Further, since the protective layer having a high dielectric constant has high resistance, it is considered that the problem of resistance reduction of the protective layer is sufficiently satisfied.

  In the protective layer according to the present invention, the formula 1 is 0.40 or more and 2.50 or less, but preferably 1.00 or more and 2.50 or less. If Equation 1 is less than 0.40, the dielectric constant of the protective layer is small and the dielectric relaxation phenomenon is not sufficient, so that the residual potential is likely to increase. On the other hand, if it is larger than 2.50, the content of the inorganic particles in the protective layer tends to increase, the film physical properties of the protective layer become brittle, cracks tend to occur, and image flow tends to occur.

  The inorganic particles to be contained in the protective layer in the present invention are preferably particles such as silica, alumina, titanium oxide, barium titanate, zinc oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, zirconium oxide, and more preferably high. Dielectric constant titanium oxide and barium titanate are preferable, and titanium oxide is more preferable. You may use these 1 type or in mixture of 2 or more types. When two or more types are mixed, they may take the form of a solid solution or fusion. The average particle size of such inorganic particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

  Various additives can be added for the purpose of improving the dispersibility and smoothness of the inorganic particles. In particular, for improving dispersibility, it is very effective to perform surface treatment of metal oxide particles. Examples of the surface treatment agent include various inorganic treatments, treatments with silicon compounds, fluorine-containing silane coupling agents, fluorine-modified silicone oils, fluorine-based surfactants, fluorine-based graft polymers, and the like.

  On the other hand, as the resin of the protective layer according to the present invention, a high molecular weight polycarbonate resin, light, heat curable resin, silicone-based hard coat resin, etc. may be used, and in particular, a photocurable acrylic compound is cured. Resins are preferred.

  In addition, resins using various reactive oligomers can also be used. For example, a resin formed from an epoxy acrylate oligomer, a urethane acrylate oligomer, a polyester acrylate oligomer, an unsaturated polyester resin, or the like can be used.

  In addition, other resins such as polyester, polycarbonate, polyurethane, acrylic resin, epoxy resin, silicone resin, alkyd resin, and vinyl chloride-vinyl acetate copolymer can be mixed and used.

  The resin of the protective layer according to the present invention preferably forms a cured resin film obtained by reaction curing of a compound having a curable functional group. Here, the resin cured film is a film formed by reaction curing, and the film is more preferably a three-dimensionally crosslinked cured film. The cured resin film is preferably a film produced by a photopolymerization reaction.

    Examples of the compound having a curable functional group include an acrylic compound that generates the following radical polymerization reaction.

  In addition, R and R 'of the above exemplary compounds represent the following groups.

  The above exemplary compounds can be obtained from Toagosei Co., Ltd., Nippon Kayaku Co., Ltd., Daicel Cytec Co., Ltd., Shin-Nakamura Chemical Co., Ltd. and the like.

  When curing the acrylic compound, a radical polymerization initiator is used. The addition amount of the initiator is preferably 0.1 to 20%, more preferably 0.5 to 10% with respect to the total mass of the acrylic monomer. As the initiator, either a photopolymerization initiator or a thermal polymerization initiator can be used.

  Further, both light and heat initiators can be used in combination.

  In the photopolymerization of an acrylic compound, a protective layer coating solution (a coating solution containing the acrylic compound) is applied on the photosensitive layer, and then primary dried to the extent that the coating film loses fluidity, and then irradiated with ultraviolet rays. It is preferable to cure the protective layer by irradiation.

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

  In the protective layer used in the present invention, various lubricant particles can be added for the purpose of improving smoothness. 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 fluorine atom-containing resin particles in the protective layer is preferably 5 to 70% by mass, more preferably 10 to 60% by mass. The molecular weight of the resin and the particle size of the particles can be appropriately selected and are not particularly limited.

  In the present invention, an additive such as an antioxidant may be added to the protective layer for the purpose of improving the weather resistance.

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

  Next, the photosensitive layer will be described. The structure of the photosensitive layer of the electrophotographic photosensitive member according to the present invention includes a single layer type containing both a charge generating substance and a charge transporting substance in the same layer, or a charge generating layer containing a charge generating substance and a charge transporting substance. And a charge transport layer to be laminated on a conductive support. An undercoat layer having a barrier function and an adhesive function may be provided between the conductive layer and the photosensitive layer. The object of the present invention is achieved by providing the protective layer of the present invention on the photosensitive layer. As a method for applying these intermediate layer, photosensitive layer and protective layer, dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, slide hopper method and the like can be used.

  The laminated type photoreceptor will be described below.

As the structure of the photosensitive layer of the laminated type photoreceptor, there are a structure in which a charge generation layer and a charge transport layer are laminated in this order on a conductive support, and a structure in which a charge transport layer and a charge generation layer are laminated in this order. .
(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 undercoat layer having a barrier function and an adhesive function may be provided between the conductive layer and the photosensitive layer. The undercoat layer can be formed of casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, gelatin and the like. Of these, an alcohol-soluble polyamide is preferable.

  The thickness of the undercoat layer is preferably 0.1 to 15 μm.

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, they 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.
(Charge generation layer)
The charge generation layer is composed of azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as bilenquinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and charge generation materials such as phthalocyanine pigments. It can be used in a form dispersed in the resin. As the binder resin, a formal resin, a butyral resin, a silicone resin, a silicone-modified butyral resin, a phenoxy resin, polystyrene, polyvinyl acetate, an acrylic resin, and the like are desirable. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. The film thickness of such a resin-dispersed charge generation layer is preferably 5 μm or less, 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 is formed by coating and drying mainly a charge transport material and a paint obtained by dissolving the binder resin used in the present invention in a solvent. Examples of the charge transport material used include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, and thiazole compounds.

  These are combined with 0.5 to 2 times the amount of binder resin, applied and dried to form a charge transport layer. Examples of the binder resin include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin and And a copolymer resin containing two or more of the repeating unit structures of these resins. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used.

  The charge transport layer preferably contains an antioxidant. Typical examples of the antioxidants are those that prevent the action of oxygen under conditions of light, heat, discharge, etc. on auto-oxidizing substances present in the organic photoreceptor or on the surface of the organic photoreceptor, It is a substance that has the property of inhibiting.

The film thickness of the charge transport layer is preferably 5 to 40 μm, more preferably 15 to 30 μm.
(Protective layer)
The protective layer described above is used for the protective layer according to the present invention.

  Next, an image forming apparatus using the electrophotographic photosensitive member 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 as a transferring means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and light neutralizing means (light slow charge). PCL (precharge lamp) 27 as a process is 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, it is preferable to use a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 800 nm 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 direction is narrowed down to 10 to 100 μm, and digital exposure is performed on the organic photoreceptor, so that it is 400 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 (Ld: measured at the maximum position) along the main scanning direction 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 image forming method of the present invention, it is preferable to use a polymerized toner as a developer used in the developing means. By using a polymer toner having a uniform shape and particle size distribution in combination with the organic photoreceptor according to the present invention, an electrophotographic image with better sharpness can be obtained.

  The electrostatic latent image formed on the organic photoreceptor of the present invention is visualized as a toner image by development. The toner used for development may be a pulverized toner or a polymerized toner, but the toner according to the present invention is preferably a polymerized toner that can be prepared by a polymerization method from the viewpoint of obtaining a stable particle size distribution.

  The term “polymerized toner” means a toner in which a toner binder resin is formed and the toner shape is formed by polymerization of a raw material monomer of the binder resin and, if necessary, subsequent chemical treatment. More specifically, it means a toner formed through a polymerization reaction such as suspension polymerization or emulsion polymerization, and if necessary, a step of fusing particles between them.

  The volume average particle diameter of the toner, that is, the 50% volume particle diameter (Dv50) is preferably 2 to 9 μm, more preferably 3 to 7 μm. By setting this range, the resolution can be increased. In addition, by combining with the above range, the amount of toner having a fine particle diameter can be reduced while being a small particle diameter toner, the dot image reproducibility is improved over a long period of time, and the sharpness is excellent. In addition, a stable image can be formed.

  The toner according to the present invention may be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. be able to.

  Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 80 μm.

  The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.

  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 to the transfer paper P while being transferred to the transfer conveyance belt 454 of the transfer conveyance belt device 45 by the transfer electrode 24 and the separation electrode 25 at the transfer position Bo. Is, transfer sheet P is separated from the photosensitive member 21 surface, 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 is 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 constructed by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge (also referred to as an image forming unit), and this unit is attached to the apparatus main body. It may be configured to be detachable. 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 5Y, 5M, 5C and 5Bk 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 5Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning means 5Y or the cleaning blade 5Y) 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 5Y 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 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 using the organic photoreceptor of the present invention (a copying machine having at least a charging means, an exposure means, a plurality of developing means, a transfer means, a cleaning means, and an intermediate transfer body around the organic photoreceptor. 1 is a cross-sectional view of a configuration of a laser beam printer). 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 yellow toner image of the first color 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 photosensitive member 1 after the transfer of the first color yellow toner image corresponding to the intermediate transfer member 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.

  The 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 has a polarity opposite to that of 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. .

  When the superimposed color toner image transferred onto the belt-shaped intermediate transfer member 70 is transferred onto 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 sheet 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 fixed by heating.

  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, and further displays, recordings, light printing, plate making and facsimiles using electrophotographic technology. The present invention can be widely applied to such devices.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples. In addition, "part" in a sentence represents a mass part.
Example 1
(Preparation 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 ten-point surface roughness Rz = 1.5 (μm). The Rz conforms to the definition described in JIS B0601-1982 (including the reference length and evaluation length).
(Middle layer)
A dispersion having the following composition was diluted twice with the same mixed solvent, allowed to stand overnight, and then filtered (filter; rigesh mesh 5 μm filter manufactured by Nippon Pole Co., Ltd.) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 10 parts Titanium oxide SMT500SAS (manufactured by Teika) 30 parts Methanol 100 parts Dispersion was carried out for 10 hours in a batch manner using a sand mill as a disperser.

It apply | coated by the dip coating method so that it might become a dry film thickness of 2 micrometers on the said support body using the said coating liquid.
(Charge generation layer)
Charge generation material: titanyl phthalocyanine pigment (a titanyl phthalocyanine pigment having a maximum diffraction peak at a Bragg angle of 2θ = 27.3 ° as measured by Cu-Kα characteristic X-ray diffraction spectrum) 2 parts Polyvinyl butyral resin (BH-S: 1 part t-butyl acetate 70 parts 4-methoxy-4-methyl-2-pentanone 30 parts were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm.
(Charge transport layer)
Charge transport material (4,4′-dimethyl-4 ″-(β-phenylstyryl)
Triphenylamine) 2 parts Binder: Polycarbonate (Z300: manufactured by Mitsubishi Engineering Co., Ltd.) 3 parts Antioxidant (Irganox 1010: manufactured by Ciba Geigy Japan, Inc.) 0.1 part Dichloromethane 20 parts are mixed and dissolved to form a charge transport layer coating solution. Prepared. A charge transport layer having a dry film thickness of 20 μm was formed on the charge generation layer using the circular slide hopper coater.
(Protective layer)
Preparation of protective layer coating solution 1.5 parts of anatase-type titanium oxide (average particle size 6 nm, 5% primary surface treatment with alumina and 30% secondary surface treatment with isobutyltrimethoxysilane) in tetrahydrofuran / toluene (volume 8/2) After adding to 5 parts of the solution and dispersing with a US homogenizer, 1.5 parts of polycarbonate resin “Z300” was dissolved to prepare a protective layer coating solution. This coating solution was applied onto the charge transport layer by a circular slide hopper coating method, followed by heat drying at 120 ° C. for 60 minutes to form a protective layer having a dry film thickness of 3.0 μm.

Example 2
Similarly to Example 1, the charge transport layer was similarly applied, and the protective layer was formed as follows. After adding 0.45 part of barium titanate (SG-BT30: manufactured by Kyoritsu Material Co., Ltd.) to 5 parts of 2-propanol and dispersing with a US homogenizer, the compound “Exemplary Compound No (9) having a curable functional group” 1.5 parts were dissolved. 0.075 parts of a polymerization initiator (Irgacure 184: manufactured by Ciba Geigy Japan, Inc.) was added thereto to prepare a protective layer coating solution. This protective layer coating solution is applied by a circular slide hopper coating method, and using a mercury lamp irradiation device ECS-401GX (manufactured by Eye Graphics), an ultraviolet integrated illuminance meter UVPF-A1 (PD-365) (eye graphics) Manufactured), the film was irradiated with an equivalent amount of light of 25 J / cm ² and then thermally dried at 120 ° C. for 60 minutes to form a protective layer having a dry film thickness of 3.0 μm.

Example 3
A barium titanate of Example 2 was prepared in the same manner except that 1.8 parts of rutile titanium oxide (SMT500SAS: manufactured by Teica) was used.

Example 4
Except that “Exemplary Compound No. (9)” of Example 2 was changed to “Exemplary Compound No. (16)” and barium titanate was changed to 1.35 parts of titanium oxide used in Example 1, it was similarly prepared.

Example 5
0.4 part of tetrafluoroethylene resin (Lublon L-2: manufactured by Daikin, specific gravity 2.0 g / cm ³ ) and 0.84 part of titanium oxide used in Example 1 were added to 5 parts of 2-propanol, After dispersing with a US homogenizer, 1.0 part of the compound “Exemplary Compound No. (16)” having a curable functional group was dissolved. To this was added 0.05 part of a polymerization initiator (Irgacure 184: manufactured by Ciba Geigy Japan), a protective layer coating solution was prepared, and coated and cured in the same manner as in Example 2 to form a protective layer having a dry film thickness of 3.0 μm.

Comparative Example 1
Except that “Exemplary Compound No. (9)” in Example 2 was changed to “Exemplary Compound No. (20)” and Barium Titanate was changed to 1.5 parts of alumina (Sumicorundum AA-03, manufactured by Sumitomo Chemical Co., Ltd.). Created in.
Comparative Example 2
“Exemplary compound No (9)” of Example 2 was prepared in the same manner except that “Exemplary compound No (7)” was changed to 0.3 part of barium titanate.
Comparative Example 3
It was created in the same manner except that “Exemplary Compound No. (9)” in Example 3 was changed to “Exemplary Compound No. (16)” and 2.7 parts of rutile titanium oxide.

[Measurement of relative permittivity]
The inorganic particle powder used in Examples 1 to 5 and Comparative Examples 1 to 3 is molded at a pressure of 1 t / cm ² to form a green molded body, fired at 1500 ° C., and electrodes are formed on both sides of the sintered body. This was supplied to a dielectric constant measuring apparatus (trade name “RF Impedance / Material Analyzer E4991A” manufactured by AGILENT), and the relative dielectric constant at 23 ° C. and 1 MHz was measured.

Similarly, for the resins or compounds having a curable functional group used in Examples 1 to 5 and Comparative Examples 1 to 3, electrodes were formed on both surfaces of the resin or reaction-cured cured film, and the relative dielectric constant was measured. In this case, measurement is performed without including inorganic particles. When the reaction is cured, an integrated light amount of 25 J / in is obtained with an ultraviolet integrated illuminance meter UVPF-A1 (PD-365) (made by Eye Graphics) using a mercury lamp irradiation device ECS-401GX (made by Eye Graphics). Irradiation equivalent to cm ² was performed.

  Table 1 summarizes the compositions of the protective layers of the photoreceptors obtained in the above Examples and Comparative Examples.

  The volume fraction of the inorganic particles in Table 1 was calculated from the volume part (mass part / specific gravity) of the inorganic particles in the protective layer and the volume part (mass part / specific gravity) of the resin.

Volume fraction of inorganic particles = volume part of inorganic particles / (volume part of inorganic particles + volume part of resin)
However, the volume part of the resin was a curable resin, and the volume part of the raw material compound was used.

Evaluation Each of the electrophotographic photoreceptors described above was mounted on a bizhub C250 (laser exposure / reverse development / intermediate transfer tandem color composite machine) manufactured by Konica Minolta Business Technologies, Inc., and evaluated according to the following evaluation items. The evaluation criteria are shown below. The obtained results are shown in Table 2.
(Evaluation of potential in actual machine)
In the environment of 23 ° C., 50% RH, the initial potential Vi after in-machine exposure and the potential after printing 30000 A4 continuous images of 5% full color each color were measured. If Vi is smaller than -200V, it is a practical range.
(Thickness loss)
The film thickness was measured after the photoconductive drum was photographed for 100,000 rotations in an environment of 23 ° C. and 50% RH. If it is 2.5 μm or less, it is practical.

Film thickness measurement method The film thickness of the photosensitive layer is measured at 10 points at random on the uniform film thickness part (excluding the film thickness fluctuation part at the front and rear end portions of the coating), and the average value is calculated. The film thickness of the photosensitive layer. The film thickness measuring device is an eddy current film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO), and the difference in the photosensitive layer thickness before and after the actual shooting test is defined as the film thickness depletion amount.
(Evaluation of image blur)
After printing 10000 sheets of A4 continuous 5% full color images at 30 ° C. and 85% RH, the machine body was turned off and left in the same environment for 12 hours. After 12 hours, the main body was turned on again to evaluate image blur (image flow).

◎: Image blur is not recognized at all. ○: Image blur is hardly observed. Δ: Image blur is partially generated and cannot be used. ×: Image blur is generated on the entire surface and cannot be used at all. Is a level.

  The obtained results are shown in Table 2.

    As is apparent from Table 2, when the electrophotographic photosensitive member of the present invention (Examples 1 to 5) having a protective layer satisfying the condition of Formula 1 is used, the potential stability and image blur after repeated use are reduced. Although the improvement can be achieved at the same time, the electrophotographic photosensitive member of the protective layer that does not satisfy the condition of the formula 1 (when the photosensitive member of Comparative Examples 1 to 3 is used) causes image blurring or cracks. Occurrence or potential stability deteriorates, and no improvement effect is observed.

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.

Explanation of symbols

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 (6)

An electrophotographic photosensitive member having a photosensitive layer and a protective layer on a conductive substrate, wherein the protective layer contains a resin satisfying the relationship of the following formula (1) and inorganic particles.

(In formula (1), ε ₁ represents the relative dielectric constant of the resin, ε ₂ represents the relative dielectric constant of the inorganic particles, and [C] represents the volume fraction of the inorganic particles in the entire protective layer.) The electrophotographic photosensitive member according to claim 1, wherein the formula 1 is 1.00 or more and 2.50 or less. The electrophotographic photosensitive member according to claim 1, wherein the resin of the protective layer forms a cured resin film obtained by reaction curing of a compound having a curable functional group. The electrophotographic photosensitive member according to claim 1, wherein the inorganic particles contained in the protective layer are titanium oxide. Electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, latent image forming means for forming an electrostatic latent image, developing means for developing an electrostatic latent image on the electrophotographic, and the electrophotographic photosensitive member In a process cartridge used in an image forming apparatus having transfer means for transferring a toner image visualized thereon onto a transfer material and cleaning means for removing residual toner on the electrophotographic photosensitive member after transfer. Item 5. The electrophotographic photosensitive member according to any one of Items 1 to 4, and at least one of a charging unit, a latent image forming unit, a developing unit, a transfer unit, a charge eliminating unit, and a cleaning unit are integrally supported to form an image. A process cartridge which can be detachably attached to a forming apparatus main body. Electrophotographic photosensitive member, charging means for charging the electrophotographic, latent image forming means for forming an electrostatic latent image, developing means for developing an electrostatic latent image on the electrophotographic photosensitive member, and the electrophotographic photosensitive member 5. The image forming apparatus according to claim 1, further comprising: a transfer unit that transfers the visualized toner image onto a transfer material; and a cleaning unit that removes toner remaining on the electrophotographic photosensitive member after transfer. An image forming apparatus using the electrophotographic photosensitive member according to any one of the above.

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