JP4561582B2 - Organic photoreceptor, process cartridge, image forming method and image forming apparatus - Google Patents

Description

  The present invention relates to an organic photoreceptor used for electrophotographic image formation, a process cartridge using the organic photoreceptor, an image forming method, and an image forming apparatus. More specifically, the present invention relates to electrophotography used in the fields of copying machines and printers. The present invention relates to an organic photoreceptor used for image formation of a system, a process cartridge using the organic photoreceptor, an image forming method, and an image forming apparatus.

  In recent years, there are increasing opportunities to use electrophotographic copying machines and printers in the fields of printing and color printing. In the fields of printing and color printing, there is a strong tendency to demand high-quality digital monochrome images or color images. In response to such demands, it has been proposed to reduce the exposure beam of the exposure light source and form a high-definition digital image (Patent Document 1). However, even if the exposure beam of the semiconductor laser or the like is narrowed down to form a dot latent image by fine dot exposure on the organic photoreceptor, the finally obtained electrophotographic image achieves sufficient high image quality. The current situation is that we have not obtained it.

  One of the causes is that even when a fine dot latent image is formed on an organic photoreceptor using semiconductor laser light or the like, the dot latent image cannot be accurately reproduced as a toner image. It is done. That is, the surface characteristics of the organophotoreceptor are poor in micro units, and the dot latent image formed by a semiconductor laser or the like is reproduced as a toner image smaller than the size of the latent image, or reproduced as a larger toner image. The toner image formed on the organic photoreceptor is not sufficiently transferred to a transfer medium (such as a transfer material such as paper or an intermediate transfer member). In addition, problems such as the occurrence of transfer omission (hereinafter simply referred to as omission) and a decrease in image density are likely to occur.

As a method for improving the surface characteristics of the organic photoreceptor, an organic photoreceptor in which fluororesin fine particles are contained on the surface of the organic photoreceptor has been proposed (Patent Document 2). Organic photoreceptors containing these fluororesin fine particles prevent toner filming and the like and have a characteristic that the surface is not easily contaminated. However, the fluororesin fine particles are dispersed in a binder resin in a micro size. The fluororesin fine particles and the binder resin are separated at a micro level, and as a result, image blur is likely to occur. Further, the surface layer of the fluorine-containing resin fine particles has insufficient wear resistance, and the surface layer is easily scratched. For this reason, there is a problem that the halftone image is easily scratched.
Japanese Patent Laid-Open No. 2001-255585 JP-A-8-328287

  The present invention has been made to solve the above problems, and an object of the present invention is to increase a dot latent image on an organic photoreceptor formed by an image exposure light source such as a semiconductor laser on the organic photoreceptor. It is to provide an organic photoreceptor that can be finely reproduced as a toner image and faithfully transfer the reproduced toner image to a transfer medium, improving transferability of the toner image on the organic photoreceptor to the transfer medium, To provide an organic photoreceptor that prevents the occurrence of voids and dot image deterioration, improves the cleaning properties of the surface layer, and prevents the occurrence of poor cleaning, and a process cartridge using the organic photoreceptor, An image forming method and an image forming apparatus are provided.

  As a result of repeated investigations on the above problems, it is possible to form a dot latent image on an organic photoreceptor formed with an image exposure light source such as a semiconductor laser into a high-definition toner image and to form the high-definition toner. In order to faithfully transfer the image from the organic photoreceptor to the transfer medium and obtain a final toner image, the surface characteristics of the organic photoreceptor can be made uniform in a low surface energy state in micro units and excellent in cleaning properties. The present invention has been completed by finding that it is necessary to develop surface layer technology.

That is, the present invention is achieved by having the following configuration.
1. A conductive support on the organic photoreceptor having a photosensitive layer, an A-B block copolymer surface layer of the organic photoreceptor has a low surface energy component (B component) to end edge (A component (matrix component) B component (low surface energy component) block copolymer), the proportion of B component of the block copolymer is 5.1 mass% or more and 45 mass% or less, and the matrix component is crosslinked. An organophotoreceptor characterized in that the low surface energy components of the B component aggregate to form a domain and form a sea-island structure.
2. 2. The organophotoreceptor according to 1 above, wherein the number average primary particle size of the domains is 1 to 100 nm.
3. 3. The organophotoreceptor according to 1 or 2 above, wherein the surface layer has a domain density of 1 to 10,000 per 1 × 10 ⁴ nm ² .
4). 4. The organophotoreceptor according to any one of items 1 to 3, wherein the B component is a polysiloxane component.
5). 5. The organophotoreceptor according to any one of 1 to 4, wherein the component A is a polymer, and the polymer has a number average molecular weight of 0.5 to 300,000.
6). 6. The organophotoreceptor according to any one of 1 to 5, wherein the polysiloxane component has a number average molecular weight of 200 to 20000.
7). 7. The organophotoreceptor according to any one of items 1 to 6, wherein the component A is a polycarbonate component.
8). 8. The organic photoreceptor according to any one of 1 to 7, wherein the organic photoreceptor has an intermediate layer, a charge generation layer, and a charge transport layer on a conductive support.
9. An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, Transfer means for transferring the visualized toner image onto the transfer medium from the organic photoreceptor, charge eliminating means for removing the charge remaining on the organic photoreceptor after the transfer of the toner image, and residual on the organic photoreceptor after the transfer In a process cartridge used in an image forming apparatus having a cleaning means for removing toner to be removed, an AB block copolymer (A component (matrix) in which the surface layer of the organic photoreceptor has a low surface energy component (B component) at its end. Component) and B component (low surface energy component), and the ratio of the B component of the block copolymer is 5.1 mass% or more and 45 mass% or less, and the matrix The component is cross-linked, the low surface energy component of the B component aggregates to form a domain, and forms an organic island with a sea-island structure and charging means, latent image forming means, developing means, transfer medium, neutralizing means And at least one of the cleaning means is integrally supported, and can be detachably attached to the image forming apparatus main body.
10. An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, A transfer medium for transferring the visualized toner image from the organic photoreceptor onto the transfer medium, a charge eliminating means for removing the charge on the organic photoreceptor after the transfer, and a residual toner on the organic photoreceptor after the transfer are removed. in the image forming method having a cleaning means for, a-B block copolymer surface layer of the organic photoreceptor has a low surface energy component (B component) to end edge (a component (matrix component) and B component (low surface A block copolymer) of the energy component), the ratio of the B component of the block copolymer is 5.1% by mass or more and 45% by mass or less, the matrix component is crosslinked , Low surface energy component Is an image forming method characterized by using an organic photoconductor that aggregates to form a domain to form a sea-island structure .
11. An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, A transfer medium for transferring the visualized toner image from the organic photoreceptor onto the transfer medium, a charge eliminating means for removing the charge on the organic photoreceptor after the transfer, and a residual toner on the organic photoreceptor after the transfer are removed. in the image forming apparatus having a cleaning means for, a-B block copolymer surface layer of the organic photoreceptor has a low surface energy component (B component) to end edge (a component (matrix component) and B component (low surface A block copolymer) of the energy component), the ratio of the B component of the block copolymer is 5.1% by mass or more and 45% by mass or less, the matrix component is crosslinked , Low surface energy component Is an image forming apparatus characterized by using an organic photoreceptor in which domains are formed to form a sea-island structure.

  By using the organic photoreceptor and process cartridge, image forming method, and image forming apparatus of the present invention, a dot latent image formed by using a semiconductor laser or the like can be formed into a high-definition dot image, and the photoreceptor. Therefore, it is possible to improve the transferability of toner from the toner to the transfer medium, to prevent voids and dot image deterioration, and to provide an electrophotographic image with improved cleaning properties.

The organic photoreceptor of the present invention is an organic photosensitive member having a photosensitive layer on an electroconductive substrate, A-B block copolymer surface layer of the organic photoreceptor has a low surface energy component (B component) on the end edge (Block copolymer of component A (matrix component) and component B (low surface energy component)), and the proportion of component B of the block copolymer is 5.1 mass% or more and 45 mass% or less. The matrix component is cross-linked, and the low surface energy components of the B component are aggregated to form a domain to form a sea-island structure.

  Since the organic photoreceptor of the present invention has the above-described configuration, a dot latent image formed by using a semiconductor laser or the like can be formed into a high-definition dot image, and toner from the photoreceptor to the transfer medium can be formed. It is possible to provide an electrophotographic image with improved transferability, preventing voids and dot image deterioration, and improved cleaning properties.

  The organophotoreceptor of the present invention uses, as a binder resin for the surface layer, a block copolymer having both components of a block having a low surface energy component at one end that aggregates with a block constituting a matrix component to form a domain. .

  Here, the low surface energy components in the block copolymer aggregate to form a domain, and the matrix components such as styrene acrylic resin and polycarbonate of the block copolymer form a substrate (sea region of sea island structure), A structure in which polysiloxane or the like having a low surface energy component gathers in a matrix formed of a matrix component to form a domain, and the domain is dispersed in the surface layer.

  The low surface energy component is a component that can form a low surface energy state, and the contact angle of pure water (20 ° C.) of a film prepared only with the low surface energy component is pure of the film formed only with the matrix component. Compared to a contact angle with water (20 ° C.), it exhibits higher characteristics, and it is more preferable that the contact angle is 1 ° or higher.

  Here, a method for measuring the contact angle of the organic photoreceptor will be described.

Measurement of contact angle and contact angle variation The contact angle of the surface of the photoreceptor is 50 ° C. at 23 ° C. using a fully automatic contact angle meter (special CA-W roll: manufactured by Kyowa Interface Science Co., Ltd.). Measure under RH environment. The measurement is completed within 5 to 30 seconds after the dropping of the water droplet in order to achieve both the change in the measured value due to water evaporation and the stability of the measurement. The measurement is based on the θ / 2 method. The contact angle value does not change within the normal water droplet amount range, but in the case of a photosensitive drum, the measurement is from a direction perpendicular to the axial direction, and the deviation from the drum curvature is ignored. Set to 70 μl.

  The measurement is based on the initial photoconductor when added to the layer of the photoconductor, or when the photoconductor is used for image formation from the outside and the surface energy reducing agent is sufficiently applied to the photoconductor surface. (After at least 1000 sheets of repeated image formation). Measurement points were measured at four locations, 90 ° in the circumferential direction, at three locations at the center and 5 cm from the left and right end portions of the cylindrical photoconductor, and the average value was determined as the contact angle of the present invention. And a value that is the largest or most negatively deviated from this average value is taken as the variation value.

  As the polymer component forming the matrix component, a polymer component generally used as a binder resin for an organic photoreceptor such as a polystyrene acrylic component, a polycarbonate component, a polyester component, a polyarylate component, or the like is used. Among these, a polystyrene acrylic component and a polycarbonate component are preferable.

  On the other hand, as the low surface energy component, a polysiloxane component, a fluorinated alkyl polymer component, a higher fatty acid hydrocarbon group and the like are preferable, and among them, the polysiloxane component is most preferable.

  As a synthesis method of the binder resin having a matrix component and a low surface energy component, a known synthesis method can be exemplified. That is, as an example of radical polymerization, polydimethylsiloxane containing an azo group as shown below is used as an initiator, monomer components such as acrylic ester and styrene are dissolved in a solvent together with the initiator, and radical polymerization is performed. An AB block copolymer of polystyrene-acrylic block and polydimethylsiloxane (AB block copolymer in which polydimethylsiloxane is bonded to only one end (one end)) can be obtained.

  Two kinds of polydimethylsiloxane containing the azo group are commercially available, VSP0501 (number average molecular weight of polysiloxane is 5000) and VSP1001 (number average molecular weight of polysiloxane is 10,000) (both are Wako Pure Chemicals Ind Ltd). ).

  In addition, a block copolymer with a condensation polymer such as polycarbonate is also synthesized by using a known block copolymerization synthesis method, so that the polycarbonate block and the AB block of polydimethylsiloxane can be combined. A polymer (a mixture of an AB block copolymer in which polydimethylsiloxane is bonded only to one end and a BAB block copolymer in which polydimethylsiloxane is bonded to both ends) can be obtained.

  That is, using an alkaline solution of a bisphenol compound such as 2,2-bis (4-hydroxy-3-methylphenyl) propane, a methylene chloride solution of a polycarbonate oligomer was prepared by a phosgene method. 2-Benzoyl-5- (3-polydimethylsiloxane propoxy) phenol and antioxidant 4-tert-butylphenol (PTBP) are mixed, and sodium hydroxide is added to have polydimethylsiloxane at the end of the polycarbonate. Block copolymers can be made.

  By the synthesis method as described above, a block copolymer having a matrix component and a low surface energy component according to the present invention can be obtained.

  In the above synthesis method, when the component A is a polycarbonate, it is preferable that a monomer unit having a vinyl group is present in the polycarbonate component in order to cause subsequent crosslinking of the component A. That is, with the bisphenol component such as 2,2-bis (4-hydroxy-3-methylphenyl) propane, the bisphenol component having the following vinyl group in the side chain (0.10 to 10.0 mass in the component A) %) In combination.

  Specific examples of the block copolymer preferably used in the present invention are given below.

  In Table 1, St represents styrene, MMA represents methyl methacrylate, and MA represents methyl acrylate.

  In Table 1, polycarbonate (DM-VBP-1), polycarbonate (Z-VBP-1) and polycarbonate (DM-Z-VBP-1) represent polycarbonate having the following structure. or. () N in n represents the ratio of each component.

  In Table 1, the mass ratio (%) of the low surface energy component indicates the mass ratio of the low surface energy component to the total mass of the block copolymer.

  In addition, blocks 1 to 4 in Table 1 are block copolymers in which all of the low surface energy components are bonded only to one end, and blocks 5 to 7 have been confirmed to have both end and end components (NMR). Data analysis).

  In the surface layer according to the present invention, the low surface energy components gather in the formation process of the surface layer to form a domain having a number average primary particle size of 1 to 100 nm, and in a matrix formed of a styrene acrylic resin component or the like. It has a distributed structure. The domain diameter is preferably a number average primary particle diameter of 1 to 100 nm. If the thickness is less than 1 nm, the effect of improving the contact angle does not last long, and the surface improvement effect tends to decrease. On the other hand, when the thickness exceeds 100 nm, the surface layer cannot be formed in a low surface energy state in a microscopic state, the transferability of the toner image from the organic photoreceptor to the transfer medium becomes partially insufficient, and the voids are likely to occur. If the domain diameter exceeds 100 nm, image blurring and scratches are likely to appear in the halftone image.

  The AB polymer block polymer of the present invention preferably has a smaller B component molecular weight than the A component molecular weight. The polymerization degree of the component A is 0.5 to 300,000 in terms of number average molecular weight, and the number average molecular weight of the component B is preferably 200 to 20000, more preferably 500 to 15000.

  The number average molecular weights of the A and B components of the AB or BAB type block copolymer according to the present invention are calculated by measuring the molecular weight distribution measured by GPC.

  Here, as a method for measuring the molecular weight of the resin by GPC, 1 ml of THF is added to 0.5 to 5.0 mg (specifically 1 mg) of a measurement sample, and stirring is performed at room temperature using a magnetic stirrer or the like. Go and dissolve well. Subsequently, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, the solution is injected into GPC.

  As GPC measurement conditions, the column is stabilized at 40 ° C., THF is allowed to flow at a flow rate of 1 ml per minute, and about 100 μl of a sample having a concentration of 1 mg / ml is injected for measurement. The column is preferably used in combination with a commercially available polystyrene gel column. For example, a combination of Shodex GPC KF-801, 802, 803, 804, 805, 806, and 807 manufactured by Showa Denko KK and TSKgel G1000H, G2000H, G3000H, G4000H, G6000H, G7000H, T7000 guard column manufactured by Tosoh Corporation Combinations can be mentioned. As a detector, a refractive index detector (IR detector) or a UV detector may be used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve prepared using monodisperse polystyrene standard particles. About 10 points may be used as polystyrene for preparing a calibration curve.

  The organophotoreceptor of the present invention is characterized in that the component A is crosslinked. The crosslinking of the component A preferably proceeds simultaneously with the formation of the domain during the formation of the surface layer. That is, the polysiloxane component at one end forms a domain when the surface layer is formed (in the process of applying and drying the surface coating solution), and at the same time, the A component is a polyacrylic (polystyrene acrylic radical polymerization polymer). In the case of (including), melamine formaldehyde and the like are mixed into the surface coating solution. By drying by heating, crosslinking of the component A can be advanced.

  On the other hand, when the component A is a polycarbonate (including a condensation polymer such as polyarylate), since the crosslinking proceeds through the monomer unit having a vinyl group in the side chain, benzoyl peroxide as a polymerization initiator is used. Is preferred. When these polymerization initiators are contained in the surface layer coating solution together with the AB block copolymer and dried by heating, the B component forms a domain, and the crosslinking of the A component proceeds, and the surface of the sea-island structure A layer can be formed.

  Under the present circumstances, 0.1-10 mass parts is preferable with respect to 100 mass parts of AB block copolymers. As the crosslinking of the component A proceeds, the molecular weight of the AB block copolymer increases dramatically, and a surface layer that is insoluble (partially or entirely) in the coating solution solvent of the surface layer can be formed.

  Organic photoreceptors having a surface layer with a sea-island structure in which the low surface energy component (B component) thus formed aggregates to form a domain and cross-linking of the A component proceeds to provide a surface contact angle. Is high (surface energy is low), the transferability of the toner image from the organic photoreceptor to the transfer medium can be improved, and excellent wear resistance can be achieved.

  Next, the structure of the organic photoreceptor of the present invention will be described.

  In order to form a surface layer using a block polymer of the AB component as described above, and to form a domain having a number average primary particle size of 1 to 100 nm in which the B component is aggregated on the surface layer, A- The proportion of the B component in the block polymer of the B component is preferably 0.1% by mass or more and 45% by mass or less, and more preferably 5.1% by mass or more and 45% by mass or less. If it is less than 0.1% by mass, it is difficult to form a domain structure in which B components are aggregated, and if it exceeds 45% by mass, it is difficult to form a continuous matrix structure (sea structure) and wear resistance of the surface layer. Characteristics are likely to deteriorate.

  Furthermore, the polymer component such as the B component polysiloxane component preferably has a relatively low degree of polymerization having a repeating structure of about 10 to 1,000. If the polymer structure of the B component is too large, the B component is less likely to aggregate and a domain structure is difficult to form.

  In addition, selection of a solvent that dissolves the AB block polymer is also important for forming the surface layer. That is, it is preferable to select a good solvent (a solvent that dissolves the matrix component well) as the matrix component of the block polymer and use it as the coating solvent for the surface layer. For example, it is preferable to use a solvent such as tetrahydrofuran or toluene.

  By forming the surface layer under such conditions, it is possible to form a surface layer in which the domain structure of the B component is formed in the matrix structure (sea) composed of the binder component of the A component.

  The number average primary particle size of the domains according to the present invention was observed by observing 100 particles randomly as primary particles by magnifying a cross section cut by a microtome in a direction perpendicular to the surface layer by a transmission electron microscope to 10,000 times ( If necessary, a photograph is taken), and the number average diameter of the ferret diameter is measured by image analysis.

  The domain density of the surface layer is also determined by observing the same cross-sectional structure.

The domain density of the surface layer according to the present invention is preferably such that ² to 10000 domains are distributed with respect to a cross-sectional area of 10000 nm 2. The presence of domains at such a density allows the surface of the photoreceptor to be kept at a low surface energy state, prevents toner filming on the surface, and improves the transferability of the toner image from the photoreceptor to the transfer medium. Image defects such as voids can be prevented.

  Moreover, it describes below about layer structures other than the said surface layer.

  As the organic photoreceptor of the present invention, an organic photoreceptor is preferred. Here, the organic photoconductor means an organic photoconductor constituted by giving an organic compound at least one of a charge generation function and a charge transport function indispensable for the configuration of the organic photoconductor. It contains all known organic photoreceptors such as a photoreceptor composed of a charge generation material or an organic charge transport material, a photoreceptor composed of a polymer complex with a charge generation function and a charge transport function.

The structure of the photoreceptor according to the present invention is not particularly limited as long as it has a surface layer having a sea-island structure in which a domain having a number average primary particle size of 1 to 100 nm in which low surface energy components in a binder resin are aggregated. For example, the following configurations may be mentioned;
1) A structure in which a charge generation layer and a charge transport layer are sequentially laminated as a photosensitive layer on a conductive support;
2) A structure in which a charge generation layer, a first charge transport layer, and a second charge transport layer are sequentially laminated as a photosensitive layer on a conductive support;
3) A structure in which a single layer containing a charge transport material and a charge generation material is formed as a photosensitive layer on a conductive support;
4) A structure in which a charge transport layer and a charge generation layer are sequentially laminated as a photosensitive layer on a conductive support;
5) A structure in which a surface protective layer is further formed on the photosensitive layer of the photoreceptors 1) to 5) above.

  The photoconductor may have any of the above configurations. The surface layer of the photoreceptor is a layer in contact with the air interface. When only a single-layer photosensitive layer is formed on the conductive support, the photosensitive layer is the surface layer, and the conductive layer In the case where a single-layered or laminated photosensitive layer and a surface protective layer are laminated on the conductive support, the surface protective layer is the outermost surface layer. In the present invention, the configuration 2) is most preferably used. Note that, even if the photoreceptor according to the present invention has any configuration, an undercoat layer may be formed on the conductive support prior to the formation of the photosensitive layer.

  The charge transport layer according to the present invention means a layer having a function of transporting charge carriers generated in the charge generation layer by light exposure to the surface of the organic photoreceptor, and the specific detection of the charge transport function is performed by This can be confirmed by laminating the generation layer and the charge transport layer on the conductive support and detecting the optical conductivity.

  A specific configuration of the photoreceptor will be described below by taking as an example the layer configuration of 2) which is most preferably used in the present invention.

Conductive Support As the conductive support used in the photoreceptor according to the present invention, a sheet-like or cylindrical conductive support is used.

  The cylindrical conductive support according to the present invention means a cylindrical support necessary to be able to form an endless image by rotating, and the cylindricity is preferably 5 to 40 μm, more preferably 7 to 30 μm. .

  This cylindricity is based on JIS standard (B0621-1984). That is, when the cylindrical substrate is sandwiched between two coaxial geometric cylinders, it is represented by the difference in radius at the position where the distance between the two coaxial cylinders is minimum. In the present invention, the difference in radius is represented by μm. The method of measuring the cylindricity is obtained by measuring the roundness of 7 points in total, that is, 2 points 10 mm on both ends of the cylindrical substrate, 4 points of the central part, and 4 points obtained by dividing the distance between the both ends. The measuring device can be measured using a non-contact universal roll diameter measuring machine (manufactured by Mitutoyo Corporation).

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

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

Intermediate layer In the present invention, an intermediate layer having a barrier function may be provided between the conductive support and the photosensitive layer.

  In the present invention, in order to improve the adhesion between the conductive support and the photosensitive layer, or to prevent charge injection from the support, an intermediate layer (including an undercoat layer) is provided between the support and the photosensitive layer. Including) can also be provided. Examples of the material for the intermediate layer include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of these resin repeating units. Of these subbing resins, a polyamide resin is preferable as a resin capable of reducing the increase in residual potential due to repeated use. The film thickness of the intermediate layer using these resins is preferably 0.01 to 0.5 μm.

  Examples of the intermediate layer preferably used in the present invention include an intermediate layer using a curable metal resin obtained by thermosetting an organic metal compound such as a silane coupling agent or a titanium coupling agent. As for the film thickness of the intermediate | middle layer using curable metal resin, 0.1-2 micrometers is preferable.

  An intermediate layer preferably used in the present invention includes an intermediate layer in which inorganic particles are dispersed in a binder resin. The average particle size of the inorganic particles is preferably 0.01 to 1 μm. In particular, an intermediate layer in which N-type semiconductive fine particles subjected to surface treatment are dispersed in a binder is preferable. For example, an intermediate layer in which titanium oxide having an average particle diameter of 0.01 to 1 μm, which has been surface-treated with silica / alumina treatment and a silane compound, is dispersed in a polyamide resin. The film thickness of such an intermediate layer is preferably 1 to 20 μm.

  The N-type semiconducting fine particles are fine particles having the property of using conductive carriers as electrons. That is, the property that the conductive carrier is an electron is that the N-type semiconducting fine particles are contained in an insulating binder to effectively block hole injection from the substrate, and to convert electrons from the photosensitive layer into electrons. On the other hand, it has the property which does not show blocking property.

  Here, a method for discriminating N-type semiconductor particles will be described.

  An intermediate layer having a thickness of 5 μm is formed on the conductive support (the intermediate layer is formed using a dispersion in which 50% by mass of particles are dispersed in the binder resin constituting the intermediate layer). The intermediate layer is negatively charged, and the light attenuation characteristic is evaluated. In addition, the light attenuation characteristics are similarly evaluated by charging to positive polarity.

  N-type semiconductive particles are particles that are dispersed in the intermediate layer in the above evaluation when the light attenuation when charged negatively is greater than the light attenuation when charged positively. It is called semiconductive particle.

Specific examples of the N-type semiconducting fine particles include fine particles of titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), etc. In the present invention, titanium oxide is particularly preferably used. It is done.

  The average particle diameter of the N-type semiconducting fine particles used in the present invention is preferably in the range of 10 nm to 500 nm in the number average primary particle diameter, more preferably 10 nm to 200 nm, and particularly preferably 15 nm to 50 nm. .

  The intermediate layer using N-type semiconducting fine particles whose number average primary particle size is within the above range can be finely dispersed in the layer, has sufficient potential stability, and generates black spots. Has a prevention function.

  For example, in the case of titanium oxide, the number-average primary particle size of the N-type semiconducting fine particles is magnified 10,000 times by observation with a transmission electron microscope, and 100 particles are randomly observed as primary particles. It is measured as the number average diameter.

  The shape of the N-type semiconducting fine particles used in the present invention includes dendritic, needle-like, and granular shapes. For example, in the case of titanium oxide particles, the N-type semiconductive fine particles have a crystalline form. There are anatase type, rutile type and amorphous type, but any crystal type may be used, or two or more crystal types may be mixed and used. Of these, the rutile type is the best.

  One of the hydrophobizing surface treatments performed on the N-type semiconducting fine particles is a plurality of surface treatments, and the last surface treatment is a surface treatment with a reactive organosilicon compound. Is to do. In addition, at least one of the surface treatments is at least one surface treatment selected from alumina, silica, and zirconia, and finally the surface treatment of the reactive organosilicon compound is performed. It is preferable.

  Alumina treatment, silica treatment, and zirconia treatment are treatments for precipitating alumina, silica, or zirconia on the surface of the N-type semiconducting fine particles. Zirconia hydrates are also included. The surface treatment of the reactive organosilicon compound means using a reactive organosilicon compound in the treatment liquid.

  In this way, the surface treatment of the N-type semiconductive fine particles such as titanium oxide particles was performed at least twice, so that the surface of the N-type semiconductive fine particles was uniformly coated (treated), and the surface treatment was performed. When N-type semiconducting fine particles are used in the intermediate layer, a good photoconductor having good dispersibility of N-type semiconductive fine particles such as titanium oxide particles in the intermediate layer and causing no image defects such as black spots. You can get it.

Photosensitive Layer The photosensitive layer configuration of the organic photoreceptor of the present invention has a photosensitive layer containing at least a charge generating substance and a charge transporting substance on a conductive substrate. The photosensitive layer may be composed of a photosensitive layer in which the charge generation material and the charge transport material are present in the same layer, but more preferably, a charge generation layer (CGL) containing a charge generation material on a conductive support and A stacked structure of a charge transport layer (CTL) containing a charge transport layer is preferred. Hereinafter, the organic photoreceptor of the present invention will be described focusing on the layer structure of the laminated structure.

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

  A known charge generation material (CGM) can be used as the charge generation material (CGM). For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azulenium pigment, or the like can be used. Among these, the CGM that can minimize the increase in residual potential due to repeated use has a three-dimensional and potential structure that can form a stable aggregate structure among a plurality of molecules. Specifically, a phthalocyanine having a specific crystal structure. CGM of pigments and perylene pigments. For example, CGM such as titanyl phthalocyanine having a maximum peak at a Bragg angle 2θ of 27.2 ° with respect to Cu-Kα ray and benzimidazole perylene having a maximum peak at 2θ of 12.4 has little deterioration due to repeated use. Potential increase can be reduced.

  When a binder is used as a CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably 0.01 μm to 2 μm.

Charge Transport Layer As described above, in the present invention, the charge transport layer is preferably composed of a plurality of charge transport layers, and the surface layer structure of the present invention is applied to the uppermost charge transport layer.

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

  As the charge transport material (CTM), a known hole transport property (P-type) charge transport material (CTM) is preferably used. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer. In particular, a charge transport material that does not absorb the wavelength of laser light for image exposure is preferably used.

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

  The ratio of the binder resin to the charge transport material is preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin. The total thickness of the charge transport layer is preferably 20 μm or less, and more preferably 10 to 16 μm. When the film thickness exceeds 20 μm, laser absorption and scattering in the charge transport layer increase, and sharpness and residual potential tend to increase.

  The surface layer according to the present invention preferably contains an antioxidant. The presence of an antioxidant in the surface layer of the sea-island structure in which the low surface energy components in the block copolymer are aggregated to form a domain prevents the surface layer from deteriorating, thereby degrading the transfer characteristics and cleaning properties. Can be prevented. 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. Typical examples include the following compound groups.

  Solvents or dispersion media used to form layers such as intermediate layers, charge generation layers, and charge transport layers include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone , Methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, Tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cello Lube, and the like. Although this invention is not limited to these, Dichloromethane, 1, 2- dichloroethane, methyl ethyl ketone, etc. are used preferably. These solvents may be used alone or as a mixed solvent of two or more.

  Next, an image forming apparatus using the organic photoreceptor according to 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, a semiconductor laser or a light emitting diode can be 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 direction is narrowed to 10 to 80 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.

  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 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 above 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 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.

  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. 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 fixed by heating.

  The image forming method 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 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 a cylindrical aluminum support (diameter = 60 mm) was cut to prepare a conductive support having a ten-point surface roughness Rz = 1.5 (μm).

<Intermediate layer>
The following intermediate layer dispersion was diluted twice with the same mixed solvent, and allowed to stand overnight, followed by filtration (filter; rigesh mesh 5 μm filter manufactured by Nihon Pall) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part Inorganic particles: Titanium oxide (Number average primary particle size 35 nm: Titanium oxide treated with silica / alumina and methylhydrogenpolysiloxane) 3 parts Methanol 10 parts are mixed as a disperser Using a sand mill, batch dispersion was performed for 10 hours to prepare an intermediate layer dispersion.

  It apply | coated so that it might become a dry film thickness of 1.0 micrometer on the said support body using the said coating liquid.

<Charge generation layer: CGL>
Titanyl phthalocyanine pigment (a titanyl phthalocyanine pigment having a maximum diffraction peak at 27.3 ° in the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu-Kα) 24 parts Polyvinyl butyral resin “ESREC BL- 1 ”(manufactured by Sekisui Chemical Co., Ltd.) 12 parts 2-butanone / cyclohexanone = 4/1 (v / v) 300 parts The above composition was mixed and dispersed using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.5 μm on the intermediate layer.

<Charge transport layer 1 (CTL1)>
Charge transport material (4,4′-dimethyl-4 ″-(α-phenylstyryl) triphenylamine) 225 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts Antioxidant (Exemplary Compound AO2-1) 6 parts Dichloromethane 2000 parts Silicon oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part was mixed and dissolved to prepare a charge transport layer coating solution 1. This coating solution was applied onto the charge generation layer by a dip coating method. Then, drying was performed at 110 ° C. for 70 minutes to form a charge transport layer 1 having a dry film thickness of 18.0 μm.

<Surface layer: Charge transport layer 2 (CTL2)>
Charge transport material (4,4′-dimethyl-4 ″-(α-phenylstyryl) triphenylamine) 150 parts Binder: (Block copolymer of Block 1) 300 parts Antioxidant (Exemplary Compound AO2-1) 12 parts THF: tetrahydrofuran (containing 1.0% by weight of water) 1200 parts Silicon oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 4 parts are mixed and dissolved, and then 2 parts of melamine-formaldehyde (MF) resin is added. A charge transport layer coating solution 2 was prepared, and this coating solution was coated on the charge transport layer 1 with a circular slide hopper type coating machine, dried at 110 ° C. for 70 minutes, and a dry film thickness of 2. A 0 μm charge transport layer 2 was formed to produce a photoreceptor 1.

Production of photoconductors 2 to 7 Photoconductors 2 to 7 were produced in the same manner as photoconductor 1 except that the binder type of charge transport layer 2 (CTL2) was changed as shown in Table 2 in production of photoconductor 1. did. (However, in the photoconductors 5, 6 and 7, benzoyl peroxide was used instead of melamine-formaldehyde (MF) resin.)
Production of Photoreceptor 8 Photoreceptor 8 was produced in the same manner except that the following graft copolymer (GP1) was used instead of block 1 of charge transport layer 2 of photoreceptor 1.

Production of Photoreceptor 9 Photoreceptor 9 was produced in the same manner except that melamine-formaldehyde (MF) resin was removed from charge transport layer 2 of photoreceptor 1.

  The measurement results of domain diameter and domain density of these photoreceptors 1 to 9 were as shown in Table 2.

  In addition, it was confirmed by IR (infrared) spectrum analysis that each of the surface layers used in the photoreceptors 1 to 7 and 9 contains an AB block copolymer.

  The evaluation of cross-linking in Table 2 was conducted when each of the photoconductors 1 to 9 was immersed in a THF solvent at 25 ° C. for 5 hours, and the surface layer (charge transport layer 2) remained without being dissolved. When the surface layer was dissolved and the lower layer appeared on the surface, it was evaluated that the cross-linked structure was insufficient (x).

<< Evaluation 1 >>
<Live-action evaluation>
The above photoreceptor was mounted on a commercially available full-color multifunction device 8050 (manufactured by Konica Minolta Business Technologies Co., Ltd.) basically having the configuration shown in FIG. 2, and color images were evaluated.

Evaluation condition Photoconductor linear velocity: 220 mm / sec
《Image evaluation》
Original image with A4 paper, 10,000 text images, white solid image, black solid image, halftone image in high temperature and high humidity (30 ° C, 80% RH) environment with each photoconductor mounted on full color multifunction device 8050 A copy image was taken out at the start and every 1,000 copies, and the following image evaluation was performed.

Other conditions for image formation Process speed: 220 mm / sec
Developer: A two-component developer (both Y, M, C, and Bk) containing a carrier and a toner was used.

  Photoconductor cleaning device: A rubber elastic cleaning blade was used under a contact condition of (linear load: 18 (N / m)).

  Intermediate transfer member cleaning device: A rubber elastic cleaning blade was used.

Reproducibility of toner image on photoconductor (evaluated with cyan toner image)
The toner image on the photoreceptor was transferred to a transparent adhesive sheet for evaluation.

A: The occurrence of voids is very small, and the dot image is clearly reproduced (good)
○: There is a small void, but the dot image is reproduced (practical)
×: Many voids occur and the shape of the dot image is broken (unusable)
Reproducibility of toner image on intermediate transfer member (evaluated with cyan toner image)
The toner image on the intermediate transfer member was transferred to a transparent adhesive sheet, and the transferred image was evaluated.

A: The occurrence of voids is very small, and the dot image is clearly reproduced (good)
○: There is a small void, but the dot image is reproduced (practical)
×: Many voids occur and the shape of the dot image is broken (unusable)
(Cleanability)
After the above evaluation, without replacing the cleaning blade, only the linear load of the cleaning blade contacting the photoconductor was changed from 18 (N / m) to 9 (N / m), and 10,000 continuous copies were made. The cleaning performance was evaluated.

◎ Throughout the printing of 10,000 sheets, there is no occurrence of cleaning defects such as toner slipping out (good)
○: Spiral cleaning defects such as toner slipping occurred during printing on 10,000 sheets, but no toner filming was found on the photoconductor, and there was no practical problem (no problem in practical use)
×: Continuous printing failure (2 or more) occurs during printing on 10,000 sheets, or toner filming is observed on the photoreceptor (practical problem)
Measurement of Contact Angle The contact angles of these photoconductors 1 to 8 were measured before and after the 10,000 copies were evaluated (start (St) and end (End)), and the results are shown in Table 3. The contact angle was measured by the method described above.

Evaluation of film thickness wear amount After the evaluation of the cleaning property, the linear load of the cleaning blade was returned to 18 (N / m), and 100,000 copies were made to evaluate the film thickness wear amount of the photoreceptor. The amount of film thickness loss was evaluated as follows.

  As for the film thickness of the photosensitive layer, 10 portions of the uniform film thickness are randomly measured, and the average value is defined as 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).

  The evaluation results are shown in Table 3 below.

Table 3 As is apparent, the block copolymer of the surface layer is a low surface energy component A-B block copolymer having a (B component) of the end edge (A component (matrix component) and B component (low surface energy component) Polymer), the proportion of the B component of the block copolymer is 5.1 mass% or more and 45 mass% or less, the matrix component is crosslinked, and the low surface energy component of the B component is an aggregate. The photoreceptors 5 to 7 of the present invention, which form a domain and a sea-island structure, have a toner image reproducibility on the photoreceptor, a toner image reproducibility on an intermediate transfer member, a cleaning property, and While good results were obtained in all evaluations of film thickness loss, the photoconductor 8 that does not have a domain in which low surface energy components are aggregated in the surface layer has a lot of voids on the intermediate transfer member. Degradation of toner image reproducibility Also deteriorate cleanability, thickness depletion amount is large. In addition, the photoreceptor 9 that does not have a crosslinked structure has a large thickness loss.

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

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 21 Photoconductor 22 Charging means 23 Developing means 24 Transfer pole 25 Separation pole 26 Cleaning device 30 Exposure optical system 45 Transfer conveyance belt apparatus 50 Fixing means 250 Separation claw unit

Claims (11)

A conductive support on the organic photoreceptor having a photosensitive layer, an A-B block copolymer surface layer of the organic photoreceptor has a low surface energy component (B component) to end edge (A component (matrix component) B component (low surface energy component) block copolymer), the proportion of B component of the block copolymer is 5.1 mass% or more and 45 mass% or less, and the matrix component is crosslinked. An organophotoreceptor characterized in that the low surface energy components of the B component aggregate to form a domain and form a sea-island structure. 2. The organophotoreceptor according to claim 1, wherein the number average primary particle size of the domains is 1 to 100 nm. 3. The organic photoreceptor according to claim 1, wherein the surface layer has a domain density of 1 to 10,000 per 1 × 10 ⁴ nm ^{2. 4} . The organophotoreceptor according to claim 1, wherein the B component is a polysiloxane component. The organophotoreceptor according to any one of claims 1 to 4, wherein the component A is a polymer, and the polymer has a number average molecular weight of 0.5 to 300,000. The organophotoreceptor according to claim 1, wherein the polysiloxane component has a number average molecular weight of 200 to 20,000. The organophotoreceptor according to claim 1, wherein the component A is a polycarbonate component. The organic photoconductor according to claim 1, wherein the organic photoconductor has an intermediate layer, a charge generation layer, and a charge transport layer on a conductive support. An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, Transfer means for transferring the visualized toner image from the organic photoreceptor onto the transfer medium, charge eliminating means for removing the charge remaining on the organic photoreceptor after the transfer of the toner image, and residual on the organic photoreceptor after the transfer In a process cartridge used in an image forming apparatus having a cleaning means for removing toner, the surface layer of the organic photoreceptor has an AB block copolymer (A component (matrix) having a low surface energy component (B component) at its terminal. Component) and B component (low surface energy component), and the ratio of the B component of the block copolymer is 5.1% by mass or more and 45% by mass or less. The components are cross-linked, and the low surface energy component of the B component aggregates to form a domain, and the organic photoreceptor forming the sea-island structure and charging means, latent image forming means, developing means, transfer medium, neutralizing means And at least one of the cleaning means is integrally supported and can be detachably attached to the main body of the image forming apparatus. An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, A transfer medium for transferring the visualized toner image from the organic photoreceptor onto the transfer medium, a charge eliminating means for removing the charge on the organic photoreceptor after the transfer, and a residual toner on the organic photoreceptor after the transfer are removed. in the image forming method having a cleaning means for, a-B block copolymer surface layer of the organic photoreceptor has a low surface energy component (B component) to end edge (a component (matrix component) and B component (low surface A block copolymer) of the energy component), the ratio of the B component of the block copolymer is 5.1% by mass or more and 45% by mass or less, the matrix component is crosslinked , Low surface energy component Is an image forming method characterized by using an organic photoconductor that aggregates to form a domain to form a sea-island structure . An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, A transfer medium for transferring the visualized toner image from the organic photoreceptor onto the transfer medium, a charge eliminating means for removing the charge on the organic photoreceptor after the transfer, and a residual toner on the organic photoreceptor after the transfer are removed. in the image forming apparatus having a cleaning means for, a-B block copolymer surface layer of the organic photoreceptor has a low surface energy component (B component) to end edge (a component (matrix component) and B component (low surface A block copolymer) of the energy component), the ratio of the B component of the block copolymer is 5.1% by mass or more and 45% by mass or less, the matrix component is crosslinked , Low surface energy component Is an image forming apparatus characterized by using an organic photoreceptor in which domains are formed to form a sea-island structure.

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