JP2008020900A - Developing roller, electrophotographic process cartridge, and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller which can be inhibited from staining due to exudates or developer or the like from a peripheral member such as a toner supply roller and a toner amount regulating member, can inhibit the staining of the peripheral member due to the exudates from the developing roller, and is inhibited from occurring irregular hardness. <P>SOLUTION: The developing roller 1 having an elastic layer 3 on the conductive shaft center body 2 has on its surface, a surface layer 4 containing polymer obtained by polymerizing polyolefine polyol (A) whose number average molecular weight Mn based on the molecular weight distribution obtained by a GPC method is 3,000≤Mn≤15,000, and whose degree of dispersion Mw/Mn is 2.80≤Mw/Mn≤12.50, and a full-alkyl type melamine compound (B). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing roller, an electrophotographic process cartridge and an electrophotographic apparatus using the developing roller.

  Image forming apparatuses are used in electrophotographic apparatuses such as copying machines and optical printers, electrostatic recording apparatuses, and the like. In the image forming apparatus, a photosensitive member that is a rotatable latent image carrier, a charging unit that uniformly charges the photosensitive member around the photosensitive member, and an electrostatic latent image is formed on the uniformly charged surface of the photosensitive member by exposure. An exposure means for developing, and a developing means for forming a toner image by supplying a developer to the photosensitive member for development. Furthermore, there are a transfer means for transferring the toner image on the photosensitive member onto the transfer material, a fixing means for fixing the toner on the transfer material, a cleaning means for removing the toner remaining on the surface of the photosensitive member after the toner transfer. Provided.

In such a developing device of an electrophotographic image forming apparatus, a developing roller is provided so as to close an opening of a developer container for storing the developer and to expose a part of the developer container outside. The developer is supplied onto the surface of the developing roller by a toner supply roller provided in contact with the developing roller in the developer container. Next, the toner amount regulating member removes the surplus portion to form a developer on the developing roller in a thin film shape, and at the same time, positive or negative charge is given to the toner particles by friction. Further, the developer charged positively or negatively by the rotation of the developing roller is conveyed to the developing area of the exposed portion, and is developed by being attached to the electrostatic latent image on the surface of the photoconductor provided opposite thereto. Such a developing roller has a conductive property (electric resistance) suitable for the purpose in a semiconductive region of 10 ³ to 10 ¹⁰ Ω so that toner can be easily transferred in order to carry charged toner. Therefore, an elastic layer having appropriate elasticity is provided. As the material of the developing roller, a polymer elastomer having a rubber elasticity, a polymer foam, or the like is used. Further, a developing roller having one or two or more resin layers on an elastic layer is used for the purpose of enhancing the functionality of the developing roller.

  In such a developing roller, the exudate from the developing roller may contaminate the surface of the photoreceptor when exposed to a special environment such as high temperature and high humidity. As a result, when the image is output, a horizontal band (photosensitive member axial direction) image defect occurs on the image at the rotation cycle of the photosensitive member. Therefore, there is a demand for suppressing the exudation of the composition from the developing roller. In order to suppress the exudation of the composition from the developing roller, a method for suppressing contamination of the photoreceptor by using a hydrophobic polyol in the elastic layer (Patent Document 1) and the like have been reported. Has been.

  However, a developing roller that uses only an elastic layer of hydrophobic polyol can suppress contamination of the photoreceptor, but exudates from the toner supply roller, toner amount regulating member, and photoreceptor are on the surface of the developing roller. There was a case where it adheres firmly and stains occur. When an image is formed using such a developing roller, a horizontal belt shape or a haze shape of the rotation cycle of the developing roller is caused in the output image due to a difference in toner carrying amount or toner charge amount between the contaminated portion and the uncontaminated portion. There was a problem that an image defect occurred.

  Further, when the developing roller is used for a long period of time, if the developing roller has insufficient durability, the developing roller may be scraped or scratched, and therefore there is a demand for a developing roller having excellent durability. A developing roller having a coating layer formed of a cured product composed of a polyol and a melamine resin has been reported (Patent Document 2).

  However, in the above method, the compatibility between the polyol and the melamine resin is insufficient, and minute hardness unevenness occurs on the surface of the developing roller. In a developing roller having such hardness unevenness on the surface, a phenomenon (filming) may occur in which toner adheres to a portion having a high surface hardness with use. As a result, the filming portion may appear in the image as a fog.

These image defects become more prominent in an electrophotographic apparatus with high image quality, high functionality, and high image quality. For this reason, in order to achieve high speed, high functionality, and high image quality in an electrophotographic apparatus, it is necessary to suppress adhesion of exudates and to suppress contamination of peripheral members including the photosensitive member and the developing roller itself. It is. In addition, there is a need for a developing roller that can suppress the sticking of toner to the surface of the developing roller even when used for a long period of time and can suppress the occurrence of fog.
JP-A-8-272211 JP 2000-321863 A

  An object of the present invention is to suppress contamination of the developing roller due to exudate from a peripheral member such as a toner supply roller and a toner amount regulating member and developer, while suppressing the occurrence of exudate from the developing roller. An object of the present invention is to provide a developing roller capable of reducing contamination. A further object of the present invention is to provide a developing roller that can suppress the occurrence of horizontal band and haze image defects even when applied to a high-speed, high-function, high-quality electronic image forming apparatus. Another object of the present invention is to provide a developing roller that can reduce unevenness in hardness, suppress sticking of toner to the surface even when used for a long period of time, and obtain an image with reduced fog.

  In addition, it can be used for high-speed, high-function, high-quality electrophotographic devices to suppress the occurrence of horizontal band and haze-like image defects, and to suppress the occurrence of fogging for a long time. An object is to provide an electrophotographic cartridge and an electrophotographic apparatus capable of obtaining a high-quality image.

  By using a polymer of a polyolefin polyol having a specific molecular weight and a full-alkyl melamine compound, the present inventors suppress the adhesion of contaminants to peripheral members and the developing roller, and the occurrence of hardness unevenness. The knowledge that it can suppress was obtained. Based on this knowledge, the present invention has been completed.

  That is, according to the present invention, in a developing roller having an elastic layer on a conductive shaft core, the number average molecular weight Mn based on the molecular weight distribution obtained by the GPC method is 3000 ≦ Mn ≦ 15000 on the surface, and the dispersity Mw / Mn Characterized by having a surface layer containing a polymer obtained by polymerizing a polyolefin polyol (A) in which 2.80 ≦ Mw / Mn ≦ 12.50 and a full-alkyl melamine compound (B) Regarding the roller.

  The present invention also provides a developing roller for supplying a developer to the surface of the latent image carrier to form a toner image, and in an electrophotographic process cartridge that is detachable from an electrophotographic apparatus, the developing roller is the developing roller. The present invention relates to a characteristic electrophotographic process cartridge.

  The present invention also relates to an electrophotographic apparatus having a developing roller that supplies a developer to the surface of a latent image carrier to form a toner image, wherein the developing roller is the developing roller.

  The developing roller of the present invention suppresses the contamination of the developing roller due to exudate from the peripheral members such as the toner supply roller and the toner amount regulating member and the developer, while suppressing the generation of exudates from the developing roller. Reduction of contamination can be achieved. Further, the developing roller of the present invention can suppress the occurrence of horizontal band and haze image defects even when applied to a high speed, high function, high image quality electronic image forming apparatus. Further, it is possible to reduce the unevenness of hardness, to suppress the sticking of the toner to the surface even when used for a long time, and to obtain an image in which the occurrence of fog is suppressed.

  Furthermore, the electrophotographic process cartridge and the electrophotographic image forming apparatus of the present invention suppress the occurrence of horizontal band and haze-like image defects even when a high-speed, high-function, high-quality electronic image forming apparatus is applied. The generation of fog can be suppressed and a high-quality image can be obtained over a long period of time.

The developing roller of the present invention has an elastic layer on the conductive shaft core. And it has the surface layer containing the polymer obtained by superposing | polymerizing the following polyolefin polyol (A) and a full alkyl type | mold melamine compound (B).
Polyolefin polyol (A): Number average molecular weight Mn based on molecular weight distribution curve obtained by GPC method is 3000 ≦ Mn ≦ 15000, and dispersity Mw / Mn is 2.80 ≦ Mw / Mn ≦ 12.50.

  The conductive shaft core used in the developing roller of the present invention can support the upper elastic layer and the surface layer, and has conductivity capable of acting as an upper electrode. Examples of the material include metals or alloys such as aluminum, copper alloy, and stainless steel; iron plated with chromium, nickel, etc .; synthetic resin having conductivity. Furthermore, what carried out the rust prevention process, such as an oxidation process, to the metal electroconductive shaft center material can be used.

  The shape of the conductive shaft core may be either a hollow body or a solid body, and if necessary, a primer treatment layer may be formed on the surface thereof. Examples of the outer diameter of the conductive shaft core include a range of 4 mm to 10 mm.

  The elastic layer in the developing roller of the present invention has a hardness capable of pressing the photoreceptor with an appropriate nip width and nip pressure so that the toner can be supplied to the electrostatic latent image formed on the photoreceptor surface without excess or deficiency. And elasticity are provided to the developing roller. Such an elastic layer is preferably composed of a molded body of rubber material. Specific examples of the rubber material will be given below. Ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR). Natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), fluorine rubber, silicone rubber, epichlorohydrin rubber, hydride of NBR, urethane rubber and the like. These can be used alone or in combination of two or more. Among these, it is preferable to use silicone rubber from the viewpoint of setting performance and the like. Examples of the silicone rubber include polydimethylsiloxane, polymethyltrifluoropropylsiloxane, polymethylvinylsiloxane, polyphenylvinylsiloxane, copolymers of these polysiloxanes, and the like.

  The elastic layer preferably contains a conductivity-imparting agent based on an ionic conduction mechanism or an electronic conduction mechanism and has semiconductivity. Specific examples of the conductivity-imparting agent include carbon-based materials such as carbon black and graphite, metals or alloys such as aluminum and copper, and metal oxides such as zinc oxide, titanium oxide, aluminum oxide, and tin oxide. Can do. These conductivity-imparting agents can be used as fine particles such as powder or fiber, and can be used alone or in combination of two or more. Among these, carbon black is preferable from the viewpoints of easy conductivity control, imparting good chargeability to the developing roller, and economical.

The elastic layer preferably has a volume resistivity of 10 ³ to 10 ¹⁰ Ω · cm when a DC voltage of 100 V is applied. When the volume resistivity of the conductive elastic layer is 1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm, the toner can be uniformly charged. For example, in the case of carbon black, the amount of the conductivity-imparting agent used to make the elastic layer have such a volume resistivity value is 15 to 80 parts by mass with respect to 100 parts by mass of the rubber component. it can.

  Here, when measuring the volume resistivity of the elastic layer, the elastic layer material is cured under the same conditions as those for forming the elastic layer to produce a 2.0 mm thick elastic layer test piece. To make measurements. Specifically, the elastic layer material is formed into a sheet and placed in a 130 ° C. oven for 20 minutes to form two 2.0 mm thick sheets, and then heated in a 200 ° C. oven for 4 hours for secondary vulcanization. I do. After that, the sheet is left in an environment of temperature 25 ° C. and humidity 45% for 24 hours or more, and measured by applying a voltage of 100 V using Hiresta IP (manufactured by Mitsubishi Oil Chemical Co., Ltd.). The volume resistivity can be obtained as an average value.

  Such an elastic layer has a crosslinking agent, a plasticizer, a filler, an extender, a vulcanizing agent, a vulcanization aid, a crosslinking aid, an antioxidant as long as it does not impair the function of the above composition. Various additives such as an agent, an anti-aging agent and a processing aid can be contained. Examples of the nonconductive filler include silica, quartz powder, titanium oxide, zinc oxide, calcium carbonate and the like. Examples of the crosslinking agent include di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, and the like.

  The thickness of the elastic layer can be appropriately selected so as to have a desired elasticity in relation to the toner amount regulating member, the photoconductor, and the like, and can include, for example, a range of 2.0 to 6.0 mm. 3.0 to 5.0 mm is preferable.

  The surface layer in the developing roller of the present invention contains a polymer obtained by polymerizing the polyolefin polyol (A) and the full alkyl melamine compound (B), thereby suppressing the adhesion of contaminants to the developing roller surface. it can. Moreover, generation | occurrence | production of the exudate from a developing roller can be suppressed, and contamination of a peripheral member can be suppressed. Further, it is possible to suppress the occurrence of hardness unevenness, to suppress toner sticking during long-term use, and to suppress fogging.

  As the polyolefin polyol (A) constituting the polymer used for the surface layer, the number average molecular weight Mn based on the molecular weight distribution obtained by the GPC method is 3000 to 15000, and the dispersity Mw / Mn is 2.80 to 12 .50 or less. If the number average molecular weight Mn of the polyolefin polyol (A) is 3000 or more, the amount of the low-molecular-weight polyolefin polyol remaining without participating in the polymerization reaction can be reduced. Moreover, if the number average molecular weight Mn of polyolefin polyol (A) is 15000 or less, it can suppress that compatibility with a full alkyl type melamine compound (B) falls. When the polyolefin polyol (A) has a number average molecular weight within the above range, unreacted components are reduced, and compatibility with the full-alkyl melamine compound (B) can be balanced. For this reason, in the developing roller, it is possible to suppress the occurrence of unevenness in hardness, to have an excellent contamination suppressing effect, to suppress toner adhesion after long-term use, and to suppress fogging.

  Further, when the molecular weight dispersity Mw / Mn of the polyolefin polyol (A) is 2.80 or more and 12.50 or less, the polyolefin polyol (A) has excellent compatibility with the full-alkyl melamine compound (B) and has an excellent antifouling effect. . Moreover, since it is excellent in compatibility, it is possible to suppress the occurrence of hardness unevenness and to suppress fogging due to toner fixation after long-term use.

  Here, the molecular weight distribution obtained by the GPC method can be obtained from measurement using Gel Permeation Chromatography. Specifically, a high performance liquid chromatograph analyzer (HLC-8120GPC: manufactured by Tosoh Corporation) in which two GPC columns (TSKgel SuperHM-m: manufactured by Tosoh Corporation) are connected in series is used. The measurement conditions are a temperature of 40 ° C., a flow rate of 0.6 ml / min, and an RI (refractive index), and the measurement sample is measured as a 0.1 mass% tetrahydrofuran (THF) solution. Monodisperse standard polystyrene (TSK standard polystyrene F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500 as a standard sample. A-1000, A-500: manufactured by Tosoh Corporation) to create a calibration curve. The molecular weight distribution is obtained from the retention time or the count number of the measurement sample. From this distribution, the number average molecular weight Mn, the weight average molecular weight Mw, and the degree of dispersion Mw / Mn can be determined.

  In addition, the molecular weight distribution curve represents the molecular weight distribution obtained as described above on a graph in which the molecular weight (logarithmic display) is taken on the X axis and the mass / molecular weight (peak area is 1) on the Y axis. Can be obtained. In the molecular weight distribution curve, the peak area in each molecular weight range indicates the mass fraction.

  Further, as shown in FIG. 1, the polyolefin polyol (A) preferably has two or more peaks between molecular weights 3000 and 15000 in the molecular weight distribution curve obtained by the GPC method. The peak is preferably not an inflection point but an extreme value. By having two or more peaks in the molecular weight distribution curve, the balance between the low molecular weight component having compatibility with the full alkyl type melamine compound (B) and the high molecular weight component exhibiting the function of stain resistance is improved. The roller can be provided with excellent antifouling properties. Further, since the occurrence of unevenness in hardness can be suppressed, toner adhesion after long-term use can be suppressed and fogging can be suppressed.

  Among such peaks having a molecular weight between 3000 and 15000, the intensity ratio (Imax) / (Imin) of the peak intensity (Imax) at the maximum molecular weight and the peak intensity (Imin) at the minimum molecular weight is 0.5 or more. Particularly preferably, it is 0 or less. In the polyolefin polyol (A) having a peak intensity ratio of molecular weight in the above range, a low molecular weight component that maintains the polymerizability with the full-alkyl melamine compound (B) and a high molecular weight component that exhibits antifouling function The balance becomes better. For this reason, it is possible to impart an excellent contamination suppressing effect to the developing roller. Further, since it is possible to suppress the occurrence of uneven hardness on the surface of the developing roller, it is possible to prevent toner sticking after long-term use and to suppress fogging appearing in the image.

  The polyolefin polyol (A) preferably contains a polyolefin polyol (a1) and a polyolefin polyol (a2). These polyolefin polyol (a1) and polyolefin polyol (a2) preferably have the same repeating unit. Furthermore, it is preferable that the polyolefin polyol (a1) and the polyolefin polyol (a2) have different number average molecular weights based on the molecular weight distribution obtained by the GPC method. By including the polyolefin polyols (a1) and (a2) having the same repeating unit and different molecular weight distributions, (Imax) / (Imin) between 3000 and 15000 can be easily adjusted to the above range. .

  The polyolefin polyol (A) having the same repeating unit is one in which the constituent units of the polyolefin polyol polymer are the same, and in the case of a copolymer, the abundance ratios of plural types of constituent units are the same.

  The number average molecular weight of the polyolefin polyol (a1) and polyolefin polyol (a2) based on the molecular weight distribution obtained by the GPC method is preferably 2500 to 70000. The polyolefin polyol (a1) preferably has a number average molecular weight of 2500 to 6000, and the polyolefin polyol (a2) preferably has a number average molecular weight of 7500 to 70000. It is preferable that

  Examples of the polyolefin polyol (A) include compounds in which a hydroxyl group is bonded to a polymer of a diene compound. Specific examples include compounds in which a hydroxyl group is bonded to a polymer of a diene compound such as butadiene and isoprene. Among these, polybutadiene polyol can be mentioned as a preferable one because it suppresses adhesion of contaminants on the developing roller.

  The example of such a polyolefin polyol (A) manufacturing method is given below. (1) A method of polymerizing a diene monomer such as butadiene in the presence of hydrogen peroxide. (2) A method in which a diene polymer and water are reacted in the presence of a protonic acid. (3) A method of polymerizing a diene monomer in the presence of an azo compound having a hydroxyl group.

  The full alkyl melamine compound (B) constituting the polymer used for the surface layer is represented by the formula (1)

The melamine compound (monomer) represented by this, the multimer (oligomer) of this melamine compound, and these mixtures can be mentioned. In the formula (1), the substituents R ^{1 to} R ⁶ independently represent an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, or a hexyl group. Of these, the substituents R ^{1 to} R ⁶ preferably represent a methyl group or a butyl group, and more preferably all represent a methyl group or all represent a butyl group. More preferably, the substituents R ^{1 to} R ⁶ are a methyl group or a butyl group, and all are methyl groups or all are butyl groups. Of the full-alkyl melamine compounds (B) represented by the formula (1), those in which the substituents R ^{1 to} R ⁶ all represent methyl groups are methylated melamine compounds and the substituents R ^{1 to} R ⁶ are all What shows a butyl group is called a butylated melamine compound. Among the full-alkyl melamine compounds (B) represented by the formula (1), the substituents R ^{1 to} R ⁶ are methyl groups or butyl groups, and all are methyl groups, or the total Those other than those that are butyl groups are referred to as methyl-butyl mixed alkylated melamine compounds. Of these, methyl / butyl mixed alkylated melamine compounds are preferred because they are excellent in compatibility and reactivity with polyolefin polyols, and are excellent in the effect of suppressing contamination and uneven hardness in the developing roller.

  Further, these full alkyl melamine compounds (B) may exist as a multimer such as a dimer or a trimer in addition to the monomer, or in a mixed state thereof, and the degree of polymerization thereof may be 1 .40 or less is preferable. If the degree of polymerization is 1.40 or less, it is excellent in compatibility and reactivity with polyolefin polyol, and it is possible to impart an excellent contamination suppressing effect and curing unevenness suppressing effect to the developing roller.

  Here, as the degree of polymerization, a value obtained from the number average molecular weight obtained based on the molecular weight distribution obtained by the GPC method and the molecular weight of the monomer can be adopted.

  As such a full alkyl type melamine compound, for example, the following commercially available products (manufactured by Nippon Cytec Industry Co., Ltd.) can be used. Cymel 300, Cymel 301, Cymel 303, Cymel 350, Cymel 267, Cymel 285, Cymel 232, Cymel 235, Cymel 236, Cymel 238, My Coat 506, and the like.

  The polymerization method of the polyolefin polyol (A) and the full alkyl type melamine compound (B) may be any of bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. The method of performing a polymerization reaction can be mentioned. As temperature and time conditions at that time, it is preferable to carry out at 120 to 180 ° C. for 60 to 300 minutes.

  Further, a conductive agent can be used for the surface layer in order to adjust electric resistance. Examples of the conductive agent include the following. Conductive carbon black such as ketjen black and acetylene black. Carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT. Oxidized carbon black for color ink, pyrolytic carbon black, natural graphite, graphite such as artificial graphite. Copper, nickel, iron, aluminum powder. Metal oxide powders such as titanium oxide, zinc oxide and tin oxide. Conductive polymers such as polyaniline, polypyrrole and polyacetylene. These can be used alone or in combination of two or more.

  In the surface layer, the filler, extender, vulcanizing agent, cross-linking agent, vulcanizing auxiliary, cross-linking auxiliary, antioxidant, anti-aging, and the like, as long as the function of the above composition is not impaired. Various additives such as an additive and a processing aid can be contained.

  The surface layer preferably has a thickness of 1 to 500 μm. If the thickness of the surface layer is within this range, contaminants are removed from the surface of the developing roller during image formation, and the occurrence of image defects can be suppressed.

  The surface layer preferably has a center line average roughness Ra satisfying 0.01 μm ≦ Ra ≦ 0.30 μm. When the surface layer has such a center line average roughness, contaminants are removed from the surface of the developing roller during image formation, and the occurrence of image defects can be suppressed.

  Here, the center line surface roughness Ra can be measured by a measurement method according to JIS B0601: 1994, using a surface roughness meter “Surf Coder SE-3400” (manufactured by Kosaka Laboratory Ltd.). . Specifically, the measurement conditions were a stylus with a radius of 2 μm, a pressing pressure of 0.7 mN, a measurement speed of 0.3 mm / sec, a measurement magnification of 5000 times, a cutoff wavelength of 0.8 mm, and a measurement length of 2.5 mm. To do. Measurement points were measured at three points in the circumferential direction with respect to three points in the axial direction (positions 3 cm from the opposite ends of the developing roller and the central portion in the axial direction of the developing roller). The arithmetic average value is defined as the surface roughness Ra. The position in the circumferential direction is arbitrary.

  As a method for forming such a surface roughness, a desired surface roughness can be formed by adding fine particles or a leveling agent contained in the surface layer and adjusting the content thereof. That is, the surface roughness Ra can be increased by increasing the content of the fine particles, and the surface roughness Ra can be decreased by increasing the content of the leveling agent. The amount of the fine particles used is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the resin solid content of the surface layer. Examples of the material of the fine particles include polyurethane resin, polyester resin, polyether resin, polyamide resin, acrylic resin, and polycarbonate resin.

  Specific examples of the developing roller of the present invention include a roller having an elastic layer 3 and a surface layer 4 on a conductive shaft core 2 as shown in FIG. Moreover, as a developing roller of this invention, as shown in FIG. 3, what has the surface layer 4 which functions as an elastic layer on the electroconductive axial core body 2 can be mentioned.

  The developing roller of the present invention may have an elastic layer composed of a plurality of layers made of different materials, or a resin layer having various functions such as easy charging and friction resistance between the elastic layer and the surface layer. It may have.

  Examples of the method for producing the developing roller of the present invention include the following methods. A composition (referred to as an uncured rubber composition) containing an uncured rubber component constituting the elastic layer, a conductivity imparting agent, and other components as required is prepared. Using this uncured rubber composition, an uncured product is formed on the conductive shaft core by an extrusion molding method, a mold molding method, an injection molding method, a coating molding method, etc., and heating, electron beam irradiation It hardens | cures by etc. and shape | molds an elastic layer. In order to improve adhesion to the upper surface layer and suppress peeling, the surface can be polished or modified by a surface modification method such as corona treatment, flame treatment, or excimer treatment.

  After forming the elastic layer, the surface layer is formed. As a method for forming the surface layer, a composition (referred to as an uncured composition) containing the polyolefin polyol (A), the full-alkyl melamine compound (B), and, if necessary, the surface layer material of other components. Prepare. This can be used for polymerization, curing and molding using extrusion molding, mold molding, injection molding, etc., but the coating solution for uncured composition on the elastic layer can be formed by coating molding. The method of forming and hardening a coating film using can be mentioned as a preferable method.

  As the coating molding method, spraying, dipping, roll coating, etc. can be used, and after forming a coating film on the elastic layer, a method of drying this to remove the solvent and heat curing is used. be able to. Specifically, the curing may be any method such as heating or electron beam irradiation, and in the case of heating, it can be set to 120 to 180 ° C., 60 to 300 minutes, or the like.

  When dip coating is used for the coating film formation, as shown in the schematic configuration diagram of FIG. 4, a coating apparatus as described in Japanese Patent Laid-Open No. 57-5047 is used to overflow the paint from the upper end of the dip tank. Is preferable because it is simple and excellent in production stability.

  A dipping tank 25 is provided in the coating apparatus shown in FIG. The dipping bath has a cylindrical shape with an inner diameter slightly larger than the outer diameter of the roller 29 on which the elastic layer is formed and a depth longer than the axial length of the roller 29, and is installed with the axial direction vertical. . An annular liquid receiving portion 30 is provided on the outer periphery of the upper end portion, and the liquid receiving portion is connected to the stirring tank 27 by a pipe 31 connected to the bottom surface. On the other hand, the bottom of the immersion tank 25 is connected to a liquid feed pump 26 that circulates the coating liquid 33 through a pipe 32, and the liquid feed pump 26 and the agitation tank 27 are further connected by a pipe 34. The agitation tank is provided with an agitation blade 35 for agitating the coating solution contained therein.

  This coating apparatus is provided with an elevating device 36 that elevates the elevating plate 28 in the axial direction of the immersing tank in the upper part of the immersing tank, and a roller 29 suspended on the elevating plate 28 can enter and retract into the immersing tank. ing.

  In order to form the surface layer on the elastic layer using such a coating apparatus, the pump 26 is driven, and the coating liquid 33 stored in the stirring tank 27 is supplied to the immersion tank 25 through the pipes 32 and 34. The elevating device 36 is driven to lower the elevating plate 28, and the roller 29 enters the immersion tank filled with the coating liquid 33. The coating liquid overflowing from the upper end of the immersion tank due to the entrance of the roller is received by the liquid receiving portion 30 and returned to the stirring tank 27 through the pipe 31. Thereafter, the elevating device is driven to raise the elevating plate, and the roller 29 is retracted from the immersion tank at a predetermined speed to form a coating film on the elastic layer. During this time, the stirring blade 35 is rotated in the stirring tank to stir the coating solution to suppress sedimentation of the contents and maintain the uniformity of the coating solution.

  After forming the coating film, the roller is removed from the lifting plate 28, the coating film is dried and cured, and the surface layer is formed to obtain the developing roller of the present invention.

  The electrophotographic apparatus of the present invention is characterized in that in the electrophotographic apparatus provided with a developing roller for supplying a developer to the surface of the latent image carrier to form a toner image, the developing roller is the developing roller. As an example, a tandem color electrophotographic apparatus shown in FIG. 5 can be cited. The electrophotographic apparatus shown in the schematic configuration diagram of FIG. 5 includes image forming units a to d that are provided for each color toner such as yellow toner, magenta toner, cyan toner, and black toner. Each image forming unit is provided with a photoreceptor 5 as an electrostatic latent image carrier that rotates in the direction of the arrow. Around each photoconductor, a charging device 12 for uniformly charging the photoconductor, exposure means for irradiating the uniformly charged photoconductor with a laser beam 11 to form an electrostatic latent image, electrostatic A developing device 8 is provided that supplies toner to the photosensitive member on which the latent image is formed to develop the electrostatic latent image. On the other hand, a transport belt 20 that transports a transfer material 22 such as paper supplied by a paper feed roller 23 is provided suspended from a drive roller 16, a driven roller 21, and a tension roller 19. A charge from a bias power source 18 is applied to the transport belt through a roller 24 so that the transfer material 22 is electrostatically attached to the surface and transported.

  Each image forming unit is provided with a transfer bias power source 17a for applying a charge for transferring the visualized toner image on the photoreceptor onto the transfer material 22 conveyed by the conveyance belt 20. The transfer bias power source is applied to the back surface of the transfer material via the transfer roller 17, and the toner image of each color formed in each image forming unit on the transfer material transported by the transport belt that is moved in synchronization with the image forming unit. Are sequentially superimposed and transferred.

  Further, the color electrophotographic image forming apparatus includes a peeling device 14 for peeling the transfer material adhering to the conveying belt 20, a fixing device 15 for fixing the toner image superimposed and transferred on the transfer material by heating, and an image-formed transfer. A conveying device (not shown) for discharging the material out of the device is provided.

  On the other hand, each image forming unit is provided with a cleaning device 13 having a cleaning blade that removes a transfer residual developer that remains without being transferred onto each photoconductor and cleans the surface, and other developments scraped off from the photoconductor. A waste developer container or the like for storing the agent is provided. The cleaned photoconductor is set in an image-formable state and stands by.

  The developing device 8 provided in each of the image forming units is provided with a developer container containing non-magnetic toner 8 as a one-component toner, and a portion exposed from the developer container so as to close the opening of the developer container. The developing roller 6 is provided so as to face the photoconductor. In the developer container, the toner is supplied to the developing roller, and at the same time, the toner on the developing roller is scraped away from the toner that is not used, and the toner on the developing roller is formed into a thin film and is triboelectrically charged. Toner regulating member 9 is provided. As the toner supply roller, for example, a foamed sponge body or polyurethane foam on a shaft core body, a fur brush structure in which fibers such as rayon or polyamide are planted, etc. are provided on the developing roller after development. This is preferable because it facilitates the removal of residual toner.

  The electrophotographic process cartridge of the present invention further includes a developing roller that supplies a developer to the surface of the latent image carrier to form a toner image, and the developing roller is detachable from the electrophotographic apparatus, and the developing roller is the above-described developing roller. It is a roller. One example is the electrophotographic process cartridge shown in FIG. The electrophotographic process cartridge shown in the schematic configuration diagram of FIG. 6 includes a developing device 10, a photoreceptor 5, and a cleaning member 14, which are integrally held and detachably provided in the electrophotographic apparatus. Examples of the developing device 10 include the same ones as described above. In addition to the above, the electrophotographic process cartridge of the present invention is integrated with a transfer member for transferring a toner image on a photosensitive member to a transfer material together with the above member or with one or more of the above members. It may be provided.

  Hereinafter, the developing roller, the electrophotographic process cartridge, and the electrophotographic image forming apparatus of the present invention will be described in detail, but the technical scope of the present invention is not limited thereto. Hereinafter, unless otherwise specified, “parts” means “parts by mass”.

[Example 1]
[Production of elastic layer]
A conductive shaft core made of SUS304 having an outer diameter of 8 mm and a length of 280 mm was placed concentrically in a cylindrical mold having an inner diameter of 16 mm, and the pieces on both ends were fixed at a pressure of 0.3 MPa. Liquid conductive silicone rubber (manufactured by Toray Dow Silicone Co., Ltd.) (AskerC hardness 50 degrees, volume resistivity 10 ⁶ Ωcm) is cast, placed in an oven at 130 ° C. and heat-molded for 20 minutes, and after demolding, in an oven at 200 ° C. Secondary vulcanization was performed for 2 hours to produce an elastic layer having a thickness of 4 mm.

[Preparation of polyolefin polyol]
The following materials were mixed in a stainless steel pressure vessel equipped with a stirrer and stirred at a temperature of 70 ° C. and a pressure of 12 kgf / cm ² for polymerization.
1,3-butadiene: 100 parts 2,2′-azobis (2-methyl-N- (1,1-bis (hydroxymethyl) ethyl) propionamide) as a polymerization initiator: 12 parts ethanol / toluene (mass ratio 65) / 35): 300 parts.

Then, 2 parts of toluene containing 4-t-butyl alcohol was added to terminate the polymerization. The obtained polymerization product was reprecipitated three times in a large excess of methanol, and then light low-boiling components were distilled off for 2 hours at 100 ° C./2 mmHg to obtain purified polymers A to E. .
Polybutadiene polyol A (number average molecular weight Mn = 3000, dispersity Mw / Mn = 2.49)
Polybutadiene polyol B (number average molecular weight Mn = 8600, dispersity Mw / Mn = 2.21)
Polybutadiene polyol C (number average molecular weight Mn = 23800, dispersity Mw / Mn = 2.55)
Polybutadiene polyol D (number average molecular weight Mn = 49000, dispersity Mw / Mn = 2.67)
Polybutadiene polyol E (number average molecular weight Mn = 61200, dispersity Mw / Mn = 2.72)
In the same manner as described above, the following polyisoprene polyols A and B having different molecular weights were obtained using isoprene as a raw material.
Polyisoprene polyol A (number average molecular weight Mn = 3200, dispersity Mw / Mn = 2.53)
Polyisoprene polyol B (number average molecular weight Mn = 50000, dispersity / 66)
The obtained polybutadiene polyol was mixed in the ratio shown in Table 1 to prepare polybutadiene polyols 1 to 12 and H1. When the polybutadiene polyol 1 was measured by the GPC method, it had a number average molecular weight Mn of 5700, a degree of dispersion Mw / Mn of 12.50, and two peaks. The results are shown in Table 2.

[Production of surface layer]
The following materials were dissolved and mixed in MEK so as to have a total solid content ratio of 30%, and uniformly dispersed by a sand mill to prepare a coating material.
Polybutadiene polyol 1:80 parts.
Cymel 235 (manufactured by Nippon Cytec Industry Co., Ltd.) (polymerization degree 1.40): 2 parts as methyl / butyl mixed alkylated melamine compound.
Carbon black (Toka Black # 7360SB, manufactured by Tokai Carbon): 16 parts by mass.
Alkylbenzenesulfonic acid catalyst: 1 part.

  The obtained paint is applied on the previously formed elastic layer so as to have a film thickness of 20 μm using the coating apparatus shown in FIG. 4, dried in an oven at 80 ° C. for 15 minutes, and then at 140 ° C. for 2 hours. The surface layer was produced by heating.

[Image evaluation]
The obtained developing roller was mounted on the electrophotographic process cartridge shown in FIG. 6 and left in an environment of 40 ° C./95% RH for 14 days. Next, the cartridge was allowed to stand at 23 ° C. and 55% RH for 1 day, and then mounted on the electrophotographic apparatus shown in FIG. 5 to output a full color image. Image defects such as horizontal banding that occurs in the photoconductor cycle (caused by photoconductor contamination due to exudate from the developing roller), and image defects such as horizontal banding and fogging that occur in the developing roller cycle (due to contamination of the developing roller by other members) Occurrence) was evaluated according to the following criteria. The results are shown in Table 2.
A: No image defect is observed.
B: Occurrence of an extremely minor image defect that is difficult to discern.
C: Minor image defects are observed.
D: The occurrence of an image defect affecting the image is observed.

  Further, after leaving in an environment of 15 ° C./10% RH for 1 day, 25,000 images with a printing rate of 1% were output and the fogging was measured. The fog was measured as follows. (1) Stop the electrophotographic apparatus while outputting a solid white image. (2) The toner adhering to the photoconductor is peeled off with a transparent tape and pasted on white paper (Business Multipurpose 4200: manufactured by XEROX). (3) The reflection density is measured with a reflection densitometer (TC-6DS / A, manufactured by Tokyo Denshoku Co., Ltd.). (4) The reflection density measured by attaching only the tape to white paper is used as a reference, and the decrease (difference) in reflectance with respect to the reference is used as the fogging value.

  In general, a fog density exceeding 3.0 is recognized as an image defect and an influence on the image is recognized. The results are shown in Table 2.

[Examples 2 to 11]
A developing roller was produced in the same manner as in Example 1 except that the polybutadiene polyols 2 to 11 shown in Table 1 were used instead of the polybutadiene polyol 1, and image evaluation was performed. The results are shown in Table 2.

[Example 12]
Instead of 20 parts of Cymel 235 (manufactured by Nippon Cytec Industry Co., Ltd.), 20 parts of Mycoat 506 (manufactured by Nippon Cytec Industry Co., Ltd.) (degree of polymerization 2.20) was used as a butylated melamine compound. Otherwise, a developing roller was prepared in the same manner as in Example 1, and image evaluation was performed. The results are shown in Table 2.

[Example 13]
In place of 20 parts of Cymel 235 (manufactured by Nippon Cytec Industry Co., Ltd.), 20 parts of Cymel 232 (manufactured by Nippon Cytec Industry Co., Ltd.) (polymerization degree 1.50) was used as a methyl / butyl mixed alkylated melamine compound. Otherwise, a developing roller was prepared in the same manner as in Example 1, and image evaluation was performed. The results are shown in Table 2.

[Example 14]
In place of 20 parts of Cymel 235 (manufactured by Nippon Cytec Industry Co., Ltd.), 20 parts of Cymel 303 (manufactured by Nippon Cytec Industry Co., Ltd.) (degree of polymerization 1.50) was used as a methylated melamine compound. Otherwise, a developing roller was prepared in the same manner as in Example 1, and image evaluation was performed. The results are shown in Table 2.

[Example 15]
Polyisoprene polyol A and polyisoprene polyol B were mixed in the same mass part to prepare polyisoprene polyol 1. When polyisoprene polyol 1 was measured by the GPC method, it had a number average molecular weight Mn of 5800, a degree of dispersion Mw / Mn of 12.22, and two peaks. The results are shown in Table 2.

  A developing roller was produced in the same manner as in Example 1 except that polyisoprene polyol 1 was used instead of polybutadiene polyol 1, and image evaluation was performed. The results are shown in Table 2.

[Example 16]
A developing roller was prepared and image evaluation was performed in the same manner as in Example 1 except that 5 parts of urethane resin fine particles (Bernock CFB100: manufactured by Dainippon Ink Co., Ltd.) were added to the coating material for forming the surface layer. The results are shown in Table 2.

[Example 17]
A developing roller was produced in the same manner as in Example 1 except that 0.2 part of BYK-310 (manufactured by Big Chemie Japan) was added as a leveling agent to the coating material for forming the surface layer, and image evaluation was performed. The results are shown in Table 2.

[Example 18]
A developing roller was prepared in the same manner as in Example 1 except that the polybutadiene polyol 12 shown in Table 1 was used instead of the polybutadiene polyol 1, and image evaluation was performed. The results are shown in Table 2.

[Comparative Example 1]
Polybutadiene polyol 1A was used instead of polybutadiene polyol 1, and 20 parts of Cymel 235 (manufactured by Nippon Cytec Industry Co., Ltd.) and 16 parts of carbon black (Toka Black # 7360SB, manufactured by Tokai Carbon Co., Ltd.) were used. Otherwise, a developing roller was prepared in the same manner as in Example 1, and image evaluation was performed. The results are shown in Table 2.

[Comparative Example 2]
Polybutadiene polyol B was used in place of polybutadiene polyol 1, and 20 parts of Cymel 235 (manufactured by Nippon Cytec Industry Co., Ltd.) and 16 parts of carbon black (Toka Black # 7360SB, manufactured by Tokai Carbon Co., Ltd.) were used. Otherwise, a developing roller was prepared in the same manner as in Example 1, and image evaluation was performed. The results are shown in Table 2.

[Comparative Example 3]
Instead of polybutadiene polyol 1, polybutadiene polyol D was used, and 20 parts of Cymel 235 (manufactured by Nippon Cytec Industry Co., Ltd.) and 16 parts of carbon black (Toka Black # 7360SB, manufactured by Tokai Carbon Co., Ltd.) were used. Otherwise, a developing roller was prepared in the same manner as in Example 1, and image evaluation was performed. The results are shown in Table 2.

[Comparative Example 4]
A developing roller was produced in the same manner as in Example 1 except that polybutadiene polyol H1 was used instead of polybutadiene polyol 1, and image evaluation was performed. The results are shown in Table 2.

[Comparative Example 5]
Instead of 20 parts of Cymel 235 (manufactured by Nippon Cytec Industry Co., Ltd.), 20 parts of Cymel 325 (manufactured by Nippon Cytec Industry Co., Ltd.) (polymerization degree 2.30) was used as an imino-type melamine resin. Moreover, 16 parts of carbon black (Toka Black # 7360SB, manufactured by Tokai Carbon Co., Ltd.) was used. Otherwise, a developing roller was prepared in the same manner as in Example 1, and image evaluation was performed. The results are shown in Table 2.

[Comparative Example 6]
Use 20 parts of isocyanate (Coronate HL: made by Nippon Polyurethane Co., Ltd.) and 16 parts of carbon black (Toka Black # 7360SB, Tokai Carbon Co., Ltd.) instead of 20 parts of Cymel 235 (made by Nippon Cytec Industry Co., Ltd.) did. Otherwise, a developing roller was prepared in the same manner as in Example 1, and image evaluation was performed. The results are shown in Table 2.

Bu/Me：メチル・ブチル混合アルキル化メラミン化合物
Bu：ブチル化メラミン化合物
Me：メチル化メラミン化合物
結果からも、本発明の現像ローラーを用いることにより、感光体の汚染が抑制され、現像ローラー自体の汚染も抑制されることが明らかである。

Bu / Me: methyl and butyl mixed alkylated melamine compounds
Bu: Butylated melamine compound
Me: Methylated melamine compound From the results, it is clear that by using the developing roller of the present invention, the contamination of the photoreceptor is suppressed and the contamination of the developing roller itself is also suppressed.

It is a figure which shows the characteristic of polyolefin polyol (A) contained in the surface layer of the image development roller of this invention. It is a schematic block diagram which shows an example of the developing roller of this invention. It is a schematic block diagram which shows another example of the developing roller of this invention. It is a schematic block diagram which shows an example of the manufacturing apparatus of the developing roller of this invention. 1 is a schematic configuration diagram showing an electrophotographic apparatus of the present invention. 1 is a schematic configuration diagram illustrating an example of an electrophotographic process cartridge of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 6 Developing roller 2 Conductive shaft core 3 Elastic layer 4 Surface layer 5 Photoconductor 7 Toner supply roller 8 Toner 9 Toner amount regulating member 10 Developing device 11 Laser beam 12 Charging device 13 Cleaning device 15 Fixing device 16 Driving roller 17 Transfer roller 17a Transfer bias power supply 18 Bias power supply 19 Tension roller 20 Conveyor belt 21 Driven roller 22 Transfer material 23 Paper feed roller 24 Roller 25 Immersion tank 26 Liquid feed pump 27 Stirring tank 28 Lifting device

Claims (11)

  In a developing roller having an elastic layer on a conductive shaft core, the number average molecular weight Mn based on the molecular weight distribution obtained by the GPC method is 3000 ≦ Mn ≦ 15000 and the degree of dispersion Mw / Mn is 2.80 ≦ Mw on the surface. A developing roller having a surface layer containing a polymer obtained by polymerizing a polyolefin polyol (A) satisfying /Mn≦12.50 and a full alkyl melamine compound (B).   2. The developing roller according to claim 1, wherein the polyolefin polyol (A) has two or more peaks between 3000 and 15000 in the molecular weight distribution curve obtained by the GPC method.   The ratio (Imax) / (Imin) of the peak intensity (Imax) at the maximum molecular weight and the peak intensity (Imin) at the minimum molecular weight among the peaks between molecular weights 3000 and 15000 in the molecular weight distribution curve obtained by the GPC method is The developing roller according to claim 2, wherein 0.5 ≦ (Imax) / (Imin) ≦ 2.0.   The polyolefin polyol (A) contains the polyolefin polyol (a1) and the polyolefin polyol (a2), and the polyolefin polyol (a1) and the polyolefin polyol (a2) have the same repeating unit and are obtained by the GPC method. The developing roller according to claim 1, wherein the number average molecular weight based on the distribution is different.   The developing roller according to claim 1, wherein the polyolefin polyol (A) contains a polybutadiene polyol.   6. The developing roller according to claim 1, wherein the full alkyl type melamine compound (B) contains a methyl / butyl mixed alkylated melamine compound.   The developing roller according to claim 1, wherein the degree of polymerization of the full alkyl melamine compound (B) is 1.40 or less.   8. The developing roller according to claim 1, wherein the center line average roughness Ra of the surface satisfies 0.01 μm ≦ Ra ≦ 0.30 μm. 9.   The developing roller according to claim 1, wherein the elastic layer is a surface layer.   An electrophotographic process cartridge that includes a developing roller that supplies a developer to the surface of the latent image carrier to form a toner image, and is detachable from the electrophotographic apparatus, wherein the developing roller is the developing roller according to claim 1. An electrophotographic process cartridge comprising:   An electrophotographic apparatus comprising a developing roller for supplying a developer to the surface of the latent image carrier to form a toner image, wherein the developing roller is the developing roller according to any one of claims 1 to 9. apparatus.

Images