JP2005352120A - Electrifying roller and image forming apparatus equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrifying roller whose elastic layer is principally composed of a non-foaming body, which does not require a long drying line for mass production, and which is equipped with a stable-quality resin covering layer on the outer surface of the elastic layer, and an image forming apparatus equipped with the electrifying roller and stably forming an excellent image. <P>SOLUTION: The electrifying roller 1 is equipped with a shaft 2, the elastic layer 3 made of the non-foaming body, which is formed on the circumference of the shaft 2, and at least one resin covering layer 4 formed on the circumferential surface of the elastic layer 3 made of the non-foaming body, and the resin covering layer 4 contains ultraviolet curing type resin. The image forming apparatus is equipped with the electrifying roller 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a charging roller and an image forming apparatus including the charging roller, and more particularly to a charging roller used in an image forming apparatus such as an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus.

  In an electrophotographic image forming apparatus such as a copying machine or a printer, as a developing method for visualizing a latent image by supplying toner to a photosensitive drum or the like holding a latent image and attaching the toner to the latent image on the photosensitive drum. A pressure development method is known. In the pressure development method, for example, after the photosensitive drum is charged to a constant potential, an electrostatic latent image is formed on the photosensitive drum by an exposure machine, and further, a developing roller carrying toner is placed on the electrostatic latent image. Development is performed by bringing the toner into contact with the latent image on the photosensitive drum in contact with the held photosensitive drum.

  Conventionally, a corona discharge method has been employed for charging the photosensitive drum. However, in the corona discharge method, it is necessary to apply a high voltage of 6 to 10 kV, which is not preferable from the viewpoint of ensuring the safety of the apparatus. In addition, since harmful substances such as ozone are generated during corona discharge, it is not preferable from the viewpoint of the environment. On the other hand, a contact charging method has been proposed in which a charging roller is brought into contact with the photosensitive drum and a voltage is applied between the photosensitive drum and the charging roller to charge the photosensitive drum.

  In the above contact charging system, the charging roller must be rotated while being securely held in close contact with the photosensitive drum. Therefore, silicone rubber, acrylonitrile-butadiene rubber is provided on the outer periphery of the shaft made of a highly conductive material such as metal. (NBR), ethylene-propylene-diene rubber (EPDM), epichlorohydrin rubber (ECO), a semiconductive elastic body in which carbon black or metal powder is dispersed in an elastomer such as polyurethane, and a foam obtained by foaming these. The semiconductive elastic layer is formed. Further, a resin coating layer may be further formed on the surface of the elastic layer for the purpose of ensuring the smoothness of the surface of the charging roller and preventing the toner from adhering to the surface of the charging roller.

  Conventionally, the resin coating layer is formed by dipping the charging roller body into a solvent-based or aqueous coating liquid or spraying the coating liquid onto the charging roller body, and then heating / drying with heat or hot air. In this case, however, a long drying line is necessary for mass production because long drying is required. In addition, the resin coating layer is required to have subtle electrical conductivity and surface condition depending on its use, but the quality distribution is affected by variations in temperature distribution and air volume in the drying line, which greatly affects the performance of the resin coating layer. There was a problem.

  On the other hand, as a method for forming a stable quality resin coating layer without requiring a long drying line, an ultraviolet curable resin is applied to the surface of the elastic layer of the foam roller and cured to form the resin coating layer. A technique has been proposed (see Patent Document 1).

JP 2002-310136 A

  However, in the foam roller in which the resin coating layer containing the ultraviolet curable resin is disposed on the outer peripheral surface of the elastic layer, the elastic layer is made of a foam, but even when the elastic layer is a non-foam, Similarly, when a resin coating layer is formed by heating / drying with heat or hot air, a long drying line is required for mass production, and variations in the temperature distribution and air volume in the drying line are the performance of the resin coating layer. As a result, there was a quality problem.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, the elastic layer is mainly made of non-foamed material, does not require a long drying line for mass production, and has a stable quality resin coating layer on the outer surface of the elastic layer. It is providing the charging roller provided with. Another object of the present invention is to provide an image forming apparatus provided with such a charging roller and capable of stably forming excellent images.

  As a result of intensive studies to achieve the above object, the present inventors have used an ultraviolet curable resin for the resin coating layer in the charging roller in which the resin coating layer is provided on the surface of the non-foamed elastic layer. As a result, it has been found that a long drying line is not required for mass production, and that variations in the performance of the resin coating layer due to variations in temperature distribution and air flow in the drying line can be eliminated, and the present invention has been completed.

  That is, the charging roller of the present invention includes a shaft, a non-foamed elastic layer formed on the outer periphery of the shaft, and at least one resin coating layer formed on the outer peripheral surface of the non-foamed elastic layer. The charging roller is characterized in that the resin coating layer contains an ultraviolet curable resin. Here, the ultraviolet curable resin is obtained by curing a resin and / or compound polymerizable by ultraviolet rays by ultraviolet irradiation.

  In a preferred example of the charging roller of the present invention, the resin coating layer is coated with a coating solution containing a resin and / or compound polymerizable by ultraviolet rays on the outer peripheral surface of the non-foamed elastic layer, and then irradiated with ultraviolet rays. The resin and / or compound that can be polymerized by ultraviolet rays is cured by the above. Here, the coating liquid preferably contains a photopolymerization initiator.

  In the charging roller of the present invention, the resin and / or compound that can be polymerized by ultraviolet rays is preferably a resin and / or compound that has a double bond between carbon atoms that can be polymerized by ultraviolet rays. Here, as the resin and / or compound having a double bond between carbon atoms that can be polymerized by ultraviolet rays, a (meth) acrylate monomer and an oligomer are preferable.

  The image forming apparatus of the present invention includes at least a charging roller, and the charging roller is the charging roller.

  According to the present invention, in a charging roller in which a resin coating layer is disposed on the surface of a non-foamed elastic layer, a long drying line is required for mass production by using an ultraviolet curable resin for the resin coating layer. In addition, a charging roller having a stable quality resin coating layer can be provided. Further, it is possible to provide an image forming apparatus that includes such a charging roller and can stably form an excellent image.

  Hereinafter, the charging roller of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an example of the charging roller of the present invention. The charging roller 1 in the illustrated example includes a shaft 2, a non-foamed elastic layer 3 formed on the outer periphery of the shaft 2, and a resin coating layer 4 formed on the outer peripheral surface of the non-foamed elastic layer 3. Prepare. In the figure, the resin coating layer 4 is composed of one layer, but the resin coating layer 4 of the charging roller of the present invention may be composed of two or more layers.

  In the charging roller 1 of the present invention, since the resin coating layer 4 is mainly composed of an ultraviolet curable resin, it is not necessary to dry the resin coating layer 4 for a long time, and it is necessary to prepare a long drying line for mass production. Disappear. That is, the resin coating layer 4 of the charging roller 1 of the present invention is applied with, for example, a coating liquid containing a resin and / or compound polymerizable by ultraviolet rays on the outer surface of the non-foamed elastic layer 3 and then irradiated with ultraviolet rays. In addition, since the resin and / or compound that can be polymerized by ultraviolet rays are cured, a drying process is not essential, and further, the resin coating layer 4 is formed at the stage of irradiation with ultraviolet rays. Variations in the performance of the resin coating layer 4 due to variations in temperature distribution and air volume in the line can be eliminated.

  The shaft of the charging roller of the present invention is not particularly limited as long as it has good conductivity. For example, a metal core made of a metal such as iron, stainless steel, or aluminum, or a metal hollowed inside A metal shaft such as a cylindrical body can be used.

  The non-foamed elastic layer of the charging roller of the present invention contains a non-foamed elastomer and a conductive agent, and optionally contains other components such as a filler. As the elastomer used for the non-foamed elastic layer, silicone rubber, ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), natural rubber, styrene-butadiene rubber (SBR), butyl rubber, chloroprene rubber, acrylic rubber , Epichlorohydrin rubber (ECO), ethylene-vinyl acetate copolymer (EVA), polyurethane, and a mixture thereof. Among these, silicone rubber, EPDM, ECO, and polyurethane are preferable.

  The shaft and the non-foamed elastic layer may be integrated using a reaction injection molding method (RIM molding method). That is, two types of monomer components constituting the raw material component of the non-foamed elastic layer can be mixed and injected into a cylindrical mold and polymerized to integrate the shaft and the elastic layer. As a result, the time required from injection of raw materials to demolding can be shortened, and production costs can be greatly reduced.

  When silicone rubber is used for the non-foamed elastic layer, the silicone rubber may be general millable silicone rubber (HCR) or liquid silicone rubber (LSR). In addition, when using liquid silicone rubber, it is preferable to form the non-foamed elastic layer by liquid injection molding (LIM). The above liquid silicone rubber contains vinyl group-containing polyorganosiloxane with organohydrogenpolysiloxane, reinforcing filler such as silica, conductive agent, platinum-based catalyst, reaction inhibitor, silicone oil, and other various additives. After being injected into a mold having a predetermined shape, it is molded by heat curing.

（式中、Ｒ¹は、それぞれ独立して一価の炭化水素基であり、ｎは100〜10,000の整数である）で表される化合物が好ましい。ここで、Ｒ¹における、一価の炭化水素基としては、メチル基、エチル基、プロピル基、ブチル基及びペンチル基等のアルキル基、ビニル基及びアリル基等のアルケニル基、シクロヘキシル基等のシクロアルキル基、フェニル基等のアリール基、ベンジル基等のアラルキル基等が挙げられる。 The vinyl group-containing polyorganosiloxane has two or more reactive groups in the molecule, and examples of the reactive group include an alkenyl group and a hydroxyl group. As the vinyl group-containing polyorganosiloxane, the following formula (I):

In the formula, R ¹ is each independently a monovalent hydrocarbon group, and n is an integer of 100 to 10,000. Here, the monovalent hydrocarbon group in R ¹ includes an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group and a pentyl group, an alkenyl group such as a vinyl group and an allyl group, and a cyclohexyl group such as a cyclohexyl group. Examples include alkyl groups, aryl groups such as phenyl groups, and aralkyl groups such as benzyl groups.

（式中、Ｒ²は、それぞれ独立して水素又は一価の炭化水素基であり、ｍは10〜1,000の整数である）で表され、分子中に２個以上のケイ素−水素結合を有する化合物が好ましい。ここで、Ｒ²における、一価の炭化水素基としては、メチル基、エチル基、プロピル基、ブチル基及びペンチル基等のアルキル基、ビニル基及びアリル基等のアルケニル基、シクロヘキシル基等のシクロアルキル基、フェニル基等のアリール基、ベンジル基等のアラルキル基等が挙げられる。 Examples of the organohydrogenpolysiloxane include the following formula (II):

(Wherein R ² is each independently hydrogen or a monovalent hydrocarbon group, m is an integer of 10 to 1,000), and has two or more silicon-hydrogen bonds in the molecule. Compounds are preferred. Here, the monovalent hydrocarbon group in R ² includes alkyl groups such as methyl group, ethyl group, propyl group, butyl group and pentyl group, alkenyl groups such as vinyl group and allyl group, and cyclohexane such as cyclohexyl group. Examples include alkyl groups, aryl groups such as phenyl groups, and aralkyl groups such as benzyl groups.

  In addition, as a conductive agent contained in the liquid silicone rubber, a conductive agent generally used for an elastic layer to be described later can be used. As a platinum-based catalyst, platinous chloride, chloroplatinic acid, alcohol-modified chloroplatinic acid can be used. Examples of the reaction inhibitor include methylvinylcyclotetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, hydroperoxide and the like.

  Examples of the conductive agent used for the non-foamed elastic layer include an electronic conductive agent and an ionic conductive agent. Electronic conductive agents include conductive carbon such as ketjen black and acetylene black, carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT and MT, and carbon black for color subjected to oxidation treatment. , Pyrolytic carbon black, natural graphite, artificial graphite, antimony-doped tin oxide, ITO, tin oxide, titanium oxide, zinc oxide and other metal oxides, nickel, copper, silver, germanium and other metals, polyaniline, polypyrrole, polyacetylene, etc. And conductive whiskers such as carbon whisker, graphite whisker, titanium carbide whisker, conductive potassium titanate whisker, conductive barium titanate whisker, conductive titanium oxide whisker, and conductive zinc oxide whisker. The blending amount of the electronic conductive agent is preferably in the range of 1 to 50 parts by mass, more preferably in the range of 5 to 40 parts by mass with respect to 100 parts by mass of the elastomer.

  Examples of the ionic conductive agent include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, modified fatty acid dimethylethylammonium, perchlorate, chlorate, hydrochloride, bromate, and the like. Ammonium salts such as salts, iodates, borofluorides, sulfates, ethyl sulfates, carboxylates, sulfonates; alkaline metals such as lithium, sodium, potassium, calcium, magnesium, alkaline earth metals Examples include perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, trifluoromethyl sulfate, and sulfonate. The compounding amount of the ionic conductive agent is preferably in the range of 0.01 to 10 parts by mass, more preferably in the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the elastomer. The said electrically conductive agent may be used individually by 1 type, may be used in combination of 2 or more type, and may combine an electronic conductive agent and an ionic conductive agent.

The resistance value of the non-foamed elastic layer is preferably 10 ³ to 10 ¹⁰ Ωcm, and more preferably 10 ⁴ to 10 ⁸ Ωcm, depending on the blending of the conductive agent.

  The non-foamed elastic layer may contain a crosslinking agent such as an organic peroxide and a vulcanizing agent such as sulfur in order to make the elastomer a rubbery material as necessary. An agent, a vulcanization accelerator, a vulcanization acceleration aid, a vulcanization retarder and the like may be contained. The non-foamed elastic layer further includes a filler, a peptizer, a foaming agent, a plasticizer, a softener, a tackifier, an anti-tacking agent, a separating agent, a release agent, an extender, a colorant, and the like. The rubber compounding agent may be contained.

  The hardness of the non-foamed elastic layer is not particularly limited, but is preferably 80 degrees or less in terms of Asker C hardness, more preferably 20 to 70 degrees. The surface roughness of the non-foamed elastic layer is not particularly limited, but the JIS 10-point average roughness (Rz) is preferably 30 μm or less, more preferably 1 to 20 μm. preferable.

The resin coating layer of the charging roller of the present invention contains an ultraviolet curable resin. The resin coating layer may be formed by, for example, applying a coating liquid containing a resin and / or compound polymerizable by ultraviolet rays to the outer surface of the non-foamed elastic layer, and then irradiating with ultraviolet rays to polymerize the resin polymerizable by ultraviolet rays and It is formed by curing the compound. In general, by providing a resin coating layer on the outer surface of the elastic layer, the resistance value can be adjusted, toner adhesion can be prevented, and the image quality can be improved. It is not necessary to prepare a long drying line for the formation of the resin coating layer, and the resin coating layer is caused by variations in various conditions of the drying process. Variations in characteristics can be eliminated. Here, the coating liquid preferably contains a reactive diluent, a conductive agent, a photopolymerization initiator, and a photopolymerization accelerator, and may contain other known additives as required. Is preferably not included. Examples of the method for applying the coating liquid to the surface of the non-foamed elastic layer include a spray method, a roll coater method, a dipping method, and the like. Examples of the light source used for ultraviolet irradiation include a mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, and a xenon lamp. The conditions for ultraviolet irradiation are appropriately selected according to the type and application amount of the ultraviolet curable resin. For example, the irradiation intensity is preferably in the range of 100 to 700 mW / cm ² and the integrated light quantity of 200 to 3000 mJ / cm ² .

  Examples of the ultraviolet curable resin used for the resin coating layer include polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, alkyd resin, phenol resin, and melamine resin. , Urea resins, silicone resins, polyvinyl butyral resins, vinyl ether resins, vinyl ester resins, and modified resins having specific functional groups introduced into these resins. These resins may be used alone or in combination of two or more. May be used. Moreover, it is preferable to introduce a crosslinked structure into the resin coating layer in order to improve mechanical strength and environmental resistance.

  The ultraviolet curable resin is obtained by curing a resin and / or compound that can be polymerized by ultraviolet rays, preferably a resin and / or compound having a double bond between carbon atoms that can be polymerized by ultraviolet rays. In addition, the resin and / or compound that can be polymerized by ultraviolet rays may be used alone or in combination of two or more.

  As the resin and / or compound having a polymerizable double bond between carbon atoms used for forming the ultraviolet curable resin, a (meth) acrylate monomer and an oligomer are preferable. Here, as the (meth) acrylate monomer and oligomer, urethane (meth) acrylate, epoxy (meth) acrylate, ether (meth) acrylate, ester (meth) acrylate, polycarbonate (meth) acrylate, fluorine-based Examples thereof include monomers and oligomers such as (meth) acrylate and silicone-based (meth) acrylate. The (meth) acrylate oligomer includes polyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, bisphenol A type epoxy resin, phenol novolac type epoxy resin, adduct of polyhydric alcohol and ε-caprolactone, and the like (meth) It can be synthesized by reaction with acrylic acid or by urethanizing a polyisocyanate compound and a (meth) acrylate compound having a hydroxyl group.

  The urethane-based (meth) acrylate oligomer can be obtained by urethanization of a polyol, an isocyanate compound and a (meth) acrylate compound having a hydroxyl group. The epoxy-based (meth) acrylate oligomer is preferably a reaction product of a compound having a glycidyl group and (meth) acrylic acid, such as a benzene ring, naphthalene ring, spiro ring, dicyclopentadiene, tricyclodecane, etc. A reaction product of a compound having a cyclic structure and having a glycidyl group and (meth) acrylic acid is more preferable. Furthermore, the ether-based (meth) acrylate oligomer, the ester-based (meth) acrylate oligomer, and the polycarbonate-based (meth) acrylate oligomer are a polyol (polyether polyol, polyester polyol, and polycarbonate polyol) and (meth) acrylic acid for each. Obtained by reaction.

  Various additives such as a reactive diluent having a polymerizable double bond and a conductive agent may be further blended in the coating liquid used for forming the resin coating layer, if necessary. By blending a reactive diluent having a polymerizable double bond into the coating solution, the viscosity of the coating solution can be adjusted. As the reactive diluent, a monofunctional, bifunctional or polyfunctional polymerizable compound having a structure in which (meth) acrylic acid is bonded to a compound containing an amino acid or a hydroxyl group by an esterification reaction or an amidation reaction is used. be able to. The compounding amount of the reactive diluent is preferably in the range of 10 to 200 parts by mass with respect to a total of 100 parts by mass of the resin and compound polymerizable by the ultraviolet rays. In addition to the above reactive diluents, alcohols, esters, ethers, aliphatic and aromatic organic solvents, or water may be used alone or in combination as a diluent as necessary.

  In addition, examples of the conductive agent used in the coating liquid include the same ones exemplified as the conductive agent for the elastic layer, and among them, a carbon-based electronic conductive agent, an ionic conductive agent, and a transparent conductive material. Agents are preferred. Carbon-based electronic conductive agents include conductive carbons such as ketjen black and acetylene black, carbon blacks for rubbers such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, and colors that have undergone oxidation treatment, etc. Examples thereof include carbon black, pyrolytic carbon black, natural graphite, and artificial graphite. In addition, as the transparent conductive agent, fine particles of metal oxide such as ITO, tin oxide, titanium oxide, and zinc oxide; fine particles of metal such as nickel, copper, silver, germanium: conductive titanium oxide whisker, conductive barium titanate Examples thereof include conductive whiskers such as whiskers. The blending amount of the transparent conductive agent is preferably 100 parts by mass or less, more preferably in the range of 1 to 80 parts by mass, and more preferably in the range of 10 to 50 parts by mass with respect to 100 parts by mass of the resin and compound polymerizable by the ultraviolet rays. A range is even more preferred. On the other hand, the blending amount of the ionic conductive agent is preferably 20 parts by mass or less, more preferably in the range of 0.01 to 20 parts by mass, and 1 to 10 parts by mass with respect to 100 parts by mass in total of the resin and compound polymerizable by the ultraviolet rays The range of part is even more preferable.

  It is preferable to mix a photopolymerization initiator in the coating solution used for forming the resin coating layer. As the photopolymerization initiator, known ones can be used. For example, 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, 2,2-dimethoxy-2-phenylacetophenone, acetophenone diethyl ketal, Benzophenone derivatives such as alkoxyacetophenone, benzyldimethyl ketal, benzophenone and 3,3-dimethyl-4-methoxybenzophenone, 4,4-dimethoxybenzophenone, 4,4-diaminobenzophenone, alkyl benzoylbenzoate, bis (4-dialkylaminophenyl) ) Ketones, benzyl derivatives such as benzyl and benzylmethyl ketal, benzoin derivatives such as benzoin and benzoin isobutyl ether, benzoin isopropyl ether, 2-hydroxy-2-methylpropiophenone, 1-hydroxy Chlohexyl phenyl ketone, xanthone, thioxanthone and thioxanthone derivatives, fluorene, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2 , 4,6-Trimethylbenzoyl) -phenylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1,2-benzyl-2-dimethylamino-1- (morpholinophenyl) -Butanone-1 and the like. These photoinitiators may be used individually by 1 type, and may use 2 or more types together. The blending amount of the photopolymerization initiator is preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass in total of the resin and compound polymerizable by ultraviolet rays.

  When a photopolymerization initiator is blended in the coating liquid used to form the resin coating layer, a tertiary amine photopolymerization accelerator such as triethylamine or triethanolamine is used to accelerate the polymerization reaction by the photopolymerization initiator. Further, a phosphine photopolymerization accelerator such as triphenylphosphine, and a thioether photopolymerization accelerator such as thiodiglycol may be further added. The addition amount of these photopolymerization accelerators is preferably in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass in total of the resin and compound polymerizable by ultraviolet rays.

  The thickness of the resin coating layer is preferably in the range of 1 to 30 μm, and more preferably in the range of 1 to 10 μm. If the thickness of the resin coating layer is less than 1 μm, the effect of disposing the resin coating layer is small, and if it exceeds 30 μm, the surface of the charging roller becomes hard and flexibility is impaired.

The charging roller of the present invention preferably has an electric resistance of 10 ³ to 10 ¹⁰ Ω, and more preferably 10 ⁴ to 10 ⁸ Ω. The resistance value is measured, for example, by pressing the outer peripheral surface of the charging roller against a flat plate or a cylindrical counter electrode with a predetermined pressure, applying a voltage of 100 V between the shaft and the counter electrode, and obtaining from the current value at that time. be able to.

  The image forming apparatus of the present invention includes the above-described charging roller with stable performance, and can stably form an excellent image. The image forming apparatus of the present invention is not particularly limited except that the charging roller is used, and can be manufactured by a known method.

  The image forming apparatus of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a partial cross-sectional view of an example of the image forming apparatus of the present invention. The image forming apparatus in the illustrated example supplies a photosensitive drum 5 that holds an electrostatic latent image, a charging roller 1 that is positioned in the vicinity of the photosensitive drum 5 (upward in the drawing) and charges the photosensitive drum 5, and toner 6. A toner supply roller 7, a developing roller 8 disposed between the toner supply roller 7 and the photosensitive drum 5, a stratification blade 9 provided in the vicinity of the developing roller 8 (upper part in the drawing), and a photosensitive drum. 5 is provided with a transfer roller 10 located near (downward in the drawing) 5 and a cleaning unit 11 provided adjacent to the photosensitive drum 5. The image forming apparatus of the present invention can further include a known component (not shown) that is usually used in the image layer forming apparatus.

  In the illustrated image forming apparatus, the charging roller 1 is brought into contact with the photosensitive drum 5 and a voltage is applied between the photosensitive drum 5 and the charging roller 1 to charge the photosensitive drum 5 to a constant potential. Then, an electrostatic latent image is formed on the photosensitive drum 5 by an exposure machine (not shown). Next, the photosensitive drum 5, the toner supply roller 7, and the developing roller 8 rotate in the direction of the arrow in the drawing, so that the toner 6 on the toner supply roller 7 is sent to the photosensitive drum 5 through the developing roller 8. It is done. The toner 6 on the developing roller 8 is adjusted to a uniform thin layer by the stratifying blade 9 and rotates while the developing roller 8 and the photosensitive drum 5 are in contact with each other, so that the toner 6 is transferred from the developing roller 8 to the photosensitive drum 5. It adheres to the electrostatic latent image and the latent image becomes visible. The toner 6 adhered to the latent image is transferred to a recording medium such as paper by the transfer roller 10, and the toner 6 remaining on the photosensitive drum 5 after the transfer is removed by the cleaning blade 12 of the cleaning unit 11. Here, in the image forming apparatus of the present invention, it is possible to stably form an excellent image by using the charging roller of the present invention with stable performance as described above as the charging roller 1.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Example 1
After adding 1.6 parts by weight of conductive carbon and 0.15 parts by weight of dibutyltin dilaurate to 100 parts by weight of a trifunctional and 9,000 molecular weight polyether polyol obtained by adding propylene oxide to glycerin and stirring sufficiently, the mixture is stirred for 20 minutes under reduced pressure. This was defoamed and used as a polyol component. The hydroxyl value of the polyol component was 19 mgKOH / g. On the other hand, polypropylene glycol-modified polymeric MDI having an NCO content of 11% was degassed as an isocyanate component for 20 minutes while stirring under reduced pressure to obtain an isocyanate component. The polyol component and isocyanate component are mixed at a high speed of 3000 rpm with a two-component casting machine so that the ratio of the polyol component to the isocyanate component is 101.75 / 13.70 (isocyanate index: 103). Was poured into a cylindrical mold having an inner diameter of 12 mm set with a core metal of φ6 mm, and heated and cured in a hot air circulation oven at 90 ° C. for 60 minutes. A urethane roller with a cored bar was taken out from the cylindrical mold to obtain a roller.

The coating liquid having the composition shown in Table 1 is applied to the outer peripheral surface of the roller body with a roll coater, and the irradiation intensity is 400 mW and the integrated light quantity is 1000 mJ while rotating the roller using the UNICURE UVH-0252C apparatus manufactured by USHIO INC. When UV irradiation was performed at / cm ² , the coating solution was instantly cured to form an elastic resin coating layer, and a charging roller having a resin coating layer on the outer peripheral surface of the roller body was obtained. The roughness and resistance value of the obtained charging roller are evaluated by a known method, and the charging roller is incorporated into an image forming apparatus, and the image density, the presence / absence of halftone spots, the presence / absence of fogging, and the difference in front and rear end density are known. The method was evaluated. These results are shown in Table 1.

(Example 2)
A charging roller was produced in the same manner as in Example 1 except that a resin coating layer was formed on the outer peripheral surface of the roller body using a coating liquid having the composition shown in Table 1. Table 1 shows the physical properties and performance of the obtained charging roller.

(Example 3)
Liquid silicone LIM liquid # 2090 (made by Toray Dow Corning Silicone) is stirred and degassed, and then poured into a cylindrical mold with an inner diameter of 12 mm and a core metal with an outer diameter of φ6 mm, and 30 ° C at 30 ° C. It was heated and cured in a hot air circulating oven for a minute. A roller with a cored bar was taken out from the cylindrical mold and heated at 200 ° C. for 4 hours in a hot air circulating oven to obtain a roller. A charging roller was produced in the same manner as in Example 1 except that a resin coating layer was formed on the outer peripheral surface of the roller body using a coating liquid having the composition shown in Table 1. Table 1 shows the physical properties and performance of the obtained charging roller.

Example 4
100 parts by mass of Nipol IR2200L (manufactured by Zeon Corporation) having Mooney viscosity ML _{1 + 4} (100 ° C.) of 70, 60 parts by mass of LIR-30 (manufactured by Kuraray) having an average molecular weight of 29,000, carbon black TB # 5500 (manufactured by Tokai Carbon Co., Ltd.) 28 A rubber composition was prepared by kneading 5 parts by mass, 5 parts by mass of zinc oxide, 1 part by mass of stearic acid, and 9 parts by mass of perhexa C-40 (manufactured by NOF Corporation) using a 55 L kneader. The rubber composition was extruded into a cylindrical shape using a cross-head type extruder from Mitsuba Manufacturing Co., Ltd. to a cored bar with an outer diameter of φ6 mm to which an adhesive had been attached, to obtain an unvulcanized rubber / cored bar integral molding. This was set in a cylindrical mold, vulcanized at 175 ° C. for 20 minutes under a pressure of 3.2 × 10 ⁶ Pa. The pressure of the split mold was released to obtain a rubber roller, and further vulcanized in an oven at 180 ° C. for 4 hours. The obtained roller was plunge-type polished to a diameter of 12 mm with a rotating grindstone to obtain a rubber roller. A charging roller was produced in the same manner as in Example 1 except that a resin coating layer was formed on the outer peripheral surface of the roller body using a coating liquid having the composition shown in Table 1. Table 1 shows the physical properties and performance of the obtained charging roller.

(Example 5)
A charging roller was produced in the same manner as in Example 1 except that a resin coating layer was formed on the outer peripheral surface of the rubber roller produced in the same manner as in Example 4 above using a coating liquid having the formulation shown in Table 2. Table 2 shows the physical properties and performance of the obtained charging roller.

(Example 6)
100 parts by mass of UR8401 (manufactured by Toyobo), 5 parts by mass of coronate HX (manufactured by Nippon Polyurethane), 25 parts by mass of carbon black Printex 35 (manufactured by Degussa) A coating composed of 60 parts by mass of MEK (methyl ethyl ketone) was applied to a thickness of 10 μm and then cured by heating at 100 ° C. for 1 hour. A resin coating layer was formed on the obtained roller using a coating liquid having the formulation shown in Table 2 to produce a charging roller. Table 2 shows the physical properties and performance of the obtained charging roller.

(Comparative Example 1)
A charging roller was manufactured in the same manner as in Example 1 except that a resin coating layer was formed by heat curing using a coating liquid having the composition shown in Table 2. Table 2 shows the physical properties and performance of the obtained charging roller.

(Comparative Example 2)
A charging roller was produced in the same manner as in Example 4 except that a resin coating layer was formed by heat curing using a coating liquid having the composition shown in Table 2. Table 2 shows the physical properties and performance of the obtained charging roller.

Evaluation methods:
(1) Image evaluation Image forming device: Commercially available laser printer Cartridge color: Cyan (2) Surface roughness Surfcom 590A (manufactured by Tokyo Seimitsu)
(3) Resistance value
R8340A ULTRA HIGH RESISTANCE METER (manufactured by ADVANTEST)
Measurement conditions: 100V applied voltage between shaft and roller surface
Measured in a static state with a load of 500g on both ends of the roller

  As is apparent from Tables 1 and 2, since the charging roller of the example has uniform physical properties of the resin coating layer, an image forming apparatus incorporating the charging roller can stably form excellent images. Can do.

It is sectional drawing of an example of the charging roller of this invention. 1 is a partial cross-sectional view of an example of an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charging roller 2 Shaft 3 Non-foamed elastic layer 4 Resin coating layer 5 Photosensitive drum 6 Toner 7 Toner supply roller 8 Developing roller 9 Layering blade 10 Transfer roller 11 Cleaning unit 12 Cleaning blade

Claims (6)

In a charging roller comprising a shaft, a non-foamed elastic layer formed on the outer periphery of the shaft, and at least one resin coating layer formed on the outer peripheral surface of the non-foamed elastic layer,
The charging roller, wherein the resin coating layer comprises an ultraviolet curable resin.   After the resin coating layer is applied to the outer peripheral surface of the non-foamed elastic layer with a coating liquid containing a resin and / or compound that can be polymerized by ultraviolet rays, the resin that can be polymerized by ultraviolet rays by irradiation with ultraviolet rays and / or The charging roller according to claim 1, wherein the compound is cured.   The charging roller according to claim 2, wherein the coating liquid contains a photopolymerization initiator.   The charging roller according to claim 2, wherein the resin and / or compound polymerizable by ultraviolet rays is a resin and / or compound having a carbon-carbon double bond polymerizable by ultraviolet rays.   5. The charging roller according to claim 4, wherein the resin and / or compound having a double bond between carbon atoms that can be polymerized by ultraviolet rays is a (meth) acrylate monomer and / or an oligomer.   An image forming apparatus comprising the charging roller according to claim 1.

Images