JP4571442B2 - Charging roller and image forming apparatus having the same - Google Patents

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 on the charging roller body, and then drying and curing with heat or hot air. In this case, since long drying is required, a long drying line is necessary for mass production. 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 resin coating layer having a stable quality without requiring a long drying line, an ultraviolet curable compound is applied to the surface of the elastic layer of the charging roller, and the compound is cured to form a resin coating layer. Has been proposed (see Patent Document 1).

JP 2002-310136 A

  However, since the resin coating layer formed by applying an ultraviolet curable compound and curing the compound with ultraviolet rays contains an unreacted compound, the photosensitive drum may be contaminated. In particular, when a carbon-based electronic conductive agent is blended to adjust the electrical resistance of the resin coating layer, the carbon-based electronic conductive agent absorbs ultraviolet rays, so that the ultraviolet curable compound does not sufficiently undergo a curing reaction, There was a problem that the reaction compound easily remained. In addition, a charging roller having a resin coating layer formed by UV curing on the outer peripheral surface of the elastic layer has a problem that toner is easily laminated on the roller surface depending on use conditions because the toner releasability on the roller surface is low. It was. Therefore, when an image forming apparatus in which such a charging roller is incorporated is used for a long time, there is a problem that toner filming occurs on the surface of the charging roller or the surface resistance increases, and image defects are likely to occur.

  Accordingly, an object of the present invention is to provide a charging roller that solves the above-described problems of the prior art, does not require a long drying line for mass production, and does not contaminate the photosensitive drum. Another object of the present invention is that a long drying line is not required for mass production, the photosensitive drum is not contaminated, and toner filming and resistance increase occur on the surface even when used for a long time. It is an object to provide a charging roller which is difficult and has excellent durability. Another object of the present invention is to provide an image forming apparatus that includes such a charging roller and that can stably form a good image over a long period of time.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have used an electron beam curable resin for the resin coating layer in a charging roller in which a resin coating layer is provided on the surface of the elastic layer. Is formed by electron beam irradiation, which eliminates the need for a long drying line for mass production, eliminates variations in the performance of the resin coating layer due to variations in temperature distribution and air flow in the drying line, and reduces the amount of unreacted compounds remaining. It has been found that a reduced charging roller can be obtained, and the resin coating layer further includes (1) a fluorine-containing electron beam curable resin, (2) a non-electron beam curable fluorine-containing resin and / or compound, and fluorine. No electron beam curable resin, (3) non-electron beam curable fluorine-containing resin and / or compound, and fluorine-containing electron beam curable resin, and the resin coating layer contains fluorine. Special In addition, the inventors have found that a charging roller can be obtained in which toner adhesion on the roller surface is low and toner filming and resistance increase hardly occur even when used for a long period of time. .

That is, the charging roller of the present invention includes a shaft, an elastic layer formed on the outer periphery of the shaft, and an electron beam curable resin cured by at least one electron beam formed on the outer peripheral surface of the elastic layer. A resin coating layer,
The resin coating layer further comprises a non-electron beam curable fluorine-containing resin containing (meth) acryloyl groups of 0 to less than 0.01 per 1,000 molecular weights ,
The resin coating layer containing the fluorine-containing resin includes a non-electron beam curable fluorine-containing resin , a resin and / or compound having a double bond between carbon atoms that can be polymerized by an electron beam and not containing fluorine, and a conductive material. after the coating liquid consisting agent was coated on the outer peripheral surface of the elastic layer, the electron beam irradiation does not contain and fluorine has a double bond polymerizable carbon atoms by the electron beam the resin and / or compound Ri name is cured,
The resin and / or compound having a double bond between carbon atoms that can be polymerized by an electron beam and not containing fluorine is a (meth) acrylate monomer and / or oligomer . Here, the electron beam curable resin is obtained by curing a resin and / or compound having a carbon-carbon double bond polymerizable by an electron beam and not containing fluorine by electron beam irradiation.

In the charging roller of the present invention, the resin coating layer contains a non-electron beam curable fluorine-containing resin . In addition, the non-electron beam curable resin forming the resin coating layer in the present invention is a resin and a compound containing less than 0 to 0.01 (meth) acryloyl group having a high electron beam sensitivity per 1,000 molecular weight, and closer to 0 preferable. Resins and compounds that can be polymerized by an electron beam include resins and oligomers containing (meth) acryloyl groups having a high electron beam sensitivity of 0.01 or more, preferably 0.1 or more per 1,000 molecular weight, and one or more in one molecule. It is a (meth) acrylate having a (meth) acryloyl group.

In the charging roller of the present invention, the resin coating layer includes a non-electron beam curable fluorine-containing resin and an electron beam curable resin. Here, as the non-electron beam curable fluorine-containing resin , fluorine-containing (meth) acrylate resin , fluorine-containing olefin resin , fluorine-containing ether resin , fluorine-containing ester resin , fluorine-containing epoxy resin , fluorine-containing resin Urethane resins are preferred. Further, the electron beam curing resin, an electron beam-curable resin containing no fluorine.

In another preferable embodiment of the charging roller of the present invention, the conductive agent is carbon-based electron conductive agent. Since the electron beam is difficult to be absorbed by the carbon-based electron conductive agent, the remaining amount of the unreacted compound can be sufficiently suppressed even if the carbon-based electron conductive agent is used for adjusting the electric resistance of the resin coating layer.

  In another preferred embodiment of the charging roller of the present invention, the resin coating layer has a thickness of 1 to 500 μm. Since the electron beam reaches the deep part of the resin coating layer, the remaining amount of the unreacted compound can be sufficiently suppressed even if the resin coating layer is thick.

  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 the charging roller in which the resin coating layer is disposed on the surface of the elastic layer, by using the electron beam curable resin for the resin coating layer, a long drying line is not required for mass production, and the photosensitive drum It is possible to provide a charging roller that does not contaminate the toner. Further, by using the electron beam-curable resin containing no fluorine-containing resin and fluorine non electron beam curing in the resin coating layer, without the need for long drying line for mass production, it is not possible to contaminate the photosensitive drum In addition, it is possible to provide a charging roller excellent in durability because toner adhesion on the roller surface is small, toner filming and resistance increase hardly occur even when used for a long period of time. Furthermore, it is possible to provide an image forming apparatus that includes such a charging roller and can stably form a good image over a long period of time.

  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 illustrated charging roller 1 includes a shaft 2, an 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 elastic layer 3. 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. Here, the resin coating layer 4 needs to contain an electron beam curable resin, and preferably contains a fluorine-containing resin and / or a compound.

In the charging roller 1 of the present invention, since the resin coating layer 4 is made of an electron beam curable resin, it is not necessary to dry for a long time in forming the resin coating layer 4, and therefore it is necessary to prepare a long drying line for mass production. There is no. That is, the resin coating layer 4 of the charging roller 1 of the present invention includes a non-electron beam curable fluorine-containing resin, a resin having a carbon-carbon double bond that can be polymerized by an electron beam , and / or no fluorine. A resin containing a compound and a conductive agent on the outer surface of the elastic layer 3 and then irradiating with an electron beam to have a carbon-carbon double bond polymerizable by the electron beam and not containing fluorine; and Since it is formed by curing the compound, a drying step is not essential, and furthermore, since the resin coating layer 4 is formed at the stage of irradiation with an electron beam, the temperature distribution in the drying line, the air volume, etc. Variations in the performance of the resin coating layer 4 due to variations can be eliminated.

  In the charging roller 1 of the present invention, since the resin coating layer 4 is formed by electron beam irradiation, it is possible to prevent residual unreacted compounds by optimizing the amount of electron beam irradiation. Moreover, the crosslinking density of the resin coating layer 4 can also be adjusted by controlling the acceleration voltage of an electron beam. Furthermore, since the electron beam is difficult to be absorbed by the carbon-based electron conductive agent, even when a carbon-based electron conductive agent is used for the resin coating layer 4, an electron beam curable resin can be sufficiently generated by electron beam irradiation, Unreacted compounds can be prevented from remaining.

Furthermore, in the charging roller 1 of the present invention, the surface energy of the resin coating layer 4 can be reduced by including a non-electron beam curable fluorine-containing resin in the resin coating layer 4. In addition, toner adhesion on the surface is small, toner filming and resistance increase hardly occur even after long-term use, and excellent durability.

  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 elastic layer of the charging roller of the present invention contains an elastomer and a conductive agent, and if necessary, contains other components such as a filler. Examples of the elastomer used for the elastic layer include silicone rubber, ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), natural rubber, styrene-butadiene rubber (SBR), butyl rubber, chloroprene rubber, acrylic rubber, and epichloro. Examples include hydrin rubber (ECO), ethylene-vinyl acetate copolymer (EVA), polyurethane, and mixtures thereof. Among these, silicone rubber, EPDM, ECO, and polyurethane are preferable. In the elastic layer, the elastomer may be used as a foam by chemically foaming the elastomer using a foaming agent, or mechanically entraining and foaming air like a polyurethane foam.

  The shaft and the elastic layer may be integrated using a reaction injection molding method (RIM molding method). That is, it is possible to integrate the shaft and the elastic layer by mixing and injecting two kinds of monomer components constituting the raw material component of the elastic layer into a cylindrical mold and performing a polymerization reaction. 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 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 an elastic layer by liquid injection molding (LIM: Liquid injection Molding). 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 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. Conductive whiskers such as conductive polymer, 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 elastic layer preferably has a resistance value of 10 ³ to 10 ¹⁰ Ωcm, more preferably 10 ⁴ to 10 ⁸ Ωcm, depending on the blending of the conductive agent.

  The 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 into a rubbery material, if necessary. Accelerators, vulcanization accelerators, vulcanization retarders, and the like may be included. In addition, the elastic layer further comprises a rubber compounding agent such as a filler, a peptizer, a foaming agent, a plasticizer, a softener, a tackifier, an anti-tacking agent, a separating agent, a release agent, a bulking agent, and a coloring agent. An agent may be contained.

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

The resin coating layer of the charging roller of the present invention needs to contain an electron beam curable resin cured by an electron beam. The resin coating layer comprises a non-electron beam curable fluorine-containing resin , a resin and / or compound having a double bond between carbon atoms that can be polymerized by an electron beam and not containing fluorine, and a conductive agent. After applying the working fluid to the outer peripheral surface of the elastic layer, it is formed by curing a resin and / or compound having a carbon-carbon double bond that can be polymerized by an electron beam and not containing fluorine. The Generally, 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, but it can be polymerized by an electron beam and does not contain fluorine. By forming the resin coating layer by curing the coating liquid containing the resin and / or compound, it is not necessary to prepare a long drying line for the formation of the resin coating layer, and also due to variations in various conditions of the drying process It is possible to eliminate variations in the characteristics of the resin coating layer . Examples of a method for applying the coating liquid to the surface of the elastic layer include a spray method, a roll coater method, a dipping method, and a die coating method. Moreover, the conditions of electron beam irradiation are suitably selected according to the kind and application amount of electron beam curable resin.

The content of the electron beam curable resin in the resin coating layer is preferably in the range of 10% by mass or more, and more preferably in the range of 30% by mass or more. When the content of the electron beam curable resin in the resin coating layer is less than 10% by mass, the degree of crosslinking due to electron beam curing may be insufficient, and the coating strength may be lowered.
It is.

  Examples of the electron beam 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. Resins, urea resins, silicone resins, polyvinyl butyral resins, vinyl ether resins, vinyl ester resins, and modified resins in which specific functional groups are introduced into these resins are included. These resins may be used alone or in combination of two or more. May be used in combination. Moreover, it is preferable to introduce a crosslinked structure into the resin coating layer in order to improve mechanical strength and environmental resistance.

The resin coating layer of the charging roller of the present invention contains a non-electron beam curable fluorine-containing resin . By including a non-electron beam curable fluorine-containing resin in the resin coating layer, the toner adhesion of the resin coating layer can be greatly reduced, and the durability of the charging roller can be greatly improved . In addition, the said resin and compound which have a carbon-carbon double bond polymerizable by an electron beam and do not contain fluorine may be used singly or in combination of two or more.

  The fluorine content in the resin coating layer is preferably in the range of 0.1 to 45% by mass, and more preferably in the range of 0.5 to 20% by mass. When the fluorine content in the resin coating layer is less than 0.1% by mass, sufficient performance for toner adhesion may not be exhibited. When it exceeds 45% by mass, the adhesion to the elastic layer or the lower layer is lowered.

As the resin and / or compound having no carbon-containing double bond that can be polymerized by the electron beam and not containing fluorine, (meth) acrylate monomers and oligomers that do not contain fluorine are preferable. For example, urethane-based (meth) acrylate And monomers and oligomers such as epoxy (meth) acrylate, ether (meth) acrylate, ester (meth) acrylate, polycarbonate (meth) acrylate, and silicone (meth) acrylate. These (meth) acrylate oligomers include polyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, bisphenol A type epoxy resin, phenol novolac type epoxy resin, adducts of polyhydric alcohol and ε-caprolactone, (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 benzene ring, naphthalene ring, spiro ring, dicyclopentadiene, tricyclodecane, etc. A reaction product of a compound having a cyclic structure and 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 each composed of a polyol (polyether polyol, polyester polyol, and polycarbonate polyol) and (meth) acrylic acid. Obtained by reaction.

On the other hand, as the non-electron beam curable fluorine-containing resin , those that are dispersed or dissolved in the coating liquid are preferable. Fluorine-containing (meth) acrylate resin , fluorine-containing olefin resin , fluorine-containing ether resin , fluorine-containing ester Resin , fluorine-containing epoxy resin , and fluorine-containing urethane resin . The non-electron beam curable fluorine-containing resin may be used alone or in combination of two or more. The fluorine-containing resin and / or compound has poor compatibility with the elastic layer, and the adhesion to the elastic layer is inferior to that of the resin not containing fluorine. However, the resin coating layer has a non-electron beam curable fluorine-containing resin. And the electron beam curable resin not containing fluorine, the surface energy of the non-electron beam curable fluorine-containing resin is smaller than the surface energy of the electron beam curable resin not containing fluorine. There is a tendency that non-electron beam curable fluorine-containing resin is unevenly distributed on the surface side (that is, the side not in contact with the elastic layer), and as a result, the non-electron beam curable fluorine-containing side of the resin coating layer on the side in contact with the elastic layer The resin content decreases, and the adhesion between the resin coating layer and the elastic layer is improved. Further, as a result of the non-electron beam curable fluorine-containing resin being unevenly distributed on the surface side of the resin coating layer, the releasability of the resin coating layer from the toner is improved. Further, even if reducing the content of non-electron beam-curing fluorine-containing resin of the resin coating layer, since the non-electron beam-curable fluorine-containing resin is unevenly distributed on the surface side of the resin coating layer, the resin coating layer toner and the It is possible to sufficiently maintain the releasability and to reduce the content of the expensive fluorine-containing resin while improving the adhesion between the resin coating layer and the elastic layer. Here, the fluorine content of the non-electron beam curable fluorine-containing resin is preferably in the range of 2 to 80% by mass, and more preferably in the range of 2 to 70% by mass. If the fluorine content of the non-electron beam curable fluorine-containing resin is less than 2% by mass, the effect of fluorine is insufficient, and if it exceeds 80% by mass, compatibility and dispersibility are problems.

（式中、Ｘは、炭素数１〜２０のアルキレン基、パーフルオロアルキレン基又は部分フッ素化アルキレン基で、直鎖状及び分岐状のいずれでもよく、更には、これらアルキレン基、パーフルオロアルキレン基及び部分フッ素化アルキレン基中の主鎖又は側鎖中に酸素原子が介在したものであってもよく；Ｒ³は、水素、メチル基、塩素、フッ素又はシアノ基である）で表される化合物が好ましい。ここで、樹脂被覆層の耐久性を向上させる観点から、式(III)中のＸが炭素数４以上のアルキレン基、パーフルオロアルキレン基又は部分フッ素化アルキレン基であるのが好ましく、炭素数６以上のアルキレン基、パーフルオロアルキレン基又は部分フッ素化アルキレン基であるのが更に好ましく、−(ＣＨ₂)₂−(ＣＦ₂)₇−であるのが特に好ましい。 As the non-electron beam curable fluorine-containing (meth) acrylate resin, perfluoroalkyl esters and partially fluorinated alkyl esters of (meth) acrylic acid, and perfluoroalkyl groups or partially fluorinated alkyl groups are organic linking groups. In addition to homopolymers of fluorine-containing (meth) acrylates such as (meth) acrylic acid esters linked via the fluorine-containing (meth) acrylate and (meth) acrylic acid methyl, ethyl, butyl, octyl, Examples thereof include alkyl esters such as dodecyl; hydroxyalkyl esters such as hydroxyethyl and hydroxybutyl; and copolymers with fluorine-free (meth) acrylates such as glycidyl esters. The copolymer may further be copolymerized with a small amount of polysiloxane group-containing (meth) acrylate. Here, the carbon number of the perfluoroalkyl group or the partially fluorinated alkyl group in the fluorine-containing (meth) acrylate is preferably in the range of 1-20. In addition, as the fluorine-containing (meth) acrylate, the following formula (III):

(In the formula, X is an alkylene group having 1 to 20 carbon atoms, a perfluoroalkylene group or a partially fluorinated alkylene group, which may be linear or branched, and further, these alkylene groups and perfluoroalkylene groups. And a compound in which an oxygen atom may be present in the main chain or side chain in the partially fluorinated alkylene group; R ³ is hydrogen, methyl group, chlorine, fluorine or cyano group) Is preferred. Here, from the viewpoint of improving the durability of the resin coating layer, X in the formula (III) is preferably an alkylene group having 4 or more carbon atoms, a perfluoroalkylene group or a partially fluorinated alkylene group, and having 6 carbon atoms. The above alkylene group, perfluoroalkylene group or partially fluorinated alkylene group is more preferable, and — (CH ₂ ) ₂ — (CF ₂ ) ₇ — is particularly preferable.

  The fluorine-containing (meth) acrylate-based resin may have a functional group capable of crosslinking reaction in the molecule, and examples of the functional group capable of crosslinking reaction include a hydroxyl group, a thiol group, a carboxyl group, an amino group, and an isocyanate. Group, aziridinyl group, glycidyl group, alkoxysilyl group, silanol group, cyclocarbonate group, acid anhydride group, vinyl group, enol ether group, thioether group, active ester group, acetoacetate group, metal salt, metal oxide and these Examples include functional groups blocked with various blocking agents. As the compound that reacts with the functional group capable of crosslinking reaction, a reactive polyfunctional compound having two or more reactive functional groups in the molecule can be used, and the reactive functional group includes the above-described crosslinking reaction. The same functional groups as possible functional groups can be mentioned. As said reactive polyfunctional compound, an organic epoxy compound and an organic polyisocyanate compound are preferable from a viewpoint of industrial usefulness.

  Examples of the organic epoxy compound include compounds having two or more glycidyl groups, and specifically include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, sorbitol polyglycidyl. Ether, polyethylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin polyglycidyl ether, diglycerin polyglycidyl ether, tri Methylolpropane polyglycidyl ether, spiroglycol diglycidyl ether, various Carboxymethyl resins.

  Specific examples of the organic polyisocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2, 4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-phenylene diisocyanate, 3,3'-dichloro -4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3, , 3′-dimethyl-4,4′-dicyclohexylmethane diisocyanate and the like, dimers and trimers thereof, and isocyanate groups of these compounds are converted to phenols, oximes, alcohols, active methylenes, mercaptans, acids And polyisocyanates partially blocked with amides, imides, amines, imidazoles, ureas, carbamates, imines or sulfites.

  On the other hand, as the non-electron beam curable fluorine-containing olefin resin, specifically, polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, Vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, polyvinyl fluoride, polyvinyl fluoride ether, fluoride vinyl ether -Tetrafluoroethylene copolymer etc. are mentioned. The fluorine-containing polyolefin resin is obtained by polymerizing or copolymerizing fluorine-containing olefin monomers such as vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, and vinyl fluoride ether.

  In addition, as the conductive agent used in the coating liquid, the electronic conductive agent and the ionic conductive agent exemplified as the conductive agent for the elastic layer can be used. Since the electron beam is not easily absorbed by the carbon-based electron conductive agent, in the present invention, the carbon-based electron conductive agent can also be suitably used for the resin coating layer. Here, as the carbon-based electron conductive agent, conductive carbon such as ketjen black and acetylene black, carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT and MT, oxidation treatment, etc. And carbon black for color, pyrolytic carbon black, natural graphite, artificial graphite, carbon whisker, graphite whisker and the like. The blending amount of the electron conductive agent is preferably 100 parts by mass or less, and 1 to 80 parts by mass with respect to 100 parts by mass in total of the resin and compound polymerizable by the electron beam and the non-electron beam curable fluorine-containing resin and compound. The range of parts is further preferred, and the range of 10 to 50 parts by mass is even more preferred. On the other hand, the blending amount of the ionic conductive agent is preferably 20 parts by mass or less with respect to 100 parts by mass in total of the resin and compound polymerizable by the electron beam and the non-electron beam curable fluorine-containing resin and compound, 0.01 to The range of 20 parts by mass is more preferable, and the range of 1 to 10 parts by mass is even more preferable.

  The thickness of the resin coating layer is preferably in the range of 1 to 500 μm, more preferably in the range of 1 to 30 μm, and still more preferably in the range of 1 to 10 μm. When the thickness of the resin coating layer is less than 1 μm, the effect of disposing the resin coating layer is small, and when it exceeds 500 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 a charging roller that does not require a long drying line for mass production and does not contaminate the photosensitive drum, 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, by using the charging roller of the present invention, in which the remaining of the unreacted compound in the resin coating layer 4 is sufficiently suppressed and the performance is stable, as the charging roller 1. An excellent image can be stably formed over a long period while preventing the photosensitive drum 5 from being contaminated.

  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.

( Comparative Example 3 )
SANNICS FA952 [Sanyo Kasei Kogyo Co., Ltd. polyether polyol, OH value = 37] 100 parts by mass, SRX274C [Toray Dow Corning Silicone Co., Ltd. foam stabilizer] 1 part by mass, TOYOCAT NP [Tosoh Corporation amine catalyst] 2.8 parts by mass, 1.5 parts by mass of TOYOCAT EP [amine catalyst manufactured by Tosoh Corporation] and 59 parts by mass of Sunfoam IC-716 [Sanyo Chemical Co., Ltd. Tolylene Diisocyanate] were mechanically stirred and foamed.

  Next, a metal shaft with an outer diameter of 6.0 mm and a length of 240 mm is arranged from one side opening of a metal cylindrical mold having an inner diameter of 12 mm and a length of 250 mm, and the surface is fluorinated. Was injected from the foaming machine.

  Next, the mold in which the foamed polyurethane raw material was injected was heated in an oven at 80 ° C. for 20 minutes and then demolded, and a roller body having an elastic layer made of urethane foam having an outer diameter of 12 mm and a foam part having an overall length of 230 mm was obtained. Produced.

  A coating liquid having the composition shown in Table 1 was applied to the outer peripheral surface of the roller body with a roll coater, and while rotating the roller using a Min-EB apparatus manufactured by Ushio Electric Co., Ltd., an acceleration voltage of 30 kV, a tube current of 300 μA, When irradiated with an electron beam under the conditions of an irradiation distance of 100 mm, a nitrogen atmosphere of 760 Torr, and an irradiation time of 1 minute, the coating solution is instantly cured to form an elastic resin coating layer, and the resin coating layer is formed on the outer peripheral surface of the roller body. A charging roller provided with The obtained charging roller is 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 leading / lower end density difference are evaluated by a known method. The toner adhesion on the surface of the charging roller after printing 10,000 sheets, and the charging roller was incorporated in the image forming apparatus, and the image density, the presence / absence of halftone spots, the presence / absence of fogging, and the difference in density between the leading and trailing edges were examined. These results are shown in Table 1.

(Example 2)
100 parts by mass of Nipol IR2200L (manufactured by Zeon Corporation) with Mooney viscosity ML _{1 + 4} (100 ° C.) of 70, 60 parts by mass of LIR-30 (manufactured by Kuraray) with 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 crosshead type extruder manufactured by Mitsuba Manufacturing Co., Ltd., to a cored bar having 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 Comparative Example 3 except that the resin coating layer was formed on the outer peripheral surface of the roller body using the coating liquid having the composition shown in Table 1. Table 1 shows the physical properties and performance of the obtained charging roller.

( Reference Example 1 )
50 parts by mass of carbon black TB # 5500 (manufactured by Tokai Carbon) with respect to 100 parts by mass of EPDM having an iodine value of 36 and Mooney viscosity ML _{1 + 4} (100 ° C.) of 39, Nobelite A (manufactured by Nippon Flour Industries) ) 36 parts by mass, Diana Process Oil PW90 (made by Idemitsu Kosan) 60 parts by mass, zinc white 3 parts by mass, stearic acid 2 parts by mass, vulcanization accelerator 2-mercaptothiazole 1 part by mass, sulfur 1.5 parts by mass, foaming agent neoselbon 6 parts by mass of N # 1000M (manufactured by Eiwa Chemical Industries) was kneaded using a 55 L kneader to prepare a foamed rubber composition. The foamed rubber composition was extruded into a cylindrical shape using a cross-head type extruder from Mitsuba Seisakusho 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 integrated molded product. This was set in a cylindrical mold, vulcanized and foamed 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 foamed rubber roller with a skin layer, 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 foamed rubber roller. A charging roller was produced in the same manner as in Comparative Example 3 except that the resin coating layer was formed on the outer peripheral surface of the roller body using the coating liquid having the composition shown in Table 1. Table 1 shows the physical properties and performance of the obtained charging roller.

Example 4
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, sufficiently stirring and mixing, and then stirring 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 the 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). It was poured into a cylindrical mold set with a core metal having a size 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. A charging roller was produced in the same manner as in Comparative Example 3 except that the resin coating layer was formed on the outer peripheral surface of the roller body using the coating liquid having the composition shown in Table 1. Table 1 shows the physical properties and performance of the obtained charging roller.

( Reference Example 2 )
Liquid silicone LIM liquid # 2090 (made by Toray Dow Corning Silicone) was stirred and degassed, then poured into a cylindrical mold set with a core metal with an outer diameter of φ6 mm, and heated with air at 120 ° C for 30 minutes It was heated and cured in a circulation oven. A roller with a cored bar was taken out from the cylindrical mold and cured by heating in a hot air circulation oven at 200 ° C. for 4 hours to obtain a roller. A charging roller was produced in the same manner as in Comparative Example 3 except that the resin coating layer was formed on the outer peripheral surface of the roller body using the coating liquid having the composition shown in Table 1. Table 1 shows the physical properties and performance of the obtained charging roller.

( Comparative Example 4 )
A charging roller was produced in the same manner as in Comparative Example 3 except that the resin coating layer was formed using the coating liquid having the formulation shown in Table 2. Table 2 shows the physical properties and performance of the obtained charging roller.

( Reference Example 3 )
A charging roller was produced in the same manner as in Comparative Example 3 except that the resin coating layer was formed using the coating liquid having the formulation shown in Table 2. Table 2 shows the physical properties and performance of the obtained charging roller.

( Reference Example 4 )
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) on the roller body having an elastic layer made of urethane foam produced in Comparative Example 3. A coating consisting of 100 parts by mass of MEK (methyl ethyl ketone) was applied to a thickness of 50 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 composition 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 produced in the same manner as in Comparative Example 3 except that the resin coating layer was formed using the coating liquid having the formulation 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 2 except that the resin coating layer was formed using the 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. In the charging roller of the embodiment, the remaining amount of the unreacted compound in the resin coating layer is sufficiently suppressed, so that the photosensitive drum is not contaminated.

Further, the charging roller of Example 2 and 4 the resin coating layer comprises a non-electron beam-curable fluorine-containing resin, since the toner adhesion of the resin coating layer is small, the image forming apparatus incorporating such a charging roller is long An excellent image could be stably formed over a wide range.

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 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 (5)

In a charging roller comprising a shaft, an elastic layer formed on the outer periphery of the shaft, and a resin coating layer containing an electron beam curable resin cured by at least one electron beam formed on the outer peripheral surface of the elastic layer ,
The resin coating layer further comprises a non-electron beam curable fluorine-containing resin containing (meth) acryloyl groups of 0 to less than 0.01 per 1,000 molecular weights ,
The resin coating layer containing the fluorine-containing resin includes a non-electron beam curable fluorine-containing resin , a resin and / or compound having a double bond between carbon atoms that can be polymerized by an electron beam and not containing fluorine, and a conductive material. after the coating liquid consisting agent was coated on the outer peripheral surface of the elastic layer, the electron beam irradiation does not contain and fluorine has a double bond polymerizable carbon atoms by the electron beam the resin and / or compound Ri name is cured,
A charging roller , wherein the resin and / or compound having a carbon-carbon double bond polymerizable by electron beam and not containing fluorine is a (meth) acrylate monomer and / or oligomer . The charging roller according to claim 1, wherein the non-electron beam curable fluorine-containing resin is at least one selected from the group consisting of fluorine-containing (meth) acrylate resins and fluorine-containing olefin resins. . The charging roller according to claim 1, wherein the conductive agent is carbon-based electron conductive agent.   The charging roller according to claim 1, wherein the resin coating layer has a thickness of 1 to 500 μm. An image forming apparatus comprising the charging roller according to claim 1 .

Images