JP4606068B2 - 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 method, since the charging roller must rotate while securely holding the photosensitive drum in close contact, 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. In addition, 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 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 of forming a stable quality resin coating layer without requiring a long drying line, a technique for forming a resin coating layer by applying and curing an ultraviolet curable resin on the surface of the elastic layer of the charging roller Has been proposed (see Patent Document 1).

JP 2002-310136 A

  In recent years, with the increase in color and speed of electrophotographic machines, the toner used tends to shift from pulverized toner to polymerized toner, and there is a tendency to lower the glass transition point (Tg) of the polymerized toner due to the demand for higher speed. It has become stronger and it has become impossible to exhibit sufficient performance with respect to toner adhesion. As a result, toner adheres to the charging roller, resulting in a decrease in durability, and a serious defect in the image.

  Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and does not require a long drying line for mass production, and filming or resistance increase due to toner adhesion hardly occurs even when used for a long time, resulting in a decrease in durability. An object of the present invention is to provide a charging roller excellent in durability. Another object of the present invention is 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.

As a result of intensive studies to achieve the above object, the present inventors have found that in a charging roller in which a resin coating layer is provided on the surface of the elastic layer , a non-UV curable fluorine-containing resin and fluorine are added to the resin coating layer. using the ultraviolet ray curable resin containing no, with a resin coating layer formed by ultraviolet irradiation, by including the fluorine resin coating layer, a long drying line unnecessary for mass production, the temperature distribution and air volume or the like in the to drying line As a result, it was found that a variation in the performance of the resin coating layer due to this variation can be eliminated, and that a charging roller in which filming or resistance increase due to toner adhesion hardly occurs on the roller surface can be obtained, and the present invention has been completed.

That is, the charging roller of the present invention is a resin coating comprising a shaft, an elastic layer formed on the outer periphery of the shaft, and at least one ultraviolet curable resin cured on the outer peripheral surface of the elastic layer. in the charging roller having a layer, the resin coating layer viewed contains a fluorine-containing resin and the ultraviolet curable resin of the non-ultraviolet curable, the resin coating layer, and the non-UV-curable fluorine-containing resin, the ultraviolet A coating liquid composed of a polymer and a fluorine-free resin and / or compound, a conductive agent, and a photopolymerization initiator is applied to the outer peripheral surface of the elastic layer, and then polymerized by the ultraviolet light by ultraviolet irradiation. It is characterized by curing a resin and / or compound that does not contain . Here, the ultraviolet curable resin is obtained by curing a resin and / or compound polymerizable by ultraviolet rays by irradiation with ultraviolet rays.

In the charging roller of the present invention, the resin coating layer includes a non-ultraviolet curable fluorine-containing resin and an ultraviolet curable resin cured by ultraviolet rays. Here, as the non-ultraviolet 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 urethane Based resins are preferred. Further, the ultraviolet curable resin is an ultraviolet-curable resin containing no fluorine.

  In the coating liquid, the resin and / or compound that can be polymerized by ultraviolet rays and do not contain fluorine is preferably a resin and / or compound that has a double bond between carbon atoms that can be polymerized by ultraviolet rays. As the resin and / or compound having a double bond between carbon atoms that can be polymerized by ultraviolet rays and not containing fluorine, (meth) acrylate monomers and oligomers are preferred.

  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 an ultraviolet curable resin containing no fluorine-containing resin and fluorine non-UV-curable in the resin coating layer, A long drying line is not required for mass production, toner adhesion on the roller surface is small, toner filming and resistance increase are unlikely to occur even when used for a long time, and a charging roller excellent in durability can be provided. Further, 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 ultraviolet curable resin and to contain 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 ultraviolet curable resin, it is not necessary to dry the resin coating layer 4 for a long period of time. Therefore, it is necessary to prepare a long drying line for mass production. No. That is, the resin coating layer 4 of the charging roller 1 of the present invention includes a non-ultraviolet curable fluorine-containing resin, a resin and / or compound that can be polymerized by ultraviolet rays and does not contain fluorine , a conductive agent, and a photopolymerization initiator. After the coating liquid consisting of is applied to the outer surface of the elastic layer 3, it is formed by curing the resin and / or compound that is irradiated with ultraviolet rays and polymerized by ultraviolet rays and does not contain fluorine. Furthermore, since the resin coating layer 4 is formed at the stage of irradiation with ultraviolet rays, it is possible to eliminate variations in the performance of the resin coating layer 4 due to variations in temperature distribution and air volume in the drying line. Further, in the charging roller 1 of the present invention, the resin coating layer 4 contains a non-ultraviolet curable fluorine-containing resin, and the surface energy of the resin coating layer 4 is small, so that toner adhesion is small and wear even after long-term use. It is difficult to do and has 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. 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 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 ultraviolet curable resin cured by ultraviolet rays and a non-ultraviolet curable fluorine-containing resin. The resin coating layer comprises a coating solution comprising a non-ultraviolet curable fluorine-containing resin, a resin and / or compound that can be polymerized by ultraviolet rays and does not contain fluorine , a conductive agent, and a photopolymerization initiator . after application to the outer surface, irradiated with ultraviolet rays, it is formed by curing the resin and / or compound contains no polymerizable fluorine by UV. 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 . Forming a resin coating layer by curing a coating solution composed of a resin and / or compound that can be polymerized by ultraviolet rays and does not contain fluorine , a conductive agent, and a photopolymerization initiator, and thus is long in forming a resin coating layer. It is no longer necessary to prepare a drying line, and variations in the characteristics of the resin coating layer due to variations in various conditions of the drying process can be eliminated. Further, a non-ultraviolet curable fluorine-containing resin is added to the resin coating layer. By including, the toner adhesion of the resin coating layer can be greatly reduced, and the durability of the charging roller can be greatly improved. Here, the coating liquid, non-UV-curable fluorine-containing resin, the resin and / or compound contains no polymerizable fluorine by UV, conductive agent, consisting of a photopolymerization initiator. 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. 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 .

In the resin coating layer, the proportion of the non-UV-curable fluorine-containing resin and the ultraviolet curing resin, an ultraviolet curable resin is preferably in the range of 10 to 10000 parts by weight per 100 parts by weight non-UV-curable fluorine-containing resin The range of 30 to 5000 parts by mass is more preferable. When the blending amount of the ultraviolet curable resin with respect to 100 parts by mass of the non-ultraviolet curable fluorine-containing resin is less than 10 parts by mass, the degree of crosslinking due to ultraviolet curing may be insufficient, and the coating strength may be lowered. , The fluorine content is lowered and the intended performance is not exhibited.

  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.

  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. You may mix and use. 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. Here, the resin and / or compound having a polymerizable double bond between carbon atoms does not contain fluorine . 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.

  (Meth) acrylate monomers and oligomers are preferable as the resin and / or compound having a polymerizable double bond between carbon atoms and / or containing no fluorine used for forming the ultraviolet curable resin. Here, as the (meth) acrylate monomer and oligomer, urethane (meth) acrylate, epoxy (meth) acrylate, ether (meth) acrylate, ester (meth) acrylate, polycarbonate (meth) acrylate, silicone Monomers and oligomers such as (meth) acrylates may be mentioned. 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 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, Examples of the non-UV-curable fluorine-containing resin preferably has dispersed or dissolved in the coating solution, the fluorine-containing (meth) acrylate resin, a fluorine-containing olefin resin, fluorine-containing ether resin, fluorine-containing ester Examples thereof include resins, fluorine-containing epoxy resins, and fluorine-containing urethane resins. The non-ultraviolet curable fluorine-containing resin may be used alone or in combination of two or more. The fluorine-containing resin has poor compatibility with the elastic layer, and its adhesion to the elastic layer is inferior to that of the resin not containing fluorine. However, the resin coating layer does not contain a non-UV curable fluorine-containing resin and fluorine. When the ultraviolet curable resin is included, the surface energy of the non-ultraviolet curable fluorine-containing resin is smaller than the surface energy of the ultraviolet curable resin not containing fluorine. The non-UV curable fluorine-containing resin tends to be unevenly distributed on the side not in contact with the resin), and as a result, the content of the non-UV curable fluorine-containing resin on the side in contact with the elastic layer of the resin coating layer is reduced, and the resin Adhesiveness between the coating layer and the elastic layer is improved. Further, as a result of the non-ultraviolet 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 the content of the non-ultraviolet curable fluorine-containing resin in the resin coating layer is reduced, the non-ultraviolet curable fluorine-containing resin is unevenly distributed on the surface side of the resin coating layer. It is also possible to sufficiently maintain the properties 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-ultraviolet 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. When the fluorine content of the non-ultraviolet curable fluorine-containing resin is less than 2% by mass, sufficient performance for toner adhesion is not exhibited, and when 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-ultraviolet curable fluorine-containing (meth) acrylate resin, perfluoroalkyl ester and partially fluorinated alkyl ester of (meth) acrylic acid, and perfluoroalkyl group or partially fluorinated alkyl group has an organic linking group. In addition to homopolymers of fluorine-containing (meth) acrylates such as (meth) acrylic acid ester and the like, the fluorine-containing (meth) acrylate and methyl, ethyl, butyl, octyl, dodecyl of (meth) acrylic acid And alkyl 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, specific examples of the non-ultraviolet curable fluorine-containing olefin resin include polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, fluorine Vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, polyvinyl fluoride, polyvinyl fluoride ether, fluoride vinyl ether A 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.

  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 carbon such as ketjen black and acetylene black, carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, and color for which oxidation treatment has been applied. 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 with respect to a total of 100 parts by mass of the resin and compound polymerizable by ultraviolet rays and the non-ultraviolet curable fluorine-containing resin and compound, and is 1 to 80 parts by mass. The range is more preferable, and the range of 10 to 50 parts by mass is even more preferable. On the other hand, the blending amount of the ionic conductive agent is preferably 20 parts by mass or less with respect to a total of 100 parts by mass of the resin and compound polymerizable by ultraviolet rays and the non-ultraviolet curable fluorine-containing resin and compound, and 0.01 to 20 mass. The range of parts is further preferred, and the range of 1 to 10 parts by mass is even more preferred.

A photopolymerization initiator is blended in the coating liquid 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.

  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 having a low surface frictional resistance, excellent durability, and 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. 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, the charging roller 1 is excellent for a long period of time by using the charging roller of the present invention having the above-described low surface frictional resistance, excellent durability, and stable performance. It is possible to form a stable image.

  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
SANNICS FA952 [Sanyo Chemical Industries, 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.

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 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 was examined. These results are shown in Table 1.

(Example 2)
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 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 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. A charging roller was manufactured in the same manner as in Example 1 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 )
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 manufactured in the same manner as in Example 1 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 )
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. An unvulcanized rubber / core metal integral molding was obtained by extruding a rubber composition onto a cored bar having an outer diameter of 6 mm with an adhesive using a crosshead type extruder from Mitsuba Seisakusho. 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 manufactured in the same manner as in Example 1 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 3 )
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 a Mooney viscosity ML _{1 + 4} (100 ° C.) of 39, Nobelite A (manufactured by Nippon Flour Industries) as calcium carbonate 36 parts by weight, 60 parts by weight of Diana Process Oil PW90 (made by Idemitsu Kosan), 3 parts by weight of zinc white, 2 parts by weight of stearic acid, 1 part by weight of vulcanization accelerator 2-mercaptothiazole, 1.5 parts by weight of sulfur, foaming agent Neo Cerbon N 6 parts by mass of # 1000M (manufactured by Eiwa Kasei Kogyo) were 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 manufactured in the same manner as in Example 1 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 4 )
A charging roller was produced in the same manner as in Example 1 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.

(Example 7)
A charging roller was produced in the same manner as in Example 1 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.

( Reference Example 5 )
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 provided with the elastic layer made of the urethane foam produced in Example 1. 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 Example 1 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.

(Comparative Example 2)
A charging roller was produced in the same manner as in Reference Example 2 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.

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 less toner adhesion to the resin coating layer, the toner adheres to the surface of the charging roller even when the image forming apparatus incorporating the charging roller is used for a long time. There were few, and the favorable image was obtained over the long term.

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 ultraviolet curable resin cured by ultraviolet rays formed on the outer peripheral surface of the elastic layer,
The resin coating layer viewed contains a non-UV-curable fluorine-containing resin and an ultraviolet curable resin,
The elastic resin layer comprises a coating liquid comprising a non-ultraviolet curable fluorine-containing resin, a resin and / or compound that can be polymerized by ultraviolet rays and does not contain fluorine, a conductive agent, and a photopolymerization initiator. A charging roller obtained by curing a resin and / or compound that can be polymerized by ultraviolet rays and does not contain fluorine after being applied to the outer peripheral surface of the resin .   The charging roller according to claim 1, wherein the non-ultraviolet curable fluorine-containing resin is at least one selected from the group consisting of fluorine-containing (meth) acrylate resins and fluorine-containing olefin resins. 2. The charging roller according to claim 1 , wherein the resin and / or compound that is polymerizable by ultraviolet rays and does not contain fluorine is a resin and / or compound having a double bond between carbon atoms that is polymerizable by ultraviolet rays. . The charging according to claim 3 , wherein the resin and / or compound having a carbon-carbon double bond polymerizable by ultraviolet rays and containing no fluorine is a (meth) acrylate monomer and / or oligomer. roller. An image forming apparatus comprising the charging roller according to claim 1 .

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