JP5116272B2 - Conductive roller and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a conductive roller having an elastic layer and a resin coating layer, and an image forming apparatus including the conductive roller, and particularly has low environmental dependency, excellent conductivity, and occurrence of bleed out. The present invention relates to a suppressed conductive roller and an image forming apparatus including the conductive roller.

  In general, in an electrophotographic image forming apparatus such as a copying machine, a facsimile, or a laser beam printer (LBP), a developing roller, a charging roller, a toner supply roller, a transfer roller, a paper feeding roller, a cleaning roller, and a pressure for fixing. As a roller or the like, a roll-shaped conductive elastic member, that is, a conductive roller is frequently used, and the conductive roller is usually mounted with a shaft member supported by both ends in the length direction, and the shaft member. And one or more elastic layers disposed on the outside in the radial direction. In addition, a resin coating layer may be further formed on the surface of the elastic layer for the purpose of controlling chargeability and adhesion to the toner and preventing contamination of the photosensitive drum by the elastic layer.

  An elastomer such as silicone rubber, acrylonitrile-butadiene rubber (NBR), ethylene-propylene-diene rubber (EPDM), epichlorohydrin rubber (ECO), and polyurethane is used for the elastic layer and the resin coating layer of the conductive roller. In order to impart conductivity to this, an electronic conductive agent such as carbon black and an ionic conductive agent such as perchlorate or quaternary ammonium salt are added. Here, when an electronic conductive agent such as carbon black is used for the resin coating layer, there is a possibility that the conductive variation of the conductive roller will increase. On the other hand, when an ionic conductive agent is used for the resin coating layer, there is a problem that the conductive roller is highly dependent on the environment, the bleed out easily occurs, and the photosensitive drum is easily contaminated.

  Accordingly, an object of the present invention is to provide a conductive roller that solves the above-described problems of the prior art, has low environmental dependency, has excellent conductivity, and suppresses the occurrence of bleed out. . Another object of the present invention is to provide an image forming apparatus capable of stably forming a good image by using such a conductive roller.

As a result of intensive studies to achieve the above object, the present inventors have found that a resin coating layer made of urethane resin adjacent to the elastic layer has lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl). By applying methane, it was found that good conductivity under low temperature and low humidity can be expressed without causing bleed out, and the present invention has been completed.

That is, the conductive roller of the present invention, conductive having a shaft, an elastic layer formed on the outer periphery of the shaft, and an elastic layer one layer of urethane resin of the resin coating layer formed on the outer peripheral surface of the In the adhesive roller, at least one of the resin coating layers contains lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane, and the resin coating layer adjacent to the elastic layer is dispersed in water. The water-dispersible urethane resin or the water-soluble urethane resin is an ultraviolet curable water-based urethane resin .

  In the conductive roller of the present invention, the resin coating layer containing lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane has lithium bis (trifluoromethane) based on 100 parts by mass of the urethane resin. It is preferable to contain 0.05 to 10 parts by mass of (sulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane.

  An image forming apparatus according to the present invention includes the conductive roller.

According to the present invention, in the conductive roller in which one or more resin coating layers made of urethane resin are disposed on the outer periphery of the elastic layer, lithium bis (trifluoromethanesulfonyl) imide is formed on the resin coating layer adjacent to the elastic layer. In addition, by including lithium tris (trifluoromethanesulfonyl) methane, it is possible to provide a conductive roller that has low environmental dependency, has excellent conductivity, and suppresses the occurrence of bleed out. . Further, by providing such a conductive roller, an image forming apparatus capable of stably forming a good image can be provided.

<Conductive roller>
Below, the conductive roller of this invention is demonstrated in detail, referring a figure. FIG. 1 is a cross-sectional view of an example of a conductive roller of the present invention. The illustrated conductive 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 made of urethane resin formed on the outer peripheral surface of the elastic layer 3. The conductive roller 1 shown in FIG. 1 has only one resin coating layer 4 made of urethane resin, but the conductive roller of the present invention is made of urethane resin like the conductive roller 5 shown in FIG. Two or more resin coating layers 6a and 6b can be provided.

In the conductive roller of the present invention, at least one of the resin coating layers is composed of lithium bis (trifluoromethanesulfonyl) imide [Li (CF ₃ SO ₂ ) ₂ N] and / or lithium tris (trifluoromethanesulfonyl) methane [Li (CF ₃ SO ₂ ) ₃ C]. In the conductive roller of the present invention, the resin coating layer adjacent to the elastic layer contains lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane. Low dependence under low humidity environment and excellent conductivity. For this reason, when lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane is used as the conductive agent, the blending amount of the conductive agent can be reduced, and the occurrence of bleeding out of the conductive agent can be caused. It is suppressed. Therefore, when a conductive roller having such a resin coating layer is used in an image forming apparatus, contamination of the photosensitive drum can be prevented.

  The shaft member of the conductive 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 solid body, a metal cylindrical body hollowed inside, or a high rigidity Examples thereof include a cylindrical body made of resin, and a composite body in which a high-rigidity resin is arranged on the outer periphery of a cored bar. In addition, when using highly rigid resin for a shaft member, it is preferable to ensure sufficient electroconductivity by adding and disperse | distributing a electrically conductive agent to highly rigid resin. Here, as the conductive agent dispersed in the high-rigidity resin, carbon black powder, graphite powder, carbon fiber, metal powder such as aluminum, copper and nickel, metal oxide powder such as tin oxide, titanium oxide and zinc oxide, conductive A powdery conductive agent such as conductive glass powder is preferred. These electrically conductive agents may be used individually by 1 type, and may be used in combination of 2 or more type. The blending amount of the conductive agent is not particularly limited, but is preferably in the range of 5 to 40% by mass, and more preferably in the range of 5 to 20% by mass with respect to the entire highly rigid resin.

  Examples of the material for the metal core bar and the metal cylinder include iron, stainless steel, and aluminum. The material of the high-rigidity resin base material is polyacetal, polyamide 6, polyamide 6 · 6, polyamide 12, polyamide 4 · 6, polyamide 6 · 10, polyamide 6 · 12, polyamide 11, polyamide MXD6, polybutylene. Terephthalate, polyphenylene oxide, polyphenylene sulfide, polyethersulfone, polycarbonate, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone, polyethylene terephthalate, polyarylate, liquid crystal polymer, polytetrafluoroethylene, polypropylene, ABS resin, polystyrene , Polyethylene, melamine resin, phenol resin, silicone resin and the like. Among these, polyacetal, polyamide 6/6, polyamide MXD6, polyamide 6/12, polybutylene terephthalate, polyphenylene ether, polyphenylene sulfide, and polycarbonate are preferable. These high-rigidity resins may be used alone or in combination of two or more.

  The elastic layer of the conductive roller of the present invention includes an elastomer and a conductive agent, and may include other components as necessary. Examples of the elastomer used for the elastic layer include polyurethane, silicone rubber, ethylene-propylene-diene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), natural rubber (NR), styrene-butadiene rubber (SBR), and butadiene rubber (BR). , Isoprene rubber (IR), polynorbornene rubber, butyl rubber (IIR), chloroprene rubber (CR), acrylic rubber, epichlorohydrin rubber (ECO), ethylene-vinyl acetate copolymer (EVA), and mixtures thereof. Among these, silicone rubber, EPDM, ECO, and polyurethane are preferable. In the elastic layer, the elastomer may be used as a non-foamed material or a foamed material.

  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. If the resistance value of the elastic layer is less than 10 ³ Ωcm, the charge may leak to the photosensitive drum or the conductive roller itself may be damaged by the voltage. If the resistance value exceeds 10 ¹⁰ Ωcm, ground cover is likely to occur. .

  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 elastic layer of the conductive roller of the present invention is preferably composed of urethane foam obtained by mechanically foaming a urethane raw material, that is, mechanical floss foamed urethane. The urethane foam is produced by a method in which bubbles are mixed by mechanically stirring a urethane raw material without using a foaming agent. Here, examples of the urethane raw material include a polyol and a polyisocyanate, or a urethane prepolymer and a chain extender synthesized from a polyol and a polyisocyanate. The urethane raw material further includes a catalyst, a foam stabilizer, the above-described conductive agent, and the like. Can be added. In addition, the bubbles in the urethane foam are mainly closed cells, and the expansion ratio and density can be appropriately adjusted depending on how air is introduced.

  Examples of the polyol that can be used as the foamed urethane raw material include polyester polyol, polyether polyol, polytetramethylene glycol, polybutadiene polyol, propylene oxide (PO) -modified polybutadiene polyol, and polyisoprene polyol. Examples of the polyester polyol include polyhydric alcohols such as ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, propylene glycol, trimethylolethane, trimethylolpropane, adipic acid, and glutaric acid. , Succinic acid, sebacic acid, pimelic acid, suberic acid and other polybasic carboxylic acids, and the polyether polyol is, for example, polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, ethylene oxide and propylene It can be obtained by adding alkylene oxide such as oxide.

  Polyisocyanates that can be used as the urethane foam raw material include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude diphenylmethane diisocyanate (crude MDI), isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diene. Isocyanates, hexamethylene diisocyanate (HDI), isocyanurate-modified products, carbodiimide-modified products, glycol-modified products, and the like can be used. The amount of these polyisocyanates used is appropriately selected so that the ratio (NCO / OH) of the isocyanate groups (NCO) of the polyisocyanates to the hydroxyl groups (OH) of the polyol is in the range of 95/100 to 110/100. It is preferable.

  The polyisocyanate may be reacted with the polyol by a one-shot method, or may be reacted with the polyol in advance to form a urethane prepolymer, and then reacted with a chain extender or the like in the presence of a catalyst. In addition, the NCO group content of the synthesized urethane prepolymer is preferably in the range of 3 to 30% by mass, more preferably in the range of 5 to 15% by mass, and the amount of polyisocyanate and polyol used in the synthesis of the urethane prepolymer is It is preferable that the NCO group content of the urethane prepolymer is appropriately selected so as to be in the above range. The chain extender is a compound that connects the urethane prepolymers, specifically, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, trimethylolpropane, polyether polyol. , Polytetramethylene glycol, polybutadiene polyol, polyisoprene polyol and the like. The amount of these chain extenders used is such that the ratio (NCO / OH) of the isocyanate group (NCO) of the urethane prepolymer to the hydroxyl group (OH) of the chain extender is in the range of 95/100 to 110/100. It is preferable to select appropriately.

  The catalyst that can be used for the foamed urethane raw material is a catalyst for urethanization reaction, specifically, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin thiocarboxylate, octene Organic tin compounds such as tin oxide; Organic lead compounds such as lead octenoate; Monoamines such as triethylamine and dimethylcyclohexylamine; Diamines such as tetramethylethylenediamine, tetramethylpropanediamine and tetramethylhexanediamine; Pentamethyldiethylenetriamine and penta Triamines such as methyldipropylenetriamine and tetramethylguanidine; triethylenediamine, dimethylpiperazine, methylethylpiperazine, methylmorpholine, di Cyclic amines such as tilaminoethylmorpholine and dimethylimidazole; alcohol amines such as dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methylhydroxyethylpiperazine and hydroxyethylmorpholine; bis (dimethylaminoethyl) ether; And ether amines such as ethylene glycol bis (dimethyl) aminopropyl ether. Of these catalysts, organotin compounds are preferred. These catalysts may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the catalyst used is preferably in the range of 0.001 to 2.0 parts by mass with respect to 100 parts by mass of the polyol or urethane prepolymer.

  Examples of the foam stabilizer that can be used for the urethane foam raw material include ionic surfactants and nonionic surfactants in addition to silicone foam stabilizers such as polyether-modified silicone oil. The amount of the foam stabilizer used is preferably in the range of 0.5 to 5.0 parts by mass with respect to 100 parts by mass of the polyol or urethane prepolymer.

  The above-mentioned elastomer raw material, preferably a urethane raw material foamed by mechanical stirring, is poured into a cylindrical mold in which a shaft is previously arranged and reacted and cured to obtain a roller body having an elastic layer on the outer periphery of the shaft. be able to.

The conductive roller of the present invention controls the chargeability and adhesion to the toner, reduces the frictional force with the photosensitive drum and the layered blade, etc., and prevents contamination of the photosensitive drum and the like by the elastic layer. One or more resin coating layers made of urethane resin are provided on the outer peripheral surface of the elastic layer.

  At least one of the resin coating layers constituting the conductive roller of the present invention is made of a urethane resin containing lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane, and if necessary fine particles And other known additives. In the conductive roller of the present invention, the resin coating layer other than the resin coating layer containing lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane is made of a urethane resin, and further, The same materials as those exemplified as the conductive agent used in the elastic layer may be included, and known additives such as fine particles may be included as necessary.

  In the resin coating layer adjacent to the elastic layer among the resin coating layers, a water-based urethane resin is preferable as the urethane resin. For example, a hydrophilic substituent in the main chain of the polyurethane skeleton is dispersed or dissolved in water. A water-dispersible urethane resin or a water-soluble urethane resin obtained by introducing a solvent or adding an emulsifier as necessary is more preferable. When such an aqueous urethane resin is applied, in the conductive roller of the present invention, the resin coating layer adjacent to the elastic layer is usually formed by applying a water-based paint containing an aqueous urethane resin to the elastic layer. In this case, since the solvent used for the paint is water, it can be produced by a technique that is friendly to the working environment. In addition, when a resin coating layer is formed using a paint containing a conventional organic solvent, there is a problem that the elastic layer is dissolved or damaged by the organic solvent. In the present invention, the resin coating layer adjacent to the elastic layer Since the aqueous urethane resin to be used does not use an organic solvent, dissolution / breakage of the elastic layer is suppressed, and curing of the elastic layer can be prevented. In addition, these urethane resins may be used independently and may be used in combination of 2 or more type.

  The water-dispersible urethane resin or water-soluble urethane resin is preferably an ultraviolet curable aqueous urethane resin. Here, the ultraviolet curable aqueous urethane resin is an aqueous urethane monomer and / or oligomer polymerizable by ultraviolet rays, preferably an aqueous urethane monomer having a carbon-carbon double bond polymerizable by ultraviolet rays and // Oligomer. The aqueous urethane monomer and / or oligomer having a carbon-carbon double bond that can be polymerized by ultraviolet rays is preferably an aqueous urethane (meth) acrylate monomer and / or oligomer. In addition, as long as an aqueous | water-based urethane type monomer and oligomer can melt | dissolve or disperse | distribute in water, all can be used.

  The urethane-based (meth) acrylate monomer and oligomer are obtained by urethanization of a polyol, an isocyanate compound and a (meth) acrylate compound having a hydroxyl group.

When the resin coating layer adjacent to the elastic layer is made of an ultraviolet curable aqueous urethane resin, the resin coating layer is formed by, for example, applying an aqueous paint containing an ultraviolet curable aqueous urethane resin to the outer peripheral surface of the elastic layer. It is formed by curing an ultraviolet curable aqueous urethane resin by ultraviolet irradiation. As a result, it is not necessary to prepare a long drying line for forming the resin coating layer, and furthermore, variations in characteristics of the resin coating layer due to variations in various conditions of the drying process can be eliminated. Here, the water-based paint preferably further contains a reactive diluent, a photopolymerization initiator, a photopolymerization accelerator and the like. Examples of a method for applying the water-based paint 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, a metal halide lamp, and a xenon lamp. Conditions of ultraviolet ray irradiation is appropriately selected depending on the type and coating amount of the ultraviolet-curable aqueous urethane resin, for example, irradiation intensity 10~2000mW / cm ^2, a range of integrated light quantity 50~2000mJ / cm ² is preferred.

  In the water-based paint containing the ultraviolet curable aqueous urethane resin, the viscosity of the water-based paint can be adjusted as appropriate by changing the amount of water used, but if necessary, the reactivity having a polymerizable double bond. A diluent may be contained. As the reactive diluent, a monofunctional, bifunctional or polyfunctional polymerizable compound having a structure in which (meth) acrylic acid is bonded by an esterification reaction or an amidation reaction to a compound containing an amino acid or a hydroxyl group is used. be able to. The amount of the reactive diluent in the water-based paint is preferably in the range of 10 to 200 parts by mass with respect to 100 parts by mass of the ultraviolet curable aqueous urethane resin.

  The water-based paint containing the ultraviolet curable aqueous urethane resin preferably contains a photopolymerization initiator, and the photopolymerization initiator is irradiated with ultraviolet rays so that the above-described urethane (meth) acrylate monomer or It has a function of initiating polymerization of urethane (meth) acrylate oligomer. Examples of the photopolymerization initiator include 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, 2,2-dimethoxy-2-phenylacetophenone, acetophenone diethyl ketal, alkoxyacetophenone, benzyldimethyl ketal, benzophenone and 3,3. -Dimethyl-4-methoxybenzophenone, benzophenone derivatives such as 4,4-dimethoxybenzophenone, 4,4-diaminobenzophenone, benzyl derivatives such as alkyl benzoylbenzoate, bis (4-dialkylaminophenyl) ketone, benzyl and benzylmethyl ketal Benzoin derivatives such as benzoin and benzoin isobutyl ether, benzoin isopropyl ether, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl 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, etc. It is done. These photoinitiators may be used individually by 1 type, and may use 2 or more types together. The blending amount of the photopolymerization initiator in the water-based paint is preferably in the range of 0.2 to 5.0 parts by mass with respect to 100 parts by mass of the ultraviolet curable aqueous urethane resin. When the blending amount of the photopolymerization initiator is 0.2 parts by mass or less, the effect of initiating UV curing of the UV curable aqueous urethane resin is small, whereas when it exceeds 5.0 parts by mass, the effect of initiating UV curing is saturated, Cost increases.

  When blending a photopolymerization initiator in the water-based paint, a tertiary amine photopolymerization accelerator such as triethylamine or triethanolamine, or a phosphine system such as triphenylphosphine is used to accelerate the polymerization reaction by the photopolymerization initiator. A photopolymerization accelerator, a thioether photopolymerization accelerator such as thiodiglycol, and the like may be further added to the water-based paint. The addition amount of these photopolymerization accelerators is preferably in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the ultraviolet curable aqueous urethane resin.

In the conductive roller of the present invention, at least one of the resin coating layers includes lithium bis (trifluoromethanesulfonyl) imide [Li (CF ₃ SO ₂ ) ₂ N] and / or lithium tris (trifluoromethanesulfonyl) as a conductive agent. It is necessary to contain methane [Li (CF ₃ SO ₂ ) ₃ C]. In the resin coating layer containing lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane, lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane It is preferable that a compounding quantity is 0.05-10 mass parts with respect to 100 mass parts of urethane resins. When the blending amount is less than 0.05 parts by mass, the conductive performance is not expressed. On the other hand, when it exceeds 10 parts by mass, the solubility in the resin is lowered.

  Furthermore, as the fine particles that can be used in the resin coating layer, inorganic fine particles such as rubber or synthetic resin fine particles, carbon fine particles, and silica-based fine particles are preferable. Silicone rubber, silicone resin, fluororesin, urethane resin, Particularly preferred are polyolefin resin, epoxy resin, polystyrene resin, epoxy resin, polystyrene resin, urethane acrylate, melamine resin, phenol resin, (meth) acrylic resin, fine particles made of glassy carbon, and silica fine particles. These fine particles may be used alone or in combination of two or more. Moreover, the blending amount of the fine particles is preferably in the range of 5 to 40 parts by mass with respect to 100 parts by mass of the urethane resin. Furthermore, the average particle diameter of the fine particles is preferably in the range of 3 to 20 μm.

  The total thickness of the resin coating layer is not particularly limited, but is preferably in the range of 5 to 100 μm. Here, the thickness refers to the average thickness. If the total thickness of the resin coating layer is less than 5 μm, the effect of disposing the resin coating layer is small, and if it exceeds 100 μm, the surface of the conductive roller becomes hard and the flexibility is impaired.

  The method for producing the developing roller of the present invention is not particularly limited, and a paint containing each component constituting the resin coating layer is prepared, and the paint is dipped, roll coater, doctor blade method, spray method or the like. Thus, after applying on the elastic layer of the roller main body obtained by the above method, a method of producing by drying or ultraviolet irradiation is suitably employed. In the production of the conductive roller of the present invention, it is preferable to reduce the number of steps in order to reduce the production cost. For example, the roller body composed of the shaft member and the elastic layer is once immersed in the paint. Then, it is preferable to form the resin coating layer by appropriately drying.

  As for the surface roughness of the conductive roller of the present invention, the JIS 10-point average roughness (Rz) is preferably 10 μm or less. When the JIS 10-point average roughness (Rz) of the conductive roller exceeds 10 μm, the toner transport amount tends to increase when used as a developing roller, but the toner charge amount is insufficient, and the image is subject to background fogging or Gradation defects will occur. The average roughness (Rz) can be controlled by selecting the average particle size and particle size distribution of the fine particles.

The resistance value of the conductive roller of the present invention is not particularly limited, but in order to obtain a good image, the electrical resistance is preferably 10 ³ to 10 ¹⁰ Ω, and 10 ⁴ to 10 ⁸ Ω. More preferably. If the resistance value of the conductive roller is less than 10 ³ Ω, gradation control is extremely difficult, and bias leakage may occur if the photosensitive drum is defective. On the other hand, if the resistance value of the conductive roller exceeds 10 ¹⁰ Ω, for example, when developing toner on the photosensitive drum, the developing bias causes a voltage drop due to the high resistance of the conductive roller itself, and the developing bias sufficient for development Cannot be secured, and a sufficient image density cannot be obtained. The resistance value can be measured, for example, by pressing the outer peripheral surface of the conductive roller against a flat plate or cylindrical counter electrode with a predetermined pressure, applying a voltage of 100 V between the shaft and the counter electrode, Can be sought. Thus, by appropriately and uniformly controlling the resistance value of the conductive roller, the electric field strength for moving the toner can be kept appropriate and uniform.

  The conductive roller of the present invention preferably has an Asker C hardness of 80 ° or less, more preferably 20 to 70 °. If the Asker C hardness of the conductive roller exceeds 80 °, the contact area between the conductive roller and the photosensitive drum may be reduced, and good development may not be performed. The conductive roller is used as a developing roller. In such a case, the toner is damaged, and the toner is fixed to the photosensitive drum or the stratified blade. On the other hand, if the conductive roller is too low in hardness, when the conductive roller is used as a developing roller, the frictional force with the photosensitive drum or the stratified blade increases, and image defects such as jitter may occur. The conductive roller is used in contact with a photosensitive drum, a stratified blade, or the like. Therefore, even when the hardness is set to a low hardness, it is preferable to reduce the compression set as much as possible, specifically 20%. The following is preferable.

<Image forming apparatus>
The image forming apparatus of the present invention includes the above-described conductive roller, and preferably includes the conductive roller as at least one of a developing roller, a charging roller, a toner supply roller, and a transfer roller. The image forming apparatus of the present invention is not particularly limited except that it includes the conductive roller, 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. 3 is a partial cross-sectional view of an example of the image forming apparatus of the present invention. The illustrated image forming apparatus includes a toner supply roller 8 for supplying toner 7, a photosensitive drum 9 holding an electrostatic latent image, and a developing roller disposed between the toner supply roller 8 and the photosensitive drum 9. 10, a stratification blade 11 provided in the vicinity (upper part in the drawing) of the developing roller 10, a charging roller 12 located in the vicinity (upper part in the figure), and a vicinity (lower part in the figure) of the photosensitive drum 9. And a cleaning unit 14 provided adjacent to the photosensitive drum 9. The image forming apparatus of the present invention can further include known components (not shown) that are normally used in the image forming apparatus.

  In the illustrated image forming apparatus, the charging roller 12 is brought into contact with the photosensitive drum 9 and a voltage is applied between the photosensitive drum 9 and the charging roller 12 to charge the photosensitive drum 9 to a constant potential. Then, an electrostatic latent image is formed on the photosensitive drum 9 by an exposure machine (not shown). Next, the toner supply roller 8, the photosensitive drum 9, and the developing roller 10 rotate in the direction of the arrow in the figure, so that the toner 7 on the toner supply roller 8 is sent to the photosensitive drum 9 through the developing roller 10. It is done. The toner 7 on the developing roller 10 is adjusted to a uniform thin layer by the stratifying blade 11 and rotates while the developing roller 10 and the photosensitive drum 9 are in contact with each other. It adheres to the electrostatic latent image and the latent image becomes visible. The toner 7 attached to the latent image is transferred to a recording medium such as paper by the transfer roller 13, and the toner 7 remaining on the photosensitive drum 9 after the transfer is removed by the cleaning blade 15 of the cleaning unit 14. Here, in the image forming apparatus of the present invention, at least one of the toner supply roller 8, the developing roller 10, the charging roller 12 and the transfer roller 13 has low environmental dependency and has excellent conductivity. In addition, it is possible to stably form an excellent image by using the conductive roller of the present invention in which the occurrence of bleed out is suppressed.

  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.

First, the roller main body which has the elastic layer of the specification common to Reference Examples 1-6, Example 7, and Comparative Examples 1-4 was produced based on the following prescription.

(Production of roller body)
100 parts by mass of an isocyanate component which is a polyol-modified tolylene diisocyanate having a NCO content of 6.7% prepolymerized with a polyether polyol, 2.0 parts by mass of conductive carbon black, a poly having an average functionality of 3 with a hydroxyl value of 37.0 mgKOH / g 21 parts by mass of ether polyol, 19 parts by mass of polyether polyol having a hydroxyl value of 388 mgKOH / g and an average number of functional groups of 3 and 5 parts by mass of reactive silicone foam stabilizer (polydimethylsiloxane / polyethylene oxide copolymer) having a hydroxyl value of 34 mgKOH / g Then, 0.3 parts by mass of sodium perchlorate and 0.2 parts by mass of dibutyltin dilaurate were mixed to prepare a polyurethane raw material. This polyurethane raw material was foamed by a mechanical floss method. By casting this foamed polyurethane raw material into a mold on which a metal shaft was set, a roller body having an elastic layer of urethane foam around the shaft was produced. The foaming ratio of the obtained urethane foam was 1.6 times.

( Reference Example 1)
100 parts by mass of water-dispersible urethane resin [Daiichi Kogyo Seiyaku Co., Ltd., trade name: Superflex 107M] and 0.1 parts by mass of lithium bis (trifluoromethanesulfonyl) imide are added to 20 parts by mass of purified water and stirred. The lower layer coating material A was prepared by stirring with a motor for 30 minutes. On the other hand, an organic solvent-based urethane resin paint [manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: NIPPON N5196] 100 parts by mass, carbon black 25 parts by mass, and urethane particles [manufactured by Negami Kogyo Co., Ltd., trade name: ART Pearl C800, 10 parts by mass of an average particle size of 8.8 μm] was dispersed in 300 parts by mass of methyl ethyl ketone (MEK), and stirred for 30 minutes with a stirring motor to prepare surface layer coating material A. Next, the lower layer coating material A is applied to the roller body having the elastic layer made of polyurethane foam and dried to form a first resin coating layer having an average thickness of 20 μm, and then the surface layer coating material A is applied. The conductive roller having the second resin coating layer having an average thickness of 10 μm was manufactured by drying and processing.

( Reference Example 2)
A conductive roller was produced in the same manner as in Reference Example 1 except that the amount of lithium bis (trifluoromethanesulfonyl) imide used in the lower layer coating material A was changed to 1 part by mass.

( Reference Example 3)
A conductive roller was produced in the same manner as in Reference Example 1 except that the amount of lithium bis (trifluoromethanesulfonyl) imide used in the lower layer coating material A was changed to 15 parts by mass.

( Reference Example 4)
A conductive roller was produced in the same manner as in Reference Example 1 except that the amount of lithium bis (trifluoromethanesulfonyl) imide used in the lower layer coating material A was changed to 20 parts by mass.

( Reference Example 5)
The amount of lithium bis (trifluoromethanesulfonyl) imide used in the lower layer coating material A was changed to 3 parts by mass, and instead of 25 parts by mass of carbon black in the surface layer coating material A, 3 parts of lithium bis (trifluoromethanesulfonyl) imide was used. A conductive roller was produced in the same manner as in Reference Example 1 except that the part was used.

( Reference Example 6)
Organic solvent-based urethane resin paint [manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: NIPPOLAN N5196], 5 parts by mass of lithium bis (trifluoromethanesulfonyl) imide, urethane particles [manufactured by Negami Kogyo Co., Ltd., Product name: Art Pearl C800, average particle size 8.8 μm] 10 parts by mass was dispersed in 300 parts by mass of methyl ethyl ketone (MEK) and stirred with a stirring motor for 30 minutes to prepare surface layer coating material B. Next, a conductive roller having a resin coating layer having an average thickness of 15 μm was prepared by coating and drying the surface layer paint B on a roller body having an elastic layer made of the polyurethane foam.

(Example 7)
Emulsion-type UV-curable aqueous urethane resin [Daiichi Kogyo Seiyaku Co., Ltd., trade name: R-5002, solid content 40%] 100 parts by mass, lithium bis (trifluoromethanesulfonyl) imide 3 parts by mass, urethane Particles [manufactured by Negami Kogyo Co., Ltd., trade name: Art Pearl C800, average particle size 8.8 μm] 10 mass and photopolymerization initiator [Ciba Specialty Chemicals Co., Ltd., trade name: Irgacure 1173] 1 part by mass Were dispersed in 70 parts by mass of purified water and stirred with a stirring motor for 30 minutes to prepare a surface layer coating material C. After that, the surface layer C is applied to the roller body having the elastic layer made of the polyurethane foam, dried at room temperature for 20 minutes, and then rotated in a nitrogen atmosphere, with an irradiation intensity of 50 mW / cm ² , integrated light quantity. A conductive roller having a resin coating layer with an average thickness of 10 μm was produced by irradiation with ultraviolet rays at 1000 mJ / cm ² .

(Comparative Example 1)
A conductive roller was produced in the same manner as in Reference Example 1 except that 3 parts by mass of lithium perchlorate was used instead of 0.1 part by mass of lithium bis (trifluoromethanesulfonyl) imide in the lower layer coating material A.

(Comparative Example 2)
A conductive roller was produced in the same manner as in Reference Example 1, except that 15 parts by mass of carbon black was used instead of 0.1 parts by mass of lithium bis (trifluoromethanesulfonyl) imide in the lower layer coating material A.

(Comparative Example 3)
A conductive roller was produced in the same manner as in Reference Example 6, except that 3 parts by mass of lithium perchlorate was used instead of 5 parts by mass of lithium bis (trifluoromethanesulfonyl) imide in the coating material B for surface layer.

(Comparative Example 4)
A conductive roller was produced in the same manner as in Example 7 except that 3 parts by mass of lithium perchlorate was used instead of 3 parts by mass of lithium bis (trifluoromethanesulfonyl) imide in the coating material C for the surface layer.

  Next, Asker C hardness, roller resistance, JIS 10-point average roughness (Rz), contamination of the photosensitive drum, and image characteristics of the obtained conductive roller were measured and evaluated by the following methods. The results are shown in Tables 1 and 2.

(1) Asker C hardness The surface hardness of the conductive roller was measured using a micro rubber hardness meter MD-1 [manufactured by Kobunshi Keiki Co., Ltd.].

(2) Roller resistance The conductive roller is pressed against the SUS drum with a load of 1 kgf, 23 ° C x 60% RH (N / N), 15 ° C x 10% RH (L / L), 30 ° C x 85% RH (H / H) for 24 hours in each environment, and then measured using ADVANTEST-R8340 (manufactured by Advantest) in the same environment.

(3) Surface roughness JIS 10-point average roughness (Rz) was determined based on JIS B0601.

(4) Contamination of the photosensitive drum The conductive roller is pressed against the photosensitive drum with a load of 1 kgf and stored for one week in a high-temperature and high-humidity environment of 40 ° C. × 95% RH. The image of the developing roller and the contact portion was judged according to the following criteria.
A case where no contamination of the photosensitive drum was observed was indicated by “◯”, a case where slight contamination of the photosensitive drum was observed was indicated by “△”, and a case where contamination of the photosensitive drum was observed by bleeding was indicated by “X”.

(5) Image density A conductive roller is incorporated in the cartridge as a developing roller, and it is in a low-temperature, low-humidity (L / L) environment (15 ° C, 10% RH), in a high-temperature, high-humidity (H / H) environment (30 ° C, 80% RH), continuous image formation with a printing rate of 2% was performed with a color LBP4700dn manufactured by Hewlett-Packard Co., and solid images and halftone images were formed initially and after printing 5000 sheets. The solid image and the halftone image were visually judged according to the following criteria.
“◯” indicates that there is no density unevenness, “Δ” indicates that there is slight density unevenness, and “x” indicates that there is density unevenness.

(6) Fog resistance During printing of a solid white image, the printer was forcibly stopped, and the amount of toner flying to the photosensitive drum in the white background portion was evaluated by density comparison by tape transfer. In addition, the relative density with respect to the white background part of 0.00 was measured using the Macbeth densitometer, and the following reference | standard judged.
A sample having a relative concentration of less than 0.15 was indicated by “◯”, a sample having a relative concentration of 0.15 or more and less than 0.20 was designated by “Δ”, and a sample having a relative concentration of 0.20 or more by “X”.

* 1 A resin coating layer using lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane as a conductive agent.
* 2 Resin coating layer using lithium perchlorate as a conductive agent.
* 3 Resin coating layer using carbon black as a conductive agent.

As is clear from the results in Tables 1 and 2, Examples and References in which lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane were selected as the conductive agent in at least one of the resin coating layers examples of the conductive roller, compared to the conductive roller of the comparison example were selected conventional ion conductive agent or electronic conductive agent as a conductive agent, without contaminating the photosensitive drum, it is understood that the image characteristics are good .

It is sectional drawing of an example of the electroconductive roller of this invention. It is sectional drawing of the other example of the electroconductive 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

1 conductive roller 2 shaft 3 elastic layer 4 urethane resin of the resin coating layer 5 conductive roller 6a urethane resin of the resin coating layer 6b urethane resin of the resin coating layer 7 Toner 8 Toner supply roller 9 photosensitive drum 10 the developing roller 11 Laminating blade 12 Charging roller 13 Transfer roller 14 Cleaning unit 15 Cleaning blade

Claims (3)

In a conductive roller comprising a shaft, an elastic layer formed on the outer periphery of the shaft, and one or more resin coating layers made of urethane resin formed on the outer peripheral surface of the elastic layer,
At least one of the resin coating layers contains lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane ,
The resin coating layer adjacent to the elastic layer is made of water-dispersible urethane resin or water-soluble urethane resin,
The conductive roller, wherein the water-dispersible urethane resin or water-soluble urethane resin is an ultraviolet curable aqueous urethane resin .   The resin coating layer containing the lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris (trifluoromethanesulfonyl) methane is lithium bis (trifluoromethanesulfonyl) imide and / or lithium tris with respect to 100 parts by mass of the urethane resin. The conductive roller according to claim 1, comprising 0.05 to 10 parts by mass of (trifluoromethanesulfonyl) methane. Image forming apparatus comprising a conductive roller according to claim 1 or 2.

Images