JP2012159554A - Conductive roller, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive roller that forms images without fogging in a low-humidity environment, and an image forming apparatus.SOLUTION: Provided is a conductive roller 1 comprising an elastic layer 3 formed on an outer peripheral surface of a shaft body 2, and an urethane coat layer 4 formed on the outer peripheral surface of the elastic layer 3. The urethane coat layer 4 contains an urethane resin, and 1-20 parts by mass of phosphonium-based ionic liquid relative to 100 parts by mass of the urethane resin. Also provided is an image forming apparatus comprising the conductive roller 1.

Description

  The present invention relates to a conductive roller and an image forming apparatus, and more particularly to a conductive roller and an image forming apparatus capable of forming an image without fogging even in a low humidity environment.

  Various image forming apparatuses using an electrophotographic system are employed in printers such as laser printers and video printers, copiers, facsimiles, and multi-function machines thereof. An image forming apparatus using an electrophotographic system includes various types of rollers. Examples of the various rollers include a conductive roller having conductivity or semi-conductivity, and an elastic roller having relatively low hardness. Specifically, the conductive roller includes a charging roller for uniformly charging an image carrier such as a photoconductor, a developing roller for carrying and transporting the developer and supplying the developer to the image carrier, and a developer on the developing roller. Examples thereof include a developer supply roller that is supplied while being charged, and a fixing roller that fixes a developer image transferred to a recording material such as recording paper. These various rollers usually have different characteristics, such as hardness, electrical resistivity, etc., depending on their functions and applications.

  As such a conductive roller, for example, Patent Document 1 discloses a “semiconductive member characterized by containing an ionic liquid”, specifically, “methylimidazolium salt and vinyl monomer or (meth)”. "Charging roll containing acrylate" is described (Example).

Patent Document 2 is characterized in that “(A) to (C) as an essential component is used for at least a part of a conductive member, the conductive composition for electrophotographic equipment is characterized in that Conductive member for electrophotographic equipment.
(A) Matrix polymer.
(B) At least one conductive filler selected from the group consisting of metal oxides, metal carbides, and carbon black having a DBP adsorption amount of 100 ml / 100 g or more.
(C) Ionic liquid. Is described.

  Patent Document 2 specifically describes “developing roll having a base layer containing a silicone polymer and 1-hexyl-3-methylimidazolium trifluoromethanesulfonate” (Example 16).

  By the way, if the surrounding environment where the image forming apparatus is installed changes, the environment inside the image forming apparatus also changes. Therefore, the characteristics of the conductive roller mounted inside the image forming apparatus may change, and the initial function may not be sufficiently exhibited. is there.

  For example, in the case of a developing roller, if the humidity around the developing roller decreases, a predetermined amount of developer charged to a predetermined charge amount cannot be supplied to the image carrier, and a solid white image (a solid image) is formed. In some cases, an unnecessary developer may be fixed (called fogging). This phenomenon is particularly noticeable when a color image is printed after a monochrome image is printed. As described above, when the peripheral environment of the roller mounted on the image forming apparatus changes, for example, when the peripheral humidity of the developing roller decreases, a desired image may not be obtained.

JP 2004-191655 A Japanese Patent Laid-Open No. 2005-220317 JP 2006-193704 A

  An object of the present invention is to provide a conductive roller and an image forming apparatus capable of forming an image without fogging even in a low humidity environment.

  The inventors of the present application speculate that the fog in a low humidity environment may be affected by the charge amount of the developer supplied to the image carrier, and pay attention to the “static elimination function” exhibited by the developing roller. As a result of intensive studies, it has been found that the inclusion of a specific amount of ionic liquid in the coating layer of a conductive roller used as a developing roller, particularly a urethane coating layer, can substantially prevent the occurrence of fog even in a low humidity environment. I found it.

Therefore, as means for solving the above problems,
Claim 1 is a conductive roller comprising an elastic layer formed on an outer peripheral surface of a shaft body and a urethane coat layer formed on the outer peripheral surface of the elastic layer, wherein the urethane coat layer is made of urethane resin And 1 to 20 parts by mass of a phosphonium-based ionic liquid with respect to 100 parts by mass of the urethane resin.
A second aspect of the present invention is an image forming apparatus comprising the conductive roller according to the first aspect.

  Since the conductive roller according to the present invention includes a urethane resin layer and a urethane coat layer containing 1 to 20 parts by mass of a phosphonium-based ionic liquid with respect to 100 parts by mass of the urethane resin, normal humidity Of course, the occurrence of fogging can be substantially suppressed even in a low humidity environment (for example, about 50% relative humidity). The image forming apparatus according to the present invention includes the conductive roller according to the present invention.

  Therefore, according to the present invention, it is possible to provide a conductive roller and an image forming apparatus that can form an image without fogging even in a low humidity environment.

FIG. 1 is a perspective view showing an example of a conductive roller according to the present invention. FIG. 2 is a schematic view showing an example of an image forming apparatus according to the present invention.

  The conductive roller according to the present invention includes an elastic layer formed on the outer peripheral surface of the shaft body, and a urethane coat layer formed on the outer peripheral surface of the elastic layer and containing a phosphonium-based ionic liquid and a urethane resin in a predetermined ratio. It is equipped with. When the urethane coat layer containing the ionic liquid in the content is provided on the outer peripheral surface of the elastic layer, the object of the present invention can be achieved well as described above. In the present invention, the low humidity environment means that the relative humidity of the environment is, for example, 20% or less, and preferably 15% or less in that the object of the present invention can be satisfactorily achieved.

  An example of the conductive roller according to the present invention will be described. As shown in FIG. 1, the conductive roller as an example of the conductive roller according to the present invention includes a shaft body 2, an elastic layer 3, and a urethane coat layer 4.

  The shaft body 2 is basically the same as a shaft body in a conventionally known conductive roller. The shaft body 2 is a so-called “core metal” composed of iron, aluminum, stainless steel, brass, or the like, and has good conductive characteristics. The shaft body 2 may be a shaft body made conductive by plating an insulating core body such as a thermoplastic resin or a thermosetting resin.

  The elastic layer 3 is basically the same as the elastic layer in a conventionally known conductive roller. The elastic layer 3 is formed by curing a conductive composition described later on the outer peripheral surface of the shaft body 2, and preferably has a JIS A hardness of 20 to 70. When the elastic layer 3 has a JIS A hardness (JIS K6301) of 20 to 70, the contact area between the conductive roller 1 and the contacted body can be increased, and the rebound resilience of the elastic layer 3 can be increased. And compression set is excellent.

The elastic layer 3 preferably has a volume resistivity in the range of 10 ¹ to 10 ⁷ Ω · cm and / or an electrical resistivity in the range of 10 ¹ to 10 ⁹ Ω. When the volume resistivity and / or electrical resistivity of the elastic layer 3 is within the above range, the developer is supported and supplied as desired when the conductive roller 1 is mounted on the image forming apparatus, and the desired quality is obtained. It is possible to contribute to forming an image having The volume resistivity can be measured according to a method defined in JIS K6911 (applied voltage is 100 V). The electrical resistivity is, for example, using an electrical resistance meter (trade name: ULTRA HIGH RESISTANCE METER R8340A, manufactured by Advantest Co., Ltd.), placing the conductive roller 1 horizontally, a thickness of 5 mm, a width of 30 mm, and A gold-plated plate having a length on which the entire elastic layer 3 of the conductive roller 1 can be placed is used as an electrode, and a load of 500 g is supported on both ends of the shaft 2 in the conductive roller 1. Then, DC100V is applied between the shaft body 2 and the electrode, the value of the electric resistance meter after 1 second is read, and the measurement can be performed according to the method of setting this value as the electric resistance value.

  The thickness of the elastic layer 3 is preferably 1 mm or more in that a uniform nip width between the contacted body and the elastic layer 3 can be secured in the contact state with the contacted body. It is particularly preferably 5 mm or more. On the other hand, the upper limit of the thickness of the elastic layer 3 is not particularly limited as long as the outer diameter accuracy of the elastic layer 3 is not impaired. Generally, if the thickness of the elastic layer 3 is excessively increased, the production cost of the elastic layer 3 increases. In consideration of practical production costs, the thickness of the elastic layer 3 is preferably 30 mm or less, and more preferably 20 mm or less. The thickness of the elastic layer 3 is appropriately selected according to the hardness of the elastic layer 3, such as JIS A hardness, in order to achieve a desired nip width.

  The conductive composition forming the elastic layer 3 contains rubber, a conductivity imparting agent, and various additives as desired. Examples of the rubber include silicone or silicone-modified rubber, nitrile rubber, ethylene propylene rubber (including ethylene propylene diene rubber), styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene rubber, butyl rubber, and epichlorohydrin. Examples thereof include rubbers such as rubber, urethane rubber, and fluorine rubber. Silicone or silicone-modified rubber or urethane rubber is preferable, and silicone or silicone-modified rubber is particularly preferable in terms of excellent heat resistance and charging characteristics. These rubbers may be liquid or millable. The electroconductivity imparting agent is not particularly limited as long as it has electroconductivity, and examples thereof include electroconductive powder such as electroconductive carbon, carbon for rubber, metal, and electroconductive polymer. Various additives include, for example, auxiliary agents such as chain extenders and crosslinking agents, catalysts, dispersants, foaming agents, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softening agents, Examples thereof include a plasticizer, an emulsifier, a heat resistance improver, a flame retardant improver, an acid acceptor, a heat conductivity improver, a release agent, and a solvent.

  Preferred examples of the conductive composition include addition curable millable conductive silicone rubber compositions and addition curable liquid conductive silicone rubber compositions. The addition-curable millable conductive silicone rubber composition is (A) an organopolysiloxane represented by the following average composition formula (1), (B) a filler, and (C) other than those belonging to the component (B). The conductive material is contained.

R _n SiO _{(4-n) / 2} (1)
Here, R is a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different, preferably a monovalent hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms. Yes, n is a positive number from 1.95 to 2.05.

  R is, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group and a dodecyl group, a cycloalkyl group such as a cyclohexyl group, an alkenyl such as a vinyl group, an allyl group, a butenyl group and a hexenyl group. Group, aryl groups such as phenyl and tolyl groups, aralkyl groups such as β-phenylpropyl group, and part or all of hydrogen atoms bonded to carbon atoms of these groups are substituted with halogen atoms or cyano groups A chloromethyl group, a trifluoropropyl group, a cyanoethyl group, etc. are mentioned.

  In the (A) organopolysiloxane, the molecular chain end is preferably blocked with a trimethylsilyl group, a dimethylvinyl group, a dimethylhydroxysilyl group, a trivinylsilyl group or the like. This organopolysiloxane preferably has at least two alkenyl groups in the molecule, and specifically, 0.001 to 5 mol%, particularly 0.01 to 0.5 mol% of alkenyl groups in R. It is preferable to have a vinyl group. In particular, when a platinum catalyst and an organohydrogenpolysiloxane are used in combination as a curing agent described later, an organopolysiloxane having such an alkenyl group is usually used.

  This (A) organopolysiloxane is obtained by cohydrolyzing and condensing one or more selected organohalosilanes or cyclic polysiloxanes such as siloxane trimers or tetramers. Can be obtained by ring-opening polymerization using an alkaline or acidic catalyst. This (A) organopolysiloxane is basically a linear diorganopolysiloxane, but may be partially branched. Further, it may be a mixture of two or more different molecular structures. This (A) organopolysiloxane usually has a viscosity of 100 cSt or more at 25 ° C., preferably 100,000 to 10,000,000 cSt. The degree of polymerization of (A) organopolysiloxane is usually 100 or more, preferably 3,000 or more, and the upper limit is preferably 100,000, and more preferably 10,000.

The (B) filler is not particularly limited, but a silica-based filler can be used. Examples of the silica-based filler include fumed silica or precipitated silica, and surface-treated silica having a high reinforcing effect, which is surface-treated with a silane coupling agent represented by a general formula RSi (OR ′) _3. System fillers are preferred. Here, R in the general formula is a glycidyl group, vinyl group, aminopropyl group, methacryloxy group, N-phenylaminopropyl group, mercapto group or the like, and R ′ in the general formula is a methyl group or an ethyl group. . The silane coupling agent represented by the general formula can be easily obtained, for example, as trade names “KBM1003” and “KBE402” manufactured by Shin-Etsu Chemical Co., Ltd. Such a silica-based filler surface-treated with a silane coupling agent can be obtained by treating the surface of the silica-based filler according to a conventional method. In addition, a commercial item may be used for the silica type filler surface-treated with the silane coupling agent. M.M. A trade name “Zeothix 95” manufactured by HUBER Co., Ltd. is available. The compounding amount of the silica-based filler is preferably 11 to 39 parts by mass, particularly preferably 15 to 35 parts by mass with respect to 100 parts by mass of the (A) organopolysiloxane. The average particle size of the silica-based filler is preferably 1 to 80 μm, and particularly preferably 2 to 40 μm. The average particle diameter of the silica-based filler can be measured as a weight average value (or median diameter) or the like using, for example, a particle size distribution measuring apparatus such as a laser light diffraction method.

  The (C) conductive material is a conductive material that does not belong to the filler (B), and even if it is made of the same material physically and chemically, it is defined as a filler (B). The conductive material that is different in form and state from the filler belongs to (C) the conductive material. Such an electroconductive material is an electroconductivity imparting component, for example, the said electroconductivity imparting agent is mentioned, Among these, carbon black is preferable. A conductive material may be used independently or may use 2 or more types together.

  The addition-curable millable conductive silicone rubber composition may contain additives and the like within a range that does not impair the object of the present invention. Examples of additives include a curing agent, a colorant, a heat improver such as iron octylate, iron oxide, and cerium oxide, an acid acceptor, a thermal conductivity improver, a release agent, an alkoxysilane, and a degree of polymerization of organopolysiloxane. (A) Lower dimethylsiloxane oil and silanol, such as diphenylsilanediol, α, ω-dimethylsiloxanediol, etc. Examples thereof include various carbon functional silanes for curing and various cured or uncured olefin elastomers that do not inhibit the crosslinking reaction.

The addition-curable liquid conductive silicone rubber composition comprises (D) an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and (E) bonded to silicon atoms in one molecule. An organohydrogenpolysiloxane containing at least two hydrogen atoms; (F) an inorganic filler having an average particle size of 1 to 30 μm and a bulk density of 0.1 to 0.5 g / cm ³ ; and (G). An addition-curable liquid conductive silicone rubber composition containing a conductivity imparting agent and (H) an addition reaction catalyst can be mentioned.

As said (D) organopolysiloxane, the compound shown by the following average compositional formula (2) is suitable.
R ¹ _a SiO _{(4-a) / 2} (2)
Here, R ¹ in the average composition formula (2) is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, which are the same or different from each other, and a is It is a positive number in the range of 1.5 to 2.8, preferably 1.8 to 2.5, more preferably 1.95 to 2.02.

R ¹ represents an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or one of these hydrogen atoms, as exemplified by R of the organopolysiloxane (A) contained in the addition-curable millable conductive silicone rubber composition. Examples include hydrocarbon groups in which part or all are substituted with halogen atoms or cyano groups. At least two of R ¹ are alkenyl groups, particularly vinyl groups, and preferably 90% or more are methyl groups. Specifically, the alkenyl group content in the organopolysiloxane is 1.0 × 10 ^{−6 to} 5.0 × 10 ⁻³ mol / g, particularly 5.0 × 10 ^{−6 to} 1.0 × 10 ^−. It is preferably ³ mol / g.

  (D) The degree of polymerization of the organopolysiloxane is liquid at room temperature (25 ° C.) (for example, the viscosity at 25 ° C. is 100 to 1,000,000 mPa · s, preferably about 200 to 100,000 mPa · s). The average degree of polymerization is preferably 100 to 800, and particularly preferably 150 to 600.

The (E) organohydrogenpolysiloxane is represented by the following average composition formula (3), and is at least 2, preferably 3 or more (usually 3 to 200), more preferably 3 to 100 in one molecule. Those having hydrogen atoms bonded to silicon atoms are preferably used.
R ² _b H _c SiO _{(4-bc) / 2} (3)
Here, R ² in the average composition formula (3) is the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms. B is 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number satisfying 0.8 to 3.0.

  The content of hydrogen atoms (Si—H) bonded to the silicon atoms is preferably 0.001 to 0.017 mol / g, particularly 0.002 to 0.015 mol / g in the organohydrogenpolysiloxane.

Examples of the organohydrogenpolysiloxane (E) include a trimethylsiloxy group-capped methylhydrogen polysiloxane at both ends, a trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer at both ends, and a dimethylhydrogensiloxy group-capped dimethyl at both ends. Polysiloxane, both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane diphenylsiloxane-dimethylsiloxane copolymers, copolymers consisting of (CH _{3) 2} HSiO _1/2 units and SiO _4/2 units, and, (CH _{3) 2} H iO _1/2 unit and the SiO _4/2 units (C ₆ H ₅₎ copolymers composed of SiO _3/2 units and the like.

  The compounding amount of the organohydrogenpolysiloxane (E) is preferably 0.1 to 30 parts by mass, particularly 0.3 to 20 parts by mass with respect to 100 parts by mass of the (D) organopolysiloxane. preferable. (D) The molar ratio of hydrogen atoms bonded to silicon atoms relative to the alkenyl groups of the organopolysiloxane is preferably 0.3 to 5.0, particularly preferably 0.5 to 2.5. .

The (F) inorganic filler is an important component for obtaining low roller permanent set, volume resistivity being stable over time, and sufficient roller durability. The inorganic filler has an average particle size of 1 to 30 μm, preferably 2 to 20 μm, and a bulk density of 0.1 to 0.5 g / cm ³ , preferably 0.15 to 0.45 g / cm ³ . If the average particle size is less than 1 μm, the electrical resistivity may change over time, and if it is greater than 30 μm, the durability of the elastic layer 3 may be reduced. If the bulk density is less than 0.1 g / cm ³ , the compression set may deteriorate and the electrical resistivity may change over time. If it exceeds 0.5 μm, the elastic layer 3 has insufficient strength and is durable. May decrease. The average particle diameter can be determined as a weight average value (or median diameter), for example, using a particle size distribution measuring device such as a laser diffraction method, and the bulk density is a measurement of the apparent specific gravity according to JIS K 6223. It can be determined based on the method.

  Examples of such an inorganic filler (F) include diatomaceous earth, pearlite, mica, calcium carbonate, glass flakes, and hollow filler, among which diatomaceous earth, pearlite, and foamed pearlite are preferable.

  (F) It is preferable that the compounding quantity of an inorganic filler is 5-100 mass parts with respect to 100 mass parts of (D) organopolysiloxane, and it is especially preferable that it is 10-80 mass parts.

  The said (G) electroconductivity imparting agent is the same as that of the said electroconductivity imparting agent, The compounding quantity can be 2-80 mass parts with respect to 100 mass parts of (D) organopolysiloxane.

  Examples of the (H) addition reaction catalyst include platinum black, platinous chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and an olefin, platinum bisacetoacetate, palladium And a rhodium-based catalyst. In addition, the compounding quantity of this (H) addition reaction catalyst can be made into a catalyst quantity, for example, as a platinum group metal quantity, it is with respect to the total mass of (D) organopolysiloxane and (E) organohydrogenpolysiloxane. 0.5 to 1,000 ppm is preferable, and about 1 to 500 ppm is particularly preferable.

  This addition curable liquid conductive silicone rubber composition is a low molecular siloxane ester, a silanol, for example, a dispersant such as diphenylsilanediol, an improved heat resistance such as iron oxide, cerium oxide, iron octylate, etc. Agents, various carbon functional silanes that improve adhesion and moldability, halogen compounds that impart flame retardancy, and the like may be included within a range that does not impair the object of the present invention.

  The addition curable liquid conductive silicone rubber composition may have a viscosity of 5 to 500 Pa · s, particularly preferably 5 to 200 Pa · s, at 25 ° C.

  The urethane coat layer 4 is formed by curing a urethane resin composition, which will be described later, on the outer peripheral surface of the elastic layer 3, and contains a phosphonium-based ionic liquid in a ratio of 1 to 20 parts by mass with respect to 100 parts by mass of the urethane resin. ing.

  The ionic liquid contained in the urethane coat layer 4 is a kind of onium salt, and is a liquid compound having a high conductivity that is in a liquid state at a temperature at least near room temperature, and is also referred to as an “ionic liquid”. The In the present invention, it is important that the ionic liquid is a phosphonium-based ionic liquid among various ionic liquids. When the ionic liquid is a phosphonium-based ionic liquid, the occurrence of fogging in a low humidity environment can be substantially suppressed, and the object of the present invention can be achieved well.

  The phosphonium-based ionic liquid contains, as cations, tributyloctylphosphonium, tributylnonylphosphonium, tributyldecylphosphonium, tributylundecylphosphonium, tributyldodecylphosphonium, tributyltridecylphosphonium, tributyltetradecylphosphonium, tributylpentadecylphosphonium, tributylhexadecyl Phosphonium, tributylheptadecylphosphonium, tributyloctadecylphosphonium, tributylnonadecylphosphonium, tributylicosylphosphonium, tripentyloctylphosphonium, tripentylnonylphosphonium, tripentyldecylphosphonium, tripentylundecylphosphonium, tripentyldodecylphosphonium, tripentyl Ridecylphosphonium, tripentyltetradecylphosphonium, tripentylpentadecylphosphonium, tripentylhexadecylphosphonium, tripentylheptadecylphosphonium, tripentyloctadecylphosphonium, tripentylnonadecylphosphonium, tripentylicosylphosphonium, trihexyloctylphosphonium, Trihexyl nonyl phosphonium, trihexyl decyl phosphonium, trihexyl undecyl phosphonium, trihexyl decyl phosphonium, trihexyl tridecyl phosphonium, trihexyl pentadecyl phosphonium, trihexyl hexadecyl phosphonium, trihexyl heptadecyl phosphonium, trihexyl octadecyl phosphonium, Trihexyl nonadecylphos Nium, trihexylicosylphosphonium, triheptyloctylphosphonium, triheptylnonylphosphonium, triheptyldecylphosphonium, triheptylundecylphosphonium, triheptyldodecylphosphonium, triheptyltridecylphosphonium, triheptyltetradecylphosphonium, triheptylpentadecyl Phosphonium, triheptylhexadecylphosphonium, triheptylheptadecylphosphonium, triheptyloctadecylphosphonium, triheptylnonadecylphosphonium, triheptylicosylphosphonium, tetraoctylphosphonium, trioctylnonylphosphonium, trioctyldecylphosphonium, trioctylundecylphosphonium , Trioctyldodecylphosphonium , Trioctyltridecylphosphonium, trioctyltetradecylphosphonium, trioctylpentadecylphosphonium, trioctylhexadecylphosphonium, trioctylheptadecylphosphonium, trioctyloctadecylphosphonium, trioctylnonadecylphosphonium, trioctylicosylphosphonium, tetramethyl Examples include phosphonium, tetraethylphosphonium, tetrapropylphosphonium, tetrabutylphosphonium, tetrapentylphosphonium, tetrahexylphosphonium, tetraheptylphosphonium, tetraoctylphosphonium, tetranonylphosphonium, tetradecylphosphonium, and tetraphenylphosphonium.

The anion constituting the phosphonium-based ionic liquid is not particularly limited. For example, a halogen ion, BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ (trifluoromethanesulfonyl ion), (CF ₃ SO ₂ ) ₂ N ^- (bis (trifluoromethanesulfonyl) imide _{ion: TFSI), CH 3 C 6} H 4 SO 3 - include (toluenesulfonic acid) and the like. Among these, organic acid anions BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ and CH ₃ C ₆ H ₄ SO ₃ ⁻ are preferable, and (CF ₃ SO _{2) 2} N ^-, and _{CH 3 C 6 H 4 SO 3} - is particularly preferable.

  Specific examples of the phosphonium-based ionic liquid include tributylmethylphosphonium = bistrifluoromethanesulfonium imide, triethyloctylphosphonium = bistrifluoromethanesulfonium imide, tripropyloctylphosphonium = bistrifluoromethanesulfonium imide, tributyloctylphosphonium = bistrifluoromethane. Sulfoniumimide, tributyldodecylphosphonium = bistrifluoromethanesulfoniumimide, tetrabutylphosphonium methylsulfate, tetrabutylphosphonium nitrate, tetrabutylmethylphosphonium = bistrifluoromethanesulfoniumimide, tetrabutylphosphonium = bistrifluoromethanesulfoniumimide, tetrabutylphosphonium -P-tor Sulfonate, trihexyl tetradecylphosphonium bis (trifluoromethylsulfonyl) imide, trihexyl tetradecylphosphonium bis (2,2,4-trimethylpentyl) hypophosphite, trihexyl tetradecylphosphonium bromide, trihexyl tetradecyl Examples thereof include phosphonium chloride, trihexyl tetradecyl phosphonium decanoate, trihexyl tetradecyl phosphonium dicyanamide, trihexyl tetradecyl phosphonium hexafluorophosphate, trihexyl tetradecyl phosphonium tetrafluoroborate and the like.

  The urethane resin contained in the urethane coat layer 4 may be a known urethane resin and is usually obtained from polyol and polyisocyanate. The polyol is preferably a polyester polyol or a polyether polyol in that the object of the present invention can be well achieved. Examples of the polyisocyanate include aliphatic polyisocyanates and aromatic polyisocyanates.

  The urethane coat layer 4 may contain various additives usually used in various urethane resin compositions. A conductivity-imparting agent such as carbon black may be contained as an optional component.

  The urethane coat layer 4 contains the ionic liquid in an amount of 1 to 20 parts by mass, that is, 1 to 8 parts by mass and 8 to 20 parts by mass with respect to 100 parts by mass of the urethane resin. If the content of the ionic liquid is less than 1 part by mass, the effect of the ionic liquid may not be sufficiently obtained, and the object of the present invention may not be achieved. On the other hand, if the content of the ionic liquid exceeds 20 parts by mass, the charge of the charged toner may be lost and the toner may not be carried on the surface of the developing roller. As a result, when mounted on an image forming apparatus, fogging is likely to occur in a low humidity environment, and density unevenness is likely to occur in a halftone image, which may reduce the quality of the formed image. The occurrence of fog in a low humidity environment can be substantially suppressed, and the content of the ionic liquid is 9 to 19 parts by mass with respect to 100 parts by mass of the urethane resin in that the object of the present invention can be well achieved. Preferably there is.

  In general, the urethane coat layer 4 preferably has a layer thickness of 0.1 to 50 μm, and more preferably has a layer thickness of 10 to 25 μm.

  The urethane resin composition that forms the urethane coat layer 4 includes a urethane adjusting component that is a precursor that forms the urethane resin, and a predetermined amount, that is, 1 to 20 parts by mass of an ionic liquid with respect to 100 parts by mass of the urethane adjusting component. And various additives as desired. Therefore, the urethane coat layer 4 is formed by applying and curing a urethane resin composition containing a urethane adjusting component, a predetermined amount of ionic liquid, and optionally various additives to the outer peripheral surface of the elastic layer 3. The ionic liquid and various additives in the urethane resin composition are as described above.

  The urethane adjusting component may be any component that can form polyurethane, and examples thereof include a mixture of a polyol and an isocyanate.

  The polyol may be any of various polyols usually used in the preparation of polyurethane, and is preferably at least one polyol selected from polyether polyols and polyester polyols. Examples of the polyether polyol include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polypropylene glycol-ethylene glycol, polytetramethylene ether glycol, copolymer polyols of tetrahydrofuran and alkylene oxide, and various modified products thereof. These mixtures etc. are mentioned. Examples of the polyester polyol include condensed polyester polyols obtained by condensation of dicarboxylic acids such as adipic acid and polyols such as ethylene glycol and hexanediol, lactone polyester polyols, polycarbonate polyols, and mixtures thereof. Can be mentioned. The polyether polyol and polyester polyol may be used singly or in combination of two or more, or a polyether polyol and a polyester polyol may be used in combination. The polyol is preferably a polyester polyol because it is excellent in thermal stability. The polyol preferably has a number average molecular weight of 1000 to 8000, more preferably 1000 to 5000, in view of excellent compatibility with polyisocyanate and the like described later. The number average molecular weight is a molecular weight when converted to standard polystyrene by gel permeation chromatography (GPC).

  The isocyanate may be any of various isocyanates usually used for preparing polyurethane, and examples thereof include aliphatic isocyanate, aromatic isocyanate, and derivatives thereof. Isocyanate is preferably an aromatic isocyanate in terms of excellent storage stability and easy control of the reaction rate. Examples of the aromatic isocyanate include xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (also referred to as tolylene diisocyanate, TDI), 3,3′-bitolylen-4,4′-diisocyanate, 3, 3'-dimethyldiphenylmethane-4,4'-diisocyanate, 2,4-tolylene diisocyanate uretidine dione (dimer of 2,4-TDI), xylene diisocyanate, naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PDI) , Tolidine diisocyanate (TODI), metaphenylene diisocyanate and the like. Examples of the aliphatic isocyanate include hexamethylene diisocyanate (HDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), orthotoluidine diisocyanate, lysine diisocyanate methyl ester, isophorone diisocyanate (IPDI), norbornane diisocyanate methyl, transcyclohexane. -1,4-diisocyanate, triphenylmethane-4,4 ′, 4 ″ -triisocyanate and the like. Examples of the derivatives include polynuclear polyisocyanates, urethane-modified products modified with polyols (including urethane prepolymers), dimers formed by uretidione formation, isocyanurate-modified products, carbodiimide-modified products, uretonimine-modified products, and allophanates. Examples include modified products, urea-modified products, and burette-modified products. The said polyisocyanate can be used individually by 1 type or 2 or more types. The polyisocyanate preferably has a molecular weight of 500 to 2000, more preferably 700 to 1500.

  The mixing ratio in the mixture of polyol and polyisocyanate is not particularly limited, but usually the molar ratio (NCO / OH) of the hydroxyl group (OH) contained in the polyol to the isocyanate group (NCO) contained in the polyisocyanate is 0. 0.7 to 1.15 is preferred. This molar ratio (NCO / OH) is more preferably 0.85 to 1.10. From the viewpoint that hydrolysis of polyurethane can be prevented. However, in practice, an amount corresponding to 3 to 4 times the appropriate molar ratio may be blended in consideration of work environment and work errors.

  In addition to the polyol and the polyisocyanate, the urethane adjusting component may be used in combination with an auxiliary agent usually used for the reaction between the polyol and the polyisocyanate, such as a chain extender and a crosslinking agent. Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane, and amines.

  The conductive roller 1 is manufactured by forming the elastic layer 3 on the outer peripheral surface of the shaft body 2 and further forming the urethane coat layer 4 on the outer peripheral surface of the elastic layer 3. In order to manufacture the conductive roller 1, first, the shaft body 2 is prepared. For example, the shaft body 2 is prepared in a desired shape by a known method. The shaft body 2 may be coated with a primer before the elastic layer 3 is formed. Although there is no restriction | limiting in particular as a primer apply | coated to the shaft body 2, The resin similar to the material which forms the primer layer which adheres or adheres the said elastic layer 3 and the coating layer 4, and a crosslinking agent are mentioned. The primer is dissolved in a solvent or the like as desired, and is applied to the outer peripheral surface of the shaft body according to a conventional method such as a dipping method or a spray method.

  The elastic layer 3 is formed by heat-curing the conductive composition on the outer peripheral surface of the shaft body 2. For example, the elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 by performing heat curing and molding simultaneously or continuously by a known molding method. The method for curing the conductive composition may be any method that can apply heat necessary for curing the conductive composition, and the method for forming the elastic layer 3 may be continuous vulcanization by extrusion, pressing, molding by injection, etc. There is no particular limitation. For example, when the conductive composition is an addition curable millable conductive silicone rubber composition, for example, extrusion molding or the like can be selected, and the conductive composition is an addition curable liquid conductive silicone rubber composition. In this case, for example, a molding method using a mold can be selected. The heating temperature for curing the conductive composition is 100 to 500 ° C., particularly 120 to 300 ° C., in the case of an addition-curable millable conductive silicone rubber composition, and the time is several seconds to 1 hour, particularly 10 seconds or more. ~ 35 minutes or less is preferable, and in the case of an addition-curable liquid conductive silicone rubber composition, it is 100 to 300 ° C, particularly 110 to 200 ° C, and the time is 5 minutes to 5 hours, particularly 1 to 3 hours. Is preferred. In addition, in the case of an addition-curable millable conductive silicone rubber composition, if necessary, the curing conditions are about 100 to 200 ° C. for about 1 to 20 hours, and in the case of an addition-curable liquid conductive silicone rubber composition. Secondary vulcanization may be performed at 120 to 250 ° C. under curing conditions for about 2 to 70 hours. In addition, the conductive composition can be foamed and cured by a known method to easily form a sponge-like elastic layer having bubbles.

  The elastic layer 3 formed in this way has its surface polished and ground as desired to adjust the outer diameter, surface state, and the like. Further, the primer layer may be formed on the elastic layer 3 formed in this way before the urethane coat layer 4 is formed.

  The urethane coat layer 4 is formed by coating the urethane resin composition on the outer peripheral surface of the elastic layer 3 thus formed or the primer layer formed as desired, and then applying the urethane resin composition. An object is formed by heat curing. The application of the urethane resin composition includes, for example, a coating method in which a coating liquid of the urethane resin composition is applied, a dipping method in which the elastic layer 3 or the like is immersed in the coating liquid, and the coating liquid in the elastic layer 3 or the like. It is carried out by a known coating method such as a spray coating method for spraying on the surface. The urethane resin composition may be applied as it is, or applied to the urethane resin composition, for example, alcohols such as methanol and ethanol, aromatic solvents such as xylene and toluene, and ester solvents such as ethyl acetate and butyl acetate. You may apply the coating liquid which added volatile solvents, such as these, or water. The urethane resin composition thus coated may be cured by any method that can add heat or moisture necessary for curing the urethane resin composition. For example, the urethane resin composition is coated. And a method of heating the elastic layer 3 and the like with a heater, a method of leaving the elastic layer 3 and the like coated with the urethane resin composition under high humidity, and the like. The heating temperature when the urethane resin composition is heat-cured is, for example, 100 to 200 ° C., particularly 120 to 160 ° C., and the heating time is preferably 10 to 120 minutes, particularly preferably 30 to 60 minutes. In addition, instead of the coating, the urethane resin composition was laminated on the outer peripheral surface of the elastic layer 3 or the primer layer by a known molding method such as extrusion molding, press molding, injection molding, or the like. Later, a method of curing the laminated urethane resin composition or the like can be employed.

  The conductive roller 1 manufactured in this manner has a urethane coat layer 4 containing 100 parts by mass of urethane resin and 1 to 20 parts by mass of ionic liquid, that is, 1 to 20 parts by mass when the urethane resin is 100 parts by mass. Since the urethane coating layer 4 containing the ionic liquid is provided, the occurrence of fogging can be substantially suppressed not only in a normal humidity but also in a low humidity environment with a relative humidity of 10%, for example. The conductive roller 1 has such an excellent effect because the urethane coat layer 4 is used as the surface layer even when the developer supplied to the image carrier is excessively charged in a low humidity environment. If the conductive roller 1 is used as a developing roller, the conductive roller 1 effectively neutralizes the excessive charge amount charged in the developer, and the charge amount of the developer supplied to the image carrier is changed to a normal humidity environment. The inventors of the present application speculate that the charge amount may be almost the same as the lower charge amount.

  Further, the conductive roller 1 can substantially suppress the occurrence of fog even when the surrounding humidity changes from, for example, normal humidity to low humidity. Therefore, according to the present invention, it is possible to achieve the object of providing a conductive roller and an image forming apparatus that can form an image without fogging even when the surrounding humidity changes to low humidity.

  Thus, since the conductive roller 1 can substantially suppress the occurrence of fog even when the surroundings are at low humidity, for example, a developer charged to a desired charge amount can be uniformly applied to its surface. It is particularly preferably used as a developing roller and a developer supply roller that are required to exhibit the function and function of being supported in thickness and supplied to the image carrier.

  Next, an example of an image forming apparatus provided with the conductive roller 1 according to the present invention (hereinafter sometimes referred to as an image forming apparatus according to the present invention) will be described with reference to FIG. As shown in FIG. 2, the image forming apparatus 10 includes a plurality of image carriers 11B, 11C, 11M, and 11Y that are provided in the developing units B, C, M, and Y of the respective colors in series on the transfer conveyance belt 6. Therefore, the developing units B, C, M, and Y are arranged in series on the transfer conveyance belt 6. The developing unit B includes an image carrier 11B such as a photosensitive member (also referred to as a photosensitive drum), a charging unit 12B such as a charging roller, an exposure unit 13B, a developing unit 20B, and an image carrier via the transfer conveyance belt 6. A transfer unit 14B that contacts the body 11B, such as a transfer roller, and a cleaning unit 15B are provided. The developing unit 20B adjusts the thickness of the casing 21B that accommodates the one-component non-magnetic developer 22B, the developer carrier 23B that supplies the developer 22B to the image carrier 11B, such as a developing roller, and the thickness of the developer 22B. Developer amount adjusting means 24B, for example, a blade. The developing units C, M, and Y are basically configured in the same manner as the developing unit B. The fixing unit 30 is disposed on the downstream side of the developing unit Y. The fixing unit 30 includes a fixing roller 31, an endless belt support roller 33 disposed in the vicinity of the fixing roller 31, a fixing roller 31, and an endless belt support roller in a housing having an opening 35 through which the recording medium 16 passes. 33, an endless belt 36 wound around 33, and a pressure roller 32 disposed opposite to the fixing roller 31. The fixing roller 31 and the pressure roller 32 are in contact with or pressed against each other via the endless belt 36. It is a pressure heat fixing device which is supported in a freely rotatable manner. At the bottom of the image forming apparatus 10, a cassette 41 that houses the recording body 16 is installed. The transfer conveyance belt 6 is wound around a plurality of support rollers 42.

  Each of the developers 22B, 22C, 22M and 22Y used in the image forming apparatus 10 may be a dry developer or a wet developer as long as it can be charged by friction, and a non-magnetic developer or a magnetic developer. An agent may be used. One component non-magnetic black developer 22B, cyan developer 22C, magenta developer 22M and yellow developer 22Y are accommodated in the housings 21B, 21C, 21M and 21Y of the developing units. In the image forming apparatus 10, the conductive roller 1 is mounted as a developer carrier 23B, 23C, 23M and 23Y, that is, as a developing roller.

  The image forming apparatus 10 forms a color image on the recording body 16 as follows. First, in the developing unit B, an electrostatic latent image is formed by the exposure unit 13B on the surface of the image carrier 11B charged by the charging unit 12B, and the black electrostatic latent image is developed by the developer 22B supplied by the developer carrier 23B. The image is developed. The black electrostatic latent image is transferred to the surface of the recording medium 16B when the recording medium 16 passes between the transfer means 14B and the image carrier 11B. Next, in the same manner as in the developing unit B, a cyan image, a magenta image, and a yellow image are superimposed on the recording medium 16 in which the electrostatic latent image is visualized as a black image by the developing units C, M, and Y, respectively. A color image is visualized. Next, the recording body 16 in which the color image is visualized is fixed to the recording body 16 by the fixing unit 30 as a permanent image. In this way, a color image can be formed on the recording medium 16.

  In the tandem type image forming apparatus 10, when the conductive roller 1 according to the present invention is used as the developer carrying member 23, it is presumed that the conductive roller 1 can remove an excessive charge amount charged in the developer. The tandem type image forming apparatus 10 provided with the roller 1 can form a high-quality image substantially free of fog even in a low humidity environment of 10% relative humidity as well as normal humidity.

  The image forming apparatus 10 is an image forming apparatus such as a copying machine, a facsimile machine, or a printer. Although the image forming apparatus 10 has been described with reference to the example in which the conductive roller 1 according to the present invention is used as a developing roller as an example of the developer carrier 23, the conductive roller 1 according to the present invention is used as a developer supply roller. Even if the property roller 1 is used, a high-quality image can be similarly formed.

  The conductive roller and the image forming apparatus according to the present invention are not limited to the above-described embodiments, and various modifications can be made within a range in which the object of the present invention can be achieved.

  The conductive roller 1 according to the present invention may have another layer between the elastic layer 3 and the urethane coat layer 4. Examples of the other layer include a primer layer that adheres or adheres the elastic layer 3 and the urethane coat layer 4 to each other. Examples of materials for forming the primer layer include alkyd resins, phenol-modified / silicone-modified alkyd resin modified products, oil-free alkyd resins, acrylic resins, silicone resins, epoxy resins, fluororesins, phenol resins, polyamide resins, urethanes. Examples thereof include resins and mixtures thereof. Moreover, as a crosslinking agent which hardens and / or bridge | crosslinks these resin, an isocyanate compound, a melamine compound, an epoxy compound, a peroxide, a phenol compound, a hydrogen siloxane compound etc. are mentioned, for example. The primer layer is formed with a thickness of 0.1 to 10 μm, for example.

  The image forming apparatus 10 is an electrophotographic image forming apparatus. However, in the present invention, the image forming apparatus is not limited to the electrophotographic system, and may be, for example, an electrostatic image forming apparatus. Good. Further, the image forming apparatus provided with the conductive roller 1 according to the present invention is not limited to a tandem type color image forming apparatus in which a plurality of image carriers having developing units of respective colors are arranged in series on a transfer conveyance belt. For example, it may be a monochrome image forming apparatus provided with a single developing unit, a 4-cycle color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier onto an endless belt, and the like. . The developer 22 used in the image forming apparatus 10 is a one-component nonmagnetic developer. However, in the present invention, the developer 22 may be a one-component magnetic developer or a two-component nonmagnetic developer. Or a two-component magnetic developer.

Example 1
An electroless nickel-plated shaft body (SUM22, diameter 10 mm, length 275 mm) was washed with ethanol, and a silicone primer (trade name “Primer No. 16”, manufactured by Shin-Etsu Chemical Co., Ltd.) on its surface. ) Was applied. The shaft body subjected to the primer treatment was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the surface of the shaft body.

Next, 100 parts by mass of dimethylpolysiloxane (D) (polymerization degree 300) blocked at both ends with dimethylvinylsiloxy groups, and a hydrophobized fumed silica having a BET specific surface area of 110 m ² / g (Nippon Aerosil Co., Ltd.) Made by company, R-972) 1 part by mass, average particle size 6 μm, bulk density of 0.25 g / cm ³ diatomaceous earth (F) (Oplite W-3005S, manufactured by Kitaaki Diatomaceous Earth Co., Ltd.) 40 parts by mass, 5 parts by mass of acetylene black (G) (Denka Black HS-100, manufactured by Denki Kagaku Kogyo Co., Ltd.) was placed in a planetary mixer, stirred for 30 minutes, and then passed once through three rolls. This is returned to the planetary mixer again, and as a crosslinking agent, methyl hydrogen polysiloxane (E) having Si—H groups at both ends and side chains (polymerization degree 17, Si—H amount 0.0060 mol / g) 2. 1 part by mass, 0.1 part by mass of ethynylcyclohexanol as a reaction control agent and 0.1 part of platinum catalyst (H) (Pt concentration 1%) are added, and the mixture is stirred and kneaded for 15 minutes to be an addition curing type. A liquid conductive silicone rubber composition was prepared. The prepared addition-curable liquid conductive silicone rubber composition was molded on the outer peripheral surface of the shaft body 2 by liquid injection molding. In liquid injection molding, the addition-curable liquid conductive silicone rubber composition was cured by heating at 150 ° C. for 10 minutes. This molded body was polished to form an elastic layer 3 having an outer diameter of 20 mm.

  On the other hand, a urethane resin composition for forming the urethane coat layer 4 having the following composition was prepared.

-Polyisocyanate (hexamethylene diisocyanate) 14 parts by mass-Condensed polyester polyol (mixing molar ratio of 1,6-hexanediol and adipic acid [COOH / OH] = 12/13) 28 parts by mass (said isocyanate and polyester polyol (NCO / OH] = 1.1 / 1)
-As a ionic liquid, 1 part by mass of tetrabutylphosphonium-p-toluenesulfonate (manufactured by Sigma Aldrich Japan), which is a phosphonium-based ionic liquid-Carbon black (trade name "Toka Black # 4500", manufactured by Tokai Carbon Co., Ltd.) 3 Part by mass-As additive 1, dibutyltin dilaurate (trade name "di-n-butyltin dilaurate", manufactured by Showa Chemical Co., Ltd.) 0.03 parts by weight-As additive 2, silica (trade name "ACEMATT OK-607 "Degussa, Inc.) 4 parts by mass

  The urethane resin composition thus prepared was applied to the outer peripheral surface of the elastic layer 3 by a spray coating method and heated at 160 ° C. for 30 minutes to form a urethane coat layer 4 having a layer thickness of 22 μm. In this way, the conductive roller of Example 1 was manufactured.

(Examples 2 to 4)
Except having changed the content of the said ionic liquid into 2 mass parts, 4 mass parts, and 8 mass parts, it carried out similarly to Example 1, and manufactured the conductive roller of Examples 2-4, respectively.

(Comparative Example 1)
A conductive roller of Comparative Example 1 was produced basically in the same manner as in Example 1 except that the phosphonium-based ionic liquid was not contained.
(Comparative Example 2)
A conductive roller of Comparative Example 2 was produced basically in the same manner as in Example 1 except that the phosphonium-based ionic liquid was not contained and the content of the carbon black was changed to 6 parts by mass.

(Evaluation of fogging in a low humidity environment)
Each manufactured conductive roller is mounted as a developing roller on a non-magnetic one-component electrophotographic printer (trade name “HL-4040CN”, manufactured by Brother Industries, Ltd.) and in a low humidity environment (23 ° C., 10% relative humidity). ) For 24 hours. Thereafter, the printer was set to “plain paper thick”, the print quality was set to “standard”, and the color setting was set to “standard”, and 100 white images were continuously printed in the monochrome mode. Immediately thereafter, the setting was changed to the color mode, and one white image was printed. The degree of contamination of the white solid image printed in this color mode was visually evaluated as a fog. The evaluation is “◎” when there is no dirt on the entire white solid image, “○” when the white solid image is slightly dirty to the extent that there is no practical problem, and practical for white solid images. A case where dirt was found to be unacceptable was marked as “x”. These evaluation results are shown in Table 1 as “fogging evaluation”.

(Image quality evaluation for halftone images)
The printer (trade name “HL-4040CN”, manufactured by Brother Industries, Ltd.) equipped with each manufactured conductive roller as a developing roller was connected to a personal computer, and the test environment (23 ° C., relative humidity 10%) was established. It was allowed to stand for 24 hours. After that, set the printer's paper settings to "plain paper thick", print quality to "standard", color settings to "standard", and other settings to "default", and a monochrome full-screen image with a density equivalent to 18% gray. Was created on the screen of a personal computer using spreadsheet software “Excel” (Microsoft Corporation), and this monochrome entire image was printed as a halftone image in monochrome mode. The degree of homogeneity of the printed halftone image was visually evaluated. Evaluation is “◎” when the halftone image is a uniform image with no density unevenness, “○” when the halftone image shows slight density unevenness to the extent that there is no practical problem, and “halftone”. A case where density unevenness was found to be unacceptable in practice in an image was indicated as “x”. These evaluation results are shown in Table 1 as “image quality evaluation”.

DESCRIPTION OF SYMBOLS 1 Conductive roller 2 Shaft body 3 Elastic layer 4 Urethane coat layer 6 Transfer conveyance belt 10 Image forming apparatus 11B, 11C, 11M, 11Y Image carrier 12B, 12C, 12M, 12Y Charging means 13B, 13C, 13M, 13Y Exposure means 14B, 14C, 14M, 14Y Transfer means 15B, 15C, 15M, 15Y Cleaning means 16 Recording medium 20 Developing means 21B, 21C, 21M, 21Y, 34 Housings 22B, 22C, 22M, 22Y Developers 23B, 23C, 23M, 23Y developer carrier 24B, 24C, 24M, 24Y developer regulating member 30 fixing means 31 fixing roller 32 pressure roller 33 endless belt support roller 35 opening 36 endless belt 41 cassette 42 support rollers B, C, M, Y development unit

Claims (2)

An electroconductive roller comprising an elastic layer formed on the outer peripheral surface of the shaft body and a urethane coat layer formed on the outer peripheral surface of the elastic layer,
The said urethane coat layer contains 1-20 mass parts of phosphonium type | system | group ionic liquids with respect to 100 mass parts of said urethane resins and urethane resin, The electroconductive roller characterized by the above-mentioned.   An image forming apparatus comprising the conductive roller according to claim 1.

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