JP5623067B2 - Conductive roller and image forming apparatus - Google Patents

Description

  The present invention relates to a conductive roller and an image forming apparatus. More specifically, the present invention relates to a conductive roller capable of forming a high-quality image even after a long period of standby or stop of the image forming apparatus and in a low humidity environment. The present invention relates to a roller and an image forming apparatus.

  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 (see Examples).

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.

  Specifically, the ionic liquid of Patent Document 2 describes “1-ethyl-3-methylimidazolium trifluoroborate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, or 1-hexylpyridinium chloride”. (See the examples).

  Patent Document 3 states that “a material containing a specific quaternary ammonium salt (excluding octyltrimethylammonium salt) represented by the general formula (1a) or (1b) is used as an ionic conductive agent. Charging member ". Specifically, the quaternary ammonium salt is “any one of the four alkyl groups bonded to N is an alkyl group having 4, 6, or 8 carbon atoms, and the remaining three are a methyl group or an ethyl group. A quaternary ammonium salt which is a group (excluding octyltrimethylammonium salt), or any three are alkyl groups having 4, 6, 8 carbon atoms, and the remaining one is a methyl group or an ethyl group. (See column 0011 of Patent Document 3)

  The image forming apparatus provided with the conductive roller containing the ionic liquid or the like disclosed in Patent Documents 1 to 3 is attached to the inside of the image forming apparatus when the surrounding environment in which the apparatus is installed changes. The characteristics of the conductive roller may change and the initial function may not be fully exhibited.

  For example, when a conductive roller is used as a developing roller, when the humidity around the conductive roller decreases, a predetermined amount of developer charged to a predetermined charge amount cannot be supplied to the image carrier, and a white solid is formed. A phenomenon (called fogging) in which an unnecessary developer is fixed to an image (also called a plain image) or the like may occur. 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 Japanese Patent No. 3804476

  By the way, the developing roller or the like of the image forming apparatus is mounted in a state in which a part of the surface thereof is in contact with the image carrier at a predetermined pressure, as shown in FIG. When the image forming apparatus that has been in a standby state or stopped for a relatively long period of time in a state where the image carrier and the developing roller are in contact with each other as described above is operated, a desired amount is formed on an image formed after the operation, particularly an image formed first. In some cases, streaky blank portions (also referred to as white streaks) in which the developer is not fixed may occur. In particular, for example, when the image forming apparatus is on standby or stopped for a relatively long time in a high temperature environment such as summer or after the internal temperature has increased due to continuous operation, the white streaks are conspicuous in the image formed thereafter. Occurs.

  The situation in which the image forming apparatus waits or stops for a relatively long time includes, for example, the case where the manufactured image forming apparatus is transported and delivered in addition to the case where the image forming apparatus is intentionally waited or stopped. .

  An object of the present invention is to provide a conductive roller and an image forming apparatus capable of forming a high-quality image even after the image forming apparatus has been in standby or stopped for a long period of time and in a low humidity environment. And

  The present inventors have a urethane resin composition containing a specific amount of an ionic liquid having two hydroxyl groups as a urethane resin component, a urethane coat layer of a conductive roller used as a developing roller or the like, particularly a urethane coat layer as an outermost layer. It has been found that the formation of the object can substantially prevent the occurrence of fog even in a low-humidity environment, and can substantially prevent the occurrence of white streaks even after the image forming apparatus has been on standby or stopped for a long period of time. .

Therefore, as means for solving the above problems,
Claim 1 is a developing roller comprising an elastic layer formed on the outer peripheral surface of a shaft body and a urethane coat layer formed on the outer peripheral surface of the elastic layer, the urethane coat layer comprising two hydroxyl groups 1 to 20 parts by mass when the content of the ionic liquid is 100 parts by mass of the total content of the polyester polyol and the polyisocyanate. so that, Ri name by curing the urethane resin composition containing the ionic liquid is a halogen ion, tetrafluoroborate ion, hexafluorophosphate ion, trifluoromethanesulfonyl ion, and bis (trifluoromethanesulfonyl) imide ion An agent having at least one anion selected from the group consisting of A developing roller which is a down-based ionic liquid,
The developing roller according to claim 1, wherein the urethane resin is composed of the following repeating units (I) to (III) that satisfy the following mass ratio:
(I) -O-A-O-
(II) R _ol (—O—) _n
(III) R _is (-NHCO-) _m
However, the repeating unit (I) is a residue of the ionic liquid (which may or may not contain an anion), and A is a residue other than the hydroxyl group of the ionic liquid.
The repeating unit (II) is a residue of the polyester polyol, the _Rol is a residue excluding the hydroxyl group of the polyester polyol, n is an integer of 2 or more, and n or more of the (—O—) is Each of them is independently bonded to _Rol .
A residue of the repeating unit (III) is the polyisocyanate, wherein R _IS is a residue excluding isocyanate group of the polyisocyanate, m is an integer of 2 or more, m or more of the (-NHCO- ) is attached to said R _iS independently.
When the total mass of the mass of the repeating unit (II) (mass when converted to polyester polyol) and the mass of the repeating unit (III) (mass when converted to polyisocyanate) is 100 parts by mass, The mass of the repeating unit (I) (mass when converted to an ionic liquid) is 1 to 20 parts by mass .
Claim 3 is the developing roller according to claim 1 or 2 , wherein the polyester polyol has a number average molecular weight of 800 to 15000.
Claim 4, wherein the polyisocyanate is a developing roller according to any one of claims 1 to 3, characterized in that an aliphatic polyisocyanate,
A fifth aspect of the present invention is an image forming apparatus including the developing roller according to any one of the first to fourth aspects.

  In the conductive roller according to the present invention, an urethane coating layer is formed by curing a urethane resin composition containing 1 to 20 parts by mass of the ionic liquid, the polyol, and the polyisocyanate. It is possible to substantially suppress the occurrence of fogging in an image formed even in a low humidity environment as well as normal humidity, for example, a relative humidity of about 50%. Even if the standby or stop continues for a long period of time, it is possible to substantially suppress the occurrence of white streaks in the image formed thereafter. The image forming apparatus according to the present invention includes the conductive roller according to the present invention. Therefore, according to the present invention, there are provided a conductive roller and an image forming apparatus capable of forming a high-quality image even after the image forming apparatus has been in standby or stopped for a long period of time and in a low humidity environment. be able to.

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 by curing the urethane resin composition on the outer peripheral surface of the elastic layer. When the urethane coat layer 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 formed on the outer peripheral surface of the shaft body 2, and an outer peripheral surface of the elastic layer 3. And a urethane coat layer 4 formed on the surface.

  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 state in which a gold-plated plate having a length on which the entire urethane coat layer 4 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, precipitated silica, etc., 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 the same or different monovalent hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, 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, and 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-b-c) / 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, (C _{3) 2} HSiO _1/2 units and _{SiO 4/2} units and _{(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 catalyst based on rhodium and rhodium. 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 as the outermost layer of the conductive roller 1 and is formed by curing a urethane resin composition described later on the outer peripheral surface of the elastic layer 3. That is, the urethane coat layer 4 is formed by applying and curing the urethane resin composition on the outer peripheral surface of the elastic layer 3. Therefore, this urethane coat layer 4 contains a urethane resin formed from the urethane resin composition, and this urethane resin is an ion having two hydroxyl groups, which is a urethane forming component contained in the urethane resin composition. It is formed from a liquid, a polyol other than this ionic liquid, and a polyisocyanate. In addition to the urethane resin, the urethane coat layer 4 may contain various additives that are usually used in various urethane resin compositions, if desired. As such an additive, for example, a conductivity imparting agent such as carbon black may be contained as an optional component.

  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 capable of forming the urethane coat layer 4 will be described.

  The ionic liquid contained in the urethane resin composition is one kind of onium salt composed of a cation and an anion, and is a liquid compound having a high conductivity in a liquid state at a temperature at least near room temperature. , Also referred to as “ionic liquid”. This ionic liquid has two hydroxyl groups, and preferably has two hydroxyl groups at the ends. Such an ionic liquid having two hydroxyl groups is not particularly limited. For example, an amine-based ionic liquid with ammonium ion as a cation, an imidazolium-based ionic liquid with imidazolium ion as a cation, and a pyridinium ion as cation. And pyridinium-based ionic liquids. One or more ionic liquids may be contained in the urethane resin composition.

The anion constituting the 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 ⁻ ( And bis (trifluoromethanesulfonyl) imide ion: TFSI). Among these, BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ^— and (CF ₃ SO ₂ ) ₂ N ⁻ which are organic acid anions are preferable, and (CF ₃ SO ₂ ) ₂ N ⁻ is particularly preferable.

  In the present invention, the ionic liquid having two hydroxyl groups is an amine ionic liquid, particularly an aliphatic amine ionic liquid among various ionic liquids. In addition, even if the standby or stop of the image forming apparatus continues for a long period of time, the occurrence of white streaks in the image formed thereafter is preferable.

  The aliphatic amine-based ionic liquid is an aliphatic amine-based ionic liquid having, as a basic skeleton, ammonium ions formed by bonding four substituents to nitrogen atoms of an aliphatic amine compound as a cation. Examples of the aliphatic amine compound include alicyclic amine compounds and aliphatic amine compounds.

As the ammonium ion, for example, two of (R ¹¹ R ¹² R ¹³ R ¹⁴ ) N ⁺ ion (R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be the same or different, each having one hydroxyl group. A linear, branched or cyclic aliphatic organic group having 1 to 20 carbon atoms, the remaining two of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may be the same or different, It is a linear, branched or cyclic alkyl group or alkenyl group having a number of 1 to 20, and two of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ may form a ring. Can be mentioned.

The two aliphatic organic groups of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are preferably linear aliphatic organic groups, and may have a substituent other than a hydroxyl group. Examples of the aliphatic organic group include an alkyl group having one hydroxyl group, an alkenyl group having one hydroxyl group, and a polyoxyalkylene group. The alkyl group and the alkenyl group preferably have 1 to 20 carbon atoms, and the polyoxyalkylene group preferably has 4 to 16 carbon atoms, for example, in the case of polyoxyethylene, the degree of polymerization is 2 to 8. . Examples of such organic groups include hydroxyalkyl groups such as hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, hydroxybutyl group, and hydroxyhexyl group, hydroxyalkenyl groups such as hydroxyethenyl group, hydroxypropenyl group, and the like. Examples thereof include polyoxyalkylene groups such as oxyethylene group and polyoxypropylene group. In this invention, it is preferable that two of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are the same aliphatic organic group.

The remaining two of R ¹¹ , R ¹² , R ¹³ and R ¹⁴ other than the aliphatic organic group are linear, branched or cyclic alkyl groups or alkenyl groups having 1 to 40 carbon atoms. It is preferably a chain alkyl group or alkenyl group. The alkyl group or the alkenyl group may have a substituent. As such an alkyl group, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, pentyl group, neopentyl group, hexyl group, Examples include isohexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, cyclopentyl group, cyclohexyl group and the like. Examples of the alkenyl group include ethenyl group, propenyl group, butenyl group, oleyl group and the like.

  Examples of the aliphatic amine ionic liquid include an aliphatic amine ionic liquid having two 2-hydroxyethyl groups and an aliphatic amine ionic liquid having two polyoxyethylene groups. Specific examples of the aliphatic amine ionic liquid having two 2-hydroxyethyl groups include bis (2-hydroxyethyl) -methyl-octylammonium bis (trifluoromethanesulfonyl) imide and bis (2-hydroxy). Ethyl) -methyl-decylammonium bis (trifluoromethanesulfonyl) imide, bis (2-hydroxyethyl) -methyl-dodecylammonium bis (trifluoromethanesulfonyl) imide, bis (2-hydroxyethyl) -methyl-tetradecylammonium bis ( Trifluoromethanesulfonyl) imide, bis (2-hydroxyethyl) -methyl-hexadecylammonium bis (trifluoromethanesulfonyl) imide, bis (2-hydroxyethyl) -methyl-octadecylan Monium bis (trifluoromethanesulfonyl) imide, ethyl-bis (2-hydroxyethyl) -octylammonium bis (trifluoromethanesulfonyl) imide, ethyl-bis (2-hydroxyethyl) -decylammonium bis (trifluoromethanesulfonyl) imide, ethyl -Bis (2-hydroxyethyl) -dodecylammonium bis (trifluoromethanesulfonyl) imide, ethyl-bis (2-hydroxyethyl) -tetradecylammonium bis (trifluoromethanesulfonyl) imide, ethyl-bis (2-hydroxyethyl)- Hexadecylammonium bis (trifluoromethanesulfonyl) imide, ethyl-bis (2-hydroxyethyl) -octadecylammonium bis (trifluoromethanes Honiru) imide, Oreirubisu (2-hydroxyethyl) methyl ammonium bis (trifluoromethanesulfonyl) imide, oleyl - ethyl - bis (2-hydroxyethyl) ammonium bis (trifluoromethanesulfonyl) imide, and the like.

  Specific examples of the aliphatic amine-based ionic liquid having two polyoxyethylene groups include bis (polyoxyethylene) -methyl-octylammonium bis (trifluoromethanesulfonyl) imide and bis (polyoxyethylene)- Methyl-decylammonium bis (trifluoromethanesulfonyl) imide, bis (polyoxyethylene) -methyl-dodecylammonium bis (trifluoromethanesulfonyl) imide, bis (polyoxyethylene) -methyl-tetradecylammonium bis (trifluoromethanesulfonyl) imide Bis (polyoxyethylene) -methyl-hexadecylammonium bis (trifluoromethanesulfonyl) imide, bis (polyoxyethylene) -methyl-octadecylammonium bis Trifluoromethanesulfonyl) imide, oleyl - bis (polyoxyethylene) - methylammonium bis (trifluoromethanesulfonyl) imide, and the like.

  The polyol contained in the urethane resin composition is a polyol other than an ionic liquid, and may be any of various polyols that are usually used for preparing polyurethanes, preferably having at least two hydroxyl groups in the molecule. . The polyol is preferably at least one polyol selected from polyether polyols and polyester polyols, and polyester polyols are more preferable in terms of excellent thermal stability. 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 polyol is preferably a diol, and therefore more preferably a polyester diol or a polyether diol, and particularly preferably a polyester diol. The polyol preferably has a number average molecular weight of 800 to 15000, 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 said polyol may be used individually by 1 type or in combination of 2 or more types, and may be used combining polyether polyol and polyester polyol.

  The polyisocyanate contained in the urethane resin composition may be any of various polyisocyanates usually used in the preparation of polyurethane having at least two isocyanate groups in the molecule and preferably used at the terminal. Examples thereof include isocyanates, aromatic polyisocyanates, and derivatives thereof. The polyisocyanate is preferably an aliphatic polyisocyanate in that a high-quality image can be formed even after waiting or stopping for a long time of the image forming apparatus or in a low humidity environment. Examples of the aromatic polyisocyanate include xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (also referred to as tolylene diisocyanate, TDI), 3,3′-bitolylene-4,4′-diisocyanate, 3 , 3′-dimethyldiphenylmethane-4,4′-diisocyanate, 2,4-tolylene diisocyanate uretidinedione (a 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 polyisocyanate include hexamethylene diisocyanate (HDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), orthotoluidine diisocyanate, lysine diisocyanate methyl ester, isophorone diisocyanate (IPDI), norbornane diisocyanate methyl, trans Examples include cyclohexane-1,4-diisocyanate and triphenylmethane-4,4 ′, 4 ″ -triisocyanate. 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, allophanate-modified products. Products, urea-modified products, and burette-modified products.

  The polyisocyanate is preferably a diisocyanate and is therefore particularly preferably an aliphatic diisocyanate. The polyisocyanate preferably has a molecular weight of 500 to 2000, more preferably 700 to 1500. The polyisocyanate can be used alone or in combination of two or more.

  The urethane composition contains, in addition to the ionic liquid, the polyol and the polyisocyanate, a solvent, an auxiliary agent usually used for the reaction between the polyol and the polyisocyanate, such as a chain extender and a crosslinking agent. May be. Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane, and amines.

  The ionic liquid in the urethane resin composition is 1 to 20 parts by mass when the total content of the polyol and the polyisocyanate is 100 parts by mass. 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 charged developer may be discharged and the developer cannot be supported on the surface of the developing roller. As a result, fogging is likely to occur in a low humidity environment, and density unevenness is likely to occur in the halftone image, which may degrade the quality of the formed image. On the other hand, when the content exceeds 20 parts by mass, white streaks may occur in an image formed after the image forming apparatus is on standby, and the image quality may deteriorate. It is possible to effectively suppress the occurrence of fogging in a low-humidity environment, and it is effective that white streaks occur in an image formed afterwards even if the standby or stop of the image forming apparatus continues for a long period of time. The content of the ionic liquid is preferably 9 to 19 parts by mass when the total content of the polyol and the polyisocyanate is 100 parts by mass.

  The mixing ratio of the ionic liquid and the polyol and the polyisocyanate is the total number of moles of the hydroxyl group (OH) contained in the polyol and the hydroxyl group (OH) contained in the ionic liquid, and the isocyanate group (NCO contained in the polyisocyanate). ) And the number of moles [NCO / OH] is preferably 0.7 to 1.15. This ratio [NCO / OH] is more preferably 0.85 to 1.10 in that the hydrolysis of the 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.

  The urethane resin composition is obtained by mixing the ionic liquid, the polyol, the polyisocyanate, and, if desired, a solvent, an auxiliary agent, and the like by an appropriate method.

  The urethane resin formed in the urethane resin composition and contained in the urethane coat layer 4 is a reaction product of the ionic liquid, the polyol, and the polyisocyanate, and the ionic liquid is present in the main chain or side chain thereof. Specifically, the cation portion is bonded. If the anion of the ionic liquid is present in the urethane coat layer 4, it is bound to the cation by electrostatic action or is present in the vicinity of the cation and is a part of the urethane resin. Alternatively, it may be present away from the cation and may be independent of the urethane resin, or both.

This urethane resin is composed of repeating units (I) to (III) that satisfy the following mass ratio. That is, the urethane resin contains the repeating units (I) to (III) so as to satisfy the following mass ratio.
(I) -O-A-O-
(II) R _ol (—O—) _n
(III) R _is (-NHCO-) _m

In the repeating units (I) to (III), the repeating unit (I) is a residue of the ionic liquid and may or may not contain the anion, and A is a hydroxyl group of the ionic liquid. It is a residue except. The repeating unit (II) is a residue of the polyol, the _Rol is a residue excluding the hydroxyl group of the polyol, n is an integer of 2 or more, and n or more of the (—O—) are independent of each other. _Are bound to _Rol . A residue of the repeating unit (III) is the polyisocyanate, wherein R _IS is a residue excluding isocyanate group of the polyisocyanate, m is an integer of 2 or more, m or more of the (-NHCO- ) is attached to said R _iS independently.

  The repeating units (I) to (III) are derived from the ionic liquid, the polyol and the polyisocyanate, respectively, and are basically the same as these. Therefore, for example, the repeating unit (I) is preferably a residue of an aliphatic amine-based ionic liquid, and the repeating unit (II) is preferably a residue of a polyester diol or a polyether diol. The unit (III) is preferably a residue of an aliphatic diisocyanate.

  The urethane resin is such that the mass of the repeating unit (I) is 1 to 20 parts by mass when the total mass of the mass of the repeating unit (II) and the mass of the repeating unit (III) is 100 parts by mass. It has repeating units (I) to (III). Here, the mass of the repeating unit (I) is a mass when converted to the ionic liquid (including anions) before the reaction, and the mass of the repeating unit (II) is converted to the polyol before the reaction. The mass of the repeating unit (III) is the mass when converted to the polyisocyanate before the reaction. When the mass of the repeating unit (I) is less than 1 part by mass, as described above, 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, when the mass of the repeating unit (I) exceeds 20 parts by mass, as described above, any of fogging in a low-humidity environment, density unevenness in a halftone image, and white streaks after standby of the image forming apparatus may occur. Are likely to occur, and the quality of the formed image may deteriorate. It is possible to effectively suppress the occurrence of fogging in a low-humidity environment, and it is effective that white streaks occur in an image formed afterwards even if the standby or stop of the image forming apparatus continues for a long period of time. The mass of the repeating unit (I) is preferably 9 to 19 parts by mass when the total mass is 100 parts by mass.

  In the conductive roller 1 including the elastic layer 3 and the urethane coat layer 4, the elastic layer 3 is formed on the outer peripheral surface of the shaft body 2, and the urethane coat layer 4 is further formed on the outer peripheral surface of the elastic layer 3. Manufactured. 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 as an embodiment of the conductive roller according to the present invention is a urethane formed by curing a urethane resin composition containing 1 to 20 parts by mass of the ionic liquid, the polyol and the polyisocyanate. Since the coating layer 4 is provided, the occurrence of fogging can be substantially suppressed not only in 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.

  Since the conductive roller 1 includes a urethane coat layer 4 obtained by curing a urethane resin composition containing 1 to 20 parts by mass of the ionic liquid, the polyol, and the polyisocyanate, the image forming apparatus includes: Even if the image forming apparatus continuously stands by or stops for a long period of time, for example, five days or more in a state where the mounted conductive roller 1 is in contact with or pressed against a contacted body such as an image carrier, It is possible to substantially suppress the occurrence of white streaks in an image formed by operating the image forming apparatus. If the urethane coating layer 4 of the conductive roller 1 contains the ionic liquid described in Patent Documents 1 to 3, a new problem that the white streaks are likely to occur in the image has occurred. When the coating layer 4 contains the specific ionic liquid in a specific ratio, in addition to preventing the occurrence of the fog, the white layer is highly prevented from occurring in the image and a new problem is solved. Can do. The conductive roller 1 achieves such an excellent effect because the ionic liquid present in the urethane coat layer 4 can move inside the urethane coat layer 4 even if the standby or stop of the image forming apparatus continues for a long period of time. It is difficult to move, and it is difficult to shift to the contacted body with which the conductive roller 1 contacts, so that the uniformity of the urethane coat layer 4 is not impaired and the contacted body is not contaminated. The present inventors have speculated.

  As described above, when the conductive roller 1 is mounted on the image forming apparatus as a conductive roller such as a developing roller, for example, even after the image forming apparatus has been on standby or stopped for a long period of time, or in a low humidity environment. The image forming apparatus can contribute to forming a high-quality image.

  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, the conductive roller capable of forming an image without fogging even after the image forming apparatus has been on standby or stopped for a long period of time, or even when the surrounding humidity has changed to low humidity, and image formation The object of providing a device can be achieved.

  Even if the conductive roller 1 contains 1 to 20 parts by mass of an ionic liquid in the urethane resin composition, and particularly contains 5 parts by mass or more, the conductive roller 1 is formed by curing the urethane resin composition. It is difficult for the ionic liquid to bleed out from the urethane coat layer 4. As a result, it is possible to contribute to forming a high-quality image without contaminating the contacted body with which the conductive roller 1 is in contact.

  As described above, the conductive roller 1 can substantially suppress the occurrence of fog even when the surrounding area is low in humidity, and also substantially eliminates the occurrence of white streaks even after the image forming apparatus is on standby or stopped for a long time. For example, development that needs to exhibit the action and function of carrying a developer charged to a desired charge amount on the surface of itself to a uniform thickness and supplying it to the image carrier. It is preferably used as a roller and a developer supply roller, and particularly preferably used as a development roller and a developer supply roller that are mounted in contact with or pressed against a contacted body such as an 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 wound around the two support rollers 42. 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 units C, M, and Y are basically configured in the same manner as the developing device B.

  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 device 20B is mounted on the image forming apparatus 10 such that the conductive roller 1 as the developer carrier 23B is in contact with or pressure contact with the image carrier 11B. The nip width between the conductive roller 1 and the image carrier 11B at this time is normally adjusted so that the circumferential length of the conductive roller 1 is 0.1 to 2 mm. The developing units C, M, and Y are basically configured in the same manner as the developing unit B.

  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 fixing unit 30 is disposed downstream of the developing unit Y in the conveyance direction of the recording medium 16. 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 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. Further, when the conductive roller 1 according to the present invention is used as the developer carrier 23, the uniformity of the urethane coat layer 4 of the conductive roller 1 is impaired even if the tandem type image forming apparatus 10 is on standby or stopped for a long period of time. The tandem type image forming apparatus 10 provided with the conductive roller 1 is assumed to be substantially free of white streaks even if standby or stop is continued for a long period of time. A quality image can be formed.

  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. The fixing unit 30 may be a heat roller fixing device, a heat fixing device, a pressure fixing device, or the like.

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) (degree of polymerization 300) blocked at both ends with dimethylvinylsiloxy groups, and 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 Hokuaki Diatomite Co., Ltd.) 40 parts by mass, and 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. The content (parts by mass) of the ionic liquid in the urethane resin composition is expressed as “unconverted”, and the content (parts by mass) of the ionic liquid when the total content of the following polyol and polyisocyanate is 100 parts by mass. ) Is expressed as “converted”, and the content of carbon black is expressed as “CB content” and shown in Table 1.

-Polyisocyanate (hexamethylene diisocyanate) 14 parts by mass-Condensed polyester polyol (mixing molar ratio of 1,6-hexanediol and adipic acid [COOH / OH] = 12/13, number average measured by the above measuring method The molecular weight was within the above range.) 28 parts by mass • As an ionic liquid, 1 part by mass of bis (2-hydroxyethyl) -methyl-dodecylammonium bis (trifluoromethanesulfonyl) imide • Dibutyltin dilaurate (trade name “Di- "n-butyltin dilaurate", manufactured by Showa Chemical Co., Ltd.) 0.03 parts by mass Silica (trade name "ACEMATT OK-607", manufactured by Degussa) 4 parts by mass Carbon black (trade name "Toka Black # 4500", Tokai Carbon Co., Ltd.) 3 parts by mass

  The ratio [NCO / OH] of the total number of moles of hydroxyl groups of the ionic liquid and the hydroxyl groups of the condensed polyester polyol and the number of moles of isocyanate groups of the polyisocyanate was 1.1). The ionic liquid is a mixture containing an ionic liquid having a dodecyl group as an alkyl group as a main component and an ammonium salt having an alkyl group having 8 to 18 carbon atoms (excluding 12) as a subcomponent.

  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.

(Examples 5 to 8)
Example 5 was essentially the same as Example 1-4 except that bis (polyoxyethylene) -methyl-tetradecylammonium bis (trifluoromethanesulfonyl) imide was used instead of the ionic liquid. Eight conductive rollers were produced respectively. This ionic liquid has a total degree of polymerization of two (polyoxyethylene) groups of 15, the ionic liquid is mainly composed of an ionic liquid having a tetradecyl group as an alkyl group, and has 8 to 18 carbon atoms (as a secondary component). 14) and an ammonium salt having an alkyl group.

(Examples 9 to 12)
The conductivity of Examples 9-12 was basically the same as that of Examples 1-4 except that oleylbis (2-hydroxyethyl) methylammonium bis (trifluoromethanesulfonyl) imide was used instead of the ionic liquid. Each sex roller was manufactured.

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

(Reference Examples 1-4)
Reference Examples 1 to 4 were basically the same as Examples 1 to 4 except that N-hexylpyridinium bis (trifluoromethanesulfonyl) imide (manufactured by Kanto Chemical Co., Inc.) was used instead of the ionic liquid. Each conductive roller was manufactured.

  The urethane coat layer of each manufactured conductive roller is a urethane resin having the repeating units (I) to (III) at a mass ratio substantially the same as the content ratio in the urethane resin composition for forming the urethane coat layer 4. Contained.

(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”.

(Evaluation of density unevenness in 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 “density unevenness evaluation”.

(White stripe generation evaluation 1)
Each manufactured conductive roller is mounted on a non-magnetic one-component electrophotographic printer (trade name “HL-4040CN”, manufactured by Brother Industries, Ltd.) as a developing roller, and the surrounding environment is set to 50 ° C. for 5 days. It was left without operating. Thereafter, the image bearing member was taken out from the printer and visually confirmed. As a result, contamination of the image bearing member could not be confirmed. This image carrier was re-installed in the printer, and a single color image was printed with the paper setting of the printer set to “plain paper thick”, the print quality set to “standard”, and the color setting set to “color mode”. . The presence or absence of white streaks in this color image was visually evaluated. Evaluation is “◎” when the color image has no white streak, “○” when the color image has a slight white streak to the extent that there is no practical problem, and the color image is not practically acceptable. The case where white streaks were observed was marked as “x”. These evaluation results are shown in Table 1 as “white stripe evaluation 1”.

(White stripe generation evaluation 2)
Except that the surrounding environment was set to 60 ° C. and left to stand without operating for 7 days, the presence or absence of white streaks in the color image was visually evaluated in the same manner as in the white streak generation evaluation 1. did. The evaluation is “◎” when the color image has no white streak, “○” when the color image has several short white spaces that are not white streak, and the color image has white streak. The case where it was faintly recognized was “◯ △”, the case where clear white streaks were recognized in the color image was “X”, and the case where many white streaks were observed in the color image was “XX”. These evaluation results are shown in Table 1 as “white stripe evaluation 2”. When the image carrier was taken out from the printer after standing still and visually confirmed, contamination of the image carrier could not be confirmed.

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 (5)

A developing 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 urethane coat layer includes an ionic liquid having two hydroxyl groups, a polyester polyol other than the ionic liquid, and a polyisocyanate. The content of the ionic liquid is 100 parts by mass of the total content of the polyester polyol and the polyisocyanate. as will be 1 to 20 parts by weight when, Ri Na by curing the urethane resin composition containing,
The ionic liquid is an amine-based ionic liquid having at least one anion selected from the group consisting of halogen ions, tetrafluoroborate ions, hexafluorophosphate ions, trifluoromethanesulfonyl ions, and bis (trifluoromethanesulfonyl) imide ions. developing roller, characterized in that it. The developing roller according to claim 1, wherein the urethane resin includes the following repeating units (I) to (III) that satisfy the following mass ratio.
(I) -O-A-O-
(II) R _ol (—O—) _n
(III) R _is (-NHCO-) _m
However, the repeating unit (I) is a residue of the ionic liquid (which may or may not contain an anion), and A is a residue other than the hydroxyl group of the ionic liquid.
The repeating unit (II) is a residue of the polyester polyol, the _Rol is a residue excluding the hydroxyl group of the polyester polyol, n is an integer of 2 or more, and n or more of the (—O—) is Each of them is independently bonded to _Rol .
A residue of the repeating unit (III) is the polyisocyanate, wherein R _IS is a residue excluding isocyanate group of the polyisocyanate, m is an integer of 2 or more, m or more of the (-NHCO- ) is attached to said R _iS independently.
When the total mass of the mass of the repeating unit (II) (mass when converted to polyester polyol) and the mass of the repeating unit (III) (mass when converted to polyisocyanate) is 100 parts by mass, The mass of the repeating unit (I) (mass when converted to an ionic liquid) is 1 to 20 parts by mass . The polyester polyol, a developing roller according to claim 1 or 2 a number average molecular weight thereof characterized in that it is a 800 to 15,000. The polyisocyanate, the developing roller according to any one of claims 1 to 3, characterized in that an aliphatic polyisocyanate. Image forming apparatus comprising a developing roller according to any one of claims 1-4.

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