JP2020079894A - Developing roller, developing device, and image forming apparatus - Google Patents

Abstract

To provide a developing roller that satisfactorily prevents the occurrence of a ghost phenomenon and filming and is excellent in durable printing performance, a developing device, and an image forming apparatus.SOLUTION: A developing roller 1 comprises: an elastic layer 3 formed on an outer peripheral surface of a shaft body 2; and a coating layer 4 formed on an outer peripheral surface of the elastic layer 3. In the developing roller 1, the coating layer 4 has a glass transition point Tg of -50°C or more and 0°C or less, a coefficient of dynamic friction μD of 0.05 or more and 0.6 or less, and an arithmetic average roughness Ra of 0.4 or more and 1.5 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a developing roller, a developing device, and an image forming apparatus.

  A developing roller used in an image forming apparatus such as a copying machine, a printer, or a facsimile adopting an electrophotographic system has a function of conveying a developer to an image carrier on which an electrostatic latent image is formed. The developer transportability of the developing roller affects the quality of the image forming apparatus, especially the print density. In recent years, it has been studied to form unevenness on the surface of the developing roller and adjust the electrical characteristics of various materials forming the developing roller to improve the developer transportability of the developing roller.

When the developing roller is used for a long period of time, the developer may adhere to its surface (referred to as "filming"). Such filming is, for example, that the developer is deformed or destroyed by the sliding stress of the blade or the like that is in pressure contact with the developing roller when charging or adhering the developer, and further, the developer is developed by frictional heat with the blade or the like. It is considered to be caused by the melting of the agent.
When the old developer not used for the development remains on the surface of the developing roller and the new developer is supplied next, the old developer and the new developer are mixed. Then, a difference occurs in the charge amount between the old developer and the new developer, and there is a problem that a phenomenon in which an image history of one round before appears on an image corresponding to the next round, that is, a ghost phenomenon occurs on the developing roller.
Therefore, various developing rollers that suppress the occurrence of ghost phenomenon and filming and have excellent durable printing performance have been studied.

  For example, Patent Document 1 describes a conductive roller containing an ionic liquid, in which a developer is unlikely to adhere to the surface for a long time. Further, Patent Document 2 discloses a reactive fluorine-containing copolymer useful as a surface modifier for imparting anti-fingerprint property and surface smoothness to the surface of resins, films, fibers and the like. Furthermore, Patent Document 3 discloses a conductive roller having excellent toner adhesion and durability, which is formed from a composition containing a fluororesin B having a glass transition point Tg of 0° C. to 80° C. ..

JP, 2011-221442, A JP, 2015-120852, A JP, 2005-187752, A

However, in the developing roller or the conductive roller described in the above patent document, it is not possible to suppress the occurrence of the ghost phenomenon and filming to the extent that the performance of the image forming apparatus required in recent years can be sufficiently suppressed, and it is said that the durable printing performance is improved. From the point of view, it was not satisfactory.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a developing roller, a developing device, and an image forming apparatus in which the occurrence of a ghost phenomenon and filming are favorably suppressed and which is excellent in durable printing performance. ..

  The developing roller of the present invention is a developing roller including an elastic layer formed on the outer peripheral surface of a shaft and a coating layer formed on the outer peripheral surface of the elastic layer, and the coating layer has a glass transition point Tg of − It is 50° C. or higher and 0° C. or lower, the dynamic friction coefficient μD is 0.05 or higher and 0.6 or lower, and the arithmetic average roughness Ra is 0.4 or higher and 1.5 or lower.

  The coating layer of the developing roller of the present invention is formed by curing the resin composition for a coating layer, and the content of fluorine atoms in the resin composition for a coating layer is preferably less than 5% by mass.

  The resin composition for the coating layer comprises (a) a polyol, (b) an isocyanate, (c) a hydroxyl group and a (meth)acrylate copolymer containing 1% by mass or more and 10% by mass or less of a fluorine atom, and (d) a surface. A material containing a roughening material and (e) an ion conductive material is preferable.

  The developing device of the present invention includes the developing roller of the present invention.

  The image forming apparatus of the present invention includes the developing roller of the present invention.

  According to the present invention, it is possible to obtain a developing roller, a developing device, and an image forming apparatus in which the occurrence of a ghost phenomenon and filming are satisfactorily suppressed and which is excellent in durable printing performance.

FIG. 1 is a schematic perspective view showing an embodiment of the developing roller of the present invention. FIG. 2 is a schematic sectional view showing an embodiment of the image forming apparatus of the present invention. FIG. 3 is a diagram showing a method of measuring a dynamic friction coefficient in the invention.

  Hereinafter, embodiments of the present invention will be described in detail, but the following embodiments are presented for the purpose of illustration, and the present invention is not limited to the embodiments described below.

[Development roller]
FIG. 1 is a schematic perspective view showing an embodiment of the developing roller of the present invention.
As shown in FIG. 1, the developing roller 1 of the present invention is a developing roller including an elastic layer 3 formed on the outer peripheral surface of a shaft body 2 and a coating layer 4 formed on the outer peripheral surface of the elastic layer 3. The coating layer 4 has a glass transition point Tg of −50° C. or higher and 0° C. or lower, a dynamic friction coefficient μD of 0.05 or higher and 0.6 or lower, and an arithmetic average roughness Ra of 0.4 or higher and 1. It is 5 or less.
Hereinafter, the configuration of the developing roller 1 of the present invention will be described.

(Shaft)
As the shaft body 2, preferably, a shaft body having conductivity and used in a conventionally known developing roller can be used. The shaft body 2 is preferably made of at least one metal selected from the group consisting of iron, aluminum, stainless steel, and brass, for example. The shaft body 2 made of such a metal is generally known by the name of "core bar".

The shaft body 2 may include an insulating resin. The insulating resin may be, for example, a thermoplastic resin or a thermosetting resin. The shaft body 2 may include, for example, a core body made of an insulating resin and a plating layer provided on the core body. Such a shaft body 2 can be obtained, for example, by plating a core body made of an insulating resin to make it conductive.
The shaft body 2 is preferably a core metal in order to obtain good conductivity.

  The shaft body 2 preferably has a rod shape, a tubular shape, or the like, for example. The sectional shape of the shaft body 2 may be, for example, a circular shape, an elliptical shape, or a non-circular shape such as a polygonal shape. The outer peripheral surface of the shaft body 2 may be subjected to treatments such as cleaning treatment, degreasing treatment and primer treatment in order to improve the adhesiveness to the elastic layer 3.

  The length of the shaft body 2 in the axial direction is not particularly limited, and may be appropriately adjusted according to the form of the image forming apparatus to be installed. For example, when the print target is an A4 size, the axial length of the shaft body 2 is preferably 250 mm or more and 320 mm or less, and more preferably 260 mm or more and 310 mm or less. The diameter of the shaft body 2 (diameter of the circumscribing circle) is not particularly limited, and may be appropriately adjusted according to the form of the image forming apparatus to be installed. For example, the outer diameter (diameter of the circumscribing circle) of the shaft body 2 is preferably 4 mm or more and 14 mm or less, and more preferably 6 mm or more and 10 mm or less.

(Elastic layer)
The elastic layer 3 is formed by heating and curing the rubber composition on the outer peripheral surface of the shaft body 2. The rubber composition for forming the elastic layer 3 preferably contains rubber, a conductivity-imparting agent, and optionally various additives.

Examples of the rubber in the rubber composition 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. Examples thereof include rubber, butyl rubber, epichlorohydrin rubber, urethane rubber and fluororubber. Silicone or silicone modified rubber or urethane rubber is preferable, and the silicone or silicone modified rubber can reduce compression set and is excellent in flexibility in a low temperature environment, and further, heat resistance and charging property. It is particularly preferable in that it has excellent properties. Examples of the silicone rubber include crosslinked products of organopolysiloxanes such as dimethylpolysiloxane and diphenylpolysiloxane.
Examples of the silicone rubber composition include addition-curable millable conductive silicone rubber compositions and addition-curable liquid conductive silicone rubber compositions.

-Addition-curable millable conductive silicone rubber composition-
The addition-curable millable conductive silicone rubber composition contains, for example, (A) an organopolysiloxane represented by the following average composition formula (1), (B) a filler, and (C) a conductivity-imparting agent. You may.
R ¹ _n SiO _(4-n)/2 (1)
In the formula (1), n represents a positive number of 1.95 or more and 2.05 or less. R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. The number of carbon atoms in the hydrocarbon group is preferably 1 or more and 12 or less, more preferably 1 or more and 8 or less.

Examples of R ¹ include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group and dodecyl group, cycloalkyl groups such as cyclohexyl group, vinyl group, allyl group, butenyl group and hexenyl group. Examples thereof include an alkenyl group, an aryl group such as a phenyl group and a tolyl group, and an aralkyl group such as a β-phenylpropyl group. Further, R ¹ may be a group in which some or all of the hydrogen atoms of these hydrocarbon groups are substituted with a substituent. The substituent may be, for example, a halogen atom, a cyano group or the like. Examples of the hydrocarbon group having a substituent include a chloromethyl group, a trifluoropropyl group, a cyanoethyl group and the like.

  The organopolysiloxane (A) has a molecular chain terminal such as a trialkylsilyl group such as a trimethylsilyl group, a dialkylaralkylsilyl group such as a dimethylvinylsilyl group, a dialkylhydroxysilyl group such as a dimethylhydroxysilyl group, and a trivinylsilyl group. It is preferably blocked with a triaralkylsilyl group or the like.

The (A) organopolysiloxane preferably has two or more alkenyl groups in the molecule. The (A) organopolysiloxane preferably has 0.001 mol% or more and 5 mol% or less (more preferably 0.01 mol% or more and 0.5 mol% or less) of alkenyl groups in R ¹ . The vinyl group is particularly preferable as the alkenyl group contained in the organopolysiloxane (A).

  The (A) organopolysiloxane is obtained by, for example, subjecting one or more organohalosilanes to cohydrolysis condensation, or ring-opening polymerization of a cyclic polysiloxane such as a trimer or tetramer of siloxane. Can be obtained by The (A) organopolysiloxane may be basically a linear diorganopolysiloxane and may be partially branched. The (A) organopolysiloxane may be a mixture of two or more kinds having different molecular structures.

  The organopolysiloxane (A) preferably has a kinematic viscosity at 25° C. of 100 cSt or more, and more preferably 100000 cSt or more and 10000000 cSt or less. The degree of polymerization of the (A) organopolysiloxane is, for example, preferably 100 or more, more preferably 3000 or more and 10000 or less.

  Examples of the filler (B) include silica-based fillers. Examples of silica-based fillers include fumed silica and precipitated silica.

As the silica-based filler, a surface-treated silica-based filler surface-treated with a silane coupling agent represented by R ² Si(OR ³ ) ₃ can be preferably used. Here, R ² may be a group having a vinyl group or an amino group, and may be, for example, a glycidyl group, a vinyl group, an aminopropyl group, a methacryloxy group, an N-phenylaminopropyl group, a mercapto group, or the like. R ³ may be an alkyl group, for example, a methyl group, an ethyl group or the like. The silane coupling agent is easily available, for example, under the trade names “KBM1003” and “KBE402” manufactured by Shin-Etsu Chemical Co., Ltd. The surface-treated silica-based filler can be obtained by treating the surface of the silica-based filler with a silane coupling agent according to a standard method. As the surface-treated silica-based filler, a commercially available product may be used. M. For example, the product name “Zeothix 95” manufactured by HUBER Co., Ltd. may be mentioned.

  The blending amount of the silica-based filler is preferably 11 parts by mass or more and 39 parts by mass or less, and more preferably 15 parts by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the (A) organopolysiloxane. The average particle size of the silica-based filler is preferably 1 μm or more and 80 μm or less, more preferably 2 μm or more and 40 μm or less. The average particle diameter of the silica-based filler can be measured as a median diameter by using a particle size distribution measuring device using a laser light diffraction method.

  The amount of the conductivity-imparting agent (C) compounded is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, relative to 100 parts by mass of the organopolysiloxane (A). The amount of the conductivity-imparting agent (C) blended is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, relative to 100 parts by mass of the (A) organopolysiloxane.

  The addition-curable millable conductive silicone rubber composition may further contain additives other than (A) to (C). Examples of the additives include auxiliary agents (chain extenders, crosslinking agents, etc.), catalysts, dispersants, foaming agents, antioxidants, antioxidants, pigments, colorants, processing aids, softening agents, plasticizers, Examples thereof include emulsifiers, heat resistance improvers, flame retardancy improvers, acid acceptors, thermal conductivity improvers, mold release agents and solvents.

  Specific examples of the additives include (A) dimethylsiloxane oil having a lower degree of polymerization than organopolysiloxane, polyether-modified silicone oil, silanol, diphenylsilanediol, and α,ω-dimethylsiloxanediol, both terminal silanol group sealing. Examples of the dispersant include low molecular weight siloxane and silane. In addition, specific examples of the additive include heat resistance improvers such as iron octylate, iron oxide, and cerium oxide. As the additive, various carbon functional silanes, various olefin-based elastomers, etc. for improving adhesiveness, molding processability and the like may be used.

-Addition-curable liquid conductive silicone rubber composition-
The addition-curable liquid conductive silicone rubber composition includes, for example, (D) an organopolysiloxane having two or more alkenyl groups in the molecule, and (E) two or more hydrogen atoms bonded to a silicon atom in the molecule. It may contain an organohydrogenpolysiloxane, a (F) filler, (G) a conductivity-imparting agent, and (H) an addition reaction catalyst.

As the organopolysiloxane (D), compounds represented by the following average composition formula (2) are preferable.
R ⁴ _a SiO _(4-a)/2 (2)
In the formula (2), a represents a positive number of 1.5 or more and 2.8 or less, preferably 1.8 or more and 2.5 or less, and more preferably 1.95 or more and 2.05 or less. R ⁴ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. However, at least two of R ^{4 in} one molecule are alkenyl groups. The number of carbon atoms in the hydrocarbon group is preferably 1 or more and 12 or less, more preferably 1 or more and 8 or less.

Examples of R ⁴ include the same groups as those exemplified above as R ¹ . In addition, it is preferable that at least two of R ^{4 s in} one molecule are alkenyl groups and the other R ^{4 s} are alkyl groups. The alkenyl group is preferably a vinyl group, and the alkyl group is preferably a methyl group. In addition, 90% or more of R ⁴ may be an alkyl group (preferably a methyl group). The content of the alkenyl group in (D) the organopolysiloxane is preferably 1.0×10 ⁻⁶ mol/g or more and 5.0×10 ⁻³ mol/g or less, and 5.0×10 ^−. It is more preferably ⁶ mol/g or more and 1.0×10 ⁻³ mol/g or less.

  The (D) organopolysiloxane is preferably liquid at 25° C., and the viscosity at 25° C. is preferably 100 mPa·s or more and 1,000,000 mPa·s or less, and more preferably 200 mPa·s or more and 100000 mPa·s or less. preferable. The average degree of polymerization of the organopolysiloxane (D) is preferably 100 or more and 800 or less, more preferably 150 or more and 600 or less.

As the organohydrogenpolysiloxane (E), a compound represented by the following average composition formula (3) is preferable.
^{_{R 5 b H c SiO (4}} -b-c) / 2 ... (3)
In the formula (3), b represents a positive number of 0.7 or more and 2.1 or less, c represents a positive number of 0.001 or more and 1.0 or less, and bc is 0.8 or more and 3.0 or less. Is. R ⁵ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. The number of carbon atoms in the hydrocarbon group is preferably 1 or more and 10 or less. In addition, as R ⁵ , the same groups as those exemplified as the above R ¹ can be exemplified.

  The organohydrogenpolysiloxane (E) has two or more hydrogen atoms (Si-H) bonded to a silicon atom in one molecule, and preferably three or more. Moreover, the number of hydrogen atoms bonded to silicon atoms contained in one molecule of the (E) organohydrogenpolysiloxane is preferably 200 or less, and more preferably 100 or less.

  In (E) the organohydrogenpolysiloxane, the content of hydrogen atoms bonded to silicon atoms is preferably 0.001 mol/g or more and 0.017 mol/g or less, and 0.002 mol/g or more and 0.015 mol/g. It is more preferably g or less.

Examples of the (E) organohydrogenpolysiloxane include trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both ends, trimethylsiloxy group-blocked dimethylsiloxane/methylhydrogensiloxane copolymer at both terminals, and dimethylhydrogensiloxy group-blocked at both ends. Dimethylpolysiloxane, dimethylhydrogensiloxy group-blocked dimethylsiloxane/methylhydrogensiloxane copolymer at both ends, trimethylsiloxy group-blocked methylhydrogensiloxane/diphenylsiloxane copolymer at both ends, trimethylsiloxy group-blocked methylhydrogensiloxane at both ends diphenylsiloxane-dimethylsiloxane _{copolymer, (CH} 3) 2 _{HSiO 1/2} consisting of units and _{SiO 4/2} units, and copolymers thereof, _{and, (CH} 3) 2 _{HSiO 1/2} units and _{SiO 4/2} copolymers thereof consisting of units and _{(C 6} H _{5) SiO 3/2} units.

  The blending amount of the (E) organohydrogenpolysiloxane is preferably 0.1 parts by mass or more and 30 parts by mass or less, and 0.3 parts by mass or more and 20 parts by mass with respect to 100 parts by mass of the (D) organopolysiloxane. The following is more preferable. Further, the molar ratio of Si-H of the organohydrogenpolysiloxane (E) to the alkenyl group of the organopolysiloxane (D) is preferably 0.3 to 5.0, and 0.5 to 2.5. Is more preferable.

  The (F) filler may be, for example, an inorganic filler. By blending the (F) filler with the addition-curable liquid conductive silicone rubber composition, the compression set becomes low, the volume resistivity becomes stable over time, and sufficient roller durability can be obtained.

  The average particle diameter of the filler (F) is preferably 1 μm or more and 30 μm or less, and more preferably 2 μm or more and 20 μm or less. When the average particle size of the filler (F) is 1 μm or more, the change in volume resistivity with time is further suppressed. Further, when the average particle diameter of the (F) filler is 30 μm or less, the elastic layer 3 having further excellent durability can be obtained. The average particle diameter of the (F) filler can be measured as a median diameter by using a particle size distribution measuring device by a laser light diffraction method.

(F) the bulk density of the filler is preferably at 0.1 g / cm ³ or more 0.5 g / cm ³ or less, and more preferably less 0.15 g / cm ³ or more 0.45 g / cm ³ .. (F) By adjusting the bulk density of the filler within the above range, the compression set can be further lowered, the change in volume resistivity with time can be further suppressed, and the elastic layer 3 having further excellent durability. Can be obtained. (F) The bulk density of the filler can be determined based on the method of measuring the apparent specific gravity of JIS K 6223.

  Examples of the filler (F) include diatomaceous earth, perlite, mica, calcium carbonate, glass flakes, and hollow fillers. Among these, as the (F) filler, diatomaceous earth, pearlite, and pulverized products of expanded perlite can be preferably used.

  The compounding amount of the (F) filler is preferably 5 parts by mass or more and 100 parts by mass or less, and more preferably 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the (D) organopolysiloxane. .

  The amount of the (G) conductivity-imparting agent added is preferably 0.5 parts by mass or more and 15 parts by mass or less, and more preferably 1 part by mass or more and 10 parts by mass or less, based on 100 parts by mass of the (D) organopolysiloxane. More preferably.

  The (H) addition reaction catalyst may be any catalyst that can activate the addition reaction between the (D) organopolysiloxane and the (E) organohydrogenpolysiloxane. Examples of the (H) addition reaction catalyst include a catalyst having a platinum group element. Examples of the catalyst having a platinum group element include platinum-based catalysts (for example, platinum black, chloroplatinic acid, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and olefins). , Platinum bisacetoacetate, etc.), palladium-based catalysts, rhodium-based catalysts, and the like.

  The compounding amount of the (H) addition reaction catalyst may be a catalytic amount. For example, the compounding amount of the (H) addition reaction catalyst is such that the platinum group element content is 0.5 mass ppm or more and 1000 mass ppm or less with respect to the total mass of the (D) organopolysiloxane and the (E) organohydrogenpolysiloxane. The amount is preferably 1 mass ppm or more and 500 mass ppm or less.

  The elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 by heat curing and molding simultaneously or continuously by a known molding method. The method for curing the rubber composition may be any method capable of applying heat necessary for curing the rubber composition, and the method for molding the elastic layer 3 may be continuous vulcanization by extrusion molding, press molding, molding by injection, and the like. It is not limited. For example, when the rubber composition is an addition-curable millable conductive silicone rubber composition, for example, extrusion molding can be selected, and the rubber composition is an addition-curable liquid conductive silicone rubber composition. In this case, for example, a molding method using a mold can be selected. Alternatively, the elastic body (cured product of the silicone rubber composition) formed on the shaft body 2 may be formed by grinding or polishing.

  The heating temperature for curing the rubber composition is preferably 100° C. or higher and 500° C. or lower, and more preferably 120° C. or higher and 300° C. or lower in the case of the addition-curable millable conductive silicone rubber composition. The heating time is preferably several seconds or more and 1 hour or less, more preferably 10 seconds or more and 35 minutes or less. In the case of the addition-curable liquid conductive silicone rubber composition, the heating temperature is preferably 100°C or higher and 300°C or lower, more preferably 110°C or higher and 200°C or lower. The heating time is preferably 5 minutes or more and 5 hours or less, more preferably 1 hour or more and 3 hours or less. In addition, secondary vulcanization may be carried out if necessary. In the case of the addition-curable millable conductive silicone rubber composition, for example, curing conditions of 100° C. or higher and 200° C. or lower and 1 hour or longer and 20 hours or shorter are selected. In addition, in the case of the addition-curable liquid conductive silicone rubber composition, for example, curing conditions of 120° C. or more and 250° C. or less and 2 hours or more and 70 hours or less are selected. In addition, a sponge-like elastic layer having bubbles can be easily formed by foaming and curing the rubber composition by a known method.

  The addition-curable liquid conductive silicone rubber composition may further contain additives other than (D) to (H). Examples of the additives include auxiliary agents (chain extenders, crosslinking agents, etc.), foaming agents, dispersants, antioxidants, antioxidants, pigments, colorants, processing aids, softening agents, plasticizers, emulsifiers, Examples of the heat resistance improver, flame retardant improver, acid acceptor, thermal conductivity improver, release agent, diluent, reactive diluent, solvent and the like.

  Specific examples of the additive include dispersants such as low molecular weight siloxane ester, polyether modified silicone oil, silanol, and phenylsilanediol. Further, heat resistance improvers such as iron octylate, iron oxide and cerium oxide can be mentioned. Further, various carbon functional silanes, various olefin elastomers, etc. for improving the adhesiveness, molding processability and the like may be used. Moreover, you may use the halogen compound etc. which give flame retardancy.

  The viscosity of the addition curable liquid conductive silicone rubber composition at 25° C. is preferably 5 Pa·s or more and 500 Pa·s or less, more preferably 5 Pa·s or more and 200 Pa·s or less.

  The thickness of the elastic layer 3 is not particularly limited, and is preferably 0.1 mm or more and 6 mm or less, more preferably 1 mm or more and 4 mm or less. In addition, the thickness in this specification indicates the thickness in a direction perpendicular to the axial direction of the developing roller 1.

  The outer diameter of the elastic layer 3 is not particularly limited and is, for example, preferably 6 mm or more and 25 mm or less, and more preferably 7 mm or more and 21 mm or less.

  The outer peripheral surface of the elastic layer 3 is subjected to a surface treatment such as a primer treatment, a corona treatment, a plasma treatment, an excimer treatment, a UV treatment, an itro treatment, and a flame treatment for the purpose of improving adhesion with the coating layer 4. You may.

  The method for forming the elastic layer 3 is not particularly limited. For example, the elastic layer 3 may be formed by a method such as extrusion molding of a silicone rubber composition or LIMS molding. The elastic layer 3 may be formed by grinding or polishing an elastic body (cured product of a silicone rubber composition) formed on the shaft body 2.

-Other ingredients-
The rubber composition may further contain various additives other than the above. Examples of various additives include auxiliary agents (chain extenders, crosslinking agents, etc.), catalysts, dispersants, foaming agents, antioxidants, antioxidants, pigments, colorants, processing aids, softening agents, plasticizers. , Emulsifiers, heat resistance improvers, flame retardancy improvers, acid acceptors, thermal conductivity improvers, release agents, solvents and the like.

(Coating layer)
The coating layer 4 is provided on the outermost surface of the elastic layer 3 and on the outermost surface of the developing roller 1. The coating layer 4 is formed by applying the coating layer resin composition to the outer peripheral surface of the elastic layer 3 or the primer layer formed as desired, and then heat-curing the coated coating layer resin composition. Is formed.
The resin composition for the coating layer comprises (a) a polyol, (b) an isocyanate, (c) a hydroxyl group and a (meth)acrylate copolymer containing 1% by mass or more and 10% by mass or less of a fluorine atom, and (d) a surface. It contains a roughening material and (e) an ion conductive material.
Hereinafter, each component (a) to (e) of the resin composition for the coating layer will be described.

(A) Polyol 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 polyol, polyester polyol, polyacrylate polyol and polycarbonate polyol. ..

  Polyether polyols include, for example, polyethylene glycol, polypropylene glycol, polyalkylene glycols such as polypropylene glycol-ethylene glycol, polytetramethylene ether glycol, copolymerized polyols of tetrahydrofuran and alkylene oxide, and various modified products of these. A mixture etc. are mentioned.

  The polyester polyol has two or more ester bonds and two or more hydroxyl groups in the molecule. Examples of the polyester polyol include a condensation reaction product of a dicarboxylic acid and a polyol. Examples of the dicarboxylic acid include aromatic dicarboxylic acids such as phthalic acid, terephthalic acid and isophthalic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid.

  Polyacrylate polyols include hydroxyl group-containing monomers and other olefinically unsaturated monomers such as esters of (meth)acrylic acid, styrene, α-methylstyrene, vinyltoluene, vinylesters, maleic acid monoalkyl esters and maleic acid dialkylesters. , Fumaric acid monoalkyl esters and fumaric acid dialkyl esters, copolymers with α-olefins and other unsaturated oligomers and polymers.

Polycarbonate polyol has two or more carbonate bonds and two or more hydroxyl groups in the molecule. Examples of the polycarbonate polyol include a condensation reaction product of a polyol and a carbonate compound. Examples of the carbonate compound include dialkyl carbonate, diaryl carbonate, alkylene carbonate and the like. Examples of the polyol used as a raw material for the polycarbonate polyol include diols such as hexanediol and butanediol, and triols such as 2,4-butanetriol.
The polyol preferably has a number average molecular weight of 1,000 to 8,000, more preferably has a number average molecular weight of 1,000 to 5,000, and the ionic liquid is a hydroxyl group-containing ionic liquid, in terms of excellent compatibility with isocyanates described below. When it is, it is preferable to have a number average molecular weight of 800 to 15,000, and it is more preferable to have a number average molecular weight of 1000 to 5000. The number average molecular weight is a molecular weight when converted into standard polystyrene by gel permeation chromatography (GPC).

(B) Isocyanate The isocyanate may be any of various isocyanates usually used for preparing polyurethanes, and examples thereof include aliphatic isocyanates, aromatic isocyanates and derivatives thereof. The isocyanate is preferably an aliphatic isocyanate because of its excellent storage stability and easy control of the reaction rate.
Examples of aromatic isocyanates include xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (also referred to as tolylene diisocyanate. TDI), 3,3′-vitrylene-4,4′-diisocyanate, 3,3. '-Dimethyldiphenylmethane-4,4'-diisocyanate, 2,4-tolylene diisocyanate uretidinedione (dimer of 2,4-TDI), xylene diisocyanate, naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PDI), Examples thereof include trisine diisocyanate (TODI) and metaphenylene diisocyanate.
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. Examples include -1,4-diisocyanate and triphenylmethane-4,4',4''-triisocyanate.
As the derivative, a polynuclear polyisocyanate, a urethane modified product (including urethane prepolymer) modified with a polyol, a dimer by uretdione formation, an isocyanurate modified product, a carbodiimide modified product, a uretonimine modified product, an alohanate modified product, Examples include urea modified products and buret modified products. The polyisocyanate may be used alone or in combination of two or more. The polyisocyanate preferably has a molecular weight of 500 to 2000, more preferably 700 to 1500.

The (b) isocyanate used in the resin composition for the coating layer is preferably polyisocyanate. (B) The number of isocyanate groups in one molecule of isocyanate is preferably more than 2, more preferably 2.5 or more, still more preferably 3 or more.
The mixing ratio in the mixture of the polyol and the polyisocyanate is not particularly limited, but usually the molar ratio (NCO/OH) of the hydroxyl group (OH) contained in the polyol and the isocyanate group (NCO) contained in the polyisocyanate is 0. It is preferably from 0.7 to 1.15. This molar ratio (NCO/OH) is more preferably 0.85 or more and 1.10 or less from the viewpoint of preventing hydrolysis of polyurethane. In practice, an amount equivalent to 3 to 4 times the appropriate molar ratio may be blended in consideration of working environment and working error.

  The resin composition for the coating layer may be used in combination with an auxiliary agent that is usually used in the reaction of (a) a polyol and (b) an isocyanate, such as a chain extender or a crosslinking agent. Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane, amines and the like.

(C) (Meth)acrylate copolymer containing a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom (meth)acrylate copolymerization containing a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom The polymer (hereinafter sometimes simply referred to as (c)(meth)acrylate copolymer) has at least a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom in the copolymer. .. Such a copolymer is composed of at least a fluorine-containing (meth)acrylate monomer (c-1) and a hydroxyl group-containing (meth)acrylate monomer (c-2).

  The fluorine-containing (meth)acrylate monomer (c-1) is represented by the following general formula (c-1).

In the formula, Rf is a group represented by the following formula (1) or (2). R ¹ is H or a methyl group, and R ² is a divalent group having 2 to 50 carbon atoms.

Examples of the divalent group having 2 to 50 carbon atoms represented by R ² include the following groups.

_{- (CH 2) n1 - (} n1 = 2~50)
_{-X-Y- (CH 2) n2} - (n2 = 2~43)
_{-X- (CH 2) n3 - (} n3 = 1~44)
_{-CH 2 CH 2 (OCH 2 CH} 2) n4 - (n4 = 1~24)
_{-XCO (OCH 2 CH 2) n5} - (n5 = 1~21)
(In the formula, X is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and phenylene, biphenylene, or naphthylene which may have 1 to 3 substituents selected from the group consisting of halogen atoms. Y represents -O-CO-, -CO-O-, -CONH- or NHCO-.)

  X is preferably 1,2-phenylene, 1,3-phenylene or 1,4-phenylene, and particularly preferably 1,4-phenylene.

Particularly preferred divalent groups represented by R ² and having 2 to 50 carbon atoms include divalent groups having the following structures.

_{- (CH 2) n1 - (} n1 = 2~10)
_{-C 6 H 4 OCO (CH 2} ) n2 - (n2 = 2~10)
_{-C 6 H 4 (CH 2)} n3 - (n3 = 1~10)
_{-CH 2 CH 2 (OCH 2 CH} 2) n4 - (n4 = 1~10)
_{-C 6 H 4 CO (OCH 2} CH 2) n5 - (n5 = 1~10)

  The (meth)acrylate compound represented by the general formula (c-1) can be produced by a known method.

  The hydroxyl group-containing (meth)acrylate monomer (c-2) is represented by the following general formula (c-2).

In the formula, R ³ is H or a methyl group. R ⁴ is a divalent group having 2 to 50 carbon atoms, preferably 2 to 10 carbon atoms, or an alkylene oxide group having 2 to 20 repeating units.

In formula (c-2), examples of the divalent group represented by R ⁴ and having 2 to 50 carbon atoms include the divalent groups exemplified for R ² . The carbon number of this divalent group is preferably 2-10.

The alkylene oxide group having 2 to 20 repeating units represented by R ⁴ is more preferably a polyalkylene oxide group having an ethylene oxide group, a propylene oxide group or the like as a repeating unit. The repeating unit of the alkylene oxide in the polyalkylene oxide group is preferably 2 to 20.

Particularly preferred R ⁴ includes the following groups.

_{- (CH 2) n6 - (} n6 = 2~10)
_{- (CH 2 CH 2 O)} n7 CH 2 CH 2 - (n7 = 1~20)
_{- (CHCH 3 CH 2 O)} n8 CHCH 3 CH 2 - (n8 = 1~10)

  The compound represented by formula (c-2) can be produced by a known method, or can be obtained as a commercial product. As a commercial item of the compound represented by general formula (c-2), NOF Corporation Blemmer AE-90, NOF Corporation Blemmer AE-200, NOF Corporation Blemmer AE-400, NOF Corporation Bremmer AP-400, NOF Corporation Bremmer PE-90, NOF Corporation Bremmer PE-200, NOF Corporation Bremmer PE-350, NOF Corporation. Bremmer PP-1000, NOF CORPORATION Blemmer 50PEP-300, NOF Corporation Bremmer 70PEP-350, NOF Corporation Bremmer 55PET-800, 2-hydroxyethyl acrylate (Kyoeisha Chemical Co., Ltd.) , Light ester HO-250), 2-hydroxyethyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., light ester HOA), 4-hydroxybutyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., 4-HBA) and the like.

  The (meth)acrylate copolymer containing (c) a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom is a fluorine-containing (meth)acrylate monomer (c-1) and a hydroxyl group-containing (meth)acrylate. In addition to the monomer (c-2), a (meth)acrylate (c-3) represented by the following general formula (c-3) can be used as a monomer forming a constitutional unit of the copolymer.

In the formula, R ⁵ is H or a methyl group. R ⁶ is an optionally substituted aromatic hydrocarbon group. n is an integer of 0-4.

In the general formula (c-3), examples of the aromatic hydrocarbon group represented by R ⁶ include a phenyl group, a naphthyl group, a toluyl group, a xylyl group, an anthranyl group, a phenanthryl group, a biphenyl group, and the like. ~ 15 aromatic hydrocarbon groups. The substituent of the substituted aromatic hydrocarbon groups include methyl, ethyl, propyl, butyl, methoxy, ethoxy, methylenedioxy, chlorine _atom, NO 2, CN, and the like NHCOCH _3. The aromatic hydrocarbon group may contain 1 to 3 substituents, preferably 1 to 2 substituents.

  As the (meth)acrylate compound represented by the general formula (c-3), benzyl methacrylate is particularly preferable.

  The compound represented by the general formula (c-3) can be produced by a known method, or as a commercial product, light ester BZ (manufactured by Kyoeisha Chemical Co., Ltd.), FANCLyl FA-BZM (Hitachi Chemical Co., Ltd.). Manufactured) can also be obtained.

  Moreover, the (meth)acrylate (c-4) represented by the following general formula (c-4) can also be used as a monomer which forms the structural unit of a copolymer.

In the formula, R ⁷ is H or a methyl group. R ⁸ is H or an aliphatic hydrocarbon group having 1 to 50 carbon atoms.

In the general formula (c-4), R ⁸ is an aliphatic hydrocarbon group having 1 to 50 carbon atoms. The aliphatic hydrocarbon group may have an ether bond, an ester bond, an amide bond or a cyclic structure.

Preferred R ⁸ includes a cyclic structure such as an alkyl group, a cyclohexyl group, a dicyclopentanyl group, a dicyclopentenyl group. Particularly preferable R ⁸ includes an aliphatic hydrocarbon group having the following structure.

_{- (CH 2) n6 CH 3} (n6 = 1~30)

  The compound represented by formula (c-4) can be produced by a known method, or can be obtained as a commercial product. As a commercial item of the compound represented by the general formula (c-4), NOF Corporation Blemmer CHMA, NOF Corporation Blemmer LMA, NOF Corporation Blemmer SMA, NOF Corporation Blemmer VMA, NOF Corporation Blemmer CHA, NOF Corporation Blemmer LA, NOF Corporation Blemmer SA, NOF Corporation Blemmer VA, Hitachi Chemical Co., Ltd. FA-513AS, Hitachi FA-513M manufactured by Kasei Co., Ltd. and the like can be mentioned.

  The content of the (meth)acrylate copolymer containing (c) a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom in the resin composition for the coating layer is (a) polyol, (b) isocyanate, And 0.1 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the (c) (meth)acrylate copolymer.

(D) Surface roughening material The coating layer 4 contains a surface roughening material. The surface roughness material is particles that adjust the surface roughness of the coating layer 4. The average particle diameter of the surface roughening material blended in the coating layer 4 is preferably 0.1 μm or more and 20 μm or less, more preferably 1 μm or more and 15 μm or less. By blending such a surface roughness material in the coating layer 4, the surface roughness of the outer peripheral surface can be easily adjusted to an appropriate range. By adjusting the surface roughness of the outer peripheral surface of the developing roller 1, the toner transportability is improved and more excellent printing characteristics are obtained. The average particle diameter of the surface roughness material can be measured as a median diameter by using a particle size distribution measuring device by a laser light diffraction method.

  The type of surface roughness material to be blended in the coating layer 4 is not particularly limited, and can be appropriately selected and used from known fillers (fillers). For example, it may be silica, spherical resin particles, metal oxide or the like.

  The content of the surface roughness material in the resin composition for coating layer is preferably 0.1 to 50 parts by mass, and 1 to 40 parts by mass with respect to 100 parts by mass of the resin composition for coating layer. Is more preferable.

(E) Ion Conductive Material Examples of the ion conductive material include sodium perchlorate, lithium perchlorate, calcium perchlorate, lithium chloride, lithium bis(trifluoromethanesulfonyl)imide, and potassium bis(trifluoromethanesulfonyl)imide. Inorganic ionic conductive substances and the like. The content of the ionic conductive material in the coating layer resin composition is preferably 0.01 to 5 parts by mass, and 0.1 to 3 parts by mass, relative to 100 parts by mass of the coating layer resin composition. Is more preferable.

  The coating layer 4 may further contain additives other than the above. For example, the coating layer 4 may further contain additives such as a silane coupling agent, a lubricant, a polymerization catalyst, a dispersant, and a filler.

  The coating layer 4 is obtained by applying the resin composition for a coating layer on the elastic layer 3 and containing (a) a polyol component and (c) a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom by heating or the like ( The (meth)acrylate copolymer component and the (b) isocyanate component are polymerized and cured. The solvent used in the coating liquid is preferably a solvent capable of dissolving the polyol component and the isocyanate component, and may be, for example, ethyl acetate, butyl acetate or the like.

  The thickness of the coating layer 4 is specifically preferably 1 μm or more and 15 μm or less, and more preferably 3 μm or more and 10 μm or less, from the viewpoint of improving durable printing performance while satisfactorily suppressing filming.

The coating of the resin composition for the coating layer includes, for example, a coating method of applying a coating liquid of the resin composition for the coating layer, a dipping method of dipping an elastic layer or the like in the coating liquid, an elastic layer of the coating liquid, etc. It is carried out by a known coating method such as a spray coating method of spraying on. The resin composition for the coating layer may be applied as it is, or may be applied to the resin composition for the coating layer, for example, alcohols such as methanol and ethanol, aromatic solvents such as xylene and toluene, ethyl acetate and butyl acetate. You may apply the coating liquid which added volatile solvents, such as ester type solvent of this, or water. The method for curing the coating layer resin composition thus coated may be any method capable of applying heat necessary for curing the coating layer resin composition, for example, a coating layer resin composition. Examples of the method include a method of heating an elastic layer or the like coated with No. 1 with a heater, a method of leaving the elastic layer or the like coated with the resin composition under high humidity. The heating temperature for heat-curing the resin composition for coating layer is, for example, preferably 100° C. or higher and 200° C. or lower, particularly preferably 120° C. or higher and 160° C. or lower, and the heating time is 10 minutes or longer. It is preferably 120 minutes or less, and more preferably 30 minutes or more and 60 minutes or less.
In the coating layer thus formed, the precursor forming the resin and the ionic conductive material may react to be integrated with each other, or may form a composite. Further, the ionic conductive material may be dispersed in the resin without reacting with the precursor forming the resin.

  The coating layer in the present invention is formed by heating and curing the resin composition for a coating layer, and the content of fluorine atoms in the resin composition for a coating layer is preferably less than 5% by mass. The content is more preferably 0.01% by mass or more and 5% by mass or less, further preferably 0.1% by mass or more and 4.5% by mass or less, and most preferably 0.1% by mass or more and 4% by mass or less. When the content is 0.1% by mass or more, elemental fluorine is transferred to the surface of the coating layer, and the oil repellency of the surface of the coating layer is improved, so that filming can be favorably prevented. If a large amount of a compound containing a fluorine atom (for example, a fluorine-based surfactant or the like) is added to improve oil repellency, the conductivity decreases, so the content of the conductive filler must be increased. Further, when the content of the conductive filler is increased, the resin becomes harder, so that the abrasion resistance of the coating layer is lowered, the durability printing performance is lowered, and the cost is increased. Further, when the conductivity-imparting agent is an ion-conducting agent, it is compounded in a large amount, which causes problems of cost increase and bleeding. However, by setting the content of fluorine atoms as described above, it is not necessary to increase the conductive filler and the coating layer can be softened, so that the durability of the coating layer is improved and a developing roller having excellent durability printing performance can be obtained. Obtainable.

  Since the coating layer produced by the resin composition for a coating layer in the present invention contains a (meth)acrylate copolymer containing a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom, the fluorine atom is a resin. Is unevenly distributed in the vicinity of the surface of the coating layer in a state of being taken in as a part of. Therefore, since the coating layer of the present invention has fluorine atoms on the surface for a long period of time, the developer melted by the operation of the image forming apparatus hardly adheres to the coating layer, and the amount of the developer fixed to the coating layer is significantly increased. It is possible to reduce the number and provide a high-quality image.

-Glass transition point Tg-
The coating layer of the developing roller of the present invention has a glass transition point Tg of -50°C or higher and 0°C or lower. The glass transition point Tg is preferably −40° C. or higher and 0° C. or lower.
When the glass transition point Tg is −50° C. or higher, the adhesiveness of the developer becomes good and the carrying force is improved. Further, when the glass transition point Tg is 0° C. or lower, the coating film has flexibility, the toner damage is reduced, and the abrasion property is good, so that the durability is improved.
The glass transition point Tg of the coating layer is a value measured by the measuring method described in Examples below.

-Dynamic friction coefficient μD-
The dynamic friction coefficient μD of the developing roller of the present invention is 0.05 or more and 0.6 or less. The dynamic friction coefficient μD is preferably 0.05 or more and 0.5 or less. When the dynamic friction coefficient μD is 0.05 or more, the scraping property of the developer is improved, so that the occurrence of the ghost phenomenon can be suppressed. Further, when the coefficient of dynamic friction μD is 0.6 or less, the developer can be satisfactorily conveyed.
The dynamic friction coefficient μD is a value measured by the measuring method described in Examples below.

-Arithmetic surface roughness Ra-
The coating layer of the developing roller of the present invention has an arithmetic surface roughness Ra of 0.4 or more and 1.5 or less. The arithmetic surface roughness Ra is preferably 0.4 or more and 0.9 or less. When the arithmetic surface roughness Ra is 0.4 or more, the developer carrying force can be increased. Further, when the arithmetic surface roughness Ra is 1.5 or less, the toner does not remain on the unevenness of the surface of the coating layer, and thus filming can be effectively prevented.
The arithmetic surface roughness Ra is a value measured by the measuring method described in Examples below.

(Other configurations)
The developing roller 1 of the present invention may include an intermediate layer such as an adhesive layer or a primer layer between the shaft body 2 and the elastic layer 3 and between the elastic layer 3 and the coating layer 4. Here, among these intermediate layers, particularly the adhesive layer and the primer layer provided between the elastic layer 3 and the coating layer 4, the electrical characteristics of the developing roller 1 are adjusted by adjusting the electrical characteristics thereof. Can be adjusted, whereby the developing performance of the developing roller 1 can be adjusted well.

  As the primer layer, those usually used as a primer layer of a developing roller can be used. For example, by forming a primer layer made of a urethane resin having an ester group, the developing performance of the developing roller 1 can be improved. Can be maintained.

[Developing device and image forming device]
Next, an embodiment of the developing device and the image forming apparatus of the present invention will be described with reference to FIG.
The developing roller 1 of the present invention can be suitably used as a developer carrier in a developing device and an image forming apparatus. In this embodiment, the configuration other than the developing roller in the image forming apparatus is not particularly limited.

  The image forming apparatus 10 includes a plurality of image carriers 11B, 11C, 11M, and 11Y provided in the developing units B, C, M, and Y of each color (black, cyan, magenta, and yellow) in series on the transfer/conveying belt 6. In the tandem type color image forming apparatus, the developing units B, C, M and Y are arranged in series on the transfer/conveying belt 6. The developing unit B includes an image carrier 11B such as a photoconductor (also referred to as a photosensitive drum), a charging unit 12B such as a charging roller, an exposure unit 13B, a developing device 20B, and an image carrier via the transfer/conveying belt 6. A transfer unit 14B, which is in contact with the body 11B, for example, a transfer roller, and a cleaning unit 15B are provided.

  The developing device 20B is an example of the developing device of the present invention, and includes the developing roller 1 of the present invention and a developer 22B as shown in FIG. Therefore, in this image forming apparatus 10, the developing roller 1 is mounted as the developer carrying members 23B, 23C, 23M and 23Y. Specifically, the developing device 20B includes a housing 21B containing a one-component non-magnetic developer 22B, a developer carrier 23B that supplies the developer 22B to the image carrier 11B, and a developer carrier 23B. The toner supply roller 25B for supplying the developer 22B and the developer amount adjusting means 24B for adjusting the thickness of the developer 22B, for example, a blade are provided. In the developing device 20B, the developer amount adjusting means 24B is in contact with or in pressure contact with the outer peripheral surface of the developer carrier 23B, as shown in FIG. That is, the developing device 20B is a "contact type developing device". The developing units C, M, and Y are basically configured similarly to the developing unit B, and the same elements are denoted by the same reference numerals and the symbols C, M, or Y indicating the respective units, and description thereof will be omitted. ..

  In the image forming apparatus 10, the developer carrying member 23B of the developing device 20B is arranged so that its surface is in contact with or in pressure contact with the surface of the image carrying member 11B. Similarly to the developing device 20B, the developing devices 20C, 20M and 20Y are arranged such that the surfaces of the developing agent carriers 23C, 23M and 23Y are in contact with or in pressure contact with the surfaces of the image carriers 11C, 11M and 11Y. .. That is, the image forming apparatus 10 is a “contact type image forming apparatus”.

  The fixing unit 30 is arranged on the downstream side of the developing unit Y. The fixing unit 30 includes a fixing roller 31, an endless belt supporting roller 33 disposed near the fixing roller 31, a fixing roller 31, and an endless belt in a housing 34 having an opening 35 through which the recording medium 16 passes. An endless belt 36 wound around the support roller 33 and a pressure roller 32 arranged to face the fixing roller 31 are provided, and the fixing roller 31 and the pressure roller 32 are in contact with each other or pressed against each other via the endless belt 36. The heat and pressure fixing device is rotatably supported as described above. 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 is a developer that can be charged by friction, and a non-magnetic developer or a magnetic developer. It may be an agent. In the housings 21B, 21C, 21M and 21Y of the developing units B, C, M and Y, one-component non-magnetic black developer 22B, cyan developer 22C, magenta developer 22M and yellow developer 22Y are stored. Each is stored.

  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 on the surface of the image carrier 11B charged by the charging unit 12B by the exposure unit 13B, and a black electrostatic latent image is formed by the developer 22B supplied by the developer carrier 23B. The image is developed. Then, when the recording body 16 passes between the transfer means 14B and the image carrier 11B, a black electrostatic latent image is transferred onto the surface of the recording body 16. Then, similarly to the developing unit B, the cyan image, the magenta image, and the yellow image are superimposed on the recording body 16 whose electrostatic latent image has been visualized as a black image by the developing units C, M, and Y, respectively. The color image is visualized. Then, the recording body 16 on which the color image is visualized is fixed on the recording body 16 by the fixing means 30 as a permanent image. In this way, a color image can be formed on the recording body 16.

  The developing device 20B includes the developing roller 1 and is excellent in developer transportability and can suppress the occurrence of toner filming to contribute to forming a high-density and high-quality image for a long time. Further, the image forming apparatus provided with the developing device 20B can form a high density and high quality image for a long period of time.

  The developing device and the image forming apparatus of the present invention are not limited to those described above, and various modifications can be made within the range in which the object of the present invention can be achieved.

  The image forming apparatus is an electrophotographic image forming apparatus, but in the present invention, the image forming apparatus is not limited to the electrophotographic method and may be, for example, an electrostatic image forming apparatus. .. Further, the image forming apparatus provided with the developing roller of 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/conveying belt. A monochrome image forming apparatus having a single developing unit, a four-cycle type color image forming apparatus in which primary transfer of a developer image carried on an image carrier to an endless belt is sequentially repeated may be used. Further, the developer used in the image forming apparatus is a one-component non-magnetic developer, but in the present invention, it may be a one-component magnetic developer or a two-component non-magnetic developer. Also, it may be a two-component magnetic developer.

  The image forming apparatus is a contact type image forming apparatus which is arranged in contact with or in pressure contact with an image carrier, a developer supply roller, a blade and the like. The image forming apparatus of the present invention may be a non-contact type image forming apparatus in which the surface of the developer carrying member is arranged with a gap so as not to contact the surface of the image carrying member.

  Although the present invention has been described above by using the embodiment, it goes without saying that the technical scope of the present invention is not limited to the scope of the invention described in the above embodiment, and various modifications or changes are made to the above embodiment. It will be apparent to those skilled in the art that modifications can be made. It is also apparent from the scope of the claims that the invention added with such changes or improvements can be included in the technical scope of the present invention.

  Hereinafter, the present invention will be described in detail with reference to examples. The present invention is not limited to the examples shown below.

[Example 1]
(Formation of primer layer)
A shaft body (SUM22, diameter 10 mm, length 275 mm) that has been subjected to electroless nickel plating is washed with ethanol, and a silicone-based primer (trade name “Primer No. 16”, manufactured by Shin-Etsu Chemical Co., Ltd.) on the surface of the shaft body. ) Was applied. The shaft body subjected to the primer treatment was baked at a temperature of 150° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or longer to form a primer layer on the outer peripheral surface of the shaft body.

(Formation of elastic layer)
Then, a silicone rubber composition for forming an elastic layer was prepared as follows. That is, 100 parts by mass of dimethylpolysiloxane (polymerization degree: 300) having both ends blocked with dimethylvinylsiloxy groups, and a hydrophobized fumed silica having a BET specific surface area of 110 m ² /g (trade name: “R-972” , Manufactured by Nippon Aerosil Co., Ltd.), 40 parts by mass of diatomaceous earth (trade name “Oplite W-3005S”, manufactured by Chuo Silica Co., Ltd.) having an average particle diameter of 6 μm and a bulk density of 0.25 g/cm ^3. 5 parts by mass of acetylene black (trade name "Denka Black HS-100", manufactured by Denka Co., Ltd.) were placed in a planetary mixer, stirred for 30 minutes, and then passed through a triple roll once. This was returned to the planetary mixer again, and 2.1 parts by mass of methylhydrogenpolysiloxane having Si-H groups at both ends and side chains (degree of polymerization 17, Si-H amount 0.0060 mol/g), ethynylcyclohexanol. 0.1 part by mass and 0.1 part by mass of a platinum-based catalyst (Pt concentration 1% by mass) were added, and the mixture was stirred and defoamed for 30 minutes to prepare an addition curable liquid conductive silicone rubber composition.

  The prepared addition-curable liquid conductive silicone rubber composition was injection molded using a mold to mold an elastic body made of a rubber material on the outer peripheral surface of the shaft body. In injection molding, the addition curable liquid conductive silicone rubber composition was heated at 120° C. for 10 minutes to be cured, and secondary vulcanization was performed at 200° C. for 4 hours to form an elastic layer having an outer diameter of 16 mm.

(Formation of coating layer)
Then, a resin composition for forming the coating layer was prepared as follows.
In addition, in the resin composition for a coating layer of each Example and Comparative Example, the total content of (a) polyol, (b) isocyanate, (c) hydroxyl group and 1 mass% or more and 10 mass% or less fluorine atom are contained. Table 1 shows the contents (parts by mass) of the (meth)acrylate copolymer, the (d) surface roughness material, and the (e) ion conductive material.

-Resin composition for coating layer-
(A) Acrylic polyol (UH-2041, manufactured by Toagosei) 20 parts by mass (b) Isocyanate (hexamethylene diisocyanate) 25 parts by mass (c) Containing a hydroxyl group and 1 to 10 mass% of fluorine atoms ( (Meth)acrylate copolymer 0.5 parts by mass (d) Surface roughness material (silica) ACEMATT OK607 manufactured by Evonik
3 parts by mass (e) Ion conductive material (potassium bis(trifluoromethanesulfonyl)imide, trade name "EF-N112", manufactured by Mitsubishi Materials Denshi Kasei Co., Ltd.) 0.2 parts by mass Mol of polyisocyanate and condensed polyester polyol The ratio [NCO/OH] was 1.1/1.

  The resin composition for a coating layer was applied to the outer peripheral surface of the elastic layer by a spray coating method and heated at 160° C. for 30 minutes to form a coating layer having a layer thickness of 3 to 7 μm. In this way, a developing roller provided with the shaft body, the elastic layer and the coating layer was manufactured.

[Example 2]
(D) Surface-roughness material in place of 0.5 parts by mass to 1.0 parts by mass of the (meth)acrylate copolymer containing a hydroxyl group and 1 to 10 mass% of fluorine atoms. A resin composition for a coating layer was prepared and a coating layer was formed in the same manner as in Example 1 except that 5 parts by mass of ACEMATT OK412 was used as silica.

[Example 3]
(A) 4 parts by mass of 20 parts by mass of acrylic polyol was replaced with acrylic copolymerized fluororesin (trade name "TR-101", manufactured by DIC Corporation), and (d) surface roughness material silica was replaced by ACEMATT OK4123. A resin composition for a coating layer was prepared and a coating layer was formed in the same manner as in Example 1 except that the amount was changed to parts by mass.

[Example 4]
(C) Similar to Example 3 except that the (meth)acrylate copolymer containing a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom was changed from 0.5 parts by mass to 0.25 parts by mass. A resin composition for a coating layer was prepared to form a coating layer.

[Comparative Example 1]
(C) A resin composition for a coating layer was prepared in the same manner as in Example 2 except that the (meth)acrylate copolymer containing a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom was not added. The coating layer was formed.

[Comparative example 2]
(A) 20 parts by mass of acrylic polyol SU-28 (manufactured by Soken Chemical Industry Co., Ltd.), (b) 12 parts by mass of isocyanate (hexamethylene diisocyanate), (d) 1 part by mass of surface roughness material ACEMATT OK607, ( c) A resin composition for a coating layer was prepared in the same manner as in Example 1 except that the (meth)acrylate copolymer containing a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom was not added, A coating layer was formed.

[Comparative Example 3]
(D) The surface-roughening material silica was changed to 3 parts by mass of ACEMATT OK412, 20 parts by mass of acrylic polyol was blended in place of the polyester polyol, and (c) a hydroxyl group and 1% by mass or more and 10% by mass or less of fluorine atoms were added. A resin composition for a coating layer was prepared in the same manner as in Comparative Example 2 except that 0.5 part by mass of a (meth)acrylate copolymer containing was added to form a coating layer.

[Evaluation]
Next, an image forming apparatus C610dn2 (model number, manufactured by Oki Data Co., Ltd.) was prepared, and the developing roller of this image forming apparatus was replaced with the developing roller of each Example and each comparative example to obtain an image forming apparatus. The obtained image forming apparatus was evaluated for filming, print density, and image uniformity by the following methods, and the results are shown in Table 1.

(Measurement method of glass transition point Tg)
Using an X-DSC7000 (trade name, manufactured by Hitachi High-Tech Science Co., Ltd.), about 10 mg of a sample was placed in an aluminum container, an aluminum lid was placed on the aluminum container, crimped, and set in the apparatus. In a nitrogen atmosphere, the temperature was raised from −80° C. to 60° C. at a heating rate (10° C./min), and DSC measurement was performed. The glass transition point Tg was calculated from the contact point between the tangent line of the endothermic curve near the glass transition point Tg and the base line.

(Measurement method of dynamic friction coefficient μD)
The dynamic friction coefficient μD of the developing roller was measured by the following procedure.
A schematic view of a measuring machine used for measuring the dynamic friction coefficient in the present invention is shown in FIG. This measuring method is based on Euler's belt method.
As shown in FIG. 3, the measuring machine 100 includes a developing roller 101 to be measured and a belt (thickness 100 μm, width 30 mm, length 200 mm, polyethylene terephthalate (PET) which is in contact with the developing roller 101 at a predetermined angle θ. ), trade name: Lumirror S10 #100, manufactured by Toray Industries, Inc.) 102, a weight 103 connected to one end of the belt 102, and a force gauge 104 connected to the other end of the belt 102. In the state shown in FIG. 3, when the developing roller 101 is rotated in a predetermined direction at a predetermined speed, the force measured by the force gauge 104 is F [g weight], the sum of the weight of the weight and the weight of the belt. When W [g weight] is set, the friction coefficient is calculated by the following formula.
Friction coefficient μD=(1/θ)ln(F/W)
The value immediately after rotating the developing roller is the force required to start the rotation, and the value after that is the force required to continue the rotation. Therefore, the friction coefficient at the rotation start point (that is, at the time of t=0 [seconds]) is the static friction coefficient, and the friction coefficient at any time t>0 [seconds] is the dynamic friction coefficient at any time. In the present invention, the average value of the friction coefficient obtained in 5 seconds from 5 seconds after the start of rotation (that is, the time point of t=5 [seconds]) to 10 seconds after that (that is, the time point of t=10 [seconds]) is given as above. The dynamic friction coefficient of μD. In the present invention, W=50 [g weight], the developing roller rotation speed was 200 rpm, and the measurement environment was 23° C./55% RH.

(Measurement method of arithmetic mean roughness Ra)
The arithmetic average roughness Ra of the developing roller manufactured as described above was measured by a surface roughness meter (trade name "Surfcom 1400G", manufactured by Tokyo Seimitsu Co., Ltd.) based on JIS B0601-2001.

(Content of Fluorine Atom in Resin Composition for Coating Layer)
The resin composition for the coating layer is cut out, 0.01 g is burned and absorbed by a sample combustion apparatus AQF-2100H (trade name, manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and the absorption liquid is ion chromatograph (manufactured by Shimadzu Corporation). Analysis was performed to determine the content of fluorine.

(Filming evaluation)
Using the image forming apparatus equipped with the developed developing roller, at the temperature of 23° C. and the humidity of 55% RH, the developer adhering to the surface of the developing roller after printing 10000 sheets is sucked and the filming weight is measured. The mass transferred to the jig was measured. For the filming evaluation, the mass of the transferred developer was evaluated according to the following criteria. In this test, the filming amount is evaluated as B when the evaluation is B.
-Evaluation criteria-
A: The mass of the transferred developer is 0 mg or more and less than 0.02 mg B: The mass of the transferred developer is 0.02 mg or more and less than 0.05 mg C: The mass of the transferred developer is 0.05 mg or more

(Evaluation of print density)
Two solid images are printed under the conditions of a temperature of 23° C. and a humidity of 55% RH, a temperature of 30° C. and a humidity of 80% RH, and a temperature of 10° C. and a humidity of 20% RH. The print density of a solid image was measured using a 508 spectral densitometer manufactured by Rite and evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: Print density is 1.4 or more B: Print density is 1.2 or more and less than 1.4 C: Print density is 1.0 or more and less than 1.2

(Evaluation of image uniformity)
A solid image is printed under the conditions of a temperature of 23° C. and a humidity of 55% RH, a temperature of 30° C. and a humidity of 80% RH, and a temperature of 10° C. and a humidity of 20% RH. And the print density of the 2000th sheet were compared. Specifically, the density step ratio between the initial print forming portion and the final print forming portion of solid printing was obtained and evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: Density step ratio is within 1.1 B: Density step ratio is above 1.1 and within 1.2 C: Density step ratio is above 1.2

  The evaluation results are shown in Table 1.

  As shown in Table 1, it can be seen that the developing roller having the coating layer of the present invention is excellent in filming, print density, and image uniformity.

DESCRIPTION OF SYMBOLS 1 developing roller 2 shaft body 3 elastic layer 4 coating 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 exposing means 14B, 14C, 14M, 14Y Transfer means 15B, 15C, 15M, 15Y Cleaning means 16 Recording bodies 20B, 20C, 20M, 20Y Developing devices 21B, 21C, 21M, 21Y, 34 Housings 22B, 22C, 22M, 22Y Developer 23B, 23C, 23M, 23Y developer carrier 24B, 24C, 24M, 24Y developer amount adjusting means 25B, 25C, 25M, 25Y toner supply roller 30 fixing means 31 fixing roller 32 pressure roller 33 endless belt support roller 35 opening 36 Endless belt 41 Cassette 42 Support roller B, C, M, Y Developing unit 100 Measuring machine 101 Developing roller 101
102 belt 103 weight 1
104 force gauge

Claims (5)

A developing roller comprising an elastic layer formed on the outer peripheral surface of a shaft and a coating layer formed on the outer peripheral surface of the elastic layer,
The coating layer has a glass transition point Tg of −50° C. or higher and 0° C. or lower, a dynamic friction coefficient μD of 0.05 or higher and 0.6 or lower, and an arithmetic mean roughness Ra of 0.4 or higher and 1.5 or lower. Developing roller.   The developing roller according to claim 1, wherein the coating layer is formed by curing the resin composition for a coating layer, and the content of fluorine atoms in the resin composition for the coating layer is less than 5% by mass.   The resin composition for a coating layer comprises (a) a polyol, (b) an isocyanate, (c) a hydroxyl group and a (meth)acrylate copolymer containing 1% by mass or more and 10% by mass or less of a fluorine atom, (d). The developing roller according to claim 2, further comprising a surface roughening material and (e) an ion conductive material.   A developing device comprising the developing roller according to claim 1.   An image forming apparatus comprising the developing roller according to claim 1.

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