JP7207632B2 - Developing roller, developing device and image forming device - Google Patents

Description

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

2. Description of the Related Art A developing roller used in image forming apparatuses such as copiers, printers, and facsimiles that employ an electrophotographic method 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. Therefore, it has been studied to improve the developer transportability of the developing roller by forming unevenness on the surface of the developing roller and adjusting the electrical properties of various materials constituting the developing roller.

The developing roller is in contact with the photosensitive drum and is rotated in the same direction with a difference in speed, thereby causing the toner to adhere to the photosensitive drum. Therefore, if the surface slippage of the developing roller is poor, the developing roller is repeatedly caught and released from the photosensitive drum. In such a case, since the toner is not uniformly supplied to the photosensitive drum, band-like shading occurs in the image.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing roller, a developing device, and an image forming apparatus in which banding is suppressed satisfactorily.

The present inventors have investigated various resins used in the coating layer in order to eliminate the problem of the developing roller being caught on the photosensitive drum. was found to be improved, and the present invention was completed.

That is, the developing roller of the present invention includes an elastic layer formed on the outer peripheral surface of the shaft and a coating layer formed on the outer peripheral surface of the elastic layer, wherein the coating layer comprises (a) a polyol , (b) an isocyanate, (c) a surface roughness agent, and (d) a coating layer resin composition containing a conductive material is thermally cured, and (a) the polyol is unreacted with the (a1) side chain and (a2) one end diol type silicone oil.

The content of at least one of (a1) a polyol having an unreactive silicone group in a side chain and (a2) a one-end diol-type silicone oil in the (a) polyol is 2% by mass or more and 60% by mass or less. Preferably.

Among (a1) a polyol having an unreactive silicone group in a side chain and (a2) a one-end diol-type silicone oil, (a1) contains only a polyol having an unreactive silicone group in a side chain, and (a1) a side chain The polyol having unreactive silicone groups is preferably a silicone-grafted acrylic polyol.

In the above case, the content of the silicone-grafted acrylic polyol in the (a) polyol is preferably 2% by mass or more and 40% by mass or less.

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

An 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 banding is satisfactorily suppressed.

FIG. 1 is a schematic perspective view showing one embodiment of the developing roller of the present invention. FIG. 2 is a schematic cross-sectional view showing an embodiment of the image forming apparatus of the invention.

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

[Development roller]
FIG. 1 is a schematic perspective view showing one embodiment of the developing roller of the present invention.
The developing roller 1 of the present invention has a shaft 2, an elastic layer 3 provided on the outer periphery of the shaft 2, and a coating layer 4 provided on the outer periphery of the elastic layer 3, as shown in FIG.
The configuration of the developing roller 1 of the present invention will be described below.

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

The shaft 2 may contain insulating resin. The insulating resin may be, for example, a thermoplastic resin or a thermosetting resin. The shaft 2 may include, for example, a core made of insulating resin and a plated layer provided on the core. Such a shaft 2 can be obtained, for example, by plating a core made of an insulating resin to make it conductive.

The shaft 2 is preferably a metal core in order to obtain good conductivity.

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

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

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

Rubbers in the rubber composition include, for example, 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, epichlorohydrin rubber, urethane rubber, fluororubber, and the like. Silicone or silicone-modified rubber or urethane rubber is preferable, and silicone or silicone-modified rubber can reduce compression set and has excellent flexibility in a low-temperature environment, as well as heat resistance and electrification properties. It is particularly preferable in that it is excellent in the above. Examples of silicone rubbers include crosslinked organopolysiloxanes such as dimethylpolysiloxane and diphenylpolysiloxane.
Examples of silicone rubber compositions 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 may contain, for example, (A) an organopolysiloxane represented by the following average compositional formula (1), (B) a filler, and (C) a conductive material. .
R ¹ _n SiO _(4−n)/2 (1)
In formula (1), n represents a positive number of 1.95 or more and 2.05 or less. Also, 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 include alkenyl groups, aryl groups such as phenyl and tolyl groups, and aralkyl groups such as β-phenylpropyl groups. Also, R ¹ may be a group in which some or all of the hydrogen atoms of these hydrocarbon groups have been substituted with a substituent. Substituents may be, for example, halogen atoms, cyano groups, and the like. Hydrocarbon groups having a substituent include, for example, a chloromethyl group, a trifluoropropyl group, a cyanoethyl group and the like.

(A) Organopolysiloxane has a molecular chain end which is a trialkylsilyl group such as a trimethylsilyl group, a dialkylaralkylsilyl group such as a dimethylvinylsilyl group, a dialkylhydroxysilyl group such as a dimethylhydroxysilyl group, a trivinylsilyl group, or the like. It is preferably blocked with a trialalkylsilyl group or the like.

(A) Organopolysiloxane preferably has two or more alkenyl groups in the molecule. (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 . (A) A vinyl group is particularly preferable as the alkenyl group possessed by the organopolysiloxane.

(A) Organopolysiloxane is obtained, for example, by cohydrolytic condensation of one or more organohalosilanes, or by ring-opening polymerization of a cyclic polysiloxane such as a siloxane trimer or tetramer. can be obtained by (A) Organopolysiloxane may be basically linear diorganopolysiloxane, and may be partially branched. Also, (A) organopolysiloxane may be a mixture of two or more different molecular structures.

(A) The organopolysiloxane preferably has a kinematic viscosity at 25° C. of 100 cSt or more, more preferably 100,000 cSt or more and 1,0000,000 cSt or less. The degree of polymerization of (A) organopolysiloxane is preferably, for example, 100 or more, and more preferably 3,000 or more and 10,000 or less.

(B) Fillers include, for example, silica-based fillers. Silica-based fillers include, for example, 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, such as glycidyl group, vinyl group, aminopropyl group, methacryloxy group, N-phenylaminopropyl group, mercapto group and the like. R3 may be an alkyl group ^, such as a methyl group, an ethyl group, and the like. Silane coupling agents are readily available, for example, under the trade names of "KBM1003" and "KBE402" manufactured by Shin-Etsu Chemical Co., Ltd. A surface-treated silica-based filler can be obtained by treating the surface of a silica-based filler with a silane coupling agent according to a conventional method. As the surface-treated silica-based filler, a commercially available product may be used. M. Trade name "Zeothix 95" manufactured by HUBER Corporation and the like can be mentioned.

The amount of the silica-based filler compounded is preferably 11 parts by mass or more and 39 parts by mass or less, more preferably 15 parts by mass or more and 35 parts by mass or less per 100 parts by mass of the organopolysiloxane (A). 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 size of the silica-based filler can be measured as a median size using a particle size distribution analyzer based on a laser beam diffraction method.

(C) The amount of the conductive material compounded is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the organopolysiloxane (A). The amount of (C) the conductive material to be blended is preferably 15 parts by mass or less, more preferably 10 parts by mass or less per 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). Additives include, for example, auxiliary agents (chain extenders, cross-linking agents, etc.), catalysts, dispersants, foaming agents, anti-aging agents, antioxidants, pigments, coloring agents, processing aids, softeners, plasticizers, Examples include emulsifiers, heat resistance improvers, flame retardancy improvers, acid acceptors, heat conductivity improvers, release agents, solvents, and the like.

Specific examples of the additive 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-capped. Dispersants such as low-molecular-weight siloxane and silane can be used. Specific examples of additives include heat resistance improvers such as iron octylate, iron oxide, and cerium oxide. As additives, various carbon functional silanes, various olefinic elastomers, and the like may be used for improving adhesiveness, molding processability, and the like.

-Addition Curing Liquid Conductive Silicone Rubber Composition-
The addition-curable liquid conductive silicone rubber composition comprises, for example, (D) an organopolysiloxane having two or more alkenyl groups in the molecule and (E) two or more hydrogen atoms bonded to silicon atoms in the molecule. (F) a filler; (G) a conductive material; and (H) an addition reaction catalyst.

(D) Organopolysiloxane is preferably a compound represented by the following average compositional formula (2).
R ⁴ _a SiO _(4-a)/2 (2)
In 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, more preferably 1.95 or more and 2.05 or less. R ⁴ also represents a substituted or unsubstituted monovalent hydrocarbon group, which may be the same or different. However, at least two of ^R4 's 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 for R ¹ above. At least two of the ^R4 's in one molecule are alkenyl groups, and the other ^R4 's are preferably alkyl groups. The alkenyl group is preferably a vinyl group and the alkyl group is preferably a methyl group. Moreover, 90% or more of R ⁴ may be an alkyl group (preferably a methyl group), for example. The alkenyl group content in (D) organopolysiloxane is, for example, 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.

(D) Organopolysiloxane is preferably liquid at 25 ° C., preferably has a viscosity at 25 ° C. of 100 mPa s or more and 1000000 mPa s or less, more preferably 200 mPa s or more and 100000 mPa s or less preferable. The average degree of polymerization of (D) organopolysiloxane is preferably 100 or more and 800 or less, more preferably 150 or more and 600 or less.

(E) Organohydrogenpolysiloxane is preferably a compound represented by the following average compositional formula (3).
R ⁵ _b H _c SiO _(4-bc)/2 (3)
In 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 also 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. Examples of R ⁵ include the same groups as those exemplified for R ¹ above.

(E) Organohydrogenpolysiloxane has two or more silicon-bonded hydrogen atoms (Si—H) in one molecule, preferably three or more. The number of silicon-bonded hydrogen atoms in one molecule of (E) organohydrogenpolysiloxane is preferably 200 or less, more preferably 100 or less.

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

Examples of (E) organohydrogenpolysiloxane include methylhydrogenpolysiloxane with both ends trimethylsiloxy group-blocked, dimethylsiloxane-methylhydrogensiloxane copolymer with both ends trimethylsiloxy group-blocked, and dimethylhydrogensiloxy group-blocked at both ends. Dimethylpolysiloxane, both ends dimethylhydrogensiloxy group-blocked dimethylsiloxane/methylhydrogensiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane/diphenylsiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane A diphenylsiloxane-dimethylsiloxane copolymer, a copolymer consisting of (CH ₃ ) ₂ HSiO _1/2 units and SiO _4/2 units, and (CH ₃ ) ₂ HSiO _1/2 units and SiO _4/2 units and a copolymer consisting of (C ₆ H ₅ )SiO _3/2 units.

The amount of (E) organohydrogenpolysiloxane compounded is preferably 0.1 to 30 parts by mass, and preferably 0.3 to 20 parts by mass, based on 100 parts by mass of (D) organopolysiloxane. The following are more preferable. Further, the molar ratio of Si—H in (E) organohydrogenpolysiloxane to alkenyl groups in (D) organopolysiloxane is preferably 0.3 to 5.0, more preferably 0.5 to 2.5. is more preferable.

(F) The filler may be, for example, an inorganic filler. By adding (F) the filler to the addition-curable liquid conductive silicone rubber composition, the compression set is lowered, the volume resistivity is stabilized over time, and sufficient roller durability is obtained.

(F) The average particle size of the filler is preferably 1 μm or more and 30 μm or less, more preferably 2 μm or more and 20 μm or less. (F) When the average particle size of the filler is 1 μm or more, the change in volume resistivity over time is further suppressed. Further, when the average particle size of the (F) filler is 30 μm or less, the elastic layer 3 having even better durability can be obtained. The average particle size of the filler (F) can be measured as a median size using a particle size distribution analyzer based on a laser beam diffraction method.

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

(F) Fillers include, for example, diatomaceous earth, perlite, mica, calcium carbonate, glass flakes, and hollow fillers. Among these, diatomaceous earth, perlite, and pulverized perlite foam can be suitably used as the filler (F).

The amount of filler (F) to be blended is preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 80 parts by mass or less based on 100 parts by mass of organopolysiloxane (D). .

(G) The amount of the conductive material compounded is preferably 0.5 parts by mass or more and 15 parts by mass or less, and 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the (D) organopolysiloxane. is more preferred.

(H) The addition reaction catalyst may be a catalyst capable of activating the addition reaction between (D) organopolysiloxane and (E) organohydrogenpolysiloxane. (H) Addition reaction catalysts include, for example, catalysts containing a platinum group element. Examples of catalysts having a platinum group element include platinum-based catalysts (e.g., platinum black, platinic chloride, chloroplatinic acid, reactants of chloroplatinic acid and monohydric alcohols, complexes of chloroplatinic acid and olefins , platinum bisacetoacetate, etc.), palladium-based catalysts, rhodium-based catalysts, and the like.

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

The addition-curable liquid conductive silicone rubber composition may further contain additives other than (D) to (H). Examples of additives include auxiliary agents (chain extenders, cross-linking agents, etc.), foaming agents, dispersants, antioxidants, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, Examples include heat resistance improvers, flame retardancy improvers, acid acceptors, heat conductivity improvers, mold release agents, diluents, reactive diluents, and solvents.

Specific examples of additives include dispersants such as low-molecular-weight siloxane esters, polyether-modified silicone oils, silanol, and phenylsilanediol. Heat resistance improvers such as iron octylate, iron oxide, and cerium oxide are also included. Also, various carbon functional silanes, various olefinic elastomers, and the like may be used for improving adhesiveness, molding processability, and the like. A halogen compound or the like that imparts flame retardancy may also be used.

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. The thickness in this specification indicates the thickness in the 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 preferably 6 mm or more and 25 mm or less, more preferably 7 mm or more and 21 mm.

The outer peripheral surface of the elastic layer 3 is subjected to surface treatment such as primer treatment, corona treatment, plasma treatment, excimer treatment, UV treatment, Itro treatment, and flame treatment for the purpose of improving adhesion with the coating layer 4, etc. you can

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

The elastic layer 3 is formed on the outer peripheral surface of the shaft 2 by performing heat curing and molding simultaneously or continuously by a known molding method. The method of curing the rubber composition may be any method as long as the heat necessary for curing the rubber composition is applied, and the method of molding the elastic layer 3 may be continuous vulcanization by extrusion molding, molding by press, injection molding, etc., and there are particular limitations. not to be For example, when the rubber composition is an addition-curable millable conductive silicone rubber composition, extrusion molding or the like can be selected, and the rubber composition is an addition-curable liquid conductive silicone rubber composition. In some cases, for example, a molding method using a mold can be selected.

The heating temperature for curing the rubber composition is preferably 100° C. or higher and 500° C. or lower, 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 to 1 hour, more preferably 10 seconds to 35 minutes. In the case of an 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 several seconds to 5 hours, more preferably 1 minute to 3 hours. Moreover, secondary vulcanization may be carried out as necessary. In the case of an addition-curable millable conductive silicone rubber composition, for example, curing conditions are selected at 100° C. or higher and 200° C. or lower for about 1 hour or longer and 20 hours or shorter. In addition, in the case of an addition-curable liquid conductive silicone rubber composition, for example, the curing conditions are selected at 120° C. or higher and 250° C. or lower for about 2 hours or more and 70 hours or less. Further, the rubber composition can be foamed and cured by a known method to easily form a sponge-like elastic layer having cells.

-Other ingredients-
The rubber composition may further contain various additives other than those described above. Examples of various additives include auxiliary agents (chain extenders, cross-linking agents, etc.), catalysts, dispersants, foaming agents, anti-aging agents, antioxidants, pigments, coloring agents, processing aids, softeners, plasticizers. , emulsifiers, heat resistance improvers, flame retardant improvers, acid acceptors, heat conductivity improvers, release agents, solvents and the like.

(coating layer)
The coating layer 4 is provided on the outermost surface of the developing roller 1 on the outer periphery of the elastic layer 3 . The coating layer 4 is formed by applying a composition (hereinafter referred to as a coating layer resin composition) to the outer peripheral surface of the elastic layer 3 or a primer layer formed as desired, and then applying the coated coating layer resin. It is formed by heat-curing the composition.
The coating layer 4 of the present invention is formed by thermosetting a coating layer resin composition containing (a) a polyol, (b) an isocyanate, (c) a surface roughness agent, and (d) a conductive material. , (a) the polyol contains at least one of (a1) a polyol having an unreactive silicone group in a side chain and (a2) a one-end diol-type silicone oil.
Each component (a) to (d) of the resin composition for coating layer will be described below.

(a) Polyol The polyol may be any of various polyols commonly used in preparing polyurethanes, and is preferably at least one polyol selected from polyether polyols, polyester polyols, polyacrylate polyols, and polycarbonate polyols. .

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

A polyester polyol has two or more ester bonds and two or more hydroxyl groups in the molecule. Polyester polyols include, for example, condensation reaction products of dicarboxylic acids and polyols. Examples of dicarboxylic acids 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 are copolymers of hydroxyl group-containing monomers and olefinically unsaturated monomers. For example, esters of (meth)acrylic acid, styrene, α-methylstyrene, vinyl toluene, vinyl esters, monoalkyl maleates, dialkyl maleates, monoalkyl fumarate, or dialkyl fumarate with α-olefins, Copolymers with unsaturated oligomers and unsaturated polymers.

Polycarbonate polyols have two or more carbonate bonds and two or more hydroxyl groups in the molecule. Polycarbonate polyols include, for example, condensation reaction products of polyols and carbonate compounds. Moreover, examples of the carbonate compound include dialkyl carbonate, diaryl carbonate, alkylene carbonate, and the like. Polyols used as raw materials for polycarbonate polyols include, for example, diols such as hexanediol and butanediol, and triols such as 2,4-butanetriol.
The polyol preferably has a number average molecular weight of 500 or more and 8,000 or less, more preferably 500 or more and 5,000 or less, from the viewpoint of excellent compatibility with isocyanate, etc., which will be described later. When the ionic liquid is a hydroxyl group-containing ionic liquid, it preferably has a number average molecular weight of 800 or more and 15000 or more, more preferably 1000 or more and 5000 or less. A number average molecular weight is a molecular weight when converted into standard polystyrene by gel permeation chromatography (GPC).

(a) The polyol contains at least one of (a1) a polyol having an unreactive silicone group in its side chain and (a2) a one-end diol-type silicone oil.
The (a1) polyol having an unreactive silicone group in the side chain and the (a2) one-end diol-type silicone oil are described below.

(a1) polyol having an unreactive silicone group in the side chain (a1) polyol having an unreactive silicone group in the side chain, for example, structural units represented by the following general formulas (1) and (2) and silicone-grafted acrylic polyols comprising:

In general formulas (1) and (2) above, R ¹ represents H or a methyl group. X is a divalent linking group having 1 or more and 12 or less carbon atoms. The linking group is preferably an alkylene group or an alkenylene group. R ² is an alkyl group having 1 to 12 carbon atoms and having a hydroxy group.

(a1) The polyol having an unreactive silicone group in its side chain preferably has a number average molecular weight of 500 or more and 300,000 or less.
(a1) The number average molecular weight of the silicone group in the polyol having an unreactive silicone group in its side chain is preferably 500 or more and 100,000 or less.
In addition, (a1) the silicone group in the polyol having an unreactive silicone group in the side chain is preferably 1% by mass or more and 50% by mass or less in the entire composition.

(a1) Commercially available polyols having an unreactive silicone group in the side chain include Shin-Etsu Chemical Co., Ltd., silicone-grafted acrylic resins, trade names: X-24-798A, X-22-8004 (R4: C2H4OH, functional group equivalent: 3250 (g / mol)), X-22-8009 (R4: Si (OCH3) 3 -containing alkyl group, functional group equivalent: 6200 (g / mol)), X-22-8053 (R4 : H, functional group equivalent: 900 (g / mol)), X-22-8084, X-22-8084EM, X-22-8195 (R4: H, functional group equivalent: 2700 (g / mol)), Toa Synthetic Co., Ltd. Cymac series (US-270, US-350, US-352, US-380, US-413, US-450, etc.), Reseta GS-1000 series (GS-1015, GS-1302, etc.) etc.

(a2) Single-ended diol-type silicone oil (a2) Examples of the single-ended diol-type silicone oil include those represented by the following general formula (3).

In the general formula (3), R ³ and R ⁶ are alkyl groups having 1 or more and 12 or less carbon atoms. R ⁴ represents a single bond or an alkylene group having 1 to 12 carbon atoms.

(a2) The viscosity of the single-ended diol-type silicone oil is preferably 130 or more and 550 or less (mm ² /s), and the hydroxyl value is preferably 8 or more and 35 or less (mgKOH/g).
(a2) The molecular weight of the single-ended diol-type silicone oil is preferably 3,000 or more and 15,000 or less.
Commercially available products include X-22-176DX, X-22-176F and X-22-176GX-A manufactured by Shin-Etsu Chemical Co., Ltd.

The content of at least one of (a1) a polyol having an unreactive silicone group in a side chain and (a2) a one-end diol-type silicone oil in the (a) polyol is 2% by mass or more and 60% by mass or less. is preferred, and more preferably 2% by mass or more and 30% by mass or less.
Among (a1) a polyol having an unreactive silicone group in a side chain and (a2) a one-end diol-type silicone oil, (a1) contains only a polyol having an unreactive silicone group in a side chain, and (a1) a side chain The polyol having unreactive silicone groups may be a silicone-grafted acrylic polyol. In this case, the content of the silicone-grafted acrylic polyol in the polyol is preferably 2% by mass or more and 40% by mass or less.

(a) The polyol may contain an acrylic monomer as a structural unit in addition to at least one of (a1) and (a2). For example, acrylic monomers include acrylic acid, methyl acrylate, ethyl acrylate, octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, acrylic sec-butyl acrylate, tert-butyl acrylate, 2,2-dimethylpropyl acrylate, cyclohexyl acrylate, 2-tert-butylphenyl acrylate, 2-naphthyl acrylate, phenyl acrylate, 4-methoxyphenyl acrylate , 2-methoxycarbonylphenyl acrylate, 2-ethoxycarbonylphenyl acrylate, 2-chlorophenyl acrylate, 4-chlorophenyl acrylate, benzyl acrylate, 2-cyanobenzyl acrylate, 4-cyanophenyl acrylate, p acrylate -tolyl, isononyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-cyanoethyl acrylate, 3-oxabutyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate , octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, 2,2-dimethylpropyl methacrylate, Cyclohexyl methacrylate, 2-tert-butylphenyl methacrylate, 2-naphthyl methacrylate, phenyl methacrylate, 4-methoxyphenyl methacrylate, 2-methoxycarbonylphenyl methacrylate, 2-ethoxycarbonylphenyl methacrylate, methacrylic acid 2 -chlorophenyl, 4-chlorophenyl methacrylate, benzyl methacrylate, 2-cyanobenzyl methacrylate, 4-cyanophenyl methacrylate, p-tolyl methacrylate, isononyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate , 2-hydroxybutyl methacrylate, 2-cyanoethyl methacrylate, 3-oxabutyl methacrylate, γ-methacryloyloxypropyltrimethoxysilane, acrylamide, butylacrylamide, N,N-dimethylacrylamide, piperidylacrylamide, methacrylamide, 4-carboxy phenyl methacrylamide, 4-methoxy carboxy Phenyl methacrylamide, methyl chloroacrylate, ethyl-α-chloroacrylate, propyl-α-chloroacrylate, isopropyl-α-chloroacrylate, methyl-α-fluoroacrylate, butyl-α-butoxycarbonyl methacrylate, butyl-α-cyanoacrylate , methyl-α-phenyl acrylate, isobornyl acrylate, isobornyl methacrylate, diethylaminoethyl methacrylate and the like. One or two of these may be copolymerized.

(a1) polyol having an unreactive silicone group in the side chain, the compound represented by the general formula (1) and general formula (2), optionally an acrylic monomer, an azo polymerization initiator It can be produced by radical copolymerization in the presence of. Such polymerization is preferably carried out by a solution polymerization method using a solvent, a bulk polymerization method, an emulsion polymerization method, or the like, and particularly preferably a solution polymerization method.

(b) Isocyanate The isocyanate may be any of various isocyanates that are commonly used in preparing polyurethanes, such as 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′-bitrylene-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), tolidine diisocyanate (TODI), metaphenylene diisocyanate, and the like.
Examples of aliphatic isocyanates include hexamethylene diisocyanate (HDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), orthotoluidine diisocyanate, lysine diisocyanate methyl ester, isophorone diisocyanate (IPDI), norbornane diisocyanate methyl, transcyclohexane. -1,4-diisocyanate, triphenylmethane-4,4',4''-triisocyanate and the like.
Derivatives include polynuclear polyisocyanate, urethane-modified products (including urethane prepolymers) modified with polyols, etc., dimers formed by uretidione formation, isocyanurate-modified products, carbodiimide-modified products, uretonimine-modified products, allohanate-modified products, Modified urea, modified burette and the like can be mentioned. Polyisocyanate can be used alone or in combination of two or more. The polyisocyanate preferably has a molecular weight of 500-2000, more preferably 700-1500.

The (b) isocyanate used in the coating layer resin composition is preferably a polyisocyanate. For example, nurate-type isocyanate, adduct-type isocyanate, and the like can be used. In particular, it is preferable to use blocked isocyanate because the reaction rate can be easily adjusted.
The mixing ratio in the mixture of the polyol and polyisocyanate of (a), (a1) and (a2) is not particularly limited, but usually the hydroxyl group (OH) contained in the polyol and the isocyanate group (NCO ) and the molar ratio (NCO/OH) is preferably 0.7 or more and 1.15 or less. This molar ratio (NCO/OH) is more preferably 0.85 or more and 1.10 or less in terms of preventing hydrolysis of the polyurethane. In practice, it may be blended in an amount equivalent to 3 to 4 times the proper molar ratio, taking into consideration work environment and work errors.

The resin composition for the coating layer contains an auxiliary agent, such as a chain extender, a cross-linking agent, etc., which is usually used for the reaction between the polyols (a), (a1) and (a2) and the isocyanate (b). may Examples of chain extenders and cross-linking agents include glycols, hexanetriol, trimethylolpropane and amines.

(c) Surface roughness material The coating layer 4 contains a surface roughness material. The surface roughness material is particles that adjust the surface roughness of the coating layer 4 . The average particle size of the surface roughening agent 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 even better printing characteristics can be obtained. The average particle size of the surface roughness material can be measured as a median size using a particle size distribution analyzer based on laser light diffraction.

The surface roughness (Rz) of the coating layer 4 is, for example, preferably 1 μm or more and 20 μm or less, more preferably 1 μm or more and 15 μm or less. In this specification, the surface roughness (Rz) of the coating layer 4 indicates ten-point average roughness measured by the method specified in JIS-1994. The surface roughness of the coating layer 4 can be easily adjusted by, for example, the type and amount of the surface roughness material to be blended.

The type of the surface roughening material blended in the coating layer 4 is not particularly limited, and can be appropriately selected from known fillers (fillers) and used. For example, small particle size silica, spherical resin particles, metal oxides and the like may be used.

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

(d) Conductive material Conductive materials include carbon black, graphite, copper, aluminum, nickel, iron powder, conductive agents having an electronic conduction mechanism such as conductive metal oxides, and ions such as alkali metal salts and quaternary ammonium salts. A conductive agent having a conductive mechanism and a conductive agent having conductive composite particles in which conductive particles such as carbon black particles are added to the surfaces of silica particles are preferred.
Carbon black is particularly preferable as the conductive material. Carbon black is not particularly limited, and for example, acetylene black, furnace black, channel black, ketjen black, thermal black and the like are preferably used. As carbon black, one of these may be used alone, or two or more thereof may be used in combination. Two or more of various conductive agents may be used in combination to obtain a desired electrical resistance.

The content of the conductive material in the resin composition for coating layer is preferably 0.5% by mass or more and 20% by mass or less, and 1.0% by mass or more and 15% by mass, based on the total amount of the resin composition for coating layer. It is more preferably 2.0% by mass or more and 10% by mass or less. By adjusting the content of the conductive material within the above range, the resistance value of the developing roller 1 is further stabilized, the printing performance is further improved, the compression set of the elastic layer 3 is reduced, and the developing roller 1 is improved. Better durability.

The coating layer 4 may further contain additives other than those described above. For example, the coating layer 4 may further contain additives such as silane coupling agents, lubricants, polymerization catalysts, dispersants and fillers.

The coating layer 4 is formed by coating the resin composition for the coating layer on the elastic layer 3 and heating or the like to form (a) a polyol, (a1) a polyol having an unreactive silicone group in a side chain, and (a2) one end. It is formed by polymerizing and curing at least one diol-type silicone oil and (b) an isocyanate component. The solvent used for the coating liquid is preferably a solvent capable of dissolving the polyol and isocyanate components, and may be, for example, ethyl acetate, butyl acetate, or the like.

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 immersing the elastic layer 3 and the like in the coating liquid, and a coating liquid applied to the elastic layer. 3, etc., by a known coating method such as a spray coating method. The coating layer resin composition may be applied as it is, or may be coated with alcohols such as methanol and ethanol, aromatic solvents such as xylene and toluene, ethyl acetate and butyl acetate, and the like. A volatile solvent such as an ester solvent or a coating solution containing water may be applied. The method for curing the coating layer resin composition thus coated may be any method in which heat or moisture necessary for curing the coating layer resin composition can be applied. Examples include a method of heating the elastic layer 3 and the like coated with the composition with a heater, and a method of leaving the elastic layer 3 and the like coated with the resin composition for coating layer under high humidity. The heating temperature for heat-curing the coating layer resin composition is, for example, preferably 100° C. or higher and 200° C. or lower, more 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, more preferably 30 minutes or more and 60 minutes or less. Instead of coating, the resin composition for the coating layer is 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, etc., or laminated. A method of curing the laminated coating layer resin composition later can be adopted.

(Other configurations)
The developing roller 1 of the present invention may have an intermediate layer such as an adhesive layer or a primer layer between the shaft 2 and the elastic layer 3 and between the elastic layer 3 and the coating layer 4 . Among these intermediate layers, the adhesive layer and the primer layer provided between the elastic layer 3 and the coating layer 4 are adjusted so that the electrical characteristics of the developing roller 1 can be improved. can be adjusted, whereby the developing performance of the developing roller 1 can be adjusted favorably.

As the primer layer, one that is commonly used as a primer layer for a developing roller can be used. can be maintained.

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

The image forming apparatus 10 is a tandem type color image forming apparatus in which a plurality of image carriers 11B, 11C, 11M and 11Y provided in developing units B, C, M and Y of respective colors are arranged in series on a transfer/conveyor belt 6. , and the developing units B, C, M and Y are arranged in series on the transfer/conveyor belt 6 . The developing unit B includes an image carrier 11B such as a photosensitive member (also referred to as a photosensitive drum), a charging means 12B such as a charging roller, an exposure means 13B, a developing device 20B, and an image carrying belt 6. A transfer means 14B, such as a transfer roller, which contacts the body 11B, and a cleaning means 15B are provided.

The developing device 20B is an example of the developing device of the present invention, and as shown in FIG. 2, includes the developing roller 1 of the present invention and developer 22B. Therefore, in this image forming apparatus 10, the developing roller 1 is mounted as developer carriers 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 for supplying the developer 22B to the image carrier 11B, for example, a developing roller 1, and a developer. It comprises a toner supply roller 25B for supplying the developer 22B to the carrier 23B, and a developer amount adjusting means 24B for example a blade for adjusting the thickness of the developer 22B. In the developing device 20B, as shown in FIG. 2, the developer amount adjusting means 24B is in contact or pressure contact with the outer peripheral surface of the developer carrier 23B. That is, the developing device 20B is a "contact developing device". Developing units C, M and Y are basically configured in the same manner as developing unit B, and the same elements are denoted by the same reference numerals and symbols C, M or Y indicating each unit, and description thereof is omitted. .

In the image forming apparatus 10, the developer carrier 23B of the developing device 20B is arranged so that its surface contacts or presses against the surface of the image carrier 11B. Similarly to the developing device 20B, the developing devices 20C, 20M and 20Y are arranged such that the surfaces of the developer carriers 23C, 23M and 23Y contact or press against the surfaces of the image carriers 11C, 11M and 11Y. . That is, the image forming apparatus 10 is a "contact image forming apparatus".

The fixing means 30 is arranged downstream of the developing unit Y. As shown in FIG. The fixing means 30 includes a fixing roller 31, an endless belt support roller 33 arranged near the fixing roller 31, the fixing roller 31 and the endless belt, in a housing 34 having an opening 35 for passing the recording medium 16. An endless belt 36 wound around a support roller 33 and a pressure roller 32 arranged opposite to the fixing roller 31 are provided. It is a pressure heat fixing device that is rotatably supported so as to do so. At the bottom of the image forming apparatus 10, a cassette 41 that accommodates the recording medium 16 is installed. The transfer/conveyor belt 6 is wound around a plurality of support rollers 42 .

The developers 22B, 22C, 22M, and 22Y used in the image forming apparatus 10 may be either dry developers or wet developers, and may be non-magnetic or magnetic developers, as long as they are frictionally charged developers. drug may be used. In housings 21B, 21C, 21M and 21Y of respective 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 contained. are housed.

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

The developing device 20B is provided with the developing roller 1, is excellent in developer transportability, suppresses the occurrence of toner filming, and contributes to long-term formation of high-density, high-quality images. Further, the image forming apparatus 10 can form high-density, high-quality images over a long period of time.

The developing device and image forming apparatus of the present invention are not limited to those described above, and various modifications are possible as long as 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 an electrophotographic image forming apparatus, 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 bearing members each having a developing unit of each color are arranged in series on a transfer/transport belt. , a monochrome image forming apparatus having a single developing unit, and a four-cycle color image forming apparatus in which developer images carried on an image carrier are sequentially and repeatedly transferred to an endless belt. 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. , or a two-component magnetic developer.

The image forming apparatus is a contact type image forming apparatus arranged in contact or 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 image forming apparatus arranged with a gap so that the surface of the developer bearing member does not come into contact with the surface of the image bearing member.

Although the present invention has been described using the embodiments, 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 embodiments. It will be clear to those skilled in the art that improvements are possible. In addition, it is clear from the description of the scope of claims that inventions with such modifications or improvements can also be included in the technical scope of the present invention.

Hereinafter, the present invention will be described in detail with reference to examples. It should be noted that the present invention is by no means limited to the examples shown below.

[Example 1]
(Formation of primer layer)
A shaft (made of SUM22, diameter 10 mm, length 275 mm) subjected to electroless nickel plating was washed with ethanol, and a silicone-based primer (trade name “Primer No. 16” manufactured by Shin-Etsu Chemical Co., Ltd. was applied to its surface. ) was applied. The primer-treated shaft 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 more to form a primer layer on the outer peripheral surface of the shaft.

(Formation of elastic layer)
Next, 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 hydrophobized fumed silica having a BET specific surface area of 110 m ² /g (trade name “R-972 ", manufactured by Nippon Aerosil Co., Ltd.) 1 part by mass, diatomaceous earth having an average particle diameter of 6 μm and a bulk density of 0.25 g / cm ³ (trade name "Oplite W-3005S", manufactured by Chuo Silica Co., Ltd.) 40 parts by mass, and , and 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 three rolls 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 content: 0.0060 mol/g), ethynylcyclohexanol 0.1 part by mass and 0.1 part by mass of a platinum catalyst (Pt concentration of 1%) were added, and the mixture was stirred, defoamed and kneaded 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 form an elastic body made of a rubber material on the outer peripheral surface of the shaft. In injection molding, the addition-curable liquid conductive silicone rubber composition was cured by heating at 120° C. for 10 minutes, followed by secondary vulcanization at 200° C. for 4 hours to form an elastic layer with an outer diameter of 16 mm.

(Formation of coating layer)
Next, a resin composition for forming a coating layer was prepared as follows.

-Resin composition for coating layer-
(a) Polycarbonate diol (trade name “Nipporan 981”, manufactured by Tosoh Corporation)
95.4 parts by mass (a1) Silicone-grafted acrylic polyol 4.6 parts by mass (b) Nurate-type isocyanate (trade name “TPA-B80E”, manufactured by Asahi Kasei Corporation)
49.6 parts by mass (c) Surface roughness material (AEROSIL (registered trademark) R 711, manufactured by Nippon Aerosil Co., Ltd.) 13.5 parts by mass (d) Conductive material (MA600, manufactured by Mitsubishi Chemical Corporation) 3 parts by mass

<(a1) Synthesis of silicone-grafted acrylic polyol>
(a1) Silicone-grafted acrylic polyol was produced by radically polymerizing the compounds represented by the general formulas (1) and (2) in the presence of azobisisobutyronitrile (AIBN).

This coating layer resin composition 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 20 μm. Thus, a developing roller having a shaft, an elastic layer and a coating layer was manufactured.

[Examples 2 to 7, Comparative Examples 1 to 3]
Using the materials and formulations shown in Table 1, a developing roller was manufactured in the same manner as in Example 1.
In Table 1, (a) polyester-based polyol uses POLYCATOR #10 manufactured by Ito Oil Co., Ltd., and (a2) one-end diol-type silicone oil uses Shin-Etsu Chemical Co., Ltd. X-22-176DX. , Asahi Kasei Co., Ltd. Duranate E402-B80B was used as the adduct type isocyanate.

[evaluation]
An image forming apparatus HL-3170CDW (model number, manufactured by Brother Industries, 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 dynamic friction coefficient, static friction coefficient and banding by the following methods.

(Dynamic friction coefficient and static friction coefficient)
Using i-tester TL701 (R contactor) manufactured by Trinity Lab Co., Ltd., the produced developing roller was measured multiple times in the longitudinal direction of the roller with a load of 300 N according to the measurement method, and the arithmetic average value was obtained for each test sheet. It was determined as the static friction coefficient and the dynamic friction coefficient.

(Banding evaluation)
Each of the produced conductive rollers was mounted as a developing roller in a contact type image forming apparatus HL-3170CDW (model number, manufactured by Brother Industries, Ltd.) and allowed to stand for 24 hours under a normal temperature and normal humidity environment of 23° C. and 50%. After that, a halftone image was printed on A4 paper (JIS) while maintaining this normal temperature and humidity environment. In the printed halftone image, "C" was given when the banding was the same as that of the conventional product, and "A" was given when a sufficient improvement was observed.
A high-density portion extending in the short side direction of the A4 paper in the image area is banding. In the banding evaluation, the developer and the developer amount adjusting means attached to this image forming apparatus were used as the developer and the developer amount adjusting means.

Table 1 shows the evaluation results.

As shown in Table 1, in examples containing (a1) a polyol having an unreactive silicone group in a side chain or (a2) a one-end diol-type silicone oil as a raw material for the coating layer resin composition, the dynamic friction coefficient and the coefficient of static friction are lower than those of the comparative examples, indicating that the banding is improved.
This is because the silicone chain in (a1) is an unreacted group and (a2) is a one-end silicone chain, so the silicone chain is not incorporated as the main chain of the polyurethane, and the degree of freedom is relatively high. Presumably, the presence of side chains on the surface of the coating layer reduced the coefficient of friction.

Reference Signs List 1 developing roller 2 shaft 3 elastic layer 4 coating layer 6 transfer conveying 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 20B, 20C, 20M, 20Y Developing device 21B, 21C, 21M, 21Y, 34 Housing 22B, 22C, 22M, 22Y Developer 23B, 23C, 23M, 23Y developer carrier (developing roller)
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

Claims (6)

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 is formed by thermosetting a coating layer resin composition containing (a) a polyol, (b) an isocyanate, (c) a surface roughness agent, and (d) a conductive material,
The (a) polyol contains a polycarbonate diol, (a1) a silicone-grafted acrylic polyol, and (a2) at least one of a one-end diol-type silicone oil,
The (c) surface roughness material is small particle size silica having an average particle size of 1 μm or more and 15 μm or less,
The content of the surface roughness material (c) is 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the resin composition for a coating layer. 2. The content of at least one of the (a1) silicone-grafted acrylic polyol and the (a2) one-end diol-type silicone oil in the (a) polyol is 2% by mass or more and 600% by mass or less. Developing roller as described. 3. The developing roller according to claim 1, wherein the (a1) silicone-grafted acrylic polyol alone is included in the (a1) silicone-grafted acrylic polyol and the (a2) one-end diol-type silicone oil. 4. The developing roller according to claim 3, wherein the content of said (a1) silicone-grafted acrylic polyol in said (a) polyol is 2% by mass or more and 40% by mass or less. A developing device comprising the developing roller according to any one of claims 1 to 4. An image forming apparatus comprising the developing roller according to any one of claims 1 to 4.

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