JP7010537B2 - Developing rollers, developing equipment and image forming equipment - Google Patents

Description

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

A developing roller used in an image forming apparatus such as a copying machine, a printer, or a facsimile that employs an electrophotographic method has a function of transporting a developing agent 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, particularly the print density. Therefore, it has been studied to form irregularities on the surface of the developing roller and to adjust the electrical characteristics of various materials constituting the developing roller to improve the developer transportability of the developing roller.

Here, when the developing roller is used for a long period of time, the developing agent may adhere to the surface thereof (referred to as "filming"). In such filming, for example, 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 the developer is charged or adhered, and further, the developing is performed by the frictional heat with the blade or the like. It is believed that this is caused by the melting of the agent. In the developing roller, there is a demand for a developing roller in which the occurrence of filming is suppressed as much as possible and the durable printing performance is stabilized.

With the recent improvement in image quality of image forming apparatus, various studies have been made on the configuration of a developing roller and particles contained in the surface layer as another approach for improving image quality. For example, Patent Document 1 discloses a developing roller in which a surface layer contains urethane resin particles whose surface is partially coated with inorganic fine particles.

On the other hand, resin particles used for various purposes have been developed. For example, in Patent Document 2, crosslinked (meth) acrylic acid ester resin particles used for coating films and cosmetics on the surface of automobile interior parts are described. It has been disclosed.

Japanese Patent No. 4455671 International Publication No. 2016/039357

However, the developing rollers and resin particles described in Patent Documents 1 and 2 cannot suppress the occurrence of filming to the extent that they can sufficiently correspond to the performance of the image forming apparatus required in recent years, and are not satisfactory in terms of durable printing performance. There wasn't.
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 device, in which the occurrence of filming is satisfactorily suppressed and the durable printing performance is excellent.

As a result of diligent studies, the present inventors have found that the occurrence of filming is satisfactorily suppressed by dispersing specific particles in the coating layer of a developing roller, and have completed the present invention.

That is, the present invention is a developing roller having a shaft body, an elastic layer provided on the outer periphery of the shaft body, and a coating layer provided on the outer periphery of the elastic layer, and the coating layer is a urethane resin as a binder. A development roller containing a conductivity-imparting agent dispersed in a binder, and crosslinked (meth) acrylic acid ester resin particles and inorganic fine particles dispersed in the binder to form irregularities on the surface of the coating layer.
Here, (meth) acrylic acid ester means a generic term including both acrylic acid ester and methacrylic acid EL.

The crosslinked (meth) acrylic acid ester resin particles preferably have a restoration rate of 20% or more and a compressive strength of 10% of 0.1 MPa or more and 2.2 MPa or less.

The inorganic fine particles are preferably silica fine particles, and the average particle size of the silica fine particles is preferably 10 nm or more and 5 μm or less.

The average particle size of the crosslinked (meth) acrylic acid ester resin particles is preferably 1 μm or more and 15 μm or less.

The sliding angle of the surface is preferably 10 ° or more and 40 ° or less.

The conductivity-imparting agent is preferably at least one selected from a conductive agent having an electronic conduction mechanism, a conductive agent having an ionic conduction mechanism, and conductive composite particles.

The developing apparatus 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, the coating layer is a urethane resin as a binder, a conductivity-imparting agent dispersed in the binder, and a crosslinked (meth) acrylic acid dispersed in the binder to form irregularities on the surface of the coating layer. By containing the ester resin particles and the inorganic fine particles, when filming occurs in the developing roller in an amount that does not cause a problem in image quality, it is pressed by the developing agent amount adjusting means and the toner supply roller to facilitate the adhered substance. Therefore, it is possible to obtain a developing roller, a developing device, and an image forming device which are excellent in durable printing performance by satisfactorily suppressing the occurrence of filming before the amount of charge of the developing roller becomes uneven.

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

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

<Developer roller>
As shown in FIG. 1, the developing roller 1 of the present invention has a shaft body 2, an elastic layer 3 provided on the outer periphery of the shaft body 2, and a coating layer 4 provided on the outer periphery of the elastic layer 3. The coating layer 4 is formed of a urethane resin as a binder, a conductive substance dispersed in the binder, and crosslinked (meth) acrylic acid ester resin particles dispersed in the binder to form irregularities on the surface of the coating layer 4. And inorganic fine particles.
Hereinafter, the details of the configuration of the developing roller 1 of the present invention will be described.

[Axis body]
As the shaft body 2, preferably, a shaft body having conductivity and used for 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, for example, iron, aluminum, stainless steel, and brass. The shaft body 2 made of such a metal is also generally known by the name of "core metal".

The shaft body 2 may contain 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 shape of the shaft body 2 is preferably, for example, a rod shape, a tubular shape, or the like. The cross-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 polygon. The outer peripheral surface of the shaft body 2 may be subjected to a treatment such as a cleaning treatment, a degreasing treatment, and a primer treatment in order to improve the adhesiveness with 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 printing target is A4 size, the length of the shaft body 2 in the axial direction is preferably 250 mm or more and 320 mm or less, and more preferably 260 mm or more and 310 mm or less. Further, the diameter of the shaft body 2 (diameter of the circumscribed 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 circumscribed 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 a rubber, a conductivity-imparting agent, and, if desired, various additives.

(Rubber composition)
-Rubber-
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, and chloroprene. Examples thereof include rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, and fluororubber. Silicone or silicone-modified rubber or urethane rubber is preferable, and silicone or silicone-modified rubber can reduce compression set, is excellent in flexibility in a low temperature environment, and has heat resistance and charging characteristics. It is particularly preferable in that it is excellent in such things as. Examples of the silicone rubber include crosslinked products of organopolysiloxane such as dimethylpolysiloxane and diphenylpolysiloxane.

-Conductivity imparting agent-
As the conductivity-imparting agent, a conductive agent having an electronic conduction mechanism such as carbon black, graphite, copper, aluminum, nickel, iron powder, and a conductive metal oxide, and an ion conduction mechanism such as an alkali metal salt and a quaternary ammonium salt are used. A conductive agent having a conductive agent and a conductive agent having conductive composite particles in which conductive particles such as carbon black particles are imparted to the surface of the silica particles are preferable.
Carbon black is particularly preferable as the conductivity-imparting agent. The 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 the carbon black, one of these may be used alone, or two or more thereof may be used in combination. In order to obtain the desired electrical resistance, two or more kinds of various conductive agents may be used in combination.

The content of the conductivity-imparting agent in the rubber composition 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 or less, based on the total amount of the rubber composition. Is more preferable, and more preferably 2.0% by mass or more and 10% by mass or less. By adjusting the content of the conductivity-imparting agent 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 is reduced. The durability of 1 is further improved.

-Various additives-
The rubber composition may further contain various additives other than the above. Examples of various additives include auxiliaries (chain extenders, cross-linking agents, etc.), catalysts, dispersants, foaming agents, antioxidants, antioxidants, fillers, pigments, colorants, processing aids, and softeners. , Plasticizers, emulsifiers, heat resistance improvers, flame retardant improvers, acid receiving agents, thermal conductivity improvers, mold release agents, solvents and the like.

Examples of the silicone rubber composition include an addition-curable mirrorable conductive silicone rubber composition and an addition-curable liquid conductive silicone rubber composition.

The addition-curable mirabable 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. It's okay.
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. Further, R ¹ indicates a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. The number of carbon atoms of the hydrocarbon group is preferably 1 or more and 12 or less, and more preferably 1 or more and 8 or less.

Examples of R ¹ include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group and a dodecyl group, a cycloalkyl group such as a cyclohexyl group, a vinyl group, an allyl group, a butenyl group and a hexenyl group. Examples thereof include an aryl group such as an alkenyl group, a phenyl group and a trill group, and an aralkyl group such as a β-phenylpropyl group. Further, R ¹ may be a group in which a part 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.

(A) The organopolysiloxane 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, or a trivinylsilyl group. It is preferably sealed with a trialal kill silyl group or the like.

(A) The organopolysiloxane preferably has two or more alkenyl groups in the molecule. (A) The organopolysiloxane preferably has an alkenyl group of 0.001 mol% or more and 5 mol% or less (more preferably 0.01 mol% or more and 0.5 mol% or less) of ^R1 . (A) The vinyl group is particularly preferable as the alkenyl group contained in the organopolysiloxane.

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

The kinematic viscosity of (A) organopolysiloxane at 25 ° C. is preferably 100 cSt or more, and more preferably 100,000 cSt or more and 10,000,000 cSt or less. Further, the degree of polymerization of (A) organopolysiloxane is preferably, for example, 100 or more, and more preferably 3000 or more and 10000 or less.

Examples of the filler (B) include silica-based fillers. Examples of the silica-based filler include fumes silica, precipitated silica and the like.

As the silica-based filler, a surface-treated silica-based filler surface-treated with the 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 methacrylate 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 can be easily obtained, 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 conventional method. As the surface-treated silica-based filler, a commercially available product may be used, for example, J.A. M. Examples thereof include the product name "Zeothix 95" manufactured by HUBER Co., Ltd.

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 (A) organopolysiloxane. The average particle size of the silica-based filler is preferably 1 μm or more and 80 μm or less, and more preferably 2 μm or more and 40 μm or less. The average particle size of the silica-based filler can be measured as the median diameter using a particle size distribution measuring device by a laser light diffraction method.

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

The addition-curable mirabable conductive silicone rubber composition may further contain additives other than (A) to (C). Examples of additives include auxiliaries (chain extenders, cross-linking agents, etc.), catalysts, dispersants, foaming agents, antioxidants, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, etc. Examples thereof include emulsifiers, heat resistance improvers, flame retardancy improvers, acid receiving agents, heat conductivity improvers, mold release agents, solvents and the like.

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

The addition-curable liquid conductive silicone rubber composition has, 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. It may contain (F) a filler, (G) a conductivity-imparting agent, and (H) an addition reaction catalyst.

As the (D) organopolysiloxane, the compound represented by the following average composition formula (2) is suitable.
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. Further, ^R4 indicates a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. However, at least two of ^R4 in one molecule are alkenyl groups. The number of carbon atoms of the hydrocarbon group is preferably 1 or more and 12 or less, and more preferably 1 or more and 8 or less.

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

(D) The 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, and more preferably 200 mPa · s or more and 100,000 mPa · s or less. preferable. Further, the average degree of polymerization of (D) organopolysiloxane is preferably 100 or more and 800 or less, and more preferably 150 or more and 600 or less.

As the (E) organohydrogenpolysiloxane, the compound represented by the following average composition formula (3) is suitable.
R ⁵ _b H _c SiO _{(4-bc) / 2} ... (3)
In formula (3), b indicates a positive number of 0.7 or more and 2.1 or less, c indicates a positive number of 0.001 or more and 1.0 or less, and bc indicates 0.8 or more and 3.0 or less. Is. Further, R5 indicates a substituted or unsubstituted monovalent hydrocarbon group which may be the ^same or different. The number of carbon atoms of the hydrocarbon group is preferably 1 or more and 10 or less. As R ⁵ , the same group as that exemplified as R ¹ can be exemplified.

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

(E) In the organohydrogenpolysiloxane, the content of the hydrogen atom bonded to the silicon atom 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 or less. It is more preferably g or less.

Examples of the organohydrogenpolysiloxane (E) include a double-ended trimethylsiloxy group-blocked methylhydrogenpolysiloxane, a double-ended trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, and a double-ended dimethylhydrogensiloxy group-blocked. 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 unit and SiO _4/2 unit, and (CH ₃ ) ₂ HSiO _1/2 unit and SiO _4/2 . Examples thereof include a copolymer composed of a unit and (C ₆ H ₅ ) SiO _3/2 unit.

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

(F) The filler may be, for example, an inorganic filler. By blending the filler (F) with the addition-curable liquid conductive silicone rubber composition, the compression set is reduced, the volume resistivity is stable 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, and 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 with time is further suppressed. Further, when the average particle size of the (F) filler is 30 μm or less, the elastic layer 3 having further excellent durability can be obtained. The average particle size of the filler (F) can be measured as a median diameter using a particle size distribution measuring device by a laser light 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, and 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 lowered, the change in volume resistivity with time is 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 (F) filler include diatomaceous earth, pearlite, mica, calcium carbonate, glass flakes, hollow filler and the like. Among these, diatomaceous earth, pearlite, and pulverized foamed pearlite can be preferably used as the (F) filler.

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

The blending amount of the (G) conductivity-imparting agent is preferably 0.5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of (D) organopolysiloxane, and is preferably 1 part by mass or more and 10 parts by mass or less. It is more preferable to have.

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

(H) The blending amount of the addition reaction catalyst may be the catalyst amount. For example, the amount of the (H) addition reaction catalyst compounded is such that the amount of platinum group elements 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). Additives include, for example, auxiliaries (chain extenders, cross-linking agents, etc.), foaming agents, dispersants, antioxidants, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, etc. Examples thereof include heat resistance improvers, flame retardant improvers, acid receiving agents, heat conductivity improvers, mold release agents, diluents, reactive diluents, solvents 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 and the like for improving adhesiveness, molding processability and the like may be used. Further, a halogen compound or the like that imparts flame retardancy may 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, and more preferably 5 Pa · s or more and 200 Pa · s or less.

The elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 by simultaneously or continuously performing heat curing and molding by a known molding method. The method for curing the rubber composition may be any method as long as the heat required for curing the rubber composition can be applied, and the method for forming the elastic layer 3 is particularly limited to continuous vulcanization by extrusion molding, pressing, mold molding by injection, and the like. It is not something that will be done. For example, when the rubber composition is an addition-curable mirable conductive silicone rubber composition, for example, 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 at which the rubber composition is cured is 100 ° C. or higher and 500 ° C. or lower, particularly 120 ° C. or higher and 300 ° C. or lower, and the time is several seconds or longer and 1 hour or shorter, particularly in the case of the addition-curable mirable conductive silicone rubber composition. It is preferably 10 seconds or more and 35 minutes or less, and in the case of an addition-curable liquid conductive silicone rubber composition, 100 ° C. or more and 300 ° C. or less, particularly 110 ° C. or more and 200 ° C. or less, and the time is 5 minutes or more and 5 hours or less. In particular, it is preferably 1 hour or more and 3 hours or less. Further, if necessary, secondary vulcanization may be carried out. In the case of the addition-curing type mirabable conductive silicone rubber composition, for example, curing conditions of about 1 hour or more and 20 hours or less at 100 ° C. or higher and 200 ° C. or lower are selected. Further, in the case of the addition-curing type liquid conductive silicone rubber composition, for example, curing conditions of about 2 hours or more and 70 hours or less at 120 ° C. or higher and 250 ° C. or lower are selected. Further, the rubber composition can be easily foamed and cured by a known method to easily form a sponge-like elastic layer having bubbles.

The thickness of the elastic layer 3 is not particularly limited, and is preferably 0.1 mm or more and 6 mm or less, and more preferably 1 mm or more and 4 mm or less. The thickness in the present specification indicates the thickness in the direction perpendicular to the axis 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, and more preferably 7 mm or more and 21 mm or less.

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 frame treatment for the purpose of improving the adhesiveness with the coating layer 4. It's okay.

The method of 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 or LIMS molding of the silicone rubber composition. Further, 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.

[Coating layer]
The coating layer 4 is the outer periphery of the elastic layer and is provided on the outermost surface of the developing roller 1. The coating layer 4 is formed by applying a resin composition to the elastic layer 3 or the outer peripheral surface of a primer layer formed if desired, and then heat-curing the coated resin composition. The resin composition contains at least a urethane adjusting component for forming a urethane resin as a binder, a crosslinked (meth) acrylic acid ester, and inorganic fine particles. It is not always necessary to heat-cure the resin composition to form the coating layer 4, but it is formed by a silicone coating treatment using ethyl silicate and a treatment in which titanium-based, aluminum-based, zirconium-based materials, etc. are included in the treatment agent. It may be a layer.

The coating of the resin composition is, for example, a coating method of applying the coating liquid of the resin composition, a dipping method of immersing the elastic layer 3 or the like in the coating liquid, or a spray coating of spraying the coating liquid on the elastic layer 3 or the like. It is performed by a known coating method such as a method. The resin composition may be applied as it is, or the resin composition may be coated with, for example, an alcohol such as methanol and ethanol, an aromatic solvent such as xylene and toluene, and an ester solvent such as ethyl acetate and butyl acetate. A volatile solvent or a coating liquid containing water may be applied. The method for curing the resin composition coated in this manner may be any method as long as it is a method in which heat or moisture necessary for curing the resin composition or the like can be applied. For example, the elastic layer coated with the resin composition. Examples thereof include a method of heating the third and the like with a heater, a method of allowing the elastic layer 3 and the like coated with the resin composition to stand under high humidity, and the like. The heating temperature for heat-curing the 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 and 120 minutes or lower. It is preferably 30 minutes or more and 60 minutes or less. Instead of coating, the resin composition 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, or after laminating. A method of curing the resulting resin composition or the like can be adopted.

In the coating layer 4 thus formed, the precursor forming the resin and the conductivity-imparting agent described later may react to be integrated or form a composite, and the conductivity-imparting agent may be formed. The agent may not react with the precursor forming the resin and may be dispersed in the resin.

(Sliding angle)
The sliding angle of the surface of the developing roller of the present invention is preferably 10 ° or more and 40 ° or less. The surface of the developing roller means the surface of the coating layer 4, that is, the surface of the coating layer 4.
Here, in the present specification, the "sliding angle" means that first, a base on which a PET (polyethylene terephthalate) film is laid is horizontally arranged (an angle with a horizontal plane is 0 °), and the vertical direction of the base is used. Place the developing roller on the base so that it is parallel to the axis direction of the developing roller. Next, with one end of the base fixed in the longitudinal direction, the other end is raised to gradually incline the base, and the base when the developing roller starts to slide toward one end. Means the angle formed with the horizontal plane.

When the sliding angle of the surface of the developing roller is 10 ° or more, the developing roller can satisfactorily carry the developer and convey it to the photoconductor. Further, when the temperature is 40 ° or less, the developer is easily desorbed after adhering to the developing roller, so that a predetermined amount of the developer can be supplied according to the image data. That is, by setting the sliding angle to 10 ° or more and 40 ° or less, the developer can be appropriately supported and conveyed, and a high-quality image can be maintained.

The slip angle can be appropriately adjusted depending on the type, average particle size or content of the crosslinked (meth) acrylic acid ester resin particles described later, or the type, average particle size or content of the inorganic fine particles.

(Thickness)
The thickness of the coating layer 4 is substantially the same as the average particle size of the crosslinked (meth) acrylic acid ester resin particles described later, and specifically, is 1 μm or more and 15 μm or less. By adjusting the thickness of the coating layer 4 within the above range, it is possible to improve the durable printing performance while satisfactorily suppressing filming.

Hereinafter, the components contained in the coating layer 4 will be described.
(Urethane resin)
The coating layer 4 has a urethane resin as a binder. The urethane preparation component, which is a precursor for forming the urethane resin, may be any material as long as it can form the urethane resin, and examples thereof include a mixture of a polyol and an isocyanate.

The polyol may be any of various polyols usually used in the preparation of polyurethane, and is preferably at least one polyol selected from a polyether polyol, a polyester polyol, a polyacrylate polyol, and a polycarbonate polyol.

The polyether polyols include, for example, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polypropylene glycol-ethylene glycol, polytetramethylene ether glycols, copolymerized polyols of tetrahydrofuran and alkylene oxide, and various modified products thereof or their respective. Examples include mixtures.

Polyester polyols have 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 are hydroxyl group-containing monomers and other olefinically unsaturated monomers such as (meth) acrylic acid esters, styrene, α-methylstyrene, vinyltoluene, vinyl esters, maleic acid monoalkyl esters and maleic acid dialkyl esters. , And copolymers with fumaric acid monoalkyl esters and fumaric acid dialkyl esters, α-olefins and other unsaturated oligomers and unsaturated polymers.

Polycarbonate polyols have 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 the polyol and the carbonate compound. Moreover, as a carbonate compound, for example, a dialkyl carbonate, a diallyl carbonate, an alkylene carbonate and the like can be mentioned. 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-butanediol.

The isocyanate may be any of various isocyanates usually used for the preparation of polyurethane, and examples thereof include aliphatic isocyanates, aromatic isocyanates and derivatives thereof. The isocyanate is preferably an aliphatic isocyanate because it has excellent storage stability and the reaction rate can be easily controlled. Examples of the aromatic isocyanate 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-toluene diisocyanate uretidinedione (2,4-TDI diisocyanate), xylene diisocyanate, naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PDI) , Trizine diisocyanate (TODI), metaphenylenedi isocyanate and the like. Examples of the aliphatic isocyanate include hexamethylene diisocyanate (HDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), orthotoluidine diisocyanate, lysine diisocyanate methyl ester, isophorone diisocyanate (IPDI), norbornane diisocyanate methyl, and transcyclohexane. -1,4-Diisocyanate, triphenylmethane-4,4', 4''-triisocyanate and the like can be mentioned. Derivatives include polyisocyanate polynuclears, urethane modified products (including urethane prepolymers) modified with polyols, dimers by uretidine formation, isocyanurate modified products, carbodiimide modified products, uretonimine modified products, alohanate modified products, etc. Examples include urea modified products and bullet modified products. As the polyisocyanate, one type alone or two or more types can be used. The polyisocyanate preferably has a molecular weight of 500 to 2000, and more preferably 700 to 1500.

The mixing ratio of 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 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 that hydrolysis of polyurethane can be prevented. Actually, in consideration of the work environment and work error, an amount equivalent to 3 to 4 times the appropriate molar ratio may be blended.

In addition to the polyol and the polyisocyanate, the urethane preparation component may be used in combination with an auxiliary agent usually used for the reaction between the polyol and the polyisocyanate, for example, a chain extender, a cross-linking agent, or the like. Examples of the chain extender and the cross-linking agent include glycols, hexanetriol, trimethylolpropane and amines.

(Crosslinked (meth) acrylic acid ester resin particles)
The coating layer 4 contains crosslinked (meth) acrylic acid ester resin particles. The crosslinked (meth) acrylic acid ester is for forming irregularities on the surface of the coating layer. The cross-linked (meth) acrylic acid ester is a resin particle formed by cross-linking the (meth) acrylic acid ester.
Examples of the acrylic acid ester include methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, butyl methacrylate, hexyl methacrylate, urethane (meth) acrylic acid ester and the like.

It is particularly preferable that the crosslinked (meth) acrylic acid ester resin particles have a restoration rate of 20% or more and a compressive strength of 10% of 0.1 MPa or more and 2.2 MPa or less. From this point of view, urethane (meth) acrylic acid ester is particularly preferable among the acrylic acid esters. When the crosslinked (meth) acrylic acid ester resin particles have a restoration rate of 20% or more and a compressive strength of 10% of 0.1 MPa or more and 2.2 MPa or less, the following effects are particularly exhibited.
The developing roller 1 is in contact with the developer amount adjusting means and the photoconductor in a pressed state, but after use, if the developing roller 1 is left in the pressed state for a long period of time, the developer amount adjusting means and the photoconductor 1 are used. The coating layer 4 at the pressed portion may be crushed and deformed. In the developing roller 1 in which the coating layer 4 is partially crushed, uneven density of the image may occur at a position corresponding to the crushing of the coating layer 4.
However, according to the present invention, the coating layer 4 contains crosslinked (meth) acrylic acid ester resin particles having a restoration rate of 20% or more and a compressive strength of 10% of 0.1 MPa or more and 2.2 MPa or less. Therefore, even after being left for a long time, the crushed portion is recovered by a plurality of rotations when the image is restarted, so that the image quality can be maintained.

Here, the "restoration rate (%)" in the present invention is measured by measuring the amount of displacement (displacement of particle size) when the load is reduced to 0.98 mN after applying a load of 9.8 mN. It means a value obtained by the following formula 1 from the displacement amount of the measured particle size and the particle size of the spherical particles before the load is applied.
Restoration rate (%) = [Displacement amount of particle diameter (μm) / Particle diameter (μm)] × 100 ... Formula 1
(Measurement condition of restoration rate)
-Test temperature: 50% RH at 23 ° C
・ Upper pressurizing indenter: Diamond flat indenter with a diameter of 50 μm ・ Lower pressurizing plate: SKS flat plate ・ Measurement mode: Unloading test ・ Load speed: 0.98 mN / sec ・ Maximum load: 9.8 mN

Further, the "10% compressive strength" in the present invention means a value measured by the following method. The values are measured under the following measurement conditions using a microcompression tester MCT manufactured by Shimadzu Corporation. When a test force is applied to one spherical particle at a load speed of 0.98 mN / sec, the test force when the displacement reaches 10% of the particle diameter is defined as the compressive strength (MPa).
(Measurement conditions for compressive strength)
-Test temperature: 50% RH at 23 ° C
・ Upper pressurizing indenter: Diamond flat indenter with a diameter of 50 μm ・ Lower pressurizing plate: SKS flat plate ・ Measurement mode: Compression test ・ Load speed: 0.98 mN / sec ・ Maximum load: Until 10% of particle diameter is reached

As a commercial product of crosslinked (meth) acrylic acid ester resin particles having a restoration rate of 20% or more and a compressive strength of 0.1 MPa or more and 2.2 MPa or less, for example, techpolymer AFX-8 (Sekisui Plastics) (Manufactured by Kogyo Co., Ltd.) and the like.

The average particle size of the crosslinked (meth) acrylic acid ester resin particles is not particularly limited, but if it is excessively large compared to the thickness of the coating layer 4, the surface unevenness of the coating layer 4 becomes rough and the toner particles are surfaced. It tends to remain in the recess. On the other hand, if the average particle size becomes excessively small, convex portions are not formed on the coating layer 4, and the charging performance of the coating layer 4 may become unstable. Therefore, from the viewpoint of stabilizing the charging performance of the developing roller and suppressing the residual of toner particles in the coating layer 4, the average particle diameter of the crosslinked (meth) acrylic acid ester resin particles is equivalent to the thickness of the coating layer 4. Is preferable. Specifically, the average particle size of the crosslinked (meth) acrylic acid ester resin particles is preferably 1 μm or more and 15 μm or less. More preferably, it is 2 μm or more and 10 μm or less.

Average particle size of crosslinked (meth) acrylic acid ester resin particles The average particle size shall be the value obtained by the following method for measuring the volume average diameter.
[Measuring method of volume average diameter of resin particles]
The volume average diameter of the resin particles (arithmetic mean diameter based on the volume-based particle size distribution) is measured by the following method using the Coulter Multisizer II (Measuring device manufactured by Beckman Coulter). In this measurement, calibration is performed using a 50 μm aperture according to Reference MANUAL FOR THE COOLTER MULTISIZER (1987) issued by Council Electricals Limited, and the measurement is performed.
Specifically, 0.1 g of resin particles are placed in 10 ml of 0.1 wt% nonionic surfactant in a touch mixer (“TOUCHMIXER MT-31” manufactured by Yamato Scientific Co., Ltd.) and an ultrasonic cleaner (“TOUCHMIXER MT-31” manufactured by Vervocouria). Pre-disperse using ULTRASONIC CLEANER VS-150]) to obtain a dispersion. Next, in a beaker filled with ISOTON® II (Beckman Coulter's measurement electrolyte) provided in the main body of the Coulter Multisizer II. The dispersion liquid is gently stirred and dropped with a spoid to adjust the reading of the densitometer on the screen of the Coulter Multisizer II main body to around 10%. Next, the aperture size (diameter) is added to the Coulter Multisizer II main body. Is 50 μm, Current (aperture electrode) is 800 μA, Gain (gain) is 4, and Polarity (polarity of internal electrode) is +, and measurement is performed in manual (manual mode). Bubbles are generated in the beaker during measurement. Stir gently so that it does not enter, and the measurement is completed when the measurement of 100,000 resin particles is completed. The arithmetic average diameter in the volume-based particle size distribution of 100,000 resin particles is defined as the volume average diameter. ..

The content of the crosslinked (meth) acrylic acid ester resin particles is not particularly limited, and the larger the content, the more the plastic deformation of the coating layer 4 can be suppressed. However, when the content is high, the density of the crosslinked acrylic resin particles distributed in the coating layer 4 becomes high, and the surface unevenness of the coating layer 4 may become rough. In this case, the toner particles tend to remain on the surface of the coating layer 4, and the charging performance of the developing roller deteriorates. Therefore, from the viewpoint of suppressing the plastic deformation of the coating layer 4 and making the surface roughness appropriate so that the toner particles do not remain, the content of the crosslinked (meth) acrylic acid ester resin particles is 100 parts by mass of the urethane adjusting component. On the other hand, it is preferably 5 parts by mass or more and 50 parts by mass or less. More preferably, it is 8 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the urethane adjusting component.

(Inorganic fine particles)
The coating layer 4 of the developing roller 1 of the present invention contains inorganic fine particles. The inorganic fine particles are for forming irregularities on the surface of the coating layer, similar to the crosslinked (meth) acrylic acid ester resin particles. The material of the inorganic fine particles is not limited as long as it contains at least one element selected from silicon, titanium and aluminum. Specific examples thereof include silica, titanium oxide, aluminum oxide and hydrotalcite. Silica is more preferable from the viewpoint of making the sliding angle 10 ° or more and 40 ° or less so that the developer can be easily supported.
Further, these inorganic fine particles may be subjected to surface treatment such as hydrophobization or hydrophilization, if necessary. In particular, silica is more preferable because it is easy to surface-treat and it is easy to control the affinity with the crosslinked (meth) acrylic acid ester resin particles. One kind or two or more kinds of these inorganic fine particles may be used.

The average particle size of the inorganic fine particles is preferably 10 nm or more and 5 μm or less from the viewpoint of uniformly dispersing the inorganic fine particles and supporting the developer satisfactorily.

Further, the inorganic fine particles may be dispersed alone in the urethane resin, or may be attached so as to cover at least a part of the crosslinked (meth) acrylic acid ester resin particles. When the particles are adhered so as to cover at least a part of the crosslinked (meth) acrylic acid ester resin particles, the average particle size of the inorganic fine particles is such that the coating property with respect to the crosslinked (meth) acrylic acid ester resin particles is good. Therefore, it is preferably 5 nm or more and 200 nm or less. Further, it is more preferably 5 nm or more and 50 nm or less because it can be effectively coated by adding a small amount. In particular, when the inorganic fine particles are silica, the average particle size of the silica fine particles is preferably 10 nm or more and 5 μm or less. The average particle diameter of the inorganic fine particles is also a value measured by the method for measuring the volume average diameter of the resin particles.

The content of the inorganic fine particles is preferably 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the urethane adjusting component in the resin composition for forming the coating layer. By setting the amount to 1 part by mass or more, the slipperiness of the surface of the coating layer 4 can be improved, and the developer can be well supported and transported to the photoconductor. Further, when the content is 10 parts by mass or less, the dispersion of particles can be improved, the uniformity of the surface state of the coating layer can be maintained, and filming can be satisfactorily suppressed. More preferably, it is 2 parts by mass or more and 8 parts by mass or less.

(Conductivity imparting agent)
The coating layer 4 may further contain a conductivity-imparting agent. The conductivity-imparting agent is not particularly limited as long as it is a component that can impart conductivity to the coating layer 4. As the conductivity-imparting agent, the conductivity-imparting agent used for the coating layer 4 described above can be used. The blending amount of the conductivity-imparting agent is not particularly limited, and may be appropriately adjusted according to the type of the conductivity-imparting agent, the desired conductivity performance, and the like. Further, the conductivity-imparting agent may be used alone or in combination of two or more.

(Other ingredients)
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 can be formed by applying a resin composition for forming a coating layer on the elastic layer 3 and polymerizing the polyol component and the isocyanate component by heating or the like. The solvent used in the coating liquid is preferably a solvent capable of dissolving the polyol component and the polyisocyanate component, and may be, for example, ethyl acetate, butyl acetate or the like.

[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 have the electrical characteristics as the developing roller 1 by adjusting the electrical characteristics thereof. With this, the development performance of the developing roller 1 as a developing roller can be satisfactorily adjusted.

As the primer layer, a primer layer 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 development performance of the developing roller is maintained well. can do.

<Developer and image forming device>
The developing roller according to the present invention can be suitably used as a developer carrier in a developing apparatus and an image forming apparatus. In the present embodiment, the configuration other than the developing roller in the image forming apparatus is not particularly limited. An embodiment of a developing apparatus and an image forming apparatus provided with a developing roller 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 mounted on the developing units B, C, M and Y of each color are arranged in series on the transfer transfer belt 6. The developing units B, C, M and Y are arranged in series on the transfer transfer belt 6. The developing unit B carries an image via an image carrier 11B, for example, a photosensitive member (also referred to as a photosensitive drum), a charging means 12B, for example, a charging roller, an exposure means 13B, a developing device 20B, and a transfer transfer belt 6. A transfer means 14B that comes into contact with the body 11B, for example, a transfer roller and a cleaning means 15B are provided.

The developing device 20B is an embodiment of the developing device of the present invention, and includes the developing roller of the present invention. As shown in FIG. 2, in the image forming apparatus 10, the developing rollers are mounted as the developer carriers 23B, 23C, 23M and 23Y. Specifically, the developing apparatus 20B has an image of a housing 21B accommodating a one-component non-magnetic developer 22B, a developing agent supply roller 25B for transporting the developing agent 22B to the developing agent carrier 23B, and a developing agent 22B. The developer carrier 23B supplied to the carrier 11B and the developer amount adjusting means 24B for adjusting the thickness of the developer 22B, for example, a blade are provided. In the developing apparatus 20B, the developing agent amount adjusting means 24B is in contact with or pressed against the outer peripheral surface of the developing agent carrier 23B as shown in FIG. That is, the developing device 20B is a "contact developing device". The developing units C, M and Y are basically configured in the same manner as the developing unit B, and the same elements are designated by the same reference numerals and the symbols C, M or Y indicating each unit, and the description thereof will be omitted. ..

In the image forming apparatus 10, the developer carrier 23B of the developing apparatus 20B is arranged so that its surface is in contact with or pressed against the surface of the image carrier 11B. Similar to the developing device 20B, the developing devices 20C, 20M and 20Y are also arranged so that the surface of the developing devices 23C, 23M and 23Y is in contact with or pressed against 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 means 30 is arranged on the downstream side of the developing unit Y. The fixing means 30 includes a fixing roller 31, an endless belt support roller 33 arranged in the vicinity of the fixing roller 31, a fixing roller 31, and an endless belt in a housing 34 having an opening 35 through which the recording body 16 is passed. 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 pressure-welded to each other via the endless belt 36. It is a pressure heat fixing device that is rotatably supported so as to be. A cassette 41 for accommodating the recording body 16 is installed at the bottom of the image forming apparatus 10. The transfer transfer 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 a dry developer or a wet developer as long as they can be charged by friction, and may be a non-magnetic developer or magnetic developer. It may be an agent. A one-component non-magnetic black developer 22B, a cyan developer 22C, a magenta developer 22M, and a yellow developer 22Y are housed in the housings 21B, 21C, 21M, and 21Y of each developing unit.

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 means 12B by the exposure means 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, the black electrostatic latent image is transferred to the surface of the recording body 16B. Next, in the same manner as in the developing unit B, the cyan image, the magenta image, and the yellow image are superimposed on the recording body 16 in which the electrostatic latent image is visualized as a black image by the developing units C, M, and Y, respectively. A color image is visualized. Next, in the recording body 16 in which the color image is visualized, the color image is fixed to the recording body 16 as a permanent image by the fixing means 30. In this way, a color image can be formed on the recording body 16.

The developing apparatus 20 includes a developing roller 1, which is excellent in developer transportability and suppresses the occurrence of toner filming, and can contribute to forming a high-density, high-quality image for a long period of time. In addition, this image forming apparatus can form a high-density and high-quality image for a long period of time.

The developing apparatus and the image forming apparatus of the present invention are not limited to those described above, and various modifications can be made 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 the electrophotographic system, and may be, for example, an electrostatic type image forming apparatus. .. Further, the image forming apparatus in which the developing rollers of the present invention are arranged is not limited to a tandem type color image forming apparatus in which a plurality of image carriers equipped with developing units of each color are arranged in series on a transfer transfer belt, for example. , A monochrome image forming apparatus provided with a single developing unit, a 4-cycle type color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier onto an endless belt, or the like 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. Alternatively, it may be a two-component magnetic developer.

The image forming apparatus 10 is a contact type image forming apparatus arranged by contacting or pressing against an image carrier, a developer supply roller, a blade, or 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 carrier does not come into contact with the surface of the image carrier.

Although the present invention has been described above with reference to 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 apparent to those skilled in the art that improvements can be made. It is also clear from the description of the claims that the invention with such changes or improvements may 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]
The shaft body (made by SUM22, diameter 10 mm, length 275 mm) 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.) is applied to the surface thereof. Applied. The primer-treated shaft was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the outer peripheral surface of the shaft.

Next, a silicone rubber composition for forming an elastic layer was prepared as follows. That is, hydrophobized fumed silica (trade name "R-972") having 100 parts by mass of dimethylpolysiloxane (polymerization degree 300) having both ends sealed with a dimethylvinylsiloxy group and a BET specific surface area of 110 m ² / g. , Nippon Aerosil Co., Ltd.) 1 part by mass, average particle size 6 μm, bulk density 0.25 g / cm ³ diatomaceous soil (trade name “Opreite W-3005S”, manufactured by Chuo Silica Co., Ltd.) 40 parts by mass, and , 5 parts by mass of acetylene black (trade name "Denka Black HS-100", manufactured by Denka Co., Ltd.) was placed in a planetary mixer, stirred for 30 minutes, and then passed through three rolls once. Returning this to the planetary mixer again, methylhydrogenpolysiloxane having Si—H groups at both ends and side chains (polymerization degree 17, Si—H amount 0.0060 mol / g) 2.1 parts by mass, ethynylcyclohexanol 0.1 part by mass and 0.1 part by mass of a platinum catalyst (Pt concentration 1%) were added, and the mixture was stirred for 30 minutes for defoaming and kneading 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 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.

Next, a resin composition for forming a coating layer was prepared as follows. That is, 35 parts by mass of acrylic polyol, 46 parts by mass of hexamethylene diisocyanate (trade name "Duranate E402-B80B", manufactured by Asahi Kasei Co., Ltd.), 0.03 parts by mass of dibutyltin dilaurate (manufactured by Tokyo Kasei Kogyo Co., Ltd.), small diameter silica (average). Particle size 4.4 μm, trade name “ACEMATT OK-607”, manufactured by Ebonic Degusa Co., Ltd.) 4 parts by mass, restoration rate 33%, 10% compression strength 0.4 MPa, 10 parts by mass of crosslinked acrylic acid ester resin particles, conductivity A resin composition was obtained by mixing 3 parts by mass of carbon black (trade name "Denka Black HS-100", manufactured by Denka Co., Ltd.) and 30 parts by mass of thinner as an imparting agent.

This 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 7 μm. In this way, a developing roller provided with a shaft body, an elastic layer and a coating layer was produced.

[Example 2]
A developing roller was produced in the same manner as in Example 1 except that the coating layer was formed of the following resin composition.
42 parts by mass of acrylic polyol, hexamethylene diisocyanate (trade name "Duranate E402-B80B", manufactured by Asahi Kasei Co., Ltd.) 52 parts by mass, dibutyltin dilaurate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 0.03 parts by mass, small diameter silica (average particle diameter) 4.4 μm, trade name “ACEMATT OK-607”, manufactured by Ebonic Degusa Co., Ltd.) 4 parts by mass, restoration rate 33%, 10% compression strength 0.4 MPa, 20 parts by mass of crosslinked acrylic acid ester resin particles, carbon black (product) A resin composition was obtained by mixing 3 parts by mass of the name "Denka Black HS-100" (manufactured by Denka Co., Ltd.) and 30 parts by mass of thinner.

[Example 3]
A developing roller was produced in the same manner as in Example 1 except that the coating layer was formed of the following resin composition.
42 parts by mass of acrylic polyol, hexamethylene diisocyanate (trade name "Duranate E402-B80B", manufactured by Asahi Kasei Co., Ltd.) 52 parts by mass, dibutyltin dilaurate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 0.03 parts by mass, small diameter silica (average particle diameter) 4.4 μm, trade name “ACEMATT OK-607”, manufactured by Ebonic Degusa Co., Ltd.) 4 parts by mass, recovery rate 20%, 10% compression strength 0.4 MPa crosslinked acrylic acid ester resin particles (trade name “Techpolymer AFX-” 8. Mix 10 parts by mass of "Sekisui Kasei Kogyo Co., Ltd.", 3 parts by mass of carbon black (trade name "Denka Black HS-100", manufactured by Denka Co., Ltd.), and 30 parts by mass of thinner to make a resin composition. Got

(Comparative Example 1)
A developing roller was produced in the same manner as in Example 1 except that the coating layer was formed of the following resin composition.
42 parts by mass of acrylic polyol, hexamethylene diisocyanate (trade name "Duranate E402-B80B", manufactured by Asahi Kasei Co., Ltd.) 52 parts by mass, dibutyltin dilaurate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 0.03 parts by mass, small diameter silica (average particle diameter) 4.4 μm, trade name “ACEMATT OK-607”, manufactured by Ebonic Degusa Co., Ltd.) 4 parts by mass, carbon black (trade name “Denka Black HS-100”, manufactured by Denka Co., Ltd.) 3 parts by mass, and 30 parts by mass of thinner. The parts were mixed to obtain a resin composition.

(Comparative Example 2)
A developing roller was produced in the same manner as in Example 1 except that the coating layer was formed of the following resin composition.
34 parts by mass of acrylic polyol, 45 parts by mass of hexamethylene diisocyanate (trade name "Duranate E402-B80B", manufactured by Asahi Kasei Co., Ltd.), 0.03 parts by mass of dibutyltin dilaurate (manufactured by Tokyo Kasei Kogyo Co., Ltd.), restoration rate 33%, 10 A mixture of 17 parts by mass of crosslinked acrylic acid ester resin particles having a% compression strength of 0.4 MPa, 3 parts by mass of carbon black (trade name "Denka Black HS-100", manufactured by Denka Co., Ltd.), and 30 parts by mass of thinner was mixed. A resin composition was obtained.

(Comparative Example 3)
A developing roller was produced in the same manner as in Example 1 except that the coating layer was formed of the following resin composition.
34 parts by mass of acrylic polyol, hexamethylene diisocyanate (trade name "Duranate E402-B80B", manufactured by Asahi Kasei Co., Ltd.) 45 parts by mass, dibutyltin dilaurate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 0.03 parts by mass, urethane particles (trade name "" Art Pearl JB-800T ", manufactured by Negami Kogyo Co., Ltd.) 17 parts by mass, carbon black (trade name" Denka Black HS-100 ", manufactured by Denka Co., Ltd.) 3 parts by mass, and thinner 30 parts by mass are mixed. A resin composition was obtained.

(Comparative Example 4)
A developing roller was produced in the same manner as in Example 1 except that the coating layer was formed of the following resin composition.
34 parts by mass of acrylic polyol, hexamethylene diisocyanate (trade name "Duranate E402-B80B", manufactured by Asahi Kasei Co., Ltd.) 45 parts by mass, dibutyltin dilaurate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 0.03 parts by mass, restoration rate 33%, 10 17 parts by mass of crosslinked acrylic ester resin particles having a% compression strength of 0.4 MPa and 30 parts by mass of thinner were mixed to obtain a resin composition.

[evaluation]

Next, an image forming apparatus C610dn2 (model number, manufactured by Oki Data Corporation) was prepared, and the developing roller of this image forming apparatus was replaced with the developing rollers produced in the above Examples and Comparative Examples to obtain an image forming apparatus. With respect to the obtained image forming apparatus, filming was evaluated, print density was evaluated, image uniformity was evaluated, and storage stability was performed by the following methods.

<Sliding angle>
Place the base on which the PET (polyethylene terephthalate) film is laid horizontally (angle 0 ° with the horizontal plane), and place it on the base so that the longitudinal direction of the base is parallel to the axial direction of the developing roller. , The developing rollers of Examples and Comparative Examples were placed. With one end of the base fixed in the longitudinal direction, the other end is raised to gradually incline the base, and the horizontal plane of the base when the developing roller starts to slide toward one end. The angle formed by was taken as the sliding angle.

<Evaluation of filming>
Using an image forming apparatus equipped with the produced developing roller, the developer adhering to the surface of the developing roller after printing 10,000 sheets is sucked under the conditions of temperature 23 ° C. and humidity 55% RH, and then the filming weight is measured. The mass transferred to the jig was measured. The filming evaluation was based on the mass of the transferred developer according to the following criteria. In this test, the filming amount is passed when the evaluation is B.
A: 0 mg or more and less than 0.02 mg B: 0.02 mg or more and less than 0.05 mg C: 0.05 mg or more

<Evaluation of print density>
A solid image was printed under the conditions of temperature 23 ° C. and humidity 55% RH, temperature 30 ° C. and humidity 80% RH, room temperature 10 ° C. and humidity 20% RH, and manufactured by X-Rite. The print density of the solid image was measured using a 508 spectroscopic densitometer. Specifically, 1.4 or more was designated as A, 1.2 or more and less than 1.4 was designated as B, and less than 1.2 was designated as C.

<Evaluation of image uniformity>
A solid image is printed under the conditions of temperature 23 ° C. and humidity 55% RH, temperature 30 ° C. and humidity 80% RH, temperature 10 ° C. and humidity 20% RH, respectively, and the print density of the first sheet is printed. Was compared with the print density of the 2000th sheet. Specifically, the case where the density step ratio between the initial print forming portion and the final print forming portion of solid printing is 1.1 or less is defined as A, the case where it is within 1.2 is defined as B, and the case where it is larger than 1.2 is defined as B. It was designated as C.

<Evaluation of storage stability>
The developing roller was replaced with a toner cartridge, and the mixture was stored at a temperature of 50 ° C. and a humidity of 65% RH for 1 month. The presence or absence of horizontal streaks after printing 20 sheets was confirmed, and after printing 20 sheets, the one in which no horizontal streaks were observed was designated as A, the one in which the horizontal streaks were considerably thin was designated as B, and the one in which the horizontal streaks could be confirmed was designated as C.

The evaluation results are shown in Table 1 together with the main components of the coating layer. The unit of the component of the coating layer in Table 1 is a mass part.

As shown in Table 1, in the example using a developing roller having a coating layer containing crosslinked (meth) acrylic acid ester resin particles and inorganic fine particles, in all of filming, print density, image uniformity, and storage stability. , B or higher.
On the other hand, Comparative Example 1 containing no crosslinked (meth) acrylic acid ester resin particles was inferior in filming and image quality uniformity. Further, Comparative Example 2 containing no inorganic fine particles was inferior in filming, print density, and image quality uniformity.

1 Develop roller 2 Axis 3 Elastic layer 4 Coating layer 6 Transfer transfer belt 10 Image forming device 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 Recorder 20B, 20C, 20M, 20Y Developer 21B, 21C, 21M, 21Y, 34 Housing 22B, 22C, 22M, 22Y Developer 23B, 23C, 23M, 23Y Developer carrier 24B, 24C, 24M, 24Y Developer amount adjusting means 25B, 25C, 25M, 25Y Developer supply roller 30 Fixing means 31 Fixing roller 32 Pressurizing roller 33 Endless belt support roller 35 Aperture 36 Endless belt 41 Cassette 42 Support roller B, C, M, Y Development unit

Claims (7)

A developing roller having a shaft body, an elastic layer provided on the outer periphery of the shaft body, and a coating layer provided on the outer periphery of the elastic layer.
The coating layer is a urethane resin as a binder, a conductivity-imparting agent dispersed in the binder, and a crosslinked (meth) acrylic acid ester resin dispersed in the binder to form irregularities on the surface of the coating layer. Including particles and inorganic fine particles,
A developing roller in which the inorganic fine particles are silica fine particles and the average particle diameter of the silica fine particles is 10 nm or more and 5 μm or less . The developing roller according to claim 1, wherein the crosslinked (meth) acrylic acid ester resin particles have a restoration rate of 20% or more and a 10% compressive strength of 0.1 MPa or more and 2.2 MPa or less. The developing roller according to claim 1 or 2 , wherein the average particle size of the crosslinked (meth) acrylic acid ester resin particles is 1 μm or more and 15 μm or less. The developing roller according to any one of claims 1 to 3 , wherein the surface sliding angle is 10 ° or more and 40 ° or less. The conductivity-imparting agent is a conductive agent having an electron conduction mechanism, a conductive agent having an ion conduction mechanism, and the like.
The developing roller according to any one of claims 1 to 4 , which is at least one selected from the conductive composite particles. A developing apparatus including the developing roller according to any one of claims 1 to 5 . An image forming apparatus comprising the developing roller according to any one of claims 1 to 5 .

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