JP2019168614A - Developing roller, developing device, and image forming apparatus - Google Patents

Abstract

To provide a developing roller that favorably prevents the occurrence of filming and is excellent in durable printing performance, and a developing device and an image forming apparatus including the developing roller.SOLUTION: A developing roller 1 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 contains a urethane resin as a binder, a conductive material dispersed in the binder, and crosslinked (meth)acrylic acid ester resin particles and inorganic fine particles dispersed in the binder and for forming irregularities on the surface of the coating layer 4.SELECTED DRAWING: Figure 1

Description

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

  A developing roller used in an image forming apparatus such as a copying machine, a printer, or a facsimile that employs an electrophotographic system has a function of transporting 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, particularly the print density. Accordingly, 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, thereby improving the developer transportability of the developing roller.

  Here, when the developing roller is used for a long period of time, the developer may adhere to the surface thereof (referred to as “filming”). In such filming, for example, when the developer is charged or adhered, the developer is deformed or destroyed by a sliding stress such as a blade pressed against the developing roller, and further developed by frictional heat with the blade or the like. It is thought to be caused by 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 apparatuses, various investigations have been made on the structure of the developing roller and the particles contained in the surface layer as another approach for improving the image quality. For example, Patent Document 1 discloses a developing roller in which a surface layer contains urethane resin particles whose surfaces are partially coated with inorganic fine particles.

  On the other hand, resin particles used for various applications have been developed. For example, Patent Document 2 discloses crosslinked (meth) acrylic acid ester resin particles used for coatings and cosmetics on the surface of automobile interior parts. It is 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 cope with the performance of image forming apparatuses that have been required in recent years. 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 apparatus in which the occurrence of filming is satisfactorily suppressed and excellent in durable printing performance.

  As a result of intensive studies, the present inventors have found that the occurrence of filming can be satisfactorily suppressed by dispersing certain particles in the coating layer of the 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, the coating layer being a urethane resin as a binder And a conductivity-imparting agent dispersed in the binder, and a crosslinked (meth) acrylate resin particle and inorganic fine particles dispersed in the binder and forming irregularities on the surface of the coating layer.
Here, (meth) acrylic acid ester means a generic name including both acrylic acid ester and methacrylic acid ester.

  The crosslinked (meth) acrylic ester resin particles preferably 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 inorganic fine particles are 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 diameter 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 electron conduction mechanism, a conductive agent having an ionic conduction mechanism, and conductive composite particles.

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

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

  According to the present invention, the coating layer is a urethane resin as a binder, a conductivity imparting agent dispersed in the binder, and a crosslinked (meth) acrylic acid that is dispersed in the binder and forms irregularities on the surface of the coating layer. By including the ester resin particles and inorganic fine particles, when the filming occurs on the developing roller in an amount that does not cause a problem in image quality, the fixed matter is easily pressed by the developer amount adjusting unit and the toner supply roller. Therefore, before the unevenness in the charge amount of the developing roller occurs, the occurrence of filming is suppressed satisfactorily, and a developing roller, a developing device, and an image forming apparatus excellent in durable printing performance can be obtained.

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

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

<Developing roller>
As shown in FIG. 1, the developing roller 1 of the present invention includes 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 includes a urethane resin as a binder, a conductive material dispersed in the binder, and a crosslinked (meth) acrylate resin particle that is dispersed in the binder and forms irregularities on the surface of the coating layer 4. And inorganic fine particles.
Details of the configuration of the developing roller 1 of the present invention will be described below.

[Shaft]
The shaft body 2 is preferably a conductive shaft body used in a conventionally known developing roller. The shaft body 2 is preferably made of at least one metal selected from the group consisting of iron, aluminum, stainless steel, and brass, for example. The shaft body 2 made of such a metal is generally known by the name “core metal”.

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

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

  The shape of the shaft body 2 is preferably, for example, a rod shape or a tubular shape. The cross-sectional shape of the shaft body 2 may be, for example, a circle or an ellipse, or may be 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 adhesion 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 installed image forming apparatus. For example, when the object to be printed is A4 size, the axial length of the shaft body 2 is preferably 250 mm or more and 320 mm or less, and more preferably 260 mm or more and 310 mm or less. 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 heat-curing a rubber composition on the outer peripheral surface of the shaft body 2. The rubber composition for forming the elastic layer 3 preferably contains rubber, a conductivity imparting agent, and various additives as required.

(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 fluorine rubber. Silicone or silicone-modified rubber or urethane rubber is preferable. Silicone or silicone-modified rubber can reduce compression set and has excellent flexibility in a low-temperature environment, and further has heat resistance and charging characteristics. It is particularly preferable in that it is excellent. Examples of the silicone rubber include crosslinked products of organopolysiloxanes such as dimethylpolysiloxane and diphenylpolysiloxane.

-Conductivity imparting agent-
Conductivity-imparting agents such as carbon black, graphite, copper, aluminum, nickel, iron powder, and conductive agents with electron conduction mechanisms such as conductive metal oxides, ion conduction mechanisms such as alkali metal salts and quaternary ammonium salts A conductive agent having conductive composite particles in which conductive particles such as carbon black particles are provided on the surface of silica particles is preferable.
As the conductivity imparting agent, carbon black is particularly preferable. 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 carbon black, one of these may be used alone, or two or more may be used in combination. In order to obtain a desired electric 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 it is still more preferable that it is 2.0 mass% or more and 10 mass% or less. By adjusting the content of the conductivity imparting agent to the above range, the resistance value of the developing roller 1 is further stabilized, the printing performance is further improved, and the compression set of the elastic layer 3 is reduced, whereby the developing roller is reduced. The durability of 1 is further improved.

-Various additives-
The rubber composition may further contain various additives other than those described above. Examples of various additives include auxiliary agents (chain extenders, crosslinking agents, etc.), catalysts, dispersants, foaming agents, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softening agents. , Plasticizers, emulsifiers, heat resistance improvers, flame retardant improvers, acid acceptors, heat conductivity improvers, mold release agents, solvents and the like.

  Examples of the silicone rubber composition include an addition curable millable conductive silicone rubber composition, an addition curable liquid conductive silicone rubber composition, and the like.

The addition-curable millable conductive silicone rubber composition contains, for example, (A) an organopolysiloxane represented by the following average composition formula (1), (B) a filler, and (C) a conductivity-imparting agent. 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. R ¹ represents 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, more preferably 1 or more and 8 or less.

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

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

(A) The organopolysiloxane preferably has two or more alkenyl groups in the molecule. (A) The organopolysiloxane preferably has 0.001 mol% to 5 mol% (more preferably 0.01 mol% to 0.5 mol%) of alkenyl groups in R ¹ . (A) As an alkenyl group which organopolysiloxane has, a vinyl group is particularly preferable.

  (A) Organopolysiloxane, for example, undergoes ring-opening polymerization of cyclic polysiloxane such as trimer or tetramer of siloxane by cohydrolytic condensation of one or more of organohalosilanes Can be obtained. (A) The organopolysiloxane may basically be a linear diorganopolysiloxane, and may be partially branched. Further, (A) the 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, and more preferably 100000 cSt or more and 10000000 cSt or less. Moreover, the polymerization degree of (A) organopolysiloxane is, for example, preferably 100 or more, and more preferably 3000 or more and 10,000 or less.

  (B) As a filler, a silica type filler is mentioned, for example. Examples of the silica filler include fumed silica and precipitated silica.

As the silica-based filler, a surface-treated silica-based filler that has been surface-treated with a silane coupling agent represented by R ² Si (OR ³ ) ₃ can be suitably used. Here, R ² may be a group having a vinyl group or an amino group, and may be, for example, a glycidyl group, a vinyl group, an aminopropyl group, a methacryloxy group, an N-phenylaminopropyl group, a mercapto group, or the like. R ³ may be an alkyl group, for example, a methyl group, an ethyl group, or the like. A silane coupling agent can be easily obtained as, for example, trade names “KBM1003”, “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. A commercially available product may be used as the surface-treated silica-based filler. M.M. A trade name “Zeothix 95” manufactured by HUBER Co., Ltd. may be mentioned.

  The compounding 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. In addition, the average particle diameter of a silica type filler can be measured as a median diameter using the particle size distribution measuring apparatus by a laser beam diffraction method.

  (C) The compounding amount of the 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) the organopolysiloxane.

  The addition-curable millable conductive silicone rubber composition may further contain additives other than (A) to (C). Examples of additives include auxiliary agents (chain extenders, crosslinking agents, etc.), catalysts, dispersants, foaming agents, anti-aging agents, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, An emulsifier, a heat resistance improver, a flame retardant improver, an acid acceptor, a thermal conductivity improver, a release agent, a solvent and the like can be mentioned.

  Specific examples of additives include (A) dimethylsiloxane oil having a lower degree of polymerization than organopolysiloxane, polyether-modified silicone oil, silanol, diphenylsilanediol, α, ω-dimethylsiloxanediol, etc. Dispersants such as low molecular siloxanes and silanes can be mentioned. Specific examples of the additive include heat resistance improvers such as iron octylate, iron oxide, and cerium oxide. Moreover, as an additive, you may use various carbon functional silane, various olefin type elastomers, etc. for improving adhesiveness, moldability, etc.

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

(D) As the organopolysiloxane, a compound represented by the following average composition formula (2) is preferable.
R ⁴ _a SiO _{(4-a) / 2} (2)
In the formula (2), a represents a positive number of 1.5 or more and 2.8 or less, preferably 1.8 or more and 2.5 or less, more preferably 1.95 or more and 2.05 or less. R ⁴ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. However, at least two of R ^{4 in} one molecule are alkenyl groups. The number of carbon atoms of 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 as R ¹ above. Moreover, it is preferable that at least two of R ^{4 in} one molecule are alkenyl groups, and other R ⁴ is an alkyl group. The alkenyl group is preferably a vinyl group, and the alkyl group is preferably a methyl group. Also, for example, 90% or more of R ⁴ may be an alkyl group (preferably a methyl group). (D) The content of the alkenyl groups in the organopolysiloxane, for example, is preferably not more than 1.0 × ¹⁰ -6 mol / g or more ^{5.0 × 10 -3 mol / g,} 5.0 × 10 - More preferably, it is 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 to 1000000 mPa · s, more preferably 200 mPa · s to 100000 mPa · s. preferable. 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.

(E) As the organohydrogenpolysiloxane, a compound represented by the following average composition formula (3) is preferable.
R ⁵ _b H _c SiO _{(4-b-c) / 2} (3)
In formula (3), b represents a positive number from 0.7 to 2.1, c represents a positive number from 0.001 to 1.0, and bc is from 0.8 to 3.0. It is. R ⁵ represents 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. Examples of R ⁵ include the same groups as those exemplified as R ¹ above.

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

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

(E) Examples of the organohydrogenpolysiloxane include, for example, a trimethylsiloxy group-capped methylhydrogen polysiloxane at both ends, a trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer, and a dimethylhydrogensiloxy group-capped 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 diphenylsiloxane-dimethylsiloxane _copolymers, copolymers 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 _{(C 6} H ₅₎ consisting of _{SiO 3/2} units, copolymers composed, and the like.

  (E) The amount of the organohydrogenpolysiloxane is preferably 0.1 parts by mass or more and 30 parts by mass or less, and 0.3 parts by mass or more and 20 parts by mass with respect to 100 parts by mass of the (D) organopolysiloxane. The following is more preferable. 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. It is more preferable that

  (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 diameter 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 diameter of a filler is 1 micrometer or more, the time-dependent change of volume resistivity is further suppressed. Moreover, the elastic layer 3 which is further excellent in durability can be obtained as the average particle diameter of the filler (F) is 30 μm or less. In addition, the average particle diameter of (F) filler can be measured as a median diameter using the particle size distribution measuring apparatus by a laser beam diffraction method.

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

  Examples of the filler (F) include diatomaceous earth, pearlite, mica, calcium carbonate, glass flake, and a hollow filler. Among these, as the filler (F), a pulverized product of diatomaceous earth, pearlite, and foamed pearlite can be suitably used.

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

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

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

  (H) The addition amount of the addition reaction catalyst may be a catalytic amount. For example, the blending amount of the (H) addition reaction catalyst is such that the platinum group element amount 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 be 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, crosslinking agents, etc.), foaming agents, dispersants, anti-aging agents, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, Examples include a heat resistance improver, a flame retardant improver, an acid acceptor, a thermal conductivity improver, a mold release agent, a diluent, a reactive diluent, a solvent, and the like.

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

  The viscosity at 25 ° C. of the addition-curable liquid conductive silicone rubber composition 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 performing heat curing and molding simultaneously or continuously by a known molding method. The method for curing the rubber composition may be any method that can apply heat necessary for curing the rubber composition, and the molding method for the elastic layer 3 is particularly limited, such as continuous vulcanization by extrusion, pressing, or molding by injection. Is not to be done. For example, when the rubber composition is an addition-curable millable 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 this case, for example, a molding method using a mold can be selected.

  The heating temperature for curing the rubber composition is 100 ° C. or more and 500 ° C. or less, particularly 120 ° C. or more and 300 ° C. or less, and the time is several seconds or more and 1 hour or less, particularly in the case of an addition curable type millable conductive silicone rubber composition. It is preferably 10 seconds or more and 35 minutes or less. 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, secondary vulcanization may be performed as necessary. In the case of an addition-curable millable conductive silicone rubber composition, for example, a curing condition of 100 to 200 ° C. for 1 to 20 hours is selected. In addition, in the case of an addition curable liquid conductive silicone rubber composition, for example, a curing condition of 120 ° C. or higher and 250 ° C. or lower and about 2 hours or longer and 70 hours or shorter is selected. The rubber composition can be foam-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, but 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 axial direction of the developing roller 1.

  The outer diameter of the elastic layer 3 is not specifically limited, For example, it is preferable that they are 6 mm or more and 25 mm or less, and it is more preferable that they are 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, frame treatment, etc. for the purpose of improving the adhesion with the coating layer 4. It's okay.

  The formation method of the elastic layer 3 is not specifically limited. For example, the elastic layer 3 may be formed by a method such as extrusion molding or LIMS molding of a silicone rubber composition. 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 provided on the outermost surface of the developing roller 1 on the outer periphery of the elastic layer. The coating layer 4 is formed by applying the resin composition to the outer peripheral surface of the elastic layer 3 or the primer layer formed as desired, and then heat-curing the applied 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. The coating layer 4 is not necessarily formed by heating and curing the resin composition, but is formed by a silicone coating treatment using ethyl silicate and a treatment including titanium, aluminum, zirconium, etc. as a treatment agent. It may be a layer.

  Coating of the resin composition includes, for example, a coating method of coating a coating liquid of the resin composition, a dipping method of immersing the elastic layer 3 etc. in the coating liquid, and spray coating in which the coating liquid is sprayed on the elastic layer 3 etc. It is performed by a known coating method such as a method. The resin composition may be applied as it is, and for example, alcohol such as methanol and ethanol, aromatic solvent such as xylene and toluene, ester solvent such as ethyl acetate and butyl acetate, etc. You may apply the coating liquid which added the volatile solvent or water. The method of curing the resin composition thus coated may be any method that can add heat or moisture necessary for curing the resin composition, for example, an elastic layer coated with the resin composition. The method of heating 3 etc. with a heater, the method of leaving the elastic layer 3 etc. with which the resin composition was coated under high humidity, etc. are mentioned. The heating temperature for heat curing the resin composition is preferably, for example, 100 ° C. or more and 200 ° C. or less, more preferably 120 ° C. or more and 160 ° C. or less, and the heating time is 10 minutes or more and 120 minutes or less. It is preferable that it is 30 minutes or more and 60 minutes or less. In addition, 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 the like, or after lamination. For example, a method of curing the formed resin composition can be employed.

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

(Slip angle)
The slip 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.
Here, in this specification, the “slip angle” means that a base on which a PET (polyethylene terephthalate) film is laid horizontally (angle 0 ° with respect to a horizontal plane) The developing roller is placed on the base so that the axial direction of the developing roller is parallel. Next, with one end in the longitudinal direction of the base fixed, the other end is lifted to gradually tilt the base, and the base when the developing roller starts to slide toward the one end Of the horizontal plane.

  When the slip angle of the surface of the developing roller is 10 ° or more, the developing roller can carry the developer well and transport it to the photoreceptor. Further, when the angle is 40 ° or less, the developer is easily detached after adhering to the developing roller, so that a predetermined amount of developer according to the image data can be supplied. That is, by setting the slip angle to 10 ° or more and 40 ° or less, the developer can be appropriately carried and conveyed, and a high-quality image can be maintained.

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

(Thickness)
The thickness of the coating layer 4 is substantially the same as the average particle diameter of the crosslinked (meth) acrylic acid ester resin particles described later, specifically, 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 favorably 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, only needs to be able to form a urethane resin, and examples thereof include a mixture of a polyol and an isocyanate.

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

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

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

  Polyacrylate polyols include hydroxyl group-containing monomers and other olefinically unsaturated monomers such as esters of (meth) acrylic acid, styrene, α-methylstyrene, vinyl toluene, 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 polymers.

  The polycarbonate polyol has two or more carbonate bonds and two or more hydroxyl groups in the molecule. Examples of the polycarbonate polyol include a condensation reaction product of a polyol and a carbonate compound. Examples of the carbonate compound include dialkyl carbonate, diaryl carbonate, and alkylene carbonate. Examples of the polyol used as a raw material for the polycarbonate polyol include diols such as hexanediol and butanediol, and triols such as 2,4-butanetriol.

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

  The mixing ratio in the mixture of polyol and polyisocyanate is not particularly limited, but usually the molar ratio (NCO / OH) of the hydroxyl group (OH) contained in the polyol to the isocyanate group (NCO) contained in the polyisocyanate is 0. It is preferable that it is 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 that the hydrolysis of polyurethane can be prevented. In practice, an amount equivalent to 3 to 4 times the appropriate molar ratio may be blended in consideration of work environment and work errors.

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

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

The crosslinked (meth) acrylic ester resin particles preferably 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. From such a viewpoint, urethane (meth) acrylic acid ester is particularly preferable among the acrylic acid esters. When the crosslinked (meth) acrylic 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 following effects are obtained.
The developing roller 1 is in contact with the developer amount adjusting unit and the photosensitive member in a pressed state. However, if the developing roller 1 is left in a pressed state for a long time after use, the developer amount adjusting unit and the photosensitive member 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, the density unevenness of the image may occur at a position corresponding to the crushed coating layer 4.
However, according to the present invention, the coating layer 4 contains crosslinked (meth) acrylate resin particles having a restoration rate of 20% or more and a 10% compression strength of 0.1 MPa or more and 2.2 MPa or less. Therefore, even after being left for a long time, when the engine is restarted, the portion that has been crushed by a plurality of rotations is recovered, 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 diameter) when a load of 9.8 mN is applied and then the load is reduced to 0.98 mN. It means a value obtained by the following formula 1 from the amount of displacement of the particle diameter and the particle diameter of the spherical particles before applying a load.
Restoration rate (%) = [displacement of particle diameter (μm) / particle diameter (μm)] × 100 Equation 1
(Restoration rate measurement conditions)
Test temperature: 50% RH at 23 ° C
・ Upper pressure indenter: Diamond flat indenter with a diameter of 50 μm ・ Lower pressure plate: SKS flat plate ・ Measurement mode: Unloading test ・ Load speed: 0.98 mN / sec ・ Maximum load: 9.8 mN

Further, “10% compressive strength” in the present invention means a value measured by the following method. It is set as the value measured on the following measurement conditions using the micro compression tester MCT 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 a compressive strength (MPa).
(Measurement conditions for compressive strength)
Test temperature: 50% RH at 23 ° C
・ Upper pressure indenter: Diamond flat indenter with a diameter of 50 μm ・ Lower pressure plate: SKS flat plate ・ Measurement mode: compression test ・ Loading speed: 0.98 mN / sec ・ Maximum load: until reaching 10% of the particle diameter

  Examples of commercially available crosslinked (meth) acrylic ester resin particles having a restoration rate of 20% or more and a 10% compressive strength of 0.1 MPa or more and 2.2 MPa or less include, for example, Techpolymer AFX-8 (Sekisui Plastics) Kogyo Co., Ltd.).

  The average particle diameter of the crosslinked (meth) acrylic ester resin particles is not particularly limited. However, if the average particle diameter is excessively large compared with the thickness of the coating layer 4, the surface irregularities of the coating layer 4 become rough, and the toner particles are on the surface. It tends to remain in the recess. On the other hand, when the average particle size is excessively small, no convex portion is 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 remaining toner particles in the coating layer 4, the average particle diameter of the crosslinked (meth) acrylate resin particles is equal to the thickness of the coating layer 4. It is preferable to make it. Specifically, the average particle diameter of the crosslinked (meth) acrylic ester resin particles is preferably 1 μm or more and 15 μm or less. More preferably, they are 2 micrometers or more and 10 micrometers or less.

Average particle diameter of crosslinked (meth) acrylate resin particles The average particle diameter is a value obtained by the following volume average diameter measurement method.
[Method for measuring volume average diameter of resin particles]
The volume average diameter of resin particles (arithmetic average diameter according to the volume-based particle size distribution) is measured by Coulter Multisizer II (Beckman Coulter, Inc.) by the following method. In this measurement, calibration is performed using a 50 μm aperture according to Reference MANUAL FOR THE COULTER MULTISIZER (1987) issued by Coulter Electronics Limited.
Specifically, 0.1 g of resin particles in 10 ml of 0.1 wt% nonionic surfactant was mixed with a touch mixer (“TOUCMIXER MT-31” manufactured by Yamato Kagaku Co., Ltd.) and an ultrasonic washer (manufactured by Vervo Coolia “ ULTRASONIC CLEANER VS-150]) to obtain a dispersion, and then in a beaker filled with ISOTON (registered trademark) II (measurement electrolyte manufactured by Beckman Coulter, Inc.) attached to the Coulter Multisizer II body The dispersion is dripped with a dropper with gentle stirring, and the concentration meter reading on the Coulter Multisizer II main body is adjusted to about 10% .Next, the aperture size (diameter) is adjusted to the Coulter Multisizer II main body. 50 μm, Current (aperture electrode) 800 μA, Gain (Ga In) 4 and Polarity (polarity of internal electrode) are input as +, and measurement is performed manually (manual mode). When the measurement of the resin particles is completed, the measurement is terminated, and 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) acrylate resin particles is not particularly limited, and the plastic deformation of the coating layer 4 can be further suppressed as the content increases. However, when the content increases, the density of the crosslinked acrylic resin particles distributed in the coating layer 4 increases, and the surface irregularities of the coating layer 4 may become rough. In this case, the toner particles are likely to remain on the surface of the coating layer 4 and the charging performance of the developing roller is degraded. Therefore, from the viewpoint of suppressing the plastic deformation of the coating layer 4 and maintaining an appropriate surface roughness so that the toner particles do not remain, the content of the crosslinked (meth) acrylate resin particles is 100 parts by mass of the urethane adjusting component. It is preferable that they are 5 mass parts or more and 50 mass parts or less with respect to. More preferably, they are 8 mass parts or more and 40 mass parts or less with respect to 100 mass parts of urethane adjustment components.

(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, similarly to the crosslinked (meth) acrylic ester resin particles. The inorganic fine particles are not limited as long as they are inorganic fine particles containing at least one element selected from silicon, titanium, and aluminum. Specific examples include silica, titanium oxide, aluminum oxide, and hydrotalcite. Silica is more preferable from the viewpoint that the slip angle is set to 10 ° or more and 40 ° or less and the developer is easily carried.
Further, these inorganic fine particles may be subjected to a surface treatment such as hydrophobization or hydrophilization as necessary. In particular, silica is more preferable because it is easy to surface-treat and can easily control the affinity with the crosslinked (meth) acrylate resin particles. One kind or two or more kinds of these inorganic fine particles may be used.

  The average particle diameter 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 favorably supporting the developer.

  The inorganic fine particles may be dispersed alone in the urethane resin, or may be attached so as to cover at least part of the periphery of the crosslinked (meth) acrylate resin particles. When adhering so as to cover at least a part of the periphery of the crosslinked (meth) acrylate resin particles, the average particle size of the inorganic fine particles is excellent in the covering property to the crosslinked (meth) acrylate resin particles. Therefore, the thickness is preferably 5 nm or more and 200 nm or less. Furthermore, since it can be effectively coated with a small amount of addition, it is more preferably 5 nm or more and 50 nm or less. 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. In addition, let the average particle diameter of an inorganic fine particle also be the value measured by the measuring method of the volume average diameter of the said resin particle.

  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, it is possible to improve the slipperiness of the surface of the coating layer 4 and to carry the developer well and transport it to the photoreceptor. Moreover, by setting it as 10 mass parts or less, dispersion | distribution of particle | grains can be improved, the uniformity of the surface state of a coating layer can be maintained, and filming can be suppressed favorably. 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 conductivity-imparting agent, desired conductivity performance, and the like. In addition, 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 those described 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 solution is preferably a solvent that can dissolve 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, in particular, 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 as the developing roller 1 are adjusted. Thus, the developing performance of the developing roller 1 as the developing roller can be adjusted favorably.

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

<Developing apparatus and image forming apparatus>
The developing roller according to the present invention can be suitably used as a developer carrier in a developing device 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 device and an image forming apparatus provided with the developing roller of the present invention will be described with reference to FIG.

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

  The developing 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 roller is mounted as developer carriers 23 </ b> B, 23 </ b> C, 23 </ b> M, and 23 </ b> Y. Specifically, the developing device 20B includes a casing 21B that accommodates a one-component non-magnetic developer 22B, a developer supply roller 25B that conveys the developer 22B to the developer carrier 23B, and an image of the developer 22B. A developer carrier 23B to be supplied to the carrier 11B and a developer amount adjusting means 24B for adjusting the thickness of the developer 22B, such as a blade, are provided. In the developing device 20B, as shown in FIG. 2, the developer amount adjusting means 24B is in contact with or in pressure contact with the outer peripheral surface of the developer carrier 23B. 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. The same elements are denoted by the same reference numerals and symbols C, M, or Y indicating the respective units, and the description thereof is omitted. .

  In the image forming apparatus 10, the developer carrier 23B of the developing device 20B is disposed such that the surface thereof is in contact with or pressure contact with 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 are in contact with or pressed against the surfaces of the image carriers 11C, 11M, and 11Y. . In other words, the image forming apparatus 10 is a “contact image forming apparatus”.

  The fixing unit 30 is disposed on the downstream side of the developing unit Y. The fixing unit 30 includes a fixing roller 31, an endless belt support roller 33 disposed in the vicinity of the fixing roller 31, a fixing roller 31, and an endless belt in a housing 34 having an opening 35 through which the recording medium 16 passes. An endless belt 36 wound around a support roller 33 and a pressure roller 32 disposed opposite to the fixing roller 31 are provided, and the fixing roller 31 and the pressure roller 32 are in contact with or pressed against each other via the endless belt 36. Thus, the pressure heat fixing device is rotatably supported. At the bottom of the image forming apparatus 10, a cassette 41 that houses the recording body 16 is installed. The transfer conveyance belt 6 is wound around a plurality of support rollers 42.

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

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

  The developing device 20 includes the developing roller 1 and is excellent in developer transportability and can suppress the occurrence of toner filming, thereby contributing to the formation of a high-density and high-quality image over a long period of time. Further, this image forming apparatus can form a high-density and high-quality image over a long period of time.

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

  The image forming apparatus is an electrophotographic image forming apparatus. However, in the present invention, the image forming apparatus is not limited to the electrophotographic system, and may be, for example, an electrostatic image forming apparatus. . Further, the image forming apparatus in which the developing roller of the present invention is disposed is not limited to a tandem color image forming apparatus in which a plurality of image carriers including developing units of respective colors are arranged in series on a transfer conveyance belt. A monochromatic image forming apparatus having a single developing unit, a four-cycle color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier onto an endless belt, and the like may be used. The developer used in the image forming apparatus is a one-component non-magnetic developer. However, in the present invention, a one-component magnetic developer or a two-component non-magnetic developer may be used. Also, a two-component magnetic developer may be used.

  The image forming apparatus 10 is a contact type image forming apparatus that is disposed in contact with 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 type image forming apparatus that is arranged with a gap so that the surface of the developer carrying member does not contact the surface of the image carrying member.

  As mentioned above, although this invention was demonstrated using embodiment, it cannot be overemphasized that the technical scope of this invention is not limited to the range of the invention as described in said embodiment, A various change or It will be apparent to those skilled in the art that improvements can be made. In addition, it is apparent from the scope of the claims that the invention to which such changes or improvements are added 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. In addition, this invention is not limited to the Example shown below at all.

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

Next, a silicone rubber composition for forming an elastic layer was prepared as follows. That is, 100 parts by mass of dimethylpolysiloxane (degree of polymerization: 300) blocked at both ends with dimethylvinylsiloxy groups, and a hydrophobized fumed silica having a BET specific surface area of 110 m ² / g (trade name “R-972” ”, 1 part by mass of Nippon Aerosil Co., Ltd.), 40 parts by mass of diatomaceous earth (trade name“ Oplite W-3005S ”, manufactured by Chuo Silica Co., Ltd.) having an average particle size of 6 μm and a bulk density of 0.25 g / cm ³ , 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 once through three rolls. This was returned again to the planetary mixer, and 2.1 parts by mass of methyl hydrogen polysiloxane having a Si—H group at both ends and side chains (polymerization degree 17, Si—H amount 0.0060 mol / g), 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 and degassed for 30 minutes to prepare an addition-curable liquid conductive silicone rubber composition.

  An elastic body made of a rubber material was molded on the outer peripheral surface of the shaft body of the prepared addition-curable liquid conductive silicone rubber composition by injection molding using a mold. In the 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 having an outer diameter of 16 mm.

  Subsequently, the 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 Chemical Industry Co., Ltd.), small diameter silica (average) 4 parts by mass, particle size 4.4 μm, trade name “ACEMATT OK-607”, manufactured by Evonik Degussa Co., Ltd.), 10% by mass of crosslinked acrylate resin particles having a restoration rate of 33%, 10% compression strength of 0.4 MPa, and conductivity As an imparting agent, 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 were mixed to obtain a resin composition.

  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. Thus, the developing roller provided with the shaft body, the elastic layer, and the 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, 52 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 Chemical Industry Co., Ltd.), small diameter silica (average particle diameter) 4.4 μm, trade name “ACEMATT OK-607”, manufactured by Evonik Degussa Co., Ltd.) 4 parts by mass, restoration rate 33%, 10% compression strength 0.4 MPa cross-linked acrylate resin particles 20 parts by mass, carbon black (product) The name “Denka Black HS-100” (manufactured by Denka Co., Ltd.) 3 parts by mass and 30 parts by mass of thinner were mixed to obtain a resin composition.

[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, 52 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 Chemical Industry Co., Ltd.), small diameter silica (average particle diameter) 4.4 μm, trade name “ACEMATT OK-607”, manufactured by Evonik Degussa Co., Ltd., 4 parts by mass, restoration rate 20%, 10% compression strength 0.4 MPa, crosslinked acrylate resin particles (trade name “Techpolymer AFX- 8, 10 parts by mass of Sekisui Plastics Industrial 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 are mixed to obtain 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, 52 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 Chemical Industry Co., Ltd.), small diameter silica (average particle diameter) 4.4 μm, trade name “ACEMATT OK-607”, 4 parts by mass of Evonik Degussa Co., Ltd., carbon black (trade name “Denka Black HS-100”, produced by Denka Co., Ltd.) 3 parts by mass, and thinner 30 masses 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 Chemical Industry Co., Ltd.), recovery rate 33%, 10 17 parts by mass of crosslinked acrylic ester resin particles having a% compressive 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 are 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, 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 Chemical Industry Co., Ltd.), 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 were 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, 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 Chemical Industry Co., Ltd.), recovery rate 33%, 10 17 parts by mass of crosslinked acrylate resin particles having a% compressive 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 Co., Ltd.) was prepared, and the image forming apparatus was obtained by replacing the developing roller of the image forming apparatus with the developing roller produced in the examples and comparative examples. With respect to the obtained image forming apparatus, filming evaluation, print density evaluation, image uniformity evaluation, and storage stability were performed by the following methods.

<Slip angle>
A base with a PET (polyethylene terephthalate) film is placed horizontally (at an angle of 0 ° with the horizontal plane), and the longitudinal direction of the base and the axial direction of the developing roller are parallel to each other on the base. The developing rollers of Examples and Comparative Examples were placed. With the one end in the longitudinal direction of the base fixed, the other end is raised to gradually tilt the base, and the horizontal surface of the base when the developing roller starts to slide toward the one end The angle formed by was defined as the slip angle.

<Filming evaluation>
Using the image forming apparatus equipped with the developed developing roller, the film weight is measured after sucking the developer adhering to the surface of the developing roller after printing 10,000 sheets under the conditions of a temperature of 23 ° C. and a humidity of 55% RH. The mass transferred to the jig was measured. About filming evaluation, it evaluated by the following reference | standard by the mass of the transferred developer. In this test, the filming amount is acceptable 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 a temperature of 23 ° C. and a humidity of 55% RH, a temperature of 30 ° C. and a humidity of 80% RH, a room temperature of 10 ° C. and a humidity of 20% RH, respectively, manufactured by X-Rite. The print density of the solid image was measured using a 508 spectral densitometer. Specifically, 1.4 or more was set as A, 1.2 or more and less than 1.4 was set as B, and less than 1.2 was set as C.

<Evaluation of image uniformity>
A solid image is printed under conditions of a temperature of 23 ° C. and a humidity of 55% RH, a temperature of 30 ° C. and a humidity of 80% RH, a temperature of 10 ° C. and a humidity of 20% RH, and the print density of the first sheet. And the print density of the 2000th sheet were compared. Specifically, the density step ratio between the initial print formation portion and the final print formation portion of solid print is A within 1.1, B is within 1.2, and B is greater than 1.2. C.

<Evaluation of preservability>
The developing roller was replaced with a toner cartridge, which was stored for 1 month at a temperature of 50 ° C. and a humidity of 65% RH. After taking out, the sample was left at room temperature of a temperature of 23 ° C. and a humidity of 55% RH for 2 hours, and a printing test was performed. The presence or absence of lateral streaks after printing 20 sheets was confirmed, and after printing 20 sheets, A was shown where no lateral streaks were observed, B was the one where the horizontal streaks were very thin, and C was the one where the lateral streaks could be confirmed.

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 part by mass.

As shown in Table 1, in Examples using a developing roller having a coating layer containing crosslinked (meth) acrylate resin particles and inorganic fine particles, all of filming, print density, image uniformity, and storage stability , B or higher.
On the other hand, the comparative example 1 which does not contain 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.

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Shaft body 3 Elastic layer 4 Cover layer 6 Transfer conveyance belt 10 Image forming apparatus 11B, 11C, 11M, 11Y Image carrier 12B, 12C, 12M, 12Y Charging means 13B, 13C, 13M, 13Y Exposure means 14B, 14C, 14M, 14Y Transfer means 15B, 15C, 15M, 15Y Cleaning means 16 Recording medium 20B, 20C, 20M, 20Y Developing device 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 Pressure roller 33 Endless belt support roller 35 Opening 36 Endless Belt 41 Cassette 42 Support B La B, C, M, Y development units

Claims (8)

A developing roller having a shaft, an elastic layer provided on the outer periphery of the shaft, 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. A developing roller containing particles and inorganic fine particles.   The developing roller according to claim 1, wherein the crosslinked (meth) acrylate 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, wherein the inorganic fine particles are silica fine particles, and the average particle size of the silica fine particles is 10 nm or more and 5 μm or less.   4. The developing roller according to claim 1, wherein an average particle diameter of the crosslinked (meth) acrylic ester resin particles is 1 μm or more and 15 μm or less. 5.   The developing roller according to claim 1, wherein a sliding angle of the surface is 10 ° or more and 40 ° or less.   The developing roller according to claim 1, wherein the conductivity imparting agent is at least one selected from a conductive agent having an electron conduction mechanism, a conductive agent having an ionic conduction mechanism, and conductive composite particles.   A developing device comprising the developing roller according to claim 1.   An image forming apparatus comprising the developing roller according to claim 1.