JP2020060749A - Developing roller, developing device, and image forming apparatus - Google Patents

Abstract

To provide a developing roller that satisfactorily prevents the occurrence of filming and is excellent in durable printing performance, a developing device, and an image forming apparatus.SOLUTION: A developing roller 1 comprises: an elastic layer 3 that is formed on an outer peripheral surface of a shaft body 2; and a coating layer 4 that is formed on an outer peripheral surface of the elastic layer 3. In the coating layer 4, the contact angle of n-hexadecane before printing is 50° or more and 80° or less, and the contact angle of n-hexadecane after 50k-A4 sheet durable printing is 20° or more.SELECTED DRAWING: Figure 1

Description

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

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

  When the developing roller is used for a long period of time, the developer may adhere to its surface (referred to as "filming"). Such filming is, for example, because the developer is deformed or destroyed by the sliding stress of the blade or the like that comes into pressure contact with the developing roller when the developer is charged or adhered, and further, the development by frictional heat with the blade or the like is performed. It is considered to be caused by the melting of the agent. There is a demand for a developing roller in which the occurrence of filming is suppressed as much as possible in the developing roller, and thereby the durable printing performance is stabilized.

  For example, Patent Document 1 describes a conductive roller containing an ionic liquid, in which a developer is hard to adhere to the surface for a long time. Further, Patent Document 2 discloses a reactive fluorine-containing copolymer useful as a surface modifier for imparting anti-fingerprint property and surface smoothness to the surface of resins, films, fibers and the like. Further, in Patent Documents 3 and 4, the surface layer is used in an electrophotographic image forming apparatus, which is made of a resin containing an acrylic skeleton and a resin containing a modified silicone compound having a polyether group and a hydroxyl group in one molecule. Intermediate transfer members are disclosed.

JP, 2011-221442, A JP, 2015-120852, A JP, 2005-18227, A JP, 2016-206643, A

However, the developing roller or the intermediate transfer member described in the above patent documents cannot suppress the occurrence of filming to the extent that the performance of the image forming apparatus required in recent years can be sufficiently satisfied, and are not satisfactory in the durable printing performance. It was
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 occurrence of filming is favorably suppressed and durability printing performance is excellent.

A developing roller of the present invention is a developing roller including an elastic layer formed on an outer peripheral surface of a shaft body and a coating layer formed on an outer peripheral surface of the elastic layer,
The coating layer is a developing roller in which the contact angle of n-hexadecane before printing is 50 ° or more and 80 ° or less, and the contact angle of n-hexadecane after durable printing of 50 k sheets of A4 paper is 20 ° or more.
The contact angle of n-hexadecane means the value measured by the measuring method described in the examples below.

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

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

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

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

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

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

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

[Development roller]
FIG. 1 is a schematic perspective view showing an embodiment of the developing roller of the present invention.
As shown in FIG. 1, the developing roller 1 of the present invention is a developing roller including an elastic layer 3 formed on the outer peripheral surface of a shaft body 2 and a coating layer 4 formed on the outer peripheral surface of the elastic layer 3. In the coating layer 4, the contact angle of n-hexadecane before printing is 50 ° or more and 80 ° or less, and the contact angle after durable printing of 50 k sheets of A4 paper is 20 ° or more.
The configuration of the developing roller 1 of the present invention will be described below.

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

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

  The shaft 2 preferably has a rod shape, a tubular shape, or the like, for example. 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 polygonal shape. The outer peripheral surface of the shaft body 2 may be subjected to treatments such as cleaning treatment, degreasing treatment, and primer treatment in order to improve the adhesiveness 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 print target is an A4 size, the axial length of the shaft body 2 is preferably 250 mm or more and 320 mm or less, and more preferably 260 mm or more and 310 mm or less. The diameter of the shaft body 2 (diameter of the circumscribing circle) is not particularly limited, and may be appropriately adjusted according to the form of the image forming apparatus to be installed. For example, the outer diameter (diameter of the circumscribing circle) of the shaft body 2 is preferably 4 mm or more and 14 mm or less, and more preferably 6 mm or more and 10 mm or less.

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

Examples of the rubber in the rubber composition include silicone or silicone-modified rubber, nitrile rubber, ethylene propylene rubber (including ethylene propylene diene rubber), styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene. Examples thereof include rubber, butyl rubber, epichlorohydrin rubber, urethane rubber and fluororubber. Silicone or silicone modified rubber or urethane rubber is preferable, and the silicone or silicone modified rubber can reduce compression set and is excellent in flexibility in a low temperature environment, and further has heat resistance and charging property. It is particularly preferable in that it has excellent properties. Examples of the silicone rubber include crosslinked products of organopolysiloxane such as dimethylpolysiloxane and diphenylpolysiloxane.
Examples of the silicone rubber composition include addition-curable millable conductive silicone rubber compositions and addition-curable liquid conductive silicone rubber compositions.

-Addition-curable millable conductive silicone rubber composition-
The addition-curable millable conductive silicone rubber composition contains, for example, (A) an organopolysiloxane represented by the following average composition formula (1), (B) a filler, and (C) a conductivity-imparting agent. You may
R ¹ _n SiO _{(4-n) / 2} (1)
In the formula (1), n represents a positive number of 1.95 or more and 2.05 or less. R ¹ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. The number of carbon atoms 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 groups, phenyl groups and tolyl groups, and aralkyl groups such as β-phenylpropyl groups. In addition, R ¹ may be a group in which some or all of the hydrogen atoms of these hydrocarbon groups are substituted with a substituent. The substituent may be, for example, a halogen atom, a cyano group or the like. Examples of the hydrocarbon group having a substituent include a chloromethyl group, a trifluoropropyl group, a cyanoethyl group and the like.

  (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, and a trivinylsilyl group. It is preferably blocked with a triaralkylsilyl group or the like.

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

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

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

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

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

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

  Examples of the conductivity-imparting agent (C) include carbon, metal, metal oxide, metal compound, conductive polymer, and ionic liquid. The amount of the conductivity-imparting agent (C) blended is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, relative to 100 parts by mass of the (A) organopolysiloxane. Further, the blending amount of the conductivity-imparting agent (C) is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, relative to 100 parts by mass of the (A) organopolysiloxane.

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

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

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

As the organopolysiloxane (D), compounds represented by the following average composition formula (2) are preferable.
R ⁴ _a SiO _{(4-a) / 2} (2)
In the formula (2), a represents a positive number of 1.5 or more and 2.8 or less, preferably 1.8 or more and 2.5 or less, and more preferably 1.95 or more and 2.05 or less. R ⁴ represents a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. However, at least two of R ^{4 in} one molecule are alkenyl groups. The number of carbon atoms 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 above as R ¹ . Further, it is preferable that at least two of R ^{4 s in} one molecule are alkenyl groups and the other R ^{4 s} are alkyl groups. The alkenyl group is preferably a vinyl group, and the alkyl group is preferably a methyl group. In addition, 90% or more of R ⁴ may be an alkyl group (preferably a methyl group). The content of the alkenyl group in the (D) organopolysiloxane is preferably 1.0 × 10 ⁻⁶ mol / g or more and 5.0 × 10 ⁻³ mol / g or less, and 5.0 × 10 ^−. It is more preferably ⁶ mol / g or more and 1.0 × 10 ⁻³ mol / g or less.

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

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

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

  In the organohydrogenpolysiloxane (E), 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 or less. It is more preferably g or less.

Examples of the (E) organohydrogenpolysiloxane include trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both terminals, trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both terminals, and dimethylhydrogensiloxy group-blocked at both terminals. 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 _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.

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

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

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

(F) the bulk density of the filler is preferably at 0.1 g / cm ³ or more 0.5 g / cm ³ or less, and more preferably less 0.15 g / cm ³ or more 0.45 g / cm ³ . (F) By adjusting the bulk density of the filler within the above range, the compression set can be further reduced, the change in volume resistivity with time can be further suppressed, and the elastic layer 3 having further excellent durability can be obtained. 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 K6223.

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

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

  Examples of the conductivity-imparting agent (G) include carbon, metal, metal oxide, metal compound, conductive polymer, and ionic liquid. The amount of the (G) conductivity-imparting agent added is preferably 0.5 parts by mass or more and 15 parts by mass or less, and preferably 1 part by mass or more and 10 parts by mass or less, based on 100 parts by mass of the (D) organopolysiloxane. More preferably.

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

  The compounding amount of the (H) addition reaction catalyst may be a catalytic amount. For example, the 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 the (D) organopolysiloxane and the (E) organohydrogenpolysiloxane. The amount is preferably 1 mass ppm or more and 500 mass ppm or less.

  The elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 by performing heat curing and molding simultaneously or continuously by a known molding method. The method for curing the rubber composition may be any method capable of applying heat necessary for curing the rubber composition, and the method for molding the elastic layer 3 is not particularly limited, such as continuous vulcanization by extrusion molding, press molding, or molding by injection. It is not something that will be done. For example, when the rubber composition is an addition curable millable conductive silicone rubber composition, for example, extrusion molding can be selected, and the rubber composition is an addition curable liquid conductive silicone rubber composition. In this case, for example, a molding method using a mold can be selected.

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

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

  Specific examples of the additive include dispersants such as low molecular weight siloxane ester, polyether modified silicone oil, silanol and phenylsilanediol. Also, heat resistance improvers such as iron octylate, iron oxide, and cerium oxide can be mentioned. Further, various carbon functional silanes, various olefin-based elastomers, etc. for improving the adhesiveness, molding processability and the like may be used. Further, a halogen compound or the like which 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 thickness of the elastic layer 3 is not particularly limited, and is preferably 0.1 mm or more and 6 mm or less, more preferably 1 mm or more and 4 mm or less. In addition, the thickness in this specification indicates the thickness in the direction perpendicular to the axial direction of the developing roller 1.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

In the general formula (c-2), examples of the divalent group represented by R ⁴ and having 2 to 50 carbon atoms include the divalent groups exemplified as the above R ² . The divalent group preferably has 2 to 10 carbon atoms.

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

Particularly preferable R ⁴ includes the following groups.

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

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

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

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

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

  Particularly preferred as the (meth) acrylate compound represented by the general formula (c-3) is benzyl methacrylate.

  The compound represented by the general formula (c-3) can be produced by a known method, or can be obtained as a commercial product.

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

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

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

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

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

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

  The content of the (meth) acrylate copolymer containing (c) a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom in the resin composition for the coating layer is (a) a polyol, (b) an isocyanate, Further, it is preferably 0.1 to 5 parts by mass, and more preferably 0.3 to 3 parts by mass with respect to 100 parts by mass in total of (c) (meth) acrylate copolymer.

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

The surface roughness (Rz) of the coating layer 4 is, for example, preferably 1 μm or more and 20 μm or less, and more preferably 1 μm or more and 15 μm or less.
The surface roughness (Ra) of the coating layer 4 is, for example, preferably 0.3 μm or more and 2.0 μm or less, and more preferably 0.4 μm or more and 1.5 μm or less.
In addition, in this specification, the surface roughness (Rz) of the coating layer 4 indicates a ten-point average roughness measured by a method specified in JIS-1994. The surface roughness of the coating layer 4 can be easily adjusted by, for example, the type and amount of the surface roughness material to be mixed.

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

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

(E) Ionic Conductive Material Examples of the ionic conductive material include sodium perchlorate, lithium perchlorate, calcium perchlorate, lithium chloride, lithium bis (trifluoromethanesulfonyl) imide, and potassium bis (trifluoromethanesulfonyl) imide. , Potassium N, N-bis (nonafluorobutanesulfonyl) imide, and other inorganic ionic conductive substances. The content of the resin composition for the ion conductive material coating layer is preferably 0.01 to 5 parts by mass, and 0.1 to 3 parts by mass, relative to 100 parts by mass of the resin composition for the coating layer. Is more preferable.

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

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

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

The coating of the resin composition for the coating layer includes, for example, a coating method of applying a coating liquid of the resin composition for the coating layer, a dipping method of immersing an elastic layer or the like in the coating liquid, an elastic layer of the coating liquid, etc. It is carried out by a known coating method such as a spray coating method of spraying on. The coating layer resin composition may be directly applied, or the coating layer resin composition may be applied to the coating layer resin composition such as alcohols such as methanol and ethanol, aromatic solvents such as xylene and toluene, ethyl acetate and butyl acetate. You may apply the coating liquid which added volatile solvents, such as ester solvent of this, or water. The method for curing the coating layer resin composition thus coated may be any method capable of applying heat necessary for curing the coating layer resin composition, for example, a coating layer resin composition. Examples of the method include a method of heating an elastic layer or the like coated with No. 2 with a heater, a method of leaving the elastic layer or the like coated with the resin composition under high humidity. The heating temperature when heat-curing the resin composition for a coating layer is, for example, preferably 100 ° C. or higher and 200 ° C. or lower, particularly preferably 120 ° C. or higher and 160 ° C. or lower, and the heating time is 10 minutes or longer. It is preferably 120 minutes or less, and more preferably 30 minutes or more and 60 minutes or less.
In the coating layer thus formed, the precursor forming the resin and the ionic conductive material may react to be integrated with each other, or may form a composite. Further, the ion conductive material may be dispersed in the resin without reacting with the precursor forming the resin.

The coating layer in the developing roller of the present invention has a contact angle of n-hexadecane before printing of 50 ° or more and 80 ° or less, and an n-hexadecane contact angle of 20 ° or more after durable printing of 50 k sheets of A4 paper. This indicates that the developing roller of the present invention maintains the n-hexadecane contact angle of the coating layer at 20 ° or more even after long-term use. That is, since the surface of the coating layer maintains sufficient oil repellency for obtaining a high-quality image at the beginning of manufacturing, filming is less likely to occur and a high-quality image can be obtained.
The contact angle of n-hexadecane after durable printing of 50 k sheets of A4 paper is more preferably 24 ° or more.

  The coating layer in the present invention is formed by heating and curing the resin composition for a coating layer, and the content of fluorine atoms in the resin composition for a coating layer is preferably less than 5% by mass. The content is more preferably 0.01% by mass or more and 4.5% by mass or less, still more preferably 0.1% by mass or more and 4% by mass or less, and most preferably 0.1% by mass or more and 3% by mass or less. When the content is 0.1% by mass or more, the elemental fluorine is unevenly distributed on the surface of the coating layer, and the oil repellency of the surface of the coating layer is improved, so that filming can be favorably prevented. If a large amount of a compound containing a fluorine atom (for example, a fluorine-based surfactant or the like) is added to improve oil repellency, the conductivity decreases, so the content of the conductive filler must be increased. When the content of the conductive filler is increased, the resin becomes hard, so that the abrasion resistance of the coating layer is reduced, the durability printing performance is reduced, and the cost is increased. Further, when the conductivity-imparting agent is an ion-conducting agent, it is compounded in a large amount, which causes problems of cost increase and bleeding. However, by setting the content of the fluorine atom as described above, it is not necessary to increase the conductive filler and the coating layer can be softened, so that the durability of the coating layer is improved and the durable printing performance is excellent. The content of fluorine atoms in the resin composition for the coating layer is a value measured by the measuring method described in Examples below.

The coating layer includes (a) a polyol, (b) an isocyanate, (c) a hydroxyl group and a (meth) acrylate copolymer containing 1% by mass or more and 10% by mass or less of a fluorine atom, (d) a surface roughness material, And (e) the coating layer resin composition containing the ion conductive material can be formed by heating and curing.
Since the coating layer produced by the resin composition for a coating layer in the present invention contains a (meth) acrylate copolymer containing a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom, the fluorine atom is a resin. Is unevenly distributed in the vicinity of the surface of the coating layer in a state of being taken in as a part of. Therefore, in the coating layer of the present invention, since fluorine atoms are present on the surface for a long period of time, the developer melted by the operation of the image forming apparatus hardly adheres to the coating layer and the amount of the developer fixed to the coating layer is significantly increased. It is possible to reduce the number and provide a high-quality image.

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

  As the primer layer, those usually used as a primer layer of a developing roller can be used. For example, a material whose resistance value becomes electrostatically conductive or an adhesive is added to an existing primer. By using a metal-based primer having electrostatic conductivity, the developing performance of the developing roller 1 can be favorably maintained.

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

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

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

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

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

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

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

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

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

  The image forming apparatus is an electrophotographic image forming apparatus, but in the present invention, the image forming apparatus is not limited to the electrophotographic method and may be, for example, an electrostatic image forming apparatus. . Further, the image forming apparatus provided with the developing roller of the present invention is not limited to a tandem type color image forming apparatus in which a plurality of image carriers having developing units of respective colors are arranged in series on a transfer / conveying belt. A monochrome image forming apparatus having a single developing unit, a four-cycle type color image forming apparatus in which primary transfer of a developer image carried on an image carrier to an endless belt is sequentially repeated may be used. 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. A two-component magnetic developer may also be used.

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

  Although the present invention has been described above by using the 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, and various modifications or changes are made to the above embodiments. It will be apparent to those skilled in the art that modifications can be made. It is also apparent from the scope of the claims that the invention added with such changes or improvements can be included in the technical scope of the present invention.

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

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

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

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

(Formation of coating layer)
Then, a resin composition for forming the coating layer was prepared as follows.
In addition, in the resin composition for a coating layer, the total content of (a) polyol, (b) isocyanate, (c) hydroxyl group and (meth) acrylate copolymer containing 1 mass% to 10 mass% of fluorine atoms. Table 1 shows the contents (parts by mass) of the united material, (d) surface roughness material, and (e) ion conductive material.

-Resin layer resin composition-
(A) Polyester polyol (mixing molar ratio of 1,6-hexanediol and adipic acid [COOH / OH] = 12/13, the number average molecular weight measured by the above measuring method is in the range of 1000 to 8000. 28 parts by mass (b) Isocyanate (hexamethylene diisocyanate) 14 parts by mass (c) 0.5 parts by mass of a (meth) acrylate copolymer containing a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom. (D) Surface roughness material (silica) 3 parts by mass (e) Ion conductive material (potassium bis (trifluoromethanesulfonyl) imide, trade name "EF-N112", manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.)
0.2 parts by mass The molar ratio [NCO / OH] of polyisocyanate and polyester polyol was 1.1 / 1.

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

[Example 2]
(A) Polyester polyol was changed to acrylic polyol (trade name "UH-2041", manufactured by Toagosei Co., Ltd.) to make the compounding amount 20 parts by mass, and (b) Isocyanate was changed to an adduct system, and the compounding amount was 25 parts by mass. A resin composition for a coating layer was prepared and a coating layer was formed in the same manner as in Example 1 except that.

[Example 3]
Example 1 except that (a) the polyester polyol was changed to polycarbonate diol (trade name "T650J", manufactured by Asahi Kasei Co., Ltd.) and the compounding amount was 20 parts by mass, and (b) the isocyanate compounding amount was 19 parts by mass. The coating layer resin composition was prepared in the same manner as in 1. to form a coating layer.

[Example 4]
(C) For the coating layer as in Example 2 except that the blending amount of the (meth) acrylate copolymer containing a hydroxyl group and 1 to 10 mass% of fluorine atoms was 0.25 parts by mass. The resin composition was adjusted to form a coating layer.

[Example 5]
(C) A resin composition for a coating layer as in Example 2 except that the compounding amount of the (meth) acrylate copolymer containing a hydroxyl group and 1% by mass or more and 10% by mass or less of a fluorine atom was 1 part by mass. The thing was prepared and the coating layer was formed.

[Example 6]
(A) A resin composition for a coating layer was prepared in the same manner as in Example 2 except that 16 parts by mass of the acrylic polyol and 4 parts by mass of the acrylic copolymer fluororesin were further added to form the coating layer.

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

[Comparative Example 2]
Acrylic polyol is mixed in an amount of 16 parts by mass in place of (a) polyester polyol, (b) isocyanate is changed to an adduct system, and the compounding amount is 25 parts by mass, and (c) hydroxyl group and 1% by mass or more and 10% by mass or less. Example 1 except that 4 parts by mass of an acrylic silicone-based graft polymer (trade name "US-270", manufactured by Toagosei Co., Ltd.) was blended in place of the (meth) acrylate copolymer containing a fluorine atom. Similarly, a resin composition for a coating layer was prepared to form a coating layer.

[Comparative Example 3]
(A) Acrylic polyol was blended in an amount of 15 parts by mass in place of the polyester polyol, (b) Isocyanate was replaced by an adduct system, and the blending amount was 25 parts by mass, and (c) a hydroxyl group and 1 mass% or more and 10 mass% or less. The same as Example 1 except that 5 parts by mass of an acrylic copolymerized fluoropolyol (trade name "TR-101", DIC Corporation) was blended in place of the (meth) acrylate copolymer containing a fluorine atom. A resin composition for a coating layer was prepared, and a coating layer was formed.

[Evaluation]

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

(Method of measuring contact angle of n-hexadecane before printing)
The contact angle of n-hexadecane was measured using a contact angle meter (trade name "portable contact angle meter PCA-1", manufactured by Kyowa Interface Science Co., Ltd.). The device is set so as to be parallel to the developing roller, and a droplet of n-hexadecane is dropped as a test solution on the sample so that the droplet diameter becomes 1 μm. For the measurement of the contact angle, the angle formed by the contact point between the sample and the liquid droplet and the vertex of the liquid droplet was read and obtained after 1 second by the camera and software built in the contact angle meter.

(Measurement method of contact angle of n-hexadecane after durability printing of 50 k sheets of A4 paper)
Using an image forming apparatus (C610dn2 manufactured by Oki Data Co., Ltd.) equipped with the developed developing roller, the development roller of 50,000 sheets (25,000 sheets in double-sided printing 9 durable printing) under the conditions of temperature 23 degrees and humidity 55% RH After sucking the developer adhering to the surface and transferring the surface adhering material with Cellotape (trade name, manufactured by Nichiban), the contact angle of n-hexadecane was measured by the contact angle measuring method.

(Content of Fluorine Atom in Resin Composition for Coating Layer)
The resin composition for the coating layer is cut out, 0.01 g is burned and absorbed by the sample combustion device AQF-2100H Mitsubishi Chemical Analytech, and the absorption liquid is analyzed by ion chromatography Integrion RFIC (Thermo Fisher Scientific Co., Ltd.). , And the content of fluorine atoms was determined.

(Filming evaluation)
Using the image forming apparatus equipped with the developed developing roller, the conditions of temperature 23 ° C., humidity 55% RH, temperature 30 ° C., humidity 80% RH, temperature 10 ° C., humidity 20% RH were changed in a cycle. A predetermined print pattern was printed on 10000 sheets (double-sided printing), and the developer adhering to the surface of the developing roller after printing 3 solid images the next day was sucked, and the mass transferred to the filming weight measurement jig was measured. . Regarding the filming evaluation, the mass of the transferred developer was evaluated according to the following criteria. In this test, the filming amount is “A” when the evaluation is “A”.
-Evaluation criteria-
A: The mass of the transferred developer is 0 mg or more and less than 0.02 mg B: The mass of the transferred developer is 0.02 mg or more and less than 0.05 mg C: The mass of the transferred developer is 0.05 mg or more

(Evaluation of print density)
Temperature 23 ° C, humidity 55% RH condition, temperature 30 ° C, humidity 80% RH condition, temperature 10 ° C, humidity 20% RH condition changed cyclically to perform a predetermined print pattern 10000 sheets (double-sided printing), The next day, three solid images were printed, the solid image print density was measured using a 508 spectral densitometer manufactured by X-Rite, and evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: Print density is 1.4 or more B: Print density is 1.2 or more and less than 1.4 C: 1.0 or more and less than 1.2

(Evaluation of image uniformity)
Temperature 23 ° C, humidity 55% RH condition, temperature 30 ° C, humidity 80% RH condition, temperature 10 ° C, humidity 20% RH condition changed cyclically to perform a predetermined print pattern 10000 sheets (double-sided printing), The next day, three solid images were printed and the upper print density and the lower print density of A4 paper were compared. Specifically, the density step ratio between the upper print forming portion and the lower print forming portion of solid printing was obtained and evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: Density step ratio is within 1.1 B: Density step ratio is above 1.1 and within 1.2 C: Density step ratio is above 1.2

  The evaluation results are shown in Table 1.

  As shown in Table 1, the contact angle of n-hexadecane before printing is 50 ° or more and 80 ° or less, and the contact angle of n-hexadecane after durable printing of 50 k sheets of A4 paper is 20 ° or more. The developing roller having the coating layer is excellent in filming, print density, and image uniformity.

DESCRIPTION OF SYMBOLS 1 developing roller 2 shaft body 3 elastic layer 4 coating layer 6 transfer conveyance belt 10 image forming apparatus 11B, 11C, 11M, 11Y image carrier 12B, 12C, 12M, 12Y charging means 13B, 13C, 13M, 13Y exposing means 14B, 14C, 14M, 14Y Transfer means 15B, 15C, 15M, 15Y Cleaning means 16 Recording bodies 20B, 20C, 20M, 20Y Developing devices 21B, 21C, 21M, 21Y, 34 Housings 22B, 22C, 22M, 22Y Developer 23B, 23C, 23M, 23Y developer carrier 24B, 24C, 24M, 24Y developer amount adjusting means 25B, 25C, 25M, 25Y toner supply roller 30 fixing means 31 fixing roller 32 pressure roller 33 endless belt support roller 35 opening 36 Endless belt 41 Cassette 42 Support roll La B, C, M, Y development units

Claims (5)

A developing roller comprising an elastic layer formed on the outer peripheral surface of a shaft and a coating layer formed on the outer peripheral surface of the elastic layer,
The coating layer has a contact angle of n-hexadecane before printing of 50 ° or more and 80 ° or less and a contact angle of n-hexadecane after durable printing of 50 k sheets of A4 paper is 20 ° or more.   The developing roller according to claim 1, wherein the coating layer is formed by heating and curing the resin composition for the coating layer, and the content of fluorine atoms in the resin composition for the coating layer is less than 5% by mass.   The resin composition for a coating layer comprises (a) a polyol, (b) an isocyanate, (c) a hydroxyl group and a (meth) acrylate copolymer containing 1% by mass or more and 10% by mass or less of a fluorine atom, (d). The developing roller according to claim 2, further comprising a surface roughness material and (e) an ion conductive material.   A developing device comprising the developing roller according to claim 1.   An image forming apparatus comprising the developing roller according to claim 1.

Images