JP5435711B2 - Developing roller and image forming apparatus - Google Patents

Description

This invention relates to a developing roller and an image forming apparatus, and more particularly, more excellent the continuous printing property, developing roller to contribute to forming a desired high resolution image, and to form the desired high resolution image The present invention relates to an image forming apparatus.

  Various image forming apparatuses using an electrophotographic system are employed in laser printers, copiers, video printers, facsimiles, and multifunctional machines of these. An image forming apparatus using an electrophotographic system includes a shaft body and an elastic layer formed on an outer peripheral surface thereof, for example, a cleaning roller, a charging roller, a developing roller, a transfer roller, a pressure roller, a paper feed conveyance roller, Various rollers such as a fixing roller are provided. Specifically, as shown in FIG. 3, the tandem color image forming apparatus includes a plurality of developing units B, C, M, and Y. The developing unit B will be described as an example. A charging roller as an example of the means 12B, a developing roller as an example of the developer carrier 23B, a fixing roller 31 constituting the fixing means 30, and the like are mounted.

  Among these rollers, conductive rollers such as a charging roller, a developing roller, and a transfer roller are provided on the outer peripheral surface of the elastic layer for the purpose of improving the durability, charging characteristics (conductivity) with respect to the developer, and environmental resistance. A surface layer or a coat layer may be provided. For example, in Patent Document 1, “a semiconductive roll in which a urethane resin coating layer is provided on the surface of an elastic body, and a silane coupling agent is laminated and coated on the outermost coating layer” Is described.

  By the way, in recent image forming apparatuses, higher definition of images, higher printing speed, and / or reduction in size and weight are achieved. The conductive roller mounted on these image forming apparatuses has a small diameter corresponding to the reduction in size and weight of the image forming apparatus even if the conductive roller is rotated at a high speed to cope with the increase in printing speed in the image forming apparatus. Even so, in order to form a desired image, it is required to have even more excellent characteristics.

  Among the conductive rollers, the developing roller that conveys the developer and charges the toner to a desired charge amount easily affects the quality of the image formed when the developing roller is mounted on the image forming apparatus. In particular, when a color image is continuously printed, the developing roller may induce blurring and / or fogging on the color image, thereby greatly affecting the quality of the image. Therefore, a conductive roller as a developing roller has a high level of both a transport characteristic for transporting a desired amount of developer and a charge characteristic for charging the developer to a desired charge amount. The image is required to be excellent in characteristics that do not cause blurring and / or fogging (hereinafter sometimes referred to as continuous printing characteristics).

Japanese Patent Laid-Open No. 2003-98782

An object of the present invention is to provide a developing roller that is more excellent in continuous printing characteristics and contributes to forming a desired high-definition image.

It is another object of the present invention to provide an image forming apparatus that includes a developing roller having even more excellent continuous printing characteristics and can form a desired high-definition image.

Conventionally, materials for forming a coating layer formed on a conductive roller, and multilayering of the coating layer (see, for example, Patent Document 1) have been studied. However, the inventors of the present invention found that the reason why the continuous printing characteristic is deteriorated is that the physical developer transport amount due to the surface roughness of the developing roller and the electrical developer transport amount and the charge amount due to the charging property of the developing roller. based on the speculation that do not located in that there was no suitable range, were intensively investigated coating layer, the thickness of the coating layer which has not been considered at all until now, and the transport properties of the developing roller It was newly found that the charging characteristics are greatly affected. Specifically, the inventors have a thickness of the conductive coat layer formed on the outer peripheral surface of the elastic layer and the coat layer formed by curing the aminosilane coupling agent on the outer peripheral surface of the conductive coat layer, It has been found that the conveyance characteristics and the charging characteristics of the developing roller are greatly affected, and the above-described problems can be solved.

That is, as means for solving the above-mentioned problem,
The present invention relates to a shaft body, an elastic layer formed on the outer peripheral surface of the shaft body, a conductive coat layer formed on the outer peripheral surface of the elastic layer, and an aminosilane coupling on the outer peripheral surface of the conductive coat layer. A coating layer formed by curing the agent,
A developing roller characterized in that the thickness of the conductive coating layer (Tu: μm) and the thickness of the coating layer (Ts: μm) satisfy the following conditions (1) and (2):
(1) 15.7 ≦ Tu (μm) ≦ 22.2
(2) 6.5 ≦ (Tu / Ts) ≦ 9.3
2. The developing roller according to claim 1, wherein the thickness (Ts) of the coating layer is 1.5 μm or more and 4.5 μm or less.
Claim 3 is the developing roller according to claim 1 or 2, wherein the coat layer has a surface glossiness of ^2.5 to 5.0 at a measurement area of 4 mm2.
A fourth aspect of the present invention is an image forming apparatus including the developing roller according to any one of the first to third aspects.

The developing roller according to the present invention includes an elastic layer, a conductive coating layer, and a coating layer in this order on the outer peripheral surface of the shaft body, and the conductive coating layer and the coating layer satisfy the conditions (1) and (2). Therefore, the transport characteristics for transporting a desired amount of developer and the charging characteristics for charging the developer to a desired charge amount can be compatible at a high level, and as a result, high continuous printing characteristics are exhibited. be able to. Therefore, the developing roller according to the present invention forms a desired high-definition image when it is mounted on an image forming apparatus that has high image definition, high printing speed, and / or small and light weight. Can contribute. Therefore, according to the present invention, it is possible to provide a developing roller that is more excellent in continuous printing characteristics and contributes to forming a desired high-definition image.

The image forming apparatus according to the present invention includes the developing roller according to the present invention. Therefore, according to the present invention, an image forming apparatus capable of forming a desired high-definition image can be provided.

FIG. 1 is a perspective view showing a developing roller which is an embodiment of the developing roller of the present invention. FIG. 2 is a cross-sectional view showing a developing roller which is an embodiment of the developing roller of the present invention. FIG. 3 is a schematic view of a tandem color image forming apparatus to which a developing roller which is an embodiment of the developing roller of the present invention can be attached.

Developing roller of an embodiment of a developing roller according to the present invention, as shown in FIGS. 1 and 2, a shaft body 2, an elastic layer 3 formed on the outer circumferential surface of the shaft body 2, the elastic layer 3 The conductive coat layer 4 formed on the outer peripheral surface and the coat layer 5 formed by curing the aminosilane coupling agent on the outer peripheral surface of the conductive coat layer 4 are provided.

  As shown in FIG. 1 and FIG. 2, the shaft body 2 only needs to have good conductive characteristics, and is usually referred to as a so-called “core metal” made of iron, aluminum, stainless steel, brass, or the like. It is made a shaft body. Further, the shaft body 2 may be a shaft body that is made conductive by plating an insulating core body such as a thermoplastic resin or a thermosetting resin. Furthermore, the shaft body 2 may be a thermoplastic resin or a thermosetting resin. The shaft body may be formed of a conductive resin in which carbon black or metal powder is blended as a conductivity imparting agent. The shaft body 2 is adjusted to an appropriate diameter and axial length according to the image forming apparatus to be mounted. For example, when mounted on an image forming apparatus that is reduced in size and weight and / or increased in speed, the diameter of the shaft body 2 is preferably reduced to, for example, 4 to 10 mm.

As shown in FIGS. 1 and 2, the elastic layer 3 is formed by curing a rubber composition described later on the outer peripheral surface of the shaft body 2. The elastic layer 3 preferably has a JIS A hardness of 10 to 90. When the elastic layer 3 has a JIS A hardness of 10 to 90, for example, when the developing roller 1 is mounted on an image forming apparatus, a large nip between the developing roller 1 and a contacted body such as an image carrier. A width can be secured. In particular, when mounting the current image roller in the image forming apparatus, to ensure a large nip width between the developing roller 1 and the image bearing member, the developer to efficiently charge transport, thereby improving the development efficiency. The JIS A hardness of the elastic layer 3 can be measured according to JIS K6253.

  The thickness of the elastic layer 3 is preferably 1 mm or more, and more preferably 5 mm or more. On the other hand, the upper limit of the thickness of the elastic layer 3 is not particularly limited as long as the accuracy of the outer diameter of the elastic layer 3 is not impaired. In general, if the thickness of the elastic layer 3 is excessively increased, the production cost of the elastic layer 3 increases. Therefore, in consideration of practical production costs, the thickness of the elastic layer 3 is preferably 30 mm or less, and more preferably 20 mm or less. In particular, when the image forming apparatus is reduced in size and weight and / or increased in speed, the elastic layer 3 is preferably adjusted to a thickness of 3 to 6 mm, for example.

  The rubber composition forming the elastic layer 3 contains rubber, a conductivity imparting agent, and various additives as desired. The rubber is not particularly limited. For example, silicone or silicone-modified rubber, nitrile rubber, ethylene propylene rubber (including ethylene propylene diene rubber), styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene. Examples include rubbers such as rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, and fluororubber. Silicone or silicone-modified rubber is excellent in heat resistance and charging characteristics, and urethane rubber has tensile strength and wear resistance. It is preferable at the point which is excellent in. These rubbers may be a liquid type or a millable type, and can be appropriately selected according to the molding method of the elastic layer 3, characteristics required for the elastic layer 3, and the like.

  The conductivity-imparting agent is not particularly limited as long as it has conductivity, and examples thereof include conductive powder and ion conductive material. More specifically, examples of the conductive powder include carbons for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT in addition to conductive carbon such as ketjen black and acetylene black. In addition, metals such as titanium oxide, zinc oxide, nickel, copper, silver, germanium, and conductive polymers such as metal oxides, polyaniline, polypyrrole, polyacetylene, etc. can be mentioned. Specific examples include inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride. The conductivity-imparting agent is added in an appropriate content so as to obtain a desired volume resistivity when the elastic layer 3 is used singly or in combination of two or more. For example, the content of the conductivity-imparting agent in the rubber composition can be 2 to 80 parts by mass with respect to 100 parts by mass of the rubber.

  The rubber composition may contain various additives usually contained in various compositions in addition to the rubber and conductivity imparting agent. Examples of the various additives include a chain extender and a crosslinking agent. Auxiliary agents, catalysts, dispersants, foaming agents, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvers, flame retardant improvements Agents, acid acceptors, thermal conductivity improvers, mold release agents, solvents and the like. These various additives may be commonly used additives or may be specially used additives depending on applications.

  The rubber composition is uniformly mixed with the rubber, conductivity-imparting agent, and various additives as required, using a rubber kneader such as a two-roller, three-roller, roll mill, Banbury mixer, and dough mixer (kneader). For example, it can be obtained by kneading at normal temperature or under heating for several minutes to several hours, preferably 5 minutes to 1 hour.

  The rubber composition preferably has a viscosity of 5 to 500 Pa · s at 25 ° C., particularly preferably 10 to 200 Pa · s. The viscosity of the rubber composition can usually be adjusted by the type and / or blending amount of each component contained therein. If necessary, the viscosity can be adjusted with a solvent or the like.

  Examples of the rubber composition that is preferably used include an addition-curable millable conductive silicone rubber composition and an addition-curable liquid conductive silicone rubber composition.

The addition-curable millable conductive silicone rubber composition is (A) an organopolysiloxane represented by the following average composition formula (1), (B) a filler, and (C) other than those belonging to the component (B). The conductive material is contained. These components (A) to (C) are basically the same as the components in the “addition-curable millable conductive silicone rubber composition” described in, for example, JP-A-2008-058622.
(1) R _n SiO _{(4-n) / 2}
(In the above average composition formula (1), R may be the same or different, substituted or unsubstituted monovalent hydrocarbon group, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms. And n is a positive number of 1.95 to 2.05.)

The addition-curable liquid conductive silicone rubber composition comprises (D) an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and (E) bonded to silicon atoms in one molecule. An organohydrogenpolysiloxane containing at least two hydrogen atoms; (F) an inorganic filler having an average particle size of 1 to 30 μm and a bulk density of 0.1 to 0.5 g / cm ³ ; and (G). An addition-curable liquid conductive silicone rubber composition containing a conductivity imparting agent and (H) an addition reaction catalyst can be mentioned. These components (D) to (H) are basically the same as the components in the “addition-curable liquid conductive silicone rubber composition” described in JP-A-2008-058622, for example.

As shown in FIGS. 1 and 2, the conductive coating layer 4 is formed by curing a urethane resin composition described later on the outer peripheral surface of the elastic layer 3, and has conductivity. The conductivity of the conductive coating layer 4 is adjusted according to the elastic layer 3, the coating layer 5 described later, and the like so that the developing roller 1 has a desired conductivity. The electroconductivity of the electroconductive coating layer 4 can be adjusted with content of the electroconductivity imparting agent in a urethane resin composition, for example. The conductive coating layer 4 can prevent low molecular weight components, such as oligomers, contained in the elastic layer 3 from exuding on the outer surface of the developing roller 1.

The conductive coating layer 4 is usually formed as a thin layer, but in the present invention, it is adjusted to a layer thickness (Tu) of 15.7 to 22.2 μm (condition (1)). When the conductive coat layer 4 is adjusted to a layer thickness in the above range, that is, when the thickness of the conductive coat layer 4 satisfies the condition (1), the conductive coat formed so as to cover the elastic layer 3 The layer 4 does not significantly impair the conductivity and hardness of the elastic layer 3, and the desired conductivity and hardness when the developing roller 1 is obtained can be realized. The thickness of the conductive coating layer 4 can easily adjust the conductivity and hardness of the developing roller 1 to a desired range, and can achieve continuous printing characteristics described later at a high level. in, that it has been adjusted to 15.7~22.2 μm.

  The urethane resin composition forming the conductive coating layer 4 contains a polyurethane preparation component, a conductivity imparting agent, and various additives as required.

  The polyurethane preparation component may be any component that can form polyurethane. For example, a mixture of polyol and polyisocyanate, a prepolymer obtained by reacting polyol and polyisocyanate, and polyol and polyisocyanate are mixed. Examples thereof include at least one component selected from the group consisting of polyurethane obtained by reaction.

  The polyol in the mixture of polyol and polyisocyanate may be any of various polyols usually used in the preparation of polyurethane, and is at least one polyol selected from polyether polyol and polyester polyol. The coat layer 4 is preferable in that it is excellent in wear resistance, electrical stability, water resistance and the like. Examples of the polyether polyol include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polypropylene glycol-ethylene glycol, polytetramethylene ether glycol, copolymer polyols of tetrahydrofuran and alkylene oxide, and various modified products thereof. These mixtures etc. are mentioned. Examples of the polyester polyol include condensed polyester polyols, lactone polyester polyols, polycarbonate polyols, and mixtures thereof obtained by condensation of dicarboxylic acids such as adipic acid and polyols such as ethylene glycol. The polyether polyol and polyester polyol may be used singly or in combination of two or more, or a polyether polyol and a polyester polyol may be used in combination. The polyol is preferably a polyester polyol because it is excellent in thermal stability. The polyol preferably has a number average molecular weight of 1000 to 8000, more preferably 1000 to 5000, in view of excellent compatibility with polyisocyanate and the like described later. The number average molecular weight is a molecular weight when converted to standard polystyrene by gel permeation chromatography (GPC).

  The polyisocyanate in the mixture of polyol and polyisocyanate may be various isocyanates usually used for preparation of polyurethane, and examples thereof include aliphatic polyisocyanates and aromatic polyisocyanates. The polyisocyanate is preferably an aromatic polyisocyanate in terms of excellent storage stability and easy control of the reaction rate. Examples of the aromatic polyisocyanate include xylylene diisocyanate (XDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (also referred to as tolylene diisocyanate, TDI), naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PDI), and tolidine diisocyanate. (TODI). Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornane diisocyanate methyl, transcyclohexane-1,4-diisocyanate, and hydrogenated MDI. The polyisocyanate preferably has a molecular weight of 500 to 2000, more preferably 700 to 1500. As the polyisocyanate, a blocked polyisocyanate obtained by blocking the isocyanate group of the polyisocyanate with a blocking agent can also be used.

  The mixing ratio in the mixture of polyol and isocyanate 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 isocyanate is 0.7. It is preferable that it is ˜1.15 in that a desired degree of crosslinking and the like in the obtained polyurethane can be realized. This molar ratio (NCO / OH) is more preferably 0.85 to 1.10. From the viewpoint that hydrolysis of polyurethane can be prevented. However, in practice, the proper molar ratio may be mixed in an amount equivalent to 3 to 4 times in consideration of work environment and work errors.

  In the mixture of polyol and isocyanate, in addition to polyol and isocyanate, auxiliary agents usually used in the reaction of polyol and isocyanate, such as a chain extender and a crosslinking agent, may be used in combination. Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane, and amines.

  The prepolymer and the polyurethane may be any prepolymer and polyurethane obtained by reacting the polyol and the polyisocyanate, and the molecular weight thereof is not particularly limited. The prepolymer and the polyurethane can be obtained by reacting a polyol and a polyisocyanate by the one-shot method or the prepolymer method in the presence of the auxiliary agent, if desired.

  The polyurethane preparation component is preferably a mixture of polyol and polyisocyanate, particularly preferably a mixture of at least one polyol selected from polyether polyol and polyester polyol and polyisocyanate. That is, the composition particularly preferably contains a mixture of at least one polyol selected from polyether polyol and polyester polyol and polyisocyanate.

As shown in FIGS. 1 and 2, the coat layer 5 is formed by curing an aminosilane coupling agent on the outer peripheral surface of the conductive coat layer 4. The coat layer 5 is usually formed as a thin layer, but in the present invention, it is preferably adjusted to a layer thickness (Ts) of 1.5 to 4.5 μm (condition (3)). When the coating layer 5 is adjusted to a layer thickness in the above range, that is, when the thickness of the coating layer 5 satisfies the condition (3), desired conductivity and hardness when the developing roller 1 is obtained can be realized. it can. The thickness (Ts) of the coat layer 5 can easily adjust the conductivity and hardness of the developing roller 1 to a desired range, and can realize continuous printing characteristics described later at a very high level. It is preferable to adjust to 2-3.5 micrometers by the point which can be performed.

The aminosilane coupling agent that forms the coat layer 5 is, for example, the formula (1) R ¹ —SiR ² _m R ³ _(3-m) (in the formula (1), R ¹ is an amino group-containing group, and R ² Is an organic group, R ³ is a hydrolyzable group, and m is an integer of 0 to 2.). The amino group-containing group R ¹ in the formula (1) may be any group containing an amino group not related to the series. For example, an aminoalkyl group and an aminoaryl group, and these hydrogen atoms are alkyl groups, etc. And an alkylaminoalkyl group, an alkylaminoaryl group, an arylaminoalkyl group, and an arylaminoaryl group substituted with Carbon number of the said aminoalkyl group and the said aminoaryl group is not specifically limited, For example, it is preferable that it is 1-30, and it is more preferable that it is 2-29. In addition, carbon number of the said alkyl group, the said aryl group, etc. which substitute the hydrogen atom of an amino group is although it does not specifically limit, It is preferable that it is 1-12. The amino group-containing group R ¹ may have a plurality of amino groups, and primary, secondary, and tertiary amino groups may be mixed.

Examples of the organic group R ² include an alkyl group and an aryl group having 1 to 30 carbon atoms, and specific examples include a methyl group, an ethyl group, and a propyl group. The hydrolyzable group R ³ may be any group that can easily hydrolyze the Si—R ³ bond in the presence of moisture, such as a halogen atom, an alkoxy group, a (meth) acryloyl group, a mercapto group, and the like. Examples include hydrolyzable substituents. Among these, an alkoxy group is preferable because it is easily available. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. M is an integer of 0 to 2, and is preferably 0 or 1 and particularly preferably 0 in that the curing rate of the aminosilane coupling agent is high and desired properties can be exhibited. .

  Examples of the aminosilane coupling agent having a primary amino group and / or a secondary amino group include 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, and 3-amino. Propyltriethoxysilane, 3-aminopropylethyldiethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropylmethyldiethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, N-monobutylaminopropyltrimethoxysilane, 3-triethoxysilyl- N- (1,3-dimethyl Butylidene) propylamine, trimethoxysilyl-3-propyl-phenylamine and trimethoxysilyl-3-propyl-benzylamine and the like.

  As an aminosilane coupling agent having a tertiary amino group, for example, N, N-dimethylaminopropyltrimethoxysilane, N, N-diethylaminopropyltrimethoxysilane, N, N-dipropylaminopropyltrimethoxysilane, N, N-dibutylaminopropyltrimethoxysilane, N, N-dioctylaminopropyltrimethoxysilane, N, N-dibutylaminopropylmethyldimethoxysilane, N, N-dibutylaminopropyldimethylmonomethoxysilane, N, N-dimethylaminophenyl Examples include trimethoxysilane, trimethoxysilyl-3-propylmorpholine, trimethoxysilyl-3-propylpiperidine, trimethoxysilyl-3-propylimidazole and the like.

  The aminosilane coupling agent having a tertiary amino group may be the aminosilane coupling agent having a tertiary amino group in advance, or an aminosilane having a primary and / or secondary amino group. The aminosilane coupling agent formed by substituting the hydrogen atom of the amino group of a coupling agent with the said alkyl group, the said alkenyl group, the said aryl group, etc. may be sufficient. Examples of the compound capable of substituting a hydrogen atom of the amino group include an epoxy group-containing compound and an epoxy group-containing silane coupling agent. As said epoxy group containing compound, a C1-C10 alkyl glycidyl ether etc. are mentioned, for example. Examples of the silane coupling agent containing an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane and the like. An epoxy silane coupling agent is preferable in that the ratio of the hydrolyzable group to the molecular weight does not greatly decrease even when the molecular weight increases.

  Examples of such aminosilane coupling agents having a tertiary amino group include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane and N-2- (aminoethyl) -3-aminopropyltrimethoxy. Silane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxy At least one aminosilane coupling agent selected from the group consisting of silane and 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane Less selected from the group Also a kind of amino silane coupling agent consisting of an epoxy silane coupling agent. In addition, as a silane coupling agent containing a tertiary amino group, the brand name "KBP43" (made by Shin-Etsu Chemical Co., Ltd.) etc. obtained from an aminosilane coupling agent and an epoxy silane coupling agent is mentioned, for example. .

  The reaction between the aminosilane coupling agent having the primary and / or secondary amino group and the compound containing the epoxy group is carried out by the molar ratio of the hydrogen atom and the epoxy group in the amino group (total moles of hydrogen atoms). (Number / number of moles of epoxy group) is 1 or more.

In the developing roller 1 provided with the conductive coating layer 4 and the coating layer 5 on the outer peripheral surface of the elastic layer 3, the thickness (Tu) of the conductive coating layer 4 and the thickness (Ts) of the coating layer 5 are as follows: (1) and condition (2) It is adjusted to satisfy 6.5 ≦ (Tu / Ts) ≦ 9.3 . When the thickness of the conductive coating layer 4 and the thickness of the coating layer 5 satisfy the conditions (1) and (2), the developing roller 1 can be adjusted to a conductivity suitable for transporting a desired amount of developer. In addition, the surface state of the developing roller 1 can be adjusted to a surface roughness suitable for transporting a desired amount of developer, and the developer can have a transport characteristic and a desired charge amount for transporting the desired amount of developer. It is possible to achieve a high level of charging characteristics for charging the battery. As a result, the developing roller 1 can exhibit high continuous printing characteristics. Therefore, the developing roller 1 contributes to forming a desired high-definition image when mounted on an image forming apparatus that has a high-definition image, a high printing speed, and / or a small and lightweight image forming apparatus. I can .

Further, the thickness (Tu) of the conductive coating layer 4 and the thickness (Ts) of the coating layer 5 are adjusted so as to satisfy the condition (3) in addition to the conditions (1) and (2). It is preferable. That is, the thickness of the conductive coating layer 4 is selected from the range of 15.7 to 22.2 μm, the thickness of the coating layer 5 is selected from the range of 1.5 to 4.5 μm, and the conductivity It is preferable that the ratio (Tu / Ts) between the thickness of the coat layer 4 and the thickness of the coat layer 5 is adjusted to be in the range of 6.5 to 9.3 . When the thickness of the conductive coating layer 4 and the thickness of the coating layer 5 satisfy the conditions (1), (2) and (3), the conductive property suitable for transporting a desired amount of developer to the developing roller 1. The surface condition of the developing roller 1 can be adjusted to a surface roughness that is more suitable for conveying a desired amount of developer, and transport characteristics and desired for conveying the desired amount of developer. The charging characteristics for charging the developer to the above-mentioned charge amount can be made compatible at an even higher level. As a result, the developing roller 1 can exhibit extremely high continuous printing characteristics. Therefore, the developing roller 1 that satisfies the above conditions (1) to (3) has a desired height when mounted on an image forming apparatus that has high image definition, high printing speed, and / or small and light weight. This can greatly contribute to forming a fine image.

In the present invention, thickness of the conductive coat layer 4 and the coating layer 5, a conductive coating layer 4 and the coating layer 5 in a cross section obtained by cutting the developing roller 1 in a plane perpendicular to the axis of the developing roller 1, respectively, scanning A plurality of points can be observed with an electron microscope, and a plurality of measured values can be obtained as an arithmetic average value.

The developing roller 1 preferably has a JIS A hardness of 30 to 80. When the developing roller 1 has a JIS A hardness of 30 to 80, the contact area between the developing roller 1 and the contacted body can be increased, and rebound resilience and compression set are excellent. The JIS A hardness is more preferably 40 to 70 in that the contact area between the developing roller 1 and the contacted body is improved and the resilience and compression set can be improved as desired. It is especially preferable that it is 45-60. The JIS A hardness can be measured according to JIS K6301.

The developing roller 1, particularly the coat layer 5, preferably has a surface roughness Rz of 4.5 to 7.0 μm. When the developing roller 1 has a surface roughness Rz of 4.5～7.0Myuemu, it can be supplied as desired to the image carrier carrying the current image agent as desired, the developer This improves the conveyance characteristics. The surface roughness Rz is particularly preferably 4.8 to 6.7 μm. Surface roughness Rz is applied to a surface roughness meter (trade name “590A”, manufactured by Tokyo Seimitsu Co., Ltd.) equipped with a measuring probe having a tip radius of 2 μm according to JIS B 0601-1984 (10-point average roughness). The developing roller 1 provided with the layer 5 is set, and the surface roughness is measured at least at three points with a measurement length of 2.4 mm, a cutoff wavelength of 0.8 mm, and a cutoff type Gaussian, and the average value of these is measured as the surface roughness Rz. And

The developing roller 1, particularly the coat layer 5, preferably has an arithmetic average roughness Ra of 0.5 to 2.0 μm. When the arithmetic average roughness Ra is within the above range, the developer can be carried in a desired manner and supplied to the abutted body in a desired manner, and the developer transport characteristics are improved. The arithmetic average roughness Ra is more preferably 0.7 to 1.5 μm, and particularly preferably 0.8 to 1.2 μm, in that this effect is more excellent. The arithmetic average roughness Ra according to JIS B 0601-1984 (arithmetic average roughness), the surface roughness meter having a measuring probe tip radius 2 [mu] m (trade name "590A", manufactured by Tokyo Seimitsu), the developer The roller 1 is set, surface roughness is measured at at least three points with a measurement length of 2.4 mm, a cut-off wavelength of 0.8 mm, and a cut-off type Gaussian, and the arithmetic average value thereof is defined as the arithmetic average roughness Ra.

The developing roller 1, particularly the coat layer 5, preferably has a surface glossiness of ^2.5 to 5.0 at a measurement area of 4 mm ² . When the developing roller 1 has the above surface glossiness of 2.5 to 5.0, a high-quality image is formed by effectively exhibiting charging characteristics that prevent a decrease in print density, blurring of the image, fogging, and the like. can do. The surface glossiness is particularly preferably from 3.0 to 4.5 in that the function of the coat layer 5 can be exerted in a well-balanced manner at a high level. The surface glossiness is, for example, the type and amount of each component contained in the urethane resin composition, the method for forming the conductive coating layer 4 or the coating layer 5, and the surface roughness of the elastic layer 3 to be described later. Can be easily adjusted to a desired value. Here, the surface glossiness is a ratio to the glossiness 100 when the reflection index 1.567 of the black glass standard plate according to DIN 67530 is 100 glossiness. The surface glossiness is measured using 4 mm ^{2 on} the surface of the coat layer 5, that is, 2 × 2 mm as a measurement area. By setting the measurement area of the surface glossiness to such a minimum area, the surface glossiness representing the surface glossiness of the entire surface of the coat layer 5 can be measured with high accuracy. In the present invention, since the surface glossiness is a minimum area, in measuring the surface glossiness, the surface of the coat layer 5 may be measured as it is, or the coat layer 5 is cut out from the developing roller 1. Alternatively, measurement may be performed in a planar state. The surface glossiness is measured at a plurality of locations on the surface of the coat layer 5, for example, 4 locations at regular intervals in the circumferential direction of the coat layer 5 and 5 locations at regular intervals in the longitudinal direction of the coat layer 5, respectively. Let these arithmetic mean values. The incident angle when measuring the surface glossiness is 60 ° with respect to the surface of the coat layer 5. For the measurement of the surface glossiness, for example, the trade name “Minimum Area Glossmeter 155-SO” (manufactured by Sheen Instruments Ltd) can be used.

The developing roller 1 preferably has an electrical resistivity of 10 ² to 10 ⁹ Ω. When the developing roller 1 has an electric resistance value of 10 ² to 10 ⁹ Ω, the charging property of the developing roller 1 is excellent. For example, when the developing roller 1 is used as an example of a developer carrying member (for example, see FIG. 3) in the image forming apparatus, the developer can be charged as desired. The developer thus carried can be reliably supplied to the image carrier as desired. The electric resistance value is more preferably 10 ³ to 10 ⁹ Ω, more preferably 10 ⁴ to 10 ⁸ Ω, in that the loading and supply of the developer can be achieved as desired at an even higher level. Is particularly preferred. The electrical resistance value of the developing roller 1 is determined by using an electrical resistance meter (trade name: ULTRA HIGH RESISTANCE METER R8340A, manufactured by Advantest Co., Ltd.), placing the developing roller 1 horizontally, a thickness of 5 mm, a width of 30 mm, and development. A gold-plated plate having a length on which the entire roller 1 can be placed is used as an electrode, and a load of 500 g is supported on both ends of the shaft body 2 in the developing roller 1 so that the shaft 2 is interposed between the electrodes. It can be measured by applying DC 100V, reading the value of an electric resistance meter one second later, and setting this value as the electric resistance value. The electrical resistance value can be adjusted within the above range by adjusting the content of the conductivity imparting agent contained in the elastic layer 3.

The developing roller 1 preferably has a developer adhesion amount of about 0.4 to 1.1 mg / cm ² , and particularly preferably 0.8 to 1.1 mg / cm ² . When the developing roller 1 has a developer adhesion amount in the above range, a predetermined amount of developer can be supplied to the image carrier , and an image can be formed with a sufficient print density. Here, the developer deposition amount is mounted 20 ° C., under a relative humidity of 50%, the developing roller 1 image forming apparatus (trade name "JUSTIO HL-4040CN", Brother Industries, Ltd., resolution 1200dpi equivalent) in Then, after 5 sheets of black solid printing were performed, the black solid printing was forcibly stopped, the developing roller 1 was taken out of the image forming apparatus, and the developer adhered to the surface of the developing roller had a cross-sectional area of 0.25 cm. A suction-type small charge amount measuring device having ^two suction ports, for example, the product name “210HS q / M METER” (manufactured by Trek Japan Co., Ltd.), and measures the mass of the developer collected by suction and measured per unit area. It can measure by converting into the mass of.

Developing roller 1, the current image agent, it is preferable to be able to impart charge amount of the charge amount or about -60 to-10 [mu] C / g to about 10~60μC / g. The charging amount of the developing roller 1 is in the above range, preferably about 15 to 50 μC / g or about −50 to −15 μC / g, particularly preferably about 35 to 50 μC / g. -50~-35μC / if g of the charge can be imparted to the developer, can supply the developer that has been charged to the charging amount of Nozomu Tokoro the image bearing member, a high quality image Can be formed. Here, the charge amount of the developer is set to an image forming apparatus (trade name “JUSTIO HL-4040CN”, manufactured by Brother Industries, Ltd., equivalent to resolution 1200 dpi) in an environment of 20 ° C. and 50% relative humidity. After the black solid printing is performed, the black solid printing is forcibly stopped, the developing roller 1 is taken out of the image forming apparatus, and the developer adhered to the surface of the developing roller has a cross-sectional area of 0. It can be measured by a suction type small charge amount measuring device having a suction port of 25 cm ² , for example, trade name “210HS Q / M METER” (manufactured by Trek Japan Co., Ltd.).

The developing roller 1 is attached to the image forming apparatus in a state where the developing roller 1 is in contact with or pressed against a contact body such as a developer carrier. At this time, the nip width between the developing roller 1 and the contact body is usually adjusted so that the circumferential length of the developing roller 1 is 0.1 to 5 mm.

The developing roller according to the present invention can be manufactured, for example, by the following method. First, the shaft body 2 is produced from the material according to a conventional method, and a primer or the like is applied to the outer peripheral surface as desired. Next, the rubber composition is heat-cured on the outer peripheral surface of the shaft body 2 by a known molding method to form the elastic layer 3. The molding method is not particularly limited, for example, continuous vulcanization by extrusion molding, press molding, mold molding by injection, or the like. The elastic layer 3 formed in this way has its surface polished and ground as desired to adjust the outer diameter, surface state, and the like. If desired, a primer or the like is applied to the outer peripheral surface of the elastic layer 3.

  The urethane resin composition is applied to the outer peripheral surface of the elastic layer 3 thus formed, and then the applied urethane resin composition is heated and cured to form the conductive coat layer 4. The application of the urethane resin composition is performed by, for example, a known application method such as a coating method, a dipping method, a spray coating method, and the method of heat-curing the urethane resin composition thus applied is Any method can be used as long as heat necessary for curing the urethane resin composition can be applied. Examples thereof include a method of heating the elastic layer 3 and the like coated with the urethane resin composition with a heater. The heating temperature when the urethane resin composition is heat-cured is, for example, 140 to 170 ° C., particularly 150 to 160 ° C., and the heating time is preferably 15 to 60 minutes, particularly 30 to 45 minutes.

  An aminosilane coupling agent is applied to the outer peripheral surface of the conductive coating layer 4 thus formed, and then the coated aminosilane coupling agent is heated and cured to form the coating layer 5. The aminosilane coupling agent is applied by a known coating method such as a coating method in which a solution containing an aminosilane coupling agent is applied, or a dipping method in which the elastic layer 3 is immersed in the solution. The aminosilane coupling agent may be applied as it is, or a coating solution in which the aminosilane coupling agent is dissolved in a volatile solvent may be applied. Examples of the coating liquid include a coating liquid obtained by dissolving or suspending an aminosilane coupling agent in an alcohol solvent such as methanol or ethanol, an ester solvent such as acetate, and the like. A density | concentration can be 0.1-100 mass%, for example. The heating temperature when the aminosilane coupling agent is cured by heating is preferably 100 to 150 ° C., particularly 110 to 130 ° C., and the heating time is 10 minutes to 2 hours, particularly 20 to 50 minutes.

The developing roller 1 is provided with an elastic layer 3, a conductive coating layer 4 and a coating layer 5 in this order on the outer peripheral surface of the shaft body 2, and the conductive coating layer 4 and the coating layer 5 satisfy the condition (1). Since (2) is satisfied, the conveyance characteristics and the charging characteristics can be achieved at a high level, and high continuous printing characteristics can be exhibited. Therefore, when the developing roller 1 is attached to the image forming apparatus, it can contribute to forming a desired high-definition image. In particular, the developing roller 1 contributes to forming a desired high-definition image when mounted on an image forming apparatus that has high image definition, high printing speed, and / or reduced size and weight. Can do.

In other words, when the developing roller 1 is mounted on a high-definition image forming apparatus that requires a high level of charging characteristics, a desired high-definition image is conveyed by electrically and physically transporting a predetermined amount of developer. Can form. Further, when the developing roller 1 is mounted on a high-speed image forming apparatus in which the developing roller rotates at high speed, a desired high-definition image is formed by electrically and physically transporting a predetermined amount of developer. be able to. Further, when the developing roller 1 is mounted on a compact and lightweight image forming apparatus in which the developing roller is reduced in size and weight (for example, the diameter is reduced), a predetermined amount of developer is electrically and physically conveyed to be desired. High-definition images can be formed.

Developing roller according to the present invention, as a developing low la for an image forming apparatus, is preferably used. In particular, it is suitably used as a developing roller that is deeply involved in the loading and supply of the developer.

Further, examples of the image forming apparatus to which the developing roller according to the present invention is attached include a color image forming apparatus (tandem type, four-cycle type) having a developing unit for each color, and the like. Preferably, the developing roller according to the present invention can achieve both a conveyance characteristic for conveying a desired amount of developer and a charging characteristic for charging the developer to a desired charge amount at a high level. Since continuous printing characteristics can be exhibited, the image forming apparatus is used in an image forming apparatus that has high image definition, high printing speed, and / or reduced size and weight. Examples of the image forming apparatus with an increased printing speed include a tandem type color image forming apparatus in which a plurality of developing units are arranged. As the image forming apparatus reduced in size and weight, for example, an image forming apparatus in which each member is reduced in size and weight, a tandem type color image forming apparatus in which developing units are arranged in a horizontal direction, and the like can be given. May be an image forming apparatus provided with a developing roller having an outer diameter of 20 mm or less.

An example of a tandem type color image forming apparatus equipped with the developing roller according to the present invention as a developer carrying member will be described with reference to FIG. The image forming apparatus shown in FIG. 3 is a direct transfer tandem color image forming apparatus that directly transfers a developer image developed on an image carrier to a recording medium.

As shown in FIG. 3, the image forming apparatus 10 includes image carriers 11 </ b> B, 11 </ b> C, 11 </ b> M, and 11 </ b> Y equipped in four types of developing units B, C, M, and Y arranged in series on the transfer conveyance belt 6. Therefore, the developing units B, C, M, and Y are arranged in series on the transfer conveyance belt 6. In the image forming apparatus 10, it is instrumentation wearing developing roller according to the present invention to said developer carrying member.

  As shown in FIG. 3, the developing unit B is provided with a rotatable image carrier 11B on which an electrostatic latent image is formed, in contact with or in pressure contact with the image carrier 11B, or at a predetermined interval. The charging means 12B for charging the image carrier 11B, the exposure means 13B provided above the image carrier 11B and forming an electrostatic latent image on the image carrier 11B, and the image carrier 11B are in contact with or pressed against each other. Or developing means 20B for supplying the developer 22B with a constant layer thickness to the image carrier 11B and developing the electrostatic latent image, and a transfer conveyance belt below the image carrier 11B. A transfer unit 14B, which is provided so as to be in contact or pressure contact via 6 and which transfers the developed electrostatic latent image from the image carrier 11B onto the recording medium 16 conveyed by the transfer conveyance belt 6; Is not transferred to the image carrier 11B and remains on the image carrier 11B. And a cleaning unit 15B for removing the developer 22B, and the like. As shown in FIG. 3, the image carrier 11 </ b> B and the transfer unit 14 </ b> B in the developing unit B are in contact or pressure contact with each other via the transfer conveyance belt 6 stretched around the two support rollers 42. Then, the recording body 16 is transported by the transfer transport belt 6 so as to pass through the contact portion between the image carrier 11B and the transfer means 14B. The transfer conveyance belt 6 conveys the recording medium 16 and transfers the developed electrostatic latent image on the image carrier 11B in cooperation with the transfer means 14B. As the image carrier 11B, the charging unit 12B, the exposure unit 13B, the transfer unit 14B, and the cleaning unit 15B, conventionally known ones can be appropriately selected and used.

As shown in FIG. 3, the developing means 20B has an opening at a position facing the image carrier 11B, and a housing 21B for storing the developer 22B and an image carrier at the opening of the housing 21B. A rotatable developer carrier 23B which is provided in contact with or pressed against the body 11B or at a predetermined interval and supplies the developer 22B to the image carrier 11B with a constant layer thickness; and a developer carrier 23B And a developer regulating member 24B that regulates the layer thickness of the developer 22B by contacting or press-contacting the developer carrier 23B and charging the developer 22B by frictional charging. Developing roller 1 which is an example of a developing roller according to the present invention is employed as a developer carrying member 23B, conventionally known ones are used is suitably selected as the developer regulating member 24B. The developer 22B may be a dry developer or a wet developer as long as it can be charged by friction and can be fixed to the recording medium 16, and may be a non-magnetic developer or a magnetic developer. The developing unit B stores a black developer in the housing 21B.

  As shown in FIG. 3, the developing units C, M, and Y are configured similarly to the developing unit B. The developing units C, M, and Y accommodate a cyan developer 22C, a magenta developer 22M, and a yellow developer 22Y in housings 21C, 21M, and 21Y, respectively.

  As shown in FIG. 3, at the bottom of the image forming apparatus 10, a cassette 41 for stacking and storing a plurality of recording bodies is installed as the recording body 16, and one recording body in the cassette 41 is fed by a sheet feeding roller or the like. They are sent out one by one and conveyed onto the transfer conveyance belt 6.

  As shown in FIG. 3, a fixing unit 30 for fixing various developers (electrostatic latent images) transferred to the recording body 16 is disposed downstream in the conveyance direction of the recording body 16 in the image forming apparatus 10. . As the fixing unit 30, for example, a heat roller fixing device including a fixing roller capable of generating heat, a heat fixing device such as an oven fixing device, a pressure fixing device including a pressurizing fixing roller, or the like can be used. As shown in FIG. 3, in the image forming apparatus 10, a fixing device including a fixing belt 36 is disposed as the fixing unit 30. As shown in the cross section of FIG. 3, the fixing device includes a fixing roller 31 and an endless belt supported in the vicinity of the fixing roller 31 in a housing 34 having an opening 35 through which the recording medium 16 passes. The fixing roller 31 includes a roller 33, a fixing belt 36 wound around the fixing roller 31 and the endless belt support roller 33, and a pressure roller 32 disposed to face the fixing roller 31. And the pressure roller 32 are pressure heat fixing devices that are rotatably supported so as to abut or press against each other. The endless belt support roller 33 may be a roller that is usually used in an image forming apparatus. Each of the fixing roller 31, the endless belt support roller 33, and the pressure roller 32 includes a heating body (not shown), and the pressure roller 32 causes the fixing belt 36 to be moved by a biasing means (not shown) such as a spring. Via the fixing roller 31. By passing the recording medium 16 between the fixing belt 36 and the pressure roller 32 being pressed against each other, the developer 42 (electrostatic latent image) transferred to the recording medium 16 is fixed by being heated simultaneously with the pressurization. be able to.

  The image forming apparatus 10 operates as follows. First, the image carrier 11B of the developing unit B is uniformly charged by the charging unit 12B, the image is exposed by the exposure unit 13B, and an electrostatic latent image is formed on the surface of the image carrier 11B. On the other hand, in the developing means 20B, the black developer 22B is regulated to a desired layer thickness and charged as desired by the developer carrier 23B and the developer regulating member 24B. Then, the black developer 22B is supplied from the developer carrier 23B to the image carrier 11B, and the electrostatic latent image formed on the image carrier 11B is developed and visualized as a developer image. Next, the developer image is transferred onto the recording medium 16 conveyed by the transfer conveyance belt 6 between the image carrier 11B and the transfer unit 14B. In this way, the developer image is visualized as a black image on the recording medium 16. Next, in the same manner as the developing unit B, the cyan image, the magenta image, and the yellow image are superimposed on the recording medium 16 in which the developer image is visualized as a black image by the developing units C, M, and Y, respectively. The image is visualized. Next, the recording body 16 in which the color image is visualized is conveyed to the fixing unit 30 by the conveying unit, and passes through a contact portion or a pressure contact portion between the fixing roller 31 and the pressure roller 32 via the fixing belt 36. Occasionally heated and / or pressurized to fix the transferred color image as a permanent image. In this way, a color image can be formed on the recording medium 16.

According to the image forming apparatus 10, the developer carrying member 23B, 23C, and a 23M and 23Y, since the developing roller 1 which is an example of a developing roller according to the present invention is mounted, none of these developing rollers, can exhibit high continuous printing characteristics, so that, for example, without continuous also blurring the color image as formed and head is substantially generated, to form the desired high resolution image Can do.

The developing roller according to the present invention is not limited to the above-described embodiments, and various modifications can be made as long as the object of the present invention can be achieved. For example, the shape of the developing roller 1 is not particularly limited as long as the developing roller 1 has a cylindrical shape, and as illustrated in FIG. 1, the outer diameter thereof is substantially the same from one end to the other end in the axial direction. May be a so-called straight shape, and may have a so-called reverse crown shape in which the outer diameter at the central portion in the axial direction is smaller than the outer diameter at both end portions, and the outer diameter at the central portion in the axial direction. It may be a so-called crown shape whose diameter is larger than the outer diameter at both ends.

Further, in the developing roller 1, the elastic layer 3, the conductive coating layer 4 and the coating layer 5 are sequentially laminated on the outer peripheral surface of the shaft body 2 without interposing other layers. Between the elastic layer and the elastic layer, between the elastic layer and the conductive coating layer, and between the conductive coating layer and the coating layer, a primer layer, an adhesive layer, etc. that improve adhesion, followability, etc. are provided. You can also.

Although the conductive coating layer 4 and the coating layer 5 in the developing roller 1 are both formed as one layer, in the present invention, the conductive coating layer and the coating layer may be formed into a plurality of layers.

  The image forming apparatus 10 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. .

Example 1
The shaft body 2 (made by SUM22, diameter 7.5 mm, length 281.5 mm) subjected to electroless nickel plating was washed with toluene, and a silicone primer (trade name “Primer No. 16”, Shin-Etsu) on its surface Chemical Industries, Ltd.) was applied. The shaft body subjected to the primer treatment was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the surface of the shaft body 2.

Next, 100 parts by mass of dimethylpolysiloxane (D) (degree of polymerization 300) blocked at both ends with dimethylvinylsiloxy groups, and hydrophobized fumed silica having a BET specific surface area of 110 m ² / g (Nippon Aerosil Co., Ltd.) Made by company, R-972) 1 part by mass, average particle size 6 μm, bulk density of 0.25 g / cm ³ diatomaceous earth (F) (Oplite W-3005S, manufactured by Hokuaki Diatomite Co., Ltd.) 40 parts by mass, and 5 parts by mass of acetylene black (G) (Denka Black HS-100, manufactured by Denki Kagaku Kogyo Co., Ltd.) was placed in a planetary mixer, stirred for 30 minutes, and then passed once through three rolls. This is returned to the planetary mixer again, and as a crosslinking agent, methyl hydrogen polysiloxane (E) having Si—H groups at both ends and side chains (polymerization degree 17, Si—H amount 0.0060 mol / g) 2. 1 part by mass, 0.1 part by mass of ethynylcyclohexanol and 0.1 part by mass of platinum catalyst (H) (Pt concentration 1%) are added as reaction control agents, and the mixture is stirred for 15 minutes and added. A curable liquid conductive silicone rubber composition was prepared. The prepared addition-curable liquid conductive silicone rubber composition was molded on the outer peripheral surface of the shaft body 2 by liquid injection molding. This molded body is polished into an inverted crown shape in which the outer diameter gradually decreases from the respective end portions in the axial direction of the molded body toward the central portion at substantially the same rate, and the outer diameter of the end portion is 20.1 mm, the central portion. The elastic layer 3 having an outer diameter of 20 mm was formed.

  Next, 20 parts by mass of polyisocyanate (trade name “Daipura Coat EN” manufactured by Dainichi Seika Kogyo Co., Ltd.) and 100 parts by mass of polyester polyol (trade name “Daipura Coat SO” manufactured by Dainichi Seika Kogyo Co., Ltd.) A urethane resin composition containing a molar ratio (NCO / OH = 1)) and 5 parts by mass of a conductivity imparting agent (trade name “Asahi Thermal”, manufactured by Asahi Carbon Co., Ltd.) was prepared.

The urethane resin composition was applied once on the outer peripheral surface of the elastic layer 3 by a spray coating method and then heated at 150 ° C. for 30 minutes to form a conductive coating layer 4 (layer thickness of the conductive coating layer 4 (Tu ) Was 15.7 μm.) An aminosilane coupling (trade name “KBP43”, manufactured by Shin-Etsu Chemical Co., Ltd.) containing a tertiary amino group was applied once to the outer peripheral surface of the conductive coating layer 4 by a spray coating method at 30 ° C. The coating layer 5 was formed by heating for a minute (the layer thickness (Ts) of the coating layer 5 was 2.4 μm). In this way, a developing roller was manufactured.

(Examples 2 and 3 and Comparative Examples 1 to 5)
A developing roller is manufactured in the same manner as in Example 1 except that the thickness (Tu) of the conductive coating layer 4 and / or the thickness (Ts) of the coating layer 5 is adjusted to the thicknesses shown in Table 1. did.

In each of the developing rollers thus produced, arithmetic average roughness Ra, surface roughness Rz, surface glossiness, and electrical resistivity were evaluated according to the above methods. The results are shown in the table.

(Continuous printing evaluation)
Next, four each of the developing rollers are prepared. In the tandem type color image forming apparatus (trade name “JUSTIO HL-4040CN”, manufactured by Brother Industries, Ltd.) shown in FIG. 3, developer carriers 23B, 23C, and 23M are prepared. And 23Y. Note that the developer and the developer regulating member attached to the tandem color image forming apparatus were used as the developer and the developer regulating member.

The environment inside the tandem type color image forming apparatus equipped with a developing roller was adjusted to a temperature of 20 ° C. and a relative humidity of 50%, and left still for a while. Thereafter, while maintaining this environment, 100 color images were printed continuously in the color printing mode (one 11-point character “A” was printed in color on the left shoulder position of the A4 size recording medium 16). The printed image was visually evaluated and faded into a color image to confirm the presence or absence of fog. Evaluation is “◯” when no blur or fog is confirmed in all color images, or when slight blur or fog is acceptable for a small number of color images, and it is not acceptable for many color images. A case where a slight blur and / or fogging could be confirmed was defined as “x”. The results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Shaft body 3 Elastic layer 4 Conductive coat layer 5 Coat 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, Development means 21B, 21C, 21M, 21Y, 34 Housings 22B, 22C, 22M , 22Y Developer 23B, 23C, 23M, 23Y Developer carrier 24B, 24C, 24M, 24Y Developer regulating member 30 Fixing means 31 Fixing roller 32 Pressure roller 33 Endless belt support roller 35 Opening 36 Fixing belt 41 Cassette 42 Support roller 100 Resistance measuring device 101 Electrode plate 102 Weight 1 03 Roller fixing jig 104 First electrode 105 Second electrode B, C, M, Y Development unit

Claims (4)

A shaft body, an elastic layer formed on the outer peripheral surface of the shaft body, a conductive coat layer formed on the outer peripheral surface of the elastic layer, and an aminosilane coupling agent cured on the outer peripheral surface of the conductive coat layer Comprising a coat layer,
A developing roller characterized in that the thickness (Tu: μm) of the conductive coating layer and the thickness (Ts: μm) of the coating layer satisfy the following conditions (1) and (2).
(1) 15.7 ≦ Tu (μm) ≦ 22.2
(2) 6.5 ≦ (Tu / Ts) ≦ 9.3 The developing roller according to claim 1, wherein a thickness (Ts) of the coating layer is 1.5 μm or more and 4.5 μm or less. The developing roller according to claim 1, wherein the coat layer has a surface glossiness of ^2.5 to 5.0 at a measurement area of 4 mm ² . An image forming apparatus comprising the developing roller according to claim 1.

Images