JP5030605B2 - Conductive elastic roller and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a conductive elastic roller having an elastic layer and a coating layer, and an image forming apparatus provided with the conductive elastic roller, and is particularly suitable as a developing roller and a charging roller, and the adhesion between the elastic layer and the coating layer. The present invention relates to a highly conductive elastic roller.

  In general, in an electrophotographic image forming apparatus such as a copying machine, a facsimile, or a laser beam printer (LBP), a developing roller, a charging roller, a toner supply roller, a transfer roller, a paper feeding roller, a cleaning roller, and a pressure for fixing. As a roller or the like, a roll-shaped conductive elastic member, i.e., a conductive elastic roller, is often used, and the conductive elastic roller is usually provided with a shaft member that is attached by being supported at both ends in the length direction, And one or more elastic layers disposed on the radially outer side of the shaft member. In addition, the conductive elastic roller may further include a resin coating layer on the surface of the elastic layer for the purpose of controlling chargeability and adhesion to toner, preventing contamination of the photosensitive drum by the elastic layer, and the like.

  For the shaft member of the conductive elastic roller, various resins such as engineering plastics are used in addition to metals such as iron and stainless steel. Moreover, various thermosetting resins such as thermosetting urethane resin are used for the elastic layer of the conductive elastic roller, and the resin raw material is injected into a mold having a desired cavity shape and heated, It is manufactured by heat-curing a resin raw material (see Patent Document 1 below). Further, the resin coating layer is prepared by dipping the roller body composed of the shaft member and the elastic layer in a solvent-based or aqueous coating liquid containing resin or spraying the coating liquid on the roller body, Alternatively, it is formed by drying and curing with hot air.

JP 2004-150610 A

  However, when an elastic layer is formed using a thermosetting urethane resin or the like, and then a conductive elastic roller is manufactured by forming a coating layer by dipping in a coating liquid containing a resin, Since it is necessary to heat and cure the resin raw material or to dry and cure the coating film, a large amount of heat energy is required, and a considerable amount of time is required for curing. Furthermore, in order to heat and dry-cure, there also existed a problem that a large installation expense, such as a curing furnace and a drying line, was required.

  On the other hand, the present inventors examined a conductive elastic roller using an ultraviolet curable resin instead of a thermosetting resin for the elastic layer and further using an ultraviolet curable resin for the coating layer. In general, it has been found that the elastic layer made of an ultraviolet curable resin and the coating layer made of an ultraviolet curable resin have poor adhesion, and there is a problem with the durability of the roller. Here, when a roller having poor adhesion between the elastic layer and the coating layer is used in the image forming apparatus, the coating layer is easily peeled off from the elastic layer during use, and image defects are likely to occur. Therefore, the elastic layer of the conductive elastic roller and the coating layer need to have sufficiently high adhesion.

  Therefore, an object of the present invention is to solve the above-described problems of the prior art, and can be manufactured in a short time without requiring a large amount of heat energy, and does not require a large amount of equipment cost. Another object of the present invention is to provide a conductive elastic roller having high adhesion between the film and the coating layer. Another object of the present invention is to provide an image forming apparatus that can stably form a good image using such a conductive elastic roller.

  As a result of intensive studies to achieve the above object, the present inventor has cured a raw material composition containing a urethane (meth) acrylate oligomer, a photopolymerization initiator and a conductive agent with ultraviolet irradiation to form an elastic layer, and By adding a partial ester of a (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid to the raw material composition for the elastic layer, a large amount of heat energy is not required, and it can be produced in a short time. It has been found that a conductive elastic roller having high adhesion between the elastic layer and the coating layer can be obtained without requiring a large amount of equipment costs, and the present invention has been completed.

That is, the conductive elastic roller of the present invention includes a shaft member, one or more elastic layers disposed on the radially outer side of the shaft member, and one or more coating layers disposed on the radially outer side of the elastic layer. With a membrane layer,
At least the outermost layer of the elastic layer is made of an ultraviolet curable resin obtained by curing a raw material mixture containing a urethane (meth) acrylate oligomer (A), a photopolymerization initiator (B), and a conductive agent (C) by ultraviolet irradiation,
The raw material mixture for the outermost layer of the elastic layer further contains a partial ester (D) of a (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid.

  In a preferred example of the conductive elastic roller of the present invention, the partial ester (D) of the (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid is a monoester of an acrylate having a hydroxyl group and a divalent carboxylic acid. .

  In another preferred embodiment of the conductive elastic roller of the present invention, the partial ester (D) of (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid is 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2 At least one selected from the group consisting of 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and pentaerythritol triacrylate, succinic acid, phthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid, methylhexahydrophthal It is a monoester with at least one selected from the group consisting of acids, hymic acids and methyl hymic acids.

  In another preferred embodiment of the conductive elastic roller of the present invention, the content of the partial ester (D) in the outermost layer raw material mixture of the elastic layer is 1 to 20% by mass.

  In another preferred embodiment of the conductive elastic roller of the present invention, the raw material mixture for the outermost layer of the elastic layer further contains an acrylate monomer (E). Here, the acrylate monomer (E) preferably has a functional group number of 1.0 to 10 and a molecular weight of 100 to 2,000.

  In another preferred embodiment of the conductive elastic roller of the present invention, the conductive agent (C) is an ionic conductive agent.

  In the conductive elastic roller of the present invention, the raw material mixture for the outermost layer of the elastic layer is a total of 100 parts by mass of the urethane (meth) acrylate oligomer (A), the partial ester (D), and the acrylate monomer (E). The photopolymerization initiator (B) is preferably contained in an amount of 0.2 to 5.0 parts by mass, and the conductive agent (C) is preferably contained in an amount of 0.1 to 5.0 parts by mass.

In another preferred embodiment of the conductive elastic roller of the present invention, the shaft member is a metal shaft or a shaft in which a highly rigid resin base material is disposed outside the metal shaft,
The outer diameter of the metal shaft is 4.0 to 8.0 mm, and the outer diameter of the resin base material is 10 to 25 mm.

In the conductive elastic roller of the present invention, the elastic layer preferably has an Asker C hardness of 30 to 70 degrees, a compressive residual strain of 5% or less, and a volume resistivity of 10 ⁴ to 10 ¹⁰ Ωcm. Further, the thickness is preferably 1 to 3000 μm

  The conductive elastic roller of the present invention is suitable as a developing roller and a charging roller.

  The image forming apparatus of the present invention is characterized by using the conductive elastic roller.

  According to the present invention, the raw material mixture containing the urethane (meth) acrylate oligomer (A), the photopolymerization initiator (B), and the conductive agent (C) is cured by ultraviolet irradiation to form at least the outermost layer of the elastic layer. Furthermore, by adding a partial ester (D) of (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid to the raw material mixture for the outermost layer of the elastic layer, a large amount of heat energy is not required, and in a short time It is possible to provide a conductive elastic roller that can be manufactured and does not require a large amount of equipment cost and has high adhesion between the elastic layer and the coating layer. Further, it is possible to provide an image forming apparatus that includes such a conductive elastic roller and can stably form a good image.

<Conductive elastic roller>
Hereinafter, the conductive elastic roller of the present invention will be described in detail with reference to FIG. FIG. 1 is a cross-sectional view of an example of the conductive elastic roller of the present invention. The conductive elastic roller 1 in the illustrated example includes a shaft member 2 that is attached to both ends in the length direction, an elastic layer 3 disposed radially outside the shaft member 2, and the elastic layer 3. And a coating film layer 4 disposed on the radially outer side. The conductive elastic roller 1 shown in FIG. 1 has only one elastic layer 3, but the conductive elastic roller of the present invention may have two or more elastic layers. Moreover, although the conductive elastic roller 1 shown in FIG. 1 has only one coating layer 4, the conductive elastic roller of the present invention may have two or more coating layers.

  In FIG. 1, the shaft member 2 is composed of a metal shaft 2A and a highly rigid resin base material 2B disposed on the outer side in the radial direction of the metal shaft 2A. The shaft member of the conductive elastic roller of the present invention is As long as it has good electrical conductivity, there is no particular limitation, and it may be composed only of the metal shaft 2A, may be composed only of a highly rigid resin base material, or is made of a metal whose interior is hollowed Alternatively, it may be a cylindrical body made of a highly rigid resin. In addition, when using highly rigid resin for the shaft member 2, it is preferable to ensure sufficient electroconductivity by adding and dispersing a conductive agent in the highly rigid resin. Here, as the conductive agent dispersed in the high-rigidity resin, carbon black powder, graphite powder, carbon fiber, metal powder such as aluminum, copper and nickel, metal oxide powder such as tin oxide, titanium oxide and zinc oxide, conductive A powdery conductive agent such as conductive glass powder is preferred. These electrically conductive agents may be used individually by 1 type, and may be used in combination of 2 or more type. The blending amount of the conductive agent is not particularly limited, but is preferably in the range of 5 to 40% by mass, and more preferably in the range of 5 to 20% by mass with respect to the entire highly rigid resin.

  Examples of the material of the metal shaft 2A and the metal cylinder include iron, stainless steel, and aluminum. The material of the high-rigidity resin base material 2B includes polyacetal, polyamide 6, polyamide 6 · 6, polyamide 12, polyamide 4 · 6, polyamide 6 · 10, polyamide 6 · 12, polyamide 11, polyamide MXD6, poly Butylene terephthalate, polyphenylene oxide, polyphenylene sulfide, polyethersulfone, polycarbonate, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone, polyethylene terephthalate, polyarylate, liquid crystal polymer, polytetrafluoroethylene, polypropylene, ABS resin, Examples include polystyrene, polyethylene, melamine resin, phenol resin, and silicone resin. Among these, polyacetal, polyamide 6/6, polyamide MXD6, polyamide 6/12, polybutylene terephthalate, polyphenylene ether, polyphenylene sulfide, and polycarbonate are preferable. These highly rigid resins may be used alone or in combination of two or more.

  When the shaft member is a metal shaft or a shaft having a highly rigid resin base disposed on the outside of the metal shaft, the outer diameter of the metal shaft is preferably in the range of 4.0 to 8.0 mm. Further, when the shaft member is a shaft in which a highly rigid resin base material is disposed outside the metal shaft, the outer diameter of the resin base material is preferably in the range of 10 to 25 mm. In addition, even if the outer diameter of a shaft member is enlarged by using high rigidity resin for the said shaft member, the increase in the mass of a shaft member can be suppressed.

  In the conductive elastic roller of the present invention, at least the outermost layer of the elastic layer is obtained by curing a raw material mixture containing a urethane (meth) acrylate oligomer (A), a photopolymerization initiator (B) and a conductive agent (C) by ultraviolet irradiation. It consists of an ultraviolet curable resin obtained. The raw material mixture for the outermost layer of the elastic layer is a partial ester of a (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid in addition to the components (A), (B) and (C). (D) is included. In addition, various additives can be mix | blended with the said raw material mixture, unless the objective of this invention is impaired.

The urethane (meth) acrylate oligomer (A) used in the raw material mixture for the outermost layer of the elastic layer has one (meth) acryloyloxy group (CH ₂ ═CHCOO— or CH ₂ ═C (CH ₃ ) COO—). These are compounds having a plurality of urethane bonds (—NHCOO—). The number of functional groups and molecular weight of the urethane (meth) acrylate oligomer (A) are not particularly limited. The urethane (meth) acrylate oligomer (A) can be produced, for example, by synthesizing a urethane prepolymer from a polyol and a polyisocyanate, and adding a (meth) acrylate having a hydroxyl group to the urethane prepolymer.

  The polyol used for the synthesis of the urethane prepolymer is a compound having a plurality of hydroxyl groups (OH groups). Specific examples of the polyol include polyether polyol, polyester polyol, polytetramethylene glycol, polybutadiene polyol, and alkylene oxide modification. Examples include polybutadiene polyol and polyisoprene polyol. The polyether polyol is obtained, for example, by adding an alkylene oxide such as ethylene oxide or propylene oxide to a polyhydric alcohol such as ethylene glycol, propylene glycol, or glycerin. The polyester polyol is, for example, ethylene glycol. , Diethylene glycol, 1,4-butanediol, 1,6-hexanediol, propylene glycol, trimethylolethane, trimethylolpropane and other polyhydric alcohols and adipic acid, glutaric acid, succinic acid, sebacic acid, pimelic acid, suberin It is obtained from a polyvalent carboxylic acid such as an acid. These polyols may be used alone or in a blend of two or more.

  The polyisocyanate is a compound having a plurality of isocyanate groups (NCO groups). Specifically, as the polyisocyanate, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), crude diphenylmethane diisocyanate (crude MDI), Examples include isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, hexamethylene diisocyanate (HDI), these isocyanurate-modified products, carbodiimide-modified products, and glycol-modified products. These polyisocyanates may be used alone or in a blend of two or more.

  In the synthesis of the urethane prepolymer, it is preferable to use a catalyst for urethanization reaction. Examples of the catalyst for urethanization reaction include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin thiocarboxylate, tin octenoate, monobutyltin oxide, and the like; stannous chloride, etc. Inorganic lead compounds; organic lead compounds such as lead octenoate; monoamines such as triethylamine and dimethylcyclohexylamine; diamines such as tetramethylethylenediamine, tetramethylpropanediamine, and tetramethylhexanediamine; pentamethyldiethylenetriamine, pentamethyldipropylene Triamines such as triamine and tetramethylguanidine; triethylenediamine, dimethylpiperazine, methylethylpiperazine, methylmorpholine, dimethyl Cyclic amines such as ruaminoethylmorpholine, dimethylimidazole, pyridine; alcohol amines such as dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methylhydroxyethylpiperazine, hydroxyethylmorpholine; bis (dimethylaminoethyl) Ethers, ether amines such as ethylene glycol bis (dimethyl) aminopropyl ether; organic sulfonic acids such as p-toluenesulfonic acid, methanesulfonic acid and fluorosulfuric acid; inorganic acids such as sulfuric acid, phosphoric acid and perchloric acid; sodium alcoholate Bases such as lithium hydroxide, aluminum alcoholate and sodium hydroxide; titanium compounds such as tetrabutyl titanate, tetraethyl titanate and tetraisopropyl titanate; Smus compounds; quaternary ammonium salts and the like. Of these catalysts, organotin compounds are preferred. These catalysts may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the catalyst used is preferably in the range of 0.001 to 2.0 parts by mass with respect to 100 parts by mass of the polyol.

The (meth) acrylate having a hydroxyl group to be added to the urethane prepolymer has one or more hydroxyl groups and is a (meth) acryloyloxy group (CH ₂ ═CHCOO— or CH ₂ ═C (CH ₃ ) COO—). Is a compound having one or more. The (meth) acrylate having a hydroxyl group can be added to the isocyanate group of the urethane prepolymer. Examples of the (meth) acrylate having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and pentaerythritol tri (meth) acrylate. These (meth) acrylates having a hydroxyl group may be used alone or in combination of two or more.

  The photopolymerization initiator (B) used in the raw material mixture of the outermost layer of the elastic layer is irradiated with ultraviolet rays, whereby the urethane (meth) acrylate oligomer (A) described above, and the partial ester (D) described later and It has the effect | action which starts superposition | polymerization of an acrylate monomer (E). Examples of the photopolymerization initiator (B) include 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, 2,2-dimethoxy-2-phenylacetophenone, acetophenone diethyl ketal, alkoxyacetophenone, benzyldimethyl ketal, benzophenone and 3,3-dimethyl-4-methoxybenzophenone, benzophenone derivatives such as 4,4-dimethoxybenzophenone, 4,4-diaminobenzophenone, alkyl benzoylbenzoate, bis (4-dialkylaminophenyl) ketone, benzyl, benzylmethyl ketal, etc. Benzyl derivatives of benzoin, benzoin derivatives such as benzoin and benzoin isobutyl ether, benzoin isopropyl ether, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, Thioxanthone and thioxanthone derivatives, fluorene, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6- Trimethylbenzoyl) -phenylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1,2-benzyl-2-dimethylamino-1- (morpholinophenyl) -butanone-1, etc. Is mentioned. These photoinitiators may be used individually by 1 type, and may use 2 or more types together.

  The conductive agent (C) used in the raw material mixture for the outermost layer of the elastic layer has an effect of imparting conductivity to the elastic layer. As this electrically conductive agent (C), what can permeate | transmit an ultraviolet-ray is preferable, It is preferable to use an ionic conductive agent and a transparent electronic conductive agent, and it is especially preferable to use an ionic conductive agent. Since the ionic conductive agent is dissolved in the urethane (meth) acrylate oligomer (A) and has transparency, when the ionic conductive agent is used as the conductive agent (C), the raw material mixture is applied thickly on the shaft member. Even so, the ultraviolet rays sufficiently reach the inside of the coating film, and the raw material mixture can be sufficiently cured. Here, as the ionic conductive agent, tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, modified fatty acid dimethylethylammonium and the like perchlorate, chlorate, hydrochloride, bromate Ammonium salts such as salts, iodates, borofluorides, sulfates, ethyl sulfates, carboxylates, sulfonates; alkaline metals such as lithium, sodium, potassium, calcium, magnesium, alkaline earth metals Examples include perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, trifluoromethyl sulfate, and sulfonate. In addition, transparent electronic conductive agents include fine particles of metal oxides such as ITO, tin oxide, titanium oxide, and zinc oxide; fine particles of metals such as nickel, copper, silver, and germanium: conductive titanium oxide whiskers, conductive titanium Examples include conductive whiskers such as barium acid whiskers. These electrically conductive agents may be used individually by 1 type, and may use 2 or more types together.

  The raw material mixture for the outermost layer of the elastic layer contains a partial ester (D) of a (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid. The partial ester (D) has one or more (meth) acryloyloxy groups and one or more carboxyl groups, and has an effect of improving adhesion to the coating layer. In addition, the partial ester (D) acts as a reactive diluent, that is, it can be cured with ultraviolet rays and can reduce the viscosity of the raw material mixture. This partial ester (D) may be used individually by 1 type, and may be used in combination of 2 or more type.

［式中、Ｒ¹は水素又はメチル基であり、Ｒ²は二価の基である］で表される水酸基を有する(メタ)アクリレートと、下記一般式(II)：

［式中、ｎは２以上の整数であり、Ｒ³はｎ価の基である］で表される多価カルボン酸とを部分的にエステル化して製造することができ、この場合、下記一般式(III)：

［式中、Ｒ¹、Ｒ²、Ｒ³及びｎは上記と同義であり、ｍは１以上（ｎ−１）以下の整数である］で表される部分エステルが生成する。 Although the partial ester (D) of the (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid is not particularly limited, for example, the following general formula (I):

[Wherein R ¹ is hydrogen or a methyl group, and R ² is a divalent group], and a (meth) acrylate having a hydroxyl group represented by the following general formula (II):

[Wherein, n is an integer of 2 or more, and R ³ is an n-valent group] can be produced by partially esterifying the polycarboxylic acid represented by the following general formula: Formula (III):

[Wherein R ¹ , R ² , R ³ and n are as defined above, and m is an integer of 1 or more and (n−1) or less].

The partial ester (D) is preferably a monoester of an acrylate having a hydroxyl group and a divalent carboxylic acid, that is, R ¹ is preferably hydrogen, n is preferably 2, and m is 1. Preferably there is. Examples of R ² include an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, and a bis (acryloyloxymethyl) ethylene group. Examples of R ³ include an ethylene group, a phenylene group, and a cyclohexenylene group. Methylcyclohexenylene group, cyclohexylene group, methylcyclohexylene group, norbornenediyl group, methylnorbornenediyl group and the like.

  Examples of the (meth) acrylate having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and pentaerythritol triacrylate. Among these, 2-hydroxyethyl acrylate is preferable.

  Examples of the polyvalent carboxylic acid include succinic acid, phthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, highmic acid and methylhymic acid. Among these, Succinic acid is preferred.

  Examples of the partial ester (D) of the (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid include β- (meth) acryloyloxyethyl hydrogen succinate, β- (meth) acryloyloxypropyl hydrogen succinate, β -(Meth) acryloyloxyethyl hydrogen phthalate, β- (meth) acryloyloxypropyl hydrogen phthalate, β- (meth) acryloyloxyethyl hydrogen tetrahydrophthalate, β- (meth) acryloyloxypropyl hydrogen tetrahydrophthalate, β -(Meth) acryloyloxyethyl hydrogen hexahydrophthalate, β- (meth) acryloyloxypropyl hydrogen hexahydrophthalate, β-tris (acryloyloxymethyl) ethyl hydrogen phthalate . Among these, beta-acryloyloxyethyl hydrogen succinate is preferable.

The raw material mixture for the outermost layer of the elastic layer preferably further contains an acrylate monomer (E) other than the partial ester (D). The acrylate monomer (E) is a monomer having one or more acryloyloxy groups (CH ₂ ═CHCOO—) and acts as a reactive diluent, that is, is cured by ultraviolet rays and lowers the viscosity of the raw material mixture. It is possible. The acrylate monomer (E) preferably has a functional group number of 1.0 to 10 and more preferably 1.0 to 3.5. Here, the functional group refers to an acryloyloxy group. If the number of functional groups of the acrylate monomer (E) is 1.0 or more, unreacted acrylate monomer hardly remains in the outermost layer of the elastic layer, while if it is 10 or less, the hardness of the outermost layer of the elastic layer is increased. Never too much.

  The acrylate monomer (E) preferably has a molecular weight of 100 to 2000, and more preferably 100 to 1000. If the molecular weight of the acrylate monomer (E) is 100 or more, the hardness can be adjusted and the viscosity of the compounded liquid can be adjusted while maintaining good resin properties. On the other hand, if the molecular weight is 2000 or less, the compression residual strain is good. Thus, the viscosity of the blended liquid can be adjusted.

  Examples of the acrylate monomer (E) include methoxytriethylene glycol acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, isoamyl acrylate, glycidyl acrylate, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydipropylene glycol acrylate, phenoxyethyl acrylate, Examples include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, pentaerythritol triacrylate and the like. These acrylate monomers may be used alone or in combination of two or more.

  The blending amount of the photopolymerization initiator (B) in the raw material mixture for the outermost layer of the elastic layer is a total of 100 of the urethane (meth) acrylate oligomer (A), the partial ester (D), and the acrylate monomer (E). A range of 0.2 to 5.0 parts by mass is preferable with respect to parts by mass. When the blending amount of the photopolymerization initiator (B) is 0.2 parts by mass or less, the effect of initiating UV curing of the raw material mixture is small. On the other hand, when it exceeds 5.0 parts by mass, the effect of initiating UV curing is saturated, while compression Physical properties such as residual strain are reduced, and the cost of the raw material mixture is increased.

  The blending amount of the conductive agent (C) in the outermost layer raw material mixture of the elastic layer is 100 parts by mass in total of the urethane (meth) acrylate oligomer (A), the partial ester (D), and the acrylate monomer (E). The range of 0.1 to 5.0 parts by mass is preferable. If the blending amount of the conductive agent (C) is less than 0.1 parts by mass, the conductivity of the elastic layer may be low and desired conductivity may not be imparted to the conductive elastic roller. On the other hand, if it exceeds 5.0 parts by mass, the elastic layer May be saturated, physical properties such as compressive residual strain may deteriorate, and a good image may not be obtained.

  The outermost layer raw material mixture of the elastic layer preferably has a content of the partial ester (D) of 1 to 20% by mass. If the content of the partial ester (D) is 1% by mass or more, the adhesion between the outermost layer of the elastic layer and the coating layer can be sufficiently improved. An elastic layer suitable for a conductive elastic roller having low hardness and compressive residual strain can be obtained.

  The raw material mixture for the outermost layer of the elastic layer has a mass ratio (A / E) of the urethane (meth) acrylate oligomer (A) to the acrylate monomer (E) in the range of 100/0 to 40/60. It is preferable that it exists in.

  The outermost layer raw material mixture of the elastic layer further contains a polymerization inhibitor in a total of 100 parts by mass of the urethane (meth) acrylate oligomer (A), the partial ester (D), and the acrylate monomer (E). In contrast, 0.001 to 0.2 parts by mass may be added. By adding a polymerization inhibitor, thermal polymerization before ultraviolet irradiation can be prevented. Polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, p-methoxyphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-p-cresol, butylhydroxyanisole, 3 -Hydroxythiophenol, α-nitroso-β-naphthol, p-benzoquinone, 2,5-dihydroxy-p-quinone and the like.

  The coating layer of the conductive elastic roller of the present invention is preferably made of an ultraviolet curable resin obtained by curing a raw material mixture containing a urethane (meth) acrylate oligomer and a photopolymerization initiator by ultraviolet irradiation. Here, as the urethane (meth) acrylate oligomer and the photopolymerization initiator, those used for the elastic layer can be used in the same manner, and the blending ratio can also be the same. In addition, various additives can be blended in the raw material mixture for the coating layer as long as the object of the present invention is not impaired. Examples of the additives include acrylate monomers, conductive agents, and fine particles. . Here, as the acrylate monomer and the conductive agent, those used for the elastic layer can be used in the same manner, and the blending ratio can be the same. The fine particles are preferably rubber, urethane or synthetic resin fine particles, carbon fine particles, and silica fine particles, and other inorganic fine particles. Silicone rubber, silicone resin, fluorine resin, urethane resin, polyolefin resin, epoxy resin, polystyrene Resins, urethane acrylates, melamine resins, phenol resins, (meth) acrylic resins, glassy carbon fine particles and silica fine particles are particularly preferred. By including fine particles in the raw material mixture of the coating layer, appropriate minute irregularities can be formed on the surface of the conductive elastic roller. These fine particles may be used alone or in combination of two or more. Further, the content of the fine particles is preferably in the range of 0.1 to 100 parts by mass with respect to 100 parts by mass in total of the urethane (meth) acrylate oligomer and the acrylate monomer.

  The elastic layer preferably has an Asker C hardness of 30 to 70 degrees. Here, the Asker C hardness is a value when a flat portion of a cylindrical sample having a height of 12.7 mm and a diameter of 29 mm is measured. If the Asker C hardness is 30 degrees or more, sufficient hardness can be secured as a conductive elastic roller such as a developing roller. On the other hand, if the Asker C hardness is 70 degrees or less, the low melting point toner is sufficiently aggregated and fused. Can be prevented.

  The elastic layer preferably has a compression residual strain (compression permanent strain) of 5% or less. Here, the compressive residual strain can be measured in accordance with JIS K 6262 (1997). Specifically, a cylindrical sample having a height of 12.7 mm and a diameter of 29 mm is subjected to a prescribed heat treatment condition (22 at 70 ° C.). Time), the sample can be determined by compressing it in the height direction by 25%. If the compressive residual strain of the elastic layer is 5% or less, when the conductive elastic roller is incorporated in an image forming apparatus as a developing roller, pressure contact marks due to a photosensitive drum, blade, supply roller, etc. are hardly generated on the roller surface. Thus, streak-like image defects are less likely to occur in the formed image.

The elastic layer preferably has a volume resistivity of 10 ⁴ to 10 ¹⁰ Ωcm. If the volume resistivity of the elastic layer is less than 10 ⁴ Ωcm, when used as a developing roller, there is a risk of charge leaking to the photosensitive drum, etc., or the roller itself may be destroyed by voltage, while 10 ¹⁰ Ωcm If it exceeds, ground cover is likely to occur.

  The elastic layer preferably has a thickness of 1 to 3000 μm. If the thickness of the elastic layer is 1 μm or more, the conductive elastic roller has sufficient elasticity and the damage to the toner is sufficiently small. Is sufficiently reached, the raw material mixture for the elastic layer can be reliably UV-cured, and the amount of high-priced UV-curing resin material used can be reduced.

  On the other hand, the thickness of the coating layer is preferably in the range of 5 to 30 μm. If the thickness of the coating layer is less than 5 μm, an appropriate roughness cannot be obtained, and the effect of disposing the coating layer is small. If it exceeds 30 μm, the surface of the conductive elastic roller becomes hard and the flexibility is impaired. .

The conductive elastic roller of the present invention preferably has a roller resistance of 10 ⁴ to 10 ¹⁰ Ω at an applied voltage of 100V. Here, the resistance value is obtained from a current value at that time by applying a voltage of 100 V between the shaft and the counter electrode by pressing the outer peripheral surface of the conductive elastic roller to a flat plate or a cylindrical counter electrode with a predetermined pressure. be able to.

  In the conductive elastic roller of the present invention, for example, the elastic layer raw material mixture is applied to the outer surface of the shaft member, and then irradiated with ultraviolet rays, and then the coating layer raw material mixture is applied to the outer surface of the elastic layer. After coating, it can be produced by irradiating with ultraviolet rays. Therefore, the conductive elastic roller of the present invention does not require a large amount of heat energy for the production of the elastic layer, and can produce the elastic layer in a short time. In addition, since a curing furnace, a drying line, and the like are not required for forming the elastic layer, a large facility cost is not required. Examples of the method for applying the elastic layer raw material mixture to the outer surface of the shaft member include a spray method, a roll coater method, a dipping method, and a die coating method. Examples of the light source used for ultraviolet irradiation include a mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, and a xenon lamp. The conditions for ultraviolet irradiation are appropriately selected according to the components, composition, coating amount, and the like contained in the elastic layer raw material mixture, and the irradiation intensity, integrated light amount, and the like may be appropriately adjusted.

  The conductive elastic roller of the present invention described above can be used as a developing roller, a charging roller, a toner supply roller, a transfer roller, a paper feed roller, a cleaning roller, a fixing pressure roller, and the like of an image forming apparatus. Particularly suitable as a developing roller and a charging roller.

<Image forming apparatus>
The image forming apparatus of the present invention includes the above-described conductive elastic roller, and preferably includes at least one of a developing roller and a charging roller. The image forming apparatus of the present invention is not particularly limited except that the conductive elastic roller is used, and can be manufactured by a known method.

  The image forming apparatus of the present invention will be described in detail below with reference to FIG. FIG. 2 is a partial cross-sectional view of an example of the image forming apparatus of the present invention. The image forming apparatus of the illustrated example supplies a photosensitive drum 5 holding an electrostatic latent image, a charging roller 6 for charging the photosensitive drum 5 located near (upward in the drawing), and toner 7. A toner supply roller 8, a developing roller 9 disposed between the toner supply roller 8 and the photosensitive drum 5, a stratification blade 10 provided in the vicinity of the developing roller 9 (upward in the drawing), and a photosensitive drum 5 is provided with a transfer roller 11 located in the vicinity (downward in the drawing) 5 and a cleaning roller 12 disposed adjacent to the photosensitive drum 5. The image forming apparatus of the present invention can further include a known component (not shown) that is usually used in the image layer forming apparatus.

  In the illustrated image forming apparatus, the charging roller 6 is brought into contact with the photosensitive drum 5 and a voltage is applied between the photosensitive drum 5 and the charging roller 6 to charge the photosensitive drum 5 to a constant potential. Then, an electrostatic latent image is formed on the photosensitive drum 5 by an exposure machine (not shown). Next, the photosensitive drum 5, the toner supply roller 8, and the developing roller 9 rotate in the direction of the arrow in the figure, so that the toner 7 on the toner supply roller 8 is sent to the photosensitive drum 5 through the developing roller 9. It is done. The toner 7 on the developing roller 9 is adjusted to a uniform thin layer by the stratifying blade 10 and rotates while the developing roller 9 and the photosensitive drum 5 are in contact with each other, so that the toner 7 is transferred from the developing roller 9 to the photosensitive drum 5. It adheres to the electrostatic latent image and the latent image becomes visible. The toner 7 attached to the latent image is transferred to a recording medium such as paper by the transfer roller 11, and the toner 7 remaining on the photosensitive drum 5 after the transfer is removed by the cleaning roller 12. Here, in the image forming apparatus of the present invention, at least one of the charging roller 6, the toner supply roller 8, the developing roller 9, the transfer roller 11 and the cleaning roller 12, preferably at least the charging roller 6 and the developing roller 9. On the other hand, it is possible to stably form an excellent image by using the above-described conductive elastic roller of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Example 1
Urethane acrylate oligomer “UA-334PZ [made by Shin-Nakamura Chemical Co., Ltd.]” 70.0 parts by mass, acrylate monomer “light acrylate MTG-A [methoxytriethylene glycol acrylate, functional group number = 1, molecular weight = 218, Kyoeisha Chemical Co., Ltd. 20.0 parts by mass, partial ester “NK ester A-SA [β-acryloyloxyethyl hydrogen succinate (CH ₂ ═CHCOOCH ₂ CH ₂ OCOCH ₂ CH ₂ COOH), manufactured by Shin-Nakamura Chemical Co., Ltd.] "10.0 parts by mass, photopolymerization initiator" Irgacure 184D [Ciba Specialty Chemicals Co., Ltd.] "0.5 parts by mass, ionic conductive agent" MP-100 [Akishima Chemical Co., Ltd.] "2.0 parts by mass With a stirrer, the mixture was stirred and mixed for 1 hour at a liquid temperature of 70 ° C. and 60 rpm, and the mixed liquid was filtered to obtain a UV curable resin raw material.

The above UV curable resin raw material is poured into a mold having a cavity with a depth of 12.7 mm and an inner diameter of 29 mm, covered with a quartz glass plate, and then irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 10 seconds to measure cylindrical physical properties. A UV curable resin sample was obtained. This sample had an Asker C hardness (manufactured by Kobunshi Keiki Co., Ltd.) of 47 degrees in the plane portion. Further, the compression residual strain of this sample was measured in accordance with JIS K 6262 (1997) and found to be 3.6%.

Further, a sheet sample of 2.0 mm was prepared by sandwiching the UV curable resin raw material between two quartz glass plates provided with a 2.0 mm spacer. If necessary, the sheet sample can be easily peeled by sandwiching the PTFE sheet between the quartz glass on the side opposite to the UV irradiation surface and the UV curable resin. The sample thus obtained was set in a JIS BOX type resistance measurement box, and when the resistance was measured with an applied voltage of 100 V using an Advantest resistance measuring instrument, the volume specific resistance was 8.50 × 10 ⁶ Ωcm.

Next, the above UV curable resin raw material is applied to a conductive roller base material made of polybutylene terephthalate (PBT) resin having an outer diameter of 17.0 mm into which a metal shaft having an outer diameter of 6.0 mm is inserted, with a thickness of 1500 μm using a die coater. The UV curable resin raw material was cured by spot UV irradiation. The UV-cured resin elastic layer-formed roller thus formed was further irradiated with UV at a UV irradiation intensity of 700 mW / cm ² for 5 seconds while rotating in a nitrogen atmosphere.

  On the surface of the roller with an elastic layer made of UV curable resin thus obtained, 60 parts by mass of urethane acrylate oligomer “UV3000B [manufactured by Nippon Synthetic Chemical Industry Co., Ltd.]”, morpholine acrylate “A-MO [Shin Nakamura Chemical Co., Ltd.] Co., Ltd., functional group number = 1] "40 parts by mass, and photopolymerization initiator" Irgacure 184D [Ciba Specialty Chemicals Co., Ltd.] "1 part by mass UV curable resin raw material in a roll coater It was applied and irradiated with UV to obtain a UV resin roller having a UV hardness [thickness: 10 μm] on the surface and a roller outer diameter of 20.0 mm and low hardness.

  The adhesion between the elastic layer and the coating layer of the obtained roller was tested by a JIS cross cut test (JIS K 5600-5-6: 1999). Specifically, use a predetermined jig to cut 5 vertical and horizontal grids, a total of 25 grids with a razor [made by Gillette], affix the cello tape (registered trademark), peel off the cello tape at once, and not peel off with the cello tape As a result of counting the number of grids, all 25 were not removed from the rollers.

  Furthermore, another roller produced as described above was incorporated in an electrophotographic apparatus as a developing roller, and after standing for 2 days in NN conditions (20 ° C., 50% RH), a durability test was performed in a gray color. Even when the sheets were printed, no peeling of the coating film was observed, and a good image was obtained. Furthermore, when another roller produced as described above was incorporated into an electrophotographic apparatus as a developing roller and left under HH conditions (32.5 ° C., 85% RH) for 2 days, a gray image was evaluated. Could get.

(Example 2)
A UV curable resin raw material for elastic layer having the composition shown in Table 1 was prepared, and a columnar UV curable resin sample for measuring physical properties was prepared in the same manner as in Example 1 to measure Asker C hardness and compressive residual strain. Further, a sheet sample was prepared from the UV curable resin raw material for the elastic layer in the same manner as in Example 1, and the volume resistivity was measured. Next, using the UV curable resin raw material for the elastic layer and the UV curable resin raw material for the coating layer shown in Table 1, a UV resin roller was produced in the same manner as in Example 1, and the elasticity of the obtained roller was The adhesion between the layer and the coating layer was evaluated. These results are shown in Table 1. Furthermore, another roller produced in the same manner was incorporated into an electrophotographic apparatus as a developing roller, and after standing for 2 days in NN conditions, a durability test was conducted in gray color. Even if 12,000 sheets were printed, No film peeling was observed, and a good image was obtained. Furthermore, when another roller produced in the same manner was incorporated in an electrophotographic apparatus as a developing roller and left for 2 days under HH conditions, image evaluation was performed in a gray color. As a result, a good image could be obtained.

(Example 3)
A UV curable resin raw material for elastic layer having the composition shown in Table 1 was prepared, and a columnar UV curable resin sample for measuring physical properties was prepared in the same manner as in Example 1 to measure Asker C hardness and compressive residual strain. Further, a sheet sample was prepared from the UV curable resin raw material for the elastic layer in the same manner as in Example 1, and the volume resistivity was measured. Next, using the UV curable resin raw material for the elastic layer and the UV curable resin raw material for the coating layer shown in Table 1, a UV resin roller was produced in the same manner as in Example 1, and the elasticity of the obtained roller was The adhesion between the layer and the coating layer was evaluated. These results are shown in Table 1. Furthermore, another roller produced in the same manner was incorporated into an electrophotographic apparatus as a developing roller, and after standing for 2 days in NN conditions, a durability test was conducted in gray color. Even if 12,000 sheets were printed, No film peeling was observed, and a good image was obtained. Furthermore, when another roller produced in the same manner was incorporated in an electrophotographic apparatus as a developing roller and left for 2 days under HH conditions, image evaluation was performed in a gray color. As a result, a good image could be obtained.

Example 4
A UV curable resin raw material for elastic layer having the composition shown in Table 1 was prepared, and a columnar UV curable resin sample for measuring physical properties was prepared in the same manner as in Example 1 to measure Asker C hardness and compressive residual strain. Further, a sheet sample was prepared from the UV curable resin raw material for the elastic layer in the same manner as in Example 1, and the volume resistivity was measured. Next, using the UV curable resin raw material for the elastic layer and the UV curable resin raw material for the coating layer shown in Table 1, a UV resin roller was produced in the same manner as in Example 1, and the elasticity of the obtained roller was The adhesion between the layer and the coating layer was evaluated. These results are shown in Table 1. Furthermore, another roller produced in the same manner was incorporated into an electrophotographic apparatus as a developing roller, and after standing for 2 days in NN conditions, a durability test was conducted in gray color. Even if 12,000 sheets were printed, No film peeling was observed, and a good image was obtained. Furthermore, when another roller produced in the same manner was incorporated in an electrophotographic apparatus as a developing roller and left for 2 days under HH conditions, image evaluation was performed in a gray color. As a result, a good image could be obtained.

(Example 5)
A UV curable resin raw material for elastic layer having the composition shown in Table 1 was prepared, and a columnar UV curable resin sample for measuring physical properties was prepared in the same manner as in Example 1 to measure Asker C hardness and compressive residual strain. Further, a sheet sample was prepared from the UV curable resin raw material for the elastic layer in the same manner as in Example 1, and the volume resistivity was measured. Next, using the UV curable resin raw material for the elastic layer and the UV curable resin raw material for the coating layer shown in Table 1, a UV resin roller was produced in the same manner as in Example 1, and the elasticity of the obtained roller was The adhesion between the layer and the coating layer was evaluated. These results are shown in Table 1. Furthermore, another roller produced in the same manner was incorporated into an electrophotographic apparatus as a developing roller, and after standing for 2 days in NN conditions, a durability test was conducted in gray color. Even if 12,000 sheets were printed, No film peeling was observed, and a good image was obtained. Furthermore, when another roller produced in the same manner was incorporated in an electrophotographic apparatus as a developing roller and left for 2 days under HH conditions, image evaluation was performed in a gray color. As a result, a good image could be obtained.

(Comparative Example 1)
A UV curable resin raw material for elastic layer having the composition shown in Table 1 was prepared, and a columnar UV curable resin sample for measuring physical properties was prepared in the same manner as in Example 1 to measure Asker C hardness and compressive residual strain. Further, a sheet sample was prepared from the UV curable resin raw material for the elastic layer in the same manner as in Example 1, and the volume resistivity was measured. Next, using the UV curable resin raw material for the elastic layer and the UV curable resin raw material for the coating layer shown in Table 1, a UV resin roller was produced in the same manner as in Example 1, and the elasticity of the obtained roller was The adhesion between the layer and the coating layer was evaluated. These results are shown in Table 1. Furthermore, another roller produced in the same manner was incorporated into an electrophotographic apparatus as a developing roller, and after standing for 2 days in NN conditions, a durability test was performed in gray. When 6,000 sheets were printed, it was good. When the roller was taken out and observed, peeling of the coating film was confirmed. Furthermore, when another roller produced in the same manner was incorporated in an electrophotographic apparatus as a developing roller and left for 2 days under HH conditions, image evaluation was performed in a gray color. As a result, a good image could be obtained.

(Comparative Example 2)
A UV curable resin raw material for elastic layer having the composition shown in Table 1 was prepared, and a columnar UV curable resin sample for measuring physical properties was prepared in the same manner as in Example 1 to measure Asker C hardness and compressive residual strain. Further, a sheet sample was prepared from the UV curable resin raw material for the elastic layer in the same manner as in Example 1, and the volume resistivity was measured. Next, using the UV curable resin raw material for the elastic layer and the UV curable resin raw material for the coating layer shown in Table 1, a UV resin roller was produced in the same manner as in Example 1, and the elasticity of the obtained roller was The adhesion between the layer and the coating layer was evaluated. These results are shown in Table 1. Furthermore, another roller produced in the same manner was incorporated into an electrophotographic apparatus as a developing roller, and after standing for 2 days in NN conditions, a durability test was conducted in gray color. Even if 12,000 sheets were printed, No film peeling was observed, and a good image was obtained. Furthermore, when another roller produced in the same manner was incorporated in the electrophotographic apparatus as a developing roller and left for 2 days in the HH condition, image evaluation was performed in a gray color. As a result, streaky image defects occurred. Further, when the surface of the developing roller was observed, a pressure contact mark by the developing blade was confirmed.

(Comparative Example 3)
A UV curable resin raw material for elastic layer having the composition shown in Table 1 was prepared, and a columnar UV curable resin sample for measuring physical properties was prepared in the same manner as in Example 1 to measure Asker C hardness and compressive residual strain. Further, a sheet sample was prepared from the UV curable resin raw material for the elastic layer in the same manner as in Example 1, and the volume resistivity was measured. Next, using the UV curable resin raw material for the elastic layer and the UV curable resin raw material for the coating layer shown in Table 1, a UV resin roller was produced in the same manner as in Example 1, and the elasticity of the obtained roller was The adhesion between the layer and the coating layer was evaluated. These results are shown in Table 1. Furthermore, another roller produced in the same manner was incorporated in the electrophotographic apparatus as a developing roller, and after standing for 2 days in NN conditions, a durability test was performed in gray. The coating film peeled off when 1,000 sheets were printed. Furthermore, when another roller produced in the same manner was incorporated in the electrophotographic apparatus as a developing roller and left for 2 days in the HH condition, image evaluation was performed in a gray color. As a result, streaky image defects occurred. Further, when the surface of the developing roller was observed, a pressure contact mark by the developing blade was confirmed.

UA-334PZ: manufactured by Shin-Nakamura Chemical Co., Ltd. Light acrylate MTG-A: methoxytriethylene glycol acrylate, functional group number = 1, molecular weight = 218, manufactured by Kyoeisha Chemical Co., Ltd. Light acrylate IM-A: isomyristyl acrylate, functional Radix = 1,
MW ester A-SA: β-acryloyloxyethyl hydrogen succinate, Shin-Nakamura Chemical Co., Ltd. Irgacure 184D: photopolymerization initiator, Ciba Specialty Chemicals Co., Ltd. ) MP-100: ionic conductive agent, Akishima Chemical Industry Co., Ltd. UV3000B: Nippon Synthetic Chemical Industry Co., Ltd. UX3301: Nippon Kayaku Co., Ltd. UV3200B: Nippon Synthetic Chemical Industry Co., Ltd. A-MO: Morpholine acrylate, manufactured by Shin-Nakamura Chemical Co., Ltd., functional group number = 1
IB-XA: manufactured by Kyoeisha Chemical Co., Ltd., number of functional groups = 1
Ketjen Black EC600JD: (Manufacturer) Ketjen Black International Co., Ltd. (Seller) Lion Co., Ltd.

  From Examples 1 to 5, UV curing in which a raw material mixture containing urethane (meth) acrylate oligomer (A), photopolymerization initiator (B), conductive agent (C), and partial ester (D) was cured by UV irradiation. A conductive layer comprising an elastic layer made of a mold resin and a coating layer made of an ultraviolet curable resin obtained by curing a raw material mixture containing a urethane (meth) acrylate oligomer (A) and a photopolymerization initiator (B) by ultraviolet irradiation. It can be seen that the adhesive elastic roller has high adhesion between the elastic layer and the coating layer.

  On the other hand, from Comparative Examples 1 and 3, a conductive elastic roller provided with an elastic layer made of an ultraviolet curable resin obtained by curing a raw material mixture containing no partial ester (D) by ultraviolet irradiation includes an elastic layer, a coating layer, It can be seen that the adhesion is low. Further, it can be seen from Comparative Example 2 that when the amount of the partial ester (D) is large, the compressive residual strain increases, which is not preferable. Furthermore, it can be seen from Comparative Example 3 that the conductive elastic roller provided with an elastic layer made of an ultraviolet curable resin obtained by curing a raw material mixture containing no conductive agent (C) by ultraviolet irradiation has very low conductivity. .

It is sectional drawing of an example of the electroconductive elastic roller of this invention. 1 is a partial cross-sectional view of an example of an image forming apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive elastic roller 2 Shaft member 2A Metal shaft 2B High-rigidity resin base material 3 Elastic layer 4 Coating layer 5 Photosensitive drum 6 Charging roller 7 Toner 8 Toner supply roller 9 Developing roller 10 Layering blade 11 Transfer roller 12 Cleaning roller 12

Claims (13)

In a conductive elastic roller comprising a shaft member, one or more elastic layers disposed on the radially outer side of the shaft member, and one or more coating layers disposed on the radially outer side of the elastic layer,
At least the outermost layer of the elastic layer is made of an ultraviolet curable resin obtained by curing a raw material mixture containing a urethane (meth) acrylate oligomer (A), a photopolymerization initiator (B), and a conductive agent (C) by ultraviolet irradiation,
The conductive elastic roller, wherein the raw material mixture for the outermost layer of the elastic layer further contains a partial ester (D) of (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid.   The conductive ester according to claim 1, wherein the partial ester (D) of the (meth) acrylate having a hydroxyl group and a polyvalent carboxylic acid is a monoester of an acrylate having a hydroxyl group and a divalent carboxylic acid. Elastic roller.   The partial ester (D) of (meth) acrylate having a hydroxyl group and a polycarboxylic acid is 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, and pentaerythritol triacrylate. And at least one selected from the group consisting of succinic acid, phthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid, hymic acid and methylhymic acid. The conductive elastic roller according to claim 1, wherein the conductive elastic roller is at least one monoester.   2. The conductive elastic roller according to claim 1, wherein the content of the partial ester (D) in the outermost layer raw material mixture of the elastic layer is 1 to 20 mass%.   The conductive elastic roller according to claim 1, wherein the outermost layer raw material mixture of the elastic layer further contains an acrylate monomer (E).   The conductive elastic roller according to claim 5, wherein the acrylate monomer (E) has a functional group number of 1.0 to 10 and a molecular weight of 100 to 2,000.   The conductive elastic roller according to claim 1, wherein the conductive agent (C) is an ionic conductive agent.   The raw material mixture for the outermost layer of the elastic layer is the photopolymerization initiator based on a total of 100 parts by mass of the urethane (meth) acrylate oligomer (A), the partial ester (D), and the acrylate monomer (E). 6. The conductive elastic roller according to claim 1, wherein 0.2 to 5.0 parts by mass of (B) and 0.1 to 5.0 parts by mass of the conductive agent (C) are contained. 2. The conductive layer according to claim 1, wherein the elastic layer has an Asker C hardness of 30 to 70 degrees, a compressive residual strain of 5% or less, and a volume resistivity of 10 ⁴ to 10 ¹⁰ Ωcm. Elastic roller. The shaft member is a metal shaft or a shaft in which a highly rigid resin base material is disposed outside the metal shaft;
2. The conductive elastic roller according to claim 1, wherein an outer diameter of the metal shaft is 4.0 to 8.0 mm and an outer diameter of the resin base material is 10 to 25 mm.   The conductive elastic roller according to claim 1, wherein the elastic layer has a thickness of 1 to 3000 μm.   The conductive elastic roller according to claim 1, wherein the conductive elastic roller is a developing roller or a charging roller.   An image forming apparatus using the conductive elastic roller according to claim 1.

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