Abstract: A phenol resin adhesive is applied to the outer peripheral surface of an axis body 2 and heated for baking to thereby form a undercoating layer 31. A phenol resin adhesive is further applied to the outer peripheral surface of the undercoating layer 31 to thereby form an upper coating layer 32. A rubber elastic layer-forming unvulcanized material for forming a rubber elastic layer 4 is laminated on the outer peripheral surface of the upper coating layer 32, and the rubber elastic layer forming material is vulcanized by heating to thereby form the rubber elastic layer 4, wherein the rubber elastic layer 4 and the undercoating layer 31 are adhered through the upper coating layer 32 while heated and vulcanized.

Abstract: The charging roller has a base layer formed of an electroconductive rubber composition containing (a) a polar rubber having an unsaturated bond or an ether bond, (b) an ion carrier containing one or more phosphonium salts selected from the group consisting of phosphonium salts having the formulae (1) and (2), and (c) a cross-linker, wherein the amount of (b) component ranges from 0.1 to 10 parts by mass per 100 parts by mass of the (a) component. The formula (1) represents [(H9C4)3(CnH2n+1)P]+(CF3SO2)2N—, and the formula (2) represents [(H9C4)3(CnH2n+1)P]+(CF3SO3)—.

Abstract: A charging roll includes a shaft and an ionically conductive elastic layer formed around the shaft. The ionically conductive elastic layer is formed of a rubber composition free of any electron-conductive agent and containing 0.7 to 1.0 parts by weight of a peroxide cross-linking agent per 100 parts by weight of an ion-conductive rubber. The ion-conductive rubber is formed of at least one of an epichlorohydrin rubber and a nitrile rubber, and a percentage of a rubber component in the ionically conductive elastic layer measured by thermogravimetric analysis is 90% or more by weight.

Abstract: The charging roller has a base layer formed of an electroconductive rubber composition containing (a) a polar rubber having an unsaturated bond or an ether bond, (b) an ion carrier containing one or more phosphonium salts selected from the group consisting of phosphonium salts having the formulae (1) and (2), and (c) a cross-linker, wherein the amount of (b) component ranges from 0.1 to 10 parts by mass per 100 parts by mass of the (a) component. The formula (1) represents [(H9O4)3(CnH2n+1)P]+(CF3SO2)2N—, and the formula (2) represents [(H9O4)3(CnH2n+1)P]+(CF3SO3)—.

Abstract: A charging roll includes a shaft and an ionically conductive elastic layer formed around the shaft. The ionically conductive elastic layer is formed of a rubber composition free of any electron-conductive agent and containing 0.7 to 1.0 parts by weight of a peroxide cross-linking agent per 100 parts by weight of an ion-conductive rubber. The ion-conductive rubber is formed of at least one of an epichlorohydrin rubber and a nitrile rubber, and a percentage of a rubber component in the ionically conductive elastic layer measured by thermogravimetric analysis is 90% or more by weight.

Abstract: A roll has a base material layer, a front surface layer, and stress relaxation layer. The base material layer is made of low hardness rubber material and provided on an outer circumference of a metal core. The stress relaxation layer is provided on the base material layer and made of material which is at least higher in hardness than the base material layer and larger in stretch than the front surface layer. The front surface layer is made of resin material and provided on the stress relaxation layer. The stress relaxation layer is made of rubber material containing self-crosslinking resin. The stress relaxation layer has a thickness in a range of from 5 to 50 &mgr;m, and stress not lower than 5 MPa at 10% stretch.

Abstract: A roll has a base material layer, a front surface layer, and stress relaxation layer. The base material layer is made of low hardness rubber material and provided on an outer circumference of a metal core. The stress relaxation layer is provided on the base material layer and made of material which is at least higher in hardness than the base material layer and larger in stretch than the front surface layer. The front surface layer is made of resin material and provided on the stress relaxation layer. The stress relaxation layer is made of rubber material containing self-crosslinking resin. The stress relaxation layer has a thickness in a range of from 5 to 50 &mgr;m, and stress not lower than 5 MPa at 10% stretch.

Abstract: A conductive roll for an electrophotographic apparatus, which eliminates deposition unevenness onto the roll surface, inhibits occurrence of non-uniform roll resistance value, and gives a satisfactory image free from density unevenness. The surface of the conductive roll is corona-treated by arranging the conductive roll oppositely to, and in parallel with a discharging electrode, and impressing a voltage onto the electrode while rotating the conductive roll. With the conductive roll subjected to a corona treatment of the roll surface, deposition unevenness onto the roll surface is eliminated, a uniform roll resistance value is maintained throughout the entire surface even after use for a long period of time, thus permitting maintenance of stable properties.