Abstract: This invention provides a process for producing a conductive rubber roller having small aspect ratios of inner and outer diameters, having a stable measure of its inner diameter, having uniform cell distribution and being free from non-uniformity of hardness and electrical resistance in the peripheral direction. The process has a step of continuously extruding a tube composed of a specific unvulcanized rubber composition from a rubber extruder in a microwave vulcanizing unit, and a step of foaming and vulcanizing the tube by using a microwave irradiator having a microwave irradiation zone 4 m or less in length while being transported at given speed. The foamed rubber tube has an inner diameter 20 to 35% smaller than the outer diameter of the conductive core material over the whole region in the lengthwise direction, and the conductive core material is press-fitted into the foamed rubber tube without using any adhesive.

Abstract: This invention provides a process for producing a conductive rubber roller having small aspect ratios of inner and outer diameters, having a stable measure of its inner diameter, having uniform cell distribution and being free from non-uniformity of hardness and electrical resistance in the peripheral direction. The process has a step of continuously extruding a tube composed of a specific unvulcanized rubber composition from a rubber extruder in a microwave vulcanizing unit, and a step of foaming and vulcanizing the tube by using a microwave irradiator having a microwave irradiation zone 4 m or less in length while being transported at given speed. The foamed rubber tube has an inner diameter 20 to 35% smaller than the outer diameter of the conductive core material over the whole region in the lengthwise direction, and the conductive core material is press-fitted into the foamed rubber tube without using any adhesive.

Abstract: This invention provides a process for producing a conductive rubber roller having small aspect ratios of inner and outer diameters, having a stable measure of its inner diameter, having uniform cell distribution and being free from non-uniformity of hardness and electrical resistance in the peripheral direction. The process has a step of continuously extruding a tube composed of a specific unvulcanized rubber composition from a rubber extruder in a microwave vulcanizing unit, and a step of foaming and vulcanizing the tube by using a microwave irradiator having a microwave irradiation zone 4 m or less in length while being transported at given speed. The foamed rubber tube has an inner diameter 20 to 35% smaller than the outer diameter of the conductive core material over the whole region in the lengthwise direction, and the conductive core material is press-fitted into the foamed rubber tube without using any adhesive.

Abstract: This invention provides a process for producing a conductive rubber roller having small aspect ratios of inner and outer diameters, having a stable measure of its inner diameter, having uniform cell distribution and being free from non-uniformity of hardness and electrical resistance in the peripheral direction. The process has a step of continuously extruding a tube composed of a specific unvulcanized rubber composition from a rubber extruder in a microwave vulcanizing unit, and a step of foaming and vulcanizing the tube by using a microwave irradiator having a microwave irradiation zone 4 m or less in length while being transported at given speed. The foamed rubber tube has an inner diameter 20 to 35% smaller than the outer diameter of the conductive core material over the whole region in the lengthwise direction, and the conductive core material is press-fitted into the foamed rubber tube without using any adhesive.

Abstract: A process for producing a conductive rubber roller having a conductive core material and a rubber layer provided thereon. The rubber layer contains at least acrylonitrile rubber, epichlorohydrin rubber and a blowing agent, and has a gas generation rate of from 2 ml/g·min to 4 ml/g·min at 170° C. to 230° C. The process has a vulcanizing and foaming step of vulcanizing and foaming the rubber layer by using a microwave vulcanizing furnace which provides hot air and irradiation with microwaves. A temperature of a heating atmosphere in the microwave vulcanizing furnace in the vulcanizing and foaming step is so controlled that a ratio of initial vulcanizing time T10 to initial foaming time Tp10, T10/Tp10, of the rubber layer is from 1 or more to less than 3 and the T10 is within 90 seconds.

Abstract: A conductive rubber roller having a rubber layer on a conductive core material. The rubber composition constituting the rubber layer contains a rubber component and a filler. The rubber component contains an epichlorohydrin rubber. The filler includes carbon black (A) having a nitrogen adsorption specific surface area (N2SA) of 20 m2/g to 40 m2/g and having a dibutyl phthalate (DBP) oil absorption of 80 ml/100 g to 100 ml/100 g and carbon black (B) having a nitrogen adsorption specific surface area (N2SA) of 15 m2/g or less and having a dibutyl phthalate (DBP) oil absorption of 40 ml/100 g or less. The carbon black (A) is in a content of 10 parts by mass to 30 parts by mass and the carbon black (B) is in a content of 20 parts by mass to 60 parts by mass or less, based on 100 parts by mass of the rubber component.

Abstract: This invention provides a process for producing a conductive rubber roller having small aspect ratios of inner and outer diameters, having a stable measure of its inner diameter, having uniform cell distribution and being free from non-uniformity of hardness and electrical resistance in the peripheral direction. The process has a step of continuously extruding a tube composed of a specific unvulcanized rubber composition from a rubber extruder in a microwave vulcanizing unit, and a step of foaming and vulcanizing the tube by using a microwave irradiator having a microwave irradiation zone 4 m or less in length while being transported at given speed. The foamed rubber tube has an inner diameter 20 to 35% smaller than the outer diameter of the conductive core material over the whole region in the lengthwise direction, and the conductive core material is press-fitted into the foamed rubber tube without using any adhesive.

Abstract: A process produces a conductive rubber roller having small aspect ratios of inner and outer diameters, having a stable measure of its inner diameter, having uniform cell distribution and being free from non uniformity of hardness and electrical resistance in the peripheral direction. The process has a step of continuously extruding a tube composed of a specific unvulcanized rubber composition from a rubber extruder in a microwave vulcanizing unit, and a step of foaming and vulcanizing the tube by using a microwave irradiator having a microwave irradiation zone 4 m or less in length while being transported at given speed. The foamed rubber tube has an inner diameter 20 to 35% smaller than the outer diameter of the conductive core material over the whole region in the lengthwise direction, and the conductive core material is press fitted into the foamed rubber tube without using any adhesive.

Abstract: A conductive rubber roller having a rubber layer on a conductive core material. The rubber composition constituting the rubber layer contains a rubber component and a filler. The rubber component contains an epichlorohydrin rubber. The filler includes carbon black (A) having a nitrogen adsorption specific surface area (N2SA) of 20 m2/g to 40 m2/g and having a dibutyl phthalate (DBP) oil absorption of 80 ml/100 g to 100 ml/100 g and carbon black (B) having a nitrogen adsorption specific surface area (N2SA) of 15 m2/g or less and having a dibutyl phthalate (DBP) oil absorption of 40 ml/100 g or less. The carbon black (A) is in a content of 10 parts by mass to 30 parts by mass and the carbon black (B) is in a content of 20 parts by mass to 60 parts by mass or less, based on 100 parts by mass of the rubber component.

Abstract: This invention provides a process for producing a conductive rubber roller having small aspect ratios of inner and outer diameters, having a stable measure of its inner diameter, having uniform cell distribution and being free from non-uniformity of hardness and electrical resistance in the peripheral direction. The process has a step of continuously extruding a tube composed of a specific unvulcanized rubber composition from a rubber extruder in a microwave vulcanizing unit, and a step of foaming and vulcanizing the tube by using a microwave irradiator having a microwave irradiation zone 4 m or less in length while being transported at given speed. The foamed rubber tube has an inner diameter 20 to 35% smaller than the outer diameter of the conductive core material over the whole region in the lengthwise direction, and the conductive core material is press-fitted into the foamed rubber tube without using any adhesive.