| 摘要 |
PROBLEM TO BE SOLVED: To reduce an unevenness of a volumetric intrinsic resistance value by forming a rubber layer obtained by mixing water soluble inorganic or organic fine powder together with an electroconductive substance and/or ion conductive substance with a solid or liquid-like rubber on a periphery of a mandrel, vulcanizing it, then eluting to remove the powder to form a semiconductive sponge layer. SOLUTION: An ethylene propylene rubber is entangled with a kneading roll, predetermined mixed chemicals of a conductive carbon black 2 except a urea powder, zinc oxide, powder sulfur and the like are sequentially mixed, sufficiently dispersed to form a rubber mixture 1. The urea powder 5 is mixed, and left to stand for one night to be aged. Then, the mixture 1 is supplied to an extruder regulated at its temperature, extruded in a hose state, and completed for vulcanization by a vulcanization can. It is then dipped in a warm water, and the powder 5 in the rubber hose is eluted and removed. Then, it is dried in an oven, and to a spongy hose in which distance between particles of the carbon black particles 2 are not altered but air gaps 6 communicate with each other. A sponge layer having fine and uniform bubbles is provided, and an unevenness of a volumetric intrinsic resistance value can be reduced. |
