PURPOSE: To prevent the blooming of rubber after vulcanization and to maintain durability over a long period of time by adding a vulcanizing agent made of a peroxide to ethylene-propylene copolymerized rubber in a specified ratio.

CONSTITUTION: A vulcanizing agent. made of a peroxide is added by 3-6 pts.wt., preferably 3.2-4.0 pts.wt. to 100 pts.wt. ethylene-propylene copolymer for a paper feeding roll or a conveying roll. The amt. of the peroxide to be added is calculated by considering the purity of the peroxide to be 100%, and if the purity of the peroxide is 40%, the peroxide is added by 7.5-15 pts.wt., preferably 8-10 pts.wt. An ethylene-propylene-unconjugated diene terpolymer obtd. by introducing unconjugated diene as a 3rd component having unsaid. bonds into the ethylene- propylene copolymer may be used in place of the copolymer and the 3rd component is, e.g. dicyclopentadiene.