Abstract: A rubber composition containing no reinforcing agent, which comprises (A) 55 to 95 parts by weight of an ethylene-?-olefin-non-conjugated diene copolymer rubber, (B) 5 to 45 parts by weight of a natural rubber, and (C) 0.1 to 15 parts by weight of an organic peroxide, wherein the total amount of the components (A) and (B) is 100 parts by weight; a process for producing a rubber composition comprising the steps of (1) kneading at least said components (A) and (B), and (2) mixing at least the kneaded product with said component (C); a process for producing a molded article containing a vulcanized rubber composition, which comprises the above kneading step (1), the above mixing step (2), and the step (3) of molding the rubber composition at elevated temperature; and a vibration-proof material which comprises a molded article containing a vulcanized rubber composition produced according to the above-mentioned process.

Abstract: A vibration damping rubber composition capable of exhibiting an excellent vibration damping property comprising: (A) a diene rubber; (B) a bismaleimide compound represented by the following general formula (1); wherein n denotes an integer of 4 to 12; and (C) a vulcanization accelerator; wherein said rubber composition does not contain elemental sulfur as a raw material for a vulcanizing agent.

Abstract: A rubber injection molding device comprising: a mold hang a molding cavity therein; an injecting machine including an injection cylinder having an injection chamber for storing a rubber therein, and an injection plunger for injecting the rubber from the injection chamber into the molding cavity by means of an advancement of the injection plunger; a feed machine having a feed cylinder with a feed aperture formed at a tip end thereof and connected with the injection chamber through a feed duct, and being adapted to feed into the injection chamber, through the feed duct the rubber in a mixed state, and a pushing assembly which pushes into the injection chamber the rubber that remains within the feed duct after a feed operation of the rubber by the feed machine. A manufacturing method of a rubber product by using the molding device is also disclosed.

Abstract: A heat-resistant vibration damping rubber composition wherein 20-80 parts by weight of a powder of silica having a BET specific surface area of 20-70 m2/g is mixed with 100 parts by weight of an ethylene-propylene-diene rubber material, and a sulfur-containing silane coupling agent and a mercapto-based silane coupling agent are both mixed with the ethylene-propylene-diene rubber.

Abstract: A vibration damping rubber composition capable of exhibiting an excellent vibration damping property comprising: (A) a diene rubber; (B) a bismaleimide compound represented by the following general formula (1); wherein n denotes an integer of 4 to 12; and (C) a vulcanization accelerator; wherein said rubber composition does not contain elemental sulfur as a raw material for a vulcanizing agent.

Abstract: A heat-resistant vibration damping rubber composition wherein 20-80 parts by weight of a powder of silica having a BET specific surface area of 20-70 m2/g is mixed with 100 parts by weight of an ethylene-propylene-diene rubber material, and a sulfur-containing silane coupling agent and a mercapto-based silane coupling agent are both mixed with the ethylene-propylene-diene rubber.