Bridgestone Tire Company Limited

Hideo Nakauchi

Kazuo Naito

Shingo Kato

Sakae Inoue

Yukio Ando

Toshiyuki Osaki

There is disclosed a rubber composition having excellent vibration-insulating properties. The rubber composition comprises 45 to 75 parts by weight of at least one rubber selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber and styrene-butadiene rubber; 40 to 20 parts by weight of halogenated butyl rubber; 5 to 15 parts by weight of copolymer having a styrene content of not less than 50%; 20 to 80 parts by weight of carbon black based on 100 parts by weight of the total of the above rubbers and copolymer; and 3 to 25 parts by weight of aromatic process oil based on 100 parts by weight of the total of the above rubbers and copolymer.

Vibration-insulating rubber composition

Polyurethane products having improved flex crack resistance can be obtained by curing a mixture of (a) a polyurethane prepolymer having terminal isocyanate group and (b) at least one curative selected from polyamine and polyol to prepare a polyurethane product, and heat treating the polyurethane product at a temperature of 60.degree.-180.degree. C for 1-30,000 minutes under an atmosphere having an absolute humidity of at least 2%.

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Higashimurayama, Japan

Hideo Nakauchi