| 摘要 |
Disclosed is a rubber composition for a belt, which is suitable for an industrial rubber belt having less energy loss and excellent durability including flex crack growth resistance. Specifically disclosed is a rubber composition for a belt, which comprises: 90 to 5 mass% of a vinyl-cis-polybutadiene rubber (A) comprising 1 to 30 mass% of a specific syndiotactic-1,2-polybutadiene crystal fiber (b) and 99 to 70 mass% of a cis-polybutadiene rubber (a), wherein the syndiotactic-1,2-polybutadiene crystal fiber (b) has an average fiber length of 200 nm or less and an average fiber aspect ratio of 10 or less, contains crystal fibers having fiber length of 200 nm or less at a density of 90 fibers or more per 25 [mu]m, and has a melting point of 170 DEG C or higher; 10 to 95 mass% of a diene rubber (B) which is different from the component (A); and a rubber reinforcing agent (C) in an amount of 20 to 70 parts by mass relative to 100 parts by mass of the total amount of the rubber components (A) and (B), wherein the rubber reinforcing agent (C) comprises at least carbon black and silica, and the content of silica in the rubber reinforcing agent (C) is 70 mass% or less. |
