An object of the present invention is to provide a rubber composition which not only realizes sufficiently low heat generation properties but also exhibits more excellent crack growth resistance than the conventional rubber composition. The rubber composition contains in 100 mass% of rubber components thereof: 20-80 mass% of natural rubber in which the total nitrogen content in natural rubber latex is in the range of 0.1 mass% to 0.4 mass% (exclusive of 0.1 mass% and inclusive of 0.4 mass%); and butadiene-based polymer having cis content of 90% or higher.
本发明的目的是提供一种橡胶组合物,它不仅具有足够低的发热性能,而且比传统橡胶组合物具有更优异的抗裂纹生长性能。该橡胶组合物含有 100 质量%的橡胶成分:20-80 质量%的
天然橡胶,其中天然胶乳中的总氮含量在 0.1 质量%至 0.4 质量%(不含 0.1 质量%,含 0.4 质量%)之间;以及顺式含量为 90% 或更高的
丁二烯基聚合物。