| 主权项 |
1. A pneumatic rubber tire polybutadiene-rich rubber tread of a rib and groove configuration comprised of at least three circumferential ribs with intervening grooves comprised of, based on parts by weight per 100 parts by weight of the tread rubber (phr),
(A) about 70 to about 90, phr of specialized cis 1,4-polybutadiene rubber, and (B) about 10 to about 30 phr of natural cis 1,4-polyisopenene rubber wherein said specialized cis 1,4-polybutadiene rubber, has a microstructure comprised of about 96 to about 99 percent cis 1,4-isomeric units, a number average molecular weight (Mn) in a range of from about 150,000 to about 200,000 and a heterogeneity index (Mw/Mn) in a range of from about 2/1 to about 3.5/1, (C) about 35 to about 55 phr of rubber reinforcing carbon black; (D) about 5 to about 15 phr of precipitated silica together with from about 2 to about 5 phr of silica coupler comprised of a bis(3-triethoxysilylpropyl)polysulfide containing an average in a range of from about 3.5 to about 3.8 connecting sulfur atoms in its polysulfidic bridge; (E) a cure package comprised of sulfur and sulfur cure accelerators, wherein said sulfur cure accelerators are composed of two primary sulfur cure accelerators comprised of:
(1) a first N-cyclohexyl-2-benzothiazolesulfenamide, and(2) a second N-ter-butyl-2-benzothiazolesulfenamide; wherein a ratio of said first sulfenamide to said second sulfenamide is in a range of from about 0.4/1 to about 4/1. |
