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AssigneeThe Goodyear Tire & Rubber Company
InventorsBruce Raymond Hahn, George Jim Papakonstantopoulos, Xiaoping Yang, Kuo-Chih Hua
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This invention is based upon the unexpected discovery that rice husk ash silica (synthetic amorphous silica from rice husk ash) provides an exceptionally good combination of properties when used in certain tire tread rubber formulations, such as an excellent combination of traction, tread-wear, and rolling resistance. These tread rubber formulations are comprised of a blend of high cis-1,4-polybutadiene rubber and a solution styrene-butadiene rubber which is preferably functionalized with amine groups, siloxy groups, thiol groups, carboxyl groups, or groups that are reactive with hydroxyl groups present on the precipitated rice husk ash silica. The use of such rice husk silica as a reinforcing-filler in rubber formulations is also highly desirable because such silica is a sustainable resource (bio-renewable) which is derived from an agricultural waste material which would otherwise be discarded as an undesirable waste product.
A sulfur curable rubber formulation which is comprised of (1) a styrene-butadiene rubber, (2) a high cis-1,4-polybutadiene rubber, (3) rice husk ash silica, wherein the rice husk ash silica has a BET nitrogen surface area which is within the range of 120 m2/gram to 300 m2/gram, a CTAB surface area which is within the range of 100 m2/gram to 300 m2/gram, a ratio of BET to CTAB surface areas which is with the range of 0.8 to 1.3, a bulk density which is within the range of 120 grams/liter to 200 grams/liter, a loss on ignition which is within the range of 3.0% to 6.0%, and a heat loss which is within the range of 4.0% to 7.0%, (4) 2 phf to 15 phf of a silica coupling agent which comprises a hydrophobating silane and a sulfur crosslinkable silane and wherein the sulfur crosslinkable silane is present in the amount from 0.5 to 5 phf and the weight ratio of the hydrophobating silane to the sulfur crosslinkable silane ranges from 4:1 to 20:1;
Dependencies are inferred from the claim text.