US 5,843,249 AGranted

Truck tire with cap/base construction tread

AssigneeThe Goodyear Tire & Rubber Company

InventorsJennifer Lyn Ryba, Michael Brendan Rodgers, Stanley Michael Mezynski

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Abstract

The invention relates to a truck or bus tire with a rubber tread of cap/base construction where the tread cap is composed of an emulsion polymerization prepared styrene/butadiene copolymer elastomer with a relatively random styrene content (E-SBR-A). Such E-SBR-A, in its uncured state, also has a relatively low Tg. In one aspect, the tire tread's tread cap may also be a blend of elastomers such as cis 1,4-polybutadiene and/or natural rubber together with said E-SBR-A and wherein the tread base elastomer is composed primarily of natural cis 1,4-polyisoprene rubber. In another aspect of the invention, said tread cap has a tread design composed of at least three circumferential continuous ribs designed to be road contacting, said ribs independently separated by continuous, circumferential grooves.

Claims6

Dependent claims

A pneumatic tire having a TRA rated maximum load limit of at least about 2684 lbs (1220 kg) at an inflation pressure in a range of about 80 to about 120 psi (about 550 kpa to about 830 kpa) and a tire bead diameter in a range of about 19 to about 25 inches (48 to about 64 cm) having a rubber tread of a cap/base construction characterized in that, for said cap/base tread:

(A) the tread cap is comprised of, based on 100 parts by weight rubber, (1) about 40 to 90 phr of emulsion polymerization prepared styrene/butadiene polymer having a bound styrene content of between 5 and 15 weight percent and, a Tg in a range of about -65.degree. C. to about -80.degree. C., and a random styrene distribution as evidenced by having less than ten percent of its styrene content in more than ten sequential styrene units (E-SBR-A), and correspondingly (2) about 10 to about 60 phr of at least one additional diene-based elastomer selected from at least one of homopolymers of 1,3-butadiene, homopolymers of isoprene, copolymers of 1,3-butadiene and isoprene and copolymers of 1,3-butadiene and styrene other than said E-SBR-A, and
(B) the tread base includes elastomer comprised of cis 1,4-polyisoprene natural rubber.

Dependencies are inferred from the claim text.