Patent ID: 6539996
Filing Date: 2003-04-01
Classification: B60C,C08K,C08L,Y10T

Abstract:
A toroidally-shaped pneumatic tire comprised of two spaced apart, relatively inextensible bead cores, a circumferential tread designed to be ground-contacting, sidewalls extending from said bead cores to said tread and a carcass which contains said tread and sidewalls, said carcass is comprised of at least one cord reinforced rubber ply extending from bead core to bead core; wherein an insert of a rubber composition is positioned juxtapositioned to at least one of said carcass plies in the sidewall region of the tire; characterized in that said insert is a rubber composition comprised of, based upon 100 phr of elastomer(s),(A) at least one elastomer selected from homopolymers and copolymers of conjugated diene hydrocarbons having from 4 to 6 carbon atoms and copolymers of conjugated hydrocarbons having from 4 to 6 carbon atoms and styrene, (B) about 5 to about 50 phr of a particulate ultra high molecular weight polyethylene having a weight average molecular weight in a range of about 4.5 million to about 8 million with a melting point in a range of about 130Â° C. to about 150Â° C. dispersed within said rubber composition of said insert, (C) about 5 to about 40 phr of a particulate starch/plasticizer composite dispersed within said rubber composition of said insert, and (D) about 10 to about 50 phr of at least one reinforcing filler selected from the group consisting of carbon black, precipitated silica, aluminosilicate, and modified carbon black having silanol units on its surface, (E) a coupling agent for said silica, aluminosilicate and/or modified carbon black and for said starch/plasticizer composite, respectively, wherein said coupling agent has a moiety reactive with silanol units contained on the surface of the silica, aluminosilicate and/or said modified carbon black and with hydroxyl units contained in said starch/plasticizer composite, respectively, and another moiety interactive with said elastomer(s); wherein said starch is composed of amylose units and amylopectin units in a ratio of about 15/85 to about 35/65 and has a softening point in a range of about 180Â° C. to about 220Â° C.; wherein said starch/plasticizer composite has a softening point in a range of about 110Â° C. to about 170Â° C., and where the plasticizer is a polymeric plasticizer having a softening point of less than 160Â° C.; wherein said plasticizer for said starch/plasticizer composite is at least one selected from the group consisting of poly(ethylenevinyl alcohol) (EVOH), and cellulose acetate and any polymeric plasticizer able to reduce the softening point of the starch/plasticizer composite to temperatures lower than 160Â° C.