TREAD FOR A TIRE FORMED FROM RUBBER COMPOSITION CURED WITH PEROXIDE
A tread for a tire is disclosed that is manufactured from a rubber composition that is based upon a cross-linkable elastomer composition that includes 100 phr of two elastomer types including at least 50 phr of a styrene-butadiene copolymer (SBR) with a polybutadiene (BR) as the remainder. Such compositions may further include between 75 phr and 130 phr of a carbon black. Also included in such elastomers is a plasticizing system that includes a plasticizing resin having a glass transition temperature (Tg) of at least 25 ° C. and a plasticizing liquid. The plasticizing system is added in an effective amount to provide the cured rubber composition with a shear modulus G* measured at 60 ° C. of between 0.7 MPa and 1.6 MPa and a measured Tg of between −30 ° C. and 0 ° C. The elastomer composition is cured with a peroxide curing system.
1 . A tread for a tire, the tread comprising a rubber composition that is based upon a cross-linkable rubber composition, the cross-linkable rubber composition comprising, per 100 parts by weight of rubber (phr):
100 phr of two elastomer types including at least 50 phr of a styrene-butadiene copolymer (SBR) and a polybutadiene (BR) as the remainder;
between 75 phr and 130 phr of a carbon black;
an effective amount of a plasticizing system that includes a plasticizing resin having a glass transition temperature (Tg) of at least 25° C. and a plasticizing liquid, wherein the effective amount of the plasticizing system provides the rubber composition with a shear modulus G* measured at 60° C. of between 0.7 MPa and 1.6 MPa and a Tg of between −35° C. and 0° C.;
a peroxide curing agent.
2 . The tread of claim 1 , wherein the cross-linkable rubber composition comprises between 50 phr and 90 phr of the SBR copolymer.
3 . The tread of claim 2 , wherein the cross-linkable rubber composition comprises between 55 phr and 80 phr of the SBR copolymer.
4 . The tread of any of the preceding claims claim 1 , wherein the cross-linkable rubber composition comprises between 5 phr and 50 phr of the plasticizing liquid.
5 . The tread of claim 1 , wherein the cross-linkable rubber composition comprises between 10 phr and 30 phr of the plasticizing liquid.
6 . The tread of claim 1 , wherein the plasticizing liquid is vegetable oil having an oleic acid content of at least 70 weight percent.
7 . The tread of claim 1 , wherein the effective amount of the plasticizing system provides the rubber composition with the shear modulus G* measured at 60° C. of between 1.0 MPa and 1.4 MPa.
8 . The tread of claim 1 , wherein the effective amount of the plasticizing system provides the rubber composition with the shear modulus G* measured at 60° C. of between 0.8 MPa and 1.4 MPa.
9 . The tread of claim 1 , wherein the effective amount of the plasticizing system provides the rubber composition with the Tg of between −35° C. and −25° C.
10 . The tread of claim 1 , wherein the effective amount of the plasticizing system provides the rubber composition with the Tg of between −30° C. and −17° C.
11 . The tread of claim 1 , wherein the effective amount of the plasticizing system provides the rubber composition with the Tg of between −17° C. and 0° C.
12 . The tread of claim 1 , wherein the cross-linkable rubber composition comprises between 85 phr and 120 phr of the carbon black.
13 . The tread of claim 1 , wherein the cross-linkable rubber composition comprises between 0.8 phr and 2.4 phr of the peroxide curing agent.
14 . The tread of claim 1 , wherein the cross-linkable rubber composition further comprises a non-ionic curing coagent.
15 . The tread of claim 14 , wherein the non-ionic curing coagent is selected from allyl-cyanurates, allyl-isocyanurates, phthalates or combinations thereof.
16 . The tread of claim 14 , wherein the non-ionic curing coagent is a selected from a vinyl SBR copolymer or a vinyl BR wherein the coagent is at least 70 percent vinyl.
17 . The tread of claim 1 , wherein the cross-linkable rubber composition includes no polar curing coagent.