Propylene-Ethylene-Diene TerPolymer Additives for Improved Tire Tread Performance

Abstract

A tire tread composition is disclosed. The tire tread composition includes components, by weight of the composition, within the range from: 5 to 75 wt % of a diene elastomer; 0 to 40 wt % of processing oil; 20 to 80 wt % of filler; a curative agent; and 5 to 30 wt % of a propylene-ethylene-diene terpolymer containing from 2 wt % to 40 wt % of ethylene and/or C4-C20 α-olefins derived units, from 0.5 to 10 wt % of diene derived units, and having a heat of fusion, as determined by DSC, of from 0 J/g to 80 J/g.

1 . A tire tread composition comprising components, by weight of the composition, within the range from:
 5 to 75 wt % of a diene elastomer;   0 to 40 wt % of processing oil;   20 to 80 wt % of filler;   a curative agent; and   5 to 30 wt % of a propylene-ethylene-diene terpolymer containing from 2 to 40 wt % of ethylene and/or C 4 -C 20  α-olefins derived units, from 0.5 to 10 wt % of diene derived units, and having a heat of fusion, as determined by DSC, of from 0 J/g to 80 J/g.   
     
     
         2 . The tire tread composition of  claim 1 , wherein the filler is a silica-based filler. 
     
     
         3 . The tire tread composition of  claim 1 , wherein the filler is a carbon black filler. 
     
     
         4 . The tire tread composition of  claim 1 , wherein the filler is blend of silica-based filler and a carbon black filler. 
     
     
         5 . The tire tread composition of  claim 1 , wherein the propylene-ethylene-diene terpolymer contains from 0.5 to 10 wt % ethylidene norbornene. 
     
     
         6 . The tire tread composition of  claim 1 , wherein the propylene-ethylene-diene terpolymer contains from 2 wt % to 20 wt % ethylene. 
     
     
         7 . The tire tread composition of  claim 1 , wherein the propylene-ethylene-diene terpolymer contains 60 wt % to 95 wt % propylene. 
     
     
         8 . The tire tread composition of  claim 1 , wherein the Tg (° C.) of the tire tread composition is from 0 to −60. 
     
     
         9 . The tire tread composition of  claim 1 , wherein the melt flow rate (MFR) at 2.16 kg weight at 230° C. of the propylene-ethylene-diene terpolymer is from 0.2 to 10 g/10 min. 
     
     
         10 . The tire tread composition of  claim 1 , wherein the diene elastomer is a styrenic copolymer, a polybutadiene, natural rubber, a polyisoprene, a butadiene copolymer, an isoprene copolymer or blends thereof. 
     
     
         11 . A tire tread comprising the cured reaction product of the components, by weight of the composition, within the range from:
 5 to 75 wt % of a diene elastomer;   0 to 40 wt % of processing oil;   20 to 80 wt % of filler;   a curative agent; and   5 to 30 wt % of a propylene-ethylene-diene terpolymer containing from 2 to 40 wt % of ethylene and/or C 4 -C 20  α-olefins derived units, from 0.5 to 10 wt % of diene derived units, and having a heat of fusion, as determined by DSC, of from 0 J/g to 80 J/g.   
     
     
         12 . The tire tread composition of  claim 11 , wherein the filler is a silica-based filler. 
     
     
         13 . The tire tread composition of  claim 11 , wherein the filler is a carbon black filler. 
     
     
         14 . The tire tread composition of  claim 11 , wherein the filler is blend of silica-based filler and a carbon black filler. 
     
     
         15 . The tire tread composition of  claim 11 , wherein the propylene-ethylene-diene terpolymer contains from 0.5 to 10 wt % ethylidene norbornene. 
     
     
         16 . The tire tread composition of  claim 11 , wherein the propylene-ethylene-diene terpolymer contains from 2 wt % to 20 wt % ethylene. 
     
     
         17 . The tire tread composition of  claim 11 , wherein the propylene-ethylene-diene terpolymer contains 60 wt % to 95 wt % propylene. 
     
     
         18 . The tire tread composition of  claim 11 , wherein the Tg (° C.) of the tire tread composition is from 0 to −60. 
     
     
         19 . The tire tread composition of  claim 11 , wherein the melt flow rate (MFR) at 2.16 kg weight at 230° C. is from 0.2 to 10 g/10 min. 
     
     
         20 . The tire tread composition of  claim 11 , wherein the diene elastomer is a styrenic copolymer, a polybutadiene, natural rubber, a polyisoprene, a butadiene copolymer, an isoprene copolymer or blends thereof. 
     
     
         21 . A method of balancing the wet traction performance and rolling resistance in a tire tread comprising:
 combining at least a filler, a diene-elastomer, and a curative agent with one or more propylene-ethylene-diene terpolymers to form a tire tread; wherein the propylene-ethylene-diene terpolymer containing from 2 wt % to 40 wt % of ethylene and/or C 4 -C 20  α-olefins derived units, from 0.5 to 10 wt % of diene derived units, and having a heat of fusion, as determined by DSC, of from 0 J/g to 80 J/g;   effecting a cure of the components to form a tire tread; and   wherein the level of the propylene-ethylene-diene terpolymer(s) relative to the other components, and its comonomer content, can be varied to improve the balance of wet traction and rolling resistance of a tire tread.   
     
     
         22 . The method of  claim 21 , wherein the filler is a silica-based filler. 
     
     
         23 . The method of  claim 21 , comprising one propylene-ethylene-diene terpolymer; and wherein the amount of the propylene-ethylene-diene terpolymer is varied within a range from 5 wt % to 30 wt %. 
     
     
         24 . The method of  claim 21 , wherein the level of ethylene and/or C 4 -C 20  α-olefins derived units in the one or more propylene-ethylene-diene terpolymer(s) is varied within a range from 2 wt % to 40 wt %; and the level of diene (e.g., ethylidene norbornenes) varied within a range from 0.5 to 10 wt %. 
     
     
         25 . The method of  claim 24 , wherein the propylene-ethylene-diene terpolymer(s) comprise a blend of different propylene-ethylene-diene terpolymers in varying amounts, the total amount within a range from 5 wt % to 30 wt %.