Butyl rubber compounds comprising a mixed modifier system

Abstract

Rubber compounds containing a halobutyl elastomer, at least one additional elastomer, a mineral filler and at least a three component mixed modifier system comprising a silane compound, a phosphine compound and an additive containing at least one hydroxyl group and a functional group containing a basic amine. A process for preparing the compounds is also disclosed. The compounds are particularly useful in tire treads and exhibit improved processability, traction, rolling resistance and wear properties.

1 . A rubber compound comprising a halobutyl elastomer, at least one additional elastomer, a mineral filler, and a mixed modifier system comprising a silane and a phosphine. 
     
     
         2 . The rubber compound according to  claim 1 , wherein the halobutyl elastomer is selected from a chlorobutyl elastomer or a bromobutyl elastomer. 
     
     
         3 . The rubber compound according to  claim 1 , wherein the halobutyl elastomer comprises a halogenated copolymer of at least an isoolefin and a conjugated diolefin. 
     
     
         4 . The rubber compound according to  claim 3 , wherein the isoolefin comprises isobutylene and wherein the conjugated diolefin comprises isoprene. 
     
     
         5 . The rubber compound according to  claim 1 , wherein the halobutyl elastomer comprises a halogenated terpolymer of an isoolefin, a conjugated diolefin, and a vinyl aromatic monomer. 
     
     
         6 . The rubber compound according to  claim 5 , wherein the isoolefin comprises isobutylene, the conjugated diene comprises isoprene and the vinyl aromatic monomer comprises p-methylstyrene. 
     
     
         7 . The rubber compound according to  claim 1 , wherein the additional elastomer comprises BR, SBR, NBR, NR, ENR or mixtures thereof. 
     
     
         8 . The rubber compound according to  claim 1 , wherein the mineral filler comprises silica. 
     
     
         9 . The rubber compound according to  claim 8 , wherein the mineral filler comprises a highly dispersive silica. 
     
     
         10 . The rubber compound according to  claim 1 , wherein the silane comprises an aminosilane or a sulphur-containing silane. 
     
     
         11 . The rubber compound according to  claim 10 , wherein the silane is selected from the group consisting of bis[3-(triethoxysilyl)propyl]-monosulfane, bis[3(triethoxysilyl)propyl]disulfane, bis[3-(triethoxysilyl)propyl]trisulfane bis[3(triethoxysilyl)propyl]tetrasulfane, bis[2-(triethoxysilyl)ethyl]-tetrasulfane, 3-(triethoxysilyl)propanthiol, and mixtures thereof. 
     
     
         12 . The rubber compound according to  claim 1 , wherein the phosphine is selected from the group consisting of trimethylphosphine, triethylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, and mixtures thereof. 
     
     
         13 . A rubber compound according to  claim 1 , wherein the phosphine is present in the range of 0.1 to 6.0 phr based on the molar mass of the phosphine. 
     
     
         14 . A rubber compound according to  claim 1 , wherein the silane is present in the range of 0.1 to 15.0 phr based on the molar mass of the silane. 
     
     
         15 . A rubber compound according to  claim 1 , wherein the phosphine comprises triphenylphosphine and is present in the range of 0.1 to 6.0 phr based on the molar mass of triphenylphosphine, and wherein the silane comprises bis[3(triethoxysilyl)propyl]tetrasulfane and is present in the range of 0.1 to 15.0 phr based on the molar mass of bis[3(triethoxysilyl)propyl]tetrasulfane. 
     
     
         16 . A rubber compound according to  claim 1 , wherein the tan delta at 0° C. is greater than 0.325, wherein the tan delta at 60° C. is less than 0.120, wherein the abrasion volume loss (DIN) is less than 165 mm 3 , and wherein the tensile at break values are greater than 13.0 MPa. 
     
     
         17 . A process for preparing a rubber compound comprising admixing a halobutyl elastomer, at least one additional elastomer, a mineral filler and a mixed modifier system comprising a silane, and a phosphine. 
     
     
         18 . The process according to  claim 17 , wherein the components of the mixed modifier system are pre-mixed. 
     
     
         19 . The process according to  claim 17 , wherein the components of the mixed modifier system are admixed with a pre-mixed combination of the halobutyl elastomer, the at least one additional elastomer and the mineral filler.