Rubber compound for tire tread and method for the preparation thereof
View Patent ↗A crosslinkable or crosslinked rubber composition is described which includes a diene elastomer having a mass content of cyclic vinyl units of greater than 15%, and which may be used to form a tire tread. Also described is a tire tread and a tire incorporating the tread. The composition contains a linear or branched diene elastomer derived from at least one conjugated diene, and a reinforcing filler. The elastomer has cyclic vinyl units according to a mass content of greater than or equal to 15% and a number-average molecular weight of from 30,000 to 350,000 g/mol. The elastomer may be obtained by anionic polymerization of one or more monomers including a conjugated diene in an inert hydrocarbon solvent with a catalytic system including an organolithium initiator and a polar agent with several heteroatoms. The reaction may be performed batchwise where the polar agent:initiator molar ratio is greater than 8, or continuously where the polar agent:initiator molar ratio is greater than or equal to 3.
1. A tire tread which comprises a crosslinkable or crosslinked rubber composition comprising a linear or branched diene elastomer resulting from at least one conjugated diene, and a reinforcing filler, wherein said elastomer comprises cyclic vinyl units according to a mass content of greater than or equal to 15% and has a number-average molecular weight ranging from 30,000 to 350,000 g/mol and a polydispersity index of less than 3.
2. The tire tread according to claim 1 , which consists of said rubber composition.
3. A tire which comprises a tread according to claim 1 .
4. The tire tread according to claim 1 , wherein said number-average molecular weight falls within a range of from 60,000 to 350,000 g/mol.
5. The tire tread according to claim 1 , wherein said number-average molecular weight falls within a range of from 100,000 to 300,000 g/mol.
6. The tire tread according to claim 1 , wherein said mass content of cyclic vinyl units is greater than or equal to 20%.
7. The tire tread according to claim 1 , wherein said elastomer comprises a mass fraction of units resulting from conjugated dienes of greater than 30%.
8. The tire tread according to claim 1 , wherein said elastomer is a 1,3-butadiene homopolymer or a copolymer of 1,3-butadiene and a vinyl aromatic comonomer.
9. The tire tread according to claim 1 , wherein said elastomer is present in a quantity of greater than or equal to 50 parts by weight per hundred parts of elastomer(s).
10. The tire tread according to claim 1 , wherein said elastomer is present in a quantity equal to 100 phr.
11. The tire tread according to claim 1 , wherein said reinforcing filler comprises an inorganic reinforcing filler.
12. The tire tread according to claim 1 , wherein the mass fraction of said inorganic reinforcing filler is greater than or equal to 50%.
13. The tire tread according to claim 1 , wherein the mass fraction of said inorganic reinforcing filler is equal to 100%.
14. The tire tread according to claim 1 , wherein the inorganic reinforcing filler is silica.
15. The tire tread according to claim 1 , wherein said elastomer is branched by means of a starring agent.
16. The tire tread according to claim 1 , where the starring agent is tris (2,4-di-tert.-butylphenyl) phosphate.