Rubber composition
A rubber composition having an adhesion to a composition based on natural rubber, the composition being at least based on 5 to 95 phr of polyisoprene comprising a content by weight of 1,4-cis bonds of at least 90% of the weight of the polyisoprene; 5 to 95 phr of copolymer of ethylene and of a 1,3-diene of formula CH 2 ═CR—CH═CH 2 , the ethylene units in the copolymer representing more than 50 mol % of the monomer units of the copolymer, the symbol R representing a hydrocarbon chain having 3 to 20 carbon atoms; and a crosslinking system. Also disclosed is a tire, in particular a tire provided with a sidewall, comprising this composition.
1. A rubber composition at least based on:
5 to 95 phr of polyisoprene comprising a content by weight of 1,4-cis bonds of at least 90% of the weight of the polyisoprene;
5 to 95 phr of copolymer of ethylene and of a 1,3-diene of formula (I), the ethylene units in the copolymer representing more than 50 mol % of the monomer units of the copolymer,
CH 2 ═CR—CH═CH 2 (I),
the symbol R representing a hydrocarbon chain having 3 to 20 carbon atoms; and
a crosslinking system.
2. The rubber composition according to claim 1 , wherein the copolymer contains ethylene units which represent between 50 mol % and 95 mol % of the monomer units of the copolymer.
3. The rubber composition according to claim 1 , wherein the copolymer contains units of the 1,3-diene of 1,2 or 3,4 configuration which represent more than 50 mol % of the units of the 1,3-diene.
4. The rubber composition according to claim 1 , wherein 1,3-diene is myrcene or β-farnesene.
5. The rubber composition according to claim 1 , wherein the copolymer has a glass transition temperature below −35° C.
6. The rubber composition according to claim 1 , wherein a content of the copolymer is within a range extending from 15 to less than 50 phr.
7. The rubber composition according to claim 1 , wherein the polyisoprene comprises a content by weight of 1,4-cis bonds of at least 98% of the weight of the polyisoprene.
8. The rubber composition according to claim 1 , wherein the polyisoprene is selected from the group consisting of natural rubber, synthetic polyisoprenes and mixtures thereof.
9. The rubber composition according to claim 1 , wherein the copolymer has a glass transition temperature between −90° C. and −35° C.
10. The rubber composition according to claim 1 , further comprising a reinforcing filler.
11. The rubber composition according to claim 10 , wherein the reinforcing filler comprises mainly carbon black.
12. The rubber composition according to claim 10 , wherein a content of reinforcing filler is within a range extending from 15 to 80 phr.
13. The rubber composition according to claim 1 , wherein a content of the polyisoprene is within a range extending from more than 50 to 85 phr, and a content of the copolymer is within a range extending from 15 to less than 50 phr, and further comprising a reinforcing filler comprising mainly carbon black.
14. A tire comprising the rubber composition according to claim 1 .
15. The tire according to claim 14 , wherein the rubber composition is present in at least one sidewall of the tire.