Rubber composition comprising a highly saturated diene elastomer
The present invention relates to a rubber composition based on a reinforcing filler and on an elastomer matrix comprising a highly saturated diene elastomer comprising at least five distinct units of A, B, C, D and E distributed randomly within the elastomer at respective molar fractions of m %, n %, o %, p % and q %, where m+n+o+p+q=100; m≥50; n+o+p+q≥10; and 15≥p+q≥2. This rubber composition enables a satisfactory degree of stiffness to be reached while maintaining hysteresis properties acceptable for use in the manufacture of tires for running vehicles.
1. A rubber composition comprising a reinforcing filler and an elastomer matrix comprising a highly saturated diene elastomer,
wherein the highly saturated diene elastomer comprises at least units of A, B, C, D and E, distributed randomly within the highly saturated diene elastomer:
wherein R1 and R2, which are identical or different, represent a hydrogen atom, a methyl radical or a phenyl radical, which is substituted or unsubstituted in the ortho, meta or para position by a methyl radical,
wherein (D) is a divalent hydrocarbon-based ring with 6 carbon atoms of 1,2-cyclohexane type,
wherein (E) is a divalent hydrocarbon-based ring with 6 carbon atoms of 1,4-cyclohexane type,
wherein m, n, o, p and q are numbers ranging from 0 to 100, and
wherein the highly saturated diene elastomer satisfies the following:
m+n+o+p+q=100,
m≤50,
n+o+p+q≤10, and
15≤p+q≤2.
2. The rubber composition according to claim 1 , wherein the highly saturated diene elastomer further comprises units of (F)
wherein R7 is an alkyl radical having from 1 to 4 carbon atoms or an aryl radical, and
wherein the highly saturated diene elastomer satisfies the following:
m+n+o+p+q+r=100,and
25≥r≥0.
3. The rubber composition according to claim 1 , wherein R1 and R2 are each a hydrogen atom.
4. The rubber composition according to claim 1 , wherein the highly saturated diene elastomer satisfies as least one of the following:
m≥65,
n+o+p+q≥15,
10≤p+q≤2,
1≤n/(o+p+q), and
when q is not zero, 20≤p/q≤1.
5. The rubber composition according to claim 4 , wherein the highly saturated diene elastomer fulfils all of the following:
m≤65,
n+o+p+q≥15,
10≤p+q≤2,
1≤n/(o+p+q), and
when q is not zero, 20≤p/q≤1.
6. The rubber composition according to claim 4 , wherein n+o+p+q≤20.
7. The rubber composition according to claim 1 , wherein the elastomer matrix consists solely of the highly saturated diene elastomer.
8. The rubber composition according to claim 1 , wherein the elastomer matrix comprises at least 40 phr of the highly saturated diene elastomer and at most 60 phr of at least one other diene elastomer.
9. The rubber composition according to claim 1 , wherein the reinforcing filler comprises carbon black.
10. The rubber composition according to claim 9 , wherein the reinforcing filler consists of 100% of carbon black.
11. The rubber composition according to claim 1 , wherein the reinforcing filler comprises an inorganic reinforcing filler other than carbon black.
12. The rubber composition according to claim 11 , wherein the reinforcing filler comprises silica.
13. A process for preparing a rubber composition according to claim 1 , said process comprising the steps of:
(a) thermomechanically working, by kneading in one or more stages, to incorporate base constituents of the rubber composition into the elastomer matrix comprising the highly saturated diene elastomer at a maximum temperature of between 130° C. and 200° C.,
wherein the base constituents do not include a crosslinking system or an adhesion promoter, if present; and then
(b) mechanically working to incorporate the crosslinking system and the adhesion promoter, if present, at a temperature lower than said maximum temperature of step (a).
14. The process according to claim 13 , wherein the maximum temperature for step (a) is between 145° C. and 185° C.
15. The process according to claim 13 , wherein the maximum temperature for step (b) is lower than 120° C.
16. The process according to claim 13 further comprising the step of preparing the highly saturated diene elastomer.
17. A semi-finished article comprising a rubber composition according to claim 1 .
18. A tire incorporating a semi-finished article according to claim 17 .
19. The tire according to claim 18 , wherein the semi-finished article is a tread.