Method for producing a diene elastomer modified with a 1,3-dipolar compound

1. A process for the preparation of a diene elastomer modified by a 1,3-dipolar compound, wherein the process comprises the following stages:

a. a diene elastomer and a 1,3-dipolar compound are mixed by thermomechanical kneading in an internal mixer in order to form a diene elastomer modified by a reaction of grafting the 1,3-dipolar compound to the diene elastomer, and

b. the modified diene elastomer is extruded before mixing the modified diene elastomer with any other constituent of a rubber composition.

2. A process according to claim 1 , in which, in stage a), the diene elastomer and the 1,3-dipolar compound are kneaded until a maximum compounding temperature ranging from 110 to 180° C. is reached.

3. A process according to claim 1 , in which the set temperature of the extruder does not exceed 40° C.

4. A process according to claim 1 , in which the dipole of the 1,3-dipolar compound is a nitrile oxide.

5. A process according to claim 4 , in which the 1,3-dipolar compound comprises a benzene ring substituted by the nitrile oxide dipole.

6. A process according to claim 5 , in which the benzene ring is substituted in the position ortho to the dipole.

7. A process according to claim 1 , in which the 1,3-dipolar compound contains a group containing a 5-membered dinitrogenous and carbonylated heterocycle.

8. A process according to claim 1 , in which the diene elastomer is selected from the group consisting of polybutadienes, polyisoprenes, butadiene copolymers, isoprene copolymers and their mixtures.

9. A process according to claim 1 , in which the diene elastomer is a polyisoprene comprising more than 90 mol % of cis-1,4 bonding.

10. A process according to claim 1 , in which the diene elastomer contains an antioxidant.

11. A process according to claim 1 , in which stage b) is followed by a stage of granulation of the modified diene elastomer before mixing the modified diene elastomer with other constituents of a rubber composition.

12. A process according to claim 1 , in which, in stage a), the diene elastomer and the 1,3-dipolar compound are kneaded until a maximum compounding temperature between 140 and 170° C. is reached.

13. A process according to claim 7 , in which the 1,3-dipolar compound contains a 2-oxoimidazolidin-1-yl group.

14. A process according to claim 9 , in which the diene elastomer is a synthetic polyisoprene.

15. A process according to claim 1 , wherein after extruding the modified diene elastomer, the process includes mixing the modified diene elastomer with a reinforcing filler, a crosslinking system, and other constituents to form a final rubber composition.

16. A process according to claim 1 including extruding or calendaring the final rubber composition.

17. A process for the preparation of a rubber composition based on a diene elastomer modified by a 1,3-dipolar compound and on a reinforcing filler which comprises the following stages:

i. a diene elastomer and a 1,3-dipolar compound are mixed by thermomechanical kneading in an internal mixer in order to form a diene elastomer modified by a reaction of grafting the 1,3-dipolar compound to the diene elastomer,

ii. the modified diene elastomer is extruded before mixing the modified diene elastomer with any other constituent of a rubber composition,

iii. a reinforcing filler is incorporated in the modified diene elastomer resulting from stage ii) by thermomechanical kneading in an internal mixer.

18. A process according to claim 17 , in which a stage of granulation of the modified diene elastomer follows stage ii) and precedes stage iii).

19. A granule of diene elastomer modified by a reaction of grafting a 1,3-dipolar compound capable of being obtained by the process defined according to claim 11 .

20. A rubber composition comprising a reinforcing filler and granules of modified diene elastomer which are defined according to claim 19 .