A tire inner liner having a rubber composition based on at least one butyl rubber, a reinforcing filler, graphite and a plasticizing system. The plasticizing system comprises a hydrocarbon plasticizing resin, the glass transition temperature T g of which is above 20° C. and the softening point of which is below 170° C. A process for producing such a composition for a tire inner liner comprises incorporating into a diene elastomer, in a mixer: a reinforcing filler, graphite, and a plasticizing system, by thermomechanically mixing all the ingredients, one or more times, until a maximum temperature between 110° C. and 190° C. is reached; cooling the mixture down to a temperature below 100° C.; then incorporating a crosslinking system; and mixing everything until a maximum temperature below 110° C. is reached.
1. A tire inner liner having a rubber composition based on at least one butyl rubber, a reinforcing filler and a plasticizing system, wherein the composition includes graphite and the plasticizing system comprises a hydrocarbon plasticizing resin, the glass transition temperature T g of which is above 20° C. and the softening point of which is below 170° C.
2. The inner liner according to claim 1 , wherein the elastomeric matrix of the rubber composition comprises predominantly one butyl rubber or predominantly one blend of several butyl rubbers.
3. The inner liner according to claim 2 , wherein the elastomeric matrix of the rubber composition comprises only a butyl rubber or a blend of several butyl rubbers.
4. The inner liner according to claim 2 , wherein the elastomeric matrix of the rubber composition comprises one or more other diene elastomers.
5. The inner liner according to claim 4 , wherein the elastomeric matrix of the rubber composition comprises one or more other essentially unsaturated diene elastomers.
6. The inner liner according to claim 1 , wherein the butyl rubber is an isobutene/isoprene copolymer.
7. The inner liner according to claim 1 , wherein the butyl rubber is a brominated polyisobutylene.
8. The inner liner according to claim 1 , wherein the butyl rubber is a chlorinated polysisobutylene.
9. The inner liner according to claim 4 , wherein the butyl rubber is blended with an isoprene polymer.
10. The inner liner according to claim 1 , wherein the reinforcing filler comprises carbon black.
11. The inner liner according to claim 10 , wherein the carbon black content is greater than 30 phe.
12. The inner liner according to claim 10 , wherein the carbon black content is between 30 and 120 phe.
13. The inner liner according to claim 10 , wherein the carbon black content is between 30 and 70 phe.
14. The inner liner according to claim 10 , wherein the carbon black content is between 35 and 60 phe.
15. The inner liner according to claim 1 , wherein the reinforcing filler comprises a reinforcing inorganic filler.
16. The inner liner according to claim 15 , wherein the reinforcing inorganic reinforcing filler is silica.
17. The inner liner according to claim 1 , wherein the hydrocarbon plasticizing resin has a T g of above +30° C.
18. The inner liner according to claim 1 , wherein the hydrocarbon plasticizing resin content is between 2 and 35 phe.
19. The inner liner according to claim 18 , wherein the hydrocarbon plasticizing resin content is between 5 and 25 phe.
20. The inner liner according to claim 1 , wherein the hydrocarbon plasticizing resin is chosen from the group formed by cyclopentadiene (CPD) or dicyclopentadiene (DCPD) homopolymer or copolymer resins, terpene homopolymer or copolymer resins, C 5 -cut homopolymer or copolymer resins and blends of these resins.
21. The inner liner according to claim 20 , wherein the copolymer resins are chosen from the group formed by (D)CPD/vinylaromatic copolymer resins, (D)CPD/terpene copolymer resins, (D)CPD/C 5 -cut copolymer resins, terpene/vinylaromatic copolymer resins, C 5 -cut/vinylaromatic copolymer resins and blends of these resins.
22. The inner liner according to claim 1 , wherein the hydrocarbon plasticizing resin is chosen from the group formed by (D)CPD homopolymer resins, (D)CPD/stirene copolymer resins, polylimonene resins, limonene/stirene copolymer resins, limonene/D(CPD) copolymer resins, C 5 -cut/stirene copolymer resins, C 5 -cut/C 9 -cut copolymer resins and blends of these resins.
23. The inner liner according to claim 22 , wherein the hydrocarbon resin is a polylimonene resin.
24. The inner liner according to claim 22 , wherein the hydrocarbon resin is a C 5 -cut/stirene copolymer resin.
25. The inner liner according to claim 22 , wherein the hydrocarbon resin is a C 5 -cut/C 9 -cut copolymer resin.
26. The inner liner according to claim 1 , wherein the graphite is in a lamellar form.
27. The inner liner according to claim 1 , wherein the graphite is a natural graphite.
28. The inner liner according to claim 1 , wherein the graphite is an expanded graphite.
29. The inner liner according to claim 1 , wherein the graphite is a synthetic graphite.
30. The inner liner according to claim 1 , wherein the graphite comprises a natural graphite blend and/or an expanded graphite blend and/or a synthetic graphite blend.
31. The inner liner according to claim 1 , wherein the graphite liner is between 3 and 50 phe.
32. The inner liner as claimed in claim 31 , wherein the graphite content is between 5 and 30 phe.
33. The inner liner according to claim 1 , wherein the composition contains a blend of several graphites.
34. The inner liner according to claim 1 , wherein the composition contains one or more inert fillers.
35. A tire that includes an inner liner according to claim 1 .
36. A process for producing a composition for a tire inner liner based on at least one butyl rubber, a reinforcing filler and a plasticizing system, wherein the composition also includes graphite and wherein the plasticizing system comprises a hydrocarbon plasticizing resin, the glass transition temperature T g of which is above 20° C. and the softening point of which is below 170° C., said process comprising the steps of:
incorporating into a diene elastomer, in a mixer; a reinforcing filler, graphite, and a plasticizing system, by thermomechanically mixing all the ingredients, one or more times, until a maximum temperature between 110° C. and 190° C. is reached;
cooling the mixture down to a temperature below 100° C.;
then incorporating a crosslinking system; and
mixing everything until a maximum temperature below 110° C. is reached.