Tire Having a Ply Border Liner With Low Hysteresis

1 . A tire comprising at least one border rubber for one end of a reinforcing element or ply, the border rubber having a composition based on at least one diene elastomer, a reinforcing filler and a vulcanization system, wherein the composition further comprises graphite, in such a way that:

the reinforcing filler content is equal to (A−X) phr and the graphite content is between X/6 and 2×/3 phr;

A being a number between 20 and 120;

X being a number between 4 and 48; and

X and A satisfying the following relationship: X<0.4A.

2 . The tire according to claim 1 , wherein the composition of the border rubber includes graphite with a content between 2 and 30 phr.

3 . The tire according to claim 1 , wherein the composition of the border rubber includes graphite with a content between 3 and 20 phr.

4 . The tire according to claim 1 , wherein the graphite content is equal to X/2.

5 . The tire according to claim 1 , wherein the graphite content is equal to X/6.

6 . The tire according to claim 1 , wherein the diene elastomer is selected from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers and blends of these elastomers.

7 . The tire according to claim 1 , wherein the diene elastomer is an isoprene elastomer.

8 . The tire according to claim 7 , wherein the diene elastomer comprises more than 40 phr natural rubber and/or synthetic polyisoprene.

9 . The tire according to claim 1 , wherein the graphite is in lamellar form.

10 . The tire according to claim 1 , wherein the graphite is a natural graphite.

11 . The tire according to claim 1 , wherein the graphite is an expandable natural graphite.

12 . The tire according to claim 1 , wherein the graphite is an expanded graphite.

13 . The tire according to claim 1 , wherein the graphite is a synthetic graphite.

14 . The tire according to claim 1 , wherein the graphite comprises a blend of natural graphite and/or expandable natural graphite and/or expanded graphite and/or synthetic graphite.

15 . The tire according to claim 1 , wherein the reinforcing filler comprises carbon black.

16 . The tire according to claim 15 , wherein the reinforcing filler comprises predominantly carbon black.

17 . The tire according to claim 16 , wherein the reinforcing black filler is formed from carbon black.

18 . The tire according to claim 1 , wherein the reinforcing filler comprises an inorganic filler.

19 . The tire according to claim 18 , wherein the inorganic filler is silica.

20 . A process for producing a border rubber for one end of a reinforcing element or ply of a tire, having a composition based on at least one diene elastomer, a reinforcing filler and a vulcanization system, wherein the composition further comprises graphite, in such a way that:

the reinforcing filler content is equal to (A−X) phr and the graphite content is between X/6 and 2×/3 phr;

A being a number between 20 and 120;

X being a number between 4 and 48; and

X and A satisfying the following relationship: X<0.4A,

said process comprising the following steps:

incorporating into a diene elastomer at least one reinforcing filler, by thermomechanically mixing all the ingredients, one or more times, until a maximum temperature of between 110° C. and 190° C. is reached;

cooling the mixture down to a temperature below 100° C.;

then incorporating a vulcanization system; and

mixing everything until a maximum temperature below 110° C. is reached.

21 . The tire according to claim 7 , wherein the isoprene elastomer comprises a synthetic or natural rubber.