TIRE TREAD
The present invention relates to a tire tread that comprises a rubber composition based on at least: an elastomer matrix comprising more than 50 wt % of a first diene elastomer bearing a silanol function and a pendent amine function; a silica at a level between 120 and 140 phr; a coupling agent; and a plasticizer system comprising a hydrocarbon-containing resin having a Tg above 20° C. according to a content A ranging from 5 to 60 phr, a hydrocarbon-containing resin having a Tg above 20° C. and a liquid plasticizer according to a content B ranging from 0 to 60 phr, a liquid plasticizer, it being understood that the total level A+B is at least equal to 60 phr, preferably ranging from 60 to 90 phr. The tread according to the invention makes it possible to improve the compromise between wet grip and dry grip of a tire with low rolling resistance.
1 .- 19 . (canceled)
20 . A tire tread comprising a rubber composition based on at least:
an elastomer matrix comprising more than 50 wt % of a first diene elastomer bearing a silanol function and a pendent amine function,
a silica at a level between 120 and 140 phr;
a coupling agent; and
a plasticizer system comprising:
a hydrocarbon-containing resin having a Tg above 20° C. according to a content A ranging from 5 to 60 phr; and
a liquid plasticizer according to a content B ranging from 0 to 60 phr,
where the total level A+B is at least equal to 60 phr.
21 . The tire tread according to claim 20 , wherein the total level A+B ranges from 60 to 90 phr.
22 . The tire tread according to claim 20 , wherein the silanol function and the pendent amine function are situated away from the chain ends of the first diene elastomer.
23 . The tire tread according to claim 20 , wherein the first diene elastomer is a diene elastomer obtainable by a coupling reaction with a coupling agent bearing an alkoxysilane function and an amine function, followed by hydrolysis of the alkoxysilane function into a silanol function.
24 . The tire tread according to claim 20 , wherein the first diene elastomer is an SBR.
25 . The tire tread according to claim 24 , wherein the first diene elastomer is a solution SBR.
26 . The tire tread according to claim 24 , wherein the first diene elastomer is a copolymer of a diene and a vinyl aromatic and has a glass transition temperature between −55° C. and −40° C.
27 . The tire tread according to claim 20 , wherein the amine function is a tertiary amine function.
28 . The tire tread according to claim 20 , wherein the amount of star chains and of branched chains present in the first diene elastomer is in a range from 0 wt % to less than 50 wt % of the total weight of the first diene elastomer.
29 . The tire tread according to claim 20 , wherein the elastomer matrix comprises more than 75 wt % of the first diene elastomer.
30 . The tire tread according to claim 29 , wherein the elastomer matrix comprises more than 90 wt % of the first diene elastomer.
31 . The tire tread according to claim 20 , wherein A is in a range from 35 to 60 phr and B is in a range from 0 to 35 phr.
32 . The tire tread according to claim 31 , wherein A is greater than 40 phr and less than or equal to 60 phr and B is in a range from 0 to 30 phr.
33 . The tire tread according to claim 20 , wherein B is between 15 and 30 phr.
34 . The tire tread according to claim 20 , wherein the ratio of A to B is greater than 1.
35 . The tire tread according to claim 34 , wherein the ratio of A to B is greater than or equal to 2.
36 . The tire tread according to claim 20 , wherein the hydrocarbon-containing resin is a terpene resin or a copolymer of C5 cut and of C9 cut.
37 . The tire tread according to claim 20 , wherein the liquid plasticizer is glycerol trioleate or a vegetable oil.
38 . The tire tread according to claim 37 , wherein the liquid plasticizer is a sunflower oil.
39 . The tire tread according to claim 38 , wherein the liquid plasticizer is an oleic sunflower oil.
40 . The tire tread according to claim 20 , wherein the level of silica is from 125 to 135 phr.
41 . The tire tread according to claim 20 , wherein the weight ratio of A+B to the weight of inorganic reinforcing filler is in a range from 40 to 60%.
42 . The tire tread according to claim 41 , wherein the weight ratio of A+B to the weight of inorganic reinforcing filler is in a range from 50 to 60%.
43 . A tire comprising the tire tread according to claim 20 .
44 . A method for preparing the tire tread according to claim 20 comprising the steps of:
thermomechanically kneading the first diene elastomer, silica, coupling agent, and plasticizer system until a maximum temperature between 110° C. and 190° C. is reached;
cooling to a temperature below 100° C.;
incorporating a crosslinking system;
kneading to a maximum temperature below 110° C.; and
calendering or extruding the composition thus obtained.