Rubber composition and truck tire
The present invention is directed to a rubber composition for a truck tire, the rubber composition comprising 70 phr to 95 phr of polyisoprene, 5 phr to 30 phr of a polybutadiene rubber having a cis content of less than 60% and being functionalized for the coupling to silica, as well as 40 phr to 80 phr of a filler comprising predominantly silica. Furthermore, the present invention is also directed to a tire comprising such a rubber composition and a truck with said tire.
1 . A tread of a semi-trailer truck tire being formed of a rubber composition, the rubber composition comprising:
70 phr to 95 phr of polyisoprene;
5 phr to 30 phr of a low cis polybutadiene rubber produced using a lithium catalyst, the polybutadiene rubber having a cis content of less than 60% and being functionalized for coupling to silica;
optionally a styrene butadiene rubber, wherein the styrene butadiene rubber being present in less than 10 phr;
2 phr to 15 phr of a resin selected from terpene resins and terpene phenol resins having a softening point of at least 105° C.; and,
40 phr to 80 phr of a filler comprising predominantly silica having a BET surface area of at least 190 m 2 /g.
2 . The rubber composition of claim 1 , comprising from 45 phr to 75 phr of silica.
3 . The rubber composition of claim 2 , comprising more than 50 phr of silica and less than 65 phr of silica.
4 . The rubber composition of claim 1 , comprising less than 10 phr of carbon black.
5 . The rubber composition of claim 1 , comprising from 0.1 phr to 4 phr of carbon black.
6 . The rubber composition of claim 1 , wherein the polybutadiene rubber has one or more of: i) at least one amino silane group, ii) at least one amino siloxane group, and iii) at least one amino silanol group.
7 . The rubber composition of claim 1 , wherein the polybutadiene rubber has a glass transition temperature within a range of −80° C. to −98° C.
8 . The rubber composition of claim 7 , wherein the polybutadiene rubber has a glass transition temperature within a range of −80° C. to −95° C.
9 . The rubber composition of claim 1 , wherein the rubber composition comprises one or more of:
from 75 phr to 90 phr of polyisoprene;
from 10 phr to 25 phr of the polybutadiene rubber.
10 . The rubber composition of claim 1 , wherein the resin has a softening point of at least 105° C.
11 . The rubber composition of claim 1 , wherein the resin is a terpene phenol resin having a softening point within a range of 125° C. to 190° C.
12 . The rubber composition of claim 1 , further comprising a silane within a range of 5 phr to 10 phr.
13 . The rubber composition of claim 12 , wherein the silane is one or more of:
i) a sulfur containing silane;
ii) a sulfur donor;
iii) one or more of tetrasulfide silanes and mercapto silanes.
14 . The rubber composition of claim 1 , wherein the composition comprises one or more of:
i) less than 4 phr of a styrene butadiene rubber;
ii) less than 10 phr of oil.
15 . A tire for a truck, the tire comprising the rubber composition of claim 1 .
16 . The tire of claim 15 , wherein the rubber composition is incorporated a radially outermost portion of the tread.
17 . The tire of claim 15 , wherein the tire is a 22.5 inch truck tire.
18 . A semi-trailer truck comprising a truck and a semi-trailer, the semitrailer truck comprising at least one tire in accordance with claim 16 .