Rubber composition for tire, and pneumatic tire
A rubber composition for a tire contains a diene rubber, silica, and a specific modified butadiene polymer, wherein the diene rubber contains an aromatic vinyl-conjugated diene rubber A and at least one rubber component B selected from an aromatic vinyl-conjugated diene rubber b1 other than the rubber A and a butadiene rubber b2 having a weight average molecular weight of ≥15000. A content of the aromatic vinyl-conjugated diene rubber A is from 30 to 90% by mass, and a content of the rubber component B is from 10 to 70% by mass, an average TG of the diene rubber is lower than −20° C., a content of the silica is from 80 to 200 parts by mass per 100 parts by mass of the diene rubber, and a content of the modified butadiene polymer is from 1.0 to 25.0% by mass with respect to content of the silica.
1. A rubber composition for a tire comprising:
a diene rubber;
silica; and
a modified butadiene polymer,
the diene rubber containing an aromatic vinyl-conjugated diene rubber A and at least one rubber component B selected from the group consisting of an aromatic vinyl-conjugated diene rubber b1 other than the aromatic vinyl-conjugated diene rubber A and a butadiene rubber b2 having a weight average molecular weight of greater than 15000,
the aromatic vinyl-conjugated diene rubber A being a terminal-modified aromatic vinyl-conjugated diene rubber having an aromatic vinyl content from 35 to 45% by mass and a vinyl unit content from 25 to 45% by mole,
in the diene rubber, the content of the aromatic vinyl-conjugated diene rubber A is from 50 to 90% by mass, and the content of the rubber component B is from 10 to 50% by mass,
the average glass transition temperature of the diene rubber is −45° C. or higher and lower than −20° C.,
the modified butadiene polymer being a terminal-modified butadiene polymer having a weight-average molecular weight from 1000 to 15000, and a molecular weight distribution of 2.0 or less,
a content of the silica being from 80 to 200 parts by mass per 100 parts by mass of the diene rubber, and
a content of the modified butadiene polymer being from 1.0 to 25.0% by mass with respect to the content of the silica.
2. A rubber composition for a tire comprising:
a diene rubber;
silica; and
a modified butadiene polymer,
the diene rubber containing an aromatic vinyl-conjugated diene rubber A and at least one rubber component B selected from the group consisting of an aromatic vinyl-conjugated diene rubber b1 other than the aromatic vinyl-conjugated diene rubber A and a butadiene rubber b2 having a weight average molecular weight of greater than 15000,
the aromatic vinyl-conjugated diene rubber A being a terminal-modified aromatic vinyl-conjugated diene rubber having an aromatic vinyl content from 35 to 45% by mass and a vinyl unit content from 25 to 45% by mole,
in the diene rubber, the content of the aromatic vinyl-conjugated diene rubber A is from 30 to 50% by mass, and the content of the rubber component B is from 50 to 70% by mass,
the average glass transition temperature of the diene rubber is lower than −45° C.,
the modified butadiene polymer being a terminal-modified butadiene polymer having a weight-average molecular weight from 1000 to 15000, and a molecular weight distribution of 2.0 or less,
a content of the silica being from 80 to 200 parts by mass per 100 parts by mass of the diene rubber, and
a content of the modified butadiene polymer being from 1.0 to 25.0% by mass with respect to the content of the silica.
3. The rubber composition for a tire according to claim 1
wherein the modified butadiene polymer has a functional group containing a nitrogen atom and a silicon atom at a terminal.
4. The rubber composition for a tire according to claim 1 , wherein the silica has a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area from 150 to 300 m 2 /g.
5. The rubber composition for a tire according to claim 1 ,
further comprising
a silane coupling agent,
wherein a content of the silane coupling agent is from 1 to 20% by mass based on the content of the silica.
6. The rubber composition for a tire according to claim 1 disposed in a cap tread.
7. The rubber composition for a tire according to claim 2 ,
wherein the modified butadiene polymer has a functional group containing a nitrogen atom and a silicon atom at a terminal.
8. The rubber composition for a tire according to claim 2 ,
wherein the silica has a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area from 150 to 300 m 2 /g.
9. The rubber composition for a tire according to claim 3 ,
wherein the silica has a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area from 150 to 300 m 2 /g.
10. The rubber composition for a tire according to claim 7 ,
wherein the silica has a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area from 150 to 300 m 2 /g.
11. The rubber composition for a tire according to claim 2 , further comprising
a silane coupling agent,
wherein a content of the silane coupling agent is from 1 to 20% by mass based on the content of the silica.
12. The rubber composition for a tire according to claim 3 , further comprising
a silane coupling agent,
wherein a content of the silane coupling agent is from 1 to 20% by mass based on the content of the silica.
13. The rubber composition for a tire according to claim 4 , further comprising
a silane coupling agent,
wherein a content of the silane coupling agent is from 1 to 20% by mass based on the content of the silica.
14. The rubber composition for a tire according to claim 7 , further comprising
a silane coupling agent,
wherein a content of the silane coupling agent is from 1 to 20% by mass based on the content of the silica.
15. A pneumatic tire having the rubber composition for a tire described in claim 2 disposed in a cap tread.