Rubber composition for tire and pneumatic tire
The present invention provides: a rubber composition for tires which has excellent processability and has excellent low heat build-up when formed into a tire; and a pneumatic tire using the same. The rubber composition for tires of the present invention is a rubber composition for tires, the rubber composition containing a diene rubber (A) and a microparticle (B), a vinyl group content of the diene rubber (A) being from 5 to 35 mass %, the microparticle (B) being a mercapto group-containing organic microparticle in which a crosslinkable oligomer or polymer (b1) is crosslinked, an average particle size of the microparticle (B) being from 1 to 200 μm, and a content of the microparticle (B) being from 1 to 55 parts by mass per 100 parts by mass of the diene rubber (A).
1. A rubber composition for a tire, the rubber composition comprising:
a diene rubber (A) and a microparticle (B);
a vinyl group content of the diene rubber (A) being from 5 to 35 mass %;
the microparticle (B) being a mercapto group-containing organic microparticle in which a crosslinkable oligomer or polymer (b1) is crosslinked;
an average particle size of the microparticle (B) being from 1 to 200 μm; and
a content of the microparticle (B) being from 1 to 55 parts by mass per 100 parts by mass of the diene rubber (A).
2. The rubber composition for a tire according to claim 1 , wherein the diene rubber (A) contains an aromatic vinyl-conjugated diene copolymer rubber (a); and
a vinyl bond content of a conjugated diene in the aromatic vinyl-conjugated diene copolymer rubber (a) is from 10 to 50 mass %.
3. The rubber composition for a tire according to claim 2 , wherein the aromatic vinyl-conjugated diene copolymer rubber (a) is a styrene-butadiene copolymer rubber obtained by emulsion polymerization.
4. The rubber composition for a tire according to claim 3 , wherein the crosslinkable oligomer or polymer (b1) is a polycarbonate urethane prepolymer.
5. The rubber composition for a tire according to claim 4 , wherein the microparticle (B) is a microparticle to which a mercapto group is introduced after the crosslinkable oligomer or polymer (b1) is crosslinked in water, an organic solvent, or the diene rubber (A) and formed into a microparticle shape.
6. The rubber composition for a tire according to claim 3 , wherein the microparticle (B) is a microparticle to which a mercapto group is introduced after the crosslinkable oligomer or polymer (b1) is crosslinked in water, an organic solvent, or the diene rubber (A) and formed into a microparticle shape.
7. The rubber composition for a tire according to claim 2 , wherein the crosslinkable oligomer or polymer (b1) is a polycarbonate urethane prepolymer.
8. The rubber composition for a tire according to claim 7 , wherein the microparticle (B) is a microparticle to which a mercapto group is introduced after the crosslinkable oligomer or polymer (b1) is crosslinked in water, an organic solvent, or the diene rubber (A) and formed into a microparticle shape.
9. The rubber composition for a tire according to claim 2 , wherein the microparticle (B) is a microparticle to which a mercapto group is introduced after the crosslinkable oligomer or polymer (b1) is crosslinked in water, an organic solvent, or the diene rubber (A) and formed into a microparticle shape.
10. The rubber composition for a tire according to claim 1 , wherein the crosslinkable oligomer or polymer (b1) is a polycarbonate urethane prepolymer.
11. The rubber composition for a tire according to claim 10 , wherein the microparticle (B) is a microparticle to which a mercapto group is introduced after the crosslinkable oligomer or polymer (b1) is crosslinked in water, an organic solvent, or the diene rubber (A) and formed into a microparticle shape.
12. The rubber composition for a tire according to claim 1 , wherein the microparticle (B) is a microparticle to which a mercapto group is introduced after the crosslinkable oligomer or polymer (b1) is crosslinked in water, an organic solvent, or the diene rubber (A) and formed into a microparticle shape.
13. A pneumatic tire comprising the rubber composition for a tire described in claim 1 in a tire tread.
14. A pneumatic tire comprising the rubber composition for a tire described in claim 2 in a tire tread.
15. A pneumatic tire comprising the rubber composition for a tire described in claim 3 in a tire tread.
16. A pneumatic tire comprising the rubber composition for a tire described in claim 10 in a tire tread.
17. A pneumatic tire comprising the rubber composition for a tire described in claim 12 in a tire tread.