Rubber composition for tire treads and pneumatic tire using same
View Patent ↗A rubber composition for tire treads of the present technology contains a diene rubber, silica and a silane coupling agent, wherein the silane coupling agent is a polysiloxane represented by a specific average composition formula, the silica content is from 5 to 200 parts by mass per 100 parts by mass of the diene rubber, and the silane coupling agent content is from 1 to 20 mass % relative to the silica content.
1. A rubber composition for tire treads, containing a diene rubber, silica and a silane coupling agent; wherein
the silane coupling agent is a polysiloxane represented by an average composition formula of formula (1) below;
silica content is from 5 to 200 parts by mass per 100 parts by mass of the diene rubber; and
silane coupling agent content is from 1 to 20 mass % relative to the silica content:
(A) a (B) b (C) c (D) d (R 1 ) e SiO (4-2a-b-c-d-e)/2 (1)
(wherein, in formula (1), A denotes a divalent organic group containing a sulfide group; B denotes a monovalent hydrocarbon group having from 5 to 20 carbons; C denotes a hydrolyzable group; D denotes an organic group containing a mercapto group; R 1 denotes a monovalent hydrocarbon group having from 1 to 4 carbons; and a to e satisfy the relationships 0<a<1, 0<b<1, 0<c<3, 0<d<1, 0≦e<2, 0<2a+b+c+d+e<4).
2. The rubber composition for tire treads according to claim 1 , wherein, in formula (1), A is a group represented by formula (2) below, C is a group represented by formula (3) below, and D is a group represented by formula (4) below:
*—(CH 2 ) n —S x —(CH 2 ) n —* (2)
(wherein, in formula (2), n denotes an integer from 1 to 10; x denotes an integer from 1 to 6; * denotes a bond position);
*—OR 2 (3)
(wherein, in formula (3), R 2 denotes an alkyl group having from 1 to 20 carbons, an aryl group having from 6 to 10 carbons, or an alkenyl group having from 2 to 10 carbons; * denotes a bond position);
*—(CH 2 ) m —SH (4)
(wherein, in formula (4), m denotes an integer from 1 to 10; * denotes a bond position).
3. The rubber composition for tire treads according to claim 1 , wherein not less than 50 mass % of the diene rubber is aromatic vinyl-conjugated diene copolymer.
4. The rubber composition for tire treads according to claim 3 , wherein the aromatic vinyl-conjugated diene copolymer contains from 5 to 50 mass % aromatic vinyl, and vinyl bond content in the conjugated diene is from 5 to 80%.
5. The rubber composition for tire treads according to claim 1 , wherein a nitrogen adsorption specific surface area of the silica is from 100 to 300 m 2 /g.
6. A pneumatic tire using the rubber composition for tire treads described in claim 1 .
7. The rubber composition for tire treads according to claim 2 , wherein not less than 50 mass % of the diene rubber is aromatic vinyl-conjugated diene copolymer.
8. The rubber composition for tire treads according to claim 2 , wherein a nitrogen adsorption specific surface area of the silica is from 100 to 300 m 2 /g.
9. The rubber composition for tire treads according to claim 1 , wherein not less than 50 mass % of the diene rubber is aromatic vinyl-conjugated diene copolymer.
10. The rubber composition for tire treads according to claim 1 , wherein a nitrogen adsorption specific surface area of the silica is from 100 to 300 m 2 /g.
11. The rubber composition for tire treads according to claim 3 , wherein a nitrogen adsorption specific surface area of the silica is from 100 to 300 m 2 /g.
12. The rubber composition for tire treads according to claim 4 , wherein a nitrogen adsorption specific surface area of the silica is from 100 to 300 m 2 /g.
13. The rubber composition for tire treads according to claim 2 , wherein not less than 50 mass % of the diene rubber is aromatic vinyl-conjugated diene copolymer.
14. The rubber composition for tire treads according to claim 2 , wherein a nitrogen adsorption specific surface area of the silica is from 100 to 300 m 2 /g.
15. The rubber composition for tire treads according to claim 7 , wherein a nitrogen adsorption specific surface area of the silica is from 100 to 300 m 2 /g.
16. The rubber composition for tire treads according to claim 9 , wherein a nitrogen adsorption specific surface area of the silica is from 100 to 300 m 2 /g.
17. The rubber composition for tire treads according to claim 13 , wherein a nitrogen adsorption specific surface area of the silica is from 100 to 300 m 2 /g.
18. A pneumatic tire using the rubber composition for tire treads described in claim 2 .