Rubber composition for tire tread, and pneumatic tire using same
Provided is a rubber composition for a tire tread containing: a diene rubber; silica in an amount of from 60 to 200 parts by mass per 100 parts by mass of the rubber; a polysiloxane represented by the average composition formula: (A) a (B) b (C) c (D) d (R 1 ) e SiO (4-2a-b-c-d-e)/2 ; and an alkyl triethoxysilane having an alkyl group with from 7 to 20 carbon atoms. Also provided is a pneumatic tire using this rubber composition in the tire tread.
1. A rubber composition for a tire tread comprising:
a diene rubber;
a silica;
a sulfur-containing silane coupling agent; and
an alkyl triethoxysilane represented by Formula (I);
a content of the silica being from 60 to 200 parts by mass per 100 parts by mass of the diene rubber,
the sulfur-containing silane coupling agent being a polysiloxane represented by the following Formula (1);
a content of the sulfur-containing silane coupling agent being from 1 to 20 mass % relative to the content of the silica, and
a content of the alkyl triethoxysilane being from 0.2 to 20 mass % of the content of the silica;
(A) a (B) b (C) c (D) d (R 1 ) e SiO (4-2a-b-c-d-e)/2 (1)
wherein Formula (1) is an average composition formula, and in Formula (1), A is a divalent organic group containing a sulfide group; B is a monovalent hydrocarbon group having from 5 to 10 carbon atoms; C is a hydrolyzable group; D is an organic group containing a mercapto group; R 1 is a monovalent hydrocarbon group having from 1 to 4 carbon atoms; and a to e satisfy the relational expressions 0<a<1, 0≦b <1, 0<c <3, 0<d <1, 0≦e <2, and 0 <2a +b +c +d +e<4;
wherein in Formula (I), R is an alkyl group having from 7 to 20 carbon atoms.
2. The rubber composition for a tire tread according to claim 1 , wherein b is greater than 0 in Formula (1).
3. A pneumatic tire having tire treads formed using the rubber composition for a tire tread described in claim 1 .