Rubber composition and pneumatic tire
There is disclosed a vulcanizable rubber composition comprising: (A) a functionalized elastomer comprising the reaction product of a living anionic elastomeric polymer and a polymerization terminator of formula I where R 1 , R 2 and R 3 are independently C1 to C8 alkyl or C1 to C8 alkoxy, with the proviso that at least two of R 1 , R 2 and R 3 are C1 to C8 alkoxy; R 4 is C1 to C8 alkyl; Si is silicon; S is sulfur; and Z is R 5 or of formula II where R 5 is alkyl, aryl, alkylaryl or arylalkyl; (B) a polymeric amine comprising a primary amine functionality; and (C) an aromatic carboxylic acid or aromatic acid anhydride.
1. A vulcanizable rubber composition comprising:
(A) a functionalized elastomer comprising the reaction product of a living anionic elastomeric polymer and
a polymerization terminator of formula I
where R 1 , R 2 and R 3 are independently C1 to C8 alkyl or C1 to C8 alkoxy, with the proviso that at least two of R 1 , R 2 and R 3 are C1 to C8 alkoxy; R 4 is C1 to C8 alkyl; Si is silicon; S is sulfur; and Z is R 5 or of formula II
where R 5 is alkyl, aryl, alkylaryl or arylalkyl;
(B) a polymeric amine comprising a primary amine functionality; and
(C) an aromatic carboxylic acid or aromatic acid anhydride.
2. The vulcanizable rubber composition of claim 1 , wherein the polymerization terminator of formula I has the structure
where Et is ethyl.
3. The vulcanizable rubber composition of claim 1 , wherein the polymerization terminator of formula I is S-benzyl-S′-triethoxysilylpropyltrithiocarbonate.
4. The vulcanizable rubber composition of claim 1 , wherein the polymeric amine is a polyethyleneimine.
5. The vulcanizable rubber composition of claim 1 , wherein the polymeric amine is a polyoxyalkylene amine.
6. The vulcanizable rubber composition of claim 1 , wherein the amount of polymeric amine ranges from 0.1 to 10 phr.
7. The vulcanizable rubber composition of claim 1 , wherein the aromatic carboxylic acid or aromatic acid anhydride is selected from the group consisting of benzoic acid, salicylic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, phthalic anhydride, and benzoic anhydride.
8. The vulcanizable rubber composition of claim 1 , wherein the amount of aromatic carboxylic acid or aromatic acid anhydride ranges from 0.1 to 10 phr.
9. The vulcanizable rubber composition of claim 1 , further comprising silica.
10. A pneumatic tire comprising the vulcanizable rubber composition of claim 1 .