Rubber composition for tire and tire
The invention has an object to provide a rubber composition for tire with improved processability and abrasion resistance. The invention relates to a rubber composition for tire, comprising: (a) 5-90 weight parts of a high cis polybutadiene having a cis structure in a proportion of 95 wt % or higher in a microstructure analysis; (b) 90-5 weight parts of a diene-based rubber other than (a); and (c) 1-100 weight parts of a reinforcing agent blended in 100 weight parts of a rubber component including (a)+(b). The high cis polybutadiene is synthesized using a cobalt-based catalyst and satisfies the requirements of: (i) a Mooney viscosity (ML) of 40-49; (ii) a molecular weight distribution [Weight average molecular weight (Mw)/Number average molecular weight (Mn)] of 3.0-3.9; and (iii) a velocity dependence index (n-value) of the Mooney viscosity of 2.3-3.0.
1. A rubber composition for tire, comprising: (a) 5-90 weight parts of a high cis polybutadiene having a cis structure in a proportion of 95 wt % or higher in a microstructure analysis; (b) 90-5 weight parts of a diene-based rubber other than (a); and (c) 1-100 weight parts of a reinforcing agent blended in 100 weight parts of a rubber component including (a)+(b), wherein the high cis polybutadiene is synthesized using a cobalt-based catalyst and satisfies the requirements of: (i) a Mooney viscosity (ML) of 40-49; (ii) a molecular weight distribution [Weight average molecular weight (Mw)/Number average molecular weight (Mn)] of 3.0-3.9; and (iii) a velocity dependence index (n-value) of the Mooney viscosity of 2.3-3.0 (the n-value is represented by Expression 1):
(Expression 1)
log( ML )=log( K )+ n −1 ×log( RS ) (1)
(where RS indicates revolutions per minute of a rotor; and K an arbitrary number).
2. The rubber composition for tire according to claim 1 , wherein the high cis polybutadiene (a) has a ratio (Tcp/ML) of a 5 wt % toluene solution viscosity (Tcp) to the Mooney viscosity (ML) of 2.5-3.5.
3. The rubber composition for tire according to claim 1 , wherein the high cis polybutadiene (a) has a Mw of 500,000-700,000 and a Mn of 120,000-250,000.
4. The rubber composition for tire according to claim 2 , wherein the high cis polybutadiene (a) has a Mw of 500,000-700,000 and a Mn of 120,000-250,000.
5. The rubber composition for tire according to claim 1 , wherein the reinforcing agent (c) includes either one or more of carbon black and silica.
6. The rubber composition for tire according to claim 2 , wherein the reinforcing agent (c) includes either one or more of carbon black and silica.
7. The rubber composition for tire according to claim 4 , wherein the reinforcing agent (c) includes either one or more of carbon black and silica.
8. The rubber composition for tire according to claim 1 , wherein the diene-based rubber (b) includes either one or more of natural rubber and polyisoprene rubber.
9. The rubber composition for tire according to claim 2 , wherein the diene-based rubber (b) includes either one or more of natural rubber and polyisoprene rubber.
10. The rubber composition for tire according to claim 4 , wherein the diene-based rubber (b) includes either one or more of natural rubber and polyisoprene rubber.
11. The rubber composition for tire according to claim 5 , wherein the diene-based rubber (b) includes either one or more of natural rubber and polyisoprene rubber.
12. A tire containing the rubber composition for tire according to claim 1 as a rubber base.