Rubber composition for run-flat tire
View Patent ↗A rubber composition for a run-flat tire comprises from 20 to 100 parts by weight of a reinforcing filler per 100 parts by weight of a diene rubber containing from 10 to 80 wt. % of butadiene rubber and from 10 to 40 wt. % of natural rubber; wherein the reinforcing filler contains at least 50 wt. % of carbon black; a mode diameter Dst in a mass distribution curve of a Stokes diameter of aggregates of the carbon black is at least 145 nm; a nitrogen adsorption specific surface area N 2 SA is from 45 to 70 m 2 /g; and a ratio N 2 SA/IA of the nitrogen adsorption specific surface area N 2 SA to an iodine adsorption IA (units: mg/g) is from 1.00 to 1.40.
1. A rubber composition for a run-flat tire, the rubber composition comprising:
from 20 to 100 parts by weight of a reinforcing filler per 100 parts by weight of a diene rubber containing from 10 to 80 wt. % of butadiene rubber and from 10 to 40 wt. % of natural rubber; wherein
the reinforcing filler contains at least 50 wt. % of carbon black;
a mode diameter Dst in a mass distribution curve of a Stokes diameter of aggregates of the carbon black is at least 145 nm;
a nitrogen adsorption specific surface area N 2 SA is from 55 to 70 m 2 /g;
a ratio N 2 SA/IA of the nitrogen adsorption specific surface area N 2 SA to an iodine adsorption IA (units: mg/g) is from 1.00 to 1.40; and
the mode diameter D st of the Stokes diameter satisfies a relationship of the following formula (1):
D st <1979×(N 2 SA) −0.61 (1)
wherein, D st is the mode diameter (nm) in the mass distribution curve of the Stokes diameter of aggregates, and N 2 SA is the nitrogen adsorption specific surface area (m 2 /g).
2. The rubber composition for a run-flat tire according to claim 1 , wherein a DBP absorption of the carbon black is from 100 to 160 ml/100 g.
3. The rubber composition for a run-flat tire according to claim 1 , wherein from 10 to 40 wt. % of a butadiene rubber containing a syndiotactic-1,2-polybutadiene component is contained in the diene rubber as the butadiene rubber.
4. A pneumatic tire comprising rubber reinforcement layers having a crescent-shaped cross section of left and right side wall portions of a run-flat tire formed with the rubber composition for a run-flat tire described in claim 1 .
5. The rubber composition for a run-flat tire according to claim 2 , wherein from 10 to 40 wt. % of a butadiene rubber containing a syndiotactic-1,2-polybutadiene component is contained in the diene rubber as the butadiene rubber.
6. A pneumatic tire comprising rubber reinforcement layers having a crescent-shaped cross section of left and right side wall portions of a run-flat tire formed with the rubber composition for a run-flat tire described in claim 2 .
7. A pneumatic tire comprising rubber reinforcement layers having a crescent-shaped cross section of left and right side wall portions of a run-flat tire formed with the rubber composition for a run-flat tire described in claim 3 .