Rubber composition for tire and method of manufacturing same

Abstract

A rubber composition for a tire comprising 100 parts by weight of diene rubber and 1 to 30 parts by weight of expandable graphite having a particle size of 30 to 600 μm.

1 . A rubber composition for a tire comprising 100 parts by weight of a diene rubber and 1 to 30 parts by weight of an expandable graphite having a particle size of 30 to 600 μm.  
     
     
         2 . A rubber composition as claimed in    claim 1   , further comprising 1 to 20 parts by weight, based upon 100 parts by weight of the diene rubber, of a microcapsule capable of being expanded to form a gas-encompassed thermoplastic resin upon heating.  
     
     
         3 . A rubber composition as claimed in    claim 1   , wherein an average glass transition temperature of the diene rubber is not more than −55° C.  
     
     
         4 . A rubber composition as claimed in    claim 1   , wherein 20 to 80 parts by weight of a carbon black having a specific surface area of nitrogen adsorption (N 2 SA) of not less than 70 m 2 /g and a dibutyl phthalate (DBP) oil absorption of not less than 105 ml/100 g and 0 to 50 parts by weight of unhydrated or precipitated silica, based upon 100 parts by weight of the rubber, are contained therein.  
     
     
         5 . A method for manufacturing a pneumatic tire from a rubber composition comprising 100 parts by weight of a diene rubber, 1 to 30 parts by weight of an expandable graphite having a particle size of 30 to 600 μm and curing agents comprising the steps of: 
 mixing the diene rubber with other components except for the expandable graphite and the curing agents;  
 adding thereto the expandable graphite and the curing agents in the separate mixing step (i.e., final mixing) under such a condition that the maximum reaching temperature is below the expansion onset temperature of the expandable graphite, followed by extrusion processing under the substantially same temperature condition as in the final mixing; and then  
 assembling a green tire with the extrude of the rubber mixture, and then, vulcanizing the green tire having the extruded rubber mixture at a temperature of more than the expansion onset temperature of the expandable graphite.  
 
     
     
         6 . A radial tire suitable for icy and snowy road comprising using the rubber composition, as a tire tread, according to    claim 1   .