Rubber composition for tire, and pneumatic tire

Abstract

A rubber composition for a tire, and a pneumatic tire are provided in which the fuel economy, abrasion resistance, and deterioration resistance can be improved in a good balance. The present invention relates to a rubber composition for a tire, containing a rubber component that contains: a modified natural rubber having a phosphorus content of not more than 200 ppm; and butadiene rubber, wherein 60 to 95% by mass of the modified natural rubber and 5 to 40% by mass of the butadiene rubber are contained based on 100% by mass of the rubber component.

1 . A rubber composition for a tire, comprising a rubber component that contains:
 a modified natural rubber having a phosphorus content of not more than 200 ppm; and   butadiene rubber,   wherein 60 to 95% by mass of the modified natural rubber and 5 to 40% by mass of the butadiene rubber are contained based on 100% by mass of the rubber component.   
     
     
         2 . The rubber composition for a tire according to  claim 1 ,
 wherein the modified natural rubber has a nitrogen content of not more than 0.3% by mass and a gel content measured as a toluene insoluble content of not more than 20% by mass.   
     
     
         3 . The rubber composition for a tire according to  claim 1 ,
 wherein the modified natural rubber is obtained by saponifying natural rubber latex.   
     
     
         4 . The rubber composition for a tire according to  claim 1 ,
 wherein the modified natural rubber is obtained by performing:   a step (A) of saponifying natural rubber latex to prepare a saponified natural rubber latex;   a step (B) of coagulating the saponified natural rubber latex and performing an alkali treatment on the resulting coagulated rubber; and   a step (C) of washing the resulting rubber until the phosphorus content in rubber falls to not more than 200 ppm.   
     
     
         5 . The rubber composition for a tire according to  claim 1 ,
 wherein the butadiene rubber is a modified butadiene rubber.   
     
     
         6 . The rubber composition for a tire according to  claim 5 ,
 wherein the modified butadiene rubber has been modified with a compound represented by formula (1):   
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2 , and R 3  are the same as or different from each other, and each represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group, a mercapto group, or a derivative thereof; R 4  and R 5  are the same as or different from each other, and each represent a hydrogen atom, an alkyl group, or a cyclic ether group; and n represents an integer. 
     
     
         7 . The rubber composition for a tire according to  claim 1 , further comprising carbon black. 
     
     
         8 . The rubber composition for a tire according to  claim 1 , which is used for a tread for heavy load tires. 
     
     
         9 . A heavy load tire comprising a tread formed from the rubber composition according to  claim 1 .