Large sized carbon black particles to reduce needed mixing energy of high hardness, stiff tire compositions

Abstract

A reinforced high viscosity rubber composition having improved processability such as reduced mixing cycles contains large sized particles of carbon black. The carbon black has low structure and a low DBP absorption number as well as a low iodine number. The rubber composition is useful in various tire rubber compositions such as those requiring a high viscosity, for example an apex rubber.

What is claimed is:  
     
         1 . A reinforced rubber composition, comprising: 
 a high viscosity rubber, and large particles of carbon black, said carbon black particles having an iodine number of about 40 or less and a DBP absorption of about 65 or less.    
     
     
         2 . A reinforced rubber composition according to    claim 1   , wherein the Mooney viscosity (ML 1+4 ) is from about 30 to about 80, and wherein the amount of said large particles of carbon black is from about 5 to about 70 parts by weight per 100 parts by weight of said rubber.  
     
     
         3 . A reinforced rubber composition according to    claim 2   , wherein said rubber is natural rubber, a rubber made from monomers of one or more conjugated dienes having from 4 to 12 carbon atoms, a rubber made from monomers of a conjugated diene having from 4 to 12 carbon atoms and a vinyl substituted aromatic having from 8 to 12 carbon atoms, or combinations thereof, wherein said DBP absorption is from about 20 to about 55, and wherein said iodine number is from about 3 to about 35.  
     
     
         4 . A reinforced rubber composition according to    claim 3   , wherein said rubber viscosity (ML 1+4 ) is from about 40 to about 70, wherein the amount of said carbon black particles is from about 10 to about 40 parts by weight per 100 parts by weight of said rubber, wherein said DBP absorption is from about 30 to about 45, and wherein said iodine number is from about 6 to about 25.  
     
     
         5 . A reinforced rubber composition according to    claim 1   , wherein said rubber composition is cured.  
     
     
         6 . A reinforced rubber composition according to    claim 4   , wherein said rubber composition is cured.  
     
     
         7 . A reinforced tire rubber composition, comprising: 
 a rubber and an effective amount of large sized carbon black particles to reduce the Mooney of (ML 1+4 ) viscosity of said rubber composition after blending but before cure.    
     
     
         8 . A reinforced rubber composition according to    claim 7   , wherein said effective amount of large sized carbon black is from about 5 to about 70 parts by weight per 100 parts by weight of said rubber, wherein said large sized carbon black particles have a DBP absorption of about 65 or less and an iodine number of about 40 or less.  
     
     
         9 . A reinforced rubber composition according to    claim 8   , wherein said DBP absorption is from about 20 to about 55, and said iodine number is from about 3 to about 35.  
     
     
         10 . A reinforced rubber composition according to    claim 9   , wherein said effective amount is from about 10 to about 40 parts by weight per 100 parts by weight of said rubber, wherein said DBP is from about 30 to about 45, wherein said iodine number is from about 6 to about 25, and wherein said Mooney (ML 1+4 ) viscosity is from about 30 to about 80.  
     
     
         11 . A reinforced rubber composition according to    claim 7   , wherein said reinforced tire rubber composition is cured.  
     
     
         12 . A reinforced rubber composition according to    claim 10   , wherein said tire reinforced rubber composition is an apex rubber, and wherein said apex rubber is cured.  
     
     
         13 . A process for mixing a high viscosity tire rubber composition comprising the steps of: 
 adding large sized carbon black particles to a rubber composition, said carbon black particles having a DBP absorption of from about 20 to about 65 and an iodine number of from about 3 to about 40; and    mixing said large sized carbon black particles and said rubber in a reduced number of mixing stages than with normal sized carbon black to form a rubber composition having a Mooney viscosity ML 1+4 ) of from about 30 to about 80.    
     
     
         14 . A process according to    claim 13   , wherein the amount of said large sized carbon black is from about 5 to about 70 parts by weight per 100 parts by weight of said rubber.  
     
     
         15 . A process according to    claim 14   , wherein said carbon black has a DBP absorption of from about 30 to about 45, an iodine number of from about 6 to about 25, and wherein the amount of said large carbon black particles is from about 10 to about 40 parts by weight per 100 parts by weight of said rubber.  
     
     
         16 . A process according to    claim 13   , including curing said rubber composition.  
     
     
         17 . A process according to    claim 15   , including curing said rubber composition.