Improved natural rubber compositions

Abstract

There is herein described improved natural rubber compositions having nanocarbon and carbon black as reinforcing agents wherein the nanocarbon is uniformly pre-dispersed within the rubber component. In particular there is described rubber compositions comprising a mixture of natural rubber, nanocarbon and carbon black wherein the relative amount in parts per hundred rubber (pphr) of nanocarbon to carbon black is in the range of about 1:40 to about 1:2 and the relative amount in parts per hundred rubber (pphr) of nanocarbon to natural rubber is in the range of about 1:100 to about 10:100 and wherein the nanocarbon component is pre-dispersed within the natural rubber component.

1 . A rubber composition comprising a mixture of natural rubber, nanocarbon and carbon black reinforcing agents wherein the relative amount in parts per hundred rubber (pphr) of nanocarbon to carbon black is in the range of about 1:40 to about 1:2 and the relative amount in parts per hundred rubber (pphr) of nanocarbon to natural rubber is in the range of about 1:100 to about 10:100 and wherein the nanocarbon component is pre-dispersed within the natural rubber component. 
     
     
         2 . A rubber composition according to  claim 1 , wherein the relative ratio of nanocarbon to carbon black in pphr is in the range of any of the following: about 1:30 to about 1:3. 
     
     
         3 . A rubber composition according to  claim 1 , wherein the relative ratio of nanocarbon to natural rubber in pphr is in the range of any of the following: about 1:100 to about 8:100. 
     
     
         4 . A rubber composition according to  claim 1 , wherein the rubber component contains from about 1 to 10 pphr nanocarbon. 
     
     
         5 . A rubber composition according to  claim 1 , wherein carbon black is present at a level of from about 10 to 50 pphr. 
     
     
         6 . A rubber composition according to  claim 1 , wherein nanocarbon and carbon black are the only reinforcing agents. 
     
     
         7 . A rubber composition according to  claim 1 , wherein there is no silica and Si-coupling agent. 
     
     
         8 . A rubber composition according to  claim 1 , wherein the natural rubber is selected from any one of or combination of the following: unprocessed and processed latex products such as ammonia containing latex concentrates; RSS, ADS or crepes; TSR, SMR L, SMR CV; specialty rubbers SP, MG, DP NR; or field grade (cup lump) rubber products such as TSR, SMR 10, SMR 20, SMR 10 CV, SMR 20 SV, SMR GP. 
     
     
         9 . A rubber composition according to  claim 1 , wherein the natural rubber is selected from chemically modified natural rubber products including: epoxidized natural rubbers (ENRs) including ENR 25 and ENR 50. 
     
     
         10 . A rubber composition according to  claim 1  containing a vulcanizing agent. 
     
     
         11 . A rubber composition according to  claim 1  containing one or more delaying accelerators. 
     
     
         12 . A composition according to  claim 1  containing one or more activating agents. 
     
     
         13 . A rubber composition according to  claim 1  containing one or more antioxidants. 
     
     
         14 . A tire comprising at least one component part made from a rubber composition as defined in  claim 1 . 
     
     
         15 . A tire according to  claim 14 , wherein the rubber composition is used in the tread of the tire. 
     
     
         16 . A tire according to  claim 14 , wherein the rubber composition is used in tire components such as the inner liner, sidewall and shoulder where the tread makes its transition to the sidewall. 
     
     
         17 . A tire according to  claim 14 , wherein the tire is a heavy vehicle tire such as a truck tire, a bus tire, a car tire, an aircraft tire or a tire for an earth moving vehicle. 
     
     
         18 . Use of a rubber composition according to  claim 1  for in the manufacture of component parts for tires such as the treads, inner liner, sidewall and shoulder where the tread makes its transition to the sidewall. 
     
     
         19 . A rubber composition having nanocarbon and carbon black as reinforcing agents wherein the relative amount in parts per hundred rubber (pphr) of nanocarbon to carbon black is in the range of about from about 1:40 to about 1:2 and the relative amount in parts per hundred rubber (pphr) of nanocarbon to natural rubber is in the range of from about 1:100 to about 10:100 and wherein the nanocarbon component is pre-dispersed within the natural rubber component and wherein said rubber component is from a masterbatch produced via:
 (a) formation of an aqueous slurry containing a dispersion of nanocarbon, at a level of from about 2% to 10% by weight of the aqueous slurry, and a surfactant and a stabilizer;   (b) grinding of the aqueous nanocarbon containing slurry;   (c) combination of the aqueous slurry with a natural rubber latex concentrate or diluted latex solution and mixing until a uniform mixture is obtained;   (d) coagulation of the mixture followed by aqueous washing, and removal of excess surfactant, water and excess stabilizers by coagulate squeezing or suitable alternative method;   (e) formation of dried rubber nanocarbon masterbatches by either direct drying of the coagulate from step (d) or by coagulate cutting to granulate size and subsequent drying;   wherein the pH of the slurry and latex are similar or equivalent prior to combination, and   wherein the pH of the nanocarbon may be adjusted using a suitable base to align it to the pH of the rubber latex.   
     
     
         20 . A rubber composition according to  claim 15 , wherein the formation of the aqueous slurry contains a dispersion of nanocarbon at a level of from about 3% to 5% by weight of the aqueous slurry and a surfactant and stabilizer. 
     
     
         21 . A rubber composition according to  claim 15 , wherein the pH of the slurry and latex are within about 2 pH units prior to combination.