Published November 1971
The decade of the sixties saw commercialization of the highly stereo-regular elastomers--polybutadiene and polyisoprene. Commercial interest and production has been concentrated mainly on polymers having 95% or more of the cis-l,4 configuration with the exception of the Firestone process using n-butyllithium. With isoprene monomer this process yields polymer of about 95% cis-l,4 structure, With butadiene monomer the process yields polymer of mixed structure, typically 35% cis-l,4, 52% trans-l,4, and 13% 1,2 (vinyl)
This report is concerned primarily with the production of polybuta-diene by four solution processes: three using catalysts that yield polymers of high cis content and the fourth using n-butyllithium. Other catalyst systems and processes are described but not evaluated economically.
Two processes for extending and reinforcing polybutadiene have been examined. One uses solution masterbatching, and the other uses the Banbury internal mixer. Polybutadiene, designated "BR' for butadiene rubber, has the ability to accept high loadings of extending oils and reinforcing fillers, usually carbon blacks. The main use of BR is in tire treads, where it is blended with styrene-butadiene rubber (SBR) for use in passenger car tires. For these uses it is often convenient for the tire fabricator to start with BR compounds already containing oil and carbon black in proportions close to his needs. The masterbatching processes are thus of importance to potential manufacturers of polybutadienes.
The Columbian Division of the Cities Service Company and the Farrel Company provided information that was very helpful in the masterbatch studies. Special equipment design and cost information for the polymer synthesis processes was provided by Crawford and Russell, Inc., and by the V. D. Anderson Company. The assistance of these companies is very much appreciated.