Abstract: Synthetic elastomers are typically made commercially by employing emulsion polymerization or solution polymerization techniques. In such solution polymerization techniques, it is desirable to operate at the highest solids content which is practical. As a general rule, it is not practical to prepare such rubbers by solution polymerization at solids contents of higher than about 20 percent. However, the subject invention reveals a technique for preparing such rubbers by high solids solution polymerization at extremely high solids contents. This technique offers substantial advantages associated with eliminating large quantities of organic solvents.

Abstract: There is disclosed a method of preparing high cis-1,4-polybutadiene which comprises continuously polymerizing butadiene in mixture with an inert aliphatic or cycloaliphatic solvent employing as a catalyst a mixture comprising (A) at least one trialkyl aluminum wherein the alkyl group contains from 2 to 8 carbon atoms, (B) at least one nickel salt of carboxylic acids and (C) at least one boron trifluoride complex of ethers in which each of the individual catalyst components are continuously injected into the polymerization vessel containing the mixture of butadiene and inert solvent.