Dehydrocarbyl magnesium and an alkali metal compound catalyst composition for polymerizing conjugated dienes

Abstract

The process and catalyst system disclosed herein comprises the polymerization of a conjugated diene such as 1,3-butadiene in hydrocarbon solution in the presence of a new catalyst composition comprising: (a) a dihydrocarbyl magnesium compound of 1-10 carbon atoms, preferably a dialkyl magnesium having 3-8 carbon atoms in each alkyl group, and (b) an alkali metal compound of the formula R(SM).sub.n, R'.sub.2 NM, R'NHM or RC.tbd.CM, wherein R is a hydrocarbyl radical of 1-10 carbon atoms, preferably alkyl, n is 1, 2 or 3, M is Li, Na or K, and R' is a hydrocarbyl radical of 1-10 carbon atoms or an acyl radical of 1-10 carbon atoms. This process is particularly advantageous in that the polymer product can be controlled to have only a relatively small amount of 1,2 structure in accordance with the polymerization temperature. For example, at 125.degree. C. with Li compounds, the product generally has a 1,2 content of 12.6% or less; at 50.degree. C., 10.6% or less; and at 25.degree. C., 7% or less. Where 1,2 contents of 17-25% are desired, these may be obtained by using the Na compounds, and when 1,2 contents of 37-54% are desired, these may be obtained by using K compounds. Where even higher 1,2 contents are desired, they may be obtained by using an amine, such as tetramethylethylenediamine, as an additional catalyst component.

Dependencies are inferred from the claim text.