GB1417002A - Polymerisation process - Google Patents

Abstract

1417002 Polymerization of butadiene BP CHEMICALS INTERNATIONAL Ltd 13 Feb 1973 [1 March 1972] 9536/72 Heading C3P Butadiene or a mixture of butadiene containing not more than 50 mole per cent of other monomers is polymerized in a 2 stage process in a substantially oxygen gas free environment wherein the second step (and preferably the first step) is carried out in the presence of (a) an ether or tertiary amine and (b) a chain transfer agent which is an aromatic hydrocarbon containing at least one hydrogen atom capable of replacement by a lithium atom and the steps comprise (1) contacting 1 to 30% by weight of monomer with an organolithium compound soluble in the reaction medium, so that the mole ratio of monomer to the lithium compound is 1 : 0À005 to 1 : 0À25 at -60‹ to 150‹ C. and allowing polymerization till all the lithium compound has reacted and (2) adding to the polymerization mixture thus obtained at least one alkali metal compound soluble in the reaction medium and selected from Na or K hydrocarbons having at least six carbon atoms in the hydrocarbon radical, Na or K alkoxides and NaB tetraphenyl so that the mole ratio of organo Li compound in step 1 to the alkali metal compound used in step 2 is in the range 20 : 1 to 1 : 2 adding the remaining 99-70 wt. per cent of monomer and allowing further polymerization at - 20‹ to + 120‹ C. The polymerization may be carried out in the presence of diluent. The products have 20 to 90% of 1,2 polymerized units and numbers average molecular weights of 500 to 20,000. In the examples butadiene is homopolymerized in toluene Œ isobutane in the presence of tetrahydrofuran using n-butyl lithium in stage (1) and Na or K tertiary butoxide or NaB tetraphenyl in stage (2) and the polymerization is terminated by the addition of ethanol containing butylated hydroxy toluene.