Process for alkylene oxide polymerization
AssigneeUnion Carbide Corporation
InventorWalter T. Reichle
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Abstract
The molecular weight of polyalkylene oxides produced by the polymerization of a cyclic oxide in contact with a catalyst comprising the reaction product of a dihydrocarbyl zinc compound and a linear alkanediol in contact with a silica dispersion aid and nonionic surfactant in an inert diluent is controlled by the continuous addition of a very dilute solution of chain transfer agent having a pKa value of from 9 to 22 to the polymerizing mixture during the polymerization reaction at a carefully controlled rate so as not to terminate the polymerization reaction.
Claims36
A process for controlling the molecular weight of polyalkylene oxides which comprises continuously feeding during the polymerization reaction a diluted chain transfer agent, said chain transfer agent havinq a pKa value of from 9 to 22, to a polymerizing mixture comprising a cyclic oxide of the formula ##STR11## wherein R' is hydrogen or alkyl of 1 to 20 carbon atoms and a catalytic amount of a catalyst comprising the reaction product of a zinc compound of the general formula R.sub.2 Zn wherein R is
- (i) an alkyl group containing from 1 to about 8 carbon atoms;
- or
- (ii) an unsubstituted or alkyl-substituted phenyl or naphthyl group;
- or
- (iii) a cycloalkyl group having from 4 to 6 ring carbon atoms;
- or
- (iv) a dicyclopentadienyl group
- with an alkane polyol having from 2 to about 6 carbon atoms in the alkane chain, or a cycloalkane diol having 5 or 6 ring carbon atoms in contact with a silica dispersion aid and nonionic surfactant in an inert medium.
Dependencies are inferred from the claim text.