Process for the production of polyethers derived from oxetanes
AssigneeThe Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland
InventorMalcolm J. Stewart
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Abstract
Hydroxyterminated prepolymers, used in curing reactions with isocyanates to produce elastomers, are prepared by continuously adding over periods of 12-50 hours an oxetane monomer to a reaction mixture containing a diol initiator and a catalyst capable of catalyzing the cationic quasi-living cationic polymerization of the monomer, the rate of addition to maintain stoichiometric excess over the monomer. Polymerization is terminated by adding brine. Polymers of increased molecular weight and reduced impurity levels result.
Claims7
Process for polymerizing an oxetane monomer comprising the steps of:
- (a) mixing together a substantially anhydrous catalyst capable of catalyzing the cationic polymerization of the monomer with a preinitiator precursor to yield an active adduct of the catalyst and precursor, wherein the molar ratio of catalyst to the functional groups of the preinitiator precursor is always at least 1:1;
- (b) adding the monomer to a quantity of the adduct in solution over a period of at least 12 hours to cause the adduct to form an initiating species with the monomer and thereafter undergo chain extension polymerization with further monomer;
- and
- (c) allowing the polymerization to proceed substantially to completion;
- and wherein steps (b) and (c) are each performed at a temperature of between +20 degrees C. and -20 degrees C.
Dependencies are inferred from the claim text.