Controlled boron trifluoride catalysis of epoxy polymerizations

A new technique which permits of the use of boron‐trifluoride for catalysis of epoxy polymerizations is described. The destructive exotherm that ordinarily accompanies contact of this substance with epoxy compounds is avoided by gradual release of the catalyst. This controlled release is accomplished through use of the catalyst in the form of the liquid boron trifluoride‐ethyl ether complex absorbed on a particulate carrier, the component particles being coated with a paraffin barrier layer. Employing this catalyst system a smooth but rapid reaction is obtained starting with all reactants initially at room temperature and without application of external heat. Polymerization is essentially complete within several minutes following addition of the catalyst system.