1996 Volume 69 Issue 11 Pages 735-742
The curing reactions of the carboxylic acid blocked by vinyl ether/epoxide cross-linking system were studied with the effect of catalyst.
The useful catalysts for the deblocking reaction of the blocked carboxylic acid were protonic acids and Lewis acids, while those for the reactions of carboxylic acid/epoxide system were Lewis acids, bases, and onium salts. Further, both the deblocking reaction of the blocked carboxylic acid and the esterification of carboxylic acid with epoxide could be accelerated without the etherification of epoxide in the presence of a relatively weak Lewis acid such as zinc 2 - ethylhexanoate.
The curing of this cross-linking system in the presence of the weak Lewis acid proceeded through the sequence of the following three steps : the deblocking reaction of the blocked carboxylic acid, the esterification of the regenerated carboxylic acid with epoxide, and the addition of vinyl ether to 2 -hydroxyalkyl ester produced by the esterification. 2 -Acetalalkyl ester produced by the addition was mainly obtained by the curing of this cross-linking system.
