Process for foaming a polymerizable medium using acid sensitive azo compounds with a polymerizable monomer and free radical inhibitor

摘要

In the foaming of a polymerizable medium (such as an unsaturated polyester resin) by using acid sensitive azo compounds, significant improvement in the foaming efficiency can be obtained by incorporating in the resin medium 0.001%-10% by weight based on the weight of the resin compounds which exert an inhibiting effect on free radical polymerization. Examples of such compounds include methacrylonitrile, alphamethylstyrene and laurylmercaptan.