Elastic melamine-formaldehyde! resin foam prepn. - using aq. soln. or dispersion contg. emulsifier, hardener, blowing agent and resin prepd. in extruder

摘要

In the parent patent an elastic melamine-HCHO resin foam is prepd. by foaming an aq. soln. or dispersion contg. a melamine-HCHO prepolymer, an emulsifier, a volatile blowing agent, a hardener, and opt. other conventional additives and then hardening. In this addn., the aq. soln. or dispersion is prepd. continuously in a mixer with a pre-mixing zone (A), an intensive mixing zone (B), a kneading zone (C) and a take-off zone (D). A melamine-HCHO prepolymer powder is fed separately to (A) and then 70-98% of the total amt. of water. in (B) the prepolymer and water are mixed and at the end of the zone, the liq. blowing agent and a soln. of the hardener and emulsifier opt. with the other additives in the rest of the water are added separately. The additives are mixed with the compsn. in (C). The take-off pressure in (D) is 1.1-5.0 bar. The temp. of the compsn. in zone (A) is not greater than 30 deg.C and in the other zones not greater than 25 deg.C. The process provides a homogeneous mixt. for foaming.