Thermo-expansive microspheres, their production process and their application

摘要

The present invention provides a process for producing thermo-expansive microspheres comprising a thermoplastic resinous shell and a blowing agent being encapsulated in the shell, the blowing agent which is a fluorine-containing C2-10 compound having ether linkage, being free of chlorine and bromine atoms and gasifying at a temperature not higher than the softening point of the thermoplastic resin. The thermo-expansive microspheres have preferably an average particle size ranging from 1 to 100 mum and a CV, or coefficient of variation, of particle size distribution being 30% or less, and a retaining ratio of blowing agent encapsulated being 90% or more.