THERMALLY EXPANDABLE MICROCAPSULE EXCELLENT IN HEAT AND SOLVENT RESISTANCE

摘要

PROBLEM TO BE SOLVED: To obtain thermally expandable microcapsules more excellent in heat resistance than a conventional product, not causing foaming at <=140 deg.C and excellent also in solvent resistance. SOLUTION: A volatile inflating agent which becomes gas at a temp. below the softening point of a polymer is microencapsulated with the polymer produced from a compsn. contg. >=80wt.% nitrile monomer, <=20wt.% non-nitrile monomer and 0.1-1wt.% crosslinking agent to obtain the objective microcapsules. The softening point of the shell walls of the microcapsules is >=135 deg.C and the microcapsules are expanded >=7 times by heating at 160 deg.C for 1 min and >=3 times by heating at 160 deg.C for 4 min.