HEAT-EXPANDABLE MICROSPHERES, PROCESS FOR PRODUCING SAME, AND USES

摘要

Heat-expandable microspheres with high encapsulation efficiency of a blowing agent and good heat-expansion performance, a process for reproducibly producing the heat-expandable microspheres and application thereof are provided. The heat-expandable microspheres comprise essentially a thermoplastic resin shell and a blowing agent encapsulated therein, and contain not more than 500 ppm of silicon, not more than 350 ppm of aluminum and not more than 600 ppm of the total of the silicon and aluminum. The heat-expandable microspheres retain at least 70 % of the blowing agent encapsulated therein at the temperature which is the average of their expansion-initiation temperature and maximum expansion temperature.