| 摘要 |
<p>A process for efficiently and easily producing heat-expandable microcapsules which combine excellent heat resistance with excellent solvent resistance, are less apt to shrink or break even when heated at a high temperature for long, and highly stably heat-expand (foam stably). The process is characterized in that monomer ingredients comprising 55 to 75 wt.% acrylonitrile, 20 to 40 wt.% methacrylonitrile, 1 to 10 wt.% vinyl acetate, and 0.1 to 1 wt.% crosslinking agent having a functionality of 4 or higher and a volatile expanding agent which gasifies at a temperature not higher than the softening point of the polymer to be obtained from the monomer ingredients are polymerized while being pressurized with nitrogen and that the resultant polymer is formed into microcapsules.</p> |
