| 摘要 |
PROBLEM TO BE SOLVED: To obtain a bead polymer having a particle size in a specified range very easily by a seed crystal/feedstock method by using a crosslinked polymer having a soluble fraction in a specified or lower rate as the seed crystals. SOLUTION: The bead polymer having a mean particle size of 1-30μm is obtained by using as seed crystals a crosslinked polymer having a soluble fraction of below 25 wt.% and a mean particle size of 0.5-10μm. The soluble fraction is one as determined by extracting the polymer with tetrahydrofuran for 6 hr by means of a Soxhlet extractor. In detail, a mixture (feedstock) comprising a monomer, an iniliator and, oplionally, a further additive is added to a seed crystal suspension formed by suspending seed crystals comprising a crosslinked polymer having a specified soluble content and a specified mean particle size, the mixture is infiltrated into the seed crystals prior to polymerization, and the polymerization of the swollen seed crystals is performed at high temperatures to form the bead polymer.
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