| 摘要 |
PROBLEM TO BE SOLVED: To obtain an aggregate of a polymer particle comprising the aggregate of particles of a hydroxyl-containing vinyl polymer and having working property capable of giving the freedom of solvent selection to users. SOLUTION: The objective aggregate comprises an aggregate of particles of a vinyl polymer, which has a solubility parameter (δ) expressed by the formula:δ=dΣG/M [G is an aggregation energy constant; M is a basic molecular weight; (d) is a specific gravity at 20 deg.C] of 7.8 or more and a hydroxyl value of 20-300 (mgKOH)/g. Further, 95 wt.% or more of the aggregate satisfies the relation that (a) and (b) are each 30-400μm, and 1.0<=b/a<=1.5, where (a) is the minor axis of a particle and (b) is the major axis.
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