| 摘要 |
PROBLEM TO BE SOLVED: To obtain a coating material having a Wardel's practical sphericity falling within a specific range, produced by suspension polymerization, suitable for thin film coating and giving a coating film having excellent surface smooth ness. SOLUTION: This powder coating material has a shape having a Wardel's practical sphericity of 0.8-1 defined by the formula and is produced by suspension polymerization. The average particle diameter of the powder coating material is 5-20μm and the ratio of the powder coating material having the above shape is preferably >=50wt.%, more preferably >=80wt.%. The suspension polymerization is carried out by supplying a disperse phase composed at least of a polymerizable monomer and a curing agent to a continuous phase, forming a suspension containing polymerizable droplets having desired size with a granulation machine and polymerizing the monomer. The disperse phase is produced by using cyclohexyl acrylate, methyl methacrylate, glycidyl acrylate or styrene as the polymerizable monomer, sebacic acid as the curing agent, benzoyl peroxide as the polymerization initiator and t-dodecyl mercaptan as a chain transfer agent.
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