PRODUCTION OF FINE POWDER, AND FINE POWDER

摘要

PROBLEM TO BE SOLVED: To provide a production process whereby a fine powder having an average primary particle size of 3μm or lower can be produced from a thermoplastic resin at a high productivity. SOLUTION: An emulsion of an acrylic copolymer formed from 70-97wt.% alkyl (meth)acrylate and 30-3wt.% unsatd. carboxylic acid is neutralized with an alkali metal compd. to neutralize 10-50% of carboxyl groups of the copolymer and is spray dried with a generally used spray drier. The emulsion can be produced by a usually used emulsion polymn. process. Thus obtd. fine powder is esp. suitable for a cement additive as a redispersible powder.