| 摘要 |
PURPOSE:To obtain the titled ultrafine particle which is in the form of a true sphere and has the desired average particle size and particle size distribution, by subjecting a high- molecular material soln. to a microscopic phase separation by cooling, evaporation, etc., to separate it into an amorphous high-molecular material-rich phase particle and a high- molecular material-lean dispersion medium and recovering the former. CONSTITUTION:A high-molecular material (e.g. cellulose linters) having an average degree of polymn. Dp of 500 or below is dissolved in a good solvent (e.g. cuprammonium soln.) in such a proportion as to give a high-molecular material soln. which has a concn. of 0.1wt% or above and a viscosity eta of 10cp or below at 20 deg.C and satisfies the relationship of the formula (wherein Dp is an average degree of polymn. and eta is viscosity). The high-molecular material soln. is subjected to microscopic phase separation by cooling said soln., evaporating said good solvent from said soln., mixing said soln. with a non-solvent (e.g. acetone) for said high-molecular compd. or a combination thereof to separate it into an amorphous high- molecular material-rich phase particle and a high-molecular material-lean dispersion medium. The high-molecular material-rich phase particle in the dispersed state is separated, recovered and spray-dried to obtain in the title ultrafine particle having an average particle size of 0.02-10mu.
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