PURPOSE: To prepare the title polyvinyl alcohol useful as a textile finishing agent, economically, by blowing super-heated vapor of a solvent which does not dissolve polyvinyl alcohol (PVA) in a wet PVA obtained by the saponification of polyvinyl acetate, and drying the PVA under fluidized state.
CONSTITUTION: Polyvinyl acetate is dissolved in an alcohol, and saponified with a saponifying catalyst such as an alkali, and the resulting slurry is separtated into solid and liquid by a centrifugal separator, etc. to obtain wet PVA containing 30W60wt% of PVA, 50W30wt% of the alcohol, and 20W10wt% of the acetic acid ester of the alcohol. The PVA pref. has a polymerization degree of 200W3000, and a saponification degree of 75W100mol%. The wet PVA is fluidized by introducing super-heated vapor of a solvent which does not dissolve the PVA, e.g. alcohol, acetic acid ester, etc., by which the drying and the heat treatment of the PVA can be carried out simultaneously to obtain the title PVA.
GOTOU RIYUUICHI
MIYAMOTO YASUNORI
