To obtain a polyvinyl alcohol having good quality, properties, etc., and having high syndiotacticity by polymerizing a specified fluorine-containing branched carboxylic acid vinyl ester and saponifying the obtained polymer.
A fluorine-containing branched carboxylic acid vinyl ester represented by the formula [wherein R1 and R2 are each a fluorohydrocarbon group which may be partially substituted by chlorine atoms; and R3 is a hydrocarbon group, a fluorohydrocarbon group, a fluorine atom, or a chlorine atom] is polymerized, and the obtained polymer is saponified to obtain a polyvinyl alcohol having a syndiotacticity (diad) of 65% or abobe. It is desirable that R1 and R2 are each a 1-3C fluorohydrocarbon group which may be partially substituted by chlorine atoms and that R3 is a 1-3C hydrocarbon group or a fluorohydrocarbon group. The fluorine-containing branched carboxylic acid vinyl ester represented by the formula is particularly desirably vinyl perfluoropivalate, for example. The polymerization temperature is desirably in the range of 0-80°C.
OKAMOTO YOSHIO
NAKANO TAMAKI
SAWAMOTO MITSUO
NAKAJIMA HIROSHI
TERADA KAZUTOSHI
IDA HIROSHI
ASAHI TETSUYA
OKI YASUYOSHI
OKANO YOSHIMICHI
NISHIMURA MASAMICHI
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