PURPOSE: To easily produce a polyvinyl alcohol polymer on an industrial scale, by saponification of a specific methanolic solution of a polyvinyl ester polymer obtained by emulsion polymerization.
CONSTITUTION: A polyvinyl alcohol (PVA) polymer is produced from a polyvinyl ester polymer obtained by emulsion polymerization as follows. That is, an emulsion of a polyvinyl ester polymer having a particle diameter of 5μ or less is mixed with methanol in an amount of 2W100 times by weight of the polyvinyl ester polymer to form a homogeneous solution, and if desired, unreacted vinyl ester monomers and water are removed therefrom, followed by saponification to produce a PVA polymer. The PVA thus obtained can be used in the conventional application field, and the PVA having a high degree of polymerization obtained effectively by the present method can be suitably used in the form of high-strength PVA sheet or fiber.
FUJIWARA NAOKI
YAMAUCHI JUNNOSUKE
OKAYA TAKUJI
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