Denki Kagaku Kogyo Kabushiki Kaisha

Satoshi Watanabe

Takahiro Kozuka

Hirohisa Otake

The present invention provides modified PVA having unsaturated double bonds derived from a specific monomer in the main chain of the molecule. A modified polyvinyl alcohol containing bond units of the formula (1) having double bonds in its molecular main chain: wherein each of X1 and X2 is a Clower alkyl group, a hydrogen atom or a metal atom, g is an integer of from 0 to 3, h is an integer of from 0 to 12, Y1 is a hydrogen atom or &#x2014;COOM, and M is a hydrogen atom, an alkyl group or a metal atom.

Modified polyvinyl alcohol and process for producing the same

Provided is a method of producing a polyvinyl alcohol resin, wherein the impurities in the resin are removed efficiently with a small amount of a washing liquid. A polyvinyl alcohol obtained after a polymerization step (step S) and a saponification step (step S) is washed with a washing liquid consisting of methyl acetate: 1 to 40 parts by mass, methanol: 50 to 98.9 parts by mass and water: 0.1 to 10 parts by mass in a washing step (step S). The solid matter concentration of the slurry containing the washing liquid then is 1 to 30 mass %.

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Itoigawa, Japan

Satoshi Watanabe