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AssigneeKuraray Co., Ltd.
InventorsNaoki Fujiwara, Kazutoshi Terada, Hitoshi Maruyama
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There are disclosed a process for producing a vinyl ester polymer having a high degree of polymerization at a high efficiency, which process comprises subjecting a vinyl ester monomer to seed polymerization by the use of a vinyl ester polymer emulsion as a seed emulsion under the conditions in which the charge of a water-soluble initiator per unit volume (1 liter) of reactant liquid charge is 1.times.10.sup.-8 to 2.times.10.sup.-4 mol, and the charge of the water-soluble initiator per one particle of the vinyl ester polymer particles in the seed emulsion is 1.times.10.sup.-28 to 1.times.10.sup.-20 mol, and a process for producing a vinyl alcohol polymer at a high efficiency from the vinyl ester polymer thus obtained. According to these processes of the present invention, both a vinyl ester polymer and vinyl alcohol polymer each having a higher degree of polymerization can be produced with ease on an industrial scale.
A process for producing a vinyl alcohol polymer having an average degree of polymerization of 4000 to 100,000, comprising seed polymerizing a monomer consisting essentially of a vinyl ester monomer to a conversion of from 20.0% to 78.9% in a seed emulsion containing a vinyl ester seed polymer and a water-soluble initiator to produce a vinyl ester polymer, said water-soluble initiator being present in an amount of from 1.times.10.sup.-8 to 2.times.10.sup.-4 mol per liter of said liquid reactant and from 1.times.10.sup.-28 to 1.times.10.sup.-20 mol per particle of said vinyl ester seed polymer, and hydrolyzing said vinyl ester polymer.
A process for producing a vinyl alcohol polymer having an average degree of polymerization of 4000 to 100,000, comprising emulsion polymerizing a monomer consisting essentially of a vinyl ester monomer at a temperature of -60.degree. to 40.degree. C. in the presence of a vinyl alcohol polymer selected from the group consisting of a polyvinyl alcohol composed of vinyl alcohol units alone, a copolymer comprising vinyl alcohol units and a block copolymer comprising polyvinyl alcohol as one segment to produce a vinyl ester polymer, and hydrolyzing said vinyl ester polymer.
Dependencies are inferred from the claim text.