Particulate polyvinyl alcohol copolymers, process for making and uses of the same
AssigneeKuraray America, Inc.
InventorsGhebrehiwet GHEBREMESKEL, Masaki KATO, Yuta TAOKA
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Abstract
The present invention relates generally to a highly-hydrolyzed polyvinyl alcohol composition having increased cold-water solubility, a process for making such a polyvinyl alcohol composition, and various end uses thereof.
Claims20
A process for preparing a polyvinyl alcohol composition of particulate agglomerated polyvinyl alcohol particles, comprising the steps of:
- (A) providing to an alcoholysis unit (i) a solution of a polyvinyl acetate in a solvent and (ii) an alkali catalyst, wherein the polyvinyl acetate is a copolymer of a monomer component consisting essentially of vinyl acetate with one or more lower alkyl acrylate ester monomers in an amount up to about 20 mol %, based on the total monomer component;
- (B) combining the solution and the alkali catalyst in the alcoholysis unit under agitation to hydrolyze the polyvinyl acetate to produce a first slurry comprising (i) a polyvinyl alcohol having a degree of hydrolysis of about 93% or greater and (ii) residual alkali catalyst;
- (C) removing the first slurry from the alcoholysis unit;
- (D) separating polyvinyl alcohol from the first slurry to produce a polyvinyl alcohol wet cake;
- and
- (E) drying the polyvinyl alcohol wet cake to produce the particulate agglomerated polyvinyl alcohol particles,
- wherein the residual alkali catalyst in the first slurry is predominantly not neutralized prior to the drying step.
A polyvinyl alcohol composition of particulate agglomerated polyvinyl alcohol particles, wherein:
- (1) the polyvinyl alcohol is a copolymer of a monomer component consisting essentially of vinyl acetate with one or more lower alkyl acrylate ester monomers in an amount up to about 20 mol %, based on the total monomer component, with a degree polymerization of from about 400 to about 10000, and a degree of hydrolysis of about 93% or greater;
- and
- (2) the composition has a D(90) particle size of from about 1 μm to about 1000 μm, a bulk density of about 0.55 g/cm3 or less, and a cold-water (20° C.) solubles of about 50% or greater.
A polyvinyl alcohol composition produced in a slurry alcoholysis process using an alcoholysis catalyst, in which the alcoholysis catalyst has not been predominantly neutralized, wherein the polyvinyl acetate is a copolymer of a monomer component consisting essentially of vinyl acetate with one or more lower alkyl acrylate ester monomers in an amount up to about 20 mol %, based on the total monomer component;
- and wherein the polyvinyl alcohol has a reduced lactone ring content as compared to a polyvinyl alcohol produced under the same conditions except that a predominant amount of the residual catalyst has been neutralized.
Dependencies are inferred from the claim text.