Polyvinyl alcohol-based reversibly hydrated gel, highly water-absorptive resin and method for the preparation thereof
AssigneeShin-Estu Chemical Co., Ltd.
InventorsAkira Takahashi, Tadaya Kato
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Abstract
The polyvinyl alcohol (PVA)-based gel of the invention is reversibly hydrated so that the gel after complete drying can again absorb water to regain the highly elastic gel-like form. Such a reversibly hydrated PVA-base gel can be prepared by impregnating a hydrated gel of PVA with an ethylenically unsaturated, water-soluble ionic monomer together with or without a free-radical polymerization initiator and bringing the thus monomer-impregnated PVA gel under conditions to cause in situ polymerization of the monomer, e.g., by heating or irradiating with actinic rays such as ultraviolet light.
Claims5
A reversibly hydrated, polyvinyl alcohol-based gel which comprises:
- (a) a polyvinyl alcohol having a gelled structure;
- (b) water as a hydrating agent of the gelled polyvinyl alcohol;
- and
- (c) a polymer of an ethylenically unsaturated, water-soluble ionic monomer impregnating the hydrated gel of the polyvinyl alcohol, the polymer being formed by the in situ polymerization of the ethylenically unsaturated, water-soluble ionic monomer impregnating the hydrated gel of the polyvinyl alcohol.
A method for the preparation of a reversibly hydrated, polyvinyl alcohol-based gel which comprises the steps of:
- (i) impregnating a hydrated gel of a polyvinyl alcohol with an ethylenically unsaturated, water-soluble ionic monomer;
- and
- (ii) bringing the hydrated gel of the polyvinyl alcohol impregnated with the monomer under conditions to cause polymerization of the monomer.
A highly water-absorptive, polyvinyl alcohol-based resin which comprises:
- (a) a polyvinyl alcohol having a network structure;
- and
- (b) a polymer of an ethylenically unsaturated, water-soluble ionic monomer impregnating the polyvinyl alcohol, the polymer being formed by the polymerization of the ethylenically unsaturated, water-soluble ionic monomer in situ impregnating a hydrated gel of the polyvinyl alcohol.
A method for the preparation of a highly water-absorptive, polyvinyl alcohol-based resin which comprises the steps of:
- (i) impregnating a hydrated gel of a polyvinyl alcohol with an ethylenically unsaturated, water-soluble ionic monomer;
- (ii) bringing the hydrated gel of the polyvinyl alcohol impregnated with the monomer under conditions to cause polymerization of the monomer to give a hydrated gel of the polyvinyl alcohol impregnated with a polymer of the monomer;
- and
- (iii) dehydrating the hydrated gel to dryness.
Dependencies are inferred from the claim text.