Cross-linked water-swellable polymer particles
AssigneeThe Dow Chemical Company
InventorsMaurice L. Zweigle, Jack C. Lamphere
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Abstract
Cross-linked water-swellable polymers are described, having a particle size of less than 4 microns. They are used as thickening agents for aqueous dispersions or solutions, particularly useful where high shear conditions are encountered in the application.
Claims15
A method for thickening an aqueous medium to obtain a composition having the properties of a viscous short solution and being resistant to viscosity degradation under conditions of high shear which comprises the step of thoroughly dispersing in said medium from about 0.1 to about 2 percent by weight of microbeads of a water-insoluble, water-swellable polymer of a water-soluble vinyl monomer or mixture of water-soluble vinyl monomers, cross-linked with a difunctional cross-linking agent copolymerizable with said monomer or monomers, said microbeads having diameters of from about 0.2 to about 4 microns and having a gel capacity of at least about 10 grams per gram in aqueous 0.27 molar sodium chloride solution, said cross-linking agent being present in an amount from about 50 to 1000 parts by weight of cross-linking agent per million parts of vinyl monomer or monomers in the polymer.
A viscous, short aqueous composition comprising an aqueous medium having dispersed therein from about 0.1 to about 2 percent by weight of microbeads of a water-insoluble, water-swellable polymer of a water-soluble vinyl monomer or mixture of water-soluble vinyl monomers, cross-linked with a difunctional cross-linking agent copolymerizable with said monomer or monomers, said microbeads having diameters of from about 0.2 to about 4 microns and having a gel capacity of at least about 10 grams per gram in aqueous 0.27 molar sodium chloride solution, said polymer being cross-linked with from about 50 to 1000 parts by weight of cross-linking agent per million parts of vinyl monomer or monomers in the polymer.
An aqueous composition comprising an aqueous medium having dispersed therein microbeads of a water-insoluble water-swellable polymer of a water-soluble vinyl monomer or mixture of water-soluble vinyl monomers, cross-linked with from about 50 to 1000 parts by weight of a difunctional cross-linking agent per million parts of vinyl monomer or monomers in the polymer, said agent being copolymerizable with said monomer or monomers, said microbeads having a gel capacity at least 10 grams per gram in aqueous 0.27 molar sodium chloride solution diameters from about 0.2 to about 4 microns and being present in an amount sufficient to thicken the aqueous medium to a viscous, short aqueous composition.
Dependencies are inferred from the claim text.