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US 5,872,189 AGranted
Water-redispersible powders of film-forming polymers with a "core/shell" structure
AssigneeRhone-Poulenc Chimie
InventorsBill Bett, Joel Richard
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AssigneeRhone-Poulenc Chimie
InventorsBill Bett, Joel Richard
Estimating the term…
The present invention relates to a water-redispersible powder based on film-forming polymers which are substantially water-insoluble and which are prepared by aqueous emulsion polymerization of monomers containing ethylenic unsaturation with a "core/shell" structure comprising a hydrophobic core based on a polymer exhibiting a Tg (glass transition temperature) of between -30.degree. and +25.degree. C., preferably between -10.degree. and +20.degree. C., and a hydrophilic shell based on a polymer exhibiting a Tg higher than +55.degree. C., preferably higher than +90.degree. C., characterized in that the shell is bonded to the core by covalent bonds resulting from the reaction of an agent for grafting the shell onto the ethylenic unsaturations remaining in the core, and is substantially insoluble in an alkaline medium.
A water-redispersible powder comprising particles of a film-forming polymer which is substantially water-insoluble and which is prepared by aqueous emulsion polymerization of monomers containing ethylenic unsaturation, said particles having a "core/shell" structure, said structure having a hydrophobic core comprising a polymer presenting remaining ethylenic unsaturations and exhibiting a glass transition temperature of between -30.degree. and +25.degree. C., and a hydrophilic shell comprising a polymer exhibiting a glass transition temperature higher than +55.degree. C., wherein the shell is substantially insoluble in an alkaline medium and is bonded to the core by covalent bonds resulting from the reaction of an agent for grafting the shell onto the ethylenic unsaturations remaining in the core.
Dependencies are inferred from the claim text.