Composition and method of controlling solid polyurethane particle size with water reactant
First Claim
1. A process for forming solid, discrete, hydrophilic, crosslinked, polyurethane particles of reduced size which comprises adding(a) a hydrophilic prepolymer comprising an isocyanate-capped polyol or mixture of isocyanate-capped polyols wherein said isocyanate-capped polyol or mixture of polyols has a reaction functionality greater than 2, the total of said polyol present having an ethylene oxide content of at least 40 weight percent before capping;
- (b) said prepolymer (a) being dissolved in a water soluble solvent, to(c) an agitated water reactant,the volume ratio of (c);
(a) being at least 2;
1.
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Abstract
This invention relates to control of particle size of solid, discrete, hydrophilic, crosslinked polyurethane particles formed from a composition which comprises
(a) a water reactant;
(b) a prepolymer comprising at least one isocyanate-capped polyol having a reaction functionality of at least two, the total of said polyol present having an ethylene oxide content of at least 40 weight percent before capping;
(c) a water-soluble solvent for (b) and
(d) when the reaction functionality of (b) is two, a crosslinking agent containing at least three functional groups, the volume ratio of (a):(b) being at least 2:1.
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Citations
12 Claims
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1. A process for forming solid, discrete, hydrophilic, crosslinked, polyurethane particles of reduced size which comprises adding
(a) a hydrophilic prepolymer comprising an isocyanate-capped polyol or mixture of isocyanate-capped polyols wherein said isocyanate-capped polyol or mixture of polyols has a reaction functionality greater than 2, the total of said polyol present having an ethylene oxide content of at least 40 weight percent before capping; (b) said prepolymer (a) being dissolved in a water soluble solvent, to (c) an agitated water reactant, the volume ratio of (c);
(a) being at least 2;
1.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
Specification