Highly-stable graft copolymer dispersions in polyols containing unsaturation and polyurethanes prepared therefrom

Abstract

Highly-stable graft copolymer dispersions are prepared by the in situ polymerization in the presence of a free radical catalyst of a vinyl monomer in a polyol containing an essential amount of unsaturation. The dispersions are low-viscous liquids which may be advantageously employed in the preparation of flexible urethane foams having enhanced load-bearing properties.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A highly stable graft copolymer dispersion prepared by the in situ polymerization in the presence of a free radical catalyst at a temperature of from 70° C. to about 170° C. of (a) an ethylenically unsaturated monomer or mixture of said monomers in    (b) an unsaturated polyol mixture containing from 0.10 mole to 0.70 mole of unsaturation per mole of polyol mixture, .Iadd.said unsaturation being incorporated into the polyol mixture by the reaction of a polyol with an organic compound having both ethylenic unsaturation and a hydroxyl, carboxyl or epoxy group or by employing said organic compound as a reactant in the preparation of the polyol, .Iaddend.said polymerization carried out by adding the monomer and the catalyst to the polyol mixture.   
     
     
       2. The copolymer dispersion of claim 1 wherein the monomer is styrene. 
     
     
       3. The copolymer dispersion of claim 1 wherein the monomer is a mixture of acrylonitrile and styrene. 
     
     
       4. The copolymer dispersion of claim 1 wherein the unsaturated polyol mixture comprises a polyol which is prepared by the reaction of an alkylene oxide with the reaction product of maleic anhydride with a polyether polyol having an equivalent weight of from 250 to 5,000. 
     
     
       5. The copolymer dispersion of claim 4 wherein the polyether polyol is an alkylene oxide adduct of glycerol or propylene glycol. 
     
     
       6. The copolymer dispersion of claim 1 wherein the unsaturated polyol mixture is prepared by the reaction of a polyhydric alcohol having from two to six hydroxyl groups with a mixture of propylene oxide and allyl glycidyl ether. 
     
     
       7. The copolymer dispersion of claim 1 wherein the catalyst is azobis(isobutyronitrile). 
     
     
       8. The copolymer dispersion of claim 1 wherein the polyol mixture contains from 0.30 to 0.60 mole of unsaturation per mole of polyol mixture.