Polyurethane quaternary ammonium salts

Abstract

Polyurethane quaternary ammonium salts are obtained by heating a solution of a polyurethane resin characterized by having present in the polymer backbone hydroxyl groups and at least one substituent selected from the group consisting of carboxylate radicals and carboxyl radicals dissolved in a water-miscible organic solvent for the resin at a temperature above 64.degree. C. and below the decomposition temperature of said polyurethane resin with an organic chloride for a period of time; adding a strong base to the reaction mixture and continuing to heat said mixture to form a polyurethane quaternary ammonium hydroxide in solution; and precipitating the polyurethane quaternary ammonium hydroxide by pouring the reaction mixture into an excess of water. The polyurethane quaternary ammonium hydroxide so obtained may be dissolved in a solvent containing sufficient hydrochloric acid to bring the pH of the solution to 8; and the corresponding polyurethane quaternary ammonium chloride may be recovered from solution by evaporation of the solvent at a temperature below the decomposition point of the polyurethane quaternary ammonium chloride. A polyurethane quaternary ammonium sulfate may be prepared by dissolving in sulfuric acid a polyurethane resin characterized by having present in the polymer backbone hydroxyl groups and lactone groups to form a solution. This solution is added to an excess of water with stirring and neutralized with sodium hydroxide to bring the pH of the diluted solution to between 3 and 4. Evaporation of the solvent gives a residue containing a polyurethane quaternary ammonium sulfate and sodium sulfate. The polyurethane quaternary ammonium sulfate may be separated from the mixture by extraction with methanol.