Hydrolyzed polymers of alkyl methacrylates and methods of producing them

Claim 1

A PROCESS FOR HYDROLYZING AN ALKYL METHACRYLATE POLYMER TO FORM AN ALKALI METAL SALT OF A METHACRYLIC ACID POLYMER WHICH COMPRISES HEATING, AT A TEMPERATURE OF AT LEAST 60* C. BUT BELOW A TEMPERATURE OF WHICH APPRECIABLE POLYMER DEGRADATION OCCURS, A PARTICULATE POLYMER OF AN ALKYL METHACRYLATE IN WHICH THE ALKYL GROUP HAS 1 TO 4 CARBON ATOMS, SELECTED FROM THE GROUP CONSISTING OF HOMOPOLYMERS THEREOF AND COPOLYMERS CONTAINING IN THE POLYMER MOLECULE 50 TO 100% BY WHICH OF AT LEAST ONE OF THE AFORESAID ALKYL METHACRYLATES AND UP TO 50% BY WEIGHT OF OTHER COPOLYMERIZABLE MONOTHEYLENICALLY UNSATURATED MOLECULES, SUSPENDED INA LIQUID MEDIUM WHICH SWELLS THE POLYMER WITHOUT DISSOLVING IT BUT DOES NOT APPRECIABLY SWELL AND DOES NOT DISSOLVE AN ALKALI METAL SALT OF HYDROLYSIS PRODUCTS OF THE POLYMER HAVING AT LEAST 10% OF HYDROLYZED METHACRYLATE UNITS, SAID MEDIUM CONTAINING AN ORGANIC SOLVENT SELECTED FROM THE GROUP CONSISTING OF ISOPROPANOL AND MIXTURES OF ISOPROPANOL AND EHTYLENE GLYCOL, SUFFICIENT ETHYLENE GLYCOL BEING USED WHEN THE FIRST-MENTIONED PARTICULATE POLYMER IS SOLUBLE IN ISOPROPANOL TO PREVENT THE MEDIUM FROM DISSOLVING SAID POLYMER, AN ALKALI METAL HYDROXIDE, AND A SMALL AMOUNT OF WATER UP TO BUT NOT IN EXCESS OF 1 MOLE THEREOF PER HYDROLYZABLE UNIT OF THE POLYMER.