Process for the manufacture of polyvinyl alcohol

Claim 1

A PROCESS FOR THE PRODUCTION OF SOLID FILTERABLE POLYVINYL ALCOHOL HAVING LESS THAN ABOUT 2 PERCENT ESTER GROUPS THEREIN WHICH COMPRISES ALCOHOLYZING, AT A TEMPERATURE BETWEEN 60*C.-95*C., A POLYMER SELECTED FROM THE GROUP CONSISTING OF (1) HOMOPOLYMERS OF VINYL ACETATE, VINYL PROPIONATE, VINYL STERATE, AND VINYL BENZOATE, AND (2) COPOLYMERS CONSISTING OF AT LEAST 50 MOL PERCENT OF A VINYL ESTER SELECTED FROM THE GROUP CONSISTING OF VINYL ACETATE, VINYL PROPIONATE, VINYL STEARATE, AND VINYL BENZOTE, THE BALANCE BEING A MEMBER SELECTED FROM THE GROUP CONSISTING OF VINYL CHLORIDE, CROTONIC ACID, ACRYLIC ACID, METHACRYLIC ACID, AND METHACRYLIC ACID ESTERS OF SATURATED ALIPHATIC ALCOHOLS HAVING 1 TO 4 CARBON ATOMS, IN THE PRESENCE OF AT LEAST A STOICHIOMETRIC AMOUNT OF AN ALIPHATIC SATURATED ALCOHOL HAVING 3-6 CARBON ATOMS, 12-100 PERCENT OF WATER, AND 1-10 PERCENT OF AN ACID SELECTED FROM THE GROUP CONSISTING OF HYDROCHLORIC, SULFURIC, ARYL SULFONIC AND SATURATED ALIPHATIC SILFONIC ACIDS, THESE PERCENTAGE FIGURES BEING CALCULATED ON THE WEIGHT OF THE POLYMER, THE TOTAL MIXTURE CONTAINING 10-50 PERCENT BY WEIGHT OF SAID POLYMER, WHEREBY A SOLID, FILTERABLE POLYVINYL ALCOHOL SEPARATES FROM THE MIXTURE.