Production of granular polyvinyl alcohol

Claim 1

IN A PROCESS FOR THE PRODUCTION OF POLYVINYL ALCOHOL BY THE CATALYZED ALCOHOLYSIS OF A POLYVINYL ESTER IN WHICH A SOLUTION OF THE POLYVINYL ESTER IN A HYDROLYTIC ALCOHOL IS FED TO AN AGITATED ALCOHOLYSIS MIXTURE AND A SLURRY OF POLYVINYL ALCOHOL IN A SOLVENT MIXTURE COMPRISING SAID HYDROLYTIC ALCOHOL AND THE ESTER OF SAID HYDROLYTIC ALCOHOL WITH THE ACID RESIDUE OF THE POLYVINYL ESTER IS REMOVED FROM SAID ALCOHOLYSIS MIXTURE, SAID ALCOHOLYSIS MIXTURE CONSISTING ESSENTIALLY OF SAID POLYVINYL ESTER, AN ALCOHOLYSIS CATALYST, SAID HYDROLYTIC ALCOHOL, SAID ESTER OF SAID HYDROLYTIC ALCOHOL AND POLYVINYL ALCOHOL, THE IMPROVEMENT COMPRISING FEEDING AT LEAST A PART OF SAID POLYVINYL ESTER SOLUTION IN INTERMITTENT PORTIONS OF SUCH SIZE THAT SAID ALCOHOLYSIS MIXTURE THICKENS AS EACH SAID PORTION AFTER ITS ADDITION TO SAID ALCOHOLYSIS MIXTURE PASSES THROUGH A GEL PHASE, EACH SUCH INTERMITTENT PORTION BEING OF SUCH SIZE AND BEING FED AT SUCH A RATE THAT IF SUCH RATE OF FEED WERE MAINTAINED CONTINUOUSLY SAID ALCOHOLYSIS MIXTURE WOULD SET UP TO A NON-MOVING GELLED MASS, THE TIME INTERVAL BETWEEN SUCCEEDING SAID PORTIONS BEING SUFFICIENT FOR SAID ALCOHOLYSIS MIXTURE TO REVERT TO A NON-THICKENED CONDITION AFTER EACH SAID PORTION PASSES THROUGH THE GEL PHASE AND BEFORE THE NEXT SUCCEDING SAID PORTION PASSES INTO THE GEL PHASE, AND RECOVERING FROM SAID SLURRY OF POLYVINYL ALCOHOL A SUBSTANTIALLY NON-DUSTY GRANULAR POLYVINYL ALCOHOL.