Heterogeneous melt hydrolysis of oxymethylene copolymers

Claim 1

IN AN EXTRUDER PROCESS FOR THE STABILIZATION OF A NORMALLY SOLID OXYMETHYLENE COPOLYMER HAVING A MELTING POINT ABOVE ABOUT 150*C., THE MOLCULES OF SAID COPOLYMER CONTAINING FROM 60 TO 99.6 MOL PERCENT OF COMPARATIVELY UNSTABLE MONOMERIC OXYMETHYLENE UNITS INTERSPERSED WITH COMPARATIVELY STABLE MONOMERIC -OR- UNITS WHEREIN R IS A DIVALENT RADICAL CONTAINING AT LEAST TWO CARBON ATOMS DIRECTLY LINKED TO EACH OTHER AND POSITIONED IN THE POLYMER CHAIN BETWEN THE TWO VALENCES, WITH ANY SUBSTITUENTS ON SAID R RADICAL BEING INERT, AT LEAST PART OF THE TERMINAL PORTIONS OF SAID MOLECULES COMPRISING SAID UNSTABLE MONOMERIC UNITS, WHEREBY SAID COPOLYMER IS INTRODUCED INTO A REACTION ZONE WITH FROM ABOUT 2 TO ABOUT 25 WEIGHT PERCENT, BASED ON THE COPOLYMER, OF A REACTANT SELECTED FROM THE CLASS CONSISTING OF WATER, ALCOHOLS, AND MIXTURES THEREOF, THE IMPROVEMENT WHICH COMPRISES: A. FORMING A SYSTEM COMPRISING MOLTEN COPOLYMER AND VAPOROUS REACTANT IN SAID ZONE BY MAINTAINING THE REACTION ZONE AT A TEMPERATURE ABOVE MELTING POINT OF THE COPOLYMER AND AT A PRESSURE SUFFICIENT TO MAINTAIN THE COPOLYMER IN A MOLTEN STATE AND THE REACTANT IN A VAPOROUS STATE, AND B. REACTING THE MOLTEN COPOLYMER WITH THE REACTANT UNDER THE ABOVE CONDITIONS OF TEMPERATURES AND PRESSURE FOR A PERIOD OF TIME IN THE RANGE OF FROM ABOUT 0.1 TO ABOUT 15 MINUTES TO REMOVE UNSTABLE MONOMERIC OXYMETHYLENE UNITS FROM THE TERMINAL PORTION OF THE COPOLYMER MOLECULES SO THAT AT LEAST 90 PERCENT OF THE RESULTING POLYMERIC CHAINS OF THE MOLECULES ARE TERMINATED BY THE STABLE MONOMERIC UNITS.