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 MOLECULES OF SAID COPOLYMER CONTAINING FROM 60 TO 99.6 MOLE PERCENT OF COMPARATIVELY UNSTABLE MONOMERIC OXYMETHYLENE UNITS INTERSPERSED WITH COMPARATIVELY STABLE MONOMERIC-OR- UNITS INWHEREIN R IS A DIVALENT RADICAL CONTAINING AT LEAST TWO CARBON ATOMS DIRECTLY LINKED TO EACH OTHER AND POSITIONED IN THE POLYMER CHAIN BETWEEN THE TWO VALENCES, WITH ANY SUBSTITUENTS ON SAID R RADICALS BEING INERT, AT LEAST PART OF THE TERMINAL PORTIONS OF SAID MOLECULES COMPRISING SAID UNSTABLE MONOMERIC UNITS, WHEREIN THE IMPROVEMENT COMPRISES REACTING IN AN EXTRUDER SAID COPOLYMER; FROM 2 TO ABOUT 25 WEIGHT PERCENT, BASED ON THE COPOLYMER OF A REACTANT SELECTED FROM THE CLASS CONSISTING OF WATER, AND ALCOHOL, AND MIXTURES THEREOF AND FROM ABOUT 0.05 TO ABOUT 10.0 WEIGHT PERCENT BASED ON POLYMER WEIGHT OF A STABILIZER SYSTEM SELECTED FROM THE GROUP CONSISTING OF AN ACID SCAVENGER, AN ANTIOXIDANT AND AN ACID SCAVENGER AND AN ANTIOXIDANT IN A HETEROGENOUS REACTION ZONE COMPRISING MOLTEN COPOLYMER AND VAPOROUS REACTANT BY MAINTAINING THE REACTION ZONE AT A TEMPERATURE ABOVE THE MELTING POINT OF COPOLYMER AND AT A PRESSURE SUFFICIENT TO MAINTAIN THE COPOLYMER IN A MOLTEN STATE AND THE REACTANT IN A VAPOR STATE, AND SAID SYSTEM IS REACTED UNDER THE ABOVE CONDITIONS OF TEMPERATURE 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 PORTIONS 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.