Inhibition of dioxane formation during recovery of glycols from polyester resins

The process for the depolymerisation of polyester into glycol and ester components comprises passing superheated methanol through a reaction mixt. contg. polyester, oligomer, and contaminants that under depolymerisation conditions are capable of forming acidic catalysts for the formation of dioxane....

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Bibliographische Detailangaben
Hauptverfasser:	GURNEY, WALTER THEODORE, GAMBLE, WILLIAM JAMES
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	ACYCLIC OR CARBOCYCLIC COMPOUNDS AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G CHEMISTRY COMPOSITIONS BASED THEREON GENERAL PROCESSES OF COMPOUNDING METALLURGY ORGANIC CHEMISTRY ORGANIC MACROMOLECULAR COMPOUNDS THEIR PREPARATION OR CHEMICAL WORKING-UP WORKING-UP
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Beschreibung
Zusammenfassung:	The process for the depolymerisation of polyester into glycol and ester components comprises passing superheated methanol through a reaction mixt. contg. polyester, oligomer, and contaminants that under depolymerisation conditions are capable of forming acidic catalysts for the formation of dioxane. Sufficient base is added during the process to neutralise acid formed from the contaminants. Pref. the polyester resin comprises polyethylene terephthalate. Pref. the base is sodium- or potassium hydroxide, or sodium- or potassium carbonate added in amt. of 0.001 - 10 g/kg polyester. Pref. the base is added in amt. to maintain the pH equiv. of the reaction at 7 - 10, pref. 7 - 8. Pref. the contaminant forms sulphuric acid or a halogen acid.