Process for the depolymerization of polyester scrap

• Main Authors: SATO; MINAKO, MURAKAMI; MASASHIGE, FUJITA; AKIHARU
• Format: Patent
• Language: English
• Published: 02.09.1986
• Edition: 4
• Subjects: ACYCLIC OR CARBOCYCLIC COMPOUNDS; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATERTREATMENT OR WASTE MANAGEMENT; COMPOSITIONS BASED THEREON; GENERAL PROCESSES OF COMPOUNDING; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS; METALLURGY; ORGANIC CHEMISTRY; ORGANIC MACROMOLECULAR COMPOUNDS; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; THEIR PREPARATION OR CHEMICAL WORKING-UP; WORKING-UP

Polyethylene terephthalate scrap is depolymerized to bis-hydroxyethyl terephthalate and/or its oligomer (BHT) by supplying the scrap, together with ethylene glycol, to a reactor containing molten BHT under the following conditions (a) the molten BHT has a glycol to acid component equivalent ratio of 1.3 to 2.0 (b) the ratio by weight of the acid component of the molten BHT to that of the polyester scrap is 1/4 to 2/1 (c) the ratio of polyester scrap to ethylene glycol is such as to have a glycol to acid component equivalent ratio between the limits of 1.3 to 2.0. The depolymerization is performed at 215 DEG to 250 DEG C. with agitation of the reactants, after which a part of the product in the reactor be removed to a polymerizing reactor.