Improved process for preparing oligomeric glycol esters of dicarboxylic acids

The invention provides a process for the preparation of a polyester oligomer capable of being further polymerized to a high polymer wherein a glycol-dicarboxylic acid ester feed is treated in a secondary esterification zone under conditions such that the partial vapor pressures of water and glycol a...

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Bibliographische Detailangaben
1. Verfasser: MAURER, CHARLES J
Format: Patent
Sprache:eng ; fre ; ger
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Beschreibung
Zusammenfassung:The invention provides a process for the preparation of a polyester oligomer capable of being further polymerized to a high polymer wherein a glycol-dicarboxylic acid ester feed is treated in a secondary esterification zone under conditions such that the partial vapor pressures of water and glycol are maintained at a cumulative level of less than 740 Torr, with water and glycol vapors being continuously removed from the secondary esterification zone, and free glycol being added to the secondary esterification zone in an amount sufficient to maintain a stable amount of liquid glycol in the secondary esterification zone. In various preferred embodiments of the invention, the secondary esterification zone can be maintained at a pressure substantially below atmospheric and the vapors from secondary esterification can be passed to a reflux column wherein glycol is condensed and returned to the secondary esterification zone, or the secondary esterification can be maintained at a pressure of about atmospheric and an inert gas can be injected into the vapor space thereby lowering the partial vapor pressures of water and glycol.