The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 15, 1979
Filed:
Jun. 19, 1978
Gurdial Singh, Greenville, NC (US);
E. I. Du Pont de Nemours and Company, Wilmington, DE (US);
Abstract
The formation of manganese-derivative scale in equipment involved in polyester manufacture is reduced by introduction of a sterically hindered benzoic acid in approximately stoichiometric amount. The acids include 2,6-dichloro-, 2,6-dimethyl- and 2,4,6-trimethylbenzoic acids. The scale is believed to be insoluble manganese terephthalate, presumably formed by reaction of manganese acetate catalyst generated as a result of a side reaction during the ester exchange reaction of dimethyl terephthalate with excess ethylene glycol. Preferably an alkali metal salt of an organic acid, such as sodium acetate or lithium acetate is also used to give a synergistic effect in combination with the hindered acid.