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:
Oct. 19, 1993
Filed:
Feb. 20, 1992
Johannes M Verheijen, Ranst, BE;
August M Marien, Westerlo, BE;
Roger I De Saedeleer, Edegem, BE;
Ludovicus M Hellemans, Boechout, BE;
Jan H Van Hove, Berchem, BE;
Agfa-Gevaert, N.V., Morstel, BE;
Abstract
A continuous direct esterification and polycondensation process is disclosed in view of the production of polyester comprising units of ethylene terephthalate as the major repeating units, said polyester being substantially improved in particular in respect of its electroconductive properties. Said process comprises supplying terephtalic acid and ethylene glycol to bis(betahydroxy ethyl) terephthalate or its oligomer so as to carry out esterification, followed by polycondensing the resulting oligomer under increasingly reduced pressure, and wherein a solution in ethylene glycol of an electroconductivity enhancing additive, preferably a metallic salt, such as e.g. magnesium acetate, is added to the oligomer reaction mixture when the esterification rate has reached at least 80% and characterized in that said ethylene glycol solution is added to the oligomer reaction mixture in such manner that escape of the added ethylene glycol out of the said oligomer reaction mixture is prohibited.