Verfahren zur Herstellung von faden- oder filmbildenden Polyestern der Terephthalsaeure

摘要

In the manufacture of filament-forming phthalate polyglycol terephthalates by heating a glycol ester of terephthalic acid in presence of a metal-containing polymerization catalyst, colour formation is inhibited by effecting polymerization in presence of a phosphoric acid, an alkyl phosphate, a hydroxyalkyl phosphate or an aryl phosphate. The glycol ester is preferably made by heating a dialkyl terephthalate with the glycol in presence of an ester-interchange catalyst. Specified glycols are those of formula OH(CH2)nOH where n=2-10 and polyethylene glycols of molecular weight 106-6000. Part of the terephthalic acid may be replaced by isophthalic, hexahydroterephthalic, tribenzoic, adipic, azelaic, naphthalic or 2.5-dimethylterephthalic acids or by bis-p-carboxyphenoxyethane. In examples, dimethyl terephthalate and ethylene glycol were heated in presence of a catalyst and after no more methanol was evolved the glycol terephthalate was added to a polymerization vessel, the phosphorus compound added and the whole heated under reduced pressure, the catalyst combination being (1) zinc acetate, tetraisopropyl titanate and tri-(2-hydroxyethyl) phosphate. (2) Magnesium acetate, antimony trioxid and trihexyl phosphate. (3) Zinc acetate, lithium hydride, antimony trioxide and trihexyl phosphate. (4) Lithium hydride, lead monoxide and triphenyl phosphate. (5) Magnesium formate, lead monoxide, antimony trioxide and tributyl phosphate. (6) Lanthanum acetate, antimony trioxide and phosphoric acid or triethyl phosphate. (7) Manganous acetate, antimony trioxide and tricresyl phosphate or phosphoric acid. (8) Calcium acetate monohydrate and phosphoric acid. (9) Manganous acetate, antimony trioxide and tricresyl phosphate. (10) Zinc acetate dihydrate, tetraisopropyl titanate and tri-(2-hydroxyethyl phosphate). Phosphoric compounds referred to in addition to those exemplified are tri-isopropyl-, triamyl- and tributyl-phosphates; also diphenyl ethyl phosphate, diphenyl phosphate, dibutyl phenyl phosphate, tri-(3-hydroxypropyl) phosphate, dibutyl hydrogen phosphate and phenyl dihydrogen phosphate. Specification 578,079, [Group IV], is referred to.