Verfahren zur Herstellung von filmbildenden Polyestern

摘要

A film-forming polyester is prepared by interacting a dicarboxylic acid, a hydroxy-carboxylic acid or an ester-forming derivative of either with a diol in the presence of a zinc compound, a titanium compound and an alkaline earth metal compound as catalysts. The product may be a homo- or copolymer. 70% of it may be ethylene terephthalate units derived from ethylene glycol and terephthalic acid or dimethyl terephthalate. Other dicarboxylic acids specified are oxalic, adipic, sebacic, azelaic, isophthalic, phthalic, naphthalene-2,6-dicarboxylic, diphenyl dicarboxylic, cyclobutane-1,2-dicarboxylic, sodium isophthalic acid 5-sulphonate and methyl isophthalic acid 5-sulphonate. Other diols specified are: di- and polyethylene glycol, propylene glycol, butylene glycol, ethylene thioglycol, p-xylylene glycol, 1,4-di(hydroxymethyl) cyclohexane, bisphenol-A, and 2,2-bis-(p-hydroxyethoxyphenyl) propane. Hydroxyacids specified are: p-hydroxybenzoic, vallinic, p-hydroxyethoxy-benzoic and its m-chloroderivative, p - hydroxymethyl - benzoic and glycolic acid. Other acids and alcohols which may be used are trimellitic and pyromellitic acids and glycerol and pentaerythritol. Polyesterification may be preceded by an esterinterchange reaction and may be continuous. All the catalysts may be added prior to the esterinterchange reaction or some may be added prior to or during the polycondensation. In the latter case a phosphorus compound may also be added. The amounts of catalyst welded may be: Zn compound: 0.005-0.1%, Ti compound: 0.005-0.2% and alkaline earth metal compound: 0.01-0.4%. Zinc compounds specified are zinc oxide, zinc chloride, the zinc salt of 2-mercaptobenzothiazole, zinc acetate, caproate, adipate, benzoate, carbonate and borate. Titanium compounds specified are aryl titanates, aralkyl titanates, acyl titanates, aloyl titanates, titanium trichloride, ammonium salts of titanic acid, alkali metal titanates, alkaline earth metal titanates, tetramethyl titanate, tetraethyl titanate, methyl triphenyltitanate, dipropyl dibenzyl titanate, dibutyl di-(hydroxyethyl) titanate, diisopropoxytitanium acetate dibutoxytitanium benzoate, tetrabutyl titanate and tetrastearyl titanate. Alkaline earth compounds specified are the carboxylates, hydrates, oxides and aluminates of Ca, Sr and Ba, e.g. calcium acetate. Polymerization may be above or below the melting point of the polyester. In Example (9) a phosphorus acid was added to the reaction mixture.