| 摘要 |
In the manufacture of film- and fibre-forming polyalkylene terephthalates by polycondensing a bis(hydroxyalkyl) terephthalate, there is used as a catalyst a germanium alkoxide, e.g. germanium tetraethoxide. The bis(hydroxyalkyl) terephthalete may be obtained by a direct esterification or an ester-interchange process and in the latter case an additional catalyst may be used, e.g. calcium acetate, magnesium carbonate or a compound of cobalt, manganese or zinc. The ester-interchange catalyst may be inactivated during the polycondensation reaction by the addition of triphenyl phosphite or phosphorous acid. Titanium dioxide may also be added after the ester-interchange stage. Part of the terephthalic acid component of the polyester may be replaced by isophthalic, adipic or sebacic acids. Examples describe the manufacture of polyethylene terephthalate from dimethyl terephthalate and ethylene glycol. Specifications 795,968 and 802,700 and U.S.A. Specification 2,587,660 are referred to. |
