| 摘要 |
<p>Polyester is prepared from polyethyleneterephthalate units by glycol-reesterification of terephthalic acid ester by means of a catalyst that consists of the mangane salt, subsequently subjected to polycondensation by means of a mixed catalyst containing mangane and the germanium salt. From 80 to 99 percent of the mangane salt is blocked by inorganic phosphorous compounds and the residual free mangane and germanium salt are, directly before a vacuum phase, used as a mixed catalyst for the purpose of polycondensation catalysis in the concentration ranging from 10 to 100 ppm of germanium and 10 to 100 ppm of mangane, with respect to dimethylterphthalate, with the proviso that the mol ratio P/Mn less than 1.</p> |
