| 摘要 |
<p>A process for the continuous manufacture of linear, high molecular weight, polybutylene terephthalates, in which dimethyl terephthalate is trans-esterified with 1,4-butanediol, if desired in the presence of up to 40 mole% of other starting materials which form linear polyesters, in the molar ratio of from 1:1.2 to 1:1.5, in a plurality of successive stages at temperatures rising from 160 to 230.degree.C, the mixture thus obtained is passed, at from 230 to 270.degree.C and from 2 mm Hg to 20 mm Hg, upward through a bundle of stationary heated tubes, and immediately thereafter through a hold tank, with the proviso that the volume of the hold tank is at least 1/4 and at most 2.5 times the volume of the tube bundle and the mean residence time in the tube bundle and hold tank together is from 10 to 60 minutes, and the precondensate thus obtained is polycondensed at from 240 to 260.degree.C and from 0.1 to 2 mm Hg, with continuous formation of thin films. The polybutylene terephthalates manufactured by the above process may be used for the manufacture of products such as fibers, films, sheeting and injection moldings.</p> |
