| 摘要 |
The present invention relates to a process for the continuous production of a biodegradable polyester based on aliphatic or aliphatic and aromatic dicarboxylic acids and on aliphatic dihydroxy compounds, where a mixture composed of the aliphatic dihydroxy compounds, of the aliphatic and aromatic dicarboxylic acids, and, if appropriate, of further comonomers (component C) is mixed, without addition of a catalyst, to give a paste, or, as an alternative, the liquid esters of the dicarboxylic acids are fed into the system, as also are the dihydroxy compound and, if appropriate, further comonomers, without addition of any catalyst, and i) in a first stage, this mixture, together with the entire amount or with a portion of the catalyst, is continuously esterified or, respectively, transesterified; ii) in a second stage, the transesterification or, respectively, esterification product obtained in i) is continuously precondensed if appropriate with the remaining amount of catalyst to an intrinsic viscosity of from 20 to 70 cm3/g to DIN 53728; iii) in a third stage, the product obtainable from ii) is continuously polycondensed to an intrinsic viscosity of from 60 to 170 cm3/g to DIN 53728, and iv) in a fourth stage, the product obtainable from iii) is reacted continuously with a chain extender D in a polyaddition reaction to an intrinsic viscosity of from 150 to 320 cm3/g to DIN 53728. The invention further relates to biodegradable polyesters which are accessible for the first time by this process.
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