| abstract |
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, wheren 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, wheren i) in a first stage, this mixture, together with the entire amount or with a portion of a titanium catalyst, is continuously esterified or, respectively, transesterified; ii) in a second stage, the transesterification or, respectively, esterification product obtained in i) is continuously precondensed to an intrinsic viscosity of from 20 to 80 cm 3 /g to DIN 53728 in a tower reactor and concurrently by way of a falling-film evaporator, the reaction vapors being removed in situ from the reaction mixture; iii) in a third stage, the product obtainable from ii) is continuously polycondensed to an intrinsic viscosity of from 100 to 220 cm 3 /g to DIN 53728. |