Patent ID: 9040639
Filing Date: 2015-05-26
Classification: C08G

Abstract:
1. A biodegradable polyester based on aliphatic and aromatic dicarboxylic acids and on aliphatic dihydroxy compounds, obtained by a continuous process, the process comprising mixing the aliphatic dihydroxy compounds, the aliphatic and aromatic dicarboxylic acids, and, optionally, 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, optionally, further comonomers, without addition of any catalyst, where 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 to an intrinsic viscosity of from 20 to 70 cm iii) in a third stage, the product obtainable from ii) is continuously polycondensed to an intrinsic viscosity of from 60 to 170 cm 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 cm where stage ii) is carried out in a tower reactor, and the product stream is conducted concurrently by way of a falling-film cascade, and the reaction vapors are removed in situ from the reaction mixture; and where, in stage ii), the transesterification product or esterification product is precondensed to an intrinsic viscosity of from 25 to 55 cm