Patent ID: 8754173

Claim:
A process for the continuous production of polyester mixtures comprising: a) from 10 to 80% by weight of a biodegradable polyester (Q) composed of aliphatic or aliphatic and aromatic dicarboxylic acids and of aliphatic dihydroxy compounds, and b) from 20 to 90% by weight of one or more polymers (T) selected from the group consisting of: polylactic acid, polycaprolactone, polypropylene carbonate, polyglycolide, aliphatic polyester, cellulose acetate, and polyhydroxyalkanoate, the process comprising i) mixing the aliphatic dihydroxy compounds, the aliphatic and aromatic dicarboxylic acids and, if appropriate, further comonomers (component C) to form a mixture, without addition of any 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, and in a first stage this mixture, together with the entire amount or with a portion of the catalyst, is continuously esterified or transesterified to obtain an esterification or transesterification product; ii) in a second stage, the transesterification product or esterification product obtained in i) is continuously precondensed to an intrinsic viscosity of from 20 to 70 cm 3 /g to DIN 53728; iii) in a third stage, the product obtained from ii) is continuously polycondensed as far as an intrinsic viscosity of from 60 to 170 cm 3 /g to DIN 53728, and iv) in a fourth stage, the product obtained from iii) is continuously mixed with the polymer T, and v) optionally, in a fifth stage, the polymer mixture obtained from iv) is continuously reacted in a polyaddition reaction with a chain extender D as far as an intrinsic viscosity of from 150 to 320 cm 3 /g to DIN 53728.