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AssigneeAkzo Nobel N.V.
InventorsMichael Martl, Thomas Mezger, Gerriet Oberlein, Klaus Haferland, Bertram Bohringer, Ulrich Berger
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For the preparation of polyesters and copolyesters, titanium dioxide/silicon dioxide coprecipitates having a composition of TiO.sub.2 :SiO.sub.2 =90:10 to 20:80 mol/mol and/or titanium dioxide/zirconium dioxide coprecipitates having a composition of TiO.sub.2 : ZrO.sub.2 =95:5 to 70:30 mol/mol are proposed as polycondensation catalysts. They have a higher catalytic activity than Sb.sub.2 O.sub.3, so that the preferred amount used is only 10 to 100 ppm, based on the esters or oligoesters to be subjected to polycondensation.
Process for the preparation of polyesters and copolyesters by polycondensation of polyester-forming starting components, esters or oligoesters being prepared in a first reaction stage and subjected to polycondensation in a second reaction stage in the presence of titanium catalysts, wherein, in the polycondensation stage, at least one of a titanium dioxide/silicon dioxide coprecipitate having a composition of TiO.sub.2 :SiO.sub.2 =90:10 to 20:80 mol/mol and a titanium dioxide/zirconium dioxide coprecipitate having a composition of TiO.sub.2 :ZrO.sub.2 =95:5 to 70:30 mol/mol, which at least one coprecipitate is obtained by hydrolytic precipitation of metal alcoholates corresponding to each component of the coprecipitate and formed from monohydric or polyhydric alcohols, is employed as the polycondensation catalyst for polycondensation of the esters or oligoesters.
Dependencies are inferred from the claim text.