| abstract |
In the production of polyesters and copolyesters, titanium dioxide/silicon dioxide co-precipitates with a composition of TiO2:SiO2 = 90:10 to 20:80 mol/mol and/or titanium dioxide/zirconium dioxide co-precipitates with a composition of TiO2:ZrO2 = 95:5 to 70:30 mol/mol are proposed as polycondensation catalysts. They exhibit greater catalytic activity than Sb2O3, so that the preferred proportion of additive is only 10 to 100 ppm in relation to the esters or oligo esters to be poly-condensed. |