Use of an additive composition for the preparation of polycondensation polymers

Use of an additive combination for the preparation of polycondensation polymers, wherein the additive combination is present in the polycondensation reaction and

• wherein the additive combination comprises one or more compounds of the formula (A)
• wherein
• R11, R12, R13, R14, R15, R16, R17, and R18 are independently selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert.-butyl, linear or branched pentyl, linear or branched hexyl, linear or branched heptyl, linear or branched octyl or linear and branched nonyl groups, and
• R21 and R22 are independently selected from the group consisting of hydrogen, methyl, O(C1-C6-Acyl) and O—R3, wherein R3 is selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert.-butyl linear or branched pentyl, linear or branched hexyl, linear or branched heptyl, linear or branched octyl or linear and branched nonyl groups, and
• one or more sterically hindered organic phosphorous(III) compounds selected from the group consisting of sterically hindered phenyl phosphonites and sterically hindered phosphites, and
• wherein the additive combination is used in a proportion of from 85% to 99.99% by weight of the compounds of the formula (A) and 0.01% to 15% by weight of the sterically hindered organic phosphorous(III) compounds.