Composition comprising (a) at least one polymeric aromatic carbodiimide of formula R 4 -R 8 -(-N=C=N-R 8 -) m -R 4, in which m represents an integer from 2 to 500, R 8 is C 1 -C 12 -alkyl-substituted arylenes, C 7 -C 18 -alkylaryl-substituted arylenes and optionally C 1 -C 12 -alkyl-substituted alkylene-bridged arylenes comprising a total of 7 to 30 carbon atoms, and arylene, and R 4 is -NCO, -NCNR 5, -NHCONHR 5, -NHCONR 5 R 6 or-NHCOOR 7, wherein R 5 and R 6 are identical or different and represent a C 1 -C 12 -alkyl, C 6 -C 12 -cycloalkyl, C 7 -C 18 -aralkyl or aryl radical and R 7 represents a C 1 -C 22 -alkyl, C 6 -C 12 -cycloalkyl, C 6 -C 18 -aryl or C 7 -C 18 -aralkyl radical and an unsaturated alkyl radical having 2 - 22 carbon atoms or an alkoxypolyoxyalkylene radical, (b) at least one ester selected from the group comprising C 9 -C 10 -alkyl esters of benzoic acid, di- (C 8 -C 12) -alkyl esters of aliphatic dicarboxylic acids, polyesters of aliphatic dicarboxylic acids, or mixtures of these dicarboxylic acids with C 2 -C 8 -aliphatic diols or polyols, the end groups of which are non-esterified or have been esterified with monofunctional compounds, and the number-average molar mass of which is 1000 - 20 000 g/mol, tri(C 2 -C 6)-alkyl esters of citric acid, acetylated tri (C 2 -C 6) -alkyl esters of citric acid, glycerol esters, benzoic acid diesters of mono-, di-, tri- or poly(C 2 -C 3)-alkylene glycols, trimethylolpropane esters, pentaerythritol esters, di(C 8 -C 12)-alkyl esters of cyclohexanedicarboxylic acids, di(C 4 -C 12)-alkyl esters of terephthalic acid, di(C 8 -C 12)-alkyl esters of phthalic acid, tri(C 8 -C 12)-alkyl esters of trimellitic acid, tri(C 6 -C 10)-aryl esters of phosphoric acid, di(C 6 -C 10)-aryl(C 8 -C 12)-alkyl esters of phosphoric acid, tri(C 8 -C 12)-alkyl esters of phosphoric acid, or (C 6 -C 10)-aryl esters of C 10 -C 21 -alkanesulfonic acids and (c) polyvinyl chloride or polyvinyl butyral. (a) at least one polymeric aromatic carbodiimide of formula R 4 -R 8 -(-N=C=N-R 8 -) m -R 4, in which m represents an integer from 2 to 500, R 8 is C 1 -C 12 -alkyl-substituted arylenes, C 7 -C 18 -alkylaryl-substituted arylenes and optionally C 1 -C 12 -alkyl-substituted alkylene-bridged arylenes comprising a total of 7 to 30 carbon atoms, and arylene, and R 4 is -NCO, -NCNR 5, -NHCONHR 5, -NHCONR 5 R 6 or-NHCOOR 7, wherein R 5 and R 6 are identical or different and represent a C 1 -C 12 -alkyl, C 6 -C 12 -cycloalkyl, C 7 -C 18 -aralkyl or aryl radical and R 7 represents a C 1 -C 22 -alkyl, C 6 -C 12 -cycloalkyl, C 6 -C 18 -aryl or C 7 -C 18 -aralkyl radical and an unsaturated alkyl radical having 2 - 22 carbon atoms or an alkoxypolyoxyalkylene radical, m represents an integer from 2 to 500, R 8 is C 1 -C 12 -alkyl-substituted arylenes, C 7 -C 18 -alkylaryl-substituted arylenes and optionally C 1 -C 12 -alkyl-substituted alkylene-bridged arylenes comprising a total of 7 to 30 carbon atoms, and arylene, R 4 is -NCO, -NCNR 5, -NHCONHR 5, -NHCONR 5 R 6 or-NHCOOR 7, wherein R 5 and R 6 are identical or different and represent a C 1 -C 12 -alkyl, C 6 -C 12 -cycloalkyl, C 7 -C 18 -aralkyl or aryl radical and R 7 represents a C 1 -C 22 -alkyl, C 6 -C 12 -cycloalkyl, C 6 -C 18 -aryl or C 7 -C 18 -aralkyl radical and an unsaturated alkyl radical having 2 - 22 carbon atoms or an alkoxypolyoxyalkylene radical, (b) at least one ester selected from the group comprising C 9 -C 10 -alkyl esters of benzoic acid, di- (C 8 -C 12) -alkyl esters of aliphatic dicarboxylic acids, polyesters of aliphatic dicarboxylic acids, or mixtures of these dicarboxylic acids with C 2 -C 8 -aliphatic diols or polyols, the end groups of which are non-esterified or have been esterified with monofunctional compounds, and the number-average molar mass of which is 1000 - 20 000 g/mol, tri(C 2 -C 6)-alkyl esters of citric acid, acetylated tri (C 2 -C 6) -alkyl esters of citric acid, glycerol esters, benzoic acid diesters of mono-, di-, tri- or poly(C 2 -C 3)-alkylene glycols, trimethylolpropane esters, pentaerythritol esters, di(C 8 -C 12)-alkyl esters of cyclohexanedicarboxylic acids, di(C 4 -C 12)-alkyl esters of terephthalic acid, di(C 8 -C 12)-alkyl esters of phthalic acid, tri(C 8 -C 12)-alkyl esters of trimellitic acid, tri(C 6 -C 10)-aryl esters of phosphoric acid, di(C 6 -C 10)-aryl(C 8 -C 12)-alkyl esters of phosphoric acid, tri(C 8 -C 12)-alkyl esters of phosphoric acid, or (C 6 -C 10)-aryl esters of C 10 -C 21 -alkanesulfonic acids and (c) polyvinyl chloride or polyvinyl butyral.