Mixture composition comprising a first alkyl carboxylate group of the general formula (la) and a second alkyl carboxylate group of the general formula (Ib) with R 1a and R 1b chosen from saturated or unsaturated, linear or branched, optionally hydroxy-substituted, hydrocarbon acyl radicals exhibiting from 10 to 30, preferably from 10 to 22, particularly preferably from 10 to 18, carbon atoms, R 2a and R 2b each chosen from saturated or unsaturated, linear or branched, optionally hydroxy-substituted, hydrocarbon radicals exhibiting from 12 to 22, preferably from 12 to 18, particularly preferably from 12 to 14, carbon atoms, with the proviso that R 2a is different from R 2b, and that the alkyl carboxylates of the first group and of the second group in total are present in an amount of at least 55% by weight, preferably at least 70% by weight, particularly preferably at least 80% by weight, the percentages by weight referring to all alkyl carboxylates present in the mixture composition, characterized in that the ratio by weight of all alkyl carboxylates of the first group to all alkyl carboxylates of the second group is from 10.0:1.0 to 1.0:1.0, preferably from 4.0:1.0 to 1.5:1.0, particularly preferably from 3.5:1.0 to 2.0:1.0. a first alkyl carboxylate group of the general formula (la) and a second alkyl carboxylate group of the general formula (Ib) with R 1a and R 1b chosen from saturated or unsaturated, linear or branched, optionally hydroxy-substituted, hydrocarbon acyl radicals exhibiting from 10 to 30, preferably from 10 to 22, particularly preferably from 10 to 18, carbon atoms, R 2a and R 2b each chosen from saturated or unsaturated, linear or branched, optionally hydroxy-substituted, hydrocarbon radicals exhibiting from 12 to 22, preferably from 12 to 18, particularly preferably from 12 to 14, carbon atoms, with the proviso that R 2a is different from R 2b, and that the alkyl carboxylates of the first group and of the second group in total are present in an amount of at least 55% by weight, preferably at least 70% by weight, particularly preferably at least 80% by weight, the percentages by weight referring to all alkyl carboxylates present in the mixture composition, characterized in that the ratio by weight of all alkyl carboxylates of the first group to all alkyl carboxylates of the second group is from 10.0:1.0 to 1.0:1.0, preferably from 4.0:1.0 to 1.5:1.0, particularly preferably from 3.5:1.0 to 2.0:1.0. R 1a and R 1b chosen from saturated or unsaturated, linear or branched, optionally hydroxy-substituted, hydrocarbon acyl radicals exhibiting from 10 to 30, preferably from 10 to 22, particularly preferably from 10 to 18, carbon atoms, R 2a and R 2b each chosen from saturated or unsaturated, linear or branched, optionally hydroxy-substituted, hydrocarbon radicals exhibiting from 12 to 22, preferably from 12 to 18, particularly preferably from 12 to 14, carbon atoms, with the proviso that R 2a is different from R 2b, and that the alkyl carboxylates of the first group and of the second group in total are present in an amount of at least 55% by weight, preferably at least 70% by weight, particularly preferably at least 80% by weight, the percentages by weight referring to all alkyl carboxylates present in the mixture composition, characterized in that the ratio by weight of all alkyl carboxylates of the first group to all alkyl carboxylates of the second group is from 10.0:1.0 to 1.0:1.0, preferably from 4.0:1.0 to 1.5:1.0, particularly preferably from 3.5:1.0 to 2.0:1.0.