The alkoxylate mixtures comprise alkoxylates of the formula (I) C.sub.5H.sub.11CH(C.sub.3H.sub.7)CH.sub.2O(A).sub.n(B).sub.mH (I) where A is ethyleneoxy, B is C.sub.3-10-alkyleneoxy or mixtures thereof, where groups A and B may be present in random distribution, alternately or in the form of two or more blocks in any order, n is a number from 0 to 30, m is a number from 0 to 20 n+m is at least 1 where 70 to 99% by weight of alkoxylates A1 in which C.sub.5H.sub.11 has the meaning n-C.sub.5H.sub.11, and 1 to 30% by weight of alkoxylates A2 in which C.sub.5H.sub.11 has the meaning C.sub.2H.sub.5CH(CH.sub.3)CH.sub.2 and/or CH.sub.3CH(CH.sub.3)CH.sub.2CH.sub.2, are present in the mixture.