The invention thus provides terpolymers of ethylene, at least one ethylenically unsaturated ester and propene, which have i) from 4.0 to 12.0 mol % of structural units derived from at least one ethylenically unsaturated ester having a C4- to C20-alkyl radical, ii) from 0.5 to 4.0 methyl groups derived from propene per 100 aliphatic carbon atoms, and iii) fewer than 8.0 methyl groups stemming from chain ends per 100 CH2 groups.