The use of graft copolymers obtainable by grafting a) polyalkylene oxides with b) at least one monomer selected from the group of b.sub.1) C.sub.1 -C.sub.30 -alkyl esters of monoethylenically unsaturated C.sub.3 -C.sub.8 -carboxylic acids; b.sub.2) vinyl esters of aliphatic C.sub.1 -C.sub.30 -carboxylic acids; b.sub.3) C.sub.1 -C.sub.30 -alkyl vinyl ethers; b.sub.4) N--C.sub.1 -C.sub.12 -alkyl-substituted amides of monoethylenically unsaturated C.sub.3 -C.sub.8 -carboxylic acids; b.sub.5) N,N--C.sub.1 -C.sub.12 -dialkyl-substituted amides of monoethylenically unsaturated C.sub.3 -C.sub.8 -carboxylic acids as solubilizer.

O uso dos copolymers do graft obteníveis grafting a) óxidos do polyalkylene com b) ao menos o um monomer selecionado do grupo de b.sub.1) C.sub.1 - C.sub.30 - esters alkyl de C.sub.3 monoethylenically unsaturated - C.sub.8 - ácidos carboxylic; ) esters do vinil b.sub.2 de C.sub.1 aliphatic - C.sub.30 - ácidos carboxylic; b.sub.3) C.sub.1 - C.sub.30 - ethers alkyl do vinil; b.sub.4) N -- C.sub.1 - C.sub.12 - amidos alkyl-substituted de C.sub.3 monoethylenically unsaturated - C.sub.8 - ácidos carboxylic; b.sub.5) N,N -- C.sub.1 - C.sub.12 - amidos dialkyl-substituídos de C.sub.3 monoethylenically unsaturated - C.sub.8 - ácidos carboxylic como o solubilizer.