Defoamer for defoaming of aqueous media

摘要

The invention relates to compositions for defoaming aqueous media, comprising as defoamers urea derivatives of the formula I where R1-is a hydrocarbon radical, preferably having 4 to 30 carbon atoms or a hydrocarbon radical, preferably having 4 to 24 carbon atoms and one nitrogen atom or a hydrocarbon radical, preferably having 4 to 30 carbon atoms and one carbonyl group, R2-is a hydrogen atom or a hydrocarbon radical, preferably having 1 to 24 carbon atoms, R3-is a hydrogen atom or a hydrocarbon radical, preferably having 1 to 24 carbon atoms, R4-is an organic radical, preferably having 2 to 30 carbon atoms, and n-is from 0 to 5; in the form of solid particles, which are obtained by crystallization from a clear homogeneous melt dispersed in a carrier medium, and a process of preparation thereof.