| abstract |
The present invention relates to substances for defoaming aqueous media. Said substances comprise the urea derivatives of formula (I) in the form of solid particles as defoamers. In formula (I), R 1 is a hydrocarbon group having 4-30 carbon atoms, a hydrocarbon group having 4-24 carbon atoms and nitrogen atoms, or a hydrocarbon group having 4-30 carbon atoms and a carbonyl group, R 2 is hydrogen atom or a hydrocarbon group with 1-24 carbon atoms, R3 is a hydrogen atom or a hydrocarbon group with 1-24 carbon atoms, R4 is an organic group with 2-30 carbon atoms, and n is 0-5. The urea derivative is obtained by reacting isocyanate and amine in a carrier medium. The present invention is characterized in that the reaction is carried out in the presence of a monohydric alcohol of formula (VI) R 8 -OH, wherein R 8 is linear or branched, preferably branched, with 6-10 carbon atoms of alkyl. (Formula I) |