Amino acid derivatives and their use as a sag control agent

Use as a sag control agent in a coating composition of a rheology modification agent obtainable by reacting one or more polyisocyanates with one or more-optically active amino acids, esters and/or salts thereof of the general formula (I)

• not as racemic mixture, wherein each of R1, R2, and R3 is independently selected from hydrogen and linear or branched, substituted or unsubstituted, saturated or unsaturated hydrocarbyl or heteroatom containing group, with each of R1 and R2 being different such that the carbon atom C* is a chiral centre.