Method for producing dispersant additives

A method for producing an additive composition, comprising the steps i) to iii), wherein

• in step i) a hydroxy component of the general formula (I)
• Y(—OH)q (I)
• wherein
• Y is the same or different and is represented by a branched or unbranched, saturated or unsaturated organic radical having 1 to 1000 carbon atoms,
• q is the same or different and represented by an integer from 1 to 10
• is reacted with a diisocyanate of the general formula (II) having NCO groups of different reactivity
• R1(NCO)2 (II)
• wherein
• R1 is the same or different and is represented by a branched or unbranched, saturated or unsaturated organic radical having 6 to 20 carbon atoms,
• wherein the diisocyanate of the general formula (II) is used with respect to the hydroxy component of the general formula (I) in a molar ratio of at least (1.1*arithmetic mean of q):1.0, so that an isocyanate adduct of the general formula (III)
• Y(—O—CO—NH—R1—NCO)q (III)
• wherein
• Y, q and R1 are each as described above,
• and unreacted diisocyanate of the general formula (II) containing reaction mixture is formed,
• in step ii) at least 50 mol % of the unreacted portion of the diisocyanate of the general formula (II) is removed from the reaction mixture,
• in step iii) a compound of the general formula (IV) having at least one head group radical Z1
• Y(—O—CO—NH—R1—NH—CO—X—Z1)q (IV)
• wherein
• Y, q and R1 are each as described above,
• X is the same or different and is represented by 0, NH and/or NZ2
• wherein
• Z2 is the same or different and is represented by a branched or unbranched, saturated or unsaturated organic radical,
• Z1 is the same or different and is represented by a branched or unbranched, saturated or unsaturated organic radical having at least two carbon atoms having at least one head group which is present in salifiable or salified form, and is selected from the group consisting of tertiary amino functions, quaternary ammonium functions, phosphoric acid ester functions, and carboxylic acid functions,
• wherein step iii) is carried out in a single stage iii-a) or a sequence of steps iii-b),
• in step iii-a) the isocyanate adduct of the general formula (III) present in the reaction mixture is reacted with an isocyanate-reactive compound of general formula (V) having said head group radical Z1,
• HX—Z1 (V)
• wherein
• X and Z1 are each as described above,
• and in the sequence of steps iii-b), first, the isocyanate adduct of the formula (III) which is present in the reaction mixture is reacted with a compound having a isocyanate-reactive group HX and at least one further functional group Q, wherein then Q is reacted with a reagent involved in the generation of the head group radical Z1 to form the head group radical Z1.