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 formula (I)
• Y(—OH)q (I)
• or mixtures thereof,
• 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 formula (II) having NCO groups of different reactivity
• R1(NCO)2 (II)
• or mixtures thereof,
• wherein
• R1 is the same or different and is represented by a hydrocarbon radical having 6 to 20 carbon atoms, comprising an arylene group, a branched or unbranched alkylarylene group, and/or an acyclic, cyclic, branched or unbranched alkylene group,
• wherein the diisocyanate of formula (II) is used with respect to the hydroxy component of formula (I) in a molar ratio of at least (1.1*arithmetic mean of q):1.0, so that an isocyanate adduct of formula (III)
• Y(—O—CO—NH—R1—NCO)q (III)
• or mixtures thereof,
• wherein
• Y, q and R1 are each as described above,
• and unreacted diisocyanate of formula (II) containing reaction mixture is formed,
• in step ii) at least 50 mol % of the unreacted portion of the diisocyanate of formula (II) is removed from the reaction mixture,
• in step iii) a compound of formula (IV) having at least one head group radical Z1
• Y(—O—CO—NH—R1—NH—CO—X—Z1)q (IV)
• or mixtures thereof,
• wherein
• Y, q and R1 are each as described above,
• X is the same or different and is represented by O, 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 formula (III) present in the reaction mixture is reacted with an isocyanate-reactive compound of 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.