| 摘要 |
PROBLEM TO BE SOLVED: To obtain a dispersant which, even when used in a small amount, can stably disperse a pigment to form an aqueous pigment dispersion excellent in storage stability by using a polyisocyanate compound having a specified average NCO functionality as the starting material and introducing anionic groups into the NCO groups through urethane bonds. SOLUTION: The starting material used is a polyisocyanate compound having an average NCO functionality of above 2, desirably, 2.1-20, desirably having an aromatic ring and/or having an isocyanurate ring, and/or being tolylene diisocyanate. Anionic groups, desirably, sulfo groups are introduced into the NCO groups through urethane bonds. A desirable method for introducing anionic groups consists of reacting a compound containing at least one active H group and at least one anionic group in the molecule, (e.g. 2-hydroxyethoxybenzene-4- sulfonic acid) with a polyisocyanate compound.
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