PIGMENT DISPERSING AGENT AND OFFSET PRINTING INK COMPOSITION EMPLOYING THE SAME

摘要

A pigment dispersing agent comprising the reaction product of a polyester having a free carboxyl group, of which the acid value is in the range of from 10 to 60, with an amine compound of the formula: (wherein R1 and R2 are alkylene radicals which can be the same or different, each containing from 2 to 6 carbon atoms, and R3 is a radical of the formula CH3- or C2H5-,), wherein said reaction being conducted in the range of from 0.8 to 1.0 of equivalent molar ratio of the amino groups having active hydrogen of said amine compound to the free carboxyl groups of said polyester. Application of the dispersing agent to nonaqueous paint or printing inks enables pigments to be dispersed in the vehicle at higher concentrations with low viscosity than in the prior art, and the dispersions thus obtained exhibit high coloring power and excellent storage stability.