Abstract: A pigment dispersion is disclosed which comprises a pigment, a pigment dispersant, and optionally a binder resin, wherein the pigment dispersion comprises as the pigment dispersion at least 0.2 parts by weight of a modified novolak resin (A) and/or a graft copolymer (B) relative to 100 parts by weight of the pigment, the modified novolak resin (A) and the graft copolymer (B) each having an aromatic ring and a ring structure given by ring opening of an epoxy group by a carboxyl group of a hydroxycarboxylic acid or a derivative thereof. An ink composition for offset printing containing the pigment dispersion is also disclosed.

Abstract: The improved polyurethane resin has a number average molecular weight of 2,000-200,000 and is prepared by reacting an organic diisocyanate compound, a polymer diol compound, a chain extender and a terminator. It is characterized by having at least one group selected from hydrazine groups, hydrazide groups and semicarbazide groups in the molecule. The polyurethane resin can be produced using a chain extender and/or a terminator that have at least one hydrazine group or hydrazide group. This polyurethane resin can be dispersed in water in the presence of an emulsifier or by first introducing free carboxyl groups into the molecule of the resin and then dissolving or dispersing it in an aqueous alkali solution or by first introducing tertiary amino groups into the molecule of the resin and then dissolving or dispersing it in an aqueous acid solution. The water-based polyurethane resin can be used either as a binder for water-based printing inks or as a water-based laminating adhesive.

Abstract: Disclosed is a water-based printing ink composition exhibiting excellently low foaming behavior with sustainability even under adverse conditions of high temperature and intense shearing force encountered in the printing works. The printing ink composition comprises, besides an organic polymer as the binder resin in the form of an aqueous solution or emulsion and a coloring agent, e.g., dyes and pigments, a silicone-based defoaming composition comprising a polyoxyalkylene-modified polydiorganosiloxane, polydimethylsiloxane, finely divided silica filler and organopolysiloxane resin mainly or solely consisting of monofunctional organosiloxane units and tetrafunctional siloxane units each in a specified weight proportion.