WATER-BASED PIGMENT INK

摘要

PROBLEM TO BE SOLVED: To obtain the subject ink good in pigment dispensability over a long period and under high-temperature storage by blending water with a pigment, a high molecular dispersant comprising a copolymer from an alkylene oxide- added (meth)acrylic acid derivative and a specific monomer and an anionic surfactant. SOLUTION: This water-based pigment ink excellent in pigment dispersion stability over a long period and under high-temperature storage, thus suitable for ink jet printing use, is obtained by blending water with (A) a pigment such as carbon black, (B) a high molecular dispersant comprising a copolymer from an alkylene oxide-added (meth)acrylic acid derivative of formula I (R1 and R2 are each H or a lower alkyl: (m1 ) is an integer of 0-2; AO is a 2-3C oxyalkylene group; (n) is an integer of 1-300; X is H or a lower alkyl) and a monomer of formula II [R3 to R5 are each H, a lower alkyl or of the formula (CH2 )m2 COOHM2 (M2 is H, an alkali metal, alkaline earth metal, ammonium, etc.; (m2 ) is an integer of 0-2); M1 is the same kinds as M2 ], and (C) an anionic surfactant such as an alkylbenzenesulfonate.