| 摘要 |
PROBLEM TO BE SOLVED: To obtain an ink composition which can give a recording image having water resistance and high quality by incorporating water, a colorant, a cationic water-soluble polymer, and an inorganic salt into the ink composition. SOLUTION: This ink composition comprises deionized water; 0.5-20 wt.% colorant such as an alkali-soluble oil-soluble dye, a basic dye, a water-soluble acid dye, or a direct dye; 0.1-20 wt.% cationic water-soluble polymer comprising a homopolymer of e.g. polyethyleneimine having a structure selected from among ethyleneimine, allylamine, diallyamine, etc., in the molecule or a copolymer of such a monomer with vinyl acetate or the like and having a weight-average molecular weight of 300-20,000; and 0.5-5 wt.% inorganic salt (e.g. sodium chloride or potassium bromide) present in the state dissociated in the ink. This composition may additionally contain 5-20 wt.% humectant comprising a water- soluble organic solvent such as ethylene glycol and a saccharide; a penetration accelerator such as a lower alcohol; pH modifier; hydrotropic agent; an antimold; a chelating agent; a preservative; a rustproofing agent; etc. |
