| 摘要 |
PROBLEM TO BE SOLVED: To provide a process in order to dispersed a pigment in an aqueous solution. SOLUTION: The process comprises (a) a step to make ready for the pigment distinguishable for the possession of an azo group and either theβ-diketo structure or a hydroxyl group each of which bonds conjugatedly to the above azo group, (b) a step to treat the surface of the above pigment with a base having an efficient strength (for example, a pKa of at least 6) to form a negative electric charge on the above pigment, and (c) a step to react the above negatively charged pigment with either (1) a first hydrophilic molecule which has at least one functional group inclusive of a carbon-carbon double bond and a carbonyl group located in theα-position to this carbon-carbon double bond and is to form a hydrophilic group on the above pigment by an addition reaction, or (2) a second hydrophilic molecule which has at least one functional group selected from the group consisting of an anionic functional group, a cationic functional group and a zwiter-ionic functional group and at least one leaving group and is to form a hydrophilic group on the above pigment by a replacement reaction. The treated pigment is relatively solubilizable in a water-based ink and subsequently eliminates the necessity for a dispersing agent to disperse a pigment.
|
