| 摘要 |
PROBLEM TO BE SOLVED: To obtain a recording ink which causes neither clogging of an ink jet printer during printing nor sedimentation during storage even when it contains a dye in a high concn. by keeping the content of acetate ions in the ink at a specified value or lower. SOLUTION: Sodium sulfate is added to an aq. dye soln. having a specified concn. to precipitate the dye by salting out. The resulting precipitates are separated by filtration, washed with a satd. pure-water soln. of sodium sulfate, and dried. A certain amt. of the resulting dried solid is dissolved in a water-sol. org. solvent which is a poor solvent for sodium sulfate and a good solvent for the dye and then filtered. The resulting filtrate is mixed with a certain amt. of water under stirring, passed through an anion exchange resin to remove anions, and confirmed by ion chromatography analysis that the acetate ion content is lower than 90ppm. |
