| 摘要 |
<p>PURPOSE:To obtain a liquid composition for ink jet recording system, free from nozzle clogging, development of sediments and foreign substance settling on heating head, by regulating to a level below specified value the content of the iron as an impurity present in a liquid composition containing water-soluble dye. CONSTITUTION:The objective composition, being a liquid composition containing a water-soluble dye (e.g., C.I. Direct Black 17), can be obtained by regulating the content of the iron as an impurity present in said liquid composition to a level <=4ppm. For said regulation, one of the processes is as follows: Na2SO4 is added to an aqueous dye solution to subject the dye to salting-out. The resulting precipitate deposited is collected by filtration, being washed with aq. Na2SO4 solution and dried. The solid thus obtained is dissolved in a water- soluble organic solvent followed by filtration. The resultant filtrate is incorporated with water followed by passing through cation exchange resin column then pH adjusting. This filtrate is left at rest for 7-10 days followed by filtration.</p> |
