| 摘要 |
<p>PURPOSE:To obtain a recording liquid for ink jet system or writing utensils, 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 phosphorus as an impurity present in an ink composition containing water-soluble dye. CONSTITUTION:The objective recording liquid, being a liquid composition containing a water-soluble dye, can be obtained by regulating the content of the phosphorus present in said composition to a level <=4ppm. This recording liquid is used in ink jet recording system operable by applying thermal energy. For the 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 the liquid through cation exchange region layer then pH adjusting. This filtrate is left at rest for 7-10 days followed by filtration.</p> |
