| 摘要 |
PURPOSE:To eliminate the change of a color tone of ink back-flow preventive element even after it is stored for a long period by incorporating water-soluble black dye in water base ink, and coloring the element with color tone similar to the color of the by-product or unreacted substance of the black dye. CONSTITUTION:Water base ink 3 is contained in an ink containing tube 1. The ink 3 contains a colorant and water, and the colorant uses a water-soluble black dye. An ink back-flow preventive element 4 which is not compatible with the ink 3 is contained in the other ends side of the ink 3. The element 4 contains a hard volatile organic liquid selected from hydrocarbons and the like or silicon oil, or grease in gel state as main ingredients. It is necessary that the element 4 is colored with a color tone similar to the color of the by- product or the unreacted substance of the black dye used for the ink 3 to suppress and prevent aging discoloring. |
