| 摘要 |
PURPOSE:To obtain a printed matter such as a question book in which an answer is checked when required, a color-changing glass or the like, by printing in an ink containing a color reaction agent which is colorless or forms a color when being dried and forms a color, is discolored or decolorized when being supplied with water, and a color reaction adjuvant. CONSTITUTION:A pH indicator for indicating a pH range for a color reaction, a discolorable coloring matter for indicating the pH range, a flavonoid coloring matter showing a color change upon a redox reaction or presence or absence of a substituent group in addition to a change of pH, or the like is used as a color reaction agent, while an acidic, basic or neutral compound capable of adjusting pH and/or a reducing agent or the like is used as a color reaction adjuvant. The color reaction agent and the color reaction adjuvant are dissolved in a solvent such as water or an alcohol, to which a thickener or the like is added, and the resultant material is used as an ink for printing. The color reaction adjuvant may be mixed with the color reaction agent, or may be infiltrated into a material to be printed in the form of a separate solution. Further, the color reaction adjuvant may be added to a brush pen, a sponge or the like for supplying water for color developing, discoloration or decolorization at the time of use. |
