| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain the subject compound having mild influence on organisms, no problems in environmental affairs and excellent properties as a coloring matter such as light resistance, coloring extensibility and the like, as many of conventionally used inks of blue color, black color, etc., or textile dyes are not preferable from the environmental aspects such as biodegradability, effects to ecosystems and the like. SOLUTION: To obtain a water-based ink or an oil-based ink by reacting a tannin (polyphenol) such as tannic acid, catechin or the like with a ferrous ion- or ferric ion-containing liquid and colored powder or colored fiber through a coloring reaction between the iron ions and the tannin by carrying out the said reaction on the surface or the inside structure of the powder or the fiber.</p> |
