| 摘要 |
PURPOSE:To produce a near IR light-absorbing powdery material visually not recognized but well recognized as a matter or an image with a semiconductor laser light source. CONSTITUTION:A copper-containing phosphoric acid compound having a CuO/P2 O5 molar ratio of 0.05-4, the copper and the phosphoric acid being herein converted into the CuO and the P2O5, respectively, is wet-ground in the presence of water or dry-ground with a grinder not using alumina into fine powder. |
