PURPOSE: To obtain an infrared phosphor, having a sufficient luminous output in high-speed reading and useful for an ink composition by supporting an organic substance having the absorption at wavelengths in the infrared region on at least one specific organic substance containing rare earths constituting the infrared phosphor.
CONSTITUTION: This infrared phosphor comprises an organic substance containing one or more rare earths selected from neodymium; ytterbium and erbium (preferably an aromatic carboxylate containing the rare earths) and is obtained by supporting an organic substance having absorption at wavelengths in the infrared region, preferably 700-1000nm (preferably a polymethylene-based, an anthraquinone-based, a dithiol metallic coloring matter, etc.) on at least one of the selected neodymium, ytterbium and erbium. This ink composition useful as an ink for the ink jet can be obtained by including the phosphor together with a binder resin in a solvent.
YAMAMOTO YOSHINORI
NISHIHARA SHOJI
SUEYOSHI TOSHINOBU
OIWA TSUNEMI
