| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject highly purified coloring matter having excellent heat stability suitable as a coloring matter for new heat recording system by specifying the content of nickel in the coloring matter. SOLUTION: This vaporizing coloring matter has <=100 ppb nickel content. Furthermore, the vaporizing coloring matter is preferably a coloring matter selected from the group consisting of a methine-based coloring matter, an anthraquinone-based coloring matter, an azomethine-based coloring matter, an azo-based coloring matter, a quinophthalone-based coloring matter, a coumarin-based coloring matter, a perinone-based coloring matter, a xanthene- based coloring matter, a thioxanthene-based coloring matter, an azathioxanthene- based coloring matter, an oxazine-based coloring matter and a thiazine-based coloring matter and purification of the coloring matter is preferably carried out by vaporizing purification method such as sublimating purification method directly vaporizing the coloring matter from a solid state and then directly solidifying the coloring matter from gas state. |
