| 摘要 |
PROBLEM TO BE SOLVED: To prevent a printing face, etc., from being dirty and easily detect printed contents, etc., by using a printing ink using an insoluble azo pigment as a pigment as a printing ink to be printed to a front face and/or a rear face of a thermal paper. SOLUTION: A thermal paper 20 suitable for use in gas-, water- or the like inspecting system has a thermal layer 30 on a surface of a paper base 20. The thermal layer 30 is formed by dispersing a colorless leuco dye and an acid substance in a resin binder are applied onto the surface of the paper base 20. Frame lines 40 and required items are printed on a surface if the thermal layer 30. A printing ink used at this time is one that uses an insoluble azo pigment as a pigment. Even of components of the thermal layer 30 are dissolved in water, the insoluble azo pigment is not dissolved in the components, so that a migration at a front or rear face of the thermal paper 10 is prevented. |
