| 摘要 |
PURPOSE:To permit immediate recognition, by naked eyes, of the fact that a sheet-shaped base material is wet with water by providing a display layer contg. a pH indicator and alkali agent on the surface of said base material. CONSTITUTION:All pH indicators which color by reacting with the alkali agent in the presence of water are usable as the pH indicator and are exemplified by thymolphthalein, halogenated thymolpthalein, etc. The alkali agent to be used for coloring the pH indicator may be any alkali agents and is exemplified by slaked lime, sodium carbonate, etc. The display layer which colors by sensing the water is formed on the surface of the sheet-shaped base material by the above-mentioned pH indicator and alkali agent.
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