| 摘要 |
PURPOSE:To prevent fading of a leuco dye by including a leuco dye expressed by the specific formula as the dispersion material of a soln. electrolyzed in a hydrophobic solvent into a hydrophilic medium into a water permeable layer. CONSTITUTION:At least one water permeable layer is provided on a light transmissive base and the leuco dye expressed by the formula (R<1> denotes an aryl group which may be substd.; R<2> denotes an alkyl group which may be substd.; R<3> denotes an alkyl group which may be substd.) is incorporated as the dispersion material of the soln. dissolved in the hydrophobic solvent into the hydrophilic medium. The substituent which may have the alkyl group expressed by R<1> includes a hydroxy group, etc.; the alkyl group expressed by R<2> may be substd. and includes a phenyl group, etc.; the substituent which may have the aryl group expressed by R<3> is a hydroxyl group, etc. The fading of the leuco dye is thereby substantially prevented.
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