| 摘要 |
PURPOSE:To make it possible to read a recording material with a source of light having a wavelength in the near-infrared region, by using a leuco dye of a specified structural formula as an electron-donating color former. CONSTITUTION:This leuco dye is represented by formula I (wherein R1, R2, R3, R4, R5, R6, R7 and R8 are each a lower alkyl group, X is an alkyl group or a group of formula II, III or IV, R9 is a hydrogen atom, a lower alkyl group, a halogen atom, a hydroxyl group, a trifluoromethyl group, a nitro group, an amino group, a substituted amino group or an amide group). When the leuco dye of formula I is brought into contact with an electron-accepting compound on a molecular level, a color formation reaction takes place rapidly to form a deep blue color. The lambdamax of the absorption spectrum of this color is about 800-820nm in a solution and about 500-900nm in the color-forming part of a recording paper. |
