| 摘要 |
PURPOSE:To enable images to be satisfactorily read by an optical character reader or an image reader, by using a specified phthalide compound capable of performing color reaction and having strong absorption in a near infrared region at or above a specified wavelength. CONSTITUTION:A phthalide compound of formula I, wherein R is hydrogen or an alkyl, A is hydrogen, an alkyl or halogen, and B is hydrogen or a substd. amino, is a white or pale yellow crystalline powder, shows strong absorption in a near infrared region at or above 700nm, and performs a color reaction to give a blue - green color or other color upon making contact with a color developer. A color reaction agent to be used in combination with the leuco dye may be an electron-acceptive compound, an oxidizing agent or the like. In the case of producing a pressure-sensitive recording material, a color reaction agent sheet is produced by dispersing or dissolving the color reaction agent in water or an organic solvent by using an appropriate dispersing agent, with optional addition of a binder, and applying the resultant liquid to a base such as a paper, whereas a color developer sheet is produced by dispersing the leuco dye in a microencapsulated state by using an appropriate dispersing agent, and applying the resultant liquid to a base such as a paper. On the other hand, in the case of producing a thermal recording material, liquids separately prepared by respectively dispersing the leuco dye and the color reaction agent are mixed with an appropriate binder, and the resultant mixed liquid is applied to a base such as a paper. |
