CRYSTAL OF FLUORAN COMPOUND, PRODUCTION OF THE SAME CRYSTAL AND RECORDING MATERIAL CONTAINING THE SAME CRYSTAL

摘要

PURPOSE:To provide a new compound useful as a color-developing compound suitable for a recording material such as a pressureor heat-sensitive recording material. CONSTITUTION:A crystal of a fluoran compound represented by formula I, shoeing peaks at 7.5 deg. and 17.0 angle of diffraction (2theta) and relatively strong peaks at 15.1 deg., 19.1 deg., 21.5 deg. and 35.3 deg. in X rat diffraction method by Cu-K rays. The compound of formula I can be obtained by reacting a benzoic acid derivative of formula II with a diphenylamine derivative of formula III (R is 1-4C lower alkyl) in the presence of a dehydration condensation agent (e.g. concentrated sulfuric acid) at 0-100 deg.C and subsequently treating it with an alkali. The crystal of the above-mentioned compound is deposited, e.g. by cooling a formula I compound-containing solution in an organic solvent (e.g. benzene) containing >=30wt.% aromatic hydrocarbon solvent. The obtained crystal can be readily finely ground and is suitable for preparation of a recording material. The prepared heatsensitive recording material is excellent in thermal resistance of the color-undeveloped part.