| 摘要 |
PROBLEM TO BE SOLVED: To improve spectral diffraction transmittance of a texture part by raising an ultraviolet density of an image area by a method wherein in a thermal recording medium for block copy of which a light transmittance of a non- image area and the image area is specified, an electron donative color developing compound is made those represented by the formulas I to III. SOLUTION: A thermal recording medium having a thermal recording layer having an electron donative color developing compound, an electron acceptive compound, etc., as main constituens on a transparent base material, is 35% or more in all wavelength area of 380 nm to 620 nm in light transmittance of a non-image area and 10% or under in all the same wavelength area in light transmittance of an image area. Further, the electron donative compound is the formula I (R1 represents 8 or under C alkyl group, and R2 represents 8 or under C alkyl group and an hydrogen atom.), formula II (R3 represents 8 or under C alkyl group or the like, R4 represents <=4C alkyl group, R5 , R6 represent an hydrogen atom or <=4C alkyl group, and R7 represents <=8C alkyl group or a substitutable phenyl group.), and the formula III (R8 , R10 represent <=8C alkyl group, R9 represents <=8C alkyl group or an hydrogen atom, and R11 represents <=4C alkyl group, a halogen atom, etc.). |
