| abstract |
Mixtures of dye precursors which contain (a) the lactone of 2-carboxy-4,4'-bisdimethylaminobenzhydrol (I) and (b) crystal violet lactone and/or one or more fluoran lactones of the formula <IMAGE> (II) where R1 is alkyl, R2 is alkyl, phenalkyl, unsubstituted or substituted phenyl or cycloalkyl, or <IMAGE> is pyrrolidinyl, piperidinyl or morpholinyl, R3 is H or tert.-butyl, R4 is H or methyl, R5 is H, alkyl or phenalkyl and R6 is H, alkyl, phenalkyl, cycloalkyl or unsubstituted or substituted phenyl, or <IMAGE> is pyrrolidinyl, piperidinyl or morpholinyl, possess improved lightfastness in pressure-sensitive recording systems. |