| abstract |
Pressure-sensitive copying material containing included in its Color-reactant system a mixture of at least two color formers, wherein at least one color former is a leuco methylene dyestuff of the formula Y-CH-Y (1) ¦ Z wherein Y represents an amino-substituted phenyl residue of the formula OR AN INDOLYL RESIDUE OF THE FORMULA WHEREIN R1 and R2, independently of the other represent hydrogen, alkyl with 1 to 12 carbon atoms, alkoxyalkyl with 2 to 8 carbon atoms, benzyl or phenyl, R3 is hydrogen, halogen, nitro, alkyl having 1 to 4 carbon atoms or alkoxy having 1 to 4 carbon atoms, X1 represents hydrogen, alkyl with 1 to 12 carbon atoms, alkenyl with at most 12 carbon atoms or benzyl, X2 represents hydrogen, alkyl with 1 to 12 carbon atoms or phenyl and the ring A is unsubstituted or substituted by cyano, nitro, halogen, alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms or acyl with 1 to 8 carbon atoms, and Z represents alkyl with 1 to 12 carbon atoms, alkenyl with at most 12 carbon atoms, aryl, aralkyl, an heterocyclic radical or the residue of an organic, particularly aliphatic or cycloaliphatic compound having a ketomethylene group. |