Copying material employing fluoran color formers

摘要

Fluoran compounds of the formula wherein one of R1, R2, R3 and R4 represents n-alkyl having 6 to 12 carbon atoms and the other R's, independently of each other, represent hydrogen, alkyl having 1 to 12 carbon atoms, alkoxyalkyl having 2 to 8 carbon atoms or benzyl optionally substituted in the ring by nitro, halogen or alkyl having 1 to 6 carbon atoms. The fluoran compounds are particularly useful as color formers which give intense dark green color when they are brought into contact with an electron-accepting co-reactant.