Imprint sheets of a self-copy set

摘要

For better recognition of forgeries the invention proposes an imprint sheet of a self-copy set which on one of its sides has an i mprint layer containing a dye coupling developer used for reacting with colorless dye precursors. The imprint layer also contains one or more dye precursors in solid form which are freely accessible and not isolated from the dye coupling developer and which constitute not more than 1 wt.% relative to the dye coupling develo per.