Means of a safe against falsification by chemical agent, a security paper containing such a means, and document security comprising said paper security

摘要

The paper contains a nonfluorescent chemical unforging means which reacts to a redox pair. The paper according to the invention contains iron(III) and a product which gives a coloured complex with iron(II). The attempt at chemical unforging results in the reduction of the iron(III) to iron(II) immediately followed by the formation of the coloured complex. According to the invention the complexing agent is preferably 2,2'-bipyridyl. Another complexing agent is ortho-phenanthroline.