PROCESSES FOR IMPROVING THE SECURITY OF IMPACT IMAGES

摘要

Method for preventing or reducing the likelihood of successful alteration of information printed on a document, wherein a detectable substance is released from ruptured microcapsules onto the document in image areas. The substance penetrates through the document to form a confirming image on the reverse surface. Another detectable substance of lesser penetrating ability simultaneously may be released onto the document in the image areas. Spreading of the first substance outside the boundaries of the image area created by the second substance may produce a halo effect around the image area. Documents as treated by the methods are disclosed, as well as articles comprising a document to be treated in contact with a sheet coated with the detectable substance. The first substance is microencapsulated, the second substance may or may not be microencapsulated.