Heat-sensitive chromogenic system

摘要

A document capable of providing information under the application of heat, which comprises a first support having a first surface and a second surface, the first surface bearing an information area including a visible principal image, and at least one of said first support or second support bearing at least one localized coating comprising a substantially colorless, non-pressure sensitive, heat-activatable chromogenic composition capable of producing a first color under the application of heat, the chromogenic composition comprising a chromogenic compound and a color developer. The chromogenic compound and the color developer are substantially colorless solids in physical contact prior to reaction, but which can chemically react to produce a visible colored image by application of heat at temperatures above room temperature. The information area is substantially free of chromogenic compounds, and free of color developers capable of reacting with chromogenic compounds to produce a visible colored image by application of heat.