THERMOCHROMIC MATERIAL CONTAINING AN ELECTRON-DONATING COLOUR FORMER

摘要

1531121 Indicating temperature FUJI PHOTO FILM CO Ltd 29 April 1977 [19 May 1976] 18119/77 Heading G1D A thermochromic material comprises a mixture of an oxybenzoic acid ester of general formula HO-Ar-COOR (where Ar is an aromatic nucleus and R is an organic group with 1-13 C atoms) and an electron-donating colour former which reacts with an electron-accepting acid to form a colour. Many examples of colour formers and esters are given. The colour reversion after a temperature has returned to its original value may take several days. The mixture may be rendered electrically conductive (to detect Joule heating) by the inclusion of metal powders or salts.