Thermochromic compsns. for thermographic recording - giving variety of colours with phenolic cpds. and chelating cpds.

摘要

Thermochromic compsns. and thermographic recording materials contg. the compsns. are claimed, the compsn. contg. at least a cpd. of formula (I) or (II): where Ri is H or electron repelling gps. in positions 5,6,7 and 8 in (I); R'i is H or electron repelling or attracting gps. in positions 4', 5', 6' and 7' and 4", 5", 6" and 7", formulae (I) and (II) and Rj is H or electron repelling gps. in positions 5,6,7,8,9 and 10 in (II). (I) and (II) (both known cpds.) produce a colour change when heated at >180 degrees C, and, when used with a reactant, give a sharper colour change at a lower temp. than when either (I) or (II) is used alone. Use of a reactant also gives colours different to that given by (I) or (II) alone. Colour obtd. varies from chestnut violet-red to pink.