Color-developing compositions and their use

摘要

A color-developing composition comprises a multi-valent-metal-modified salicylic acid resin (Resin A) and a polycondensation resin (resin B) at a weight ratio of 90-30 to 10-70. Resin A is composed of 5-35 mole % of a structural unit (I) and 65-95 mole % of at least one structural unit (II) or 65-95 mole % of a coupled structural unit of at least one unit (II) and at least one unit (III) and has a weight-average molecular weight of 350-5,000. Resin B is composed of the unit (II) and/or the unit (III) and has a weight-average molecular weight of 350-5,000. <IMAGE> (I) <IMAGE> (II) <IMAGE> <IMAGE> (III) <IMAGE> wherein Z represents M/m, M being a metal ion of m valence and m being an integer; R1 and R2 represent H or a C1-12 alkyl, aralkyl, aryl or cycloalkyl group; R3 and R6 represent H or a C1-4 alkyl group; and R4 and R5 represent H or CH3.