Patent ID: 8420568

Claim:
A color-developing composition which is a reaction composition containing a mixture of compounds represented by formula (III) (wherein R, Y and m have the same meaning as defined below and n represents an integer of 1 to 6) that are obtained by reacting a dihydroxydiphenylsulfone derivative represented by formula (I) (wherein each R independently represents a halogen atom, C1-C6 alkyl group or C2-C6 alkenyl group, and m represents an integer of 0 to 4) with a dihalide represented by formula (II) X—Y—X (II) {wherein X represents a halogen atom, Y either represents a linear, branched or cyclic C1-C12 hydrocarbon group which may have an ether bond or represents the following formula (wherein R′ represents a methylene group or ethylene group, and T represents a hydrogen atom or C1-C4 alkyl group)}, wherein the content of a n=1 compound in the reaction composition is 5-80% by mass relative to the solid content in the whole composition and wherein 10% by mass or more of the n=1 compound is a crystalline material.