| abstract |
PROBLEM TO BE SOLVED: To provide a thermosensitive recording developer composition having high sensitivity, little background fogging, and excellent storage stability of a recorded image, particularly, excellent moisture resistance, heat resistance and plasticizer resistance. It is in. SOLUTION: The heat developer comprises a mixture of at least one selected from a sulfonyl compound represented by the formula (1) or a polyvalent metal salt thereof and at least one selected from a sulfonyl compound represented by the formula (3). A developer composition for recording materials. Embedded image (Where X is a hydrogen atom, an alkyl group, R 1 to R 3 are a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, a cycloalkyl group, R 4 to R 6 , R 8 to R 10 are a hydrogen atom, a halogen Atom, alkyl group, cycloalkyl group, R 7 is a hydrogen atom, and represents formula (2)) |