Hydroxydiphenyl sulfone derivative and heat-sensitive recording material using the derivative

Abstract From the Canadian patent

A hydroxydiphenyl sulfone derivative represented by the formula I is a novel compound and a heat sensitive recording material which comprises at least one of the derivatives as a color acceptor not only has an excellent recording sensitivity, resistances to plasticizer and diazo developer but also suits to high - speed recording, has an excellent storage stability of record images and does not decrease in whiteness of the background, wherein R1 and R2 are each hydrogen halogen, lower, alkyl, lower alkoxyl or hydroxyl and n is an integer of 3 or 4.