Kanzaki Paper Manufacturing Co., Ltd.

Sanko Kaihatsu Kagaku Kenkyusho

Toshio Kimura

Toranosuke Saito

Takashi Ishibashi

Masato Tanaka

Eiji Kawabata

Yoshihiro Shimizu

Tooru Yamamoto

Herein disclosed is a method for preparing a nuclear-substituted salicylic acid or a metal salt thereof represented by the following general formula (1): ##STR1## [wherein R.sub.1 and R.sub.2 each represents a t-butyl group, a t-amyl group, a t-octyl group, an isononyl group or an isododecyl group, provided that at least one of R.sub.1 and R.sub.2 represents an isononyl group or an isododecyl group; M represents a hydrogen atom or a metal atom; and n is the atomic valency of the metal atom M] which comprises the step of subjecting, to a Kolbe-Schmitt reaction, an alkali metal salt of a nuclear-substituted phenol represented by the following general formula (2): ##STR2## [wherein R.sub.1 and R.sub.2 are the same as those defined above] in which 100 to 50% of the alkali metal salt is potassium salt and 0 to 50% thereof is sodium salt, in a substantially water-insoluble solvent as a reaction medium. The method makes it possible to improve the yield of the specific nuclear-substituted salicylic acid and metal salts thereof and to provide such products having high purity without any post-treatment. The compounds can be used in color developers for pressure-sensitive recording sheets without any additional purification treatment.

Color developer for pressure-sensitive recording sheets

A heat-sensitive recording material comprising a substrate, an intermediate layer disposed on said substrate and a heat sensitive recording layer disposed on said intermediate layer, characterized in that said intermediate layer contains a pigment of 80 cc/100 g or more in oil absorption as the main constituent and an alkaline pigment of 8 or more in PH value in an amount of 0.1 to 25% by weight on the total amount of the pigments contained in said intermediate layer.

Heat-sensitive recording material

Growing community of inventors

Hyogo, Japan

Toshio Kimura