Abstract
We have designed and synthesized diphenylether diazonium salts as red color formers for a black-red dual color direct thermal recording system. The diphenylether diazonium salts obtained form red color via a coupling reaction with Naphthol-AS or yellow color via a coupling reaction with Naphthol-ASI4G. The color forming abilities of papers coated with the mixture of coupler, organic base, thermo-sensitizer and microcapsule incorporating the derivatives were examined. The derivative having normal butyl chain could be encapsulated in high amounts and formed vivid red color. Combined with another black color-forming diazonium salt, black-red dual color direct thermal recording was achieved.
