Fixable thermosensitive recording sheet

Claim 1

A fixable thermosensitive recording sheet consisting of a substrate, a photo- and thermo-sensitive layer composed of an acid stabilized diazonium salt capable of forming a dye by reacting with a coupler compound, and a heat-softening binder material, said layer being formed on said substrate, and a developer layer composed of a heat-softening binder material and a particulate dispersion of a heat-fusible developer capable of supplying a necessary amount of base for allowing said acid stabilized diazonium salt to react sufficiently with the coupler compound, said developer layer being formed on said photo- and thermo-sensitive layer, wherein the coupler compound is contained in at least one of said two layers and the heat-fusible developer is a hydrophobic guanidine derivative represented by the general formula: ##STR4## wherein one or both of R 1 and R 2 is/are selected from the group consisting of alkyl, cycloalkyl, aryl and aralkyl groups, and when only one of R 1 and R 2 is selected from said groups, the remaining R 1 or R 2 is hydrogen; one or both of R 3 and R 4 is/are selected from the group consisting of alkyl, cycloalkyl, aryl and aralkyl groups, and when only one of R 3 and R 4 is selected from said groups, the remaining R 3 or R 4 is hydrogen; and R 5 is selected from the group consisting of alkyl, cycloalkyl, aryl and aralkyl groups, wherein said cycloalkyl group may have a halogen substituent and said aryl group may have a substituent selected from the group consisting of alkyl, alkoxy, nitro and halogen.