Heat-sensitive recording material

Claim 1

A heat-sensitive recording material incorporating a colorless or pale-colored basic dye and a color acceptor which is reactive with the dye to form a color when contacted therewith, characterized in that (a) as the basic dye are used 100 parts by weight of a phthalide derivative of the formula [ I ] and 20 to 100 parts by weight of a black color-­forming fluoran derivative of the formula [ II ], (b) as the color acceptor is used a polyvalent metal salt of an aromatic carboxylic acid and (c) a recording sensitizer is further used, and whereby the resulting record images are at least 0.75 in PCS value at 800nm : wherein R₁ to R₄ are each hydrogen atom ; C 1∼8 alkyl ; C 5∼8 cycloalkyl ; C 3∼8 alkoxyalkyl ; C 3∼9 unsaturated alkyl ; tetrahydrofurfuryl ; tetrahydropyran-2-methyl ; C₇∼₁₀ aralkyl unsubstituted or substituted with halogen atom, C 1∼4 alkyl or C 1∼4 alkoxyl ; phenyl unsubstituted or substituted with halogen atom, C 1∼4 alkyl or C 1∼4 alkoxyl ; C 2∼8 alkyl having phenoxy unsubstituted or substituted with halogen atom, C 1∼4 alkyl or C 1∼4 alkoxyl ; or halogenated C 1∼8 alkyl; R₁ and R₂, and/ or R₃ and R₄ may form a heteroring selected from the group consisting of pyrrolidine, piperidine, hexa­methyleneimine, morpholine, julolidine and tetrahydroquinoline together therewith or with an adjacent benzene ring, a, b, c and d represent carbon atoms and one or two of them may be nitrogen atom, the carbon atom may have a substituent selected from the group consisting of hydrogen atom ; halogen atom ; C₁∼₄ alkyl ; C₁∼₄ alkoxyl ; -N(R₅)(R₆), R₅ and R₆ are same as R₁ to R₄ ; and nitro, one of a-b, b-c and c-d bond may form an another benzene ring together with the substituent ; wherein R₇ and R₈ are each C₁∼₈ alkyl unsubstituted or substituted with halogen atom or C₁∼₄ alkoxyl ; unsaturated C₃∼₉ alkyl ; C₅∼₁₂ alicyclic group ; phenyl unsubstituted or substituted with halogen atom, C₁∼₄ alkyl or C₁∼₄ alkoxyl ; benzyl unsubstituted or substituted with halogen atom, C₁∼₄ alkyl or C₁∼₄ alkoxyl ; or tetrahydrofurfuryl, R₇ and R₈ may form a ring selected from the group consisting of pyrrolidine, piperidine, hexamethyleneimine and morpholine together therewith, R₉ and R₁₀ are each hydrogen atom ; halogen atom ; C₁∼₄ alkyl ; or C₁∼₄ alkoxyl, P is hydrogen atom ; halogen atom ; C₁∼₄ alkyl ; C₅∼₆ alicyclic group ; halogenated C₁∼₄ alkyl ; phenyl ; benzyl ; C₁∼₄ alkoxyl ; (C₁∼₄ alkoxy)carbonyl ; or di(C₁∼₄ alkyl)amino, X is hydrogen atom ; halogen atom ; or C₁∼₄ alkyl, n is an integer of 1 to 4.