Abstract: The present invention relates to a heat-sensitive recording sheet which comprises a support, an undercoat layer provided on said support and a heat-sensitive color forming layer provided on said undercoat layer, said heat-sensitive color fomring layer containing a colorless or palely colored dye precursor, a developer which reacts with said dye precursor upon application of heat to cause said dye precursor to form color, N-methylolbehenic acid amide, and at least one sensitivity enhancing agent. This heat-sensitive recording sheet is excellent in heat responsiveness, high in sensitivity and superior in mechanical matching properties.

Abstract: A thermosensitive recording material bearing a specific intermediate layer comprising a specific alkyl ammonium salt provides a high color density even with a low printing energy and minimized background strain. The intermediate layer is provided between a support and a thermosensitive recording layer.

Abstract: A recording material wherein a color forming system comprising (a) a fluorene compound as a dye precursor, (b) a color developer, (c) an isocyanate compound, and (d) in imido compound, gives a developed color image having an absorption at near infrared portion and excellent image storability.

Abstract: There is disclosed a good thermosensitive recording material, having excellent thermal response and having minimal adhesion to a thermal head, which comprises a support having provided thereon a thermosensitive recording layer comprising:(1) a substantially colorless dye precursor,(2) an electron donating developer capable of developing a color of the dye precursor, and,(3) as an additive, 2-benzyloxynaphthalene and p-benzylbiphenyl in a mixing ratio of 95:5 to 70:30 (by weight).

Abstract: A recording material wherein a color forming system comprising (a) a fluorene compound as a dye precursor, (b) a color developer, (c) an isocyanate compound, and (d) an imino compound, gives a developed color image having an absorption at near infrared portion and excellent image storability.

Abstract: There is provided a heat sensitive recording sheet comprising a support and a heat sensitive color forming layer excellent in mechanical adaptability and recording characteristics and capable of providing clear copies. This recording sheet has a smoothness of at least 150 seconds measured according to JIS P8119, an opaqueness of 30-50% according to JIS P8138 and a stiffness in longitudinal direction of 35 or less in Clark value according to JIS P8143 and the support is a synthetic paper.

Abstract: In a heat-sensitive recording sheet having a heat-sensitive coating layer comprising a colorless to light-colored dye precursor as color former and a color developer which causes said dye precursor to develop a color by reacting with said dye precursor when heated, the color development sensitivity of said sheet, particularly at low temperatures, is enhanced by using benzyl p-hydroxybenzoate as said color developer and allowing said heat-sensitive coating layer to further comprise a terephthalic acid ester having a melting point of 60.degree. C. or higher and a fatty acid amide or derivative thereof having a melting point of 60.degree. C. or higher.

Abstract: In a heat-sensitive recording sheet comprising (1) a substrate, (2) a heat-sensitive color-developing layer provided on said substrate, composed essentially of a colorless or light-colored dye precursor and a color developer capable of allowing said dye precursor to develop a color by reacting with the dye precursor when heated and, as necessary, (3) an overcoat layer provided on said heat-sensitive color-developing layer, improvements in printability, storability, etc. can be obtained by allowing the heat-sensitive color-developing layer and/or the overcoat layer to contain a boric acid ester.

Abstract: A thermosensitive recording paper consisting of a dye precursor and a color developer capable of coloring said dye precursor on heating, wherein one type of overcoat layer selected from the group consisting of alginates, alumina sol, colloidal silica and a mixture of alumina sol with colloidal silica is provided as the topmost layer thereof to give improved chemical resistance and good printing quality with a reduced deterioration in sensitivity and no residues and sticking.

Abstract: In a heat-sensitive recording sheet having a heat-sensitive coating layer comprising a colorless to light-colored dye precursor as color former and benzyl p-hydroxybenzoate as color developer which causes said dye precursor to develop a color by reacting with said dye precursor when heated, the color development sensitivity of said sheet particularly at low temperatures is enhanced by allowing said heat-sensitive coating layer to further comprise a terephthalic acid ester having a melting point of 60.degree. C. or higher and a wax having a melting point of 60.degree. C. or higher.

Abstract: A thermosensitive recording material of improved color generation characteristics is obtained by using as the color developer a fused mixture of a conventional color developing bisphenol compound and other phenolic compounds.

Abstract: A thermosensitive recording paper consisting of a dye precursor and a color developer capable of coloring said dye precursor on heating, wherein one type of overcoat layer selected from the group consisting of alginates, alumina sol, colloidal silica and a mixture of alumina sol with colloidal silica is provided as the topmost layer thereof to give improved chemical resistance and good printing quality with a reduced deterioration in sensitivity and no residues and sticking.

Abstract: A heat-sensitive recording composition with an improved image stability comprises 3-(N-methylcyclohexylamino)-6-methyl-7-anilinofluorane, 4,4'-isopropylidenediphenol capable of color-developing the fluorane through reaction by heating, fatty acid amide as a sensitizer and water-insoluble modified phenol resin having a softening point of 80.degree. to 190.degree. C., where at least 20% by weight of N-monosubstituted fatty acid amide is contained on the basis of total fatty acid amide, and 5 to 50% by weight of the water-insoluble, modified phenol resin is contained on the basis of the 4,4'-isopropylidenediphenol.