Abstract: The present invention provides a heat sensitive recording material comprising a substrate, a recording layer formed over the substrate and containing a colorless or light-colored basic dye and a color acceptor, and a protective layer formed over the recording layer, the recording material being characterized in that microcapsules having an ultraviolet absorber enclosed therein and having substantially no color forming ability are incorporated in the protective layer.Further, the present invention provides microcapsules having an ultraviolet absorber and as required an organic solvent enclosed therein, which have capsule wall film of synthetic resin and mean particle size of 0.1 to 3 .mu.m.

Abstract: In the heat-sensitive recording material which has on a base sheet a heat-sensitive recording layer containing a colorless or pale colored chromogenic material and a color developer forming a color by reacting with the chromogenic material and a protective layer arbitrarily formed on the recording layer, a water-soluble graft copolymer of a polymer comprising at least one ethylenically unsaturated carboxylic acid unit and silicone is comprised in the recording layer and/or the protective layer.

Abstract: The present invention provides a heat sensitive recording material comprising a recording layer formed on a substrate and containing a colorless or light-colored basic dye and a color acceptor, the material being characterized in that the basic dye is 3-diethylamino-7-[m-(trifluoromethyl)phenylamino]fluoran and/or 3-di-n-pentylamino-6-methyl-7-phenylaminofluoran, the color acceptor being 4,4'-dihydroxydiphenylsulfone.

Abstract: The present invention provides a heat sensitive recording material comprising a substrate, a recording layer formed over the substrate and containing a colorless or light-colored basic dye and a color acceptor, and a protective layer formed over the recording layer, the recording material being characterized in that microcapsules having an ultraviolet absorber enclosed therein and having substantially no color forming ability are incorporated in the protective layer.Further, the present invention provides microcapsules having an ultraviolet absorber and as required an organic solvent enclosed therein, which have capsule wall film of synthetic resin and mean particle size of 0.1 to 3 .mu.m.

Abstract: The present invention provides a heat sensitive recording material comprising a substrate and a recording layer thereon incorporating a colorless or light-colored basic dye and a color acceptor reactive with the dye to form a color when contacted therewith, the recording material being characterized in that, the basic dye comprises 1 at least one compound represented by the formula below [I] and 2 3-di-n-butylamino-6-methyl-7-anilinofluoran and/or 3-di-n-pentylamino-6-methyl-7-anilinofluoran, and the color acceptor comprises 4,4'-isopropylidenediphenol ##STR1## wherein R.sub.1, R.sub.2, a, b, c and d are as defined in the specification.

Abstract: A heat sensitive recording material comprising a substrate and a heat sensitive recording layer thereon incorporating a colorless or light-colored basic dye and a color acceptor reactive with the dye to form a color when contacted therewith, the recording material being characterized in that the material has a heat sensitive recording layer having incorporated therein (1) a heat-fusible substance exhibiting a weight reduction of at least 5% at 200.degree. C. based on the weight at 25.degree. C. under the condition of 20.degree. C./min in the rate of rise of temperature, (2) a wax, (3) a lubricant, and (4) an oil-absorbing pigment at least 85 ml/100 g in oil absorption.

Abstract: An improved heat-sensitive recording material having a substrate and a heat-sensitive recording layer formed thereon which contains a colorless or light-colored basic dye and a color developer to color said basic dye upon contact by heating, said heat-sensitive recording layer being formed by applying a coating dispersion containing prismatic calcium carbonate comprising single particles each having such a particle size that the average length is 1 to 6 .mu.m and the average breadth is 0.1 to 0.6 .mu.m. The heat-sensitive recording material does not generate any foreign matter to contaminate the recording head and it does not cause reduction in the whiteness of the recording layer with the lapse of time.