There is disclosed a heat-sensitive recording material including an undercoat layer formed on one surface of a support and a heat-sensitive recording layer formed on the undercoat layer. The heat-sensitive recording layer contains a leuco dye and a coloring agent. The undercoat layer contains hollow particles and a binding resin. A maximum particle diameter (D100) of the hollow particles is 10 to 30 μm. A particle diameter (D50) of the hollow particles at cumulative 50 volume % is 4.0 to 15 μm. A ratio D100/D50 of the maximum particle diameter (D100) of the hollow particles to the particle diameter (D50) of the hollow particles at cumulative 50 volume % is 1.8 to 3.0. A volume percentage of the hollow particles having particle diameters of 2.0 μm or less is 1% or less.

There is disclosed a heat-sensitive recording material including an undercoat layer formed on one surface of a support and a heat-sensitive recording layer formed on the undercoat layer. The heat-sensitive recording layer contains a leuco dye and a coloring agent. The undercoat layer contains hollow particles and a binding resin. A maximum particle diameter (D100) of the hollow particles is 10 to 30 μm. A particle diameter (D50) of the hollow particles at cumulative 50 volume % is 4.0 to 15 μm. A ratio D100/D50 of the maximum particle diameter (D100) of the hollow particles to the particle diameter (D50) of the hollow particles at cumulative 50 volume % is 1.8 to 3.0. A volume percentage of the hollow particles having particle diameters of 2.0 μm or less is 1% or less.

A thermal transfer sheet is used in indirect transfer printing for forming an image through a primary transfer from the thermal transfer sheet to an intermediate transfer medium and thereafter forming an image on a transfer target through secondary transfer to the transfer target. The thermal transfer sheet includes, on a substrate, a masking layer that is a portion that prevents transfer to the transfer target during the secondary transfer. The masking layer is formed from a resin having a Tg of 140° C. or more and 220° C. or less, and the masking layer contains 0.5 wt % or more and 20 wt % or less filler particles relative to the resin.

A thermal transfer sheet is used in indirect transfer printing for forming an image through a primary transfer from the thermal transfer sheet to an intermediate transfer medium and thereafter forming an image on a transfer target through secondary transfer to the transfer target. The thermal transfer sheet includes, on a substrate, a masking layer that is a portion that prevents transfer to the transfer target during the secondary transfer. The masking layer is formed from a resin having a Tg of 140° C. or more and 220° C. or less, and the masking layer contains 0.5 wt % or more and 20 wt % or less filler particles relative to the resin.

A thermosensitive recording medium includes a base material; a thermosensitive recording layer; and an under layer disposed between the base material and the thermosensitive recording layer and containing a non-thermally-expandable hollow filler. The thermosensitive recording medium includes a hydrocarbon, where an amount of the hydrocarbon having from 3 through 16 carbon atoms is 0.2 mg/m.sup.2 or more, relative to an area of the thermosensitive recording medium.

A thermosensitive recording medium includes a base material; a thermosensitive recording layer; and an under layer disposed between the base material and the thermosensitive recording layer and containing a non-thermally-expandable hollow filler. The thermosensitive recording medium includes a hydrocarbon, where an amount of the hydrocarbon having from 3 through 16 carbon atoms is 0.2 mg/m.sup.2 or more, relative to an area of the thermosensitive recording medium.

Provided is a thermal transfer sheet that can form a good image on both a transfer object made of a polyethylene terephthalate and a transfer object made of a polypropylene, as well as can form an image with high alcohol resistance. The thermal transfer sheet of the present invention includes a substrate, and a transfer layer including a colored layer and an adhesive layer, in which the adhesive layer has a phase-separated structure formed by a polyester and a polyolefin that are incompatible with each other, and in which the percentage of the region formed by one of the polyester and the polyolefin to the total area (100%) of the adhesive layer is 55% or more and 85% or less.

Provided is a thermal transfer sheet that can form a good image on both a transfer object made of a polyethylene terephthalate and a transfer object made of a polypropylene, as well as can form an image with high alcohol resistance. The thermal transfer sheet of the present invention includes a substrate, and a transfer layer including a colored layer and an adhesive layer, in which the adhesive layer has a phase-separated structure formed by a polyester and a polyolefin that are incompatible with each other, and in which the percentage of the region formed by one of the polyester and the polyolefin to the total area (100%) of the adhesive layer is 55% or more and 85% or less.

Provided is a thermal transfer sheet enabling printing suitability on high temperature printing to be good. A thermal transfer sheet 100 in which either one or both of a colorant layer 3 and a transfer layer 10 are provided on one face of a substrate 1, and a back face layer 20 is provided on the other face of the substrate 1, wherein a back face primer layer 25 is provided between the substrate 1 and the back face layer 20, and the back face primer layer 25 contains at least one component selected from a silicone resin, a siloxane cross-linked resin, and a silica-introduced resin.

Provided is a thermal transfer sheet with low hot and cold peeling strengths. Thermal transfer sheet according to the present disclosure includes a substrate and a transfer layer, wherein the transfer layer includes at least a peeling layer, and the peeling layer contains a vinyl resin and at least one of an alcohol alkoxylate and an alcohol having 18 to 80 carbon atoms.