Conventionally, a thermosensitive sublimation type transfer system and a thermosensitive melting type transfer system have been widely used among various thermal transfer recording systems. Among them, the thermosensitive sublimation type transfer system is a system in which a sublimation dye is used as a color material, and the dye in a sublimation dye layer formed on a thermal transfer ink sheet is transferred to a thermal transfer image-receiving sheet using a heating device such as a thermal head of which the heat generation is controlled depending on image information, thereby forming an image.
According to the thermosensitive sublimation type transfer system, the amount of transferred dye can be controlled in dot units by heating in a very short time. Because the color material is a dye, transparency is excellent, and a formed image is very clear and is excellent in halftone reproducibility and tone. Therefore, a very-high-definition image is obtained, and a high-quality image equivalent to full-color silver halide photography can be obtained.
As a thermal transfer image-receiving sheet for sublimation transfer (hereinafter referred to as thermal transfer image-receiving sheet) used in such a thermosensitive sublimation type transfer system, a thermal transfer image-receiving sheet in which a color material-receiving layer is formed on a substrate layer is commonly used. Not only high printing sensitivity but also stability against the curl of the image-receiving sheet in itself (curl resistance) is significant as performance demanded for the image-receiving sheet. Therefore, particularly in the case of producing an image-receiving sheet in sheet form, a method of preventing curl using the image-receiving sheet in which plastic sheets and the like are further symmetrically layered on both sides of a support such as a plastic sheet or paper, a method of disposing a curl prevention layer formed of resin or the like on the back side or the like of the image-receiving sheet to keep stability against curl, and the like have been adopted. As such a curl prevention measure, for example, disposition of a back side resin layer on the back side of the support of a thermal transfer image-receiving sheet has been proposed (see Patent Literature 1).