2012 Volume 51 Issue 2 Pages 139-146
Thermal paper is a functional paper, which can develop color images by thermal reaction of dye and developer. One major problem of the thermal paper is that when exposed to UV light, photodecomposition of leuco dye proceeds and yellowish coloration and image fading occurs. In order to improve its durability against light (lightfastness), novel cinnamic amide derivatives which posses' UV-absorbent ability was employed as a developer. By using the selected derivatives, we succeeded to realize a thermal paper that exhibits excellent lightfastness in both background and image. To afford lightfastness by using cinnamic amide derivatives, the developer's photostability is also needed. And by crystal structure analyses, the derivative showing low photostability proceeds solid state [2+2] photodimerization by UV irradiation, which decreases UV absorbing ability of the compound.