| abstract |
PURPOSE:To enhance preservation stability, particularly, resistance to plasticizers, oils, alcohols, acids, alkalis, water and abrasion, by providing a protective layer comprising a polyester resin and/or a polyurethane resin on a thermal color forming layer. CONSTITUTION:A polyester resin or polyurethane resin in which functional groups are introduced to side chains and/or a main chain while retaining chemical resistance is used. Particularly, such a resin having at least one functional group selected from carboxyl, sulfonic acid group, sulfonate group, hydroxyl, epoxy, unsaturated group and amino, is preferable. By this, affinity of a pigment or the like in the protective layer for other components is increased, accompanied by marked enhancement of binding forces in the layer and interlaminar strength. Where a hydrophilic functional group is introduced, the resin can be used in the form of an aqueous solution or emulsion. If required, a protective layer comprising a cross-linking agent in addition to the above components is provided, and a protective layer comprising a cold curable type silicone is provided thereon as required. |