| 摘要 |
PURPOSE: To obtain a visually readable recording card excellent in durability and deterioration resistance by employing an oxide glass of TeO2 -PbO-Tl2 in a thermal display layer. CONSTITUTION: A thermal display layer 2 on the surface of a substrate 1 is composed of an oxide glass having composition within a range defined by lines connecting point A (TeO2 : 85%, Tl2 O: 15%), point B (TeO2 : 80%, PbO: 20%), point C (TeO2 : 40%, PbO: 60%), point D (PbO: 50%, Tl2 O: 50%), point E (Tl2 O: 70%, PbO: 30%), and point F (Tl2 O: 70%, TeO2 : 30%) on the three element phase diagram of TeO2 -PbO-Tl2 . The oxide glass is a hard and safety material causing no oxidation discoloring with water or sweat. It is also excellent in water resistance and crystallized through heating at a relatively low temperature for a short time to change the color tone, transparency, reflectance, or the like, thus presenting an indication. |
