Reversible thermographic medium used on sleeve of diskette or record or label of magnetic tape cassette for showing (part of) the stored information has limited retarded initial transparency temperature

摘要

In a reversible thermographic medium with a substrate and heat-sensitive layer that undergoes a reversible change in transparency or color with temperature, the novelty is that the change in the retarded initial transparency temperature is /} 5 deg C. Independent claims are also included for: (a) a reversible thermographic medium with a substrate and heat-sensitive layer that undergoes a reversible change in transparency or color with temperature, which consists of an organic material of low molecular weight dispersed in a matrix resin, in which the matrix resin is a crosslinked mixture of a thermoplastic resin containing hydroxyl groups, a linear isocyanate and a cyclic isocyanate; (b) a similar medium, in which the matrix is a crosslinked urethane resin based on polycarbonate; (c) a process for writing and erasing an image in such a medium by heating.