Patent ID: 6245479
Filing Date: 2001-06-12
Classification: B41M,Y10S,Y10T

Abstract:
A thermal imaging medium for forming images in response to intense image-forming radiation, comprising:a web material, said web material being a self-supporting sheet of thermoplastic material having a thickness from about 1 to about 1000 micrometers and provided with a subcoat of one of the group of polystyrene and a copolymer of styrene and acrylonitrile, said web material being transparent to said radiation and said subcoat providing an image-forming surface at least a surface zone of which comprises a polymeric material liquefiable and solidifiable in a short time; said surface zone being liquefiable and flowable at a predetermined elevated temperature range, upon subjection of said thermal imaging medium to brief and intense radiation, and being thereafter rapidly solidifiable upon cooling, said surface zone, when subjected to temperatures of about 400.degree. C., exhibiting a catastrophic drop in viscosity of from about 10.sup.13 Pa.s to about 0.001 Pa.s;a layer of porous or particulate image-forming substance uniformly coated and initially adhered to said web material sufficiently to prevent accidental dislocation; said layer having a cohesive strength greater than the adhesive strength between said layer and said web material;said thermal imaging medium being capable of absorbing radiation rapidly at or near the interface of said image-forming surface and said layer of porous or particulate image-forming substance and being capable of converting absorbed energy into thermal energy of sufficient intensity to liquefy said surface zone of said image-forming surface at said predetermined elevated temperature range;said surface zone, when liquefied, exhibiting capillary flow and penetrating into adjacent portions of said image-forming substance, said liquefied surface zone solidifying upon rapid cooling, thereby substantially locking said layer of image-forming substance to said web material.