GB1023494A - Thermographic copying process - Google Patents

Abstract

1,023,494. Thermographic transfer materials. KALLE A. G. March 7, 1963 [March 14, 1962], No. 9165/63. Heading G2C. A thermographic transfer sheet comprises a support coated with a sublimable dye as the sole heat-sensitive constituent in a layer less than one micron thick. This sheet is contacted with a recepter sheet and an original so that on exposure to radiant heat, the dye transfers imagewise to the receptor sheet. The dye preferably sublimes between 100 and 120‹C. and may be a stilbene, pyrazolone,triphenyl methane, diphenyl naphthyl methane, azo and oxazine dyes and indamises. Copies may be made from one-or two solid originals by reflex exposure. The image on the receptor sheet may be transferred to a further sheet by heating. Negative images may be reproduced on the receptor sheet by placing between the original and the transfer sheet a sheet of thermally insulating material which transmits infra-red radiation and putting an infra-red obsorbtive pigment in the transfer sheet so that on exposing the back of the original to infra-red radiation the radiant heat is transmitted through the thermally insulating sheet in the non-image areas only and is absorbed by the pigment in the transfer sheet causing the dye to sublime onto the recepter sheet in the non-image areas.