Abstract: light-sensitive vesicular imaging materials, suitable for the production of labels, etc., comprise a light-sensitive vesicular imaging layer applied to one surface of a self-supporting plastics sheet or film preferably a polyester film, e.g., an oriented and heat-set film of polyethylene terephthalate, said light-sensitive vesicular imaging layer comprising a polymeric vehicle having uniformly dispersed therein a sensitizing agent which releases a vesicle-forming gas upon exposure to light and may comprise a nitrogent-liberating diazonium salt, said polymeric vehicle comprising a thermoplastic polymer having a nitrogent permeability constant (as defined in the specification) in the range 1 .times. 10.sup.-15 to 1 .times. 10.sup.-10 and being softenable upon heating above ambient temperature to permit the gas released by the sensitizing agent in the light-struck areas to form light-scattering or reflecting vesicles therein, e.g.

Abstract: light-sensitive vesicular imaging materials, suitable for the production of labels, etc., comprise a light-sensitive vesicular imaging layer applied to one surface of an opaque self-supporting plastics sheet or film, preferably a polyester film, e.g., an oriented and heat-set film of polyethylene terephthalate, said light-sensitive vesicular imaging layer comprising a polymeric vehicle having uniformly dispersed therein a sensitizing agent which releases a vesicle-forming gas upon exposure to light and may comprise a nitrogen-liberating diazonium salt, said polymeric vehicle comprising a thermoplastic polymer having a nitrogent permeability constant (as defined in the specification) in the range of 1 .times. 10.sup.-15 to 1 .times. 10.sup.-10 and being softenable upon heading above ambient temperature to permit the gas released by the sensitizing agent in the light-struck areas to form light scattering or reflecting vesicles therein, and an adhesive layer applied to the other surface of the sheet or film.