GB1330537A - Vesicular copying process - Google Patents

Abstract

1330537 Vesicular processes and stripping materials therefor PITNEY-BOWES Inc 20 Sep 1970 35103/70 Heading G2C A vesicular process comprises reflex exposing a vesicular material comprising a lighttransmissive support coated with a layer of a binder in which is uniformly dispersed a diazonium compound through the support to an original which is more reflective in the non- image areas using radiation which excludes the absorption maxima of the diazonium compound thus generating more gas in the areas corresponding to the non-image areas. This image may be developed by heating and fixed by a uniform low intensity exposure. A reversed image may be obtained by increasing the intensity of the imagewise exposure. The diazonium layer may contain a coupler so that a dye image in the area corresponding to the image areas is formed by applying ammonia or heat if a heat-sensitive alkali-generator is present in either the diazonium or adjacent layer. The vesicular image may then be removed by treatment with water vapour. The dye image may be transferred to a receptor sheet using heat and pressure if a stripping layer is applied between the diazonium layer and the support or, if adhesion is weak between the support and diazonium layer, no stripping layer is necessary. The transfer may be assisted by applying an adhesive layer to the diazonium layer before transfer. Alternatively, the dye image may be produced during transfer if the receptor sheet contains an alkali-generator. The specified stripping layer is a copolymer of maleic anhydride and methyl vinyl ether. The binder for the vesicular layer may be methyl cellulose, polyvinyl pyrrolidone or a copolymer of maleic anhydride and methyl vinyl ether. The vesicular layer may also contain silica, urea (as alkali-generator), or a combination of couplers to produce a black image. Correct exposure is obtained by exposing through filters which cut out the peak wavelength(s) of the diazonium compound. A coloured image on projection may be produced if the exposure is such to produce vesicules over the entire material but with more opaque vesicles (by transmitted light) in the areas corresponding to the image areas of the original. These opaque vesicles may be removed by steam treatment which also renders the vesicles in the non-image areas more opaque to transmitted light. A polystyrene layer may be applied over the light-sensitive layer to prevent adhesion with the original.