GB402737A - Manufacture of negative copies - Google Patents

Abstract

402,737. Negative copies. KALLE & CO. AKT.-GES., 23, Rheinstrasse, Biebrich, Wiesbaden, Germany. March 4, 1932, No. 6572. Void [Abridged as open to inspection under Sect. 91 of the Acts, March 5, 1932]. [Class 98 (ii).] Negative copies are prepared by exposing to light under a pattern a colloidal base to which light-sensitive substances have been added which develop gas on exposure to light and, if required, after-treating it in order to effect a loosening of the colloid particles in the places which have been exposed to light. The gas is set free in the exposed places and inflates the colloidal material to a greater or less extent, whilst simultaneously dulling it. A negative picture of the pattern is thus obtained. In order to fix the picture the undecomposed light-sensitive compound may be washed out or the picture further cautiously exposed to diffused light. The inflation of the colloid also produces a relief effect. Colloidal bases suitable are layers of regenerated cellulose, gelatine, glue, gum either alone or on a support. Light sensitive substances suitable are diazo compounds, aromatic azides, and superoxides. In examples (1) a regenerated cellulose hydrate foil is impregnated with p-aminomonoethyl-otoluidine diazonium borofluoride, glycerine and tartaric acid, dried and exposed under a pattern ; a strong dulling effect is obtained at the exposed places and after removal of the pattern the foil is exposed to diffused daylight, (2) a gelatinised cellulose ester foil is impregnated with 2-diazo-1-naphthol-4-sulphonic acid, exposed as in (1) and washed with water or aqueous alcohol ; by treating the layers with alkali before or after exposure dyestuffs are formed by the coupling of the unchanged diazo compound in which case an acid after-treatment is necessary, (3) a glass plate is coated with a gelatine emulsion containing sodium 2:1: 6-diazonaphtholsulphonate, resorcin, acetic acid and gelatine, dried, exposed as in (1), treated in a current of steam and finally in an atmosphere of ammonia, (4) a glass plate or a lacquered metal plate is covered with an emulsion containing 1 : 2 : 4-diazonaphtholsulphonic acid, sodium acetate and gelatine, dried, exposed under a pattern, and exposed to moist air or washed with alcohol, (5) a nitro-cellulose film is coated with an emulsion containing sodium azidosalicylate and chrome-alum, dried, exposed as above, and steamed.