GB1354165A - Process for marking gelatine layers - Google Patents

Abstract

1354165 Marking gelatine layers with ink containing a hydroxyalkylformamide AGFAGEVAERT AG 8 July 1971 [11 July 1970] 32089/71 Heading G2X [Also in Division C4] Gelatine layers are marked by applying thereto an ink mixture comprising a hydrophilic dye which does not diffuse in gelatine, dissolved in a solvent comprising at least one hydroxyalkyl formamide wherein R 1 is a straight or branched chain C 1 -C 6 alkylene radical, and R 2 is H, a straight or branched chain C 1 -C 4 alkyl, a straight or branched chain C 1 -C 6 hydroxyalkyl, or a straight or branched chain C 1 -C 6 formylaminoalkyl radical. When applied to gelatine layers of photographic materials the ink produces a mark which is resistant to various photographic baths. The dye is particularly an azo dye which may be used for the silver dye bleaching process, preferably a polymer dye obtained by diazotization of amino-hydroxynaphthalene sulphonic acids followed by self-coupling in an alkaline medium. The mark may be applied by a felt tip pen, rubber stamp, typing ribbon or printing cloth. The formamide solvent is removed from the gelatine in the aqueous photographic baths, thus securing the dye to the gelatine layer. The process may be used to mark the upper surface of a photographic material, but more preferably a rear gelatine surface, particularly a layer containing 3-18 per cent by wt. of cellulose triacetate and 1-6 per cent wool fat, based on the dry weight of gelatine. In addition the layer may contain barium sulphate, strontium sulphate, silica or starch matting agents. In Examples a typing ribbon is used to apply the mark.