GB395864A - The production of multi-coloured artificial cellulosic materials in the form of sheets, bands or films - Google Patents

Abstract

Multi-coloured sheets, bands, or films are obtained by heterogeneous colouration of aqueous cellulosic solutions followed by regeneration or coagulation in known manner. The film-forming solution may be viscose, or a solution of cellulose in cuprammonium, thiocyanate, or zinc chloride solution. The films may be transparent or if fillers such as kaolin, blanc fixe, or metallic powders are incorporated in the solutions, they may be translucent or opaque. The cellulose solution may be divided into a number of equal or unequal portions which are separately dyed or coloured and then associated together to any desired degree of partial blending followed by regeneration. If desired one or more coloured cellulosic solutions may be associated with an uncoloured cellulosic solution. In an example, a number of portions of a viscose solution are separately impregnated uniformly with colour and fed independently to an extruding or pouring device at a number of positions throughout its length in such manner that a degree of diffusion of the variously coloured portions of viscose takes place therein. The solution is extruded in the form of a heterogeneously coloured sheet into a regenerating or coagulating bath. In another example, a colourless or uniformly coloured viscose solution is heterogeneously coloured in the extruding device by means of dyes, either as such or in the form of solutions, which are fed at various positions immediately prior to the passage of the viscose through the shaped aperture. Dyestuffs which may be used are benzo-direct dyes, vat dyes such as indanthrene, pigment dyes, acid dyes such as tartrazine and disulphine naphthalene, chlorazol, thional, and water soluble anthraquinone dyes. In cases where the dyestuff is discoloured by the cellulosic solution such as viscose, or by the mineral acids or other substances employed in the regenerating baths, the colour may be restored by treatment with a neutralizing or oxidizing bath.