GB573236A - Improvements in or relating to the production of sheet wrapping materials - Google Patents

Abstract

Sheet wrapping material, capable of affording substantially complete absorption of ultraviolet rays in the region close to the visible rays of light is obtained by incorporating, in a state of fine division, a salt of bis(p-amino benzoyl)-4 : 41-diamino stilbene-2 : 21-disulphonic acid, into a flexible regenerated cellulose sheet or film. Preferably, the di-sodium salt of the stilbene derivative is used. It may be incorporated by dispersion in the sheet or film or by dispersion in a surface coating applied to the regenerated cellulose sheet or film as base, or by dispersion in an anchoring layer between the regenerated cellulose sheet or film as base and a surface coating. The regenerated cellulose sheet may contain a softener such as glycerine. It may be clear and substantially colourless or it may be pigmented or dyed. The sodium salt of the stilbene derivative imparts a slight tinge of yellow, but shows a bluish fluorescence in daylight. The sheet or film may be impregnated while in the gel state, or after the first drying, with an aqueous solution containing 0.1-1.0 per cent of the salt of the stilbene derivative. The salt may be incorporated in a liquid coating composition, e.g. a moisture-proofing surface coating composition comprising a film-forming substance and an organic solvent, and the composition may then be applied to the regenerated cellulose film and dried. The solid salt may be dispersed in the coating composition, or an aqueous solution of the salt may be stirred into the coating composition. The sheet material may be used for wrapping or packaging oils, fats, foodstuffs, dyed fabrics, or other articles which are deleteriously affected by ultra-violet rays. In an example, a continuous film of regenerated cellulose produced from viscose is impregnated while in the gel condition with an aqueous solution containing glycerine and bis-(p-amino-benzoyl)-4 : 41-diamino stilbene di-sodium sulphonate, and is then dried. It may be waterproofed by coating with a composition comprising cellulose nitrate, ester gum, dibutyl phthalate, and paraffin wax. In another example, the impregnating solution contains a little urea-formaldehyde syrup and ammonium chloride as well as glycerine and the salt of the stilbene derivative. In another example, a regenerated cellulose film is coated with a moisture-proofing composition containing cellulose nitrate, gum dammar, bis-(p-amino - benzoyl) - 4 : 41 - diamino - stilbene di - sodium sulphonate, paraffin wax, tricresyl phosphate, ethyl acetate, toluene, ethyl alcohol, and butyl acetate. Specifications 211,446, [Class 2 (ii)], 436,891 and 574,425 are referred to.ALSO:Sheet wrapping material which absorbs ultra violet rays in the p region close to the visible rays and is useful in preventing the development of rancidity in fatty foods is obtained by incorporating a salt of bis-(p-amino benzoyl)-4:41-diamino stilbene-2:21-disulphonic acid into a flexible regenerated cellulose sheet or film. Preferably the di-sodium salt is used. It may be incorporated in the film itself or in a surface coating, or in an anchoring layer between the base sheet and a surface coating. The sheet may contain softeners, dyes, or pigments. The sodium salt of the stilbene derivative imparts a slight tinge of yellow but gives a blue fluorescence in daylight. The salt may be incorporated in a moisture-proofing surface coating composition. In an example a regenerated cellulose film is impregnated with an aqueous solution containing glycerine and the sodium salt of the stilbene compound and then dried. It may be waterproofed by coating with a composition comprising cellulose nitrate, ester gum, dibutyl phthalate, and paraffin wax. In another example, the impregnating solution contains a little urea-formaldehyde syrup and ammonium chloride as well as glycerine and the salt of the stilbene derivative. In another example, a regenerated cellulose film is coated with a moisture-proofing composition containing cellulose nitrate, gum dammar, bis-(p-amino-benzoyl)-4:41-diamino-stilbene di-sodium sulphonate, paraffin wax, tricresyl phosphate, ethyl acetate, toluene, ethyl alcohol, and butyl acetate. Specifications 211,446, [Class 2 (ii)], 436,891 and 574,425 are referred to.