GB581436A - Process for rendering cellulosic fibres, or fabrics, transparent - Google Patents

Abstract

Cellulosic fibres or fabrics are rendered transparent by impregnation with a solution of cellulose zincate followed by mercerization while the goods are in the damp condition. Cellulose zincate solutions containing 2-5 per cent cellulose and having a total alkalinity of 5-8 per cent referred to NaOH, and fabrics or fibres of cotton or regenerated cellulose, including pre-mercerized fabrics, may be used. If desired, the cellulose may be regenerated after impregnation by precipitation with salts or dilute acids. Mercerization is preferably performed under tension with alkali of mercerization strength. Acid treatment may be carried on in place of or in combination with mercerization. In examples: (1) bleached unmercerized cotton muslin impregnated with a solution containing 4 per cent cellulose, 2 per cent zinc oxide and 6 per cent total alkali, calculated as NaOH, is mercerized, without intermediate drying in caustic soda solution (30 DEG B<\>ae) for 1/2 minute; (2) bleached unmercerized cotton muslin impregnated with a solution containing 3 per cent cellulose, 1.5 per cent zinc oxide and 7.5 per cent total alkali, calculated as NaOH and subjected to the action of a solution containing 50 gms. calcined Glauber salt and 25 c.cs. of concentrated sulphuric acid per litre, followed by washing in cold water until neutral, and squeezed, is mercerized in caustic soda solution (32 DEG B<\>ae) for 1 minute; (3) mercerized, bleached cotton muslin impregnated with cellulose zincate solution and subjected to the acid treatment as in (2) is steeped for 12 seconds in sulphuric acid (50 DEG B<\>ae at 15 DEG C.). Local "effects" may be obtained by applying the solution with a printing roller. The cellulose zincate solution may be made by boiling zinc oxide with sodium hydroxide solution until a clear solution is obtained, diluting with water and then cooling to room temperature. Viscose waste is added, and the solution is allowed to stand for 1-2 days, after which more water is added. Specification 573,768 is referred to.