GB338490A - Improvements in the production of artificial materials from solutions of cellulose or its derivatives - Google Patents

Abstract

338,490. Dreyfus, H. May 17, 1929. Grant of Patent opposed. Cellulose carboxylates and ethers, processes for making filaments and films from.-Finely-divided insoluble substances are added to solutions for dry or wet spinning or to the base or solvent thereof, in proportion not exceeding 5 per cent, and preferably amounting to 1/2 -2 per cent, of the weight of the cellulosic base so as to produce a reduced, subdued, or otherwise modified lustre. White metallic compounds are preferred, particularly those of the pigment type, which may previously be calcined at temperatures of 300-900‹ C. Suitable substances are : barium sulphate, lead sulphate, zinc oxide, barium phosphate, zinc carbonate, calcium and magnesium carbonates. calcium sulphate, alumina, and silica. To minimize settling, materials of low specific gravity, preferably below about 3, may be selected, particularly minerals such as lithium and magnesium silicates, e.g. members of the tale and serpentine groups, petalite and lepidolite, other members of the mica class, such as common mica or muscovite, and clays, e.g. kaolin, orthoclase, microline, and members of the albiteanorthite series. The spinning solution may, in addition, contain a small proportion of oil. The insoluble substance should be reduced to particles of size not exceeding 0.003 millimetre; the preferred partial size is between about 0.0005 and 0.0025 mm., although barium sulphate may be reduced to 0.003 mm. Reduction may be effected before and/or during incorporation in the spinning solutions, and wet or dry grinding may be used, but preferably a preliminary dry grinding is employed, whether or not followed by wet grinding, to allow of grading the particles, say by an air current. Wet grinding may be effected with water, .or with the solvent for the spinning solution, or with a part of the solution itself, and preferably in the presence of small proportions of dispersing agents or protective colloids, e.g. turkey-red oil, and/or in the presence of oils such as oleic acid, linseed, olive, or petroleum oil. Alternatively, the finely-divided substance may be formed by precipitation, say from barium chloride and sodium sulphate or phosphate, from aqueous solution or from the solvent itself or from other organic liquids or aqueous-organic liquids; according to the first Provisional Specification, undesirable bye-products may be avoided by using barium hydrate and sulphuric acid. A dispersion agent or protective colloid, but not the cellulosic substance itself, may also be present in this case; according to the first Provisional Specification, alkyl or aralkyl ethers of starch, cellulose, or the like, particularly water-soluble ones, are suitable for this purpose. Any acidity which develops may be neutralized by means of zinc oxide &c. The invention is particularly applicable to the production of filaments, yarns, threads, ribbons, or films from cellulose acetate, formate, propionate, or butyrate, or methyl, ethyl, or benzyl cellulose. The filaments may be twisted, immediately after formation, with normal-lustrous filaments, or otherwise associated with other fibres. Additional effects may be obtained by the processes of Specifications 328,247, 333,504, or 334,195.