GB388421A - Improvements in or relating to compositions of matter - Google Patents

Abstract

In the preparation of compositions containing acetone-soluble cellulose acetates &c. or acetone-soluble cellulose ethers, more particularly moulding powders, and of articles such as sound-records, there are employed cellulose derivatives of low viscosity characteristics, namely, of viscosity below 5, preferably between 0,5 and 3, as measured by the rate of flow of a 6 per cent solution relative to that of glycerine, taken as 100. p By the use of these low viscosity products, a better reproduction of the surface of the mould is obtained, together with an economy of solvent when such is used in the preparation of the composition &c. Low viscosity cellulose acetates may be obtained by the employment of high temperatures during the acetylation, see Specification 326,515, [Class 2 (ii), Cellulose &c.], or by the employment of large proportions of strong catalysts, or by prolonging the duration of the acetylation reaction; or, alternatively, by hydrolysing the primary acetylation solutions at high temperatures or for long periods of time; or again by treatment of cellulose acetate with hydrogen peroxide in the presence of iron salts, see Specification 273,473, [Class 81 (ii), Medical &c. appliances], or preferably by heating under pressure with water or aqueous liquid, see Specification 377,313, or with aqueous solutions of salts or mineral acids. The compositions may contain plasticizers, fire-retardants, pigments, effect materials, etc.; and the ingredients may be incorporated with the aid of solvents and at elevated temperatures, or as an alternative the cellulose derivative and plasticizer may be simply ground together. The Specification as open to inspection under Sect. 91 includes the application of the invention to organic derivatives of cellulose in general, and it refers to the production of films, foils and transparent paper by casting on wheels, bands, &c. or by extrusion into precipitating baths, and also of artificial filaments, yarns, horsehair, &c. by wet or dry methods. This subject-matter does not appear in the Specification as accepted.ALSO:In the preparation of compositions containing acetone-soluble cellulose acetates &c. or acetone-soluble cellulose ethers, more particularly moulding powders, there are employed cellulose derivatives of low viscosity characteristics, namely, of viscosity below 5, preferably between 0,5 and 3, as measured by the rate of flow of a 6 per cent solution relative to that of glycerine taken as 100. By the use of these low viscosity products, a better reproduction of the surface of the mould is obtained, together with an economy of solvent when such is used in the preparation of the composition &c. The compositions may contain plasticizers, fire retardants, pigments, effect materials etc.; and the ingredients may be incorporated with the aid of solvents and at elevated temperatures, or as an alternative the cellulose derivative and the plasticizers may be simply ground together.