GB522097A - Improvements in or relating to cleaning powders - Google Patents

Abstract

522,097. Cleansing-compositions. TAINTON, U. C. Sept. 1, 1938, No. 25631. [Class 91] A powder, cake, or crayon for cleaning delicate and other fabrics by adsorption consists essentially of alumina or stannous or stannic hydroxide mixed with silica or a silicate, each constituent having a porous or sponge-like structure and a particle size lying essentially between 10 and 100 microns. Suitable forms of silica and silicate are silica gel, diatomaceous earth, anhydrous aluminium silicate, and a zeolite, e.g., sodium aluminium silicate. Preferably the constituents are precipitated together, the alumina or hydroxide is at least 30 per cent. of the mixture, and the alumina may be activated and may be precipitated as a gel which is dried and powdered or may be formed by oxidation of aluminium smeared with mercury. Particles smaller than 10 microns may be removed by screening, elutriation, electrostatic precipitation, or air separation. In an example solutions of sodium aluminate and sodium silicate are added simultaneously to a solution of aluminium sulphate : the gelatinous precipitate is filtered off, washed, dried at 400‹C., and elutriated with water which may contain gelatin, tannin, or other dispersing agent. According to the Provisional Specification the cleaner may be (1) a mixture of an adsorbent for basic substances with an adsorbent for acidic substances ; or (2) a single amphoteric substance which will adsorb both acidic and basic substances : alumina and stannic and stannous hydroxide are given as examples. Reference has been directed by the Comptroller to Specifications 227,084, [Class 91], 373,174 and 375,383.