GB753730A - A method of rendering fabrics water-repellent - Google Patents

Abstract

Co-hydrolysis products of a mixture consisting essentially of from 65 to 95 mol. per cent of (CH3)2SiCl2 and from 5 to 35 mol. per cent of HSiCl2 may be prepared as follows:-(i) To a mixture of HSiCl3, (CH3)2SiCl2 and toluene a mixture of methanol and toluene is added over a period of 35 minutes. Then water and toluene are added slowly. The toluene layer is separated, washed with water until neutral, filtered through diatomaceous earth and strip distilled to yield a solution containing the hydrolysate. (ii) Excess water is added over a period of two hours to a solution of (CH3)2SiCl2 HSiCl3 in ether. The ether layer is separated, washed to neutrality and all materials boiling below 78 DEG C. at 2.5 mm. are removed to yield a liquid co-hydrolysate. (iii) Water and tetrahydrofuran are added slowly to a solution of HSiCl3 and (CH3)2SiCl2 in toluene and ether. The organic layer is separated, washed free from acid and then concentrated by distillation. (iv) A mixture of water, tetrahydrofuran, ice and sodium bicarbonate is added to an equimolecular mixture of HSiCl3 and (CH3)2SiCl2 dissolved in isopropyl ether. Further specified solvents are benzene, ethanol and isopropanol. Aqueous emulsions of the hydrolysates may be formed by the action of heat decomposible emulsifying agents. Specified agents are quaternary ammonium halides such as hexadecyl dimethyl benzyl ammonium chloride. The siloxane may be dissolved in a solvent which, after emulsification, is removed under vacuum. Specifications 628,072, 635,995, 636,905 and 680,265 are referred to.