GB1327197A - Production of silica fibrils - Google Patents

Abstract

1327197 Production of silica fibrils IMPERIAL CHEMICAL INDUSTRIES Ltd 6 Oct 1970 [27 Oct 1969] 52446/69 Heading C1A Silica fibrils are produced by treating a fibrous mineral silicate in suspension in a liquid medium with an agent which removes at least part of the metallic oxide constituent of the fibrous mineral silicate. The fibrils are elongated particles having an axial ratio of at least 10 : 1 and having a width not greater than 0À1 micron. Generally fibrils of 10 to 100 microns in length are produced. It is convenient to make the suspension of fibrous mineral silicate e.g. chrysotile asbestos, attapulgite clay and sepiolite clay, by mechanical and/or with the aid of ultrasonic radiation in a suitable liquid e.g. water. Advantageously a surface-active agent e.g. dodecyl benzene sodium sulphonate and dioctyl esters of sodium sulphosuccinic acid is included preferably at a concentration of 0À1 to 5% by weight of total weight of silicate dispersion. Preferably the agent used to dissolve out the metallic oxide is an acid at a concentration up to 5 molar e.g. hydrochloric, sulphuric, nitric or acetic acids or with acid salts. The treatment, preferably with stirring, is carried out from 20‹ C. to the B.Pt. of the suspension for generally from 5 minutes to 48 hours. The product of the treatment process is filtered and washed with water to remove soluble inpurities and residual surface-active agent. In cases where water-insoluble surface-active agents are used, washing with a solvent for the surfaceactive agent e.g. methanol or acetone is convenient. The fibril product may then be dispersed in an aqueous medium or in a polar organic liquid or just dried.