METHOD OF OBTAINING A DISPERSION OF SILICA SOL OF SMALL SALT CONTENT IN ALCOHOLS OF LOW BOILING POINT ANMD METHOD OF PRODUCING COATINGES ON METAL OR NON-METAL SUBSTRATES USING SUCH DISPERSION

摘要

Production of low-salt, up to 56 wt.% silica sol dispersions in 1-3C alcohols containing less than 1 wt.% water and having the SiO2 in the form of discrete 9-50 nm diameter particles with no inter-particle siloxane bonds comprises a one-pot process involving (i) adding a strongly acid cation exchange resin to an alkaline aqueous dispersion containing up to 50 wt.% of the above SiO2 particles, the amount of the resin being 0.6-2 times the wt. of the 1-3C alcohol and sufficient to reduce the pH to below 4; (ii) reducing the water content to below 1 wt.%; and (iii) separating off the resin and optionally concentrating the dispersion to up to 56 wt.%.