AQUEOUS COATING COMPOSITIONS

摘要

1397989 Silica sols DOW CHEMICAL CO 15 Aug 1972 [16 Aug 1971] 38072/72 Heading C1A [Also in Divisions C3 and B2] Aqueous silica sols having a colloidal particle size of 1-1000 microns are stabilized with a cyclic sulphonium phenoxide zwitterion of the general formula In Example (2a) an aqueous methanol solution of the zwitterion of formula (ID2) is mixed with an NH 4 OH- stabilized silica sol. In Example 2b the same silica sol. is treated with a strong acid cation exchange resin in Fe3+ form to remove the NH 3 and the unstable sol. produced is stabilized by mixing with an aqueous solution of the zwitterion of Formula IB In Example 2c a NaOH-stabilized silica sol. is slurried with a strong acid ion-exchange resin to give an unstable acidic sol., which is then stabilized with an aqueous solution of the zwitterion of Formula IB. In Example 2E a stable aqueous methanol composition is prepared from an NH 4 OH-stabilized silica sol., and a mixture of the zwitterions of Formulµ ID2 and IB. In Example 2G stable aqueous methanol compositions are prepared from the same silica sol. as used in Examples 2a, 2b, 2d and a mixture of the zwitterions of Formulµ IB and of IE In Example 2H a stable aqueous composition is prepared from colloidal tetrahydroxyethylammonium silicate and the zwitterion of Formula ID2. On drying the above compositions by heating, e.g. at 40-200‹ C. the zwitterion polymerizes and yields a water-insoluble condensation polymer with the silica particles dispersed throughout the polymer matrix in colloidal form. Reference is also made to sols. of alumina, iron oxide, magnesia, titanium dioxide, calcium carbonate and barium sulphate.