Patent GB-647528-A (GB)
Title: Production of siliceous dispersions
Inventor: SHAW CLIFFORD
IPC: C08G77/02
Filed: 1947-07-01
Abstract: Stabilized siliceous dispersions are obtained by adding to lower alkyl orthosilicates, i.e. tetra alkoxy silicanes having not more than 6 carbon atoms in the alkoxy groups and those siloxanes derived therefrom which still contain hydrolysable alkoxy groups, water in sufficient excess over that required for complete hydrolysis to provide an aqueous dispersion medium for the hydrolysis products formed in the presence of a mutual solvent for the silicon esters and water.  Solvents specified are ethyl alcohol, triethanolamine or amines having a pKa value above 7.8, e.g. as specified in Specification 612,622.  The dispersion may be used to provide coatings on natural or synthetic fibres to increase their roughness or on natural rubber to give it anti-tacking qualities.  In examples (1) one volume of ethyl orthosilicate was mixed with two volumes of triethanolamine.  The resulting solution was diluted with 25 vols. water to give a turbid dispersion; (2) solutions of (a) ethyl alcohol, water and 10 per cent HCl, (b) ethyl alcohol and water were added successively to ethyl silicate and then a further quantity of ethyl alcohol.  The solution was diluted with 25-50 vols. water per vol. solution.  Specifications 575,734, 575,752, and 641,553 also are referred to.ALSO:Stabilized siliceous dispersions are obtained by adding to lower alkyl orthosilicates, i.e. tetra alkoxy silicanes having not more than 6 carbon atoms in the alkoxy groups and those siloxanes derived therefrom which still contain hydrolysable alkoxy groups, water, in sufficient excess over that required for complete hydrolysis, to provide an aqueous dispersion medium for the hydrolysis products formed in the presence of a mutual solvent for the silicon esters and water.  Solvents specified are ethyl alcohol, triethanolamine or amines having a pKa value above 7.8, e.g. as specified in Specification 612,622, [Group IV (a)].  The dispersion may be used to provide coatings on natural or synthetic fibres to increase their roughness or on natural rubber to give it anti-tacking qualities.  In examples (1) one volume of ethyl orthosilicate was mixed with two volumes of triethanolamine. The resulting solution was diluted with 25 vols. water to give a turbid dispersion; (2) solutions of (a) ethyl alcohol, water and 10 per cent HCl; (b) ethyl alcohol and water were added successively to ethyl silicate and then a further quantity of ethyl alcohol.  The solution was diluted with 25-50 vols water per vol. solution.  Specifications 575,734, 575,752, [both in Group IV], and 641,553 also are referred to.ALSO:The tackiness of natural rubber is decreased by wetting the surface of the rubber with a stabilized silicious dispersion prepared by adding to alkyl ortho silicates sufficient water, over that required for the hydrolysis of the ester, to provide an aqueous dispersion medium for the hydrolysis of products formed in presence of a mutual solvent for the ester and water, e.g. ethyl alcohol, and ethanolamine and like amines having a pKa value greater than 7.8.  The wetted rubber is then dried.