Patent GB-730861-A (GB)
Title: Production of organophilic inorganic colloids
IPC: B01J13/02
Filed: 1951-11-23
Abstract: A composition containing particles of colloidal silica is obtained by treating an aqueous silica sol with an aliphatic or cycloaliphatic amine containing more than 6 carbon atoms, and removing the aqueous dispersion medium at least partially. Depending on the nature and quantity of the amines used, liquid phases, which may accumulate to form layers, or precipitates may be obtained.  After removal of the aqueous dispersion medium the organic base present in the composition may be wholly or in part removed so as to form particles of colloidal silica.  According to examples, (i) glacial acetic acid and octadecyl amine are dissolved hot in water and a silica sol is added thereto with stirring.  The mixture is evaporated to dryness, the free acetic acid escaping with the steam and the residue comprises a silica and the amine.  It may be crushed and ground with the fingers to a very fine powder and is suitable as a rubber reinforcing agent. (ii) Sodium silicate solution is stirred with hydrochloric acid to form a silica sol. of pH 2.5-3.  The sol is heated to 85-90 DEG  C. and an equally hot emulsion of octadecyl amine in water is added with stirring.  Snow-like flakes of loosely associated colloidal particles are formed and may be freed from adhering sodium chloride solution by vacuum filtration and washing with water.  The filter cake thus formed may be dried at a 100-200 DEG  C. (iii) Octadecyl amine together with methyl amine and hydrochloric acid are dissolved in water at 85-90 DEG  C. and a hot sodium silicate solution is added thereto with stirring.  The silica coagulates to form a hydrophobic mass which is filtered as in example (ii).  (iv) A silica sol is added at room temperature to an aqueous solution of hexahydro-o-toluidine.  An emulsion is formed and on allowing to settle, two liquid layers separate, the supernatant layer consisting largely of water, together with some of the amine and a small quantity of silica.  The lower layer contains the bulk of the amine and the silica and approximately corresponds to the composition SiO2.1.8C7H15N.23H2O.  It is miscible with alcohols, acetone and pyridine.ALSO:A composition containing particles of colloidal silica is obtained by treating an aqueous silica sol with an aliphatic or cycloaliphatic amine containing more than 6 carbon atoms, and removing the aqueous dispersion medium at least partially. Depending on the nature and quantity of the amines used, liquid phases, which may accumulate to form layers, or precipitates may be obtained. After removal of the aqueous dispersion medium the organic base present in the composition may be wholly or in part removed so as to form particles of colloidal silica.  According to examples (i) glacial acetic acid and octadecyl amine are dissolved hot in water and a silica sol is added thereto with stirring.  The mixture is evaporated to dryness, the free acetic p  acid escaping with the steam and the residue comprises a silica and the amine.  It may be crushed and ground with the fingers to a very fine powder and is suitable as a rubber reinforcing agent. (ii) Sodium silicate solution is stirred with hydrochloric acid to form a silica sol of pH 2.5-3. The sol is heated to 85-90 DEG  C. and an equally hot emulsion of octadecyl amine in water is added with stirring.  Snow-like flakes of loosely associated colloidal particles are formed and may be freed from adhering sodium chloride solution by vacuum filtration and washing with water. The filter cake thus formed may be dried at a 100-200 DEG  C.  (iii) Octadecyl amine together with methyl amine and hydrochloric acid are dissolved in water at 85-90 DEG  C. and a hot sodium silicate solution is added thereto with stirring.  The silica coagulates to form a hydrophobic mass which is filtered as in example (ii). (iv) A silica sol is added at room temperature to an aqueous solution of hexahydro-o-toluidine.  An emulsion is formed and on allowing to settle, two liquid layers separate, the supernatant layer consisting largely of water, together with some of the amine and a small quantity of silica.  The lower layer contains the bulk of the amine and the silica and approximately corresponds to the composition SiO2.1.8C7H15N.23H2O.  It is miscible with alcohols, acetone and pyridine.