Patent GB-626847-A (GB)
Title: Improvements in or relating to methods of finishing textile materials and the improved textile materials, fabrics or yarns resulting therefrom
IPC: D06M11/79
Filed: 1945-07-16
Abstract: Silica sols free from electrolytes and from silica gel and used for treating textiles (see Group IV (c)) are prepared by reacting an acid such as a mineral acid with a water soluble silicate.  In an example 73 lb. of 66 DEG  B<\>ae sulphuric acid are diluted with 358 lb. of water and a solution of 472 lb. of sodium silicate solution (8.9 per cent Na2O and 29 per cent SiO2) diluted with 377 lb. water added with stirring.  After 16 hours ageing, the syneresis liquor is siphoned off, the gel crushed and washed with water for 16 hours, and then treated with 750 lb. water containing 0.9 lb. caustic soda.  After standing for 6 hours the excess liquor is drained off and a portion of the gel transfrerred to an autoclave, heated with steam at 215 lb. absolute pressure for 3 hours.  The undispersed gel is removed by filtration.  The solution so produced contains about 12.5 per cent of silica and may be diluted for use till it contains 0.1 per cent. Specification 607,696 and U.S.A.  Specifications 2,244,325, 2,285,449, 2,285,477 and 2,375,738 are referred to.ALSO:Textile materials other than textile fibres, such as yarns and fabrics, are treated with a substantially electrolyte-free colloidal solution of submicroscopic particles of silica consisting of silica sol free from silica gel in an amount sufficient to supply from 0.1 to 10 per cent of silica based on the weight of the material, and the so-treated material is then dried.  The drying may be carried out by passage over steam-heated cans or by infra-red heated tenter frames at a temperature of 200 DEG  F. or higher.  Wetting agents such as the sodium alkylated benzene sulphonates, sodium lauryl sulphate, the sodium salt of methyl stearamide ethionic acid, and dioctyl sodium sulphosuccinate in amounts from 0.1 to 5 per cent, and softening agents including aqueous emulsions of oils, fats, waxes, fatty acids, and cationic softeners, e.g. the quaternary ammonium salts, such as cetyl dimethyl benzyl ammonium chloride and the tertiary amine salts such as diethyl aminoethyl oleyl amide hydroacetate, in amounts from 0.03 to 3 per cent may be added to the colloidal solution. The silica content may be 0.1-10 per cent, but up to 30 per cent may be employed.  Resins may be added to increase the fastness of the silica to the fabric.  Such resins may be aqueous emulsions of polyvinyl chloride, polyvinyl acetate, polymethyl methacrylate, polyvinyl formal, acetal and butyral, rubber latex, polystyrene, and their copolymers; aqueous solutions of polyvinyl alcohol, methyl cellulose, methylolureas, dito hexa-methylol melamines, and alkylated alkylol melamines and ureas.  The amount of resin may be 0.1 to 5 per cent in general, but if additional properties such as shrink-proofing are to be imparted to the fabric, the amount of resin may be increased to 10 to 20 per cent.  The process is applicable to cotton, wool, rayon (including cellulose esters and regenerated cellulose), nylon, protein materials such as silk and casein, copolymers of vinyl chloride and vinylidene chloride, vinyl acetate and vinyl chloride, and glass, and to yarns and fabrics containing mixtures or blends of any two or more of the above materials.  The sols may be applied by spraying or immersion, and may have a pH of 7-10, though a lower pH down to 4 may be employed.  The treated yarns and fabrics possess fullness, a delustred appearance and an increased coefficient of friction and increased tensile strength.  In an example, a p substantially electrolyte-free colloidal solution of silica is prepared by diluting a sodium silicate solution containing 29 per cent SiO2 with water and adding to dilute sulphuric acid. After ageing for 16 hours the syneresis liquor is syphoned off and the gel crushed and washed with water and neutralized with dilute caustic soda.  The gel is then charged into an autocalve and heated with steam at 215 pounds per square inch absolute pressure for three hours, the contents of the autoclave being filtered to remove residual gel and then diluted to contain 0.1 per cent SiO2.  Bleached cotton sheeting is immersed in this silica sol and padded to 100 per cent pick-up, framed and dried at 250 DEG  F.  Specification 607,696 and U.S.A. Specifications 2,244,325, 2,285,449, 2,285,477 and 2,375,738 are referred to.