Patent GB-635559-A (GB)
Title: Improvements in or relating to thixotropic gel systems
IPC: B01J13/00
Filed: 1946-10-08
Abstract: A thixotropic gel system comprising as a major solid constituent thereof at least one suspendably dispersable water-insoluble alkaline earth and/or iron salt is prepared by precipitating the major solid constituent by mixing intimately an aqueous solution of a water-soluble salt containing the required anion with an aqueous solution of a water-soluble salt containing the required cation, concentrating the precipitated major constituent and incorporating therewith sufficient of a citrate of an alkaline base (e.g. alkali metal base or nitrogen base) capable of forming citrates soluble in water containing up to 5 per cent citric acid to impart thixotropic characteristics to the composition at the particular hydrogen ion concentration employed. The water-insoluble salts may be sulphates, phosphates, carbonates, silicates, aluminates, molybdates, borates, chromates or malates.  The precipitation is best effected at approximately 0 DEG  C. or in the range 55-60 DEG  C.  The concentration may be effected by decantation or filtration, and for some applications the precipitate may require washing free from electrolyte.  A minor proportion of a water-soluble carbohydrates such as glucose, mannose, fructose, manoheptose, lactose, sucrose and maltose and/or a water-soluble polyhydric alcohol such as hexitol, sorbitol, mannitol and dulcitol may be added as a thixotropy pH range extender, a pH range of 5.0-6.5 being preferably without the extender or 4.0-11.0 with the extender.  The gels are useful as pigments or paints.  Examples describe the preparation of gel systems (1) containing calcium carbonate, magnesium carbonate and sodium citrate and having a pH of 5.3 or with the further addition of beta-lactose and alkali, and having a pH of 11; (2) containing calcium and magnesium carbonate, or barium and strontium sulphates, phosphates and carbonates, or calcium and magnesium silicates and hydroxides and calcium sulphate, sodium citrate, ascorbic acid, vitamins A and D, a -tocopherol beta-lactose and a flavouring agent, and having a pH of 5.2; (3) containing the alternative insoluble alkaline earth salt mixtures described in (2) together with ammonium citrate, yeast concentrate, liver extract concentrate, rice bran concentrate, thiamine hydrochloride, riboflavin and nicotinamide, and having a pH of 4.9; (4) containing the alternative insoluble alkaline-earth salt mixtures described in (2) together with sodium citrate, citric acid, phthalylsulphathiazole, and corn syrup, and having a pH of 5.25.ALSO:A thixotropic therapeutic gel system comprising as a major solid constituent thereof at least one suspendably dispersible water-insoluble alkaline earth and/or iron salt is prepared by precipitating the major solid constituent by mixing intimately an aqueous solution of a water-soluble salt containing the required anion with an aqueous solution of a water-soluble salt containing the required cation, concentrating the precipitated major constituent and incorporating therewith sufficient of a citrate of an alkaline base (e.g., alkali metal base or nitrogen base) capable of forming citrates soluble in water containing up to 5 per cent citric acid to impart thixotropic characteristics to the composition at the particular hydrogen ion concentration employed.  The water-insoluble salts may be sulphates, phosphates, carbonates, silicates, aluminates, molybdates, borates, chromates or malates.  The precipitation is best effected at approximately 0 DEG C or in the range 55 DEG -60 DEG C.  The concentration may be effected by decantation or filtration, and for some applications the precipitate may require washing free from electrolyte.  A minor proportion of a water-soluble carbohydrate such as glucose, mannose, fructose, manoheptose, lactose, sucrose and maltose and/or a water-soluble polyhydric alcohol such as hexitol, sorbitol, mannitol and dulcitol may be added as a thixotropy pH range extender, a pH range of 5.0-6.5 being preferably without the extender or 4.0-11.0 with the extender. Such preparations may also contain water-soluble or oil-soluble vitamins, amino acids, proteins, protein hydrolysates, sulphonamides, penicillin, tyrothricin, streptomycin, hormones, additional antacids, bacterial vaccines, toxoids, and virus vaccines.  Examples describe the preparation of gel systems (1) containing calcium carbonate, magnesium carbonate and sodium nitrate, and having a pH of 5.3, or with the further addition of beta-lactose and alkali and having a pH of 11; (2) containing calcium and magnesium carbonate, or barium and strontium sulphates, phosphates and carbonates, or calcium and magnesium silicates and hydroxides, and calcium sulphate, sodium citrate, ascorbic acid, vitamins A and D,  -tocopherol betalactose and a flavouring agent, and having a pH of 5.2; (3) containing the alternative insoluble alkaline earth salt mixtures described in (2) together with ammonium citrate, yeast concentrate, liver extract concentrate, rice bran concentrate, thiamine hydrochloride, riboflavin and nicotinamide, and having a pH of 4.9; (4) containing the alternative insoluble alkaline-earth salt mixtures described in (2) together with sodium citrate, citric acid, phthalylsulphathiazole, and corn syrup, and having a pH of 5.25.