| 摘要 |
A cation-exchange resin is made by reacting phenol sulphonic acid with 1 to 2 molecular equivalents of formaldehyde and at least 2.3 molecular equivalents of water to form a resin containing not more than 15 per cent of water and drying the unwashed resin at 100-200 DEG C. in a current of an inert gas (e.g. air, carbon dioxide or nitrogen) until it contains not more than 10 per cent of water. In examples: (1) 350 parts of p-phenol sulphonic acid and 80 parts of 30 per cent aqueous formaldehyde solution are heated first at 55-65 DEG C. and then at 100 DEG C.; the mixture is cooled to 80 DEG C., an additional 120 parts aqueous formaldehyde added and the mixture heated to 90 DEG C. Two portions of the resin ground to a powder are heated at 100 DEG C. in a current of air respectively for 8 and 72 hours; (2) 874 parts of p-phenol sulphonic acid, 225 parts formaldehyde and 1550 parts of water are heated at 90-100 DEG C., the mass ground to a powder and two portions heated at 100 DEG C., respectively, for 6.5 and 23.5 hours. Specification 489,437 and U.S.A. Specification 2,230,641 are referred to.ALSO:Water is softened by cation exchange resins made by reacting phenol sulphonic acid, formaldehyde and water to form a solid resin and drying the unwashed resin at 100 DEG -200 DEG C in a current of an inert gas (see Group IV(a)). In examples 100 parts of the resin are stated to absorb calcium ions from solution in an amount corresponding respectively to 8.4, 8.54, 5.6 and 6.3 parts of calcium oxide. Specification 489,437 and U.S.A. Specification 2,230,641 are referred to. |
