GB693166A - Improvements relating to ion-exchange resins - Google Patents

Abstract

Ion-exchange resins in the form of sheets, rods, discs or tubes are prepared by reacting appropriate compounds in the presence of that quantity of water necessary substantially to saturate the resulting resin gel and under conditions such that no water can escape from the reaction mass or resin gel. The resin may be prepared in a mould of appropriate shape, or a porous support may be impregnated with a resin in the liquid state and the resin gelled on the support. The quantity of water required is determined previously by experiment. In examples: (1) phenol, sodium metabisulphite, formaldehyde and sodium hydroxide were reacted under reflux in the presence of water which formed 50 per cent by weight of the mixture, to yield a viscous resin. This was placed in a long glass tube which after sealing was heated to cure the resin. After cooling, the tube was opened and the rod of resin immersed in water; (2) sulphonated phenol, formaldehyde and sodium hydroxide with sufficient water to form 50 per cent by weight of the whole mixture were heated under reflux to give a viscous resin. After cooling this was used to impregnate a filter paper which was placed in a closed glass tube containing an open ampoule of water. The resin was cured by heating, and the paper then removed and washed with water; (3) phenol, formaldehyde, tetraethylene-pentamine, and sodium hydroxide with sufficient water to form 48 per cent by weight of the mixture were reacted under reflux to yield a viscous resin. The resin was poured into a flat bottomed tube to form a thin layer which was then sealed and heated to cure the resin to a solid disc which was then removed and washed with water; (4) acetone, formaldehyde, guanidine nitrate and sodium hydroxide with sufficient water to form 46 per cent of the mixture were reacted under reflux to give a viscous resin. This was used to impregnate a sintered glass disc which was cured in a small pressure-vessel containing water. The cured disc was removed and washed with water. The Specification also refers to the production of the resins in rods and tubes by extrusion from a tube or from between two coaxial tubes into a heated closed space. The products may be used in electrodialysis, ion-exchange resin sheets being used as the partitions, for the separation of large ions from small ions and the measurement of ionic activities and mobilities. Impregnated filter papers may be used in paper chromatography.ALSO:The Specification states that filter papers impregnated with an ion-exchange resin made in such a manner that cracking of the final resin is prevented (see Group IV(a)), may be used in the separation and detection of ions by paper chromatography.ALSO:Ion exchange resins in the form of sheets, rods, discs or tubes are made by reacting the resin-forming compounds in the presence of sufficient water to ensure that the resultant gel is substantially saturated. The products do not crack. The reaction may be effected in a mould of the appropriate shape, e.g. a glass mould which is broken to release the hardened article. Long rods (or tubes) may be made by extruding the viscous resin mixture under slight pressure through a tube (or concentric tubes) heated to about 90 DEG C. and arranged in a space which is either entirely closed or has a reflux arrangement on it to prevent loss of water. The resin solidifies continuously and then passes into another space which is completely closed, the temperature being raised to that required to complete the polycondensation, e.g. 120 DEG C.