Patent GB-720002-A (GB)
Title: Improvements in or relating to ion-exchange materials and method of making and usingthe same
IPC: C08J5/20
Filed: 1950-06-12
Abstract: Structures of substantial size in the form of rods, tubes, discs and diaphragms consisting of ion-exchange resin gel alone supported or unsupported by fabric, or consisting predominantly of an ion-exchange resin gel which extends substantially throughout the structure, the resin gel containing at least 15 per cent by weight of the dry resin of water, are made (a) by polymerizing suitable resin components in the presence of the required quantity of water and while constraining the resin-forming materials in the required shape, or (b) combining granules of an ion-exchange resin containing at least 15 per cent water and a binder and solidifying the binder while preventing escape of the water.  The binder may itself be an ion-exchange resin.  The ion-exchange groups have a dissociation constant of at least 10-5 and are present in an amount of at least 0.3 milli-equivalent per gram of dry resin.  Acid groups specified are sulphonic and carboxylic; basic groups specified are quaternary ammonium, amines, guanidyl and dicyandiamidine.  The structures have a high conductivity generally exceeding 0.5 X 10-2 ohm-1 cm-1 If the dissociation constant is at least 10-3 the structures will undergo electrolysis with decomposition of the gel water.  The structures are useful for the continuous transfer of ions between two electrolytes, with or without an applied electric field, and as diaphragms in primary or secondary cells, and their electrical properties may be utilized in an electrolytic coulomb-meter and in the measurement of the frequency of alternating currents (see Groups III and XXXVI).  In examples: (1) phenol sulphonic acid and aqueous formaldehyde were partially polymerized at 50 DEG  C. in a closed container and the resulting viscous mixture used to impregnate various acid resisting fabrics to give diaphragms.  Discs were also cast from the viscous mixture. Curing was effected at 100 DEG  C. in a closed system in the presence of moisture; (2) beads of a carboxylic type cation exchanger of capacity about 10 milli-equivalents per dry gram and containing 20 per cent water were pulverized to finer than 100 mesh and made into a slurry with a solution of polystyrene in benzene, cast into a mould and the benzene removed at 50 DEG  C.; (3) a low polymer was formed by condensing at 40 DEG  C. for 45 minutes melamine, guanidine carbonate, aqueous formaldehyde and aqueous hydrochloric acid.  The polymer was used to impregnate fabric and to cast diaphragms and cured at 90 DEG  or 75 DEG  C. in the presence of moisture; (4) 100 parts of a sulphonated copolymer of styrene and divinyl benzene in the form of beads of 100-200 mesh were made into a slurry with 25 parts of 65 per cent aqueous phenol sulphuric acid and 12.5 parts of 35 per cent formaldehyde, the slurry cast into discs and cured in the presence of water vapour at 105 DEG  C.; (5) a slurry of 20-40 mesh beads of a styrene and divinyl-benzene copolymer having quaternary ammonium groups attached to the polymer structure, low molecular weight melamine guanidine formaldehyde polymer and water was cast into discs and cured at 105 DEG  C. in the presence of water vapour. Figures are given for the characteristic concentration potential, conductivity, moisture content, capacity and dissociation constant of the resins of example 1-5 in cast form and when supported on fabric. Example 6 describes the electrolysis of a rod of phenolsulphonic acid-formaldehyde resin; example 7 the variation with frequency of the electrical resistance of a rod of a similar resin; example 8 continuous ion-exchange between a solution of 0.02N calcium chloride circulating through the inside of a tube of a similar resin and a solution of 0.2N sodium chloride circulating outside the tube, and ion-exchange through a fabric-supported diaphragm between a 0.1N calcium chloride solution and a 0.1N potassium nitrate solution; example 9 the use of a similar resin in disc form in the sodium chloride electrolysis cell and example 10 the use of a fabric-supported resin from melamine, guanidine carbonate, formaldehyde and hydrochloric acid in a zinc-copper primary cell.ALSO:Ion-exchange resins in diaphragm form supported or unsupported on a fabric (see Groups IV(a) and VIII) are used to separate two solutions between which ion exchange takes place.  The two solutions may contain two different species of ion or two different concentrations of the same ion, exchange taking place between ions of one charge with substantial exclusion of exchange of ions of opposite charge and/or exchange of small ions with substantial exclusion of exchange of large ions.  The exchange may be enhanced by an electric field across the two solutions.  In example 8 a solution of 0.02 N calcium chloride was circulated through a tube of a phenol sulphonic acid-formaldehyde resin and a solution of 0.2 N sodium chloride circulated on the outside. Transfer of cations took place.  A reinforced diaphragm made by impregnating a fabric with the unpolymerized resin and curing at 110 DEG  C. in the presence of water was used to separate solutions of 0.1 N calcium chloride and 0.1 N potassium nitrate.  The rate of exchange of calcium ions was 1.6 x 10-2 mg. per foot hour which was greater than the rate of exchange of chloride ions (2.5 x 10-3mg. per foot hour). Anion-exchange resins may be used as barriers in Daniel cells and in the sodium chloride electrolysis cell (see Group XXXVI).ALSO:Ion-exchange resins of relatively large structural form e.g rods, tubes, discs and membranes, (see Group IV (a),) are used to separate two solutions between which ion-exchange takes place. The two solutions may contain two different species of ion or two different concentrations of the same ion, exchange taking place between ions of one charge with substantial exclusion of exchange of ions of opposite charge and/or exchange of small ions with substantial exclusion of exchange of large ions.  The exchange may be enhanced by an electric field across the two solutions.  In example 8 a solution of 0.02N calcium chloride was circulated through a tube of a phenol sulphuric acid-formaldehyde resin and a solution of 0.2N sodium chloride circulated on the outside. Transfer of cations took place.  A reinforced diaphragm made by impregnating a fabric with unpolymerized resin and curing at 110 DEG C. in the presence of water was used to separate solutions of 0.1N calcium chloride and 0.1N potassium nitrate.  The rate of exchange of calcium ions was 1.6 x 10-2mg. per foot hour which was greater than the rate of exchange of chloride ions (2.5 x 10-3 mg. per foot hour).