Patent GB-1013585-A (GB)
Title: Improvements in or relating to ion-exchange materials
IPC: B01J39/20
Filed: 1964-04-21
Abstract: High molecular weight, ion-exchanging group substituted hydrophilic copolymers consisting of mainly ball-shaped gel grains are made from partially ion - exchanging group - substituted hydroxyl-group containing polymers by reacting the latter in the presence of an alkaline reacting substance, with a bifunctional substance capable of reacting with the hydroxyl groups of the polymer as a cross-linking agent with formation of ether-like linkages, by a method comprising mixing a solution of the ion-exchanging group-substituted polymer with a liquid capable of forming a two-phase system therewith under such conditions of agitation as to transform this solution into drops, causing the cross-linking agent to react with the polymer contained in the drops, in the presence of the alkaline reacting substance at least until gel formation has taken place, and receiving the gel grains formed from the drops.  The alkaline reacting substance may be contained in the solution of the ion-exchanging group-substituted hydroxyl group containing polymer, or in the liquid forming the continuous phase of the two-phase system, or may be added to the two-phase system.  The cross-linking agent may be contacted with the partially ion-exchanging group-substituted hydroxyl group containing polymer after forming the two-phase system, or before forming the two-phase system, without permitting gel formation to take place.  Alternatively a portion of the cross-linking agent may be contacted with the partially ion-exchanging group substituted polymer before the two-phase system has been formed, without permitting gel formation to take place, and the remaining portion of the cross-linking agent then supplied to the two-phase system; or the whole amount of the cross-linking agent or part thereof may be supplied to the two-phase system as dissolved in the liquid used to form the latter.  If desired, a solution of the partially ion-exchanging group-substituted polymer, the alkaline reacting substance and the cross-linker may be maintained at such a low temperature as to prevent it being transformed into gel form, whereupon the two phase system is formed.  The degree of dispersion may be controlled by adding a high-molecular weight polymer insoluble in the solvent in which the partially ion-exchanging group substituted polymer is dissolved, suitably in a concentration of 0.1-15% calculated on the amount of the liquid which is the continuous phase of the two-phase system, especially 1-10%.  Said insoluble polymer may be capable of undergoing hydrolysis under mild conditions.  The partially ion - exchanging group-substituted hydroxyl-group containing polymers used as starting materials may be made by reacting a hydroxyl-group containing polymer with a compound of the formula Z1-R1-X2 in the presence of an alkaline reacting substance, where R1 is an alkylene radical, containing no more than 5 carbon atoms, optionally substituted by one or more hydroxyl groups, Z1 is an acid ion-exchanging group such as carboxyl, sulpho or phosphoric group or a basic group, preferably an amino group of the formula <FORM:1013585/C3/1> where R2 and R3 each are hydrogen or a lower alkyl group, optionally substituted by one or more hydroxyl groups, and R2 and R3 together are alkyls linked together into a saturated heterocyclic ring system, in the case of Z1 being an amino group, R2 containing at least 2 carbon atoms and X1 being a halogen atom, or when R1 contains two carbon atoms or more, also an epoxy group.  Specified hydroxyl group containing polymers include poly saccharides such as dextran, starch, dextrin, cellulose, polyglucose and hydroxyl group-containing uncharged derivatives thereof, e.g. methyld extran, ethyl dextran, hydroxypropyl dextran, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose or products obtained by partial depolymerization of these substances, fractions thereof, and polyvinyl alcohol.  Hydroxy group-containing polymers formed by copolymerization of hydroxyl-group containing monomers such as sorbitol, sucrose, glucose and fructose with a bifunctional substance such as epichlorhydrin or any of the compounds listed below may be used.  Specified starting materials include carboxy methyl dextran, 2-carboxyethyl dextran, 3-carboxy propyl dextran, sulphopropyl dextran, 5-sulphoaryl dextran, sulpho-methyl starch, 2-sulphoethyl starch, 3-sulphopropyl starch, 2-sulphoethyl hydroxyethyl cellulose, 3-sulphopropylhydroxyethyl-cellulose, 2-diethyl-amino-ethyl dextran, 3-diethylaminopropyldextran, 2 - dimethyl amino starch and 2-phosphono ethyl starch.  The bifunctional organic substance is preferably of the type X-R-Z where R is an aliphatic residue containing 3-10 carbon atoms and X and Z each are a halogen atom or an epoxy group, the latter being optionally linked to a carbon atom of the aliphatic group to the formation of an oxirane group. Specified bifunctional substances are epichlorhydrin, dichlorhydrin, 1,2,3,4-diepoxy-butane, bis-epoxypropyl ether, ethylene glycol-bis-epoxypropyl ether and 1,4-butane diol-bis-epoxypropyl ether. The aliphatic residue can contain substituents, preferably one or more hydroxyl groups and/or be interrupted by one or more hetero atoms, preferably oxygen atoms. The molar ratio between the bifunctional substance and the substituted hydroxyl-group containing polymer should be large enough to obtain a degree of cross-linking sufficient to form a gel.  Specified alkaline-reacting substances are sodium and potassium hydroxides, alkali-metal and alkaline earth metal carbonates and alkaline earth metal hydroxides and quaternary ammonium compounds.  Specified solvents include water, where starch, dextran and cellulose are to be treated, and alcohols and ketones or solvent mixtures in which water predominates.  To form the continuous phase of the two-phase system, liquids may be used which are immiscible with water or with the substance used as a solvent for the hydroxyl-group containing polymer.  Suitable solvents are aliphatic and aromatic hydrocarbons, halogenated aliphatic and aromatic hydrocarbons, e.g. dichloromethane, 1,2-dichloro ethane, 1,2-dibromoethane and o-dichloro-benzene, when the hydroxyl group containing polymer is dissolved in water. Specified high molecular weight polymers insoluble in water include polyvinyl acetate, polystyrene, polyisobutylene and cellulose acetate-butyrate, which may be later removed from the gel grains formed by treatment with a suitable solvent or hydrolytic agent.  Surfaceactive agents may be added if desired. Reaction temperatures specified vary from room temperature to 90 DEG  C. and are preferably between 20 DEG  and 60 DEG  C.  In Examples (1) 2-diethylaminoethyldextran hydrochloride is treated with epichlorhydrin in the presence of cellulose acetate butyrate; (2) carboxymethyldextran sodium salt is treated as in (1); (3) 2-sulphoethyldextran sodium salt is treated as in (1); (4) 2-sulphoethyl starch sodium salt is treated as in (1); (5) 2-sulphoethyl hydroxyethyl cellulose sodium salt is treated as in (1); (6) 2-sulphoethyldextran sodium salt is treated with 1,2 ethandiol-bis-2,3-epoxypropyl ether in the presence of polyvinyl acetate; (7) 2-sulphoethyl dextran sodium salt is treated with 1,2-di-bromoethane and 1,2,3,4-diepoxybutane in the presence of polymethyl methacrylate. Specifications 854,715 and 936,039 are referred to.