MXPA99010230A - Procedure for obtaining single-speed anchor exchangers in the form of - Google Patents

Abstract

The present invention relates to a process for obtaining monodispersed anion exchangers, in gel form, with high stability and purity, from a polymer in pearls with a swelling index of 2.5 to 7.5 and with a contained in non-evaporable, soluble parts, less than 1% in pe

Description

PROCEDURE FOR OBTAINING SPANISH MONOD SPLIT ANCHOR EXCHANGERS IN THE FORM OF GEL Field of the Invention The invention relates to a process for obtaining monodispersed anion exchangers, in gel form, with high stability and purity.

Background of the Invention In recent years, ion exchangers with particle sizes as unitary as possible (hereinafter referred to as "monodispersed") have become increasingly important, since in many applications economic advantages can be achieved due to the favorable hydrodynamic properties of a bed. of exchanger constituted by monodispersed ion exchangers. Monodispersed ion exchangers can be obtained by functionalizing polymers in monodispersed beads. Another possibility for obtaining polymers in monodispersed beads consists of the REF .: 31791 procedure called sowing / feeding, according to which a monodispersed polymer ("sowing") is swollen in the monomer and this is then polymerized. Sowing / feeding procedures are described, for example, in EP-A-0098 130 and EP-A-0 101 943. The seed polymers used in the seeding / feeding procedures must have a high swelling index in order to that can absorb a large amount of the monomer added in the sowing / feeding procedure. As a swelling index (QI) the quotient between the volume of the swollen polymer and the volume of the non-swollen polymer is defined. The swelling index can be controlled in a known manner by the crosslinking content: low crosslinker contents lead to high swelling rates and vice versa. Thus, for example, styrene polymers, which are crosslinked with 0.8 to 2.0% by weight of divinylbenzene, have swelling rates of 8 to 2.5 in toluene. Seed polymers with low crosslinking have, of course, a really high proportion in soluble, non-crosslinked polymers. This proportion in soluble, non-crosslinked polymers in the seed polymer is undesirable from many points of view: 1. The polymerization of the swollen seeding can be impaired because the polymer parts removed by dissolving the seeding by means of the added monomer, cause glueing of the particles together. 2. Functionalization for obtaining anion exchangers can be difficult because the parts of the polymer eliminated by dissolution can be enriched in the reaction solutions used for the operation. 3. Anion exchangers can contain high amounts in soluble polymers, which can lead to undesirable bleeding (leaching) of the ion exchanger.

Another problem with known ion exchangers is their mechanical and osmotic stability which are not always sufficient. In this way the beads of the anion exchangers can be broken during manufacture or during their use due to the mechanical or osmotic forces that arise. For all applications of anion exchangers it is valid that the exchanger, present in the form of beads, has to maintain its habit and should not be partially or even completely decomposed during application or should not be broken into broken pieces. The broken pieces and the splinters of the polymer in pearls can reach the solutions to be purified during the application and even cause their impurification. Furthermore, the presence of polymers in damaged pearls is also unfavorable for the operation of the ion exchanger used in the column processes. The splinters lead, on the one hand, to high pressure losses of the system in column and thus reduce the flow rate of the liquid to be purified through the column.

Detailed description of the invention The object of the present invention is to provide monodispersed ion exchangers in the form of a gel with high stability and purity. For purity in the sense of the present invention, it should be noted, first of all, that the anion exchangers do not bleed. The bleeding is expressed by means of an increase in the conductivity of the water treated with the ion exchanger. It has now been found that monodispersed anion exchangers, in gel form, with high stability and purity can be obtained by u? Sowing / feeding procedure using polymers with high swelling capacity and low content, in soluble polymer parts. The object of the present invention is a process for obtaining monodispersed anion exchangers, in the form of a gel, with high stability and purity, comprising the following process steps: a) formation of a suspension of seed polymer in a phase continuous aqueous, b) swelling of the seed polymer in a monomer mixture consisting of vinyl monomers, crosslinkers and radical initiators c) polymerization of the mixture, of monomers in the seed polymer, d) functionalized of the copolymer formed by chlorine ethylation and subsequent amination, characterized in that the seed polymer is a cross-linked polymer with a swelling index of 2.5 to 7.5 (measured in toluene) and with a content of soluble, non-evaporable parts (measured by extraction with tetrahydrofuran) less than 1% by weight.

In a special embodiment of the present invention, a crosslinked polymer, prepared from i) 96.5 to 99.0% by weight of monomer, ii) 0.8 to 2.5% by weight, is used as the seed polymer. weight of crosslinker and iii) 0.2 to 1.0% by weight of aliphatic peroxyester in the manner of polymerization initiator.

The monomers (i) for the preparation of the seed polymer are compounds with a C = C double bond polymerizable by radicals per molecule. Preferred compounds of this type include aromatic monomers, such as, for example, vinyl- and vinylidene-benzene and naphthalene derivatives, such as, for example, vinylnaphthalene, vinyltoluene, vinylstyrene, α-methylstyrene, chlorostyrenes, preferably styrene, as well as vinyl and vinylidene- non-aromatic compounds, such as for example acrylic acid, methacrylic acid, alkyl acrylate with 1 to 8 carbon atoms, alkyl methacrylate with 1 to 8 carbon atoms, acrylonitrile, methacrylonitrile, acrylamide, ethacrylamide, vinyl chloride , vinylidene chloride and vinyl acetate, as well as mixtures of these monomers. Preferably, the non-aromatic monomers are used in minor amounts, preferably in amounts of 0.1 to 50% by weight, in particular 0.5 to 20% by weight, based on the aromatic monomers. In most cases, however, exclusively aromatic monomers will be used. Suitable crosslinking agents 11 are compounds containing two or more, preferably two to four double bonds polymerized by radicals, per molecule. For example, it is possible to cite: divinylbenzene, divinyl toluene, trivinylbenzene, divinylnaphthalene, d trivinylnaphthalene, diethylene glycol divinyl ether, octadiene-1,7, hexadiene-1, 5, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tri-methylolpropanetrimethacrylate, allyl methacrylate, and methylene-N, N'-bisacrylamide. Divinylbenzene will be preferred as crosslinking agents. For most applications, commercial grades of divinylbenzene are sufficient, which also contains the isomers. The aliphatic peroxyesters iii) for the preparation of the seed polymers correspond to the formulas I, II or III R 1 I ?. ?? W "RO22 R pi Formula I Formula II Formula III where R 1 signifies an alkyl radical having 2 to 20 carbon atoms or a cycloalkyl radical with up to 20 carbon atoms, R 2 represents a branched alkyl radical with A at 12 carbon atoms and L is an alkyl radical having 2 to 20 carbon atoms or a cycloalkyl moiety with up to 20 carbon atoms. Preferred aliphatic peroxyesters according to formula I are, for example tert-butylperoxyacetate, tert-butylperoxyisobutyrate, tere. -butylperoxipivalate, tere. -butyl peroxoctoate, tert-butylperoxy-2-ethylhexanoate, tere. -butylperoxineodecanoate, tere. -amilpero i eodecanoato, tere. -amilperoxipivalate, tere. -amilperoxioctoate, tere. -amilyloxy-2-ethylhexanoate and tere. -Imbapero ineodecanoate.

Preferred aliphatic peroxyesters of formula II are, for example, 2, 5-bis (2-ethylhexanoylperoxy) -2,5-dimethylhexane, 2,5-dipivaloyl-2,5-dimethylhexane and 2,5-bis (2- neodecanoylperoxy) -2,5-dimethylhexane. Preferred aliphatic peroxyesters according to formula III are, for example, di-tere. -butylperoxyacetate and di-tere. -amilperoxyacetylate.

Of course, it is also possible to use mixtures of the aforementioned polymerization initiators. In another preferred embodiment of the present invention the seed polymer is icroencapsulated. In this case it is especially advantageous to microencapsulate the components for obtaining the seed polymer (monomer (i), crosslinker (ii) and aliphatic peroxyester as polymerization initiator (iii)) and harden the microencapsulated particles to give the polymer of sowing For the microencapsulation the known materials for this purpose come into consideration. Especially polyester, natural and synthetic polyamides, polyurethanes, polyureas. As a natural polyamide, gelatin is particularly suitable. This is used especially as a coacervate and a complex coacervate. In the sense of the invention, complex coacervates containing gelatin will be understood in all combinations of gelatin and synthetic polyelectrolytes. Suitable synthetic polyelect rollers are copolymers with incorporated units of, for example, maleic acid, acrylic acid, methacrylic acid, acrylamide and methacrylate. Capsules containing gelatin can be hardened with customary curing agents such as, for example, formaldehyde thi glutaraldehyde. The encapsulation of the monomer droplets, for example with gelatin, gelatin-containing coacervates and complex coacervates containing gelatin is described extensively in EP-A-0 046 535. The synthetic polymer encapsulation methods are known per se. For example, condensation is suitable in a very good manner at the boundary surface between the phases, in which a reaction component dissolved in the monomer droplet (for example isocyanate or an acyl chloride) is reacted. with a second reaction component, dissolved in a monomer droplet (for example an isocyanate or an acyl chloride) with a second reaction component, dissolved in the aqueous phase, (for example an amine). Microencapsulation with complex coacervate containing gelatin is preferred. The polymerization (hardening) of the icroencapsulated droplets of monomer (i), crosslinker (ii) and aliphatic peroxyester (iii) to give the seed polymer is carried out in aqueous suspension, it being preferred to employ an inhibitor dissolved in the aqueous phase, it being preferred to employ an inhibitor dissolved in the aqueous phase. Suitable inhibitors are inorganic or organic products. Examples of inorganic inhibitors are hydrogenated compounds such as hydroxylamine, hydrazine, sodium nitrite and potassium nitrite. Examples of organic inhibitors are phenolic compounds such as hydroquinone, hydroquinone monomethyl ether, resorcin, pyrocatechin, tere. -but ilpirocatecholine, condensation products of phenols with aldehydes. Other organic inhibitors are nitrogen compounds such as for example diethylhydroxylamine and isopropylhydroxylamine. Resorcin will be preferred as an inhibitor. The concentration of the inhibitor is from 5 to 1,000 ppm, preferably from 10 to 500 ppm, more preferably from 20 to 250 ppm, based on the aqueous phase. The seed polymer is isolated from the aqueous suspension after polymerization, and dried, preferably to a water content of less than 0.5% by weight. The particle size of the seed polymer is from 5 to 500 μm, preferably from 20 to 400 μm, particularly preferably from 100 to 300 μm. The shape of the curve of the particle size distribution must correspond to the desired anion exchanger. In order to obtain a narrowly distributed or monodispersed ion exchanger, therefore, a seed polymer with narrow or onodispersed distribution will be used. The dried seed polymer is suspended in an aqueous phase, the ratio between the polymer and water being between 2: 1 and 1:20. preferably it will be from 1: 2 to 1:10. The use of an auxiliary product, for example of a surfactant or protective colloid, is not necessary.

The suspension can be carried out, for example, with the aid of a normal stirrer, using low to medium shear forces. A mixture of monomer (a), crosslinker (aa) and radical initiator (aaa) "feed" will be added to the suspended seed polymer. The monomers (a) indicated above are suitable as monomers (a), namely styrene, vinyltoluene, ethylstyrene, o-methylstyrene, chlorostyrene, acrylic acid, methacrylic acid, esters of acrylic acid, esters of methacrylic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, as well as mixtures of these monomers, styrene is preferred. Suitable crosslinking agents (aa) include divinylbenzene, divinyl toluene, trivinylbenzene, divinylnaphthalene, trivinylnaphthalene, diethylene glycol divinyl ether, octadiene-1,7, hexanediene-1,5, and ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane trimetaerylate, allyl methacrylate, and methylene-N, N '-bisacrylamide. Divinylbenzene is preferred. For most applications, commercial grades of divinylbenzene are sufficient, which contain, in addition to the isomers of divinylbenzene, also ethylvinylbenzene. The content of crosslinking agents in the monomer mixture is from 1 to 20% by weight, preferably from 4 to 12% by weight. The radical initiators (aaa) suitable for the process according to the invention are, for example, peroxy compounds such as dibenzoyl peroxide, dilauroyl peroxide, bis (p-chlorobenzoylperoxide), dicyclohexylperoxydicarbonate, tere. -butylperoctoate, 2,5-bis (2-ethylhexanoylperoxy) -2,5-dimethylhexane and tere. -amylperoxy-2-ethylhexane, in addition azo compounds such as 2,2'-azobis (isobutyronitrile) and 2,2'-azobis (2-methylisobutyronitrile). The radical initiators are generally used in amounts of 0.5 to 2.5% by weight, preferably 0.2 to 1.5% by weight, based on the mixtures of monomer (a) and crosslinker (aa). The ratio between the seed polymer and the aggregate mixture (seed / feed ratio) is generally 1: 0.5 to 1:20, preferably 1: 0.75 to 1:10, particularly preferably 1 : 1 to 1: 5. The added mixture swells in the seed polymer. The maximum amount of feed, which can be completely absorbed by sowing, depends to a large extent on the crosslinking content of the sowing. With a given size of the particles of the seed polymer, the size of the particles of the copolymer formed or of the ion exchanger can be adjusted by means of the seed / feed ratio. The polymerization of the swollen seed polymer to give the copolymer is carried out in the presence of one or more protective colloids and, if necessary, of a buffer system. Suitable protective colloids are water-soluble and synthetic water-soluble polymers, such as, for example, gelatins, starches, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylates, polymethacrylic acid and copolymers of (meth) acrylic acid and acid esters. (met) acrylic. Cellulose derivatives, especially cellulose esters and cellulose ethers, such as carboxymethylcellulose and hydroxyethylcellulose, are also very suitable. The cellulose derivatives are preferred as protective colloids. The amount of protective colloids used is, in general, from 0.05 to 1% by weight, based on the aqueous phase, preferably from 0.1 to 0.5% by weight. The polymerization can be carried out in the presence of a buffer system. Preference will be given to buffer systems which adjust the pH value of the aqueous phase at the start of the polymerization to a value between 14 and 6, preferably between 13 and 9. Under these conditions the protective colloids with carboxylic acid groups are present in total or partially in the form of salts. In this way, the effect of the protective colloids is favorably influenced. Suitable buffer systems in an especially good way contain phosphate or borate salts.

The ratio between the organic phase and the aqueous phase during the polymerization of the swollen seeding is from 1: 1 to 1:20, preferably from 1: 1.5 to 1:10. The temperature during the polymerization of the swollen seeding polymer depends on the decomposition temperature of the initiator employed (aaa). This is, in general, between 50 and 150 ° C, preferably between 55 and 130 ° C, particularly preferably between 60 and 100 ° C. The polymerization lasts from 1 up to a few hours. It has been proven to employ a temperature program in which the polymerization is initiated at a low temperature, for example at 60 ° C, and the reaction temperature is increased as the polymer conversion proceeds. In this way, the requirement for a safe development of the reaction and a high conversion to polymer can be fulfilled in a very good manner. After the polymerization, the copolymer can be isolated according to customary methods, for example by filtration or decantation, and can be dried, if appropriate after one or more washings, and, if desired, sieved. The conversion of the copolymer into anion exchangers is carried out by chloromethylation and subsequent amination. Chloromethylmethylether is preferably used for chloromethylation. The chloromethylmethylether can be used in a non-purified form, which can contain, for example, a secondary component, for example methylal and methanol. The chloromethyl methyl ether is used in excess and acts not only as a reactant but also as a solvent and swelling agent. Therefore, it is not necessary, in general, the use of an additional solvent. The chloromethylation reaction is catalyzed by the addition of a Lewis acid. Suitable catalysts are, for example, ferric chloride (III), zinc chloride, tin (IV) chloride and aluminum chloride. The temperature of the reaction can be in the range of 40 to 80 ° C. When working in the absence of pressure, a temperature range of 50 to 60 ° C is especially convenient. During the reaction, volatile components such as hydrochloric acid, methanol, methylal, formaldehyde and partially chloromethylmethylether can be removed by evaporation. For the removal of the rest of the chloromethyl methyl ether as well as for the purification of the chloromethylate, a washing with methylal, methanol and finally with water can be carried out. It has been found that in the process according to the invention with excess chloromethyl-methyl ether only a very small amount of polymer components are obtained.

The polymeric components that would be eliminated by dissolving the copolymer are undesirable since they make difficult the recovery and the reuse of the chloromethyl methyl ether in excess. In order to obtain weakly basic anion exchangers, the chloromethyl copolymer is reacted with ammonia, with a primary amine, such as methyl- or ethylamine or with a secondary amine such as dimethylamide. Reaction with tertiary amines leads to strongly basic ion exchangers. Suitable tertiary amines are trimethylamine, dimethylaminoethanol, triethylamine, tripropylamine, and tributylamin. For the complete conversion of the chloromethylated copolymer, at least 1 mole of amine is required, based on 1 mole of chlorine in the chloromethylate. A slight excess in amine will be preferred. 1,1 to 1,3 mol of amine per mol of chlorine are particularly preferred. The amination reaction is carried out in the presence of water. In this case, water fulfills various tasks. The agitation medium, the reaction medium, the solvent for the amine and the swelling agent for the anion exchanger formed are constituted. During the amination the resin continuously absorbs water and swells. Therefore, a minimum amount of water is required to keep the load agitable. There is no special maximum water limit. Of course very high amounts of water are unfavorable since, as a consequence of the dilution, the space / time yields are reduced. At least 1.5 g, preferably 2 to 4 g, of water should be used per gram of chloromethylated copolymer. The reaction mixture may contain subordinate amounts of solvents, such as alcohol. In this way, the use of a chloromethylated copolymer moistened with methanol is not detrimental. Preferably, however, no organic solvent will be added. In a special embodiment of the present invention, the amination will be carried out in the presence of an inorganic salt dissolved in water. Suitable salts are halides, carbonates and sulfates, soluble in water, of alkali metals, such as sodium and potassium and alkaline earth metals, such as magnesium and calcium. Preferably, sodium chloride will be used. The inorganic salt will be used in an amount of less than 5% by weight, based on the total amount of water. Preferably, from 1 to 4.5% by weight, more preferably from 1.5 to 4% by weight of inorganic salt, based on the total amount of water, will be used. The total amount of water is deducted from the sum of the added water and the amount of water incorporated with an aqueous solution of amine. The temperature, at which the amination is carried out, can be in the range between room temperature and 160 ° C. The temperatures between 70 and 120 ° C, particularly preferably in the range between 70 and 110 ° C, will be preferred. After amination, the ion exchanger obtained is washed with water and then treated in dilute hydrochloric acid (1 to 10%) at temperatures of 20 to 120 ° C, preferably 50 to 90 ° C. The product is allowed to decant, for example, or is isolated by filtration and washed with water for further purification.

Obviously, the sand exchangers according to the invention can be transformed in a known manner into other forms by exchange of the chloride ion with another counterion. The anion exchangers obtained according to the process of the invention are characterized by particularly high stability and purity. These also do not present any defect on the beads of the ion exchangers even after a prolonged use and a large number of regenerations and have a bleeding (leached) clearly less than the exchanger.

And emplos. Test methods Soluble, non-evaporable part of the sowing polymer. For the determination of the soluble part, 5 to 7 g of the seed polymer were exposed in an extraction sheath and extracted overnight in a Soxhlet apparatus with 800 ml of toluene (bath temperature 140 ° C). The extract was filtered through a nutcha with black band filter and concentrated by evaporation in the rotary evaporator to approximately 1 ml. Then 300 ml of methanol were added and dried under vacuum in the rotary evaporator until weight constancy. A double determination was carried out for each sample.

Swelling of the sowing polymer. The swelling of the seed polymer was tested with toluene. To do this, 10 ml of the polymer was placed in dry, sieved beads, in a test tube with a foot of 100 ml. The test piece with foot was completed up to 100 ml with the swelling agent and allowed to stand for 10 to 20 hours. In this case it was shaken frequently and then measures were taken so that the air bubbles eventually formed could escape. The volume of the swollen bulk charge was measured and gave Va. The quotient between Vi and the volume of the charge of the non-swollen pearls V0 is by definition the swelling index (QI).

Number of perfect pearls after obtaining. 100 beads were observed under the microscope. The number of pearls that show cracks or that show chips are determined. The number of perfect pearls is given by the difference between the number of damaged pearls and 100.

Stability when swelling. 25 ml of the anion exchanger are charged in the chloride form into a polycarbonate plastic column, with a length of 540 mm, diameter 19 mm, with sieve devices on the head and bottom, mesh width 0.3 mm.

The resin is rinsed from the bottom, for 5 minutes, with 500 ml of deionized water. The following is treated successively with 500 ml of aqueous sodium hydroxide solution at 4% by weight, 500 ml of deionized water and 500 ml of 6% hydrochloric acid and 500 ml of deionized water flowing the sodium hydroxide solution and hydrochloric acid from the top respectively for 10 minutes, through the resin and pumping the deionized water from the lower part, respectively for 5 minutes, through the resin. The treatment is carried out at intervals of time by means of a control device. The work cycle lasts 1 hour. 20 work cycles are carried out. After the end of the work cycles, 100 beads of the resin sample are counted. The number of perfect pearls that are not damaged by cracks or chipping is determined.

Example 1. (Comparative example). A copolymer was prepared according to Example 2 of DE-19 634 393. This was chloromethylated according to the method described in Example 9 of DE-19 634 393. In this case, they were precipitated from the filter of the reaction mixture. about 20 g of oligomer per 1000 g of polymer with an excess of methanol. The chloromethylated copolymer was converted into a strongly basic ion exchanger according to the method described in Example 10 of DE 19 634 393 by amination with trimethylamine.

Example 2 (According to the invention). a) Obtaining a seed polymer. 1,960 ml of deionized water are placed in a 4-liter glass reactor. 630 g of a microencapsulated mixture consisting of 1, 0% by weight of divinylbenzene, 0.6% by weight of ethylstyrene (used as a commercial mixture consisting of divinylbenzene and ethylstyrene with 63% by weight of divinylbenzene), 0.5% by weight of tere. -but ilperoxy-2-ethexanoate and 97.9% by weight of styrene, the microcapsules being constituted by a complex coacervate, hardened with formaldehyde, constituted by gelatin and by an acrylamide / acrylic acid copolymer. The average particle size is 231 μm. The mixture is combined with a solution consisting of 2.4 g of gelatin, 4 g of sodium hydrogen phosphate dodecahydrate and 100 mg of resorcinol in 80 ml of deionized water, stirred slowly and polymerized under stirring for 10 hours at 75 ° C. . The polymerization is then concluded by increasing the temperature to 95 ° C. The load is washed through a 32 μm sieve and dried. 605 g of a polymer in the form of spheres, microencapsulated, with a smooth surface is obtained. The polymers appear optically transparent; The average particle size is 220 μm. The seed polymer has a swelling index in volume of 4.7 and a soluble proportion of 0.45%. b) Obtaining a copolymer. 416.2 g of seed polymer from a 4-liter glass reactor are charged to the reactor. (a) and an aqueous solution formed by 1100 g of deionized water, 3.6 g of boric acid and 1 g of sodium hydroxide and the stirring speed is adjusted to 220 rpm (revolutions per minute). A mixture of 713.4 g of styrene, 56 g of divinylbenzene, 14 g of ethylstyrene (used together as a commercially available mixture of divinylbenzene and ethylbenzene with 80.0) is added as a feed in the course of 30 minutes. % divinylbenzene) and 6.3 g of dibenzoyl peroxide (75% by weight, moistened with water). The mixture is stirred at room temperature for 60 minutes, the gaseous space being flushed with nitrogen. Then a solution of 2.4 g of methylhydroxyethylcellulose in 120 g of deionized water is added. The mixture is now heated to 63 ° C and left at this temperature for 11 hours at this temperature, then heated for 2 hours at 95 ° C. The charge is washed, after cooling, deeply through a 40 μm sieve with deionized water and then dried for 18 hours at 80 ° C in the drying cabinet. 1150 g of a copolymer in the form of spheres are obtained, with a particle size of 370 μm. c) Chloromethylation of the copolymer A mixture consisting of 1600 g of monochlorodimethylether, 165 g of methylal and 5 g of ferric chloride (III) is added in a 3-liter sulfonation vessel and then 300 g of the copolymer from b) are added. The mixture is allowed to stand for 30 minutes at room temperature and is heated in 3 hours to reflux temperature (55 to 95 ° C). The mixture is then stirred at reflux for an additional 1.75 hours. Approximately 275 g of hydrochloric acid and low-boiling organic products are expelled during the reaction time. The suspension of the dark brown reaction is then filtered off, the product obtained is intensively washed with a mixture of methylal and methanol, then with methanol, and then with deionized water. 680 g of polymer in pearls moistened with water, chloromethyl is obtained. Chlorine content: 18.8%. In this case about 8 to 10 g of oligomers per 1000 g of polymer with an excess in methanol were precipitated from the filtrate of the reaction mixture. In this case 100 ml of the wetted chloromethylate of the nutcha weigh 65.9 g. These contain 12.45 g of chlorine corresponding to 0.351 mol. d) Obtaining a strongly basic ion exchanger. 803 ml of deionized water are placed in the autoclave. In these, 19.4 g of sodium chloride are dissolved. 430 ml of chloromethylated pearl polymer, moistened with nutcha (with water) is added, which corresponds to 283.4 g of polymer in dry, chloromethylated beads with a chlorine content of 18.8% by weight) and 276.6 g of 40.4% by weight aqueous trimethylamine solution. The suspension is heated in 1.5 hours to 70 ° C, stirred for another 2 hours at 70 ° C, heated to 80 ° C in one hour and heated for another 2 hours at 80 ° C. After cooling to room temperature, the mother liquors are filtered off by suction, the resin is combined with 800 ml of deionized water and stirred for 30 minutes at room temperature. The water is separated and replaced by 2000 ml of 3% by weight aqueous hydrochloric acid solution. The suspension is stirred for 4 hours at 70 ° C. After cooling, the liquid is separated, the resin is collected with water and eluted in a column, from the bottom, with 6 volumes of the bed of deionized water. 1208 ml of anion exchanger beads are obtained in the chloride form.

Both immediately after obtaining and also after the test to the swelling stability there is a greater number of perfect beads than in the comparative example.

Example 3 (according to the invention). b) Obtaining a strongly basic ion exchanger. 1013 ml of deionized water are placed in the autoclave. In it, 40.5 g of sodium chloride are placed. 450 ml of polymer are added to chloromethylated beads, moistened with the nutcha (with water) from example 2c (corresponding to 296.6 g of polymer in dry, chloromethylated beads with a chlorine content of 18.8% by weight and 176 g of dimethylaminoethanol.The suspension is heated in 3 hours at 110 ° C and stirred for another 3 hours at 110 ° C. After cooling to room temperature, the mother liquor is filtered off by suction, the resin is combined with 800 ml of deionized water and stirred for 30 minutes at room temperature The water is separated and replaced by 1254 ml of 3% by weight aqueous hydrochloric acid The suspension is stirred for 4 hours at 70 ° C. After cooling the liquid is separated, the resin is collected with water and diluted in a column from the bottom with 6 bed volumes of deionized water, 1,240 ml of anion exchanger beads are obtained in the chloride form.

Both immediately after the preparation and also after the test of the swelling stability there is a greater number of perfect beads than in the comparative example.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property:

Claims (5)

R E I V I N D I C A C I O N S

1. Process for obtaining monodispersed anion exchangers, in gel form, with high stability and purity by a) formation of a seed polymer suspension in a continuous aqueous phase, b) swelling of the seed polymer in a constituted monomer mixture by vinylmonomers, crosslinkers and initiators by means of radicals, c) polymerization of the mixture, of monomers in the seed polymer, d) functionalized of the copolymer formed by chloromethylation and amination, characterized in that the seed polymer is a crosslinked polymer with an index of swelling from 2.5 to 7.5 and with a content in non-evaporable, soluble parts, less than 1% by weight.

2. Process for obtaining monodispersed anion exchangers, in gel form, according to claim 1, characterized in that the seeding polymer is a crosslinked polymer, prepared from i) 96.5 to 99.0% by weight of monomer, ii) 0.8 to 2.5% by weight of crosslinker and iii) 0.2 to 1.0% by weight of aliphatic peroxyester as the polymerization initiator.

3. Process for obtaining anion exchangers, in gel form, according to claim 2, characterized in that the aliphatic peroxyester corresponds to formulas I, II or III Formula I Formula II Formula III where R 1 is an alkyl radical having 2 to 20 carbon atoms or a cycloalkyl radical with up to 20 carbon atoms, R 2 represents a branched alkyl radical with 4 to 12 carbon atoms and L is an alkyl radical with 2 to 20 carbon atoms or a cycloalkyl moiety with up to 20 carbon atoms.

4. Process for obtaining monodispersed anion exchangers, in gel form, according to claim 1, characterized in that the seed polymer is microencapsulated. Method according to claim 1, characterized in that the amination is carried out in the presence of a proportion of less than 5% by weight, based on the total amount of water, of an inorganic salt.