DE2805121C2 - Process for the preparation of ion exchange resin beads - Google Patents

Description

The invention relates to a process for the production of copolymer beads, used as ion exchange polymer beads with improved phy are suitable for physical properties.

The Methods for Making Crosslinked Vinyl Copolymers in spherical form (as a precursor for ion exchange resins) a free radical catalyzed polymerization of the mono Mixture in aqueous dispersion are known. The term "cross-linked vinyl copolymer" becomes simplistic used and refers to copolymers with a larger Share, d. H. 50 to 99.5 mol%, and usually 80 to 99 mol%, a monoethylenically unsaturated aromatic monomer, for example, styrene, vinyltoluene, vinylnapthalene, ethylvinyl benzene, vinylchlorobenzene or chloromethylstyrene, and a smaller proportion, d. H. 0.5 to 50 mol%, and preferably 1 to 20 mol%, of a polyäthylenisch unsaturated monomer with at least two active ethylenically unsaturated groups, the with the above-mentioned monounsaturated monomer under Formation of a crosslinked, insoluble and infusible copoly mers is polymerizable. Examples are: divinylbenzene, tri methylolpropane trimethacrylate, ethylene glycol dimethacrylate, Divinyltoluene, trivinylbenzene, divinylchlorobenzene, diallyl phthalate, divinylpyridine, divinyltoluene, divinylnaphthalene, Ethylene glycol diacrylate, neopentyl glycol dimethacrylate, Diethy glycol divinyl ether, bisphenol A dimethacrylate, pentaerythritol tetra- and trimethacrylate, divinylxylene, divinylethylbenzene, Divinyl sulfone, divinyl ketone, divinyl sulfide, allyl acrylate, dial lylmaleate, diallyl fumarate, diallyl succinate, diallyl carbonate, Diallyl malonate, diallyl oxalate, diallyl adipate, diallyl sebacate, Divinyl sebacate, diallyl tartrate, diallyl silicate, triallyl tri carballyate, triallylaconitate, triallyl citrate, triallyl phosphate, N, N'-methylenediacrylamide, N, N'-methylenedimethacrylamide, N, N'- Ethylene diacrylamide, trivinylnaphthene, polyvinylanthracenes, and the like  the polyallyl polyvinyl ethers of glycol, glycerol, pentaerythritol, Resorcinol and the monothio and dithio derivatives of glycols. The copolymer may also be polymerized up to about 5 mole percent Units of non-aromatic ethylenically unsaturated vinyl mono Merer of a kind that does not adversely affect the Basic nature of the resin matrix influences, for example acrylonitrile, Methyl acrylate and butadiene.

Conventional polymerization conditions lead to crosslinked Vinyl copolymers, which in the conversion into the Ionenaustau scherharze by attaching functional groups due a physical weakness with certain disadvantages in her Use tainted.

The invention can be used to ion exchange resins to deliver, wherein the polymer beads have a high mechanical Fe strength and resistance to swelling pressures within a bead during the acid / Base cycle occur, d. H. that they have a resilience to have an osmotic shock. A higher mecha The niche strength of beads is improved Resistance to a physical combination to recognize break as a result of external forces acting for example, the weight of the resin column bed, strong Flüs flow and backwash. Therefore, the inventions Physically solid ion exchange resins prepared according to the invention suitable for the treatment of liquid flows with high flow speeds, for example when cleaning condenses where lower quality resins have become mechani tend to collapse and have a short life.

During the preparation of crosslinked vinyl polymers known as Basic matrix copolymer used for the ion exchange resins oxygen is excluded in a conventional manner, because oxygen is a safety hazard and in general my disadvantageous with respect to the properties of the polymer is considered that by a running for free radicals Po lymerisation is obtained.  

According to the invention, the vinyl monomer, the crosslinking Mo monomers and optionally other monomers in an aqueous Dispersion in the presence of a free radical generating Ini polymerized, namely (1) in contact with a Oxygen-containing gas or (2) using a Monomer mixture that has been previously oxygenated or (3) in compliance with measures (1) and (2), preferably at a reaction temperature of 30 to 95 ° C and in particular 50 to 70 ° C is worked. To the verb tion of the absorption of oxygen by the monomer mixture it is generally preferable, something lower To comply with polymerization temperatures, for example Tempe temperatures that are 5 to 25 ° C below the temperatures, as normally used to carry out suspension polymer tion process for the production of similar products be. Therefore, there is the free used in the process according to the invention Radicals initiator preferably from such Ini tiator, which catalyzes the polymerization of these Temperatures is suitable. Mention should be made, for example, of (4-tert-butylcyclohexyl) peroxydicarbonate, dicyclohexyl peroxydicarbonate, di- (sec-butyl) -peroxydicarbonate, di (2- ethylhexyl) peroxydicarbonate, dibenzyl peroxydicarbonate, diiso propyl peroxydicarbonate, azobis (isobutyronitrile), azobis (2,4- dimethylvaleronitrile), tert-butyl peroxypivalate, lauroyl peroxide, Benzoyl peroxide, tert-butyl peroctoate and tert-butyl peroxy isobutyrate. The amount of initiator used is normal usually between 0.1 and 2%, based on the monomer weight, and preferably varies between 0.3 and 1%. Become Catalysts used at relatively low tempera acids, such as 30 to 60 ° C, are used, then it may be advantageous to use a second, so-called "Cha ser-catalyst "to be used at higher temperatures is active to higher yields of cross-linked vinyl polymer to obtain. For example, about 0.05 to 0.1%, based on the monomer weight of such initiators, such as Benzoyl peroxide, tert-butyl peroctoate or tert-butyl peroxy isobutyrate.  

As mentioned above, Ver suggest that oxygen through the monomer mixture little is absorbed until the polymerization until the Gel point has reached, d. H. the point at which an unbe bordered polymer network has been formed (see, for example Wise Fundamental Principles of Polymerization by G. F. D'Alelio, Johne Wiley & Sons, Inc., 1952, page 93). Known Methods using gaseous reactants in Polymerisa tion systems can be used to introduce oxygen into the Monomermischung be used. For example, the Space above the reaction medium with a gaseous acid be rinsed before the Initiation of the reaction by raising the temperature to what a corresponding O₂ / N₂ mixture through the room during the Rinsing reaction period. The gaseous mixture can contain up to 20% by volume of oxygen, for safety green However, they can under conditions prone to explosion lower levels are required, depending on the ex plosive range of mixtures from each used Vinyl monomers or the vinyl monomers with oxygen in the Vapor phase. For example, less than 9% by volume Oxygen in the case of a mixture of styrene and divinylbenzene be required. Because the absorption of oxygen by the monomer droplets not only from the temperature and the Partial pressure of oxygen in the gas in the room depends but also from the surface of the reaction medium, which is the Space is exposed determines the design of the vessel, whether it is advantageous under atmospheric pressure or under he to work under high pressure, for example under pressure of up to 5 or more atmospheres, as larger prints do require greater oxygen absorption. Another method for introducing oxygen into the monomer mixture therein introducing the gaseous mixture into the monomer mixture before and / or to bead during the polymerization.

The aqueous medium in which the polymerization in dispersions Form usually contains smaller amounts the conventional suspension additives, d. H. dispersants,  such as xanthan gum (biosynthetic polysaccharide), poly (diallyl dimethylammonium chloride), polyacrylic acid (and salts), poly acrylamide, magnesium silicate and hydrolyzed polymer styrene and maleic anhydride, protective colloids, such as carboxymethylcellulose, hydroxyalkylcellulose, methylcellu loose, polyvinyl alcohol, gelatin and alginates, buffering aid medium, such as phosphate and borate salts and the pH-controlling Chemicals, such as sodium hydroxide and sodium carbonate.

The crosslinked high molecular weight copolymers can from the reactor in the form of hard discrete beads with Particle sizes of 0.02 to 2 mm are obtained, the average particle size usually between 0.2 and 1 mm lies. These copolymers may be functionalized by known methods are converted into ion exchange resins, of the candidate functional groups sulfone amide, trialkylamino, tetralaklyammonium, carboxyl, carboxy lat, sulfonic, sulfonate, hydroxyalkylammonium, iminidiace tat, amine oxide, phosphonate or other known groups he I think. The functionalization reactions involving vinyl aromatic copolymers for the production of ion exchangers resins can be carried out, for example by sulfonation using concentrated sulfur hydrochloric acid, a chlorosulfonation using chlorosulfone acid and subsequent amination, a reaction with sulforyl chloride or thionyl chloride and subsequent amination or explain a chloromethylation and subsequent amination. The ion exchange resins can be divided into the following types len: types with strong acid cations, d. H. Types, which the Sulfonic acid group (-SO₃H) or sulfonate group (-SO₃M, wherein M usually represents an alkali metal ion); resins with weakly acidic cations, d. H. Resins which are the carboxyl group (-CO₂H) or carboxylate group (-CO₂M, where M is used Lich represents an alkali metal ion), contain; Resins with strong basic anions, d. H. Resins containing the tetraalkylammonium group-NR₃X, wherein R is alkyl or hydroxyalkyl and X usually chloride or hydroxide; Resins with weakly basic anions, d. H. Resins containing a trialkylamino  group NR₂ contain, wherein R is an alkyl or hydroxy alkyl group.

The properties of the copolymers prepared according to the invention can be determined by their characteristics in thermal analysis as well as swelling with solvents and during the conversion in ion exchange resins by linking with the above determine the functional groups mentioned. The increased physika The strength of these resins is based on their resistance from being crushed, which is intrinsic traditionally using the Chatillon-In measured. You can also do a visual sub before or after use for ion exchange purposes make. For example, strongly acidic styrene type resins often Chatillon values of 900 to 5000 g force per bead and preferably 1200 to 5000 g per bead, in the Unlike resins that are based on copolymers that after conventional polymerization methods are produced where in these resins usually Chatillon values of 50 to 550 g / Show beads. In a similar way can be styrene type produce anion resins according to the present invention, the Cha tillon values of 500 to 2500 and in particular 600 to 2500 and, specifically, show 900 to 1500, and that in contrast to resins based on copolymers, the be prepared according to previously known methods, in typi Scher manner own Chatillon values from 25 to 400.

The gel ion exchange resins prepared according to the invention, in particular the most commercially used resins made from aro matic copolymers can be easily generated by the known resins due to one or more different different physical parameters, the following (1) the presence of intact globules (less cracked or broken globules), (2) the Crumbling of the resin (Chatillon test), (3) the resistance ability to break after repeated cycles from exhaustion and regeneration (microcycling test) and (4)  the birefringence patterns of the beads. Test methods as well Observational methods to identify these discriminating Features are explained below.

In some cases, known resins have been carried out one or more of the tests (1) to (3) a high physika but they did not succeed in all meet three criteria. In the case of cationic resins point about 75 to 90% of the resins used commercially , average levels of crosslinking agent, d. H. un 4% to 12% by weight and usually 7% to 10% Ver wetting agent (preferably divinylbenzene, DVB). Under Be Consideration of commercial considerations is conventional anionic resins which contain relatively small amounts of Ver containing networking agent, d. H. about 1 to 10 wt .-% and usually 2 to 5% of crosslinking agents. Produced according to the invention Products with the described physical properties can be produced with all cross-linking agent contents, however, mention is made of only the most conventional types the. The differences between the birefringence patterns of Resins prepared according to the invention and similar known resins are less at lower crosslinker content imprints, since in these cases a residual internal stress of under is ordered order. Nevertheless, the improvement can be Recognize the new resins with known resins of the same type (and same Vernetzungsmittelgehalts) in ent neither a relaxed or artificially tense state (for example in swelling solvents).

The number of intact beads is determined as follows:

The determination is made microscopically after a functionalization of the copolymer, for example by sulfonation or chloromethylation and amination of the copolymer. Intact beads are those that have no visible cracks, ie beads having a perfectly spherical shape with no cracks, fragments, holes or surface defects. Inven tion products contain at least 90% or more intak te beads, typically 93 to 99% intact beads, as can be determined visually and by counting. Known resins typically contain about 40 to 99% intak te beads. Many types of commercially available resins contain only 40 to 50% intact globules (see, for example, the following explained Fig. II, C and D).

The acid / base cycle test (microcycling test) is as follows carried out:

The microcycling test serves to accelerate accelerated loading conditions under which the resin is used. The examinations will be done during a period of few Days and not for a period of months or years as they are characteristic for operating conditions, carried out. Repeated exhaustion and regeneration cycle len are using the resins in a predetermined time span NEN in a fully automated device durchge leads.

From the resin to be tested, a -20 + 30 US mesh fraction is taken and under a microscope to determine the appearance of the Microcycling test examines: There are four different Fields of single-layered beads observed and the average result of each field as follows averages:

• (a)% intact globules
• (b) Cracked beads
• (c)% fragmented / broken globules

A small portion of the sieved resin (0.5 ml) is placed in a Filter tube made of sintered glass filled in such a way that a Single layer of beads is formed in the tube. These small amount of resin beads ensures good con clock between solution and resin and a complete conversion of the resin during each stage. The exhaustion and Regeneration deployed solutions are previously manufactured and stored in 50 l tanks. The solutions for the anion and  Cation resins are used are described below ben:

During a typical experiment, about 200 ml the depletion solution dropwise the resin sample during a period of 10 minutes, after which the main amount of fatigue agent removed by gentle vacuum becomes. Then it is rinsed with deionized water, whereupon again a slight vacuum is applied. Subsequently, will dropwise the regeneration solution during a time 10 minutes, after which the distance the bulk of the regenerant by light Va followed by cooling and rinsing with water. The termination of this Process represents a cycle of exhaustion and regeneration and takes about 30 minutes. A complete automa allows to carry out 100 cycles in un about 48 hours. After completion of 100 cycles that will Resin removed and examined microscopically for its appearance. The reduction of the percentage of intact globules becomes referred to as "collapse".

The products according to the invention give after 100 cycles of Microcycling tests have a value of lessening the intact Globules of less than 30% and usually no more than 15%. The cationic resins show a lower value of Reduction of the intact globules of not more than 10% and usually at most 5%. Anionic resins show values of up to 30%, normally not more than 15%. In contrast, who in the case of known cation resins, values of 15 to 80% and most typically between 30 and 50%. Many known anionic resins show values of 15 to 80% 100 cycles, with values from 15 to 50 being most typical.  

The Chatillon test will be used to determine the resin crumbling carried out as follows:

The term "chatillon test" is referring to a device too John Chatillon and Sons, New York, N.Y. is prepared and intended to the Harzbröckeligkeit to eat. The device (Model LTCM, Gauge DPP-2.5 kg) measures the Force in grams, which is required to use a resin bead to rupture or break if it is between two parallel plates is located. The plates are getting slow with a steady speed as long as each other closed until the "break point" of the resin is reached. The The purpose of this test is to reduce the friction and pressure To simulate that on individual resin beads under the actual operating conditions. The test will be in individual carried out in such a way that the resin in the ent meaningful form (hydrogen or sodium form in the case of ge tested cation resins and chloride form in the case of the tested th anionic resins) converted by known standard methods becomes. The converted resin is then used to obtain a -20 Sieved +30 US mesh fraction, followed by deionized Water for a period of at least 15 minutes before completely hydrate the test. The testing is done using a single resin bead (that of a small drop of water is covered) in the Chatillon instrument, the lowest most suitable speed being the Crushing plate is set. The single ones Fragmentation forces are applied to the instrument in grams per Globules displayed. The results are considered average (Minimum 20 beads, typically 30 beads), where one standard deviation and 95% reliability interval is assumed. The percentage of beads that It will become a minimum friability standard averages.

The birefringence test is carried out as follows:  

The birefringence test is an analyti test, which identifies manufactured according to the invention Gel resins relieved and a distinction from the known th corresponding resins allows. Achieving the dop The pelbrechungsmuster takes place using an optical Microscope (for example a Carl Zeiss photomicroscope), that at a low magnification (for example 34x) set to a bright field lighting. polarized Lenses are inserted above and below the stage sets and arranged perpendicular to each other. A piece of mattier The glass is attached to the stage to create a diffused surface Illumination of the samples to effect. About 30 to 50 globules The resin sample to be analyzed is then placed in the concave Inserted recess of a microscope slide. The Recess is filled with water and then with a large Cover glass covered. The object made in this way Carrier is placed on the frosted glass lying on the ob jekttisch is fixed, the focus adjusted in such a way that will give an optimal picture of the outer edge of the globules is possible. To record the birefringence pattern is made a photomicrograph.

Observations of a large number of double calculation patterns of ion exchange resin samples produced in accordance with this invention how to compare these samples with patterns of the commercially available resins have clear differences between give the patterns. Both the cation and the Anionic resins differ from the corresponding ones resins, but on a slightly different basis, so that the cation and anion resins described separately who the.

cation resins

The use of birefringence stress patterns to identify the stresses in cationic resins is not new in the field of ion exchangers (see, for example, RM Wheaten et al., Industrial and Engineering Chemistry, Vol 44, No. 8, August 1952, pages 1796 to 1800). A number of characteristic patterns have now been identified and empirically reconciled with the physical properties of the resin, including residual stress remaining in the beads, to establish qualitative identification of the resin origin and resin properties. A high internal stress in the resin beads directly corresponds to a low physical stability. The low stress cation resins of the present invention are illustrated by the patterns AD in Figure 1 of the accompanying drawings, while some of the different types of harders currently available are shown by the patterns AD in Figure 2 of the accompanying drawings. The photographs showing the birefringence patterns were taken at substantially the same exposure time and sample illumination.

The patterns representing the high tension products (which are therefore more susceptible to breakage or breakage) can be identified by the gloss and sharpness of the pattern as well as the pattern type. Figure 2 shows spheres under higher strain and thus a sharper and brighter single globule pattern. It should be noted that this observation, as well as other observations, have been made taking into account the overall appearance of a sample, since individual beads in a batch or sample are different. It is also to be understood that some of the observed commercially available samples may be composites or physical mixtures formed under various conditions, therefore, the samples may reflect the sensitivity of product quality to variations in the manufacturing process.

Typically, the resin stress birefringence examine a Maltese cross or a modification of it festge represents, this appearance is an indication of a bullet  shaped symmetrical stress orientation gives. Each one Effect of physical stress on an ion exchanger Resin beads produces a pattern of tension, typically white a Maltese cross. This phenomenon can be observed if you have a relatively relaxed bead between parallel Plane compresses and tension through osmotic pressure, like when swelling a bead in a solvent, indu ed. The width and sharpness of the branches or arms of the Malte serene gives a qualitative (and sometimes quanti Refer to the voltage. Sharper and narrower branches indicate a higher voltage, especially if bright areas exist between the branches.

Considering the foregoing, the birefringence patterns of FIGS. 1 and 2 can be different from each other. The low voltage cationic nanoparticles represented by FIGS . 1, AD in the hydrogen form have at least one of three identi fi ed patterns, namely:

• (1) a broad Maltese cross surrounded by an extinction ring (dark ring) around the periphery of the beads (pattern dominating in Figures 1, A and B);
• (2) a broad Maltese cross surrounded by an extinction ring which is well within and separate from the periphery of the bead ( Figures 1, A, B and C, most observable in the lower half of C), and
• (3) an irregular pattern, sometimes similar to an arbitrarily oriented chain, sometimes seen as a twisted version of (2) ( Figure 1, patterns C and D, best observable in D).

Each of the patterns of Figs. 1, A to C having a Maltese cross are relatively dull and have broad and slightly swollen branches. The pattern of Fig. 1D is less clear and somewhat dull, and to a greater degree has arbitrary stress patterns, which is probably indicative of an arbitrary stress orientation. All of the patterns in FIG. 1 are atypical of known cationic gel resins, which are illustrated in FIG . All cation resins according to FIG. 1 were prepared from a styrene / divinylbenzene (8%) copolymer backbone using the process according to the invention, which is explained in more detail in the following examples. The material according to FIG. 1C is a composite of three samples produced in the laboratory. All were sulfonated to produce strong acid resins.

Typical stress birefringence patterns of known gel resins are illustrated in FIG. 2, A to D. FIG . These patterns have at least one of three identifying criteria:

• (a) A square on a Maltese cross (see Fig. 2A);
• (b) a sharp Maltese cross with narrow branches and bright spots between the branches, optionally with an outer extinction ring (see Fig. 2, C and some beads in B) and
• (c) an irregular pattern sometimes resembling a twisted cross (or swastika), and sometimes a square on a cross similar to (a) ( Fig. 2, D).

The pattern in Figure 2, B represents a sample of a known relatively high quality styrene / DVB gel resin containing about 8% DVB in the copolymer backbone (sample taken from the manufacturer during a regular production operation). The pattern in Fig. 2C represents a sample of a known relatively poor quality styrene / DVB gel resin containing about 8% DVB. The material has many surface defects as well as poor physical stability both when performing the micro cycling test and the Chatillon test (the sample was taken during the normal production run). An otherwise poor styrene / DBV resin having surface defects and bubbles and having poor physical stability is illustrated by Fig. 2D. It is a commercial product. The sample, using which the pattern of Fig. 2A has been obtained, is a well-known medium grade styrene / 8% DVB gel resin (normal commercial product). All resins which are erläu by Fig. 2, are strongly acidic and are present in the sulfonic acid form.

Although individual beads in a given pattern in FIG. 1 may have voltage patterns that are practically the same as the patterns in FIG. 2, the products are easily distinguishable. For example, a similarity may be found between some individual beads in Figs. 1A or B and Fig. 2B, but a significant number of beads are different from each other. The resins of Fig. 1 are clearly superior to the resins of Fig. 2 (even the best samples thereof) when performing the Chatillon test, as is the case with respect to intact bead count and accelerated use test (microcycling test) ,

On the basis of the above findings as well as on their investigations of stress birefringence patterns, without wishing to be bound by any particular theory, it can be postulated that differences in the patterns of the novel resins and known resins produced in accordance with the invention reflect different degrees of residual stress within the resin beads , However, the invention should not be dependent on any of the explained Theo rien. The patterns attributable to the novel resins represent conditions of low intrinsic stress, while those patterns attributable to the resins of Figure 2 AD give higher levels of intrinsic resin stress. Since the stress responsible for the birefringence pattern, which is believed to be residual stress within the beads, it seems logical that higher stress levels would correspond to poorer physical quality. Therefore, birefringence patterns provide a simple qualitative method for identifying and distinguishing the products of the invention.

Copolymer precursors for cation and anion resins can also of known copolymers based on the thermo analysis and the swelling properties in solvents be differentiated. Because these copolymers are improved resins condition, it can be seen that the copolymers are the known copolymers an improved composition have.

anion resins

Anionic exchange resins, which according to the improved invention be prepared according to copolymerization methods also from known anionic resins by stress Distinguish birefringence patterns with improved physical properties are in a relationship. in the In general, it has been found that the anionic resins are prin basically on the basis of differences in the intensity of the Birefringence patterns and not due to differences in the shape or nature of the pattern itself. Consequently, the experimental conditions as far as be standardized as possible. It must have a sample as Inten standard for a direct comparison the birefringence pattern from one day to the next is.

Usually it is preferable to use the microscope on the outer to focus on the edge of the beads. Certain factors like the intensity of the light source, radiation losses in the microscope, the position of the focusing lenses, the sensation he influence the film's quality and the exposure time Significantly, the overall intensity of the fixed image. at However, in a given microscope all these factors are in sufficiently reproduced, wherein in the presence of a Sample as intensity standard conditions from one day to the  others in a satisfactory manner so that a direct comparison can be made microphotographs is possible.

The microscope and the corresponding optical device conditions for recording birefringence patterns of anionic resins are the same as in the case of cationic resins. The source solvent in which the anionic resins were investigated, However, it was made of ethanol and not water as in the case the cation resins. Each anion resin was added in an oven 90 to 100 ° C during a period of about 4 hours in Vacuum dried, overnight in the equilibrium state placed under ambient conditions and then in ethanol dipped until the source equilibrium has been reached. All birefringence patterns of the investigated anionic resins WUR obtained using samples in the chloride form, in ethanol for a period of at least 7 Ta have been swollen.

All anionic resins, including resins, which are new produced according to the invention oxygen-moderated processes show patterns that are qualitatively as broad serkreuz can be described, whereby only in small Aus dimensions or no extinction ring on the circumference of the beads occurs. Compared to the known resins show the resins according to the invention, which are up to equilibrium in Ethanol swollen, patterns that are noticeably more intense (lighter) are. Intensity differences in water are difficult characterize riger.

In the accompanying drawings, Fig. 3, A to C illustrate the birefringence patterns of various samples of anion exchange resins prepared according to the invention at 34X magnification. Uniformity of pattern intensity and configuration is typical of anionic resins made in accordance with this invention. Figure 3, D illustrates a composite sample of a new resin (top of the photo / light) along with beads made in known manner (bottom of the photo / matt) with no oxygen added in the copolymerization.

Fig. 4, AD shows the birefringence patterns of known anion exchange resins, which have been testified by four different manufacturers. All photomicrographs of Figures 3 and 4 were made with the same exposure under the controlled conditions described above to allow comparisons of pattern intensities. Even the low intensity patterns of FIG. 4 form broad Maltese crosses, with few globules exhibiting strong stress patterns characteristic of the known cationic resins.

The dominant property of anionic resins does not seem the residual internal stress in the resin beads as in the case of To be cationic resins. The intensity of the wide Maltese cross birefringence pattern, however, corresponds directly and reproducibly bar of the physical stability of the resin. The lighter Mu esters serve as birefringence characterizations of most physically stable resins. While the dominant feature of cation resins as tension inside the globules postu it has been assumed that the greater swelling pressure, which is maintained in excellent anionic resins an indication of a larger elastic component in the networked network that allows the network to better an externally applied tension without crack adaptation or tearing. The more intense patterns of new resins swollen to equilibrium in ethanol an indication of a higher swelling pressure of the new resins.

Of course, it is possible that certain selected samples, which represent extreme ratios with respect to the pattern intensity in the case of new and known resins, are difficult to distinguish. Also, a given bead in a pattern may differ significantly from the overall pattern of a known sample. However, if data is collected for a significant number of products studied, then ambiguities in determining the quality of a particular product can be precluded by conducting multiple analyzes, preferably using different samples of the same product. In some cases, both in the case of known cation and anion resins, the overall patterns, which have wide variations in pattern and / or intensity, are indicative of the quality of the overall product and not the presence of both good and good globules with poor quality within a single sample. Thus, the birefringence patterns according to Figs. 4, B and D should be interpreted as characterizing a typical known product which has overall physical stability which is inferior to that of the products made in accordance with the invention. The patterns should not be interpreted as being both good (high gloss) and poor (low intensity) beads. The bright patterns for a few beads in these samples are an indication of a high In nenspannung, so that these beads are excluded from a comparison of Mu ster.

The need for different interpretations of the dop is pelbrechungsmuster with respect to cation and anion resins, it is believed to be a succession of different cation and Anionic resins of interior properties, being mainly Composition factors play a role, for example the uniformity of the cross-linking as well as the content of pri märem crosslinking agent. These factors cause differences the relative proportions of the swelling pressure and the residual stress to the total stress level in the cation resins used in Water are swollen, compared to the anionic resins, the swollen in ethanol. The importance of elasticity of the Backbone in the anionic resins became at least partial by thermomechanical analyzes (TMA) above the copolymer substantiated substantive, wherein a secondary stretch limit both in the case of cation and Anionencopolyme was discovered, according to the new invention Co  polymerization process have been prepared. Restspannun conditions seem to be less important in the case of anionic resins, there wide Maltese cross patterns, which are both typical of the Har ze according to the present invention as well as for the resins of Stan of the technique, no indication of high-globule Tension are.

It could be assumed that the elasticity is an important ge role regarding the physical stability of both Cation as well as anion resins plays, however, the Stability not independent in the case of cation resins cha characterized, their characteristic Hauptbrechungseigen different pattern types.

Reaction rate kinetic studies have one some change in crosslinking agent (DVB) reaction If a copolymerization in counter was carried out by oxygen, and in comparison to conventional methods, which justifies the assumption that homo the copolymer matrix according to the inventive method can be networked, which also improves Elastizi explained the nature of the resins.

All of the resins of Figures 3 and 4 contain low levels of crosslinking agents typically typified by the most commonly used styrene / divinylbenzene type anion exchange resins, with levels ranging from about 2 to about 5% crosslinking agent (DVB).

In the cationic resins ( Figures 1 and 2), in the case of about 75 to 90% of the resins used commercially, the average levels of crosslinking agent are between 7 and 10% (which is usually divinylbenzene, DVB). The most widely used anionic resins for commercial reasons are those containing relatively low levels of crosslinking agent, ie, amounts of about 2 to 5%. The improved products according to the invention are obtained in all Ver netzungsmittelgehalten, but in the case of the examples shown, the amounts used in a conventional manner are used. The differences between the cationic resins and similar known resins prepared according to the invention can be less pronounced at lower crosslinking agent contents, in which an internal residual stress of the resin is of secondary importance. Nevertheless, an improvement can be seen by comparing the novel resins prepared according to the invention with the known resins of the same type (and crosslinking agent content) either in a relaxed or artificially stressed state (for example, in swelling solvents). The following examples show some preferred embodiments of the invention.

Example 1 polymerization

It is used as a polymerization reactor, a 2-liter 3-neck round bottom flask used with a two-bladed paddle stirrer, Thermo meter, cooler, heating jacket with temperature control device and means for introducing a mixture of acid fabric and nitrogen and a shield is provided. because at, the oxygen concentration in the gas flow is through Gas-liquid chromatography and in the monomer mixture monitored by a Beckman oxygen analyzer.

An initiator-containing monomer phase is added to the reactor guided. The headspace is filled with a suitable gas mixture (For example, 2% by volume of oxygen in nitrogen) as long rinsed until at 25 ° C, an equilibrium state has. Then the aqueous phase is added and the Rüh at 210 rpm to produce monomer droplets in one aqueous dispersion turned on, while the gas purge on will be maintained. The following is a representative poly merisationsreaktionsmaterialcharge listed, the ange quantities in grams are to be understood.

styrene 489.4 Divinylbenzene (54.7% concentration) 85.3 methyl acrylate 8.8 "Percadox-16" initiator (di (4-tert-butylcyclohexyl) peroxydicarbonate) 2.04 water 510.3 "Padmac A" as a dispersant poly (diallyldimethylammonium chloride) 20.1 "Pharmagel" as protective colloid (gelatin) 1.6 boric acid 0.88 sodium nitrate 0.59 Sodium hydroxide solution (50% concentration) added to set a pH of 10 to 10.5

The oxygen-nitrogen gas purging is at 140 cc / min the dispersion passed while these from 25 to 57 ° C in 45 Mi is heated. Then the reaction mixture is at 57 ± 2 ° C held for a period of 7 hours. The Char ge then to 75 ° C for a period of 30 minutes heated to 75 ° C over a period of 1 hour hold. The copolymer beads are washed, whereupon schüssiges water by vacuum filtration using a Büchner funnel is removed.

Sulfonation of the copolymer

Part of the wet polymer beads used in the above have been prepared (110 g), becomes 600 g of a 95% H₂SO₄ in a 1-liter flask, the with a stirrer, condenser, dropping funnel, thermometer, alkali scrubber and a heater is provided. 30 g of ethylene dichloride (swelling agent for the beads) are added followed by the suspension from 30 to 120 ° C for a period of time heated for 3 hours. Then a hydration closes when carrying it out water to quench the Pro is added. The polymer beads are in a Transferred backwash tower and back to remove residual acid washed. The resulting ion exchange resin product records  characterized by the following properties:

Whole Beads | 99% Cracked beads 2% Fragmented beads 1% Intact globules 97% Friability: Chatillon value, g / beads 2139 Solids, H⁺-form 44.7% Solids, Na⁺-form 51.5% Salt splitting cation capacity mEq / g, dry 5.21

Examples 2 to 4 and Comparative Tests A and B

There are further crosslinked styrene copolymers in the above prepared manner, wherein the oxygenates tion in the reactor headspace is varied. Then ei takes place ne sulfonation in the manner described, wherein Ionenaustau scherharze be obtained. The properties of these resins are vergli with commercially available sulfonated resins which are obtained from copolymers which are free of oxygen added during the polymerization have been prepared. In Table I, the resins prepared according to the invention are labeled A, B and C denotes.

Table I

Examples 5 to 7 and comparative tests C and D

Further crosslinked styrene copolymers are prepared according to Example 1 prepared, but instead of the sulfonation of a chlorine methylation and amination in a conventional manner under Bil strong base anion exchange resins is carried out, their properties with commercially available resins with the be compared to the same functional groups derived from Co polymers are prepared which without oxygen during the polymerization are generated. In Table II the resins prepared according to the invention denoted by D, E and F.  

Examples 8 to 21

Using the polymerization described in Example 1 method further copolymers are prepared. They will be on closing to the production of strongly acidic cation and strong base functionalized with anionic resins. Using the in Example 1 reaction vessel is a monomer charge (hereinafter referred to as "A") and an Ini tiator supplied to the reactor, wherein either the mono only previously saturated with oxygen or the reactor head space with an oxygen-containing gas, for example 8 Vo lumen-% O₂ in nitrogen while purging until a match weight at 25 ° C (typically 30 minutes). The aqueous phase, hereinafter referred to as "B", is then fed (weight ratio of the monomer to the aqueous phase = 1.1: 1.0), whereupon the stirrer at 210 rpm is set in motion. In this case, monomer droplets in aq ger dispersion generated. If an oxygen-nitrogen gas pur used, then this is about the dispersion with a Speed of 140 cc / minute during the rest of the reac headed. Optionally, a pressure of 0.35 to 1.05 kg / cm² complied with the gas.

The following are representative reaction material charges in Parts by weight are given per 100 parts of each solution.

Solution A (monomer phase) (a) styrene 83.6 (b) divinylbenzene (54.7% concentration) 14.6 (8.0 active) (c) methyl acrylate 1.5 (d) di (4-tert-butylcyclohexyl) peroxydicarbonate: percadox-16 (initiator) 0.35 (e) tert-butyl peroctoate (chaser) -

Solution B (aqueous phase) (a) water 95.3 (b) Poly (tetraalkylammonium chloride) (dispersing agent) 3.75 (c) gelatin (protective colloid) 0.30 (d) boric acid 0.16 (e) sodium nitrate 0.11 (f) Sodium hydroxide solution (50% concentration) added to adjust the pH from 10.5 to 11.0 0.2-0.4

The reaction mixture is heated from 25 to 57 ° C in 45 minutes heated and to 57 ± 2 ° C for a period of 7 hours held. The batch is then brought to 75 ° C for a while heated for 30 minutes and at 75 ° C for a while span of 1 hour (Chase stage). Will a Coinitia tor used as a chaser, for example, tert-butyl peroctoate (tBP), then the batch is at 95 ° C for a period of time heated for 30 minutes and at 95 ° C for a period of time of 1 hour (endchase stage). The batch will be then cooled, whereupon the copolymer beads are washed. Excess water is removed by vacuum filtration under Ver away from a Büchner funnel. The specific ones Reaction conditions and the end product properties of obtained styrene / DVB resins are shown in Table III, in which the crosslinker content as% "active" crosslink ingredient is indicated. The other monomer components of the commercially available crosslinking agent (mainly ethylvinylbenzene) are considered parts of the mono calculated vinyl monomers. The application specified Ver Network content is also calculated on an "active" basis. Furthermore, all ion exchange resin test values are full constantly functionalized copolymers, d. H. Resins with high Capacity and reasonable technical quality.  

Another method (macroporous resins), the above Polymerization is similar.

Macroreticular copolymers are prepared and used for production functionalized by strongly acidic cation exchange resins. The adhered polymerization process is in contrast to the oxygen treatment process according to the invention carried out known methods.

example 22

The monomer phase consists of

Styrene | 387 g divinylbenzene 97.4 g Methyl isobutyl 215.6 g Percadox - 16 2.18 g tert-butyl peroctoate 0.49 g

The aqueous phase consists of

Water | 770 g gelatin 3.0 g boric acid 3.17 g Padmac A 27.9 g sodium chloride 23.1 g

example 23

The monomer phase consists of

Styrene | 369 g divinylbenzene 92.9 g Methyl isobutyl 238 g Percadox - 16 2.08 g tert-butyl peroctoate 0.51 g

The aqueous phase consists of

Water | 734 g gelatin 2.24 g boric acid 3.17 g Padmac A 40.0 g

After completion of the copolymerization while maintaining the conditions mentioned above, the Copolymerisationsmi slowly to 100 ° C to remove methyl isobutyl carbinol heated. The copolymer beads are then removed before Sulfonation washed and dried.

sulfonation

According to the Sul The two methods are described above are also sulfonated. Dried copolymer (100 g) is added to 98% H₂SO₄ (615 g) added, followed by the addition of 35 g of ethylene dichloride closes. The chlorinated mixture is heated to 120 ° C in 65 minutes heated and at 122 ° C for a period of 1 hour held. Then follows a hydration, in which Water is added to quench the product. The abge frightened product is with 80 g of a 50% NaOH for conversion treated treatment in the sodium salt.

Macroreticular strongly acidic cation exchange resins

Claims (7)

1. A process for the preparation of hard, crosslinked copolymer beads with high mechanical strength, characterized in that a free radical polymerization in an aqueous dispersion of a monomer mixture of at least 50 wt .-% monoethylenically unsaturated aromatic monomer and less than 50 wt .-% on polyethylenically unsaturated crosslinked monomers having at least two active ethylenically unsaturated groups, wherein the polymerization is carried out at a temperature of 30 to 95 ° C and oxygen is in contact with the monomer mixture and / or dissolved therein until the polymerization at least the Gel point has reached. 2. The method according to claim 1, characterized in that a reaction temperature of 50 to 70 ° C is maintained. 3. The method according to claim 1 or 2, characterized that as the aromatic monomer styrene and as crosslinking monomer divinylbenzene is used. 4. The method according to any one of claims 1 to 3, characterized characterized in that the monomer mixture used with Air is saturated before the start of the polymerization.   5. The method according to claim 4, characterized in that an oxygen-containing gas in contact with the Monomer mixture passed through during the polymerization is, the gas less than 9 vol .-% oxygen contains. 6. The method according to any one of claims 1 to 5, characterized characterized in that the monomer mixture additionally up to 5 wt .-% of other polymerizable non-aromatic Containing monomers. 7. The method according to any one of claims 1 to 6, characterized characterized in that in an additional stage in the polymer anionic or cationic functional Introduces exchanger groups.