DE1094984B - Process for the sulphonation of a benzoluble, thermoplastic, alkenyl aromatic resin - Google Patents

Description

GERMAN

The invention relates to a process for the sulfonation of a benzene-soluble, thermoplastic, alkenyl aromatic Resin, preferably of polystyrene, polyvinyltoluene or a copolymer of styrene and vinyl toluene, in which the resin is treated with a solution of sulfur trioxide in a liquid solvent brings into contact that of sulfur dioxide or a mixture of a larger proportion by weight of sulfur dioxide and a smaller proportion at least one polychlorinated aliphatic hydrocarbon, such as methylene chloride, carbon tetrachloride, 1,1,1-trichloroethane, tetrachlorethylene or ethylene dioxide exists.

This process according to the invention is characterized in that a sulfur trioxide solution is used used to make the heavy metal ions beforehand by passing the solution through a bed of an alkali salt form a cation exchange resin that has sulfonic acid or carboxyl groups as functional groups contains have been removed.

When carrying out the process according to the invention, a cation exchange resin is preferred insoluble, resinous, sulfonated copolymer made from a predominant proportion of styrene and a smaller proportion of ethylene vinylbenzene and divinylbenzene are used.

Sulfonated alkenyl aromatic resins and processes for their preparation are known. One of these The method consists in using a sulfonating agent, z. B. sulfuric acid, chlorosulfonic acid or an ether complex of sulfur trioxide, with one Polymer of an alkenyl aromatic compound, which in a liquid chlorinated aliphatic Hydrocarbon solvent is dissolved, reacts at a temperature lying between -10 and 60 ° C.

In carrying out the sulfonation of an alkenyl aromatic resin, e.g. B. of polystyrene, Polyvinyl toluene or copolymers of styrene and vinyl toluene, it was found that the presence of ions of a heavy metal, especially iron or copper, in the solution of the reaction participating sulfur trioxide a decidedly catalytic effect in terms of increasing the Has a tendency to form crosslinks between the resin molecules. Bare traces of cations of the Metals iron or copper or their salts in the sulfur trioxide solution, as they are during the several hours Storage of a practically anhydrous solution of sulfur trioxide in one of the specified Solvent in an iron, copper, or steel vessel or with prolonged contact of the solution with the pipes or the like. Made of such metals before Mixing with a solution of the polymer

Process for sulfonation

of a benzene solids, thermoplastic,

alkenyl aromatic resin

Applicant:

The Dow Chemical Company,
Midland, me. (V. St. A.)

Representative: Dr.-Ing. H. Ruschke, Berlin-Friedenau,

and Dipl.-Ing. K. Grentzenberg,
Munich 27, Pienzenauer Str. 2, patent attorneys

Claimed priority:
V. St. v. America March 1, 1954

Jacob Eichhorn, Saginaw, Mich. (V. St. A.),
has been named as the inventor

are usually sufficient to make a substantial change in the properties of the sulfonated polymer compared to the properties of the product, which under otherwise identical conditions was produced in the absence of these heavy metal ions.

It has also been found that cations of heavy metals or salts of such heavy metals, e.g. B. from iron, copper or lead, from an anhydrous or practically anhydrous solution of sulfur trioxide in a non-aqueous solvent,

z. B. liquid SO ₂ or a liquid mixture of a major part of SO ₂ and a minor part of a polychlorinated aliphatic hydrocarbon, can be easily removed if the solution is brought into contact with a cation exchange resin in the alkali salt form.

If the cations of the metals iron or copper are removed from the solution in this way, it will run when mixing the solution of sulfur trioxide with a solution of a polymer one alkenyl aromatic compound in an anhydrous chlorinated aliphatic hydrocarbon or in sulfur dioxide the reaction between the sulfur trioxide and the polymer is rapid and smoothly forming a water-soluble sulfonated

009 678/538

Polymer without causing any noticeable crosslinking between the polymer molecules.

The formation of heavy metal ions in the sulfur trioxide solution appears to be mainly due to conversion of sulfur trioxide with the metal container or with lines or pipes made of these metals get. This reaction proceeds at ordinary temperatures under anhydrous or practically anhydrous conditions, d. H. relatively slow in the presence of only traces of water. In general arise through contact with a practically anhydrous solution of sulfur trioxide in liquid Sulfur dioxide with metals, e.g. B. iron, copper or stainless steel, in storage containers or pipes at room temperature or below in several, e.g. B. 2 to 5 hours or longer time iron or Copper ions in sufficient quantity so that a noticeable change in the properties of the sulfonated Polymer compared to the properties ao of a product made by reacting sulfur trioxide with a polyalkylene aromatic compound in the absence of metal ions, among other things the same reaction conditions is produced, occurs.

After removing the heavy metal cations from a solution of sulfur trioxide in liquid SO ₂ by bringing the practically anhydrous solution into contact with the alkali metal salt form of a cation exchange resin, the treated solution can be treated with metals, e.g. Iron or copper or stainless steel pipes, for a limited time, e.g. B. 30 minutes or less, remain in contact without a significant amount of ions of these metals going into the treated solution. Therefore, the treated sulfur trioxide solution via metal lines, e.g. B. iron or copper pipes, mixed with the polymer solution in a suitable reaction zone. The sulfonation can easily be carried out in a vessel made of iron, copper or stainless steel without the formation of crosslinks between the polymer molecules caused by heavy metal ions.

It has been found that the sulfonation described can easily be carried out so that one can regulate or control the degree of crosslinking in the sulfonated polymer. In addition becomes a solution of sulfur trioxide in liquid sulfur dioxide, preferably in one concentration from 0.5 to 5 percent by weight of sulfur trioxide, based on the weight of the solution, through a bed of Alkali salt form of a cation exchange resin passed, whereby the cations of the metals iron or Copper can be removed from the solution. After that, the solution in whole or in part by bed of a cation exchange resin in the iron or copper form, creating a certain amount Iron or copper ions are introduced into the solution of sulfur trioxide. The solution of sulfur trioxide is then polychlorinated with a solution of an alkenyl aromatic resin in a aliphatic hydrocarbon mixed and the sulfur trioxide with the resin to form a sulfonated one Resin product implemented. Following this process, the degree of crosslinking between the resin molecules can be increased easily by introducing a certain amount of iron or copper ions into the reaction mixture during sulfonation to produce a sulfonated resin product with the desired ones Viscosity properties are regulated.

Any cation exchange resin that has sulfonic acid or carboxyl groups can be used in the new process contains as functional groups. Examples of such exchange resins are the resinous ones Condensation products of phenol sulfonic acid or one of its salts with formaldehyde, sulfonated carbon or sulfonated benzene-insoluble vinyl aromatic resins, e.g. B. sulfonated copolymers of styrene and divinylbenzene or sulfonated copolymers of styrene, ethylvinylbenzene and divinylbenzene, or Cation exchange resins in the free acid form. Cation exchange resins are particularly preferred with sulfonate groups. They come in the form of an alkali salt, especially the sodium salt of the hydrogen form of the cation exchange resin, used to remove heavy metal ions. The cation exchange resin is usually applied in dry or practically dry form, although the resin also a limited amount of water, e.g. B. 10% by weight or less, contained in the resin granules can. The cation exchange resin is usually previously exposed to air at atmospheric pressure or reduced Pressure and dried at temperatures up to 125 ° C.

In the practical implementation z. B. a solution of 0.5 to 5 percent by weight sulfur trioxide in liquid sulfur dioxide or in a mixture of 50 to 99 percent by weight of sulfur dioxide and 50 to 1 percent by weight of a polychlorinated aliphatic hydrocarbon (methylene chloride, carbon tetrachloride, 1,1,1-trichloroethane, tetrachlorethylene or ethylene dichloride), which solution ions of heavy metals, e.g. B. of iron or copper, contains, passed through a bed of cation exchange resin in the alkali salt form, thereby removing the heavy metal ions sorbed by the resin and removed from the solution. The resin can be used in the usual way, z. B. by treating or washing with an aqueous sodium chloride, sodium sulfate or potassium chloride solution or by washing with dilute aqueous hydrochloric or sulfuric acid and then washing Washing with an aqueous solution of an alkali or a salt thereof and rinsing with water, can be converted back into the alkali salt form. The regenerated resin is dried and is then in a form in which there is the sorption of ions of heavy metals or cations their salts can be reused from another part of the solution.

The anhydrous solution of sulfur trioxide that has been treated to remove it from the ions of the Liberating heavy metals can be beneficial to carrying out the nuclear sulfonation of any benzene-soluble resinous or resin-forming polynuclear aromatic substances, e.g. B. of indene resins or alkenyl aromatic thermoplastic resins. The polynuclear to be sulfonated aromatic substance can have any molecular weight; it can be alkenyl aromatic Resins from dimers up to castable resins with molecular weights up to 500,000 or more are sulfonated with the treated solution to give water-soluble resin or To reach polymer sulfonates without any noticeable crosslinking between the polymer molecules entry.

It should be mentioned that the solution of the sulfur trioxide, which with the cation exchange resin for the purpose of removal which has been treated with metal ions can be used most advantageously to prevent the formation of

Cross-links between the polymer molecules when carrying out the core sulfonation of an alkenyl aromatic Resin having a molecular weight of at least 20,000 or above, preferably between 50,000 and 500,000, to be prevented or severely restricted. The cross-linking between the polymer molecules, caused by the ions of the metals iron or copper in the sulfur trioxide solution or the reaction mixture caused only a slight change in the properties of the sulfonated Polymer if the polymer used as starting material has a molecular weight of 20,000 or less.

In a preferred embodiment of the nuclear sulfonation described, the relevant Resin-like polynuclear substance in methylene chloride, carbon tetrachloride, 1,1,1-trichloroethane, tetrachlorethylene or ethylene dichloride dissolved to form a solution containing 0.5 to 5 percent by weight of the polymer contains. The solution is stirred and kept at a temperature between -20 and 40 ° C. You will get a solution of 0.5 to 5 percent by weight of sulfur trioxide in liquid while stirring Sulfur dioxide is added to remove heavy metal ions through a bed of cation exchange resin has been passed in the alkali salt form. The solution of the polymer and that of the Sulfur trioxide are usually mixed together in such proportions that the Reaction medium 20 to 80 percent by weight of sulfur dioxide and 80 to 20 percent by weight of a polychlorinated one contains aliphatic hydrocarbon. The addition is usually fairly quick; H. within 1 to 20, and usually 10 minutes or less. The reaction is at one pressure carried out, which is sufficient to get most of the solvent mixture liquid. When applied a reaction temperature of -1 ° C or below, the reaction can be carried out at atmospheric pressure be performed. But if you work at 10 to 40 ° C, a moderate pressure (up to 5.6 at) required to keep the solvent mixture liquid. In most cases, it is best to use the To carry out the reaction in a pressure vessel and at a pressure above atmospheric pressure.

The amount of sulfur trioxide to be used can vary within wide limits. You can use the sulfur trioxide z. B. apply in an amount which corresponds only to the amount theoretically required for the introduction of 0.1 sulfonate radicals per aromatic nucleus of the polymer used as the starting material. Usually, however, the SO _{3 is used} in an amount which is theoretically necessary for the introduction of at least 0.6 and preferably 0.6 to 1.1 sulfonic acid residues per aromatic nucleus of the polymer in order to obtain a water-soluble sulfonated polymer. The solvent mixture is expediently used in such an amount that the combined weight of the sulfur trioxide and the polymer used as starting material corresponds to 0.5 to 5 percent by weight of the total reaction mixture. Using the reactants and the solvent mixture in these proportions usually results in a slurry of the sulfonated polymer which is flowable and easy to handle and which facilitates the production of a sulfonated alkenyl aromatic resin of good quality.

The sulfonation reaction is rapid and is practically over after a few seconds. Low further sulfonation usually occurs when one

let the mixture stand for a short time (10 minutes or longer).

The sulfonated resin product can be separated from the liquid reaction medium in the usual manner will. When an alkenyl aromatic resin is sulfonated, the resin sulfonic acid falls immediately usually in the form of granules after formation, which are filtered off from the reaction mixture can be. Usually this granular product is obtained in a form that is unreacted Sulfur trioxide is almost free. This product can be used advantageously with liquid sulfur dioxide or with the Above-mentioned sulfur dioxide-containing solvent can be washed to remove the last traces To remove sulfur trioxide.

The sulfonation process can be carried out on a batch basis; the reaction becomes more difficult, however, the larger the approach. The process can also be carried out interrupted by a stream of the pretreated solution of the sulfur trioxide in liquid SO ₂ or in the above-mentioned solvent mixture and a stream of a solution of the polymer to be treated in another part of this solvent mixture or preferably a polychlorinated aliphatic hydrocarbon mixed with one another combines to form a reaction mixture which contains all the starting materials in the proportions mentioned above and which undergoes the reaction under the conditions mentioned. The sulfonated resin can be separated in a granular state immediately after formation. One can pass the sulfonation mixture fairly quickly through a reaction zone and then put it on a filter device to separate the product.

The following examples illustrate the invention.

example 1

1.4 parts by weight of a copolymer containing chemically bonded 50 percent by weight styrene and 50 percent by weight vinyl tuene and having a viscosity of 38 cP (it was determined on a 10 percent by weight solution of the copolymer in toluene at 25 ° C.) was dissolved in 100 parts by weight of carbon tetrachloride. In a steel storage vessel, 1 part by weight of sulfur trioxide was dissolved under pressure in 100 parts by weight of liquid sulfur dioxide. The solution of the copolymer and that of the sulfur trioxide were then mixed and placed in a reaction vessel (a steel pot approximately 10 cm in internal diameter and 15 cm in length, which was provided with a stirrer and an overflow) at atmospheric pressure. The mixture was held at a temperature between -6 and -7 ° C for 5 to 6 minutes (reaction time). "Reaction time" is to be understood as the time required to lead a very small amount of the mixture through the reaction mass from the point of supply of the solution of the reactants to the point of discharge or the overflow of the reacted mixture from the vessel. The solution of the copolymer in C Cl ₄ was added in an amount of 9 kg of solution per hour. The solution of sulfur trioxide in the liquid SO ₂ was withdrawn from the storage vessel and passed through a bed of the sodium form of a cation exchange resin, which consisted of a sulfonated copolymer of approximately 87 percent by weight styrene, 5 percent by weight ethylvinylbenzene and 8 percent by weight divinylbenzene, before this sulfur trioxide solution was mixed with the

Solution of the copolymer was added to the reaction vessel. The cation exchange resin was air dried at room temperature prior to testing. The sulfur trioxide solution was added in an amount of 9.2 kg of solution per hour. In the experiment 5, the two solutions of the reactants were added in the mixture with each other in the same direction into the reaction vessel in the above proportions and removed the reacted mixture from the vessel 8 ¹ It hours continuously. The sulfonated copolymer precipitated from the reaction mixture immediately after formation; it was filtered off and dried. Aliquots of the sulfonated copolymer were collected at certain time intervals during the experiment. A portion of the dried sulfonated product was dissolved in water to form a solution containing 0.5 percent by weight of the product. The viscosity of this solution was determined in cP in a Brookfield viscometer at 25 ° C. After the experiment had been carried out for 3 1/2 hours, during which time the solution of the sulfur trioxide had been passed through the bed of the cation exchanger, the cation exchanger bed was switched off and the solution of the sulfur trioxide in the liquid SO ₂ in the following 2 hours directly from the storage kettle into the reaction vessel in the mixture given with the solution of the copolymer in the proportions mentioned above. Thereafter, the solution of the sulfur trioxide in the liquid SO _{2 was} again passed through the bed of the cation exchange resin throughout the rest of the experiment. In Table I below, each aliquot is shown under the "Sample No." column. The time in minutes after the start of the experiment after which the aliquot was obtained is also given. The temperature at which the reaction was carried out is then indicated. Finally, the viscosity of the product in question is given in cP at 25 ° C. for a 0.5 percent by weight solution of the acidic sulfonated copolymer in water. The viscosity of the solution is an indirect, but easy to determine, measure of the degree of crosslinking between the polymer molecules in the sulfonated product. An increase in viscosity indicates that the crosslinking in the molecules has also become stronger.

Table I. Example 2

Another part of the copolymer described in Example 1 was dissolved in methylene chloride to form a solution which contained 1.4 parts by weight of the polymer per 100 parts by weight of methylene chloride. This mixed polymer solution and a solution of 1 part by weight of sulfur trioxide in 100 parts of SO ₂ were mixed with one another in a reaction vessel (as in Example 1) in such amounts that 0.8 part by weight of the mixed polymer solution was present for 1 part of the sulfur oxides. In the reaction vessel, the mixture was held at -1 ° C for approximately 8 minutes. _{The liquid SO 2} containing the sulfur trioxide was passed through a bed of the sodium form of a cation exchange resin before it was added to the reaction vessel as a mixture with the solution of the copolymer. In this experiment, the solutions of the reactants were mixed with one another, introduced into the reaction zone and the reacted mixture withdrawn therefrom continuously for 4.75 hours. Each aliquot obtained after a certain time was filtered and in this way the sulfonated product was recovered, which was dried. A portion of the dried sulfonate was dissolved in water to form a 0.5 weight percent solution. The viscosity of this solution was determined at 25 ° C. After the experiment had been carried out for 3 hours, during which time the SO ₂ -S Oj solution was passed through the bed of the sodium form of the cation exchange resin, this bed was switched off and the SO ₂ -SO ₃ solution was taken directly from the storage vessel for ⁸ Ai hours in passed the reaction vessel. In Table II, each aliquot part and the time in hours after which this aliquot part, calculated from the beginning of the experiment, was obtained is again under the column “Sample No.”. The viscosity of a 0.5 percent by weight solution of the acidic sulfonated product in question is also given in cP at 25 ° C., -p T, 11 TT

Table II

Aliquo the part
Time temperature viscosity
of the product Sample no. in hours in C incP 0 0 -6 1 1 -6 15th 2 1.5 -6 16 3 2.0 -6 20th 4th 2.5 -6 18th 5 3.0 -7 25th 6th 3.5 -7 36 7th 4.0 -7 130 8th 4.5 -7 265 9 5.0 -7 206 10 5.5 > -7 420 11 6.0 _m ij 250 12th 6.5 -7 55 13th 7.0 -7 50 14th 7.5 7th 31 15th 8.0 -7 45 16 8.5 -7 20th

55

Aliquot part Time
in hours Viscosity of the product Sample no. 0 incP 0 0.5 1 1 23 2 1.5 25th 3 2 24 4th 2.5 35 5 3 28 6th 3.5 30th 7th 4th 73 8th 4.25 115 9 4.5 120 10 4.75 115 11 105

60

65

70 Similar results were obtained in a second experiment in which instead of the above cation exchange resin a bed of sodium form of a phenolsulfonic - formaldehyde - condensation product was used.

Example 3

The sodium form of a cation exchange resin, which is made from the sulfonated copolymer of approximately 87 percent by weight styrene, 5 percent by weight ethylvinylbenzene and 8 percent by weight divinylbenzene existed, was dried in the air at room temperature and placed in a steel tube with an inner diameter of 5 cm.

knife filled in, so that a bed about 20 cm deep was created. This cation exchange resin passed of particles that passed through a sieve of 365 meshes per square centimeter and of one Sieve with 1460 meshes per square centimeter were retained. This. According to analysis, resin contained

3 parts by weight of copper, 23 parts by weight of iron and

4 parts by weight of lead per million parts by weight of resin. This resin bed was used in an attempt to sulfonate a copolymer of 50 percent by weight styrene and 50 percent by weight vinyl toluene according to the method described in Example 1, in which a _{solution containing 1 part by weight of sulfur trioxide per 100 parts by weight of SO 2 was passed} through a cation exchange resin bed before it was in Mixture with a solution of the copolymer in a polychlorinated aliphatic hydrocarbon was passed into the reaction zone. After the end of the experiment, the cation exchange resin was taken out of the tube, washed with water and dried. Based on the analysis, the resin now contained 26 parts by weight of copper, 220 parts by weight of iron and 5 parts by weight of lead per million parts by weight of the resin.

In a second experiment, another bed of the sodium form of the cation exchange resin was used in successive Attempts to sulfonate a copolymer made from 50 percent by weight of styrene and Used 50 weight percent vinyl toluene until heavy metal ions broke through the resin bed. That Resin was then taken out from the tube, washed with water and dried. Like the analysis found it contained 155 parts by weight of copper, 680 parts by weight of iron and 16 parts by weight of lead per million Parts by weight of the resin.

Example 4

About 0.6 kg of polyvinyltoluene, which had been prepared by polymerizing a mixture of 65 percent by weight of m-vinyltoluene and 35 percent by weight of p-vinyltoluene in bulk and had a viscosity of 921 cP (determined on a 10 percent by weight solution of the polymer in toluene at 25 ° C), were dissolved in 45 kg of methylene chloride. Then 0.45 kg of SO _{3 were} mixed with 45 kg of liquid SO 3 and stored in a steel storage vessel for 65 hours at room temperature. The polyvinyltoluene solution was then introduced into the reaction vessel described in Example 1 in an amount of about 7.5 kg of solution per hour. _{The liquid SO 3} containing the SO 3 was withdrawn from the storage vessel and passed through a bed of the sodium form of a cation exchange resin, which consisted of the sulfonated copolymer of approximately 87 percent by weight of styrene, 5 percent by weight of ethylvinylbenzene and 8 percent by weight of divinylbenzene, and then added continuously in an amount of 7.75 kg per hour in a mixture with the solution of polyvinyltoluene into the reaction vessel, in which it was kept at −2 ° C. for 5 to 6 minutes. When the two solutions were fed into this reaction vessel in the same direction, the reacted mixture was withdrawn from the reaction ^{zone without interruption for 4 1 2 hours.} During the entire experiment, aliquots of the reacted mixture were collected at certain time intervals. Each portion was filtered to obtain the sulfonated product, which was then dried. Part of the sulfonated polymer was dissolved in water to form a 0.5 percent strength by weight solution. The viscosity

the solution in cP at 25 ° C. was again determined in a Brookfield viscometer.

_{After the experiment had been carried out for 2} hours without interruption, during which time the liquid SO 2 -S O ₃ solution had been passed through the resin bed, the resin bed was switched off and the SO ₂ -SO ₃ solution was taken directly from the storage tank in a mixture with the polyvinyltoluene solution passed into the reaction vessel for the rest of the time of the experiment. In Table III all necessary information is again compiled.

Table III

Aliquot part Time
in hours Viscosity of the product sample No. 0 incP 0 1 1 1.5 73 2 2 66 3 2.5 85 4th 3 120 5 3.5 184 6th 4th 260 7th 4.5 244 8th 186

Example 5

Two experiments were carried out in which each time 0.63 kg of the polyvinyltoluene described in Example 4 were dissolved in 45 kg of methylene chloride. 0.45 kg of SO ₃ were mixed with 45 kg of liquid SO ₂ and stored in a steel storage tank for 16 hours. _{The SO 3} solution withdrawn from this tank was passed through a bed of the sodium form of the cation exchange resin described in Example 3 in an amount of 7.75 kg of solution per hour and then into the reaction vessel given in Example 1 together with the solution of polyvinyltoluene in methylene chloride given in an amount of 7.88 kg of solution per hour. The mixture was stirred in and about 6 minutes at long - held for 2 ^C C. The entire experiment was carried out without interruption, the solutions of the starting materials being added to the reaction vessel in the stated amounts and the reacted mixture being drawn off from the overflow for 5 hours. The sulfonated polymer precipitated from the liquid reaction medium immediately after its formation was filtered off, _{washed with liquid SO 2} and dried in air at room temperature. After the experiment had been carried out for 2½ hours, aliquots of the sulfonated polymer were collected at certain time intervals during the entire duration of the experiment. A portion of each sulfonated polymer was dissolved in water to form a 0.5 percent by weight solution and its viscosity was determined as above in a Brookfield viscometer at 25 ° C. All the necessary information is summarized in Table IV.

Table IV

Aliquot part Time
in hours Viscosity of the product Sample no. 2.5 incP 1 3.0 80 2 3.5 71 3 4.0 87 4th 4.5 74 5 5.0 71 6th "70

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In a second experiment with the same solutions, the SO ₂ -SO ₃ solution was withdrawn from the storage tank and passed through a bed of the ferric form of a cation exchange resin, which consisted of the sulfonated copolymer described in Example 4, in order to introduce iron ions into the solution before it was mixed with the solution of the polyvinyltoluene in the reaction vessel. The sulfonated polymer was separated from the reacted mixture as described above. Table V summarizes the results. The viscosity of the sulfonated product was measured on a 0.5 percent by weight solution of the dried product in distilled water at 25 ° C.

Aliquot part Time
in hours V Tabel Sample no. 2.5 Viscosity of the product 1 3.0 incP 2 3.5 139 3 4.0 128. 4th 4.5 155 5 5.0 128 6th 122 140

Claims (2)

PATENT CLAIMS: 1. Process for the sulfonation of a benzene-soluble, thermoplastic, alkenylaromatic Resin, preferably of polystyrene, polyvinyltoluene or a mixed polymer of styrene and vinyltoluene, in which the resin is treated with a solution of sulfur trioxide in a liquid solvent brings into contact, that of sulfur dioxide or a mixture of a larger one Weight fraction of sulfur dioxide and a smaller one Proportion of at least one polychlorinated aliphatic hydrocarbon, such as methylene chloride, Carbon tetrachloride, 1,1,1-trichloroethane, Tetrachlorethylene or ethylene dichloride, characterized in that a sulfur trioxide solution used, from which the heavy metal ions previously passed by the Solution through a bed of an alkali salt form of a cation exchange resin, which is known to be functional Groups containing sulfonic acid or carboxyl groups have been removed. 2. The method according to claim 1, characterized in that the cation exchange resin is an insoluble, Resin-like, sulfonated copolymer made from a predominant proportion of styrene and a minor proportion is ethyl vinylbenzene and divinylbenzene. Considered publications:
German Patent No. 832,886;
U.S. Patent Nos. 2,533,210, 2,533,211;
German patent application H 11721 IVb / 39c (published on December 17, 1953). © 009 678/538 12.60