MXPA01011153A - Process for removing iron-and rhodium-containing catalyst residues from hydrogenated nitrile rubber - Google Patents

Abstract

A process is provided for the removal of iron- and rhodium-containing residues from a solution of hydrogenated nitrile rubber. The process utilizes an ion-exchange resin having thiourea functional groups. Further, the resin is both macroporour and monodispersed. The process removes both rhodium and iron from viscous rubber solutions. In a preferred embodiment, the process is carried out in an ion-exchange column.

Description

A PROCEDURE FOR THE ELIMINATION OF RESIDUES OF CATALYSTS THAT CONTAIN IRON AND RHODIUM FROM RUBBER OF HYDROGENATED NITRIL This invention provides a process for the removal of residues of catalysts containing iron and rhodium from hydrogenated nitrile rubber. BACKGROUND OF THE INVENTION The hydrogenation of polymers and the subsequent removal of the catalyst from the hydrogenation of the polymer are both well known unit operations, as described, for example, in US Pat. 4,396,761, 4,510,293 and 4,595,749. More specifically, it is known that certain rhodium-containing catalysts are particularly suitable for the selective hydrogenation of nitrile rubber (ie, for the reduction of carbon-carbon double bonds without concomitant reduction of the triple carbon-nitrogen bonds present. in nitrile rubber). Said hydrogenated nitrile rubber is less susceptible to heat induced degradation as compared to the unsaturated nitrile rubber. For example, UK Patent 1,558,491 describes the use of chloro trio (tristriphenylphosphine) [i.e., RhCl (PPh3) 3] in said process. The Patent, USA No. 4,464,515 shows the use of the hydrohydrodiotetra-kis catalyst (triphenylphosphine) [ie, HRh (PPh3) 4] for the same purpose. In both processes, the nitrile rubber in place is first dissolved in a suitable solvent to obtain a viscous rubber solution. The catalyst is then dissolved in the rubber solution. These hydrogenation processes are said to be homogeneous, since the substrate and the catalyst are contained in the same phase. An advantage of homogenous procedures an- This is because they require minimal amounts of catalyst to effect hydrogenation. However, a major drawback of such processes is that it is difficult to remove the catalyst from the reaction mixture once the reaction has been completed (as a comparison, in a heterogeneous process (i.e., when the catalyst does not dissolve in the reaction), the catalyst can be easily removed by filtration or centrifugation). In addition to rhodium, there may also be presence of iron residues in the nitrile polymer. Both iron and rhodium are active catalytic metals and, therefore, it is desirable to remove them from hydrogenated rubber to improve the overall quality of the product. Moreover, the high price of rhodium provides an economic incentive for your. Recovery. The prior art directed toward the recovery of rhodium from hydrogenated rubber is described in US Pat. No. 4,985,540, which describes a process in which a solution containing a hydrogenated nitrile rubber in a hydrocarbon solvent with an ion exchange resin is treated. The ion exchange resin used was characterized by being. a macroporous heterodisperse resin with a functional group selected from a primary amine, a secondary amine, a thiol, a carbodithioate, a thiourea and a dithiocarbamate. The recovery of rhodium complexes from non-viscous chemical process streams using ion exchange resins * is also known. For example, in Chemical Abstraete (CA) 75: 19878e (1971), the separation of rhodium-containing catalysts from oxo reaction streams using an ion exchange resin is described. In CA 85: .588k (1976) the use of a thiol-functionalized resin is taught to recover Group VII metals from spent organic solutions containing catalysts. In CA 87: 26590p (1977) a two-stage procedure is described in which (1) is prepared one. aqueous solution containing a noble metal by extraction of metal from a catalyst support and (ii) noble * metal is adsorbed by an ion exchange resin. Finally, CA 95: 10502r (1981). Relates to the recovery of platinum and rhodium by extracting metals from spent catalysts using HCl and HN03, followed by the subsequent use of an ion exchange column to separate the metals. Notwithstanding the above methods of the art, there remains room for an improvement of methods for the removal of residues of iron and rhodium-containing catalysts from hydrogenated nitrile rubber, particularly with respect to viscous solutions of hydrogenated nitrile rubber. SUMMARY OF THE INVENTION An improved process for the removal of residues of iron and rhodium-containing catalysts from hydrogenated nitrile rubber is provided, the process of which consists in the treatment of a solution of hydrogenated nitrile rubber containing said residues with a resin. ion exchange, the resin being a macroporous and homodisperse crosslinked styrene-divinylbenzene copolymer resin having urea functional groups. The aforementioned ion exchange resin is capable of removing both the iron and rhodium residues of the hydrogenated nitrile rubber. In another aspect of the invention, there is presented a column method for the elimination of residues of iron and rhodium-containing catalysts of hydrogenated ni-trile rubber which results in a markedly lower pressure drop through the system, increasing this mode the capacity of production by allowing a greater yield of olumen. DETAILED DESCRIPTION As used herein, the term "hydrogenated nitrile rubber" refers to the product that is obtained by hydrogenation of at least 80 mol%, preferably 85-99.5 mol% of the original carbon-carbon double bonds in the unsaturated nitrile rubber. The unsaturated nitrile rubber is a copolymer of a C3.5 a, ß-unsaturated nitrile monomer and a C4.6 conjugated diene monomer. A typical example is acrylonitrile-butadiene rubber, commonly referred to as "NBR". The unsaturated nitrile rubber can be produced by the known free radical emulsion polymerization process. A typical unsaturated nitrile rubber produced by the polymerization of acrylonitrile and butadiene contains from 18 to 50 weight percent of acrylonitrile units attached, the remainder being butadiene attached. The hydrogenated nitrile rubber is preferably prepared using a rhodium-containing catalyst, since many of the cheap catalysts. of heavy metals (such as Raney nickel, cobalt alcoholes and aluminum alcoholes) or are not active enough to catalyze the hydrogenation of nitrile rubber, or are not selective (ie, they also catalyze the reduction of triple carbon bonds -nitrogen). The use of rhodium-containing complexes as catalysts for the hydrogenation of nitrile rubber. it is described in UK Patent 1,558,491. The process of the present invention requires the use of a homodisperse macroporous cross-linked styrene-divinylbenzene copolymer resin having thiourea functional groups. Said resins consist typically of crosslinked copolymers of monovinyl-aromatic and at least one polyvinylaromatic compounds and are described in DE-A 19940868, the description of which is incorporated herein by reference. Said resins can be prepared by the procedure: (a) reaction of monomer droplets consisting of at least one monovinylaromatic compound and at least one polyvinylaromatic compound, if desired, together with a porogen (pore former) and with an initiator or a combination of initiators to give a polymer in mono-dispersed crosslinked pearls; (b) amidomethylation of the monodisperse cross-linked pearl polymer of step (a) with phthalimide derivatives; (c) converting the polymer into amidomethyl beads of step (b) into a polymer in aminometal beads, and (d) reacting the polymer in aminomethylated beads of step (c) with thiourea, with substituted thiourea or with salts of thiocyanic acid. The monodisperse cross-linked vinylaromatic basic polymer according to step (a) of the process can be prepared by methods known from the literature. Methods of this type are described, for example, in U.S. Pat. 4,444,961, EP-A 46,535, U.S. Pat. 4,419,245 or WO 93/12167. In step (a) of the process, at least one monovinylaromatic compound and at least one polyvinylaromatic compound are used. However, it is also possible to use mixtures of. two or more monovinylaromatic compounds and mixtures of two or more polyvinylaromatic compounds. Preferred monovinylaromatic compounds for use in step (a) of the process are monoethylenically unsaturated compounds, such as styrene, vinylthioluene, ethylstyrene, α-methylstyrene, chlordestirene, chlorometylstyrene, alkyl acrylates and alkyl methacrylates. Particular preference is given to the use of styrene or mixtures of styrene with the aforementioned monomers. The preferred polyvinylaromatic compounds for use in step (a) of the process are ethylenically unsaturated, multifunctional compounds, such as divinyl benzene, divinyl toluene, trivinyl benzene, divinyl naphthalene, trivinyl naphthalene, 1,7-octadiene, 1,5-hexadiene, dimethacrylate. - ethylene glycol, trimethylolpropane trimethacrylate or allyl methacrylate. The amounts used of the polyvinylaromatic compounds are generally from 1 to 20% by weight (preferably from 2 to 12% by weight), particularly preferably from 4 to 10% by weight), based on the monomer or its mixture with other monomers. The nature of the polyvinylaromatic compounds (cross-linking agents) is selected considering the subsequent use of the spherical polymer. In many cases divinylbenzene is suitable. For most uses, they are sufficient. commercial grades of divinylbenzene and contain ethylvinylbenzene in addition to divinylbenzene isomers. In a preferred process, droplets of. microencapsulated monomers in step (a) of the process. Possible materials for the microencapsulation of the monomer droplets are those known for use as complex coacervates, in particular polyesters, natural synthetic polyamides, polyurethanes and polyureas. An example of a particularly suitable natural polyamide is gelatin, which is used in particular as a coacervate and complex coacervate. For the purposes of the present invention, the complex coacervates containing gelatin are primarily combinations of gelatin with synthetic polyelectrolytes. Suitable synthetic polyelectrolytes are copolymers incorporating units of, for example, maleic acid, acrylic acid, methacrylic acid, acrylic Lick or methacrylamide. Particular preference is given to the use of acrylic acid and acrylamide. Capsules containing gelatin can be hardened using conventional hardeners, such as formaldehyde or glutaric dialdehyde. The encapsulation of monomer droplets with gelatin, with coacervates containing "gelatin and with complex coacervates containing gelatin is described in detail in EP-A 46,535. The methods for encapsulation using synthetic polymers are known." An example of a highly suitable process is interfacial condensation, wherein a reactive component dissolved in the monomer droplet (eg, an isocyanate or an acid chloride) reacts with a second reactive component (eg, an amine) dissolved in the aqueous phase. monomers, which can be microencapsulated, if desired, can, if desired, contain an initiator or mixtures of initiators to initiate the polymerization Examples of initiators suitable for the new process are peroxy compounds such as dibenzoyl peroxide, dilauroyl peroxide, bis (p- = chlorobenzoyl) peroxide, dicyclohexyl peroxydicarbonate, efl? ßt roc t-butyl to ate, t-butyl peroxy-2-ethylhexanoate, 2,5-bis (2-ethylhexanoylper-oxy) -2,5-dimethylhexane and t-amylperoxy-2-ethylhexane; and azo compounds such as 2,2'-azobis (isobutyro-nitrile) and 2,2'-azobis (2-methylisobutyronitrile). The amount of initiator used is generally from 0.05 to 2.5% by weight (preferably from 0.1 to 1.5% by weight), based on the monomer mixture. To create a macroporous structure in the spherical polymer, it is possible, if desired, to use porogens as further additives in the eventually microencapsulated monomer droplets. Suitable solvents for this purpose are organic solvents which are poor solvents and, respectively, of numbing agents with respect to the polymer produced. Examples which may be mentioned are hexane, octane, isooctane, isododecane, methyl ethyl ketone, butanol and octanol and their isomers. The concepts "microporous" or "gel" and "macroporous" have been described in detail in the technical literature. Preferred pearl polymers for the purposes of the present invention and prepared in step (a) of the process have a macroporous structure. Monodispersed substances for the purposes of the present application are those for which the diameter of at least 90% by volume or weight of the particles varies with respect to the most frequent diameter by no more than ± 10% of the most frequent diameter. For example, in the case of a substance with. a more frequent diameter of 0.5 mm, at least 90% by volume or weight have a size range of 0.45 mm to 0.55 mm and, in the case of a substance with a more frequent diameter of 0.7 mm, at least 90% by volume or weight have a size range of 0.77 mm to 0.63 mm. Polymers in macroporous monodisperse beads can be produced by, for example, adding inert materials (porogens) to the monomer mixture during polymerization. Suitable substances of this type are primarily organic substances which dissolve in the monomer, but which are poor solvents for the polymer (numbing agents), for example certain aliphatic hydrocarbons. . U.S. Pat. No. 4,382,124, for example, uses alcohols having from 4 to 10 carbon atoms as the porogens to prepare polymers in macodorous monodisperse beads based on styrene / divinylbenzene. A summary of the preparation methods for polymers in macroporous pearls is also given.

The monomer droplets, which may be microencapsulated, if desired, may also contain, if desired, up to 30% by weight (based on the monomer) of crosslinked or non-crosslinked polymer. Preferred polymers defer to the aforementioned monomers, particularly preferably styrene. The average particle size of the monomer droplets, which can be encapsulated, if desired, is 10 to 1,000 μp ?, preferably 100 to 1,000 μt ?. The procedure is also very suitable for preparing monodisperse spherical polymers. When polymers are prepared in monodisperse beads according to step (a) of the process, the aqueous phase may contain, if desired, an inhibitor of the dissolved polymerization, which may be an inorganic or organic substance. Examples of inorganic inhibitors are nitrogenous compounds such as hydroxylamine, hydrazine, sodium nitrite, potassium nitrite.; salts of phosphorous acid, such as sodium hydrogen phosphite, and sulfur-containing compounds, such as sodium dithionite, sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium thiocyanate and ammonium thiocyanate. Examples of organic inhibitors are phenolic compounds such as hydroquinone, hydroquinone, monomethyl ether, resorcinol, pyrocatechol, tert-butylpyrocatechol, pyrogallol and condensation products made with phenols and aldehydes. Other suitable organic inhibitors are the nitrogen-containing compounds, including the hydroxylamine derivatives. such as N, N-diethylhydroxylamine, N-isopropylhydroxylamine and sulfonated or carboxylated derivatives of N-alkylhydroxylamine or of N, N-dialkylhydroxyl-amine; hydrazine derivatives, such as N, N-hydrazinodiacetic acid; nitroso compounds, such as N-n-nitrosophenylhydroxylamine, the ammonium salt of N-nitroso-phenylhydroxylamine or the aluminum salt of N-nitrosophe- nylhydroxylamine. The concentration of the inhibitor is from 5 to 1,000 pptn (based on the aqueous phase), preferably from 10 to 500 ppm, particularly preferably from 10 to 250 ppm. As mentioned above, the polymerization of monomer droplets optionally microencapsulated to give the polymer in spherical monodisperse beads can take place, if desired, in the presence of one or more protective colloids in the aqueous phase. Suitable protective colloids are natural or synthetic water-soluble polymers such as gelatin, starch, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid or copolymers made from methacrylic acid and from methacrylates. Other suitable materials are cellulose derivatives, particularly cellulose esters and cellulose ethers, such as carboxymethylcellulose, methylhydroxy-ethylcellulose,. methylhydroxypropylcellulose and hydroxyethylcellulose. Gelatin is particularly suitable. The amount used of the protective colloid is generally from 0.05 to 1% by weight (preferably from 0.05 to 0.5% by weight), based on the aqueous phase. Polymerization to give the polymer in macroporous, monodisperse and spherical beads in step (a) of the process may also be, if desired, carried out in the presence of a buffer system. Preference is given to buffer systems which fix the pH of the aqueous phase at the beginning of the polymerization to between 14 and 6 (preferably between 12 and 8). Under these conditions, protective colloids having carboxylic acid groups are present to some extent, or completely, in the form of salts, which has a favorable effect on the action of the protective colloids. The systems . Buffers particularly suitable for the purposes of the present invention contain phosphate salts or borate salts. For the purposes of the present invention, the terms phosphate and borate include the condensation products of the forms ortho of the corresponding acids and salts. The concentration of the phosphate or borate in the aqueous phase is from 0.5 to 500 mmol / 1, preferably from 2.5 to 100 mmol / 1. The stirring speed during the polymerization is relatively non-critical and, unlike conventional bead polymerization, has no effect on the particle size. The agitation speeds used are low speeds, which are sufficient to keep the droplets of monomer in suspension and to promote the heat dissipation of the polymerization. A variety of agitator types can be used for this task. Gate agitators with axial action are particularly suitable. The volume ratio of droplets of encapsulated monomer to aqueous phase is from 1: 0.75 to 1:20, preferably from 1: 1 to 1: 6. The polymerization temperature depends on the decomposition temperature of the initiator used and is generally 50 to 80 ° C (preferably 55 to 130 ° C). The polymerization takes from 0.5 hours to a few hours. It has been found useful to use a temperature program in which polymerization is initiated at a low temperature (eg, 60 ° C) and the temperature of the reaction is raised as the conversion of the polymerization progresses. This is a very good way of fulfilling, for example, the requirement of a reaction that proceeds in a reliable manner and with a high polymerization conversion. After polymerization, the polymer is isolated using conventional methods (eg, by filtration or decantation) and washed, if desired. In the process step (b), the amidomethylating reagent is first prepared. This is done, for example, by dissolving a phthalimide or phthalimide derivative in a solvent and mixing with formalin. A form is then formed bis (phthalimido) ether from this material with removal of water. The bis (phthalimido) ether may react, if desired, to give the phthalimido ester. Preferred phthalimide derivatives are phthalimide itself and substituted phthalimides such as methylphthalimide. The solvents used in step (b) of the process are inert and suitable for swelling the polymer and. they are preferably chlorinated hydrocarbons, particularly preferably dichloroethane or methylene chloride. In step (b) of the process, the polymer is condensed into beads with phthalimide derivatives. The catalyst used here includes oleum, sulfuric acid or. sulfur trioxide. The elimination of the phthalic acid residue, and thereby the release of the aminomethyl group, takes place in step (c) of the process through the treatment of the cross-linked phthalimidomethylated polymer. with | solu- aqueous or alcoholic salts of an alkali metal hydroxide, such as sodium hydroxide or potassium hydroxide, at temperatures of 100 to 250 ° C (preferably 120 to 190 ° C).

The concentration of the aqueous sodium hydroxide is 10 to 50% by weight, preferably 20 to 40% by weight. This process allows the preparation of polymers in crosslinked beads containing aminoalkyl groups with substitution of the aromatic rings at a level greater than 1. The resulting polymer in aminomethylated beads is finally washed with deionized water until alkali-free. In step (d) of the process, the polymers are prepared by reaction of the cross-linked, monodisperse and aminomethyl aromatic base polymer in suspension with thiourea or substituted thiourea or with thio-cyanic acid salts. It is particularly preferable to use thiourea or salts of thiocyanic acid.

Mineral acids are used as suspending medium, preferably aqueous hydrochloric acid, at concentrations of 10 to 40% by weight (preferably, 2.0 to 35% by weight). The process preferably gives polymers in monodisperse beads having the following functional groups that are formed during step (d) of the process: (2) - (CH2) n- -NR, H (4) . { - (CH2) n- N = C = N- (CH2) -] - where Ri is hydrogen or an alkyl group, R 2 is hydrogen or an alkyl group, R 3 is hydrogen or an alkyl group and n is an integer from 1 to 5 (in particular, preferably 1). In the Rif groups R2 and R3l the alkyl is preferably in each case Ci-C6 alkyl. In polymers in monodisperse beads having thiourea groups, each aromatic ring preferably has 0.1 to 2 of the functional groups mentioned above (1), (2), (3) or (4). The proportion of the individual functional groups, based on the total of all the functional groups, is preferably: from 30 to 80% of (1), from 5 to 30% of (2), from 1 to 95% of (3), from 1 to 5% of (4). Pearl polymers are particularly suitable for removing rhodium, platinum group elements, gold, silver or catalyst residues containing rhodium or noble metals, from solutions or organic solvents. For example, such polymers can be used in beads to remove iron and rhodium-containing catalyst residues from the hydrogenation product of the nitrile rubber using a homogeneous catalyst system. The rubber solution may contain from about 0.5 to about 20% by weight of rubber, preferably from about 3 to about 12 weight percent and, therefore, is viscous. In a typical embodiment of the invention, the resin is added to a solution of the hydrogenated nitrile rubber containing catalyst residues and the mixture is stirred for a sufficient period of time for the catalyst residues to be removed by the resin. The reaction time may vary between about 5 and about 100 hours and is preferably in the range of about 48 to about 72 hours.The resin is separated by simple filtration and the rubber is recovered by removing the solvent using standard techniques known in US Pat. This field, such as evaporation under reduced pressure, may be carried out in an inert atmosphere, for example under a blanket of nitrogen.

Preferably, the amount of resin used in the practice of the invention varies between about 0.1 and about 10 weight percent, based on the amount of hydrogenated nitrile rubber in the solution. More preferably, about 0.5 to about 5 weight percent is used. Suitable operating temperatures vary between about 60 and about 120 ° C. Preferably, the operating temperature is in the approximate range. 90 to about 120 ° C. Higher temperatures of approximately 160 ° C should not be used, due to the decomposition potential of the ion exchange resin. In another embodiment of the present invention, the ion exchange resin is mounted in a bed configuration, for example by packing the resin in a column (i.e., in a cylindrical container) and passing the nitrile rubber solution through the the column in a continuous way. In another embodiment of the invention, the rubber solution can be passed through the column more than once.; thus ensuring that all possible catalyst residue is removed by the resin. As will be appreciated by those skilled in the art, a substantial pressure drop occurs by the flow. of a solution through a bed of small particles. This phenomenon is particularly pronounced when the solution is viscous and the particles are very fine and of a variable particle size. In a preferred embodiment of the present invention, however, the pressure drop that results from the flow of the hydrogenated rubber solution containing iron and rhodium through the ion exchange resin bed is substantially less than that observed using a resin heterodisperse. This significant reduction in pressure drop (by a factor of approximately two thirds) per- limit a much higher volume yield than would otherwise be possible, resulting in a much greater reduction capacity of said column procedure. More details about the invention are given by the following non-limiting examples. EXAMPLES Example 1) Preparation of the monodisperse macroporous polymer polymer based on styrene, divinylbenzene and ethylstyrene. 3,000 g of deionized water were placed in a 10 liter glass reactor and a solution consisting of 10 g of gelatine, 16 g of water, was added. hydrogen phosphate disodium-dodecahydrate and 0.73 g of resorcinol in 320 g of deionized water, and mixed well. The temperature of the mixture was controlled at 25 ° C. A mixture of 3,200 .g of microencapsulated monomer droplets with a narrow particle size distribution and prepared from 3.6% by weight of divinylbenzene and 0.9% by weight was then introduced with stirring. weight of ethylstyrene (used in the form of a commercially available isomer mixture of divinylbenzene and ethylstyrene in 80% divinylbenzene), 0, -5% by weight of dibenzoyl peroxide, 56.2% by weight of styrene and a 38.8% by weight of isododecane (mixture of industrial isomers with a high proportion of pentamethylheptane), where the microcapsules were composed of a complex coacervate hardened with formaldehyde prepared with gelatin and with a copolymer of acrylamide and acrylic acid, and 3,200 were added g of aqueous phase with a pH of 12. The average particle size of the monomer droplets was 460 μp ?. The mixture was polymerized until completion, with stirring, increasing the temperature according to a temperature program that started at 25 ° C and ended at 95 ° C. The mixture was cooled, washed using a 32 um sieve and dried under vacuum at 80 ° C. This gave 1893 g of a spherical polymer with a mean particle size of 440 μt ?, a narrow particle size distribution and a smooth surface. The polymer had a creamy white appearance from above and had a bulk density of about 370 g / 1. Ib) Preparation of the polymer in amidomethylated beads 2.373 g of dichloroethane, 705 g of phthalimide and 505 g of formalin were placed with one. concentration of 29.2% by weight in a. container at room temperature. The pH of the suspension was adjusted to 5.5 to 6 using aqueous sodium hydroxide. The water was then removed by distillation, then 51.7 g of sulfuric acid were metered in and the resulting water was removed by distillation. The mixture was cooled. 189 g of oleum at a concentration of 65% at 30 ° C were dosed, followed by 371.4 g of monodisperse pearl polymer prepared according to step a) of the procedure of Example 1. The suspension was heated to 70 ° C. and stirred for another 6 hours at this temperature. The reaction liquid was removed, deionized water was metered in and the residual dichloroethane was removed by distillation. Performance of the polymer in amidomethylated beads: 2,140 ml.

Composition by elemental analysis: Carbon: 75.3% by weight. Hydrogen: 4.9% by weight. Nitrogen: 5.8% by weight. Rest: oxygen. (a) Preparation of the polymer in aminomethylated beads. 1.019 g of aqueous sodium hydroxide with a concentration of 45% by weight and 406 ml of deionized water at room temperature in 2,100 ml of polymer in amidomethylated beads were dosed. The suspension was heated to 180 ° C and stirred for 6 hours at this temperature.

The resultant polymer was washed with deionized water. Performance of the polymer in aminomethylated beads: 1770 ml. The overall yield (extrapolated) was 1,804 mi. Composition by elemental analysis: Nitrogen 11.75% by weight. It could be calculated by the polymer composition in aminomethylated beads by elemental analysis that, as a statistical average per aromatic ring - as a result of the styrene and divinylbenzene units -, 1.17 hydrogen atoms had been replaced by aminomethyl groups. Id) Preparation of the monodisperse resin having thiourea groups. 1132 ml of deionized water were placed in a 4 liter autoclave at room temperature. 1,700 ml of polymer were metered into aminomethylated beads from stage c), 470 g of hydrochloric acid with a concentration of 30% by weight and 485 g of thiourea in the autoclave. The suspension was stirred for 30 minutes at room temperature. The autoclave was then heated at 145 eC for a period of 2 hours. The mixture was stirred at 145 ° C for another 15 hours. The mixture was cooled and the pressure relaxed. The supernatant fluid was extracted. The polymer was washed in resulting beads with aqueous sodium hydroxide of a concentration of 4% by weight and finally with deionized water. Performance: 1,652 mi. Elemental analyzes: Nitrogen: 10.4% by weight. Sulfur: 10.2% by weight. . Example 2 This example illustrates the use of thiourea-functionalized macropoxyl resin (Lewatit OC 1601, obtained from Bayer AG (Leverkusen, Germany)) to remove iron and rhodium of a solution containing iron and rhodium of hydrogenated ni-trile rubber in a batch process. A 7.5% (by weight) solution in monocylobenzene of 99% hydrogenated nitrile rubber was used as a standard for all experimental work. and the term "standard rubber solution", as used herein, refers to this solution. In a series of 500 ml three-necked round bottom flasks, various amounts of the monodisperse resin functionalized with thiourea (ie, 0.1, 0.2, 0.3, and 0.5 g) were added together with 180 g of the standard rubber solution, as indicated in Table 1. Each reaction mixture was stirred at about 100 ° C, under nitrogen, for 64 hours. The resin was then separated from the mixture by filtration and the rubber was recovered by evaporation of the solvent in a rotary evaporator, followed by drying in a reduced pressure oven at 60 ° C. Samples of recovered rubber were analyzed for Rh and Fe content by atomic absorption spectroscopy and induction-coupled plasma, respectively. The results are shown in Table 1. In a comparative experiment, the rubber was recovered from an untreated 180 g sample of the standard rubber solution by the evaporation / desiccation methods described above. The amount of Rh in this "control sample" was measured by atomic absorption spectroscopy and the amount of Fe per plasma coupled by induction was measured. The amounts of Rh and Fe initially present at 100 parts were normalized and all subsequent results are cited with respect to the initial amounts present. Contrary to the control sample, it was found that the Rh content of the rubber recovered after the treatment was in the range of 13.7-43.6 parts, depending on the amount of resin used. These results indicate that had eliminated 56-86% of the Rh (ie, compared to the Rh content in the standard rubber sample). The more resin sample will be used, the more Rh was removed from the hydrogenated nitrile rubber solution. It was found that the Fe content of the rubber after the treatment was consistently in the range of 24.4-30.2 parts (with one exception, in which 0.2 g of resin was used). These results indicate that the resin is capable of removing a certain amount of Fe (70-76%, that is, compared to the Fe content in the standard rubber sample) irrespective of the amount of resin used. Table 1 * The initial content of Rh and Fe was normalized to 100. Example 3 (comparative) This is a comparative example in which a macroporous heterodisperse resin having dithiol functionality is used to remove Rh and Fe from a sample of the solution. Standard rubber in example 1. The results are shown in Table 2. It was found that the Rh content of the rubber recovered after the treatment was in the range of 26.9-70.2 parts, depending on the amount of resin used. These re- Substitutes indicate that 30-73% of the Rh had been removed (ie, compared to the Rh content in the standard rubber sample). The more resin sample will be used, the more Rh was. removed from the hydrogenated nitrile rubber solution. It was found that the Fe content of the rubber after the treatment was in the range of 40-98.2 parts depending on the amount of resin used. These results indicate that 2-60% of the Fe had been removed (ie, compared to the Rh content in the standard rubber sample). The more resin sample used, the more Fe was removed from the hydrogenated nitrile rubber solution. Therefore, it can be clearly seen that the use of the monodisperse resin functionalized with thiourea removed significantly more Rh and Fe from the hydrogenated nitrile rubber solution than the method of the art. Table 2 * The initial content of Rh and Fe was normalized to 100. Example 4 This example illustrates the use of thiourea-functionalized macropolar resin to remove iron and rhodium from a solution containing iron and rubber rhodium of hydrogenated nitrile in a column procedure. The resin employed was the same macroreticular resin functionalized with thiourea used in Example 1. Approximately 65-75 grams (dry weight) of the resin was packed in a column having a length of about 91 cm and an internal diameter of about 1, 9 cm The adsorption experiment was carried out by continuously passing the standard rubber solution through the packed column (base once through) for a period of 8 hours. The column was preheated to between 80 and 100 ° C and the rubber solution was also preheated to between 50 and 70 ° C. One gallon US of the rubber solution was added to the column at a flow rate between 11.5 and 12.5 g / min. The effluent leaving the column was collected, dried and the final rubber sample was analyzed for rhodium and iron. The standard rubber sample was analyzed to determine the rhodium and iron concentration of the rubber solution before the treatment in the column. The rhodium and iron analyzes were carried out according to the procedures described in Example 1. The Rh content in the final rubber sample after the treatment was 3.08 parts, indicating that it had been removed around 97% Rh (ie, compared to the Rh content in the standard rubber sample). The Fe content of the final rubber sample after the treatment was 17.2 parts, indicating that about 83% of the Fe was removed (ie, compared to the Fe content in the rubber sample). standard) . Table 3 * The initial content of Rh and Fe was normalized to 100.

Example 5 (Comparative) This is a comparative example in which a macroporous heterodisperse resin having thiol functionality was used to remove Rh and Fe from a sample of the standard rubber solution. from example 1 in a column procedure. The adsorption experiment was carried out under the same conditions as those described in Example 3. The analytical results of Rh and Fe are shown in Table 4. The Rh content of the final rubber sample after treatment was 20, 1 parts, indicating that approximately 80% of the Rh was removed (ie, compared to the Rh content in the rubber sample, standard). The content of Fe. of the final rubber sample after the treatment was 60.3 parts, indicating that approximately 40% of the Fe had been removed (ie, compared to the Fe content in the standard rubber sample). . Once again, it can be clearly seen that the use of monodisperse resin functionalized with thiourea in a column procedure significantly eliminated more Rh and Fe from the hydrogenated nitrile rubber solution than the metal. all of the technique. Table 4 * The initial content of Rh and Fe was normalized to 100. Example 6 (comparative). The treated rubber blends of Examples 3 and 4 were compounded (using a peroxide method) and the properties of the resulting vulcanizates were investigated to determine the effects of the residual metals (Rh and Fe) after aging in hot air. The results are illustrated in Figures 1 and 2. After aging at 150 ° C for 168 hours, the vulcanizate derived from Example 3 showed a slightly better retention of tensile strength and elongation, but slightly worse in the coefficients than the sample derived from Example 4. However, it was observed a marked difference after aging at 150 ° C for 672 hours, in which the vulcanizate derived from example 3 showed a much better retention of properties such as tensile strength, elongation and coefficients than the vulcanizate derived from example 4.

Claims (11)

1. CLAIMS 1. A process for the removal of catalyst residues containing iron and rhodium from hydrogenated nitro rubber, which consists in the treatment of a solution of hydrogenated nitrile rubber containing said residues | with a styrene-divinylbenzene copolymer resin cross-linked, macroporous and homodisperse that has thiourea functional groups.
2. 2. A process according to claim 1, wherein the hydrogenated nitrile rubber is dissolved in a halogenated solvent.
3. 3. A process according to claim 2, wherein the solvent is monochlorobenzene.
4. 4. A process according to claim 2, wherein the solution contains from about 0.5 to about 20 weight percent of hydrogenated nitrile rubber.
5. 5. A process according to claim 4, wherein the solution contains from about 3 to about 12 per cent. 100 percent by weight of hydrogenated nitrile rubber.
6. 6. A process according to claim 5, wherein the process is carried out at a temperature in the range of about 60 ° C to about 120 ° C
7. 7. A process according to claim 6, wherein the process is carried out at a temperature in the range of about 90 ° C to about 120 ° C.
8. 8. A process according to claim 7, wherein the amount of resin used is in the range of about 0.1 to about 10 weight percent, based on the amount of hydrogenated nitrile rubber in the solution
9. 9. A process according to claim 8, wherein the amount of resin used is in the range of approx. 0.5 to about 5 weight percent, based on the amount of hydrogenated nitrile rubber in the solution.
10. 10. A process according to claim 1, wherein the resin is packed in a column and the solution containing the hydrogenated nitrile rubber is passed through. the column continuously.
11. 11. A process according to claim 10, wherein the solution containing the hydrogenated nitrile rubber is cycled through the column more than once.