WO2016058640A1

WO2016058640A1 - Cross-linked copolymerisates, process for the efficient production of a low-swelling pearl polymer and use thereof

Info

Publication number: WO2016058640A1
Application number: PCT/EP2014/072140
Authority: WO
Inventors: Michael DR. KATZBERG; Helmut Ritter; Georg MEISWINKEL; Klaus KÜHLEIN
Original assignee: Thyssenkrupp Industrial Solutions Ag; Thyssenkrupp Ag
Priority date: 2014-10-15
Filing date: 2014-10-15
Publication date: 2016-04-21

Abstract

The present invention relates to a cross-linked copolymerisates in the form of spherical particles derived from heterocycles containing ring nitrogen, a process for their preparation and their use for the adsorption and purification of acid compounds, in particular organic carboxylic acids.

Description

Crosslinked copolymers, process for efficiently producing a low

swelling polymer beads and their use

The present invention relates to a crosslinked copolymer in the form of spherical particles derived from ring nitrogen-containing heterocycles, a process for their preparation and their use for the adsorption and purification of acidic compounds, in particular of organic carboxylic acids.

The adsorption of carboxylic acids by basic adsorption materials is well known. DE 3 043 766 A1 discloses a process for recovering carboxylic acid from an aqueous solution. The sorbent consists of pyridine units and is prepared by suspension polymerization. Crosslinkers are divinylbenzene, divinyl phthalate and ethylene glycol diacrylate. The sorbent material has a low capacity and has a strong swelling.

The adsorption of organic acids from aqueous solutions is also described in U.S. Patent Nos. 4,552,905 and 4,576,973. U.S. Patent No. 4,552,905 describes an exchange resin based on 4-vinylpyridine. US Pat. No. 4,576,973 describes an exchange resin based on N-vinylimidazole. The crosslinkers used are predominantly difunctional water-soluble acrylamides, such as Ν, Ν-methylenebisacrylamide, or diacrylates or dimethacrylates. The exchange resin is obtained by an inverse suspension polymerization by 4-vinylpyridine or N-vinylimidazole is dissolved together with the crosslinker and the initiator in water and the aqueous phase is then suspended in a hydrophobic inert solvent by the addition of an emulsifier. But also the use of non-water-soluble crosslinkers, such as divinylbenzene, is possible by solution in the hydrophobic phase. In addition, other usable monomers, such as N-vinylformamide or N-vinylacetamide may be mentioned. Typically, 50-95% of the basic monomer and 5-50% crosslinker are used. The copolymer is in the form of beads having a diameter in the range of 0.04 to 0.15 mm. The thus-synthesized exchange resin has a high adsorption capacity compared to conventional ion exchangers. Information on the degree of swelling can not be found. The synthesis of N-vinylimidazole and divinylbenzene-based exchange resins, as well as 4-vinylpyridine-divinylbenzene-based resins and their application is described in various patent documents and scientific publications. Fontanals et al. describe in J. Polym. Science (A), 42, 2019-25 (2004) and in J. Chromat. A, 1030 (2004) 63-8 and in J. Chromat. A, 1035 (2004) 281-84 describe the synthesis of such exchange resins for solid-phase extraction of polymeric substances by suspension polymerization. In this case, for example, a solution of N-vinylimidazole, divinylbenzene and 2,2'-azobis (2-methylpropionitrile) (AIBN) in toluene or a toluene / dibutyl phthalate mixture with the aid of polyvinyl alcohol is emulsified in water and then polymerized. The polymer is in the form of particles of uniform spherical shape. Important for the sorption capacity of such polymers is their proportion of functional groups in the polymer, which can be characterized by the amount of nitrogen in the polymer or the percentage of incorporated into the polymer amount of the nitrogen-containing monomer. In the prior art, it is possible to produce a polymer having a maximum N content in the polymer of 6.3%. The recovery for various organic substances from aqueous solution was investigated.

DE 3 138 194 A1 and US 2006/0138052 A1 describe the synthesis of N-vinylimidazole / divinylbenzene resins by suspension polymerization. Depending on the process, butyl acetate or ethyl acetate are used as the hydrophobic phase and water with the addition of inorganic salts as the hydrophilic phase. The emulsifier used polyvinyl alcohol or polyvinylpyrrolidone. The initiator is AIBN. Copolymers in the form of spherical particles in the range between 50 and 150 μm are obtained. The use of the exchange resins relates to the separation of various substances from liquids or the implementation of enzymatic reactions.

Crosslinked and non-swellable polymeric ampholytes are described in U.S. Patent No. 6,420,439 B1. These polymers are obtained by modification of poly-2 or poly-4-vinylpyridine resins crosslinked with divinylbenzene. The modification can be carried out by quaternization of the nitrogen atom on the pyridine radicals by covalently bonding a substituent which additionally carries a negatively charged group to the pyridyl nitrogen. The ampholytes can be used to separate acids from other substances.

DE 102 61 910 A1 describes an adsorbent material for blood, blood plasma and albumin purification processes. It is a highly networked, highly porous, Spherical divinylbenzene copolymer containing 4 to 30 wt .-% of a radically copolymerized vinylimidazole monomer.

Processes for the preparation of bead polymers are moreover known from DE 971, 934 B, DE 3 537 259 A1, DE 3 709 921 A1, DE 198 07 1 18 A1 and DE 199 17 562 A1.

The separation of acidic substances from mixtures of substances, e.g. from fermentation broths, is described in DE 33 28 093 A1, WO 93/06226 A1, US Pat. No. 6,146,534 and DE 10 201 1 120 632 A1.

The separation of acidic substances from substance mixtures is still in need of improvement. Although a wide variety of exchange substances are available, further improvements are constantly being sought, e.g. Separation processes which use such exchange resins to improve or increase their exchange capacity even further.

Applicant's experiments have shown that crosslinked copolymers derived from vinylimidazole and divinylbenzene or other crosslinkers and prepared by inverse suspension polymerization have too high a degree of swelling and a significant portion of the monomers (> 30%), in particular vinylimidazole, are not incorporated into the polymer during the suspension polymerization become. While the latter observation adversely affects the efficiency and economy of the resin production process, the former observation makes it difficult to use such resins in appropriate chromatography columns, especially on an industrial scale, and reduces the durability of the resin (higher brittle fragility of the resin beads upon high swelling in resin beds).

An object of the present invention was therefore to provide a crosslinked copolymer which has a high sorptive capacity for acidic substances and a low swelling capacity and can be efficiently produced.

This object is solved by the subject matter of the description and the claims.

In a first aspect, the present invention relates to a crosslinked copolymer in the form of spherical particles (a) 45-80% by weight, based on the total weight of the copolymer, of structural units derived from the general formula (I)

wherein

R ¹ , R ² and R ³ , each independently of one another, denote hydrogen or (C 1 -C 4) -alkyl,

X is a covalent C-C, C-O or C-N bond or a divalent organic bridging group, and

R ^{4 is} a monovalent radical of a heterocyclic 5- or 6-ring compound having at least one protonatable nitrogen atom in the ring,

From 20 to 55% by weight, based on the total weight of the copolymer, of structural units derived from the general formula (II)

wherein

R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ , each independently of one another denote hydrogen or (C 1 -C ₄ ) -alkyl,

Y is a C-C or C-N covalent bond or a -CO-O- or -CO-NH- group, U is a bi- to hexahydric organic bridging group, which may also have one or more heteroatoms, and

a = 1, 2, 3, 4 or 5, and wherein the particles have a mean particle diameter D ₅ o of 100 to 500 μηι, and have a volume swelling degree of 1, 1 to 2.0. In the above definition of the copolymer, the information relating to the proportion of the structural units derived from the formulas (I) and (II) relates to the total weight of the copolymer.

The skilled person understands that if X is a covalent CC, CO or CN bond, X represents exclusively the bond itself and no atoms, ie, if it is a CO or CN bond, comes the O- or the N atom from the radical R ⁴ . The same applies if Y is a covalent bond. If Y is a - CO-O- or -CO-NH group, this may be bonded in any direction, ie also as -O-CO- or -NH-CO- group.

The crosslinked copolymer of the invention is characterized in that it has a comparatively high proportion of incorporated crosslinker derived from the general formula (II) and at the same time a comparatively high proportion of sorbent groups derived from the general formula (I).

Preferably, the proportion of the structural units is derived from the general formula

(I) 50 to 70 wt .-%, based on the total weight of the copolymer.

(II) 30 to 50 wt .-%, based on the total weight of the copolymer.

Preference is given to copolymers according to the invention in which R ¹ , R ² and R ^{3 are} hydrogen or one of these groups is methyl and two of these groups are hydrogen, X is a covalent CC, CO or CN bond or is a methylene group, and R ⁴ is a monovalent radical of a heterocyclic 5- or 6-ring compound, with 1, 2, 3 or 4, preferably one or two nitrogen atoms in the ring, of which at least one is a protonatable nitrogen atom.

Very particular preference is given to copolymers according to the invention in which X is a covalent CN bond and R ^{4 is} an imidazolyl radical.

Further preferred copolymers according to the invention contain structural units derived from the general formula (II) in which R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ^{10 are} each hydrogen or two of these groups are methyl and the remaining of these groups are hydrogen, Y is a covalent CC bond or is a -CO-O- group, U is a divalent or trivalent aliphatic hydrocarbon group, in particular CrC ₆ - Alkylene, or a di- or trihydric carbocyclic-aromatic hydrocarbon group, in particular di- or trihydric phenylene, and a = 1 or 2.

Further very particularly preferred copolymers according to the invention contain structural units derived from the general formula (II) in which a = 1, R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ^{10 are} each hydrogen, and U is Ce alkylene or phenylene.

Very particular preference is given to copolymers in which the structural units derived from the general formula (I) are N-vinylimidazole and the structural units derived from the general formula (II) are divinylbenzene.

Preferably, the particles of the polymer according to the invention have an average particle diameter D ₅ o of 150 to 300 μηι.

Preferably, the volume swelling degree is 1, 2 to 1, 6, more preferably 1, 2 to 1, 5.

Also preferred are those novel copolymers which, in addition to the structural units derived from the general formulas (I) and (II), contain no units of other polymerizable compounds.

The copolymers of the invention are in the form of spherical particles or as a bead polymer and can preferably be prepared by suspension polymerization. The skilled person understands that this is understood to mean not only exactly spherical particles but also substantially spherical particles, wherein a part of the copolymer may also be present in non-spherical form.

In a further aspect, the present invention relates to a process for the preparation of crosslinked copolymers in the form of spherical particles comprising the steps:

A) providing a composition comprising the components

i) water,

ii) at least one protective colloid,

iii) comprising a monomer mixture

(a) 45-80% by weight of structural units derived from the general formula (I), based on the total weight of the monomers in the monomer mixture,

(I)

wherein

X is a covalent C-C, C-O or C-N bond or a divalent organic bridging group, and

20 to 55 wt .-% structural units derived from the general formula (II), based on the total weight of the monomers in the monomer mixture

wherein

R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ , each independently of one another denote hydrogen or (C 1 -C 4) -alkyl,

Y is a C-C or C-N covalent bond or a -CO-O or -CO-NH group,

U is a bi- to hexahydric organic bridging group, which may also have one or more heteroatoms, and

a = 1, 2, 3, 4 or 5, iv) at least one cosmotropic salt in an amount of at least 30% by weight, particularly preferably 60-90% by weight, based on the total amount of the monomers (a) and (b) used,

v) at least one water-immiscible organic solvent, vi) optionally at least one radical initiator;

(B) stirring the composition obtained in step (A);

(C) Radical polymerization of the monomers (a) and (b).

The components of the composition according to step (A) can be used in customary quantities known to the person skilled in the art.

Suitable cosmotropic salts of component (iv) are customary cosmotropic salts known to the person skilled in the art.

Preferably, the cosmotropic salt is selected from the group consisting of fluorides, chlorides, sulfates, hydrogen phosphates and acetates or mixtures of at least two of these salts, more preferably selected from the group consisting of fluorides, chlorides, sulfates, hydrogen phosphates and acetates of sodium, potassium or ammonium or mixtures of at least two of these salts and most preferably from the group consisting of sodium chloride, sodium sulfate, potassium chloride, potassium sulfate or a mixture of at least two of these salts.

The cosmotropic salt may preferably be used in an amount of from 30% by weight to 120% by weight, based on the total amount of the monomers (a) and (b) used. The cosmotropic salt is particularly preferably used in an amount of 60 to 90% by weight, based on the total amount of the monomers (a) and (b) used.

The radical polymerization takes place according to the invention preferably in the form of a suspension polymerization in aqueous phase in which monomer droplets are suspended. The monomer droplets are produced by agitating the composition in step (B) wherein the components of the composition in step A) can be provided simultaneously or at least partially sequentially, for example in the form of an aqueous receiver containing the protective colloid and monomers or the protective colloid and to which the monomers are added while stirring. By type of stirrer, reactor geometry and by the selection of the Stirring speed or the protective colloid can be adjusted size and size distribution of the monomer droplets and thus size and size distribution of the polymerized particles.

As the protective colloid, it is possible to use all polymeric substances known to the person skilled in the art for this purpose. Examples of these are cellosolve derivatives, such as cellulose ethers, e.g. Hydroxyethyl cellulose, polyvinyl alcohol or polyvinylpyrrolidone. Preferably, the protective colloid used is polyvinyl alcohol.

The initiation of the polymerization takes place after preparation of the monomer suspension by measures known to the person skilled in the art, such as irradiation of high-energy radiation and / or by addition of a radical polymerization initiator which initiates the polymerization at elevated temperatures, e.g. initiated by more than 40 ° C.

The free radical initiator may already be present in the composition at the beginning of the process and is activated by the temperature increase or by energetic radiation or the temperature of the composition stirred according to step (B) is increased and the radical initiator is then added to the composition. The addition of several portions of radical initiator is possible. These additions may extend over the entire duration of the polymerization.

Further, during the polymerization, further monomer or monomer mixture may be added to the reaction mixture.

Preferably, the free-radical polymerization is carried out at temperatures of 60 to 140 ° C, preferably at 80 to 95 ° C.

The radical polymerization can be carried out under normal pressure, under reduced pressure or under elevated pressure. The free radical polymerization is preferably carried out under atmospheric pressure.

In a particularly preferred process variant, the monomer derived from the general formula (I) is N-vinylimidazole and the monomer derived from the general formula (II) used is divinylbenzene.

The copolymer according to the invention contains structural units derived from one or more crosslinkers and structural units derived from one or more, one polymerizable olefinic group and in the ring at least one protonatable nitrogen atom containing heterocyclic 5- or 6-ring compound and optionally structural units of one or more other polymerizable compounds.

By "structural units" is meant the groups randomly distributed in the copolymer which are formed from the polymerizable monomeric compounds used to prepare the copolymer.

The polymerizable olefinic group of the heterocyclic 5- or 6-ring compound having at least one protonatable nitrogen atom in the nucleus is usually directly, but optionally also indirectly, e.g. via an oxygen or sulfur atom bonded to the nucleus and has the general formula (I) described above.

Preferred monomers of general formula (I) are those in which R ¹ , R ² and R ^{3 are} each independently. Is hydrogen or (C 1 -C 4) -alkyl, in particular hydrogen and a group thereof are methyl and very particularly all of the radicals R ¹ , R ² and R ^{3 are} hydrogen and X is -O- or -S- or a covalent CC-, CO - or CN bond, preferably a covalent CC, CO or CN bond.

The radical R ^{4 of} the heterocyclic 5- or 6-ring compound may have, for example, one, two, three or four nitrogen atoms, of which at least one must be protonatable; The heterocyclic ring may optionally also contain another heteroatom or several, for example 1, 2 or 3, other heteroatoms, in particular oxygen and / or sulfur. The heterocyclic 5-membered ring can be saturated, partially saturated or unsaturated and represent, for example, an imidazoline, oxazoline, thiazole, oxadiazole, triazole or tetrazole and may optionally also contain one or more, for example 1, 2 or 3, (C 1 -C 4) -alkyl and / or (C ₂ -C 4) -hydroxyalkyl groups. In the case of a heterocyclic 6-membered ring, it may be saturated, partially saturated or unsaturated and may represent, for example, a pyridine or pyrimidine, pyrazine, pyridazine and may optionally contain one or more, for example 1, 2 or 3 (C 1 -C 4) alkyl and / or or (C ₂ -C 4) -hydroxyalkyl groups.

Polymerizable olefinic groups in the monomer of the formula I are in particular the vinyl, allyl, methallyl or isopropenyl group.

As a polymerizable olefinic group of the heterocyclic-5-ring compound of the formula (I), there may be mentioned, for example: 1-vinyl-1,2,3-triazole; 1-vinyl-1, 2,4-triazole; 4-vinyl-1,2,3-triazole; 5-vinyl-1,2,3-triazole; 1-vinyl-1,2,3,4-tetrazole; 2-vinyl-1,2,3,4-tetrazole; 2-allyl-1,2,3,4-tetrazole; 1-allyl-1,2,3,4-tetrazole; 1-methyl-5-vinyl-1,2,3,4-tetrazole; 2-methyl-5-vinyl-1,2,3,4-tetrazole; 3-vinyl-1,2,4-oxadiazole; 3-vinyl-5-methyl-1,2,4-oxadiazole; 3-iso-propenyl-1, 2,4-oxadiazole; 2-isopropenyl-1, 3,4-oxadiazolin-5-one; 3-isopropenyl-1, 2,4-oxadiazole; 3-isopropenyl-5-methyl-1,2,4-oxadiazole; 2-vinyloxazoline; 2-isopropenyl-oxazoline; 2-vinyl-3-methyl-oxazolidine; 2-vinyl thiazole; 4-vinyl thiazole; 1-vinyl-2-imidazoline; 2-vinyl-4- (or 5 -) -methyl-2-imidazoline; 1-vinyl-2-methyl-2-imidazoline; 1-vinylimidazole; 1-methyl-2-vinyl-imidazole; 1-vinyl-2-methylimidazole; 1-vinyl-4- (2-hydroxyethyl) -imidazole; pyrrole; 2-isopropenyl-2-imidazoline; 2-vinyl-3-methyl-2-imidazoline and 1-vinyl-2,4-dimethyl-imidazole.

The crosslinker of the formula (II) links together n-polymer chains, where n is a number equal to or greater than 2. In particular, n = 2, 3 or 4, preferably 2.

Suitable crosslinkers are compounds of the formula (II) which contain 2-3 polymerizable radicals, in particular the formulas CH ₂ CHCH-, CH ₂ CHCH-CH ₂ - or CH ₂ CHCH (R ⁷ ) -CO-, in the molecule R ^{7 is} hydrogen or (Ci-C4) alkyl, in particular hydrogen or methyl. Examples of such crosslinkers are: triallyl cyanurate, triallyl phosphate, Ν, Ν ', Ν "- tris-acryloyl perhydrotriazine, 1, 2,3-trivinyl oxypropane, tetrasilyl-oxyethane, pentaallyl sucrose, triallylamine, ethenphosphonic acid di-allyl ester, ethylene glycol-1, 2- to (ethenphosphonsäureester), also generally compounds of the formulas IV, V or VI

(CH ₂ = CH) _n -R ¹⁷ (IV),

(CH ₂ = CH-CH ₂ ) _n -R ¹⁸ (V),

(CH ₂ = C (R ⁷ ) -CO) _n -R (VI),

where R ^{7 has} the meaning already mentioned, n = 2, 3 or 4, preferably 2, R ^{18 is} the residue of a di-, tri-, tetra- or polycarboxylic acid formed by removal of n acidic H atoms,

R ^{19 is} the residue of a di-, tri-, tetra- or polyol formed by removal of n hydroxyl-hydrogen atoms, and

R ^{17 is} the radical of an aliphatic, aromatic or heteroaromatic hydrocarbon formed by removal of n hydrogen atoms.

Suitable compounds of the formulas (V) and (VI) are, for example: triallyl tricarballylate, triallyl aconitate, triallyl citrate, triallyl trimesinate, triallyl trimellitate, trimethylolpropane tri- acrylate and methacrylate, diallyl oxalate, divinyl phthalate, diallyl maleate, fumarate, adipate, pentaerythritol tetra-acrylate and methacrylate, pentaerythritol tri-acrylate and methacrylate.

Examples of crosslinkers of the formula (IV) are divinylbenzenes and trivinylbenzenes.

Divalent crosslinkers and water-soluble crosslinkers are preferred. Suitable water-soluble crosslinkers are, in particular, derivatives of acrylic or methacrylic acid, such as e.g. N, N'-methylene-bis-acrylamide, Ν, Ν'-methylene-bis-methacrylamide, N, N'-methylene-bis- (N-hydroxymethyl-methacrylamide), N, N'-bis (methacroyl) - aminoacetic acid, N, N'-bis (acryloyl) aminoacetic acid, 1, 2 bis (acrylamido) -1, 2-dihydroxy-ethane, 1, 2-bis (methacrylamido) -1, 2-dihydroxyethane, 1, 2-bis (N-hydroxymethyl-methacrylamido) -1,2-dihydroxy-ethane, 1,2-bis- (N-methoxymethyl-methacrylamido) -1,2-dimethyloxyethane, 1,6-bis (arcrylamido) - hexane, 1,6-bis (methacrylamido) hexane, 2-methyl-1,4-bis (acrylamido) butane ("isovalerylidenebisacrylamide"), 2-methyl-1,4-bis ( methacrylamido) butane ("isovaleryldenebismethacrylamide").

Further preferred bivalent crosslinkers are divinylbenzenes, especially 1, 4-divinylbenzene, ethylene glycol diacrylate or dimethacrylate, diallylamine, divinylpyridines, divinylchinolines, divinyl ketone, divinylsulfone, dimethylenglycol diacrylate or dimethacrylate, butylene glycol diacrylate or dimethacrylate, diallyl oxalate, diallyl maleate, fumarate, adipate, phthalate, divinyl phthalate, diallylmelamine.

Also beneficial are combinations of two or more surfactants, e.g. of N, N-methylene-bis-acrylamide / Ν, Ν-bis-acryloyl-aminoacetic acid; N, N'-methylene-bis-acrylamide / isovaleryl-bis-acrylamide; N, N'-methylene-bis-acrylamide / ethylene glycol-1,2-bis (ethenphosphonic acid ester).

The copolymers according to the invention may also contain units of polymerisable silicon and / or boron-organic compounds, in particular if these compounds act as units of n-valent crosslinking agents.

Suitable n-valent crosslinkers are also those compounds which contain only one or two polymerizable olefinic double bonds in the molecule, but which can additionally link together (n-1) or (n-2) polymer chains due to secondary reactions. Such crosslinkers are, for example, silanes containing alkoxy groups, in which the alkoxy groups are hydrolyzed in an aqueous medium as an intermediate to Si-OH groups. Two such silanol groups then cause condensation of and formation of a siloxane bond Si-O-Si the linkage of two chains. Suitable polymerizable silicon and boron-organic compounds are, for example, acrylic or methacrylic acid-3- (trimethoxy-silyl) -propyl esters, acrylic or methacrylic acid-3- (triethoxy-silyl) -propyl esters, acrylic or methacrylic acid -3- (tri (methoxyethoxy) silyl) propyl ester, acrylic or methacrylic acid 3- (tri (methoxyethoxyethoxy) silyl) propyl ester, acrylic or methacrylic acid 3- (di (methoxy) methyl -silyl) propyl ester, acrylic or methacrylic acid 3- (di (ethoxy) ethylsilyl) propyl ester, vinyltri-ethoxy-silane, vinyltrimethoxy-silane, vinyltri -allyloxy-silane, allyl-tri-allyloxy-silane, vinyl-methyl-di-ethoxy-silane, vinyl-methyl-dimethoxy-silane, vinyl-tri-acetoxy-silane, vinyl-tri- (methoxyethoxy) -silane, 1 , 3-Di-vinyl-1,1,3,3-tetra-methyldisiloxane, 1,3-di-vinyl-1,1,3,3-tetra-methyldisilazane, CH ₂ = CH-COO- (CH ₂₎ 3- (Si (CH3) p-0) 3-Si (CH3) 2-CH 3) ₂ -0-CO-CH = CH _2, CH ₂ = CH-COO- (CH ₂₎ ₃ -COO- (CH 2) ₃ - (Si (CH 3) ₂ -O) p-Si (CH ₃ ) ₂ - (CH ₃ ) ₂ -O-CO-C (CH ₃ ) = CH ₂ where p is a Number from 1 to 20, in particular a number from 1 to 10, means, CH ₂ = CH-CH ₂ -NH-SiH (CH) ₃ -N (CH ₂ CH = CH ₂ ) - SiH (CH ₃ ) -NH- CH ₂ -CH = CH ₂ , triallyl-boric acid ester, trimethallyl-boric acid ester. The polymerisable organosilicon or boron-organic compounds can also, if the prerequisites for this are present, be used as n-valent crosslinkers or at the same time as polymerizable silicon or boron-organic compounds and as crosslinkers.

The polymerizable monomers can generally be used in commercial form, ie without prior purification.

The crosslinked copolymer particles according to the invention are preferably prepared by the suspension polymerization in the aqueous phase described above.

The aqueous phase used in the copolymerization consists wholly or for the most part of water. Optionally, up to 20 wt .-%, based on the total amount of the reaction mixture, of water-miscible substances are used, for example, aliphatic Ci-C4 alcohols.

In the suspension polymerization process, a generally 15 to 80% solution of the monomers is prepared in an inert hydrophobic liquid, for example in aromatic and / or aliphatic hydrocarbons. However, liquid monomers can be used as such or solid monomers are dissolved in liquid monomers and added to the reaction mixture. The monomer solution is added in whole or in part to the aqueous receiver and therein in the presence of a protective colloid such as polyvinyl alcohol, usually at temperatures of 20 to 40 ° C by stirring suspended. The copolymerization into polymeric products in bead form is carried out at the temperatures described above.

The copolymerization is carried out in a manner known per se, e.g. triggered by UV light or other high-energy radiation, but usually by a soluble in the monomer mixture, radical-providing initiator. Suitable initiators are e.g. Benzoyl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, methyl ethyl ketone peroxide, lauroyl peroxide, tert-butyl perbenzoate, tert-butyl diperphthalate, azodiisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2-phenyl-azo-2,4-dimethyl 4-methoxy-valeronitrile, 2-cyano-2-propyl-azoformamide, azodiisobutyramide, dimethyl, diethyl or dibutylazobis methylvalerate. It is also possible to use mixtures of initiators.

Based on the total amount of monomer, about 0.01 to 4 wt .-%, preferably 0.1 to 2 wt .-% initiator can be used. The free radical initiator may be added to the water and / or oil phase. Preferably, the free radical initiator is added to the water phase.

The protective colloid must be soluble or dispersible in the aqueous phase and prevents coalescence of the finely divided dispersed organic phase.

Suitable protective colloids are the above-enumerated high molecular weight organic substances.

The protective colloid or a mixture of different protective colloids are generally used in amounts of at least 0.5% by weight, preferably 2 to 20% by weight, based on the total amount of monomers.

The volumes of the disperse organic phase and the aqueous phase preferably behave as 1: (2 to 50), more preferably 1: (2-5), most preferably 1: 3.

The dispersion of the organic monomers in the aqueous phase treated with protective colloid takes place in a manner known per se, preferably by vigorous stirring.

It is expedient to carry out the copolymerization in the absence of oxygen. This can be done in a known manner by flushing or passing an inert gas, such as nitrogen. The copolymerization is usually completed after 0.5 to 100 h, preferably after 1 to 20 h. After completion of the copolymerization, the resulting crosslinked copolymer is separated, washed with water and / or organic solvent and dried.

In the suspension polymerization so-called regulators can be added to the polymerization batches. These are those compounds which influence the molecular weight of the copolymers produced. Suitable known regulators are e.g. Alkylmercaptans, such as e.g. Dodecylmercaptan and tert-dodecylmercaptan, isooctylthioglycolate and some halogen compounds, e.g. Carbon tetrachloride, chloroform and methylene chloride.

After several hours of reheating of the obtained by the process of suspension copolymerization in the temperature range of 50 to 130 ° C, preferably 70 to 100 ° C, the quality properties of the crosslinked copolymers can be further improved.

The crosslinked copolymers according to the invention prepared in this way, in the form of spherical particles or fine beads, are dried after separation from the reaction mixture and obtained in solid form.

The crosslinked copolymers according to the invention are obtained in the form of spherical particles or beads, which typically have diameters in the range from 40 to 500 μm, in particular from 100 to 300 μm. The average particle diameter D ₅ o of these particles is 100 to 500 μηι, preferably 150 to 300 μηι. The mean value is calculated from the sum distribution curve of the measured particle diameter.

In addition, the copolymer particles according to the invention are characterized by an extremely low volume swelling degree of 1.1 to 2.0, in particular from 1.2 to 1.6, more preferably 1.2 to 1.5. The volume swelling rate is determined by filling 1 ml of the dry copolymer in a 10 ml graduated cylinder and then making up to 10 ml with a 2% strength by weight solution of an organic acid, preferably lactic acid. After 24 hours the resin bed volume is read. The volume swelling Qv is the quotient of the volume of the swollen copolymer and the volume of the dry copolymer. It is believed that the high level of crosslinking in the copolymer particles accounts for this surprisingly low volume swell. In addition, the copolymer according to the invention by a surprisingly high degree of incorporation (quotient of molar amount of the monomer of the general formula I in the copolymer and the amount of the same monomer in the reaction mixture) of> 70%, preferably> 75%, more preferably at least 80%, completely particularly preferably 80-90% of sorption-active monomers (corresponding to compounds of the formula I).

A further subject of the present invention is a copolymer obtainable by a process as described above.

The copolymer particles according to the invention are outstandingly suitable as sorbents, in particular as sorbents for acidic substances from solvents.

In the context of the present invention, acidic substances are understood as meaning substances of the general formula HA which can dissociate in a solvent of the general formula Lm (usually a water or solvent mixture) into LmH ⁺ and an acid radical A ^" Examples of suitable acidic organic substances are carboxylic acids, sulfonic acids, mineral acids, aminocarboxylic acids, aminodicarboxylic acids, thiocarboxylic acids, phenols, thiophenols, mercaptans, acidimides, acid sulfimides, etc. The abovementioned acidic organic substances can also be substituted and / or contain several identical or different acidic groups in the molecule.

Suitable aliphatic and aromatic mono-, di- and polycarboxylic acids, hydroxy and ketocarboxylic acids are e.g. Formic acid, acetic acid, propionic acid, n-butyric acid, i-butyric acid, n-valeric acid, trimethylacetic acid, caproic acid, n-heptanoic acid, caprylic acid, capric acid, pelargonic acid, stearic acid, tallow fatty acid, fluoroacetic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid, dichloroacetic acid, 2-chloropropionic acid, Glycolic, lactic, methoxyacetic, thioglycolic, cyanoacetic, glyoxylic, malonic, acrylic, methacrylic, vinylacetic, phenylacetic, oxalic, succinic, glutaric, adipic, maleic, fumaric, phthalic, isophthalic, terephthalic, citric, malic, benzilic, aconitic, trimesic, Benzoic, cinnamic, mandelic, tartaric, salicylic, acetoacetic, hydroxybenzoic, gallic, dihydroxybenzoic.

Suitable aminocarboxylic acids and aminodicarboxylic acids are, in particular, alpha-aminocarboxylic acids and alpha-aminodicarboxylic acids, for example glycine, alanine, valine, leucine, isoleucine, methionine, proline, phenylalanine, serine, threonine, cysteine, tyrosine, aspartic acid, Glutamic acid, hydroxyglutamic acid, furthermore, in particular 6-aminopenicillan and aminocephalosporanic acid.

Suitable mineral acids are e.g. Sulfuric acid, phosphoric acid, phosphorous acid, hydrochloric acid.

Suitable sulfonic acids are e.g. Benzenesulfonic acid or naphthalene-1 - or 2-naphthalene or benzene-di-sulfonic acids.

Also suitable are thiophenol., M-thiocresol, 2-bromothio-p-cresol, ethanethiol, phenylmethanethiol, 1,4-butanedithiol, 4-mercapto-2-pyridinecarboxylic acid, 2,3-dimercaptosuccinic acid, Dithioacetic acid, thioacetic O-acid, thioacetic S-acid, phthalimide, succinimide, benzenesulfimide.

The copolymers according to the invention are preferably suitable for the sorption of carboxylic acids, in particular from their aqueous solutions.

The copolymers of the invention have in the sorption of carboxylic acids exceptionally high sorption capacity at the same time less swelling in solvents. The sorption can be carried out in a manner known per se. In general, the column or fixed bed method is used, in which the sorbent is filled in a column, which is then flowed through by the solvent containing one or more acidic substances until the capacity of the exchanger is exhausted.

Subsequently, the desorption of the sorbed acidic substances with the aid of organic solvents, optionally in admixture with water, such. an alcohol such as methanol, ethanol, i-propanol, n-butanol, a ketone such as acetone, methyl ethyl ketone, diethyl ketone, an ester such as methyl or ethyl acetate, ethyl acetate, ethyl acetate, dimethyl carbonate, an ether such as methylene chloride; Tetrahydrofuran, dioxane, ethylene glycol di-methyl or di-ethyl ether. Alternatively, desorption of the sorbed acidic substances with water is also possible.

The temperature is in this case at 20-90 ° C, preferably at 40-60 ° C.

The desorption with dimethyl carbonate leads at suitable temperatures, pressures and residence times to the formation of the methyl ester of the acidic substances. The desorbed acidic substances or their esters can be used for other purposes.

The sorption and desorption of acidic substances with the aid of the copolymer particles according to the invention can also be carried out by other known sorption methods, e.g. be carried out by continuous processes with moving bed by the fluidized bed process or in batch mode.

The invention also relates, in a further aspect, to the use of the above-described crosslinked copolymers in the form of spherical particles for the separation of acidic substances from aqueous compositions.

These may preferably be fermentation broths, which optionally contain solids in addition to the acidic substances.

The above-described crosslinked copolymers are preferably used in the form of spherical particles for separating off organic acids from solvents, in particular water, particularly preferably mono- or dicarboxylic acids, very particularly preferably hydroxycarboxylic acids or dicarboxylic acids, and in particular malic acid, glycolic acid, isocitric acid, Mandelic acid, lactic acid, tartronic acid, tartaric acid, citric acid, beta-hydroxybutyric acid, mevalonic acid, salicylic acid, oxalic acid, acetic acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, pimelic acid, suberic acid, fumaric acid, itaconic acid, glucaric acid, gluconic acid, glucuronic acid, aminocarboxylic acid, Hydroxypropionic acid, acrylic acid, malonic acid, alpha-hydroxyglutaric acid, beta-hydroxyglutaric acid, glyceric acid.

But also comes the separation of fatty acids into consideration, such as sebacic acid, dodecanedioic acid, erucic acid or ricinoleic acid.

In a particularly preferred application, the crosslinked copolymer particles according to the invention are used in a process analogous to the process according to DE 10 201 1 120 632 A1.

For this purpose, a fermentation broth is purified by separating off the biomass and any solids present and optionally subjected to filtration, and the purified fermentation broth is treated with spherical particles of the invention crosslinked copolymers brought into contact to separate the acidic substances by adsorption.

Another object of the present invention is the use of copolymers according to the invention for the separation of heavy metal ions or as a stationary phase in chromatographic columns, preferably as a stationary phase in the SMB (Simulated moving bed) chromatography.

Another object of the present invention is the use of copolymers according to the invention for the separation of acidic substances, preferably carboxylic acids, and subsequent esterification of the acidic substances sorbed on the polymer, preferably carboxylic acids.

Further objects of the present invention are a process for the separation of acidic substances from aqueous compositions using the copolymers according to the invention, a process for the separation of heavy metal ions using the novel copolymers, a chromatography process using the novel copolymers as stationary phase in chromatographic columns, preferably as stationary Phase in the SMB (Simulated moving bed) chromatography, and methods for the separation of acidic substances, preferably carboxylic acids, and subsequent esterification of the acidic substances sorbed on the polymer, preferably carboxylic acids.

In Figure 1, the density distribution curve of the particle diameter of the copolymer obtained in Example 1 is shown.

In Figure 2, the cumulative distribution curve of the particle diameter of the copolymer obtained in Example 1 is shown.

FIG. 3 a shows a scanning electron micrograph of the copolymer obtained according to Example 1, which shows its particulate structure.

FIG. 3b shows a scanning electron micrograph of the copolymer obtained according to Example 1, which shows its porous structure. In the following the invention will be explained by means of examples. These explanations are merely exemplary and do not limit the general inventive concept. The given percentages are by weight.

Example:

As chemicals were used:

N-vinylimidazole (BASF)

Divinylbenzene (DVB) as an 80% Isomenengemisch (Aldrich)

Polyvinyl alcohol (PVA) 86,000 g / mol, 99-100% hydrolyzed (Acros Organics)

Toluene, technical and

2,2-Azoisobutyronitrile (AIBN) (Acros Organics). example 1

In a 500 ml three-necked flask equipped with reflux condenser, KPG stirrer and nitrogen inlet, at room temperature, 0.36 g of polyvinyl alcohol (PVA, 86,000 g / mol, 99-100% hydrolyzed), 360 mL of dist. Submitted H2O and 54 g NaCl. In a 250 ml round bottom flask, 37.64 g / V vinylimidazole, 22.32 g divinylbenzene, and 1.22 g AIBN were dissolved in 60 mL toluene, purged with N 2 for 15 minutes, and then added to the aqueous phase with stirring. A continuous N 2 stream was passed over the reaction solution. It was stirred for one hour to achieve a stable droplet size. Then it was heated to 80 ° C. After reaching the reaction temperature, the N 2 feed was turned off and polymerized for 20 h. Subsequently, the reaction solution was cooled to room temperature. The polymer beads were isolated and dried.

This gave 47.5 g (about 78%) of a copolymer in the form of spherical particles.

The analysis of this product gave the following values:

N content: 15.68% (determined by elemental analysis)

Vinylimidazole content: 60.7 mol%

Divinylbenzene content: 39.3 mol%

Incorporation of vinylimidazole into the polymer: 86.5%

Bulk density / weight (dry): 0.43 g / ml

Max. Adsorption: 5 g / 10 g of dry copolymer or 5.6 eq / kg (dry copolymer) or 2.4 eq / L (dry copolymer) (based on lactic acid)

Volume swelling Qv 1, 5 (in the presence of 2% by weight of lactic acid)

effective size (D10): 190 μηι

average size (D ₅₀ ): 250 μηι

Uniformity coefficient: 1, 4

Claims

claims:

1 . Crosslinked copolymer in the form of spherical particles containing

(a) 45-80% by weight, based on the total weight of the copolymer, of structural units derived from the general formula (I)

wherein

R ¹ , R ² and R ³ , in each case independently of one another, denote hydrogen or (C 1 -C ₄ ) -alkyl,

X is a covalent C-C, C-O or C-N bond or a divalent organic bridging group, and

wherein

Y is a CC or CN covalent bond or a -CO-O or -CO-NH group, U is a bi- to hexahydric organic bridging group, which may also have one or more heteroatoms, and

a = 1, 2, 3, 4 or 5, and wherein the particles have a mean particle diameter D ₅ o of 100 to 500 μηι, and have a volume swelling degree of 1, 1 to 2.0.

2. The copolymer of claim 1, wherein R ¹ , R ² and R ^{3 are} each hydrogen or one of these groups is methyl and two of these groups are hydrogen, X is a covalent CC, CO or CN bond or a methylene group and R is ^{4 is} a monovalent radical of a heterocyclic 5- or 6-ring compound having 1, 2, 3 or 4, preferably 2 nitrogen atoms in the ring, at least one of which is a protonatable nitrogen atom.

3. A copolymer according to claim 1 or 2, wherein X is a covalent CN bond and R ^{4 is} an imidazolyl radical.

4. A copolymer according to any one of claims 1 -3, wherein R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ^{10 are} each hydrogen or two of these groups are methyl and the remaining of these groups are hydrogen, Y is a covalent CC B is or is a -CO-O- group, U is a divalent or trivalent aliphatic hydrocarbon group, preferably C 1 -C ₆ -alkylene, or a di- or trihydric carbocyclic-aromatic hydrocarbon group, preferably di- or tri-valent phenylene, and a = 1 or 2 is.

5. A copolymer according to any one of claims 1 -4, wherein a = 1, R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ^{10 are} each hydrogen, and U is C 2 -C 6 -alkylene or phenylene.

A copolymer according to any one of claims 1-5, wherein the structural units derived from the general formula (I) is N-vinylimidazole and the structural units derived from the general formula (II) is divinylbenzene.

7. A process for the preparation of crosslinked copolymers according to any one of claims 1 -6 comprising the steps:

A) providing a composition comprising the components

i) water,

ii) at least one protective colloid,

iii) comprising a monomer mixture

45-80% by weight of structural units derived from the general formula (I), based on the total weight of the monomers in the monomer mixture,

wherein

X is a covalent C-C, C-O or C-N bond or a divalent organic bridging group, and

20 to 55 wt .-%, structural units derived from the general formula (II), based on the total weight of the monomers in the monomer mixture,

wherein R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ , each independently of one another denote hydrogen or (C 1 -C 4) -alkyl,

Y is a C-C or C-N covalent bond or a -CO-O or -CO-NH group,

a = 1, 2, 3, 4 or 5, iv) at least one cosmotropic salt in an amount of at least 30 wt .-%, particularly preferably 60-90 wt .-%, based on the total amount of the monomers used (a) and (b)

(B) stirring the composition obtained in step (A);

(C) Radical polymerization of the monomers (a) and (b).

The method of claim 7, wherein the protective colloid comprises polyvinyl alcohol.

9. The method of claim 7 or 8, wherein the cosmotropic salt is selected from the group consisting of fluorides, chlorides, sulfates, hydrogen phosphates and acetates or mixtures of at least two of these salts, preferably from the group consisting of fluorides, chlorides, sulfates, hydrogen phosphates and acetates of sodium, potassium or ammonium or mixtures of at least two of these salts, more preferably selected from the group consisting of sodium chloride, sodium sulfate, potassium chloride, potassium sulfate or a mixture of at least two of these salts.

10. The method according to any one of claims 7-9, wherein the free-radical polymerization at temperatures of 60 to 140 ° C, preferably at 80 to 95 ° C, optionally under elevated pressure.

1 1. A method according to any one of claims 7-10, wherein one or more of the components are provided in degassed form.

12. The method according to any one of claims 7-1 1, wherein one or more of the steps are carried out under inert gas.

13. The method according to any one of claims 7-12, wherein the free-radical polymerization is carried out for a period of 0.5 to 100 hours, preferably from 0.5 to 20 hours.

14. The method according to any one of claims 7-13, wherein as the monomer (a) of the general formula (I) N-vinylimidazole and as the monomer (b) of the general formula (II) divinylbenzene is used.

15. The method according to any one of claims 7-14, wherein the degree of incorporation of the monomer of the general formula (I)> 70%, preferably> 75%, more preferably at least 80%, most preferably 80-90%.

16. A copolymer obtainable by a process according to any one of claims 7-15.

17. A copolymer according to any one of claims 1 -6 or 16, wherein the particles have a mean particle diameter D ₅ o of 150 to 300 μηι.

18. A copolymer according to any one of claims 1 -6 or 16, wherein the volume swelling degree is 1, 2 to 1, 6, preferably 1, 2 to 1, 5.

19. Use of copolymers according to any one of claims 1 -6 or 16 for the separation of acidic substances from aqueous compositions.

20. Use according to claim 19, wherein the aqueous compositions are fermentation broths which optionally contain solids in addition to the acidic substances.

21. Use according to claim 19 or 20, wherein the acidic substances are organic acids, preferably monocarboxylic acids, dicarboxylic acids, hydroxycarboxylic acids or hydroxydicarboxylic acids.

22. Use according to claim 21, wherein the hydroxycarboxylic acid is selected from the group consisting of malic acid, glycolic acid, isocitric acid, mandelic acid, lactic acid, tartronic acid, tartaric acid, citric acid, beta-hydroxybutyric acid, Mevalonic acid, salicylic, oxalic, acetic, maleic, succinic, glutaric, adipic, sebacic, pimelic, suberic, fumaric, itaconic, glucaric, gluconic, glucoronic, aminocarboxylic, 3-hydroxypropionic Hydroxy glutaric acid and glyceric acid.

23. Use according to claim 21, wherein the dicarboxylic acid is selected from the group consisting of oxalic acid, acetic acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, pimelic acid, suberic acid, fumaric acid and itaconic acid, preferably succinic acid.

24. Use of copolymers according to any one of claims 1 -6 or 16 for the separation of heavy metal ions or as a stationary phase in chromatographic columns, preferably as a stationary phase in the SMB (simulated moving bed) chromatography.

25. Use of copolymers according to any one of claims 1 -8 or 16 for the separation of acidic substances, preferably carboxylic acids, and subsequent esterification of the acidic substances sorbed on the polymer, preferably carboxylic acids.