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Abstract

An anion exchange membrane obtainable by curing a curable composition comprising: (a) a monomer of formula (I) (a) AR1-(CH2) n-N + (RaRb)-(CH2) n-AR2 wherein: each n independently has a value of 1 or 2; (i) Ra and Rb are each independently an optionally substituted C1-3 alkyl group or an optionally substituted C2-3 alkenyl group; or (ii) Ra and Rb together with the positively charged nitrogen atom to which they are attached form an optionally substituted 5 or 6 membered ring; or (iii) one of Ra and Rb is an optionally substituted C1-3 alkyl group or an optionally substituted C2-3 alkenyl group, and the other of Ra and Rb together with a group of formula AR1-(CH2) n-N + forms an optionally substituted 5 or 6 membered ring; or (iv) Ra together with a group of formula AR1-(CH2) n-N + forms an optionally substituted 5 or 6 membered ring, and Rb together with a group of formula N +-(CH2) n-AR2 forms an optionally substituted 5 or 6 membered ring; x-is an anion; and AR1 and AR2 each independently comprise an aromatic group; wherein: (I) at least one of AR1 and AR2 comprises a curable ethylenically unsaturated group; (II) the monomer (a) of formula (I) comprises at least two curable ethylenically unsaturated groups; and (III) the anion exchange membrane has an ion exchange capacity (IEC) of less than 1.65 meq / g dry membrane.

Description

[0001] The present invention relates to ion exchange membranes, in particular anion exchange membranes (AEMs), methods for preparing the same and uses thereof.

[0002] Ion exchange membranes are used in electrodialysis, electrolysis, the production of acids and bases, and in many other processes. Typically, the transport of ions through a membrane occurs under the influence of a driving force, such as an electrical potential gradient.

[0003] Some ion exchange membranes contain a porous support that provides mechanical strength. Such membranes are often referred to as "composite membranes" due to the presence of both an ionically charged polymer that discriminates between oppositely charged ions and a porous support that provides mechanical strength.

[0004] To generate acids and bases, BPMs are often used, for example in a process known as bipolar electrodialysis (BPED). BPMs have both a cation layer or anion exchange layer (AEL) and a negative layer or cation exchange layer (CEL), so they have both negatively and positively charged layers.

[0005] During the BPED process, acids and bases are generated at the interface of the BPM via water dissociation reaction (WDR). + and OH - The ions move toward the cathode and anode through the corresponding ion exchange layers, respectively. The BPED process is carried out in a bipolar electrodialysis stack, which contains a monopolar anion exchange membrane and a monopolar cation exchange membrane in addition to the bipolar membrane. In the bipolar electrodialysis stack, the monopolar cation exchange membrane and the monopolar anion exchange membrane are responsible for selectively separating the salt ions in the feed stream according to their charge. The salt anions will then react with the H formed by the WDR. + Combine to form an acid, the salt cation will react with OH - Combine to form a base. For example, if NaCl is used in the feed stream, the monopolar membrane will make Na + With Cl - Separation occurs, whereby NaOH and HCl are formed.

[0006] In order to generate high concentrations of acids and bases, it is important that the monopolar membrane has very high pH stability and high durability (high pH stability and durability increase the lifetime of the membrane). High efficiency of the process of generating acids and bases is also required. This requires the membrane to have very high permselectivity to prevent H + and OH - Ions reach the wrong channel resulting in recombination and thus product loss. Especially for anion exchange membranes, it is difficult to obtain high proton blocking performance at high concentrations due to the small size of protons.

[0007] It is an object of the present invention to provide anion exchange membranes which have high mechanical strength, high stability at very low pH values ​​and high permselectivity at high acid concentrations.

[0008] According to a first aspect of the present invention, there is provided an anion exchange membrane obtainable by curing a curable composition, the curable composition comprising:

[0009] (a) Monomer (a) of formula (I)

[0010] AR 1 -(CH2) n -N + (R a R b )-(CH2) n -AR 2 ,X -

[0011] Formula (I)

[0012] in:

[0013] Each n independently has a value of 1 or 2;

[0014] (i)R a and R b Each independently is an optionally substituted C 1-3 Alkyl or optionally substituted C 2-3 alkenyl; or

[0015] (ii) R a and R b Together with the positively charged nitrogen atom to which they are attached, form an optionally substituted 5- or 6-membered ring; or

[0016] (iii) R a and R b One of the C 1-3 Alkyl or optionally substituted C 2-3 alkenyl, and R a and R b Another AR 1 -(CH2) n -N + together form an optionally substituted 5- or 6-membered ring; or

[0017] (iv) R a AR 1 -(CH2) n -N + The groups together form an optionally substituted 5- or 6-membered ring, and R b With formula N + -(CH2) n -AR 2 The groups together form an optionally substituted 5- or 6-membered ring;

[0018] X - is an anion; and

[0019] AR 1 and AR 2 each independently comprises an aromatic group;

[0020] in:

[0021] (I)AR 1 and AR 2 At least one of the comprises a curable ethylenically unsaturated group;

[0022] (II) the monomer (a) of formula (I) comprises at least two curable ethylenically unsaturated groups; and

[0023] (III) The anion exchange capacity (IEC) of the anion exchange membrane is lower than 1.65 meq / g dry membrane.

[0024] The ion exchange capacity (IEC) of an anion exchange membrane can be measured as follows.

[0025] In this document (including its claims), the verb "to comprise" and its conjugations are used in its non-limiting sense to mean that the items following the word are included, but items not specifically mentioned are not excluded. In addition, reference to an element with the indefinite article "a" or "an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there is one and only one of the element. Thus, the indefinite article "a" or "an" generally means "at least one".

[0026] Preferably, monomer (a) comprises at least two curable ethylenically unsaturated groups, more preferably two and only two curable ethylenically unsaturated groups. Preferably, the curable ethylenically unsaturated groups present in monomer (a) are present in AR 1 and / or AR 2 In a preferred embodiment, AR 1 and AR 2 Each contains one and only one curable ethylenically unsaturated group, and monomer (a) has a total of two curable ethylenically unsaturated groups.

[0027] Curable ethylenically unsaturated groups are capable of reacting with other curable ethylenically unsaturated groups to form covalent bonds therewith, for example, upon application of heat and / or irradiation with light (eg, ultraviolet light or electron beam).

[0028] Preferred curable ethylenically unsaturated groups are vinyl and allyl, with vinyl being most preferred. Vinyl (CH2=CH-) is non-acrylic, ie, the vinyl is not attached to a (C=O)O-group or a (C=O)NH-group.

[0029] The positively charged nitrogen atom (N + ) is non-aromatic, ie, not part of an aromatic heterocycle.

[0030] Preferably, the anion X - Does not react with other components of the curable composition, i.e. X - is inert. X - Preferred anions for X include hydroxide, fluoride, chloride, bromide, iodide, nitrate, thiocyanate, hexafluoroborate, methanesulfonate, trifluoromethanesulfonate, formate and acetate. Most preferably, X - The chloride anion is preferred because this provides the monomer of formula (I) with good solubility and does not significantly increase the molecular weight of the monomer (a) of formula (I).

[0031] Preferably, each n independently has a value of 1. In a particularly preferred embodiment, both n have a value of 1.

[0032] In one embodiment, R a and R b are each independently selected from optionally substituted C 1-3 Alkyl (eg, methyl, ethyl, propyl or isopropyl) and optionally substituted C 2-3 Alkenyl (eg, -CH=CH2 or -CH2CH=CH2).

[0033] In another embodiment, R a and R b Together with the positively charged nitrogen atom to which they are attached they form an optionally substituted 5- or 6-membered ring, such as an optionally substituted pyrrolidinium, pyrrolinium, imidazolinium, piperidinium or morpholinium ring.

[0034] In another embodiment, R a and R b One of the C 1-3 Alkyl or optionally substituted C 2-3 alkenyl, and R a and R b Another AR 1 -(CH2) n -N + The group (where AR 1 and n are as defined above) together form an optionally substituted 5- or 6-membered ring, such as an optionally substituted pyrrolidinium, pyrrolinium, piperidinium or morpholinium ring, in each case having an aromatic ring (such as a benzene ring) fused thereto (preferably the benzene ring has two or more, preferably one, curable ethylenically unsaturated group attached thereto).

[0035] In another embodiment, R a AR 1 -(CH2) n -N + The group (where AR 1 and n are as defined above) together form an optionally substituted 5 or 6 membered ring, R b With formula N + -(CH2) n -AR 2 The group (where AR 2 and n are as defined above) together form an optionally substituted 5 or 6 membered ring.

[0036] Preferred optionally substituted 5 or 6 membered rings are as defined above (an example is 6-azoniaspiro[5.5]undecene ring).

[0037] Preferred optional substituents are curable ethylenically unsaturated groups (as described and preferred above).

[0038] Preferably, AR 1 and AR 2 Each independently comprises a phenyl group or a styryl group. More preferably, AR 1 and AR 2 All are styryl.

[0039] In a preferred embodiment, monomer (a) has formula (II):

[0040]

[0041] Among them, R a , R b and X - As defined above.

[0042] Component (a) optionally comprises one or more than one monomer (a) of formula (I) (more preferably formula (II)), for example a mixture of isomers, wherein the monomers present in AR 1 and / or AR 2 The curable unsaturated groups in the alkylene oxide are in different positions (eg, ortho, meta and / or para).

[0043] Examples of monomers that can be used as monomer (a) include compounds AXL-1 to AX-11 shown below:

[0044]

[0045]

[0046]

[0047] The curable composition preferably comprises 50 to 90 wt % of component (a), more preferably 65 to 85 wt %, especially 69 to 83 wt %.

[0048] In one embodiment, the anion exchange membrane of the first aspect of the present invention comprises at least 1 ppm of monomer (a) (usually due to incomplete curing during membrane formation), preferably at least 10 ppm, in particular at least 100 ppm. Preferably, the anion exchange membrane comprises less than 20,000 ppm of monomer (a), more preferably less than 10,000 ppm.

[0049] The curable composition optionally further comprises a monomer containing a cationic charged group and one and only one curable ethylenically unsaturated group as component (b). Preferably, the curable composition does not contain component (b) or the composition comprises a small amount of component (b), for example, the curable composition preferably comprises 0 to 10% by weight of component (b), more preferably 0 to 7% by weight of component (b).

[0050] In monomer (b), the cationically charged group is preferably a quaternary ammonium group. The one and only one curable ethylenically unsaturated group present in monomer (b) is preferably a vinyl or allyl group, more preferably a vinyl group.

[0051] Component (b) may comprise one or more than one monomer (b) containing a cationically charged group and one and only one curable ethylenically unsaturated group.

[0052] In one embodiment, component (b) has the formula (SM), wherein R 1 , R 2 and R 3 Each independently represents an alkyl group or an aryl group, or R 1 , R 2 and R 3 2 or 3 of them together with the positively charged nitrogen atom to which they are attached form an optionally substituted 5- or 6-membered ring; n3 represents an integer from 1 to 3; and X3 Θ represents an anion, preferably chloride, bromide, iodide or hydroxide.

[0053]

[0054] Examples of component (b) of formula (SM) include the following compounds:

[0055]

[0056] The above components can be prepared as described in, for example, US2016177006.

[0057] The curable composition may optionally further comprise a free radical initiator as component (c). Preferred free radical initiators include thermal initiators, photoinitiators and combinations thereof.

[0058] The curable composition preferably contains 0 to 10% by weight of a free radical initiator, more preferably 0 to 3% by weight. When UV light, visible light or heat is used to cure the curable composition, the curable composition preferably contains 0.001 to 2% by weight, especially 0.005 to 1.5% by weight of a free radical initiator.

[0059] Examples of suitable thermal initiators that can be used as component (c) include 2,2'-azobis(2-methylpropionitrile) (AIBN), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide, 1-[(1-cyano-1-methylethyl)azo]formamide, 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis(N-cyclohexyl-2-methylpropionamide), 2,2'-azobis(2-methyl 2,2'-Azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] hydrate, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis(1-imino-1-pyrrolidinyl-2-ethylpropane) dihydrochloride, 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide} and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].

[0060] Examples of suitable photoinitiators that may be included in the curable composition as component (c) include aromatic ketones, acylphosphine compounds, aromatic onium salt compounds, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azine compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds. Preferred examples of aromatic ketones, acylphosphine oxide compounds, and thio compounds include compounds having a benzophenone main chain or a thioxanthone main chain described in "RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY", pages 77-117 (1993). More preferred examples thereof include α-thiobenzophenone compounds described in JP1972-6416B (JP-S47-6416B), benzoin ether compounds described in JP1972-3981B (JP-S47-3981B), α-substituted benzoin compounds described in JP1972-22326B (JP-S47-22326B), α-substituted benzoin compounds described in JP1972-23664B (JP-S47- 23664B), benzoin derivatives described in JP1982-30704A (JP-S57-30704A), dialkoxybenzophenones described in JP1985-26483B (JP-S60-26483B), benzoin derivatives described in JP1985-26403B (JP-S60-26403B) and JP1987-81345A (JP-S62-81345A), benzoin derivatives described in JP1982-30704A (JP-S57-30704A), dialkoxybenzophenones described in JP1985-26483B (JP-S60-26403B), benzoin ether described in JP1989-34242B (JP H01-34242B), U.S. Pat. No. 4,318,791A and EP0284561A1, p-bis(dimethylaminobenzoyl)benzene described in JP1990-211452A (JP-H02-211452A), JP1986-194062A (JP S61-194062A) and EP0284561A1. Thio-substituted aromatic ketones described in JP1990-9597B (JP-H02-9597B), acylphosphine sulfides described in JP1990-9596B (JP-H02-9596B), thioxanthones described in JP1988-61950B (JP-S63-61950B), and coumarins described in JP1984-42864B (JP-S59-42864B). In addition, photoinitiators described in JP2008-105379A and JP2009-114290A are also preferred.In addition, a photoinitiator described on pages 65 to 148 of "Ultraviolet Curing System" by Kato Kiyomi (published by Research Center Co., Ltd. in 1989) can be used.

[0061] Particularly preferred photoinitiators include Norrish Type II photoinitiators having an absorption maximum at a wavelength greater than 380 nm when measured in one or more of the following solvents at a temperature of 23° C.: water, ethanol and toluene. Examples include xanthene, flavin, curcumin, porphyrin, anthraquinone, phenoxazine, camphorquinone, phenazine, acridine, phenothiazine, xanthone, thioxanthone, thioxanthene, acridone, flavonoid, coumarin, fluorenone, quinoline, quinolone, naphthoquinone, quinolone, arylmethane, azo, benzophenone, carotenoid, anthocyanin, phthalocyanine, dipyrrin, squarine, stilbene, styryl, triazine or anthocyanin derived photoinitiators.

[0062] Optionally, the curable composition further comprises as component (d) a monomer free of cationically charged groups, preferably comprising at least two curable ethylenically unsaturated groups.

[0063] Preferably, the curable composition comprises 0 to 5 wt% of component (d).More preferably, the curable composition does not contain component (d).

[0064] The curable composition preferably further comprises a solvent as component (e). The solvent is preferably an inert solvent. The inert solvent does not react with any other component of the curable composition. In a preferred embodiment, component (e) comprises water and an optional organic solvent, particularly in the case where a portion or all of the organic solvent is miscible with water. Water can be used to dissolve components (a) and (b), and may also be used to dissolve component (c), and the organic solvent can be used to dissolve any organic component present in the curable composition.

[0065] Component (e) can be used to reduce the viscosity and / or surface tension of the curable composition. In a preferred embodiment, the curable composition comprises 10 to 40 wt%, in particular 20 to 30 wt% of component (e).

[0066] Examples of inert solvents that can be used as component (e) or in component (e) include water, alcohol solvents, ether solvents, amide solvents, ketone solvents, sulfoxide solvents, sulfone solvents, nitrile solvents and organophosphorus solvents. Examples of alcohol solvents that can be used as component (e) or in component (e) (especially in combination with water) include methanol, ethanol, isopropanol, n-propanol, n-butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol and mixtures containing two or more thereof. In addition, preferred inert organic solvents that can be used in component (e) include dimethyl sulfoxide, dimethylimidazolidinone, sulfolane, N-methylpyrrolidone, dimethylformamide, acetonitrile, acetone, 1,4-dioxane, 1,3-dioxolane, tetramethylurea, hexamethylphosphoramide, hexamethylphosphoric triamide, pyridine, propionitrile, butanone, cyclohexanone, tetrahydrofuran, tetrahydropyran, 2-methyltetrahydrofuran, ethylene glycol diacetate, cyclopentyl methyl ether, methyl ethyl ketone, ethyl acetate, γ-butyrolactone and a mixture comprising two or more thereof.

[0067] The molar fraction of component (a) relative to all curable compounds present in the curable composition is preferably at least 0.90, more preferably at least 0.95. It is preferred that the proportion of component (a) relative to all curable compounds present in the curable composition is high in order to obtain a membrane with a high crosslink density and thus a high permselectivity. The molar fraction of component (a) relative to all curable compounds present in the curable composition is preferably up to 1.0.

[0068] The mole fraction of component (a) relative to all curable compounds present in the curable composition can be calculated by dividing the molar amount of component (a) by the sum of the molar amounts of all curable compounds present in the curable composition. Alternatively, the mole fraction can be determined by measuring extractables from anion exchange membranes, for example as described on page 19 of WO2022162083.

[0069] Preferably, the anion exchange membrane of the present invention has an ion exchange capacity (IEC) of at least 1.1 meq / g dry membrane, more preferably at least 1.2 meq / g dry membrane, when measured by the method described below. Such IEC can provide an anion exchange membrane with low electrical resistance.

[0070] Preferably, the anion exchange membrane of the present invention has an IEC of less than 1.61 meq / g dry membrane when measured by the method described below. Such IEC can provide an anion exchange membrane that does not swell too much, thus maintaining good permselectivity during use.

[0071] The anion exchange membrane of the present invention preferably further comprises a porous support.

[0072] As the example of the porous carrier that can be used, weaving or nonwoven synthetic fabric and extruded film can be mentioned.Example includes wet and dry nonwoven materials, spunbond and meltblown fabrics and nanofiber webs made of, for example, polyethylene, polypropylene, polyacrylonitrile, polyvinyl chloride, polyphenylene sulfide, polyester, polyamide, polyaryletherketone (for example, polyetheretherketone) and copolymers thereof.Porous carrier can also be porous membrane, for example, polysulfone, polyethersulfone, polyphenylene sulfone, polyphenylene sulfone, polyimide, polyetherimide (polyethermide), polyamide, polyamideimide, polyacrylonitrile, polycarbonate, polyacrylate, cellulose acetate, polypropylene, poly (4-methyl-1-pentene), polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene and polychlorotrifluoroethylene film and derivatives thereof.

[0073] The average thickness of the porous support is preferably 10 to 800 μm, more preferably 15 to 300 μm, particularly 20 to 150 μm, more particularly 30 to 130 μm, for example about 60 μm or about 100 μm.

[0074] Preferably, the porous support has a porosity of 30 to 95%, more preferably 60 to 75%, wherein (in the final membrane) the pores are filled with anion exchange polymer obtained from the solidified composition, i.e. the membrane preferably comprises 25 to 40% by volume of porous (uncharged) support material and 75 to 60% by volume of anion exchange polymer material (i.e. the solidified composition of the first aspect of the invention). Prior to making the membrane, the porosity of the support can be measured by a porometer (e.g. Porolux from IB-FT GmbH, Germany). TM 1000) to measure.

[0075] The porous support (when present) may be treated to modify its surface energy, for example to a value above 45 mN / m, preferably above 55 mN / m. Suitable treatments include corona discharge treatment, plasma glow discharge treatment, flame treatment, ultraviolet light irradiation treatment or chemical treatment, for example to improve the wettability of the porous support and the adhesion to the anion exchange membrane.

[0076] Commercially available porous supports are available from a number of sources, for example from Freudenberg Filtration Technologies (Novatexx materials), Lydall Performance Materials, Celgard LLC, A Porous Inc., SWM (Conwed Plastics, DelStar Technologies), Teijin, Hirose, Mitsubishi Paper Mills Ltd, and Sefar AG.

[0077] Preferably, the porous support is a porous polymer support.Preferably, the porous support is a woven or non-woven synthetic fabric or an extruded membrane that does not contain covalently bonded ionic groups.

[0078] Preferably, the average thickness of the anion exchange membrane of the present invention is 15 μm to 600 μm, more preferably 50 μm to 450 μm, and particularly 60 to 240 μm.

[0079] According to a second aspect of the present invention there is provided a method of preparing an anion exchange membrane comprising curing a curable composition as defined (and preferred) in relation to the first aspect of the present invention.

[0080] The method of the second aspect of the present invention preferably comprises the following steps:

[0081] i. providing a porous carrier;

[0082] ii. impregnating the porous support with the curable composition; and

[0083] iii. curing the curable composition;

[0084] wherein the curable composition is as defined above.

[0085] The curable composition may be cured by any suitable method, including thermal curing, photocuring, electron beam (EB) irradiation, gamma ray (gamma) irradiation, and combinations thereof.

[0086] Preferably, the method of the second aspect of the present invention comprises a first curing step and a second curing step (dual curing). Dual curing is preferred because it increases the crosslinking density of the resulting anion exchange membrane, thereby improving the permselectivity.

[0087] In a preferred embodiment of the method of the second aspect of the present invention, the curable composition is cured in the following manner: first, for example, by irradiating the curable composition with ultraviolet (UV) or visible light, photocuring is performed, or by gamma ray or electron beam irradiation, thereby causing the curable components present in the curable composition to polymerize, and then applying the second curing step. The second curing step preferably includes thermal curing, gamma ray irradiation or EB irradiation of the product of the first curing step, whereby the second curing step preferably applies a curing technique different from the first curing step. When gamma ray or electron beam irradiation is used in the first curing step, a dose of 60 to 200 kGy, more preferably 80 to 150 kGy, is preferably applied to the curable composition.

[0088] In one embodiment, the method of the second aspect of the invention comprises curing the curable composition to form an anion exchange membrane in a first curing step, winding the anion exchange membrane onto a core (optionally with an inert polymer foil), and then subjecting the wound product of the first curing step to a second curing step.

[0089] In a preferred embodiment, the first and second curing steps are respectively selected from: (i) UV curing (first curing step) followed by thermal curing (second curing step); (ii) UV curing followed by electron beam curing; and (iii) electron beam curing followed by thermal curing.

[0090] Component (c) may comprise only one free radical initiator or more than one free radical initiator, for example a mixture of photoinitiators (eg for single cure) or a mixture of a photoinitiator and a thermal initiator (eg for dual cure).

[0091] In one embodiment, the second curing step is performed using gamma ray or electron beam (EB) irradiation. For the second curing step performed by gamma ray or EB irradiation, preferably a dose of 60 to 200 kGy is applied to the product of the first curing step, more preferably a dose of 80 to 150 kGy is applied.

[0092] For the optional second curing step, heat curing is preferred. Heat curing is preferably carried out at a temperature of 50 to 100° C., more preferably 60 to 90° C. Heat curing is preferably carried out for a period of 2 to 72 hours, for example about 3 hours for sheets; 8 to 16 hours, for example about 10 hours for small rolls; 24 to 72 hours for large rolls. Optionally, after the first curing step, a polymer foil is applied to the product of the first curing step before it is wound onto a reel (this reduces oxygen inhibition, drying and / or adhesion of the product of the first curing step to itself).

[0093] In a preferred method of the second aspect of the invention, the curable composition is preferably applied continuously to a moving (preferably porous) carrier by a manufacturing unit, which comprises a curable composition application station, one or more radiation sources for curing the curable composition, a film collection station and a device for moving the carrier from the curable composition application station to the radiation source and the film collection station.

[0094] The curable composition application station may be located in an upstream position relative to the radiation source, and the radiation source is located in an upstream position relative to the film collection station.

[0095] Examples of suitable coating techniques for applying the curable composition to the support include slot coating, slide coating, air knife coating, roller coating, screen printing and dipping. Depending on the technique used and the desired end specification, it may be necessary to remove excess coating from the substrate by, for example, roll-to-roll extrusion, roll-to-blade or blade-to-roll extrusion, blade-to-blade extrusion or removal using a coating rod. The first curing step is preferably photocured, preferably using 40 to 20,000 mJ / cm at a wavelength of 300 nm to 800 nm. 2 In some cases, additional drying may be required, for which a temperature of 40°C to 200°C may be used. When gamma or EB curing is used, irradiation may be carried out under low oxygen conditions, for example less than 200 ppm oxygen.

[0096] According to the third aspect of the present invention, there is provided the use of the anion exchange membrane of the first aspect of the present invention in an electromembrane process, such as for treating polar liquids (such as desalination), for producing acids and alkalis, or for power generation or storage (method of use).

[0097] According to a fourth aspect of the present invention, an electrodialysis or reverse electrodialysis device, a bipolar electrodialysis device, an electrodeionization module, a flow-through capacitor, a diffusion dialysis device, a membrane distillation module, an electrolyzer, a redox flow battery, an acid-base flow battery or a fuel cell is provided, which comprises one or more anion exchange membranes of the first aspect of the present invention.

[0098] The invention will now be illustrated by the following non-limiting examples in which all parts and percentages are by weight unless otherwise stated.

[0099] pH stability

[0100] The pH stability of the anion exchange membrane was tested by immersing the tested membrane samples in 4M HCl at 80°C for at least 1 month. After this treatment, the membrane's permselectivity (PS) was measured and compared to its PS before immersion. If the PS after immersion was at least 80% of the original PS, the pH stability of the membrane was considered "OK"; if it was less than 80% of the original PS, the pH stability was considered bad ("NG").

[0101] Selective Permeability (PS)

[0102] The permselectivity (PS) (%) (i.e., the selectivity of an anion exchange membrane for the passage of ions of opposite charge) was measured as follows:

[0103] The anion exchange membrane to be tested was placed in a two-compartment system, one compartment was filled with 0.05M HCl solution, the other compartment was filled with 4M HCl solution, and the membrane to be tested separated the two compartments.

[0104] set up:

[0105] The capillary and the Ag / AgCl reference electrode (Metrohm model 6.0750.100) contained 3 M KCl;

[0106] ·Effective membrane area is 9.62cm 2 ;

[0107] The distance between the capillaries is about 15 mm;

[0108] The measured temperature is 21.0±0.2℃;

[0109] For both compartments, a Cole Parmer Masterflex console drive (77521-47) with an Easy-load II model 77200-62 gear pump was used;

[0110] The flow rate was controlled to be constant at 500 ml / min using a Porter Instrument flow meter (150AV-B250-4RVS) and a Cole Parmer flow meter (G-30217-90);

[0111] Before measurement, the anion exchange membrane sample was equilibrated in 0.25 M HCl solution for 1 hour. The voltage was read from a conventional VOM (multimeter) after 20 minutes.

[0112] The PS is calculated from the voltage readings using the Nernst equation. Preferably, the PS of the HCl is at least 50%.

[0113] Ion Exchange Capacity (IEC)

[0114] Prior to measurement, the membrane was converted to the chloride form by immersing the sample in a 2 M NaCl solution for 1 hour. The 2 M NaCl solution was replaced once and the sample was equilibrated for another 24 hours. Rinse with water and soak in fresh water for 1 hour and then again Rinse once with water.

[0115] A sample with a diameter of 2.0 cm (12.57 cm) was punched out from the membrane sample with chloride ions as counter ions. 2 ), dried at 40°C for 24 hours and weighed. Then, the sample was placed in 75 ml water for 24 hours to remove all non-counter ions, and then After washing with water, each sample was immersed in 10.00 ml of 0.1 M AgNO3 solution and the solution and sample were shaken for 24 hours. + The ions were removed by precipitation of AgCl salt. - ions, so Cl - Ions are NO3 - The ions were completely exchanged. Subsequently, the sample was removed from the AgNO3 solution and washed with a small amount of Water rinse. The rinse water of each sample and the corresponding AgNO3 solution remaining after shaking the membrane sample were combined and titrated with a calibrated 0.1M KBr solution, and the results were compared with the titration of 10.00ml of a 0.1M AgNO3 blank solution (containing no membrane sample). The difference between the titration results of the blank solution and the test solution of each sample was related to the ion exchange capacity of the corresponding membrane using equation (I):

[0116] IEC (meq / g dry film) = (YX) * 0.1 / W Equation (I)

[0117] in

[0118] Y is the amount of 0.1 M KBr used to titrate the blank AgNO3 solution (in ml);

[0119] X is used to titrate the AgNO3 solution (in which the membrane sample is soaked) with The amount (in ml) of the combined 0.1 M KBr of water (used to rinse the sample after immersion in the AgNO3 solution); and

[0120] W is the dry weight of the membrane in grams.

[0121] Resistor (ER)

[0122] The ER (ohm.cm) of the anion exchange membrane prepared in the example 2 ) was measured by the method described in Dlugolecki et al., J. of Membrane Science, 319 (2008), pp. 217-218, with the following modifications:

[0123] The auxiliary membranes are CMX and AMX from Tokuyama Soda of Japan;

[0124] The capillary and the Ag / AgCl reference electrode (Metrohm model 6.0750.100) contained 3 M KCl;

[0125] The calibration solution and the liquid in compartments 2, 3, 4, and 5 are 2.0 M NaCl solutions at 25°C;

[0126] ·Effective membrane area is 9.62cm 2 ;

[0127] The distance between capillaries is 5.0 mm;

[0128] The measurement temperature is 25℃;

[0129] For all compartments, a Cole Parmer Masterflex console drive (77521-47) with an Easy-load II model 77200-62 gear pump was used;

[0130] The flow rate of each stream was controlled at 475 ml / min by a Porter Instrument flow meter (model 150AV-B250-4RVS) and a ColeParmer flow meter (model G-30217-90); and

[0131] Before measurement, the anion exchange membrane samples were equilibrated in 0.5 M NaCl solution at room temperature for at least 1 hour.

[0132] ER is preferably low, for example, less than 15 ohm.cm 2 .

[0133] Table 1: Ingredients

[0134]

[0135] CL-1 was synthesized as described in Example 1 of US20160177006:

[0136]

[0137] General procedure for the preparation of AXL-1 to 4

[0138]

[0139] CMS-14 (2.02 mmol) was added dropwise to a 40% PW solution of the corresponding amine (1 mmol) containing 4-OH-TEMPO (0.1 g) over a period of 1 hour. Afterwards, the mixture was stirred vigorously for 2 hours. Diethyl ether was added and the aqueous phase was extracted three times (3×200 mL). The product was isolated from water by spray drying as a light yellow solid.

[0140] Table 2: Structural elements of AXL and corresponding amines

[0141] Compound <![CDATA[R a ,R b ]]> X amine Yield AXL-1 <![CDATA[CH3-,CH3-]]> Cl DMA 73％ AXL-2 <![CDATA[-(CH2)4-]]> Cl Pyrrolidine 82％ AXL-3 <![CDATA[-(CH2)5-]]> Cl Piperidine 78％ AXL-4 <![CDATA[CH3CH2-,CH3CH2-]]> Cl DEA 76％

[0142] Examples Ex1 to Ex6 and Comparative Examples CEx1 and CEx2.

[0143] Table 3: Curable compositions and results

[0144]

[0145] Table 3: Curable compositions and results (continued)

[0146]

[0147]

[0148] The IEC in Comparative Example 1 is higher because the amount of component (b) is higher, resulting in a lower PS. In Comparative Example 2, component (a) does not conform to formula (I).

[0149] Preparation of curable compositions and anion exchange membranes

[0150] The curable compositions shown in Table 3 above were prepared by sequentially mixing the specified amounts of the components (in wt%) in a specified amount of a mixture of water / n-propanol at a temperature of 40°C.

[0151] The anion exchange membranes of the first aspect of the present invention and the comparative examples were prepared by applying each curable composition described in Table 3 to a porous support (PS1) using a 100 μm Meyer rod at room temperature (21° C.), removing excess curable composition using a 4 μm Meyer rod, and then curing the composition. UV curing was performed by placing a sample of the porous support carrying the curable composition on a 5 m / min conveyor belt and exposing the curable composition to UV light emitted by a D bulb at 50% power, the conveyor belt being equipped with a Light from Fusion UV Systems Inc. The UV cured samples were covered with 60 μm polyethylene terephthalate (PET) foil (from Toray) without any surface treatment and placed in a metallized vacuum sealed bag. The bag containing the UV cured film was then heat cured (as a second curing step) at 90° C. in a conventional oven for 3 hours.

Claims

1. An anion exchange membrane obtainable by curing a curable composition, the curable composition comprising: (a) Monomer (a) of formula (I) AR 1 -(CH2) n -N + (R a R b )-(CH2) n -AR 2 ,X - Formula (I) in: Each n independently has a value of 1 or 2; (i)R a and R b are each independently an optionally substituted C 1-3 Alkyl or optionally substituted C 2-3 alkenyl; or (ii) R a and R b Together with the positively charged nitrogen atom to which they are attached, they form an optionally substituted 5- or 6-membered ring; or (iii) R a and R b One of the C 1-3 Alkyl or optionally substituted C 2-3 alkenyl, and R a and R b Another AR 1 -(CH2) n -N + together form an optionally substituted 5- or 6-membered ring; or (iv) R a AR 1 -(CH2) n -N + The groups together form an optionally substituted 5- or 6-membered ring, and R b With formula N + -(CH2) n -AR 2 The groups together form an optionally substituted 5- or 6-membered ring; X - is an anion; and AR 1 and AR 2 each independently comprises an aromatic group; in: (I)AR 1 and AR 2 At least one of the comprises a curable ethylenically unsaturated group; (II) the monomer (a) of formula (I) comprises at least two curable ethylenically unsaturated groups; and (III) The anion exchange capacity (IEC) of the anion exchange membrane is lower than 1.65 meq / g dry membrane.

2. The anion exchange membrane according to claim 1, wherein In formula (I), the value of n is 1.

3. An anion exchange membrane as claimed in any one of the preceding claims, wherein AR 1 and AR 2 Each contains a curable ethylenically unsaturated group.

4. An anion exchange membrane as claimed in any one of the preceding claims, wherein In formula (I), AR 1 and AR 2 All contain styryl groups.

5. An anion exchange membrane as claimed in any one of the preceding claims, wherein The curable composition further comprises a monomer (b) comprising a cationically charged group and one and only one curable ethylenically unsaturated group.

6. An anion exchange membrane as claimed in any one of the preceding claims, wherein The curable ethylenically unsaturated group is a vinyl group.

7. An anion exchange membrane as claimed in any one of the preceding claims, wherein The mole fraction of component (a) relative to all curable components of the curable composition is at least 0.

90.

8. An anion exchange membrane as claimed in any one of the preceding claims, wherein The curable composition further comprises (c) a free radical initiator.

9. An anion exchange membrane as claimed in any one of the preceding claims, wherein The curable composition further comprises (d) a monomer that does not contain a cationically charged group.

10. An anion exchange membrane as claimed in any one of the preceding claims, wherein The curable composition further includes (e) a solvent.

11. An anion exchange membrane as claimed in any one of the preceding claims, wherein The curable composition comprises: 50 to 90% by weight of component (a), 0 to 10% by weight of component (b), 0 to 10% by weight of component (c) (free radical initiator), 0 to 5% by weight of component (d) (monomer free of cationically charged groups) and 10 to 40% by weight of component (e) (solvent).

12. An anion exchange membrane as claimed in any preceding claim further comprising a porous support.

13. A method of preparing an anion exchange membrane comprising curing a curable composition as defined in any one of the preceding claims.

14. The method of claim 13, comprising the steps of: (i) providing a curable composition as defined in claim 1; (ii) applying the curable composition to a porous support, whereby at least a portion of the curable composition impregnates the porous support; and (iii) curing the curable composition.

15. An electrodialysis unit, a bipolar electrodialysis unit, an electrolyser, a redox flow battery, an acid-base flow battery or a fuel cell comprising one or more anion exchange membranes according to any one of claims 1 to 12.

16. Use of the anion exchange membrane according to any one of claims 1 to 12 for treating polar liquids, for producing acids and bases, or for power generation or storage.

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