Anion exchange membrane

Abstract

An anion exchange membrane, particularly suitable for use in electrolytic devices and fuel cells, comprises a polyolefin support and an active copolymer containing monomer units derived from an acrylic monomer having long-chain saturated linear alkyl chains. The saturated linear alkyl chains of the monomer units of the active polymer derived from an acrylic monomer with sufficient chain length interact with similar saturated linear chains exposed on the surface of the polyolefin support, thereby allowing the active copolymer to adhere to the support, thereby enabling the acquisition of an anion exchange membrane with high mechanical properties and durability. Furthermore, the positive charge of the active copolymer is separated within the pores of the polyolefin support, promoting the formation of positively charged ion channels, facilitating the movement of hydroxide ions, and enabling the achievement of high performance in electrochemical cells. The anion exchange membrane according to the present invention can be obtained in an economically advantageous manner by a specific process in a reactor, which involves promoting the polymerization of the monomer mixture, activating the copolymer with tertiary piperidine and / or pyrrolidineamine to promote the formation of quaternary ammonium salts, and promoting the adhesion of the copolymer to the polyolefin support.

Description

Technical Field

[0001] The present invention relates to anion exchange membranes, and particularly to their use in electrolyzers and fuel cells.

[0002] The present invention also relates to a method for manufacturing an anion exchange membrane.

Background Art

[0003] The main types of electrolyzers that can be used for hydrogen production are four: alkaline type (AEL), solid polymer type (PEM), anion exchange membrane type (AEM), and solid oxide type (SOEC). The first two already occupy a good position in the market, have stacks (an assembly of electrochemical cells where water molecules are decomposed into oxygen and hydrogen), and their output is on the MW scale. The other two have stack outputs on the kW scale and short service lives.

[0004] AEL electrolyzers operate at low temperatures and are low-cost. Since this is a widely used technology, it has an established supply network and production capacity. However, due to the limited response to fluctuations in electrical input, it is difficult to cooperate with renewable energy sources.

[0005] PEM electrolysis systems use solid electrolytes. They provide faster dynamic responses, compact designs, and high energy efficiency. In proton exchange membranes, the passage of hydrogen is significantly limited, enabling high-pressure operation and reducing the energy required for hydrogen compression and storage. However, since PEM systems have high basic power consumption, even these systems are not suitable for cooperation with renewable energy sources, particularly for cooperation with solar power generation for nighttime consumption.

[0006] AEM electrolytic units combine the advantages of PEM and AEL systems. They use lower-cost materials and offer energy density and efficiency comparable to PEM technology. AEM electrolytic units currently reach up to 2.4kW, but currently available membranes on the market do not achieve sufficient stability, which limits the widespread adoption of this technology in electrolytic applications.

[0007] Finally, SOEC electrolytic devices have the advantage of operating at high pressure and achieving high efficiency while using non-precious metal catalysts. Although they have good development potential, their commercial use is currently limited due to their short service life caused by high operating temperatures.

[0008] PEM and AEM systems generally use polymer membranes placed between the anode and cathode to transport ions from one half-cell to the other. Therefore, membranes capable of moving H+ ions (proton exchange membranes, PEMs) are used in systems operating in acidic environments, while membranes capable of circulating hydroxide ions are used in systems operating in alkaline environments (anion exchange membranes, AEMs).

[0009] AEMs are obtained by synthesizing positively charged ionic polymers, which are responsible for the movement of negatively charged hydroxide ions. Given the unique operating characteristics of these devices, the properties of the polymer materials used must meet very stringent requirements. Firstly, they must have high operating pH stability to avoid undesirable degradation phenomena that cause uncontrollable membrane failure. Furthermore, to optimize electrochemical performance, the polymer materials and membranes obtained from them must exhibit high ionic conductivity. Finally, a crucial aspect is mechanical properties, which enable operation even when a pressure gradient exists between the two semicells.

[0010] Compared to the first two types of electrolytic devices mentioned above, AEM has limited adoption because AEM films have greater limitations, particularly in terms of stability and mechanical properties, and as a result, the stack size is limited to a few kW.

[0011] Considering the points mentioned above, AEM electrolytic devices are primarily used in combination with renewable energy sources. However, due to limitations in stack size, when it is necessary to combine them with MW-class or even GW-class renewable energy plants, a large number of AEM electrolytic device modular stacks are used, which significantly increases both production and operating costs.

[0012] In almost all known AEM membranes, the positive charge responsible for the movement of hydroxide ions is obtained by the formation of quaternary ammonium salts. AEM anion exchange membranes operate in strongly alkaline environments, and one of the best-known degradation mechanisms of quaternary ammonium salts at such pH levels is Hoffmann elimination. This occurs through the removal of the β-hydrogen relative to the nitrogen atom, leading to the formation of a double bond and the elimination of the amine.

[0013] Furthermore, hydroxide ions can cause nucleophilic substitution on the nitrogen atom of ammonium. This mechanism leads to the loss of quaternary ammonium salts and the formation of alcohols on the polymer chain (making it difficult for ions to conduct easily), thereby inhibiting ion transport activity. The solution to this problem is to sterically disrupt the chemical environment of the nitrogen atom.

[0014] These phenomena cause a decrease in the number of active sites responsible for the movement of hydroxide ions (OH-) over time, resulting in a decrease in ionic conductivity.

[0015] Generally, ammonium salts are subject to such limitations, but this can be prevented by using amines that do not have a hydrogen atom at the β position or that cannot be easily removed due to steric hindrance (D. Henkensmeier, M. Najibah, C. Harms, J. Zitka, J. Hnat, K. Bouzek, J. Electrochem. Energy Convers. Storage 2021, 18, 024001).

[0016] Recent studies have shown that piperidinium-type ammonium salts, although difficult to prepare, can be conferred with high chemical resistance (MGMarino, KDKreuer, ChemSusChem2015, 8, 513).

[0017] The possibility of fabricating anionic films in which ammonium salts are obtained as reaction products of piperidine compounds is suggested in U.S. Patent Application Publication No. 2020 / 0030787.

[0018] There is extensive scientific literature describing the use of polymers containing heteroatoms in the main chain. However, this creates sites that are susceptible to attack by hydroxide ions, leading to chain breakdown and a resulting decrease in average molecular weight (Merle G, Wessling M, Nijmeijer K (2011) J Membr Sci, 377:1-35).

[0019] When the main polymer chain degrades during AEM use within a cell, it leads to a loss of mechanical properties, resulting in film rupture and a rapid decline in the performance of the electrochemical device.

[0020] For an electrochemical reaction to occur, water molecules, in addition to hydroxide ions, must also permeate the membrane. However, an excess of water molecules within the membrane can lead to the following problems. - Swelling, - Changes in the size of polymer films, -Mechanical weakening.

[0021] Excessive dimensional changes can lead to suboptimal adhesion between the film and the electrode, potentially causing device failure. Conversely, mechanical weakening can cause film fracture, particularly in devices operating under pressure. To improve the mechanical properties of the film, polymer chain crosslinking strategies are often employed. However, these are difficult to control, and excessive crosslinking can impart excessive stiffness to the film, promoting fracture (TYSon, THKo, V.Vijayakumar, K.Kim, SYNam, SolidStateIonics 344 (2020), 115153).

[0022] Furthermore, known procedures for producing AEM membranes involve complicated and cumbersome synthesis using inexpensive reagents (Kimberly F.L. Hagesteijn1, Shanxue Jiang1, and Bradley P. Ladewig1, JMaterSci (2018) 53:11131-11150).

[0023] For example, it is known that polymeric hydrophilic polymer composite films and hydrophobic porous supports can be fabricated. In these solutions, mechanical properties are improved, but the inertness of the polymer support makes it difficult for hydroxide ions to pass through, resulting in a decrease in film performance. Furthermore, the difference in chemical properties between the commonly used hydrophobic support and the positively charged polymer leads to low affinity between the two polymer phases, resulting in the formation of weak bonds. To overcome this problem, chemical and physical changes can be made to the surface of the polymer support, thereby exposing functional groups that can covalently bond with the polymer responsible for the movement of hydroxide ions. According to known techniques, these operations are carried out using complex techniques (e.g., plasma treatment, corona treatment), but these do not penetrate deeply into the pores of the substrate, resulting in insufficient effectiveness or causing changes that are difficult to control (TYSon, THKo, V.Vijayakumar, K.Kim, SYNam, Anion exchange composite membranes composed of poly(phenylene oxide)quaternary ammonium and polyethylene support for alkaline anion membrane exchange fuel cell containing applications, Solid State Ionics 344(2020), 115153).

[0024] To achieve good conductivity of hydroxide ions without excessively increasing the number of active sites, separation of positive charges is required, which leads to the formation of "ion channels." These ion channels are continuous positively charged zones that penetrate the membrane and function as preferential pathways for hydroxide ions.

[0025] Although the importance of ion channels is recognized in the literature, there is no simple and effective method for obtaining them (G. Arges et al. vj. Mater. Chem. A, 2017, 5, 5619).

[0026] Publication LUO Y ET AL: "Quaternized poly(methyl methacrylate-co-butyl acrylate-co-vinylbenzyl chloride) membrane for alkaline fuel cells", JOURNAL OF POWER SOURCES, ELSEVIER, AMSTERDAM, NL, vol. 195, No. 12, 15 June 2010 (2010-06-15), pages 3765-3771 describes a method of making a membrane from a random poly(methyl methacrylate-co-butyl acrylate-co-vinylbenzyl chloride) copolymer by copolymerizing specific functional monomers. This copolymer is quaternized after copolymerization and finally membrane-formed by "membrane casting", so no kind of support is used. This copolymer does not have ammonium salts derived from styrene units and pyrrolidine / piperidine units, and PTFE is only used as a component in the preparation of electrochemical cell electrodes and not as a support for the active membrane copolymer.

[0027] Especially in view of the increasing interest in AEM devices by virtue of the advantageous combination utilization with renewable sources, it is necessary to develop alternative solutions for AEM membranes that exhibit mechanical strength and durability and are associated with high ionic conductivity.

Prior Art Documents

Patent Documents

[0028]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0029] An object of the present invention is to propose an anion exchange membrane (AEM) that exhibits good mechanical strength and durability characteristics related to high ionic conductivity.

[0030] Another objective of the present invention is to propose an anion exchange membrane that combines high performance in terms of mechanical strength, durability, and conductivity with very low production costs.

[0031] Another objective of the present invention is to propose a method for realizing an anion exchange membrane that can realize a high-performance membrane at a very low production cost.

[0032] Another objective of the present invention is to propose a method for realizing an anion exchange film that can be produced at low cost and has high mechanical performance, durability, and conductivity in large-format films. [Means for solving the problem]

[0033] According to a first aspect of the present invention, the above objective is achieved by an anion exchange membrane comprising a support made of a porous polyolefin material for increasing mechanical strength, a polyfunctional copolymer containing positively charged monomer units (non-acrylic) capable of moving hydroxide ions, and a paraffin group of monomer units derived from an acrylic monomer having a linear saturated alkyl chain with three or more carbon atoms. Thus, in addition to providing a positive charge for OH- movement, the copolymer can chemically bond to the polyolefin material (paraffin) support via hydrophobic interactions.

[0034] The porous polyolefin material support ensures high mechanical resistance to the film. The active copolymer is a polyfunctional copolymer containing positively charged monomer units (non-acrylic) capable of moving hydroxide ions and paraffin groups of monomer units derived from acrylic monomers having linear saturated alkyl chains with three or more carbon atoms. Therefore, in addition to donating a positive charge for OH- movement, the copolymer can chemically bond to the polyolefin material (paraffin-based) support via hydrophobic interactions.

[0035] Saturated linear alkyl chains (paraffinic) derived from acrylic monomers with sufficient copolymer chain length interact with similar saturated linear chains exposed on the surface of the polyolefin support, resulting in two effects: - The active copolymer adheres to the support, thereby making it possible to obtain an anion exchange film with high mechanical properties and durability. - The formation of two phases, namely a hydrophobic phase and a conductive-hydrophilic phase, the separation of the positive charge of the active copolymer within the pores of the polyolefin support, and the formation of positively charged ion channels are promoted, facilitating the movement of hydroxide ions and enabling high performance in the electrochemical cell.

[0036] Preferably, the active copolymer consists of alkyl acrylate units, styrene units, and vinyl-benzyl units having benzyl bond substituents, where these substituents belong to the piperidine and / or pyrrolidine groups, and are preferably N-alkylpiperidine and / or N-alkylpyrrolidine.

[0037] Piperidine and / or pyrrolidine are bonded to vinylbenzene units via chloromethyl groups to form positively charged quaternary ammonium groups.

[0038] By using piperidinium and / or pyrrolidinium, which are quaternary ammonium ions that are less susceptible to attack by hydroxide ions due to their cyclic nature, high ion exchange capacity and conductivity can be combined with high durability.

[0039] More advantageously, the active copolymer consists of polymerization products of at least the following components: a. Acrylic monomer having a saturated linear alkyl chain with 3 or more carbon atoms, b. Vinyl benzyl monomers in which a methyl chloride group is bonded to an aromatic ring, and c. Vinyl aromatic monomers having tertiary piperidine and / or pyrrolidineamine.

[0040] Advantageously, the tertiary piperidine and / or pyrrolidine amines include at least one of 1-methylpiperidine, 1-ethylpiperidine, 1-propylpiperidine, 1-butylpiperidine, 1,2,6-trimethylpiperidine, 1,2,6-triethylpiperidine, 1,2,6-tripropylpiperidine, 1,2,2,6,6-pentamethylpiperidine, 1-methylpyrrolidine, 1-ethylpyrrolidine, 1-propylpyrrolidine, and 1,2,5-trimethylpyrrolidine.

[0041] Advantageously, acrylic monomers are esters of acrylic acid, which bond a straight chain of saturated hydrocarbons to the outer oxygen atom.

[0042] More advantageously, the acrylic monomers include at least propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecyl acrylate, octadecyl acrylate, nonadecyl acrylate, eicosyl acrylate, and propyl acrylate. It contains any one of the following: methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecyl methacrylate, octadecyl methacrylate, nonadecyl methacrylate, and icosyl methacrylate.

[0043] A vinylbenzyl unit having a positively charged substituent is obtained as a reaction product of a vinylbenzyl group, in which a methyl chloride group is bonded to an aromatic ring, and at least one tertiary piperidineamine and / or pyrrolidineamine, in which an alkyl group is bonded to a nitrogen atom. In this way, a quaternary ammonium salt is formed.

[0044] The hydrophobic interactions established between the linear aliphatic chains of the active copolymer and the support material expose the quaternary ammonium salt within the support's pores, forming a hydrophobic phase that intersects with the hydrophilic phase. As a result, positively charged hydrophilic domains are formed. This provides positively charged ion channels that are easily accessible to hydroxide anions present in alkaline solutions. These channels are surrounded by the hydrophobic phase, preventing excessive water accumulation and mechanical weakening within the membrane.

[0045] Advantageously, the copolymer comprises 3 mol% to 10 mol% acrylic units, 40 mol% to 79 mol% vinyl aromatic units, and 20 mol% to 50 mol% substituted vinyl benzyl units.

[0046] Furthermore, the copolymer has an average degree of polymerization of 200 to 500.

[0047] Advantageously, copolymers are obtained by using peroxide radical initiators to accelerate the polymerization reaction.

[0048] In a preferred configuration, the polyolefin support is made from a polyethylene-based material selected from LDPE, HDPE, or UHMWPE.

[0049] In another configuration, the polyolefin support is made of polypropylene-based material.

[0050] By using a polyolefin support, the mechanical properties of the film can be significantly improved compared to films obtained by casting only the active polymer, as in the case of anion exchange film production using many known technologies.

[0051] By using active polymers and support structures that do not contain heteroatoms in the main chain, the problem of degradation in alkaline environments can be solved. This is because, in both the support structure and the active copolymer, all bonds in the main chain are carbon-carbon sp3 covalent bonds that cannot be attached by OH anions.

[0052] In a preferred configuration, the polyolefin support has a porosity of 40% to 95% and an average pore diameter of 0.2 μm to 1.2 μm.

[0053] Advantageously, the adhesion of copolymers to a support in a polyolefin material is facilitated by radical initiators and / or radical stabilizers, and in particular by at least one olefin having aromatic and / or heteroaromatic groups.

[0054] More specifically, the adhesion of copolymers to a support within a polyolefin material can be enhanced by grafting the active polymer onto a support activated with a co-reagent that stabilizes a radical initiator and primary radicals, thereby preferentially promoting reaction bonding over decomposition. In particular, this effect can be obtained by using at least one appropriately substituted olefin having aromatic and / or heteroaromatic groups, such as 1-phenylmethyl acrylate or 1-furylmethyl acrylate.

[0055] Due to the presence of the polyolefin support, the film has high tensile strength, a Young's modulus of 4800 MPa to 5800 MPa, and an elongation of over 10%. As a result, it can be used in electrolytic devices operating under high-pressure conditions (exceeding 30 Bar) without the occurrence of fracture phenomena that could cause short circuits in the electrolytic cells.

[0056] The suppressed linear expansion (less than 10%) resulting from water absorption by the membrane prevents the membrane from detaching from the electrodes even when humidity changes occur in fuel cells that operate using atmospheric oxygen, thus enabling their use.

[0057] According to another aspect of the present invention, the aforementioned object of the present invention is achieved by a method for realizing an anion exchange membrane comprising the following steps: —Using at least one peroxide radical initiator, ii. Acrylic monomers having a saturated linear alkyl chain with 3 or more carbon atoms, iii. A vinyl benzyl monomer having a methyl chloride group on the aromatic ring, iv. To promote the polymerization of a mixture containing vinyl aromatic monomers. —Activating copolymers obtained using tertiary piperidine and / or pyrrolidineamine by promoting the formation of quaternary ammonium salts through substitution of at least one vinyl benzyl chloride monomer.

[0058] —Promoting the bonding of copolymers to polyolefin supports by immersing a film of the polyolefin support in a copolymer liquid solution in the presence of a polar solvent.

[0059] The method of the present invention provides a simple, safe, and economical process for obtaining anion exchange membranes with performance and mechanical properties comparable to those obtained by accelerating the grafting of active polymers onto a polymeric matrix with high mechanical properties using gamma rays. The use of gamma rays is particularly costly due to the strict safety constraints of its use. These constraints make it economically unfeasible to produce anion exchange membranes beyond a certain size limit, and therefore, the realization of high-power plants using this technology is limited unless a very large number of low-power electrochemical cells are used. Compared with known technologies that can obtain anion exchange membranes with comparable performance, the method of the present invention makes it possible to obtain much larger anion exchange membranes at a very competitive cost, thereby opening up the possibility of creating high-power electrolytic cells that are not currently possible with known AEM electrolytic devices.

[0060] In a preferred embodiment of the method of the present invention, the copolymer activation step is performed before the step of promoting the bonding of the copolymer to the polyolefin support, and the polyolefin material support is polyethylene-based.

[0061] In this case, when the polyethylene support is immersed in the copolymer solution, saturated linear alkyl chains of monomer units derived from acrylic monomers having a sufficient copolymer chain length interact with similar saturated linear alkyl chains exposed on the surface of the polyolefin support. After the solvent present in the solution evaporates, a chemical bond is realized through hydrophobic interaction between the active copolymer and the support.

[0062] In a preferred embodiment, the step of promoting the bonding of the copolymer to the polyolefin support is carried out by adding a peroxide radical activator and a radical stabilizer consisting of an olefin having aromatic and / or heteroaromatic groups to a liquid solution containing the copolymer and the porous polyolefin support.

[0063] By adding radical activators and radical stabilizers, the formation of covalent bonds can be promoted between the polyolefin support, which in this case may be polypropylene, and the activated copolymer. Furthermore, in this case, the adhesion of the copolymer to the polyolefin support can also be promoted before the copolymer is activated.

[0064] Further features and advantages of the present invention are illustrated with reference to the accompanying drawings and will become apparent from the following description of embodiments that are not limited to them. [Brief explanation of the drawing]

[0065] [Figure 1] The main chemical reactions required to obtain an anion exchange membrane according to the present invention are schematically shown. [Figure 2] This is a Cartesian coordinate diagram showing the polarization curves at various temperatures of an electrolytic cell containing an anion exchange membrane according to the present invention. [Figure 3]This table shows the measurement results of water absorption rate (20°C and 80°C), thickness increase rate (20°C and 80°C), and linear expansion coefficient (20°C and 80°C) conducted in accordance with ISO standards. [Figure 4] This table shows the measurement results of tensile strength, Young's modulus, and elongation of the anion exchange membrane according to the present invention, performed in accordance with ISO 153-7. [Modes for carrying out the invention]

[0066] In the following description of specific embodiments of the present invention, it is understood that the composition of the film according to the present invention is not limited to the specific reagents mentioned, and that the described realization process represents the main steps, and that the tools, protocols, and reagents used may vary, as understood by experts in the art, and are not intended to limit the scope of the process. Where used herein and in the appended claims, the singular form includes the plural form unless the context clearly indicates otherwise. For example, a reference to “solvent” means a reference to one or more solvents and their equivalents known to experts in the art. Similarly, the combination “and / or” is used to indicate that one or both of the declared cases may occur, for example, A and / or B includes (A and B) and (A or B). Unless otherwise defined, technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which this process belongs.

[0067] Before describing specific embodiments of the present invention below, some definitions of terms used in this text are provided.

[0068] definition Anion exchange membrane: A membrane made of a positively charged polymer that can move hydroxide ions when placed between the electrodes of an electrochemical cell in an alkaline bath.

[0069] Polyolefin materials: Materials based on polyethylene and / or polypropylene.

[0070] Positively charged units: Units within polymer chains containing ammonium salts.

[0071] Acrylic monomers: Monomers containing acrylates and methacrylates having various substituents.

[0072] Peroxy radical initiators: Radical initiators are molecules containing an oxygen-oxygen bond that is particularly vulnerable to homogenization, and therefore function as a source of free radicals, and thus can be used as initiators in radical polymerization or graft reactions. Peroxides (compounds with the general formula RO-OR structure) are the most commonly used radical initiators. When peroxides are heated, homogenization of the fragile OO bond occurs, forming two RO radicals*. These can attach to the double bond of an olefin compound to initiate polymerization, or abstract hydrogen from an organic compound to create a secondary radical on the molecule. The two free radicals can interact with each other (combination reaction) to create a covalent bond.

[0073] Radical stabilizers are molecules added to stabilize primary free radicals via resonance (delocalization on molecules with unpaired electrons). They prevent polymer degradation by inhibiting the abstraction of hydrogen atoms from chains (backbiting), and can also induce combination reactions between two types of radicals.

[0074] In the present invention, the radical stabilizer is a molecule used to promote grafting, and by stabilizing the radical, the probability of covalently bonding the active polymer to the support via the recombination of two radicals is increased.

[0075] Grafting: Generally, grafting refers to the process of grafting molecules onto a specific polymer for functionalization. Here, it means forming covalent bonds between the polyolefin support chain and the active polymer through a radical reaction, and then these are "grafted" onto the support.

[0076] Copolymer activation: Conversion of polymers to positively charged ionomers obtained by the reaction of tertiary amines with benzyl halides.

[0077] Example 1 Referring to Figure 1, -Support made from porous polyolefin material, and -i. A positively charged monomer unit capable of moving hydroxide ions. ii. Monomer units derived from acrylic monomers having saturated linear alkyl chains with 3 or more carbon atoms, and iii. An anion exchange membrane containing a copolymer containing monomer units derived from vinyl aromatic monomers, -56 mol% styrene, -4-vinylbenzene chloride 34 mol%, - Octadecyl acrylate 9 mol%, - Insert 1 mol% benzoyl peroxide. The mixture is then obtained by maintaining the reactor at 73°C for approximately 10 hours under a controlled atmosphere. Next, an amount of acetone (CH3-CO-CH3) equivalent to 300 mol% (relative to the initial mixture in the reactor) is added, and stirring is continued until the polymer is completely dissolved.

[0078] Subsequently, 20 mol% of N-methylpiperidine is added (to the mixture in the reactor), and while stirring for another 10 hours, 160 mol% of ethanol (CH3-CH2-OH) is added to obtain the active copolymer in solution.

[0079] Finally, a support made of a polyethylene sheet with a porosity of 60% and an average pore size of 0.6 μm is immersed in the obtained solution and left until the solvent has completely evaporated. In this step, the hydrocarbon chains of the active copolymer crystallize together with the surface of the support, and as a result, positive charges are exposed and separated within the pores of the support, thereby obtaining the anion exchange film according to the present invention.

[0080] The performance of the obtained anion exchange film in an electrolytic cell was measured by polarization curves at various temperatures using a platinum-based cathode and a Ni / Fe / Co oxide-based anode. The results of the measurement tests are shown in Figure 2.

[0081] The ion exchange capacity (IEC) of the obtained anion exchange membrane was measured by acid-base titration according to the following steps. -A process to activate the membrane in KOH 1M for 24 hours. - A drying process in an inert atmosphere, - A weighing process until the weight becomes constant. - A process of immersing the film in a known amount of 0.01M HCl for 24 hours. - A step of back titrating an acid solution using KOH of known concentration, - A step to calculate the ion exchange capacity according to the following formula, IEC=[(molfHCI-molesHCI) / m]*1000 During the ceremony, -molf HCl indicates the final number of moles of HCl after immersion of the film. -HCl moles indicates the initial number of moles of HCl before immersion of the membrane. -m represents the mass of the dry film. - The results are expressed in millimoles per gram.

[0082] These five repeated experiments showed an average IEC value of 1.9 mmol / g.

[0083] The electrical resistance and corresponding ionic conductivity of the anion exchange film were calculated using the following procedure. The film was activated in KOH for 24 hours, and then assembled in a 5 cm² electrolytic cell with nickel-based electrodes. -Electrolysis was performed for 1 minute (10 mA / cm²), and then the resistance was measured using HIOKI3560 at 20°C and 60°C.

[0084] Similar measurements were performed on electrolytic cells excluding the same membrane, and the effective electrical resistance (Rm) of the membrane was derived by subtracting the obtained values ​​from the aforementioned values ​​using the following formula. Rm = (R1 - R2) * A During the ceremony, -R1 represents the total electrical resistance of the cell containing the film. -R2 represents the electrical resistance of the cell without the film. -A indicates the area of ​​the electrode.

[0085] The ionic conductivity (Y) was derived from the following equation. y = S / (Rm * A) In the formula, S represents the film thickness.

[0086] The conductivity of the film was found to be 35 ms / cm at 20°C and 75 ms / cm at 60°C.

[0087] For the anion exchange membrane, the water absorption rate (at 20°C and 80°C), the thickness increase rate (at 20°C and 80°C), and the coefficient of linear expansion (at 20°C and 80°C) were measured according to ISO 62:2008(E). The measurement results are shown in the table in Figure 3.

[0088] The tensile strength, Young's modulus, and elongation of the anion exchange membrane were measured according to ISO 153-7. The measurements were performed using a Shimadzu AGS-X SKN instrument. The results are shown in the table in Figure 4.

[0089] Example 2 Anion exchange membranes including the following: -Support made from porous polyolefin material, and -i. A monomer unit having a positive charge capable of moving hydroxide ions, and ii. A monomer unit derived from an acrylic monomer having a saturated linear alkyl chain with 3 or more carbon atoms, and iii. An anion exchange membrane containing a copolymer containing monomer units derived from vinyl aromatic monomers, 54 mol% styrene, 4-Vinyl chloride 30 mol%, Esil methacrylate 15 mol%, - Insert 1 mol% benzoyl peroxide. The product is obtained by maintaining the reactor under a controlled atmosphere for approximately 20 hours.

[0090] Subsequently, 300 mol% acetone (CH3-CO-CH3) was added to the mixture in the reactor, and stirring was continued until the polymer was completely dissolved.

[0091] 1-Methylpyrrolidine was added in molar units (different from the unit of the mixture in the reactor), and then 150 mol% ethanol was added while stirring for 40 hours.

[0092] Subsequently, a 1 mol% benzoyl peroxide solution and a 2 mol% olefin containing aromatic groups with heteroatoms were added. A support made of a polypropylene sheet with a porosity of 50% and an average pore size of 0.5 μm was immersed in the resulting solution, and the entire mixture was maintained at 73°C for approximately 10 hours under a controlled atmosphere.

[0093] The film according to the present invention comprises a polypropylene support to which an active copolymer is chemically bonded, and is obtained by evaporation of a solvent.

[0094] This film possesses characteristics particularly suitable for use in alkaline electrolytic devices, including mechanical properties, high ion exchange capacity and conductivity, and high durability in alkaline environments.

Claims

1. a. A support made of polyolefin material, b. An anion exchange membrane comprising an active copolymer containing positively charged monomer units that can move hydroxide ions, The anion exchange membrane is composed of the active copolymer, c. Monomer units derived from acrylic monomers having a saturated linear alkyl chain with 3 or more carbon atoms, d. Styrene units, e. A vinylbenzyl unit having a benzyl bond substituent, further comprising vinylbenzyl units in which the substituent belongs to piperidine and / or pyrrolidine, An anion exchange membrane in which the copolymer can chemically bond to a support made of the polyolefin material via hydrophobic interactions.

2. The anion exchange membrane according to claim 1, characterized in that the piperidine and / or pyrrolidine is N-alkylpiperidine and / or N-alkylpyrrolidine.

3. The active copolymer is at least An acrylic monomer having a saturated linear alkyl chain with 3 or more carbon atoms, A vinyl benzyl monomer in which a methyl chloride group is bonded to the aromatic ring, The anion exchange membrane according to claim 1 or 2, characterized by comprising a polymerization product of a vinyl aromatic monomer having piperidine and / or pyrrolidine tertiary amine.

4. The anion exchange membrane according to claim 3, characterized in that the tertiary piperidine and / or pyrrolidineamine comprises at least one of 1-methylpyridine, 1-ethylpyridine, 1-propylpiperidine, 1-butylpiperidine, 1,2,6-trimethylpyridine, 1,2,6-triethylpiperidine, 1,2,6-tripropylpiperidine, 1,2,2,6,6-pentamethylpiperidine, 1-methylpyrrolidine, 1-ethylpyrrolidine, 1-propylpyrrolidine, 1-butylpyrrolidine, and 1,2,5-trimethylpyrrolidine.

5. The anion exchange membrane according to claim 3 or 4, characterized in that the acrylic monomer is an ester of acrylic acid in which a linear saturated hydrocarbon chain is bonded to the ester oxygen atom.

6. The acrylic monomers include at least propyl acrylate, butyl acrylate, pentyl acrylate, heptyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecyl acrylate, octadecyl acrylate, nonadecyl acrylate, eicosyl acrylate, propyl methacrylate, butyl methacrylate, and pentyl methacrylate. The anion exchange membrane according to claim 5, characterized by containing one of the following: acrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecyl methacrylate, octadecyl methacrylate, nonadecyl methacrylate, and icosyl methacrylate.

7. The anion exchange membrane according to any one of claims 1 to 6, characterized in that the copolymer comprises 3 mol% to 10 mol% of acrylic units, 40 mol% to 79 mol% of vinyl aromatic units, and 20 mol% to 50 mol% of substituent-containing vinyl benzyl units.

8. The anion exchange membrane according to any one of claims 1 to 7, characterized in that the polyolefin material support is made of a polyethylene-based material selected from PE, LDPE, HDPE, or UHMWPE.

9. The anion exchange membrane according to any one of claims 1 to 7, characterized in that the support made of the polyolefin material is made of a polypropylene-based material.

10. a) Using at least one peroxide radical initiator, i) Acrylic monomers having a saturated linear alkyl chain with 3 or more carbon atoms, ii) A vinyl benzyl monomer in which a methyl chloride group is bonded to an aromatic group, iii) A step of promoting the polymerization of a mixture containing a vinyl aromatic monomer, b) A step of activating the copolymer obtained using tertiary piperidine and / or pyrrolidineamine by promoting the formation of a quaternary ammonium salt by substitution of at least one vinyl benzyl chloride monomer, c) A method for constructing an anion exchange membrane, comprising the step of immersing a film of a polyolefin support in a copolymer liquid solution in the presence of a polar solvent to promote the bonding of the copolymer to the polyolefin support.

11. A method for realizing the anion exchange membrane described in claim 10, - The step of activating the copolymer is performed before the step of promoting the bonding of the copolymer to the polyolefin support. - The polyolefin support is polyethylene-based.

12. A method for realizing an anion exchange membrane according to claim 10, wherein the step of promoting the bonding of the copolymer to the polyolefin support is performed by adding a peroxide radical activator and a radical stabilizer consisting of an olefin having aromatic groups and / or heteroaromatic groups to a liquid solution containing the copolymer and the porous polyolefin support.

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