Composite porous basement membrane and preparation method thereof

Abstract

The invention discloses a composite porous basement membrane and a preparation method thereof. The composite porous basement membrane comprises a porous sulfonated resin basement membrane and a hydrogen bond donor layer at least partially filled in pores of the porous sulfonated resin basement membrane. The interface compatibility and the interface bonding force between the composite porous basement membrane and the functional resin material are excellent, the layering risk is reduced, and an application basis is provided for long-time operation.

Description

Technical Field

[0001] This invention belongs to the field of ion exchange membrane technology, specifically relating to a composite porous substrate membrane and its preparation method. Background Technology

[0002] The following statements are intended to provide background information in relation to the present invention and do not necessarily constitute prior art.

[0003] As an important component of fuel cells and flow batteries, ion exchange membranes need to perform both physical isolation and ion conduction functions. Although they do not participate in electrochemical reactions, they are one of the key technologies that restrict the development and application of batteries. The application performance and operational stability of fuel cells and flow batteries are directly related to ion exchange membranes, and improving the performance of ion exchange membranes plays an important role in improving the overall performance of batteries.

[0004] Currently, the common practice to improve the hydrophilicity of ion exchange membranes is to introduce a hydrophilic layer on the surface. However, the hydrophilic layer is prone to peeling off during long-term use, leading to a decrease in battery performance and safety risks. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a composite porous substrate membrane and its preparation method.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a composite porous substrate membrane, comprising a porous sulfonated resin substrate membrane and a hydrogen bond donor layer at least partially filled within the pores of the porous sulfonated resin substrate membrane.

[0008] In a second aspect, the present invention provides a method for preparing a composite porous substrate membrane as described in the first aspect, the method comprising:

[0009] A solution containing a hydrogen bond donor material is placed on a porous sulfonated resin substrate membrane and then dried to obtain the composite porous substrate membrane.

[0010] Thirdly, an ion exchange membrane includes the composite porous substrate membrane described in the first aspect and a functional resin material layer, wherein the functional resin material layer is disposed on at least one side of the surface of the hydrogen bond donor layer.

[0011] In this invention, by introducing a sulfonated resin base membrane, the sulfonic acid groups on the sulfonated resin can increase the hydrophilicity of the base membrane, which is beneficial for the wetting of the functional resin material solution and improves the compatibility between the base membrane and the functional resin material. At the same time, the sulfonic acid groups can form hydrogen bonds with the functional resin material, thereby improving the bonding force between the two.

[0012] Based on this, the present invention introduces a hydrogen bond donor layer containing multiple hydrogen bond donor groups (such as hydroxyl and / or amino groups), which can form hydrogen bond interactions between the sulfonated resin base film and the functional resin material layer, acting as an "adhesive" between the base film and the functional resin material layer, and significantly improving the interfacial bonding force between the base film and the functional resin material layer.

[0013] Therefore, the composite porous base membrane provided by the present invention has superior hydrophilicity and high interfacial bonding force with the functional resin material layer, reducing the risk of delamination and providing a basis for long-term operation. Detailed Implementation

[0014] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0016] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0017] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0018] This invention provides a composite porous substrate membrane, comprising a porous sulfonated resin substrate membrane and a hydrogen bond donor layer that is at least partially filled within the pores of the porous sulfonated resin substrate membrane.

[0019] The composite porous substrate membrane provided by this invention has the following advantages:

[0020] i. By introducing sulfonated resin base membranes, the sulfonic acid groups on the sulfonated resins can increase the hydrophilicity of the base membrane, which is beneficial for the wetting of functional resin materials in the solution and improves the compatibility between the base membrane and the functional resin materials. At the same time, the sulfonic acid groups can form hydrogen bonds with the functional resin materials, thereby improving the bonding force between the two.

[0021] ii. By introducing a hydrogen bond donor layer containing multiple hydrogen bond donor groups (e.g., hydroxyl and / or amino groups), hydrogen bonds can be formed between the sulfonated resin base film and the functional resin material layer, acting as an "adhesive" between the base film and the functional resin material layer, significantly improving the interfacial bonding force between the base film and the functional resin material layer.

[0022] Therefore, the composite porous base membrane and functional resin material provided by this invention have excellent interfacial compatibility and interfacial bonding, reducing the risk of delamination and providing an application basis for long-term operation.

[0023] In some embodiments, the thickness of the hydrogen bond donor layer is ≤100 nm, for example, 100 nm, 95 nm, 90 nm, 85 nm, 80 nm, 75 nm, 70 nm, 65 nm, 60 nm, 55 nm, 50 nm, 45 nm, 40 nm, 35 nm, 30 nm, 25 nm, 20 nm, 15 nm, 10 nm, 5 nm, or any of the above values.

[0024] In this invention, the thickness of the hydrogen bond donor layer refers to the thickness of the hydrogen bond donor layer on the inner pore wall of the porous sulfonated resin substrate film, or it can be understood as the distance between the surface of the hydrogen bond donor layer and the inner pore wall of the porous sulfonated resin substrate film.

[0025] In this invention, the thickness of the hydrogen bond donor layer can be determined using methods such as scanning transmission electron microscopy (TEM) and elemental analysis.

[0026] In this invention, the thickness of the hydrogen bond donor layer ≤ 100 nm means that the maximum thickness of the hydrogen bond donor layer located on the pore wall inside the porous sulfonated resin substrate membrane is ≤ 100 nm. Within this thickness range, the hydrogen bond donor layer can increase the bonding force between the substrate membrane and the functional resin layer, while not significantly affecting the pore structure of the substrate membrane and the connectivity between the pore structures. This avoids the disadvantages of the modified material causing pore size reduction or even pore blockage. If the thickness of the hydrogen bond donor layer is too high, it may affect the pore structure of the porous sulfonated resin substrate membrane and the connectivity between the pore structures, thus affecting the mass transfer efficiency in subsequent applications.

[0027] In some embodiments, the thickness of the hydrogen bond donor layer is ≥20 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm or any of the above values.

[0028] In this invention, the thickness of the hydrogen bond donor layer ≥20 nm means that the minimum thickness of the hydrogen bond donor layer located on the pore wall inside the porous sulfonated resin base film is ≥20 nm. By further adjusting the minimum thickness of the hydrogen bond donor layer, this invention can further increase the bonding force between the base film and the functional resin material, thereby enabling the composite porous base film to have better hydrophilic properties.

[0029] In this invention, the thickness of the hydrogen bond donor layer is directly measured by transmission electron microscopy (TEM). In the TEM image, since TEM uses electrons to penetrate the ultrathin sample to form an image, the electron scattering ability of the hydrogen bond donor layer and the porous sulfonated resin substrate film is different, forming a contrast between light and dark. Therefore, the thickness of the donor layer inside the pore can be directly measured.

[0030] In some embodiments, the mass percentage of the hydrogen bond donor layer, based on the total mass of the composite porous base membrane as 100%, is 0.5% to 10%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any of the above values, preferably 1% to 5%, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any of the above values.

[0031] This invention, by limiting the mass percentage of the hydrogen bond donor layer, enables the final composite porous substrate membrane to possess both superior hydrophilicity and high interfacial bonding strength with the functional resin material layer. A high hydrogen bond donor layer content may affect the pore structure and connectivity between the pores of the porous sulfonated resin substrate membrane, impacting mass transfer efficiency in subsequent applications. Conversely, a low hydrogen bond donor layer content may affect the interfacial bonding strength between the substrate membrane and the functional resin material, leading to potential delamination during subsequent applications. It is understood that the mass percentage of the hydrogen bond donor layer in this invention can be tested using existing methods such as ultrasonic dissolution followed by weighing, and this invention is not limited to these methods. Specifically, the initial mass of the composite porous base membrane can be denoted as m1. It is placed in a hydrogen donor solvent and subjected to multiple ultrasonic treatments, drying, and weighing until the weight of the composite porous base membrane no longer changes. The mass of the treated composite porous base membrane can then be denoted as m2. The difference between m1 and m2 is the mass of the hydrogen donor layer, which can then be converted into a mass percentage. The hydrogen donor solvent can be water, alcohol, N,N-dimethylformamide (DMF), or a mixture thereof.

[0032] In some embodiments, the hydrogen bond donor layer comprises at least one of small molecule polyols, small molecule polyamines, sugars and their derivatives, and polymeric hydrogen bond donor materials.

[0033] In some embodiments, the small molecule polyol includes glycerol and / or xylitol.

[0034] In some embodiments, the small molecule polyamine includes ethylenediamine and / or hexamethylenediamine.

[0035] In some embodiments, the sugars and derivatives include maltitol.

[0036] In some embodiments, the polymeric hydrogen bond donor material includes at least one of polyglycerol, polyvinyl alcohol, or polyamide.

[0037] In some embodiments, the porosity of the porous sulfonated resin substrate membrane is 30-90%, for example, 30%, 40%, 50%, 60%, 70%, 80%, 90% or any of the above values, preferably 40-70%, for example, 40%, 45%, 50%, 55%, 60%, 65%, 70% or any of the above values.

[0038] In some embodiments, the average pore size of the porous sulfonated resin substrate membrane is 100~1000 nm, for example 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm or any of the above values, preferably 200~500 nm, for example 200 nm, 220 nm, 250 nm, 280 nm, 300 nm, 320 nm, 350 nm, 380 nm, 400 nm, 420 nm, 450 nm, 480 nm, 500 nm or any of the above values.

[0039] In some embodiments, the thickness of the porous sulfonated resin substrate film is 5 to 50 μm, for example, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or any of the above values, preferably 10 to 40 μm, for example, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm or any of the above values.

[0040] The porosity test method of the porous sulfonated resin substrate membrane described in this invention is carried out in accordance with GB / T 33052-2016. The test method is as follows: cut the test sample into 3 pieces each with a length of not less than 10 cm and a width of not less than 5 cm. Accurately measure the length, width and thickness of the sample. Then accurately measure the mass of the initial sample and the mass of the sample filled with hexadecane. Calculate the volume of hexadecane absorbed based on the mass difference. Divide the volume by the sample volume to obtain the porosity.

[0041] The test method for the average pore size of the porous sulfonated resin substrate membrane described in this invention is performed in accordance with GB / T 32361-2015. The specific test method includes: placing dry membrane and wet membrane samples in the membrane holder respectively, tightening the membrane holder and gradually increasing the gas pressure, recording the gas flow rate and corresponding gas pressure data of the dry membrane and wet membrane respectively, and plotting a gas flow rate-pressure graph; drawing a straight line (or curve) corresponding to half of the measured dry membrane gas flow rate, finding the intersection point between the wet membrane gas flow rate line and the dry membrane half-flow rate line, calculating the pressure value at the corresponding intersection point, and substituting it into the pressure-pore size equation to calculate the average pore size.

[0042] The thickness of the porous sulfonated resin substrate film described in this invention is measured using a high-precision thickness gauge, and the average value is taken.

[0043] In some embodiments, the porous sulfonated resin substrate membrane comprises sulfonated resin material and crosslinking agent.

[0044] In some embodiments, the sulfonated resin includes at least one of the following: sulfonated polysulfone material, sulfonated polyethersulfone material, sulfonated polyarylene ethersulfone material, sulfonated polyamide material, sulfonated polyimide material, sulfonated polyetherimide material, sulfonated polyetheretherketone material, sulfonated polyarylene etherketone material, sulfonated polyphenylene sulfide material, sulfonated polyphenylene ether, sulfonated polybenzimidazole material, sulfonated polyphosphonic nitrile material, perfluorosulfonic acid, sulfonated polytetrafluoroethylene, or sulfonated polyvinylidene fluoride.

[0045] In some embodiments, the degree of sulfonation of the sulfonated resin is 10-30%, for example, 10%, 15%, 20%, 25%, 30% or any of the above values, preferably 15-30%, for example, 15%, 18%, 20%, 22%, 25%, 28%, 30% or any of the above values.

[0046] If the sulfonation is too high, the porous sulfonated resin base membrane will have good hydrophilicity. Although it can undergo cross-linking treatment, it may still cause severe swelling of the porous sulfonated resin base membrane, reduce its mechanical strength, and thus result in poor reinforcement of the base membrane. If the sulfonation is too low, the number of sulfonic acid groups on the surface will be small, making it difficult to carry out an effective cross-linking reaction with the cross-linking agent.

[0047] In some embodiments, the crosslinking agent includes at least one of epoxy, aldehyde, bismaleimide, or organosilicon, and more preferably, the crosslinking agent includes any one or a combination of at least two of polyethylene glycol diglycidyl ether (PEGDGE), glutaraldehyde, bismaleimide, or 3-aminopropyltriethoxysilane (APTES).

[0048] This invention improves the mechanical properties of a porous sulfonated resin base membrane by introducing a crosslinking agent into the membrane, thereby further crosslinking the agent with the resin and eliminating the influence of the selected resin on the mechanical properties.

[0049] In some embodiments, the mass ratio of the sulfonated resin material to the crosslinking agent is 100:(0.5~5), for example, 100:0.5, 100:1, 100:2, 100:3, 100:4, 100:5 or any range of the above values, more preferably 100:(1~3), for example, 100:1, 100:1.2, 100:1.5, 100:1.8, 100:2, 100:2.2, 100:2.5, 100:2.8, 100:3 or any range of the above values.

[0050] This invention also provides a method for preparing the above-mentioned composite porous substrate membrane.

[0051] The method includes the following steps: preparing a base membrane using a pore-forming agent; optionally, impregnating the base membrane with a crosslinking agent solution and performing a crosslinking reaction to obtain a porous sulfonated resin base membrane; placing a solution containing a hydrogen bond donor material on the porous sulfonated resin base membrane and drying it to obtain the composite porous base membrane.

[0052] This invention first prepares a porous sulfonated resin substrate membrane, and then forms a hydrogen bond donor layer inside and on one side of the porous sulfonated resin substrate membrane. The design method has the following advantages:

[0053] i. Compared with introducing hydrogen bond donor materials during casting, the preparation method provided by the present invention can avoid the drawbacks of hydrogen bond donor materials reacting with casting solvents and / or crosslinking agents, without affecting the formation and reaction crosslinking of the base film, and without affecting the thermodynamic properties of the casting solution, thus avoiding problems such as uneven pore size distribution, pore blockage or film cracking caused by interfering with the phase separation process.

[0054] ii. Compared to introducing hydrogen bond donor materials during casting, hydrogen bond donor materials may act as "plasticizers" and be dispersed and deposited at the bottom of the substrate film, which can lead to a decrease in the glass transition temperature and mechanical properties of the substrate film. They may also block pores and damage the porous structure. The preparation method provided by this invention can form a hydrogen bond donor layer with a thickness of ≤100 nm inside and on the surface of the substrate film. This method can avoid affecting the porous structure of the substrate film and preserve the original porous structure and mechanical strength of the substrate film.

[0055] iii. Compared to introducing hydrogen bond donor materials during casting, the preparation method provided by the present invention enables the hydrogen bond donor material to form a hydrogen bond donor layer with a thickness of ≤100 nm inside and on the surface of the substrate film, which can fully participate in the bonding between the substrate film and the functional resin material.

[0056] In some embodiments, the method for preparing a base membrane using a porogen is a known existing method. Any method that can use a porogen to prepare a base membrane can be applied to this invention. This invention is only provided as an example.

[0057] In some embodiments, the method for preparing a base film using a porogen includes: dissolving a sulfonated resin in an organic solvent to obtain a resin solution; mixing the resin solution with a porogen to obtain a slurry; casting the slurry, drying it, and impregnating it with deionized water to obtain a base film.

[0058] In some embodiments, the sulfonated resin includes, but is not limited to, at least one of the following: sulfonated polysulfone materials, sulfonated polyethersulfone materials, sulfonated polyarylene ethersulfone materials, sulfonated polyamide materials, sulfonated polyimide materials, sulfonated polyetherimide materials, sulfonated polyetheretherketone materials, sulfonated polyarylene etherketone materials, sulfonated polyphenylene sulfide materials, sulfonated polyphenylene ether materials, sulfonated polybenzimidazole materials, sulfonated polyphosphonic nitrile materials, perfluorosulfonic acid, sulfonated polytetrafluoroethylene, or sulfonated polyvinylidene fluoride.

[0059] In some embodiments, the organic solvent includes, but is not limited to, at least one of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or N-methylpyrrolidone (NMP).

[0060] In some embodiments, the dissolution method may be magnetic stirring or mechanical stirring. Optionally, the dissolution temperature is higher than room temperature to accelerate dissolution and allow the resin segments to fully extend. Optionally, the dissolution temperature is ≥50°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C or any range between the above values.

[0061] In some embodiments, the solid content of the resin solution is ≤20 wt%, for example 20 wt%, 18 wt%, 15 wt%, 12 wt%, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, or any of the above values, preferably ≤10 wt%. A lower solid content results in a lower viscosity of the resin solution, which is beneficial for the subsequent dispersion and removal of the pore-forming agent.

[0062] In some embodiments, the pore-forming agent is selected from soluble salts, and optionally, the cation of the soluble salt includes Na.+ K + NH4 + Al 3+ Mg 2+ Ca 2+ Zn 2+ Ba 2+ Anions include Cl. - NO3 - SO4 2- CO3 2- Optionally, the soluble salt includes various water-soluble salts such as NaCl, NaNO3, Na2SO4, K2CO3, NH4Cl, and AlCl3.

[0063] In some embodiments, the amount of pore-forming agent added is 25-400% of the resin solids mass in the slurry, for example, it can be 25%, 35%, 45%, 55%, 80%, 95%, 100%, 120%, 150%, 180%, 200%, 250%, 300%, 350%, 400% or any range of the above values.

[0064] In some embodiments, the mixing method includes magnetic stirring or ultrasonic stirring. Optionally, stirring is performed for 0.5 to 2 hours, for example, 0.5 hours, 0.8 hours, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours or any of the above values, followed by ultrasonic stirring for 0.5 to 2 hours, for example, 0.5 hours, 0.8 hours, 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours or any of the above values, to ensure that the pore-forming agent is uniformly dispersed and free from agglomeration.

[0065] In some embodiments, the casting method includes casting the slurry on a flat substrate, which may include a glass plate, a metal plate, a silicon wafer, etc.

[0066] In some embodiments, the drying method includes gradient drying molding, optionally first drying at 30-40°C (e.g., 30°C, 32°C, 35°C, 38°C, 40°C or any of the above values) for 1-2 hours, e.g., 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours or any of the above values, to slowly remove the organic solvent from the wet film surface; then accelerating the temperature to 40-60°C at 0.1-1°C / min (e.g., 0.1°C / min, 0.2°C / min, 0.5°C / min, 0.8°C / min, 1°C / min or any of the above values), e.g., 40°C, 45°C, 50°C, 55°C, 60°C or any of the above values, to accelerate the evaporation rate of the organic solvent; finally, drying to 60-80°C, e.g., 60°C, 65°C, 70°C, 75°C, 80°C or any of the above values, for 1-1.5 hours, e.g., 1 hour. The solvent is removed within a range of h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, or any of the above values.

[0067] In some implementations, the soaking time includes 1 to 3 days, such as 1 day, 2 days, 3 days or any range between the above values, during which the deionized water needs to be replaced at least once.

[0068] In some embodiments, the process of impregnating the base membrane with a crosslinking agent solution and performing a crosslinking reaction specifically includes: immersing the base membrane in the crosslinking agent solution; after impregnation, removing the base membrane, removing excess solution from the surface, and then performing a crosslinking reaction; after the reaction, removing the unreacted crosslinking agent, and drying to obtain the porous sulfonated resin base membrane.

[0069] In some embodiments, the mass ratio of the sulfonated resin material to the crosslinking agent is 100:(0.5~5), for example, 100:0.5, 100:1, 100:2, 100:3, 100:4, 100:5 or any range of the above values, more preferably 100:(1~3), for example, 100:1, 100:1.2, 100:1.5, 100:1.8, 100:2, 100:2.2, 100:2.5, 100:2.8, 100:3 or any range of the above values.

[0070] In some embodiments, the solvent used in the crosslinking agent solution is a mixture of an organic solvent and deionized water. Optionally, the volume ratio of the organic solvent to the deionized water is 1:1. Optionally, the organic solvent includes, but is not limited to, at least one of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or N-methylpyrrolidone (NMP). Optionally, the mass fraction of the crosslinking agent in the crosslinking agent solution is 1 to 5%, for example, 1%, 2%, 3%, 4%, 5%, or any of the above values.

[0071] In some embodiments, the immersion temperature in the crosslinking agent solution is 40~60°C, for example 40°C, 45°C, 50°C, 55°C, 60°C or any of the above values, and the time is 2~4 h, for example 2 h, 2.5 h, 3 h, 3.5 h, 4 h or any of the above values. Within this temperature and time range, the crosslinking agent can fully penetrate into the interior of the porous sulfonated resin base film.

[0072] In some embodiments, the crosslinking reaction is carried out in a vacuum environment. Optionally, the temperature of the crosslinking reaction is 100~120°C, for example 100°C, 105°C, 110°C, 115°C, 120°C or any of the above values, and the time is 3~6 h, for example 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h or any of the above values.

[0073] In some embodiments, the concentration of the solution containing the hydrogen bond donor material is 1 to 20 wt%, for example 1 wt%, 2 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, or any of the above values, preferably 3 to 15 wt%.

[0074] In this invention, the solution concentration specified by this invention allows the hydrogen bond donor material to enter the interior of the porous sulfonated resin substrate membrane without overfilling the pores, thus avoiding the impact on the porous sulfonated resin substrate membrane due to the introduction of the hydrogen bond donor material.

[0075] In some embodiments, the method of setting includes immersion or coating, and the coating method includes bar coating, blade coating, or spray coating.

[0076] In some embodiments, the immersion or coating temperature is 30~50°C, for example 30°C, 35°C, 40°C, 45°C, 50°C or any of the above values, and the time is 0.5~2 h, for example 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h or any of the above values.

[0077] In some embodiments, the porous sulfonated resin substrate membrane is impregnated with a solution containing hydrogen bond donor material by vacuum impregnation, which can accelerate the penetration of the hydrogen bond donor material.

[0078] In some embodiments, the drying method includes removing excess solution from the surface followed by vacuum drying.

[0079] In this invention, by impregnating or coating a porous sulfonated resin base membrane with a solution containing a hydrogen bond donor material, the hydrogen bond donor material can enter the interior of the porous sulfonated resin base membrane and form stable hydrogen bonds with the sulfonic acid groups included therein. At the same time, the excess hydroxyl and / or amino groups can also form hydrogen bonds with the functional resin material, thereby bonding the functional resin material layer with the porous sulfonated resin base membrane and forming a tight interfacial bond between the two.

[0080] This invention also provides an ion exchange membrane, comprising the composite porous substrate membrane described in the first aspect and a functional resin material layer, wherein the functional resin material layer is disposed on at least one side of the surface of the hydrogen bond donor layer.

[0081] Unless otherwise specified, the raw materials involved in the following specific embodiments of the present invention are all conventional materials in the art, and can be purchased from commercially available products. Some raw material information is as follows:

[0082] Sulfonated Resin 1: Sulfonated polysulfone material with a sulfonation degree of 30%, purchased from Shanghai Chenyihui Plastic Co., Ltd.;

[0083] Sulfonated Resin 2: Sulfonated polyether ether ketone material with a sulfonation degree of 30%, purchased from Dongguan Tianzhihong Plastic Co., Ltd.

[0084] Sulfonated Resin 3: Sulfonated polyphenylene sulfide material, with a sulfonation degree of 20%, purchased from Sabic;

[0085] Polyethylene glycol diglycidyl ether: PEGDGE, purchased from Aladdin, model number P579486;

[0086] Ethylene-vinyl acetate copolymer: purchased from Aladdin, model number P432375.

[0087] Examples 1-11

[0088] This embodiment provides a composite porous base membrane and its preparation method. The composite porous base membrane includes a porous sulfonated resin base membrane and a hydrogen bond donor layer that at least partially fills the pores of the porous sulfonated resin base membrane. The preparation method is as follows:

[0089] (1) Preparation of casting solution

[0090] Sulfonated resin material was dissolved in DMF under mechanical stirring at 50℃ to obtain a resin solution with a solid content of 10 wt%. Then, a pore-forming agent was added and stirred for 2 h, followed by ultrasonication for 0.5 h to obtain a casting solution.

[0091] (2) Preparation of basement membrane

[0092] The casting solution was cast onto a glass plate and then dried at 35°C for 1.5 h. The temperature was then increased to 40°C at a rate of 1°C / min, and finally increased to 60°C and dried for 1.5 h to remove most of the solvent. The film and glass plate were then immersed in deionized water for 1 day, during which the deionized water was changed three times to obtain the base film.

[0093] (3) Crosslinking to obtain a porous sulfonated resin substrate membrane

[0094] A crosslinking agent solution was prepared by dissolving the crosslinking agent in a mixed solvent of DMF and water at a volume ratio of 1:1.

[0095] The base membrane is immersed in a crosslinking agent solution. After immersion, the porous sulfonated resin base membrane is removed, excess solution is removed from the surface, and then a crosslinking reaction is carried out in a vacuum environment. After the reaction, the unreacted crosslinking agent is removed by rinsing with water and then dried to obtain a porous sulfonated resin base membrane.

[0096] (4) Modification of hydrogen bond donor layer

[0097] Hydrogen bond donor materials are dissolved in water to prepare hydrogen bond donor material solutions;

[0098] Under vacuum conditions, a hydrogen bond donor material solution was placed on a porous sulfonated resin substrate membrane, and then vacuum dried at 60°C for 2 h to obtain a composite porous substrate membrane.

[0099] The specific parameters of some examples 1 to 11 are shown in Table 1-2.

[0100] Table 1

[0101]

[0102] Table 2

[0103]

[0104] Comparative Example 1

[0105] This comparative example provides a composite porous base membrane and its preparation method.

[0106] The difference from Example 1 is that, in this comparative example, the same mass of hydrogen bond donor material is added to the casting solution, and the thickness of the final composite porous substrate membrane is controlled to be the same as that of the composite porous substrate membrane provided in Example 1, while step (4) is omitted.

[0107] Comparative Example 2

[0108] This comparative example provides a composite porous base membrane and its preparation method.

[0109] The difference from Example 1 is that, in this comparative example, the hydrogen bond donor material is replaced with an ethylene-vinyl acetate copolymer.

[0110] Comparative Example 3

[0111] This comparative example provides a composite porous base membrane and its preparation method.

[0112] The difference from Example 1 is that step (3) is not performed in this comparative example.

[0113] Comparative Example 4

[0114] This comparative example provides a porous basement membrane and its preparation method.

[0115] The difference from Example 1 is that step (4) is not performed in this comparative example.

[0116] Performance testing

[0117] The structural and performance characteristics of the samples provided in the examples and comparative examples were characterized as follows:

[0118] (1) Peel strength: Sulfonated polysulfone resin material (Shanghai Chenyihui Plastic Co., Ltd.) was dissolved in NMP to prepare a 15 wt% solution. The solution was directly cast onto the composite porous substrate membrane provided in the above examples or comparative examples to form a functional layer. Then, it was dried in an oven at 80℃ for 12 h to obtain an ion exchange membrane. The thickness of the functional layer was 20 μm. The peel strength was tested according to GB / T 8808-1988. The test method was as follows: For a 200 mm × 15 mm sample, 50 mm was removed from both ends in the width direction. Five longitudinal and five transverse samples were cut evenly along the width direction of the sample. The functional layer and the composite porous substrate membrane were peeled apart by 50 mm along the length direction of the sample. Then, the two ends of the peeled part were clamped on the upper and lower clamps of the testing machine, respectively. The peel force curve during the peeling process of the sample was recorded, and the peel strength was calculated.

[0119] (2) Hydrophilicity: The water contact angle is used to determine the hydrophilicity. The test is conducted in accordance with GB / T 30693-2014. The method is as follows: the dry sample is fixed on the test stage to ensure that the surface is horizontal. The position of the needle is adjusted so that it is perpendicular to the membrane surface and the distance is about 1~2 mm. Then, ultrapure water is slowly added through a micro-syringe (at a speed of about 1 μL / s) to form a stable droplet. The measurement is taken immediately after the droplet contacts the surface (<5 s) to avoid the liquid penetration affecting the results. More than 5 test points are randomly selected for each sample (the distance between the points is ≥5 mm), and the average value is taken.

[0120] The results are as follows:

[0121] Table 3

[0122]

[0123] Note:

[0124] Since the hydrogen bond donor material was directly added to the casting solution in Comparative Example 1, the structural characterization of the porous sulfonated resin substrate membrane in Comparative Example 1 was actually performed on the composite porous substrate membrane obtained in Comparative Example 1.

[0125] Since no crosslinking reaction is performed in Comparative Example 3, the structural characterization of the porous sulfonated resin substrate membrane in Comparative Example 3 is actually performed on the substrate membrane obtained in step (2).

[0126] As can be seen from the examples and performance tests, the composite porous base membrane provided by the present invention has excellent hydrophilicity and high interfacial bonding force with the functional resin material layer, which reduces the risk of delamination.

[0127] As can be seen from the comparison of Examples 1-5, the present invention, by controlling the concentration of the hydrogen bond donor material solution, can maintain the mass percentage of the hydrogen bond donor layer within a certain range, thereby resulting in a composite porous substrate membrane with both superior hydrophilicity and high interfacial bonding with the functional resin material layer. When the concentration of the hydrogen bond donor material solution is too high, the improvement in hydrophilicity becomes less significant, and the production cost and process difficulty increase.

[0128] As can be seen from the comparison of Examples 1 and 6-9, the present invention improves the mechanical properties of porous sulfonated resin base membrane by limiting the mass ratio of sulfonated resin material to crosslinking agent to 100:(0.5~5), while ensuring the excellent hydrophilicity of composite porous base membrane and high interfacial bonding force with functional resin material layer.

[0129] As can be seen from the comparison between Example 1 and Comparative Example 1, the preparation method provided by the present invention can make the composite porous base membrane have better hydrophilicity while having higher interfacial bonding force with the functional resin material layer.

[0130] As can be seen from the comparison between Example 1 and Comparative Example 2, the hydrogen bond donor material defined in this invention can improve the hydrophilicity of the composite porous substrate membrane and at the same time improve the interfacial bonding force between it and the functional resin material layer.

[0131] As can be seen from the comparison of Example 1 and Comparative Examples 3-4, the crosslinking agent and hydrogen bond donor material specified in this invention are both indispensable.

[0132] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A composite porous substrate membrane, characterized in that, It includes a porous sulfonated resin base membrane and a hydrogen bond donor layer that is at least partially filled within the pores of the porous sulfonated resin base membrane.

2. The composite porous substrate membrane according to claim 1, characterized in that, The thickness of the hydrogen bond donor layer is ≤100nm; Preferably, the thickness of the hydrogen bond donor layer is ≥20 nm.

3. The composite porous substrate membrane according to claim 1 or 2, characterized in that, Based on the total mass of the composite porous substrate membrane as 100%, the mass percentage of the hydrogen bond donor layer is 0.5-10%, preferably 1-5%.

4. The composite porous substrate membrane according to any one of claims 1 to 3, characterized in that, The hydrogen bond donor layer is composed of at least one of the following: small molecule polyols, small molecule polyamines, sugars and their derivatives, and polymeric hydrogen bond donor materials. Preferably, the small molecule polyol includes glycerol and / or xylitol; Preferably, the small molecule polyamine includes ethylenediamine and / or hexamethylenediamine; Preferably, the sugars and derivatives include maltitol; Preferably, the polymeric hydrogen bond donor material includes at least one of polyglycerol, polyvinyl alcohol, or polyamide.

5. The composite porous substrate membrane according to any one of claims 1 to 4, characterized in that, The porosity of the porous sulfonated resin substrate membrane is 30-90%, preferably 40-70%; And / or, the average pore size of the porous sulfonated resin substrate membrane is 100~1000 nm, preferably 200~500 nm; And / or, the thickness of the porous sulfonated resin substrate film is 5~50 μm, preferably 10~40 μm.

6. The composite porous substrate membrane according to any one of claims 1 to 5, characterized in that, The porous sulfonated resin substrate membrane comprises sulfonated resin material and crosslinking agent; Preferably, the sulfonated resin includes at least one of the following: sulfonated polysulfone material, sulfonated polyethersulfone material, sulfonated polyarylene ethersulfone material, sulfonated polyamide material, sulfonated polyimide material, sulfonated polyetherimide material, sulfonated polyetheretherketone material, sulfonated polyarylene etherketone material, sulfonated polyphenylene sulfide material, sulfonated polyphenylene ether material, sulfonated polybenzimidazole material, sulfonated polyphosphonic nitrile material, perfluorosulfonic acid, sulfonated polytetrafluoroethylene, or sulfonated polyvinylidene fluoride. Preferably, the degree of sulfonation of the sulfonated resin is 10-30%, more preferably 15-30%; Preferably, the crosslinking agent includes at least one of epoxy, aldehyde, bismaleimide or organosilicon, and more preferably the crosslinking agent includes any one or a combination of at least two of polyethylene glycol diglycidyl ether, glutaraldehyde, bismaleimide or 3-aminopropyltriethoxysilane; Preferably, the mass ratio of the sulfonated resin material to the crosslinking agent is 100:(0.5~5), and more preferably 100:(1~3).

7. A method for preparing a composite porous substrate membrane as described in any one of claims 1 to 6, characterized in that, The preparation method includes: A solution containing a hydrogen bond donor material is placed on a porous sulfonated resin substrate membrane and then dried to obtain the composite porous substrate membrane.

8. The preparation method according to claim 7, characterized in that, The concentration of the solution containing the hydrogen bond donor material is 1-20 wt%, preferably 3-15 wt%. Preferably, the method of setting includes impregnation or coating; Preferably, the impregnation is carried out under vacuum conditions, and more preferably, the impregnation temperature is 30~50°C and the time is 0.5~2 h.

9. The preparation method according to claim 7 or 8, characterized in that, The method for preparing the porous sulfonated resin substrate membrane includes: A porous membrane is obtained by coating, drying, and removing the porogen from a sulfonated resin slurry containing a porogen. The porous membrane is impregnated with a crosslinking agent solution and subjected to a crosslinking reaction to obtain the porous sulfonated resin substrate membrane.

10. An ion exchange membrane, characterized in that, The composite porous substrate membrane and the functional resin material layer are included in any one of claims 1 to 6, wherein the functional resin material layer is disposed on at least one side of the surface of the hydrogen bond donor layer.

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