A polyimide resin, a gas separation membrane, and a method for producing the same

Abstract

The polyimide resin is prepared through a diamine monomer and a triptycene-2,3,6,7,14,15-hexacarboxylic anhydride structure, and the polyimide resin contains the triptycene-2,3,6,7,14,15-hexacarboxylic anhydride structure in a molecular chain. The gas separation membrane is composed of the polyimide resin. The polyimide resin provided by the present disclosure is used for preparing the gas separation membrane.

Description

Technical Field

[0001] This disclosure relates to the field of gas separation membrane technology, and in particular to a polyimide resin, a gas separation membrane, and a method for preparing the same. Background Technology

[0002] As a substitute for fossil fuels in the global energy transition, the demand for hydrogen separation and production has been growing worldwide. However, commonly used centralized hydrogen production methods all produce byproducts, making it impossible to use hydrogen directly. These byproducts need to be separated, and gas separation membranes have attracted increasing attention due to their advantages such as no secondary pollution and simple equipment.

[0003] However, polyimide gas separation membranes, which are commonly used in gas separation membrane materials, are prone to aging and plasticization, which greatly reduces the service life of the membrane. Summary of the Invention

[0004] The purpose of this disclosure is to provide a polyimide resin, a gas separation membrane, and a method for preparing the same, which provides a gas separation membrane material and gas separation membrane with good anti-aging, anti-plasticization, solvent resistance, permeability, and selectivity.

[0005] To achieve the above objectives, this disclosure provides the following technical solution:

[0006] A polyimide resin, wherein the polyimide resin has the following structural formula:

[0007] In the formula, n is a natural number greater than 1, and R1 is an aromatic diamine residue;

[0008] The polyimide resin contains a triterpenoid-2,3,6,7,14,15-hexacarboxylic acid trianic acid structure in its molecular chain.

[0009] Compared with existing technologies, the polyimide resin provided in this disclosure has a three-dimensional rigid structure, as determined by its structural formula. This structure stabilizes the internal molecular cavities of the polyimide resin, resulting in better solvent resistance, aging resistance, and plasticization resistance. Because multiple three-dimensional rigid structures can form a highly interconnected three-dimensional network structure through covalent bonds, when this polyimide resin is used to prepare gas separation membranes, the highly interconnected three-dimensional network structure restricts the contraction, expansion, and movement of the molecular chains, thus further enhancing its solvent resistance, aging resistance, and plasticization resistance. Meanwhile, the highly interconnected three-dimensional network structure also provides support, keeping the molecular cavities inside the gas separation membrane in a stable state, thereby preventing the tight packing of molecular chains within the gas separation membrane. Using tripterene-2,3,6,7,14,15-hexacarboxylic trihydric acid as the crosslinking center, the spacing between molecular chains is relatively fixed, improving the selectivity and permeability of the gas separation membrane.

[0010] This disclosure also provides a gas separation membrane, which is composed of the above-described polyimide resin.

[0011] Compared with the prior art, the beneficial effects of the gas separation membrane provided in this disclosure are the same as those of the polyimide resin described in the above technical solution, and will not be repeated here.

[0012] This disclosure also provides a method for preparing a gas separation membrane, used to prepare the above-mentioned gas separation membrane, the method comprising:

[0013] Under the first reaction conditions, triterpenoid-2,3,6,7,14,15-hexacarboxylic trihydride was added to a mixture of a first organic solvent and a diamine monomer to obtain a spinning solution.

[0014] The second organic solvent and water are mixed to obtain the core fluid;

[0015] Under the second reaction conditions, the spinning solution and the core solution are mixed and extruded into a coagulation bath for spinning to obtain a pre-made gas separation membrane;

[0016] The pre-made gas separation membrane is washed and dried to obtain a gas separation membrane.

[0017] Compared with the prior art, the beneficial effects of the gas separation membrane preparation method provided in this disclosure are the same as the beneficial effects of the polyimide resin described in the above technical solution, and will not be repeated here. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of this disclosure and form part of this disclosure, illustrate exemplary embodiments of the present disclosure and are used to explain the disclosure, but do not constitute an undue limitation of the disclosure. In the drawings:

[0019] Figure 1 A schematic flowchart of a method for preparing a polyimide resin according to an exemplary embodiment of the present disclosure is shown;

[0020] Figure 2 A schematic flowchart of a method for preparing a gas separation membrane according to an exemplary embodiment of the present disclosure is shown;

[0021] Figure 3 A schematic flowchart of a method for obtaining spinning solution in step 200 according to an exemplary embodiment of the present disclosure is shown;

[0022] Figure 4 A schematic flowchart of a method for obtaining a gas separation membrane in step 230 according to an exemplary embodiment of the present disclosure is shown. Detailed Implementation

[0023] Embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0024] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0025] In the context of this disclosure, when a layer / element is referred to as being "on top of" another layer / element, the layer / element may be directly on top of the other layer / element, or there may be an intermediate layer / element between them. Additionally, if a layer / element is "on top of" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element. To make the technical problems, technical solutions, and beneficial effects to be solved by this disclosure clearer, this disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this disclosure and are not intended to limit this disclosure.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise expressly and specifically defined. "Several" means one or more, unless otherwise expressly and specifically defined.

[0027] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0028] Hydrogen is the energy source with the highest energy content per unit weight among known fuels, and its reserves are abundant. As the only byproduct of its use, water, hydrogen is gradually becoming an alternative to fossil fuels in the global energy transition. The demand for hydrogen separation and production in various countries has been growing.

[0029] Hydrogen can be produced through various processes, with common methods including coal-to-hydrogen, methane steam reforming, and production from industrial by-product gases. The tail gases from these methods all contain by-products, meaning the hydrogen cannot be used directly. For example, coal-to-hydrogen tail gas mainly contains N2, CO, CO2, and CH4, while methane steam reforming tail gas mainly contains CH4, CO, and CO2. Industrial by-product gas production includes by-product gas from the chlor-alkali industry, coke oven gas from coal chemical processes, hydrogen from light hydrocarbon cracking, and purge gases from ammonia synthesis and methanol production. In coal chemical coke oven gas production, H2 needs to be separated from CH4, CO, unsaturated hydrocarbons above C2, CO2, and N2. In ammonia synthesis and methanol purge gases, H2 needs to be separated from inert gases such as N2 and Ar.

[0030] Compared to pressure swing adsorption and cryogenic separation, membrane separation devices are simple, consume less energy, require less investment, do not involve phase changes during the separation process, and produce no secondary pollution. They are a highly efficient and simple gas separation method that has attracted increasing attention.

[0031] Among gas separation membrane materials, polymer membranes are the most commercially valuable due to their ease of production, tunable structure, and relatively low cost. Aromatic polyimides, with their excellent heat and solvent resistance, have become the mainstream material for gas separation membranes. However, aromatic polyimide gas separation membranes suffer from easy aging and plasticization, significantly reducing their service life.

[0032] To overcome the aforementioned problems, an exemplary embodiment of this disclosure provides a polyimide resin. Because the molecular chain of this polyimide resin contains a tripterene-2,3,6,7,14,15-hexacarboxylic acid trianic acid structure, the internal molecular cavity of the polyimide resin is stable, resulting in good solvent resistance, aging resistance, and plasticization resistance. When this polyimide resin is used to prepare a gas separation membrane, the multiple three-dimensional rigid structures within the polyimide resin can form a highly interconnected three-dimensional network structure through interconnected covalent bonds, thereby further enhancing the polyimide resin's solvent resistance, aging resistance, and plasticization resistance.

[0033] An exemplary embodiment of this disclosure provides a polyimide resin with the following structural formula:

[0034] In the formula, n is a natural number greater than 1, and R1 is an aromatic diamine residue.

[0035] The polyimide resin contains a tripterene-2,3,6,7,14,15-hexacarboxylic trianate structure in its molecular chain, which is a three-dimensional rigid structure. Multiple three-dimensional rigid structures can form a highly interconnected three-dimensional network structure through covalent bonds, reducing the mobility between molecular chains. Therefore, when using this polyimide resin to prepare gas separation membranes, the membranes exhibit good plasticization resistance. Simultaneously, the highly interconnected network structure stabilizes the internal molecular cavities of the gas separation membrane, improving its aging resistance. Due to the supporting nature of the three-dimensional rigid structure, the molecular chains of the three-dimensional network structure formed by multiple interconnected three-dimensional rigid structures have a relatively fixed spacing and do not pile up. Therefore, the gas separation membrane exhibits good permeability and selectivity.

[0036] As can be seen from the above, the polyimide resin provided in the exemplary embodiments of this disclosure has a three-dimensional rigid structure, as determined by its structural formula. This stabilizes the internal molecular cavities of the polyimide resin, resulting in good solvent resistance, aging resistance, and plasticization resistance. Since multiple three-dimensional rigid structures can form a highly interconnected three-dimensional network structure through interconnected covalent bonds, when this polyimide resin is used to prepare a gas separation membrane, the highly interconnected three-dimensional network structure restricts the contraction, expansion, and movement of the molecular chains, thus improving the solvent resistance, aging resistance, and plasticization resistance of the polyimide resin. Meanwhile, the highly interconnected three-dimensional network structure also provides support, keeping the molecular cavities inside the gas separation membrane in a stable state, thereby preventing the tight packing of molecular chains within the gas separation membrane. Using tripterene-2,3,6,7,14,15-hexacarboxylic trihydric acid as the crosslinking center, the spacing between molecular chains is relatively fixed, improving the selectivity and permeability of the gas separation membrane.

[0037] As one possible implementation, R1 is selected from any of the following groups:

[0038] , , , , , , , , .

[0039] For example, R1 can be It can be It can be It can be It can be It can be It can be It can also be used for .

[0040] Figure 1 A schematic flowchart illustrating a method for preparing a polyimide resin according to exemplary embodiments of the present disclosure is shown. Figure 1 As shown, the method for preparing the polyimide resin is used to prepare the above-mentioned polyimide resin, and the method includes:

[0041] Step 100: At a temperature of -80℃ to -10℃, add triptene-2,3,6,7,14,15-hexacarboxylic trihydric acid to a mixture of organic solvent and diamine monomer to obtain a polyamic acid solution. The mass fraction of polyamic acid in the polyamic acid solution is 10%-40%, for example, it can be 10%, 20%, or 40%, etc., and is not limited thereto. It should be understood that the reaction temperature here can be -80℃, -50℃, or 10℃, etc., and is not limited thereto. By preparing polyimide resin at low temperatures, the gelation time of polyimide resin can be extended, and the yield of polyimide resin can be improved. It should be noted that when preparing polyimide resin, a dry, inert gas-protected environment needs to be maintained to protect the intermediate product polyamic acid and prevent hydrolysis during the preparation of polyimide resin. The inert gas here can be nitrogen or other inert gases.

[0042] The aforementioned organic solvent can be a good solvent for dissolving polyamic acid. Specifically, the organic solvent may include one or more of N-methylpyrrolidone, dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, and N,N-dimethylformamide. Exemplarily, the aforementioned organic solvent may include N-methylpyrrolidone, may include dimethylacetamide, may include tetrahydrofuran, may include dimethyl sulfoxide, may include N,N-dimethylformamide, and may also include N-methylpyrrolidone and dimethylacetamide, etc., and is not limited thereto.

[0043] For example, the mass ratio of tripterene-2,3,6,7,14,15-hexacarboxylic tricornis to the diamine monomer is 1:(1-1.5) to ensure that the tripterene-2,3,6,7,14,15-hexacarboxylic tricornis reacts completely. For example, the mass ratio of the diamine monomer to tripterene-2,3,6,7,14,15-hexacarboxylic tricornis can be 1:1, 1:1.2, or 1:1.5, etc., and is not limited thereto. The selection of the diamine monomer is not limited in this disclosure; any diamine monomer that can react with tripterene-2,3,6,7,14,15-hexacarboxylic tricornis is within the scope of this disclosure. For example, the diamine monomer may include one or more of 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, and 4,4'-diaminobiphenyl. For example, the diamine monomer can be 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-diaminobiphenyl, or 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, and 4,4'-diaminobiphenyl, etc., and is not limited thereto.

[0044] Step 110: Imidate the polyamic acid solution to obtain a polyimide resin. It should be understood that the imidation treatment here may include chemical imidation and thermal imidation. When the imidation treatment is chemical imidation, proceed to step 120; when the imidation treatment is thermal imidation, proceed to step 130.

[0045] Step 120: A catalyst and a dehydrating agent are added to the polyamic acid solution to carry out a chemical imidization reaction to obtain polyimide resin. The catalyst is used to accelerate the reaction process, and the dehydrating agent is used to remove water from the reaction to obtain the polyimide resin. It should be understood that the catalyst here includes one or more of β-pyrrololine, isoquinoline, triethylenediamine, and pyridine. For example, the catalyst may include β-pyrrololine, may include isoquinoline, may include triethylenediamine, may include pyridine, and may include triethylenediamine and pyridine, etc., and is not limited thereto. The dehydrating agent may include acetic anhydride.

[0046] Step 130: The polyamic acid solution is subjected to thermal imidization treatment using a stepped heating method to obtain polyimide resin. Using a stepped heating method ensures a more uniform reaction, allowing the polyamic acid to be completely converted into polyimide. It should be noted that the stepped heating rate can be 2℃ / min-4℃ / min. For example, the temperature can be initially raised to the first temperature at a rate of 4℃ / min, then the heating rate can be reduced to 2℃ / min. This extends the heating time between the first and second temperatures, allowing for a more complete conversion of the polyamic acid into polyimide.

[0047] An exemplary embodiment of this disclosure also provides a gas separation membrane composed of the aforementioned polyimide resin. This gas separation membrane exhibits good aging resistance, plasticization resistance, solvent resistance, permeability, and selectivity.

[0048] The aforementioned gas separation membrane is used to separate hydrogen and nitrogen, hydrogen and carbon monoxide, and hydrogen and methane to obtain hydrogen for hydrogen energy storage. The gas separation membrane has a hydrogen permeability greater than 100 barrers, a nitrogen permeability greater than 2.5 barrers, a carbon monoxide permeability greater than 2.0 barrers, and a methane permeability greater than 2.0 barrers.

[0049] An exemplary embodiment of this disclosure also provides a method for preparing a gas separation membrane, used to prepare the aforementioned gas separation membrane. Figure 2 A schematic flowchart illustrating a method for preparing a gas separation membrane according to exemplary embodiments of the present disclosure is shown, such as... Figure 2 As shown, the preparation method of this gas separation membrane includes:

[0050] Step 200: Under the first reaction conditions, triptene-2,3,6,7,14,15-hexacarboxylic trihydric acid is added to the mixture of the first organic solvent and the diamine monomer to obtain a spinning solution. It should be understood that the first reaction conditions here may include a reaction temperature of -80℃ to 10℃; for example, the reaction temperature may be -80℃, -70℃, or 10℃, etc., and is not limited to these. The protective gas for the reaction may be an inert gas; for example, the protective gas may be nitrogen, or other inert gases, etc.

[0051] The first organic solvent mentioned above may include one or more of N-methylpyrrolidone, dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, and N,N-dimethylformamide. It should be understood that this first organic solvent is the same as the organic solvent used in the preparation of polyimide resins; please refer to its relevant description, which will not be listed here again. The diamine monomer mentioned above may include one or more of 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, and 4,4'-diaminobiphenyl. It should be understood that this diamine monomer is the same as the diamine monomer used in the preparation of polyimide resins; please refer to its relevant description, which will not be listed here again. The mass ratio of the above-mentioned tripterene-2,3,6,7,14,15-hexacarboxylic trihydric anhydride to the diamine monomer is 1:(1-1.5). It should be understood that this mass ratio is the same as the mass ratio used in the preparation of polyimide resins; please refer to its relevant description, which will not be listed here again.

[0052] Step 210: Mix the second organic solvent and water to obtain the core solution. It should be understood that the second organic solvent may include one or more of methanol, ethanol, propanol, and acetone. For example, the second organic solvent may include methanol, ethanol, propanol, acetone, or a combination of methanol and ethanol, and is not limited thereto. The mass fraction of the second organic solvent in the core solution is 20%-80%, for example, it may be 20%, 50%, or 80%, and is not limited thereto. By minimizing the proportion of water in the core solution, the hydrolysis of the polyamic acid solution is reduced.

[0053] Step 220: Under the second reaction conditions, the spinning solution and core solution are mixed and extruded into a coagulation bath for spinning to obtain a pre-fabricated gas separation membrane. By mixing the core solution and the spinning solution, the skin layer inside the polyamic acid fiber undergoes a phase inversion, that is, it changes from a liquid phase to a solid phase, making the polyamic acid fiber hollow. The hollow fiber membrane continues to undergo solvent exchange in the coagulation bath to obtain the pre-fabricated gas separation membrane.

[0054] The second reaction conditions mentioned above include an extrusion speed of 100 ml / h - 300 ml / h for the spinning solution. For example, the extrusion speed of the spinning solution can be 100 ml / h, 200 ml / h, or 300 ml / h, etc., and is not limited to these. The extrusion speed ratio of the spinning solution to the core solution is 1:1 to 5:1. For example, the extrusion speed ratio of the spinning solution to the core solution can be 1:1, 2:1, or 5:1, etc., and is not limited to these. By adjusting the extrusion speed of the spinning solution and the core solution, the inner diameter of the polyamic acid hollow fiber can be adjusted. When the extrusion speed of the core solution is fast, the inner diameter of the polyamic acid hollow fiber is large, resulting in poor mechanical properties of the polyamic acid fiber membrane. When the extrusion speed of the core solution is too slow, its inner diameter is too small or even unable to form a hollow structure. Therefore, it is necessary to control the extrusion speed of the spinning solution and the core solution to meet the above requirements in order to obtain a polyamic acid fiber membrane with a suitable pore size.

[0055] The air gap height mentioned above is 5cm-20cm. For example, the air gap height can be 5cm, 15cm, or 20cm, etc., and is not limited to these. Since the solvent will partially evaporate in the air, making the polyamic acid surface skin more dense, when the air gap height is too large, the thickness of the polyamic acid surface skin is too thick, resulting in a decrease in the permeability of the prepared polyamic acid fiber membrane. Therefore, in order to improve the permeability of the polyamic acid membrane, the air gap height should meet the above requirements.

[0056] The take-up speed of the aforementioned spinning process is 100 m / h - 1000 m / h. For example, the take-up speed can be 100 m / h, 500 m / h, or 1000 m / h, and is not limited to these. Simultaneously, by controlling the take-up speed, the size of the fiber pores in the polyamic acid fiber membrane can be adjusted. The higher the take-up speed, the smaller the pore size. However, the take-up speed must meet the above requirements to avoid excessive traction on the membrane due to excessive take-up speed, which could lead to fiber breakage.

[0057] The temperature of the coagulation bath is 10℃-50℃, for example, it can be 10℃, 20℃, or 50℃, and is not limited to these. By controlling the temperature of the coagulation bath, the shape of the fiber pores inside the polyamic acid fiber membrane can be adjusted, preventing the formation of finger-like fiber pores due to excessively high temperatures and rapid exchange between the non-solvent and solvent in the coagulation bath, which would reduce the strength of the support layer and shorten its service life. The coagulation bath is a mixture of a second organic solvent and water, wherein the mass fraction of the second organic solvent in the coagulation bath is 5%-50%, to prevent the hollow fiber membrane from softening in water. For example, the mass fraction of the second organic solvent in the coagulation bath can be 5%, 25%, or 50%, etc.

[0058] Step 230: The pre-fabricated gas separation membrane is washed and dried to obtain a gas separation membrane. Residual organic solvents and water in the polyamic acid fiber membrane are removed by washing, and then the polyamic acid fiber membrane is prepared into a polyimide fiber membrane by thermal imidization treatment.

[0059] As one possible implementation method, Figure 3 A schematic flowchart of a method for obtaining spinning solution in step 200 according to an exemplary embodiment of the present disclosure is shown. Figure 3 As shown, under the first reaction conditions, adding tripterene-2,3,6,7,14,15-hexacarboxylic acid trihydric acid to a mixture of a first organic solvent and a diamine monomer to obtain a spinning solution may include:

[0060] Step 300: Under the first reaction conditions, triptene-2,3,6,7,14,15-hexacarboxylic trihydric acid is added to the mixture of the first organic solvent and the diamine monomer to obtain a polyamic acid solution. The mass fraction of polyamic acid in the polyamic acid solution is 10%-40%, for example, it can be 10%, 20%, or 40%, etc., and is not limited thereto. This is to ensure that when using the polyamic acid solution to prepare a polyimide gas separation membrane, the film-forming properties are good and it is easy to dissolve.

[0061] Step 310: Filter and defoam the polyamic acid solution to obtain the spinning solution.

[0062] For example, the polyamic acid solution can be filtered using a microporous membrane, which can be a polytetrafluoroethylene membrane with a pore size of 0.45 μm. The filtered solution can then be allowed to stand for 12-24 hours to allow visual observation of complete removal of small air bubbles, thus obtaining the spinning solution.

[0063] As one possible implementation method, Figure 4 A schematic flowchart of a method for obtaining a gas separation membrane in step 230 according to an exemplary embodiment of the present disclosure is shown. Figure 4 As shown, the above-mentioned prefabricated gas separation membrane is washed and dried to obtain a gas separation membrane, including:

[0064] Step 400: Immerse the pre-formed gas separation membrane in a second organic solvent for cleaning. This removes the organic solvent and water from the polyamic acid fiber membrane. It should be understood that the cleaning time here can be more than 1 hour to ensure that the organic solvent and water in the polyamic acid fiber membrane are completely removed.

[0065] For example, the second organic solvent can be an alcohol-based organic solvent, which can be a monohydric alcohol organic solvent, and the monohydric alcohol organic solvent can include one or more of methanol, ethanol, and propanol. For example, the monohydric alcohol organic solvent can include methanol, can include ethanol, can include propanol, and can also include methanol and ethanol, etc., and is not limited thereto.

[0066] Step 410: Immerse the prefabricated gas separation membrane, after cleaning with the second organic solvent, in a third organic solvent for further cleaning to obtain a cleaned prefabricated gas separation membrane. The third organic solvent can be a low-boiling-point organic solvent with good miscibility with the second organic solvent. After removing the second organic solvent from the polyamic acid fiber membrane, the third organic solvent can be removed through a subsequent drying process. It should be understood that the cleaning time here can be more than 1 hour to ensure that the second organic solvent in the polyamic acid fiber membrane is completely removed.

[0067] For example, the third organic solvent may include one or more of n-hexane, cyclohexane, isooctane, and methyl isopropanone. For instance, the third organic solvent may include n-hexane, may include cyclohexane, may include isooctane, may include methyl isopropanone, and may include n-hexane and cyclohexane, etc., and is not limited thereto.

[0068] Step 420: Under the third reaction conditions, the pre-prepared gas separation membrane after cleaning is dried and subjected to thermal imidization treatment to obtain a gas separation membrane. It should be understood that the third reaction conditions here may include a drying temperature of 50℃-80℃ to improve efficiency while preventing deformation of the limiting pores within the polyimide fiber membrane due to excessively high drying temperatures, which would degrade the mechanical properties of the polyimide fiber membrane. For example, the drying temperature can be 50℃, 70℃, 80℃, etc., and is not limited to this. The heating rate of thermal imidization can be 1℃ / min-5℃ / min to ensure a more uniform thermal imidization reaction of the polyamic acid. For example, the heating rate can be 1℃ / min, 2℃ / min, 5℃ / min, etc., and is not limited to this. The thermal imidization temperature can be 250℃-350℃ to ensure that the polyamic acid can completely react into polyimide. For example, the thermal imidization temperature can be 250℃, 300℃, 350℃, etc., and is not limited to this. The thermal imidization time can be 1 hour to 4 hours to ensure the thermal imidization reaction is complete. For example, the thermal imidization time can be 1 hour, 1.5 hours, or 4 hours, etc., and is not limited to these.

[0069] In some alternative methods, the process of drying and thermally imidizing the pre-prepared gas separation membrane under the third reaction conditions to obtain the gas separation membrane may include: drying the pre-prepared gas separation membrane under the third reaction conditions; then thermally imidizing the dried pre-prepared gas separation membrane using a stepped heating method to obtain the gas separation membrane. By using a stepped heating method, the temperature can be rapidly increased to the reaction temperature in the first step, and the heating rate can be reduced when the reaction temperature is reached to prolong the reaction time, resulting in a more uniform and complete reaction.

[0070] The present disclosure is further illustrated below by way of embodiments, but these embodiments are not intended to limit the scope of the present disclosure. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected in accordance with the product instructions.

[0071] Example 1

[0072] This embodiment is used to prepare polyimide resin. The diamine monomer selected is 4,4'-diaminodiphenyl ether, the organic solvent selected is N,N-dimethylformamide, the reaction temperature is -20℃, the inert gas selected is nitrogen, the mass ratio of triptene-2,3,6,7,14,15-hexacarboxylic trianic anhydride to diamine monomer is 1:1, the catalyst selected is pyridine, and the dehydrating agent selected is acetic anhydride.

[0073] Step 1: Preparation of polyamic acid solution

[0074] The dried flask was evacuated and purged with nitrogen. 4,4'-diaminodiphenyl ether (4 mmol) was added to the flask, followed by 10 mL of dried N,N-dimethylformamide. The mixture was stirred until homogeneous. Tripteroene-2,3,6,7,14,15-hexacarboxylic acid trihydric acid (4 mmol) was slowly and uniformly added at -20°C, and stirred until homogeneous, thus preparing a polyamic acid solution. The mass fraction of polyamic acid in this solution was 21.9%.

[0075] Step 2: Preparation of polyimide resin

[0076] Add 1 mL of pyridine and 1 mL of acetic anhydride, stir under nitrogen at room temperature for 10 min, heat to 100 °C and stir for 3 h to complete chemical imidization, cool to room temperature, pour in 200 mL of methanol to obtain polyimide precipitate, wash with methanol three times and filter, and then vacuum dry in an oven at 160 °C to obtain polyimide resin. The solubility of the polyimide resin prepared in this example is shown in Table 1.

[0077] Example 2

[0078] This embodiment is used to prepare polyimide resin. The diamine monomer selected is 2,2-bis(4-aminophenyl)hexafluoropropane, the organic solvent selected is dimethylacetamide, the reaction temperature is -80℃, the inert gas selected is nitrogen, the mass ratio of triterpenoid-2,3,6,7,14,15-hexacarboxylic acid trianic anhydride to diamine monomer is 1:1.2, the catalyst selected is pyridine, and the dehydrating agent selected is acetic anhydride.

[0079] Step 1: Preparation of polyamic acid solution

[0080] The dried flask was evacuated and purged with nitrogen. 2,2-bis(4-aminophenyl)hexafluoropropane (3.6 mmol) was added, followed by 10 mL of dried dimethylacetamide. The mixture was stirred until homogeneous. Tripteroene-2,3,6,7,14,15-hexacarboxylic acid trianic acid (3 mmol) was slowly and uniformly added at -80°C, and stirred until homogeneous, thus preparing a polyamic acid solution. The mass fraction of polyamic acid in this solution was 21.5%.

[0081] Step 2: Preparation of polyimide resin

[0082] Add 1 mL of pyridine and 1 mL of acetic anhydride, stir under nitrogen at room temperature for 10 min, heat to 120 °C and stir for 3.5 h to complete chemical imidization, cool to room temperature, pour into 200 mL of methanol to obtain polyimide precipitate, wash with methanol three times and filter, and then vacuum dry in an oven at 150 °C to obtain polyimide resin. The solubility of the polyimide resin prepared in this example is shown in Table 1.

[0083] Example 3

[0084] This embodiment is used to prepare polyimide resin. The diamine monomer selected is 4,4'-diaminobiphenyl, the organic solvent selected is tetrahydrofuran, the reaction temperature is 10°C, the inert gas selected is nitrogen, the mass ratio of triptene-2,3,6,7,14,15-hexacarboxylic acid trianic anhydride to diamine monomer is 1:1.5, the catalyst selected is isoquinoline, and the dehydrating agent selected is acetic anhydride.

[0085] Step 1: Preparation of polyamic acid solution

[0086] The dried flask was evacuated and purged with nitrogen. 4,4'-diaminobiphenyl (6 mmol) was added to the flask, followed by 10 mL of dried dimethylacetamide. The mixture was stirred thoroughly. Tripteroene-2,3,6,7,14,15-hexacarboxylic acid trianic acid (4 mmol) was slowly and uniformly added at -80°C, and stirred until homogeneous, thus preparing a polyamic acid solution. The mass fraction of polyamic acid in this solution was 23.8%.

[0087] Step 2: Preparation of polyimide resin

[0088] Add 1 mL of isoquinoline and 1 mL of acetic anhydride, stir under nitrogen at room temperature for 10 min, heat to 80 °C and stir for 4 h to complete chemical imidization, cool to room temperature, pour into 200 mL of methanol to obtain polyimide precipitate, wash with methanol three times and filter, and then vacuum dry in an oven at 200 °C to obtain polyimide resin. The solubility of the polyimide resin prepared in this example is shown in Table 1.

[0089] Comparative Example 1

[0090] This comparative example is used to prepare polyimide resin.

[0091] Step 1: Prepare polyamic acid solution.

[0092] The dried flask was evacuated and purged with nitrogen. 4,4'-diaminobiphenyl (4 mmol) was added to the flask, followed by 10 mL of dried dimethylacetamide. The mixture was stirred until homogeneous. 2,3,6,7-tetracarboxylic acid triptene dianhydride (4 mmol) was slowly and uniformly added at a low temperature of -50°C. The mixture was stirred until homogeneous to prepare a polyamic acid solution.

[0093] Step 2: Prepare polyimide resin.

[0094] Add 1 mL of pyridine and 1 mL of acetic anhydride, stir at room temperature for 30 min, heat to 100 °C and stir for 3 h to complete chemical imidization, cool to room temperature, pour in 200 mL of methanol to obtain polyimide precipitate, wash with methanol three times and filter, dry under vacuum at 160 °C to obtain polyimide resin. The solubility of the polyimide resin prepared in this comparative example is shown in Table 1.

[0095] Comparative Example 2

[0096] This comparative example is used to prepare polyimide resin.

[0097] Step 1: Prepare polyamic acid solution.

[0098] The dried flask was evacuated and purged with nitrogen. 4,4'-diaminobiphenyl (4 mmol) was added to the flask, followed by 10 mL of dried dimethylacetamide. The mixture was stirred until homogeneous. 4,4'-(hexafluoroisopropene)phthalic anhydride (4 mmol) was slowly and uniformly added at a low temperature of -50°C and stirred until homogeneous to prepare a polyamic acid solution.

[0099] Step 2: Prepare polyimide resin.

[0100] Add 1 mL of pyridine and 1 mL of acetic anhydride, stir at room temperature for 30 min, heat to 100 °C and stir for 3 h to complete chemical imidization, cool to room temperature, pour in 200 mL of methanol to obtain polyimide precipitate, wash with methanol three times and filter, dry under vacuum at 160 °C to obtain polyimide resin. The solubility of the polyimide resin prepared in this comparative example is shown in Table 1.

[0101] Table 1: Solubility Test Table for Polyimide Resins

[0102]

[0103] "+" indicates that it is soluble at room temperature, and "-" indicates that it is not soluble at room temperature.

[0104] As shown in Table 1, the polyimide resins prepared in Examples 1-3 are insoluble in several organic solvents, including N-methylpyrrolidone, dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, and N,N-dimethylformamide. In contrast, the polyimide resins prepared by reacting dianhydride and diamine monomers with a tripterene structure in Comparative Example 1 and in Comparative Example 2 are soluble in the same organic solvents. Therefore, the polyimide resins prepared by the exemplary embodiments of this disclosure have good solvent resistance.

[0105] Example 4

[0106] This embodiment is used to prepare a polyimide gas separation membrane. The selected diamine monomer is 4,4'-diaminodiphenyl ether, the selected organic solvent is N,N-dimethylformamide, the reaction temperature is -20°C, the selected inert gas is nitrogen, the mass ratio of trimerene-2,3,6,7,14,15-hexacarboxylic acid tricornis to the diamine monomer is 1:1, the selected catalyst is pyridine, the selected dehydrating agent is acetic anhydride, the selected second organic solvent is isopropanol, and the selected coagulation bath is a mixture of isopropanol and water, with isopropanol having a mass fraction of 5%. The selected second organic solvent for cleaning is isopropanol, and the third organic solvent is isooctane.

[0107] Step 1: Preparation of polyamic acid solution

[0108] The dried flask was evacuated and purged with nitrogen. 0.4 mol of 4,4'-diaminodiphenyl ether was added, followed by 1 L of dried N,N-dimethylformamide, and the mixture was stirred until homogeneous. Tripteroene-2,3,6,7,14,15-hexacarboxylic acid trihydric acid (0.4 mol) was slowly and uniformly added at -20°C, and the mixture was stirred until homogeneous, thus preparing a polyamic acid solution. The mass fraction of polyamic acid in this solution was 21.9%.

[0109] Step 2: Preparation of spinning solution

[0110] The polyamic acid solution was filtered using a 0.45 μm polytetrafluoroethylene membrane, and the filtrate was defoamed until all small bubbles were removed to obtain the spinning solution.

[0111] Step 3: Preparation of core fluid

[0112] Isopropanol and deionized water were mixed, and the mixture was defoamed until all small bubbles were removed to obtain the core solution. The second organic solvent had a mass fraction of 50% in the core solution.

[0113] Step 4: Preparation of pre-fabricated gas separation membrane

[0114] The extrusion speed of the spinning solution was adjusted to 150 ml / h, and the extrusion speed of the core solution was adjusted to 50 ml / h. The air gap height was 5 cm, and the winding speed was 200 m / h. The core solution and spinning solution were mixed and extruded into a coagulation bath at a temperature of 20°C. The fibers were then wound up using a winding assembly to obtain a pre-fabricated gas separation membrane (i.e., a polyamic acid fiber membrane).

[0115] Step 5: Preparation of gas separation membrane

[0116] The pre-prepared gas separation membrane was immersed in isopropanol for 1 hour, and then immersed in isooctane for 1 hour. It was then heated at 80°C in a vacuum oven for a period of time until the pre-prepared gas separation membrane was completely dried and its quality no longer changed. The temperature was then increased to 200°C in a tube furnace at a rate of 4°C / min, and subsequently increased to 300°C at a rate of 2°C / min for 4 hours to obtain the gas separation membrane. The performance of the polyimide gas separation membrane prepared in this embodiment is shown in Table 2.

[0117] Example 5

[0118] This embodiment is used to prepare a polyimide gas separation membrane. The selected diamine monomer is 2,2-bis(4-aminophenyl)hexafluoropropane, the selected organic solvent is dimethylacetamide, the reaction temperature is -80℃, the selected inert gas is nitrogen, the mass ratio of trimerene-2,3,6,7,14,15-hexacarboxylic acid tricornis to the diamine monomer is 1:1.2, the selected catalyst is pyridine, the selected dehydrating agent is acetic anhydride, the selected second organic solvent is methanol, and the selected coagulation bath is a mixture of methanol and water, with methanol comprising 25% by mass. The second organic solvent used for cleaning is methanol, and the third organic solvent is n-hexane.

[0119] Step 1: Preparation of polyamic acid solution

[0120] The dried flask was evacuated and purged with nitrogen. 0.36 mol of 2,2-bis(4-aminophenyl)hexafluoropropane was added, followed by 1 L of dried dimethylacetamide. The mixture was stirred until homogeneous. Then, 0.3 mol of triptene-2,3,6,7,14,15-hexacarboxylic acid trihydric acid was slowly and uniformly added at -80°C, and the mixture was stirred until homogeneous, thus preparing a polyamic acid solution. The mass fraction of polyamic acid in this solution was 21.5%.

[0121] Step 2: Preparation of spinning solution

[0122] The polyamic acid solution was filtered using a 0.45 μm polytetrafluoroethylene membrane, and the filtrate was defoamed until all small bubbles were removed to obtain the spinning solution.

[0123] Step 3: Preparation of core fluid

[0124] Methanol and deionized water were mixed, and the mixture was defoamed until all small bubbles were removed to obtain the core solution. The second organic solvent had a mass fraction of 20% in the core solution.

[0125] Step 4: Preparation of pre-fabricated gas separation membrane

[0126] The extrusion speed of the spinning solution and the core solution were both adjusted to 100 ml / h. The air gap height was 10 cm and the winding speed was 100 m / h. The core solution and spinning solution were mixed and extruded into a coagulation bath at 10°C. The fibers were then wound up using a winding assembly to obtain a pre-fabricated gas separation membrane (i.e., a polyamic acid fiber membrane).

[0127] Step 5: Preparation of gas separation membrane

[0128] The pre-prepared gas separation membrane was soaked in methanol for 1 hour, and then soaked in n-hexane for 1 hour. It was then heated at 50°C in a vacuum oven for a period of time until the pre-prepared gas separation membrane was completely dried and its quality no longer changed. The temperature was then increased to 200°C in a tube furnace at a rate of 5°C / min, and then increased to 250°C at a rate of 1°C / min for thermal imidization for 1 hour to obtain the gas separation membrane. The performance of the polyimide gas separation membrane prepared in this embodiment is shown in Table 2.

[0129] Example 6

[0130] This embodiment is used to prepare a polyimide gas separation membrane. The selected diamine monomer is 4,4'-diaminobiphenyl, the selected organic solvent is tetrahydrofuran, the reaction temperature is 10°C, the selected inert gas is nitrogen, the mass ratio of trimerene-2,3,6,7,14,15-hexacarboxylic acid tricornis to the diamine monomer is 1:1.5, the selected catalyst is isoquinoline, the selected dehydrating agent is acetic anhydride, the selected second organic solvent is ethanol, and the selected coagulation bath is a mixture of ethanol and water, with ethanol comprising 50% by mass. The second organic solvent used for cleaning is ethanol, and the third organic solvent is cyclohexane.

[0131] Step 1: Preparation of polyamic acid solution

[0132] The dried flask was evacuated and purged with nitrogen. 0.6 mol of 4,4'-diaminobiphenyl was added, followed by 1 L of dried dimethylacetamide, and the mixture was stirred until homogeneous. Then, 0.4 mol of triptene-2,3,6,7,14,15-hexacarboxylic acid tricornis was slowly and uniformly added at -80°C, and the mixture was stirred until homogeneous, thus preparing a polyamic acid solution. The mass fraction of polyamic acid in this solution was 23.8%.

[0133] Step 2: Preparation of spinning solution

[0134] The polyamic acid solution was filtered using a 0.45 μm polytetrafluoroethylene membrane, and the filtrate was defoamed until all small bubbles were removed to obtain the spinning solution.

[0135] Step 3: Preparation of core fluid

[0136] Ethanol and deionized water were mixed, and the mixture was defoamed until all small bubbles were removed to obtain the core solution. The mass fraction of ethanol in the core solution was 80%.

[0137] Step 4: Preparation of pre-fabricated gas separation membrane

[0138] The extrusion speed of the spinning solution was adjusted to 300 ml / h, and the extrusion speed of the core solution was adjusted to 60 ml / h. The air gap height was 20 cm, and the winding speed was 1000 m / h. The core solution and spinning solution were mixed and extruded into a coagulation bath at a temperature of 50°C. The fibers were then wound up using a winding assembly to obtain a pre-fabricated gas separation membrane (i.e., a polyamic acid fiber membrane).

[0139] Step 5: Preparation of gas separation membrane

[0140] The pre-prepared gas separation membrane was soaked in ethanol for 1 hour, and then soaked in cyclohexane for 1 hour. It was then heated at 70°C in a vacuum oven for a period of time until the pre-prepared gas separation membrane was completely dried and its quality no longer changed. The temperature was then increased to 200°C in a tube furnace at a rate of 5°C / min, and then increased to 350°C at a rate of 3°C / min for thermal imidization for 3.5 hours to obtain the gas separation membrane. The performance of the polyimide gas separation membrane prepared in this embodiment is shown in Table 2.

[0141] Comparative Example 3

[0142] This comparative example is used to prepare a polyimide gas separation membrane. The second organic solvent used is isopropanol, and the coagulation bath is a mixture of isopropanol and water, with isopropanol comprising 5% by mass. The second organic solvent used for cleaning is isopropanol, and the third organic solvent is isooctane.

[0143] Step 1: Preparation of spinning solution

[0144] The polyimide resin prepared in Comparative Example 1 was dissolved in N-methylpyrrolidone to prepare a polyimide resin N-methylpyrrolidone solution with a mass fraction of 20%. The solution was then filtered through a 0.45 μm polytetrafluoroethylene membrane and defoamed until small bubbles were completely removed to obtain the spinning solution.

[0145] Step 2: Preparation of core fluid

[0146] Isopropanol and deionized water were mixed, and the mixture was defoamed until all small bubbles were removed to obtain the core solution. The second organic solvent had a mass fraction of 50% in the core solution.

[0147] Step 3: Preparation of pre-fabricated gas separation membrane

[0148] The extrusion speed of the spinning solution was adjusted to 150 ml / h, and the extrusion speed of the core solution was adjusted to 50 ml / h. The air gap height was 5 cm, and the winding speed was 200 m / h. The core solution and spinning solution were mixed and extruded into a coagulation bath at a temperature of 20°C. The fibers were then wound up using a winding assembly to obtain a pre-fabricated gas separation membrane.

[0149] Step 4: Preparation of gas separation membrane

[0150] The pre-prepared gas separation membrane was immersed in isopropanol for 1 hour, and then immersed in isooctane for 1 hour. It was then heated in a vacuum oven at 200°C for a period of time until the pre-prepared gas separation membrane was completely dried and its mass no longer changed, thus obtaining the gas separation membrane. The performance of the polyimide gas separation membrane prepared in this embodiment is shown in Table 2.

[0151] Comparative Example 4

[0152] This comparative example is used to prepare a polyimide gas separation membrane. The second organic solvent used is isopropanol, and the coagulation bath is a mixture of isopropanol and water, with isopropanol comprising 5% by mass. The second organic solvent used for cleaning is isopropanol, and the third organic solvent is isooctane.

[0153] Step 1: Preparation of spinning solution

[0154] The polyimide resin prepared in Comparative Example 2 was dissolved in N-methylpyrrolidone to prepare a 20% N-methylpyrrolidone solution of polyimide resin. The solution was then filtered through a 0.45 μm polytetrafluoroethylene membrane and defoamed until small bubbles were completely removed to obtain the spinning solution.

[0155] Step 2: Preparation of core fluid

[0156] Isopropanol and deionized water were mixed, and the mixture was defoamed until all small bubbles were removed to obtain the core solution. The second organic solvent had a mass fraction of 50% in the core solution.

[0157] Step 3: Preparation of pre-fabricated gas separation membrane

[0158] The extrusion speed of the spinning solution was adjusted to 150 ml / h, and the extrusion speed of the core solution was adjusted to 50 ml / h. The air gap height was 5 cm, and the winding speed was 200 m / h. The core solution and spinning solution were mixed and extruded into a coagulation bath at a temperature of 20°C. The fibers were then wound up using a winding assembly to obtain a pre-fabricated gas separation membrane.

[0159] Step 4: Preparation of gas separation membrane

[0160] The pre-prepared gas separation membrane was immersed in isopropanol for 1 hour, and then immersed in isooctane for 1 hour. It was then heated at 100°C in a vacuum oven for a period of time until the pre-prepared gas separation membrane was completely dried and its mass no longer changed, thus obtaining the gas separation membrane. The performance of the polyimide gas separation membrane prepared in this embodiment is shown in Table 2.

[0161] The gas separation performance of polyimide gas separation membranes can be tested using the constant pressure variable volume method. Specifically, the permeability coefficients P of H2, N2, CO, and CH4 can be tested using polyimide gas separation membranes at a working pressure of 300.15 K and 0.2 MPa. The test results are shown in Table 2.

[0162] The selectivity α of the polyimide gas separation membrane can be determined by calculation using the formula: α i / j =P i / P j , where P i P j Table 2 shows the test results for the selectivity α of the polyimide gas separation membrane, where i and j are the permeation coefficients of gases i and j, respectively.

[0163] Table 2 Gas permeability coefficient and selectivity

[0164]

[0165] As shown in Table 2, in all exemplary embodiments 4-6 of this disclosure, a polyimide gas separation membrane was prepared by reacting triterpenoid-2,3,6,7,14,15-hexacarboxylic tricornis as a tricornis monomer with diamine monomers of 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, and 4,4'-diaminobiphenyl. The polyimide gas separation membrane has a three-dimensional network structure, and its permeability coefficient P for H2, N2, CO, and CH4 is higher than that of Comparative Example 3 and Comparative Example 4, and its selectivity is also higher than that of Comparative Example 3 and Comparative Example 4.

[0166] Specifically, in Comparative Example 3, a polyimide gas separation membrane was prepared by reacting 2,3,6,7-tetracarboxylic acid tripterene dianhydride monomer with 4,4'-diaminobiphenyl. Due to the presence of the tripterene structure, the free volume of the polyimide can be increased. However, unlike Example 6, the polyimide gas separation membrane prepared in Comparative Example 3 is a linear polyimide gas separation membrane, while the polyimide gas separation membrane prepared in Example 6 is a three-dimensional network structure polyimide gas separation membrane. Compared with the linear polyimide gas separation membrane, the molecular chain spacing of the three-dimensional network structure polyimide gas separation membrane is more fixed and the molecular chain mobility is worse. Therefore, the polyimide gas separation membrane prepared in Example 6 has better anti-aging and anti-plasticization properties. Combined with the data in Table 2, it can be determined that the polyimide gas separation membrane prepared in Example 6 has better permeability and selectivity.

[0167] Comparative Example 4 uses 4,4'-(hexafluoroisopropene) diaphthalic anhydride and 4,4'-diaminobiphenyl to prepare a polyimide gas separation membrane. Unlike Example 6, the diaphthalic anhydride in Comparative Example 4 does not have a triterpenene structure and is a linear polyimide. Therefore, the polyimide gas separation membrane prepared by the method in Example 6 has better anti-aging and anti-plasticization properties. Combined with the data in Table 2, it can be determined that the polyimide gas separation membrane prepared in Example 6 has better permeability.

[0168] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0169] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A polyimide resin, characterized by, A structural formula of the polyimide resin is: wherein n is a natural number greater than 1 and R1is an aromatic diamine residue; The polyimide resin contains a triptycene-2,3,6,7,14,15-hexacarboxylic acid trianhydride structure in a molecular chain thereof; The R1 is selected from any one of the following groups: 、 、 、 、 、 、 、 、 。 2. A gas separation membrane characterized by, The gas separation membrane is composed of the polyimide resin according to claim 1.

3. The gas separation membrane of claim 2, wherein, The gas separation membrane is used for separating hydrogen and nitrogen, hydrogen and carbon monoxide, and hydrogen and methane; and / or, The hydrogen permeability of the gas separation membrane is greater than 100 barrers, the nitrogen permeability is greater than 2.5 barrers, the carbon monoxide permeability is greater than 2.0 barrers, and the methane permeability is greater than 2.0 barrers.

4. A method of making a gas separation membrane, characterized by, The method for preparing the gas separation membrane according to any one of claims 2-3, the method comprising: under first reaction conditions, adding triptycene-2,3,6,7,14,15-hexacarboxylic acid trianhydride to a mixed solution of a first organic solvent and a diamine monomer to obtain a spinning solution; mixing a second organic solvent and water to obtain a core liquid; under second reaction conditions, mixing the spinning solution and the core liquid and extruding into a coagulation bath for spinning to obtain a pre-prepared gas separation membrane; washing and drying the pre-prepared gas separation membrane to obtain a gas separation membrane.

5. The method of claim 4, wherein the membrane is a gas separation membrane. The first reaction conditions include: the reaction temperature is -80℃-10℃, and the reaction protective gas is an inert gas; and / or, The first organic solvent includes one or more of N-methylpyrrolidone, dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide and N,N-dimethylformamide; and / or, The diamine monomer includes one or more of 4,4'-oxydianiline, 2,2-bis(4-aminophenyl)hexafluoropropane and 4,4'-diaminobiphenyl; and / or, The mass ratio of the triptycene-2,3,6,7,14,15-hexacarboxylic acid trianhydride and the diamine monomer is 1:(1-1.5); and / or, The second organic solvent includes one or more of methanol, ethanol, propanol and acetone; and / or, The mass fraction of the second organic solvent in the core liquid is 20%-80%; and / or, The second reaction conditions include: the extrusion speed of the spinning solution is 100ml / h-300ml / h, the extrusion speed ratio of the spinning solution and the core liquid is 1:1-5:1, the air gap height is 5cm-20cm, and the spinning take-up speed is 100m / h-1000m / h; and / or, The temperature of the coagulation bath is 10℃-50℃, and the coagulation bath is a mixed solution of a second organic solvent and water, wherein the mass fraction of the second organic solvent in the coagulation bath is 5%-50%.

6. The method of claim 4, wherein the membrane is a gas separation membrane. The method for preparing the gas separation membrane according to any one of claims 2-3, the method comprising: under first reaction conditions, adding triptycene-2,3,6,7,14,15-hexacarboxylic acid trianhydride to a mixed solution of a first organic solvent and a diamine monomer to obtain a spinning solution; mixing a second organic solvent and water to obtain a core liquid; under second reaction conditions, mixing the spinning solution and the core liquid and extruding into a coagulation bath for spinning to obtain a pre-prepared gas separation membrane; washing and drying the pre-prepared gas separation membrane to obtain a gas separation membrane. The first reaction conditions include: the reaction temperature is -80℃-10℃, and the reaction protective gas is an inert gas; and / or, The first organic solvent includes one or more of N-methylpyrrolidone, dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide and N,N-dimethylformamide; and / or, The diamine monomer includes one or more of 4,4'-oxydianiline, 2,2-bis(4-aminophenyl)hexafluoropropane and 4,4'-diaminobiphenyl; and / or, The mass ratio of the triptycene-2,3,6,7,14,15-hexacarboxylic acid trianhydride and the diamine monomer is 1:(1-1.5); and / or, The second organic solvent includes one or more of methanol, ethanol, propanol and acetone; and / or, The mass fraction of the second organic solvent in the core liquid is 20%-80%; and / or, The second reaction conditions include: the extrusion speed of the spinning solution is 100ml / h-300ml / h, the extrusion speed ratio of the spinning solution and the core liquid is 1:1-5:1, the air gap height is 5cm-20cm, and the spinning take-up speed is 100m / h-1000m / h; and / or, The temperature of the coagulation bath is 10℃-50℃, and the coagulation bath is a mixed solution of a second organic solvent and water, wherein the mass fraction of the second organic solvent in the coagulation bath is 5%-50%. The method for preparing the gas separation membrane according to any one of claims 2-3, the method comprising: under first reaction conditions, adding triptycene-2,3,6,7,14,15-hexacarboxylic acid trianhydride to a mixed solution of a first organic solvent and a diamine monomer to obtain a spinning solution; The polyamide acid solution is filtered and defoamed to obtain a spinning solution.

7. The method of claim 4, wherein the membrane is a gas separation membrane. The pre-prepared gas separation membrane is washed and dried to obtain a gas separation membrane, including: The pre-prepared gas separation membrane is immersed in a second organic solvent for cleaning; The pre-prepared gas separation membrane cleaned with the second organic solvent is immersed in a third organic solvent for cleaning to obtain a cleaned pre-prepared gas separation membrane; The cleaned pre-prepared gas separation membrane is dried and thermally imidized under a third reaction condition to obtain a gas separation membrane.

8. The method of claim 7, wherein the membrane is a gas separation membrane. The cleaned pre-prepared gas separation membrane is dried and thermally imidized under a third reaction condition to obtain a gas separation membrane, including: The cleaned pre-prepared gas separation membrane is dried under a third reaction condition; The pre-prepared gas separation membrane after drying is thermally imidized using a stepwise heating method to obtain the gas separation membrane.

9. The method of claim 7, wherein the membrane is a gas separation membrane. The second organic solvent is an alcohol organic solvent, the alcohol organic solvent is a monohydric alcohol organic solvent, and the monohydric alcohol organic solvent includes one or more of methanol, ethanol, and propanol; and / or, The third organic solvent includes one or more of n-hexane, cyclohexane, isooctane, and methyl isopropyl ketone; and / or, The third reaction condition includes that the drying temperature is 50-80°C, and the heating rate of thermal imidization is 1-5°C / min.

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