Polyimide support for water electrolysis

Abstract

The present invention relates to a polyimide support for water electrolysis having an elongation of 15% or more, which can be used even at a temperature of 90°C or higher and can withstand swelling of an ionomer by 20% or more during operation. The polyimide support is formed by heat-treating polyamic acid, wherein the polyimide support has a stress-strain curve composed of three sections including initial, intermediate, and final sections, and the average slope of the initial section is greater than the average slope of the intermediate section and the average slope of the final section.

Description

Polyimide support for water electrolysis

[0001] Cross-reference regarding related applications

[0002] The present application claims the benefit of priority to Korean Patent Application No. 2024-0187000 filed on December 16, 2024, Korean Patent Application No. 2025-0057506 filed on April 30, 2025, and Korean Patent Application No. 2025-0057507 filed on April 30, 2025, the contents of said patent applications are incorporated by reference into this specification.

[0003] The present invention relates to a polyimide support for water electrolysis, and more specifically, to a polyimide support capable of high-temperature operation.

[0004] Supports for water electrolysis manufactured using hydrocarbons can be used at temperatures above 90°C, which increases hydrogen energy efficiency and can lower production costs. In order to increase the durability of the ionomer used in this process, a composite membrane is essential.

[0005] With current technology, there is a problem where the durability of the ionomer decreases in water during hydrogen energy generation, making it impossible to use PEM components for a long period. Therefore, there is a need for a material that can withstand organic solvents when a support is immersed after dissolving a hydrocarbon-based ionomer in an organic solvent. To solve this problem, materials such as PI (polyimide), PPS (Polyphenylene sulfide), LCP (Liquid Crystal Polymer), and PBO (Poly-p-phenylenebenzpbisoxazole) can be used. However, polyimide (PI) is the only material that satisfies the physical properties required to withstand the water electrolysis atmosphere and the difficulty in manufacturing nano nonwoven fabrics through electrospinning.

[0006] Accordingly, although much effort has been made to use conventional polyimide as a support, there are many difficulties in manufacturing a polyimide support having an elongation of 15% or more to withstand swelling of more than 20% of the ionomer during operation.

[0007] The problem that the present invention aims to solve is to provide a polyimide support for water electrolysis having an elongation of 15% or more that can be used at a temperature of 90°C or higher and can withstand swelling of 20% or more of the ionomer during operation.

[0008] The present invention relates to a polyimide support formed by heat-treating polyamic acid, wherein the polyimide support has a stress-strain curve composed of three sections: an initial section, an intermediate section, and a final section, and the average slope of the initial section is greater than the average slope of the intermediate section and the average slope of the final section.

[0009] In the present invention, the ratio of the average slope of the intermediate section to the average slope of the final section of the polyimide support may be 1:1 to 3.

[0010] In the present invention, the ratio of the average slope of the initial section to the average slope of the intermediate section of the polyimide support may be 1:0.1 to 0.9.

[0011] In the present invention, the polyamic acid may be a polymer of BPDA (3,3',4,4'-Biphenyltetracarboxylic dianhydride) and BAPP (2,2-bis[4-(4-aminophenoxy)phenyl]propane) or BPDA and 6F-BAPP (2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane).

[0012] In the present invention, the heat treatment may be performed at 250 to 410°C for 10 to 200 minutes.

[0013] In the present invention, the polyimide support may have a modulus in the TD direction of 30 to 300 MPa measured by the following measurement method and an elongation of 15 to 50%.

[0014] [measurement method]

[0015] Shin Yul: ASTD D 882

[0016] Modulus: Calculated using the following mathematical formula 1 E=σ / ε

[0017] In the above mathematical formula 1, σ is stress (force per unit area, MPa) and ε is strain (strain per unit length)

[0018] In the present invention, the polyimide support may have a porosity of 50% or more and a pore size of 0.1 to 5 μm.

[0019] In the present invention, the polyimide support may have a solvent resistance of 95% or more as measured by the following measurement method.

[0020] [measurement method]

[0021] Solvent resistance: A polyimide support (10 x 10 cm) is immersed in a solvent for 5 minutes and dried at 60°C for 12 hours, and the weight is measured by comparing the weight before and after. The solvent is DMAC (N,N-dimethylacetamide), DMF (N,N-dimethyl formamide), or NMP (N-methyl-2-pyrrolidone).

[0022] In the present invention, the polyimide support may be for water electrolysis.

[0023] The polyimide support of the present invention can be used at temperatures of 90°C or higher and can have an elongation of 15% or more to withstand swelling of 20% or more of the ionomer during operation.

[0024] In addition, the polyimide support of the present invention has a stress-strain curve different from that of conventional polyimide when the polyamic acid with specified components is heated at a specific temperature, and accordingly, can have a higher elongation than conventional polyimide.

[0025] Figure 1 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with BPDA and 6F-BAPP of the present invention.

[0026] Figure 2 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with BPDA and BAPP of the present invention.

[0027] Figure 3 shows the stress-strain curve of a polyimide formed from polyamic acid polymerized with PMDA and ODA of the comparative example.

[0028] Figure 4 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with BPDA and ODA of the comparative example.

[0029] Figure 5 shows the stress-strain curve of a polyimide formed from polyamic acid polymerized with OPDA and ODA of the comparative example.

[0030] FIG. 6 is a scanning electron microscope (X5,000) image of the surface of the polyimide support of Example 1, Example 2 and Comparative Example 4.

[0031] Hereinafter, the present invention will be described in more detail with reference to exemplary embodiments and examples so that those skilled in the art can easily implement it. However, the present invention may be embodied in various different forms and is not limited only to the embodiments and examples described herein.

[0032] As used herein, the terms “comprise,” “comprising,” “formed,” “has,” “having,” or any other variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, article, or apparatus comprising a list of elements is not necessarily limited to such elements alone and may include other elements not explicitly listed or inherent to such process, method, article, or apparatus. Furthermore, unless explicitly stated otherwise, “or” means an inclusive “or” and not an exclusive “or.”

[0033] All examples or the use of exemplary terms are merely for the purpose of describing technical ideas in detail, and unless limited by the claims, the scope is not limited by such examples or exemplary terms.

[0034]

[0035] Figure 1 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with BPDA and 6F-BAPP of the present invention, and Figure 2 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with BPDA and BAPP of the present invention.

[0036] Referring to FIGS. 1 and 2, the present invention is a polyimide support formed by heat-treating polyamic acid, wherein the polyimide support has a stress-strain curve composed of three sections: an initial section, an intermediate section, and a final section, and the average slope of the initial section is greater than the average slope of the intermediate section and the average slope of the final section.

[0037] In Figures 1 and 2, the initial section refers to the section where the strain (%) is 0% or more and 5% or less, the intermediate section refers to the section where the strain is greater than 5% and 20% or less, and the final section refers to the section where the strain is greater than 20% and up to the strain (%) of the part where the stress is measured to be highest.

[0038] In addition, in the present invention, elongation refers to the strain at which the material breaks (Elongation at Break) in the stress-strain curve, and this represents the maximum deformation capacity of the material.

[0039] In the present invention, the stress-strain curve can be obtained according to ASTM D 882 using a tensile testing machine (Instron 5566).

[0040] Specifically, the sample is cut to a width of 25 mm and a length of 200 mm, and the distance between grips is set to 100 mm. After setting, the final material properties are checked by tensile testing at a speed of 50 mm / min.

[0041] The ratio of the average slope of the intermediate section to the average slope of the final section of the polyimide support may be 1:1 to 3, and preferably 1:1.5 to 2.5. If the ratio of the average slope of the intermediate section to the average slope of the final section falls outside the above range, the elongation of the polyimide support measured according to ASTD D 882 may be less than 15%, so the above range is preferred.

[0042] In addition, the ratio of the average slope of the initial section to the average slope of the intermediate section of the polyimide support may be 1:0.1 to 0.9, and preferably 1:0.1 to 0.5. If the ratio of the average slope of the initial section to the average slope of the intermediate section falls outside the above range, the elongation of the polyimide support measured according to ASTD D 882 may be less than 15%, so the above range is preferred.

[0043] In addition, the polyimide support may have a strain of 0.1 to 1% at a stress of 1 MPa, a strain of 0.5 to 3% at a stress of 2 MPa, and a strain of 1 to 10% at a stress of 3 MPa in the stress-strain curve.

[0044] Preferably, when the polyimide support is a polyimide formed from a polyamic acid polymerized from BPDA and BAPP, in the stress-strain curve, it may have a strain of 0.1 to 0.5% at a stress of 1 MPa, a strain of 0.5 to 1% at a stress of 2 MPa, and a strain of 1 to 2% at a stress of 3 MPa.

[0045] Preferably, when the polyimide support is a polyimide formed from a polyamic acid polymerized from BPDA and 6F-BAPP, in the stress-strain curve, it may have a strain of 0.5 to 1% at a stress of 1 MPa, a strain of 2 to 3% at a stress of 2 MPa, and a strain of 5 to 10% at a stress of 3 MPa.

[0046] If the above polyimide support deviates from the stress and strain conditions indicated in the stress-strain curve, the elongation of the polyimide support measured according to ASTD D 882 may be less than 15%, so the above range is desirable.

[0047] In the present invention, the polyamic acid may be a polymer of BPDA (3,3',4,4'-Biphenyltetracarboxylic dianhydride) and BAPP (2,2-bis[4-(4-aminophenoxy)phenyl]propane) or BPDA and 6F-BAPP (2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane), and preferably a polymer of BPDA and BAPP.

[0048] In addition, the above polyamic acid can be represented by the following chemical formula 1.

[0049] [Chemical Formula 1]

[0050]

[0051] In the above chemical formula 1, X is CH3 or CF3, and n is a natural number greater than or equal to 1.

[0052] In the present invention, the heat treatment can be performed at 250 to 410°C for 10 to 200 minutes, preferably at 270 to 400°C for 30 to 120 minutes, and more preferably at 310 to 390°C for 30 to 60 minutes.

[0053] In the present invention, when the polyimide support is formed of a polyamic acid polymerized with BPDA and BAPP, the heat treatment may be performed at 250 to 410°C for 10 to 200 minutes, preferably at 270 to 350°C for 30 to 120 minutes, and more preferably at 310 to 330°C for 30 to 60 minutes.

[0054] In addition, in the present invention, when the polyimide support is formed of a polyamic acid polymerized with BPDA and 6F-BAPP, the heat treatment may be performed at 250 to 410°C for 10 to 200 minutes, preferably at 300 to 400°C for 30 to 120 minutes, and more preferably at 350 to 390°C for 30 to 60 minutes.

[0055] By heat-treating the polyamic acid at the temperature and time as described above, the elongation of the polyimide support measured according to ASTD D 882 can be 15% or more, so the above range is preferred.

[0056] In the present invention, the polyimide formed by heat-treating the polyamic acid can be represented by the following chemical formula 2.

[0057] [Chemical Formula 2]

[0058]

[0059] In the above chemical formula 2, X is CH3 or CF3, and n is a natural number greater than or equal to 1.

[0060] The above polyimide support may have an elongation of 15 to 50% as measured by the ASTD D 882 method, and a modulus in the TD (Transverse direction) direction as measured by the following Equation 1 may be 30 to 300 MPa.

[0061] [Mathematical Formula 1]

[0062] E=σ / ε

[0063] In the above mathematical formula 1, σ is stress (force per unit area) and ε is strain (strain per unit length).

[0064] In addition, in the present invention, when the polyimide support is formed from a polyamic acid polymerized with BPDA and 6F-BAPP, the modulus in the TD (Transverse direction) direction may be 60 to 100 MPa and the elongation may be 15 to 35%.

[0065] In addition, in the present invention, when the polyimide support is formed from a polyamic acid polymerized with BPDA and BAPP, the modulus in the TD (Transverse direction) direction may be 200 to 300 MPa and the elongation may be 35 to 50%.

[0066] In the present invention, the polyimide support may have a porosity of 50% or more and an average pore size of 0.7 to 5 μm. Additionally, the polyimide support may preferably have a porosity of 60 to 80% and an average pore size of 0.7 to 3 μm.

[0067] In addition, in the present invention, when the polyimide support is formed from a polyamic acid polymerized with BPDA and BAPP, the porosity may be 60 to 80% and the average pore size may be 0.7 to 1 μm.

[0068] In addition, in the present invention, when the polyimide support is formed from a polyamic acid polymerized with BPDA and 6F-BAPP, the porosity may be 60 to 80% and the average pore size may be 1 to 3 μm.

[0069] The thickness of the polyimide support may be 10 to 100 μm, preferably 20 to 80 μm, and the basis weight may be 1 to 50 gsm (Gram per Square Metre), preferably 10 to 30 gsm.

[0070] The polyimide support according to the present invention may have solvent resistance of 95% or more as measured by the following measurement method, preferably 95.5% or more, and more preferably 96% or more.

[0071] [measurement method]

[0072] Solvent resistance: A polyimide support (10×10 cm) is immersed in a solvent for 5 minutes and dried at 60°C for 12 hours, and the weight is measured by comparing the weight before and after. The solvent is DMAC (N,N-dimethylacetamide), DMF (N,N-dimethyl formamide), or NMP (N-methyl-2-pyrrolidone).

[0073] The polyimide support according to the present invention may be used for water electrolysis.

[0074] The present invention will be explained in more detail below through specific embodiments, but the present invention is not limited by the following embodiments.

[0075]

[0076] The ingredients used are as follows.

[0077] BPDA: 3,3',4,4'-Biphenyltetracarboxylic dianhydride

[0078] ODPA: 4,4'-Oxydiphthalic Anhydride

[0079] PMDA: Pyromellitic Dianhydride

[0080] BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane

[0081] 6F-BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane

[0082] ODA: 4,4-Oxydianiline

[0083] DMF: Dimethylformamide

[0084]

[0085] Examples and Comparative Examples

[0086] Polyamic acid solids were prepared by polymerizing dianhydride and diamine monomers in a 1:1 ratio using the combinations shown in Table 1 below. Subsequently, the mixture was mixed and stirred in the organic solvent DMF to prepare 5 L of polyamic acid solution with a solid content of 11 wt% and a solution viscosity of 250 poise (KS M ISO 2555, 23 ℃).

[0087] Specifically, the solution viscosity was measured at 23°C using a Brookfield viscometer in accordance with KS M ISO 2555. During the measurement, the spindle number of the viscometer was set to No. 64 (LV Type), and the rotation speed was set to 3–10 rpm. The measurement was performed after maintaining 5 L of polyamic acid solution in a homogeneous state and ensuring it was sufficiently stabilized.

[0088] After transferring the prepared polyamic acid solution to a solution tank, it was supplied via a metering gear pump to a spinning chamber equipped with 20 nozzles and a high voltage of 60 kV, and electrospun to produce a precursor. At this time, the discharge rate was 4 ml / min, the ratio of the distance between the nozzle and the collecting plate to the distance to the nozzle tip was 1.2, and air at 70°C was blown in the direction of the precursor discharge to disperse the precursor. A converted precursor with a thickness of 150 μm and a unit weight of 20 g / m² was produced through a converting process.

[0089] Subsequently, the converted precursor was transferred in a roll-to-roll manner and heat-treated for 45 minutes to induce imidization, thereby finally producing a polyimide support with a thickness of 50 μm and a unit weight of 15 g / m². The components and heat treatment temperatures used in the examples are as shown in Table 1 below.

[0090]

[0091] Classification Dianhydride Diamine Heat Treatment Temperature (°C) Example 1 BPDA6F-BAPP390 Example 2 BPDABAPP320 Comparative Example 1 PMDAODA320 Comparative Example 2 BPDAODA320 Comparative Example 3 OPDAODA320 Comparative Example 4 BPDABAPP420

[0092]

[0093] Experimental Example 1: Stress-Strain Curve

[0094] The stress-strain curves of the polyimide supports prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were measured according to ASTM D 882 using a tensile testing machine (Instron 5566), and the results are shown in Figures 1 to 5, Table 2, and Table 3. At this time, the samples were prepared with a width of 25 mm and a length of 200 mm, and when the prepared samples were set in the tensile testing machine, the distance between the grips was set to 100 mm, and measurements were taken at a crosshead speed of 5 cm / min.

[0095] Table 2 shows the average slopes of the initial, middle, and final sections, the ratio of the average slopes of the initial and middle sections, and the ratio of the average slopes of the middle and final sections, and Table 3 shows the strains at 1 MPa, 2 MPa, and 3 MPa. Values ​​were rounded to the second decimal place.

[0096]

[0097] Classification Average Slope Initial:Intermediate Average Slope Ratio Intermediate:Final Average Slope Ratio Intermediate Final Example 10.450.070.161:0.161:2.29 Example 21.360.170.291:0.131:1.71

[0098] Classification 1MPa 2MPa 3MPa Example 10.73% 2.48% 7.23% Example 20.25% 0.68% 1.14% Comparative Example 10.32% 1.36% 2.45% Comparative Example 20.12% 0.36% 0.68% Comparative Example 30.12% 0.36% 0.68%

[0099] FIG. 1 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with BPDA and 6F-BAPP of the present invention, FIG. 2 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with BPDA and BAPP of the present invention, FIG. 3 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with PMDA and ODA of a comparative example, FIG. 4 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with BPDA and ODA of a comparative example, and FIG. 5 shows the stress-strain curve of a polyimide formed from a polyamic acid polymerized with OPDA and ODA of a comparative example.

[0100] Referring to Figures 1 and 2, it can be seen that the polyimide support formed from polyamic acid polymerized with BPDA and 6F-BAPP (Example 1) and the polyimide support formed from polyamic acid polymerized with BPDA and BAPP (Example 2) have an elongation of 15% or more.

[0101] On the other hand, referring to FIGS. 3 to 5, the polyimide support formed from polyamic acid polymerized with PMDA and ODA (Comparative Example 1), the polyimide support formed from polyamic acid polymerized with BPDA and ODA (Comparative Example 2), and the polyimide support formed from polyamic acid polymerized with OPDA and ODA (Comparative Example 3) have an elongation of less than 15%, and it can be confirmed that, unlike the present invention, there are no intermediate or final sections.

[0102] In addition, referring to Table 2 above, it can be seen that the polyimide support formed from polyamic acid polymerized with BPDA and 6F-BAPP (Example 1) and the polyimide support formed from polyamic acid polymerized with BPDA and BAPP (Example 2) have an average slope in the initial section that is greater than the average slope in the intermediate section and the average slope in the final section, and the ratio of the average slope in the intermediate section to the average slope in the final section is 1:1.5 to 2.5, and the ratio of the average slope in the initial section to the average slope in the intermediate section is 1:0.1 to 0.5.

[0103] In addition, referring to Table 3 above, it can be seen that the polyimide support (Example 1) formed from polyamic acid polymerized with BPDA and 6F-BAPP has a strain of about 0.73% at a stress of 1 MPa, a strain of about 2.48% at a stress of 2 MPa, and a strain of about 7.23% at a stress of 3 MPa.

[0104] In addition, it can be confirmed that a polyimide support formed from polyamic acid polymerized with BPDA and BAPP (Example 2) has a strain of about 0.25% at a stress of 1 MPa, a strain of about 0.68% at a stress of 2 MPa, and a strain of about 1.14% at a stress of 3 MPa.

[0105]

[0106] Experimental Example 2

[0107] The tensile stress at MaxLoad, tensile strain at MaxLoad, modulus (Young's) in the TD direction, porosity, and average pore size of the polyimide supports prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were measured, and the results are shown in Table 4.

[0108] Strength and elongation were measured according to ASTM D 882 using a tensile testing machine (Instron 5566). The sample was prepared with a width of 25 mm and a length of 200 mm. When setting the prepared sample in the tensile testing machine, the distance between the grips was set to 100 mm, and the measurement was performed at a crosshead speed of 5 cm / min.

[0109] The modulus was calculated using the following mathematical formula 1, E=σ / ε, where σ is stress (force per unit area, MPa) and ε is strain (strain per unit length).

[0110] The pore size is 10cm 2 Samples were prepared with the specified size, and after measuring the actual weight, the results were recorded by comparing them to the theoretical weight. Specifically, the polyimide density was 1.47 g / cm³. 3 It was calculated as {(Theoretical weight - Actual weight) / Theoretical weight} * 100 using the theoretical weight obtained through the sampled area and thickness by applying [theoretical weight].

[0111] The average pore size was calculated by measuring using the Half Dry method in accordance with ASTM F316-03. Specifically, measurements were taken using a capillary flow porometer (CFP) specified in ASTM F316-03. Samples were prepared in dimensions of 3 cm x 3 cm, immersed in Galwick oil (Surface tension: 15.9 dynes / cm) for 5–8 seconds, mounted on the equipment, and measured using the Wet Up / Dry Up test type within Capillary Flow Porometry. The pore size distribution was calculated using a wet curve based on the measured average pore size, and the average pore size was determined using the pressure at which the Half Dry curve and the wet curve intersect.

[0112] Classification Strength in TD direction Elongation Modulus in TD direction Porosity Average pore size Unit MPa% MPa% µm Example 1 5.4 2 28.5 8 4.2 7 7 4.6 1.79 Example 2 16 43.4 2 24 4.2 5 7 3.1 0.82 Comparative Example 19.3 11 1.6 7 11 5.7 27 6.2 0.56 Comparative Example 2 17.5 7 8.3 3 35 0.3 4 7 0.1 0.48 Comparative Example 3 18.9 8.3 3 37 4.3 4 6 5.3 0.66

[0113]

[0114] Referring to Table 4 above, it can be confirmed that the elongation of the polyimide support according to the present invention (Examples 1 and 2) is 15% or more, and the average pore size is 0.7 μm or more.

[0115] On the other hand, it can be confirmed that the elongation of Comparative Examples 1 to 3 is 15% or less and the average pore size is less than 0.7㎛.

[0116]

[0117] Experimental Example 3

[0118] The polyimide support (10×10 cm) of Example 2 was immersed in DMAC (N,N-dimethylacetamide) solvent for 5 minutes, then sealed in a glass bottle and stored for 2 days, and then dried at 60°C for 12 hours. The weight before and after was measured by comparing the results, and the results are shown in Table 5 below.

[0119]

[0120] Classification Weight before treatment (g) Weight after treatment (g) Residual amount (%) Example 10.045 20.043 295.6 Example 20.027 10.0268 98.9 Comparative Example 10.039 10.035 290.0 Comparative Example 20.024 30.022 291.4 Comparative Example 30.038 90.0366 94.1

[0121] Referring to Table 5 above, it can be seen that the solvent resistance of the polyimide support according to the present invention (Examples 1 and 2) is 95% or higher, whereas the solvent resistance of Comparative Examples 1 to 3 is less than 95%.

[0122]

[0123] Experimental Example 4

[0124] The surface of the polyimide support of Example 1, Example 2 and Comparative Example 4 was photographed (X5,000) using a scanning electron microscope and is shown in FIG. 6.

[0125]

[0126] FIG. 6 is a scanning electron microscope (X5,000) image of the surface of the polyimide support of Example 1, Example 2 and Comparative Example 4.

[0127] Referring to FIG. 6, in the case of Examples 1 and 2, pores can be observed, but in the case of Comparative Example 4, it can be observed that it was heat-cured at a high temperature and formed into a film.

[0128]

[0129] The national research and development projects that supported this invention are as follows.

[0130] [Project ID] 2410002345

[0131] [Assignment No.] 00432227

[0132] [Ministry Name] Ministry of Trade, Industry and Energy

[0133] [Project Management (Specialized) Agency Name] Korea Institute of Industrial Technology Planning and Evaluation

[0134] [Research Project Name] Materials and Components Technology Development Project (R&D) Package Type

[0135] [Research Project Title] Development of Manufacturing Technology for High-Weight Nano Nonwoven Fabrics Based on High-Strength, High-Heat Resistant Organic Fibers with Thermal Decomposition Temperature of Over 450℃

[0136] [Name of Project Performing Organization] Kolon Industries Co., Ltd. Gumi Plant

[0137] [Contribution Participation] 50%

[0138] [Research Period] 2025.01.01 ~ 2025.12.

[0139]

[0140] The polyimide support of the present invention can be used at temperatures of 90°C or higher and can have an elongation of 15% or more to withstand swelling of 20% or more of the ionomer during operation. The polyimide support of the present invention has a stress-strain curve different from that of conventional polyimide when the polyamic acid with specified components is heated at a specific temperature, and accordingly, can have a higher elongation than that of conventional polyimide.

Claims

1. A polyimide support formed by heat treatment of polyamic acid, The above polyimide support has a stress-strain curve composed of three sections: initial, intermediate, and final, and A polyimide support having a stress-strain curve in which the average slope of the initial section is greater than the average slope of the intermediate section and the average slope of the final section.

2. In Paragraph 1, The above polyimide support is a polyimide support having a ratio of the average slope of the intermediate section to the average slope of the final section of 1:1 to 3.

3. In Paragraph 1, The above polyimide support is a polyimide support having a ratio of the average slope of the initial section to the average slope of the intermediate section of 1:0.1 to 0.

9.

4. In Paragraph 1, The above polyamic acid is a polyimide support polymerized from BPDA (3,3',4,4'-Biphenyltetracarboxylic dianhydride) and BAPP (2,2-bis[4-(4-aminophenoxy)phenyl]propane) or BPDA and 6F-BAPP (2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane).

5. In Paragraph 1, A polyimide support, wherein the heat treatment is performed at 250 to 410°C for 10 to 200 minutes.

6. In Paragraph 1, The above polyimide support is a polyimide support having a modulus in the TD direction of 30 to 300 MPa and an elongation of 15 to 50% as measured by the following measurement method. [measurement method] Elongation: ASTM D 882 Modulus: Calculated using the following mathematical formula 1 E=σ / ε In the above mathematical formula 1, σ is stress (force per unit area) and ε is strain (strain per unit length) 7. In Paragraph 1, The above polyimide support has a porosity of 50% or more and a pore size of 0.7 to 5㎛.

8. In Paragraph 1, The above polyimide support is a polyimide support having a solvent resistance of 95% or more as measured by the following measurement method. [measurement method] Solvent resistance: A polyimide support (10 x 10 cm) is immersed in a solvent for 5 minutes and dried at 60°C for 12 hours, and the weight is measured by comparing the weight before and after. The solvent is DMAC (N,N-dimethylacetamide), DMF (N,N-dimethyl formamide), or NMP (N-methyl-2-pyrrolidone).

9. In Paragraph 1, The above polyimide support is a polyimide support for water electrolysis.

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