High-strength polyimide porous membrane including benzimidazole and benzene lateral groups and manufacturing method thereof

[0038] Example 1

[0039] A method for preparing a high-strength polyimide porous membrane includes the following steps:

[0040] 1. Synthesis of polyamic acid solution:

[0041] According to benzophenone tetraacid dianhydride (BTDA): 1,4-bis(4'-aminophenoxy)-2-(phenyl)benzene (TPEQ): 2-(4-aminophenyl)-5- Aminobenzimidazole (DAPBI) = 10:6:4 molar ratio for weighing and mixing, first add the two diamine monomers TPEQ and DAPBI with a molar ratio of 6:4 to the metered N,N-dimethyl In DMAc, make the total solid content 20%; then mechanically stir under the protection of nitrogen, and then add BTDA equal to the total amount of the two diamines in batches, and keep it under 25℃ in a nitrogen atmosphere The reaction was carried out for 5 hours to obtain a viscous polyamic acid solution. The polyamic acid solution was sealed and placed in a refrigerator for later use. After 24 hours, its viscosity was measured to be 5.6 Pa·s.

[0042] The structural formula of the polyamic acid polymer obtained in this synthesis step is as follows:

[0043]

[0044] Where n:m=4:6.

[0045] 2. Preparation of polyimide porous membrane:

[0046] Refer below image 3 The shown flow specifically illustrates the preparation of the polyimide porous membrane of this embodiment. The above polyamic acid solution is subjected to an electrostatic spinning process in a high-voltage electric field of 100 kV/m, and the porous polyamic acid film is received by a stainless steel drum. The obtained polyamic acid porous film was thermally imidized in a vacuum tube furnace. The imidization process is as follows: increase from room temperature to 150°C at a temperature increase rate of 10°C/min, keep at this temperature for 10 minutes, and then increase from 150°C to 360°C at a temperature increase rate of 20°C/min, and Keep at 360°C for 30 min.

[0047] After testing, the glass transition temperature of the polyimide porous film after thermal imidization was 295°C. The thermally imidized porous membrane was calendered at 315°C/10MPa for 10 minutes to obtain the final polyimide porous membrane. After testing, the thermal decomposition temperature of the obtained polyimide porous film is 530℃; the porosity is 80%; the dimensional shrinkage rate after heating at 210℃ for 1 hour is 0.2%; the tensile strength of the polyimide porous film is 75MPa .

[0048] Example 2

[0049] 1. Synthesis of polyamic acid solution:

[0050] According to benzophenone tetraacid dianhydride (BTDA): 1,4-bis(4'-aminophenoxy)-2-(phenyl)benzene (TPEQ): 2-(4-aminophenyl)-5- Aminobenzimidazole (DAPBI) = 10:6:4 molar ratio for weighing and mixing, first add the two diamine monomers TPEQ and DAPBI with a molar ratio of 6:4 to the metered DMAc to make the total solid The content is 20%; then mechanically stirred under the protection of nitrogen, and then the BTDA equal to the total amount of the two diamines is added in batches, and the reaction is continued for 5 hours under a nitrogen atmosphere below 25°C to obtain viscous polyamic acid Solution. The polyamic acid solution was sealed and placed in a refrigerator for later use. After 24 hours, its viscosity was measured to be 5.6 Pa·s.

[0051] The structural formula of the polyamic acid polymer obtained in this synthesis step is as follows:

[0052]

[0053] Where n:m=4:6.

[0054] 2. Preparation of polyimide porous membrane:

[0055] Refer below image 3 The shown flow specifically illustrates the preparation of the polyimide porous membrane of this embodiment.

[0056] The above polyamic acid solution is diluted with acetone solvent to a viscosity of 1.5 Pa·s, and then an electrospinning process is implemented in a high-voltage electric field of 45 kV/m, and the polyamic acid porous film is received through a stainless steel drum. The obtained polyamic acid porous film was thermally imidized in a vacuum tube furnace. The imidization process is as follows: increase from room temperature to 250°C at a temperature increase rate of 5°C/min, keep at this temperature for 30 minutes, and then increase from 250°C to 360°C at a temperature increase rate of 20°C/min, and Keep at 360°C for 30 min.

[0057] After testing, the glass transition temperature of the polyimide porous film after thermal imidization is 295℃, and the imidized porous film is calendered at 305℃/20MPa for 5 minutes to obtain the final polyimide porous film . After testing, the thermal decomposition temperature of the obtained polyimide porous film is 530℃; the porosity is 45%; the dimensional shrinkage rate is 0.2% after heating at 210℃ for 1 hour; the tensile strength of the polyimide porous film is 70MPa .

[0058] Example 3

[0059] 1. Synthesis of polyamic acid solution:

[0060] According to benzophenone tetraacid dianhydride (BTDA): 1,4-bis(4'-aminophenoxy)-2-(phenyl)benzene (TPEQ): 2-(4-aminophenyl)-5- Aminobenzimidazole (DAPBI) = 10:6:4 molar ratio for weighing and mixing, first add the two diamine monomers TPEQ and DAPBI with a molar ratio of 6:4 to the metered DMAc to make the total solid The content is 20%; then mechanically stirred under the protection of nitrogen, and then the BTDA equal to the total amount of the two diamines is added in batches, and the reaction is continued for 5 hours under a nitrogen atmosphere below 25°C to obtain viscous polyamic acid Solution. The polyamic acid solution was sealed and placed in a refrigerator for later use. After 24 hours, its viscosity was measured to be 5.6 Pa·s.

[0061] The structural formula of the polyamic acid polymer obtained in this synthesis step is as follows:

[0062]

[0063] Where n:m=4:6.

[0064] 2. Preparation of polyimide porous membrane:

[0065] Refer below image 3 The shown flow specifically illustrates the preparation of the polyimide porous membrane of this embodiment.

[0066] The above polyamic acid solution was diluted with acetone solvent to a viscosity of 2.7 Pa·s, and then an electrospinning process was performed in a high-voltage electric field of 65 kV/m, and the polyamic acid porous film was received by a stainless steel drum. The obtained polyamic acid porous film is thermally imidized in a vacuum tube furnace. The imidization process is as follows: increase from room temperature to 250°C at a temperature increase rate of 5°C/min, keep at this temperature for 30 minutes, and then increase from 250°C to 360°C at a temperature increase rate of 20°C/min, and Keep at 360°C for 30 min.

[0067] After testing, the glass transition temperature of the polyimide porous film after thermal imidization is 295℃, and the imidized porous film is calendered at 310℃/5MPa for 5 minutes to obtain the final polyimide porous film . After testing, the thermal decomposition temperature of the obtained polyimide porous film is 530℃; the porosity is 45%; the dimensional shrinkage rate after heating at 210℃ for 1 hour is 0.2%; the tensile strength of the polyimide porous film is 69MPa .