A polyimide composite intermolecularly complex polybenzimidazole profile and a method for producing the same

Abstract

This invention discloses a polyimide-polybenzimidazole intermolecular composite profile and its preparation method. The preparation method is as follows: First, polybenzimidazole is pre-dissolved to form a homogeneous solution to allow its polymer chains to unfold. Then, aromatic diammonium is added to the system. After the diammonium is completely dissolved, aromatic dianhydride is added to generate polyamic acid in situ in the system. Then, thermal imidization is performed to form a polyimide / polybenzimidazole composite material with entangled polymer chains. This preparation method can achieve full mixing between the polyimide and polybenzimidazole polymer chains. The polyimide-polybenzimidazole intermolecular composite material prepared by this method has advantages such as easy molding and easy processing. The molded profile has good strength and toughness and can be widely used in high-end fields such as aerospace high-temperature structural parts, high-end sealing components, high-temperature wear-resistant parts for new energy equipment, and chemical corrosion-resistant structural profiles.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a polyimide-polybenzimidazole intermolecular composite profile and its preparation method. Background Technology

[0002] Polyimide (PI) and polybenzimidazole (PBI) are both top-tier specialty engineering plastics, each with its own irreplaceable advantages and corresponding shortcomings. Polyimide resins possess excellent high-temperature resistance and outstanding overall performance, including high strength, excellent mechanical properties, high modulus, wear resistance, low dielectric constant, and radiation resistance, making them widely used in the semiconductor field and high-temperature, high-pressure insulating materials. Polybenzimidazole, on the other hand, exhibits extreme high-temperature resistance and stability in extreme environments, as well as excellent resistance to acids, alkalis, and most organic solvents, making it widely used in high-temperature protective equipment, proton exchange membranes for high-temperature fuel cells, and special corrosion-resistant filter materials.

[0003] Currently, polyimide resin profiles and components are well-developed, and polyimide resin materials of specified sizes and shapes can be prepared according to requirements. However, due to its inherent rigidity, polybenzimidazole (PBI) presents challenges in profile manufacturing, such as brittleness during compression molding and easy breakage during processing. If a certain amount of polyimide (PI) can be compounded into PBI, the moldability of PBI profiles can be significantly improved.

[0004] Currently, the common method for preparing PBI composite PI profiles involves physically mixing the powders of both materials until homogeneous, followed by molding. A drawback of this method is that the composite material is formed between micron-sized particles. Current experience shows that, under ideal molding conditions, only up to 20% of PBI and thermosetting PI resin can be mixed and molded. Increasing the PBI proportion leads to cracking of the pressed sheets. Using thermoplastic PI as the base material allows for a PBI proportion up to 50%, but thermoplastic materials exhibit a bottleneck effect in composite material applications. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a polyimide-polybenzimidazole intermolecular composite profile and its preparation method. This preparation method enables thorough mixing between polyimide and polybenzimidazole polymer chains. The polyimide-polybenzimidazole intermolecular composite material prepared in this manner has advantages such as easy molding and processing. The molded profile exhibits good strength and toughness and can be widely used in high-end fields such as aerospace high-temperature structural components, high-end sealing components, high-temperature wear-resistant components for new energy equipment, and chemical corrosion-resistant structural profiles.

[0006] The technical solution adopted in this invention is as follows:

[0007] This invention provides a method for preparing a polyimide-polybenzimidazole intermolecular composite profile, the method comprising the following steps:

[0008] (1) Dissolve polybenzimidazole in a strongly polar aprotic solvent to obtain a polybenzimidazole solution;

[0009] (2) Add aromatic diamine to polybenzimidazole solution, stir evenly, then add aromatic dianhydride, and stir at 40-45℃ for 10-12 h.

[0010] (3) Add the end-capping agent to step (2), continue stirring and react for 5-6 h, then heat and reflux for 5-6 h, cool and centrifuge and dry to obtain polyimide composite polybenzimidazole intermolecular composite material;

[0011] (4) The polyimide-polybenzimidazole intermolecular composite material is molded to obtain the polyimide-polybenzimidazole intermolecular composite profile.

[0012] Furthermore, the mass ratio of polybenzimidazole, aromatic diamine, aromatic dianhydride, and capping agent is 1:0.1~1.0:0.5~1.6:0.01~0.03.

[0013] In step (1), the strongly polar aprotic solvent is any one or more of N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0014] In step (1), the mass concentration of polybenzimidazole in a strongly polar aprotic solvent is 3-10%.

[0015] In step (2), the aromatic diamine is any one or more of 4,4'-diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenylmethane.

[0016] In step (2), the aromatic dianhydride is any one or more of the following: pyromellitic dianhydride, 4,4'-oxobisphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-(hexafluoroisopropyl)diphthalic anhydride, and diphenyl sulfone tetracarboxylic dianhydride.

[0017] In step (3), the capping agent is any one or more of phenylacetylene phthalic anhydride, phenylacetylene aniline, and phthalic anhydride.

[0018] In step (4), the molding conditions are: molding temperature 380~390℃, subsequent pressure not less than 20MPa, and pressure and temperature holding for 1.5~2.5 h.

[0019] This invention also provides a polyimide-polybenzimidazole intermolecular composite profile prepared by the aforementioned method, which has a hardness ≥75HRE, tensile strength ≥140MPa, flexural strength ≥125MPa, elongation at break ≥5%, flexural modulus ≥3300MPa, and impact strength ≥28 kJ / m. 2 .

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The method for preparing polyimide-polybenzimidazole intermolecular composite profiles provided by the present invention firstly involves pre-dissolving polybenzimidazole (PBI) to form a homogeneous solution to allow its polymer chains to unfold. Then, aromatic diammonium is added to the system. After the diammonium is completely dissolved, aromatic dianhydride is added to generate polyamic acid in situ in the system. Then, thermal imidization is performed to form a polyimide / polybenzimidazole composite material with entangled molecular chains. In this method, PI and PBI are tightly bound together in the solution by intermolecular forces such as molecular chain entanglement and π-π stacking, avoiding the stress concentration problem caused by weak interfacial bonding in physical blending, thereby significantly improving the load-bearing capacity and deformation resistance of the material.

[0022] 2. The preparation method provided by this invention employs a step-by-step feeding, low-temperature reaction, and end-capping agent control process, enabling PI and PBI to achieve uniform composite at the molecular scale. This completely eliminates problems such as microscopic phase separation and interface defects caused by poor compatibility between the two phases in physical blending. Simultaneously, the segmented heating and reflux process promotes complete imidization, reduces residual solvents and low-molecular-weight volatiles, and avoids bubbling and cracking during molding, achieving large-scale and stable preparation of composite profiles. After molding, the profiles can effectively resist stress concentration under harsh conditions such as high temperature, high load, and strong impact, significantly reducing the risk of material failure and providing structural support for their long-term stable service in high-end applications.

[0023] 3. Traditional PBI materials are difficult to process and mold, making it challenging to fabricate large-size, complex structural profiles. However, the moldable polyimide-polybenzimidazole composite powder prepared in this invention, combined with a molding process at a molding temperature of 380-390℃ and a molding pressure of no less than 20MPa, successfully solves the industry pain point of PBI's difficulty in thermoforming. This process not only expands the molding size and structural diversity of profiles but also reduces the complexity of the production process and improves the feasibility of industrial production.

[0024] 4. The polyimide-polybenzimidazole intermolecular composite profile provided by the present invention achieves uniform interpenetration of tough PI and rigid PBI molecular chains at the nanoscale. Under the action of external force, the slippage and entanglement of molecular chains can effectively absorb impact energy, significantly improve the toughness of the material, and at the same time possess high strength and high toughness.

[0025] 5. This invention utilizes core processes of in-situ solution compounding, segmented reaction control, and compression molding to prepare polyimide-polybenzimidazole (PBI) intermolecular composite profiles. Compared to traditional physical blending methods, this achieves a breakthrough improvement in the comprehensive mechanical properties of the material, while simultaneously solving common industry problems such as significant brittleness and molding difficulties in single PBI materials, as well as poor compatibility and weak interfacial bonding in physical blends. These profiles can be widely used in high-end fields such as aerospace high-temperature structural components, high-end sealing components, high-temperature wear-resistant parts for new energy equipment, and corrosion-resistant structural profiles for chemical industries, significantly improving the reliability and service life of related products. They possess extremely high industrial application value and market promotion potential. Attached Figure Description

[0026] Figure 1 The sheet material and the tested sample of the polyimide-polybenzimidazole intermolecular composite profile prepared in Example 1;

[0027] Figure 2 The energy dispersive spectroscopy (EDS) spectrum of the polyimide-polybenzimidazole intermolecular composite profile prepared in Example 1 is shown. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the embodiments.

[0029] Example 1

[0030] A method for preparing a polyimide-polybenzimidazole intermolecular composite profile includes the following steps:

[0031] (1) Add 6 kg of N,N-dimethylacetamide to a 10 L glass reactor, and add 500 g of PBI with a molecular weight of 30,000 Mp to it while stirring. Heat to 40-45 °C and stir until PBI is completely dissolved to obtain a PBI solution.

[0032] (2) Add 287.14 g of 4,4'-diaminodiphenyl ether (ODA) to the PBI solution and keep stirring for 30 min, then add 312.86 g of pyromellitic dianhydride (PMDA) and stir for 12 h.

[0033] (3) Add 5g of phenylacetylene phthalic anhydride (PEPA) to step (2), and seal the reaction for 6h. Then heat the system and wait for the system to boil and reflux for 6h before cooling to 30℃. Then centrifuge the material and put the centrifuged material into a vacuum oven to dry. The temperature of the oven is 250℃ and the vacuum degree is not lower than -0.095MPa. Crush and sieve the dried material to obtain polyimide composite polybenzimidazole intermolecular composite material.

[0034] (4) Place the polyimide-polybenzimidazole intermolecular composite material into the mold, with a molding temperature of 385℃ and a subsequent pressure of not less than 20MPa. Hold the pressure and heat for 2 hours, then cool down and demold to obtain the polyimide-polybenzimidazole intermolecular composite profile.

[0035] Example 2

[0036] A method for preparing a polyimide-polybenzimidazole intermolecular composite profile includes the following steps:

[0037] (1) Add 6 kg of N,N-dimethylformamide to a 10 L glass reactor, and add 300 g of PBI with a molecular weight of 50,000 Mp to it while stirring. Heat to 40-45 °C and stir until PBI is completely dissolved to obtain a PBI solution.

[0038] (2) Add 191.43 g of 4,4'-diaminodiphenyl ether (ODA) to the PBI solution and keep stirring for 30 min, then add 208.56 g of pyromellitic dianhydride (PMDA) and stir for 12 h.

[0039] (3) Add 4g of phenylacetylene phthalic anhydride (PEPA) to step (2), and seal the reaction for 6h. Then heat the system and wait for the system to boil and reflux for 6h before cooling to 30℃. Then centrifuge the material and put the centrifuged material into a vacuum oven to dry. The temperature of the oven is 250℃ and the vacuum degree is not lower than -0.095MPa. Crush and sieve the dried material to obtain polyimide composite polybenzimidazole intermolecular composite material.

[0040] (4) Place the polyimide-polybenzimidazole intermolecular composite material into the mold, with a molding temperature of 385℃ and a subsequent pressure of not less than 20MPa. Hold the pressure and heat for 2 hours, then cool down and demold to obtain the polyimide-polybenzimidazole intermolecular composite profile.

[0041] Example 3

[0042] A method for preparing a polyimide-polybenzimidazole intermolecular composite profile includes the following steps:

[0043] (1) Add 6 kg of N-methylpyrrolidone to a 10 L glass reactor, and add 200 g of PBI with a molecular weight of 100,000 Mp while stirring. Heat to 40-45 °C and stir until PBI is completely dissolved to obtain a PBI solution.

[0044] (2) Add 196.32 g of 4,4'-diaminodiphenyl ether (ODA) to the PBI solution and keep stirring for 30 min, then add 304.12 g of pyromellitic dianhydride (PMDA) and stir for 12 h.

[0045] (3) Add 4g of phenylacetylene phthalic anhydride (PEPA) to step (2), and seal the reaction for 6h. Then heat the system and wait for the system to boil and reflux for 6h before cooling to 30℃. Then centrifuge the material and put the centrifuged material into a vacuum oven to dry. The temperature of the oven is 250℃ and the vacuum degree is not lower than -0.095MPa. Crush and sieve the dried material to obtain polyimide composite polybenzimidazole intermolecular composite material.

[0046] (4) Place the polyimide-polybenzimidazole intermolecular composite material into the mold, with a molding temperature of 385℃ and a subsequent pressure of not less than 20MPa. Hold the pressure and heat for 2 hours, then cool down and demold to obtain the polyimide-polybenzimidazole intermolecular composite profile.

[0047] Example 4

[0048] The rest is the same as in Example 1, except that 4,4'-diaminodiphenyl ether (ODA), pyromellitic dianhydride (PMDA), and phenylacetylene phthalic anhydride (PEPA) are replaced with p-phenylenediamine, 4,4'-oxobisphthalic anhydride, and phenylacetylene aniline, respectively.

[0049] Example 5

[0050] The rest is the same as in Example 2, except that 4,4'-diaminodiphenyl ether (ODA), pyromellitic dianhydride (PMDA), and phenylacetylene phthalic anhydride (PEPA) are replaced with 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(hexafluoroisopropyl)diphthalic anhydride, and phthalic anhydride, respectively.

[0051] Example 6

[0052] The rest is the same as in Example 2, except that 4,4'-diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA) are replaced with 4,4'-diaminodiphenyl sulfone and diphenyl sulfone tetracarboxylic dianhydride, respectively.

[0053] Comparative Example 1

[0054] A method for preparing a polyimide / polybenzimidazole composite profile includes the following steps:

[0055] (1) Add 6 kg of N-methylpyrrolidone to a 10 L glass reactor, add 287.14 g of 4,4'-diaminodiphenyl ether (ODA) and keep stirring for 30 min, then add 312.86 g of pyromellitic dianhydride (PMDA) and stir for 12 h.

[0056] (2) Add 5g of phenylacetylene phthalic anhydride (PEPA) to step (1), and seal the reaction for 6h. Then heat the system and wait for the system to boil and reflux for 6h before cooling to 30℃. Then centrifuge the material and put the centrifuged material into a vacuum oven to dry. The temperature of the oven is 250℃ and the vacuum degree is not lower than -0.095MPa. Crush and sieve the dried material to obtain polyimide powder.

[0057] (3) Mix polyimide powder with 500g of PBI powder with a molecular weight of 30,000 Mp evenly, then put it into a mold, mold temperature 385℃, back pressure not less than 20MPa, keep pressure and heat for 2h, then cool down and demold to obtain polyimide / polybenzimidazole composite profile.

[0058] Test case

[0059] The profiles prepared in the above embodiments and comparative examples were tested for hardness, tensile strength, elongation at break, flexural strength, flexural modulus, and impact strength, respectively, with the following test standards as referenced:

[0060] Hardness test: The test shall be conducted in accordance with the "Determination of Hardness of Plastics - Part 2: Rockwell Hardness" (GB / T 3398.2-2008).

[0061] Tensile strength and elongation at break: Tested according to "Determination of tensile properties of plastics - Part 1: General" (GB / T 1040.1-2025).

[0062] Flexural strength and flexural modulus: tested according to "Determination of Flexural Properties of Plastics" (GB / T 9341-2008).

[0063] Impact strength: Tested according to GB / T1043.1-2008 "Determination of impact properties of simply supported plastic beams - Part 1: Non-instrumental impact test".

[0064] The test results are shown in Table 1.

[0065] Table 1

[0066]

[0067] As can be seen from the above, the profiles prepared in the above embodiments have a hardness ≥75HRE, tensile strength ≥140MPa, flexural strength ≥125MPa, elongation at break ≥5%, flexural modulus ≥3300MPa, and impact strength ≥28 kJ / m. 2 The energy dispersive spectroscopy (EDS) spectrum of the polyimide-polybenzimidazole intermolecular composite profile prepared in Example 1 is shown below. Figure 2 As shown in the figure, its nitrogen content is relatively high and positively correlated with the nitrogen content in PBI.

[0068] In contrast to Example 1, Comparative Example 1 used a physical mixing method to prepare the polyimide / polybenzimidazole composite profile, and its performance was inferior to that of Example 1.

[0069] As can be seen, the polyimide-polybenzimidazole intermolecular composite profile prepared by this invention possesses advantages such as high strength, high toughness, and good formability. This profile can be widely used in high-end fields such as aerospace high-temperature structural components, high-end sealing components, high-temperature wear-resistant parts for new energy equipment, and chemical corrosion-resistant structural profiles, significantly improving the reliability and service life of related products, and possessing extremely high industrial application value and market promotion potential.

[0070] The above detailed description of a polyimide-polybenzimidazole intermolecular composite profile and its preparation method, with reference to the embodiments, is illustrative rather than limiting. Several embodiments may be listed within the defined scope. Therefore, variations and modifications without departing from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a polyimide-polybenzimidazole intermolecular composite profile, characterized in that, The preparation method includes the following steps: (1) Dissolve polybenzimidazole in a strongly polar aprotic solvent to obtain a polybenzimidazole solution; (2) Add aromatic diamine to polybenzimidazole solution, stir evenly, add aromatic dianhydride, and stir at 40-45 °C for 10-12 h; (3) Add the end-capping agent to step (2), continue stirring and react for 5-6 h, then heat and reflux for 5-6 h, cool and centrifuge and dry to obtain polyimide composite polybenzimidazole intermolecular composite material; (4) The polyimide-polybenzimidazole intermolecular composite material is molded to obtain the polyimide-polybenzimidazole intermolecular composite profile.

2. The preparation method according to claim 1, characterized in that, The mass ratio of polybenzimidazole, aromatic diamine, aromatic dianhydride, and end-capping agent is 1:0.1~1.0:0.5~1.6:0.01~0.

03.

3. The preparation method according to claim 1 or 2, characterized in that, In step (1), the strongly polar aprotic solvent is any one or more of N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

4. The preparation method according to claim 1 or 2, characterized in that, In step (1), the mass concentration of polybenzimidazole in a strongly polar aprotic solvent is 3-10%.

5. The preparation method according to claim 1 or 2, characterized in that, In step (2), the aromatic diamine is any one or more of 4,4'-diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl sulfone, and 4,4'-diaminodiphenylmethane.

6. The preparation method according to claim 1 or 2, characterized in that, In step (2), the aromatic dianhydride is any one or more of the following: pyromellitic dianhydride, 4,4'-oxobisphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-(hexafluoroisopropyl)diphthalic anhydride, and diphenyl sulfone tetracarboxylic dianhydride.

7. The preparation method according to claim 1 or 2, characterized in that, In step (3), the capping agent is any one or more of phenylacetylene phthalic anhydride, phenylacetylene aniline, and phthalic anhydride.

8. The preparation method according to claim 1 or 2, characterized in that, In step (4), the molding conditions are: molding temperature 380~390℃, subsequent pressure not less than 20MPa, and pressure and temperature holding for 1.5~2.5 h.

9. The polyimide-polybenzimidazole intermolecular composite profile prepared by the preparation method according to any one of claims 1-8.

10. The polyimide-polybenzimidazole intermolecular composite profile as described in claim 9, characterized in that, The polyimide-polybenzimidazole intermolecular composite profile has the following properties: hardness ≥75HRE, tensile strength ≥140MPa, flexural strength ≥125MPa, elongation at break ≥5%, flexural modulus ≥3300MPa, and impact strength ≥28 kJ / m. 2 .

Images