Toughened polyimide resin and preparation method thereof
By introducing short-cut fibers into polyimide resin and improving its structural flexibility, the problem of high brittleness of polyimide resin was solved, and toughness was improved without affecting temperature resistance and mechanical properties, thus expanding its application range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-05
- Publication Date
- 2026-03-10
AI Technical Summary
Polyimide resin materials are brittle and fragile, making them difficult to use in applications requiring high toughness. Existing toughening methods can affect their temperature resistance and mechanical properties.
By introducing short-cut fibers into polyimide resin and then performing ultrasonic dispersion, polymerization reaction, and imidization treatment, the bonding force between the fibers and the resin is improved. The introduction of ether anhydride and ketone anhydride improves structural flexibility, toughness, and glass transition temperature.
Without compromising temperature resistance and mechanical properties, the toughness and application range of polyimide resin are significantly improved, resulting in a comprehensive performance enhancement of the material.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a toughened polyimide resin and its preparation method. Background Technology
[0002] Polyimide resin materials possess excellent properties such as resistance to high and low temperatures, thermal insulation, flame retardancy, and electrical insulation, and have broad application prospects and enormous commercial value in many high-tech fields such as aerospace, shipbuilding, electronics, new energy, and rail transportation. However, polyimide resin materials are brittle, fragile, and difficult to process and mold. They are prone to cracking or breaking when subjected to external impacts or temperature changes, which limits their use in certain applications requiring high toughness.
[0003] Existing technologies for toughening resins can effectively address the problem of high brittleness. There are two main methods: structural toughening and component toughening. Structural toughening involves introducing flexible and cross-linking active groups during the preparation of polyimide resins to achieve structural toughening. Component toughening involves adding toughening chopped fibers during the raw material mixing stage. Each method has its advantages and disadvantages. For structural toughening, introducing too many flexible and cross-linking active groups can reduce the resin's temperature resistance and lower the degree of polymerization, failing to achieve complete improvement at the molecular structure level. For component toughening, adding too many toughening chopped fibers often leads to a certain degree of decrease in the material's mechanical and heat resistance properties. Summary of the Invention
[0004] In view of this, the main objective of the present invention is to provide a method for preparing toughened polyimide resin, which improves the toughness of polyimide resin without affecting its temperature resistance and mechanical properties.
[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:
[0006] A method for preparing toughened polyimide resin, comprising the following steps:
[0007] S1. The fiber is added to the solvent and ultrasonically dispersed to obtain a dispersion.
[0008] S2. Add 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, and pyromellitic dianhydride to the dispersion in step S1 to dissolve them and obtain an intermediate mixture.
[0009] S3. Add diisocyanate to the intermediate mixture described in step S2, and obtain a polymerization intermediate solution through a polymerization reaction;
[0010] S4. The polymerization intermediate solution is subjected to an imidization reaction to obtain a toughened polyimide resin.
[0011] Preferably, a preprocessing step is included before step S1, specifically:
[0012] The polyimide resin is completely dissolved in a solvent, then the fiber is added, stirred, mixed thoroughly, and dried to obtain fiber pre-impregnated with polyimide.
[0013] Preferably, the polyimide resin is an ether anhydride type polyimide resin; the fiber is a short-cut fiber with a length of 1-5 mm; and the mass ratio of the polyimide resin to the fiber is 2-4:100.
[0014] Preferably, in step S1, the fiber is at least one of carbon fiber, glass fiber, and polyimide fiber.
[0015] Preferably, in step S1, the solvent is N,N-dimethylacetamide, N-methylpyrrolidone, or N,N-dimethylformamide.
[0016] Preferably, the diisocyanate in step S3 is MDI, TDI, or a mixture of both.
[0017] Preferably, in step S3, the polymerization reaction temperature is 30–50°C, the reaction time is 4–8 h, and the solid content of the polymerization intermediate solution is 10–30% by mass.
[0018] Preferably, in step S4, the imidization reaction specifically includes: heating at 70-80°C for 20-30 min, then raising the temperature to 150-160°C and heating for 20-30 min, and continuing to raise the temperature to 250-260°C and heating for 0.5-1 h.
[0019] Another objective of this invention is to provide a toughened polyimide resin obtained by the above preparation method.
[0020] Preferably, the fiber accounts for 5-8% of the product by mass.
[0021] Compared with existing methods, this invention improves the bonding force between polyimide and chopped fibers, enabling the chopped fibers to be more uniformly dispersed in the polyimide resin matrix, thereby endowing the polyimide resin with better overall properties. At the same time, the introduction of ether anhydride and ketone anhydride improves the flexibility of the resin structure through the introduction of ether bonds, and the secondary crosslinking of carbonyl groups in ketone anhydride under high temperature conditions improves the toughness and glass transition temperature of the polyimide resin, thereby effectively improving the toughness of the polyimide resin and expanding the application range of the polyimide resin. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0023] This invention provides a method for preparing toughened polyimide resin, which is achieved through the following steps:
[0024] A method for preparing toughened polyimide resin, comprising the following steps:
[0025] S1. The fiber is added to the solvent and ultrasonically dispersed to obtain a dispersion.
[0026] S2. Add 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, and pyromellitic dianhydride to the dispersion in step S1 to dissolve them and obtain an intermediate mixture.
[0027] S3. Add diisocyanate to the intermediate mixture described in step S2, and obtain a polymerization intermediate solution through a polymerization reaction;
[0028] S4. The polymerization intermediate solution is subjected to an imidization reaction to obtain a toughened polyimide resin.
[0029] Specifically, a preprocessing step is included before step S1, which includes:
[0030] The polyimide resin is completely dissolved in a solvent, then the fiber is added, stirred, mixed thoroughly, and dried to obtain fiber pre-impregnated with polyimide.
[0031] Specifically, the polyimide resin is an ether anhydride type polyimide resin; the fiber is a short-cut fiber with a length of 1 to 5 mm; and the mass ratio of the polyimide resin to the fiber is 2 to 4:100.
[0032] Specifically, in step S1, the fiber is at least one of carbon fiber, glass fiber, and polyimide fiber.
[0033] Specifically, in step S1, the solvent is N,N-dimethylacetamide, N-methylpyrrolidone, or N,N-dimethylformamide.
[0034] Specifically, in step S3, the diisocyanate is MDI, TDI, or a mixture of both.
[0035] Specifically, in step S3, the polymerization reaction temperature is 30–50°C, and the reaction time is 4–8 h; the solid content of the polymerization intermediate solution is 10–30% by mass.
[0036] Specifically, in step S4, the imidization reaction includes: heating at 70-80°C for 20-30 minutes, then heating at 150-160°C for 20-30 minutes, and then heating at 250-260°C for 0.5-1 hour.
[0037] Another objective of this invention is to provide a toughened polyimide resin obtained by the above preparation method.
[0038] Specifically, the fiber accounts for 5-8% of the product's mass fraction.
[0039] The following are specific examples.
[0040] Example 1
[0041] Example 1 of this invention provides a method for preparing toughened polyimide resin, which is achieved through the following steps:
[0042] S1. Add 85g of modified short-cut carbon fibers with a length of 2mm to 5000g of N,N-dimethylacetamide and disperse them by ultrasonication to obtain a dispersion.
[0043] S2. Add 850g of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, and pyromellitic dianhydride to the dispersion in a molar ratio of 1:1:1 to dissolve them and obtain an intermediate mixture.
[0044] S3. 750g of MDI diisocyanate was added to the intermediate mixture described in S2 according to the molar ratio of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, pyromellitic dianhydride and diisocyanate in a ratio of 1:1:1:3. The polymerization intermediate solution was obtained by polymerization reaction at 30°C for 6 hours.
[0045] S4. The polymerization intermediate solution is subjected to an imidization reaction to obtain the toughened polyimide resin. The specific method of the imidization reaction is as follows: heating at 70°C for 20 min, then heating at 150°C for 20 min, and then heating at 250°C for 0.5 h.
[0046] The toughened polyimide resin prepared according to the above method has a short-cut carbon fiber content of 6% by mass.
[0047] Example 2
[0048] Example 2 of this invention provides a method for preparing toughened polyimide resin, which is achieved through the following steps:
[0049] S1. Add 150g of modified short-cut carbon fiber with a length of 5mm to 6000g of N-methylpyrrolidone and disperse it by ultrasonication to obtain a dispersion.
[0050] S2. Add 850g of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, and pyromellitic dianhydride to the dispersion in a molar ratio of 1:1:1 to dissolve them and obtain an intermediate mixture.
[0051] S3. 1000g of MDI diisocyanate was added to the intermediate mixture according to the molar ratio of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, pyromellitic dianhydride and the diisocyanate of 1:1:1:4, and the polymerization intermediate solution was obtained by polymerization reaction at 50°C for 8 hours.
[0052] S4. The polymerization intermediate solution is subjected to an imidization reaction to obtain the toughened polyimide resin. The specific method of the imidization reaction is as follows: heating at 80°C for 30 min, then heating at 160°C for 30 min, and then heating at 260°C for 1 h.
[0053] The toughened polyimide resin prepared according to the above method has a short-cut carbon fiber content of 8% by mass.
[0054] Example 3
[0055] Example 3 of this invention provides a method for preparing toughened polyimide resin, which is achieved through the following steps:
[0056] S1. Add 85g of modified short-cut polyimide fibers with a length of 5mm to 4500g of N,N-dimethylacetamide and disperse by ultrasonication to obtain a dispersion.
[0057] S2. Add 850g of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, and pyromellitic dianhydride to the dispersion in a molar ratio of 1:1:1 to dissolve them and obtain an intermediate mixture.
[0058] S3. 750g of MDI diisocyanate was added to the intermediate mixture according to the molar ratio of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, pyromellitic dianhydride and the diisocyanate of 1:1:1:3, and the polymerization intermediate solution was obtained by polymerization reaction at 30°C for 6h.
[0059] S4. The polymerization intermediate solution is subjected to an imidization reaction to obtain the toughened polyimide resin. The specific method of the imidization reaction is as follows: heating at 70°C for 30 min, then heating at 150°C for 30 min, and then heating at 250°C for 1 h.
[0060] The toughened polyimide resin prepared according to the above method has a chopped polyimide content of 5% by mass.
[0061] Example 4
[0062] Example 4 of this invention provides a method for preparing toughened polyimide resin, which is achieved through the following steps:
[0063] S1. Add 85g of modified short-cut carbon fibers with a length of 4mm to 5000g of N,N-dimethylformamide and disperse them by ultrasonication to obtain a dispersion.
[0064] S2. Add 850g of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, and pyromellitic dianhydride to the dispersion in a molar ratio of 1:1:1 to dissolve them and obtain an intermediate mixture.
[0065] S3. 750g of MDI diisocyanate was added to the intermediate mixture according to the molar ratio of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, pyromellitic dianhydride and the diisocyanate of 1:1:1:3, and the polymerization intermediate solution was obtained by polymerization reaction at 30°C for 8 hours.
[0066] S4. The polymerization intermediate solution is subjected to an imidization reaction to obtain the toughened polyimide resin. The specific method of the imidization reaction is as follows: heating at 80°C for 20 min, then heating at 160°C for 20 min, and then heating at 260°C for 0.5 h.
[0067] The toughened polyimide resin prepared according to the above method has a short-cut carbon fiber content of 5% by mass.
[0068] Example 5
[0069] Example 5 of this invention provides a method for preparing toughened polyimide resin, which is achieved through the following steps:
[0070] S1. Add 85g of modified short-cut carbon fibers with a length of 2mm to 5500g of N-methylpyrrolidone and disperse them by ultrasonication to obtain a dispersion.
[0071] S2. Add 850g of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, and pyromellitic dianhydride to the dispersion in a molar ratio of 1:1:1 to dissolve them and obtain an intermediate mixture.
[0072] S3. 875g of MDI diisocyanate was added to the intermediate mixture according to the molar ratio of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, pyromellitic dianhydride and the diisocyanate of 1:1:1:3.5, and the polymerization intermediate solution was obtained by polymerization reaction at 40°C for 8 hours.
[0073] S4. The polymer intermediate solution is subjected to an imidization reaction to obtain the toughened polyimide resin. The specific method of the thermosetting reaction is as follows: heating at 70°C for 20 min, then heating at 150°C for 20 min, and then heating at 250°C for 0.5 h.
[0074] The toughened polyimide resin prepared according to the above method has a short-cut carbon fiber content of 6% by mass.
[0075] Example 6
[0076] Example 6 of this invention provides a method for preparing toughened polyimide resin, which is achieved through the following steps:
[0077] S1. Add 85g of modified short-cut glass fibers with a length of 2mm to 5000g of N,N-dimethylacetamide and disperse them by ultrasonication to obtain a dispersion.
[0078] S2. Add 850g of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, and pyromellitic dianhydride to the dispersion in a molar ratio of 1:1:1 to dissolve them and obtain an intermediate mixture.
[0079] S3. 520g of TDI diisocyanate was added to the intermediate mixture according to the molar ratio of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, pyromellitic dianhydride and the diisocyanate of 1:1:1:3, and the polymerization intermediate solution was obtained by polymerization reaction at 30°C for 8 hours.
[0080] S4. The polymer intermediate solution is subjected to an imidization reaction to obtain the toughened polyimide resin. The specific method of the thermosetting reaction is as follows: heating at 70°C for 30 min, then heating at 150°C for 30 min, and then heating at 250°C for 1 h.
[0081] The toughened polyimide resin prepared according to the above method has a chopped glass fiber content of 6% by mass.
[0082] Example 7
[0083] Embodiment 7 of the present invention is implemented according to Embodiment 1. Before step S1, a pretreatment step is also included, specifically: according to the mass ratio of polyimide resin to chopped fiber of 3:100, 2.55 g of polyimide resin is added to a solvent and completely dissolved, then 85 g of chopped carbon fiber with a length of 2 mm is added, and then stirred, mixed thoroughly, and dried to obtain chopped fiber pre-impregnated with polyimide.
[0084] Example 8
[0085] Embodiment 8 of the present invention is implemented according to Embodiment 1. Before step S1, a pretreatment step is included, specifically: according to the mass ratio of polyimide resin to chopped fiber of 2:100, 1.7 g of polyimide resin is added to a solvent and completely dissolved, then 85 g of chopped carbon fiber with a length of 2 mm is added, and then stirred, mixed thoroughly, and dried to obtain chopped fiber pre-impregnated with polyimide.
[0086] Example 9
[0087] Example 9 of the present invention is implemented according to Example 1. Before step S1, a pretreatment step is included, specifically: according to the mass ratio of polyimide resin to chopped fiber of 4:100, 3.4 g of polyimide resin is added to a solvent and completely dissolved, then 85 g of chopped carbon fiber with a length of 2 mm is added, and then stirred, mixed thoroughly, and dried to obtain chopped fiber pre-impregnated with polyimide.
[0088] Comparative Example 1
[0089] Comparative Example 1 of the present invention is implemented according to Example 1, except that the amount of short-cut carbon fiber added in step S1 is changed to 14g.
[0090] The toughened polyimide resin prepared according to the above method has a short-cut carbon fiber content of 1% by mass.
[0091] Comparative Example 2
[0092] Comparative Example 2 of the present invention is implemented according to Example 1, except that in step S2, 850g of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4'-biphenyl ether dianhydride, and pyromellitic dianhydride in a molar ratio of 1:1:1 is replaced with 654g of pyromellitic dianhydride alone.
[0093] Comparative Example 3
[0094] Comparative Example 3 of the present invention was implemented according to Example 1, except that the polymerization temperature of the imidization reaction in step S4 was changed to 60°C.
[0095] Comparative Example 4
[0096] Comparative Example 4 of the present invention was implemented according to Example 1, except that the final temperature of the imidization reaction in step S4 was changed to 280°C: heating at 70°C for 20 min, then heating at 150°C for 20 min, and then heating at 280°C for 0.5 h.
[0097] To further verify the performance of the toughened polyimide resin obtained by this invention, the performance of the toughened polyimide resins obtained in Examples 1-6 and the polyimide resins obtained in Comparative Examples 1-4, when pressed into standard test samples, was tested and compared. The test results are shown in the table below:
[0098]
[0099] The above test results were obtained by testing resin particles under standard test conditions, such as by extruding or injection molding samples, after the resin particles were pressed into a sample block by membrane pressing (300℃).
[0100] Heat distortion temperature: The heat distortion temperature was determined by DSC measurement using a differential scanning calorimeter under a nitrogen atmosphere at a heating rate of 10℃ / min.
[0101] Mechanical properties: determined using a universal testing machine in accordance with GB / T 1040.3-2006.
[0102] As shown in the table above, in the preparation of toughened polyimide resin in this embodiment of the invention, a polymerization intermediate solution is obtained by first polymerizing 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-biphenyl ether dianhydride, and pyromellitic tetracarboxylic dianhydride with diisocyanate, wherein at least one of the short-cut carbon fibers, glass fibers, and polyimide fibers modified by polyimide resin is dispersed therein. Then, the polymerization intermediate solution is subjected to an imidization reaction. The resulting polyimide resin improves the bonding force between polyimide and short-cut fibers, allowing the short-cut fibers to be more uniformly dispersed in the polyimide resin matrix, thereby endowing the polyimide resin with better comprehensive properties. At the same time, the introduction of ether anhydride and ketone anhydride improves the flexibility of the resin structure through ether bonds, and the secondary crosslinking of carbonyl groups in ketone anhydride under high temperature conditions improves the toughness and heat distortion temperature of the polyimide resin, so that the resin achieves a good balance in terms of temperature resistance and mechanical properties, thereby effectively increasing the application range of polyimide resin.
[0103] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for preparing a toughened polyimide resin, characterized by, The method is realized by the following steps: S1, the fiber is added to the solvent for ultrasonic dispersion, and a dispersion liquid is obtained; S2, 3, 3', 4, 4'-benzophenone tetracarboxylic dianhydride, 4, 4'-diphenyl ether dianhydride and pyromellitic dianhydride are added to the dispersion liquid of step S1 for dissolution, and an intermediate mixed liquid is obtained; S3, the diisocyanate is added to the intermediate mixed liquid of step S2, and a polymerization intermediate solution is obtained by polymerization reaction; S4, the imidization reaction is carried out on the polymerization intermediate solution, and the product toughened polyimide resin is obtained.
2. The method for preparing a toughened polyimide resin according to claim 1, characterized in that, The step S1 further includes a pretreatment step, specifically: The polyimide resin is added to the solvent for complete dissolution, then the fiber is added, and then stirring, mixing, drying are carried out to obtain the polyimide pre-impregnated fiber.
3. The method for preparing a toughened polyimide resin according to claim 2, characterized in that, The polyimide resin is ether anhydride type polyimide resin; the fiber is chopped fiber, and the length of the chopped fiber is 1-5mm; the mass ratio of the polyimide resin to the chopped fiber is 2-4:
100.
4. The method for preparing a toughened polyimide resin according to claim 1, characterized in that, In the step S1, the fiber is at least one of carbon fiber, glass fiber and polyimide fiber.
5. The method for preparing a toughened polyimide resin according to claim 1, characterized in that, In the step S1, the solvent is N, N-dimethylacetamide, N-methylpyrrolidone or N, N-dimethylformamide.
6. The method for preparing a toughened polyimide resin according to claim 1, characterized in that, In the step S3, the diisocyanate is MDI, TDI or a mixture of the two.
7. The method for preparing a toughened polyimide resin according to claim 1, characterized in that, In the step S3, the temperature of the polymerization reaction is 30-50℃, and the reaction time is 4-8h; the solid content mass fraction of the polymerization intermediate solution is 10-30%.
8. The method for preparing a toughened polyimide resin according to claim 1, characterized in that, In the step S4, the imidization reaction specifically includes: heating at 70-80℃ for 20-30min, then heating at 150-160℃ for 20-30min, and then heating at 250-260℃ for 0.5-1h.
9. A toughened polyimide resin characterized by, The toughened polyimide resin is prepared by the preparation method of any one of claims 1-9.
10. The toughened polyimide resin according to claim 9, wherein The mass fraction of the fiber in the product toughened polyimide resin is 5-8%.