Hard open-cell polyimide foam and preparation method thereof
By preparing rigid open-cell polyimide foam, the problem of excessive density of polyimide foam and the only way to produce closed-cell foam is solved, and foam materials with low density and high open-cell ratio are achieved, and its scope of application is expanded.
Patent Information
- Application Number
- CN202510448656.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-10
- Publication Date
- 2025-05-27
AI Technical Summary
In the prior art, the density of polyimide foam is too high and can only produce closed-cell foam, and the scope of application is limited.
Rigid open-porous polyimide foam was prepared by adding dianhydride to a polar solvent, heating and esterification under gas atmosphere, and adding diamine and surfactant to form a precursor powder, and then foaming under vacuum heating conditions, and finally imidizing under air and heating conditions.
The low-density and open-porous structure of polyimide foam is achieved, with a density of 25-80kg/m3 and a porosity of 90-99%, which expands production conditions and has a wider range of application.
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of polymer foam materials, and particularly relates to a rigid open-cell polyimide foam and a preparation method thereof. Background Art
[0002] Polyimide foam has properties such as light weight, flame retardancy, low thermal conductivity, resistance to high and low temperatures, and strong chemical stability. As a special engineering plastic foam material, it is widely used in the fields of machinery, energy, environmental protection, etc.
[0003] At present, the main foaming processes for preparing polyimide foam include extrusion foaming method, temperature-rising foaming method, microwave foaming method, and vacuum foaming method, etc. Among them, the vacuum foaming method is realized by applying a relatively high vacuum degree on the basis of the temperature-rising foaming method, and has the advantages of simple process, low foaming temperature, small foam density, and less energy consumption, and is easy to realize large-scale production using industrial equipment.
[0004] Patent CN113788979 discloses a polyimide foam and a preparation method thereof, and a rigid closed-cell polyimide foam is prepared by a vacuum foaming method using polyimide precursor powder. However, the density of the polyimide foam in this scheme is 80 - 900 kg / m 3 , its density is too high, and only closed-cell foam can be produced, so the applicable range is limited.
[0005] The literature (Kuang-Min Ting, Jun Xu, Bao-Hua Guo, A novel vacuum-assisted method for fabricating flexible polyimide foams from 3,3’,4,4’-oxydiphthalic anhydride / 4,4’-oxydianiline. High Performance Polymers 2016, 29(3): 1 - 7, DOI: 10.1177 / 0954008316639367) prepared open-cell foams with a density of 15 - 28 kg / m 3 by a vacuum foaming method, but in this scheme, a polyimide precursor solution was used for foaming, and the precursor in solution state is not conducive to storage and use. Summary of the Invention
[0006] Aiming at the deficiencies of the prior art, the present invention provides a rigid open-cell polyimide foam and a preparation method thereof.
[0007] The technical solution provided by the present invention is as follows: a rigid open-cell polyimide foam, which is prepared by adding dianhydride into a polar solvent, adding a certain amount of small molecule fatty alcohol in a gas atmosphere and heating to complete esterification, adding a certain amount of diamine, heating and polymerizing for a certain time, adding a certain amount of surfactant, drying the obtained solution under vacuum heating conditions, sieving and pulverizing to obtain a precursor powder, and then foaming the precursor powder under vacuum heating conditions, and imidizing the obtained pre-foamed precursor foam under air and heating conditions.
[0008] The dianhydride is at least one of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-oxydiphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and pyromellitic dianhydride;
[0009] The polar solvent is selected from at least one of tetrahydrofuran, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone;
[0010] Preferably, the polar solvent is selected from tetrahydrofuran.
[0011] The small molecule fatty alcohol is selected from at least one of methanol and ethanol;
[0012] The gas atmosphere is selected from at least one of air, nitrogen, helium, neon, argon, krypton, and xenon;
[0013] Preferably, the gas atmosphere is nitrogen.
[0014] The temperature for heating esterification is 50-100 °C;
[0015] Preferably, the temperature for heating esterification is 75 °C.
[0016] The temperature for heating polymerization is 50-90 °C, and the time is 4-12 h;
[0017] Preferably, the temperature for heating polymerization is 70 °C, and the time is 10 h.
[0018] The diamine is selected from at least one of p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 3,4'-diaminodiphenyl ether;
[0019] The surfactant is selected from at least one of silicone oil DC-193, silicone oil AK-8805, and silicone oil silok2008N;
[0020] Preferably, the surfactant is selected from silicone oil DC-193.
[0021] The absolute pressure of the vacuum condition for drying is 0-0.02 MPa, and the temperature of the heating condition is 50-80 °C.
[0022] The sieve plate diameter of the sieving and pulverizing is 5 to 500 mesh;
[0023] Preferably, the sieve plate diameter of the sieving and pulverizing is 16 mesh.
[0024] The mass ratio of the dianhydride to the polar solvent is 1:(2 to 6); the mass ratio of the dianhydride to the small molecule fatty alcohol is 1:(0.5 to 2.5).
[0025] Preferably, the mass ratio of the dianhydride to the polar solvent is 1:4; the mass ratio of the dianhydride to the small molecule fatty alcohol is 1:1.
[0026] The molar ratio of the dianhydride to the diamine is 100:(95 to 105).
[0027] Preferably, the molar ratio of the dianhydride to the diamine is 100:100.
[0028] The mass ratio of the sum of the masses of the dianhydride and the diamine to the mass of the surfactant is 100:(0.3 to 5);
[0029] The absolute pressure of the vacuum condition for foaming is 0 to 0.01 MPa, the temperature of the heating condition is 80 to 200 °C; the time is 0 to 1 h.
[0030] The temperature of imidization under the heating condition is 310 to 370 °C, and the time is 0.5 h to 1 h;
[0031] Preferably, the imidization temperature is 350 °C.
[0032] The present invention further provides a polyimide foam material prepared by the above preparation method.
[0033] Compared with the prior art, the present invention develops a method of first preparing a precursor powder and then vacuum foaming. Since the precursor powder can be stored for a long time and is convenient to use, the production conditions of producing polyimide foam by the vacuum foaming method are expanded, and the separation of the precursor preparation and the foaming process can be realized, and the restrictions on the production area and time are less. The prepared foam presents an open-cell structure, the density is 25 - 80 kg / m3, and the open-cell rate is 90 to 99%.
[0034] Obviously, based on the above content of the present invention, according to the common general knowledge and customary means in the art, without departing from the above basic technical idea of the present invention, various other forms of modifications, substitutions or changes can also be made.
[0035] The following is a further detailed description of the above content of the present invention through specific embodiments in the form of examples. However, this should not be understood that the scope of the above subject matter of the present invention is limited to the following examples. All technologies implemented based on the above content of the present invention belong to the scope of the present invention Detailed implementation mode
[0036] The present invention will be described in detail below, and its features and advantages will become clearer and more definite along with these descriptions.
[0037] Here, the special term "exemplary" means "serving as an example, embodiment or illustration". Any embodiment described as "exemplary" here does not have to be construed as superior or better than other embodiments.
[0038] The raw materials and equipment used in the specific implementation mode of the present invention are all known products and are obtained by purchasing commercially available products.
[0039] Example 1. Preparation of rigid open-cell polyimide foam of the present invention
[0040] Step (1): Add 31 g (0.1 mol) of 3,3',4,4'-oxydiphthalic anhydride to 124 g of tetrahydrofuran, add 31 g of methanol, and heat to complete esterification at 70 °C under a nitrogen atmosphere to obtain solution A;
[0041] Step (2): Add 20 g (0.1 mol) of 4,4'-diaminodiphenyl ether to solution A obtained in step (1), and heat for a polymerization reaction at 65 °C for 10 h to obtain precursor solution B;
[0042] Step (3): Add 0.84 g of DC-193 to precursor solution B obtained in step (2) and dissolve it to obtain solution C;
[0043] Step (4): Dry solution C obtained in step (3) under the conditions of maintaining the pressure at 0 - 0.02 MPa and the temperature at 50 - 80 °C to obtain solid D;
[0044] Step (5): Sieve and crush solid D obtained in step (4) through a 16-mesh sieve plate to obtain foamable precursor powder E;
[0045] Step (6): Heat precursor powder E obtained in step (5) to 170 °C under the condition of maintaining the pressure at 0 - 0.01 Mpa and keep it for 0.5 h to obtain pre-foamed precursor foam F;
[0046] Step (7): Heat pre-foamed precursor foam F to 350 °C and keep it for 1 h for imidization, and then cool to obtain the rigid open-cell polyimide foam.
[0047] The density of the rigid open-cell polyimide foam obtained in this example is 51.3 kg / m 3 , and the open-cell rate is 95.3%.
[0048] Example 2. Preparation of the rigid open-cell polyimide foam of the present invention
[0049] Except that the variety and quality of the diamine in step (2) of Example 1 were changed to 20 g (0.1 mol) of 3,4'-diaminodiphenyl ether, and the holding time in step (7) was changed to 1 h, the remaining operations were the same as those in Example 1.
[0050] The density of the rigid open-cell polyimide foam obtained in this example was 47.7 kg / m 3 , and the open-cell rate was 96.3%.
[0051] Example 3. Preparation of the rigid open-cell polyimide foam of the present invention
[0052] Except that the variety and quality of the dianhydride in step (1) of Example 1 were changed to a mixture of 21.7 g (0.07 mol) of 3,3',4,4'-oxydiphthalic anhydride and 6.54 g (0.03 mol) of pyromellitic dianhydride, the remaining operations were the same as those in Example 1.
[0053] The density of the rigid open-cell polyimide foam obtained in this example was 28.2 kg / m 3 , and the open-cell rate was 98.6%.
[0054] Example 4. Preparation of the rigid open-cell polyimide foam of the present invention
[0055] Except that the variety and quality of the dianhydride in step (1) of Example 1 were changed to a mixture of 27.9 g (0.07 mol) of 3,3',4,4'-oxydiphthalic anhydride and 2.18 g (0.01 mol) of pyromellitic dianhydride, the remaining operations were the same as those in Example 1.
[0056] The density of the rigid open-cell polyimide foam obtained in this example was 45.6 kg / m 3 , and the open-cell rate was 96.5%.
[0057] Example 5. Preparation of the rigid open-cell polyimide foam of the present invention
[0058] Except that the variety and quality of the diamine in step (2) of Example 1 were changed to a mixture of 14 g (0.07 mol) of 4,4'-diaminodiphenyl ether and 3.24 g (0.03 mol) of p-phenylenediamine, the remaining operations were the same as those in Example 1.
[0059] The density of the rigid open-cell polyimide foam obtained in this example was 69.0 kg / m 3 , and the open-cell rate was 91.2%.
[0060] Example 6. Preparation of the rigid open-cell polyimide foam of the present invention
[0061] Except that the type and mass of diamine in step (2) of Example 1 were changed to a mixture of 18 g (0.09 mol) of 4,4'-diaminodiphenyl ether and 1.08 g (0.03 mol) of p-phenylenediamine, the remaining operations and examples were the same as those of Example 1.
[0062] The density of the rigid open-cell polyimide foam obtained in this example is 63.2 kg / m 3 , the opening rate is 93.8%.
[0063] Example 7: Preparation of the rigid open-cell polyimide foam of the present invention
[0064] Except that the mass of DC-193 in step (3) of Example 1 was changed to 1.53 g, the rest of the operations and examples were the same as those in 1.
[0065] The density of the rigid open-cell polyimide foam obtained in this example is 57.3 kg / m 3 , the opening rate is 94.5%.
[0066] Example 8: Preparation of the rigid open-cell polyimide foam of the present invention
[0067] Except that the foaming temperature in step (6) of Example 1 is changed to 130 degrees Celsius and the time is 0.25 hours, the rest of the operations and examples are the same as those in 1.
[0068] The density of the rigid open-cell polyimide foam obtained in this example is 58.9 kg / m 3 , the opening rate is 92.7%.
[0069] Finally, it should be pointed out that the above embodiments are only representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in this field should be considered as the protection scope of the present invention.
Claims
1. A method for preparing a rigid open-cell polyimide foam, characterized in that The steps include: Step (1), adding dianhydride to a polar solvent, adding a certain amount of small molecular fatty alcohol, and heating in a gas atmosphere until the dianhydride is completely esterified and dissolved to obtain a solution A; Step (2), adding a certain amount of diamine to the solution A obtained in step (1), heating and polymerizing in a gas atmosphere for a certain period of time to obtain a precursor solution B; Step (3), adding a certain amount of surfactant to the precursor solution B obtained in step (2), dissolving it, and obtaining solution C; Step (4), drying the solution C obtained in step (3) under vacuum heating conditions, sieving and crushing to obtain a foamable precursor powder E; Step (5), foaming the precursor powder E obtained in step (4) under vacuum heating conditions to obtain a pre-foamed precursor foam F; Step (6), imidizing the pre-foamed precursor foam F under air and heating conditions, and cooling to obtain the rigid open-cell polyimide foam.
2. The method for preparing a rigid open-cell polyimide foam according to claim 1, characterized in that: In step (1), the mass ratio of dianhydride, polar solvent and small molecule fat is 1:(2-6):(0.5-2.5); The dianhydride is selected from at least one of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-oxydiphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and pyromellitic dianhydride; the polar solvent is selected from at least one of tetrahydrofuran, dimethylformamide, dimethylacetamide, or N-methylpyrrolidone; the small molecule fatty alcohol is selected from at least one of methanol and ethanol; The temperature of the heating esterification is 50-100°C.
3. The method for preparing a rigid open-cell polyimide foam according to claim 1, characterized in that: In step (2), the molar ratio of diamine to dianhydride is 1:(0.95-1.05); The diamine is selected from at least one of p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 3,4'-diaminodiphenyl ether; The gas atmosphere is selected from at least one of air, nitrogen, helium, neon, argon, krypton, and xenon; The temperature of the heating polymerization is 50-90° C. and the time is 4-12 hours.
4. The method for preparing a rigid open-cell polyimide foam according to claim 1, characterized in that: In step (3), the mass ratio of the surfactant to the dianhydride is 1:(20-500); The surfactant is selected from at least one of silicone oil DC-193, silicone oil AK-8805 and silicone oil silok2008N.
5. The method for preparing a rigid open-cell polyimide foam according to claim 1, characterized in that: In step (4), the absolute pressure of the vacuum condition is 0-0.02 MPa, the temperature of the heating condition is 50-80° C., and the diameter of the sieve plate for sieving and crushing is 5-500 mesh.
6. The method for preparing a rigid open-cell polyimide foam according to claim 1, characterized in that: In step (5), the absolute pressure of the vacuum condition is 0 to 0.01 MPa, the temperature of the heating condition is 80 to 200° C., and the time is 0 to 1 h.
7. The method for preparing a rigid open-cell polyimide foam according to claim 1, characterized in that: In step (6), the heating condition is a temperature of 310 to 370° C. and a time of 0.5 h to 1 h.
8. A rigid open-cell polyimide foam, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 7.
9. The rigid open-cell polyimide foam according to claim 8, characterized in that: The density of the rigid open-cell polyimide foam material is 25-80 kg / m 3 The opening rate is 90-99%.