High-temperature-resistant PMR type polyimide composite material and preparation method thereof

Abstract

The invention relates to a high-temperature-resistant PMR type polyimide composite material and a preparation method thereof.The preparation method comprises the steps that firstly, prepreg serves as a surface layer laying layer, dry fibers serve as a core layer laying layer to prepare a prefabricated body, then molten thermosetting polyimide resin is injected, and preliminary curing is conducted; and then carrying out thermocuring treatment to enable the porosity to be less than or equal to 1.45%, so as to obtain the high-temperature-resistant PMR type polyimide composite material, namely the high-temperature-resistant PMR type polyimide composite material. Wherein the prepreg is prepared from a monomer mixture solution of fiber impregnated PMR type polyimide resin. Compared with the prior art, the forming manufacturability of the composite material is effectively improved, the blank of the high-temperature-resistant PMR type polyimide resin in the fields of complex components and large-thickness components is filled up, and the internal porosity of the composite material is effectively reduced, so that the overall performance of the composite material is improved, and the application scene of the composite material in the aerospace field is enriched.

Description

Technical Field

[0001] The invention belongs to the field of high-temperature resistant resin-based composite material molding, and relates to a high-temperature resistant PMR type polyimide composite material and a preparation method thereof. Background Art

[0002] Polyimide composite materials have good mechanical and electrical properties, high specific strength and specific stiffness, excellent thermal and chemical stability, small thermal expansion coefficient, strong solvent resistance, high dimensional stability, and are easy to form components with complex shapes. They are one of the most widely used structural resin-based composite materials in aircraft engines and have been widely used in engine nozzle adjustment plates, boost ducts, engine high-pressure cooling pipes, antenna covers, outer casings, and ultra-high-speed fan blades.

[0003] In the 1970s, NASA's Lewis Research Center in the United States developed PMR (Polymerization of Monomer Reactants) technology to improve the molding process of polyimides. This technology addressed the previous challenges of heat-resistant aromatic heterocyclic resins, which were insoluble and difficult to process. It became a key method for preparing thermoset polyimide composites. To increase the operating temperature of composites, NASA and the Air Force Materials Laboratory subsequently developed a variety of improved PMR polyimide resins, such as LaRC-160, LaRC-RP46, PMR-II-50, V-CAP, AFR-700B, and DMBZ-15, with maximum temperature resistance exceeding 400°C. However, high-temperature polyimide resins have a rigid molecular chain structure and a high minimum melt viscosity, typically exceeding several thousand Pa.s, resulting in a narrow processing window. Furthermore, small molecular byproducts released during the curing process can easily create porosity defects within the composite material, reducing the molding processability of polyimide composites, especially for thick components, and hindering their expanded engineering applications.

[0004] CN110588022A discloses a method for improving the thermal oxidative stability of RTM-molded polyimide composite materials. This method uses the RTM process to prepare the composite material, and the resin matrix component of the composite material varies with the thickness gradient. That is, the surface matrix component of the composite material is a thermosetting polyimide resin A with a designed molecular weight between 1500 and 10000 g / mol, and the core layer matrix is a thermosetting polyimide resin B with a minimum rheological viscosity below 1 Pa·s. This method not only allows the composite material to be prepared by the RTM process, but also effectively improves the thermal oxidative stability of the composite material, thereby extending the life of the composite material. However, this existing technology relies on gradient resin viscosity differences to achieve RTM filling, and only improves thermal oxidative stability through physical protection of the high molecular weight resin on the surface. The aliphatic hydrocarbon structure of the core layer resin B still has thermal stability shortcomings.

[0005] Existing polyimide composite components are mainly studied for the molding process of simple thin-walled structures. The molding process mainly adopts a single molding method, such as autoclave molding, compression molding or resin transfer molding to prepare components. There are no reports on the molding process of polyimide composites for thick components. Autoclave molding has the characteristics of uniform and stable molding pressure and temperature, and the vacuum bag maintains a vacuum negative pressure at all times, which can promptly remove the small molecular by-products produced by the polyimide resin reaction. Compression molding is one of the most widely used molding processes for preparing composite materials in the aerospace field. However, for high-rigidity and high-temperature resistant polyimide composite materials, it is difficult to release the internal small molecules during the preparation of thick products, which easily forms void defects in the product. Summary of the Invention

[0006] The purpose of the present invention is to provide a high-temperature resistant PMR type polyimide composite material and a preparation method thereof, which is used to solve the problems of complex structure, difficult processing and forming of large-thickness components, and many hole defects in the preparation of high-temperature resistant PMR type polyimide composite materials.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A first aspect of the present invention provides a method for preparing a high-temperature resistant PMR type polyimide composite material, comprising the following steps:

[0009] S1: A preform is formed by laying prepreg as a surface layer and dry fiber as a core layer, and then injecting molten thermosetting polyimide resin and preliminarily curing it; wherein the prepreg is prepared by impregnating the fiber with a monomer mixture solution of PMR type polyimide resin;

[0010] S2: further performing heat curing treatment on the material preliminarily cured in S1 so as to make the porosity ≤1.45%, thereby obtaining a high temperature resistant PMR type polyimide composite material.

[0011] In some specific embodiments, in step S1, the prepreg is a fiber-impregnated PMR polyimide resin with a resin mass fraction of 40% to 60%, preferably 40% and 55%. The preparation method comprises: adding 4-phenylacetylene phthalic anhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride to ethanol, refluxing and esterifying for 4 hours at a reflux temperature of 78 to 82°C; subsequently adding 3,4'-diaminodiphenyl ether and continuing the reaction for 6 hours to obtain a transparent PMR polyimide resin; the molar ratio of 4-phenylacetylene phthalic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 3,4'-diaminodiphenyl ether is 2:2:3 or 2:4:5, corresponding to molecular weights of 1500 g / mol and 3000 g / mol, respectively.

[0012] In some specific embodiments, in step S1, the PMR polyimide resin has a temperature resistance rating greater than 400° C. and a molecular weight of 1500 to 5000 g / mol.

[0013] In some specific embodiments, in step S1, the PMR polyimide resin is selected from one or a blend of two or more of phenylethene-terminated polyimide, norbornene-terminated polyimide, or ethynyl-terminated polyimide.

[0014] In some preferred embodiments, the molar ratio of 4-phenylacetylene phthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 3,4'-diaminodiphenyl ether is 2:2:3 or 2:4:5, and the molecular weights of the PMR polyimide resin obtained corresponding to the two molar ratios are 1500 g / mol and 3000 g / mol.

[0015] In some specific embodiments, in step S1, the dry fiber is selected from at least one of carbon fiber, glass fiber, quartz fiber, polyimide fiber or aramid fiber.

[0016] In some preferred embodiments, the dry fibers are carbon fibers and / or glass fibers commonly used in composite components of aircraft engines.

[0017] In some specific embodiments, in step S1, the ratio of the number of layers of the surface layer to the number of layers of the core layer is (1-8):(26-28), and the total number of layers is 27-33.

[0018] In some preferred embodiments, in step S1, the ratio of the number of layers of the surface layer to the number of layers of the core layer is 2:28 to 4:26, and the total number of layers is 30.

[0019] In some specific embodiments, in step S1, the thermosetting polyimide resin is an asymmetric biphenyltetracarboxylic acid dianhydride polyimide terminated with 4-phenylacetylene phthalic anhydride, the resin melt viscosity is less than 1 Pa·s, suitable for resin transfer molding (RTM), and the melting temperature ranges from 250° C. to 280° C. The preparation method comprises:

[0020] 3,4'-diaminodiphenyl ether was added to DMAc, stirred and dissolved for 30 minutes, 4-phenylacetylene phthalic anhydride and biphenyltetracarboxylic dianhydride were added, and the mixture was reacted for 6 hours. The mixture was then vacuum dried at 150°C to obtain a fusible thermosetting polyimide resin powder.

[0021] In some preferred embodiments, in step S1, before the thermosetting polyimide resin is added, the temperature of the preliminary curing mold used is 250-280°C.

[0022] In some specific embodiments, in step S1, during the preliminary curing, the curing temperature is 320-380°C.

[0023] In some preferred embodiments, in step S1, during the preliminary curing, the curing temperature is 320° C. and 340° C. according to the characteristics of the selected resin.

[0024] The high-temperature resistant PMR polyimide composite material of the present invention uses two resins with similar structures and adopts a two-step molding process. The resin matrix component of the composite material changes gradually with the thickness of the composite material. That is, the matrix component of the surface layer of the composite material is a PMR polyimide resin that is resistant to high temperatures of 400°C, and the matrix of the core layer is a thermosetting polyimide resin that is suitable for RTM molding and has a minimum melt viscosity of less than 1 Pa·s. This allows the surface of the composite material to withstand high temperatures above 400°C while effectively improving the molding processability of the composite material, providing a new method for preparing high-temperature resistant composite materials with complex structures and large thicknesses.

[0025] The present invention can be applied to high-tech fields such as aviation engines, aviation, and aerospace.

[0026] In some specific embodiments, in step S2, in the heat curing treatment, the heat curing treatment temperature is 340-400°C, the heat curing treatment pressure is 3-15 MPa, the heat curing treatment time is 30 min-2 h, and the heat curing treatment heating rate is 2-8°C / min.

[0027] In some preferred embodiments, in step S2, during the heat curing treatment, the heat curing treatment temperature is 380°C, the heat curing treatment pressure is 5 MPa, the heat curing treatment time is 1 hour, and the heat curing treatment heating rate is 3°C / min.

[0028] In some specific embodiments, in step S1, the discharge temperature of the preliminary solidification is below 50-150°C, and then step S2 is performed.

[0029] In some preferred embodiments, in step S1, the discharge temperature of the preliminary solidification is 140°C.

[0030] A second aspect of the present invention provides a high-temperature-resistant PMR-type polyimide composite material prepared by the above-described preparation method. This material significantly reduces porosity (less than 1.45%) through the synergistic curing of the prepreg surface and core resins, while also addressing the lack of fluidity associated with traditional PMR resins in complex components. Not only does it reduce thermal oxidation weight loss by 56% to 71%, but it also accommodates a wider curing window of 340 to 400°C, providing a more reliable solution for large, complex components in the aerospace industry.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention discloses a method for improving the molding processability of high-temperature resistant PMR polyimide composite materials. The method provided by the present invention solves the problems of complex structure, difficult molding of thick components, and frequent porosity defects in the preparation of high-temperature resistant PMR polyimide composite materials. By selecting two resins with similar structures and adopting a two-step molding process, combining the advantages of both RTM and compression molding, the molding processability of the composite material is effectively improved. This method fills the gap in the application of high-temperature resistant PMR polyimide resins in complex and thick components, effectively reduces the internal porosity of the composite material, thereby improving the overall performance of the composite material and enriching its application scenarios in the aerospace field. DETAILED DESCRIPTION

[0033] On the whole, the present invention adopts a two-step molding process, and the resin matrix component of the composite material changes with the thickness gradient, that is, the matrix component of the surface layer of the composite material is a PMR-type polyimide resin A that is resistant to high temperatures of 400°C, and the core layer matrix is a thermosetting polyimide resin B that is suitable for RTM molding with a minimum melt viscosity of less than 1Pa·s. The two-step molding process is as follows: the first step is to place a preform with a surface layer of prepreg containing resin A and a core layer of dry carbon fiber into an RTM mold, infuse resin B, and preliminarily cure the preform; the second step is to place the preform into a molding mold for post-processing and curing. The method provided by the present invention effectively improves the molding processability of the composite material while making the surface of the composite material resistant to high temperatures above 400°C, and provides a new method for preparing high-temperature resistant composite materials with complex structures and large thicknesses. The present invention can be applied to high-tech fields such as aircraft engines, aviation, and aerospace.

[0034] Compared to the technical solution of CN110588022A, the present invention uses a PMR-type polyimide resin as the surface prepreg matrix. Through a specific monomer ratio (such as the molar ratio of 4-phenylacetylene phthalic anhydride to biphenyltetracarboxylic dianhydride), a high-temperature-resistant resin with a molecular weight of 1500 to 5000 g / mol (temperature resistance level >400°C) is formed. Compared with the surface resin A (molecular weight 1500 to 10000 g / mol) in Reference 1, its molecular structure is more precisely controllable, and a two-step molding process (RTM combined with molding) achieves efficient molding of complex components and thick parts. Reference 1 relies on gradient resin viscosity differences to achieve RTM filling, but the present invention significantly reduces porosity (<1.45%) through the coordinated curing of the prepreg surface and core layer resins (such as the combination of initial curing and high-temperature hot pressing curing), while solving the problem of insufficient fluidity of traditional PMR resins in complex components. In terms of comprehensive performance improvement, the present invention achieves both excellent high temperature resistance and compactness of the composite material by designing a high resin content of 40-60% in the surface prepreg and high pressure treatment (3-15MPa) in the thermal curing stage. However, Comparative Document 1 only improves the thermal oxidation stability through the physical protection of the surface high molecular weight resin, and the aliphatic hydrocarbon structure of its core layer resin B still has a thermal stability shortcoming. In contrast, the PMR resin system of the present invention forms a more stable cross-linked network at high temperature through the design of phenylacetylene end-capping and asymmetric biphenyltetracarboxylic dianhydride structure, which not only reduces the thermal oxidation weight loss rate by 56% to 71% (see example data), but also can adapt to a wider curing window of 340-400°C, providing a more reliable solution for large-scale complex components in the aerospace field.

[0035] The present invention is described in detail below with reference to specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0036] The following are more detailed implementation cases, which further illustrate the technical solutions of the present invention and the technical effects that can be obtained.

[0037] In the following examples, unless otherwise specified, raw materials, reagents or processing techniques are all conventional commercially available products or conventional processing techniques in the art.

[0038] Example 1:

[0039] A high-temperature resistant PMR polyimide composite material, the preparation method of which comprises the following steps:

[0040] S1: Layer laying and initial curing

[0041] S1-1: A composite preform is prepared by paving. The surface of the preform is formed by paving two layers of prepreg. The thickness of each prepreg layer is 0.15-0.17 mm, and the paving density is 450-510 g / m 2 The prepreg is prepared by impregnating carbon fiber with a monomer mixture solution of PMR polyimide resin A, with a resin content of 40wt%; the PMR polyimide resin A is a 3,4'-ODA-type polyimide terminated with 4-phenylacetylene phthalic anhydride. The preparation method is as follows: 4-phenylacetylene phthalic anhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride are added to ethanol, and refluxed for esterification for 4 hours at a reflux temperature of 78-82°C; 3,4'-diaminodiphenyl ether is then added and the reaction is continued for 6 hours to obtain a transparent PMR polyimide resin; the molar ratio of 4-phenylacetylene phthalic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 3,4'-diaminodiphenyl ether is 2:2:3 or 2:4:5, corresponding to molecular weights of 1500g / mol and 3000g / mol, respectively.

[0042] The core layer is made of 28 layers of dry carbon fiber, with a thickness of 0.08 to 0.1 mm and a density of 288180 to 360 g / m 2 ;

[0043] S1-2: Place the preform in a 4 mm mold and heat the mold to 260-280°C;

[0044] S1-3: Melting a thermosetting polyimide resin B and injecting it into the mold of step S1-2; wherein the thermosetting polyimide resin B is an asymmetric biphenyltetracarboxylic dianhydride-type polyimide terminated with 4-phenylacetylene phthalic anhydride, and is prepared by adding 3,4'-diaminodiphenyl ether to DMAc, stirring and dissolving for 30 minutes, adding 4-phenylacetylene phthalic anhydride and biphenyltetracarboxylic dianhydride, reacting for 6 hours, and then vacuum drying at 150°C to obtain a fusible thermosetting polyimide resin powder having a molecular weight of 750 g / mol and a resin melt viscosity of less than 1 Pa·s;

[0045] S1-4: heating the mold in step S1-3 to 320°C and maintaining the temperature for 20 to 30 minutes to preliminarily solidify the composite material;

[0046] S2: Post-curing molding

[0047] S2-1: Cool the mold in step S1-4 to 140°C, remove it, and then place it in a molding machine for post-curing molding. The post-curing molding temperature is 380°C, the post-curing molding pressure is 5 MPa, the post-curing molding time is 1 hour (holding period), and the post-curing molding heating rate is 3°C / min;

[0048] S2-2: After cooling the molding machine in step S2-1, the mold is removed to obtain a 4 mm composite material.

[0049] Composite samples were cut to 80 mm long by 10 mm wide and tested for porosity and flexural strength. The porosity test method was based on ASTM 2734-09, and the flexural strength test method was based on GB / T 9341-2008. The test results are shown in Table 1.

[0050] Example 2:

[0051] A high-temperature resistant PMR polyimide composite material, the preparation method of which is different from that of Example 1, except that: in step S1-1, the surface layer includes 4 layers of prepreg, and the core layer includes 26 layers of dry carbon fiber.

[0052] The rest is the same as in Example 1.

[0053] Example 3:

[0054] A high-temperature resistant PMR polyimide composite material, the preparation method of which is different from that of Example 1, except that: in step S1-1, the prepreg is prepared by impregnating glass fiber with a monomer mixture solution of PMR polyimide resin A, the glass fiber thickness is 0.08-0.1 mm, and the paving density is 288-360 g / m 2 The glass fiber manufacturer is Jiangsu Tianniao, and the model is C-GQ3522.

[0055] The rest is the same as in Example 1.

[0056] Example 4:

[0057] A high-temperature resistant PMR polyimide composite material is prepared by a method similar to that of Example 1, except that in step S1-1, the molecular weight of the PMR polyimide resin A is 3000 g / mol, and in step S1-4, the curing temperature of the composite material is 340°C.

[0058] The rest is the same as in Example 1.

[0059] Example 5:

[0060] A high-temperature resistant PMR polyimide composite material, the preparation method of which is different from that of Example 1, except that in step S1-1, the prepreg is prepared by impregnating carbon fibers with a monomer mixture solution of PMR polyimide resin A, with a resin content of 55 wt%.

[0061] The rest is the same as in Example 1.

[0062] Comparative Example 1:

[0063] A high-temperature resistant PMR polyimide composite material, the preparation method of which is different from that of Example 1, except that in step S1-1, the preform only contains 30 layers of prepreg and does not contain dry carbon fiber.

[0064] The rest is the same as Example 1.

[0065] Comparative Example 2:

[0066] A high-temperature resistant PMR polyimide composite material, the preparation method of which is different from that of Example 1, except that in step S1-1, the preform only contains 30 layers of dry carbon fibers and does not contain prepreg.

[0067] The rest is the same as in Example 1.

[0068] Application examples:

[0069] Using the method proposed in the present invention for improving the thermal oxidative stability of RTM-molded polyimide composites, six composite materials were prepared using Examples 1-5 and Comparative Example 1. The thermal weight loss rates of the six composite materials after 200 hours in air at 350°C are shown in Table 1 to illustrate the technical advantages of the present invention.

[0070] Using the method proposed in the present invention for improving the molding processability of high-temperature-resistant PMR polyimide composite materials, a total of six composite materials were prepared through Examples 1-5 and Comparative Example 1. Porosity and flexural strength test data for the six composite materials are also provided to illustrate the technical advantages of the present invention. The results are shown in Table 2.

[0071] Table 1 Thermal weight loss of the composite materials in comparative examples and examples after being kept in air at 350°C for 200 hours

[0072] sample Thermal weight loss rate (%) Comparative Example 1 7.2 Comparative Example 2 8.1 Example 1 4.7 Example 2 4.6 Example 3 5.2 Example 4 5.9 Example 5 5.3

[0073] Table 2 Porosity and flexural strength of composite materials in comparative examples and examples

[0074]

[0075]

[0076] Compared to the comparative examples, the method provided by the present invention significantly reduces the porosity of high-temperature-resistant PMR polyimide composites and improves their mechanical properties. For example, the porosity of the polyimide composites in Examples 1 and 2 was reduced by 37% and 28%, respectively, compared to the comparative examples, while their flexural properties were improved by 17% and 13%, respectively. This improves both the composite's formability and overall performance.

[0077] Comparative Example 3

[0078] Replace the two-step curing process with a one-step process.

[0079] The preparation method differs from that of Example 1 only in that the preliminary curing steps S1-4 are omitted, and high-temperature curing is performed directly. The post-molding curing (step S2) is eliminated, and a single curing process is adopted: the mold is directly heated to 380°C and maintained for 1 hour at a pressure of 0.1 MPa (no autoclaving).

[0080]

[0081] It can be analyzed that one-step curing leads to insufficient resin flow, poor interface bonding between the core layer and the surface layer, a significant increase in porosity, and a decrease in bending strength; at the same time, the resin is not completely cross-linked at high temperatures, and the thermal stability deteriorates.

[0082] Comparative Example 4

[0083] Eliminate heat curing and high pressure treatment

[0084] Preparation method: Compared with Example 1, the only difference is that the molding high pressure (5 MPa) in S2-1 is cancelled, and only normal pressure (0.1 MPa) is maintained in the post-curing stage.

[0085]

[0086] It can be analyzed that the lack of high-pressure treatment leads to insufficient resin density, increased porosity, decreased interlayer bonding strength, increased microcracks inside the composite material, and significantly reduced mechanical properties.

[0087] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature resistant PMR type polyimide composite material, characterized in that: The following steps are involved: S1: A preform is formed by laying prepreg as a surface layer and dry fiber as a core layer, and then injecting molten thermosetting polyimide resin and preliminarily curing it; wherein the prepreg is prepared by impregnating the fiber with a monomer mixture solution of PMR type polyimide resin; S2: further performing heat curing treatment on the material preliminarily cured in S1 so as to make the porosity ≤1.45%, thereby obtaining a high temperature resistant PMR type polyimide composite material.

2. The method for preparing the high temperature resistant PMR type polyimide composite material according to claim 1, characterized in that: In step S1, the prepreg is a fiber impregnated PMR polyimide resin with a resin mass fraction of 40-60%. The preparation method of the prepreg includes: Add 4-phenylacetylene phthalic anhydride and 3,3',4,4'-benzophenone tetracarboxylic dianhydride to ethanol and reflux for esterification for 4 hours at a reflux temperature of 78-82°C; Then, 3,4'-diaminodiphenyl ether was added and the reaction was continued for 6 hours to obtain a transparent PMR type polyimide resin; The PMR type polyimide resin has a temperature resistance grade greater than 400° C. and a molecular weight of 1500 to 5000 g / mol.

3. The method for preparing the high temperature resistant PMR type polyimide composite material according to claim 2, characterized in that: In step S1, the molar ratio of 4-phenylacetylene phthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 3,4'-diaminodiphenyl ether is 2:2:3 or 2:4:5, and the molecular weights of the PMR polyimide resin obtained corresponding to the two molar ratios are 1500 g / mol and 3000 g / mol.

4. The method for preparing the high temperature resistant PMR type polyimide composite material according to claim 2, characterized in that: In step S1, the PMR polyimide resin is selected from one or a blend of two or more of phenylethene-terminated polyimide, norbornene-terminated polyimide or ethynyl-terminated polyimide.

5. The method for preparing the high temperature resistant PMR type polyimide composite material according to claim 2, characterized in that: In step S1, the dry fiber is selected from at least one of carbon fiber, glass fiber, quartz fiber, polyimide fiber or aramid fiber.

6. The method for preparing the high temperature resistant PMR type polyimide composite material according to claim 1, characterized in that: In step S1, the ratio of the number of layers of the surface layer to the number of layers of the core layer is (1-8):(26-28), and the total number of layers is 27-33.

7. The method for preparing the high temperature resistant PMR type polyimide composite material according to claim 1, characterized in that: In step S1, the thermosetting polyimide resin is an asymmetric biphenyltetracarboxylic acid dianhydride polyimide terminated with 4-phenylethynylphthalic anhydride, the resin melt viscosity is less than 1 Pa·s, and the melting temperature ranges from 250 to 280° C. The preparation method comprises: 3,4'-diaminodiphenyl ether was added to DMAc, stirred and dissolved for 30 minutes, 4-phenylacetylene phthalic anhydride and biphenyltetracarboxylic dianhydride were added, and the mixture was reacted for 6 hours. The mixture was then vacuum dried at 150°C to obtain a fusible thermosetting polyimide resin powder.

8. The method for preparing the high temperature resistant PMR type polyimide composite material according to claim 1, characterized in that: In step S1, during the preliminary curing, the curing temperature is 320-380°C; In step S1, the discharge temperature of the preliminary solidification is below 50-150°C, and then step S2 is performed.

9. The method for preparing a high temperature resistant PMR type polyimide composite material according to claim 1, characterized in that: In step S2, in the thermal curing treatment, the thermal curing treatment temperature is 340-400°C, the thermal curing treatment pressure is 3-15 MPa, the thermal curing treatment time is 30 min-2 h, and the thermal curing treatment heating rate is 2-8°C / min.

10. A high-temperature resistant PMR polyimide composite material prepared by the preparation method according to any one of claims 1 to 9.

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