Hard polyimide foam prefabricated part and splicing method thereof
By preparing and splicing rigid polyimide foam prefabricated components, the problems of poor splicing strength and joint temperature resistance were solved, enabling the application of large-size foam boards in high-temperature environments, and achieving high strength and good thermal performance consistency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-24
- Publication Date
- 2026-03-31
AI Technical Summary
Existing rigid polyimide foam materials suffer from insufficient splicing strength and poor temperature resistance at the joints during the splicing process, which limits the application of large-size flat composite panels.
A precursor solution was prepared using aromatic dianhydride, aromatic diamine, and end-capping agent. Polyester ammonium salt powder was obtained by drying and pulverizing, and then foamed into rigid polyimide foam blanks. Polyimide-based adhesive was applied to the splicing end faces, and the integral structure was formed by pressure bonding and heat treatment. The adhesive with the same composition as the foam body was selected to improve the bonding strength and thermal performance consistency.
The fabrication of large-size rigid polyimide foam boards has been achieved, which can maintain the consistency of splicing strength and thermal performance in high-temperature environments. They are suitable for large-area and special structural applications, and their mechanical strength and sealing performance are enhanced by serrated and other shape designs.
Smart Images
Figure CN121756613A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a rigid polyimide foam preform and its splicing method, belonging to the field of polymer materials technology. Background Technology
[0002] Polyimide foam is an important type of polymeric foam material. It possesses excellent flame retardant properties, outstanding high-temperature resistance, and excellent resistance to low-temperature brittleness, and has been widely used internationally as a thermal insulation and noise reduction material. Rigid polyimide foam is a type of polyimide foam that can be used as a core material in environments requiring high-temperature strength. Currently, high-temperature resistant rigid foam materials with good oxidation resistance and maintaining good compressive strength can be prepared using the end-capped RTM resin method. However, rigid polyimide foam requires high preparation temperatures, and when foaming large sizes, the internal heating is not uniform, resulting in a small effective planar size after foaming, which cannot meet the needs of large-area overall thermal insulation areas. In practical applications, due to the shape and size limitations of foam materials, it is often necessary to splice multiple pieces of foam material together to meet specific design requirements. Existing splicing methods often have the following problems: (1) When bonding rectangular foam boards, the edge contact area is small, resulting in insufficient bonding strength; (2) When selecting adhesives, other adhesives with different compositions from the foam body have poor temperature resistance and cannot withstand the composite molding temperature together with the foam. Therefore, the application of large-size flat composite boards with rigid polyimide foam as the core material is limited. Summary of the Invention
[0003] The purpose of this invention is to overcome the above-mentioned defects and provide a rigid polyimide foam prefabricated component and its splicing method, which solves the technical problems of insufficient splicing strength and poor temperature resistance of joints in the existing polyimide foam splicing process. The rigid polyimide foam splicing method of this invention has the advantages of simple implementation, high splicing strength, and matching performance between adhesive and foam body.
[0004] The above-mentioned objectives of the present invention are mainly achieved through the following technical solutions:
[0005] A method for splicing rigid polyimide foam prefabricated components includes:
[0006] S1. A precursor solution was prepared using aromatic dianhydride, aromatic diamine, and a capping agent;
[0007] S2. The precursor solution is dried and pulverized to obtain polyester ammonium salt powder;
[0008] S3. The polyester ammonium salt powder is heated and pressurized to foam, thereby obtaining a rigid polyimide foam blank.
[0009] S4. Process the rigid polyimide foam blank into a foam board with splicable edges;
[0010] S5. Apply polyimide-based adhesive to the splicing end face of the splicable part of the foam board. The polyimide-based adhesive is the precursor solution in step S1, or the mixture of polyester ammonium salt powder and tetrahydrofuran in step S2.
[0011] S6. Assemble multiple foam boards according to the predetermined size, and apply pressure to make the spliced parts fit together to form an integral structure;
[0012] S7. Perform heat treatment to cure the polyimide-based adhesive at the splicing parts.
[0013] In the above-mentioned method for splicing rigid polyimide foam preforms, the method for preparing the precursor solution using aromatic dianhydride, aromatic diamine, and end-capping agent in step S1 includes:
[0014] S1.1 Add aromatic dianhydride and end-capping agent to solvent and heat at 50-70°C for 1-4 hours;
[0015] S1.2 is added with an aromatic diamine and heated at 50–70°C for 3–8 hours to obtain a precursor solution;
[0016] S1.3 Add a foam stabilizer to the precursor solution.
[0017] The molar ratio of the aromatic dianhydride, the aromatic diamine, and the capping agent is 1–6:1–6:2;
[0018] The mass fraction of the foam stabilizer is 0.5%-6% of the solid content of the precursor solution.
[0019] In the above-mentioned method for splicing rigid polyimide foam preforms, the percentage of the total mass of aromatic dianhydride, aromatic diamine and end-capping agent in the precursor solution is 40-70%.
[0020] In the above-mentioned method for splicing rigid polyimide foam preforms, the solvent in step S1.1 is a mixture of tetrahydrofuran and methanol, and the mass ratio of tetrahydrofuran to methanol is 3 to 6:1; the foam stabilizer in step S1.3 is a silicone oil foam stabilizer.
[0021] In the above-mentioned splicing method of rigid polyimide foam preforms, the aromatic dianhydride is one or a combination of several of the following: 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, bisphenol A type diphenyl ether dianhydride, or 2,3',4,4'-biphenyl tetracarboxylic dianhydride.
[0022] The aromatic diamine is one or a combination of several of the following: 1,4-p-phenylenediamine, 1,3-m-phenylenediamine, 4,4-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-bis(3-aminophenoxy)benzophenone, 4,4'-bis(3-aminophenoxy)diphenyl sulfone, 1,3-bis(4'-aminophenoxy)benzene, or 2,2'-bis[4-(4-aminophenoxyphenyl)]propane;
[0023] The capping agent is one or a combination of several of 5-norbornene-2,3-dianhydride, 4-phenylacetylene phthalic anhydride, or 4-acetylene phthalic anhydride.
[0024] In the above-mentioned method for splicing rigid polyimide foam preforms, in step S2, the precursor solution is first dried in an oven at 70-100℃ for 0.2-2 hours, and then dried in an oven at 190℃-250℃ for 0.5-4 hours.
[0025] In the above-mentioned splicing method of rigid polyimide foam prefabricated parts, in step S3, the heating and pressurizing foaming parameters are: pressure 0.01~0.3MPa, heating process is programmed temperature control, 240~390℃, and total foaming time is 8~24h.
[0026] In the above-mentioned splicing method of rigid polyimide foam prefabricated parts, the thickness of the foam board in step S4 is 5-25mm, the length and width are 100-700mm, and the perimeter splicable parts are in shapes that can fit together or interlock, specifically serrated, wavy, trapezoidal or rectangular.
[0027] In the above-mentioned splicing method of rigid polyimide foam prefabricated parts, when the splicing shape is serrated, the length and width of the serrations are 15mm-45mm, and the serration angle is 30-60°.
[0028] In the above-mentioned method for splicing rigid polyimide foam preforms, the mass ratio of the polyester ammonium salt powder to the tetrahydrofuran mixture in step S5 is 100:5 to 25.
[0029] In the above-mentioned method for splicing rigid polyimide foam preforms, in step S6, the pressure applied after splicing is either by vacuum pressurization or by mold pressurization, and the pressurization and heat treatment are carried out simultaneously; in step S7, the heat treatment temperature is 320℃~380℃, and the treatment time is 1~5h.
[0030] A rigid polyimide foam prefabricated component is obtained by the above-mentioned splicing method.
[0031] In the aforementioned rigid polyimide foam preforms, the average density of the rigid polyimide foam preforms is 80–200 kg / m³. 3 Glass transition temperature Tg ≥370℃, thermal decomposition temperature T d5％ At ≥550℃, the room temperature tensile shear strength at the splice joint is ≥3MPa.
[0032] Compared with the prior art, the present invention has at least the following beneficial effects:
[0033] (1) This invention achieves the preparation of large-size rigid polyimide foam boards through optimized design of prefabricated materials, splicing process and splicing materials. Furthermore, the splicing strength and thermal performance are ensured by the shape design of the splicing joint and the polyimide-based adhesive with the same composition as the foam body. This enables the spliced foam board to withstand CNC machining and hot bending and can be used in high-temperature environments of 300°C and above. Large-size foam boards can be obtained through splicing to meet the needs of large-area and special structure applications.
[0034] (2) The adhesive used in the splicing area of the present invention is the same as the composition of the foam body, which can ensure the bonding strength. At the same time, the thermal properties of the bonding part are similar to those of the foam body, which can meet the molding requirements of composite materials at high temperature.
[0035] (3) In the embodiments of the present invention, the splicing part can be serrated, wavy, trapezoidal or rectangular, which is simple to process and can be achieved by conventional mechanical processing methods, reducing the complexity of the process and cost, and is suitable for mass production.
[0036] (4) In the embodiments of the present invention, the preferred sawtooth splicing structure can provide a larger bonding area and mechanical interlocking ability during bonding, thereby significantly enhancing the mechanical strength of the joint and being able to withstand the stress generated by subsequent machining, hot bending or other processing methods; due to the interlocking of the sawtooth structure, it can effectively prevent gas or liquid leakage and improve the sealing performance of the splicing. Attached Figure Description
[0037] Figure 1 The serrated polyimide foam prefabricated board in Embodiment 1 of the present invention;
[0038] Figure 2 This is a schematic diagram of the spliced effect in Embodiment 1 of the present invention;
[0039] Figure 3 This is a schematic diagram of the tensile specimen in Embodiment 1 of the present invention;
[0040] Figure 4 This is a schematic diagram of the arc-shaped foam board prepared in Embodiment 2 of the present invention;
[0041] Figure 5 This is a schematic diagram of the isosceles triangular sawtooth pattern with a width of 30mm and a height of 30mm in Embodiment 5 of the present invention. Detailed Implementation
[0042] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:
[0043] This invention provides a method for splicing rigid polyimide foam prefabricated components, specifically including the following steps:
[0044] S1. A precursor solution is prepared using aromatic dianhydride, aromatic diamine, and a capping agent. The specific method includes the following steps:
[0045] S1.1 Add aromatic dianhydride and end-capping agent to solvent and heat at 50-70°C for 1-4 hours; in an optional embodiment, the solvent is a mixture of tetrahydrofuran and methanol, with a mass ratio of tetrahydrofuran to methanol of 3-6:1.
[0046] After the S1.2 solution becomes clear, an aromatic diamine is added, and the mixture is heated at 50–70°C for 3–8 hours to obtain a precursor solution. In one optional embodiment, the molar ratio of aromatic dianhydride, aromatic diamine, and capping agent is 1–6:1–6:2. In another optional embodiment, the percentage of the total mass of aromatic dianhydride, aromatic diamine, and capping agent in the precursor solution is 40–70%.
[0047] S1.3 Add an appropriate amount of foam stabilizer to the precursor solution. In an optional embodiment, the foam stabilizer is a silicone oil foam stabilizer, and its mass fraction is 0.5%-6% of the solid content of the precursor solution.
[0048] In one optional embodiment, the aromatic dianhydride is one or a combination of several of the following: 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, bisphenol A type diphenyl ether dianhydride, or 2,3',4,4'-biphenyl tetracarboxylic dianhydride.
[0049] In one optional embodiment, the aromatic diamine is one or a combination of several of the following: 1,4-p-phenylenediamine, 1,3-m-phenylenediamine, 4,4-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-bis(3-aminophenoxy)benzophenone, 4,4'-bis(3-aminophenoxy)diphenyl sulfone, 1,3-bis(4'-aminophenoxy)benzene, or 2,2'-bis[4-(4-aminophenoxyphenyl)]propane;
[0050] In one optional embodiment, the capping agent is one or a combination of several of 5-norbornene-2,3-dianhydride, 4-phenylacetylene phthalic anhydride, or 4-acetylene phthalic anhydride.
[0051] S2. The precursor solution is dried and pulverized to obtain polyester ammonium salt powder; in an optional embodiment, the precursor solution is first dried in an oven at 70-100℃ for 0.2-2h, and then the precursor is dried in an oven at 190℃-250℃ for 0.5-4h.
[0052] S3. The polyester ammonium salt powder is placed in a hot autoclave and heated and pressurized to foam, thereby obtaining a rigid polyimide foam blank. In an optional embodiment, the heating and pressurizing foaming parameters are as follows: pressure 0.01~0.3MPa, heating process is programmed temperature control, 240~390℃, and total foaming time is 8~24h.
[0053] S4. Process the rigid polyimide foam blank into prefabricated parts to obtain a foam board with splicable parts (splicable shape) around the perimeter.
[0054] In one optional embodiment, the prefabricated foam board is a flat plate with a thickness of 5-25mm and a length and width of 100-700mm, or other larger dimensions. Its four sides are serrated, wavy, trapezoidal, rectangular, or other interlocking shapes that can be joined together. When the joining area is serrated, the serrated shape is preferably an isosceles triangle with its base connected to the flat plate. The base and height of the isosceles triangle are 15mm-45mm, and the apex angle is 30-60°.
[0055] S5. Apply polyimide-based adhesive to the splicing end faces of the splicable parts of the foam board. For example, if the splicable parts are serrated, apply polyimide-based adhesive to the serrations. In an optional embodiment, the polyimide-based adhesive is the precursor solution prepared in step S1, or a paste made by mixing the precursor powder prepared in step S2 with tetrahydrofuran.
[0056] S6. Assemble multiple foam boards according to the predetermined size, apply pressure to make the spliced parts interlock to form an integral structure, and perform heat treatment on the whole to cure the polyimide adhesive at the joints.
[0057] In one optional embodiment, the pressure is applied after splicing by vacuum pressurization or mold pressurization, and the pressurization and heat treatment are carried out simultaneously; the temperature of the overall heat treatment is 320℃~380℃, and the treatment time is 1~5h.
[0058] This invention also provides a rigid polyimide foam board, obtained by splicing the above-mentioned rigid polyimide foam prefabricated components, wherein the average density of the polyimide foam is 80-200 kg / m³. 3 Glass transition temperature T g ≥370℃, thermal decomposition temperature T d5％ ≥550℃. The room temperature tensile shear strength at the joint is ≥3MPa, which is much greater than the tensile strength of the foam body.
[0059] Example
[0060] Polyimide foam synthesis:
[0061] Foam 1:
[0062] 6.52 kg of dried 2,3',4,4'-biphenyltetracarboxylic dianhydride and 4.54 kg of norbornene dianhydride were added to a mixed solvent containing 6.51 kg of tetrahydrofuran and 3.43 kg of methanol. The mixture was heated to 60 °C and stirred continuously for 1 h. Then, 3.85 kg of 1,3-m-phenylenediamine was added, and the mixture was stirred at 60 °C for 5 h, followed by cooling to room temperature. The precursor solution was treated by rotary distillation, and the product was then heat-treated at 250 °C for 2.0 h, followed by pulverization to obtain precursor powder. The precursor powder was pressed into a mold to form precursor sheets, which were then foamed at 330 °C for 2 h, cured at 350 °C for 2 h, and subjected to a pressure of 0.09 MPa to obtain norbornene-terminated rigid polyimide foam with a foam density of 130 kg / m³. 3 .
[0063] Bubble 2:
[0064] 5.75 kg of dried 2,3',4,4'-biphenyltetracarboxylic dianhydride and 2.48 kg of phenylethynyl phthalic anhydride were added to a mixed solvent containing 4.90 kg of tetrahydrofuran and 2.36 kg of methanol. The mixture was heated to 60 °C and stirred continuously for 1 h. Then, 2.65 kg of m-phenylenediamine was added, and the mixture was stirred at 60 °C for 5 h, followed by cooling to room temperature. The precursor solution was treated by rotary distillation, and the product was then heat-treated at 280 °C for 1.5 h, followed by pulverization to obtain precursor powder. The precursor powder was pressed into a mold to form precursor sheets, which were then foamed at 350 °C for 2 h, cured at 390 °C for 2 h, and subjected to a pressure of 0.07 MPa to obtain phenylethynyl-terminated rigid polyimide foam with a foam density of 130 kg / m³. 3 .
[0065] Example 1
[0066] Foam 1 is made into a 300mm × 300mm square precast panel with a thickness of 10mm. The edges of the precast panel are isosceles triangular serrations with a base length of 15mm and a height of 15mm. The precursor solution of foam 1 is evenly applied to the serrated surface, the seams are aligned, and it is extruded using a specific mold to ensure that the serrated parts are firmly interlocked. It is then placed in a 330℃ oven for 1.0h, and then heated to 350℃ for 1.0h. After curing, it is removed to obtain the assembled flat foam panel. Figure 1 The image shown is a serrated polyimide foam prefabricated board from Embodiment 1 of the present invention; as shown... Figure 2 The image shown is a schematic diagram of the spliced effect in Embodiment 1 of the present invention.
[0067] Tensile properties tests were performed on samples taken from the butt joint. A schematic diagram of the tensile spline is shown below. Figure 3 As shown, the tensile strength was measured to be 1.45 MPa, and the fracture point was the foam body far from the seam.
[0068] Example 2
[0069] Foam 1 is made into a 300mm × 300mm square precast board with a thickness of 10mm. The edges of the precast board are isosceles triangular serrations with a base length of 15mm and a height of 15mm. Take 100g of the precursor powder of foam 1, add 10g of tetrahydrofuran to it, stir thoroughly to form a paste, and apply it to the serrated surface. Align the seams and press appropriately. Let it dry at room temperature for 30-60 minutes, then put it in a 330℃ oven and heat for 1.0h. Then raise the temperature to 350℃ and heat for 1.0h. After curing, remove it to obtain the spliced flat foam.
[0070] Tensile properties were tested on samples taken from the joint, and the tensile strength was measured to be 1.25 MPa. The fracture point was the foam body.
[0071] The spliced foam is placed on an arc-shaped mold, the mold is closed, and it is treated in a 320℃ oven for 2 hours. Pressure is slowly applied to the upper and lower molds until the curvature of the foam board matches the mold, thus producing a spliced arc-shaped foam board. Figure 4 As shown.
[0072] Example 3
[0073] Foam 1 is made into a 300mm × 300mm square precast panel with a thickness of 10mm. The edges of the precast panel are isosceles triangular serrations with a base length of 15mm and a height of 30mm. Take 100g of the precursor powder of foam 1, add 10g of tetrahydrofuran to it, stir thoroughly to form a paste, and apply it to the serrated surface. Align the seams and press appropriately. Let it dry at room temperature for 30-60 minutes, then put it in a 330℃ oven and heat for 1.0h. Then raise the temperature to 350℃ and heat for 1.0h. After curing, remove it to obtain the spliced flat foam.
[0074] Tensile properties were tested on samples taken from the joint, and the tensile strength was measured to be 0.56 MPa. The fracture point was at the root of the serration.
[0075] Example 4
[0076] Foam 1 is made into a 300mm × 300mm square precast panel with a thickness of 10mm. The edges of the precast panel are isosceles triangular serrations with a base length of 30mm and a height of 15mm. The precursor solution of foam 1 is evenly applied to the serrated surface, the seams are aligned and appropriate pressure is applied, and it is placed in an oven at 330℃ for 1.0h, then the temperature is increased to 350℃ for 1.0h. After curing, it is removed to obtain the spliced flat foam.
[0077] Tensile properties were tested on samples taken from the joint, and the tensile strength was measured to be 0.75 MPa. The sample was then broken along the joint.
[0078] Example 5
[0079] Foam 2 is made into a 400mm × 400mm square precast panel, 15mm thick, with isosceles triangular serrations at the edges, each 30mm at the base and 30mm at the height. Figure 5 As shown. The precursor solution of foam 2 is evenly applied to the serrated surface, the seams are aligned and appropriate pressure is applied, and it is placed in an oven at 370℃ for 1.5 hours. Then the temperature is increased to 390℃ and heated for 1.5 hours. After curing, it is taken out to obtain the spliced flat foam.
[0080] Tensile properties were tested on samples taken from the seam, and the tensile strength was measured to be 1.52 MPa. The fracture point was the foam body far from the seam.
[0081] Example 6
[0082] Foam 2 is made into a 400mm×400mm square precast board with a thickness of 20mm. The edges of the precast board are isosceles triangular serrations with a base length of 30mm and a height of 30mm. Take 100g of the precursor powder of foam 2, add 10g of tetrahydrofuran to it, stir thoroughly to form a paste, and apply it to the serrated surface. Align the seams and apply appropriate pressure. Place it in a 370℃ oven and heat for 1.5h, then raise the temperature to 390℃ and heat for 1.5h. After curing, remove it to obtain the spliced flat foam.
[0083] The foam was shaped using a machining center. No cracks appeared at the seams during the machining process, and the seams were found to be filled tightly without any voids or defects after machining.
[0084] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.
[0085] The contents not described in detail in this specification are common knowledge to those skilled in the art.
Claims
1. A method of splicing rigid polyimide foam preforms, characterized by, The application relates to a method for preparing a hard polyimide foam plate. S1, a precursor solution is prepared by using aromatic dianhydride, aromatic diamine and capping agent; S2, the precursor solution is dried and crushed to obtain polyester ammonium salt powder; S3, the polyester ammonium salt powder is heated and pressurized to foam to obtain a hard polyimide foam blank, S4, the hard polyimide foam blank is processed into a foam plate with a splicable part at the edge; S5, polyimide-based adhesive is applied to the splicable end surface of the foam plate, wherein the polyimide-based adhesive is the precursor solution in step S1 or a mixture of the polyester ammonium salt powder and tetrahydrofuran in step S2; S6, a plurality of foam plates are spliced according to the predetermined size, the splicable parts are embedded into each other by applying pressure to form an overall structure; S7, heat treatment is performed to solidify the polyimide-based adhesive of the splicable part.
2. The method of splicing rigid polyimide foam preforms according to claim 1, wherein The method for preparing the precursor solution by using aromatic dianhydride, aromatic diamine and capping agent in step S1 comprises the following steps: S1.1 aromatic dianhydride and capping agent are added into a solvent, and heated at 50-70 DEG C for 1-4 hours; S1.2 aromatic diamine is added, and heated at 50-70 DEG C for 3-8 hours to obtain the precursor solution; S1.3 a foam stabilizer is added into the precursor solution. The molar ratio of the aromatic dianhydride, the aromatic diamine and the capping agent is 1-6:1-6:2; The mass fraction of the foam stabilizer is 0.5%-6% of the solid content of the precursor solution.
3. The method of splicing rigid polyimide foam preforms according to claim 2, wherein The total mass percentage of the aromatic dianhydride, the aromatic diamine and the capping agent in the precursor solution is 40-70%.
4. The method of splicing rigid polyimide foam preforms according to claim 2, wherein The solvent in step S1.1 is a mixture of tetrahydrofuran and methanol, and the mass ratio of tetrahydrofuran to methanol is 3-6:1; the foam stabilizer in step S1.3 is a silicone foam stabilizer.
5. The method of splicing rigid polyimide foam preforms according to claim 1, wherein The aromatic dianhydride is one or a combination of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, bisphenol A type diphenyl ether dianhydride or 2,3',4,4'-biphenyl tetracarboxylic dianhydride; The aromatic diamine is one or a combination of 1,4-p-phenylenediamine, 1,3-m-phenylenediamine, 4,4'-diamino diphenyl ether, 3,4'-diamino diphenyl ether, 4,4'-bis(3-aminophenoxy)benzophenone, 4,4'-bis(3-aminophenoxy)diphenyl sulfone, 1,3-bis(4'-aminophenoxy)benzene or 2,2'-bis[4-(4-aminophenoxyphenyl)]propane; The capping agent is one or a combination of 5-norbornene-2,3-dicarboxylic anhydride, 4-phenylacetylene phthalic anhydride or 4-ethynyl phthalic anhydride.
6. The method of splicing rigid polyimide foam preforms according to claim 1, wherein In step S2, the precursor solution is first dried in an oven at 70-100 DEG C for 0.2-2 hours, and then dried in an oven at 190 DEG C-250 DEG C for 0.5-4 hours.
7. The method of splicing rigid polyimide foam preforms according to claim 1, wherein In step S3, the heating and pressurizing foaming parameters are as follows: the pressure is 0.01-0.3 MPa, the heating process is programmed temperature control, the temperature is 240-390 DEG C, and the total foaming time is 8-24 hours.
8. The method of splicing rigid polyimide foam preforms according to claim 1, wherein The thickness of the foam board in the step S4 is 5-25mm, the length and width are 100-700mm, and the peripheral splicing part is in a shape capable of being spliced or interlocked with each other, specifically, a zigzag shape, a wave shape, a trapezoidal shape or a rectangular shape.
9. The method of splicing rigid polyimide foam preforms according to claim 8, wherein When the splicing shape is a zigzag shape, the length and width of the zigzag are 15mm-45mm, and the zigzag angle is 30-60°.
10. The method of splicing rigid polyimide foam preforms according to claim 1, wherein The mass ratio of the mixture of the polyester ammonium salt powder and the tetrahydrofuran in the step S5 is 100:5-25.
11. The method of splicing rigid polyimide foam preforms according to claim 1, wherein In the step S6, the pressure applying mode after splicing is vacuumizing and pressurizing or mold pressurizing, and the pressurizing and heat treatment are simultaneously performed. The temperature of the heat treatment in the step S7 is 320℃-380℃, and the treatment time is 1-5h.
12. A rigid polyimide foam preform characterized by, The splicing method is obtained by using any one of claims 1-11.
13. The rigid polyimide foam preform of claim 12, wherein, The average density of the rigid polyimide foam preform is 80-200 kg / m 3 , the glass transition temperature T g ≥ 370℃, the thermal decomposition temperature T d5％ ≥ 550℃, and the room temperature tensile shear strength of the joint is ≥ 3 MPa.