Polyimide composite material liquid infiltration autoclave curing molding method

Abstract

The invention belongs to the technical field of manufacturing of resin-based composite materials, and particularly relates to a liquid infiltration autoclave curing forming method for a polyimide composite material. The preparation method comprises the following steps: injecting amic acid oligomer or amide salt oligomer or polyimide resin into a fiber preform assembled on a single-sided mold by adopting a vacuum-assisted impregnation method, pretreating the impregnated fiber preform, packaging by adopting a high-temperature packaging material, and curing in an autoclave, thereby obtaining the high-temperature-resistant fiber preform. Thus, the polyimide composite material is obtained. According to the polyimide composite material and the component thereof prepared by the invention, the polyimide composite material reinforced complex structure can be integrally formed by adopting a single-sided mold, the adoption of an immature high-temperature secondary cementing process method is avoided, and the preparation method has important significance for expanding the application range of the polyimide composite material.

Description

Technical Field

[0001] The invention belongs to the technical field of manufacturing resin-based composite materials, and relates to a polyimide composite material liquid impregnation autoclave curing molding method. Background Art

[0002] Polyimide resin-based composite materials have been widely used in aero engines, missiles, high-speed aircraft and other equipment due to their excellent thermal stability and mechanical properties at high temperatures. For example, the engine casing, F404 engine, F119 engine and other models all use polyimide composite materials, and gradually expanded to CFM56 engine core cap, F119 guide vane, M88 nozzle adjustment plate, PW4000 high-pressure compressor movable blade and other structures. In addition, missile rudders, fairings, and hypersonic aircraft fuselage structures have also been used. At present, the mature molding processes of polyimide composite materials are mainly autoclave process and liquid RTM (Rein transfer molding) molding process. The autoclave process is suitable for manufacturing large-sized parts, and the RTM process is suitable for parts with complex structures but relatively small parts.

[0003] With the gradual expansion of application fields, the demand for high-speed aircraft or aircraft structures is becoming more and more clear, especially the rear fuselage structure, which is mostly a reinforced wall panel structure. For high-temperature molded polyimide composite materials, the molding process of this type of structure is difficult. The autoclave process often requires a secondary bonding process that is not yet mature, and it is difficult to achieve integrated molding. The RTM process is suitable for the overall molding of complex structures, but it is often suitable for structures with relatively small part sizes. However, with the rapid development of composite material molding technology in recent years, the vacuum-assisted liquid immersion process (VARI, Vacuumassist resin infusion) is a liquid molding technology suitable for the manufacture of large-size part structures that has been developed in recent years. This technology is mainly used in the molding of epoxy resin and bismaleimide resin-based composite materials, but there is no report on the application of VARI process to polyimide composite materials. Therefore, if the advantages of different molding process methods can be combined and further integrated, the process advantages can be maximized. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The technical problem to be solved by the present invention is the difficulty of high temperature molding of polyimide composite material reinforced wall plate structure.

[0006] (II) Technical solution

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0008] A polyimide composite material liquid impregnation autoclave curing molding method, the method adopts a low-temperature vacuum assisted impregnation method, and comprises the following steps:

[0009] S1. concentrating the oligomer solution obtained by the polymerization reaction to obtain a high concentration oligomer solution;

[0010] S2. A continuous fiber preform is prepared by shaping the fabric and laid on a single-sided autoclave molding mold and packaged using conventional packaging materials;

[0011] S3. The high concentration oligomer solution is injected into the continuous fiber preform assembled in the single-sided mold by vacuum-assisted impregnation, and the impregnated continuous fiber preform is pretreated;

[0012] S4. The conventional packaging material of the pretreated continuous fiber preform is removed, and then the preform is packaged with a high-temperature packaging material, and placed in an autoclave for curing, and the curing process is vacuumed, and the mold is heated and pressurized;

[0013] S5. Maintain the pressure of the mold and the vacuum degree of the autoclave, cool down to below 150° C., then release the pressure and vacuum, open the autoclave, and demold to obtain a molded polyimide composite material.

[0014] The conventional packaging materials are polytetrafluoroethylene cloth, flow guide net, breathable isolation cloth, conventional vacuum bag, putty strip and the like.

[0015] The high-temperature packaging materials include high-temperature polytetrafluoroethylene cloth, breathable felt, high-temperature vacuum bag, high-temperature putty strip, metal guide net, high-temperature air isolation membrane and the like.

[0016] Furthermore, the oligomer solution is selected from at least one of an amic acid oligomer solution, an amide salt oligomer solution, and an amide ester oligomer solution.

[0017] Furthermore, the concentration temperature in S1 is 60° C.-150° C. The concentration of the obtained high-concentration oligomer solution is 60-95%wt.

[0018] Furthermore, the oligomer solution concentration method is selected from one of distillation, reduced pressure distillation, freeze drying, dialysis, ultrafiltration, adsorption and precipitation.

[0019] Furthermore, the continuous fiber preform described in S2 is prepared by covering, sewing or weaving a shaped fabric.

[0020] Furthermore, in step S3, the injection temperature of the injection is 80-150°C.

[0021] Furthermore, in step S3, the pretreatment temperature is 80-250° C., and the pretreatment time is 30-600 min.

[0022] Furthermore, in step S4, the vacuum degree of the vacuum extraction is -0.095MPa to -0.01MPa.

[0023] Furthermore, in step S4, the heating and pressurizing of the mold includes: first heating to 280-350°C and pressurizing 0.1-2.5MPa, then heating to 350-450°C and keeping the temperature for 30min-1000min to complete the curing.

[0024] The present invention also provides another polyimide composite material liquid impregnation autoclave curing molding method, the method adopts a high temperature vacuum assisted impregnation method, and comprises the following steps:

[0025] S1. A continuous fiber preform is prepared by shaping the fabric, and is laid on a single-sided autoclave molding mold, and is encapsulated with a high-temperature encapsulation material;

[0026] S2. placing the encapsulated continuous fiber preform and the mold in an autoclave, and injecting the polyimide resin into the continuous fiber preform assembled on the single-sided mold by vacuum-assisted impregnation;

[0027] S3. After impregnation is completed, the continuous fiber preform is cured, the mold is heated and pressurized, and the autoclave is evacuated during the curing process;

[0028] S4. Maintain the pressure of the mold and the vacuum degree of the autoclave, cool to below 120° C., then release the pressure and vacuum, open the autoclave, and demold to obtain a molded polyimide composite material.

[0029] Furthermore, in step S2, the injection temperature of the injection is 230-300°C.

[0030] Furthermore, in step S3, the heating and pressurizing of the mold includes: first heating to 280-350°C, keeping warm for 1-300 minutes, then pressurizing by 0.1-2.5MPa, and then heating to 350-450°C and keeping warm for 30-1000 minutes to complete curing.

[0031] Furthermore, in step S3, the vacuum degree is controlled to be -0.095 MPa to -0.01 MPa.

[0032] Furthermore, in the method of the present invention, the shaped fabric is a pre-shaped fabric with a polyimide setting agent adhered to the surface, the pre-shaped treatment temperature is 50° C.-150° C., and the pre-shaped treatment time is 10 min-300 min.

[0033] Furthermore, in the method of the present invention, the continuous fiber is selected from one or more of carbon fiber, glass fiber, aramid fiber, polyimide fiber, PBO fiber, basalt fiber, and silicon carbide fiber.

[0034] Furthermore, in the method of the present invention, the weaving method is selected from one of two-dimensional weaving, two-dimensional triaxial weaving, two-and-a-half-dimensional weaving, and three-dimensional weaving.

[0035] The present invention also provides a polyimide composite material, which is obtained by the above method of the present invention.

[0036] The present invention also provides an application of the polyimide composite material in a flying device.

[0037] (III) Beneficial effects

[0038] The above technical solution of the present invention has the following advantages:

[0039] The present invention uses a vacuum-assisted impregnation method to inject amic acid oligomers or amide salt oligomers or polyimide resins into a fiber preform assembled in a single-sided mold, pre-treats the impregnated fiber preform, and then uses a high-temperature packaging material to package it, and places it in an autoclave to complete curing, thereby obtaining a polyimide composite material. The polyimide composite material and its components prepared by the present invention can realize the use of a single-sided mold to integrally mold a complex structure reinforced by a polyimide composite material, avoid the use of an immature high-temperature secondary bonding process method, and are of great significance for expanding the application range of polyimide composite materials. DETAILED DESCRIPTION

[0040] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0041] A polyimide composite material liquid impregnation autoclave curing molding method, the method adopts a low-temperature vacuum assisted impregnation method, and comprises the following steps:

[0042] S1. concentrating the oligomer solution obtained by the polymerization reaction to obtain a high concentration oligomer solution;

[0043] S2. A continuous fiber preform is prepared by shaping the fabric and laid on a single-sided autoclave molding mold and packaged using conventional packaging materials;

[0044] S3. The high concentration oligomer solution is injected into the continuous fiber preform assembled in the single-sided mold by vacuum-assisted impregnation, and the impregnated continuous fiber preform is pretreated;

[0045] S4. The conventional packaging material of the pretreated continuous fiber preform is removed, and then the preform is packaged with a high-temperature packaging material, and placed in an autoclave for curing, and the curing process is vacuumed, and the mold is heated and pressurized;

[0046] S5. Maintain the pressure of the mold and the vacuum degree of the autoclave, cool down to below 150° C., then release the pressure and vacuum, open the autoclave, and demold to obtain a molded polyimide composite material.

[0047] The conventional packaging materials are polytetrafluoroethylene cloth, flow guide net, breathable isolation cloth, conventional vacuum bag, putty strip and the like.

[0048] The high-temperature packaging materials include high-temperature polytetrafluoroethylene cloth, breathable felt, high-temperature vacuum bag, high-temperature putty strip, metal guide net, high-temperature air isolation membrane and the like.

[0049] Furthermore, the oligomer solution is selected from at least one of an amic acid oligomer solution, an amide salt oligomer solution, and an amide ester oligomer solution.

[0050] Furthermore, the concentration temperature in S1 is 60° C.-150° C. The concentration of the obtained high-concentration oligomer solution is 60-95%wt.

[0051] Furthermore, the oligomer solution concentration method is selected from one of distillation, reduced pressure distillation, freeze drying, dialysis, ultrafiltration, adsorption and precipitation.

[0052] Furthermore, the continuous fiber preform described in S2 is prepared by covering, sewing or weaving a shaped fabric.

[0053] Furthermore, in step S3, the injection temperature of the injection is 80-150°C.

[0054] Furthermore, in step S3, the pretreatment temperature is 80-250° C., and the pretreatment time is 30-600 min.

[0055] Furthermore, in step S4, the vacuum degree of the vacuum extraction is -0.095MPa to -0.01MPa.

[0056] Furthermore, in step S4, the heating and pressurizing of the mold includes: first heating to 280-350°C and pressurizing 0.1-2.5MPa, then heating to 350-450°C and keeping the temperature for 30min-1000min to complete the curing.

[0057] The present invention also provides another polyimide composite material liquid impregnation autoclave curing molding method, the method adopts a high temperature vacuum assisted impregnation method, and comprises the following steps:

[0058] S1. A continuous fiber preform is prepared by shaping the fabric, and is laid on a single-sided autoclave molding mold, and is encapsulated with a high-temperature encapsulation material;

[0059] S2. placing the encapsulated continuous fiber preform and the mold in an autoclave, and injecting the polyimide resin into the continuous fiber preform assembled on the single-sided mold by vacuum-assisted impregnation;

[0060] S3. After impregnation is completed, the continuous fiber preform is cured, the mold is heated and pressurized, and the autoclave is evacuated during the curing process;

[0061] S4. Maintain the pressure of the mold and the vacuum degree of the autoclave, cool to below 120° C., then release the pressure and vacuum, open the autoclave, and demold to obtain a molded polyimide composite material.

[0062] Furthermore, in step S2, the injection temperature of the injection is 230-300°C.

[0063] Furthermore, in step S3, the heating and pressurizing of the mold includes: first heating to 280-350°C, keeping warm for 1-300 minutes, then pressurizing by 0.1-2.5MPa, and then heating to 350-450°C and keeping warm for 30-1000 minutes to complete curing.

[0064] Furthermore, in step S3, the vacuum degree is controlled to be -0.095 MPa to -0.01 MPa.

[0065] Furthermore, in the method of the present invention, the shaped fabric is a pre-shaped fabric with a polyimide setting agent adhered to the surface, the pre-shaped treatment temperature is 50° C.-150° C., and the pre-shaped treatment time is 10 min-300 min.

[0066] Furthermore, in the method of the present invention, the continuous fiber is selected from one or more of carbon fiber, glass fiber, aramid fiber, polyimide fiber, PBO fiber, basalt fiber, and silicon carbide fiber.

[0067] Furthermore, in the method of the present invention, the weaving method is selected from one of two-dimensional weaving, two-dimensional triaxial weaving, two-and-a-half-dimensional weaving, and three-dimensional weaving.

[0068] Example 1

[0069] This embodiment introduces a polyimide composite material liquid impregnation autoclave curing molding method, which adopts a low-temperature vacuum assisted impregnation method and includes the following steps:

[0070] S1. Selecting the structure of 4-PEPA / 6FDA / 3,4-ODA (PI-1), PEPA is phenylethynylphthalic anhydride, 6FDA is hexafluorodianhydride, 3,4-ODA is 3,4-diaminodiphenyl ether, using ethanol as a solvent to prepare an amide ester oligomer solution, and quantitatively concentrating it by distillation at a concentration temperature of 90° C. to obtain a PI-1 oligomer solution with a concentration of 80 wt%;

[0071] S2. According to the design requirements of the ply, CF3052 carbon fiber fabric containing polyimide setting agent is selected as the setting fabric, the CF3052 carbon fiber fabric is cut into 500mm×400mm rectangular sheets, laid according to the ply of [(0 / 90)]8, laid on a single-sided autoclave forming mold, vacuum packaged and treated at 100℃ for 30min to obtain a laminate preform, polytetrafluoroethylene cloth, guide net and breathable isolation cloth are laid on the surface of the preform in sequence, inlet and outlet rubber pipes are arranged on the front and rear sides of the preform, and conventional vacuum bags and putty strips are used for packaging;

[0072] S3. Inject 80% PI-1 oligomer solution into the fiber preform assembled in the single-sided mold under vacuum assistance, the injection temperature is 100°C, and the impregnated fiber preform is pretreated at 180°C for 60 minutes.

[0073] S4. All packaging materials used to complete the pretreatment of the fiber preform are removed, and it is re-packaged with high-temperature polytetrafluoroethylene cloth, breathable felt, vacuum bags, and putty strips. It is then placed in an autoclave for curing. The entire curing process is vacuumed and the vacuum degree is controlled at -0.095MPa to -0.01MPa. The mold is heated to 300℃ and pressurized to 1.0MPa. Finally, the temperature is raised to 375℃ and kept warm for 120 minutes to complete the curing.

[0074] S5. The mold is cooled to 145° C. while maintaining pressure and vacuum, and the pressure and vacuum are released. The autoclave is opened and the polyimide composite material (PI-1 / CF3052) is obtained after demolding.

[0075] The relevant properties of the prepared polyimide composite material were tested, as shown in Table 1.

[0076] Table 1 Mechanical properties of PI-1 / CF3052 polyimide composites

[0077] Serial number performance Test Method Measured value 1 Warp tensile strength, MPa ASTM D3039 820 2 Warp compression strength, MPa ASTM D6641 650 3 Warp bending strength, MPa ASTM D790 910 4 Interlaminar shear strength, MPa ASTM D2344 70

[0078] Example 2

[0079] This embodiment introduces a polyimide composite material liquid impregnation autoclave curing molding method, which adopts a low-temperature vacuum assisted impregnation method and includes the following steps:

[0080] S1. Selecting the structure of 4-PEPA / 6FDA / 3,4-ODA (PI-1), PEPA is phenylethynylphthalic anhydride, 6FDA is hexafluorodianhydride, 3,4-ODA is 3,4-diaminodiphenyl ether, using ethanol as a solvent to prepare an amide ester oligomer solution, and quantitatively concentrating it by distillation at a concentration temperature of 90° C. to obtain a PI-1 oligomer solution with a concentration of 80 wt%;

[0081] S2. According to the design requirements, CF3052 carbon fiber fabric containing polyimide setting agent is selected as the setting fabric to prepare the U-shaped structure of the composite material. 2s The CF3052 carbon fiber fabric is cut into rectangles according to the U-shaped structure, and then laid on the preform mold layer by layer. After the laying is completed, vacuum packaging is adopted and the preform is fixed at 100°C for 30 minutes to obtain a U-shaped preform. Teflon cloth, guide net and breathable isolation cloth are laid on the surface of the preform in sequence. Inlet and outlet rubber pipes are arranged on the front and rear sides of the preform, and conventional vacuum bags and putty strips are used for packaging;

[0082] S3. Injecting 80% PI-1 oligomer solution into the fiber preform assembled in the single-sided mold under vacuum assistance, the injection temperature is 100° C., and the impregnated fiber preform is pretreated at 180° C. for 120 min.

[0083] S4. All packaging materials used for the pretreated fiber preform are removed, and the preform is repackaged with high-temperature PTFE cloth, breathable felt, vacuum bag, and putty strips. The preform is then placed in an autoclave for curing. The entire curing process is vacuumed and the vacuum degree is controlled at -0.095MPa to -0.01MPa. The mold is heated to 300°C and pressurized to 1.0MPa. Finally, the temperature is raised to 375°C and maintained for 180 minutes to complete the curing.

[0084] S5. Keep the pressure and vacuum of the mold and cool it down to 140°C, release the pressure and vacuum, open the autoclave, and demold to obtain a U-shaped part of the PI-1 / CF3052 polyimide composite material.

[0085] Example 3

[0086] This embodiment introduces a polyimide composite material liquid impregnation autoclave curing molding method, which adopts a low-temperature vacuum assisted impregnation method and includes the following steps:

[0087] S1. Selecting the structure of 4-PEPA / a-BPDA / M-PDA (PI-2), PEPA is phenylethynylphthalic anhydride, a-BPDA is 2,3,3',4'-biphenyltetracarboxylic dianhydride, M-PDA is m-phenylenediamine, using ethanol as a solvent to prepare an amide ester oligomer solution, and quantitatively concentrating it by distillation at a concentration of 85° C. to obtain a PI-1 oligomer solution with a concentration of 70 wt%;

[0088] S2. According to the design requirements of the ply, CF3031 carbon fiber fabric containing polyimide setting agent is selected as the setting fabric, the CF3031 carbon fiber fabric is cut into 500mm×400mm rectangular sheets, laid according to the ply of [(0 / 90)]8, laid on a single-sided autoclave forming mold, vacuum packaged and treated at 105℃ for 60min to obtain a laminate preform, polytetrafluoroethylene cloth, guide net and breathable isolation cloth are laid on the surface of the preform in sequence, inlet and outlet rubber pipes are arranged on the front and rear sides of the preform, and conventional vacuum bags and putty strips are used for packaging;

[0089] S3. A PI-2 oligomer solution with a concentration of 70% was injected into the fiber preform assembled in the single-sided mold under the action of vacuum assistance. The injection temperature was 110° C. and the impregnated fiber preform was pretreated at 160° C. for 120 min.

[0090] S4. All packaging materials used for the pretreated fiber preform are removed, and the preform is repackaged with high-temperature PTFE cloth, breathable felt, vacuum bag, and putty strips. The preform is then placed in an autoclave for curing. The entire curing process is vacuumed and the vacuum degree is controlled at -0.095MPa to -0.01MPa. The mold is heated to 320°C and pressurized to 0.8MPa. Finally, the mold is heated to 380°C and kept warm for 180 minutes to complete the curing.

[0091] S5. Keep the pressure and vacuum of the mold and cool it down to 145°C, release the pressure and vacuum, open the autoclave, and demold to obtain a polyimide composite material (PI-2 / CF3031).

[0092] The relevant properties of the prepared polyimide composite material were tested, as shown in Table 2.

[0093] Table 2 Mechanical properties of PI-2 / CF3031 polyimide composites

[0094] Serial number performance Test Method Measured value 1 Warp tensile strength, MPa ASTM D3039 850 2 Warp compression strength, MPa ASTM D6641 680 3 Warp bending strength, MPa ASTM D790 900 4 Interlaminar shear strength, MPa ASTM D2344 72

[0095] Example 4

[0096] This embodiment introduces a polyimide composite material liquid impregnation autoclave curing molding method, which adopts a low-temperature vacuum assisted impregnation method and includes the following steps:

[0097] S1. Selecting the structure of 4-PEPA / a-BPDA / M-PDA (PI-2), PEPA is phenylethynylphthalic anhydride, a-BPDA is 2,3,3',4'-biphenyltetracarboxylic dianhydride, M-PDA is m-phenylenediamine, using ethanol as a solvent to prepare an amide ester oligomer solution, and quantitatively concentrating it by distillation at a concentration of 85° C. to obtain a PI-1 oligomer solution with a concentration of 70 wt%;

[0098] S2. According to the design requirements of the layup, a rectangular preform with a thickness of 4 mm and an outer size of 300 mm × 350 mm was prepared by using T300 fiber and a two-and-a-half-dimensional (2,5D) weaving method, which was laid on a single-sided autoclave forming mold. Teflon cloth, a guide net, and a breathable isolation cloth were laid on the surface of the preform in sequence. Inlet and outlet rubber pipes were arranged on the front and rear sides of the preform, and conventional vacuum bags and putty strips were used for packaging;

[0099] S3. A PI-2 oligomer solution with a concentration of 70% was injected into the fiber preform assembled in the single-sided mold under the action of vacuum assistance. The injection temperature was 110° C. and the impregnated fiber preform was pretreated at 160° C. for 180 min.

[0100] S4. All packaging materials used for the pretreated fiber preform are removed, and the preform is repackaged with high-temperature PTFE cloth, breathable felt, vacuum bag, and putty strips. The preform is then placed in an autoclave for curing. The entire curing process is vacuumed and the vacuum degree is controlled at -0.095MPa to -0.01MPa. The mold is heated to 320°C and pressurized to 0.8MPa. Finally, the mold is heated to 380°C and kept warm for 180 minutes to complete the curing.

[0101] S5. Maintain the pressure and vacuum while cooling to 140°C, release the pressure and vacuum, open the autoclave, and demold to obtain a polyimide composite material (PI-2 / T300).

[0102] Example 5

[0103] This embodiment introduces a polyimide composite material liquid impregnation autoclave curing molding method, which adopts a low-temperature vacuum assisted impregnation method and includes the following steps:

[0104] S1. Selecting the structure of 4-PEPA / a-BPDA / M-PDA (PI-2), PEPA is phenylethynylphthalic anhydride, a-BPDA is 2,3,3',4'-biphenyltetracarboxylic dianhydride, M-PDA is m-phenylenediamine, using ethanol as a solvent to prepare an amide ester oligomer solution, and quantitatively concentrating it by distillation at a concentration of 85° C. to obtain a PI-1 oligomer solution with a concentration of 70 wt%;

[0105] S2. According to the design ply requirements, U3160 carbon fiber unidirectional cord fabric containing polyimide setting agent is used as the setting fabric, and the U3160 carbon fiber unidirectional cord fabric is cut into a rectangle of 500mm×350mm. 12 The preform is covered with a layer of a laminate, laid on a single-sided autoclave forming mold, vacuum packaged and treated at 110°C for 60 minutes to obtain a laminate preform, and polytetrafluoroethylene cloth, a guide net, and a breathable isolation cloth are laid on the surface of the preform in sequence, and inlet and outlet rubber pipes are arranged on the front and rear sides of the preform, and conventional vacuum bags and putty strips are used for packaging;

[0106] S3. A PI-2 oligomer solution with a concentration of 70% was injected into the fiber preform assembled in the single-sided mold under the action of vacuum assistance. The injection temperature was 110° C. and the impregnated fiber preform was pretreated at 160° C. for 120 min.

[0107] S4. All packaging materials used for the pretreated fiber preform are removed, and the preform is repackaged with high-temperature PTFE cloth, breathable felt, vacuum bag, and putty strips. The preform is then placed in an autoclave for curing. The entire curing process is vacuumed and the vacuum degree is controlled at -0.095MPa to -0.01MPa. The mold is heated to 320°C and pressurized to 0.8MPa. Finally, the mold is heated to 380°C and kept warm for 180 minutes to complete the curing.

[0108] S5. Keep the pressure and vacuum of the mold and cool it down to below 145°C, release the pressure and vacuum, open the autoclave, and demold to obtain the polyimide composite material (PI-2 / U3160).

[0109] The relevant properties of the prepared polyimide composite material were tested, as shown in Table 3.

[0110] Table 3 Mechanical properties of PI-2 / U3160 polyimide composites

[0111] Serial number performance Test Method Measured value 1 0° tensile strength, MPa ASTM D3039 1550 2 0° compression strength, MPa ASTM D6641 1180 3 Bending strength, MPa ASTM D790 1590 4 Interlaminar shear strength, MPa ASTM D2344 106

[0112] Example 6

[0113] This embodiment provides a polyimide composite material liquid impregnation autoclave curing molding method, which adopts a high-temperature vacuum-assisted impregnation method and includes the following steps:

[0114] S1. The structure of 4-PEPA / a-BPDA / 3,4-DA (PI-3) was selected, where PEPA was phenylethynylphthalic anhydride, a-BPDA was 2,3,3',4'-biphenyltetracarboxylic dianhydride, and 3,4-DA was 3,4-diaminodiphenyl ether. The fully imidized PI-3 oligomer was obtained by a two-step solution synthesis method.

[0115] S2. According to the design ply requirements, U3160 carbon fiber unidirectional cord fabric containing polyimide setting agent is used as the setting fabric, and the U3160 carbon fiber unidirectional cord fabric is cut into a rectangle of 500mm×350mm. 12 The preform is covered with a layer and laid on a single-sided autoclave forming mold. It is vacuum packaged and treated at 110°C for 60 minutes to obtain a preform. Teflon cloth, metal guide net, and high-temperature air-insulated isolation film are laid on the surface of the preform in sequence. Inlet and outlet rubber pipes are arranged on the front and rear sides of the preform, and it is packaged with a high-temperature vacuum bag and putty strips.

[0116] S3. The polyimide resin is injected into the fiber preform assembled in the single-sided mold by vacuum-assisted impregnation method, and the injection temperature is 280 ° C;

[0117] S4. After the impregnation of the fiber preform is maintained at 310°C for 60 minutes, the preform is pressurized to 1.6MPa and finally heated to 375°C for 120 minutes to complete the curing. The whole curing process is vacuumed and the vacuum degree is controlled to be -0.095MPa to -0.01MPa.

[0118] S5. Keep the pressure and vacuum of the mold and cool it down to 115°C, release the pressure and vacuum, open the autoclave, and demold to obtain the PI-3 / U3160 polyimide composite material.

[0119] The relevant properties of the prepared polyimide composite material were tested, as shown in Table 4.

[0120] Table 4 Mechanical properties of PI-3 / U3160 polyimide composites

[0121] Serial number performance Test Method Measured value 1 0° tensile strength, MPa ASTM D3039 1610 2 0° compression strength, MPa ASTM D6641 1250 3 Bending strength, MPa ASTM D790 1530 4 Interlaminar shear strength, MPa ASTM D2344 108

[0122] Example 7

[0123] This embodiment provides a polyimide composite material liquid impregnation autoclave curing molding method, which adopts a high-temperature vacuum-assisted impregnation method and includes the following steps:

[0124] S1. The structure of 4-PEPA / a-BPDA / 3,4-DA (PI-3) was selected, where PEPA was phenylethynylphthalic anhydride, a-BPDA was 2,3,3',4'-biphenyltetracarboxylic dianhydride, and 3,4-DA was 3,4-diaminodiphenyl ether. The fully imidized PI-3 oligomer was obtained by a two-step solution synthesis method.

[0125] S2. According to the design requirements of the layup, a rectangular preform with a thickness of 4 mm and an outer size of 300 mm × 350 mm is prepared by using T300 fiber and a two-and-a-half-dimensional (2,5D) weaving method, which is laid on a single-sided autoclave forming mold. Teflon cloth, metal guide net, and high-temperature air-insulated isolation film are laid on the surface of the preform in sequence. Inlet and outlet rubber pipes are arranged on the front and rear sides of the preform, and high-temperature vacuum bags and putty strips are used for packaging;

[0126] S3. The polyimide resin is injected into the fiber preform assembled in the single-sided mold by vacuum-assisted impregnation method, and the injection temperature is 280 ° C;

[0127] S3. The impregnated fiber preform is kept at 310°C for 60 minutes, then pressurized to 1.8 MPa, and finally heated to 375°C for 180 minutes to complete curing. The whole curing process is vacuumed, and the vacuum degree is controlled to be -0.095 MPa to -0.01 MPa.

[0128] S4. Keep the pressure and vacuum of the mold and cool it down to below 120°C, release the pressure and vacuum, open the autoclave, and obtain the PI-3 braided polyimide composite material after demoulding.

[0129] The present invention adopts a vacuum-assisted impregnation method to inject amic acid oligomer or amide salt oligomer or polyimide resin into a fiber preform assembled in a single-sided mold, pre-treats the impregnated fiber preform, and then packages it with a high-temperature packaging material, and places it in an autoclave to complete curing, thereby obtaining a polyimide composite material.

[0130] It can be seen from Tables 1-5 that the polyimide composite materials and components prepared by the present invention have good tensile, compression, bending and shear properties, and realize the integrated molding of polyimide composite reinforced complex structures using a single-sided mold, avoiding the use of immature high-temperature secondary bonding process methods, which is of great significance for expanding the application range of polyimide composite materials.

[0131] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. For the embodiments of the method, the relevant parts can refer to the partial description of the device embodiment (adopted according to the writing situation). The present invention is not limited to the specific steps and structures described above. In addition, for the sake of brevity, a detailed description of known method technologies is omitted here.

[0132] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A polyimide composite material liquid impregnation autoclave curing molding method, characterized in that: The method adopts a low-temperature vacuum-assisted impregnation method, comprising the following steps: S1. concentrating the oligomer solution obtained by the polymerization reaction to obtain a high concentration oligomer solution; S2. A continuous fiber preform is prepared by shaping the fabric and laid on a single-sided autoclave molding mold and packaged using conventional packaging materials; S3. The high concentration oligomer solution is injected into the continuous fiber preform assembled in the single-sided mold by vacuum-assisted impregnation, and the impregnated continuous fiber preform is pretreated; S4. The conventional packaging material of the pretreated continuous fiber preform is removed, and then the preform is packaged with a high-temperature packaging material, and placed in an autoclave for curing, and the curing process is vacuumed, and the mold is heated and pressurized; S5. Maintain the pressure of the mold and the vacuum degree of the autoclave, cool down to below 150° C., then release the pressure and vacuum, open the autoclave, and demold to obtain a molded polyimide composite material.

2. The method according to claim 1, characterized in that The oligomer solution is selected from at least one of an amic acid oligomer solution, an amide salt oligomer solution, and an amide ester oligomer solution.

3. The method according to claim 1, characterized in that The concentration of the high-concentration oligomer solution is 60-95%wt.

4. The method according to claim 1, characterized in that In step S3, the injection temperature of the injection is 80-150°C; and / or, The pretreatment temperature is 80-250° C., and the pretreatment time is 30-600 min.

5. The method according to claim 1, characterized in that In step S4, the vacuum degree of the vacuum extraction is -0.095MPa to -0.01MPa, and / or the heating and pressurizing of the mold includes: first heating to 280-350°C and pressurizing 0.1 to 2.5MPa, then heating to 350°C to 450°C and keeping warm for 30min to 1000min to complete curing.

6. A polyimide composite material liquid impregnation autoclave curing molding method, characterized in that: The method adopts a high temperature vacuum assisted impregnation method, comprising the following steps: S1. A continuous fiber preform is prepared by shaping the fabric, and is laid on a single-sided autoclave molding mold, and is encapsulated with a high-temperature encapsulation material; S2. placing the encapsulated continuous fiber preform and the mold in an autoclave, and injecting the polyimide resin into the continuous fiber preform assembled on the single-sided mold by vacuum-assisted impregnation; S3. After impregnation is completed, the continuous fiber preform is cured, the mold is heated and pressurized, and the autoclave is evacuated during the curing process; S4. Maintain the pressure of the mold and the vacuum degree of the autoclave, cool to below 120° C., then release the pressure and vacuum, open the autoclave, and demold to obtain a molded polyimide composite material.

7. The method according to claim 6, characterized in that In step S2, the injection temperature of the injection is 230-300°C.

8. The method according to claim 6, characterized in that In step S3, the heating and pressurizing of the mold includes: first heating to 280-350°C, keeping warm for 1-300 minutes, then pressurizing by 0.1-2.5MPa, and then heating to 350-450°C and keeping warm for 30-1000 minutes to complete curing; and / or, vacuuming to control the vacuum degree to -0.095MPa to -0.01MPa.

9. A polyimide composite material obtained by the method according to any one of claims 1 to 5 or the method according to any one of claims 6 to 8.

10. Use of the polyimide composite material according to claim 9 in a flying device.