High-strength in-plane heat-conducting and out-plane heat-insulating composite material and preparation method thereof

Abstract

The invention provides a high-strength in-plane heat conduction and out-plane heat insulation composite material and a preparation method thereof, and belongs to the technical field of composite materials. The phenolic curing agent is used as the curing agent of the high-temperature-resistant phthalonitrile resin, so that the curing efficiency of the phthalonitrile resin is improved, and the curing temperature is reduced. The preparation method comprises the following steps: preparing a resin-based fiber composite material as a heat insulation layer from phthalonitrile resin, introducing a heat conduction filler to prepare a phthalonitrile resin-based carbon fiber composite material, and preparing the high-strength in-plane heat conduction and out-plane heat insulation phthalonitrile composite material in a hot pressing manner. The composite material with heat insulation and heat conduction functions is obtained through flexible design in a hot pressing mode, multifunctional integration is achieved, and a new thought is provided for design of similar multifunctional composite materials.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and relates to a high-strength composite material with in-plane heat conduction and out-plane heat insulation, and a preparation method thereof. Background Art

[0002] Aerospace materials are high-performance materials used in the design and manufacture of aircraft. They need to meet the requirements of being lightweight, high-strength, high-temperature resistant, and corrosion-resistant under extreme conditions. In applications in the aerospace industry, when an aircraft is traveling at high speed or passing through a high-temperature area, the fuselage will generate a large amount of heat. The accumulation of heat will reduce the performance and life of the equipment. Therefore, how the aircraft can quickly dissipate heat without damaging other properties of the aircraft fuselage has become a major problem. The thermal conductivity of materials is divided into in-plane thermal conductivity and out-of-plane thermal conductivity. Specifically, in-plane thermal conductivity refers to the transfer of heat perpendicular to the plane of the material, and out-of-plane thermal conductivity refers to the transfer of heat parallel to the plane of the material. Therefore, considering the heat dissipation and heat insulation problems of aircraft, a concept of in-plane thermal conduction and out-of-plane thermal insulation is proposed, so that heat is only dissipated perpendicular to the material, blocking its transfer in the parallel direction, thereby achieving the purpose of efficient heat dissipation without damaging the equipment inside the fuselage and ensuring the safety of cabin personnel.

[0003] Phthalonitrile resins are a class of high-performance thermosetting polymers containing cyano groups. Upon polymerization, they form a three-dimensional network, endowing them with excellent thermal stability, outstanding mechanical properties, and good chemical resistance, making them widely used in aerospace, electronics, and chemical industries. However, cyanopolymers typically have high melting points and rigidity, making them difficult to process. Polymerization conditions are demanding, requiring high temperatures and high pressures, which places high demands on production equipment and increases operational complexity and cost. The introduction of curing agents is one of the most common methods to address the high polymerization temperatures of phthalonitrile, with amines, phenols, and anhydrides being the most common. Fully cured phthalonitrile resins can achieve decomposition temperatures of 500°C or higher, and glass transition temperatures of 350-400°C, making them excellent candidates for high-temperature applications. Composites based on phthalonitrile resins offer the advantages of lightweight, high strength, high-temperature resistance, and corrosion resistance required for aerospace applications, making them promising substrates for aircraft manufacturing. However, the thermal conductivity of phthalonitrile resin is low, requiring the addition of fillers to enhance its performance. Furthermore, ensuring that the fillers conduct heat out-of-plane while insulating in-plane is a major technical challenge. To address this, anisotropic thermally conductive fillers are selected and vertically aligned within the phthalonitrile resin through magnetic fields or shear forces, along with structural optimization. Summary of the Invention

[0004] In view of this, the present invention provides a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation and a preparation method thereof.

[0005] The object of the present invention is to prepare a composite material with both heat insulation and heat conduction functions for aircraft, so as to avoid overheating of aircraft during flight and cause equipment failure and material performance loss. The present invention utilizes phthalonitrile resin to prepare resin-based glass fiber material as thermal insulation layer, then prepares phthalonitrile resin-based carbon fiber material as thermal conductive layer by combining the directional arrangement technology of filler by adding anisotropic filler, and prepares the composite material containing high-strength in-plane heat conduction and out-plane heat insulation by hot pressing the thermal conductive layer and the thermal insulation layer. The phthalonitrile resin involved in the present invention is a curing agent with phenol, which can undergo polymerization reaction at a lower temperature. Compared with traditional phthalonitrile resin, the curing temperature is lower and the curing rate is fast, which can enhance the thermal stability and mechanical properties of phthalonitrile resin. The present invention is a composite assembly of glass fiber and carbon fiber, which utilizes the different characteristics of glass fiber and carbon fiber to finally prepare a multifunctional composite material.

[0006] It should be noted that the present invention uses phenol as a curing agent for phthalonitrile resin, and then selects glass fiber and carbon fiber to prepare a resin-based glass fiber composite material with thermal insulation function and a resin-based carbon fiber composite material with thermal conductivity function. To enhance the thermal conductivity effect, a thermally conductive filler is added during the preparation of the thermally conductive resin-based carbon fiber composite material. Finally, a composite material with high strength, in-plane thermal conductivity and out-of-plane thermal insulation is prepared through hot pressing.

[0007] By changing the type of phenol and the hot pressing temperature, the chemical structure, reactivity and processability of phthalonitrile resin-based composite materials can be regulated. By changing the type of fiber material, the number of fiber layers, the resin content and the type of filler, the performance of the resin-based composite materials can be regulated to meet the needs of different usage scenarios.

[0008] In order to achieve the above object, the technical solution of the present invention is as follows:

[0009] The first technical purpose of the present invention is to provide a method for preparing a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation. The chemical structure of the phthalonitrile resin used is as follows:

[0010]

[0011] The chemical structure of the curing agent used is as follows:

[0012]

[0013] The specific method is as follows:

[0014] (1) a certain amount of phthalonitrile resin is melted and reacted at an appropriate temperature for a period of time until a phthalonitrile liquid is obtained; (2) a curing agent containing R1 is added to the phthalonitrile resin liquid and reacted for a period of time to obtain a modified phthalonitrile liquid; (3) a solvent is added to the modified phthalonitrile liquid and reacted for a period of time to obtain a phthalonitrile solution; (4) the solution obtained in step (3) is coated on a glass fiber cloth, and dried at a certain temperature to obtain a heat insulation layer prepreg cloth; (5) a certain amount of heat conductive filler is dispersed in the solution obtained in step (3); (6) the solution containing the heat conductive filler obtained in step (5) is coated on a carbon fiber cloth, and dried at a certain temperature to obtain a heat conductive layer prepreg cloth; (7) the heat insulation layer prepreg cloth obtained in step (4) and the heat conductive layer prepreg cloth obtained in step (6) are hot pressed at a certain temperature for a period of time to obtain a composite material.

[0015] Optionally, in step (1),

[0016] The melting temperature of the phthalonitrile resin is 200-240°C;

[0017] The melting time of the phthalonitrile resin is 1 to 3 hours;

[0018] The mass proportion of the phthalonitrile resin in the composite material is 30-40wt%.

[0019] Optionally, in step (2),

[0020] The curing agent is one of bisphenol A, bisphenol S and bisphenol F;

[0021] The molar ratio of the curing agent to the phthalonitrile resin is 1:4-1:1;

[0022] The reaction time after adding the curing agent is 0.5 to 1 hour, and the reaction temperature is 200 to 240°C.

[0023] Optionally, the thermally conductive filler is an inorganic filler or a metal filler, the thermally conductive filler includes boron nitride, carbon nanotubes, and graphene, and the metal filler includes carbonyl iron powder, aluminum powder, and zinc powder;

[0024] The added amount of the thermal conductive filler is 30 to 50 wt % compared to the mass ratio of the phthalonitrile resin.

[0025] Optionally, in step (3),

[0026] The solvent is an organic solvent, specifically one or more combinations of DMF and NMP.

[0027] Optionally, the glass fiber includes E-glass fiber, S-glass fiber, and high-strength glass fiber, and the carbon fiber includes asphalt-based carbon fiber, viscose-based carbon fiber, T800, and T1000.

[0028] Optionally, the hot pressing temperature is 240-320°C;

[0029] The hot pressing time is not less than 2 hours;

[0030] The drying temperature of the glass fiber prepreg cloth and the carbon fiber prepreg cloth are both 120-160° C., and the drying time is both 10-30 minutes.

[0031] The second technical object of the present invention is to provide a high-strength in-plane thermal conductive and out-of-plane thermal insulating composite material prepared by the method as described above, wherein the composite material has a flexural modulus exceeding 30 GPa, a glass transition temperature higher than 300°C, an out-of-plane thermal conductivity lower than 0.8 W / (m*K), and an in-plane thermal conductivity exceeding 2 W / (m*K).

[0032] In summary, the beneficial effects of the present invention are embodied in:

[0033] 1. The present invention utilizes phenol as a modifier for phthalonitrile resin, which can accelerate the curing reaction on the phthalonitrile resin, shorten the curing time, and improve production efficiency;

[0034] 2. Using phenol to modify phthalonitrile can not only improve the thermal stability of phthalonitrile, so that it can maintain dimensional stability at high temperatures, but also enhance the mechanical properties, making it have high strength and high modulus;

[0035] 3. Phthalonitrile resin-based fiber composite materials exhibit low thermal conductivity and good thermal insulation effect, are suitable for high-temperature thermal insulation applications, and can effectively prevent heat transfer and have good thermal resistance;

[0036] 4. The phthalonitrile resin-based carbon fiber composite material prepared by adding thermal conductive fillers can have both thermal conductivity and structural load-bearing functions, realizing the integration of thermal conductivity and structural functions;

[0037] 5. Combining the thermal conductive layer and the thermal insulation layer by hot pressing can flexibly design the structure and performance of the composite material, obtain a composite material with both thermal insulation and thermal conductivity functions, and realize multifunctional integration;

[0038] 6. The phthalonitrile composite material obtained by the method of the present invention has the advantages of light weight, high strength, excellent thermal properties, outstanding mechanical properties, flexible design, etc., which provides new ideas for the design of other similar multifunctional composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0040] Figure 1 Thermal expansion curve of the high-strength in-plane thermal conductive and out-of-plane thermal insulating composite material prepared for experimental case 1.

[0041] Figure 2 This is the thermal diffusivity of the high-strength in-plane thermal conductive and out-of-plane thermal insulating composite material prepared in experimental case three.

[0042] Figure 3 This is the thermal conductivity of the high-strength in-plane thermal conductive and out-of-plane thermal insulating composite material prepared in experimental case three. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] The term "embodiment" is used herein specifically to describe any embodiment as "exemplary," and should not be construed as superior or preferable to other embodiments. Performance indicators in the embodiments of this application were tested using conventional testing methods in the art, unless otherwise specified. It should be understood that the terms used in this application are intended solely to describe specific implementations and are not intended to limit the disclosure herein.

[0045] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0046] In order to better illustrate the content of this application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that this application can be implemented without certain specific details. In the examples, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of this application.

[0047] Under the premise of no conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of this application.

[0048] The invention discloses a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation and a preparation method thereof.

[0049] For a better understanding of the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0050] Implementation Case 1

[0051] Step 1: 9.72 g of phthalonitrile resin was melted and reacted at 200°C for 1 hour until phthalonitrile liquid was obtained;

[0052] Step 2: Add 2.28 g of bisphenol A to the phthalonitrile resin liquid and react for 40 minutes to obtain a modified phthalonitrile liquid;

[0053] Step 3: Add NMP to the modified phthalonitrile liquid and react for 30 minutes to obtain a phthalonitrile solution;

[0054] Step 4: coating the phthalonitrile solution obtained in step 3 on high-strength glass fiber cloth, and drying at 160° C. for 15 minutes to obtain a thermal insulation layer prepreg cloth;

[0055] Step 5: Disperse 3.6 g of carbonyl iron powder in the phthalonitrile solution obtained in step 3;

[0056] Step 6: Coat the thermally conductive filler-containing solution obtained in step 5 on T800 and dry at 160° C. for 15 minutes to obtain a thermally conductive layer prepreg cloth;

[0057] Step 7: hot-press the thermal insulation layer prepreg cloth and the thermal conductive layer prepreg cloth obtained in steps 4 and 6 at 240° C. for 2 hours to obtain a composite material.

[0058] In this case, a phthalonitrile resin-based composite material was obtained with a flexural modulus of 44.7 GPa, a CTE of 46.5 ppm / °C, a glass transition temperature of 325°C, and an out-of-plane thermal diffusivity of 0.302 mm 2 / s, the out-of-plane thermal conductivity is 0.472W / (m*K), and the in-plane thermal diffusion coefficient is 1.721mm 2 / s, and the in-plane thermal conductivity is 2.84W / (m*K).

[0059] Implementation Case 2

[0060] Step 1: 4.86 g of phthalonitrile resin was melted and reacted at 200°C for 1 hour until phthalonitrile liquid was obtained;

[0061] Step 2: Add 2.0 g of bisphenol F to the phthalonitrile resin liquid and react for 30 minutes to obtain a modified phthalonitrile liquid;

[0062] Step 3: Add DMF to the modified phthalonitrile liquid and react for 45 minutes to obtain a phthalonitrile solution;

[0063] Step 4: coating the phthalonitrile solution obtained in step 3 on E-glass fiber cloth, and drying at 160° C. for 10 minutes to obtain a thermal insulation layer prepreg cloth;

[0064] Step 5: Disperse 2.4 g of boron nitride in the phthalonitrile solution obtained in step 3;

[0065] Step 6: coating the solution containing the thermal conductive filler obtained in step 5 on the asphalt-based carbon fiber cloth, and drying at 160° C. for 20 minutes to obtain a thermal conductive layer prepreg cloth;

[0066] Step 7: hot-press the thermal insulation layer prepreg cloth and the thermal conductive layer prepreg cloth obtained in steps 4 and 6 at 280° C. for 2 hours to obtain a composite material.

[0067] The phthalonitrile resin-based composite material obtained in this case has a flexural modulus of 38.6 GPa, a CTE of 52 ppm / °C, a glass transition temperature of 300°C, and an out-of-plane thermal diffusivity of 0.336 mm 2 / s, the out-of-plane thermal conductivity is 0.483W / (m*K), and the in-plane thermal diffusion coefficient is 1.648mm 2 / s, and the in-plane thermal conductivity is 2.719W / (m*K).

[0068] Implementation Case 3

[0069] Step 1: 4.86 g of phthalonitrile resin was melted and reacted at 205°C for 1 hour until phthalonitrile liquid was obtained;

[0070] Step 2: Add 2.28 g of bisphenol A to the phthalonitrile resin liquid and react for 30 minutes to obtain a modified phthalonitrile liquid;

[0071] Step 3: Add DMF to the modified phthalonitrile liquid and react for 30 minutes to obtain a phthalonitrile solution;

[0072] Step 4: coating the phthalonitrile solution obtained in step 3 on S-glass fiber cloth, and drying at 120° C. for 30 minutes to obtain a thermal insulation layer prepreg cloth;

[0073] Step 5: Disperse 2.85 g of carbon nanotubes in the phthalonitrile solution obtained in step 3;

[0074] Step 6: coating the carbon nanotube-containing solution obtained in step 5 on viscose-based carbon fibers, and drying at 140° C. for 20 minutes to obtain a thermal conductive layer prepreg cloth;

[0075] Step 7: hot-press the thermal insulation layer prepreg cloth and the thermal conductive layer prepreg cloth obtained in steps 4 and 6 at 260° C. for 4 hours to obtain a composite material.

[0076] In this case, a phthalonitrile resin-based composite material was obtained with a flexural modulus of 38.4 GPa, a CTE of 57.6 ppm / °C, a glass transition temperature of 317°C, and an out-of-plane thermal diffusivity of 0.254 mm 2 / s, the out-of-plane thermal conductivity is 0.508W / (m*K), and the in-plane thermal diffusion coefficient is 1.726mm 2 / s, and the in-plane thermal conductivity is 2.848W / (m*K).

[0077] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the following comparative examples are provided to further illustrate the technical features disclosed in the present invention, but they should not be construed as limiting the present invention. Other improvements made by those skilled in the art based on the above invention without inventive work are also considered to fall within the scope of protection of the present invention.

[0078] Comparative Case 1

[0079] Same as Example 1, except that there is no heat-conducting layer. The out-of-plane thermal diffusion coefficient of the obtained phthalonitrile resin-based composite material is 0.252 mm 2 / s, the out-of-plane thermal conductivity is 0.505W / (m*K), and the in-plane thermal diffusion coefficient is 0.565mm 2 / s, and the in-plane thermal conductivity is 0.813W / (m*K).

[0080] Comparative Case 2

[0081] Same as Example 1, except that there is no heat insulation layer. The obtained phthalonitrile resin-based composite material has an out-of-plane thermal diffusion coefficient of 0.4 mm 2 / s, the out-of-plane thermal conductivity is 0.555W / (m*K), and the in-plane thermal diffusion coefficient is 1.713mm 2 / s, and the in-plane thermal conductivity is 2.46W / (m*K).

[0082] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation, characterized in that: The method specifically comprises the following steps: (1) melting the phthalonitrile resin at an appropriate temperature for a period of time until a phthalonitrile liquid is obtained; (2) adding a curing agent to the phthalonitrile resin liquid and reacting for a period of time to obtain a phthalonitrile prepolymer; (3) adding a solvent to the phthalonitrile prepolymer liquid and reacting for a period of time to obtain a phthalonitrile prepolymer solution; (4) coating the phthalonitrile prepolymer solution on a glass fiber cloth, and drying at a certain temperature to obtain a thermal insulation layer prepreg cloth; (5) dispersing a certain amount of thermal conductive filler in the phthalonitrile prepolymer solution, and then coating the solution containing the thermal conductive filler on a carbon fiber cloth, and drying at a certain temperature to obtain a thermal conductive layer prepreg cloth; (6) hot pressing the obtained thermal insulation layer prepreg cloth and thermal conductive layer prepreg cloth to obtain a composite material.

2. The method for preparing a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation according to claim 1, characterized in that: The structural formula of the base resin phthalonitrile resin is: The structural formula of the curing agent:

3. The method for preparing a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation according to claim 1, characterized in that: In step (1), The melting temperature of the phthalonitrile resin is 200-240°C; The melting time of the phthalonitrile resin is 1 to 3 hours; The mass proportion of the phthalonitrile resin in the composite material is 30-40wt%.

4. The method for preparing a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation according to claim 1, characterized in that: In step (2), The curing agent is one of bisphenol A, bisphenol S and bisphenol F; The molar ratio of the curing agent to the phthalonitrile resin is 1:4-1:1; The reaction time after adding the curing agent is 0.5 to 1 hour, and the reaction temperature is 200 to 240°C.

5. The method for preparing a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation according to claim 1, characterized in that: The thermally conductive filler is an inorganic filler or a metal filler, wherein the thermally conductive filler includes boron nitride, carbon nanotubes, and graphene, and the metal filler includes carbonyl iron powder, aluminum powder, and zinc powder; The added amount of the thermal conductive filler is 30 to 50 wt % compared to the mass ratio of the phthalonitrile resin.

6. The method for preparing a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation according to claim 1, characterized in that: In step (3), The solvent is an organic solvent, specifically one or more combinations of DMF and NMP.

7. The method for preparing a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation according to claim 1, characterized in that: The glass fiber includes E-glass fiber, S-glass fiber, and high-strength glass fiber, and the carbon fiber includes asphalt-based carbon fiber, viscose-based carbon fiber, T800, and T1000.

8. The method for preparing a high-strength composite material with in-plane heat conduction and out-of-plane heat insulation according to claim 1, characterized in that: The hot pressing temperature is 240-320°C; The hot pressing time is not less than 2 hours; The drying temperature of the glass fiber prepreg cloth and the carbon fiber prepreg cloth are both 120-160° C., and the drying time is both 10-30 minutes.

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