Reinforced flame-retardant electromagnetic shielding thermoset resin matrix composite

Abstract

The application relates to the field of composite materials and discloses a reinforced-flame-retardant-electromagnetic-shielded thermosetting resin-based composite material which comprises a flame-retardant modified thermosetting resin matrix and an electrically conductive modified fiber fabric combined in the matrix; the flame-retardant modified thermosetting resin matrix is a thermosetting resin containing a flame retardant; the electrically conductive modified fiber fabric is a fiber fabric with a surface of electrically conductive nanoparticles; the number of layers of the electrically conductive modified fiber fabric is at least one, and the materials of each layer are the same or different. The electrically conductive modified fiber fabric and the flame-retardant modified thermosetting resin are cured and formed through a vacuum lamination mode, the material has excellent mechanical properties, flame-retardant properties and adjustable electromagnetic shielding properties. The raw materials used in the application have a wide source, low cost, safety and environmental protection, and the application provides a convenient and practical preparation scheme for preparing a flame-retardant electromagnetic shielding laminated composite material.

Description

Technical Field

[0001] This invention relates to the field of composite materials, and more particularly to a reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material. Background Technology

[0002] The rapid development of communication technology has driven the development and application of various electronic and electrical devices, leading to an increasingly complex electromagnetic environment. Excessive electromagnetic radiation can seriously affect human health and interfere with the normal operation of sensitive electronic instruments and systems. Using electromagnetic shielding materials to reflect and / or absorb electromagnetic waves is the most direct way to address electromagnetic hazard. Currently, reinforced polymer-based electromagnetic shielding composites made from conductive fibers have many advantages, such as high mechanical strength, low weight, and easy controllability, and are widely used in electronics, aerospace, and other fields. However, the limited variety and high cost of currently available conductive fibers severely restrict their development. Furthermore, most polymers involved in fiber-reinforced composites are flammable, and the aforementioned application fields have extremely high requirements for the flame-retardant properties of protective shielding materials. Therefore, designing a high-strength electromagnetic shielding composite material with controllable conductive fibers and flame-retardant properties has significant theoretical and practical implications.

[0003] Studies have shown that electromagnetic shielding composite materials constructed using a layered conductive network structure can significantly solve the problem of low utilization efficiency of conductive fillers in matrix blending. Among these methods, constructing a complete conductive network on the fiber surface using a coating finishing process is an effective way to prepare tunable, high-efficiency conductive fibers. Graphene, carbon nanotubes, titanium carbide, and metal nanoparticles are widely used as electromagnetic shielding coating fillers due to their unique advantages such as high electrical conductivity and high aspect ratio / specific surface area. However, for ramie fibers and cotton fibers, the presence of surface sizing during the weaving process often affects the bonding force between them and conductive nanofillers. Furthermore, for commonly used composite reinforcing fibers such as basalt fibers and glass fibers, their surface affinity is poor, resulting in weak bonding force with conductive nanofillers and affecting the construction of their surface conductive coatings. In addition, the compatibility between the conductive nanofiller coating and the polymer matrix is ​​often poor, which will seriously affect the mechanical properties of the molded composite sample. Therefore, the key to preparing mechanically reinforced electromagnetic shielding composite materials with high surface conductivity and high shielding effect lies in enhancing the interaction force between fibers and conductive nanofillers, and between conductive nanocoatings and polymer resins.

[0004] In addition to possessing the required mechanical and electromagnetic shielding properties, fiber-reinforced composites also face serious fire safety issues. The fabrics and polymer matrices involved in these composites, such as epoxy resin (EP) or unsaturated polyester, are highly flammable. To address this problem, adding flame retardants can effectively improve their flame-retardant effect. Current research shows that phosphorus and nitrogen-based flame retardants, especially intumescent flame retardant systems, are widely used in composites due to their advantages such as low addition amount, high flame-retardant efficiency, and good char formation properties. However, when combined with fabrics modified with conductive nanofiller coatings, the interaction between the intumescent flame retardant and the conductive filler coating lacks comprehensive research. Therefore, constructing an efficient flame-retardant-conductive network is key to preparing composites with both excellent flame-retardant and electromagnetic shielding properties. Summary of the Invention

[0005] To address the problems of limited selectivity of conductive fibers, poor compatibility between conductive fibers and resins, and flammability of composite materials in current fiber-reinforced electromagnetic shielding composite materials, this invention provides a reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material. This invention uses vacuum lamination to cure conductive modified fiber fabric and flame-retardant modified thermosetting resin into a molded product. This material has excellent mechanical properties, flame-retardant properties, and adjustable electromagnetic shielding properties.

[0006] The specific technical solution of the present invention is: a reinforced-flame-retardant-electromagnetic shielding thermosetting resin matrix composite material, which includes a flame-retardant modified thermosetting resin matrix and a conductive modified fiber fabric composited in the matrix.

[0007] Wherein: the flame-retardant modified thermosetting resin matrix is ​​a thermosetting resin containing flame retardant; the conductive modified fiber fabric is a fiber fabric with conductive nanoparticle surface modification; the fiber fabric includes one or more of ramie fiber fabric, basalt fiber fabric, cotton fiber fabric and glass fiber fabric; the conductive modified fiber fabric has at least one layer, and the material of each layer may be the same or different.

[0008] This invention modifies the conductivity of the surface of fiber fabrics, adjusting the structure and conductivity of the conductive coating on the fiber surface. This is then achieved through vacuum lamination with a flame-retardant-modified thermosetting resin, resulting in a composite material with enhanced, flame-retardant, and electromagnetic shielding properties. This structural design offers several advantages: First, it solves the problem of conductive nanofiller adsorption on the fiber surface, enhancing the interaction between the conductive coating, the fiber, and the thermosetting resin. Second, it broadens the range of fibers suitable for electromagnetic shielding composites, improving the controllability and efficiency of the electromagnetic shielding function. Third, it mitigates the flammability issue of electromagnetic shielding composites, improving their safety. Fourth, it simplifies the processing, reduces application costs, increases production efficiency, and expands the application scope of electromagnetic shielding composites.

[0009] Preferably, the thermosetting resin includes one or more of epoxy resin and unsaturated polyester.

[0010] Preferably, the flame retardant includes one or more of inorganic flame retardants, nano flame retardants, and intumescent flame retardants.

[0011] Preferably, the flame retardant content in the flame-retardant modified thermosetting resin matrix is ​​10-30 wt%.

[0012] Preferably, the content of conductive nanoparticles in the conductive modified fiber fabric is 0.5-2 mg / cm³. 2 .

[0013] Preferably, the conductive nanoparticles include one or more of graphene, carbon nanotubes, conductive carbon black, metal ions, and titanium carbide.

[0014] Preferably, the conductive nanoparticles are attached to the surface of the fiber fabric by low-temperature plasma sputtering, in-situ modification with polydopamine, surface modification with silane coupling agent, or polymer coating modification.

[0015] Preferably, the conductive modified fiber fabric has multiple layers, and each layer of conductive modified fiber fabric is composited by vacuum lamination and pressing.

[0016] Preferably, the conductive modified fiber fabric has 3-10 layers.

[0017] Preferably, the mass ratio of the conductive modified fiber fabric to the flame-retardant modified thermosetting resin matrix is ​​1:1-2.

[0018] Preferably, the thickness of the reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material is 1-10 mm.

[0019] Preferably, the reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material is selected from one of the following combinations:

[0020] (a) The flame-retardant modified thermosetting resin matrix is ​​an epoxy resin containing an intumescent flame retardant; the conductive modified fiber fabric is a silver nanowire coated modified ramie fiber fabric.

[0021] (b) The flame-retardant modified thermosetting resin matrix is ​​an unsaturated polyester resin containing an intumescent flame retardant; the conductive modified fiber fabric is a titanium carbide / carbon nanotube synergistic modified basalt fiber fabric.

[0022] (c) The flame-retardant modified thermosetting resin matrix is ​​an epoxy resin containing ammonium polyphosphate flame retardant; the conductive modified fiber fabric is a titanium carbide / graphene synergistic modified glass fiber fabric.

[0023] (d) The flame-retardant modified thermosetting resin matrix is ​​an epoxy resin containing ammonium polyphosphate flame retardant; the conductive modified fiber fabric is a titanium carbide / graphene synergistic modified glass fiber fabric and a silane modified basalt fiber fabric.

[0024] This invention discovers that the above-mentioned specific material combination of reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material has excellent flame retardant, mechanical properties and electromagnetic shielding properties.

[0025] Preferably, the reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material has a shielding effectiveness of not less than 30dB in the X-band 8-12GHz, a limiting oxygen index of not less than 26%, a vertical burning rating of at least V-0, a tensile strength of not less than 50MPa, and an elongation at break of not less than 8%.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material of the present invention has excellent mechanical, flame-retardant and controllable electromagnetic shielding properties, and the materials used are basically commercially available, which simplifies the processing, reduces application costs, improves production efficiency, and is suitable for industrial production.

[0028] (2) The present invention successfully solved the problem of coating adsorption of conductive nanofillers on the surface of fiber fabrics, improved the interaction force between conductive coating and fiber and polymer resin, and improved the mechanical properties of composite materials.

[0029] (3) This invention is the first to utilize conductive modified fiber fabrics to prepare laminated composite materials, effectively solving the problem of low electromagnetic shielding efficiency of conductive nanofillers in polymer composite materials. This invention provides a new approach for the high performance and multifunctionality of fiber-reinforced electromagnetic shielding composite materials.

[0030] (4) The final performance of the reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material of the present invention can be controlled by adjusting the type of fiber, the type and quantity of conductive filler, the construction method and morphology of conductive coating, the ratio of conductive modified fiber to non-conductive modified fiber, the type of thermosetting resin, the type and content of flame retardant, the distribution of flame retardant, and the thickness of composite board.

[0031] (5) The reinforced-flame-retardant-electromagnetic shielding thermosetting resin matrix composite material of the present invention has the properties of reinforcement, flame retardancy and electromagnetic shielding, which means that the shielding effectiveness in the X-band (8-12GHz) is not less than 30dB, the limiting oxygen index is not less than 26%, the vertical burning rating reaches V-0 level, the tensile strength is not less than 50Mpa, and the elongation at break is not less than 8%. Attached Figure Description

[0032] Figure 1 This is a diagram illustrating the vertical combustion process of a silver nanowire-modified ramie fiber-reinforced flame-retardant-electromagnetic shielding epoxy resin-based composite material. Detailed Implementation

[0033] The present invention will be further described below with reference to embodiments.

[0034] Example 1: Preparation of ramie fiber fabric modified with silver nanowire coating

[0035] Step 1: The ramie fiber fabric is subjected to low-temperature plasma sputtering treatment in an oxygen atmosphere for 3 minutes to obtain a modified ramie fiber fabric with good surface hydrophilicity.

[0036] Step 2: Under heat baking conditions, a 10 mg / mL silver nanowire solution is sprayed onto the surface of the modified ramie fiber fabric at a spraying density of 2 mg / cm³. 2 The ramie fiber fabric with silver nanowire coating was obtained by vacuum drying at 80℃ for 2 hours.

[0037] Step 3: Dissolve 2 parts of dopamine solution in 1000 mL of deionized water, then dissolve 1 part of tris(hydroxymethyl)aminomethane in the prepared dopamine solution and adjust the pH to about 8.5.

[0038] Step 4: Immerse the modified ramie fiber fabric prepared in Step 2 into the dopamine solution in Step 3, soak for 6 hours at room temperature, wash the modified ramie fiber fabric with deionized water to remove residual dopamine solution, and then dry at 40°C for 10 hours to obtain silver nanowire coated modified ramie fiber fabric with good compatibility.

[0039] Example 2:

[0040] 20 wt% of an intumescent flame retardant and 10 wt% of a curing agent were added to a room-temperature curing epoxy resin and mixed thoroughly. This mixture was then used as an adhesive to impregnate and bond five layers of silver nanowire-coated modified ramie fiber fabric layer by layer. The ratio of the flame-retardant epoxy resin to the ramie fiber fabric was 2:1. Finally, the mixture was cured using a vacuum pressing method, with a negative pressure below 10 Pa, a temperature of 20°C, and a curing time of 48 hours. This resulted in a silver nanowire-coated modified ramie fiber fabric reinforced-flame-retardant-electromagnetic shielding composite material.

[0041] The performance test results are shown in Table 1 below:

[0042] Table 1

[0043]

[0044] The vertical combustion process of the above-mentioned silver nanowire-coated modified ramie fiber fabric reinforced-flame retardant-electromagnetic shielding composite material is as follows: Figure 1 As shown.

[0045] Example 3: Preparation of basalt fiber fabric synergistically modified with titanium carbide / carbon nanotubes

[0046] Step 1: Ultrasonically wash the basalt fiber fabric in ethanol for half an hour, then soak it in a mixed solvent containing 20% ​​KH550 (anhydrous ethanol and water are mixed in a mass ratio of 3:1, the same below), and then react at 50°C for 8 hours to obtain silane-modified basalt fiber fabric.

[0047] Step 2: Titanium carbide and carbon nanotubes are mixed at a 1:1 mass ratio and sprayed onto the substrate. Strong electrostatic adsorption occurs under the positive charge of the silane-amino functional groups, resulting in a total conductive nanofiller loading of 1 mg / cm³. 2 Modified basalt fiber fabric;

[0048] Step 3: Again, using a spraying method, the mixed solvent containing KH550 is sprayed onto the surface of the modified basalt fiber fabric from Step 2. The loading of KH550 is 2% of the fiber mass. The reaction is carried out at 60°C for 1 hour to obtain the titanium carbide / carbon nanotube synergistic modified basalt fiber fabric.

[0049] Example 4:

[0050] 25 wt% of an intumescent flame retardant and 2 wt% of an initiator were added to an unsaturated polyester resin melt and mixed thoroughly to obtain a flame-retardant unsaturated polyester resin. This resin was used as an adhesive to impregnate and bond 10 layers of titanium carbide / carbon nanotube synergistic modified basalt fiber fabric layer by layer. The ratio of the flame-retardant unsaturated polyester resin to the titanium carbide / carbon nanotube synergistic modified basalt fiber fabric was 1.5:1. The mixture was then cured using a vacuum pressing method with a negative pressure below 10 Pa. Curing was first performed at 70℃ for 4 hours, followed by curing at 120℃ for 3 hours. This resulted in a flame-retardant-electromagnetic shielding composite material reinforced with titanium carbide / carbon nanotube synergistic modified basalt fiber fabric.

[0051] The performance test results are shown in Table 2 below:

[0052] Table 2

[0053]

[0054] Example 5: Preparation of Titanium Carbide / Graphene Synergistic Modified Glass Fiber Fabric

[0055] Step 1: Ultrasonically wash the glass fiber fabric in ethanol for half an hour, then soak it in a mixed solvent containing 20% ​​KH550 (anhydrous ethanol and water are mixed in a mass ratio of 3:1, the same below), and then react at 50°C for 8 hours to obtain silane-modified glass fiber fabric.

[0056] Step 2: Titanium carbide and graphene are mixed at a 1:1 mass ratio and sprayed onto the substrate. Under the positive charge of the silane amino functional groups, strong electrostatic adsorption is formed, resulting in a total conductive nanofiller loading of 2.2 mg / cm³. 2 Modified glass fiber fabric;

[0057] Step 3: Again, using a spraying method, the mixed solvent containing KH550 is sprayed onto the surface of the modified glass fiber fabric from Step 2. The loading of KH550 is 3% of the mass of the fiber fabric. The reaction is carried out at 60°C for 1 hour to obtain the titanium carbide / graphene synergistic modified glass fiber fabric.

[0058] Example 6:

[0059] 25 wt% ammonium polyphosphate flame retardant and 20 wt% curing agent were added to a high-temperature curing epoxy resin and mixed evenly to obtain a flame-retardant epoxy resin. This resin was used as an adhesive to impregnate and bond 10 layers of titanium carbide / graphene synergistic modified glass fiber fabric layer by layer. The ratio of the flame-retardant epoxy resin to the titanium carbide / graphene synergistic modified glass fiber fabric was 1.2:1. Finally, the mixture was cured using a vacuum pressing method, with a negative pressure below 10 Pa, a temperature of 140℃, and a curing time of 5 hours. This resulted in a flame-retardant-electromagnetic shielding composite material reinforced with titanium carbide / graphene synergistic modified glass fiber fabric.

[0060] The performance test results are shown in Table 3 below:

[0061] Table 3

[0062]

[0063] Example 7:

[0064] 20 wt% of an intumescent flame retardant and 10 wt% of a curing agent were added to a room-temperature curing epoxy resin and mixed thoroughly to obtain a flame-retardant epoxy resin as an adhesive. Two layers of silver nanowire-coated modified ramie fiber fabric (Example 1) were used as the middle layer, and eight layers of silane-modified basalt fiber fabric (Example 2) were used as the outer layer. The layers were impregnated and bonded together, with the ratio of flame-retardant epoxy resin to fabric being 2:1. Finally, the mixture was cured using a vacuum pressing method, with a negative pressure below 10 Pa, a temperature of 20°C, and a curing time of 48 hours. The resulting flame-retardant-electromagnetic shielding composite material reinforced with silver nanowire-coated modified ramie-basalt fiber fabric was obtained.

[0065] The performance test results are shown in Table 4 below:

[0066] Table 4

[0067]

[0068] In the above embodiments, the tensile strength and elongation at break test standards are GB / T 1447-2005; the oxygen index test standard is ASTM D2863; the vertical burning test standard is ASTM D3801; and the electromagnetic shielding performance is tested according to the waveguide method test standard.

[0069] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material, characterized in that: It includes a flame-retardant modified thermosetting resin matrix and a conductive modified fiber fabric composited in the matrix. The flame-retardant modified thermosetting resin matrix is ​​a thermosetting resin containing flame retardants. The conductive modified fiber fabric is a fiber fabric with conductive nanoparticle surface modification. The fiber fabric includes one or more of ramie fiber fabric, basalt fiber fabric, cotton fiber fabric and glass fiber fabric; The conductive modified fiber fabric has at least one layer, and each layer may be made of the same or different materials.

2. The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material as described in claim 1, characterized in that, The thermosetting resin includes one or more of epoxy resin and unsaturated polyester; The flame retardant includes one or more of inorganic flame retardants, nano flame retardants, and intumescent flame retardants; The flame retardant content in the flame-retardant modified thermosetting resin matrix is ​​10-30 wt%.

3. The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material as described in claim 1, characterized in that, The conductive nanoparticle content in the conductive modified fiber fabric is 0.5-2 mg / cm³. 2 ; The conductive nanoparticles include one or more of graphene, carbon nanotubes, conductive carbon black, metal ions, and titanium carbide.

4. The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material as described in claim 1 or 3, characterized in that, The conductive nanoparticles are attached to the surface of the fiber fabric through low-temperature plasma sputtering, in-situ modification with polydopamine, surface modification with silane coupling agent, or polymer coating modification.

5. The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material as described in claim 1, characterized in that, The conductive modified fiber fabric has multiple layers, and each layer of conductive modified fiber fabric is composited by vacuum lamination and pressing.

6. The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material as described in claim 5, characterized in that, The conductive modified fiber fabric has 3-10 layers.

7. The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material as described in claim 1, characterized in that, The mass ratio of the conductive modified fiber fabric to the flame-retardant modified thermosetting resin matrix is ​​1:1-2.

8. The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material as described in claim 1 or 7, characterized in that, The thickness of the reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material is 1-10 mm.

9. The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material as described in claim 1, characterized in that, Choose from one of the following combinations: (a) The flame-retardant modified thermosetting resin matrix is ​​an epoxy resin containing an intumescent flame retardant; the conductive modified fiber fabric is a silver nanowire coated modified ramie fiber fabric. (b) The flame-retardant modified thermosetting resin matrix is ​​an unsaturated polyester resin containing an intumescent flame retardant; the conductive modified fiber fabric is a titanium carbide / carbon nanotube synergistic modified basalt fiber fabric. (c) The flame-retardant modified thermosetting resin matrix is ​​an epoxy resin containing ammonium polyphosphate flame retardant; the conductive modified fiber fabric is a titanium carbide / graphene synergistic modified glass fiber fabric. (d) The flame-retardant modified thermosetting resin matrix is ​​an epoxy resin containing ammonium polyphosphate flame retardant; the conductive modified fiber fabric is a titanium carbide / graphene synergistic modified glass fiber fabric and a silane modified basalt fiber fabric.

10. The reinforced-flame-retardant-electromagnetic shielding thermosetting resin-based composite material as described in claim 1, characterized in that, The shielding effectiveness in the X-band 8-12GHz is no less than 30dB, the limiting oxygen index is no less than 26%, the vertical burning rating is at least V-0, the tensile strength is no less than 50MPa, and the elongation at break is no less than 8%.

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