Green flame-retardant low-dielectric MXD6 / PPO composite material and preparation method thereof

Abstract

The invention discloses a green flame-retardant low-dielectric MXD6 / PPO composite material and a preparation method thereof, and relates to the technical field of high polymer materials, the composite material comprises the following components by weight: 36-48 parts of MXD6 resin, 20-30 parts of PPO resin, 5-15 parts of aramid chopped fiber, 8-15 parts of hexagonal boron nitride, 3-10 parts of mesoporous silica, 3-8 parts of a compatilizer and 2-4 parts of an auxiliary agent. Through the synergistic effect of all the components and a unique two-step preparation process, the comprehensive performance of the composite material is remarkably improved, so that the composite material realizes perfect balance of ultralow dielectric property, excellent green flame retardant property and good mechanical strength under the condition that no flame retardant is needed; the structure is especially suitable for the fields of 5G communication, high-frequency circuit boards and advanced electronic packaging.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to a green flame-retardant low-dielectric MXD6 / PPO composite material and a preparation method thereof. BACKGROUND

[0002] Under the background of the rapid development of today's electronic information industry, the fifth generation mobile communication technology (5G), millimeter wave radar, high-speed server and artificial intelligence computing equipment are driving electronic components to high frequency, high speed and high integration. This technological evolution puts unprecedentedly stringent requirements on key basic materials. On the one hand, the continuous increase of signal transmission frequency requires that the base material must have stable ultra-low dielectric constant (Dk≤3.0) and extremely low dielectric loss factor (Df≤0.005) to minimize signal transmission delay, attenuation and distortion; on the other hand, the miniaturization and light weight trend of electronic devices requires that the material must have excellent flame retardant performance of UL94-V0 level to ensure safety while maintaining excellent electrical properties, and must have excellent mechanical strength, rigidity and heat resistance to ensure structural stability and soldering performance. The superposition of these multiple performance requirements makes the traditional electronic materials face severe performance bottlenecks.

[0003] Poly(m-xylylene adipamide) (MXD6) is a high-performance semi-crystalline polyamide, which is favored in the engineering plastics field for its excellent mechanical properties, outstanding impact strength, good solvent resistance and excellent processing flow characteristics. However, the intrinsic dielectric constant of MXD6 is relatively high, usually in the range of 3.5-4.0, and its inherent flame retardant performance cannot meet the safety standards of high-end electronic applications, which greatly limits its application in high-frequency communication fields. In contrast, polyphenylene oxide (PPO) exhibits extremely excellent dielectric properties, with a dielectric constant of about 2.55 and a dielectric loss of about 0.0007, as well as excellent heat resistance, which makes it an ideal candidate material for high-frequency applications. However, the inherent high melt viscosity, poor processing flowability, significant stress cracking tendency and sensitivity to certain chemical solvents of PPO make it difficult to be applied alone in the manufacture of complex and precise electronic components. In theory, the dielectric constant of the composite material can be improved by blending MXD6 and PPO. However, MXD6 is a polar polyamide, while PPO is a non-polar polyether, resulting in thermodynamic incompatibility between the two. This incompatibility causes severe phase separation in the simple mechanically blended system, forming a fragile two-phase interface. The fragile interface not only significantly reduces the mechanical properties of the material and becomes a weak link for stress concentration, but also increases the dielectric loss due to the interface polarization effect, ultimately making the comprehensive performance of the blended material, especially the key electrical properties, worse than that of the single component material.

[0004] Further, in order to achieve the necessary flame retardant performance, the traditional halogen-free flame retardant scheme usually relies on a large amount of addition of metal hydroxide and other flame retardants to achieve UL94-V0 level of flame retardant effect. Such a high addition amount inevitably leads to significant deterioration of the dielectric properties of the material, a substantial decrease in the mechanical strength, an increase in the density and a serious deterioration of the processing flowability. In addition, although some emerging low dielectric fillers can effectively reduce the dielectric constant of the material, they often have no contribution to the flame retardant performance or even may have a negative impact, or their own thermal stability cannot withstand high temperature processing environment, making it difficult to maintain stable performance under complex actual application conditions. At the same time, with the increasing global environmental awareness and the increasingly stringent relevant regulations, the requirements for green and halogen-free flame retardant in the field of electronic materials are continuously improving. However, the existing green flame retardant technology often has difficulty in achieving a good balance between flame retardant efficiency, dielectric properties, mechanical properties and processing performance, and often has to sacrifice other performances in order to meet the performance requirements of one aspect. This dilemma of "gaining one and losing another" has become a key technical problem restricting the development of high-performance electronic materials.

[0005] Therefore, how to provide a green flame-retardant low-dielectric MXD6 / PPO composite material, through the synergistic effect between the components and process optimization, to improve the comprehensive performance of the composite material is a technical problem that those skilled in the art urgently need to solve. SUMMARY

[0006] The primary purpose of the present application is to overcome the defects of the prior art and provide a MXD6 / PPO composite material with ultra-low dielectric constant and dielectric loss, high flame retardant grade, high mechanical strength and excellent processing flowability.

[0007] Another purpose of the present application is to provide a preparation method of the above-mentioned composite material. The method ensures that each functional component, especially the shear-sensitive reinforcing fiber, can be dispersed in the matrix in the most optimized form through a unique process flow, especially the "two-step" melt blending combined with the lateral large lead feeding technology, so as to fully play its designed function.

[0008] To achieve the above-mentioned purposes, the technical scheme of the present application is as follows: The first aspect of the present application provides a green flame-retardant low-dielectric MXD6 / PPO composite material, which comprises the following components in parts by weight: 36-48 parts of MXD6 resin, 20-30 parts of PPO resin, 5-15 parts of aramid short-cut fiber, 8-15 parts of hexagonal boron nitride, 3-10 parts of mesoporous silica, 3-8 parts of compatibilizer and 2-4 parts of auxiliary agent.

[0009] In the first aspect, the intrinsic viscosity of the MXD6 resin is 0.8-1.2 dL / g, and the intrinsic viscosity of the PPO resin is 0.4-0.55 dL / g.

[0010] In the first aspect, the aramid short fiber has a length of 3-6 mm and a diameter of 10-15 μm.

[0011] In the first aspect, the hexagonal boron nitride has a flake structure, an average particle size of 5-15 μm, and a thickness of 0.5-2 μm.

[0012] In the first aspect, the mesoporous silica has a pore size of 2-10 nm and a specific surface area of 300-800 m 2 / g.

[0013] In the first aspect, the compatilizer includes at least one of maleic anhydride grafted polyphenylene ether, maleic anhydride grafted polyethylene octene copolymer, and maleic anhydride grafted SEBS.

[0014] In the first aspect, the auxiliary agent includes: 0.2-0.5 parts of a primary antioxidant, 0.3-0.8 parts of a secondary antioxidant, 0.5-1.5 parts of a lubricant, and 0.5-2.0 parts of a black auxiliary agent; the primary antioxidant is a hindered phenolic antioxidant; the secondary antioxidant is a phosphite antioxidant; the lubricant is a stearate or a fatty acid amide lubricant; and the black auxiliary agent is a nylon carrier black masterbatch or a carbon black masterbatch.

[0015] The second aspect of the present application provides a preparation method of the green flame-retardant low-dielectric MXD6 / PPO composite material, which includes: drying MXD6 resin and PPO resin at 100-110 °C for 4-6 h; weighing each component of the green flame-retardant low-dielectric MXD6 / PPO composite material according to the first aspect; adding the dried MXD6 resin, PPO resin, hexagonal boron nitride, mesoporous silica, compatilizer, and auxiliary agent into a high-speed mixer, mixing at a speed of 300-500 rpm at room temperature for 5-10 minutes to obtain a premix; performing first melt extrusion on the premix through a double-screw extruder, pelletizing, and sieving to obtain MXD6 / PPO base masterbatch; drying the MXD6 / PPO base masterbatch at 80-90 °C for 2-3 h; adding the dried MXD6 / PPO base masterbatch into the screw cavity of a double-screw extruder from a main feeding port, and adding aramid short fiber into the screw cavity from a side feeding port to perform second melt extrusion, pelletizing, and sieving to obtain the green flame-retardant low-dielectric MXD6 / PPO composite material.

[0016] In the second aspect, the process parameters of the first melt extrusion include: the temperature of each section of the double screw extruder is 260-270 DEG C for 2-3 sections, 275-285 DEG C for 4-5 sections, 285-295 DEG C for 6-7 sections, 290-300 DEG C for 8-9 sections, and 290-300 DEG C for the die; the screw rotation speed of the double screw extruder is 300-400 rpm; the process parameters of the second melt extrusion include: the temperature of each section of the double screw extruder is 265-275 DEG C for 2-3 sections, 280-290 DEG C for 4-5 sections, 290-295 DEG C for 6-7 sections, 285-295 DEG C for 8-9 sections, and 285-295 DEG C for the die; and the screw rotation speed of the double screw extruder is 250-350 rpm.

[0017] The third aspect of the present application provides an application of the green flame-retardant low-dielectric MXD6 / PPO composite material in high-frequency electronic devices.

[0018] Beneficial effects: The green flame-retardant low-dielectric MXD6 / PPO composite material provided by the present application comprises, in weight parts, 36-48 parts of MXD6 resin, 20-30 parts of PPO resin, 5-15 parts of aramid short-cut fiber, 8-15 parts of hexagonal boron nitride, 3-10 parts of mesoporous silica, 3-8 parts of a compatibilizer, and 2-4 parts of an auxiliary agent; the MXD6 resin and the PPO resin are used as base resins to provide basic mechanical properties and dielectric properties for the composite material; the aramid short-cut fiber is used to improve the mechanical properties of the composite material, and cooperates with the hexagonal boron nitride to build a flame-retardant system, and the hexagonal boron nitride and the mesoporous silica are used to cooperatively reduce the dielectric constant of the composite material; the compatibilizer is used to improve the interfacial bonding force between the components of the raw materials, thereby ensuring the overall uniformity of the composite material; and the auxiliary agent is used to optimize the processing performance and assist in improving the comprehensive performance of the composite material. Through the synergistic effect of the components and the unique two-step process, the composite material has excellent green flame retardancy without any flame retardant, and also has ultra-low dielectric constant and dielectric loss, good mechanical strength and processing performance, and is particularly suitable for 5G communication, high-frequency circuit boards and advanced electronic packaging fields. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0020] Figure 1A flowchart of a preparation method of a green flame-retardant low-dielectric MXD6 / PPO composite material provided by the present application is shown. DETAILED DESCRIPTION

[0021] The advantages and various effects of the present application will be more clearly presented hereinafter in conjunction with specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present application, rather than limit the present application.

[0022] Throughout the specification, unless otherwise specifically indicated, the terms used herein are to be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as generally understood by those skilled in the art to which the present application belongs. If there is a conflict, the present specification takes precedence.

[0023] Unless otherwise specifically indicated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or obtained by existing methods.

[0024] The present application provides a green flame-retardant low-dielectric MXD6 / PPO composite material, which comprises the following components in parts by weight: 36-48 parts of MXD6 resin, 20-30 parts of PPO resin, 5-15 parts of aramid short fiber, 8-15 parts of hexagonal boron nitride, 3-10 parts of mesoporous silica, 3-8 parts of compatibilizer and 2-4 parts of auxiliary agent.

[0025] Specifically, the green flame-retardant low-dielectric MXD6 / PPO composite material provided by the present application comprises the following components in parts by weight: 36-48 parts of MXD6 resin, 20-30 parts of PPO resin, 5-15 parts of aramid short fiber, 8-15 parts of hexagonal boron nitride, 3-10 parts of mesoporous silica, 3-8 parts of compatibilizer and 2-4 parts of auxiliary agent; the MXD6 resin and the PPO resin are used as the base resin to provide the basic mechanical properties and dielectric properties of the composite material; the aramid short fiber is used to improve the mechanical properties of the composite material, and cooperates with the hexagonal boron nitride to build a flame-retardant system, and the hexagonal boron nitride and the mesoporous silica are used to cooperatively reduce the dielectric constant of the composite material; the compatibilizer is used to improve the interfacial bonding force between the components of the raw materials, so as to ensure the overall uniformity of the composite material; and the auxiliary agent is used to optimize the processing performance and assist in improving the comprehensive performance of the composite material. Through the synergistic effect of the components, the composite material provided by the present application still has excellent green flame-retardant property without any flame retardant, and has ultra-low dielectric constant and dielectric loss, as well as good mechanical strength and processability, and is particularly suitable for 5G communication, high-frequency circuit board and advanced electronic packaging fields.

[0026] As one of the embodiments, the MXD6 resin has an intrinsic viscosity of 0.8-1.2 dL / g, and the PPO resin has an intrinsic viscosity of 0.4-0.55 dL / g; the combination of the raw materials in this viscosity range helps to obtain a better phase structure during melt blending.

[0027] The MXD6 resin with an intrinsic viscosity of 0.8-1.2 dL / g and the PPO resin with an intrinsic viscosity of 0.4-0.55 dL / g are blended in the present application, which is one of the core designs for performance breakthrough in the present application. The fundamental advantage lies in creating an ideal rheological environment, which makes the originally high-viscosity PPO phase easy to be broken in the blending process due to its lower molecular weight, so as to be dispersed as a dispersed phase in the continuous phase composed of the higher-viscosity MXD6. This specific structure brings multiple synergistic benefits. First, it greatly increases the interfacial area of the two phases, allowing the compatibilizer PPO-g-MAH to fully play its bridging role, forming a strong and tough interface, thereby efficiently transferring stress between the two phases, combining the rigidity and heat resistance of PPO with the toughness and strength of MXD6, and achieving the balance of rigidity and toughness of the matrix itself; secondly, the high flowability of MXD6 as the continuous phase makes the entire composite system inherit its excellent processing characteristics, significantly improving the melt flowability, making it easy to form complex thin-walled electronic parts, and reducing the processing energy consumption and thermal degradation risk; in addition, a stable and moderately flowable continuous phase also creates favorable conditions for the uniform distribution and directional arrangement of functional fillers such as hexagonal boron nitride and mesoporous silica, ensuring the full play of their functionality. Therefore, this selection of intrinsic viscosity is based on the molecular chain scale, and through precise control of the phase structure, it optimizes the contradiction between compatibility, processability and mechanical properties, and lays a crucial microstructure foundation for achieving a balance between low dielectric, high flame retardance and high performance.

[0028] As one of the embodiments, the aramid short-cut fiber has a length of 3-6 mm and a diameter of 10-15 μm; this specification of fiber can maximize its aspect ratio under the premise of ensuring dispersity, thereby obtaining the best reinforcing effect.

[0029] The para-aramid short fiber with the length of 3-6 mm and the diameter of 10-15 microns is processed into a fluffy fiber by a special process, and then fibrillated by grinding to make the surface fluffy and many microfibrils arranged along the fiber axis, forming a large surface area, having good adsorption, and being able to be well infiltrated and combined with resin and filler, and the size design precisely balances the contradiction between the aspect ratio effect and the processing dispersibility. On the one hand, the length and diameter give the fiber a high aspect ratio of about 200-600, which enables the fiber to effectively form a network in the matrix, and when the material is stressed, the fiber can transfer and bear the load through the large interface area, thereby significantly improving the tensile and impact strength of the material; on the other hand, this length range ensures that the fiber can be smoothly fed and uniformly dispersed in the melt blending, especially in the second step of the mild extrusion process adopted by the application through side feeding, avoiding the problems of entanglement, clumping or excessive breakage of long fibers. In addition, the inherent high heat resistance and carbonization tendency of the fiber of this specification can produce excellent synergistic flame-retardant effect with the ceramic barrier of hexagonal boron nitride, and together build a more dense protective layer.

[0030] As one of the embodiments, the hexagonal boron nitride has a flaky structure, an average particle size of 5-15 microns, and a thickness of 0.5-2 microns; this form of hexagonal boron nitride is easy to form an effective barrier network and a heat conduction path in the matrix.

[0031] The flaky hexagonal boron nitride selected by the application plays a core role in the MXD6 / PPO composite material through a multiple synergistic mechanism due to its average particle size of 5-15 microns and ultra-thin thickness of 0.5-2 microns. First, in terms of flame retardation, the flaky structure interweaves with the carbon layer formed after the aramid short fiber burns, and as a high-temperature-resistant flaky body, it covers and enhances the carbon layer density, and cooperates with the mesoporous silica to stabilize the carbon layer skeleton while the hexagonal boron nitride provides a gas phase barrier, together building an efficient intumescent flame retardant system; second, in terms of functional conduction, the two-dimensional flaky structure can be more uniformly dispersed through the compatible agent PPO-g-MAH which is compatible with the matrix, and form a complementary three-dimensional functional network with spherical mesoporous silica, which can not only improve the in-plane thermal conductivity through phonon transmission, but also reduce dielectric loss by reflecting and scattering electromagnetic waves through the flaky structure and the nano air bubble effect of mesoporous silica.

[0032] As one of the embodiments, the pore size of the mesoporous silica is 2-10 nm, and the specific surface area is 300-800 m 2 / g; the large specific surface area and nanoscale pore are the structural basis for realizing the "physical foaming" effect and significantly reducing the dielectric constant.

[0033] The mesoporous silica selected in the application has a unique nanoscale pore structure (pore size 2-10 nm) and a large specific surface area (300-800 m 2 / g), and forms a multi-level synergistic effect with the MXD6 / PPO composite system. In terms of dielectric properties, the rich nanochannels inside it are equivalent to introducing a large number of stable nanobubbles, which significantly reduces the overall dielectric constant of the material through physical foaming effect, and the large specific surface area forms a dense and stable interface layer through synergistic effect with the compatibilizer, effectively binds the dipole movement, and significantly reduces the dielectric loss; in terms of flame retardant performance, it forms a complementary mechanism with hexagonal boron nitride, mesoporous silica promotes carbon formation and stabilizes the carbon layer skeleton through surface silicon hydroxyl groups, while hexagonal boron nitride provides a shielding layer, together to build a more dense and effective barrier system; in terms of mechanical properties, its nanoscale size and large specific surface area synergize with the PPO-g-MAH compatibilizer to enhance the interfacial bonding force with the polymer matrix, which not only does not cause stress concentration like traditional fillers, but also improves the overall material through interface optimization.

[0034] As one of the embodiments, the compatibilizer includes at least one of maleic anhydride grafted polyphenylene ether, maleic anhydride grafted polyethylene octene copolymer, and maleic anhydride grafted SEBS.

[0035] In this application, maleic anhydride grafted polyphenylene ether (PPO-g-MAH) can most effectively inhibit phase separation, build a dense and stable rigid interface, and thus optimally improve the dimensional stability and rigidity of the alloy, and significantly reduce the dielectric loss, due to its perfect compatibility with the PPO matrix and firm chemical bonding with the MXD6 end group. Maleic anhydride grafted polyethylene octene copolymer (POE-g-MAH) can achieve excellent toughening effect by initiating, terminating silver lines and absorbing a large amount of impact energy in the matrix through its elastomer particles, which can maximally improve the impact strength and fracture toughness of the composite material. Maleic anhydride grafted SEBS (SEBS-g-MAH) can achieve a more excellent balance between the toughness and rigidity of the material, and can bring better heat aging performance, due to its unique microphase separation structure, which provides significant toughening effect while having less impact on the rigidity of the matrix.

[0036] As one of the embodiments, the auxiliary agent includes: 0.2-0.5 parts of primary antioxidant, 0.3-0.8 parts of secondary antioxidant, 0.5-1.5 parts of lubricant, and 0.5-2.0 parts of black auxiliary agent.

[0037] The primary antioxidant is a hindered phenolic antioxidant; the secondary antioxidant is a phosphite antioxidant; the lubricant is a stearate or a fatty acid amide lubricant; and the black auxiliary agent is a nylon carrier black masterbatch or a carbon black masterbatch.

[0038] In the present application, the primary antioxidant is a hindered phenolic antioxidant, including at least one of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid octadecyl ester; the secondary antioxidant is a phosphite antioxidant, including at least one of tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite. The synergistic use of the primary antioxidant and the secondary antioxidant builds a high-efficiency multiple antioxidant protection mechanism for the MXD6 / PPO composite. The primary antioxidant inhibits the initiation and propagation of oxidation reactions by capturing free radicals, effectively interrupts the chain oxidation reaction by providing hydrogen atoms to capture and neutralize the peroxide radicals generated during processing and use. The secondary antioxidant acts as a hydrogen peroxide decomposer, which can convert the generated hydrogen peroxide into stable non-radical products, preventing it from decomposing into new active free radicals. The synergistic effect of the two forms a complementary continuous defense network, the primary antioxidant solves the generated free radicals, and the secondary antioxidant eliminates the source of free radical generation, thereby significantly improving the thermal-oxidative aging resistance of the composite, effectively preventing the degradation and crosslinking of polymer molecular chains, ensuring the stability of the mechanical properties and dielectric properties of the composite during high-temperature processing and long-term use, and prolonging the service life of the product.

[0039] The lubricant is a stearate or fatty acid amide lubricant, preferably at least one of calcium stearate, zinc stearate, ethylene bis-stearamide (EBS). Calcium stearate as a lubricant, with its excellent metal ion characteristics, forms a stable lubricating layer between the polymer and the metal surface of the processing equipment, which can significantly improve the melt flowability and demolding performance; zinc stearate can provide more durable lubrication protection while maintaining good external lubrication effect, and has certain weather resistance contribution; and the double amide groups in the molecular structure of EBS make it have excellent internal and external lubrication functions, which can effectively reduce the melt viscosity, improve the filler dispersion, and significantly improve the surface finish of the product.

[0040] The nylon carrier black masterbatch has excellent compatibility with the MXD6 matrix, which can achieve efficient and uniform dispersion of carbon black pigment, ensure that the product has a deep and uniform black appearance, and avoid color difference or surface defects caused by uneven dispersion; and the carbon black masterbatch can achieve the same deep black effect with a lower addition amount due to its higher carbon black content and extreme coloring power.

[0041] Based on a general inventive concept, as shown in Figure 1 The present application provides a preparation method of a green flame-retardant low-dielectric MXD6 / PPO composite material, which comprises the following steps: S1, dry MXD6 resin and PPO resin at 100-110℃ for 4-6h; S2, according to the first aspect, the green flame-retardant low-dielectric MXD6 / PPO composite material is weighed with each component of raw materials; S3, after drying, MXD6 resin, PPO resin, hexagonal boron nitride, mesoporous silica, compatibilizer and auxiliary are added to the high-speed mixer, mixed at room temperature at a speed of 300-500 rpm for 5-10 minutes to obtain a premix material; S4, the premix material is subjected to first melt extrusion by a double screw extruder, granulated, and sieved to obtain MXD6 / PPO base masterbatch; wherein the process parameters of the first melt extrusion include: the temperature of each section of the double screw extruder is 260-270℃ for 2-3 sections, 275-285℃ for 4-5 sections, 285-295℃ for 6-7 sections, 290-300℃ for 8-9 sections, and the die head is 290-300℃; the screw speed of the double screw extruder is 300-400 rpm; S5, the MXD6 / PPO base masterbatch is dried at 80-90℃ for 2-3h; S6, the dried MXD6 / PPO base masterbatch is added to the screw cavity of the double screw extruder from the main feeding port, and aramid short-cut fiber is added to the screw cavity from the side feeding port, and second melt extrusion is carried out, granulated, and sieved to obtain a green flame-retardant low-dielectric MXD6 / PPO composite material; Wherein, the process parameters of the second melt extrusion include: the temperature of each section of the double screw extruder is 265-275℃ for 2-3 sections, 280-290℃ for 4-5 sections, 290-295℃ for 6-7 sections, 285-295℃ for 8-9 sections, and the die head is 285-295℃, and the screw speed of the double screw extruder is 250-350 rpm.

[0042] Specifically, the application provides a preparation method of a green flame-retardant low-dielectric MXD6 / PPO composite material. First, the components of raw materials are weighed according to preset proportions, then the weighed MXD6 resin, PPO resin, hexagonal boron nitride, mesoporous silicon dioxide, a compatibilizer and an additive are uniformly mixed to obtain a premix, and the premix is placed in a double-screw extruder to perform first melt extrusion, granulation and sieving, so as to obtain MXD6 / PPO base granules. Then, the dried MXD6 / PPO base granules are added to the double-screw extruder from a main feeding port, and aramid short fibers are added to the double-screw extruder from a side feeding port to perform second melt extrusion, granulation and sieving, so as to obtain the green flame-retardant low-dielectric MXD6 / PPO composite material with uniform particles. The application performs twice melt extrusion, which not only effectively protects the integrity and aspect ratio of the aramid short fibers, but also significantly improves the comprehensive performance of the composite material, so that the composite material can be widely applied to the fields of 5G communication, high-frequency circuit boards and advanced electronic packaging.

[0043] Based on the overall inventive concept, the application also provides an application of the green flame-retardant low-dielectric MXD6 / PPO composite material in a high-frequency electronic device.

[0044] The application will be further described in conjunction with specific examples. It should be understood that the examples are only used to illustrate the application and not to limit the scope of the application. The experimental methods in the following examples are not specified, and the methods are generally determined according to national standards. If there is no corresponding national standard, the methods are determined according to the general international standards, conventional conditions, or the conditions recommended by the manufacturers.

[0045] The raw materials used in the examples and comparative examples are as follows: MXD6 resin: Mitsubishi Chemical High Performance MXD6 S6007; PPO resin: Saudi Basic Industries PPO-646; Mesoporous silicon dioxide: Xianfeng Nanometer Mesoporous Silica XFF48; Hexagonal boron nitride: Henan Nitrogen Boron Technology PBN700; Aramid short fibers: Jiangxi Suobang Aramid Short Fibers; Main antioxidant: Tetra [beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester, BASF antioxidant 1010; Auxiliary antioxidant: Tris (2, 4-di-tert-butylphenyl) phosphite, BASF antioxidant 168; Compatibilizer: Chingjie Plastic Maleic Anhydride Grafted PPO; Lubricant: Japan Kawakami EBS-SF; Black additive: Nylon carrier black masterbatch, Jiucai Chemical Nylon Carrier High Gloss Black Masterbatch PA8183.

[0046] Example 1 The green flame-retardant low-dielectric MXD6 / PPO composite material of this example comprises the following components in parts by weight: MXD6 resin 36.5 parts, PPO resin 20 parts, compatibilizer 8 parts, primary antioxidant 0.2 parts, secondary antioxidant 0.3 parts, aramid short-cut fiber 15 parts, hexagonal boron nitride 15 parts, mesoporous silica 3 parts, lubricant 1.5 parts, black auxiliary agent 0.5 parts.

[0047] The preparation method of the green flame-retardant low-dielectric MXD6 / PPO composite material described above has the following steps: (1) Dry the MXD6 resin and PPO resin in a blast oven at 100°C for 6 hours to remove moisture.

[0048] (2) According to the above weight parts, take each component of the raw materials, and put the dried MXD6 resin, PPO resin, compatibilizer, antioxidant, lubricant, black auxiliary agent, hexagonal boron nitride and mesoporous silica into a high-speed mixer together, mix at a speed of 300 rpm for 10 minutes at room temperature to obtain a premix material.

[0049] (3) Set the process parameters of the twin-screw extruder: the melt extrusion temperature of each section of the twin-screw extruder is: 260°C for sections 2-3, 275°C for sections 4-5, 285°C for sections 6-7, 290°C for sections 8-9, and 290°C for the die. The screw speed of the twin-screw extruder is 300 rpm.

[0050] (4) The premix material is added to the screw cavity of the twin-screw extruder from the main feeding port of the twin-screw extruder, and is subjected to sufficient mixing, shearing and plasticizing in the twin-screw extruder to uniformly disperse each component. The material extruded from the twin-screw extruder is granulated by water-cooled pull bars and a granulator to obtain MXD6 / PPO base masterbatch.

[0051] (5) Dry the MXD6 / PPO base masterbatch in a blast oven at 80°C for 3 hours to remove moisture.

[0052] (6) Set the process parameters of the twin-screw extruder: the melt extrusion temperature of each section of the twin-screw extruder is: 265°C for sections 2-3, 280°C for sections 4-5, 290°C for sections 6-7, 285°C for sections 8-9, and 285°C for the die. The screw speed of the twin-screw extruder is 250 rpm.

[0053] (7) The dry MXD6 / PPO base masterbatch is added into the screw cavity of the twin-screw extruder from the main feeding port of the twin-screw extruder, and the aramid short-cut fiber is added into the screw cavity of the twin-screw extruder from the side feeding port of the twin-screw extruder. The components are uniformly dispersed through sufficient mixing, shearing and plasticizing in the twin-screw extruder. The material extruded from the twin-screw extruder is granulated again by the water-cooled puller and the granulator to obtain the green flame-retardant low-dielectric MXD6 / PPO composite material.

[0054] Example 2 The green flame-retardant low-dielectric MXD6 / PPO composite material of the present example comprises the following components in parts by weight: MXD6 resin 36.5 parts, PPO resin 20 parts, compatibilizer 8 parts, primary antioxidant 0.2 parts, secondary antioxidant 0.3 parts, aramid short-cut fiber 8 parts, hexagonal boron nitride 15 parts, mesoporous silica 10 parts, lubricant 1.5 parts, and black additive 0.5 parts.

[0055] The preparation method of the green flame-retardant low-dielectric MXD6 / PPO composite material described above comprises the following steps:

[0056] Example 3 The green flame-retardant low-dielectric MXD6 / PPO composite material of the present example comprises the following components in parts by weight: MXD6 resin 40.1 parts, PPO resin 25 parts, compatibilizer 6 parts, primary antioxidant 0.4 parts, secondary antioxidant 0.5 parts, aramid short-cut fiber 10 parts, hexagonal boron nitride 10 parts, mesoporous silica 6 parts, lubricant 1 part, and black additive 1 part.

[0057] The preparation method of the green flame-retardant low-dielectric MXD6 / PPO composite material described above comprises the following steps: (1) The MXD6 resin and the PPO resin are dried in a blast oven at 105°C for 5 hours to remove moisture.

[0058] (2) The raw material components are weighed according to the above weight parts. The dried MXD6 resin, PPO resin, compatibilizer, antioxidant, lubricant, black additive, hexagonal boron nitride and mesoporous silica are put into a high-speed mixer together, mixed at a speed of 400 rpm for 7 minutes at room temperature to obtain a premix material.

[0059] (3) The process parameters of the twin-screw extruder are set. The temperature of the melt extrusion of each section of the twin-screw extruder is as follows: 265°C for sections 2-3, 280°C for sections 4-5, 290°C for sections 6-7, 295°C for sections 8-9, and 295°C for the die. The screw speed of the twin-screw extruder is 350 rpm.

[0060] (4) The premixed materials are added into the screw cavity of the twin-screw extruder from the main feeding port of the twin-screw extruder, and the components are uniformly dispersed in the twin-screw extruder through sufficient mixing, shearing and plasticizing. The material extruded from the twin-screw extruder is granulated by the water-cooled puller and the granulator to obtain the MXD6 / PPO base masterbatch.

[0061] (5) The MXD6 / PPO base masterbatch is dried in the blast oven at 85°C for 2.5 hours to remove the moisture.

[0062] (6) The process parameters of the twin-screw extruder are set, and the temperature of the melt extrusion of each section of the twin-screw extruder is 270°C for sections 2-3, 285°C for sections 4-5, 285°C for sections 6-7, 285°C for sections 8-9, and 290°C for the die. The screw rotation speed of the twin-screw extruder is 300 rpm.

[0063] (7) The dried MXD6 / PPO base masterbatch is added into the screw cavity of the twin-screw extruder from the main feeding port of the twin-screw extruder, and the aramid short-cut fiber is added into the screw cavity of the twin-screw extruder from the side feeding port of the twin-screw extruder. The components are uniformly dispersed in the twin-screw extruder through sufficient mixing, shearing and plasticizing. The material extruded from the twin-screw extruder is granulated by the water-cooled puller and the granulator to obtain the final green flame-retardant low-dielectric MXD6 / PPO composite material.

[0064] Comparative Example 1 The green flame-retardant low-dielectric MXD6 / PPO composite material of the present comparative example comprises the following components in parts by weight: MXD6 resin 46.6 parts, PPO resin 28.5 parts, compatibilizer 6 parts, primary antioxidant 0.4 part, secondary antioxidant 0.5 part, hexagonal boron nitride 10 parts, mesoporous silica 6 parts, lubricant 1 part, and black additive 1 part.

[0065] The preparation method of the green flame-retardant low-dielectric MXD6 / PPO composite material is as follows: the components are weighed according to the weight parts of each component of the raw materials of the present comparative example, and the process parameters are the same as those of Example 3.

[0066] Comparative Example 2 The green flame-retardant low-dielectric MXD6 / PPO composite material of the present comparative example comprises the following components in parts by weight: MXD6 resin 43.9 parts, PPO resin 27.2 parts, compatibilizer 6 parts, primary antioxidant 0.4 part, secondary antioxidant 0.5 part, hexagonal boron nitride 10 parts, aramid short-cut fiber 10 parts, lubricant 1 part, and black additive 1 part.

[0067] The preparation method of the green flame-retardant low-dielectric MXD6 / PPO composite material is as follows: the components are weighed according to the weight parts of each component of the raw materials of the present comparative example, and the process parameters are the same as those of Example 3.

[0068] Comparative Example 3 The green flame-retardant low-dielectric MXD6 / PPO composite material of the present comparative example comprises the following components in parts by weight: MXD6 resin 46.6 parts, PPO resin 28.5 parts, compatibilizer 6 parts, primary antioxidant 0.4 parts, secondary antioxidant 0.5 parts, mesoporous silica 6 parts, aramid short-cut fiber 10 parts, lubricant 1 part, black additive 1 part.

[0069] The preparation method of the green flame-retardant low-dielectric MXD6 / PPO composite material described above, the components are weighed according to the weight parts of the raw materials of the present comparative example, and the process parameters are the same as those of Example 3.

[0070] Comparative Example 4 The green flame-retardant low-dielectric MXD6 / PPO composite material of the present comparative example comprises the following components in parts by weight: MXD6 resin 46.6 parts, PPO resin 28.5 parts, compatibilizer 6 parts, primary antioxidant 0.4 parts, secondary antioxidant 0.5 parts, mesoporous silica 6 parts, aramid short-cut fiber 10 parts, lubricant 1 part, black additive 1 part.

[0071] The preparation method of the green flame-retardant low-dielectric MXD6 / PPO composite material described above, the steps are as follows: (1) The MXD6 resin and PPO resin are dried in a blast oven at 105°C for 5 hours to remove moisture.

[0072] (2) The raw material components are weighed according to the weight parts described above, and the dried MXD6 resin, PPO resin, compatibilizer, antioxidant, lubricant, black additive, hexagonal boron nitride and mesoporous silica are put into a high-speed mixer together, mixed at a speed of 400 rpm for 7 minutes at room temperature to obtain a premix material.

[0073] (3) The process parameters of the twin-screw extruder are set, and the temperature of the melt extrusion of each section of the twin-screw extruder is: 2-3 sections 265°C, 4-5 sections 280°C, 6-7 sections three zones 290°C, 8-9 sections 295°C, die 295°C; the screw speed of the twin-screw extruder is 350 rpm.

[0074] (4) The premix material is added into the screw cavity of the twin-screw extruder from the main feeding port of the twin-screw extruder, and the aramid short-cut fiber is added into the screw cavity of the twin-screw extruder from the side feeding port of the twin-screw extruder, and the components are uniformly dispersed through sufficient mixing, shearing and plasticizing in the twin-screw extruder. The material extruded from the twin-screw extruder is granulated by water-cooled puller and granulator to obtain the final green flame-retardant low-dielectric MXD6 / PPO composite material.

[0075] Comparative Example 5 The green flame-retardant low-dielectric MXD6 / PPO composite material of the present comparative example comprises the following components in parts by weight: MXD6 resin 48.2 parts, PPO resin 30 parts, compatibilizer 3 parts, primary antioxidant 0.5 parts, secondary antioxidant 0.8 parts, aramid short fibers 8 parts, hexagonal boron nitride 5 parts, mesoporous silica 3 parts, lubricant 0.5 parts, black additive 2 parts.

[0076] The preparation method of the green flame-retardant low-dielectric MXD6 / PPO composite material described above has the following steps: (1) Dry the MXD6 resin and PPO resin in a blast oven at 110°C for 4 hours to remove moisture.

[0077] (2) According to the above weight parts, the components of the raw materials are weighed, and the dried MXD6 resin, PPO resin, compatibilizer, antioxidant, lubricant, black additive, hexagonal boron nitride and mesoporous silica are put into a high-speed mixer together, mixed at a speed of 500 rpm at room temperature for 5 minutes to obtain a premix material.

[0078] (3) Set the process parameters of the twin-screw extruder, and the melt extrusion temperature of each section of the twin-screw extruder is: 270°C for sections 2-3, 285°C for sections 4-5, 295°C for sections 6-7, 300°C for sections 8-9, and the die temperature is 300°C; the screw speed of the twin-screw extruder is 400 rpm.

[0079] (4) The premix material is added to the screw cavity of the twin-screw extruder from the main feeding port of the twin-screw extruder, and the components are uniformly dispersed through sufficient mixing, shearing and plasticizing in the twin-screw extruder. The material extruded by the twin-screw extruder is granulated by water-cooled bars and a granulator to obtain MXD6 / PPO base masterbatch.

[0080] (5) Dry the MXD6 / PPO base masterbatch in a blast oven at 90°C for 2 hours to remove moisture.

[0081] (6) Set the process parameters of the twin-screw extruder, and the melt extrusion temperature of each section of the twin-screw extruder is: 275°C for sections 2-3, 290°C for sections 4-5, 295°C for sections 6-7, 295°C for sections 8-9, and the die temperature is 295°C; the screw speed of the twin-screw extruder is 350 rpm.

[0082] (7) The dry MXD6 / PPO base masterbatch is added into the screw cavity of the twin-screw extruder from the main feeding port of the twin-screw extruder, and the aramid short fiber is added into the screw cavity of the twin-screw extruder from the side feeding port of the twin-screw extruder, and the components are uniformly dispersed through sufficient mixing, shearing and plasticizing in the twin-screw extruder. The material extruded by the twin-screw extruder is granulated by water-cooled puller and granulator again to obtain the final green flame-retardant low-dielectric MXD6 / PPO composite material.

[0083] The green flame-retardant low-dielectric MXD6 / PPO composite material prepared above is made into a sample bar for testing, and the test results are shown in Table 1, and the specific test standards are as follows: Tensile property test: the test standard is ISO 527, and the tensile rate is 50 mm / min.

[0084] Bending property test: the test standard is ISO-178, and the bending rate is 2 mm / min.

[0085] Charpy notched impact strength: the test standard is ISO-179.

[0086] Heat distortion temperature: the test standard is ISO 75-2, and the test bending stress is 1.8 MPa.

[0087] Flame retardant property test: the test standard is UL 94, and the test sample thickness is 3.2 mm.

[0088] Dielectric property test: the test standard is ISO 6721-2, and the parallel plate electrode method is used to measure at a frequency of 1 GHz.

[0089] Table 1 Test results From the above experimental data, it can be seen that Example 1 exhibits the characteristics of a high reinforcement system, and the combination of 15 parts of aramid short fiber and 15 parts of hexagonal boron nitride, together with the interfacial strengthening effect of 8 parts of a compatibilizer, makes the material perform outstandingly in terms of mechanical properties, with a tensile strength of 105 MPa and a bending strength of 155 MPa, while maintaining a good impact toughness of 10.5 kJ / m 2 In terms of flame retardant properties, the formulation successfully passed the UL94-V0 level certification, and the heat distortion temperature reached 178°C, fully demonstrating the effect of a high content reinforcement system on the comprehensive performance of the material. However, the formulation performs relatively weakly in terms of dielectric properties, with a dielectric constant of 2.78, which is directly related to the addition of only 3 parts of mesoporous silica, indicating that while pursuing mechanical properties, appropriate balance of dielectric properties is also needed.

[0090] The formulation adjustment of Example 2 reflects the emphasis on dielectric performance, increasing mesoporous silica to 10 parts while reducing aramid short fibers to 8 parts. This adjustment brings significant improvement in dielectric performance, with a dielectric constant of 2.68, making it the best in the series in terms of dielectric performance. However, this optimization comes at the cost of mechanical performance, especially impact strength, which drops to 8.8kJ / m 2 , reflecting the weakening of the reinforcing system's impact on material toughness. This result shows the balance between different performance indicators in material design.

[0091] The success of Example 3 lies in breaking through the performance balance, by precisely adjusting the ratio of base resin to 40.1 parts of MXD6 resin and 25 parts of PPO resin, and using a combination of 6 parts of mesoporous silica and 10 parts of hexagonal boron nitride functional fillers, together with a reinforcing system of 10 parts of aramid short fibers, achieving a synergistic optimization of various performance indicators. This formulation not only maintains a tensile strength of 102MPa and an impact toughness of 10.2kJ / m 2 , but also achieves a low dielectric constant of 2.72 and a low dielectric loss of 0.0040, with stable flame retardant performance reaching UL94-V0 level, and a heat distortion temperature of 180℃. This comprehensive excellent performance proves the advantages of this formulation in component synergy.

[0092] After completely removing aramid short fibers in Comparative Example 1, the impact performance of the material significantly decreases, with impact strength dropping from 10.2kJ / m 2 to 5.0kJ / m 2 , a decrease of 51%, proving the core role of aramid short fibers in improving material toughness, and its flame retardant grade from UL94-V0 to UL94-V1, indicating the synergistic effect of aramid short fibers in the flame retardant system.

[0093] After completely removing mesoporous silica in Comparative Example 2, its dielectric constant rises to 2.95, significantly higher than other examples, verifying the mechanism of mesoporous silica in reducing the dielectric constant of the material.

[0094] The complete absence of hexagonal boron nitride in Comparative Example 3 greatly reduces the flame retardant performance of the material to only UL94-V2 level, proving the important role of hexagonal boron nitride in building a flame retardant system.

[0095] Comparative Example 4 uses a one-step process, and its mechanical performance indicators are lower than Example 3 which uses a two-step process, with impact strength decreasing by about 17%, highlighting the advantages of the two-step process in protecting fiber integrity.

[0096] Comparative Example 5 verifies the importance of formula balance from the negative side. The method of increasing the MXD6 resin content to 48.2 parts and reducing the amount of functional filler results in a decrease in the comprehensive performance of the material, especially the flame retardant level only reaches UL94-V1 level, indicating that excessive matrix resin will affect the functional balance of the material system.

[0097] In summary, through systematic experimental research, the technical advantages of the present application have been fully verified. Among them, Example 3 is the optimal implementation scheme, through the matrix ratio of 40.1 parts of MXD6 resin and 25 parts of PPO resin, 6 parts of mesoporous silica and 10 parts of hexagonal boron nitride functional filler combination, and 10 parts of aramid short fiber reinforcement system, combined with optimized process conditions, the best balance between mechanical properties, dielectric properties, flame retardant properties and heat resistance of the material is achieved. The formula maintains 102MPa tensile strength and 10.2kJ / m 2 impact toughness, realizes low dielectric constant of 2.72 and V0 level flame retardant, successfully solves the technical difficulties that traditional electronic materials are difficult to balance low dielectric, high flame retardant and good mechanical properties, and provides an ideal material solution for high-frequency communication equipment and electronic packaging field.

[0098] Compared with the prior art, the present application has the following advantages: (1) Excellent low dielectric properties: based on the synergistic dielectric reduction principle of multi-scale and multi-mechanism, the present application does not rely on a single component or a single mechanism in reducing the dielectric constant and dielectric loss, but builds an innovative system with multi-scale and multi-mechanism synergistic effect. The mesoporous silica used in the present application has the core characteristics of precisely controlled nanoscale pore structure (pore size 2-10 nm) and extremely high specific surface area (300-800 m 2 / g). This unique structure plays a dual key role in the system. On the one hand, the bulk effect (nanometer air bubble), which is filled with a large number of nanometer-scale air (dielectric constant ≈1) inside, is equivalent to uniformly distributing countless nanoscale pores in the composite material. When electromagnetic waves pass through the material, these low-dielectric pores effectively reduce the polarization ability of the material, thereby significantly reducing the overall dielectric constant of the composite material. This effect is far superior to that of solid silica. On the other hand, the interface effect, the huge specific surface area means that there is a large interface area between it and the polymer matrix. Through the surface modification of the compatibilizer and its good interaction with the matrix, a tightly bonded and defect-free interface layer can be formed. This high-quality interface can effectively bind dipoles and reduce the occurrence of interfacial polarization, thereby significantly reducing the dielectric loss factor (Df), which is crucial for signal integrity at high frequencies.

[0099] The hexagonal boron nitride used in the application has the core feature of two-dimensional layered shielding and heat conduction auxiliary effect. As a two-dimensional sheet material, the hexagonal boron nitride assumes the ability of a functional shielding layer in the dielectric performance optimization of the application. It can be oriented and arranged in the matrix to form a multi-layer barrier structure. This structure can produce multiple reflections and scattering of incident electromagnetic waves, effectively prolonging the transmission path of the electromagnetic waves and increasing the transmission resistance, thereby to a certain extent, auxiliary reducing the dielectric response of the material. In addition, it is an excellent heat conductor, and its introduction helps to timely conduct the heat generated by the material during high-frequency operation, avoiding the deterioration of dielectric performance caused by local overheating, and ensuring the dielectric stability of the material in real working conditions from another dimension.

[0100] Through mesoporous silica and hexagonal boron nitride, a multi-scale and multi-mechanism synergistic dielectric reduction system from "nanoscale" to "micron" to "two-dimensional sheet" can be formed in the application. They respectively introduce low dielectric phase, optimize the interface state, and construct electromagnetic shielding network, etc. to jointly act from different physical levels, realize the precise control and synergistic optimization of the dielectric performance of the composite material, which is the fundamental reason for realizing ultra-low dielectric constant (which can be as low as 2.6-2.9) and ultra-low dielectric loss (which can be as low as 0.003-0.005).

[0101] (2) High-efficiency and environmentally-friendly flame-retardant performance: based on the synergistic flame-retardant mechanism of the dense shielding carbon layer, the flame-retardant property of the application is not realized by the traditional high-addition amount flame retardant, but is derived from the clever synergistic flame-retardant design between the functional filler and the reinforcing fiber. On the one hand, the skeleton porcelain effect of hexagonal boron nitride, at the initial stage of combustion, the hexagonal boron nitride sheet layer will migrate to the surface of the material, and form a dense, continuous and high-thermal-stability ceramic protective layer through sintering and accumulation. The protective layer can effectively isolate the transmission of oxygen and heat to the inside, and block the outward overflow of the internal combustible pyrolysis products. On the other hand, the carbonization and reinforcement effect of aramid short fibers, aramid short fibers are inherently flame-retardant materials, and will rapidly carbonize at high temperatures to form an expanded carbon layer. The carbon layer and the ceramic layer formed by the hexagonal boron nitride are interwoven and combined with each other, and the carbon layer of the aramid short fibers provides a firm support skeleton for the hexagonal boron nitride, and the hexagonal boron nitride sheet layer covers and strengthens the carbon layer structure like tiles, and the two form a more solid, dense and difficult-to-break "barrier system". This "gas-solid" synergistic flame-retardant mechanism enables the material to achieve the highest flame-retardant level of UL94-V0 at a very low total addition amount (much lower than traditional inorganic hydroxides), while avoiding the serious deterioration of dielectric and mechanical properties caused by adding a large amount of flame retardants.

[0102] (3) High mechanical properties and processability: Based on the double protection of interface compatibilization and process protection, on the one hand, interface compatibilization, through the selection of a suitable compatibilizer, a firm chemical bridge is formed at the interface of MXD6 and PPO, greatly improving the compatibility and eliminating the performance short board caused by phase separation, so that the stress can be effectively transmitted between the two phases. On the other hand, process protection, the unique "two-step" preparation process, the core is to protect the shear-sensitive aramid short fibers. By introducing the fibers in the second step in the side feeding mode, the shear damage of the screw to the fibers is minimized, and the designed length-diameter ratio of the fibers is completely retained, so that the reinforcing and toughening efficiency of the fibers is maximized.

[0103] Finally, it should also be noted that the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or apparatus that includes a series of elements not only includes those elements, but also includes other elements not explicitly listed, or inherent to such a process, method, article or apparatus.

[0104] Although preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0105] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A green flame-retardant low-dielectric MXD6 / PPO composite material, characterized in that, The composite comprises the following components in parts by weight: MXD6 resin 36-48 parts, PPO resin 20-30 parts, aramid short fibers 5-15 parts, hexagonal boron nitride 8-15 parts, mesoporous silica 3-10 parts, compatibilizer 3-8 parts and auxiliary agent 2-4 parts. The auxiliary agent is composed of antioxidant, lubricant and black auxiliary agent.

2. Green flame-retardant low-dielectric MXD6 / PPO composite material according to claim 1, characterized in that, The MXD6 resin has a specific viscosity of 0.8-1.2 dL / g, and the PPO resin has a specific viscosity of 0.4-0.55 dL / g.

3. Green flame-retardant low-dielectric MXD6 / PPO composite material according to claim 1, characterized in that, The aramid short fibers have a length of 3-6 mm and a diameter of 10-15 μm.

4. Green flame-retardant low-dielectric MXD6 / PPO composite material according to claim 1, characterized in that, The hexagonal boron nitride has a flaky structure, an average particle size of 5-15 μm and a thickness of 0.5-2 μm.

5. Green flame retardant low dielectric MXD6 / PPO composite material according to claim 1, characterized in that, The mesoporous silica has a pore size of 2-10 nm, a specific surface area of 300-800 m 2 / g.

6. Green flame retardant low dielectric MXD6 / PPO composite material according to claim 1, characterized in that, The compatibilizer comprises at least one of maleic anhydride grafted polyphenyl ether, maleic anhydride grafted polyethylene octene copolymer and maleic anhydride grafted SEBS.

7. Green flame retardant low dielectric MXD6 / PPO composite material according to claim 1, characterized in that, The antioxidant comprises primary antioxidant and secondary antioxidant; the auxiliary agent is composed of the following components in parts by weight: primary antioxidant 0.2-0.5 parts, secondary antioxidant 0.3-0.8 parts, lubricant 0.5-1.5 parts and black auxiliary agent 0.5-2.0 parts; The primary antioxidant is a hindered phenolic antioxidant; The secondary antioxidant is a phosphite antioxidant; The lubricant is a stearate or fatty acid amide lubricant; The black auxiliary agent is a nylon carrier black masterbatch or carbon black masterbatch.

8. A process for the preparation of green flame-retardant low-dielectric MXD6 / PPO composite material, characterized in that, The preparation method comprises: drying MXD6 resin and PPO resin at 100-110℃ for 4-6 h; The green flame-retardant low-dielectric MXD6 / PPO composite material according to any one of claims 1-7 is weighed with each component of raw materials; After drying, the MXD6 resin, PPO resin, hexagonal boron nitride, mesoporous silica, compatibilizer and auxiliary agent are added into a high-speed mixer, mixed at a speed of 300-500 rpm at room temperature for 5-10 min to obtain a premix; The premix is subjected to first melt extrusion by a double-screw extruder, pelletized, sieved to obtain MXD6 / PPO base masterbatch; The MXD6 / PPO base masterbatch is dried at 80-90℃ for 2-3 h; The dried MXD6 / PPO base masterbatch is added into the screw cavity of a double-screw extruder from a main feeding port, and aramid short fibers are added into the screw cavity from a side feeding port, subjected to second melt extrusion, pelletized, sieved to obtain the green flame-retardant low-dielectric MXD6 / PPO composite material.

9. The process for the preparation of green flame-retardant low-dielectric MXD6 / PPO composites according to claim 8, characterized in that, The process parameters of the first melt extrusion include: the temperature of each section of the double-screw extruder is 260-270℃ for sections 2-3, 275-285℃ for sections 4-5, 285-295℃ for sections 6-7, 290-300℃ for sections 8-9 and 290-300℃ for the die; and the screw rotation speed of the double-screw extruder is 300-400 rpm. The process parameters of the second melt extrusion include: the temperature of each section of the double-screw extruder is 265-275 DEG C for 2-3 sections, 280-290 DEG C for 4-5 sections, 290-295 DEG C for 6-7 sections, 285-295 DEG C for 8-9 sections, and 285-295 DEG C for the die; and the screw rotation speed of the double-screw extruder is 250-350 rpm.

10. The use of the green flame-retardant low-dielectric MXD6 / PPO composite material as claimed in any one of claims 1-7 in high-frequency electronic devices.

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