Low-dielectric lightweight functional material as well as preparation method and application thereof

Abstract

The invention relates to a low-dielectric lightweight functional material as well as a preparation method and application thereof. The low-dielectric lightweight functional material comprises the following raw materials in parts by weight: 40-50 parts of high isotactic polypropylene, 10-30 parts of low isotactic polypropylene, 10-20 parts of hollow glass beads, 2-4 parts of thermoplastic hollow polymer microspheres, 15-25 parts of glass fibers and 3-20 parts of a processing aid. According to the low-dielectric lightweight functional material, the glass fibers are introduced into a system of the hollow glass beads and the thermoplastic hollow polymer beads, and the glass fibers, the hollow glass beads and the thermoplastic hollow polymer beads are synergistically compounded into a blended matrix formed by the high-isotactic PP and the low-isotactic PP, so that a'multi-stage hollow structure-polymer matrix 'composite system is constructed, and collaborative optimization of low dielectric, high strength and light weight is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, and in particular to a low-dielectric lightweight functional material and a preparation method and application thereof. BACKGROUND

[0002] In the field of modern electronic and electrical, aerospace and high-end communication equipment, the structural materials are required to be lightweight, high-strength and low-dielectric. Although traditional engineering plastics such as polypropylene (PP) have good processing performance and cost advantages, their mechanical strength and dielectric properties are difficult to meet the application requirements of high-frequency and high-integration electronic devices. Especially in the fields of 5G communication, millimeter wave radar and satellite structural parts, the materials need to have a low dielectric constant (ε < 3.0) to reduce signal transmission delay and loss, while maintaining sufficient tensile strength and rigidity to support complex structures.

[0003] In the prior art, in order to reduce the dielectric constant, hollow microbeads (such as glass microbeads, polymer microbeads) or porous structures are often used, but such methods often result in a significant decrease in material strength, making it difficult to achieve both low dielectric and high strength.

[0004] Therefore, there is an urgent need to provide a functional material that meets the three performance requirements of low dielectric, high strength and lightweight. SUMMARY

[0005] In order to solve the technical problem that the mechanical strength of the existing lightweight material is severely reduced during the process of reducing the dielectric constant, the purpose of the present application is to provide a low-dielectric lightweight functional material and a preparation method and application thereof, which can maintain low density (density < 0.90 g / cm 3 , low dielectric constant (dielectric constant ε < 3.0) and excellent mechanical strength at the same time.

[0006] To this end, in a first aspect, the present application provides a low-dielectric lightweight functional material, the raw materials of which include, by weight: 40-50 parts of high isotactic polypropylene, 10-30 parts of low isotactic polypropylene, 10-20 parts of hollow glass microbeads, 2-4 parts of thermoplastic hollow polymer microspheres, 15-25 parts of glass fibers, 3-20 parts of processing aids.

[0007] The low-dielectric lightweight functional material of the application introduces glass fibers into the hollow glass microsphere and thermoplastic hollow polymer microsphere system to synergistically compound in the blended matrix formed by high isotactic PP and low isotactic PP, constructs a "multi-level hollow structure-polymer matrix" composite system, and realizes the synergistic optimization of low dielectric, high strength and lightweight.

[0008] As a specific embodiment of the application, the glass fiber is selected from solid glass fiber and hollow glass fiber.

[0009] As a specific embodiment of the application, the glass fiber is hollow glass fiber. The lightweight functional material of the application introduces hollow glass fiber as a skeleton reinforcing body, combines the synergistic filling of hollow glass microspheres and thermoplastic hollow polymer microspheres, forms a "micropore-hollow fiber-matrix" multi-level structure, further effectively disperses stress and inhibits crack propagation, further improves the tensile performance of the material, and further improves the lightweight and low dielectric advantages of the material.

[0010] As a specific embodiment of the application, the glass fiber is solid glass fiber. The lightweight functional material of the application introduces solid glass fiber as a skeleton reinforcing body, combines the synergistic filling of hollow glass microspheres and thermoplastic hollow polymer microspheres, forms a "micropore-solid fiber-matrix" multi-level structure, further effectively disperses stress and inhibits crack propagation, further improves the tensile performance of the material, and further improves the strength of the material.

[0011] As a specific embodiment of the application, the glass fiber is solid glass fiber and hollow glass fiber, and the mass ratio of the solid glass fiber to the hollow glass fiber is 1:1-2. The lightweight functional material of the application introduces solid and hollow glass fibers as skeleton reinforcing bodies, combines the synergistic filling of hollow glass microspheres and thermoplastic hollow polymer microspheres, forms a "micropore-fiber-matrix" multi-level structure, further effectively disperses stress and inhibits crack propagation, further improves the tensile performance of the material, and further comprehensively improves the strength, lightweight and low dielectric advantages of the material.

[0012] As a specific embodiment of the application, the diameter of the solid glass fiber is 10-13 μm, and the length is 3-5 mm.

[0013] As a specific embodiment of the application, the outer diameter of the hollow glass fiber is 20-100 μm, and the duty cycle is 50%-90%.

[0014] As a specific embodiment of the application, the isotacticity of the high isotactic polypropylene is ≥90%, preferably 90%-95%.

[0015] As a specific embodiment of the application, the isotacticity of the low isotactic polypropylene is 30-60%.

[0016] As a specific embodiment of the present application, the low isotactic polypropylene has a melting temperature of 60-100°C, a melt index of 200-2000 g / 10 min, and a weight average molecular weight of 600,000-1,500,000.

[0017] As a specific embodiment of the present application, the hollow glass microbead has a density of 0.3-0.6 g / cm3, a particle size of 10-50 μm, and a pressure bearing value of 4,500-30,000 PSI.

[0018] As a specific embodiment of the present application, the thermoplastic hollow polymer microsphere is composed of a thermoplastic polymer shell and a liquid alkane gas enclosed in the shell, and has a layer of ethylene-vinyl acetate copolymer organic carrier on the surface of the shell.

[0019] As a specific embodiment of the present application, the thermoplastic hollow polymer microsphere has a foaming volume expansion of 20-50 times, an initial foaming temperature of 150-180°C, and an optimal foaming temperature of 220-240°C.

[0020] As a specific embodiment of the present application, the processing aid includes 0.1-5 parts of an antioxidant.

[0021] As a specific embodiment of the present application, the processing aid includes 1-5 parts of a crosslinking agent.

[0022] As a specific embodiment of the present application, the processing aid includes 0.1-5 parts of a bonding agent.

[0023] As a specific embodiment of the present application, the processing aid includes 0.1-5 parts of a weathering agent.

[0024] As a specific embodiment of the present application, the processing aid includes 0.1-5 parts of a lubricant.

[0025] As a specific embodiment of the present application, the antioxidant is selected from the group consisting of a hindered phenol antioxidant and a phosphite antioxidant, and the mass ratio of the hindered phenol antioxidant to the phosphite antioxidant is 1:1-3.

[0026] As a specific embodiment of the present application, the crosslinking agent is a grafted maleic anhydride.

[0027] As a specific embodiment of the present application, the bonding agent is a silane coupling agent.

[0028] As a specific embodiment of the present application, the weathering agent is a hindered amine light stabilizer.

[0029] As a specific embodiment of the present application, the lubricant is selected from the group consisting of at least one of polyethylene wax, calcium stearate, barium stearate, zinc stearate, ethylene bis-stearamide, and pentaerythritol stearate.

[0030] As a specific embodiment of the present application, the density of the low-dielectric lightweight functional material is <0.90 g / cm 3 , the dielectric constant ε <3.0, and the tensile strength >25MPa.

[0031] To this end, in a second aspect, the present application provides a preparation method of the low-dielectric lightweight functional material, comprising the following steps: S1, uniformly mixing high isotactic polypropylene, low isotactic polypropylene, glass fiber, hollow glass microsphere, thermoplastic hollow polymer microsphere, antioxidant, weather resistant agent and processing aid to form a base premix; S2, uniformly stirring the base premix prepared in step S1 after preheating at a first temperature, then heating to a second temperature for banburying, and then extruding and granulating to obtain the lightweight functional material.

[0032] As a specific embodiment of the present application, the first temperature is 70-120℃; and / or, the preheating time is 3-8min; and / or, the second temperature is 160-250℃; and / or, the banburying time is 5-15min.

[0033] As a specific embodiment of the present application, the extrusion is performed by a screw extruder, preferably a single screw extruder.

[0034] As a specific embodiment of the present application, the temperature of each section of the screw extruder is between 160-220℃, and the screw rotation speed is 150-300rpm.

[0035] As a specific embodiment of the present application, the extrusion is performed by a screw extruder, and the temperature of each section is 165-175℃, 175-185℃, 170-180℃, 175-185℃, and 185-195℃, and the screw rotation speed is 150-250rpm.

[0036] To this end, in a third aspect, the present application provides a use of the low-dielectric lightweight functional material as described above or prepared by the preparation method as described above as a radome.

[0037] As a specific embodiment of the present application, the low-dielectric lightweight functional material is used as a radome of a UAV, a vehicle-mounted radar or a satellite communication terminal.

[0038] The low-dielectric lightweight reinforced PP material of the present application has good low-dielectric coefficient, lightweight, high-strength mechanical properties, simple production process, abundant raw material sources, low cost, and can effectively reduce the attenuation and reflection of electromagnetic waves in the penetration process, improve the transmission efficiency, and can be widely used in UAVs, vehicle-mounted radars, satellite communication terminals, etc.

[0039] The beneficial effects of this invention are: To address the technical problem of a significant decrease in mechanical strength caused by reducing the dielectric constant of existing lightweight materials, the lightweight functional material of this invention introduces glass fiber as a skeleton reinforcement, combined with the synergistic filling of hollow glass microspheres and thermoplastic hollow polymer microspheres, to form a multi-level structure of "micropore-hollow fiber-matrix", which effectively disperses stress and inhibits crack propagation, significantly improving the tensile properties of the material.

[0040] To address the technical problem that traditional low-dielectric materials are difficult to further reduce in dielectric constant due to high filler density or poor interfacial bonding, the lightweight functional material of this invention constructs a large number of low-dielectric-constant air and microporous structures inside the material by introducing glass fibers and hollow glass microspheres. At the same time, by controlling the interfacial compatibility between the PP matrix and the filler (using crosslinking agents and binders to improve interfacial bonding), the dielectric and tensile properties are significantly optimized.

[0041] To address the technical challenge of achieving both lightweighting and structural stability with a single reinforcement method, the lightweight functional material of this invention utilizes high isotactic PP to provide high crystallinity and rigidity, and low isotactic PP to improve processing fluidity and interfacial wettability. Together, they form a "rigid-flexible" matrix network, which, in conjunction with the three-dimensional support structure of hollow glass fiber, achieves a balance between structural stability and lightweighting. Detailed Implementation

[0042] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0043] (a) Raw materials High isotactic polypropylene (HPP), with an average isotacticity of 90%; Low isotactic polypropylene (LPP) with an average isotacticity of 40%, a melt temperature of 80℃, a melt index of 390 g / 10 min, and a weight-average molecular weight of 75,000. Hollow glass microspheres, density 0.4 g / cm³, particle size range 20-40μm, compressive strength 5500PSI; Thermoplastic hollow polymer microspheres consist of a thermoplastic polymer shell and liquid alkane gas sealed inside the shell. The surface of the shell has a layer of ethylene-vinyl acetate copolymer (EVA) organic carrier. The foaming volume expands about 30 times. The initial foaming temperature is 160℃ and the optimal foaming temperature (foaming peak) is 230℃. The diameter of the solid glass fiber is 13 μm, and the length is 3-5 mm. The outer diameter of the hollow glass fiber is 30-80 μm, and the duty cycle is 60%-80%. Crosslinking agent: grafted maleic anhydride; Binder: silane coupling agent FD-560; Antioxidant: antioxidant 1010 + antioxidant 168 (mass ratio of 1:1); Weathering agent: hindered amine light stabilizer HALS-770 / 6608; Lubricant: calcium stearate.

[0044] (II) Performance test method (1) Density: tested according to GB / T 1033.1-2008; (2) Tensile strength: standard tensile test samples were extracted from the raw material and injection molded; after the sample state was adjusted, the tensile strength was tested using an electronic universal testing machine; a total of 10 samples were tested, and the arithmetic average tensile strength was obtained; (3) Dielectric constant: tested according to GB / T 5594.4-2015.

[0045] Example 1 Preparation of low-dielectric lightweight functional material (1) High isotactic polypropylene HPP, low isotactic polypropylene LPP, solid glass fiber and / or hollow glass fiber, hollow glass microbeads, thermoplastic hollow polymer microbeads, antioxidant, weathering agent and processing aid were mixed in a high-speed mixer for 10 minutes to form a uniform base premix. The amounts of the components are shown in Table 1-1.

[0046] (2) The base premix was first heated to 90°C and preheated for 5 min, then stirred uniformly, then milled at 160°C for 10 min, and then extruded through a single screw extruder. The extrusion section temperatures were 170, 180, 175, 180 and 190°C, respectively, and the screw rotation speed was 200 rpm. Granulation can obtain a low-dielectric lightweight functional material.

[0047] Examples 2-9 The same as the steps of Example 1, except that the amounts of the components are shown in Table 1-1.

[0048] Comparative Examples 1-8 The same as the steps of Example 1, except that the amounts of the components are shown in Table 1-2.

[0049] The performance test results of the low-dielectric lightweight functional materials of Examples 1-9 and Comparative Examples 1-8 are shown in Tables 2-1 and 2-2, respectively.

[0050] Table 1-1

[0051] Table 1-2

[0052] Table 2-1

[0053] Table 2-2

[0054] The "@2.5GHz" in Table 2-1 and Table 2-2 represents the response ability of the material to the electric field at a frequency of 2.5GHz, which reflects the polarization characteristics of the material under the action of electromagnetic waves. This parameter is crucial in radio frequency and microwave engineering, directly affecting the performance of signal transmission, antenna design, etc. The lower this value, the less the electromagnetic wave attenuates in the material, and the higher the transmission efficiency.

[0055] The results of Example 1-9 and Comparative Example 1-8 show that there is a synergistic effect between high and low isotactic polypropylene and glass fibers, hollow glass microspheres, and thermoplastic hollow polymer microspheres. Proper proportioning can significantly optimize the lightweight and low dielectric properties of the composite material, but excessive hollow glass microspheres or thermoplastic hollow polymer microspheres will weaken the mechanical properties due to structural damage or density reduction. The proportioning of each component needs to be within a specific range to achieve performance synergy.

[0056] Compared with Comparative Example 1, Example 1 adds solid glass fibers, hollow glass microspheres, and thermoplastic hollow polymer microspheres, which form a "microporous-solid fiber-matrix" multi-level structure, effectively dispersing stress and inhibiting crack propagation, reducing the dielectric constant while improving the tensile properties of the material, effectively improving the tensile strength of the material.

[0057] Compared with Comparative Example 2-3, Example 1 adds solid glass fibers and low isotactic PP, forming a synergistic composite of hollow glass microspheres, thermoplastic hollow polymer microspheres in the blending matrix formed by high and low isotactic PP, constructing a "multi-level hollow structure-polymer matrix" composite system, achieving synergistic optimization of low dielectric, high strength, and lightweight.

[0058] Compared with Comparative Example 4, Example 1 adds solid glass fibers, which form a "microporous-solid fiber-matrix" multi-level structure with hollow glass microspheres and thermoplastic hollow polymer microspheres, effectively dispersing stress and inhibiting crack propagation, improving the tensile properties of the material, and effectively improving the tensile strength of the material.

[0059] Compared with Comparative Example 5, Example 6 adds hollow glass fibers, combined with the synergistic filling of hollow glass beads and thermoplastic hollow polymer microbeads, to form a "microporous-hollow fiber-matrix" multi-level structure, which further effectively disperses stress and inhibits crack propagation, further improves the tensile performance of the material, and further improves the lightweight and low dielectric advantages of the material.

[0060] Compared with Comparative Example 7, Example 8 adds hollow glass fibers, combined with the synergistic filling of hollow glass beads and thermoplastic hollow polymer microbeads, to form a "microporous-hollow fiber-matrix" multi-level structure, which further effectively disperses stress and inhibits crack propagation, further improves the tensile performance of the material, and further improves the lightweight and low dielectric advantages of the material.

[0061] Compared with Comparative Example 8, Example 1 uses solid glass fibers to replace 20 parts of high isotactic PP, and the tensile strength is significantly improved, but the density and dielectric constant are also significantly improved.

[0062] Example 2 increases the amount of thermoplastic hollow polymer microspheres based on Example 1, and the tensile strength decreases slightly, but the density and dielectric constant are further optimized.

[0063] In Example 3, hollow glass fibers are used instead of solid glass fibers compared to Example 1, and the material density and dielectric constant are significantly reduced, indicating that the hollow structure effectively reduces the overall weight and dielectric response while maintaining a certain rigidity. However, due to the low mechanical strength of the hollow structure, the tensile performance is lower than that of Example 1.

[0064] Example 4 increases 10 parts of hollow glass fibers based on Example 3, and the tensile strength is significantly improved, but the density also rises, and the lightweight advantage is slightly weakened.

[0065] Example 5 uses a combination of solid glass fibers and hollow glass fibers, achieving a dynamic balance between mechanical properties and lightweight indicators, and showing excellent synergistic control potential.

[0066] Examples 6 and 7 respectively introduce 10 parts of hollow glass beads and 1 part of thermoplastic hollow polymer microspheres based on Example 3, both of which achieve a significant reduction in density and dielectric constant, but the tensile strength decreases slightly.

[0067] Example 8 compared with Example 7, Example 8 adds 10 parts of hollow glass beads based on Example 7, although the tensile strength decreases, the material density is significantly reduced, and the dielectric constant also shows a slight downward trend.

[0068] Compared with Example 7, Example 9 is based on Example 7 with the addition of 1 part of thermoplastic hollow polymer microspheres. The results show that the tensile strength of the material decreases slightly, but the density decreases significantly, and the dielectric constant also shows a slight downward trend. This phenomenon shows that the thermoplastic hollow polymer microspheres not only introduce microstructure cavities in the material, play a foaming effect, effectively reduce the overall density, but also actively regulate the dielectric properties of the material through its unique dielectric properties, but also attenuate the tensile strength.

[0069] In summary, in Examples 1-9, a comprehensive balanced material system with low density, low dielectric properties and excellent mechanical strength is successfully constructed. Based on Examples 1-9, according to the technical standards corresponding to the plastic parts, combined with the performance requirements of the application scene, scientific and precise optimization decision can be made to realize efficient matching of material performance and engineering application.

[0070] The above description of the examples is to facilitate the understanding and application of the present application by those of ordinary skill in the art. Those skilled in the art can easily make various modifications to these examples, and apply the general principles described herein to other examples without having to go through creative labor. Therefore, the present application is not limited to the examples herein, and any improvements and modifications made by those skilled in the art without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A low-dielectric, lightweight functional material, characterized in that, The raw materials for this low-dielectric lightweight functional material, by weight, include: 40-50 parts of high-grade polypropylene, 10-30 parts of low-isotactic polypropylene, 10-20 parts hollow glass microspheres, 2-4 parts thermoplastic hollow polymer microspheres, 15-25 parts glass fiber, 3-20 parts processing aids.

2. The functional material according to claim 1, characterized in that, The glass fiber is selected from solid glass fiber and hollow glass fiber.

3. The functional material according to claim 2, characterized in that, The solid glass fibers have a diameter of 10-13 μm and a length of 3-5 mm; and / or The hollow glass fiber has an outer diameter of 20-100 μm and a duty cycle of 50%-90%.

4. The functional material according to any one of claims 1-3, characterized in that, The isotacticity of the high isotactic polypropylene is ≥90%; and / or The isotacticity of the low-isotactic polypropylene is 30-60%; and / or The low isotactic polypropylene has a melt temperature of 60-100℃, a melt index of 200-2000 g / 10 min, and a weight-average molecular weight of 60,000-150,000.

5. The functional material according to any one of claims 1-3, characterized in that, The hollow glass microspheres have a density of 0.3-0.6 g / cm³, a particle size of 10-50 μm, and a compressive strength of 4500-30000 PSI; and / or The thermoplastic hollow polymer microspheres consist of a thermoplastic polymer shell and liquid alkane gas sealed inside the shell, with a layer of ethylene-vinyl acetate copolymer on the surface of the shell. and / or The thermoplastic hollow polymer microspheres expand 20-50 times in volume during foaming, with an initial foaming temperature of 150-180℃ and an optimal foaming temperature of 220-240℃.

6. The functional material according to any one of claims 1-3, characterized in that, The processing aid includes 0.1-5 parts of antioxidant; and / or The processing aid includes 1-5 parts of a crosslinking agent; and / or The processing aid includes 0.1-5 parts of binder; and / or The processing aid includes 0.1-5 parts of weather-resistant agent; and / or The processing aid includes 0.1-5 parts of lubricant.

7. The functional material according to claim 6, characterized in that, The antioxidant is selected from hindered phenolic antioxidants and phosphite antioxidants, wherein the mass ratio of the hindered phenolic antioxidant to the phosphite antioxidant is 1:1-3; and / or The crosslinking agent is grafted maleic anhydride; and / or The adhesive is a silane coupling agent; and / or The weather-resistant agent is a hindered amine light stabilizer; and / or The lubricant is selected from at least one of polyethylene wax, calcium stearate, barium stearate, zinc stearate, ethylene bis-stearamide, and pentaerythritol stearate.

8. A method for preparing a low-dielectric lightweight functional material according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Mix high-isotactic polypropylene, low-isotactic polypropylene, glass fiber, hollow glass microspheres, thermoplastic hollow polymer microspheres, antioxidants, weathering agents and processing aids evenly to form a matrix premix. S2. The matrix premix obtained in step S1 is heated to a first temperature for preheating and then stirred evenly. It is then heated to a second temperature for intensive mixing, extruded, and granulated to obtain the lightweight functional material.

9. The preparation method according to claim 8, characterized in that, The first temperature is 70-120℃; and / or, the preheating time is 3-8 min; and / or, the second temperature is 160-250℃; and / or, the mixing time is 5-15 min; and / or, the extrusion is performed using a screw extruder, with the temperature of each extrusion section between 160-220℃ and the screw speed between 150-300 rpm.

10. Use of the low-dielectric lightweight functional material according to any one of claims 1-7 or the low-dielectric lightweight functional material prepared by the preparation method according to claim 8 or 9 as an antenna radome.

Images