A low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material and its preparation method

Abstract

The present invention discloses a low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material, which is made of the following components in mass percentage: 43-82% of siloxane copolymer polycarbonate resin, 9.8-25% of short-cut low-dielectric glass fiber, 5-15% of modified hollow glass microspheres, 1-10% of polyphosphate flame retardant, 1-4% of polyphenylsiloxane flame retardant, 0.1-1% of silane coupling agent, 1-5% of silicone toughening agent, and 0.1-2% of additives. The present invention uses a compound of short-cut low-dielectric glass fiber and modified hollow glass microspheres, which is applied to the siloxane copolymer polycarbonate resin, having excellent comprehensive performance, and obtaining lower dielectric constant and dielectric loss, meeting the usage requirements of 5G.

Description

Technical Field

[0001] The invention belongs to the field of polymer composite materials, and in particular relates to a low-dielectric, halogen-free, flame-retardant, weather-resistant, reinforced polycarbonate material and a preparation method thereof. Background Art

[0002] The fifth generation of mobile phone mobile communication standards, also known as the fifth generation of mobile communication technology, abbreviated as 5G. The difference between 5G mobile communication and the previous four generations of mobile communication is that the previous four generations are single technologies, while 5G is the sum of the previous four generations of technology, which makes the peak rate of 5G mobile communication higher, more secure, and more widely covered. 5G mobile communication makes up for the loopholes in 4G mobile communication. Its technology is more advanced and can meet people's current needs for the network. It is the mainstream trend of development in the future. 5G communication uses millimeter wave bands. Its biggest advantage is fast propagation speed, and its biggest disadvantage is poor penetration and large attenuation. In this way, 5G requires the dielectric constant and dielectric loss of the propagation medium material to be small in order to achieve effective reception and transmission, and to remain stable over a wide frequency range. The dielectric constant of 5G equipment for low dielectric materials is less than 3, which is much smaller than the 4G standard of dielectric constant between 3.4-3.7. High-frequency and high-speed transmission also requires the composite materials used in smartphones to have low dielectric loss under high-frequency voltage. Therefore, reducing the dielectric constant and dielectric loss of materials is an urgent need to cope with 5G communications. In addition, 5G smart terminals and base stations will develop in the direction of miniaturization and thinness, requiring the composite materials used in them to have excellent mechanical properties and melt forming processing properties to form high-strength thin-walled structural components.

[0003] Polycarbonate is widely used in electronic appliances, automobiles, machinery manufacturing, computers and other technical fields because of its heat resistance, flame retardancy, good impact resistance, easy processing and low cost. Polycarbonate (PC) can be further strengthened by glass fiber reinforcement to improve its fatigue resistance and stress cracking resistance. It is used to prepare structural packaging components such as the outer frame, middle frame and base station antenna cover of electrical equipment. However, alkali-free glass fiber (E-glass fiber) is commonly used to reinforce PC composite materials. Because E-glass fiber has higher Dk (6.80~7.10, 1MHz) and Df (6.00*10 -3 , 1MHz), its filling leads to the deterioration of the dielectric properties of PC, and due to the orientation of alkali-free glass fiber, the appearance of floating fiber is more obvious after reinforcement, which is difficult to meet the requirements of 5G applications. Ordinary PC has a dielectric constant of 3.0-3.1 and a dielectric loss of 0.009. After glass fiber reinforcement modification, its dielectric constant is 3.5 and the dielectric loss is 0.009, which cannot meet the requirements of 5G equipment. In addition, ordinary polycarbonate is not flame retardant enough and cannot meet the occasions with high or very high flame retardant requirements.

[0004] Traditional brominated flame retardants have high flame retardancy efficiency, but they produce a large amount of smoke and carcinogenic substances such as tetrabromodibenzodioxane and tetrabromodibenzofuran during combustion and pyrolysis; although low-molecular-weight phosphate ester flame retardants avoid the harmful substances generated during the combustion of brominated flame retardant systems, their low melting point and high volatility easily cause a significant decrease in the heat resistance of materials and volatilization loss during the molding process; sulfonate flame retardants accelerate the carbonization rate of bisphenol A polycarbonate during combustion, promote the molecular crosslinking of polymers, have a small addition amount, high efficiency, and can keep the material transparent, but cannot meet the flame retardant requirements of thin-walled parts; phosphazene flame retardants have excellent flame retardancy, water resistance, antioxidant properties, thermal stability, and molding processability, and have the advantages of low smoke generation during combustion or pyrolysis, but the addition amount is relatively large, and after adding, it affects the heat resistance and light transmittance of the material; traditional polysiloxane flame retardants have attracted much attention from researchers due to their excellent processability, flame retardancy, and good mechanical properties, especially their environmental friendliness. However, when used alone, the flame retardant effect on thin walls is not good, the addition amount is relatively large, and the cost is high. Generally, they are used as co - flame retardants in compounding. Phenyl silicone flame retardants have better thermal stability, higher thermal decomposition activation energy and thermal decomposition temperature, and better flame retardant effect. The higher the phenyl content of this kind of silicone - based flame retardant, the denser the carbon layer formed after the combustion of the prepared flame retardant material, and the better the flame retardant effect.

[0005] The patent application "A Glass Fiber Reinforced Polycarbonate Material and Its Preparation Method" with the publication number CN115124826A discloses a glass fiber reinforced polycarbonate material, its preparation method and application. The glass fiber reinforced polycarbonate material includes the following components by weight: 40 - 95 parts of polycarbonate, 1 - 40 parts of non - alkali glass fiber, and 1 - 40 parts of porous glass fiber; the mass percentage content of SiO2 in the porous glass fiber is ≥95%. In the present invention, non - alkali glass fiber with low dielectric loss is compounded with porous glass fiber to modify polycarbonate, comprehensively improving the dielectric properties, mechanical properties and processability of the material, making it have high impact toughness, good mechanical properties, good processing characteristics, lower dielectric loss and dielectric constant, achieving a performance balance in many aspects such as excellent dielectric properties, processability, and comprehensive mechanical properties, and being able to meet the requirements of fields such as high - frequency communication equipment, automotive parts, and electrical appliances. The invention compounds non - alkali glass fiber with low dielectric loss and porous glass fiber, and modifies polycarbonate. The dielectric constant of the modified material at 5 GHz is 2.9 - 3.25, and due to the orientation of the glass fiber, the appearance of floating fibers is relatively obvious. In addition, this material has not been modified for flame retardancy and weather resistance, cannot meet the occasions with higher requirements for flame retardant levels, and is not suitable for outdoor use.

[0006] Patent application "Low dielectric glass fiber reinforced PC / PPO composite material and its preparation" with publication number CN113416401A discloses a low dielectric glass fiber reinforced PC / PPO composite material and its preparation method. In terms of mass percentage, the raw material formula of the PC / PPO composite material is composed of the following components: 29.8% to 41.5% polycarbonate, 29.7% to 38.0% modified polyphenylene ether, 20.0% to 40.0% short-cut low dielectric glass fiber, 0.1% to 0.4% antioxidant, and 0.3% to 0.6% dispersant; the Dk of the composite material of the present invention is reduced to 2.83 to 3.10, and the Df is reduced to 1.53×10 -3 ~2.40×10 -3 , which can meet the application requirements of 5G / 6G for low dielectric materials, and the good compatibility and low melt viscosity ensure that the composite material has high mechanical properties and excellent molding and processing performance. The patent application with publication number CN105440628A discloses a reinforced flame retardant PC / PPO composite material, the components of which are as follows: 20-30 parts of PC resin, 14.9-22 parts of PPO (polyphenylene ether), 3-5.2 parts of PC-PPO block copolymer, 5-8 parts of SEBS graft, 5-8 parts of polypropylene elastomer graft, 0.5-1 parts of amino modified silicone oil, 0.5-1 parts of amino silane coupling agent, 20-30 parts of glass fiber; and composite flame retardant, antioxidant and light stabilizer. The composite materials disclosed in these two patents have good tensile strength, rigidity and high and low temperature toughness, but the PPO material has high viscosity and high rigidity, resulting in low processing fluidity of the material and difficulty in preparing thin-walled parts.

[0007] The patent application with publication number CN114716802A, "A low-dielectric mobile phone middle frame substrate and its preparation method", discloses a low-dielectric mobile phone middle frame substrate and its preparation method. The mobile phone middle frame substrate includes the following components in parts by weight: 55-70 parts of polycarbonate, 10-25 parts of polyethylene terephthalate, 10-18 parts of modified hollow glass microspheres, 5-15 parts of toughening agent, 3-8 parts of dispersant, 0.4-1 part of antioxidant and 0.5-1.5 parts of lubricant. The better the dielectric properties of the mobile phone middle frame substrate of the present invention, the better the mechanical properties, the lighter the weight, the lower the cost and the easier it is to process. The dielectric constant of the substrate obtained by the invention is 2.601-2.723, the dielectric loss is 0.00257-0.0036, and the dielectric properties are excellent; the notched impact strength is 20.22-24.40KJ / m 2 , tensile strength is 36-45MPa, flexural strength is 58-70MPa, mechanical properties are excellent, and specific gravity is 0.956-0.993g / cm 3 , small specific gravity and light weight. However, the strength is low and cannot meet the use requirements of the middle frame, antenna cover, etc.

[0008] The structural composition of chopped low-dielectric glass fiber (D-glass fiber) contains more low-polarity components, and has a lower Dk (4.20 - 4.80, 1 MHz) and Df (1.00*10 -3 , 1 MHz) than E-glass fiber. The patent application with the publication number WO2017203467A1 uses D-glass fiber instead of E-glass fiber to enhance and modify PC. When the glass fiber content is the same at 20 wt%, the Dk and Df of the composite material are reduced by 4.2% and 6.8% respectively. It can be seen that only using D-glass fiber instead of E-glass fiber to modify PC, the reduction degrees of Dk and Df of the obtained composite material are very limited and still cannot meet the needs of 5G applications.

[0009] Therefore, reducing the dielectric properties and dielectric loss of the reinforced polycarbonate material, and improving the strength, flame retardancy, weather resistance, and fiber floating of the material are still the research focuses in this field. Summary of the Invention

[0010] The purpose of the present invention is to provide a low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material.

[0011] Another purpose of the present invention is to provide a preparation method of the low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material.

[0012] In order to achieve the above purposes, the technical solutions adopted by the present invention are as follows:

[0013] The first aspect of the present invention provides a low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material, which is made of the following components in mass percentage: 43 - 82% of siloxane copolymerized polycarbonate resin, 9.8 - 25% of chopped low-dielectric glass fiber, 5 - 15% of modified hollow glass microspheres, 1 - 10% of polyphosphate flame retardant, 1 - 4% of polyphenylsiloxane flame retardant, 0.1 - 1% of silane coupling agent, 1 - 5% of silicone-based toughening agent, and 0.1 - 2% of auxiliary agent.

[0014] The low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material is made of the following components in mass percentage: 55.4% of siloxane copolymerized polycarbonate resin, 20% of chopped low-dielectric glass fiber, 10% of modified hollow glass microspheres, 7% of polyphosphate flame retardant, 3% of polyphenylsiloxane flame retardant, 0.3% of silane coupling agent, 3% of silicone-based toughening agent, and 1.3% of auxiliary agent.

[0015] The siloxane copolymerized polycarbonate resin is a polycarbonate resin copolymerized from bisphenol A and siloxane, with a relative molecular weight of 25,000 - 32,000 and a siloxane content of 5 - 20%. Specifically, FG1760 of Idemitsu Kosan Co., Ltd. of Japan and 8000 - 05 of LG Chem are selected. The structure is as follows:

[0016]

[0017] wherein R 1 and R 2 are each independently selected from C1-C10 alkyl, C6-C18 aryl, alkoxylated C1-C10 alkyl, C6-C18 aryl, preferably methyl, phenyl.

[0018] The chopped low-dielectric glass fiber has a mass percentage content of SiO2 ≥ 90%, a dielectric constant of 4.2-4.6, a dielectric loss of 0.0020-0.0030, and is purchased from Taishan Fiberglass Co., Ltd., with the model being TLD-CS310-3.0-T436S.

[0019] The modified hollow glass microspheres have a particle size of 15-20 μm, a density of 0.125-0.60 g / cm 3 , a strength of 82 MPa - 124 MPa, a dielectric constant of 1.2-2.0, a dielectric loss of 0.001-0.002, and are purchased from 3M Company in the United States, with the model being 1M16K.

[0020] The relative molecular weight of the polyphosphate flame retardant is 40,000 - 50,000, and its structure is as follows:

[0021]

[0022] It is produced by FRX Polymers Company in the United States, with the model being HM1100.

[0023] The polyphenylsiloxane flame retardant is octaphenylcyclotetrasiloxane, and its molecular structure is as follows:

[0024]

[0025] The preparation method is as follows: Put 200 g of diphenyldimethoxysilane, 320 g of acetone, and 8 g of deionized water into a three-necked flask equipped with a stirring device, a condenser, and a thermometer, stir well to make them mix evenly. Dissolve 0.05 g of NaOH in a beaker containing 20 g of methanol, mix evenly and then put it into the three-necked flask. Heat up to 55 °C and start refluxing. React for 4 h. After the reaction is completed, filter by suction, wash 3 times with absolute ethanol, and then wash 3 times with deionized water until the filtrate is neutral. Dry under vacuum to obtain white crystalline octaphenylcyclotetrasiloxane. Among them, the diphenyldimethoxysilane, acetone, dichloromethane, potassium hydroxide, and methanol used are commercially available (specific reference: Yang Rui et al., Research on a High-Phenyl-Content Organosilicon Flame-Retarded Polycarbonate, Engineering Science and Technology, 2021, 195-202.).

[0026] The silane coupling agent is selected from at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane or γ-glycidoxypropyltriethoxysilane. γ-glycidoxypropyltrimethoxysilane is purchased from Boiling Point Chemical Co., Ltd., and the model is KH560.

[0027] The silicone toughening agent is a core-shell structured graft copolymer with silicone rubber-acrylate as the core and polymethyl methacrylate as the shell, with a silicon content of 70-80%, and can be selected from Mitsubishi Rayon Co., Ltd. in Japan, and the model is SX005.

[0028] The auxiliary agent is made of an antioxidant, a light stabilizer, a processing aid, and a color powder.

[0029] The antioxidant is at least one of phosphite antioxidant 168, S-9228, hindered phenol antioxidant 1010, hindered phenol antioxidant 1098, hindered phenol antioxidant 1076, and more preferably a mixture of antioxidant S-9228 and antioxidant 1076.

[0030] The light stabilizer is a cyanoacrylate ultraviolet absorber, purchased from BASF, and the model is Uvinul 3030.

[0031] The processing aid is selected from at least one of polyethylene wax, oxidized polyethylene wax, and pentaerythritol stearate, and more preferably pentaerythritol stearate.

[0032] The color powder is mainly composed of a pigment and lubricant EBS. The pigment is phthalocyanine blue, phthalocyanine green, BR red, HG yellow, 3R blue, etc., and can be purchased from Clariant Chemicals (China) Co., Ltd.; the pigment and lubricant EBS are diluted in a ratio of 1:10.

[0033] The second aspect of the present invention provides a preparation method of the low dielectric halogen-free flame retardant weather-resistant reinforced polycarbonate material, including the following steps:

[0034] Add the silane coupling agent to the silicone copolymer polycarbonate resin and mix in a high-speed mixer; then add the polyphosphate flame retardant, polyphenylsiloxane flame retardant, silicone toughening agent, and auxiliary agent to the high-speed mixer and mix at high speed for 6-8 minutes. After mixing evenly, pass through the main feeder and enter the twin-screw extruder; the short-cut low dielectric glass fiber and modified hollow glass microspheres are respectively added to the twin-screw extruder through the side feeding of the 4th and 5th sections of the extruder, and granulated after melt blending; the low dielectric halogen-free flame retardant weather-resistant reinforced polycarbonate material is obtained.

[0035] The temperatures of the 11 zones of the twin-screw extruder are respectively set at 250 °C, 260 °C, 270 °C, 270 °C, 270 °C, 260 °C, 260 °C, 260 °C, 260 °C, 260 °C, 260 °C; the obtained pellets are dried at 120 °C for 4 hours and then injection-molded into standard specimens at 280 - 290 °C.

[0036] The siloxane copolymerized polycarbonate resin must be dried at 110 °C for 6 h in a blast dryer.

[0037] The polyphosphate flame retardant is dried in a vacuum oven at 100 °C for 6 h.

[0038] Due to the adoption of the above technical solutions, the present invention has the following advantages and beneficial effects:

[0039] (1) By using the compounding of short-cut low-dielectric glass fibers and modified hollow glass microspheres and applying them to the siloxane copolymerized polycarbonate resin, the comprehensive performance is excellent, and lower dielectric constant and dielectric loss are obtained, meeting the usage requirements of 5G.

[0040] (2) By using the compounding of polyphosphate flame retardant and polyphenylsiloxane flame retardant and applying them to the siloxane copolymerized polycarbonate resin, there is an obvious flame retardant synergistic effect among the three, which can meet the thin-wall flame retardant requirements.

[0041] (3) The addition of a toughening agent with a high silicon content not only improves the impact resistance of the material but also helps to improve the flame retardant performance.

[0042] (4) The material has excellent weather resistance and can meet the outdoor use requirements of 5G. Specific embodiments

[0043] To illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the specific content described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0044] The polycarbonate resin used in the comparative example: bisphenol A aromatic polycarbonate resin purchased from Covestro AG, with a relative molecular weight of 20,000 - 30,000 and a model of 2805.

[0045] Table 1 Components and ratios of Comparative Examples 1 - 4 and Examples 1 - 5

[0046]

[0047] Table 2 Components and ratios of Comparative Examples 5 - 7 and Example 6

[0048]

[0049]

[0050] Preparation method:

[0051] First, dry the silicone copolymer polycarbonate resin or bisphenol A polycarbonate resin in a forced-air dryer at 110 °C for 6 h, and dry the polyphosphate flame retardant in a vacuum oven at 100 °C for 6 h; then add the silane coupling agent to the PC resin in proportion and mix in a high-speed mixer for 1 minute; then add the polyphosphate flame retardant, polyphenyl silicone flame retardant, silicone-based toughening agent, and additives to the high-speed mixer and mix at high speed for 6 - 8 minutes. After mixing evenly, pass through the main feeder and enter the twin-screw extruder; the chopped low-dielectric glass fiber and modified hollow glass microspheres are respectively added to the twin-screw extruder through the side feeders at the 4th and 5th sections of the extruder, and granulated after melt blending.

[0052] The temperatures of the 11 zones of the twin-screw extruder are respectively set at 250 °C, 260 °C, 270 °C, 270 °C, 270 °C, 260 °C, 260 °C, 260 °C, 260 °C, 260 °C, 260 °C. The obtained pellets are dried at 120 °C for 4 hours and then injection molded into standard specimens at 280 - 290 °C to obtain the product.

[0053] Evaluation of implementation effects

[0054] Test the mechanical properties of the samples obtained in the above Examples 1 - 8 and Comparative Examples 1 - 5 according to the standards of the American Society for Testing and Materials (ASTM). The flame retardancy is tested according to the UL94 standard, the dielectric constant and dielectric loss of the material are tested according to the ASTM ES 7 - 83 standard, the flame retardancy of the material is tested according to the UL94 standard, the weather resistance of the material (15 cycles) is tested according to the procedure B of GB / T 2423 - 2013, and the gray scale of color change is evaluated according to ISO 105 - A02 after weathering. The test results are shown in the following table:

[0055] Table 3 Properties of Comparative Examples 1 - 4 and Examples 1 - 5

[0056]

[0057]

[0058] Table 4 Properties of Comparative Examples 5 - 7 and Example 6

[0059]

[0060]

[0061] The test performance results in Table 3 and Table 4 show that:

[0062] (1) By comparing Examples 1-5 with Comparative Example 5, it was found that the addition of modified hollow glass microspheres significantly reduced the density, dielectric constant, and dielectric loss of the composite material. This is because the hollow glass microspheres contain a large number of microscopic pores (air, with a dielectric constant of 1 and a dielectric loss of 0), which endows the hollow glass microspheres with low dielectric constant and dielectric loss. Moreover, the micropores can produce capillary action, improving the bonding property with the PC resin in the molten state and enhancing the comprehensive mechanical properties of the material. However, in Comparative Example 5, when only adding hollow glass fibers, the strength and modulus of the material were very low and could not meet the usage requirements. Compared with ordinary glass fibers, low-dielectric glass fibers contain more than 90% SiO2 and basically do not contain MgO, Li2O, Na2O, K2O, and TiO2, and their dielectric constant and dielectric loss are very low. The combined use of low-dielectric glass fibers and hollow glass microspheres can obtain a low-dielectric composite material with excellent comprehensive performance, and the best ratio is Example 2.

[0063] (2) By comparing Example 2 with Comparative Example 2, it was found that compared with ordinary bisphenol A polycarbonate resin, the silicone copolymer polycarbonate resin not only has good low-temperature and weather resistance performance but also has lower dielectric constant and dielectric loss, making it more suitable for 5G scenarios. This is because the molecular chain contains Si—O bonds. Due to the presence of Si atoms, it generally has a lower dipole moment and smaller polarization intensity.

[0064] (3) By comparing Example 2 with Comparative Examples 1 and 3, it was found that the compounding of polyphosphate flame retardant and polyphenylsiloxane flame retardant, when applied to reinforced silicone copolymer polycarbonate resin, has excellent comprehensive performance and does not affect the dielectric properties, meeting the requirements of high heat resistance and high flame retardancy. From Comparative Examples 1 and 2, it was found that when using polyphosphate flame retardant alone or polyphenylsiloxane flame retardant alone, the flame retardant effect is not good and cannot meet the flame retardant requirements. The molecular chain of silicone-based flame retardants is Si—O bonds, with a high bond energy and excellent thermal stability. During combustion, organosilicon can promote the formation of a carbon layer, prevent the formation of smoke and the development of flames, and enhance the flame retardant effect. Phenyl organosilicon flame retardants have better flame retardant effects due to higher thermal decomposition activation energy and thermal decomposition temperature. Moreover, the higher the phenyl content, the denser the carbon layer formed after combustion and the better the flame retardant effect.

[0065] (4) By comparing Example 2 with Comparative Example 7, it was found that by introducing cyanoacrylate ultraviolet absorbers, the composite material has excellent weather resistance and can meet outdoor usage requirements. By comparing Examples 2, 6 with Comparative Example 6, it was found that adding a toughening agent with a high silicon content not only improves the impact resistance of the material but also helps to improve the flame retardant performance and reduce the dielectric performance. However, as the addition amount increases, the strength of the material decreases. Therefore, the best ratio should be Example 2.

[0066] The above are only the preferred embodiments of the present invention, and there is no limitation to the present invention in any form. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art of this patent, without departing from the scope of the technical solution of the present invention, can make some changes or modifications using the technical content prompted above to form equivalent embodiments of equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material, characterized in that, It is made of the following components by mass percentage: 43-82% of siloxane copolymerized polycarbonate resin, 9.8-25% of chopped low-dielectric glass fiber, 5-15% of modified hollow glass microsphere, 1-10% of polyphosphate flame retardant, 1-4% of polyphenylsiloxane flame retardant, 0.1-1% of silane coupling agent, 1-5% of silicone toughening agent, 0.1-2% of auxiliary agent; The siloxane copolymerized polycarbonate resin is a polycarbonate resin copolymerized from bisphenol A and siloxane, with a relative molecular weight of 25,000-32,000 and a siloxane content of 5-20%; The auxiliary agent is made of antioxidant, light stabilizer, processing aid, and color powder; For the chopped low-dielectric glass fiber, the mass percentage of SiO2 is ≥90%, the dielectric constant is 4.2-4.6, and the dielectric loss is 0.0020-0.0030; The particle size of the modified hollow glass microspheres is 15 - 20 μm, and the density is 0.125 - 0.60 g / cm 3 , the strength is 82 MPa - 124 MPa, the dielectric constant is 1.2 - 2.0, and the dielectric loss is 0.001 - 0.002; The relative molecular weight of the polyphosphate flame retardant is 40,000-50,000; The polyphenylsiloxane flame retardant is octaphenylcyclotetrasiloxane; The silicone toughening agent is a core-shell structured graft copolymer with silicone rubber-acrylate as the core and polymethyl methacrylate as the shell, with a silicon content of 70-80%.

2. The low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material according to claim 1, wherein The low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material is made of the following components by mass percentage: 55.4% of siloxane copolymerized polycarbonate resin, 20% of chopped low-dielectric glass fiber, 10% of modified hollow glass microsphere, 7% of polyphosphate flame retardant, 3% of polyphenylsiloxane flame retardant, 0.3% of silane coupling agent, 3% of silicone toughening agent, 1.3% of auxiliary agent.

3. The low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material according to claim 1, wherein The silane coupling agent is selected from at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidyletheroxypropyltrimethoxysilane, or γ-glycidyletheroxypropyltriethoxysilane.

4. The low dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material according to claim 1, wherein The antioxidant is at least one of phosphite antioxidant 168, S-9228, hindered phenol antioxidant 1010, hindered phenol antioxidant 1098, hindered phenol antioxidant 1076; The light stabilizer is a cyanoacrylate ultraviolet absorber; The processing aid is selected from at least one of polyethylene wax, oxidized polyethylene wax, and pentaerythritol stearate; The color powder is mainly composed of pigment and lubricant EBS, where the pigment is phthalocyanine blue, phthalocyanine green, BR red, HG yellow, 3R blue.

5. A method for preparing the low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material according to any one of claims 1 to 4, characterized in that, It includes the following steps: Add the silane coupling agent to the siloxane copolymerized polycarbonate resin and mix in a high-speed mixer; Then add the polyphosphate flame retardant, polyphenylsiloxane flame retardant, silicone toughening agent, and auxiliary agent to the high-speed mixer, mix at high speed for 6-8 minutes, and after mixing evenly, enter the twin-screw extruder through the main feeder; the chopped low-dielectric glass fiber and the modified hollow glass microsphere are respectively added to the twin-screw extruder through the side feeding at the 4th and 5th sections of the extruder, and granulated after melt blending; the low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material is obtained.

6. The preparation method of the low-dielectric halogen-free flame-retardant weather-resistant reinforced polycarbonate material according to claim 5, characterized in that, The temperatures of the 11 zones of the twin-screw extruder are respectively set at 250 °C, 260 °C, 270 °C, 270 °C, 270 °C, 260 °C, 260 °C, 260 °C, 260 °C, 260 °C, 260 °C; the obtained pellets are dried at 120 °C for 4 hours and then injection-molded into standard specimens at 280-290 °C.

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