PPO-based dielectric composite material and preparation method thereof

Abstract

The present invention discloses a PPO-based dielectric composite material and a preparation method thereof. The PPO-based dielectric composite material is prepared from the following raw materials: polyphenylene ether resin, hyperbranched polyamide-coated barium titanate, styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, small-particle silicon carbide, large-particle silicon carbide, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate. The PPO-based dielectric composite material has excellent dielectric properties, thermal conductivity, processing performance, and mechanical properties, as well as a price advantage, and can be widely used in the field of electronic components requiring shielding and thermal conductivity functions.

Description

Technical Field

[0001] The present invention belongs to the field of materials, and in particular relates to a PPO-based dielectric composite material and a preparation method thereof. Background Art

[0002] As a popular material in the electrical and electronic field, polymer-based dielectric composites are widely used in microelectronic systems, high-temperature electronic devices, and energy storage devices due to their low price, good processing performance, and arbitrary shape design and control. With the development of science and technology and manufacturing, polymer-based dielectric composites have more and more applications, but they also face more and more challenges. For example, in the fields of aerospace, new energy vehicles, and integrated circuits, polymer-based dielectric materials need to maintain stable performance at high temperatures for a long time. Therefore, new polymer-based composite materials with high thermal conductivity, high dielectric constant, and low dielectric loss are urgently needed.

[0003] Polyphenylene ether (PPO) offers advantages such as high rigidity, excellent flame retardancy, high heat resistance, very low water absorption, and high strength. Its dielectric constant and dielectric loss are among the lowest among engineering plastics. PPO maintains excellent dielectric properties across a wide range of temperatures and frequencies, making it widely used in electronics, electrical appliances, 5G materials, and other fields.

[0004] Currently, some research has been conducted on PPO-based dielectric composites. For example, Chinese patent CN108117739A discloses a PPO composite material with a high dielectric constant at high frequencies. The composite material is composed, by weight, of the following raw materials: 20-29 parts PPO resin; 60-70 parts filler; 5-10 parts dielectric additive; and 1-1.5 parts processing aid. Chinese patent CN108117739A discloses a low-dielectric glass fiber-reinforced PC / PPO composite material and its preparation method. The PC / PPO composite material comprises, by weight, 29.8%-41.5% polycarbonate, 29.7%-38.0% modified polyphenylene ether, 20.0%-40.0% chopped low-dielectric glass fiber, 0.1%-0.4% antioxidant, and 0.3%-0.6% dispersant. Chinese patent CN 108164973A discloses a high dielectric polyphenylene ether material, its preparation method and application. The raw materials for preparing the polyphenylene ether material include the following components in parts by weight: 3070 parts by weight of PPO, 2040 parts by weight of high-impact polystyrene (HIPS) foam masterbatch, 3-10 parts by weight of single-walled carbon nanotubes, 0.5-1.5 parts by weight of graphene, 1020 parts by weight of a high dielectric filler, 1-4 parts by weight of a toughening agent, 0.3-0.8 parts by weight of an antioxidant and 0.5-2 parts by weight of a lubricant. Chinese patent CN 108164970A discloses a high thermal conductivity and low dielectric polyphenylene ether composite material and its preparation method. The composite material includes: 100 parts of polyphenylene ether resin, 10-40 parts of polystyrene resin, 80-160 parts of boron nitride, 5-15 parts of compatibilizer, 0.8-3.0 parts of coupling agent, 1.0-5.0 parts of dispersant, and 0.4-1.2 parts of antioxidant. Chinese patent CN110698839A discloses a high-dielectric-constant polyphenylene ether / high-impact polystyrene composition and its preparation method. The high-dielectric-constant polyphenylene ether / high-impact polystyrene composition is prepared from the following raw materials: a high-viscosity polyphenylene ether resin, a low-viscosity polyphenylene ether resin, a high-impact polystyrene resin, a copolymer of styrene and glycidyl methacrylate, toluene diisocyanate, a hydrogenated styrene isoprene copolymer grafted with maleic anhydride, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-benzenedicarboxamide, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate, zinc pentaerythritol, a high-dielectric-constant filler, a silane coupling agent, polyvinylidene fluoride, and a copper phthalocyanine oligomer. As can be seen from the above patent, the current prior art mainly uses ceramic dielectric materials, carbon-containing conductive fillers, and organic high-dielectric materials to prepare PPO-based dielectric composites. Summary of the Invention

[0005] Based on this, one of the objects of the present invention is to provide a PPO-based dielectric composite material, which has excellent dielectric properties and thermal conductivity and can be widely used in electronic and electrical components, 5G devices, etc.

[0006] The specific technical solutions for achieving the above-mentioned invention objectives include the following:

[0007] A PPO-based dielectric composite material is prepared from the following raw materials in parts by weight:

[0008]

[0009] In some embodiments, the PPO-based dielectric composite material is prepared from the following raw materials in parts by weight:

[0010]

[0011] In some embodiments, the PPO-based dielectric composite material is prepared from the following raw materials in parts by weight:

[0012]

[0013]

[0014] In some embodiments, the intrinsic viscosity of the polyphenylene ether resin is 35-38 mL / g, tested according to GB / T1632.1-2008 standard, and the solvent is chloroform.

[0015] In some embodiments, the general-purpose polystyrene has a number average molecular weight of 230,000 to 270,000 g / mol.

[0016] In some embodiments, the particle size of the barium titanate in the hyperbranched polyamide-coated barium titanate is 90-110 nm.

[0017] In some embodiments, the content of glycidyl methacrylate in the styrene-glycidyl methacrylate copolymer is 5-7 wt %; and the grafting rate of glycidyl methacrylate in the hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate is 0.8-1.6%.

[0018] In some embodiments, the small-particle silicon carbide is obtained by modifying silicon carbide with a particle size of 0.5-0.7 μm with γ-aminopropyltriethoxysilane, and the added amount of γ-aminopropyltriethoxysilane is 1.5-2.5 wt % of the weight of the silicon carbide.

[0019] In some embodiments, the large-particle silicon carbide is obtained by modifying silicon carbide with a particle size of 4 to 6 μm with γ-aminopropyltriethoxysilane, and the added amount of γ-aminopropyltriethoxysilane is 1.5 to 2.5 wt % of the weight of the silicon carbide.

[0020] In some embodiments, the preparation method of the hyperbranched polyamide-coated barium titanate is:

[0021] (1) 100 parts by weight of barium titanate (BT) was added to a flask containing 400-600 mL of a 25-35 wt% hydrogen peroxide solution, and the mixture was ultrasonically dispersed for 0.3-0.7 h using an ultrasonic rod, and then refluxed in an oil bath at 100-110° C. for 3-5 h. Finally, the barium titanate particles were washed with deionized water and vacuum dried at 75-85° C. for 10-14 h to obtain hydroxylated barium titanate (BT-OH);

[0022] (2) 100 parts by weight of hydroxylated barium titanate (BT-OH) was added to a flask containing 800-1000 mL of toluene, and the mixture was ultrasonically dispersed with an ultrasonic rod for 0.3-0.7 h, and then 40-60 parts by weight of γ-aminopropyltriethoxysilane (APS) was added, and nitrogen was introduced for 3-5 min. The mixture was refluxed in an oil bath at 75-85° C. for 20-24 h, and then the barium titanate particles were separated by centrifugation at a speed of 8000-10000 rpm for 4-6 min. Finally, the barium titanate particles were washed with toluene and vacuum dried at 75-85° C. for 10-14 h to obtain aminoated barium titanate (BT-NH2);

[0023] (3) 100 parts by weight of amide barium titanate (BT-NH2) was added to a flask containing 800-1000 mL of N-methylpyrrolidone, and the mixture was ultrasonically dispersed with an ultrasonic rod for 0.3-0.7 h. Then, 80-120 parts by weight of 3,5-diaminobenzoic acid was added and stirred until the 3,5-diaminobenzoic acid was dissolved. Then, 200-300 mL of pyridine, 200-300 mL of triphenyl phosphite and 2-3 parts by weight of lithium chloride were added. Nitrogen was introduced for 3-5 min, and the mixture was reacted in an oil bath at 90-110°C for 2-4 h. , cooled to room temperature in a nitrogen atmosphere, and then added 200-300 mL of a methanol solution containing 0.1% lithium chloride; then centrifuged to separate the hyperbranched polyamide-coated barium titanate particles at a speed of 8000-10000 rpm for 4-6 min, and finally washed the barium titanate particles with N-methylpyrrolidone, and vacuum dried at 75-85° C. for 10-14 h to obtain hyperbranched polyamide-coated barium titanate (BT-HBPA).

[0024] Another object of the present invention is to provide a method for preparing the above-mentioned PPO-based dielectric composite material.

[0025] The specific technical solutions for achieving the above-mentioned invention objectives include the following:

[0026] A method for preparing a PPO-based dielectric composite material comprises the following steps:

[0027] (1) drying the polyphenylene ether resin at a temperature of 110 to 120° C. for 2 to 4 hours, cooling the resin, and adding the cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate into a blender for mixing;

[0028] (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing them;

[0029] (3) adding the mixed material prepared in step (1) into a parallel twin-screw extruder via a feeder, and adding the mixed material prepared in step (2) into the side of the parallel twin-screw extruder (eight zones in total) for melt extrusion and granulation, wherein the process parameters include: a temperature of zone 1 of 260-280° C., a temperature of zone 2 of 265-285° C., a temperature of zone 3 of 270-290° C., a temperature of zone 4 of 270-290° C., a temperature of zone 5 of 270-290° C., a temperature of zone 6 of 270-290° C., a temperature of zone 7 of 270-290° C., a temperature of zone 8 of 270-290° C., a die head temperature of 265-285° C., and a screw speed of 300-700 rpm.

[0030] In some embodiments, the method for preparing the PPO-based dielectric composite material comprises the following steps:

[0031] (1) drying the polyphenylene ether resin at a temperature of 114 to 116° C. for 2.6 to 3.4 hours, cooling the resin, and adding the cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate into a blender for mixing;

[0032] (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing them;

[0033] (3) adding the mixed material prepared in step (1) into a parallel twin-screw extruder via a feeder, and adding the mixed material prepared in step (2) into the side of the parallel twin-screw extruder (eight zones in total) for melt extrusion and granulation, wherein the process parameters include: a temperature of zone 1 of 265-275° C., a temperature of zone 2 of 270-280° C., a temperature of zone 3 of 275-285° C., a temperature of zone 4 of 275-285° C., a temperature of zone 5 of 275-285° C., a temperature of zone 6 of 275-285° C., a temperature of zone 7 of 275-285° C., a temperature of zone 8 of 275-285° C., a die head temperature of 270-280° C., and a screw speed of 400-600 rpm.

[0034] In some embodiments, the screw shape of the parallel twin-screw extruder is a single-line thread; the ratio L / D of the screw length L and the diameter D is 35 to 55; and the screw is provided with one or more (including one) meshing block areas and one or more (including one) reverse thread areas.

[0035] In some embodiments, the ratio L / D of the screw length L to the diameter D is 40-50; and the screw is provided with two meshing block areas and one reverse thread area.

[0036] In some embodiments, in step (1) and / or step (2), the stirrer is a high-speed stirrer with a rotation speed of 500-1500 rpm.

[0037] The principle of the PPO-based dielectric composite material of the present invention and the functions of each raw material are as follows:

[0038] High dielectric materials have a very wide range of applications, and one of the main parameters for evaluating the performance of such materials is the dielectric constant. Therefore, to prepare high-performance dielectric materials, the first thing to do is to improve their dielectric constant. The dielectric constant of dielectric materials mainly comes from the polarization inside the material. To improve the dielectric constant of the material, the intensity of the polarization inside the material must be enhanced. The molecular mechanism of dielectric polarization under an electric field is relatively complex, and mainly includes four types: interface polarization, dipole orientation, ionic polarization, and electronic polarization. Among them, dipole orientation, ionic polarization, and electronic polarization are related to the composition of the material and their intrinsic electrical properties, while interface polarization is related to the interface structure of the composite material in addition to the intrinsic electrical properties of the material. In order to prepare nano-polymer composite materials with high dielectric constants, this patent improves dipole orientation, ionic polarization, and electronic polarization by selecting suitable high dielectric nanofillers and polymer matrices, and improves interface polarization by designing a unique interface structure with nano-specific structures, thereby significantly improving the dielectric constant of the composite material.

[0039] This patent uses barium titanate particles with a size of 90 to 110 nanometers as a filler to increase the dielectric constant of polymer composites. Barium titanate is a common ferroelectric ceramic that can spontaneously polarize and has a high dielectric constant. Barium titanate also has excellent insulation properties and stability, and the presence of reactive hydroxyl functional groups on its surface makes it feasible to design a special interface structure. Furthermore, the dielectric constant of barium titanate is related to its particle size, reaching a maximum value at around 1 micron and then decreasing with decreasing size, rapidly decreasing below 100 nanometers. Taking into account the nano effect of barium titanate and its own dielectric constant, this patent selects a barium titanate with a size of 90 to 110 nanometers.

[0040] The unique structure of hyperbranched polymers imparts excellent properties such as low viscosity, high rheological properties, and good solubility, providing a new approach for preparing modified barium titanate and improving its compatibility with polymer binders. Hyperbranched polymer-modified barium titanate exhibits many unique properties not possessed by linear polymer-modified barium titanate. Its spherical structure and numerous surface functional groups improve its dispersibility in polymer binders and enable the preparation of modified barium titanate with specialized functions, offering promising applications. This patent utilizes hyperbranched polyamide to coat barium titanate nanoparticles, creating a unique core-shell structure that improves the dielectric constant of the composite. The interfacial polarization of a composite material is related not only to the properties of its components but also to its interfacial structure. Interfacial polarization is caused by charge accumulation at the interface. Therefore, this patent enhances interfacial polarization by designing a specialized structure that facilitates charge accumulation. Hyperbranched polyamide was chosen to coat barium titanate because it has higher electrical conductivity and dielectric constant than other polymers. Inserting a layer of hyperbranched polyamide at the interface can promote the accumulation of charges at the interface, thereby increasing the interfacial polarization.

[0041] Among epoxy-type compatibilizers, the epoxy content of the styrene-glycidyl methacrylate copolymer is moderate, which can not only increase compatibility and improve mechanical properties, but also slightly reduce the melt index. The styrene structural unit has excellent compatibility with the polyphenylene ether resin. The epoxy groups of the glycidyl methacrylate structural unit can react with the terminal amino groups of the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide, as well as the terminal hydroxyl groups of the polyphenylene ether resin. Among them, the glycidyl methacrylate content in the styrene-glycidyl methacrylate copolymer is optimally 5-7wt%. This is because when the glycidyl methacrylate content is less than 5wt%, the number of its epoxy groups is insufficient to provide the functional groups required for the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide to react with the polymer substrate polyphenylene ether resin. When the glycidyl methacrylate content exceeds 7wt%, the excessive epoxy groups lead to crosslinking of the polyphenylene ether resin, thereby significantly reducing the melt index and the fluidity of the entire material.

[0042] Hydrogenated styrene-butadiene-styrene (HSBS) is produced by the selective hydrogenation of styrene-butadiene-styrene (SBS) and is a versatile thermoplastic elastomer. Due to the high saturation of its backbone, HSBS exhibits excellent weather resistance, heat resistance, and acid and alkali resistance, particularly in terms of resistance to oxidation, ozone, and UV-induced oxidation or cross-linking reactions. It is often added to polymers as a modifier. The styrene structural units in HSBS grafted with glycidyl methacrylate are highly compatible with polyphenylene ether resins. The epoxy groups of the grafted glycidyl methacrylate react with the terminal amino groups of hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide, as well as the terminal hydroxyl groups of the polyphenylene ether resin, thereby improving the dispersion of the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide in the polyphenylene ether base resin and enhancing its dielectric and thermal conductivity.

[0043] The presence of benzene rings in the polyphenylene ether (PPE) backbone imparts excellent mechanical properties, heat resistance, and chemical stability. However, these rings also make PPE difficult to process using conventional methods due to its high melt viscosity and susceptibility to internal stress cracking, significantly limiting its application. Currently, the most effective and commonly used method for modifying PPE is by blending it with other resins. PPE and general-purpose polystyrene exhibit strong interfacial bonding and are fully compatible within a certain composition range. Dynamic mechanical testing (DMA) shows that PPE / general-purpose polystyrene blends exhibit a single corresponding glass transition temperature over a wide composition range, indicating complete compatibility. The addition of general-purpose polystyrene effectively improves the processability of PPO, enabling its processing and molding through various methods such as extrusion, compression molding, and injection molding, broadening PPO's application. At the same time, the general-grade polystyrene used in this patent has a number average relative molecular mass of 230,000 to 270,000 g / mol, has good mechanical properties, and has little effect on the mechanical properties of the PPO-based dielectric composite material.

[0044] Silicon carbide has the advantages of high thermal conductivity, excellent high-temperature insulation properties, and a low thermal expansion coefficient. This patented compound utilizes γ-aminopropyltriethoxysilane-modified silicon carbide with a particle size of 0.5-0.7 μm and γ-aminopropyltriethoxysilane-modified silicon carbide with a particle size of 4-6 μm to improve the thermal conductivity of PPO-based dielectric composites. This is primarily because the gradation effect produced by various particle sizes facilitates the formation of a thermally conductive network. This means that by varying the filler size and the ratio of different sized fillers, the thermal conductivity of the composite can be more effectively improved without increasing the total amount of filler.

[0045] Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate belongs to the spirocyclic structure of pentaerythritol bisphosphite. Its high steric effect, high molecular weight and high effective phosphorus content determine its high hydrolytic stability, low volatility and high processing stability. It also overcomes the problems of traditional phosphorus-containing antioxidants that are prone to yellowing and hydrolysis resistance at high temperatures.

[0046] Compared with the prior art, the PPO-based dielectric composite material and its preparation method provided by the present invention have the following beneficial effects:

[0047] 1. In view of the defects of poor thermal conductivity and processing performance of traditional PPO-based dielectric composite materials, the present invention innovatively proposes to use hyperbranched polyamide to coat barium titanate nanoparticles to form a special core-shell structure to improve the dielectric constant of the composite material. At the same time, γ-aminopropyltriethoxysilane modified silicon carbide with different particle sizes and ratios is compounded to form more thermal conductive network chains through the grading effect without increasing the total amount of filler filling. In addition, epoxy-type compatibilizer styrene-methacrylate glycidyl copolymer and toughening agent hydrogenated styrene-butadiene-styrene grafted methacrylate are compounded. Glycidyl ester is used to improve the compatibility and interfacial adhesion between hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, large-particle silicon carbide and the polymer substrate polyphenylene ether resin, general-grade polystyrene is used to improve the processing performance of the PPO-based dielectric composite material, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate is used to improve the yellowing resistance and hydrolysis resistance of the PPO-based dielectric composite material. Through the synergistic cooperation of the above-mentioned additives, the PPO-based dielectric composite material of the present invention with excellent dielectric properties, thermal conductivity, processing properties and mechanical properties, as well as price advantages, can be obtained.

[0048] 2. The preparation method of the PPO-based dielectric composite material of the present invention has a simple process, is easy to control, and has low requirements on equipment. The equipment used is all general polymer processing equipment, and the investment is low, which is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a flow chart of the preparation process of the PPO-based dielectric composite material of the present invention. DETAILED DESCRIPTION

[0050] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the present invention more thorough and comprehensive.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] The reaction mechanism of the PPO-based dielectric composite material of the present invention is as follows (see the preparation process flow chart Figure 1 ):

[0053]

[0054] Among them, R1 is styrene-glycidyl methacrylate copolymer, or hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, R2 is polyphenylene ether resin, and R3 is hyperbranched polyamide-coated barium titanate, or small-particle silicon carbide, or large-particle silicon carbide.

[0055] Reaction mechanism

[0056] As can be seen from the above reaction formula, the epoxy functional groups of styrene-glycidyl methacrylate copolymer or hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate can react with the terminal hydroxyl groups of the polyphenylene ether resin and the terminal amino groups of the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide, thereby improving the compatibility and interfacial adhesion between the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide and the polymer matrix polyphenylene ether resin, improving the dispersibility of the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide in the polyphenylene ether matrix resin, reducing the occurrence of agglomeration, and thereby improving the dielectric properties and thermal conductivity of the PPO-based dielectric composite material.

[0057] The raw materials used in the Examples of the present invention and the Comparative Examples are as follows:

[0058] Polyphenylene ether resin with an intrinsic viscosity of 36 mL / g was purchased from Bluestar Chemical New Materials Co., Ltd.

[0059] Barium titanate, with a particle size of 100 nm, was purchased from Shandong Guoci Functional Materials Co., Ltd.

[0060] Hydrogen peroxide solution, with a concentration of 30 wt %, analytical grade, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0061] Toluene, analytical grade, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0062] γ-Aminopropyltriethoxysilane was purchased from Qingdao Hengda New Material Technology Co., Ltd.

[0063] N-Methylpyrrolidone (analytical grade) was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0064] 3,5-Diaminobenzoic acid was purchased from Jinsei Chemical Industry Co., Ltd., Tokyo, Japan.

[0065] Pyridine was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0066] Triphenyl phosphite was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0067] Lithium chloride was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0068] The styrene-glycidyl methacrylate copolymers in the examples and comparative examples except Comparative Example 2 had a glycidyl methacrylate content of 6 wt %, which was purchased from Jiayirong Polymer (Shanghai) Co., Ltd.

[0069] The styrene-glycidyl methacrylate copolymer in Comparative Example 2 has a glycidyl methacrylate content of 20 wt %, and was purchased from Jiayirong Polymer (Shanghai) Co., Ltd.

[0070] Hydrogenated styrene-butadiene-styrene grafted with glycidyl methacrylate, with a grafting rate of glycidyl methacrylate of 1.2%, was purchased from Shenyang Ketong New Materials Co., Ltd.

[0071] General-purpose polystyrene with a number average molecular weight of 250,000 g / mol was purchased from Dushanzi Petrochemical Company of PetroChina Co., Ltd.

[0072] Small-particle silicon carbide with a particle size of 0.6 μm was purchased from Zhengzhou Xinhua Furnace Material Technology Co., Ltd.

[0073] Large-particle silicon carbide with a particle size of 5 μm was purchased from Zhengzhou Xinhua Furnace Material Technology Co., Ltd.

[0074] Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0075] The small-particle silicon carbide used in the following examples and comparative examples is prepared by the following steps:

[0076] 100 g of silicon carbide with a particle size of 0.6 μm and 2 g of γ-aminopropyltriethoxysilane were uniformly mixed to obtain modified small-particle silicon carbide.

[0077] The large-particle silicon carbide used in the following examples and comparative examples is prepared by the following steps:

[0078] 100 g of silicon carbide with a particle size of 5 μm and 2 g of γ-aminopropyltriethoxysilane were uniformly mixed to obtain modified large-particle silicon carbide.

[0079] The hyperbranched polyamide-coated barium titanate used in the following examples and comparative examples is prepared by the following steps:

[0080] (1) 100 g of barium titanate (BT) was added to a flask containing 500 mL of a 30 wt% hydrogen peroxide solution. The mixture was ultrasonically dispersed for 0.5 h using an ultrasonic bar, and then refluxed in an oil bath at 105° C. for 4 h. Finally, the barium titanate particles were washed with deionized water and vacuum dried at 80° C. for 12 h to obtain hydroxylated barium titanate (BT-OH).

[0081] (2) 100 g of hydroxylated barium titanate (BT-OH) was added to a flask containing 900 mL of toluene. The mixture was ultrasonically dispersed for 0.5 h using an ultrasonic rod, and then 50 g of γ-aminopropyltriethoxysilane (APS) was added. Nitrogen was introduced for 4 min, and the mixture was refluxed in an oil bath at 80°C for 22 h. The barium titanate particles were then centrifuged at 9000 rpm for 5 min to separate the barium titanate particles. The barium titanate particles were finally washed with toluene and dried in a vacuum at 80°C for 12 h to obtain aminoated barium titanate (BT-NH2).

[0082] (3) 100 g of amino barium titanate (BT-NH2) was added to a flask containing 900 mL of N-methylpyrrolidone, and the mixture was ultrasonically dispersed for 0.5 h using an ultrasonic rod, and then 100 g of 3,5-diaminobenzoic acid was added and stirred until the 3,5-diaminobenzoic acid was dissolved. Then, 250 mL of pyridine, 250 mL of triphenyl phosphite and 2.5 g of lithium chloride were added, and nitrogen was introduced for 4 min. The mixture was reacted in an oil bath at 100 ° C for 3 h, and cooled to room temperature in a nitrogen atmosphere. Then, 250 mL of a methanol solution containing 0.1% lithium chloride was added; the hyperbranched polyamide-coated barium titanate particles were then separated by centrifugation at a speed of 9000 rpm for 5 min. Finally, the barium titanate particles were washed with N-methylpyrrolidone and vacuum dried at 80 ° C for 12 h to obtain hyperbranched polyamide-coated barium titanate (BT-HBPA);

[0083] The synthetic route of hyperbranched polyamide-coated barium titanate is as follows:

[0084]

[0085] The present invention is described in detail below with reference to specific embodiments.

[0086] Example 1 PPO-based dielectric composite material and preparation method thereof

[0087] The PPO-based dielectric composite material of this embodiment is prepared from the following raw materials in parts by weight:

[0088]

[0089] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0090] (1) drying the polyphenylene ether resin at 120° C. for 2 hours and then cooling the resin. The cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate were added to a blender and mixed.

[0091] (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing them;

[0092] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is fed into the side of the parallel twin-screw extruder (eight zones in total) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 280° C., a temperature of zone 2 of 285° C., a temperature of zone 3 of 290° C., a temperature of zone 4 of 290° C., a temperature of zone 5 of 290° C., a temperature of zone 6 of 290° C., a temperature of zone 7 of 290° C., a temperature of zone 8 of 290° C., a die head temperature of 285° C., and a screw speed of 700 rpm.

[0093] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L to the diameter D is 55; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and / or step (2), the mixer is a high-speed mixer with a rotation speed of 1500 rpm.

[0094] Example 2 PPO-based dielectric composite material and preparation method thereof

[0095] The PPO-based dielectric composite material of this embodiment is prepared from the following raw materials in parts by weight:

[0096]

[0097] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0098] (1) drying the polyphenylene ether resin at 110° C. for 4 hours and then cooling the resin. The cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate were added to a blender and mixed.

[0099] (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing them;

[0100] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder through a feeder, and the mixed material prepared in step (2) is fed into the side of the parallel twin-screw extruder (eight zones in total) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 260° C., a temperature of zone 2 of 265° C., a temperature of zone 3 of 270° C., a temperature of zone 4 of 270° C., a temperature of zone 5 of 270° C., a temperature of zone 6 of 270° C., a temperature of zone 7 of 270° C., a temperature of zone 8 of 270° C., a die head temperature of 265° C., and a screw speed of 300 rpm.

[0101] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L to the diameter D is 35; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and / or step (2), the mixer is a high-speed mixer with a rotation speed of 500 rpm.

[0102] Example 3 PPO-based dielectric composite material and preparation method thereof

[0103] The PPO-based dielectric composite material of this embodiment is prepared from the following raw materials in parts by weight:

[0104]

[0105] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0106] (1) drying the polyphenylene ether resin at 116° C. for 2.6 hours and then cooling the resin. The cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate were added to a blender and mixed.

[0107] (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing them;

[0108] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is fed into the side of the parallel twin-screw extruder (eight zones in total) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 275° C., a temperature of zone 2 of 280° C., a temperature of zone 3 of 285° C., a temperature of zone 4 of 285° C., a temperature of zone 5 of 285° C., a temperature of zone 6 of 285° C., a temperature of zone 7 of 285° C., a temperature of zone 8 of 285° C., a die head temperature of 280° C., and a screw speed of 600 rpm.

[0109] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L and the diameter D is 50; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and / or step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0110] Example 4 PPO-based dielectric composite material and preparation method thereof

[0111] The PPO-based dielectric composite material of this embodiment is prepared from the following raw materials in parts by weight:

[0112]

[0113] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0114] (1) drying the polyphenylene ether resin at 114° C. for 3.4 hours and then cooling the resin. The cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate were added to a blender and mixed.

[0115] (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing them;

[0116] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder via a feeder, and the mixed material prepared in step (2) is fed into the side of the parallel twin-screw extruder (eight zones in total) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265° C., a temperature of zone 2 of 270° C., a temperature of zone 3 of 275° C., a temperature of zone 4 of 275° C., a temperature of zone 5 of 275° C., a temperature of zone 6 of 275° C., a temperature of zone 7 of 275° C., a temperature of zone 8 of 275° C., a die head temperature of 270° C., and a screw speed of 400 rpm.

[0117] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L to the diameter D is 40; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and / or step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0118] Example 5 PPO-based dielectric composite material and preparation method thereof

[0119] The PPO-based dielectric composite material of this embodiment is prepared from the following raw materials in parts by weight:

[0120]

[0121]

[0122] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0123] (1) drying the polyphenylene ether resin at 115° C. for 3 hours and then cooling the resin. The cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate were added to a blender and mixed.

[0124] (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing them;

[0125] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder through a feeder, and the mixed material prepared in step (2) is fed into the side of the parallel twin-screw extruder (eight zones in total) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 270° C., a temperature of zone 2 of 275° C., a temperature of zone 3 of 280° C., a temperature of zone 4 of 280° C., a temperature of zone 5 of 280° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 280° C., a die head temperature of 275° C., and a screw speed of 500 rpm.

[0126] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L to the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and / or step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0127] Example 6 PPO-based dielectric composite material and preparation method thereof

[0128] The PPO-based dielectric composite material of this embodiment is prepared from the following raw materials in parts by weight:

[0129]

[0130] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0131] (1) drying the polyphenylene ether resin at 115° C. for 3 hours and then cooling the resin. The cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate were added to a blender and mixed.

[0132] (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing them;

[0133] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder through a feeder, and the mixed material prepared in step (2) is fed into the side of the parallel twin-screw extruder (eight zones in total) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 270° C., a temperature of zone 2 of 275° C., a temperature of zone 3 of 280° C., a temperature of zone 4 of 280° C., a temperature of zone 5 of 280° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 280° C., a die head temperature of 275° C., and a screw speed of 500 rpm.

[0134] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L to the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and / or step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0135] Example 7 PPO-based dielectric composite material and preparation method thereof

[0136] The PPO-based dielectric composite material of this embodiment is prepared from the following raw materials in parts by weight:

[0137]

[0138] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0139] (1) drying the polyphenylene ether resin at 115° C. for 3 hours and then cooling the resin. The cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate were added to a blender and mixed.

[0140] (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing them;

[0141] (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder through a feeder, and the mixed material prepared in step (2) is fed into the side of the parallel twin-screw extruder (eight zones in total) for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 270° C., a temperature of zone 2 of 275° C., a temperature of zone 3 of 280° C., a temperature of zone 4 of 280° C., a temperature of zone 5 of 280° C., a temperature of zone 6 of 280° C., a temperature of zone 7 of 280° C., a temperature of zone 8 of 280° C., a die head temperature of 275° C., and a screw speed of 500 rpm.

[0142] The screw shape of the parallel twin-screw extruder is a single-threaded screw; the ratio L / D of the screw length L to the diameter D is 45; the screw is provided with two meshing block areas and one reverse thread area; in step (1) and / or step (2), the mixer is a high-speed mixer with a rotation speed of 1000 rpm.

[0143] Comparative Example 1

[0144] The PPO-based dielectric composite material of this comparative example is prepared from the following raw materials in parts by weight:

[0145]

[0146] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0147] (1) Same as Example 1;

[0148] (2) adding the barium titanate, small-particle silicon carbide and large-particle silicon carbide into another mixer and mixing them;

[0149] (3) Same as Example 1.

[0150] Comparative Example 2

[0151] The PPO-based dielectric composite material of this comparative example is prepared from the following raw materials in parts by weight:

[0152]

[0153]

[0154] Wherein, the content of glycidyl methacrylate in the styrene-glycidyl methacrylate copolymer is 20 wt %.

[0155] The preparation method of the above-mentioned PPO-based dielectric composite material is the same as that in Example 1.

[0156] Comparative Example 3

[0157] The PPO-based dielectric composite material of this comparative example is prepared from the following raw materials in parts by weight:

[0158]

[0159] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0160] (1) drying the polyphenylene ether resin at 120° C. for 2 hours and then cooling the resin. The cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate were added to a blender and mixed.

[0161] (2) Same as Example 1;

[0162] (3) Same as Example 1.

[0163] Comparative Example 4

[0164] The PPO-based dielectric composite material of this comparative example is prepared from the following raw materials in parts by weight:

[0165]

[0166]

[0167] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0168] (1) drying the polyphenylene ether resin at 120° C. for 2 hours and then cooling the resin. The cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, the hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, and the bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate were added to a blender and mixed.

[0169] (2) Same as Example 1;

[0170] (3) Same as Example 1.

[0171] Comparative Example 5

[0172] The PPO-based dielectric composite material of this comparative example is prepared from the following raw materials in parts by weight:

[0173]

[0174] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0175] (1) Same as Example 1;

[0176] (2) adding the hyperbranched polyamide-coated barium titanate and small-particle silicon carbide into another mixer and mixing;

[0177] (3) Same as Example 1.

[0178] Comparative Example 6

[0179] The PPO-based dielectric composite material of this comparative example is prepared from the following raw materials in parts by weight:

[0180]

[0181]

[0182] The preparation method of the above-mentioned PPO-based dielectric composite material comprises the following steps:

[0183] (1) Same as Example 1;

[0184] (2) adding the hyperbranched polyamide-coated barium titanate and large-particle silicon carbide into another mixer and mixing;

[0185] (3) Same as Example 1.

[0186] The following is a table of raw material compositions for Examples 1-7 and Comparative Examples 1-6.

[0187] Table 1 Summary of raw material compositions of Examples 1-7 and Comparative Examples 1-6

[0188]

[0189] Note: a, hyperbranched polyamide-coated barium titanate was replaced by unmodified barium titanate with a particle size of 100 nm; b, styrene-glycidyl methacrylate copolymer, the content of glycidyl methacrylate was 6 wt%, was replaced by styrene-glycidyl methacrylate copolymer, the content of glycidyl methacrylate was 20 wt%.

[0190] Examples 1 to 7 are to prepare PPO-based dielectric composite materials by adjusting the addition amount of polyphenylene ether resin, hyperbranched polyamide-coated barium titanate, styrene-methacrylate glycidyl copolymer, hydrogenated styrene-butadiene-styrene grafted methacrylate glycidyl ester, general-purpose polystyrene, small particle size silicon carbide, large particle size silicon carbide, and bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate. Comparative Example 1 is to replace the hyperbranched polyamide-coated barium titanate with unmodified barium titanate (particle size of 100 nm), and Comparative Example 2 is to replace the styrene-methacrylate glycidyl copolymer with the unmodified barium titanate (particle size of 100 nm). The oil ester copolymer, the content of glycidyl methacrylate is 6wt%, is replaced by a styrene-glycidyl methacrylate copolymer, the content of glycidyl methacrylate is 20wt%, Comparative Example 3 is without adding hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, Comparative Example 4 is without adding general-purpose polystyrene, Comparative Example 5 is without increasing the total amount of filler filling, the addition amount of small-particle silicon carbide is 15 parts by weight, and Comparative Example 6 is without increasing the total amount of filler filling, the addition amount of large-particle silicon carbide is 15 parts by weight.

[0191] The PPO-based dielectric composite materials prepared in the above examples and comparative examples were subjected to the following performance tests:

[0192] Tensile strength: tested in accordance with GB / T 1040-2006 standard, with a tensile rate of 50 mm / min.

[0193] Notched impact strength: tested in accordance with GB / T 1843-2008 standard.

[0194] Melt index: tested in accordance with GB / T 3682-2000 standard, test conditions 280℃, 5kg.

[0195] Dielectric constant: tested according to GB / T 5597-1999 standard, test frequency 5GHz.

[0196] Thermal conductivity: tested according to ASTM D5470-2017 standard.

[0197] The performance test results are shown in Table 2.

[0198] Table 2 Performance of PPO-based dielectric composite materials of Examples 1-7 and Comparative Examples 1-6

[0199]

[0200] From Table 2 we can see that:

[0201] As the amount of polyphenylene ether resin added decreases and the amount of hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate added increases, the tensile strength of the PPO-based dielectric composite decreases, while the notched impact strength increases. This is mainly due to the higher tensile strength of the polyphenylene ether resin matrix and the lower tensile strength and higher notched impact strength of hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate.

[0202] As the amount of general-purpose polystyrene added decreases, the melt index of the PPO-based dielectric composite material decreases. This is primarily because the addition of general-purpose polystyrene effectively improves the processability of polyphenylene ether, enabling it to be processed and molded through various methods such as extrusion, compression molding, and injection molding, thus broadening the application of PPO. Furthermore, the general-purpose polystyrene used in this patent has a number-average relative molecular mass of 250,000 g / mol and exhibits excellent mechanical properties, thus having minimal impact on the mechanical properties of the PPO-based dielectric composite material.

[0203] As the amount of hyperbranched polyamide-coated barium titanate added increases, the dielectric constant of the PPO-based dielectric composite increases. This is primarily because this patent uses barium titanate particles with a size of 90 to 110 nanometers as a filler to increase the dielectric constant of the polymer composite. Barium titanate is a common ferroelectric ceramic that can spontaneously polarize and has a high dielectric constant. Barium titanate also has excellent insulating properties and stability, and the presence of reactive hydroxyl functional groups on its surface makes it feasible to design specialized interface structures. Furthermore, the dielectric constant of barium titanate is related to its particle size, reaching a maximum value at around 1 micron and then decreasing with decreasing size, rapidly decreasing below 100 nanometers. Taking into account both the nano-effect of barium titanate and its inherent dielectric constant, this patent selects a barium titanate particle size of 90 to 110 nanometers.

[0204] As the addition amount of small-particle silicon carbide and large-particle silicon carbide increases, the thermal conductivity of the PPO-based dielectric composite material increases. This is mainly because silicon carbide has the advantages of high thermal conductivity, excellent high-temperature insulation performance, and low thermal expansion coefficient. This patented compound uses γ-aminopropyltriethoxysilane-modified silicon carbide with a particle size of 0.5 to 0.7 μm and γ-aminopropyltriethoxysilane-modified silicon carbide with a particle size of 4 to 6 μm to improve the thermal conductivity of the PPO-based dielectric composite material. This is mainly because the grading effect produced by particles of various sizes is conducive to the formation of a thermal conductive network chain, that is, without increasing the total amount of filler filling, by changing the filler size and the ratio of fillers of different sizes, the thermal conductivity of the composite material can be more effectively improved.

[0205] In summary, by adjusting the addition amounts of polyphenylene ether resin, hyperbranched polyamide-coated barium titanate, styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, small-particle silicon carbide, large-particle silicon carbide, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate, and with the synergistic cooperation of various additives, the PPO-based dielectric composite material of the present invention having excellent dielectric properties, thermal conductivity, processing properties, and mechanical properties, as well as price advantages, can be obtained.

[0206] Compared with Example 1, Comparative Example 1 is a hyperbranched polyamide-coated barium titanate replaced with unmodified barium titanate (particle size is 100nm). Due to the unique structure of the hyperbranched polymer, it has excellent properties such as low viscosity, high rheology, and good solubility, providing a new way to prepare modified barium titanate and improve the compatibility of barium titanate with polymer base materials. Hyperbranched polymer-modified barium titanate has many unique properties that are not possessed by linear polymer-modified barium titanate. Structurally, it has a spherical structure and a large number of functional groups on its surface, so its dispersibility in the polymer base material is better, and modified barium titanate with special functions can be prepared, with broad application prospects. This patent forms a special core-shell structure by coating barium titanate nanoparticles with hyperbranched polyamide, thereby improving the dielectric constant of the composite material. The interfacial polarization of the composite material is not only related to the properties of the components of the composite material, but also to the interfacial structure of the composite material. Interfacial polarization is caused by the accumulation of charges at the interface. Therefore, this patent improves interfacial polarization by designing a special structure that facilitates charge accumulation. Hyperbranched polyamide was chosen to coat barium titanate because it has higher conductivity and dielectric constant than other polymers. Inserting a layer of hyperbranched polyamide at the interface can promote charge accumulation at the interface, thereby improving interfacial polarization. Therefore, the dielectric constant of Comparative Example 1 is lower than that of Example 1.

[0207] Compared with Example 1, Comparative Example 2 is a styrene-glycidyl methacrylate copolymer with a glycidyl methacrylate content of 6wt%. Instead, it is a styrene-glycidyl methacrylate copolymer with a glycidyl methacrylate content of 20wt%. When the glycidyl methacrylate content exceeds 7wt%, the excessive epoxy groups lead to crosslinking of the polyphenylene ether resin, thereby significantly reducing the melt index and the fluidity of the entire material. At the same time, it affects the dispersibility of the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide in the polyphenylene ether base resin, reducing the dielectric constant and thermal conductivity of the PPO-based dielectric composite material. Therefore, the melt index, dielectric constant, and thermal conductivity of Comparative Example 2 are all lower than those of Example 1.

[0208] Compared to Example 1, Comparative Example 3 does not include hydrogenated styrene-butadiene-styrene grafted with glycidyl methacrylate. Hydrogenated styrene-butadiene-styrene, produced by selective hydrogenation of styrene-butadiene-styrene, is a versatile thermoplastic elastomer. The high saturation of the hydrogenated styrene-butadiene-styrene backbone imparts excellent weather resistance, heat resistance, and acid and alkali resistance, particularly in terms of resistance to oxidation, ozone, and UV-induced oxidation or crosslinking reactions. It is often added to polymers as a modifier. The styrene structural units in the hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate have excellent compatibility with the polyphenylene ether resin. The epoxy groups of the grafted glycidyl methacrylate can react with the terminal amino groups of the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide, as well as the terminal hydroxyl groups of the polyphenylene ether resin. This improves the dispersibility of the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide in the polyphenylene ether base resin, and enhances the dielectric properties and thermal conductivity. Therefore, the notched impact strength, dielectric constant, and thermal conductivity of Comparative Example 3 are lower than those of Example 1.

[0209] Compared with Example 1, Comparative Example 4 does not add general-purpose polystyrene. Due to the presence of benzene rings on the polyphenylene ether main chain, it has excellent mechanical properties, heat resistance and chemical stability. However, these benzene rings also make it difficult for polyphenylene ether to be processed and shaped by common means due to high melt viscosity and easy internal stress cracking during processing, thereby greatly limiting the application of polyphenylene ether. The addition of general-purpose polystyrene can effectively improve its processability, enabling it to be processed and shaped by many methods such as extrusion, compression molding, and injection, widening the application of PPO. At the same time, the reduction of melt index affects the dispersibility of hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide in the polyphenylene ether base resin, reducing the dielectric constant and thermal conductivity of the PPO-based dielectric composite material. Therefore, the melt index, dielectric constant and thermal conductivity of Comparative Example 4 are all lower than those of Example 1.

[0210] Compared with Example 1, in Comparative Example 5, the amount of small-particle silicon carbide added is 15 parts by weight without increasing the total amount of filler filling, and in Comparative Example 6, the amount of large-particle silicon carbide added is 15 parts by weight without increasing the total amount of filler filling. Since silicon carbide has the advantages of high thermal conductivity, excellent high-temperature insulation performance, and low thermal expansion coefficient, this patent compound uses γ-aminopropyltriethoxysilane-modified silicon carbide with a particle size of 0.5 to 0.7 μm and γ-aminopropyltriethoxysilane-modified silicon carbide with a particle size of 4 to 6 μm to improve the thermal conductivity of the PPO-based dielectric composite material. This is mainly because the grading effect produced by particles of various sizes is conducive to the formation of a thermal conductive network chain, that is, without increasing the total amount of filler filling, by changing the filler size and the ratio of fillers of different sizes, the thermal conductivity of the composite material can be more effectively improved. Therefore, the thermal conductivity of Comparative Examples 5 and 6 is lower than that of Example 1.

[0211] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0212] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A PPO-based dielectric composite material, characterized in that: It is prepared from the following raw materials in parts by weight: 50-70 parts of polyphenylene ether resin, 30-50 parts of hyperbranched polyamide coated barium titanate, 2 to 6 parts of styrene-glycidyl methacrylate copolymer, 2 to 6 parts of hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, 5-15 parts of general-purpose polystyrene, 12-20 parts of small-particle silicon carbide, 3-5 parts of large-particle silicon carbide, 0.2-0.6 parts of bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate; The content of glycidyl methacrylate in the styrene-glycidyl methacrylate copolymer is 5 to 7 wt %; the small-particle silicon carbide is obtained by modifying silicon carbide with a particle size of 0.5 to 0.7 μm by γ-aminopropyltriethoxysilane, and the amount of γ-aminopropyltriethoxysilane added is 1.5 to 2.5 wt % of the weight of the silicon carbide; and / or the large-particle silicon carbide is obtained by modifying silicon carbide with a particle size of 4 to 6 μm by γ-aminopropyltriethoxysilane, and the amount of γ-aminopropyltriethoxysilane added is 1.5 to 2.5 wt % of the weight of the silicon carbide.

2. The PPO-based dielectric composite material according to claim 1, characterized in that: It is prepared from the following raw materials in parts by weight: 55-65 parts of polyphenylene ether resin, 35-45 parts of hyperbranched polyamide coated barium titanate, 3 to 5 parts of styrene-glycidyl methacrylate copolymer, 3-5 parts of hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, 7-13 parts of general-purpose polystyrene, 14-18 parts of small-particle silicon carbide, 3.5-4.5 parts of large particle size silicon carbide, 0.3 to 0.5 parts of bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate 3. The PPO-based dielectric composite material according to claim 2, characterized in that: It is prepared from the following raw materials in parts by weight: 58-62 parts of polyphenylene ether resin, 38-42 parts of hyperbranched polyamide coated barium titanate, 3.5 to 4.5 parts of styrene-glycidyl methacrylate copolymer, 3.5-4.5 parts of hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, 9-11 parts of general-purpose polystyrene, 15-17 parts of small-particle silicon carbide, 3.75-4.25 parts of large particle size silicon carbide, 0.35 to 0.45 parts of bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate 4. The PPO-based dielectric composite material according to any one of claims 1 to 3, characterized in that: The intrinsic viscosity of the polyphenylene ether resin is 35 to 38 mL / g; and / or the number average relative molecular mass of the general-grade polystyrene is 230,000 to 270,000 g / mol; and / or the particle size of the barium titanate in the hyperbranched polyamide-coated barium titanate is 90 to 110 nm.

5. The PPO-based dielectric composite material according to any one of claims 1 to 3, characterized in that: The grafting rate of glycidyl methacrylate in the hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate is 0.8-1.6%.

6. The PPO-based dielectric composite material according to any one of claims 1 to 3, characterized in that: The preparation method of the hyperbranched polyamide-coated barium titanate is: (1) 100 parts by weight of barium titanate was added to a flask containing 400-600 mL of a 25-35 wt% hydrogen peroxide solution, the mixture was ultrasonically dispersed for 0.3-0.7 h using an ultrasonic rod, and then refluxed in an oil bath at 100-110° C. for 3-5 h. Finally, the barium titanate particles were washed with deionized water and vacuum dried at 75-85° C. for 10-14 h to obtain hydroxylated barium titanate. (2) 100 parts by weight of hydroxylated barium titanate was added to a flask containing 800-1000 mL of toluene, and the mixture was ultrasonically dispersed with an ultrasonic rod for 0.3-0.7 h, and then 40-60 parts by weight of γ-aminopropyltriethoxysilane was added, and nitrogen was introduced for 3-5 min. The mixture was refluxed in an oil bath at 75-85°C for 20-24 h, and then the barium titanate particles were separated by centrifugation at a speed of 8000-10000 rpm for 4-6 min. Finally, the barium titanate particles were washed with toluene and vacuum dried at 75-85°C for 10-14 h to obtain aminoated barium titanate. (3) 100 parts by weight of amino barium titanate were added to a flask containing 800-1000 mL of N-methylpyrrolidone, and the mixture was ultrasonically dispersed with an ultrasonic rod for 0.3-0.7 h, and then 80-120 parts by weight of 3,5-diaminobenzoic acid was added and stirred until the 3,5-diaminobenzoic acid was dissolved, and then 200-300 mL of pyridine, 200-300 mL of triphenyl phosphite and 2-3 parts by weight of lithium chloride were added, and nitrogen was introduced for 3-5 min. The mixture was reacted in an oil bath at 90-110°C for 2-4 h, and cooled to room temperature in a nitrogen atmosphere. Then, 200-300 mL of a methanol solution containing 0.1% lithium chloride was added; the hyperbranched polyamide-coated barium titanate particles were then separated by centrifugation at a speed of 8000-10000 rpm for 4-6 min. min, and finally the barium titanate particles were washed with N-methylpyrrolidone and dried in vacuum at 75-85°C for 10-14 h to obtain hyperbranched polyamide-coated barium titanate.

7. A method for preparing the PPO-based dielectric composite material according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) drying the polyphenylene ether resin at a temperature of 110 to 120° C. for 2 to 4 hours, cooling the resin, and adding the cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate into a blender for mixing; (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing; (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder through a feeder, and the mixed material prepared in step (2) is fed into the side of the parallel twin-screw extruder for melt extrusion and granulation. The process parameters include: the temperature of zone 1 is 260-280°C, the temperature of zone 2 is 265-285°C, the temperature of zone 3 is 270-290°C, the temperature of zone 4 is 270-290°C, the temperature of zone 5 is 270-290°C, the temperature of zone 6 is 270-290°C, the temperature of zone 7 is 270-290°C, the temperature of zone 8 is 270-290°C, the die head temperature is 265-285°C, and the screw speed is 300-700rpm.

8. The preparation method according to claim 7, characterized in that The preparation method of the PPO-based dielectric composite material comprises the following steps: (1) drying the polyphenylene ether resin at a temperature of 114 to 116° C. for 2.6 to 3.4 hours, cooling the resin, and adding the cooled polyphenylene ether resin, the styrene-glycidyl methacrylate copolymer, hydrogenated styrene-butadiene-styrene grafted glycidyl methacrylate, general-purpose polystyrene, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphate into a blender for mixing; (2) adding the hyperbranched polyamide-coated barium titanate, small-particle silicon carbide, and large-particle silicon carbide into another mixer and mixing; (3) The mixed material prepared in step (1) is fed into a parallel twin-screw extruder through a feeder, and the mixed material prepared in step (2) is fed into the side of the parallel twin-screw extruder for melt extrusion and granulation. The process parameters include: a temperature of zone 1 of 265 to 275°C, a temperature of zone 2 of 270 to 280°C, a temperature of zone 3 of 275 to 285°C, a temperature of zone 4 of 275 to 285°C, a temperature of zone 5 of 275 to 285°C, a temperature of zone 6 of 275 to 285°C, a temperature of zone 7 of 275 to 285°C, a temperature of zone 8 of 275 to 285°C, a die head temperature of 270 to 280°C, and a screw speed of 400 to 600 rpm.

9. The preparation method according to any one of claims 7-8, characterized in that The screw shape of the parallel twin-screw extruder is a single-threaded screw; and / or, the ratio L / D of the screw length L and the diameter D of the parallel twin-screw extruder is 35 to 55; and / or, the screw of the parallel twin-screw extruder is provided with one or more meshing block areas and one or more reverse thread areas; in step (1) and / or step (2), the mixer is a high-speed mixer with a rotation speed of 500-1500 rpm.

10. The preparation method according to claim 9, characterized in that The ratio L / D of the screw length L to the diameter D of the parallel twin-screw extruder is 40-50; and / or the screw of the parallel twin-screw extruder is provided with two meshing block areas and one reverse thread area.

Images