A thermally conductive electromagnetic shielding PBT-based composite material and a preparation method thereof

Abstract

The application relates to a heat-conducting electromagnetic shielding PBT-based composite material and a preparation method thereof, and relates to the technical field of composite materials, which is prepared from the following raw materials in parts by weight: PBT matrix resin 100 parts, toughened graphene heat-conducting master batch 5-20 parts, heat-conducting filler alumina 5-8 parts, carbon nanotube 8-10 parts, short carbon fiber 3-8 parts, boron nitride nanosheet 1-3 parts, hexafluorobisphenol A diacrylate 1-3 parts, hyperbranched unsaturated resin 2-4 parts, coupling agent 1-3 parts, antioxidant 0.1-0.5 parts, lubricant 0.5-1.5 parts, aminoethylized acrylic acid polymer 3-5 parts, carbodiimide 0.3-1 part, dicumyl peroxide 0.3-0.8 part. The composite material has better heat-conducting performance, higher mechanical strength and impact toughness, more excellent aging resistance, and a longer service life.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a thermally conductive and electromagnetically shielded PBT-based composite material and its preparation method. Background Technology

[0002] Polybutylene terephthalate (PBT), a thermoplastic polyester resin with excellent comprehensive properties, possesses outstanding mechanical properties, good chemical resistance, heat resistance, and excellent electrical insulation, and has been widely used in many fields such as electronics, automotive manufacturing, and mechanical engineering. However, its extremely low thermal conductivity has become a key bottleneck restricting its application in scenarios with high heat dissipation requirements. With the rapid development of industries such as 5G communication and new energy vehicles, the power density of electronic components continues to rise, placing more stringent demands on the thermal conductivity and electromagnetic shielding functions of packaging materials. Traditional PBT materials can no longer meet the needs of practical applications.

[0003] To address the poor thermal conductivity of PBT, a common method is to add thermally conductive fillers. Common thermally conductive fillers include alumina (…). Inorganic materials such as boron nitride (BN) and aluminum nitride (AlN) can improve the thermal conductivity of composite materials to some extent, but they also have many drawbacks. Firstly, these inorganic fillers have poor compatibility with the PBT resin matrix and are difficult to disperse uniformly within the matrix, resulting in numerous interfacial defects within the composite material. This not only affects thermal conductivity but also reduces the material's mechanical properties, which is extremely detrimental to applications requiring high overall material performance. Secondly, achieving good thermal conductivity often requires adding large amounts of thermally conductive fillers. This not only increases material costs but also worsens the composite material's processing flowability, increases molding difficulty, and makes it difficult to meet the processing requirements of complex-shaped products. It also increases the material's density, making it unsuitable for applications with strict weight limitations (such as aerospace and portable electronic devices). To achieve electromagnetic shielding, carbon black, graphite, and metals are commonly used as fillers. However, to achieve effective electromagnetic shielding, traditional PBT materials with electromagnetic shielding functions require excessive filler additions, leading to a significant decrease in the material's mechanical properties. Commercially available thermally conductive and electromagnetically shielding PBT-based composite materials still have some technical defects, such as insufficient mechanical strength and impact toughness, and the need to further improve their aging resistance and thermal conductivity.

[0004] To address the aforementioned issues, Chinese invention patent CN115536998B discloses an electromagnetic shielding and thermally conductive PBT / PET-based composite material and its preparation method. This composite material is prepared from the following raw materials: PBT, PET, flake graphite, zinc oxide, barium ferrite, POE-g-GMA, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and β-(4-hydroxyphenyl-3,5-di-tert-butyl)propionate (octadecyl alcohol ester). This PBT / PET-based composite material exhibits excellent electromagnetic shielding and thermal conductivity, making it widely applicable in electronic components requiring both shielding and thermal conductivity. However, its impact toughness, mechanical strength, and aging resistance still require further improvement.

[0005] It is evident that it is necessary to seek more effective methods to prepare thermally conductive and electromagnetically shielded PBT-based composite materials with better thermal conductivity, mechanical strength, electromagnetic shielding effectiveness and impact toughness, superior aging resistance and longer service life. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a thermally conductive electromagnetic shielding PBT-based composite material and its preparation method, which has better thermal performance, mechanical strength, electromagnetic shielding effectiveness and impact toughness, better aging resistance and longer service life.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a thermally conductive and electromagnetically shielding PBT-based composite material, comprising the following raw materials in parts by weight: 100 parts of PBT matrix resin, 5-20 parts of toughened graphene thermally conductive masterbatch, 5-8 parts of thermally conductive alumina filler, 8-10 parts of carbon nanotubes, 3-8 parts of chopped carbon fibers, 1-3 parts of boron nitride nanosheets, 1-3 parts of bisphenol A diacrylate, 2-4 parts of hyperbranched unsaturated resin, 1-3 parts of coupling agent, 0.1-0.5 parts of antioxidant, 0.5-1.5 parts of lubricant, 3-5 parts of aminoethylated acrylic polymer, 0.3-1 part of carbodiimide, and 0.3-0.8 parts of dicumyl peroxide.

[0008] Preferably, the intrinsic viscosity of the PBT matrix resin is 0.8-1.2 dL / g.

[0009] Preferably, the PBT matrix resin is Kanghui New Materials' PBT KH2100.

[0010] Preferably, the preparation method of the toughened graphene thermally conductive masterbatch includes the following steps: uniformly dispersing graphene in an ethanol aqueous solution, adding a multifunctional additive, ultrasonicating for 30-40 minutes, and drying in an oven at 115-123℃ for 2-4 hours to obtain pretreated graphene; then, uniformly mixing the pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer using a high-speed mixer, and then co-extruding and granulating the mixture using a twin-screw extruder to obtain the toughened graphene thermally conductive masterbatch.

[0011] Preferably, the graphene is a single-layer graphene with a thickness of 0.8-1.2 nm and a sheet diameter of 0.5-5 μm.

[0012] Preferably, the mass percentage concentration of the ethanol aqueous solution is 10-20%.

[0013] Preferably, the multifunctional additive is at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH-570.

[0014] Preferably, the mass ratio of graphene, ethanol aqueous solution, and multifunctional additive is 1:(3-5):(0.03-0.05).

[0015] Preferably, the mass ratio of the pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer is 1:2:9:5:3.

[0016] Preferably, the thermoplastic polyester elastomer is TPEE model 8238 manufactured by DuPont.

[0017] Preferably, the intrinsic viscosity of the polybutylene terephthalate resin is 1.2 dL / g.

[0018] Preferably, the core-shell structured methyl methacrylate-butadiene-styrene terpolymer is designated as MBS EM-500.

[0019] Preferably, the grade of the ethylene-butyl acrylate-glycidyl methacrylate copolymer is [grade number missing]. .

[0020] Preferably, the temperature of the co-extrusion is 230-250°C.

[0021] Preferably, the average particle size of the thermally conductive filler alumina is 100-400 nm.

[0022] Preferably, the carbon nanotubes are multi-walled carbon nanotubes with a length of 0.5-2 μm and a diameter of 50 nm.

[0023] Preferably, the chopped carbon fibers have an average diameter of 10 μm and a length of 4-5 mm.

[0024] Preferably, the boron nitride nanosheets have a diameter of 0.1-0.4 μm.

[0025] Preferably, the hyperbranched unsaturated resin is the hyperbranched unsaturated resin HyPer U102.

[0026] Preferably, the coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH-570.

[0027] Preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 168, and antioxidant 1076.

[0028] Preferably, the lubricant is one or more of calcium stearate, zinc stearate, and ethylene bis-stearamide.

[0029] Preferably, the aminoethylated acrylic polymer is aminoethylated acrylic polymer HD-105-PMA.

[0030] Another objective of this invention is to provide a method for preparing the thermally conductive and electromagnetically shielded PBT-based composite material, comprising the following steps: adding each raw material in parts by weight into a high-speed mixer and mixing them evenly to obtain a mixture; then extruding the mixture through a twin-screw extruder; and finally, granulating the mixture after water cooling to obtain the thermally conductive and electromagnetically shielded PBT-based composite material of this invention.

[0031] Preferably, the specific process parameters for the co-extrusion of the twin-screw extruder are as follows: the twin-screw extruder is divided into ten temperature zones, with zone 1 at 230-235℃, zone 2 at 230-235℃, zone 3 at 230-235℃, zone 4 at 235-240℃, zone 5 at 235-240℃, zone 6 at 240-245℃, zone 7 at 240-245℃, zone 8 at 245-250℃, zone 9 at 245-250℃, and zone 10 at 245-250℃; the die head temperature is 250-255℃; and the rotational speed of the twin-screw extruder is 290-380 rpm.

[0032] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0033] (1) The preparation method of the thermally conductive electromagnetic shielding PBT-based composite material disclosed in this invention is simple, easy to control, and does not require high equipment. The equipment used is all general polymer processing equipment, and the investment is not high, which is conducive to industrial production.

[0034] (2) The thermally conductive electromagnetic shielding PBT-based composite material disclosed in this invention uses toughened graphene thermally conductive masterbatch (high thermal conductivity + easy dispersion), boron nitride nanosheets (sheet structure) to provide macroscopic thermal conduction pathways, alumina (granular) to fill the gaps between sheets, and short-cut carbon fibers (fiber-like) to bridge the thermally conductive units in different regions, forming a three-dimensional complementary thermally conductive network of "sheet-particle-fiber", which greatly reduces the thermal bottleneck; the combination of graphene and boron nitride takes into account high thermal conductivity, and the insulation of boron nitride can avoid the problem of excessive conductivity caused by single graphene, which is suitable for electronic packaging and other scenarios that require "thermal conductivity + insulation". Toughened graphene thermally conductive masterbatch, after toughening modification, retains the reinforcing effect of graphene while compensating for the brittleness of PBT itself, thus improving the material's impact resistance. Short-cut carbon fibers (high strength, high modulus) are bonded to the PBT matrix through coupling agents and aminoethylated acrylic polymers to enhance the interface, significantly improving tensile strength, flexural strength, and rigidity. The addition of hyperbranched unsaturated resin not only further improves impact toughness but also reduces interfacial stress, avoiding mechanical property degradation caused by filler agglomeration, achieving a balance between "high thermal conductivity" and "high strength and high toughness".

[0035] (3) The thermally conductive and electromagnetically shielding PBT-based composite material disclosed in this invention is prone to hydrolysis of the ester groups in the PBT molecular chain under humid and hot conditions, leading to performance degradation. Existing technologies have limited improvements in hydrolysis resistance. In this formulation: carbodiimide can react with the carboxyl groups generated by PBT hydrolysis, inhibiting the hydrolysis chain reaction and significantly improving the long-term stability of the material under humid and high-temperature conditions; the amino groups of the aminoethylated acrylic polymer can combine with the terminal carboxyl groups of PBT, further enhancing the hydrolysis resistance, making the material applicable to humid and hot environments such as automotive engine compartments and bathroom equipment. The lubricant reduces the friction between the melt and the equipment, and the hyperbranched unsaturated resin reduces the viscosity of the system due to the branched structure, improving fluidity; toughened graphene is added in the form of masterbatch, and the short-cut carbon fiber is controlled at 3-8 parts, all of which avoid the processing blockage problem caused by filler agglomeration, and can be directly produced by conventional processes such as extrusion.

[0036] (4) The thermally conductive electromagnetic shielding PBT-based composite material disclosed in this invention has antioxidants that inhibit the oxidative degradation of the material during processing and use. Dicumyl peroxide initiates the cross-linking of hexafluorobisphenol A diacrylate and hyperbranched unsaturated resin to form a three-dimensional network, thereby improving the heat distortion temperature and weather resistance. The introduction of the hexafluorobisphenol A structure enhances the chemical resistance of the material (such as oil and solvent resistance). Combined with antioxidants and cross-linking networks, the material can maintain stable performance under long-term high temperature or complex environment, thus extending its service life.

[0037] (5) The thermally conductive electromagnetic shielding PBT-based composite material disclosed in this invention, and the preparation method of the toughened graphene thermally conductive masterbatch, through the four-fold design of "efficient dispersion-synergistic toughening-interface optimization-process simplification", has significantly improved the graphene dispersibility, masterbatch comprehensive performance (thermal conductivity + mechanical properties), compatibility with matrix and industrial feasibility compared with the prior art, providing a key guarantee for the preparation of high-performance thermally conductive composite materials.

[0038] (6) The thermally conductive and electromagnetically shielding PBT-based composite material disclosed in this invention is made from the following raw materials in parts by weight: 100 parts PBT matrix resin, 5-20 parts toughened graphene thermally conductive masterbatch, 5-8 parts thermally conductive filler alumina, 8-10 parts carbon nanotubes, 3-8 parts chopped carbon fibers, 1-3 parts boron nitride nanosheets, 1-3 parts hexafluorobisphenol A diacrylate, 2-4 parts hyperbranched unsaturated resin, 1-3 parts coupling agent, 0.1-0.5 parts antioxidant, 0.5-1.5 parts lubricant, 3-5 parts aminoethylated acrylic polymer, 0.3-1 part carbodiimide, and 0.3-0.8 parts dicumyl peroxide. Through the synergistic effect of the various raw materials, the resulting composite material exhibits better thermal conductivity, higher mechanical strength, better electromagnetic shielding effectiveness and impact toughness, superior aging resistance, and a longer service life. Detailed Implementation

[0039] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0040] Example 1: A thermally conductive and electromagnetically shielding PBT-based composite material, comprising the following raw materials in parts by weight: 100 parts PBT matrix resin, 5 parts toughened graphene thermally conductive masterbatch, 5 parts thermally conductive filler alumina, 8 parts carbon nanotubes, 3 parts chopped carbon fibers, 1 part boron nitride nanosheets, 1 part hexafluorobisphenol A diacrylate, 2 parts hyperbranched unsaturated resin, 1 part coupling agent, 0.1 part antioxidant, 0.5 parts lubricant, 3 parts aminoethylated acrylic polymer, 0.3 parts carbodiimide, and 0.3 parts dicumyl peroxide.

[0041] The PBT matrix resin is Kanghui New Materials' PBT KH2100.

[0042] The preparation method of the toughened graphene thermally conductive masterbatch includes the following steps: graphene is uniformly dispersed in an ethanol aqueous solution, a multifunctional additive is added, ultrasonication is performed for 30 minutes, and drying is carried out in an oven at 115°C for 2 hours to obtain pretreated graphene; then, the pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer are mixed uniformly using a high-speed mixer, and then co-extruded and granulated using a twin-screw extruder to obtain the toughened graphene thermally conductive masterbatch; the graphene is a single-layer graphene with a thickness of 0.8-1.2 nm and a sheet diameter of 0.5-5 μm; the mass of the ethanol aqueous solution is... The concentration is 10%; the multifunctional additive is silane coupling agent KH550; the mass ratio of graphene, ethanol aqueous solution, and multifunctional additive is 1:3:0.03; the mass ratio of pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell structured methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer is 1:2:9:5:3; the thermoplastic polyester elastomer is TPEE model 8238 manufactured by DuPont; the intrinsic viscosity of polybutylene terephthalate resin is 1.2 dL / g; the grade of the core-shell structured methyl methacrylate-butadiene-styrene terpolymer is MBS EM-500; the grade of the ethylene-butyl acrylate-glycidyl methacrylate copolymer is... The temperature of the co-extrusion is 230-250℃.

[0043] The thermally conductive filler alumina has an average particle size of 100 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 0.5-2 μm and a diameter of 50 nm; the chopped carbon fibers have an average diameter of 10 μm and a length of 4-5 mm; the boron nitride nanosheets have a sheet diameter of 0.1-0.4 μm; the hyperbranched unsaturated resin is hyperbranched unsaturated resin HyPer U102; the coupling agent is silane coupling agent KH550; the antioxidant is antioxidant 1010; the lubricant is calcium stearate; and the aminoethylated acrylic polymer is aminoethylated acrylic polymer HD-105-PMA.

[0044] A method for preparing the thermally conductive and electromagnetically shielded PBT-based composite material includes the following steps: adding each raw material according to its weight proportions into a high-speed mixer and mixing them evenly to obtain a mixture; then, extruding the mixture through a twin-screw extruder; after water cooling, pelletizing to obtain the thermally conductive and electromagnetically shielded PBT-based composite material of the present invention; the specific process parameters of the twin-screw extruder are as follows: the twin-screw extruder is divided into ten temperature zones, zone 1 temperature is 230℃, zone 2 temperature is 230℃, zone 3 temperature is 230℃, zone 4 temperature is 235℃, zone 5 temperature is 235℃, zone 6 temperature is 240℃, zone 7 temperature is 240℃, zone 8 temperature is 245℃, zone 9 temperature is 245℃, and zone 10 temperature is 245℃; the die head temperature is 250℃; and the rotation speed of the twin-screw extruder is 290 rpm.

[0045] Example 2: A thermally conductive and electromagnetically shielding PBT-based composite material, comprising the following raw materials in parts by weight: 100 parts PBT matrix resin, 10 parts toughened graphene thermally conductive masterbatch, 6 parts thermally conductive filler alumina, 8.5 parts carbon nanotubes, 4 parts chopped carbon fibers, 1.5 parts boron nitride nanosheets, 1.5 parts hexafluorobisphenol A diacrylate, 2.5 parts hyperbranched unsaturated resin, 1.5 parts coupling agent, 0.2 parts antioxidant, 0.7 parts lubricant, 3.5 parts aminoethylated acrylic polymer, 0.6 parts carbodiimide, and 0.5 parts dicumyl peroxide; wherein the PBT matrix resin is Kanghui New Materials' PBT KH2100.

[0046] The preparation method of the toughened graphene thermally conductive masterbatch includes the following steps: graphene is uniformly dispersed in an ethanol aqueous solution, a multifunctional additive is added, ultrasonication is performed for 33 minutes, and drying is carried out in an oven at 117°C for 2.5 hours to obtain pretreated graphene; then, the pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer are mixed uniformly using a high-speed mixer, and then co-extruded using a twin-screw extruder and granulated to obtain the toughened graphene thermally conductive masterbatch; the graphene is a single-layer graphene with a thickness of 0.8-1.2 nm and a sheet diameter of 0.5-5 μm; the mass of the ethanol aqueous solution... The percentage concentration is 13%; the multifunctional additive is silane coupling agent KH560; the mass ratio of graphene, ethanol aqueous solution, and multifunctional additive is 1:3.5:0.035; the mass ratio of pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell structured methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer is 1:2:9:5:3; the thermoplastic polyester elastomer is TPEE model 8238 manufactured by DuPont; the intrinsic viscosity of the polybutylene terephthalate resin is 1.2 dL / g; the grade of the core-shell structured methyl methacrylate-butadiene-styrene terpolymer is MBS EM-500; the grade of the ethylene-butyl acrylate-glycidyl methacrylate copolymer is... The temperature of the co-extrusion is 230-250℃.

[0047] The thermally conductive filler alumina has an average particle size of 200 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 0.5-2 μm and a diameter of 50 nm; the chopped carbon fibers have an average diameter of 10 μm and a length of 4-5 mm; the boron nitride nanosheets have a sheet diameter of 0.1-0.4 μm; the hyperbranched unsaturated resin is hyperbranched unsaturated resin HyPer U102; the coupling agent is silane coupling agent KH560; the antioxidant is antioxidant 168; the lubricant is zinc stearate; and the aminoethylated acrylic polymer is aminoethylated acrylic polymer HD-105-PMA.

[0048] A method for preparing the thermally conductive and electromagnetically shielded PBT-based composite material includes the following steps: adding each raw material according to its weight proportions into a high-speed mixer and mixing them evenly to obtain a mixture; then, extruding the mixture through a twin-screw extruder; after water cooling, pelletizing to obtain the thermally conductive and electromagnetically shielded PBT-based composite material of the present invention; the specific process parameters of the twin-screw extruder are as follows: the twin-screw extruder is divided into ten temperature zones, zone 1 temperature is 232℃, zone 2 temperature is 232℃, zone 3 temperature is 232℃, zone 4 temperature is 237℃, zone 5 temperature is 237℃, zone 6 temperature is 242℃, zone 7 temperature is 242℃, zone 8 temperature is 247℃, zone 9 temperature is 247℃, and zone 10 temperature is 247℃; the die head temperature is 252℃; and the rotation speed of the twin-screw extruder is 310 rpm.

[0049] Example 3: A thermally conductive and electromagnetically shielding PBT-based composite material, comprising the following raw materials in parts by weight: 100 parts PBT matrix resin, 13 parts toughened graphene thermally conductive masterbatch, 6.5 parts thermally conductive filler alumina, 9 parts carbon nanotubes, 5.5 parts short-cut carbon fibers, 2 parts boron nitride nanosheets, 2 parts hexafluorobisphenol A diacrylate, 3 parts hyperbranched unsaturated resin, 2 parts coupling agent, 0.35 parts antioxidant, 1 part lubricant, 4 parts aminoethylated acrylic polymer, 0.7 parts carbodiimide, and 0.6 parts dicumyl peroxide; wherein the PBT matrix resin is Kanghui New Materials' PBT KH2100.

[0050] The preparation method of the toughened graphene thermally conductive masterbatch includes the following steps: graphene is uniformly dispersed in an ethanol aqueous solution, a multifunctional additive is added, ultrasonication is performed for 35 minutes, and drying is carried out in an oven at 119°C for 3 hours to obtain pretreated graphene; then, the pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell structured methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer are mixed uniformly using a high-speed mixer, and then co-extruded using a twin-screw extruder and granulated to obtain the toughened graphene thermally conductive masterbatch; the graphene is a single-layer graphene with a thickness of 0.8-1.2 nm and a sheet diameter of 0.5-5 μm; the mass of the ethanol aqueous solution... The percentage concentration is 15%; the multifunctional additive is silane coupling agent KH-570; the mass ratio of graphene, ethanol aqueous solution, and multifunctional additive is 1:4:0.04; the mass ratio of pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell structured methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer is 1:2:9:5:3; the thermoplastic polyester elastomer is TPEE model 8238 manufactured by DuPont; the intrinsic viscosity of the polybutylene terephthalate resin is 1.2 dL / g; the grade of the core-shell structured methyl methacrylate-butadiene-styrene terpolymer is MBS EM-500; the grade of the ethylene-butyl acrylate-glycidyl methacrylate copolymer is... The temperature of the co-extrusion is 230-250℃.

[0051] The thermally conductive filler alumina has an average particle size of 250 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 0.5-2 μm and a diameter of 50 nm; the chopped carbon fibers have an average diameter of 10 μm and a length of 4-5 mm; the boron nitride nanosheets have a sheet diameter of 0.1-0.4 μm; the hyperbranched unsaturated resin is hyperbranched unsaturated resin HyPer U102; the coupling agent is silane coupling agent KH-570; the antioxidant is antioxidant 1076; the lubricant is ethylene bis-stearamide; and the aminoethylated acrylic polymer is aminoethylated acrylic polymer HD-105-PMA.

[0052] A method for preparing the thermally conductive and electromagnetically shielded PBT-based composite material includes the following steps: adding each raw material in parts by weight to a high-speed mixer and mixing them evenly to obtain a mixture; then extruding the mixture through a twin-screw extruder; after water cooling, pelletizing to obtain the thermally conductive and electromagnetically shielded PBT-based composite material of the present invention; the specific process parameters of the twin-screw extruder are as follows: the twin-screw extruder is divided into ten temperature zones, zone 1 temperature is 233℃, zone 2 temperature is 233℃, zone 3 temperature is 233℃, zone 4 temperature is 238℃, zone 5 temperature is 238℃, zone 6 temperature is 243℃, zone 7 temperature is 243℃, zone 8 temperature is 248℃, zone 9 temperature is 248℃, and zone 10 temperature is 248℃; the die head temperature is 253℃; and the rotation speed of the twin-screw extruder is 340 rpm.

[0053] Example 4: A thermally conductive and electromagnetically shielding PBT-based composite material, comprising the following raw materials in parts by weight: 100 parts PBT matrix resin, 18 parts toughened graphene thermally conductive masterbatch, 7.5 parts thermally conductive filler alumina, 9.5 parts carbon nanotubes, 7 parts chopped carbon fibers, 2.5 parts boron nitride nanosheets, 2.5 parts hexafluorobisphenol A diacrylate, 3.5 parts hyperbranched unsaturated resin, 2.5 parts coupling agent, 0.4 parts antioxidant, 1.4 parts lubricant, 4.5 parts aminoethylated acrylic polymer, 0.9 parts carbodiimide, and 0.7 parts dicumyl peroxide; wherein the PBT matrix resin is Kanghui New Materials' PBT KH2100.

[0054] The preparation method of the toughened graphene thermally conductive masterbatch includes the following steps: graphene is uniformly dispersed in an ethanol aqueous solution, a multifunctional additive is added, ultrasonication is performed for 38 minutes, and drying is carried out in an oven at 121°C for 3.5 hours to obtain pretreated graphene; then, the pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer are mixed uniformly by a high-speed mixer, and then co-extruded by a twin-screw extruder and granulated to obtain the toughened graphene thermally conductive masterbatch; the graphene is a single-layer graphene with a thickness of 0.8-1.2 nm and a sheet diameter of 0.5-5 μm; the ethanol aqueous solution has a mass percentage concentration of 18%; the multifunctional additive is silicon. The mixture comprises alkyl coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH-570 in a mass ratio of 1:2:2; the mass ratio of graphene, ethanol aqueous solution, and multifunctional additive is 1:4.5:0.045; the mass ratio of pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer is 1:2:9:5:3; the thermoplastic polyester elastomer is TPEE model 8238 manufactured by DuPont; the intrinsic viscosity of the polybutylene terephthalate resin is 1.2 dL / g; the grade of the core-shell methyl methacrylate-butadiene-styrene terpolymer is MBS EM-500; and the grade of the ethylene-butyl acrylate-glycidyl methacrylate copolymer is... The temperature of the co-extrusion is 230-250℃.

[0055] The thermally conductive filler alumina has an average particle size of 350 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 0.5-2 μm and a diameter of 50 nm; the chopped carbon fibers have an average diameter of 10 μm and a length of 4-5 mm; the boron nitride nanosheets have a sheet diameter of 0.1-0.4 μm; the hyperbranched unsaturated resin is hyperbranched unsaturated resin HyPer U102; the coupling agent is a mixture of silane coupling agents KH550, KH560, and KH-570 in a mass ratio of 2:3:5; the antioxidant is a mixture of antioxidant 1010, 168, and 1076 in a mass ratio of 1:1:1; the lubricant is a mixture of calcium stearate, zinc stearate, and ethylene bis-stearamide in a mass ratio of 2:3:4; and the aminoethylated acrylic polymer is aminoethylated acrylic polymer HD-105-PMA.

[0056] A method for preparing the thermally conductive and electromagnetically shielded PBT-based composite material includes the following steps: adding each raw material in parts by weight to a high-speed mixer and mixing them evenly to obtain a mixture; then extruding the mixture through a twin-screw extruder; after water cooling, pelletizing to obtain the thermally conductive and electromagnetically shielded PBT-based composite material of the present invention; the specific process parameters of the twin-screw extruder are as follows: the twin-screw extruder is divided into ten temperature zones, zone 1 temperature is 234℃, zone 2 temperature is 234℃, zone 3 temperature is 234℃, zone 4 temperature is 239℃, zone 5 temperature is 239℃, zone 6 temperature is 244℃, zone 7 temperature is 244℃, zone 8 temperature is 249℃, zone 9 temperature is 249℃, and zone 10 temperature is 249℃; the die head temperature is 254℃; and the rotation speed of the twin-screw extruder is 370 rpm.

[0057] Example 5: A thermally conductive and electromagnetically shielding PBT-based composite material, comprising the following raw materials in parts by weight: 100 parts PBT matrix resin, 20 parts toughened graphene thermally conductive masterbatch, 8 parts thermally conductive filler alumina, 10 parts carbon nanotubes, 8 parts chopped carbon fibers, 3 parts boron nitride nanosheets, 3 parts hexafluorobisphenol A diacrylate, 4 parts hyperbranched unsaturated resin, 3 parts coupling agent, 0.5 parts antioxidant, 1.5 parts lubricant, 5 parts aminoethylated acrylic polymer, 1 part carbodiimide, and 0.8 parts dicumyl peroxide; wherein the PBT matrix resin is Kanghui New Materials' PBT KH2100.

[0058] The preparation method of the toughened graphene thermally conductive masterbatch includes the following steps: graphene is uniformly dispersed in an ethanol aqueous solution, a multifunctional additive is added, ultrasonication is performed for 40 minutes, and drying is carried out in an oven at 123°C for 4 hours to obtain pretreated graphene; then, the pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell structured methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer are mixed uniformly by a high-speed mixer, and then co-extruded by a twin-screw extruder and granulated to obtain the toughened graphene thermally conductive masterbatch; the graphene is a single-layer graphene with a thickness of 0.8-1.2 nm and a sheet diameter of 0.5-5 μm; the mass of the ethanol aqueous solution is... The concentration is 20%; the multifunctional additive is silane coupling agent KH550; the mass ratio of graphene, ethanol aqueous solution, and multifunctional additive is 1:5:0.05; the mass ratio of pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell structured methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer is 1:2:9:5:3; the thermoplastic polyester elastomer is TPEE model 8238 manufactured by DuPont; the intrinsic viscosity of the polybutylene terephthalate resin is 1.2 dL / g; the grade of the core-shell structured methyl methacrylate-butadiene-styrene terpolymer is MBS EM-500; the grade of the ethylene-butyl acrylate-glycidyl methacrylate copolymer is... The temperature of the co-extrusion is 230-250℃.

[0059] The thermally conductive filler alumina has an average particle size of 400 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 0.5-2 μm and a diameter of 50 nm; the chopped carbon fibers have an average diameter of 10 μm and a length of 4-5 mm; the boron nitride nanosheets have a sheet diameter of 0.1-0.4 μm; the hyperbranched unsaturated resin is hyperbranched unsaturated resin HyPer U102; the coupling agent is silane coupling agent KH550; the antioxidant is antioxidant 1076; the lubricant is zinc stearate; and the aminoethylated acrylic polymer is aminoethylated acrylic polymer HD-105-PMA.

[0060] A method for preparing the thermally conductive and electromagnetically shielded PBT-based composite material includes the following steps: adding each raw material according to its weight proportions into a high-speed mixer and mixing them evenly to obtain a mixture; then, extruding the mixture through a twin-screw extruder; after water cooling, pelletizing to obtain the thermally conductive and electromagnetically shielded PBT-based composite material of the present invention; the specific process parameters of the twin-screw extruder are as follows: the twin-screw extruder is divided into ten temperature zones, zone 1 temperature is 235℃, zone 2 temperature is 235℃, zone 3 temperature is 235℃, zone 4 temperature is 240℃, zone 5 temperature is 240℃, zone 6 temperature is 245℃, zone 7 temperature is 245℃, zone 8 temperature is 250℃, zone 9 temperature is 250℃, and zone 10 temperature is 250℃; the die head temperature is 255℃; and the rotation speed of the twin-screw extruder is 380 rpm.

[0061] Comparative Example 1: This example provides a thermally conductive electromagnetic shielding PBT-based composite material and its preparation method, which is basically the same as Example 1. The difference is that an equal amount of graphene is used to replace the toughened graphene thermally conductive masterbatch, and an equal amount of thermally conductive filler alumina is used to replace boron nitride nanosheets.

[0062] Comparative Example 2: This example provides a thermally conductive and electromagnetically shielding PBT-based composite material and its preparation method, which is basically the same as Example 1, except that an equal amount of PBT matrix resin is used to replace hexafluorobisphenol A diacrylate and hyperbranched unsaturated resin.

[0063] To further illustrate the beneficial technical effects of the thermally conductive and electromagnetically shielding PBT-based composite materials involved in the various embodiments of the present invention, relevant performance tests were conducted on each product. The test results are shown in Table 1, and the test methods are as follows:

[0064] (1) Thermal conductivity test: The thermal conductivity was tested using a TPS2500S thermal conductivity meter. The test standard was ISO 22007-2:2022. The test sample had dimensions of length × width × height = 4 × 4 × 3 mm. 3 The square sheet has a thermal conductivity measured in W / (m·K).

[0065] (2) Tensile properties: Tested according to ISO 527-2-2012, with a sample size of 150mm×10mm×4mm and a tensile speed of 5mm / min.

[0066] (3) Bending performance: Tested according to ISO 178:2019E, with a sample size of 80mm×10mm×4mm, a test speed of 2mm / min, and a span of 64mm.

[0067] (4) Impact strength of simply supported beam: Tested according to ISO 179-1-2023.

[0068] (5) Resistance to damp heat aging: Each product was placed in an environment of 85°C and 85% relative humidity for 1000 hours. After cooling to room temperature, the tensile strength of the aged products was tested again, and the retention rate of tensile strength was calculated. The larger the value, the better the resistance to damp heat aging. The test method for tensile strength is the same as that for (2) tensile properties.

[0069] (6) Electromagnetic shielding effectiveness: The electromagnetic shielding effectiveness of the sample was tested using a vector network analyzer. The waveguide method was used to measure the electromagnetic shielding effectiveness in the X-band between 8.2-12.4 GHz. The sample size was 23×10×4 mm. 3 .

[0070]

[0071] As can be seen from Table 1, the thermally conductive and electromagnetically shielding PBT-based composite materials disclosed in the embodiments of the present invention have superior mechanical properties and impact toughness compared with the comparative examples, and have better resistance to damp heat aging, thermal conductivity and electromagnetic shielding effectiveness. The combined use of toughened graphene thermally conductive masterbatch, boron nitride nanosheets, hexafluorobisphenol A diacrylate and hyperbranched unsaturated resin is beneficial to improving the above properties.

[0072] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A thermally conductive and electromagnetically shielding PBT-based composite material, characterized in that, It is made from the following raw materials in parts by weight: 100 parts PBT matrix resin, 5-20 parts toughened graphene thermally conductive masterbatch, 5-8 parts thermally conductive filler alumina, 8-10 parts carbon nanotubes, 3-8 parts short-cut carbon fibers, 1-3 parts boron nitride nanosheets, 1-3 parts hexafluorobisphenol A diacrylate, 2-4 parts hyperbranched unsaturated resin, 1-3 parts coupling agent, 0.1-0.5 parts antioxidant, 0.5-1.5 parts lubricant, 3-5 parts aminoethylated acrylic polymer, 0.3-1 part carbodiimide, and 0.3-0.8 parts dicumyl peroxide; The preparation method of the toughened graphene thermally conductive masterbatch includes the following steps: uniformly dispersing graphene in an ethanol aqueous solution, adding a multifunctional additive, ultrasonicating for 30-40 minutes, and drying in an oven at 115-123℃ for 2-4 hours to obtain pretreated graphene; then, uniformly mixing the pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell structured methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer using a high-speed mixer, followed by co-extrusion using a twin-screw extruder, and granulation. Toughened graphene thermally conductive masterbatch was obtained; the multifunctional additive was at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH-570; the mass ratio of graphene, ethanol aqueous solution, and multifunctional additive was 1:(3-5):(0.03-0.05); the mass ratio of pretreated graphene, polybutylene terephthalate resin, thermoplastic polyester elastomer, core-shell structured methyl methacrylate-butadiene-styrene terpolymer, and ethylene-butyl acrylate-glycidyl methacrylate copolymer was 1:2:9:5:

3.

2. The thermally conductive and electromagnetically shielding PBT-based composite material according to claim 1, characterized in that, The intrinsic viscosity of the PBT matrix resin is 0.8-1.2 dL / g.

3. The thermally conductive and electromagnetically shielding PBT-based composite material according to claim 1, characterized in that, The graphene is a single-layer graphene with a thickness of 0.8-1.2 nm and a sheet diameter of 0.5-5 μm; the ethanol aqueous solution has a mass percentage concentration of 10-20%.

4. The thermally conductive and electromagnetically shielding PBT-based composite material according to claim 1, characterized in that, The thermoplastic polyester elastomer is TPEE of type 8238; the intrinsic viscosity of the polybutylene terephthalate resin is 1.2 dL / g; the core-shell methyl methacrylate-butadiene-styrene terpolymer is MBS EM-500; the ethylene-butyl acrylate-glycidyl methacrylate copolymer is Elvaloy® PTW; and the co-extrusion temperature is 230-250℃.

5. The thermally conductive and electromagnetically shielding PBT-based composite material according to claim 1, characterized in that, The thermally conductive filler alumina has an average particle size of 100-400 nm; the carbon nanotubes are multi-walled carbon nanotubes with a length of 0.5-2 μm and a diameter of 50 nm; the chopped carbon fibers have an average diameter of 10 μm and a length of 4-5 mm; the boron nitride nanosheets have a sheet diameter of 0.1-0.4 μm; the hyperbranched unsaturated resin is hyperbranched unsaturated resin HyPer U102; the coupling agent is at least one of silane coupling agents KH550, KH560, and KH-570; the antioxidant is at least one of antioxidant 1010, 168, and 1076; the lubricant is one or more of calcium stearate, zinc stearate, and ethylene bis-stearamide; and the aminoethylated acrylic polymer is aminoethylated acrylic polymer HD-105-PMA.

6. A method for preparing a thermally conductive and electromagnetically shielding PBT-based composite material according to any one of claims 1-5, characterized in that, The process includes the following steps: adding each raw material according to its weight into a high-speed mixer and mixing them evenly to obtain a mixture; then extruding the mixture through a twin-screw extruder; and finally, after water cooling, pelletizing to obtain a thermally conductive and electromagnetically shielded PBT-based composite material.

7. The method for preparing the thermally conductive and electromagnetically shielded PBT-based composite material according to claim 6, characterized in that, The specific process parameters for the co-extrusion of the twin-screw extruder are as follows: the twin-screw extruder is divided into ten temperature zones, with zone 1 at 230-235℃, zone 2 at 230-235℃, zone 3 at 230-235℃, zone 4 at 235-240℃, zone 5 at 235-240℃, zone 6 at 240-245℃, zone 7 at 240-245℃, zone 8 at 245-250℃, zone 9 at 245-250℃, and zone 10 at 245-250℃; the die head temperature is 250-255℃; and the rotational speed of the twin-screw extruder is 290-380 rpm.

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