A sprayable conductive ppe / pa material

Abstract

The application belongs to the technical field of polymer composites, and particularly relates to a sprayable conductive PPE / PA material, which is composed of polyphenylene ether, polyamide, styrene-maleic anhydride copolymer, silane functionalized zinc tin oxide nanowire, boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheet, antioxidant and ethylene bis-stearamide. The application first prepares zinc metatitanate nanowire through a hydrothermal-calcination method, and obtains silane functionalized zinc tin oxide nanowire through surface functionalization of aminopropyl triethoxysilane. Meanwhile, the boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheet is prepared through a hydrothermal co-doping-in-situ reduction method. The modified compounds are melt blended, extruded and granulated together with polyphenylene ether, polyamide, a compatibilizer and the like, and then a coating is obtained through melt spraying and solidification. The application adopts nanowire and nanosheet to synergistically enhance the conductive network, and the filler is firmly combined with the matrix interface, so that the obtained material has good conductivity and excellent sprayability.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to a sprayable conductive PPE / PA material. Background Technology

[0002] Polyphenylene ether (PPE) is an engineering plastic with excellent heat resistance, dimensional stability, and dielectric properties, and is widely used in electronics, automotive, and other industries. However, PPE's high melt viscosity, poor processing fluidity, and insufficient solvent resistance and stress cracking resistance limit its application in complex structural parts and thin-walled products. Polyamide 66, on the other hand, possesses excellent processing fluidity, oil resistance, abrasion resistance, and mechanical strength, but it suffers from high hygroscopicity, poor low-temperature toughness, and insufficient dimensional stability. Melt blending PPE and polyamide 66 to prepare alloy materials can achieve complementary properties while retaining the advantages of both, resulting in engineering plastics with balanced overall performance. However, PPE and polyamide 66 are typical incompatible polymer systems, exhibiting high interfacial tension and poor compatibility. Direct blending leads to severe phase separation, forming rough phase morphology and weak interfacial bonding, thus significantly deteriorating the material's mechanical properties. Therefore, compatibilizers, such as styrene-maleic anhydride copolymers, must be added to the blend system. The maleic anhydride groups can react with the terminal amino groups of polyamide 66, while the styrene segments have good compatibility with polyphenylene ether, thus playing a "compensating bridging" role at the interface between the two phases and effectively improving the phase morphology and interfacial bonding strength.

[0003] In applications such as electrostatic spraying of automotive exterior parts, antistatic coating of electronic device housings, and plastic parts for flammable and explosive environments, polyphenylene ether / polyamide 66 alloy materials are required to possess good surface conductivity to eliminate static electricity accumulation and avoid safety hazards caused by electrostatic discharge. Traditional methods to improve the conductivity of polymer materials involve adding conductive fillers, such as carbon black, carbon nanotubes, and graphene, to the matrix, forming a conductive network through the contact between the fillers. However, existing conductive polyphenylene ether / polyamide 66 composite materials still face three major technical bottlenecks. First, conductive fillers, especially carbon nanotubes and graphene, are prone to agglomeration in the polymer matrix, leading to discontinuous conductive pathways and large batch-to-batch fluctuations in conductivity. Achieving low resistivity often requires high filler dosages, which not only increases costs but also degrades the material's mechanical properties and processing flowability. Second, the interfacial compatibility between inorganic conductive fillers and the organic polymer matrix is ​​poor, with numerous defects and voids at the filler-matrix interface. This limits conductivity and weakens mechanical properties; the lack of effective chemical bonding between the filler and the matrix prevents effective stress transfer. Third, the sprayability is poor. Traditional conductive composite materials have high viscosity in the molten state, resulting in poor leveling properties when used for spraying, making it difficult to obtain a coating with uniform thickness and a smooth surface. Furthermore, the adhesion between the coating and the substrate is insufficient. Therefore, developing a polyphenylene ether / polyamide composite material that combines high conductivity, good mechanical properties, and excellent sprayability has significant industrial value. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a sprayable conductive PPE / PA material comprising the following components in parts by weight: 30-60 parts of polyphenylene ether, 30-60 parts of polyamide 66, 5-15 parts of styrene-maleic anhydride copolymer, 0.5-5 parts of silane-functionalized zinc tin oxide nanowires, 0.5-5 parts of boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets, 0.1-1.0 parts of antioxidant 1010, and 0.2-2 parts of ethylene bis-stearamide.

[0005] According to a preferred embodiment of the present invention, the preparation steps of the sprayable conductive PPE / PA material include: S1. Silane-functionalized zinc tin oxide nanowires and boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets are ultrasonically dispersed in anhydrous ethanol to obtain a dispersion. The dispersion is then rotary evaporated in a rotary evaporator at 58-62℃ to collect the mixed powder. The mixed powder is dried in a vacuum drying oven at 78-82℃ to obtain a dried mixed powder. Polyphenylene ether is dried in a forced-air drying oven at 98-102℃ to obtain dried polyphenylene ether. Polyamide 66 is dried in a vacuum drying oven at 78-82℃ to obtain dried polyamide 66. Styrene-maleic anhydride copolymer is dried in a drying oven at 78-82℃ to obtain dried styrene-maleic anhydride copolymer. The dried polyphenylene ether, polyamide 66, styrene-maleic anhydride copolymer, mixed powder, antioxidant 1010, and ethylene bis-stearamide are premixed in a mixer to obtain a premix. S2. The premixed material is fed into a twin-screw extruder for melt blending and extrusion to obtain an extruded molten strip. The extruded molten strip is cooled in a water tank and then fed into a pelletizer for granulation to obtain granules. The granules are dried in a vacuum drying oven at 78-82℃ to obtain dried granules. The dried granules are added to a melt spraying extruder to obtain molten material. The molten material is atomized and sprayed onto the surface of the substrate through a spraying die. After spraying, it is cured in an oven at 118-122℃.

[0006] In this invention, the preparation of the sprayable conductive PPE / PA material focuses on the interfacial compatibilization and spatiotemporal construction of a synergistic conductive network in a multiphase system. Polyphenylene ether (PPE) and polyamide 66 are thermodynamically incompatible systems, and direct blending easily leads to severe phase separation. The styrene-maleic anhydride copolymer introduced into the system acts as a key surfactant, playing a chemical bridging role under the strong shear field and high-temperature melting environment of twin-screw extrusion: the maleic anhydride groups spontaneously form graft products with the terminal amino groups of polyamide 66 through a ring-opening reaction. The styrene segments of this product are physically compatible with the PPE segments through intermolecular forces, thereby forming a dense compatibilizing layer at the two-phase interface, significantly reducing interfacial tension and refining the dispersed phase size. Simultaneously, the amino groups on the surface of silane-functionalized nanowires also participate in the maleic anhydride ring-opening reaction, chemically grafting the inorganic nanowires onto the polymer phase interface or matrix. Regarding the conductivity mechanism, this invention fully leverages the "bridging" effect of one-dimensional nanowires and the "planar transport" advantages of two-dimensional nanosheets. During melt spraying, the temperature of the melt rapidly decreases upon contact with the substrate after being atomized from the die. High aspect ratio zinc stannate nanowires interweave between graphene nanosheets, connecting spatially isolated conductive planes to form a three-dimensional hierarchical conductive network that integrates "grid and wires." This synergistic structure allows electrons to freely transition between multidimensional paths as they pass through the material's interior via tunneling or direct contact, significantly improving macroscopic conductivity. Finally, at an appropriate curing temperature, polymer segments rearrange and lock onto the substrate surface, forming a functional protective coating that combines excellent conductivity, good mechanical strength, and strong interfacial adhesion.

[0007] According to a preferred embodiment of the present invention, in step S1, the ultrasonic dispersion time is 30-60 min.

[0008] According to a preferred embodiment of the present invention, in step S2, the temperature of the melt spray extruder is set to 260-280°C.

[0009] According to a preferred embodiment of the present invention, the preparation method of the silane-functionalized zinc tin oxide nanowires includes: A1, dissolving 5-8 parts by weight of zinc nitrate hexahydrate and 7-10 parts by weight of tin tetrachloride pentahydrate in 100-150 parts by weight of deionized water, stirring at room temperature to obtain a precursor solution; adding 10-20 parts by weight of ammonia water dropwise to the precursor solution to adjust the pH to 8.8-9.2, and continuing to stir to obtain a suspension; transferring the suspension to a reaction vessel, hydrothermally reacting at 178-182°C, and naturally cooling to room temperature to obtain a reaction mixture; centrifuging the reaction mixture to obtain a precipitate; washing the precipitate with deionized water and anhydrous ethanol, and then... The zinc tin oxide nanowire precursor was obtained by drying in a vacuum drying oven at -82℃. The zinc tin oxide nanowire precursor was then placed in a tube furnace and calcined at 395-405℃ under a nitrogen atmosphere to obtain zinc metastannate nanowires. A2. 1-2 parts of γ-aminopropyltriethoxysilane were dissolved in a mixed solvent of 40-60 parts anhydrous ethanol and 5-10 parts deionized water, and stirred at room temperature to obtain a hydrolysate. 1-1.5 parts of zinc metastannate nanowires were added to the hydrolysate, and the reaction was continued in a water bath at 58-62℃ to obtain a reaction mixture. The reaction mixture was centrifuged to obtain a precipitate. The precipitate was washed with anhydrous ethanol and dried in a vacuum drying oven at 58-62℃.

[0010] In this invention, the preparation of the silane-functionalized zinc-tin oxide nanowires begins with the controlled co-precipitation and crystal phase evolution of the precursor. In a liquid system, zinc and tin source metal cations are uniformly dispersed at the molecular level in deionized water. Ammonia is added dropwise to the system, and hydroxide ions induce the metal ions to undergo hydrolysis and condensation, forming an amorphous zinc-tin hydroxide colloid. By precisely adjusting the hydrogen ion concentration index to a weakly alkaline range, a suitable environment is created for subsequent directional crystal growth. Subsequently, under high temperature and high pressure hydrothermal conditions, the subcritical water environment in the reactor drives the precursor to oriented and stack along a specific crystal axis, forming a one-dimensional nanowire morphology with a high aspect ratio. After washing and drying, the hydrothermal product is calcined under nitrogen protection at a temperature appropriately below the phase transition critical point, causing the precursor to undergo dehydroxylation and lattice rearrangement, transforming from a metastable state into a well-crystallized zinc stannate perovskite structure. To impart organic affinity to the nanowires, an aminosilane coupling agent was introduced for surface modification: the alkoxy groups of the silane molecules hydrolyze in an alcohol-water medium to generate active silanols, which are adsorbed onto the hydroxyl groups on the nanowire surface via hydrogen bonding, and then undergo dehydration condensation under heating to form strong oxygen-silicon bonds. This modification covalently grafts reactive primary amine groups onto the inorganic surface, reducing surface energy, preventing aggregation, and providing sites for subsequent chemical bonding with the resin matrix.

[0011] According to a preferred embodiment of the present invention, in step A1, the hydrothermal reaction time at 178-182°C is 24-30 hours.

[0012] According to a preferred embodiment of the present invention, in step A2, the reaction time in a water bath at 58-62°C is 6-8 hours.

[0013] According to a preferred embodiment of the present invention, the preparation method of the boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets includes: B1, dispersing 1-2 parts by weight of graphene oxide in 200-250 parts by weight of deionized water, ultrasonically dispersing to obtain a graphene oxide dispersion; adding 0.5-1 parts by weight of boric acid and 1-2 parts by weight of urea to the graphene oxide dispersion, stirring at room temperature to obtain a mixture; transferring the mixture to a reaction vessel, hydrothermally reacting at 178-182°C, and naturally cooling to obtain a reaction solution; adding a mixture containing 0.3-0.5 parts by weight of silver nitrate and 10-15 parts by weight of deionized water to the reaction solution, stirring at room temperature; then adding 0.5-1 parts by weight of ascorbic acid, stirring at 58-62°C to obtain a reaction mixture; B2, centrifuging the reaction mixture to collect the precipitate; washing the precipitate with deionized water and anhydrous ethanol, and drying it in a vacuum drying oven at 58-62°C.

[0014] In this invention, the preparation of boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets involves the synergistic effect of lattice atom substitution and in-situ redox. In the hydrothermal stage, graphene oxide serves as the carbon-based template, with urea and boric acid acting as the nitrogen and boron sources, respectively. Under high temperature and pressure, nitrogen-containing intermediates generated from urea pyrolysis and boric acid molecules attack graphene defect sites or oxygen-containing functional group positions through nucleophilic reactions, covalently embedding nitrogen and boron atoms into the hexagonal honeycomb lattice of carbon. The boron-nitrogen dual doping breaks the symmetry of the original charge distribution of graphene, modulates the band structure, and significantly improves the electron mobility within the sheet. Simultaneously, the reducing properties of the hydrothermal environment promote the removal of a large number of insulating oxygen-containing groups on the surface of graphene oxide, restoring the conjugated structure and achieving the transformation into doped reduced graphene oxide. In the silver hybridization stage, the local charge inhomogeneity generated by the doping sites is utilized to electrically capture and coordinately anchor silver ions in the solution, allowing silver ions to pre-occupy the active sites of the sheet. The subsequent addition of a mild organic reducing agent reduces the adsorbed silver ions in situ to metallic silver nanoparticles, which then grow uniformly on the surface of the graphene sheets, forming a point-to-surface contact interface. This structure utilizes the high conductivity of silver particles to compensate for the physical contact resistance between the sheets, and the three-dimensional distribution of silver particles greatly enhances the effective conductive radius of the nanosheets in the composite material.

[0015] According to a preferred embodiment of the present invention, in step B1, the hydrothermal reaction time at 178-182°C is 12-14 hours.

[0016] According to a preferred embodiment of the present invention, in step B2, the drying time in a vacuum drying oven at 58-62°C is 24-30 hours.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention achieves a synergistic improvement in the conductivity and sprayability of polyphenylene ether / polyamide 66 composite materials by designing two novel inorganic modified compounds: silane-functionalized zinc tin oxide nanowires and boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets. The one-dimensional nanowires and two-dimensional nanosheets are geometrically complementary in morphology and form a three-dimensional conductive network in terms of conductivity mechanism, which can significantly reduce the conductivity percolation threshold, enabling the material to obtain excellent conductivity with low filler content, meeting the application requirements in the fields of automotive electrostatic spraying and electronic antistatic spraying.

[0018] (2) This invention improves the interfacial compatibility between inorganic fillers and the polymer matrix through a surface chemical bonding strategy. The amino groups on the surface of silane-functionalized zinc tin oxide nanowires can undergo ring-opening imidization reactions with the maleic anhydride groups in the compatibilizer to form covalent bonds; the oxygen-containing functional groups on the surface of boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets can also undergo hydrogen bonding or chemical reactions with the end groups of polyamide 66. This interfacial bonding effectively inhibits filler agglomeration, improves dispersion uniformity, and enables the composite material to maintain good conductivity while possessing excellent mechanical properties. The introduction of the compatibilizer further reduces the interfacial tension between the polyphenylene ether and polyamide 66 phases, forming a stable phase morphology.

[0019] (3) The material of this invention has excellent melt flowability and spray coating adaptability. The low filler content combined with the addition of lubricant results in a moderate melt viscosity, which can be smoothly atomized in the melt spraying equipment to form uniform and fine droplets. After spraying, the leveling property is good, and the coating is smooth and dense. This solvent-free hot melt spraying process is environmentally friendly and efficient, requires no secondary coating, greatly simplifies the production process, and reduces costs. This invention has excellent comprehensive performance and broad industrial application prospects. Detailed Implementation

[0020] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0021] Example 1 This embodiment provides a method for preparing a sprayable conductive PPE / PA material, the steps of which include: Step S1: Weigh 2.75g of silane-functionalized zinc tin oxide nanowires and 2.75g of boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets, and add them together to a round-bottom flask. Add 75g of anhydrous ethanol and ultrasonically disperse in an ultrasonic cleaner for 45min at an ultrasonic power of 200W and a frequency of 40kHz to obtain a uniform black dispersion. Mount the round-bottom flask on a rotary evaporator, set the water bath temperature to 60℃, the vacuum degree to -0.08MPa, and the rotation speed to 60rpm, and remove the anhydrous ethanol by rotary evaporation. After about 40min, a dry mixed powder is obtained. Transfer the mixed powder to a petri dish and place it in an 80℃ vacuum drying oven at a vacuum degree of -0.09MPa for 12h to obtain a dried mixed modified compound powder. In addition, 45g of polyphenylene oxide (PPE) powder was spread evenly in a stainless steel tray and dried in a 100℃ forced-air drying oven for 4 hours; 45g of polyamide 66 (PA66) granules were dried in a vacuum drying oven at 80℃ with a vacuum degree of -0.09MPa for 12 hours; and 10g of styrene-maleic anhydride copolymer (SMA) with a maleic anhydride content of 25wt% was dried in a 80℃ forced-air drying oven for 4 hours. After drying, all the above dried materials, including PPE, PA66, SMA, mixed modified compound powder, 0.55g of antioxidant 1010, and 1.1g of ethylene bis-stearamide (EBS), were added to a high-speed mixer, covered, and premixed at 500rpm for 10 minutes to obtain a uniform premix.

[0022] Step S2: The premixed material is fed into the feed port of a co-rotating twin-screw extruder via a loss-in-weight feeder. The twin-screw extruder has a screw diameter of 35 mm and a length-to-diameter ratio of 40:1. The extruder temperatures are set as follows: feeding section 240℃, melting section 270℃, mixing section 280℃, venting section 275℃, metering section 270℃; screw speed 300 rpm; and feed rate 5 kg / h. After melting and blending in the extruder, the material is extruded from the die into molten strips approximately 3 mm in diameter. The strips are cooled in a 5 m long water tank at 25℃, air-dried, and then fed into a pelletizer to be cut into cylindrical pellets approximately 3 mm in length. The pellets are collected and dried in an 80℃ vacuum drying oven at a vacuum degree of -0.09 MPa for 12 hours. The dried granules were added to the hopper of a single-screw melt spray extruder with a screw diameter of 20 mm and a length-to-diameter ratio of 25:1. The extruder temperature was set to 270℃ and the screw speed to 50 rpm. The molten material was extruded through a slit die with a slit width of 0.5 mm and a length of 30 mm. Compressed air was simultaneously introduced through the die to atomize the melt into tiny droplets at a pressure of 0.65 MPa. The atomized droplets were sprayed onto the surface of an aluminum substrate that had been pre-cleaned with acetone and preheated to 60℃. The spraying distance was 20 cm, the die moving speed was 5 cm / s, and the spraying was repeated three times to achieve a coating thickness of 125 μm, which was measured using an eddy current thickness gauge. After spraying, the coated substrate was placed in a 120℃ forced-air oven for 30 minutes to cure, and then allowed to cool naturally to room temperature to obtain a sprayable conductive PPE / PA material coating.

[0023] Preparation of silane-functionalized zinc tin oxide nanowires: Step A1: Add 6.5g of zinc nitrate hexahydrate and 8.5g of tin tetrachloride pentahydrate to a beaker, add 125g of deionized water, place on a magnetic stirrer, and stir at 400 rpm for 30 min at room temperature (25℃) until the solid is completely dissolved, obtaining a clear and transparent precursor solution. Using a dropping funnel, add 15g of ammonia water (25% by mass) dropwise to the precursor solution at a rate of 2 mL / min, while stirring at 300 rpm. Monitor the pH of the solution with a pH meter; stop adding the ammonia water when the pH reaches 9.0, and continue stirring for 2 h. A white precipitate suspension gradually forms. Transfer the suspension to a 200mL stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), filling it to 75%. Seal the reactor and place it in a drying oven at 180℃ for hydrothermal reaction for 27 h. After the reaction, allow it to cool naturally to room temperature for approximately 6 h. Open the reaction vessel and transfer the reaction mixture to a centrifuge tube. Centrifuge at 8000 rpm for 15 min using a benchtop high-speed centrifuge (relative centrifugal force approximately 6000 × g). Discard the supernatant and collect the precipitate. Add 50 mL of deionized water to the precipitate, stir with a glass rod to disperse, and centrifuge again. Repeat this process three times. Wash the precipitate three times with 50 mL of anhydrous ethanol. Transfer the washed precipitate to a petri dish and place it in a vacuum drying oven at 80 °C and -0.09 MPa for 12 h to obtain a white powdery zinc tin oxide nanowire precursor. Spread the precursor evenly in a corundum boat and place it in the quartz tube of a tube furnace. Purge with nitrogen gas (99.999% purity) at a flow rate of 100 mL / min for 30 min to replace the air. Then, raise the furnace temperature to 400 °C at a rate of 5 °C / min and calcine for 4 h. Afterward, allow it to cool naturally to room temperature and remove the product to obtain grayish-white zinc metastannate nanowires.

[0024] Step A2: In a 100 mL round-bottom flask, dissolve 1.5 g of γ-aminopropyltriethoxysilane in a mixed solvent of 50 g anhydrous ethanol and 7.5 g deionized water. Add a magnetic stir bar and stir at 300 rpm for 30 min at room temperature to fully hydrolyze the γ-aminopropyltriethoxysilane, obtaining a clear hydrolysate. Add 1.25 g of the above-mentioned zinc stannate nanowires to the hydrolysate, seal the flask, and place it in a constant temperature water bath. Refluxing at 200 rpm for 7 h at 60 °C. After the reaction is complete, transfer the reaction mixture to a centrifuge tube and centrifuge at 8000 rpm for 15 min. Discard the supernatant and collect the precipitate. Add 40 mL of anhydrous ethanol to the precipitate, sonicate for 5 min at 150 W, and then centrifuge again. Repeat this process three times to remove unreacted silane coupling agent. Finally, the precipitate was transferred to a vacuum drying oven and dried at 60°C and a vacuum of -0.09 MPa for 12 hours to obtain silane-functionalized zinc tin oxide nanowires, which were then sealed and stored for later use.

[0025] Preparation of boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets: Step B1: In a 500mL beaker, disperse 1.5g of graphene oxide in 225g of deionized water. Use an ultrasonic cell disruptor in an ice-water bath for 1 hour (probe diameter 12mm, power 200W, 2s operation, 3s interval) to obtain a uniform brownish-red graphene oxide dispersion. Add 0.75g of boric acid and 1.5g of urea to the dispersion and stir magnetically at 400rpm for 30 minutes at room temperature to obtain a mixture. Transfer the mixture to a 300mL stainless steel high-pressure reactor lined with polytetrafluoroethylene (PTFE), filling to 80%. Seal the reactor and place it in a forced-air drying oven for hydrothermal reaction at 180℃ for 13 hours. After the reaction, allow it to cool naturally to room temperature. Open the reactor to obtain a black reaction solution. Slowly add approximately 0.8g of 1mol / L dilute nitric acid (measured with a pH meter) to the reaction solution, adjusting the pH to 6.8. Then, a pre-prepared mixture containing 0.4 g silver nitrate and 12.5 g deionized water was added dropwise with stirring at a rate of 1 mL / min, and the mixture was stirred at room temperature for 30 min. Subsequently, 0.75 g ascorbic acid (vitamin C) was added, and the reaction was continued to be stirred in a 60 °C water bath for 2 h to obtain the reaction mixture.

[0026] Step B2: Transfer the above reaction mixture to a centrifuge tube and centrifuge at 8000 rpm for 15 min. Discard the supernatant and collect the precipitate. Wash the precipitate sequentially with 50 mL of deionized water and 50 mL of anhydrous ethanol, centrifuging at 8000 rpm for 10 min after each wash, washing three times with deionized water and twice with anhydrous ethanol. Finally, dry the precipitate in a vacuum drying oven at 60℃ and -0.09 MPa for 27 h to obtain black, fluffy powdery boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets, which are then sealed and stored for later use.

[0027] Example 2 The difference between this embodiment and Embodiment 1 is that this embodiment provides a method for preparing a sprayable conductive PPE / PA material, the steps of which include: Step S1: 0.5g of silane-functionalized zinc tin oxide nanowires and 0.5g of boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets were ultrasonically dispersed in 50g of anhydrous ethanol for 30min to obtain a dispersion; the dispersion was rotary evaporated in a rotary evaporator at 58℃ to collect the mixed powder; the mixed powder was dried in a vacuum drying oven at 78℃ for 12h to obtain the dried mixed powder; 30g of polyphenylene ether was dried in a forced-air drying oven at 98℃ for 4h to obtain the dried polyphenylene ether; 30g of polyamide... Polyamide 66 was dried in a vacuum drying oven at 78°C for 12 hours to obtain dried polyamide 66; 5g of styrene-maleic anhydride copolymer was dried in a drying oven at 78°C for 4 hours to obtain dried styrene-maleic anhydride copolymer; the dried polyphenylene ether, polyamide 66, styrene-maleic anhydride copolymer, the above-mentioned dried mixed powder, 0.1g of antioxidant 1010 and 0.2g of ethylene bis-stearamide were premixed in a high-speed mixer at 500rpm for 10min to obtain a premix.

[0028] Step S2: The premixed material is fed into a co-rotating twin-screw extruder for melt blending and extrusion. The temperatures of each section of the extruder are set as follows: feeding section 240℃, melting section 270℃, mixing section 280℃, venting section 275℃, metering section 270℃, screw speed 300rpm, and feeding rate 5kg / h. The extruded molten material is cooled in a water bath and then granulated by a pelletizer to obtain granules. The granules are dried in a vacuum drying oven at 78℃ for 12h to obtain dried granules. The dried granules are added to a melt spraying extruder. The temperature of the spraying extruder is set to 260℃. The molten material is atomized by compressed air through a spraying die and sprayed onto the surface of the pretreated substrate. The spraying distance is 15cm, the spraying pressure is 0.5MPa, and the coating thickness is controlled to be 50μm. After spraying, the coating is cured in an oven at 118℃ for 30min to obtain a sprayable conductive PPE / PA material coating.

[0029] Preparation of silane-functionalized zinc tin oxide nanowires: Step A1: Dissolve 5g of zinc nitrate hexahydrate and 7g of tin tetrachloride pentahydrate together in 100g of deionized water and stir at room temperature for 30min to obtain a precursor solution; add 10g of ammonia dropwise to the precursor solution to adjust the pH to 8.8 and continue stirring for 2h to obtain a suspension; transfer the suspension to a reaction vessel and hydrothermally react at 178℃ for 24h, then cool naturally to room temperature to obtain a reaction mixture; centrifuge the reaction mixture to obtain a precipitate; wash the precipitate three times each with deionized water and anhydrous ethanol, and then dry it in a vacuum drying oven at 78℃ for 12h to obtain a zinc tin oxide nanowire precursor; place the zinc tin oxide nanowire precursor in a tube furnace and calcine it at 395℃ for 4h under a nitrogen atmosphere to obtain zinc metastannate nanowires.

[0030] Step A2: Dissolve 1g of γ-aminopropyltriethoxysilane in a mixed solvent of 40g anhydrous ethanol and 5g deionized water, and stir at room temperature for 30min to obtain a hydrolysate; add 1g of zinc stannate nanowires to the hydrolysate, and continue to react in a water bath at 58℃ for 6h to obtain a reaction mixture; centrifuge the reaction mixture to obtain a precipitate; wash the precipitate three times with anhydrous ethanol, and dry it in a vacuum drying oven at 58℃ for 12h to obtain silane-functionalized zinc tin oxide nanowires.

[0031] Preparation of boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets: Step B1: Disperse 1g of graphene oxide in 200g of deionized water and sonicate for 1h at 200W to obtain a graphene oxide dispersion; add 0.5g of boric acid and 1g of urea to the graphene oxide dispersion and stir at room temperature for 30min to obtain a mixture; transfer the mixture to a reaction vessel and hydrothermally react at 178℃ for 12h, then cool naturally to obtain a reaction solution; add a mixture containing 0.3g of silver nitrate and 10g of deionized water to the reaction solution and stir at room temperature for 30min; then add 0.5g of ascorbic acid and stir at 58℃ for 2h to obtain a reaction mixture.

[0032] Step B2: Centrifuge the reaction mixture at 8000 rpm for 15 min and collect the precipitate; wash the precipitate five times each with deionized water and anhydrous ethanol, and dry it in a vacuum drying oven at 58℃ for 24 h to obtain boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets.

[0033] Example 3 The difference between this embodiment and Embodiment 1 is that this embodiment provides a method for preparing a sprayable conductive PPE / PA material, the steps of which include: Step S1: 5g of silane-functionalized zinc tin oxide nanowires and 5g of boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets were ultrasonically dispersed in 100g of anhydrous ethanol for 60min to obtain a dispersion; the dispersion was rotary evaporated in a rotary evaporator at 62℃ to collect the mixed powder; the mixed powder was dried in a vacuum drying oven at 82℃ for 12h to obtain the dried mixed powder; 60g of polyphenylene ether was dried in a forced-air drying oven at 102℃ for 4h to obtain the dried polyphenylene ether; 60g of polyamide Polyamide 66 was dried in a vacuum drying oven at 82℃ for 12 hours to obtain dried polyamide 66; 15g of styrene-maleic anhydride copolymer was dried in a drying oven at 82℃ for 4 hours to obtain dried styrene-maleic anhydride copolymer; the dried polyphenylene ether, polyamide 66, styrene-maleic anhydride copolymer, the above-mentioned dried mixed powder, 1.0g of antioxidant 1010 and 2g of ethylene bis-stearamide were premixed in a high-speed mixer at 500rpm for 10min to obtain a premix.

[0034] Step S2: The premixed material is fed into a co-rotating twin-screw extruder for melt blending and extrusion. The temperatures of each section of the extruder are set as follows: feeding section 240℃, melting section 270℃, mixing section 280℃, venting section 275℃, metering section 270℃, screw speed 300rpm, and feeding rate 5kg / h. The extruded molten material is cooled in a water tank and then granulated by a pelletizer to obtain granules. The granules are dried in a vacuum drying oven at 82℃ for 12h to obtain dried granules. The dried granules are added to a melt spraying extruder. The temperature of the spraying extruder is set to 280℃. The molten material is atomized by compressed air through a spraying die and sprayed onto the surface of the pretreated substrate. The spraying distance is 25cm, the spraying pressure is 0.8MPa, and the coating thickness is controlled to be 200μm. After spraying, the coating is cured in a 122℃ oven for 30min to obtain a sprayable conductive PPE / PA material coating.

[0035] Preparation of silane-functionalized zinc tin oxide nanowires: Step A1: Dissolve 8g of zinc nitrate hexahydrate and 10g of tin tetrachloride pentahydrate in 150g of deionized water and stir at room temperature for 30min to obtain a precursor solution; add 20g of ammonia dropwise to the precursor solution to adjust the pH to 9.2 and continue stirring for 2h to obtain a suspension; transfer the suspension to a reaction vessel and hydrothermally react at 182℃ for 30h, then cool naturally to room temperature to obtain a reaction mixture; centrifuge the reaction mixture to obtain a precipitate; wash the precipitate three times each with deionized water and anhydrous ethanol, and then dry it in a vacuum drying oven at 82℃ for 12h to obtain a zinc tin oxide nanowire precursor; place the zinc tin oxide nanowire precursor in a tube furnace and calcine it at 405℃ for 4h under a nitrogen atmosphere to obtain zinc metastannate nanowires.

[0036] Step A2: Dissolve 2g of γ-aminopropyltriethoxysilane in a mixed solvent of 60g anhydrous ethanol and 10g deionized water, and stir at room temperature for 30min to obtain a hydrolysate; add 1.5g of zinc stannate nanowires to the hydrolysate, and continue to react in a water bath at 62℃ for 8h to obtain a reaction mixture; centrifuge the reaction mixture to obtain a precipitate; wash the precipitate three times with anhydrous ethanol, and dry it in a vacuum drying oven at 62℃ for 12h to obtain silane-functionalized zinc tin oxide nanowires.

[0037] Preparation of boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets: Step B1: Disperse 2g of graphene oxide in 250g of deionized water and sonicate for 1h at 200W to obtain a graphene oxide dispersion; add 1g of boric acid and 2g of urea to the graphene oxide dispersion and stir at room temperature for 30min to obtain a mixture; transfer the mixture to a reaction vessel and hydrothermally react at 182℃ for 14h, then cool naturally to obtain a reaction solution; add a mixture containing 0.5g of silver nitrate and 15g of deionized water to the reaction solution and stir at room temperature for 30min; then add 1g of ascorbic acid and stir at 62℃ for 2h to obtain a reaction mixture.

[0038] Step B2: Centrifuge the reaction mixture at 8000 rpm for 15 min and collect the precipitate; wash the precipitate five times each with deionized water and anhydrous ethanol, and dry it in a vacuum drying oven at 62℃ for 30 h to obtain boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that silane-functionalized zinc tin oxide nanowires and boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets are not added. Otherwise, it is exactly the same as Example 1.

[0040] Comparative Example 2 The difference between this comparative example and Example 1 is that boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets are not added; only silane-functionalized zinc tin oxide nanowires are added. Everything else is exactly the same as in Example 1.

[0041] Comparative Example 3 The difference between this comparative example and Example 1 is that silane-functionalized zinc tin oxide nanowires are not added; only boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets are added. Everything else is exactly the same as in Example 1.

[0042] The properties of the sprayable conductive PPE / PA materials provided in the above embodiments and comparative examples were tested using the following methods: Volume resistivity test: The coated sample was cut into 100mm × 100mm square specimens and conditioned for 24 hours at an ambient temperature of 23±2℃ and a relative humidity of 50±5%. Using a high insulation resistance tester, conductive silver paste was coated on two opposite sides of the specimen as electrodes, with an electrode spacing of 50mm and an electrode width of 10mm. A 100V DC voltage was applied, and the resistance value was read after 1 minute. The volume resistivity was calculated using the following formula: ρv = R × S / L, where ρv is the volume resistivity in Ω·cm; R is the measured resistance in Ω; S is the cross-sectional area of ​​the specimen in cm², calculated by multiplying the coating thickness by the electrode width; and L is the electrode spacing in cm. Five parallel samples were tested for each sample, and the arithmetic mean was taken as the final result.

[0043] Surface resistivity test: The coated sample was cut into 100mm × 100mm square specimens and conditioned for 24 hours under environmental conditions of 23±2℃ and 50±5% relative humidity. A high insulation resistance tester was used with concentric ring electrodes, with an inner ring diameter of 50mm and an outer ring diameter of 70mm. The concentric ring electrodes were placed on the sample surface, and a 500V DC voltage was applied. After 1 minute of energization, the surface resistance value was read. The surface resistivity was calculated using the following formula: ρs = 2π × R / ln(r2 / r1), where ρs is the surface resistivity in Ω / sq; R is the measured surface resistance in Ω; r2 is the outer ring radius in cm; and r1 is the inner ring radius in cm. Five points were tested at different locations for each sample, and the arithmetic mean was taken as the final result.

[0044] Tensile strength and elongation at break tests: The coating was carefully peeled off from the substrate to obtain a uniformly thick, individual film. The film was cut into standard tensile specimens using a dumbbell-shaped cutter. The total length of the specimen was 75 mm, the gauge length was 25 mm, the width of the parallel section in the middle was 4 mm, and the width of the ends was 10 mm. The specimens were conditioned for 24 hours at a temperature of 23±2℃ and a relative humidity of 50±5%. The specimens were clamped in the upper and lower fixtures of a universal testing machine with a fixture spacing of 25 mm, and stretched at a constant tensile speed of 50 mm / min until the specimen broke. The maximum tensile force was recorded, and the tensile strength was calculated using the following formula: σ = F max / A, where σ is the tensile strength in MPa; F max The maximum tensile force is expressed in N; A is the original cross-sectional area of ​​the specimen (specimen width × coating thickness), expressed in mm².

[0045] Elongation at break is calculated using the following formula: ε = (L b -L0) / L0×100%, where ε is the elongation at break, in units of %; L b L1 represents the gauge length at break, in mm; L2 represents the original gauge length, in mm. Five parallel samples were tested for each sample, and the arithmetic mean was taken.

[0046] Adhesion Test: The coating adhesion test was conducted using the cross-cut adhesion test. A 10×10 grid with 1mm spacing was drawn on the coating surface using a cross-cutting knife. The knife blade should penetrate the coating to reach the substrate surface during the cross-cutting process. After gently cleaning the debris from the cross-cut area with a soft brush, 3M 600 tape (25mm wide) was applied to the cross-cut area. The tape was pressed firmly with the fingers to ensure full contact with the coating, and then quickly peeled off at a 60° angle within 0.5 to 1.0 seconds. The coating peeling in the grid area was observed under standard light and rated according to the following standards: Grade 0: Completely smooth cut edges, no peeling; Grade 1: Peeling area no more than 5%; Grade 2: Peeling area greater than 5% but not more than 15%; Grade 3: Peeling area greater than 15% but not more than 35%; Grade 4: Peeling area greater than 35% but not more than 65%; Grade 5: Peeling area greater than 65%. Each sample was tested at three different locations, and the worst grade was taken as the final result.

[0047] Evaluation of melt-spray leveling properties: The coated and cured sample was placed in a standard light source box (1000 lux, 6500 K) and the surface morphology was observed at a 45° angle. Evaluation indicators included surface smoothness, orange peel effect, sagging, and thickness uniformity. Evaluation criteria were: Excellent: The coating surface was completely smooth and uniform, with no orange peel, sagging, or pinholes, and the visual reflection was clear; Good: The coating surface was basically uniform, with slight orange peel but no sagging, and the reflected image was slightly blurred; Poor: The coating surface was significantly uneven, with severe orange peel or visible sagging streaks, and the reflected image was severely distorted. The evaluation was conducted independently by three testers, and the majority opinion was used if the three evaluations differed.

[0048] The performance test data above are shown in Table 1:

[0049] As can be seen from the above, Examples 1-3 solve the following prior art problems compared to Comparative Examples 1-3: First, Comparative Example 1, without any added conductive filler, exhibited both volume resistivity and surface resistivity exceeding the instrument's upper limit (>1.0×10⁻⁶). 14 Ω·cm and >1.0×10 15 (Ω / sq), exhibiting an insulating state, while the volume resistivity of Examples 1-3 is as low as 1.5 × 10 Ω / sq. 4 -8.7×10 5 Ω·cm, with a surface resistivity as low as 8.9×10⁻⁶. 4 -4.2×10 6The value of Ω / sq indicates that the present invention successfully constructed a highly efficient three-dimensional conductive network with low filler content through the synergistic effect of silane-functionalized zinc tin oxide nanowires and boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets. This solves the problems of poor dispersion of conductive fillers, discontinuous conductive pathways, and difficulty in achieving good conductivity with low filler content in the prior art.

[0050] Secondly, Comparative Example 2, which only added silane-functionalized zinc tin oxide nanowires (one-dimensional filler), had a volume resistivity of 3.8 × 10⁻⁶. 8 Ω·cm, surface resistivity 2.1×10 9 Ω / sq; Comparative Example 3, with only boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets, has a volume resistivity of 5.2 × 10⁻⁶ Ω / sq. 7 Ω·cm, surface resistivity 2.8×10 8 The resistivity of Examples 1-3 was reduced by 2 to 4 orders of magnitude compared to Comparative Examples 2-3, indicating that the complementary morphology of one-dimensional and two-dimensional fillers and the synergistic effect of "bridging-planar transport" are key technical means to solve the problems of incomplete conductive networks and high percolation threshold.

[0051] Furthermore, Comparative Example 1 exhibited a tensile strength of only 42.6 MPa, an elongation at break of only 8.3%, and an adhesion grade of 3, indicating severe phase separation and weak interfacial bonding in the PPE / PA incompatible system. Although Comparative Examples 2 and 3 added a single modifying compound, their tensile strengths were 51.2 MPa and 52.8 MPa, respectively, their elongation at break were 10.1% and 10.5%, respectively, and their adhesion grades were all 2, indicating unsatisfactory mechanical properties. In contrast, Examples 1-3 achieved tensile strengths ranging from 55.3 to 72.1 MPa. The elongation at break reaches 12.8-16.5%, and the adhesion is grade 0-1, which is significantly better than the comparative example. This is because the primary amino groups on the surface of the silane-functionalized zinc tin oxide nanowires undergo ring-opening imidization reaction with the maleic anhydride of the styrene-maleic anhydride copolymer. At the same time, the oxygen-containing functional groups of the two-dimensional nanosheets form chemical bonds with the end groups of polyamide 66, thereby realizing the interfacial covalent connection between the filler and the polymer matrix. This solves the problems of poor interfacial compatibility between inorganic fillers and organic matrices, low stress transfer efficiency, and deterioration of mechanical properties in the prior art.

[0052] Finally, regarding sprayability, the melt spraying leveling properties of Comparative Examples 1-3 were all good, while Examples 1 and 3 achieved excellent, and Example 2 was good. This indicates that the one-dimensional / two-dimensional synergistic filler of the present invention has little impact on melt viscosity at low filler amounts, and achieves good atomization leveling properties in conjunction with a lubricant, solving the problems of poor leveling and numerous surface defects in traditional conductive composite material melt spraying. In summary, the present invention, through the synergistic conductive network and interfacial chemical bonding of two novel inorganic modified compounds, successfully solves the comprehensive technical problems in the prior art, such as conductive filler agglomeration, incomplete conductive network, poor interfacial compatibility, decreased mechanical properties, and poor sprayability.

Claims

1. A sprayable conductive PPE / PA material, characterized in that, The product comprises the following components in parts by weight: 30-60 parts polyphenylene ether, 30-60 parts polyamide 66, 5-15 parts styrene-maleic anhydride copolymer, 0.5-5 parts silane-functionalized zinc tin oxide nanowires, 0.5-5 parts boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets, 0.1-1.0 parts antioxidant 1010, and 0.2-2 parts ethylene bis-stearamide.

2. The sprayable conductive PPE / PA material according to claim 1, characterized in that, The preparation steps of the sprayable conductive PPE / PA material include: S1. Silane-functionalized zinc tin oxide nanowires and boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets are ultrasonically dispersed in anhydrous ethanol to obtain a dispersion. The dispersion is then rotary evaporated in a rotary evaporator at 58-62℃ to collect the mixed powder. The mixed powder is dried in a vacuum drying oven at 78-82℃ to obtain a dried mixed powder. Polyphenylene ether is dried in a forced-air drying oven at 98-102℃ to obtain dried polyphenylene ether. Polyamide 66 is dried in a vacuum drying oven at 78-82℃ to obtain dried polyamide 66. Styrene-maleic anhydride copolymer is dried in a drying oven at 78-82℃ to obtain dried styrene-maleic anhydride copolymer. The dried polyphenylene ether, polyamide 66, styrene-maleic anhydride copolymer, mixed powder, antioxidant 1010, and ethylene bis-stearamide are premixed in a mixer to obtain a premix. S2. The premixed material is fed into a twin-screw extruder for melt blending and extrusion to obtain an extruded molten strip. The extruded molten strip is cooled in a water tank and then fed into a pelletizer for granulation to obtain granules. The granules are dried in a vacuum drying oven at 78-82℃ to obtain dried granules. The dried granules are added to a melt spraying extruder to obtain molten material. The molten material is atomized and sprayed onto the surface of the substrate through a spraying die. After spraying, it is cured in an oven at 118-122℃.

3. The sprayable conductive PPE / PA material according to claim 2, characterized in that, In step S1, the ultrasonic dispersion time is 30-60 min.

4. The sprayable conductive PPE / PA material according to claim 2, characterized in that, In step S2, the temperature of the melt spray extruder is set to 260-280℃.

5. The sprayable conductive PPE / PA material according to claim 1, characterized in that, The preparation method of the silane-functionalized zinc tin oxide nanowires includes: A1. Dissolving 5-8 parts by weight of zinc nitrate hexahydrate and 7-10 parts by weight of tin tetrachloride pentahydrate in 100-150 parts by weight of deionized water, stirring at room temperature to obtain a precursor solution; adding 10-20 parts by weight of ammonia water dropwise to the precursor solution to adjust the pH to 8.8-9.2, and continuing to stir to obtain a suspension; transferring the suspension to a reaction vessel and performing a hydrothermal reaction at 178-182℃, then naturally cooling to room temperature to obtain a reaction mixture; centrifuging the reaction mixture to obtain a precipitate; washing the precipitate with deionized water and anhydrous ethanol, and then vacuum drying at 78-82℃. The zinc tin oxide nanowire precursor was obtained by drying in a drying oven. The precursor was then placed in a tube furnace and calcined at 395-405℃ under a nitrogen atmosphere to obtain zinc metastannate nanowires. A2. 1-2 parts of γ-aminopropyltriethoxysilane were dissolved in a mixed solvent of 40-60 parts anhydrous ethanol and 5-10 parts deionized water, and stirred at room temperature to obtain a hydrolysate. 1-1.5 parts of zinc metastannate nanowires were added to the hydrolysate, and the reaction was continued in a water bath at 58-62℃ to obtain a reaction mixture. The reaction mixture was centrifuged to obtain a precipitate. The precipitate was washed with anhydrous ethanol and dried in a vacuum drying oven at 58-62℃.

6. The sprayable conductive PPE / PA material according to claim 5, characterized in that, In step A1, the hydrothermal reaction time at 178-182℃ is 24-30 hours.

7. The sprayable conductive PPE / PA material according to claim 5, characterized in that, In step A2, the reaction time in a water bath at 58-62℃ is 6-8 hours.

8. The sprayable conductive PPE / PA material according to claim 1, characterized in that, The preparation method of the boron-nitrogen co-doped reduced graphene oxide-silver hybrid nanosheets includes: B1, dispersing 1-2 parts by weight of graphene oxide in 200-250 parts by weight of deionized water, ultrasonically dispersing to obtain a graphene oxide dispersion; adding 0.5-1 parts by weight of boric acid and 1-2 parts by weight of urea to the graphene oxide dispersion, stirring at room temperature to obtain a mixture; transferring the mixture to a reaction vessel, hydrothermally reacting at 178-182℃, and naturally cooling to obtain a reaction solution; adding a mixture containing 0.3-0.5 parts by weight of silver nitrate and 10-15 parts by weight of deionized water to the reaction solution, stirring at room temperature; then adding 0.5-1 parts by weight of ascorbic acid, stirring at 58-62℃ to obtain a reaction mixture; B2, centrifuging the reaction mixture to separate the precipitate; washing the precipitate with deionized water and anhydrous ethanol, and drying it in a vacuum drying oven at 58-62℃.

9. The sprayable conductive PPE / PA material according to claim 8, characterized in that, In step B1, the hydrothermal reaction time at 178-182℃ is 12-14 hours.

10. The sprayable conductive PPE / PA material according to claim 8, characterized in that, In step B2, the drying time in a vacuum drying oven at 58-62℃ is 24-30 hours.

Images