Halogen-free high-thermal-conductivity composite material, explosion-proof lamp heat dissipation piece, preparation method and application

Abstract

The present application relates to halogen-free high thermal conductivity composite, explosion-proof lamp heat dissipation piece and preparation method and application, belong to polymer composite material, industrial lighting, consumer electronics, new energy storage heat dissipation device manufacturing technology field;The halogen-free high thermal conductivity composite includes the following weight parts raw materials: high molecular polymer 39~45 parts, alkali-free glass fiber short cut original wire for thermoplastic plastic 19~24 parts, composite heat conducting mineral filler 16~21 parts, carbon-based auxiliary heat conducting filler 0.8~1.5 parts, compound halogen-free flame retardant 11~14 parts, color master batch 1.3~2.2 parts, composite processing aid 1.8~2.8 parts.The present application realizes the maximization of the comprehensive performance of composite material in heat conduction, flame retardant, dimensional stability, mechanical property, processability, aging resistance and the like through the mutual cooperation of carbon-based dual-component filler, phosphorus-nitrogen flame-retardant component, composite three-systems and the mutual synergy of each compound material in three-systems.

Description

Technical Field

[0001] This invention relates to halogen-free high thermal conductivity composite materials, explosion-proof lighting heat sinks, their preparation methods and applications, and belongs to the technical fields of polymer composite materials, industrial lighting, consumer electronics, and new energy storage heat sink manufacturing. Background Technology

[0002] Industrial explosion-proof lighting fixtures, floodlights, and other high-power lighting equipment generate a large amount of heat during operation, and their heat dissipation performance directly determines the lifespan and safety of the fixtures. Currently, the heat sink housings and radiators of such fixtures are almost entirely made of aluminum alloy materials (such as ADC12 die-cast aluminum and 6063 extruded aluminum profiles) through die casting or extrusion molding. However, electrolytic aluminum smelting has high power consumption per unit product, and die casting and subsequent processes such as pickling, electroplating, and anodizing are highly polluting processes. High-energy-consuming aluminum smelting and die casting capacity is limited, and the costs of pollution control and environmental remediation for enterprises are increasing year by year, resulting in high overall manufacturing costs for aluminum radiators. Furthermore, after die casting, aluminum alloy radiators require multiple post-processing steps such as drilling, tapping, cutting, grinding, and surface coating, making the process lengthy. The manufacturing cost of aluminum die casting molds is typically 50% to 100% higher than that of non-metallic injection molds, placing significant pressure on small and medium-sized lighting enterprises in terms of initial mold investment. From a material perspective, aluminum is a conductive metal, requiring additional insulating pads during PCB assembly, increasing the variety of components and assembly time. Furthermore, aluminum alloy has a density of approximately 2.7 g / cm³, making the finished product relatively heavy and increasing the logistics, transportation, and installation costs of the entire lighting fixture. Therefore, finding non-metallic heat dissipation materials to replace aluminum alloy has become an urgent need for cost reduction, efficiency improvement, and green transformation in the industrial lighting sector.

[0003] In the field of non-metallic heat dissipation materials, there are currently significant differences among various modification manufacturers in terms of formulation systems, filler types, and addition amounts, resulting in inconsistent material performance and severely restricting the engineering application of non-metallic heat dissipation materials. As for existing thermally conductive non-metallic materials, their comprehensive performance is insufficient to simultaneously meet the requirements of mechanical properties, thermal conductivity, flame retardancy, and processing. For example, the thermal conductivity of pure glass fiber reinforced PA6 material is only 0.3~1 W / (m·K), which is significantly insufficient in heat dissipation. Moreover, its flame retardant rating is mostly V2, and its glow wire temperature is below 850℃, which cannot meet the mandatory safety specifications for explosion-proof lighting fixtures. Although thermally conductive PA6 filled with boron nitride or high-purity carbon nanotubes can achieve a higher thermal conductivity, the high price of high-end fillers increases the raw material cost by more than 30% compared to ordinary PA6, making it difficult to carry out large-scale industrialization. At the same time, the disordered dispersion of fillers can easily cause differences in molding shrinkage, resulting in severe warping and deformation of injection molded parts. Although single mineral filled PA6 improves dimensional stability, its impact strength and tensile strength are greatly reduced, and it is prone to cracking under drop hammer impact, failing to meet the 7J impact resistance rating required for explosion-proof lighting fixtures. Furthermore, after adding a large amount of halogen-free flame retardant, the interface between the resin and the filler is destroyed, resulting in a precipitous decline in mechanical properties. More importantly, in the domestic industrial explosion-proof electrical field, there are almost no mature industrialization cases of replacing aluminum alloys with all-non-metallic heat sinks. Most thermally conductive non-metallic material solutions are only at the laboratory sample testing stage, with actual installed temperature rise being too high, failing to achieve a true all-non-metallic shell replacement. In addition, the mechanical and thermal conductivity properties of commonly used thermally conductive nylon and other modified materials generally decrease by more than 20% under humid heat environments of 85℃ / 85%RH or long-term high-temperature conditions of 150℃, which cannot meet the stringent requirements for weather resistance and aging in the harsh all-weather use environment of outdoor explosion-proof electrical equipment.

[0004] In summary, the existing technology lacks a high thermal conductivity composite material that offers balanced overall performance, controllable cost, and is halogen-free and environmentally friendly, which cannot meet the industrialization demand for large-scale replacement of aluminum alloy materials with non-metallic composite materials in industrial explosion-proof lighting radiators. Summary of the Invention

[0005] This invention addresses the aforementioned technical problems by providing a halogen-free high thermal conductivity composite material, an explosion-proof lighting heat sink, its preparation method, and its application. It aims to solve the problems of high energy consumption, high pollution, cumbersome processing, and inherent defects of metal aluminum heat dissipation solutions. Simultaneously, it overcomes the contradictions in coordinating thermal conductivity, mechanics, flame retardancy, weather resistance, and cost among existing non-metallic materials, filling the gap in the field of non-metallic heat dissipation materials for explosion-proof lighting.

[0006] The technical solution provided by this invention is as follows: One of the objectives of this invention is to provide a halogen-free high thermal conductivity composite material, comprising the following raw materials in parts by weight: 39-45 parts of polymer, 19-24 parts of chopped alkali-free glass fiber for thermoplastic plastics, 16-21 parts of composite thermally conductive mineral filler, 0.8-1.5 parts of carbon-based auxiliary thermally conductive filler, 11-14 parts of compounded halogen-free flame retardant, 1.3-2.2 parts of color masterbatch, and 1.8-2.8 parts of composite processing aid.

[0007] Based on the above technical solution, the present invention can be further improved as follows: Furthermore, the polymer is PA6 resin or PA66 resin.

[0008] Furthermore, the composite thermally conductive mineral filler is composed of calcined silica, alumina, and flaky kaolin in a mass ratio of 3.5~4.5:4.5~5.5:0.8~1.2.

[0009] Furthermore, the composite thermally conductive mineral filler is composed of silica powder and magnesium oxide in a mass ratio of 0.8~1.2:0.8~1.2.

[0010] Furthermore, the carbon-based auxiliary thermally conductive filler is composed of ultrafine graphite and carbon nanotubes in a mass ratio of 8.0~9.5:0.5~2.0.

[0011] Furthermore, the compounded halogen-free flame retardant is prepared by compounding aluminum hypophosphite and nitrogen-based flame retardant in a mass ratio of 3.2~4.8:0.8~1.8.

[0012] Furthermore, the composite processing aid is composed of hindered phenolic antioxidant, polyolefin lubricant, and silane coupling agent in a mass ratio of 1.6~2.4:4.2~5.8:2.4~3.6.

[0013] Furthermore, the hindered phenolic antioxidant is any one of antioxidant 1010, antioxidant 1076, antioxidant 245, AO-80, and antioxidant 1098.

[0014] Furthermore, the polyolefin lubricant is any one of polyethylene wax, oxidized polyethylene wax, and ethylene-vinyl acetate wax.

[0015] Furthermore, the silane coupling agent is any one of KH-550, KH-560, KH-570, and KH-792.

[0016] A second objective of this invention is to provide a method for preparing the halogen-free high thermal conductivity composite material as described above, comprising the following steps: S1: Raw material pretreatment: Dry the polymer at 100~120℃ for 4~6h to make the moisture content ≤0.10%; Pre-dry the thermoplastic plastic with alkali-free glass fiber short filaments and composite thermally conductive mineral filler at 75~85℃ for 1.5~2.5h to remove free moisture. S2: Material premixing: The pretreated polymer, color masterbatch, compound halogen-free flame retardant, and composite processing aid are put into the mixer and stirred for 5-8 minutes; then the pretreated composite thermally conductive mineral filler and carbon-based auxiliary thermally conductive filler are fed into the mixer through the side feed port of the twin screw, and the pretreated thermoplastic plastic is fed into the mixer with alkali-free glass fiber chopped filaments through independent side feeding for mixing. S3: Twin-screw extrusion: Set screw length-to-diameter ratio to 40:1, barrel section temperature to 240~285℃, main unit speed to 320~430rpm, nozzle temperature to 275~295℃, and barrel vacuum pressure to -0.07~-0.09MPa for devolatilization extrusion; S4: Cooling and pelletizing: The extruded strip is water-cooled, air-dried, pelletized and screened to obtain a halogen-free high thermal conductivity composite material.

[0017] Furthermore, the water cooling temperature is controlled at 25~40℃, the water tank cooling length is 3~6m, and the material traction speed is 10~20m / min; the air drying uses hot air at 40~60℃ with an air pressure of 0.03~0.06MPa; the pelletizer speed is 350~550rpm, and the pellet length is 2.5~4.0mm; the sieving is a multi-stage vibrating screen for grading, with an upper 4-mesh screen to remove long strips and lumps, a middle 8-mesh screen to retain qualified particles, and a bottom 20-mesh screen to filter powder and debris.

[0018] The third objective of this invention is to provide an explosion-proof lighting fixture heat sink, which is injection molded from the halogen-free high thermal conductivity composite material described above. The fourth objective of this invention is to provide a method for preparing the explosion-proof lighting heat sink as described above, comprising the following steps: drying the halogen-free high thermal conductivity composite material as described above, performing twin-screw melt extrusion, and then injecting it into a structural reinforcement mold for injection molding.

[0019] The fifth objective of this invention is to provide the application of the explosion-proof lamp heat sink as described above in the fields of explosion-proof lighting equipment, new energy storage, LED lighting, and camera heat sink housing.

[0020] The technical solution provided by this invention has the following advantages compared with the prior art: 1. This invention does not rely on a single thermally conductive filler, but rather uses a precise blend of carbon-based two-component fillers and a polymer matrix to synergistically construct a three-dimensional thermally conductive network, thereby improving the thermal conductivity of the composite material. It employs a low-addition phosphorus-nitrogen compound halogen-free flame-retardant system, ensuring flame-retardant efficiency while avoiding halogen introduction. This allows the material to simultaneously meet the stringent safety requirements of UL94 V-0 flame retardancy and glow wire 960°C. Furthermore, the entire formulation is halogen-free, complying with RoHS directives and relevant IEC standards for explosion-proof electrical appliances. Balancing high flame retardancy with environmental friendliness, it is suitable for scenarios with extremely high safety requirements, such as explosion-proof lighting fixtures. Through the synergistic regulation of a ternary composite processing aid system, the molding shrinkage rate of injection-molded parts is effectively controlled, significantly reducing warpage and improving product dimensional accuracy and batch consistency, laying the foundation for large-scale precision injection molding of complex heat dissipation components.

[0021] 2. To address the mechanical shortcomings of non-metallic materials, this invention incorporates structural design optimization measures such as mold reinforcement ribs and local thickening to compensate for the inherent rigidity and impact resistance of composite materials. This ensures that explosion-proof lighting fixtures meet the mechanical strength requirements under harsh operating environments, guaranteeing long-term service safety and accelerating the industrialization and promotion of high-performance halogen-free thermally conductive composite materials in the fields of electrical and electronic engineering, lighting, and explosion-proof equipment.

[0022] 3. This invention maximizes the comprehensive performance of composite materials in terms of thermal conductivity, flame retardancy, dimensional stability, mechanical properties, processability, and aging resistance by combining three systems: carbon-based two-component filler, phosphorus-nitrogen flame retardant component, and ternary processing aid, and by the synergistic effect of each compound substance in the three systems. Detailed Implementation

[0023] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0024] Example 1 A halogen-free high thermal conductivity composite material comprises the following raw materials in parts by weight: 42 parts PA6 resin, 22 parts alkali-free glass fiber chopped strands for thermoplastic plastics (China Jushi Co., Ltd., model 568H), 19 parts composite thermally conductive mineral filler, 1.2 parts carbon-based auxiliary thermally conductive filler, 13 parts compounded halogen-free flame retardant, 2.1 parts black masterbatch, and 2.5 parts composite processing aid; The composite thermally conductive mineral filler is composed of calcined silica, alumina, and flaky kaolin in a mass ratio of 4:5:1. The carbon-based auxiliary thermally conductive filler is composed of ultrafine graphite and carbon nanotubes in a mass ratio of 9:1. The compounded halogen-free flame retardant is composed of aluminum hypophosphite and nitrogen-based flame retardant MCA in a mass ratio of 4:1. The composite processing aid is composed of antioxidant 1010, polyethylene wax, and KH-550 in a mass ratio of 2:5:3.

[0025] The preparation method of the halogen-free high thermal conductivity composite material as described above includes the following steps: S1: Raw material pretreatment: PA6 resin is dried in hot air at 110℃ for 5 hours to make the moisture content ≤0.10%; thermoplastic plastics are pre-dried in alkali-free glass fiber short filaments and composite thermally conductive mineral fillers at 80℃ for 2 hours to remove free moisture. S2: Material premixing: Add the pretreated PA6 resin, color masterbatch, compound halogen-free flame retardant, and compound processing aid to the mixer and stir for 6 minutes; then add the pretreated composite thermally conductive mineral filler and carbon-based auxiliary thermally conductive filler through the side feed port of the twin screw, and add the pretreated thermoplastic plastic alkali-free glass fiber chopped filaments to the mixer through independent side feeding for mixing. S3: Twin-screw extrusion: Set screw length-to-diameter ratio to 40:1, barrel section temperature to 240~285℃, main unit speed to 380rpm, nozzle temperature to 285℃, and barrel vacuum pressure to -0.08MPa for devolatilization extrusion; The barrel is divided into 6 heating zones and 1 transition section, totaling 7 sections: Zone 1 (feeding section): 240℃; Zone 2 (melting premixing section): 250℃; Zone 3 (filler dispersion section): 260℃; Zone 4 (thermally conductive filler and flame retardant strong shear section): 270℃; Zone 5 (homogenization and devolatilization section): 278℃; Zone 6 (pressurization and conveying section): 282℃; Zone 7 (before the die head): 285℃; Die head: 285℃; Nozzle: 285℃; S4: Cooling and pelletizing: The extruded strips are water-cooled, air-dried, pelletized, and screened to obtain halogen-free high thermal conductivity composite materials; the water cooling temperature is 35℃, the water tank cooling length is 5m, the strip traction speed is 15m / min, and the air drying uses 50℃ hot air with an air pressure of 0.05MPa to completely remove free moisture from the surface of the strips; the pelletizer speed is 450rpm to produce cylindrical particles with a length of 3mm; then, the particles are classified by multi-stage vibrating screens, with the upper 4-mesh screen removing long strip lumps, the middle 8-mesh screen retaining qualified particles, and the bottom 20-mesh screen filtering out powder and debris.

[0026] An explosion-proof lighting fixture heat sink is injection molded from the halogen-free high thermal conductivity composite material as described above.

[0027] The preparation method of the explosion-proof lighting heat sink as described above includes the following steps: drying the prepared halogen-free high thermal conductivity composite material under hot air at 110℃ for 5 hours to make the moisture content ≤0.10%; setting the screw length-to-diameter ratio of the twin-screw extrusion to 40:1, the barrel segment temperature to 240~285℃ (the barrel segment temperature refers to the preparation method of the halogen-free high thermal conductivity composite material described above), the main engine speed to 380rpm, the nozzle temperature to 285℃, and the barrel vacuum negative pressure to -0.08MPa for devolatilization extrusion, and then injecting it into a reinforcing mold (mold temperature 100℃) with internal reinforcing ribs and locally thickened structures for integral injection molding (injection molding pressure is 100MPa) to obtain the explosion-proof lighting heat sink.

[0028] Example 2 A halogen-free high thermal conductivity composite material comprises the following raw materials in parts by weight: 39 parts PA66 resin, 19 parts alkali-free glass fiber chopped strands for thermoplastic plastics (China Jushi Co., Ltd., model 568H), 16 parts composite thermally conductive mineral filler, 0.8 parts carbon-based auxiliary thermally conductive filler, 11 parts compounded halogen-free flame retardant, 1.3 parts black masterbatch, and 1.8 parts composite processing aid; The composite thermally conductive mineral filler is composed of calcined silica, alumina, and flaky kaolin in a mass ratio of 4:5:1. The carbon-based auxiliary thermally conductive filler is composed of ultrafine graphite and carbon nanotubes in a mass ratio of 9:1. The compounded halogen-free flame retardant is a mixture of aluminum hypophosphite and nitrogen-based flame retardant MCA in a mass ratio of 4:1. The composite processing aid is composed of antioxidant 1076, oxidized polyethylene wax, and KH-560 in a mass ratio of 2:5:3.

[0029] The preparation method of the halogen-free high thermal conductivity composite material as described above includes the following steps: S1: Raw material pretreatment: PA66 resin is dried in hot air at 100℃ for 4 hours to make the moisture content ≤0.10%; thermoplastic plastics are pre-dried in alkali-free glass fiber short filaments and composite thermally conductive mineral fillers at 80℃ for 2 hours to remove free moisture. S2: Material premixing: Add the pretreated PA66 resin, color masterbatch, compound halogen-free flame retardant, and compound processing aid to the mixer and stir for 5 minutes; then add the pretreated composite thermally conductive mineral filler and carbon-based auxiliary thermally conductive filler through the side feed port of the twin screw, and add the pretreated thermoplastic plastic alkali-free glass fiber chopped filaments to the mixer through independent side feeding for mixing. S3: Twin-screw extrusion: Set the screw length-to-diameter ratio to 40:1, the barrel section temperature to 240~285℃ (same as in Example 1), the main machine speed to 320rpm, the nozzle temperature to 275℃, and the barrel vacuum pressure to -0.08MPa for devolatilization extrusion; S4: Cooling and pelletizing: The extruded strips are water-cooled, air-dried, pelletized, and screened to obtain halogen-free high thermal conductivity composite materials; the water cooling temperature is 25℃, the water tank cooling length is 3m, the strip traction speed is 10m / min, and the air drying uses 40℃ hot air with an air pressure of 0.03MPa to completely remove free moisture from the surface of the strips; the pelletizer speed is 350rpm to produce cylindrical particles with a length of 2.5mm; then, the particles are classified by multi-stage vibrating screens, with the upper 4-mesh screen removing long strip lumps, the middle 8-mesh screen retaining qualified particles, and the bottom 20-mesh screen filtering out powder and debris.

[0030] An explosion-proof lighting fixture heat sink is injection molded from the halogen-free high thermal conductivity composite material as described above.

[0031] The preparation method of the explosion-proof lamp heat sink as described above includes the following steps: drying the prepared halogen-free high thermal conductivity composite material under hot air at 100°C for 4 hours to make the moisture content ≤0.10%; setting the screw length-to-diameter ratio of the twin screw to 40:1, the barrel section temperature to 240~285°C (same as in Example 1), the main machine speed to 320 rpm, the nozzle temperature to 275°C, and the barrel vacuum negative pressure to -0.08MPa for devolatilization extrusion, and then injecting it into a reinforcing mold (mold temperature 80°C) with internal reinforcing ribs and locally thickened structures for integral injection molding (injection molding pressure to 80MPa) to obtain the explosion-proof lamp heat sink.

[0032] Example 3 A halogen-free high thermal conductivity composite material comprises the following raw materials in parts by weight: 45 parts PA6 resin, 24 parts alkali-free glass fiber chopped strands for thermoplastic plastics (China Jushi Co., Ltd., model 568H), 21 parts composite thermally conductive mineral filler, 1.5 parts carbon-based auxiliary thermally conductive filler, 14 parts compounded halogen-free flame retardant, 2.2 parts black masterbatch, and 2.8 parts composite processing aid; The composite thermally conductive mineral filler is composed of calcined silica, alumina, and flaky kaolin in a mass ratio of 4:5:1. The carbon-based auxiliary thermally conductive filler is composed of ultrafine graphite and carbon nanotubes in a mass ratio of 9:1. The compounded halogen-free flame retardant is a mixture of aluminum hypophosphite and nitrogen-based flame retardant MCA in a mass ratio of 4:1. The composite processing aid is composed of AO-80, ethylene-vinyl acetate wax, and KH-570 in a mass ratio of 2:5:3.

[0033] The preparation method of the halogen-free high thermal conductivity composite material as described above includes the following steps: S1: Raw material pretreatment: PA6 resin is dried in hot air at 120℃ for 6 hours to make the moisture content ≤0.10%; thermoplastic plastics are pre-dried in alkali-free glass fiber short filaments and composite thermally conductive mineral fillers at 80℃ for 2 hours to remove free moisture. S2: Material premixing: Add the pretreated PA6 resin, color masterbatch, compound halogen-free flame retardant, and compound processing aid to the mixer and stir for 8 minutes; then add the pretreated composite thermally conductive mineral filler and carbon-based auxiliary thermally conductive filler through the side feed port of the twin screw, and add the pretreated thermoplastic plastic alkali-free glass fiber chopped filaments to the mixer through independent side feeding for mixing. S3: Twin-screw extrusion: Set the screw length-to-diameter ratio to 40:1, the barrel section temperature to 240~285℃ (same as in Example 1), the main machine speed to 430rpm, the nozzle temperature to 295℃, and the barrel vacuum pressure to -0.08MPa for devolatilization extrusion; S4: Cooling and pelletizing: The extruded strip is water-cooled, air-dried, pelletized and screened to obtain a halogen-free high thermal conductivity composite material; The water cooling temperature is 40℃, the water tank cooling length is 6m, the material strip traction speed is 20m / min, and the air drying uses 60℃ hot air with an air pressure of 0.06MPa to completely remove free moisture from the surface of the material strip; the pelletizer speed is 550rpm to produce cylindrical particles with a length of 4.0mm; then the particles are classified by multi-stage vibrating screens, with the upper 4-mesh screen removing long strip lumps, the middle 8-mesh screen retaining qualified particles, and the bottom 20-mesh screen filtering out powder and debris.

[0034] An explosion-proof lighting fixture heat sink is injection molded from the halogen-free high thermal conductivity composite material as described above.

[0035] The preparation method of the explosion-proof lamp heat sink as described above includes the following steps: drying the prepared halogen-free high thermal conductivity composite material under hot air at 120°C for 6 hours to make the moisture content ≤0.10%; setting the screw length-to-diameter ratio of the twin screw to 40:1, the barrel section temperature to 240~285°C (same as in Example 1), the main machine speed to 430 rpm, the nozzle temperature to 295°C, and the barrel vacuum negative pressure to -0.08MPa for devolatilization extrusion, and then injecting it into a reinforcing mold (mold temperature 120°C) with internal reinforcing ribs and locally thickened structures for integral injection molding (injection molding pressure to 120MPa) to obtain the explosion-proof lamp heat sink.

[0036] Example 4 A halogen-free high thermal conductivity composite material comprises the following raw materials in parts by weight: 42 parts PA6 resin, 22 parts alkali-free glass fiber chopped strands for thermoplastic plastics (China Jushi Co., Ltd., model 568H), 19 parts composite thermally conductive mineral filler, 1.2 parts carbon-based auxiliary thermally conductive filler, 13 parts compounded halogen-free flame retardant, 2.1 parts black masterbatch, and 2.5 parts composite processing aid; The composite thermally conductive mineral filler is composed of silica powder and magnesium oxide in a mass ratio of 1:1. The carbon-based auxiliary thermally conductive filler is composed of ultrafine graphite and carbon nanotubes in a mass ratio of 9:1. The compounded halogen-free flame retardant is a mixture of aluminum hypophosphite and nitrogen-based flame retardant MCA in a mass ratio of 4:1. The composite processing aid is composed of antioxidant 1098, polyethylene wax, and KH-792 in a mass ratio of 2:5:3.

[0037] The preparation method of the halogen-free high thermal conductivity composite material as described above includes the following steps: S1: Raw material pretreatment: PA6 resin is dried in hot air at 110℃ for 5 hours to make the moisture content ≤0.10%; thermoplastic plastics are pre-dried in alkali-free glass fiber short filaments and composite thermally conductive mineral fillers at 80℃ for 2 hours to remove free moisture. S2: Material premixing: Add the pretreated PA6 resin, color masterbatch, compound halogen-free flame retardant, and compound processing aid to the mixer and stir for 6 minutes; then add the pretreated composite thermally conductive mineral filler and carbon-based auxiliary thermally conductive filler through the side feed port of the twin screw, and add the pretreated thermoplastic plastic alkali-free glass fiber chopped filaments to the mixer through independent side feeding for mixing. S3: Twin-screw extrusion: Set the screw length-to-diameter ratio to 40:1, the barrel section temperature to 240~285℃ (same as in Example 1), the main machine speed to 380rpm, the nozzle temperature to 285℃, and the barrel vacuum pressure to -0.08MPa for devolatilization extrusion; S4: Cooling and pelletizing: The extruded strip is water-cooled, air-dried, pelletized and screened to obtain a halogen-free high thermal conductivity composite material; The water cooling temperature is 35℃, the water tank cooling length is 5m, the material strip traction speed is 15m / min, and the air drying uses 50℃ hot air with an air pressure of 0.05MPa to completely remove free moisture from the surface of the material strip. The pelletizer rotates at 450rpm to produce cylindrical particles with a length of 3mm. Subsequently, the particles are classified by a multi-stage vibrating screen. The upper 4-mesh screen removes long strip lumps, the middle 8-mesh screen retains qualified particles, and the bottom 20-mesh screen filters out powder and debris.

[0038] An explosion-proof lighting fixture heat sink is injection molded from the halogen-free high thermal conductivity composite material as described above.

[0039] The preparation method of the explosion-proof lamp heat sink as described above includes the following steps: drying the prepared halogen-free high thermal conductivity composite material under hot air at 110°C for 5 hours to make the moisture content ≤0.10%; setting the screw length-to-diameter ratio of the twin screw to 40:1, the barrel section temperature to 240~285°C (same as in Example 1), the main machine speed to 380 rpm, the nozzle temperature to 285°C, and the barrel vacuum negative pressure to -0.08MPa for devolatilization extrusion, and then injecting it into a reinforcing mold (mold temperature 100°C) with internal reinforcing ribs and locally thickened structures for integral injection molding (injection molding pressure to 100MPa) to obtain the explosion-proof lamp heat sink.

[0040] Comparative Example 1 Referring to Example 1, the difference from Example 1 is that 1.2 parts of carbon-based auxiliary thermally conductive filler are replaced with 1.2 parts of ultrafine graphite, and no carbon nanotubes are added.

[0041] Comparative Example 2 Referring to Example 1, the difference from Example 1 is that 1.2 parts of carbon-based auxiliary thermally conductive filler are replaced with 1.2 parts of carbon nanotubes, and no ultrafine graphite is added.

[0042] Comparative Example 3 Referring to Example 1, the difference from Example 1 is that 13 parts of the compound halogen-free flame retardant are replaced with 13 parts of aluminum hypophosphite, and no nitrogen-based flame retardant MCA is added.

[0043] Comparative Example 4 Referring to Example 1, the difference from Example 1 is that 13 parts of the compound halogen-free flame retardant are replaced with 13 parts of nitrogen-based flame retardant MCA, and aluminum hypophosphite is not added.

[0044] Comparative Example 5 Referring to Example 1, the difference from Example 1 is that the compounded halogen-free flame retardant is a mixture of aluminum hypophosphite and nitrogen-based flame retardant MCA in a mass ratio of 1.5:1.

[0045] Comparative Example 6 Referring to Example 1, the difference from Example 1 is that the composite processing aid is composed of polyethylene wax and KH-550 in a mass ratio of 5:3.

[0046] Comparative Example 7 Referring to Example 1, the difference from Example 1 is that the composite processing aid is composed of antioxidant 1010 and KH-550 in a mass ratio of 2:3.

[0047] Comparative Example 8 Referring to Example 1, the difference from Example 1 is that the composite processing aid is composed of antioxidant 1010 and polyethylene wax in a mass ratio of 2:5.

[0048] Comparative Example 9 Referring to Example 1, the difference from Example 1 is that 2.5 parts of the composite processing aid are replaced with 2.5 parts of KH-550.

[0049] Performance testing: 1. Thermal conductivity: Refer to GB / T 10297 "Determination of thermal conductivity of non-metallic solid materials - hot wire method"; 2. Infrared emissivity: Refer to the FTIR integrating sphere reflectance method (8-13μm atmospheric infrared window); 3. Parallel molding shrinkage: Refer to GB / T 17037.4-2003 "Preparation of injection molded specimens of thermoplastic materials - Part 4: Determination of molding shrinkage"; 4. Notched impact strength: Refer to GB / T 1843-2008 "Determination of impact strength of plastic cantilever beams"; 5. UL94 rating determination: Refer to UL94 Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances; 6. Glow wire test: Refer to GB / T 5169.13-2024 "Fire hazard testing of electrical and electronic products - Part 13: Glow wire / hot wire basic test methods - Glow wire ignition temperature (GWIT) test method for materials"; 7. Burning dripping condition: Simultaneous UL94 and glow wire test, with visual recording throughout, divided into three levels: No dripping: The molten material has high viscosity and does not drip; Slight dripping: A small amount of melt drips without igniting the absorbent cotton. Large dripping: The continuous dripping ignited the cotton pad; 8. Smoke density test: Refer to GB / T 8323.2 "Plastic smoke generation - Part 2: Test method for determination of smoke density by single chamber method"; 9. Tensile strength test: Refer to GB / T 1040.2-2018 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics"; 10. Melt flow rate: Refer to GB / T 3682.1-2018 "Plastics - Thermoplastic Melt Mass Flow Rate"; 11. Mechanical retention rate after 85℃ / 85%RH damp heat aging: constant damp heat GB / T 2423.3 "Environmental testing - Part 2: Test methods - Cab: constant damp heat test", mechanical properties GB / T 1040 "Determination of tensile properties of plastics"; 12. Water absorption rate determination: Refer to GB / T 1034-2008 "Determination of water absorption of plastics"; 13. Extrusion processing status: Advantages: Smooth and non-sticky, smooth material strips, and uniform pellets; Poor performance: high torque, uneven discharge, pellet sticking, and poor filler dispersion.

[0050] The thermal conductivity, infrared emissivity, parallel molding shrinkage, and notched impact strength of the halogen-free high thermal conductivity composite materials prepared in Examples 1-4 and Comparative Examples 1-2 were tested, and the results are shown in Table 1. Table 1. Performance test results of halogen-free high thermal conductivity composite materials prepared in Examples 1-4 and Comparative Examples 1-2

[0051] As can be seen from Table 1, single ultrafine graphite can only form planar thermal conduction pathways, with a large number of thermal conduction breaks; single carbon nanotubes are prone to agglomeration and cannot fully overlap with mineral fillers; after the two are combined, one-dimensional carbon nanotubes fill the gaps in graphite and improve the three-dimensional thermal conduction network, while inhibiting filler agglomeration and reducing molding shrinkage. Thermal conduction, radiative heat dissipation, and dimensional stability are synergistically improved, indicating that ultrafine graphite and carbon nanotubes with carbon-based auxiliary thermal conductive fillers have a significant synergistic effect.

[0052] The halogen-free high thermal conductivity composite materials prepared in Examples 1-4 and Comparative Examples 3-5 were tested for UL94 rating, glow wire temperature, combustion dripping, smoke density, and tensile strength. The results are shown in Table 2. Table 2. Performance test results of halogen-free high thermal conductivity composite materials prepared in Examples 1-4 and Comparative Examples 3-5

[0053] As shown in Table 2, the main functions of aluminum hypophosphite are char formation and free radical capture, while the main functions of MCA are oxygen dilution and smoke suppression / drip prevention. Neither single component can simultaneously meet the V-0 rating and the 960°C glow wire requirement; furthermore, excessive MCA can lead to additive precipitation and a decrease in mechanical properties. In the formulation of the example, the phosphorus and nitrogen components form a strongly synergistic flame-retardant system, balancing flame retardancy, safety, mechanical properties, and appearance, demonstrating significant advantages of this compound formulation.

[0054] The halogen-free high thermal conductivity composite materials prepared in Examples 1-4 and Comparative Examples 6-9 were tested for melt flow rate, mechanical retention rate after 85℃ / 85%RH hygrothermal aging, water absorption rate, and extrusion processing status. The results are shown in Table 3. Table 3 Performance test results of the halogen-free high thermal conductivity composite materials prepared in Examples 1-4 and Comparative Examples 6-9

[0055] As shown in Table 3, silane coupling agents are responsible for the interfacial bonding of inorganic fillers, glass fibers, and resin, reducing water absorption and improving filler dispersibility; polyolefin lubricants improve melt flowability, reduce processing load, and prevent sticking; hindered phenolic antioxidants inhibit thermo-oxidative degradation during high-temperature processing and long-term use. The absence of any one of these three components will result in defects in processing performance, aging resistance, and interfacial properties. The ternary additives, when combined, form a synergistic system with complementary functions, simultaneously meeting multiple requirements such as processing performance, weather resistance, low water absorption, and high interfacial strength.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A halogen-free high thermal conductivity composite material, characterized in that, The raw materials include the following parts by weight: 39-45 parts of high molecular polymer, 19-24 parts of alkali-free glass fiber chopped strands for thermoplastic plastics, 16-21 parts of composite thermally conductive mineral filler, 0.8-1.5 parts of carbon-based auxiliary thermally conductive filler, 11-14 parts of compound halogen-free flame retardant, 1.3-2.2 parts of color masterbatch, and 1.8-2.8 parts of composite processing aid.

2. The halogen-free high thermal conductivity composite material according to claim 1, characterized in that, The polymer is PA6 resin or PA66 resin.

3. The halogen-free high thermal conductivity composite material according to claim 1, characterized in that, The composite thermally conductive mineral filler is composed of calcined silica, alumina, and flaky kaolin in a mass ratio of 3.5~4.5:4.5~5.5:0.8~1.

2.

4. The halogen-free high thermal conductivity composite material according to claim 1, characterized in that, The composite thermally conductive mineral filler is composed of silica powder and magnesium oxide in a mass ratio of 0.8~1.2:0.8~1.

2.

5. The halogen-free high thermal conductivity composite material according to claim 1, characterized in that, The carbon-based auxiliary thermally conductive filler is composed of ultrafine graphite and carbon nanotubes in a mass ratio of 8.0~9.5:0.5~2.0; the compounded halogen-free flame retardant is composed of aluminum hypophosphite and nitrogen-based flame retardant in a mass ratio of 3.2~4.8:0.8~1.

8.

6. The halogen-free high thermal conductivity composite material according to claim 1, characterized in that, The composite processing aid is composed of hindered phenolic antioxidant, polyolefin lubricant and silane coupling agent in a mass ratio of 1.6~2.4:4.2~5.8:2.4~3.

6.

7. The method for preparing the halogen-free high thermal conductivity composite material according to any one of claims 1 to 6, characterized in that, The steps include the following: S1: Raw material pretreatment: Dry the polymer at 100~120℃ for 4~6h to make the moisture content ≤0.10%; Pre-dry the thermoplastic plastic with alkali-free glass fiber short filaments and composite thermally conductive mineral filler at 75~85℃ for 1.5~2.5h to remove free moisture. S2: Material premixing: The pretreated polymer, color masterbatch, compound halogen-free flame retardant, and composite processing aid are put into the mixer and stirred for 5-8 minutes; then the pretreated composite thermally conductive mineral filler and carbon-based auxiliary thermally conductive filler are fed into the mixer through the side feed port of the twin screw, and the pretreated thermoplastic plastic is fed into the mixer with alkali-free glass fiber chopped filaments through independent side feeding for mixing. S3: Twin-screw extrusion: Set screw length-to-diameter ratio to 40:1, barrel section temperature to 240~285℃, main unit speed to 320~430rpm, nozzle temperature to 275~295℃, and barrel vacuum pressure to -0.07~-0.09MPa for devolatilization extrusion; S4: Cooling and pelletizing: The extruded strip is water-cooled, air-dried, pelletized and screened to obtain a halogen-free high thermal conductivity composite material.

8. A heat sink for explosion-proof lighting fixtures, characterized in that, It is injection molded from the halogen-free high thermal conductivity composite material as described in any one of claims 1 to 6.

9. The method for preparing the heat sink of the explosion-proof lamp as described in claim 8, characterized in that, Includes the following steps: The halogen-free high thermal conductivity composite material as described in any one of claims 1 to 6 is dried, melt-extruded using a twin-screw extruder, and then injected into a structural reinforcement mold for injection molding.

10. The application of the explosion-proof lamp heat sink as described in claim 8 in the fields of explosion-proof lighting equipment, new energy storage, LED lighting, and camera heat sink housing.

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