Ceramifiable halogen-free flame-retardant polypropylene composite material, preparation method and application thereof

Abstract

The application discloses a ceramicizable halogen-free flame-retardant polypropylene composite material and a preparation method and application thereof. The ceramicizable halogen-free flame-retardant polypropylene composite material comprises the following components in percentage by mass: polypropylene: 65-75%; layered magnesium-aluminum double-metal hydroxide solid-supported platinum: 3-10%; ammonium polyphosphate: 5-15%; char-forming agent: 1-10%; anti-dripping agent: 0.2-5%; antioxidant: 0.5-2%; compatibilizer: 3-10%; porcelain-forming filler: 1-5%; layered nano filler: 0.5-5%; hindered amine: 0.1-1%. The ceramicizable halogen-free flame-retardant polypropylene composite material has excellent flame-retardant performance, excellent mechanical performance and excellent ablation resistance, is suitable for being applied to the fields of electronic appliances, automobiles and building materials, and has the advantages of simple preparation method, low production cost, and suitability for large-scale industrial production and application.

Description

Technical Field

[0001] This invention relates to the field of flame-retardant composite materials technology, specifically to a halogen-free flame-retardant polypropylene composite material that can be ceramized, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP) possesses excellent physical and chemical properties and is widely used in electronics, automobiles, and building materials. However, polypropylene has extremely poor char-forming ability (during pyrolysis or combustion, polypropylene mainly undergoes random chain scission reactions, generating flammable small-molecule volatiles with almost no char residue), making it impossible to form a continuous, dense, heat-insulating, and oxygen-barrier char layer on its surface (flame and heat can directly act on the interior of the polypropylene matrix, accelerating its decomposition). It also lacks a condensed-phase flame-retardant protection mechanism, resulting in polypropylene's flammability.

[0003] Currently, the flame retardant properties of polypropylene are mainly improved by adding halogen-free flame retardants. Commonly used halogen-free flame retardants include phosphorus-based, nitrogen-based, and intumescent flame retardants. However, the flame retardant efficiency of existing halogen-free flame retardants is generally low, and a relatively high addition amount is usually required to achieve the desired flame retardant effect. The large addition of halogen-free flame retardants not only leads to higher production costs for polypropylene composites, but also inevitably causes a significant decrease in the mechanical properties of polypropylene composites due to the poor dispersibility of halogen-free flame retardants in the polypropylene matrix.

[0004] Therefore, it is of great significance to develop a halogen-free flame-retardant polypropylene composite material that combines excellent flame retardant properties, excellent mechanical properties, and excellent ablation resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a ceramizable halogen-free flame-retardant polypropylene composite material, its preparation method, and its application.

[0006] The technical solution adopted in this invention is: A ceramizable halogen-free flame-retardant polypropylene composite material comprising the following components by weight percentage: Polypropylene: 65%–75%; Layered magnesium-aluminum bimetallic hydroxide immobilized with platinum: 3%–10%; Ammonium polyphosphate: 5%–15%; Charcoal-forming agent: 1%–10%; Anti-dripping agent: 0.2%–5%; Antioxidant: 0.5%–2%; Compatibilizer: 3%–10%; Ceramic filler: 1%–5%; Layered nanofillers: 0.5%–5%; Hindered amines: 0.1%–1%.

[0007] Preferably, the polypropylene has a number-average molecular weight of 230,000 g / mol to 240,000 g / mol, a melt index of 4 g / 10 min to 5 g / 10 min, and melt index test conditions of 230℃ / 2.16 kg.

[0008] Preferably, the platinum-supported layered magnesium-aluminum bimetallic hydroxide comprises a carrier layered magnesium-aluminum bimetallic hydroxide and loaded platinum nanoparticles.

[0009] Preferably, the particle size of the platinum nanoparticles is 3nm to 5nm.

[0010] Preferably, the platinum nanoparticles in the layered magnesium-aluminum bimetallic hydroxide contain 0.1% to 5% by mass.

[0011] Preferably, the layered magnesium-aluminum bimetallic hydroxide immobilized platinum is prepared by a method comprising the following steps: a) Prepare aqueous solutions of magnesium salts and aluminum salts, sodium hydroxide and sodium carbonate, and chloroplatinic acid; b) Add the magnesium salt-aluminum salt aqueous solution and the sodium hydroxide-sodium carbonate aqueous solution to the chloroplatinic acid aqueous solution, then carry out a hydrothermal reaction, and then separate, purify and dry the product to obtain layered magnesium-aluminum bimetallic hydroxide supported on platinum.

[0012] Preferably, the magnesium salt-aluminum salt aqueous solution in step a) is prepared from the following raw materials in parts by weight: Magnesium nitrate hexahydrate: 50-60 parts; Aluminum nitrate nonahydrate: 20-30 parts; Water: 200 to 250 parts.

[0013] Preferably, the sodium hydroxide-sodium carbonate aqueous solution in step a) is prepared from the following raw materials in parts by weight: Sodium hydroxide: 10 to 20 parts; Sodium carbonate: 15 to 25 parts; Water: 200 to 250 parts.

[0014] Preferably, the chloroplatinic acid aqueous solution in step a) is prepared from the following raw materials in parts by weight: Chloroplatinic acid hexahydrate: 0.8 parts to 1.5 parts; Water: 200 to 250 parts.

[0015] Preferably, the hydrothermal reaction in step b) is carried out at a temperature of 170℃ to 190℃ for a reaction time of 20h to 30h.

[0016] Preferably, the charring agent is at least one of pentaerythritol, dipentaerythritol, and poly(2-ethanolamino-4,6-ethylenediamino-1,3,5-triazine).

[0017] Preferably, the anti-dripping agent is at least one of polytetrafluoroethylene, polysiloxane, talc, and organomontmorillonite.

[0018] Preferably, the antioxidant is antioxidant 1010 or antioxidant 168.

[0019] Preferably, the compatibilizer is at least one of maleic anhydride-grafted polypropylene elastomer, methyl methacrylate-butadiene-styrene terpolymer, liquid acrylate rubber, and liquid polybutadiene rubber.

[0020] Preferably, the ceramic filler is at least one of fluorophlogopite, alumina, silica, and zinc borate.

[0021] Preferably, the layered nanofiller is at least one of layered bimetallic hydroxide, layered nano-zirconium phosphate, acidic montmorillonite, and layered niobate.

[0022] Preferably, the hindered amine is at least one of tetramethylpiperidinamine, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and bis(2,2,6,6-tetramethyl-4-piperidinyl) adipate.

[0023] A method for preparing a ceramizable halogen-free flame-retardant polypropylene composite material as described above includes the following steps: 1) Polypropylene, layered magnesium-aluminum bimetallic hydroxide supported platinum, ammonium polyphosphate, charring agent, anti-dripping agent, antioxidant, compatibilizer, ceramic filler, layered nanofiller and hindered amine are added to a high-speed mixer and mixed evenly to obtain a mixture. 2) The mixture is added to a twin-screw extruder for melt extrusion and granulation to obtain a ceramizable halogen-free flame-retardant polypropylene composite material.

[0024] Preferably, the process parameters for melt extrusion in step 2) include: processing temperature of 170℃~230℃, die head temperature of 210℃~230℃, screw speed of 200r / min~250r / min, and screw feeding speed of 2r / min~5r / min.

[0025] Applications of a ceramicizable halogen-free flame-retardant polypropylene composite material as described above in the fields of electronics, automotive, or building materials.

[0026] The beneficial effects of this invention are: the ceramicizable halogen-free flame-retardant polypropylene composite material of this invention has excellent flame retardant properties, excellent mechanical properties and excellent ablation resistance, and is suitable for use in the fields of electronics, automobiles, building materials, etc. Moreover, its preparation method is simple and the production cost is low, making it suitable for large-scale industrial production and application.

[0027] Specifically: 1) The halogen-free flame-retardant polypropylene composite material of the present invention contains layered magnesium-aluminum bimetallic hydroxide immobilized platinum (the layered magnesium-aluminum bimetallic hydroxide is used as a carrier to immobilize highly dispersed platinum nanoparticles. The strong interaction between the layered bimetallic hydroxide and the platinum nanoparticles can not only achieve uniform dispersion and stable anchoring of platinum species, thereby effectively inhibiting its high-temperature sintering, but also improve the catalytic char formation efficiency through synergistic effect). It utilizes this to construct a multifunctional flame-retardant system with catalytic char formation, free radical regulation and high-temperature ceramization functions, so that the polypropylene composite material can exhibit a unique "catalytic-barrier-self-extinguishing" triple synergistic flame-retardant mechanism when facing the severe challenges of dangerous high temperature or open flame. 2) The ceramizable halogen-free flame-retardant polypropylene composite material of the present invention contains layered magnesium-aluminum bimetallic hydroxide immobilized with platinum and ammonium polyphosphate. Under high temperature conditions (>400℃), the layered magnesium-aluminum bimetallic hydroxide transforms into a magnesium-aluminum mixed oxide with high specific surface area and strong Lewis acidity. This active phase and the ammonium polyphosphate in the system can undergo a deep synergistic effect: on the one hand, the magnesium-aluminum mixed oxide can catalyze the esterification and dehydration crosslinking reaction of ammonium polyphosphate, accelerating the formation of a dense carbon layer rich in aromatic structures; on the other hand, platinum nanoparticles further catalyze the graphitization of the carbon layer, improving its thermal stability and mechanical strength. As the temperature continues to rise to 600℃~900℃, the carbon layer undergoes an in-situ ceramization transformation—Mg 2+ Al 3+ It reacts with phosphate to form a high-melting-point magnesium aluminum phosphate ceramic phase, which then, together with the residual carbon skeleton, constructs a continuous, dense, and high-strength inorganic-organic hybrid ceramic barrier layer. This ceramic barrier layer has extremely low thermal conductivity and excellent oxidation resistance, which can effectively isolate external heat from being transferred inward, while preventing the escape of internal combustible pyrolysis products and the diffusion of oxygen, thus fundamentally cutting off the cycle of the three elements of combustion. 3) This invention constructs a catalytic system based on layered magnesium-aluminum bimetallic hydroxide loaded with highly dispersed platinum nanoparticles, forming a flame-retardant system that combines high-temperature ceramicization and high-efficiency heat insulation. When encountering extreme high temperatures caused by battery thermal runaway or external flame attack, it can generate a continuous, dense, and high-strength ceramicized protective layer in situ. It has a triple synergistic mechanism of catalytic carbonization, barrier heat insulation, and self-extinguishing protection, which can effectively resist flame erosion and thermal corrosion, thereby maintaining the structural integrity of the battery shell and preventing heat spread. Detailed Implementation

[0028] The present invention will be further explained and described below with reference to specific embodiments.

[0029] The sources and main parameters of some of the raw materials used in Examples 1-9 and Comparative Examples 1-4 are as follows: Polypropylene: ExxonMobil Chemical Co., Ltd., grade PP7032E2, number average molecular weight 230000 g / mol, melt index 4 g / 10 min, melt index test conditions 230℃ / 2.16 kg.

[0030] Ammonium polyphosphate: Qingyuan Pusefur Phosphate Chemical Co., Ltd., brand name EPFR-APP216, number average molecular weight is 147g / mol.

[0031] Poly(2-ethanolamino-4,6-ethylenediamino-1,3,5-triazine): Guangzhou Xijia New Materials Co., Ltd., brand name CFA935, number average molecular weight is 400 g / mol.

[0032] Polytetrafluoroethylene (PTFE): Guangzhou Yinyuan New Material Co., Ltd., brand name FR-PT105, number average molecular weight is 250,000 g / mol.

[0033] Antioxidant 1010 and Antioxidant 168: BASF, Germany.

[0034] Maleic anhydride-grafted polyolefin elastomer: ExxonMobil Chemical Co., Ltd., brand name PO 1015, number average molecular weight of 60,000 g / mol, maleic anhydride grafting rate of 1%.

[0035] Fluorophyllite: Guangdong Sanbao New Material Technology Co., Ltd., grade B525, in flake form, with a flake diameter of 5μm to 10μm.

[0036] Layered nano-zirconium phosphate: Jinda Nanotechnology (Xiamen) Co., Ltd., in sheet form, with a sheet diameter of 0.2μm to 2μm.

[0037] Melamine polyurethane: Qingyuan Pusefur Phosphate Chemical Co., Ltd., with a number-average molecular weight of 255 g / mol.

[0038] Example 1: A layered magnesium-aluminum bimetallic hydroxide immobilized with platinum is prepared by the following method: a) 57 parts by mass of magnesium nitrate hexahydrate and 28 parts by mass of aluminum nitrate nonahydrate were stirred and dispersed in 250 parts by mass of deionized water to obtain a magnesium salt-aluminum salt aqueous solution; 19 parts by mass of sodium hydroxide and 23 parts by mass of sodium carbonate were stirred and dispersed in 250 parts by mass of deionized water to obtain a sodium hydroxide-sodium carbonate aqueous solution; 1 part by mass of chloroplatinic acid hexahydrate was stirred and dispersed in 250 parts by mass of deionized water to obtain a chloroplatinic acid aqueous solution. b) Magnesium salt-aluminum salt aqueous solution and sodium hydroxide-sodium carbonate aqueous solution were simultaneously added dropwise to chloroplatinic acid aqueous solution under stirring. After the addition was complete, the mixture was stirred vigorously for 20 min, then transferred to a hydrothermal synthesis reactor and reacted at 180℃ for 24 h. After naturally cooling to room temperature, the mixture was filtered, and the solid was washed with water, then vacuum dried and pulverized to obtain layered magnesium-aluminum bimetallic hydroxide immobilized platinum (the particle size of platinum nanoparticles was 3 nm to 5 nm, and the mass percentage of platinum nanoparticles was 2%).

[0039] A halogen-free flame-retardant polypropylene composite material that can be ceramized has the following composition as shown in the table below: Table 1. Composition of a halogen-free flame-retardant polypropylene composite material that can be ceramicized.

[0040] The preparation method of the above-mentioned ceramizable halogen-free flame-retardant polypropylene composite material is as follows: 1) Polypropylene, layered magnesium aluminum bimetallic hydroxide-supported platinum, ammonium polyphosphate, poly2-ethanolamino-4,6-ethylenediamino-1,3,5-triazine, polytetrafluoroethylene, antioxidant 1010, antioxidant 168, maleic anhydride-grafted polyolefin elastomer, fluorophlogopite, layered nano-zirconium phosphate, and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate are added to a high-speed mixer and mixed evenly to obtain a mixture; 2) The mixture is added to a twin-screw extruder for melt extrusion and granulation. The temperatures of zones 1 to 9 of the twin-screw extruder from the feeding section are 180℃, 185℃, 185℃, 190℃, 190℃, 195℃, 200℃, 205℃ and 210℃ respectively. The die head temperature is 210℃, the screw speed is 250r / min and the screw feeding speed is 5r / min, to obtain a ceramizable halogen-free flame-retardant polypropylene composite material.

[0041] Example 2: A halogen-free flame-retardant polypropylene composite material that can be ceramized has the following composition as shown in the table below: Table 2. Composition of a halogen-free flame-retardant polypropylene composite material that can be ceramicized.

[0042] Note: The preparation method of the above-mentioned ceramizable halogen-free flame-retardant polypropylene composite material is the same as that in Example 1.

[0043] Example 3: A halogen-free flame-retardant polypropylene composite material that can be ceramized has the following composition as shown in the table below: Table 3. Composition of a halogen-free flame-retardant polypropylene composite material that can be ceramicized.

[0044] Note: The preparation method of the above-mentioned ceramizable halogen-free flame-retardant polypropylene composite material is the same as that in Example 1.

[0045] Example 4: A halogen-free flame-retardant polypropylene composite material that can be ceramized has the following composition as shown in the table below: Table 4. Composition of a halogen-free flame-retardant polypropylene composite material that can be ceramicized.

[0046] Note: The preparation method of the above-mentioned ceramizable halogen-free flame-retardant polypropylene composite material is the same as that in Example 1.

[0047] Example 5: A halogen-free flame-retardant polypropylene composite material that can be ceramized has the following composition as shown in the table below: Table 5. Composition of a halogen-free flame-retardant polypropylene composite material that can be ceramicized.

[0048] Note: The preparation method of the above-mentioned ceramizable halogen-free flame-retardant polypropylene composite material is the same as that in Example 1.

[0049] Example 6: A halogen-free flame-retardant polypropylene composite material that can be ceramized has the following composition as shown in the table below: Table 6. Composition of a halogen-free flame-retardant polypropylene composite material that can be ceramicized.

[0050] Note: The preparation method of the above-mentioned ceramizable halogen-free flame-retardant polypropylene composite material is the same as that in Example 1.

[0051] Example 7: A halogen-free flame-retardant polypropylene composite material that can be ceramized has the following composition as shown in the table below: Table 7 Composition of a halogen-free flame-retardant polypropylene composite material that can be ceramicized

[0052] Note: The preparation method of the above-mentioned ceramizable halogen-free flame-retardant polypropylene composite material is the same as that in Example 1.

[0053] Example 8: A halogen-free flame-retardant polypropylene composite material that can be ceramized has the following composition as shown in the table below: Table 8. Composition of a halogen-free flame-retardant polypropylene composite material that can be ceramicized.

[0054] Note: The preparation method of the above-mentioned ceramizable halogen-free flame-retardant polypropylene composite material is the same as that in Example 1.

[0055] Example 9: A halogen-free flame-retardant polypropylene composite material that can be ceramized has the following composition as shown in the table below: Table 9. Composition of a halogen-free flame-retardant polypropylene composite material that can be ceramicized.

[0056] Note: The preparation method of the above-mentioned ceramizable halogen-free flame-retardant polypropylene composite material is the same as that in Example 1.

[0057] Comparative Example 1: Thermoplastic polypropylene elastomer: ExxonMobil Chemical Co., Ltd., grade PP7032E2, number average molecular weight 230,000 g / mol, melt index 4 g / 10 min, melt index test conditions 230℃ / 2.16 kg.

[0058] Comparative Example 2: A halogen-free flame-retardant polypropylene composite material, the composition of which is shown in the table below: Table 10 Composition of a halogen-free flame-retardant polypropylene composite material

[0059] The preparation method of the above-mentioned halogen-free flame-retardant polypropylene composite material is as follows: 1) Polypropylene, ammonium polyphosphate, melamine polyurate, pentaerythritol, polytetrafluoroethylene, antioxidant 1010, antioxidant 168, maleic anhydride-grafted polyolefin elastomer, fluorophlogopite, layered nano-zirconium phosphate and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate are added to a high-speed mixer and mixed evenly to obtain a mixture; 2) The mixture is added to a twin-screw extruder for melt extrusion and granulation. The temperatures of zones 1 to 9 of the twin-screw extruder from the feeding section are 180℃, 185℃, 185℃, 190℃, 190℃, 195℃, 200℃, 205℃ and 210℃ respectively. The die head temperature is 210℃, the screw speed is 250r / min and the screw feeding speed is 5r / min, to obtain halogen-free flame-retardant polypropylene composite material.

[0060] Comparative Example 3: A halogen-free flame-retardant polypropylene composite material is identical to the ceramicizable halogen-free flame-retardant polypropylene composite material of Example 1, except that the amount of layered magnesium aluminum bimetallic hydroxide-supported platinum is adjusted from "5%" to "0" (i.e., platinum is not supported by layered magnesium aluminum bimetallic hydroxide) and the amount of poly(2-ethanolamine-4,6-ethylenediamine-1,3,5-triazine) is adjusted from "5%" to "10%".

[0061] Comparative Example 4: A halogen-free flame-retardant polypropylene composite material is identical to the ceramicizable halogen-free flame-retardant polypropylene composite material of Example 1, except that the amount of fluorophlogopite is adjusted from "3%" to "0" (i.e., fluorophlogopite is not present) and the amount of layered nano-zirconium phosphate is adjusted from "0.5%" to "3.5%".

[0062] Performance testing: The mechanical and flame retardant properties of the ceramizable halogen-free flame-retardant polypropylene composites of Examples 1-9, the thermoplastic polypropylene elastomer of Comparative Example 1, and the halogen-free flame-retardant polypropylene composites of Comparative Examples 2-4 are shown in the table below: Table 11 Test results of mechanical properties and flame retardant properties

[0063] Note: Tensile strength and elongation at break: The test was conducted in accordance with "GB / T 1040.3-2006 Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets". The specimen was strip-shaped, with a length of 120 mm and a width of 10 mm. The clamping length of the specimen was 100 mm. The stretching method was constant elongation, and the stretching speed was 20 mm / min.

[0064] Bending strength: The test was conducted in accordance with "GB / T 9341-2008 Determination of bending properties of plastics". A standard injection-molded 80mm×10mm×4mm specimen was used. The test was conducted under three-point bending conditions with a span of 64mm and a loading speed of 2mm / min. The maximum load at which the specimen broke or reached the specified strain was recorded and the bending strength was calculated.

[0065] Notched impact strength: Tested according to "ISO180 / 179 standard", with a sample size of 80mm×10mm×4mm and a notch of 2mm. Six samples were tested in each group and the average value was taken.

[0066] Limiting Oxygen Index (LOI): Tested according to "ASTM D2863 standard", with a sample size of 120mm × 6.5mm × 3mm.

[0067] Flame retardancy rating: Vertical burning test was conducted according to the “UL-94 standard”, with sample size of 127mm×12.7mm×3.2mm.

[0068] As shown in Table 11: a) The halogen-free flame-retardant polypropylene composites of Examples 1 to 9 all achieved the UL-94V-0 flame retardant rating, with no burning drips, and the LOI was stable between 32.1% and 32.9%. Moreover, their mechanical properties were very similar to those of thermoplastic polypropylene elastomer (Comparative Example 1), demonstrating both excellent flame retardant properties and excellent mechanical properties. (b) The ceramizable halogen-free flame-retardant polypropylene composites of Examples 5 and 7 exhibit superior overall performance. The ceramizable halogen-free flame-retardant polypropylene composite of Example 7 achieved the highest LOI (32.9%) among all samples, while maintaining a tensile strength of 25.2 MPa and a tensile strength of 11.9 kJ / m². 2 The notched impact strength indicates that the synergy between catalytic carbonization and the ceramicized framework is optimal under this ratio, forming the densest barrier layer. The ceramicizable halogen-free flame-retardant polypropylene composite material of Example 5 is slightly better in terms of mechanical strength, and its LOI is also as high as 32.5%. c) Compared with the thermoplastic polypropylene elastomer (polypropylene elastomer without any additives) of Comparative Example 1, the ceramizable halogen-free flame-retardant polypropylene composite materials of Examples 1-9 achieved excellent flame-retardant properties without a significant decrease in mechanical strength, and ultimately demonstrated excellent comprehensive performance. d) The thermoplastic polypropylene elastomer (pure PP) of Comparative Example 1 exhibited the highest notched impact strength (49.3 kJ / m). 2 The intrinsic properties of the unfilled elastomer are high (165.5%) and low elongation at break (165.5%). After introducing approximately 30%–35% flame-retardant filler, the impact strength of the ceramizable halogen-free flame-retardant polypropylene composites in Examples 1–9 decreased to 11.1 kJ / m². 2 ~12.9kJ / m 2 This range is normal for highly filled composite materials, mainly due to stress concentration caused by rigid particles. However, it is noteworthy that the impact strengths of the ceramizable halogen-free flame-retardant polypropylene composites of Examples 2 and 5 reached 12.9 kJ / m². 2 and 12.5kJ / m 2Furthermore, the tensile strength remained above 25 MPa, which was superior to the halogen-free flame-retardant polypropylene composites of Comparative Examples 2-4. This indicates that the introduction of layered magnesium-aluminum bimetallic hydroxide-supported platinum and layered nano-zirconium phosphate improved the interfacial compatibility between the filler and the PP matrix to a certain extent, and alleviated the damage to the toughness of the PP matrix caused by the rigid filler. In particular, the presence of maleic anhydride-grafted polypropylene elastomer further ensured that the polypropylene composite material maintained high rigidity while still possessing the toughness required for engineering applications (i.e., elongation at break > 120%). e) The halogen-free flame-retardant polypropylene composite material of Comparative Example 2 uses a traditional intumescent flame retardant system (ammonium polyphosphate / pentaerythritol / melamine cyanurate), with an LOI of only 29.0% and a flame retardant rating that does not reach UL-94 V-0. It is also accompanied by dripping. This indicates that the synergistic effect of poly(2-ethanolamine-4,6-ethylenediamine-1,3,5-triazine) charring agent and layered magnesium aluminum bimetallic hydroxide-supported platinum (the platinum component in the layered magnesium aluminum bimetallic hydroxide-supported platinum catalyzes the dehydrogenation crosslinking reaction of polypropylene during combustion, promoting the formation of a high-quality graphitized carbon layer, while the triazine macromolecular charring agent provides a more stable carbon source. The combination of the two effectively solves the pain point of easy melting and dripping of traditional flame-retardant PP and achieves a true ceramic barrier effect) is significantly better than that of traditional small molecule charring agents. f) Compared to the ceramizable halogen-free flame-retardant polypropylene composite material of Example 1, the halogen-free flame-retardant polypropylene composite material of Comparative Example 3 (without layered magnesium-aluminum bimetallic hydroxide-supported platinum) still achieves a flame retardant rating of UL-94. The V-0 rating was achieved, but the LOI decreased from 32.1% to 29.0%, indicating that the layered magnesium-aluminum bimetallic hydroxide-supported platinum played a key catalytic enhancement role in improving flame retardant efficiency and carbon layer density. It can significantly improve the flame resistance of polypropylene composites in oxygen-rich environments. Compared with the ceramicizable halogen-free flame-retardant polypropylene composite of Example 1, the LOI of the halogen-free flame-retardant polypropylene composite of Comparative Example 4 (without fluorophlogopite) further decreased to 28.3%, confirming the core position of fluorophlogopite as a ceramic skeleton (at high temperatures, the mica sheets are not only heat-resistant themselves, but can also interweave with zirconium phosphate and catalytic carbon layers to form a ceramic-like hard protective layer, physically blocking the transfer of heat and oxygen). It can be seen that there is a significant positive synergistic effect between the layered magnesium-aluminum bimetallic hydroxide-supported platinum and fluorophlogopite. Both are indispensable and together they construct a high-strength ceramic barrier layer, which is the key microscopic mechanism for achieving high LOI and no dripping.

[0069] In summary, the ceramicizable halogen-free flame-retardant polypropylene composite material of the present invention has a high flame retardant rating (UL-94V-0), a high oxygen index (LOI>32%), and good mechanical processing properties. It solves the technical bottleneck of traditional halogen-free flame-retardant polypropylene composite materials, which have difficulty in exceeding 30% LOI and are prone to dripping. It has a very broad prospect for industrial application.

[0070] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A ceramizable halogen-free flame-retardant polypropylene composite material, characterized in that, Includes the following components by mass percentage: Polypropylene: 65%–75%; Layered magnesium-aluminum bimetallic hydroxide immobilized with platinum: 3%–10%; Ammonium polyphosphate: 5%–15%; Charcoal-forming agent: 1%–10%; Anti-dripping agent: 0.2%–5%; Antioxidant: 0.5%–2%; Compatibilizer: 3%–10%; Ceramic filler: 1%–5%; Layered nanofillers: 0.5%–5%; Hindered amines: 0.1%–1%.

2. The ceramizable halogen-free flame-retardant polypropylene composite material according to claim 1, characterized in that: The polypropylene has a number-average molecular weight of 230,000 g / mol to 240,000 g / mol, a melt index of 4 g / 10 min to 5 g / 10 min, and a melt index test condition of 230℃ / 2.16 kg.

3. The ceramizable halogen-free flame-retardant polypropylene composite material according to claim 1, characterized in that: The platinum-supported layered magnesium-aluminum bimetallic hydroxide consists of a carrier layered magnesium-aluminum bimetallic hydroxide and loaded platinum nanoparticles.

4. The ceramizable halogen-free flame-retardant polypropylene composite material according to claim 3, characterized in that: The layered magnesium-aluminum bimetallic hydroxide immobilized platinum is prepared by a method including the following steps: a) Prepare aqueous solutions of magnesium salts and aluminum salts, sodium hydroxide and sodium carbonate, and chloroplatinic acid; b) Add the magnesium salt-aluminum salt aqueous solution and the sodium hydroxide-sodium carbonate aqueous solution to the chloroplatinic acid aqueous solution, then carry out a hydrothermal reaction, and then separate, purify and dry the product to obtain layered magnesium-aluminum bimetallic hydroxide supported on platinum.

5. The ceramizable halogen-free flame-retardant polypropylene composite material according to any one of claims 1 to 4, characterized in that: The charring agent is at least one of pentaerythritol, dipentaerythritol, and poly(2-ethanolamino-4,6-ethylenediamino-1,3,5-triazine).

6. The ceramizable halogen-free flame-retardant polypropylene composite material according to any one of claims 1 to 4, characterized in that: The anti-dripping agent is at least one of polytetrafluoroethylene, polysiloxane, talc, and organomontmorillonite; and / or, the antioxidant is antioxidant 1010 and antioxidant 168; and / or, the compatibilizer is at least one of maleic anhydride-grafted polypropylene elastomer, methyl methacrylate-butadiene-styrene terpolymer, liquid acrylate rubber, and liquid polybutadiene rubber.

7. The ceramizable halogen-free flame-retardant polypropylene composite material according to any one of claims 1 to 4, characterized in that: The ceramic filler is at least one of fluorophlogopite, alumina, silica, and zinc borate; and / or, the layered nanofiller is at least one of layered bimetallic hydroxide, layered nano-zirconium phosphate, acidic montmorillonite, and layered niobate.

8. The ceramizable halogen-free flame-retardant polypropylene composite material according to any one of claims 1 to 4, characterized in that: The hindered amine is at least one of tetramethylpiperidinamine, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, and bis(2,2,6,6-tetramethyl-4-piperidinyl) adipate.

9. A method for preparing a ceramizable halogen-free flame-retardant polypropylene composite material as described in any one of claims 1 to 8, characterized in that, Includes the following steps: 1) Polypropylene, layered magnesium-aluminum bimetallic hydroxide supported platinum, ammonium polyphosphate, charring agent, anti-dripping agent, antioxidant, compatibilizer, ceramic filler, layered nanofiller and hindered amine are added to a high-speed mixer and mixed evenly to obtain a mixture. 2) The mixture is added to a twin-screw extruder for melt extrusion and granulation to obtain a ceramizable halogen-free flame-retardant polypropylene composite material.

10. The application of a ceramizable halogen-free flame-retardant polypropylene composite material as described in any one of claims 1 to 8 in the fields of electronics, automotive, or building materials.

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