Flame-retardant continuous glass fiber-reinforced thermoplastic material and method for its production and use

Abstract

This invention discloses a flame-retardant continuous glass fiber reinforced thermoplastic material, its preparation method, and its application. The flame-retardant continuous glass fiber reinforced thermoplastic material, by weight, comprises the following components: 39-76 parts polypropylene; 45-80 parts surface-modified continuous glass fiber; 2-5 parts compatibilizer; 8-35 parts ceramic filler; 10-35 parts piperazine flame retardant; 2.5-6 parts nitrogen- and / or phosphorus-containing flame retardant; and 0.5-3.5 parts flame retardant synergist. The surface-modified continuous glass fiber is coated with low-melting-point glass powder, which accounts for 0.2-3 wt% of the surface-modified continuous glass fiber. This invention, by modifying the continuous glass fiber with low-melting-point glass powder, facilitates the formation of bonding sites on the surface of the continuous glass fiber, preventing gas and carbon sources during combustion from damaging the integrity of the ceramic structure. This solves the defects of flame-retardant materials in the field, such as easy collapse and burn-through during high-temperature burning, which prevent uncontrollable flame spread. Simultaneously, it also improves the adhesion to injection-molded structures of metal parts.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a flame-retardant glass fiber reinforced thermoplastic material, its preparation method, and its application. Background Technology

[0002] Continuous glass fiber reinforced polypropylene (LFT-PP) possesses high strength, high rigidity, excellent impact resistance and creep resistance, while also exhibiting low density, low warpage, and outstanding dimensional stability. By forming a three-dimensional network structure within the matrix using continuous glass fibers (length > 3 mm), it significantly improves mechanical properties (strength increased by more than 20% compared to traditional short glass fibers) and achieves weight reduction of 20-50%. However, it has inherent drawbacks such as low surface hardness, flammability (oxygen index 17.4%), and poor compatibility with glass fiber interfaces. LFT-PP is primarily used in lightweight automotive structural components (such as front-end modules, tailgate inner panels, battery trays, etc.), high-load-bearing components in home appliances (such as washing machine drums, air conditioner fan impellers), and functional electronic components (such as 5G base station antenna covers, electrical control boxes). It is gradually replacing metals and engineering plastics (such as nylon) to reduce costs, and its applications are expanding into military packaging, energy storage equipment housings, and other fields. In recent years, the application of LFT-PP in new energy vehicles has gradually increased. With the increasing safety requirements of the three-electric systems (battery, motor, and electronic control system) in new energy vehicles, key components such as battery pack covers and control boxes are required to simultaneously meet UL94 5VA flame retardant rating and GB / T31467.3-2015 ablation resistance test (no burn-through, no collapse). While traditional metals or thermosetting materials are ablation resistant, they suffer from high density, slow processing, and non-recyclability. Conventional polypropylene (PP) has an oxygen index of only 17.5, making it highly flammable and prone to severe dripping, hindering its direct application. Currently, the industry is attempting to improve the ablation resistance of PP by compounding it with halogen-free piperazine, phosphorus-nitrogen intumescent flame retardants, continuous glass fiber, and ceramic fillers. However, these methods still result in easy burn-through in thin-walled, lightweight applications. While thermosetting systems can form a stable char layer, they introduce environmental problems such as high smoke toxicity, poor toughness, and non-recyclability. CN118620324A discloses a halogen-free, ablation-resistant polypropylene resin composition, which uses a specific amount of piperazine flame retardant, nitrogen-phosphorus composite flame retardant, synergistic flame retardant, and specific long glass fibers to form a compound. The resulting composition is particularly suitable for preparing thin-walled polypropylene materials, improving the burn-through resistance, heat insulation performance, and flame retardant performance of thin-walled polypropylene materials; achieving continuous burning at 1000°C for 10 minutes without burn-through, and with a backplate temperature below 255°C.

[0003] CN119241944A discloses a halogen-free flame-retardant and ablation-resistant polypropylene composite material, its preparation method, and its application. This halogen-free flame-retardant and ablation-resistant polypropylene composite material, through the composite of PPE resin in a halogen-free flame-retardant system and compounding with long glass fiber masterbatch, effectively improves the material's flame-retardant, heat-insulating, and ablation-resistant properties under the synergistic effect of the halogen-free flame retardant. The halogen-free flame-retardant system consists of piperazine-based substances and ammonium phosphate salts, and also employs surface-modified ultrafine aluminum hydroxide, specifically treated with coupling agents, crosslinking agents, and melamine. This invention achieves continuous burning at 1300℃ for 10 minutes without burn-through, and the backplate temperature remains below 150℃.

[0004] CN119899455A discloses a long glass fiber reinforced flame-retardant ceramicized polypropylene material and its preparation method. It comprises the following components in parts by weight: 0-20 parts polypropylene, 30-60 parts flame-retardant long glass fiber masterbatch, and 40-70 parts ceramicized masterbatch. By selecting multi-gradient melting point glass powder, phosphorus-based flame retardant, tetraneedle-shaped zinc oxide whiskers, long glass fibers, and ceramic-forming fillers (one or more selected from kaolin, talc, mica, and wollastonite), the material maintains a dense carbon layer structure with high structural strength during combustion, resisting flame pressure without breakage. The interlayer structure blocks thermal conductivity, significantly reducing the back-side temperature and preventing softening and collapse. It achieves continuous burning at 1200℃ for 10 minutes without burn-through, and the back-side temperature does not exceed 370℃.

[0005] CN114369311B discloses a brominated ablation-resistant flame-retardant polypropylene material and its preparation and application, comprising the following components in parts by weight: 20-55 parts polypropylene, 14-20 parts brominated flame retardant, 3-8 parts synergistic flame retardant, 12-20 parts inorganic flame retardant, 15-30 parts long glass fiber masterbatch, 3-6 parts flux, and 2.4-7 parts other additives. This brominated ablation-resistant flame-retardant polypropylene material, by employing specific inorganic flame retardants, long glass fibers, and flux in combination with brominated flame retardants, achieves a significant improvement in the ablation resistance of polypropylene materials without affecting their flame-retardant properties. The flux is low-melting-point glass powder; the inorganic flame retardant is magnesium hydroxide with an average particle size of 2-10 μm.

[0006] Flame-retardant modification of materials can achieve self-extinguishing upon removal of the flame, suppress smoke generation, and reduce smoke toxicity. However, when exposed to high-temperature flames such as in battery fires, prolonged exposure can easily lead to structural collapse or burn-through, causing the flames to spread to surrounding areas. With increasing market demands for fire resistance, materials must withstand butane flames at 1400℃ for 20 minutes without burn-through or collapse. On the other hand, lightweight and high-load-bearing components still require necessary metal parts to ensure structural load-bearing capacity, assembly reliability, and connection reliability through creep resistance, fatigue resistance, and ductility. These are typically bonded to LFT-PP using insert injection molding or thermoforming welding. However, the poor adhesion between polypropylene composites and metal parts easily leads to interface detachment. None of the aforementioned patents address the adhesion issue between polypropylene composites and metal parts. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned defects and provide a flame-retardant, continuous glass fiber reinforced thermoplastic material that does not collapse or burn through at high temperatures, as well as its preparation method and application.

[0008] This invention is achieved through the following technical solution:

[0009] A flame-retardant continuous glass fiber reinforced thermoplastic material, comprising the following components by weight:

[0010] 39-76 parts of polypropylene;

[0011] 45-80 parts of surface-modified continuous glass fiber;

[0012] 2-5 parts compatibilizer;

[0013] 8-35 parts of ceramic filler;

[0014] 10-35 parts of piperazine flame retardant;

[0015] Contains 2.5-6 parts of nitrogen and / or phosphorus-based flame retardants;

[0016] 0.5-3.5 parts of flame retardant synergist;

[0017] The surface-modified continuous glass fiber is coated with low-melting-point glass powder, which accounts for 0.2-3 wt% of the surface-modified continuous glass fiber.

[0018] The melting point of the low-melting-point glass powder is 450-1000℃.

[0019] In the flame-retardant continuous glass fiber reinforced thermoplastic material of the present invention, the content of polypropylene can be any value or a range between 39 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, and 76 parts; the content of surface-modified continuous glass fiber can be any value or a range between 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, and 80 parts; the content of compatibilizer can be any value or a range between 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, and 5 parts; and the content of ceramic filler can be 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 2 The content of piperazine flame retardant can be any value from 9, 30, 31, 32, 33, 34, or 35 parts, or a range between two values; the content of piperazine flame retardant can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, or 32 parts. The content of nitrogen- and / or phosphorus-based flame retardants can be any of 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6 parts, or a range between the two; the content of flame retardant synergists can be any of 0.5, 1, 1.5, 2, 2.5, 3, or 3.5 parts, or a range between the two.

[0020] The weight percentage of low-melting-point glass powder in surface-modified continuous glass fibers can be any value or a range between 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2.0 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, and 3.0 wt%.

[0021] The test method for determining the weight percentage of low-melting-point glass powder in surface-modified continuous glass fiber in flame-retardant continuous glass fiber reinforced thermoplastic materials is as follows: The material is dissolved in dichloromethane to fully dissolve polypropylene, then filtered. The filter residue containing glass fiber and glass powder is placed in deionized water and boiled for 15-60 minutes, then filtered again. After thoroughly drying the filter residue, it is placed in a 650-mesh ultrasonic sieve. Ultrasonic action causes the sieve to vibrate at a high frequency (20-40kHz) to prevent glass powder from clogging the mesh. After ultrasonic treatment for 30 minutes, the weight of the glass powder below the sieve is weighed, and its proportion of the total weight of the glass fiber filter residue is calculated to obtain its weight percentage.

[0022] Preferably, the low melting point glass powder accounts for 0.7-1.5 wt% of the surface-modified continuous glass fiber.

[0023] Preferably, the polypropylene is a blend of homopolymer polypropylene and copolymer polypropylene, wherein the copolymer polypropylene accounts for 45-95 wt% of the total weight of polypropylene, more preferably 60-90 wt%.

[0024] The melting point of low melting point glass powder can be any value or a range between 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, and 1000℃.

[0025] Preferably, the melting point of the low-melting-point glass powder is 500-800℃; the melting point is determined by differential scanning calorimetry according to ISO 11357-3:2011.

[0026] The low-melting-point glass powder has an average particle size of 1-20 micrometers. The average particle size of the low-melting-point glass powder is measured using a laser particle size analyzer.

[0027] The compatibilizer is selected from polar monomer-grafted olefin polymers; the polar monomer is selected from at least one of maleic anhydride groups, acrylic acid groups, and acrylate derivative groups; the olefin polymer is selected from at least one of polyethylene, polypropylene, ethylene-α-olefin copolymers, and styrene-butadiene copolymers. The grafting rate ranges from 0.2 wt% to 2 wt%. For maleic anhydride and acrylic acid group grafting, a titration method is used, i.e., saponification with excess alkali solution, followed by back titration with acid solution, and the neutralization amount is calculated to obtain the grafting rate. For acrylate grafting, the sample is hot-pressed into a film, and the carbonyl characteristic peak (≈1730 cm⁻¹) is tested. -1 ) and polymer internal standard peaks (such as 841 cm⁻¹ for PP) -1 The grafting rate is calculated by converting the absorbance ratio of the two light sources using an empirical formula.

[0028] Acrylic ester derivatives may have groups such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, dimethylaminoethyl acrylate, acrylamide, or hexafluorobutyl acrylate.

[0029] Specifically, the compatibilizer is selected from maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted ethylene-α-olefin copolymer, maleic anhydride-grafted styrene-butadiene copolymer, acrylic group-grafted polyethylene, acrylic group-grafted polypropylene, acrylic group-grafted ethylene-α-olefin copolymer, acrylic group-grafted styrene-butadiene copolymer, etc.

[0030] The ceramic-forming filler is selected from at least one of kaolin, talc, mica, wollastonite, sepiolite, and montmorillonite. The average particle size range of the ceramic-forming filler can be 0.2~30 micrometers;

[0031] The piperazine flame retardant is selected from at least one of piperazine phosphate, piperazine pyrophosphate, and piperazine polyphosphate; the nitrogen- and / or phosphorus-containing flame retardant is selected from at least one of ammonium polyphosphate, melamine cyanurate, melamine polyphosphate, triazine charring agent, aluminum hypophosphite, diphenylphosphine-piperazine condensate, and melamine pyrophosphate.

[0032] The flame retardant synergist is selected from at least one of zinc oxide, zinc borate, and sepiolite.

[0033] Based on the weight percentage of the flame-retardant continuous glass fiber reinforced thermoplastic material of the present invention, piperazine flame retardants account for 8-17 wt%, nitrogen- and / or phosphorus-containing flame retardants account for 1.5-4 wt%, and flame retardant synergists account for 0.3-2 wt%.

[0034] The diameter of the continuous glass fiber ranges from 10 to 25 micrometers. The continuous glass fiber can be a continuous round glass fiber or a continuous flat glass fiber.

[0035] The ratio of the major axis diameter of the cross-section of continuous flat glass fiber to the minor axis diameter perpendicular to it is not less than 2, and can be 2-5. The major axis diameter of the cross-section can be 6-40 micrometers.

[0036] The continuous glass fiber contains more than 60% silica by mass.

[0037] Preferably, the surface-modified continuous glass fiber is coated with a coupling agent and flat glass fiber powder.

[0038] Surface-modified continuous glass fibers can be commercially available products or obtained in-house. For example, they can be coated onto the surface of continuous glass fibers using conventional coating methods in the art, thereby achieving the coating of low-melting-point glass powder onto the surface of the continuous glass fibers. For instance, an in-house method could be the spraying method in the art, specifically: Step A, mixing low-melting-point glass powder with an optional coupling agent (the weight ratio of low-melting-point glass powder to coupling agent is 1:0.01-0.2), and treating at 15-40°C for 15-60 minutes; Step B, mixing the above mixture with water, stirring evenly to prepare a 0.2-2wt% suspension, and dispersing evenly (ultrasonic treatment may be performed) to obtain a low-melting-point glass powder suspension; Step C, spraying the low-melting-point glass powder suspension onto the surface of the continuous glass fibers, and drying by baking at a high temperature of 400-500°C to obtain surface-modified continuous glass fibers.

[0039] Surface-modified continuous glass fibers can also be prepared by immersion method. The difference from the above method is that step C is to immerse the continuous glass fibers in a suspension of low-melting-point glass powder so that the low-melting-point glass powder adheres to the surface of the continuous glass fibers.

[0040] You can choose to add 0-0.5 parts of coupling agent according to actual needs, for example, you can add 0.01-0.5 parts of coupling agent.

[0041] The coupling agent is selected from at least one of silane coupling agents, titanate coupling agents, and aluminate coupling agents.

[0042] Silane coupling agents can be selected from aminosilane coupling agents, epoxysilane coupling agents, methoxysilane coupling agents, and vinylsilane coupling agents.

[0043] The titanate coupling agent is selected from at least one of monoalkoxy pyrophosphate type titanate coupling agents, monoalkoxy type titanate coupling agents, coordination type titanate coupling agents, and chelation type titanate coupling agents; specifically, it can be bis(triethanolamine) titanate diisopropyl ester; or optionally, bis(triethanolamine) titanate diisopropyl ester.

[0044] The aluminate coupling agent is selected from at least one of monoalkoxy pyrophosphate type aluminate coupling agents, monoalkoxy type aluminate coupling agents, coordination type aluminate coupling agents, and chelation type aluminate coupling agents.

[0045] You may choose to add 0-2 parts of an additive, such as 0.01-2 parts, depending on the actual needs; the additive is selected from at least one of antioxidants, light stabilizers, and lubricants.

[0046] The antioxidants are hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants. The hindered phenolic antioxidant is selected from one or more of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], (2,4,6-trioxo-1,3,5-triazine-1,3,5(2H,4H,6H)-triyl)trivinyltris[3-(3,5-di-tert-butyl-4-hydroxyphenyl)acrylate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, and 1,3,5-(3,5-di-tert-butyl-4-hydroxybenzyl)-triazine-2,4,6-(1H,3H,5H)-trione. The phosphite antioxidant is tris(2,4-di-tert-butylphenyl) phosphite and / or pentaerythritol di(2,4-di-tert-butylphenyl) phosphite. The thioester antioxidant is bis(octadecyl) thiodipropionate and / or dilauryl thiodipropionate.

[0047] The lubricant may be at least one of fluorosilicone polymer lubricants, stearate lubricants, fatty acid lubricants, and stearate ester lubricants; the stearate lubricant is selected from at least one of calcium stearate, magnesium stearate, and zinc stearate; the fatty acid lubricant is selected from at least one of fatty acids, fatty acid derivatives, and fatty acid esters; and the stearate ester lubricant is selected from pentaerythritol stearate.

[0048] You can also add 0-1 parts of color powder, such as 0.01-1 parts of color powder.

[0049] The preparation method of the flame-retardant continuous glass fiber reinforced thermoplastic material of the present invention includes the following steps: mixing the components other than the surface-modified continuous glass fiber evenly; then adding the mixture to the main feed port of a twin-screw extruder, extruding the molten material into an impregnation die for melt impregnation with the surface-modified continuous glass fiber, cooling, solidifying, and pelletizing to obtain the flame-retardant continuous glass fiber reinforced thermoplastic material. The particle length range is 5-20 mm.

[0050] The application of the flame-retardant continuous glass fiber reinforced thermoplastic material of the present invention is used to prepare flame-retardant parts.

[0051] The present invention has the following beneficial effects:

[0052] This invention modifies continuous glass fibers with low-melting-point glass powder, which facilitates the formation of bonding sites on the glass fiber surface. This synergistic flame-retardant-ceramic formulation of piperazine flame retardants / nitrogen- and / or phosphorus-based flame retardants / flame retardant synergists / ceramic fillers of this invention, especially when combustion occurs, in the early stage of combustion (when the temperature rises to the melting point of the glass powder), a glass melt quickly forms on the surface of the continuous glass fiber to bond the ceramic filler, preventing the gas and carbon sources during the combustion process from destroying the integrity of the ceramic structure. This can solve the defects of flame retardant materials in the field that are prone to collapse and burn-through when burned at high temperatures (1400℃), and the inability to control flame spread.

[0053] Meanwhile, the bonding sites formed by the surface modification of glass fiber help to strengthen the fiber skeleton and resist the detachment of bonding sites from the injection-molded bonding structure of metal parts; on the other hand, the low melting point glass powder is bonded to the surface of glass fiber, changing the surface morphology of glass fiber and inhibiting the ability of traditional fiber surface to induce crystallization, thereby improving the metal bonding force. Detailed Implementation

[0054] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0055] The raw materials for this invention are sourced as follows:

[0056] Homopolymer polypropylene A: 17g / 10min, PP M17HN, Hainan Petrochemical;

[0057] Homopolymer polypropylene B: 32g / 10min, PP 320 powder, Maoming Petrochemical;

[0058] Homopolymer polypropylene C: 55g / 10min, PP H9018H, Lanzhou Petrochemical;

[0059] Copolymer polypropylene A: 9g / 10min, PP M09, Wuhan Petrochemical;

[0060] Copolymer polypropylene B: 25g / 10min, PP EP548R, Zhenhai Petrochemical;

[0061] Copolymer polypropylene C: 35g / 10min, PP K9930H(FP), Guangzhou Petrochemical;

[0062] Continuous circular glass fiber: EDR240-T838D, with a diameter of 17 micrometers, made by Taishan Glass Fiber;

[0063] Continuous flat glass fiber: TFG-1000-T838J, major axis diameter 18 micrometers, minor axis diameter 4 micrometers, Taishan glass fiber;

[0064] Low melting point glass powder A: melting point 400℃, glass glaze 461, Foshan Taoyise Glaze Co., Ltd.;

[0065] Low melting point glass powder B: melting point 450℃, CA450, Guangzhou Geliner New Materials Co., Ltd.;

[0066] Low melting point glass powder C: melting point 520℃, glass glaze 562H, Foshan Taoyise Glaze Co., Ltd.;

[0067] Low melting point glass powder D: melting point is 790℃, glass glaze 9213, Foshan Taoyise Glaze Co., Ltd.;

[0068] Low melting point glass powder E: melting point 900℃, GT90, Guangzhou Goertek New Materials Co., Ltd.;

[0069] The above-mentioned low-melting-point glass powder was screened to obtain raw materials with an average particle size of about 6 micrometers.

[0070] Surface-modified continuous circular glass fiber A-1: ​​low melting point glass powder B, 0.2 wt%, self-made;

[0071] Surface-modified continuous circular glass fiber A-2: low melting point glass powder B accounts for 0.7 wt%, self-made;

[0072] Surface-modified continuous circular glass fiber A-3: low melting point glass powder B, 1.5 wt%, self-made;

[0073] Surface-modified continuous circular glass fiber A-4: low melting point glass powder B accounts for 2.9 wt%, self-made;

[0074] Surface-modified continuous circular glass fiber B: low melting point glass powder C, 1.1 wt%, self-made;

[0075] Surface-modified continuous circular glass fiber C: low melting point glass powder D, 1.1 wt%, self-made;

[0076] Surface-modified continuous circular glass fiber D: low melting point glass powder E, 1.1 wt%, self-made;

[0077] Surface-modified continuous circular glass fiber E: low melting point glass powder A accounts for 1.1 wt%, self-made;

[0078] Surface-modified continuous flat glass fiber: low melting point glass powder B accounts for 1.1 wt%, self-made;

[0079] The method for making surface-modified continuous glass fiber is as follows: Step A, mix low-melting-point glass powder with coupling agent (KH-550) (the weight ratio of low-melting-point glass powder to coupling agent is 1:0.05) evenly, and treat at 30°C for 30 minutes; Step B, mix the above mixture with water, stir evenly, prepare a 1.2wt% suspension solution, and ultrasonically disperse evenly to obtain a low-melting-point glass powder suspension; Step C, spray the low-melting-point glass powder suspension onto the surface of continuous glass fiber, and bake and dry at a high temperature of 400-500°C to obtain surface-modified continuous glass fiber.

[0080] Coupling agent: γ-aminopropyltriethoxysilane, KH-550;

[0081] Compatibilizer A: Maleic anhydride grafted polypropylene: CMG5701, Jia Yi Rong Polymer (Shanghai) Co., Ltd.

[0082] Compatibilizer B: Acrylic group grafted polyethylene: HG540, Jiangxi Weike Oil & Chemical Co., Ltd.;

[0083] Compatibilizer C: Glycidyl methacrylate grafted ethylene-α-olefin copolymer: SOG-03, Jia Yi Rong Polymer (Shanghai) Co., Ltd.;

[0084] Kaolin: Calcined and washed kaolin, purchased from Hebei Huishun Mining Co., Ltd.;

[0085] Piperazine flame retardant A: piperazine phosphate, CAS number 1951-97-9, commercially available;

[0086] Piperazine flame retardant B: piperazine pyrophosphate, CAS number 66034-17-1, commercially available;

[0087] Nitrogen- and / or phosphorus-based flame retardant A: melamine cyanurate, MPP, purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd.;

[0088] Nitrogen- and / or phosphorus-based flame retardant B: aluminum hypophosphite, purchased from Shandong Chenxu New Material Co., Ltd.;

[0089] Zinc oxide: KND-XR30, purchased from Changzhou Kenada New Materials;

[0090] Zinc borate: CAS No. 1332-07-6, Nantong Bona Chemical Technology Co., Ltd.;

[0091] Sepiolite: Clay 20, TOLSA, Spain;

[0092] Preparation method of flame-retardant continuous glass fiber reinforced thermoplastic material in examples and comparative examples (except for comparative example 2 / 3): Polypropylene, compatibilizer, ceramic filler, piperazine flame retardant, nitrogen- and / or phosphorus-containing flame retardant, flame retardant synergist, and coupling agent are mixed evenly; the evenly mixed material is added to the main feed port of a twin-screw extruder, and the molten material is extruded into an impregnation die for melt impregnation with surface-modified continuous glass fiber (temperature 240-260℃), cooled, cured, and pelletized. The pellet length is 10mm to obtain the flame-retardant continuous glass fiber reinforced thermoplastic material. The twin-screw extruder has a temperature of 170-250℃ and a screw speed of 450-500 rpm.

[0093] Preparation method of comparative example 2 / 3 flame-retardant continuous glass fiber reinforced thermoplastic material: Polypropylene, compatibilizer, ceramic filler, piperazine flame retardant, nitrogen- and / or phosphorus-containing flame retardant, flame retardant synergist, coupling agent, and low-melting-point glass powder are mixed evenly; the uniformly mixed material is added to the main feed port of a twin-screw extruder, and the molten material is extruded into an impregnation die for melt impregnation with continuous glass fibers (continuous round glass fibers or continuous flat glass fibers) (temperature 240-260℃), cooled, cured, and pelletized with a pellet length of 10mm to obtain the flame-retardant continuous glass fiber reinforced thermoplastic material. The twin-screw extruder has a temperature of 170-250℃ and a screw speed of 450-500 rpm.

[0094] Test methods:

[0095] (1) Flame retardancy: According to UL94 / 2016, the test specimen size is 125mm×12.5mm×2.0mm specimen, and the test equipment is Plastics HVUL HVFC burner, ATLAS, USA.

[0096] (2) Ablation resistance test: The sample with injection molding size of 100mm×100mm×3.00mm was subjected to vertical burning of butane flame according to the test method of GJB323A-96. The temperature of butane flame was as high as 1400℃. The time it took for the sample to be burned through was recorded. The maximum test time was 30 minutes.

[0097] (3) Back plate temperature test: The sample with injection molding size of 100mm×100mm×3.00mm was subjected to butane flame vertically burning according to the test method of GJB323A-96. The temperature of the butane flame was as high as 1400℃. A thermocouple was placed on the other side of the flame of the sample to detect and record the back plate temperature after burning for 10 minutes.

[0098] (4) Evaluation of metal bonding failure: Using a 100mm×10mm×2mm aluminum sample, a 10mm×10mm transverse groove area was laser-etched at the metal end. Flame-retardant glass fiber reinforced polypropylene material was then injection molded to bond the transverse groove area. The bonded sample was subjected to shear tensile failure, and the shear strength was measured in MPa.

[0099] Table 1: Component content and test results of flame-retardant continuous glass fiber reinforced thermoplastic materials in Examples 1-14

[0100]

[0101] Continued from Table 1:

[0102]

[0103] As can be seen from Examples 1-11, when the preferred blending ratio of homopolymer polypropylene / copolymer polypropylene is used, the bonding force with the metal insert is higher and the backplate temperature is lower.

[0104] Table 2: Component content and test results of flame-retardant continuous glass fiber reinforced thermoplastic materials in Examples 15-20

[0105]

[0106] As can be seen from Examples 8 / 15-20, the preferred low melting point glass powder accounts for 0.7-1.5 wt% of the surface-modified continuous glass fiber, and the melting point of the low melting point glass powder is 500-800℃.

[0107] Table 3: Component content and test results of flame-retardant continuous glass fiber reinforced thermoplastic materials in Examples 21-24

[0108]

[0109] The flame-retardant continuous glass fiber reinforced thermoplastic material of the present invention achieves V-0 flame retardancy, shear strength > 6.5 MPa, burn-through time at 1400℃ is not less than 23 min, and back plate temperature is not higher than 150℃ during the 1400℃ ablation test.

[0110] Table 4: Component Contents and Test Results of Comparative Flame-Retardant Continuous Glass Fiber Reinforced Thermoplastic Materials

[0111]

[0112] As can be seen from Comparative Example 1, when the melting point of low-melting-point glass powder is too low, it is easy to burn through and has a low bonding force with metal inserts.

[0113] As can be seen from Comparative Example 2 / 3, when the low melting point glass powder is not attached to the glass fiber, it is easy to burn through and has a low bonding force with the metal insert.

[0114] As can be seen from Comparative Example 4, when the content of compatibilizer is too low, it is easy to burn through.

[0115] As can be seen from Comparative Examples 5 / 6, when the proportion of flame retardant is outside the scope of this invention, the flame retardancy is poor and it is easy to burn through.

[0116] As can be seen from Comparative Example 7, the flame retardancy is poor when kaolin is not present, and the bonding force with metal inserts is low.

Claims

1. A flame-retardant continuous glass fiber reinforced thermoplastic material, characterized in that, By weight, it includes the following components: 39-76 parts of polypropylene; 45-80 parts of surface-modified continuous glass fiber; 2-5 parts compatibilizer; 8-35 parts of ceramic filler; 10-35 parts of piperazine flame retardant; Contains 2.5-6 parts of nitrogen and / or phosphorus-based flame retardants; 0.5-3.5 parts of flame retardant synergist; The surface-modified continuous glass fiber is coated with low-melting-point glass powder, which accounts for 0.2-3 wt% of the surface-modified continuous glass fiber. The melting point of the low-melting-point glass powder is 450-1000℃.

2. The flame-retardant continuous glass fiber reinforced thermoplastic material according to claim 1, characterized in that, The surface-modified continuous glass fiber is coated with a coupling agent and flat glass fiber powder.

3. The flame-retardant continuous glass fiber reinforced thermoplastic material according to claim 1, characterized in that, The weight percentage of low melting point glass powder in surface-modified continuous glass fibers is 0.7-1.5 wt%.

4. The flame-retardant continuous glass fiber reinforced thermoplastic material according to claim 1, characterized in that, The polypropylene is a blend of homopolymer polypropylene and copolymer polypropylene, with the copolymer polypropylene accounting for 45-95 wt% of the total weight of polypropylene.

5. The flame-retardant continuous glass fiber reinforced thermoplastic material according to claim 4, characterized in that, The polypropylene is a blend of homopolymer polypropylene and copolymer polypropylene, with the copolymer polypropylene accounting for 60-90 wt% of the total weight of polypropylene.

6. The flame-retardant continuous glass fiber reinforced thermoplastic material according to claim 1, characterized in that, The melting point of the low-melting-point glass powder is 500-800℃; the average particle size of the low-melting-point glass powder is 1-20 micrometers.

7. The flame-retardant continuous glass fiber reinforced thermoplastic material according to claim 1, characterized in that, The compatibilizer is selected from polar monomer-grafted olefin polymers; the polar monomer is selected from at least one of maleic anhydride groups, acrylic acid groups, and acrylate derivative groups; the olefin polymer is selected from at least one of polyethylene, polypropylene, ethylene-α-olefin copolymers, and styrene-butadiene copolymers.

8. The flame-retardant continuous glass fiber reinforced thermoplastic material according to claim 1, characterized in that, The ceramic filler is selected from at least one of kaolin, talc, mica, wollastonite, sepiolite, and montmorillonite; the piperazine flame retardant is selected from at least one of piperazine phosphate, piperazine pyrophosphate, and piperazine polyphosphate; the nitrogen- and / or phosphorus-containing flame retardant is selected from at least one of ammonium polyphosphate, melamine cyanurate, melamine polyphosphate, triazine charring agent, aluminum hypophosphite, diphenylphosphine-piperazine condensate, and melamine pyrophosphate; and the flame retardant synergist is selected from at least one of zinc oxide, zinc borate, and sepiolite.

9. The flame-retardant continuous glass fiber reinforced thermoplastic material according to claim 1, characterized in that, The mixture, by weight, further comprises 0-0.5 parts of coupling agent, wherein the coupling agent is selected from at least one of silane coupling agent, titanate coupling agent, and aluminate coupling agent; by weight, it further comprises 0-2 parts of additives, wherein the additives are selected from at least one of antioxidants and lubricants; and it further comprises 0-1 parts of colorant.

10. A method for preparing the flame-retardant continuous glass fiber reinforced thermoplastic material according to any one of claims 1-9, characterized in that, The process includes the following steps: mixing all components except the surface-modified continuous glass fiber evenly; then adding the mixture to the main feed port of a twin-screw extruder, extruding the molten material into an impregnation die to melt-impregnate it with the surface-modified continuous glass fiber, cooling, curing, and pelletizing to obtain a flame-retardant continuous glass fiber reinforced thermoplastic material.

11. The application of the flame-retardant continuous glass fiber reinforced thermoplastic material according to any one of claims 1-9, characterized in that, Used to manufacture flame-retardant components.

12. An injection-molded part containing a metal insert, wherein the injection-molded structural component of the part comprises a component made of the flame-retardant continuous glass fiber reinforced thermoplastic material as described in any one of claims 1-8.

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