A continuous glass fiber reinforced flame-retardant ceramicized polyester composite material, unidirectional prepreg tape, composite board and preparation method thereof

Abstract

The application discloses a continuous glass fiber reinforced flame-retardant ceramicized polyester composite material, a unidirectional prepreg tape, a composite board and a preparation method thereof, and belongs to the technical field of high polymer materials. The composite material comprises a polyester thermoplastic resin, continuous glass fibers, a flame retardant, a ceramicizing component and a multifunctional reactive compatibilizer. Further, the multifunctional reactive compatibilizer is a pentaerythritol-based tetra-epoxy silane oligomer, and the molecular structure of the oligomer comprises four epoxy groups and four silanol groups. The application further comprises a melt impregnation preparation method of the unidirectional prepreg tape and a hot-pressing forming method of the composite board. The application combines the continuous glass fiber reinforcement and the ceramicizing flame-retardant technology for the first time and applies the combination to a PBT / PET polyester system. The prepared composite board has a flame-retardant grade reaching UL-94 V-0 level, has excellent mechanical properties and ablation resistance, and can be widely used in battery package shells, interior parts of rail transit vehicles, building templates and electronic and electrical housings and the like.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a continuous glass fiber reinforced flame-retardant ceramicized polyester composite material, a unidirectional prepreg tape, a composite board, and its preparation method. Background Technology

[0002] Continuous fiber reinforced thermoplastic composites (CFRTPs) are widely used in aerospace, transportation, and electronics industries due to their advantages such as lightweight, high strength, and recyclability. Polyester thermoplastic resins such as polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) have become important matrix materials for glass fiber reinforced composites due to their excellent mechanical properties, electrical insulation, and chemical resistance. However, existing technologies still have shortcomings in the following aspects:

[0003] (i) Limitations of fiber morphology. Currently, most commercially available glass fiber reinforced PBT / PET composites use short or long glass fibers as reinforcements, which limits the fiber length and makes it difficult to fully utilize the fiber's reinforcing efficiency. Continuous glass fiber unidirectional tape (UD Tape) can enable the fibers to be fully oriented in a single direction, maximizing the reinforcing effect. However, related technologies are mostly concentrated in a few leading foreign companies, and domestic technological accumulation is relatively weak.

[0004] (II) The contradiction between flame retardant properties and processing performance. PBT and PET are flammable materials, and they need to meet the UL-94 V-0 flame retardant requirements in fields such as electronics, electrical appliances, and new energy vehicles. Existing technologies usually add a large amount of flame retardant (10-20%), but this can easily lead to a sharp increase in melt viscosity, which seriously affects the resin's impregnation effect on continuous fibers and causes a significant decrease in mechanical properties.

[0005] (III) Ceramicization flame retardant technology has not yet been applied to continuous glass fiber reinforced polyester systems. Polymer-based ceramicized composites can form a self-supporting ceramic layer under high-temperature ablation conditions, providing thermal insulation, flame retardancy, and fire protection. Existing technologies have applied ceramicization technology to polypropylene (PP)-based continuous glass fiber reinforced composites, as well as chopped glass fiber reinforced ceramicized flame-retardant PBT composites. However, a technical solution combining continuous glass fiber reinforcement with ceramicized flame retardancy and applying it to PBT / PET polyester systems has not yet been reported. Furthermore, as an inorganic filler, the ceramicized component has poor compatibility with the polyester matrix and is prone to agglomeration, making it difficult to achieve uniform dispersion in continuous fiber impregnation processes.

[0006] (iv) Compatibility issues of PBT / PET alloys. Blending PBT and PET can combine the performance advantages of both, but they tend to separate during melt blending, resulting in limited compatibility. Most existing compatibilizers can only improve the interfacial bonding between polymer matrices and cannot simultaneously solve the interfacial problem between inorganic ceramic fillers and organic matrices.

[0007] (v) Melt Impregnation Issues in High-Filler Systems. In the melt impregnation process of continuous fibers, the high viscosity of thermoplastic resin melt makes it difficult to fully penetrate the fiber bundle. When flame retardants and ceramic components are further added to the resin system, the impregnation difficulty increases further, seriously affecting the quality and mechanical properties of the prepreg tape. Summary of the Invention

[0008] In view of this, the present invention provides a continuous glass fiber reinforced flame-retardant ceramicized polyester composite material, which is made of polyester thermoplastic resin as matrix, continuous glass fiber as reinforcement, and combined with polyepoxysilane oligomer compatibilizer. By combining continuous glass fiber reinforcement, ceramicized flame retardant technology and reactive compatibilization technology, the continuous glass fiber achieves efficient reinforcement of the polyester matrix while ensuring the UL-94 V-0 flame retardant rating. At the same time, it solves the problems of excessively high melt viscosity, difficult impregnation, poor dispersion of ceramic powder and insufficient compatibility of PBT / PET alloy in the existing high-filler flame retardant system.

[0009] The present invention also provides a polyepoxysilane oligomer compatibilizer, which can simultaneously improve the compatibility of PBT / PET alloys, the dispersibility of ceramic powders, and reduce melt viscosity.

[0010] The present invention also provides a method for preparing a unidirectional prepreg tape, which is obtained by the melt impregnation process of the continuous glass fiber reinforced flame retardant ceramicized polyester composite material, and can achieve full impregnation of continuous glass fibers by the high-filling flame retardant ceramicized polyester system.

[0011] A third object of the present invention is to provide a composite board comprising the aforementioned unidirectional prepreg tape.

[0012] The fourth objective of this invention is to provide a method for preparing a composite board, wherein the above-mentioned unidirectional prepreg tape is made into a high-performance composite board by hot pressing.

[0013] To achieve the above objectives, the present invention provides the following technical solution:

[0014] In a first aspect, the present invention provides a continuous glass fiber reinforced flame-retardant ceramicized polyester composite material, comprising the following components by weight: 80-120 parts by weight of polyester thermoplastic resin, 20-80 parts by weight of continuous glass fiber, 5-25 parts by weight of flame retardant, 5-35 parts by weight of ceramicized component, and 0.5-5 parts by weight of multifunctional reactive compatibilizer; wherein...

[0015] The multifunctional reactive compatibilizer is a polyepoxysilane oligomer containing epoxy groups and silanoxy groups, and its molecular structure contains at least 2 epoxy groups and 2 silanoxy groups.

[0016] Preferably, the polyester thermoplastic resin is selected from at least one of polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, and polycyclohexanediol terephthalate.

[0017] Preferably, the continuous glass fiber is a unidirectional continuous glass fiber with a fiber diameter of 5-30 μm.

[0018] Preferably, the flame retardant is a halogen-free flame retardant, selected from at least one of organophosphorus flame retardants and phosphorus-nitrogen flame retardants.

[0019] Preferably, the ceramicizing component includes a ceramicizing agent and a fluxing agent, wherein the ceramicizing agent is selected from at least one of silicate mineral powder, mica powder, and kaolin, and the fluxing agent is selected from at least one of low melting point glass powder and borate.

[0020] Preferably, the polyester thermoplastic resin is an alloy of polybutylene terephthalate and polyethylene terephthalate, wherein the weight ratio of polybutylene terephthalate to polyethylene terephthalate is (60-70):(30-40).

[0021] Preferably, the continuous glass fiber is an alkali-free continuous glass fiber that has been surface-modified with a silane coupling agent.

[0022] Preferably, the polyepoxysilane oligomer has the following general formula:

[0023]

[0024] Where R is a pentaerythritol residue and n is 4, the oligomer is pentaerythritol-based tetraepoxysilane oligomer, whose molecular structure contains 4 epoxy groups and 4 siloxane groups.

[0025] The epoxy equivalent of the polyepoxysilane oligomer is 150-800 g / eq, and the number average molecular weight is 500-3000 g / mol.

[0026] Preferably, the polyepoxysilane oligomer is a pentaerythritol-based tetraepoxysilane oligomer, whose molecular structure contains four epoxy groups and four silane groups; the preparation method of the pentaerythritol-based tetraepoxysilane oligomer includes: pentaerythritol and γ-glycidoxypropyltrimethoxysilane in a molar ratio of 1:4-4.5 undergoing transesterification condensation reaction under the conditions of a catalyst and 80-120°C, removing the byproduct methanol during the reaction, and purifying the product after the reaction to obtain the polyepoxysilane oligomer; the catalyst is p-toluenesulfonic acid, and the amount of catalyst used is 0.5-1.5% of the total mass of the reactants.

[0027] A second aspect of the present invention provides a method for preparing a unidirectional prepreg tape, which is obtained by melt impregnation of the continuous glass fiber reinforced flame-retardant ceramicized polyester composite material, comprising the following steps:

[0028] (1) Drying treatment: Place the polyester thermoplastic resin in a dryer and dry it at 120-160℃ for 4-8 hours to reduce the water content to below 200 ppm;

[0029] (2) The dried polyester thermoplastic resin, flame retardant, ceramic component and multifunctional reactive compatibilizer are mixed evenly according to the formula, and melt-blended by a twin-screw extruder to obtain resin melt; the screw speed of the twin-screw extruder is 10-60 r / min and the extrusion temperature is 160-280℃.

[0030] (3) The continuous glass fiber is spread and dispersed by the fiber spreading device. Before spreading and dispersing, it is preheated by the infrared heating device. The temperature of the infrared heating device is 180-250℃.

[0031] (4) The resin melt obtained in step (2) is conveyed to the melt distributor, the temperature of which is 200-280℃. After being evenly distributed by the melt distributor, it enters the impregnation mold; the continuous glass fiber obtained in step (3) after spreading and dispersing is sent into the impregnation mold and melted with the resin melt in the impregnation mold. The heating temperature of the impregnation mold is 200-300℃ and the impregnation pressure is 0.5-5 MPa.

[0032] (5) The continuous fiber bundle obtained after impregnation in step (4) is cooled and shaped by a three-roll calender at a temperature of 20-80°C. Then it is pulled by a traction device and wound by a winding device to obtain a unidirectional prepreg tape. The traction speed of the traction device is 2-15 m / min and the winding speed of the winding device is 5-15 m / min.

[0033] Preferably, in step (2), the twin-screw extruder is provided with five heating zones in sequence along the material conveying direction, and the temperature of each heating zone is set as follows: Zone 1 160-200℃, Zone 2 180-220℃, Zone 3 200-240℃, Zone 4 220-260℃, and Zone 5 240-280℃; the feeding speed of the twin-screw extruder is 5-50 kg / h.

[0034] Preferably, in step (4), the impregnation mold is an impregnation mold with a wavy impregnation surface. The wavy impregnation surface is formed by the bottom surface of the upper mold core and the top surface of the lower mold core being fastened together to form an impregnation cavity. The impregnation cavity is provided with multiple sets of impregnation rollers. The melt impregnates the continuous glass fiber under the wetting angle formed by the multiple sets of impregnation rollers. The melt impregnation is a secondary melt impregnation, which includes a preliminary impregnation and a secondary impregnation step.

[0035] Preferably, in step (5), the three-roll calender consists of an upper calendering roller, an intermediate calendering roller, and a lower calendering roller, with the temperatures of the three rollers independently controlled. The temperature of the upper roller is 30-80℃, the temperature of the intermediate roller is 40-90℃, and the temperature of the lower roller is 20-70℃. The thickness of the unidirectional prepreg tape is 0.10-0.60 mm, the width is 50-600 mm, and the fiber content is 50-80 wt%.

[0036] A third aspect of the present invention provides a method for preparing a continuous glass fiber reinforced flame-retardant ceramicized polyester composite board, the flame-retardant rating of which reaches UL-94 V-0, wherein the board is prepared by hot pressing of the unidirectional prepreg tape obtained by the aforementioned method, and includes the following steps:

[0037] (a) Lay up several layers of the unidirectional prepreg tape at a preset angle;

[0038] (b) Place the stacked prepreg tape layers into a hot press mold, heat it to above the melting point of the polyester thermoplastic resin, and apply pressure to perform hot pressing molding;

[0039] (c) While maintaining pressure, the material is cooled and shaped, then demolded to obtain a continuous glass fiber reinforced flame retardant ceramicized polyester composite board.

[0040] Preferably, in step (a), the preset angle is one or more of 0°, 90°, and ±45°.

[0041] Preferably, in step (b), the heating is segmented heating, including a preheating section and a hot pressing section, the hot pressing temperature is 180-280℃, the hot pressing pressure is 0.5-5 MPa, and the hot pressing time is 5-30 min.

[0042] A fourth aspect of the invention provides the application of the continuous glass fiber reinforced flame-retardant ceramicized polyester composite material, or the continuous glass fiber reinforced flame-retardant ceramicized polyester composite board, in the preparation of battery pack housings, interior parts for rail transit vehicles, building templates, or electronic and electrical enclosures.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. This invention is the first to combine continuous glass fiber reinforcement with ceramic flame retardant technology and apply it to PBT / PET polyester systems, overcoming the limitation of existing ceramic flame retardant technology being only applicable to PP matrix or short fiber reinforced systems. During combustion, the ceramic components and flame retardants work synergistically to form a dense ceramic protective layer, isolating oxygen and heat transfer, enabling the composite material to achieve a UL-94 V-0 flame retardant rating.

[0045] 2. This invention provides a pentaerythritol-based tetraepoxysilane oligomer as a multifunctional reactive compatibilizer. Its molecular structure contains four epoxy groups and four silane groups. The epoxy groups react with polyester end groups (-COOH, -OH) to achieve star-shaped chain extension compatibilization, improving the compatibility of PBT / PET alloys. The silane groups condense with the hydroxyl groups on the surface of ceramic powder to form chemical bonds, firmly anchoring the ceramic powder in the polyester matrix, significantly improving the dispersibility of the ceramic powder and enhancing the interfacial bonding force.

[0046] 3. The multi-arm star-shaped structure of the compatibilizer of the present invention can effectively reduce the melt viscosity of the high-filling system, improve the high-temperature processing fluidity, and solve the process problem of the viscosity increasing sharply and the impregnation difficulty caused by the addition of a large amount of flame retardant and ceramic powder in the prior art.

[0047] 4. This invention achieves full impregnation of continuous glass fibers by a high-filling flame-retardant ceramicized polyester system through an optimized melt impregnation process (coordinated operation of zoned temperature control, infrared preheating, and uniform material distribution by a melt distributor). The prepreg tape has excellent impregnation quality and controllable fiber content.

[0048] 5. The composite board prepared by this invention has both high mechanical strength due to continuous fiber reinforcement and high fire safety due to ceramic flame retardancy, and can be widely used in fields such as battery pack shells, interior parts of rail transit vehicles, building templates and electronic appliance shells. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to embodiments. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various equivalent substitutions and modifications based on the inventive concept, and these all fall within the scope of protection of the present invention.

[0050] (a) Composite material composition

[0051] A continuous glass fiber reinforced flame-retardant ceramicized polyester composite material comprises the following components: polyester thermoplastic resin, continuous glass fiber, flame retardant, ceramicized component, and multifunctional reactive compatibilizer; wherein the multifunctional reactive compatibilizer is a polyepoxysilane oligomer containing multiple epoxy groups and multiple silanoxy groups, and its molecular structure contains at least 2 epoxy groups and 2 silanoxy groups.

[0052] The polyepoxysilane oligomer is prepared by transesterification condensation reaction of pentaerythritol and γ-glycidyl etheroxypropyltrimethoxysilane, and has the following general formula:

[0053]

[0054] Where R is a pentaerythritol residue and n is 4, the oligomer is pentaerythritol-based tetraepoxysilane oligomer, whose molecular structure contains 4 epoxy groups and 4 siloxane groups.

[0055] The epoxy equivalent of the polyepoxysilane oligomer is 150-800 g / eq, and the number average molecular weight is 500-3000 g / mol; the amount of the multifunctional reactive compatibilizer added is 0.5-5 parts by weight.

[0056] The polyester thermoplastic resin is selected from at least one of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET). When a PBT and PET alloy is used, the weight ratio of PBT to PET is (60-70):(30-40).

[0057] The continuous glass fiber is a unidirectional continuous glass fiber with a fiber diameter of 5-30 μm and a fiber content of 20-80 parts by weight; preferably, the continuous glass fiber is an alkali-free continuous glass fiber that has been surface modified with a silane coupling agent.

[0058] The ceramicizing component includes a ceramicizing agent and a flux. The ceramicizing agent is selected from at least one of silicate mineral powder, mica powder, and kaolin. The flux is selected from at least one of low-melting-point glass powder and borate. The total amount of the ceramicizing component added is 5-35 parts by weight.

[0059] The flame retardant is a halogen-free flame retardant, selected from at least one of organophosphorus flame retardants and phosphorus-nitrogen flame retardants; the amount of the flame retardant added is 5-25 parts by weight.

[0060] In the above composite material, the epoxy group of the multifunctional reactive compatibilizer undergoes a ring-opening reaction with the carboxyl group (-COOH) and / or hydroxyl group (-OH) at the end of the polyester thermoplastic resin to achieve star-shaped chain extension compatibilization; after hydrolysis, the silanoxy group (Si-OCH3) undergoes a condensation reaction with the hydroxyl group (-OH) on the surface of the ceramicized component to form Si-O- ceramic chemical bonds, thereby chemically anchoring the ceramicized component to the polyester matrix, while also compatibilizing the PBT / PET alloy and regulating the viscosity of the system.

[0061] (II) Preparation of polyepoxysilane oligomers

[0062] The preparation method of the above-mentioned polyepoxysilane oligomers includes the following steps:

[0063] (1) Dissolve γ-glycidoxypropyltrimethoxysilane (KH-560) in anhydrous ethanol, add deionized water, adjust the pH to 4-5 with glacial acetic acid, and stir hydrolyze for 30-60 min at room temperature to obtain hydrolysate, wherein the molar ratio of KH-560 to deionized water is 1:0.3-0.5;

[0064] (2) Dissolve pentaerythritol in anhydrous xylene and heat to 80-100℃ to dissolve it completely. Under nitrogen protection, slowly add the hydrolysate obtained in step (1) and add p-toluenesulfonic acid as a catalyst. Stir the reaction at 100-120℃ for 4-8 h. The molar ratio of pentaerythritol to KH-560 is 1:4-4.5, and the amount of catalyst is 0.5-1.5% of the total mass of the reactants.

[0065] (3) During the reaction, methanol, a byproduct, is continuously distilled off. After the reaction is completed, the solvent and unreacted small molecules are removed by vacuum distillation to obtain pentaerythritol tetracyclooxysilane oligomer.

[0066] (III) Preparation of unidirectional prepreg tape

[0067] A method for preparing a continuous glass fiber reinforced flame-retardant ceramicized polyester unidirectional prepreg tape includes the following steps:

[0068] (1) Drying treatment: Place the polyester thermoplastic resin in a dryer and dry it at 120-160℃ for 4-8 hours to reduce the water content to below 200 ppm;

[0069] (2) The dried polyester thermoplastic resin, flame retardant, ceramicized component and the above-mentioned multifunctional reactive compatibilizer are mixed evenly according to the formula, and melt-blended by a twin-screw extruder to obtain resin melt; the twin-screw extruder is provided with five heating zones in sequence along the material conveying direction, and the temperature of each heating zone is set as follows: Zone 1 160-200℃, Zone 2 180-220℃, Zone 3 200-240℃, Zone 4 220-260℃, Zone 5 240-280℃; the screw speed is 10-60 r / min, and the feeding speed is 5-50 kg / h;

[0070] (3) The continuous glass fiber is spread and dispersed by the fiber spreading device. Before spreading and dispersing, it is preheated by the infrared heating device. The temperature of the infrared heating device is 180-250℃.

[0071] (4) The resin melt obtained in step (2) is conveyed to the melt distributor, the temperature of which is 200-280℃. After being evenly distributed by the melt distributor, it enters the impregnation mold; the continuous glass fiber obtained in step (3) after spreading and dispersing is sent into the impregnation mold and melted with the resin melt in the impregnation mold. The heating temperature of the impregnation mold is 200-300℃ and the impregnation pressure is 0.5-5 MPa.

[0072] (5) The continuous fiber bundle obtained after impregnation in step (4) is cooled and shaped by a three-roll calender at a temperature of 20-80°C. Then it is pulled by a traction device and wound by a winding device to obtain a continuous glass fiber reinforced flame retardant ceramicized polyester unidirectional prepreg tape. The traction speed of the traction device is 2-15 m / min and the winding speed of the winding device is 5-15 m / min.

[0073] Preferably, the impregnation mold is an impregnation mold with a wavy impregnation surface. The wavy impregnation surface is formed by the bottom surface of the upper mold core and the top surface of the lower mold core being fastened together to form an impregnation cavity. Multiple sets of impregnation rollers are provided in the impregnation cavity, and the melt impregnates the continuous glass fiber under the wetting angle formed by the multiple sets of impregnation rollers.

[0074] Preferably, the melt impregnation is a two-stage melt impregnation, which includes a preliminary impregnation and a secondary impregnation step.

[0075] Preferably, the continuous glass fibers are pretreated with a silane coupling agent before being spread and dispersed.

[0076] Preferably, the three-roll calender consists of an upper calendering roller, an intermediate calendering roller, and a lower calendering roller. The temperatures of the three rollers are independently controlled, with the upper roller temperature at 30-80℃, the intermediate roller temperature at 40-90℃, and the lower roller temperature at 20-70℃.

[0077] Preferably, the unidirectional prepreg tape has a thickness of 0.10-0.60 mm, a width of 50-600 mm, and a fiber content of 50-80 wt%.

[0078] (iv) Preparation of composite panels

[0079] A method for preparing a continuous glass fiber reinforced flame-retardant ceramicized polyester composite board includes the following steps:

[0080] (1) Provide a continuous glass fiber reinforced flame retardant ceramicized polyester unidirectional prepreg tape prepared by the above method;

[0081] (2) Lay up the multiple layers of the unidirectional prepreg tape at a preset angle, wherein the preset angle is one or more combinations of 0°, 90°, and ±45°;

[0082] (3) Place the stacked prepreg tape layer into a hot press mold, heat it to above the melting point of the polyester thermoplastic resin, and apply pressure for hot pressing molding; the hot pressing molding temperature is 180-280℃, the hot pressing pressure is 0.5-5 MPa, and the hot pressing time is 5-30 min.

[0083] (4) While maintaining pressure, the temperature drops and the material is cooled and shaped, then demolded to obtain a continuous glass fiber reinforced flame retardant ceramicized polyester composite board.

[0084] Preferably, the heating is segmented heating, including a preheating section and a hot pressing section.

[0085] (v) Products and Uses

[0086] A continuous glass fiber reinforced flame-retardant ceramicized polyester composite board is prepared by the above-mentioned method, and the flame retardant rating of the composite board reaches UL-94 V-0 level.

[0087] The above-mentioned continuous glass fiber reinforced flame retardant ceramicized polyester composite material or composite board is used in the preparation of battery pack shells, interior parts of rail transit vehicles, building templates or electronic and electrical enclosures.

[0088] In the following examples, all raw materials used were commercially available industrial products. Specifically: the PBT resin used was injection molding grade PBT with an intrinsic viscosity of 0.8-1.2 dL / g; the PET resin used was fiber grade PET with an intrinsic viscosity of 0.6-0.8 dL / g; the continuous glass fiber used was alkali-free continuous glass fiber roving with a single filament diameter of 13-17 μm and a linear density of 1200-2400 tex; the purity of KH-560 (γ-glycidoxypropyltrimethoxysilane) was ≥98%; the purity of pentaerythritol was ≥99%; and the p-toluenesulfonic acid was analytical grade.

[0089] Example 1: Preparation of pentaerythritol-based tetraepoxysilane oligomers

[0090] This embodiment provides a method for preparing pentaerythritol-based tetracyclooxysilane oligomers, which are multifunctional reactive compatibilizers.

[0091] 236.4 g (1.0 mol) of γ-glycidoxypropyltrimethoxysilane (KH-560) was dissolved in 500 mL of anhydrous ethanol, 9.0 g (0.5 mol) of deionized water was added, the pH was adjusted to 4-5 with glacial acetic acid, and the mixture was stirred and hydrolyzed at room temperature for 45 min to obtain the hydrolysate.

[0092] 34.0 g (0.25 mol) of pentaerythritol was dissolved in 800 mL of anhydrous xylene and heated to 90 °C until completely dissolved. Under nitrogen protection, the hydrolysate was slowly added dropwise, followed by 2.7 g of p-toluenesulfonic acid (1.0% of the total mass of the reactants), and the mixture was stirred at 110 °C for 6 h. Methanol, a byproduct, was continuously distilled off during the reaction.

[0093] After the reaction was completed, the solvent and unreacted small molecules were removed by vacuum distillation, yielding a pale yellow viscous liquid product, which was pentaerythritol-based tetraepoxysilane oligomer. Analysis showed that the product had an epoxy equivalent of 235 g / eq and a number-average molecular weight of 1120 g / mol, which is close to the theoretical value (approximately 1084 g / mol).

[0094] The product was characterized using Fourier transform infrared spectroscopy (FT-IR): at 910 cm⁻¹ -1 Characteristic absorption peaks of epoxy groups appear at 1100-1020 cm⁻¹. -1 The characteristic absorption peak of the Si-OC bond appears at 3400 cm⁻¹. -1 The hydroxyl absorption peak was significantly weakened. The product was characterized by ¹H nuclear magnetic resonance (¹H-NMR): δ 0.6-0.8 ppm (Si-CH2-), δ 1.6-1.8 ppm (-CH2-), δ 2.6-2.8 ppm (-CH- on the epoxy ring), δ 3.2-3.4 ppm (-CH2- on the epoxy ring), δ 3.5-3.7 ppm (-O-CH3), δ 4.0-4.2 ppm (-CH2-O- in the pentaerythritol core). The above characterization results confirm the successful synthesis of the target product, pentaerythritol-based tetraepoxysilane oligomer.

[0095] Example 2: Preparation of Continuous Glass Fiber Reinforced Flame-Retardant Ceramicized PBT Unidirectional Prepreg Tape

[0096] This embodiment provides a method for preparing a continuous glass fiber reinforced flame-retardant ceramicized unidirectional prepreg tape based on PBT.

[0097] (1) Resin drying: Place the PBT resin in a blower dryer and dry it at 140°C for 6 hours to reduce the water content to below 200 ppm.

[0098] (2) Preparation of resin melt: By weight, 100 parts of dried PBT resin, 18 parts of halogen-free flame retardant (aluminum diethylphosphinate), 20 parts of ceramicizing components (12 parts of wollastonite powder and 8 parts of low-melting-point glass powder), 3 parts of pentaerythritol-based tetraepoxysilane oligomer prepared in Example 1, and 0.5 parts of antioxidant (antioxidant 1010) were added to a high-speed mixer and mixed evenly. The mixture was then melt-blended using a twin-screw extruder. The temperatures of the heating zones of the extruder were set as follows: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 240℃, and Zone 5 260℃; the screw speed was 30 r / min, and the feeding speed was 20 kg / h, to obtain a uniform resin melt.

[0099] (3) Pretreatment and spreading of continuous glass fiber: The alkali-free continuous glass fiber roving is pretreated with an aqueous solution of silane coupling agent (KH-550) and then dried. The pretreated glass fiber is spread and dispersed by a spreading device. Before spreading and dispersing, it is preheated by an infrared heating device at a temperature of 220°C.

[0100] (4) Melt Impregnation: The resin melt obtained in step (2) is conveyed to a melt distributor at a temperature of 250°C. After being evenly distributed by the melt distributor, the resin melt enters an impregnation mold with a wavy impregnation surface. The continuous glass fiber obtained in step (3) after spreading and dispersing is fed into the impregnation mold and melt impregnated with the resin melt. The heating temperature of the impregnation mold is 260°C, and the impregnation pressure is 2 MPa.

[0101] (5) Cooling and setting: The impregnated continuous fiber bundle is cooled and set by a three-roll calender. The temperatures of the three rolls are: 50°C for the upper roll, 60°C for the middle roll, and 40°C for the lower roll. After cooling and setting, it is pulled by a traction device and wound by a winding device. The traction speed is 8 m / min and the winding speed is 8 m / min, to obtain a continuous glass fiber reinforced flame-retardant ceramicized PBT unidirectional prepreg tape. The thickness of the obtained unidirectional prepreg tape is 0.30 mm, the width is 300 mm, and the fiber content is 65 wt%.

[0102] Example 3: Preparation of Continuous Glass Fiber Reinforced Flame-Retardant Ceramicized PET Unidirectional Prepreg Tape

[0103] This embodiment provides a method for preparing a continuous glass fiber reinforced flame-retardant ceramicized unidirectional prepreg tape based on PET.

[0104] The difference from Example 2 is that PBT resin was replaced with PET resin, the drying temperature of PET resin was 150°C and the drying time was 8 h; the temperatures of each heating zone of the twin-screw extruder were set as follows: zone 1 200°C, zone 2 220°C, zone 3 240°C, zone 4 260°C, and zone 5 280°C; the melt distributor temperature was 270°C; the impregnation die heating temperature was 280°C; and the other conditions were the same as in Example 2. The resulting unidirectional prepreg tape had a thickness of 0.30 mm, a width of 300 mm, and a fiber content of 63 wt%.

[0105] Example 4: Preparation of Continuously Glass Fiber Reinforced Flame-Retardant Ceramicized PBT / PET Alloy Unidirectional Prepreg Tape

[0106] This embodiment provides a method for preparing a continuous glass fiber reinforced flame-retardant ceramicized unidirectional prepreg tape with PBT / PET alloy as the matrix.

[0107] The difference from Example 2 is that the PBT resin was replaced with a PBT / PET alloy (PBT to PET weight ratio of 65:35); the temperatures of each heating zone of the twin-screw extruder were set as follows: Zone 1 190°C, Zone 2 210°C, Zone 3 230°C, Zone 4 250°C, and Zone 5 270°C; all other conditions were the same as in Example 2. The resulting unidirectional prepreg tape had a thickness of 0.32 mm, a width of 300 mm, and a fiber content of 64 wt%.

[0108] Example 5: Preparation of Continuous Glass Fiber Reinforced Flame-Retardant Ceramicized Polyester Composite Board

[0109] This embodiment provides a method for preparing a composite board from the above-mentioned unidirectional prepreg tape by hot pressing.

[0110] Take the continuous glass fiber reinforced flame-retardant ceramicized PBT unidirectional prepreg tape prepared in Example 2 and lay it up in a [0° / 90°]4 layup pattern (i.e., 4 layers in the 0° direction and 4 layers in the 90° direction are alternately stacked, for a total of 8 layers).

[0111] The stacked prepreg tape layers are placed in a hot press mold. After the mold is closed, it is preheated to 240°C at a rate of 5°C / min and held for 10 min. Then, it is pressurized to 2 MPa and hot-pressed at 240°C and 2 MPa for 15 min. After holding the pressure and cooling to below 60°C, it is demolded to obtain a continuous glass fiber reinforced flame-retardant ceramicized PBT composite board with a thickness of 2.4 mm.

[0112] Example 6: Preparation of PBT / PET alloy composite plate

[0113] This embodiment provides a method for preparing composite boards from PBT / PET alloy-based unidirectional prepreg tape by hot pressing.

[0114] The continuous glass fiber reinforced flame-retardant ceramicized PBT / PET alloy unidirectional prepreg tape prepared in Example 4 was laminated in a layup pattern of [0° / 90° / +45° / -45°] (8 layers in total).

[0115] The stacked prepreg tape layers are placed in a hot press mold. After the mold is closed, it is preheated to 255°C at a rate of 5°C / min and held for 10 min. Then, it is pressurized to 2.5 MPa and hot-pressed at 255°C and 2.5 MPa for 15 min. After holding the pressure and cooling to below 60°C, it is demolded to obtain a continuous glass fiber reinforced flame-retardant ceramicized PBT / PET alloy composite board.

[0116] Performance testing

[0117] The composite panels prepared in the above embodiments were subjected to performance tests, and the test results are shown in Table 1.

[0118] Table 1

[0119]

[0120] Ablation resistance test method: Refer to GJB 323A-96 "Ablation Test Method for Ablation Materials" and adopt the oxygen-acetylene ablation test method. The composite plate sample is processed into a 30 mm × 30 mm × 10 mm cube and fixed on the sample fixture. The oxygen-acetylene flame is adjusted to the distance between the tip of the inner flame and the sample surface, and the flame is perpendicular to the sample surface. The oxygen pressure is 0.4 MPa, the acetylene pressure is 0.095 MPa, and the ablation time is 60 s. The thickness and mass of the sample are measured before and after ablation. The linear ablation rate and mass ablation rate are calculated according to formula (1) and formula (2). At the same time, the K-type thermocouple is used to measure the back center temperature of the sample during the ablation process.

[0121] Linear ablation rate R_l = (d0 – d1) / t

[0122] Mass ablation rate R_m = (m0 – m1) / t

[0123] Where d0 and d1 are the sample thicknesses (mm) before and after ablation, m0 and m1 are the sample masses (g) before and after ablation, and t is the ablation time (s).

[0124] Test method for flexural strength of ignition residue: Refer to GB / T 1449-2005 "Test method for flexural properties of fiber reinforced plastics" and use the three-point bending method. Place the composite board sample in a muffle furnace and heat it to 1000℃ at a heating rate of 10℃ / min. After holding at this temperature for 30 min, allow it to cool naturally to room temperature. Remove the ignition residue (ceramic body) and process it into a bending sample of 80 mm × 10 mm × 4 mm. Perform a three-point bending test on an electronic universal testing machine with a loading rate of 2 mm / min and a span of 64 mm.

[0125] Test results show that the continuous glass fiber reinforced flame-retardant ceramicized polyester composite board prepared by this invention has excellent mechanical and flame-retardant properties, with a tensile strength (0° direction) ≥485 MPa, a flexural strength ≥640 MPa, a flame-retardant rating of UL-94 V-0, and a limiting oxygen index ≥30%. Furthermore, after being burned at 1000℃, the residue still maintains a high flexural strength (≥28 MPa), indicating that the ceramicized components form a dense ceramic protective layer at high temperatures, endowing the composite material with excellent ablation resistance, with a linear ablation rate as low as 0.012-0.015 mm / s.

[0126] Comparative Example 1: No compatibilizer added

[0127] The difference from Example 2 is that pentaerythritol-based tetraepoxysilane oligomers are not added; all other conditions are the same as in Example 2. Composite plates are prepared according to the method of Example 5.

[0128] Test results show that the composite board prepared in Comparative Example 1 has a tensile strength of 380 MPa and a flexural strength of 490 MPa, which are significantly lower than the corresponding values ​​in Example 5. Meanwhile, during the preparation of the prepreg tape, the impregnation effect was significantly worse due to the excessively high viscosity of the resin melt, resulting in noticeable unimpregnated areas on the surface of the prepreg tape. This indicates that the multifunctional reactive compatibilizer of the present invention plays a crucial role in improving the impregnation effect and enhancing mechanical properties.

[0129] Comparative Example 2: Commercially available KH-560 was used instead of the compatibilizer of this invention.

[0130] The difference from Example 2 is that the pentaerythritol tetracyclooxysilane oligomer was replaced with an equal amount of KH-560 (γ-glycidoxypropyltrimethoxysilane), while the other conditions were the same as in Example 2. The composite plate was prepared according to the method of Example 5.

[0131] Test results show that the composite plate prepared in Comparative Example 2 has a tensile strength of 410 MPa and a flexural strength of 530 MPa, which are lower than the corresponding values ​​in Example 5. Meanwhile, the uniformity of the dispersion of the ceramicized component in the matrix is ​​significantly worse than in Example 5, indicating that the multi-anchor structure of the compatibilizer of this invention has a better effect on improving the dispersion of ceramic powder than the single-functional-group KH-560.

[0132] Comparative Example 3: No ceramicizing components added

[0133] The difference from Example 2 is that no ceramicizing components (wollastonite powder and low-melting-point glass powder) are added, the amount of flame retardant added is increased to 25 parts, and the other conditions are the same as in Example 2. The composite board is prepared according to the method of Example 5.

[0134] The test results are shown in Table 2. The composite board prepared in Comparative Example 3 only achieved a UL-94 V-1 flame retardancy rating (1.6 mm) with a limiting oxygen index of 26%, failing to meet the V-0 rating requirement. This indicates that the synergistic effect of the ceramicized components and the flame retardant is key to achieving a V-0 flame retardancy rating.

[0135] Table 2

[0136]

[0137] The continuous glass fiber reinforced flame-retardant ceramicized polyester composite material, its unidirectional prepreg tape, and composite board provided by this invention have widely available raw materials, mature preparation processes, and strong operability, making them suitable for large-scale industrial production. The resulting composite board possesses both excellent mechanical and flame-retardant properties, and can be widely used in battery pack housings, interior components of rail transit vehicles, building formwork, and electronic appliance housings.

[0138] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A continuous glass fiber reinforced flame-retardant ceramicized polyester composite material, characterized in that, The product comprises the following components by weight: 80-120 parts by weight of polyester thermoplastic resin, 20-80 parts by weight of continuous glass fiber, 5-25 parts by weight of flame retardant, 5-35 parts by weight of ceramicizing component, and 0.5-5 parts by weight of multifunctional reactive compatibilizer; wherein... The multifunctional reactive compatibilizer is a polyepoxysilane oligomer containing epoxy groups and silanoxy groups, and its molecular structure contains at least 2 epoxy groups and 2 silanoxy groups.

2. The continuous glass fiber reinforced flame-retardant ceramicized polyester composite material according to claim 1, characterized in that, The polyester thermoplastic resin is selected from at least one of polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, and polycyclohexanediol terephthalate. The continuous glass fiber is a unidirectional continuous glass fiber with a fiber diameter of 5-30 μm; The flame retardant is a halogen-free flame retardant, selected from at least one of organophosphorus flame retardants and phosphorus-nitrogen flame retardants; The ceramicizing component includes a ceramic-forming agent and a flux. The ceramic-forming agent is selected from at least one of silicate mineral powder, mica powder, and kaolin, and the flux is selected from at least one of low-melting-point glass powder and borate.

3. The continuous glass fiber reinforced flame-retardant ceramicized polyester composite material according to claim 2, characterized in that, The polyester thermoplastic resin is an alloy of polybutylene terephthalate and polyethylene terephthalate, wherein the weight ratio of polybutylene terephthalate to polyethylene terephthalate is (60-70):(30-40). The continuous glass fiber is an alkali-free continuous glass fiber that has been surface-modified with a silane coupling agent.

4. The continuous glass fiber reinforced flame-retardant ceramicized polyester composite material according to claim 1, characterized in that, The polyepoxysilane oligomers have the following general formula: Where R is a pentaerythritol residue and n is an integer in the range [2, 8]; The epoxy equivalent of the polyepoxysilane oligomer is 150-800 g / eq, and the number average molecular weight is 500-3000 g / mol.

5. The continuous glass fiber reinforced flame-retardant ceramicized polyester composite material according to claim 4, characterized in that, The polyepoxysilane oligomer is a pentaerythritol tetraepoxysilane oligomer, whose molecular structure contains 4 epoxy groups and 4 siloxane groups. The method for preparing the pentaerythritol-based tetraepoxysilane oligomer includes: pentaerythritol and γ-glycidoxypropyltrimethoxysilane in a molar ratio of 1:4-4.5 undergoing transesterification condensation reaction under the conditions of a catalyst and 80-120°C; during the reaction, methanol byproduct is removed; and after the reaction, the oligomer is obtained by purification; the catalyst is p-toluenesulfonic acid, and the amount of catalyst used is 0.5-1.5% of the total mass of the reactants.

6. A method for preparing a unidirectional prepreg tape, characterized in that, It is prepared by melt impregnation of the continuous glass fiber reinforced flame retardant ceramicized polyester composite material according to any one of claims 1 to 5, comprising the following steps: (1) Drying treatment: Place the polyester thermoplastic resin in a dryer and dry it at 120-160℃ for 4-8 hours to reduce the moisture content to below 200 ppm; (2) The dried polyester thermoplastic resin, flame retardant, ceramic component and multifunctional reactive compatibilizer are mixed evenly according to the formula, and melt-blended by a twin-screw extruder to obtain resin melt; the screw speed of the twin-screw extruder is 10-60 r / min and the extrusion temperature is 160-280℃. (3) The continuous glass fiber is spread and dispersed by the fiber spreading device. Before spreading and dispersing, it is preheated by the infrared heating device. The temperature of the infrared heating device is 180-250℃. (4) The resin melt obtained in step (2) is conveyed to the melt distributor, the temperature of which is 200-280℃. After being evenly distributed by the melt distributor, it enters the impregnation mold; the continuous glass fiber obtained in step (3) after spreading and dispersing is sent into the impregnation mold and melted with the resin melt in the impregnation mold. The heating temperature of the impregnation mold is 200-300℃ and the impregnation pressure is 0.5-5 MPa. (5) The continuous fiber bundle obtained after impregnation in step (4) is cooled and shaped by a three-roll calender at a temperature of 20-80°C. Then it is pulled by a traction device and wound by a winding device to obtain a unidirectional prepreg tape. The traction speed of the traction device is 2-15 m / min and the winding speed of the winding device is 5-15 m / min.

7. The method for preparing the unidirectional prepreg tape according to claim 6, characterized in that, In step (2), the twin-screw extruder is provided with five heating zones in sequence along the material conveying direction, and the temperature of each heating zone is set as follows: Zone 1 160-200℃, Zone 2 180-220℃, Zone 3 200-240℃, Zone 4 220-260℃, Zone 5 240-280℃; the feeding speed of the twin-screw extruder is 5-50 kg / h; In step (4), the impregnation mold is an impregnation mold with a wavy impregnation surface. The wavy impregnation surface is formed by the bottom surface of the upper mold core and the top surface of the lower mold core being fastened together to form an impregnation cavity. Multiple sets of impregnation rollers are provided in the impregnation cavity. The melt impregnates the continuous glass fiber under the wetting angle formed by the multiple sets of impregnation rollers. The melt impregnation is a two-stage melt impregnation, which includes a preliminary impregnation and a secondary impregnation step; In step (5), the three-roll calender consists of an upper calendering roller, an intermediate calendering roller, and a lower calendering roller. The temperatures of the three rollers are independently controlled. The temperature of the upper roller is 30-80℃, the temperature of the intermediate roller is 40-90℃, and the temperature of the lower roller is 20-70℃. The thickness of the unidirectional prepreg tape is 0.10-0.60 mm, the width is 50-600 mm, and the fiber content is 50-80 wt%.

8. A method for preparing a continuous glass fiber reinforced flame-retardant ceramicized polyester composite board, characterized in that, Its flame retardancy rating reaches UL-94 V-0. It is produced by hot pressing of a unidirectional prepreg tape prepared by the method described in claim 6 or 7, comprising the following steps: (a) Lay up several layers of the unidirectional prepreg tape at a preset angle; (b) Place the stacked prepreg tape layers into a hot press mold, heat it to above the melting point of the polyester thermoplastic resin, and apply pressure to perform hot pressing molding; (c) While maintaining pressure, the material is cooled and shaped, then demolded to obtain a continuous glass fiber reinforced flame retardant ceramicized polyester composite board.

9. The method for preparing the continuous glass fiber reinforced flame-retardant ceramicized polyester composite board according to claim 8, characterized in that, In step (a), the preset angle is one or more of 0°, 90°, and ±45°; In step (b), the heating is segmented heating, including a preheating section and a hot pressing section. The hot pressing temperature is 180-280℃, the hot pressing pressure is 0.5-5 MPa, and the hot pressing time is 5-30 min.

10. The application of the continuous glass fiber reinforced flame retardant ceramicized polyester composite material according to any one of claims 1 to 5, or the continuous glass fiber reinforced flame retardant ceramicized polyester composite board according to claim 8 or 9, in the preparation of battery pack housings, interior parts of rail transit vehicles, building templates, or electronic and electrical enclosures.

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