Continuous fiber reinforced thermoplastic composite material and preparation method thereof

Abstract

The invention discloses a continuous fiber reinforced thermoplastic composite material and a preparation method thereof. The continuous fiber reinforced thermoplastic composite material comprises 35-40% of a polypropylene matrix with a melt index of 10-30 g / 10 min; 55% of continuous fibers are selected from glass fibers, carbon fibers or basalt fibers which are arranged in one direction, and the monofilament diameter is 9-15 microns; the intumescent flame retardant and the ammonium polyphosphate are compounded according to the mass ratio of 2: 1; 1-2% of an interface modifier, wherein a silane coupling agent KH-570 or PP-g-MAH is selected and used; the roughness Ra of the aluminum foil layer is 1.5-2.5 microns; under the condition of basically ensuring that the overall performance of the material is not greatly influenced, the application capability of the material is expanded, and the fireproof and flame-retardant capability of the material is improved, so that a thermoplastic composite material scheme can also be adopted under various harsh use conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance flame-retardant composite materials for new energy battery packs, and specifically to a continuous fiber-reinforced thermoplastic composite material and a preparation method thereof. Background Art

[0002] Currently, existing continuous fiber-reinforced PP composites can achieve UL-94 V0 flame retardancy by adding intumescent flame retardants (such as APP / PER / MCA systems). However, these materials suffer from the following drawbacks: A high flame retardant dosage limit is required: 25-30% flame retardant is required to achieve V0, resulting in a reduced matrix resin ratio and reduced interfacial bonding strength (peel strength is typically <5N / cm); insufficient droplet suppression: PP matrix combustion still easily produces droplets. While these materials pass vertical burn tests, the risk of droplet ignition in actual fire scenarios remains unresolved; and a high heat release rate: While the V0 rating only evaluates extinguishing time, the total heat release (THR) of the material remains as high as 80-100MJ / m², failing to meet the stringent fire safety requirements of high-end applications. While aluminum foil coating is used to enhance flame retardancy, conventional processes for bonding aluminum foil to high-flame retardant-content substrates suffer from poor interfacial compatibility and cracking of the coating layer due to thermal expansion coefficient mismatch. Summary of the Invention

[0003] The object of the present invention is to provide a continuous fiber reinforced thermoplastic composite material and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a continuous fiber reinforced thermoplastic composite material, comprising 35-40% polypropylene matrix with a melt index of 10-30 g / 10 min; 55% continuous fiber, selected from unidirectionally arranged glass fiber, carbon fiber or basalt fiber, with a single fiber diameter of 9-15 μm; 4-6% composite flame retardant, selected from an intumescent flame retardant and ammonium polyphosphate in a mass ratio of 2:1; 1-2% interface modifier, selected from a silane coupling agent KH-570 or PP-g-MAH; and an aluminum foil layer with a roughness Ra of 1.5-2.5 μm.

[0005] Preferably, the preparation method specifically comprises the following steps: S1, fiber pretreatment; S2, preparing prepreg; S3, lamination molding; S4, aluminum foil composite.

[0006] Preferably, the step S1 specifically includes the following steps: a1. Immerse the continuous fiber in an ethanol solution containing 1 wt% KH-570 and dry it; a2. Eliminate fiber bunching through electrostatic dispersion device.

[0007] Preferably, the step S2 specifically includes the following steps: b1. Melt-blending PP-g-MAH, composite flame retardant and 2 wt% antioxidant; b2, coated on the surface of continuous fiber through extruder to form a prepreg tape with a thickness of 0.2-0.3mm. The volume fraction of the fiber is 55%.

[0008] Preferably, in step S3, the prepreg tapes are stacked in the direction of 0° / 90° / 0° / 90° / 90° / 0° / 90° / 0° and placed in a hot press, and pressed and cooled to obtain a composite material plate.

[0009] Preferably, the step S4 specifically includes the following steps: c1. Preheat the plasma-treated aluminum foil to 120°C; c2. Bond the composite material surface with silicone adhesive and form a dense coating layer after hot pressing.

[0010] Preferably, the step c2 specifically includes the following steps: d1. Aluminum atoms on the surface of aluminum foil undergo oxidation reaction with oxygen to generate layer, the reaction equation is: ; d2, ammonium polyphosphate decomposes into and , the reaction equation is: ; d3, polyphosphoric acid and metal oxides Reaction to form aluminum phosphate or glassy polyphosphate; d4. Polyphosphate melts at high temperature and wraps particles, It reacts with polyphosphoric acid to form aluminophosphate, forming a continuous glassy matrix; d5. Oxide layer of aluminum foil It provides a rigid skeleton, and the polyphosphate generated by the decomposition of ammonium polyphosphate acts as a binder and reaction precursor, forming a ceramic barrier through physical filling and chemical reaction.

[0011] Preferably, the hot press temperature is set to 180-190° C., the hot press pressure is set to 5 MPa, and the hot press time is set to 10 min.

[0012] Preferably, in step c2, the hot pressing pressure is set to 0.8 MPa and the hot pressing temperature is set to 140°C.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a continuous fiber-reinforced thermoplastic composite material and its preparation method. This composite material utilizes a V0-grade fiber / PP matrix (LOI ≥ 28%) composite material combined with aluminum foil produced using a specific production process. By combining the lightweight and high-strength properties of the composite material with the flame-retardant properties of aluminum foil, the material achieves significantly enhanced flame retardancy without compromising performance. The aluminum foil not only acts as a physical barrier but also synergistically reacts with the gas-phase physical flame retardant (such as APP) in the matrix, effectively enhancing overall flame retardancy. DETAILED DESCRIPTION

[0014] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0015] In the description of this patent, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "disposed" should be understood broadly. For example, they can refer to fixed connection or disposition, detachable connection or disposition, or integrated connection or disposition. Those skilled in the art will understand the specific meanings of the above terms in this patent based on the specific circumstances.

[0016] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "several" means two or more, unless otherwise specifically defined.

[0017] Example 1 The present invention provides a technical solution for a continuous fiber reinforced thermoplastic composite material: the material composition includes 38% PP-g-MAH; 55% glass fiber; 5% IFR / APP; 2% silane coupling agent KH-570; and an aluminum foil layer, the aluminum foil layer is selected as model 8011, has a content of 0.15 mm, and a roughness Ra of 1.5-2.5 μm.

[0018] A method for preparing a continuous fiber reinforced thermoplastic composite material specifically comprises the following steps: S1, fiber pretreatment; a1. Immerse the continuous fiber in an ethanol solution containing 1 wt% KH-570 and dry it; a2. Eliminate fiber bunching through electrostatic dispersion device; S2, preparing prepreg; b1. Melt-blending PP-g-MAH, composite flame retardant and 2 wt% antioxidant; b2, coated on the surface of continuous fiber through extruder to form a prepreg tape with a thickness of 0.2-0.3mm. Dimensional volume fraction 55%; S3, lamination molding; The prepreg tapes were stacked in the direction of 0° / 90° / 0° / 90° / 90° / 0° / 90° / 0° and placed in a hot press. After pressing and cooling, the composite material sheet was obtained. The hot press temperature was set to 180-190°C, the hot press pressure was set to 5 MPa, and the hot press time was set to 10 min. S4, aluminum foil composite; c1. Preheat the plasma-treated aluminum foil to 120°C; c2. Laminating the composite material surface with a silicone adhesive and hot pressing to form a dense coating layer. The hot pressing pressure is set to 0.8 MPa and the hot pressing temperature is set to 140°C. d1. Aluminum atoms on the surface of aluminum foil undergo oxidation reaction with oxygen to generate layer, the reaction equation is: , has excellent thermal insulation and chemical stability, which can prevent heat and oxygen from further penetrating into the interior of the material; d2, ammonium polyphosphate decomposes into and , the reaction equation is: , the molten polyphosphate has fluidity and can be filled Porosity and cracks in the layer; d3, polyphosphoric acid and metal oxides Reaction to form aluminum phosphate Or glassy polyphosphate, molten polyphosphate has fluidity and can be filled The pores and cracks in the layer further enhance the high temperature resistance and density of the barrier; d4. Polyphosphate melts at high temperature and wraps particles, It reacts with polyphosphoric acid to form aluminophosphate, forming a continuous glassy matrix. The reaction equation is: Reacts with polyphosphoric acid to form aluminophosphate ; d5. Oxide layer of aluminum foil It provides a rigid skeleton, and the polyphosphate generated by the decomposition of ammonium polyphosphate acts as a binder and reaction precursor, forming a ceramic barrier through physical filling and chemical reaction; Furthermore, polymer matrices (such as plastics and rubbers) soften and melt at high temperatures or when burning, forming high-temperature liquid droplets. The droplets carry a large amount of heat and may cause new fire sources when they drip onto the surfaces of other combustible materials.

[0019] Furthermore, the high thermal conductivity of the aluminum foil accelerates cooling Thermal conductivity of aluminum: The thermal conductivity of metallic aluminum is as high as 237 W / (m·K), which is much higher than that of the polymer matrix (usually <0.5 W / (m·K)).

[0020] Rapid heat dissipation: When the substrate is heated, the aluminum foil acts as a heat conduction network to quickly transfer local heat to the entire material or the environment (such as through heat convection or radiation).

[0021] The temperature gradient around the droplet increases, causing the melt to cool rapidly below its freezing point.

[0022] Furthermore, the physical anchoring effect of the aluminum foil mesh Mesh structure design: Aluminum foil is embedded in the matrix in a micron-scale mesh form (such as honeycomb or grid distribution).

[0023] Droplet capture and solidification: Melt flows into the mesh: Liquid droplets penetrate into the aluminum foil mesh due to surface tension or gravity.

[0024] Contact cooling and solidification: The molten drop contacts the surface of the highly thermally conductive aluminum foil, the heat is quickly conducted away, and the melt solidifies within the mesh.

[0025] Mechanical anchoring: The solidified molten droplet forms a mechanical interlocking structure with the aluminum foil mesh and cannot be separated from the substrate.

[0026] Furthermore, the quantitative mechanism of droplet number reduction is Inhibit droplet formation: The thermal conductivity of aluminum foil reduces the surface temperature of the substrate, slows down the melting rate of the polymer, and reduces the total amount of molten droplets.

[0027] Improved anchoring efficiency: The mesh structure provides a large number of anchor points, and more than 90% of the molten droplets are captured and solidified before dripping.

[0028] Droplet size control: The heat conduction of aluminum foil causes the droplet volume to shrink (rapid solidification), further reducing the ignition ability.

[0029] Furthermore, the synergistic flame retardancy and elimination of secondary ignition Thermal-mechanical coupling effect: Thermal insulation protection: The solidified molten droplets in the aluminum foil mesh form a local barrier, hindering the transfer of heat to the interior of the substrate.

[0030] Oxygen isolation: Anchored molten droplets block the pores on the material surface, reducing oxygen diffusion.

[0031] Changes in droplet behavior: The molten droplets that do not fall off participate in the formation of the carbonized layer instead of becoming an ignition source.

[0032] Furthermore, the Fourier heat conduction equation shows that the addition of aluminum foil significantly improves the overall thermal diffusion coefficient of the material (α=k / ρCpα=k / ρCp) and shortens the cooling time of the molten droplet.

[0033] As shown in Table 1 and Table 2, the final performance test: LOI: 36%; UL-94: V-0 (0 droplet); ; Tensile strength: 325MPa; Flexural strength: 425MPa; Aluminum foil peel strength: 10.2N / cm.

[0034] Comparative Example 1 A continuous fiber reinforced thermoplastic composite material technology solution is also provided: the material composition includes PP-g-MAH 40%; glass fiber 55%; IFR / APP 5%; silane coupling agent KH-570 0%; aluminum foil layer, selected model 8011, content 0.15mm, roughness Ra 1.5-2.5μm.

[0035] A method for preparing a continuous fiber reinforced thermoplastic composite material specifically comprises the following steps: S1, fiber pretreatment; a1. Immerse the continuous fiber in an ethanol solution containing 1 wt% KH-570 and dry it; a2. Eliminate fiber bunching through electrostatic dispersion device; S2, preparing prepreg; b1. Melt-blending PP-g-MAH, composite flame retardant and 2 wt% antioxidant; b2, coated on the surface of continuous fiber through extruder to form a prepreg tape with a thickness of 0.2-0.3mm. Dimensional volume fraction 55%; S3, lamination molding; The prepreg tapes were stacked in the direction of 0° / 90° / 0° / 90° / 90° / 0° / 90° / 0° and placed in a hot press. After pressing and cooling, the composite material sheet was obtained. The hot press temperature was set to 180-190°C, the hot press pressure was set to 5 MPa, and the hot press time was set to 10 min. S4, aluminum foil composite; c1. Preheat the plasma-treated aluminum foil to 120°C; c2. Laminating the composite material surface with a silicone adhesive and hot pressing to form a dense coating layer. The hot pressing pressure is set to 0.8 MPa and the hot pressing temperature is set to 140°C. d1. Aluminum atoms on the surface of aluminum foil undergo oxidation reaction with oxygen to generate layer, the reaction equation is: ; d2, ammonium polyphosphate decomposes into and , the reaction equation is: ; d3, polyphosphoric acid and metal oxides Reaction to form aluminum phosphate or glassy polyphosphate; d4. Polyphosphate melts at high temperature and wraps particles, It reacts with polyphosphoric acid to form aluminophosphate, forming a continuous glassy matrix; d5. Oxide layer of aluminum foil It provides a rigid skeleton, and the polyphosphate generated by the decomposition of ammonium polyphosphate acts as a binder and reaction precursor, forming a ceramic barrier through physical filling and chemical reaction; As shown in Table 1 and Table 2, the final performance test: LOI: 33%; UL-94: V-0 (0 droplet); ; Tensile strength: 325MPa; Flexural strength: 310MPa; Aluminum foil peel strength: 3.5N / cm.

[0036] Comparative Example 2 A continuous fiber reinforced thermoplastic composite material technology solution is also provided: the material composition includes PP-g-MAH 40%; glass fiber 55%; IFR / APP 5%; silane coupling agent KH-570 0%; aluminum foil layer, selected model 8011, content 0.15mm, roughness Ra 1.5-2.5μm.

[0037] A method for preparing a continuous fiber reinforced thermoplastic composite material specifically comprises the following steps: S1, fiber pretreatment; a1. Immerse the continuous fiber in an ethanol solution containing 1 wt% KH-570 and dry it; a2. Eliminate fiber bunching through electrostatic dispersion device; S2, preparing prepreg; b1. Melt-blending PP-g-MAH, composite flame retardant and 2 wt% antioxidant; b2, coated on the surface of continuous fiber through extruder to form a prepreg tape with a thickness of 0.2-0.3mm. Dimensional volume fraction 55%; S3, lamination molding; The prepreg tapes were stacked in the direction of 0° / 90° / 0° / 90° / 90° / 0° / 90° / 0° and placed in a hot press. After pressing and cooling, the composite material sheet was obtained. The hot press temperature was set to 180-190°C, the hot press pressure was set to 5 MPa, and the hot press time was set to 10 min. S4, aluminum foil composite; c1. Preheat the plasma-treated aluminum foil to 120°C; c2. Laminating the composite material surface with a silicone adhesive and hot pressing to form a dense coating layer. The hot pressing pressure is set to 0.8 MPa and the hot pressing temperature is set to 140°C. d1. Aluminum atoms on the surface of aluminum foil undergo oxidation reaction with oxygen to generate layer, the reaction equation is: ; d2, ammonium polyphosphate decomposes into and , the reaction equation is: ; d3, polyphosphoric acid and metal oxides Reaction to form aluminum phosphate or glassy polyphosphate; d4. Polyphosphate melts at high temperature and wraps particles, It reacts with polyphosphoric acid to form aluminophosphate, forming a continuous glassy matrix; d5. Oxide layer of aluminum foil It provides a rigid skeleton, and the polyphosphate generated by the decomposition of ammonium polyphosphate acts as a binder and reaction precursor, forming a ceramic barrier through physical filling and chemical reaction; As shown in Table 1 and Table 2, the final performance test: LOI: 25%; UL-94: V-0 (0 droplet); ; Tensile strength: 290MPa; Flexural strength: 375MPa; Aluminum foil peel strength: 0N / cm.

[0038] Table 1 Table 2 Through Example 1, Comparative Example 1 and Comparative Example 2, the performance of the samples with the interface modifier added is significantly better than that of the samples without the interface modifier. The performance of the samples with aluminum foil coating is significantly better than that of the samples without aluminum foil coating. Safety performance: LOI reaches 36%, far exceeding the V0 level threshold of 28%; THR is 45MJ / m², meeting aviation grade requirements. Mechanical properties: tensile strength of 325MPa, maintaining the advantages of fiber reinforcement. Process compatibility: hot pressing temperature is less than or equal to 190℃, suitable for industrial production. The current electric vehicle battery pack THR requirement is less than or equal to 50MJ / m². Compared with the metal shell, this solution reduces the weight by 30%, passes the GB / T5169.38 needle puncture test, and the aluminum foil is resistant to bursting. Expansion areas include aerospace firewalls and flame retardant linings for high-rise buildings.

[0039] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A continuous fiber reinforced thermoplastic composite material, characterized in that: The material composition includes 35-40% polypropylene matrix with a melt index of 10-30g / 10min; 55% continuous fiber, which is unidirectionally arranged glass fiber, carbon fiber or basalt fiber, with a single fiber diameter of 9-15μm; 4-6% composite flame retardant, which is a mixture of intumescent flame retardant and ammonium polyphosphate in a mass ratio of 2:1; 1-2% interface modifier, which is a silane coupling agent KH-570 or PP-g-MAH; and an aluminum foil layer with a roughness Ra of 1.5-2.5μm.

2. The method for preparing a continuous fiber reinforced thermoplastic composite material according to claim 1, wherein: The preparation method specifically comprises the following steps: S1, fiber pretreatment; S2, preparing prepreg; S3, lamination molding; S4, aluminum foil composite.

3. The method for preparing a continuous fiber reinforced thermoplastic composite material according to claim 2, wherein: The step S1 specifically includes the following steps: a1. Immerse the continuous fiber in an ethanol solution containing 1 wt% KH-570 and dry it; a2. Eliminate fiber bunching through electrostatic dispersion device.

4. The method for preparing a continuous fiber reinforced thermoplastic composite material according to claim 2, wherein: The step S2 specifically includes the following steps: b1. Melt-blending PP-g-MAH, composite flame retardant and 2 wt% antioxidant; b2. Coated on the surface of continuous fiber through extruder to form a prepreg with a thickness of 0.2-0.3mm Belt, fiber volume fraction 55%.

5. The method for preparing a continuous fiber reinforced thermoplastic composite material according to claim 2, wherein: In step S3, the prepreg tapes are stacked in the direction of 0° / 90° / 0° / 90° / 90° / 0° / 90° / 0° and placed in a hot press, and pressed and cooled to obtain a composite material plate.

6. The method for preparing a continuous fiber reinforced thermoplastic composite material according to claim 2, wherein: The step S4 specifically includes the following steps: c1. Preheat the plasma-treated aluminum foil to 120°C; c2. Bond the composite material surface with silicone adhesive and form a dense coating layer after hot pressing.

7. The method for preparing a continuous fiber reinforced thermoplastic composite material according to claim 6, characterized in that: The step c2 specifically includes the following steps: d1. Aluminum atoms on the surface of aluminum foil undergo oxidation reaction with oxygen to generate layer, the reaction equation is: ; d2, ammonium polyphosphate decomposes into and , the reaction equation is: ； d3, polyphosphoric acid and metal oxides Reaction to form aluminum phosphate or glassy polyphosphate; d4, polyphosphate melts at high temperature and wraps particles, It reacts with polyphosphoric acid to form aluminophosphate, forming a continuous glassy matrix; d5. Oxide layer of aluminum foil It provides a rigid skeleton, and the polyphosphate generated by the decomposition of ammonium polyphosphate acts as a binder and reaction precursor, forming a ceramic barrier through physical filling and chemical reaction.

8. The method for preparing a continuous fiber reinforced thermoplastic composite material according to claim 5, characterized in that: The hot press temperature was set to 180-190°C, the hot press pressure was set to 5 MPa, and the hot press time was set to 10 min.

9. The method for preparing a continuous fiber reinforced thermoplastic composite material according to claim 6, wherein: In step c2, the hot pressing pressure is set to 0.8 MPa and the hot pressing temperature is set to 140°C.

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