Fiber composite protective film as well as preparation method and application thereof

Abstract

The invention relates to the technical field of protective films, in particular to a fiber composite protective film and a preparation method and application thereof. The preparation method of the fiber composite protective film comprises the following steps: preparing a fiber reinforced layer; and preparing a substrate and a functional layer, and performing hot-pressing compounding on the substrate, the fiber reinforced layer and the functional layer to obtain the fiber composite protective film. The fiber reinforced layer is prepared from the following raw material components in parts by weight: 12 to 18 parts of modified fiber, 6 to 8 parts of epoxy resin acrylate, 48 to 54 parts of thermoplastic polyurethane elastomer, 0.8 to 1.5 parts of compatilizer and 3 to 4 parts of curing agent. According to the fiber composite protective film prepared by the preparation method disclosed by the invention, the functional layer can be effectively attached to the base layer, the performance of the base layer is improved, and the overall tensile strength and elongation at break of the fiber composite protective film can be improved.

Description

Technical Field

[0001] This invention relates to the field of protective film technology, and in particular to a fiber composite protective film, its preparation method, and its application. Background Technology

[0002] With the rapid development of industries such as electronics, automobiles, and construction, the comprehensive performance requirements for surface protection materials are increasing. Fiber composite protective films, due to their combination of lightweight and reinforcing properties, have become one of the mainstream protective materials. However, existing technologies for fiber composite protective films generally suffer from core technical bottlenecks: firstly, insufficient interfacial bonding between fibers and the resin matrix, leading to stress transfer failure and limited mechanical properties; secondly, poor compatibility during multi-component blending, resulting in phase separation and affecting product stability; and thirdly, unreasonable preparation processes, such as premature curing agent reaction and uneven component dispersion, further deteriorate overall performance. Furthermore, traditional protective films struggle to simultaneously meet the demands for high mechanical strength, excellent interlayer bonding, and environmental resistance, limiting their application in complex scenarios. Therefore, there is an urgent need to develop a fiber composite protective film preparation technology that optimizes component synergy and preparation processes. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to solve at least one of the technical problems mentioned above.

[0004] The solution to the technical problem of this invention is: In a first aspect, this application provides a method for preparing a fiber composite protective film, comprising the following steps: Preparation of fiber reinforcement layer; A substrate and a functional layer are configured, and the substrate, the fiber reinforcement layer and the functional layer are hot-pressed together to obtain the fiber composite protective film; The fiber reinforcement layer comprises the following components by weight: The mixture contains 12-18 parts modified fiber, 6-8 parts epoxy resin acrylate, 48-54 parts thermoplastic polyurethane elastomer, 0.8-1.5 parts compatibilizer, and 3-4 parts curing agent.

[0005] Furthermore, the method for preparing the modified fiber includes the following steps: The nanofiller was dispersed in deionized water to obtain a nanofiller dispersion. A silane coupling agent is added to the nanofiller dispersion, and the mixture is then prepared to obtain a composite modified solution. The carbon fiber was placed in the composite modification liquid, heated and stirred at 60-80℃ for 2-4 hours, filtered, and then vacuum dried.

[0006] Furthermore, the nanofiller is a combination of nano-silica and nano-alumina, wherein the weight ratio of nano-silica to nano-alumina is 2:1-2; The carbon fibers have a length of 100-500 μm and a diameter of 5-20 μm.

[0007] Furthermore, the silane coupling agent is a combination of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, wherein the weight ratio of γ-aminopropyltriethoxysilane to γ-glycidoxypropyltrimethoxysilane is 4-6:1.

[0008] Furthermore, in the composite modified liquid, the mass concentration of the silane coupling agent is 5-15%, and the mass concentration of the nanofiller is 2-4%. The weight ratio of the carbon fiber to the nanofiller is 7-9:1.

[0009] Furthermore, the epoxy resin acrylate is epoxy resin E-51; The thermoplastic polyurethane elastomer is TPU-1185A; The compatibilizer is BYK-A 515; The curing agent is dicyandiamide.

[0010] Furthermore, the step of preparing the fiber reinforcement layer includes: The thermoplastic polyurethane elastomer is divided into a first TPU, a second TPU, and a third TPU, with the weight ratio of the first TPU, the second TPU, and the third TPU being 6:3:1. The epoxy resin acrylate and the first TPU are premixed at 50-60°C to prepare the first masterbatch; The second TPU, the compatibilizer, and the modified fiber are premixed to form a second masterbatch; The third TPU and the curing agent are premixed to form the third masterbatch; The first masterbatch and the second masterbatch are melt-blended by the first screw extruder at an extrusion temperature of 160-180°C and flow out from the die to form a film. The third masterbatch is melt-blended by the second screw extruder at a temperature of 110-120°C and fed into the die before the first screw extruder for blending and simultaneous extrusion.

[0011] Furthermore, the hot-pressing composite step includes: The fiber reinforcement layer and the functional layer are sequentially applied to the base layer and hot-pressed at 100-130℃ with a pressure of 0.5-1.5MPa and a heat preservation time of 10-30min.

[0012] Secondly, this application provides a fiber composite protective film, which is prepared by the fiber composite protective film preparation method described in the first aspect.

[0013] Thirdly, the application of a fiber composite protective film as described in the second aspect in the surface protection of electronic device housings, automotive parts, or building materials.

[0014] The beneficial effects of this invention are as follows: a low proportion of epoxy resin acrylate can form an interpenetrating system with a high proportion of thermoplastic polyurethane elastomer, providing rigid support and flexible cushioning. The epoxy resin acrylate provides a rigid skeleton to enhance strength, while the thermoplastic polyurethane elastomer ensures the toughness of the matrix. Modified fibers are uniformly dispersed in the resin matrix, allowing stress to be transferred through interfacial interactions, thus improving the strength of the fiber reinforcement layer. The compatibilizer improves the interfacial compatibility of the components, and the curing agent increases the resin crosslinking density, which helps overcome limitations caused by excessively high crosslinking strength or insufficient strength due to the need for flexibility. This effectively attaches the functional layer to the base layer and improves its performance, contributing to increased overall tensile strength and elongation at break of the fiber composite protective film. Detailed Implementation

[0016] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages mentioned herein do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0017] This application provides a method for preparing a fiber composite protective film, comprising the following steps: Preparation of fiber reinforcement layer; A fiber composite protective film is obtained by hot-pressing the substrate, fiber reinforcement layer, and functional layer together with a substrate and a functional layer.

[0018] The fiber reinforcement layer, calculated by weight, comprises the following components: The mixture contains 12-18 parts modified fiber, 6-8 parts epoxy resin acrylate, 48-54 parts thermoplastic polyurethane elastomer, 0.8-1.5 parts compatibilizer, and 3-4 parts curing agent.

[0019] In this application, a low proportion of epoxy resin acrylate forms an interpenetrating system with a high proportion of thermoplastic polyurethane elastomer, providing both rigid support and flexible cushioning. The epoxy resin acrylate provides a rigid skeleton to enhance strength, while the thermoplastic polyurethane elastomer ensures the toughness of the matrix. Modified fibers are uniformly dispersed in the resin matrix, allowing stress to be transferred through interfacial interactions, thereby increasing the strength of the fiber reinforcement layer. The compatibilizer improves the interfacial compatibility of the components, and the curing agent increases the resin crosslinking density, which helps overcome limitations caused by excessively high crosslinking strength or insufficient strength due to the need for flexibility. This effectively attaches the functional layer to the base layer and improves its performance, contributing to an increase in the overall tensile strength and elongation at break of the fiber composite protective film.

[0020] Furthermore, the method for preparing modified fibers includes the following steps: The nanofiller was dispersed in deionized water to obtain a nanofiller dispersion. A silane coupling agent was added to the nanofiller dispersion, and the mixture was then prepared to obtain a composite modified solution. Carbon fibers are placed in a composite modification liquid, heated and stirred at 60-80℃ for 2-4 hours, filtered, and then vacuum dried.

[0021] In this application, the nanofiller is first dispersed in deionized water to form a stable dispersion, and then a silane coupling agent is added, which allows the silane coupling agent molecules to uniformly coat the surface of the nanofiller. Subsequently, when the carbon fiber reacts with the composite modification liquid at 60-80℃, the alkoxy groups of the silane coupling agent hydrolyze to generate silanol groups. On the one hand, these silanol groups condense with the hydroxyl groups on the carbon fiber surface to form a chemical bond, and on the other hand, they bond with the surface groups of the nanofiller. This allows the nanofiller to be "bridged" and fixed on the carbon fiber surface by the silane coupling agent. This not only improves the surface roughness and interfacial bonding force of the carbon fiber and enhances the skeletal effect of the carbon fiber in the fiber reinforcement layer, but also utilizes the reinforcing effect of the nanofiller to fill the surface defects of the carbon fiber and improve the filling effect in the fiber reinforcement layer, thereby improving the mechanical transmission effect and ensuring the reinforcement effect of the carbon fiber.

[0022] Furthermore, the nanofiller is a combination of nano-silica and nano-alumina, with a weight ratio of nano-silica to nano-alumina of 2:1-2; The length of the carbon fiber is 100-500μm, and the diameter is 5-20μm; The silane coupling agent is a combination of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, with a weight ratio of 4-6:1.

[0023] In this application, nano-silica and nano-alumina are combined in a weight ratio of 2:1-2. The complementary particle size distribution and reinforcing properties of the two can be used to more comprehensively fill the voids on the surface of carbon fibers, while improving the wear resistance and high temperature resistance of the modified fibers. Nano-silica can enhance the compatibility of carbon fibers with silane coupling agents, while nano-alumina can improve the wear resistance of carbon fibers, prevent the protective film from failing in some frequent vibration scenarios, and improve the durability of carbon fibers. The silane coupling agent is a combination of γ-aminopropyltriethoxysilane (KH550) and γ-glycidoxypropyltrimethoxysilane (KH560) in a weight ratio of 4-6:1. The amino group of KH550 can react with the active groups in the resin matrix, and the epoxy group of KH560 can combine with the hydroxyl groups on the carbon fiber surface and the nanofiller groups. The synergistic effect of the two enhances the interfacial interaction between the modified fiber and the resin matrix. When combined with carbon fibers with a length of 100-500μm and a diameter of 5-20μm, a uniform reinforcing network can be formed in the resin matrix, further improving the stress transfer efficiency and ensuring its modification effect.

[0024] Furthermore, in the composite modified liquid, the mass concentration of the silane coupling agent is 5-15%, and the mass concentration of the nanofiller is 2-4%. The weight ratio of carbon fiber to nanofiller is 7-9:1.

[0025] In this application, the mass concentration of 5-15% silane coupling agent and 2-4% nanofiller in the composite modification solution ensures that the silane coupling agent and nanofiller form a stable composite coating layer. This avoids component agglomeration caused by excessive concentration and insufficient modification caused by insufficient concentration. The carbon fiber and nanofiller are mixed in a weight ratio of 7-9:1, which allows the nanofiller to uniformly cover the carbon fiber surface without agglomeration. At the same time, it avoids the increase in brittleness caused by excessive nanofiller, ensuring that the modified carbon fiber has both excellent interfacial bonding and mechanical properties, laying the foundation for the subsequent performance improvement of the fiber reinforcement layer.

[0026] Furthermore, the epoxy resin acrylate is epoxy resin E-51; The thermoplastic polyurethane elastomer is TPU-1185A; The compatibilizer is BYK-A 515; The curing agent is dicyandiamide.

[0027] In this application, epoxy resin E-51 has low viscosity and high epoxy value, which can form a good blending system with TPU-1185A. The molecular chains of the two interpenetrate each other, synergistically improving the strength and toughness of the resin matrix. The compatibilizer BYK-A 515 specifically improves the interfacial compatibility between epoxy resin and TPU, reduces interfacial tension, and avoids phase separation. The curing agent dicyandiamide can undergo a crosslinking reaction with epoxy resin E-51 to form a stable three-dimensional crosslinking network, while not reacting adversely with TPU. The synergistic effect of the four components simultaneously improves the structural stability, mechanical properties, and environmental resistance of the fiber reinforcement layer.

[0028] Furthermore, the steps for preparing the fiber reinforcement layer include: The thermoplastic polyurethane elastomer is divided into a first TPU, a second TPU, and a third TPU, with a weight ratio of 6:3:1. The epoxy resin acrylate and the first TPU are premixed at 50-60℃ to prepare the first masterbatch; The second TPU, compatibilizer, and modified fiber are premixed to form the second masterbatch; The third TPU and curing agent are premixed to form the third masterbatch; The first and second masterbatches are melt-blended and mixed by the first screw extrusion at a temperature of 160-180°C, and flow out from the die to form a film. The third masterbatch is melt-blended and mixed by the second screw extrusion at a temperature of 110-120°C. It is fed into the die before the first screw extrusion and extruded simultaneously.

[0029] In this application, by dividing TPU into three parts in a weight ratio of 6:3:1 and preparing masterbatches with epoxy resin, modified fibers, compatibilizer, and curing agent respectively, the agglomeration and uneven distribution caused by direct mixing of the components can be avoided. The first masterbatch (epoxy resin + first TPU) is premixed at 50-60℃, which can make the epoxy resin uniformly dispersed in the TPU matrix, so as to improve the degree of blending and form a stable rigid support phase in the later stage. The second masterbatch (second TPU + compatibilizer + modified fiber) is premixed, which can improve the interfacial bonding force between modified fiber and TPU through the action of compatibilizer, which facilitates subsequent melt blending. The third masterbatch (third TPU + curing agent) is fed into the first screw at 110-120℃, which can prevent the curing agent from curing prematurely in the high-temperature section, and at the same time ensure that it reacts fully with epoxy resin during the extrusion process (for about 10-15 seconds), which is conducive to the uniform distribution and full cross-linking of fiber reinforcement layer components, and improves the mechanical properties of the product.

[0030] Furthermore, the hot-pressing composite step includes: The fiber reinforcement layer and the functional layer are then applied to the base layer in sequence, and hot-pressed at 100-130℃ with a pressure of 0.5-1.5MPa and a heat preservation time of 10-30min.

[0031] In this application, the hot-pressing temperature of 100-130℃ allows for slight softening of the interfacial materials, promoting molecular diffusion while preventing functional layer degradation or substrate deformation caused by high temperatures. A pressure of 0.5-1.5 MPa ensures tight adhesion between layers, eliminating interlayer voids; a holding time of 10-30 minutes guarantees sufficient reaction of interfacial molecules, forming a stable interfacial bonding layer. The synergistic effect of these three factors enhances interlayer peel strength, prevents delamination during use, and fully preserves the inherent functions of each layer.

[0032] This application also provides a fiber composite protective film, which is prepared by the fiber composite protective film preparation method described above. The fiber composite protective film obtained by this application exhibits synergistic reinforcement between the modified fibers and the resin matrix, synergistic adhesion between layers, and synergistic effects of the functional components, resulting in a protective film with both good mechanical strength and interlayer bonding force, reducing the risk of separation, and facilitating a comprehensive improvement in protective performance.

[0033] This application also provides an application of the fiber composite protective film described above in the surface protection of electronic device housings, automotive parts, or building materials. In the electronic device housing protection scenario, the high mechanical strength of the protective film can withstand daily friction and impact, while its hydrophobic and anti-fouling properties keep the housing clean. In the automotive parts protection scenario, its high temperature resistance and aging resistance can adapt to extreme environments, and its interlayer bonding strength ensures long-term adhesion without peeling. In the building material protection scenario, its impact resistance and UV resistance can resist external environmental corrosion. The comprehensive performance of the protective film is precisely matched to the protection requirements of various application scenarios, achieving efficient protection in different scenarios and broadening the application range of the product.

[0034] The following specific examples provide further details.

[0035] Example 1 The method for preparing the fiber composite protective film in Example 1 includes the following steps: (1) Preparation of modified fibers: (11) Preparation of nanofiller dispersion: 20g of nano silica (particle size 30nm) and 10g of nano alumina (particle size 40nm) were dispersed in 1000g of deionized water and ultrasonically dispersed for 45min to obtain nanofiller dispersion (nanofiller mass concentration 3%). (12) Preparation of composite modified liquid: Add 30g of silane coupling agent (γ-aminopropyltriethoxysilane KH550 and γ-glycidoxypropyltrimethoxysilane KH560 mixed at a weight ratio of 5:1) to the above nanofiller dispersion, stir to dissolve, and obtain a composite modified liquid with a silane coupling agent mass concentration of 5%. (13) Modification treatment: 270g of carbon fiber (300μm in length and 10μm in diameter) was placed in the composite modification liquid, heated and stirred at 70℃ for 3h, and ultrasonically assisted dispersion for 10min every 30min during the process. After filtration, it was placed in a vacuum drying oven at 90℃ for 3h to obtain modified fiber (weight ratio of carbon fiber to nanofiller 9:1).

[0036] (2) Preparation of fiber reinforcement layer: (21) Raw material ratio (by weight): 15 parts modified fiber, 7 parts epoxy resin acrylate (E-51), 51 parts thermoplastic polyurethane elastomer (TPU-1185A), 1.2 parts compatibilizer (BYK-A 515), and 3.5 parts curing agent (dicyandiamide); (22) Masterbatch preparation: 51 parts of TPU were divided into 30.6 parts of first TPU, 15.3 parts of second TPU, and 5.1 parts of third TPU in a weight ratio of 6:3:1; 7 parts of E-51 and 30.6 parts of first TPU were premixed at 55°C for 30 min to prepare the first masterbatch; 15.3 parts of second TPU, 1.2 parts of BYK-A 515 and 15 parts of modified fiber were premixed for 20 min to prepare the second masterbatch; 5.1 parts of third TPU and 3.5 parts of dicyandiamide were premixed for 15 min to prepare the third masterbatch; (23) Segmented extrusion: The first masterbatch and the second masterbatch are melt-blended through the first screw extruder at an extrusion temperature of 170°C; the third masterbatch is melt-blended through the second screw extruder at a temperature of 115°C. The third masterbatch is fed into the die of the first screw extruder for blending and extrusion into a film simultaneously to obtain a fiber-reinforced layer.

[0037] (3) Hot pressing composite: (31) Configuration of substrate and functional layer: The substrate is a 100μm thick polyolefin film, and the functional layer is a 10μm thick fluorinated acrylate copolymer coating; (32) Hot pressing process: The fiber reinforcement layer and the functional layer are sequentially applied to the substrate and hot pressed at 120°C with a pressure of 1.0 MPa and a holding time of 20 min. After cooling, the fiber composite protective film of Example 1 is obtained.

[0038] Example 2 The difference from Example 1 is that in the modified fiber preparation step, the mass concentration of silane coupling agent in the composite modification liquid is 10% (silane coupling agent addition amount 60g), the mass concentration of nanofiller is 4% (nano silica 26.7g, nano alumina 13.3g), and the weight ratio of carbon fiber to nanofiller is 7:1 (carbon fiber 280g).

[0039] Example 3 The difference from Example 1 is that in the fiber reinforcement layer preparation step, the TPU part ratio is adjusted from 6:3:1 to 5:4:1 (25.5 parts of first TPU, 20.4 parts of second TPU, and 5.1 parts of third TPU), and the premixing temperature of the first masterbatch is 60°C.

[0040] Example 4 The difference from Example 1 is that in the hot pressing composite step, the hot pressing temperature is 130°C, the pressure is 1.5MPa, and the holding time is 30min.

[0041] Example 5 The difference from Example 1 is that the ratio of silane coupling agent is 4:1 (KH550 24g, KH560 6g), and the ratio of nanofiller is 2:2 (nano silica 15g, nano alumina 15g).

[0042] Comparative Example 1 The difference from Example 1 is that the synergistic modification of "nanofiller + silane coupling agent" was not used. Instead, only KH550 single silane coupling agent was used to modify the carbon fiber (silane coupling agent addition amount 30g, no nanofiller).

[0043] Comparative Example 2 The difference from Example 1 is that the masterbatch segmented preparation process was not used when preparing the fiber reinforcement layer. Instead, all raw materials (E-51, TPU, compatibilizer, modified fiber, curing agent) were directly mixed and fed into the screw extruder in one go, with an extrusion temperature of 170°C.

[0044] Comparative Example 3 The difference from Example 1 is that no compatibilizer (BYK-A 515) was added to the fiber reinforcement layer raw material, and the amount of epoxy resin acrylate (E-51) added was adjusted to 15 parts, and the amount of TPU added was adjusted to 43 parts (keeping the total amount of resin unchanged).

[0045] The protective films prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to performance tests. The performance test items are as follows: (I) Tensile strength: tested using a universal testing machine, with sample type I, tensile rate of 50 mm / min, 5 samples per group, and average value was taken; (II) Elongation at break: recorded synchronously with the tensile strength test, the elongation at break was recorded by the data acquisition system of the universal testing machine, and the elongation at break was calculated. 5 samples per group were tested, and average value was taken; (III) Peel strength: peel samples of the substrate-fiber reinforcement layer and fiber reinforcement layer-functional layer were prepared respectively, with a sample width of 25 mm. A 180° peel test was performed using a universal testing machine, with a tensile rate of 100 mm / min. The force value during the peel process was recorded, and the average value was calculated. Peel strength: 5 samples were tested in each group, and the average value was taken; (IV) Tensile strength retention rate after aging at 180℃: The samples were placed in a 180℃ forced-air oven for 500 hours, and then placed in a standard environment (temperature 23±2℃, relative humidity 50±5%) for 24 hours. The tensile strength of the aged samples was then tested according to the test method corresponding to "Tensile Strength". Tensile strength retention rate = (tensile strength after aging / tensile strength before aging) × 100%; (V) Abrasion resistance: The Taber abrasion tester was used, with a CS-17 grinding wheel, a load of 500g, and a rotation speed of 1000 rpm. Before the test, the mass of the sample was weighed with an electronic balance with an accuracy of 0.1mg. After the test, the mass was weighed again. Abrasion resistance = mass before test - mass after test. 3 samples were tested in each group, and the average value was taken.

[0046] The performance test results for Examples 1-5 and Comparative Examples 1-3D are shown in Table 1: Table 1 Comparison reveals that Example 2, by optimizing the concentration of the composite modified liquid, improved interfacial bonding, resulting in optimal tensile strength and peel strength. Example 3, by adjusting the TPU component ratio and premixing temperature, slightly improved the elongation at break. Example 4, by optimizing hot-pressing parameters, further enhanced interlayer bonding. Example 5, by adjusting the ratio of silane coupling agent and nanofiller, maintained good overall performance, demonstrating the adjustability and adaptability of the technical parameters in this application. Comparative Example 1, lacking the synergistic modification of nanofiller and silane coupling agent, showed a significant decrease in tensile strength and peel strength, but an increase in abrasion resistance, proving that synergistic modification can improve interfacial bonding and reinforcement effects. Comparative Example 2, lacking the segmented masterbatch preparation process, resulted in uneven component dispersion, leading to a decrease in tensile strength and elongation at break, proving that the segmented masterbatch process can ensure uniform component dispersion and sufficient cross-linking. Comparative Example 3, lacking a compatibilizer and with an increased epoxy resin ratio, resulted in poor compatibility among components and deteriorated overall performance, indicating that a compatibilizer and a reasonable resin ratio help ensure system stability.

[0047] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for preparing a fiber composite protective film, characterized in that, Includes the following steps: Preparation of fiber reinforcement layer; A substrate and a functional layer are configured, and the substrate, the fiber reinforcement layer and the functional layer are hot-pressed together to obtain the fiber composite protective film; The fiber reinforcement layer comprises the following components by weight: The mixture contains 12-18 parts modified fiber, 6-8 parts epoxy resin acrylate, 48-54 parts thermoplastic polyurethane elastomer, 0.8-1.5 parts compatibilizer, and 3-4 parts curing agent.

2. The method for preparing the fiber composite protective film according to claim 1, characterized in that, The method for preparing the modified fiber includes the following steps: The nanofiller was dispersed in deionized water to obtain a nanofiller dispersion. A silane coupling agent is added to the nanofiller dispersion, and the mixture is then prepared to obtain a composite modified solution. The carbon fiber was placed in the composite modification liquid, heated and stirred at 60-80℃ for 2-4 hours, filtered, and then vacuum dried.

3. The method for preparing the fiber composite protective film according to claim 2, characterized in that, The nanofiller is a combination of nano-silica and nano-alumina, and the weight ratio of nano-silica to nano-alumina is 2:1-2. The carbon fibers have a length of 100-500 μm and a diameter of 5-20 μm.

4. The method for preparing the fiber composite protective film according to claim 3, characterized in that, The silane coupling agent is a combination of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, wherein the weight ratio of γ-aminopropyltriethoxysilane to γ-glycidoxypropyltrimethoxysilane is 4-6:

1.

5. The method for preparing the fiber composite protective film according to claim 4, characterized in that, In the composite modified liquid, the mass concentration of the silane coupling agent is 5-15%, and the mass concentration of the nanofiller is 2-4%. The weight ratio of the carbon fiber to the nanofiller is 7-9:

1.

6. The method for preparing the fiber composite protective film according to claim 1, characterized in that, The epoxy resin acrylate is epoxy resin E-51; The thermoplastic polyurethane elastomer is TPU-1185A; The compatibilizer is BYK-A 515; The curing agent is dicyandiamide.

7. The method for preparing the fiber composite protective film according to claim 6, characterized in that, The step of preparing the fiber reinforcement layer includes: The thermoplastic polyurethane elastomer is divided into a first TPU, a second TPU, and a third TPU, with the weight ratio of the first TPU, the second TPU, and the third TPU being 6:3:

1. The epoxy resin acrylate and the first TPU are premixed at 50-60°C to prepare the first masterbatch; The second TPU, the compatibilizer, and the modified fiber are premixed to form a second masterbatch; The third TPU and the curing agent are premixed to form the third masterbatch; The first masterbatch and the second masterbatch are melt-blended by the first screw extruder at an extrusion temperature of 160-180°C and flow out from the die to form a film. The third masterbatch is melt-blended by the second screw extruder at a temperature of 110-120°C and fed into the die before the first screw extruder for blending and simultaneous extrusion.

8. The method for preparing the fiber composite protective film according to claim 1, characterized in that, The hot-pressing composite step includes: The fiber reinforcement layer and the functional layer are sequentially applied to the base layer and hot-pressed at 100-130℃ with a pressure of 0.5-1.5MPa and a heat preservation time of 10-30min.

9. A fiber composite protective film, characterized in that, It is prepared by the method for preparing fiber composite protective film as described in any one of claims 1-8.

10. The application of the fiber composite protective film as described in claim 9 in the surface protection of electronic device housings, automotive parts or building panels.

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