Fire-extinguishing and flame-retardant lightweight composite material plate with stable structure as well as preparation method and application of fire-extinguishing and flame-retardant lightweight composite material plate
By using a three-layer composite material sheet design and a continuous hot-pressing process, the problems of single-function and insufficient safety protection of new energy battery shell materials have been solved. This has resulted in structural stability, fire extinguishing and flame retardancy, and lightweighting, thereby improving battery safety performance and reducing production costs.
Patent Information
- Application Number
- CN202610122874.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-29
- Publication Date
- 2026-05-01
AI Technical Summary
Existing new energy battery casing materials have limited functionality, insufficient safety protection performance, difficulty in achieving structural stability, fire extinguishing and flame retardancy, and lightweighting, and have high production costs and complex processes, failing to meet high standards of battery safety protection requirements.
The lightweight composite material sheet is designed with a protective outer layer, an energy-absorbing buffer layer, and a fire-retardant inner layer, which are sequentially composited from the outside to the inside. It is integrally formed through a continuous hot-pressing composite process, and the selection of components and materials for each layer is optimized to achieve multi-functional integration and performance improvement.
It achieves structural stability, fire retardancy, and lightweighting of the battery casing, improves safety performance, reduces production costs, simplifies the production process, and possesses excellent impact and puncture resistance as well as highly efficient fire extinguishing effect.
Smart Images
Figure SMS_1
Abstract
Description
A structurally stable, fire-extinguishing, and flame-retardant lightweight composite material sheet, its preparation method, and its application. Technical Field
[0001] This invention relates to the field of composite material technology, specifically to a structurally stable, fire-retardant, lightweight composite material sheet, a method for preparing the composite material sheet, and the application of the composite material sheet. Background Technology
[0002] As a core component in new energy vehicles and energy storage systems, the safety performance of new energy batteries directly determines the reliability of equipment operation and the safety of personnel. The battery casing, acting as a "protective shield" for the battery module, plays a crucial role. It not only supports and secures the battery module's structure but also provides robust protection under extreme conditions such as collisions, compression, and punctures. Furthermore, it plays a key role in flame retardancy, fire extinguishing, and heat insulation in the event of thermal runaway leading to high temperatures, combustion, or explosions, thus comprehensively safeguarding battery safety.
[0003] Currently, the manufacturing materials for new energy battery casings are mainly divided into two categories: metallic materials and traditional composite materials. Among them, metallic materials, mainly steel and aluminum alloys, became the mainstream choice in the early stages due to their high structural strength; traditional composite materials were developed to meet the demand for lightweighting and have significant improvements in weight control compared to metallic materials. Together, they constitute the current technological system for battery casings and are widely used in various new energy-related equipment.
[0004] Existing technologies face numerous unresolved issues, failing to meet the high standards required for battery safety. While metal casings offer sufficient strength, their weight is excessive, typically accounting for 20%–30% of the battery pack's total weight, severely limiting the device's range. Furthermore, they are prone to plastic deformation and cracking during collisions or thermal runaway, failing to effectively prevent heat spread. Their excellent thermal conductivity can even accelerate fire propagation, as evidenced by recent battery explosions following electric vehicle collisions, highlighting their safety shortcomings. Traditional composite materials, while achieving lightweighting, offer limited functionality, mostly focusing on strength or weight optimization, lacking integrated functions such as energy absorption, explosion protection, and fire extinguishing. Even with the addition of flame retardants, they cannot actively extinguish fires during thermal runaway and suffer from issues such as weak fiber-resin matrix bonding, low interlaminar shear strength, complex molding processes, and high costs, hindering large-scale application. Summary of the Invention
[0005] The technical problem to be solved by this invention is to provide a lightweight composite material sheet with stable structure and fire extinguishing and flame retardant properties. This aims to solve the problems of single function and insufficient safety protection performance of existing new energy battery shells, and to achieve integrated functions of structural stability, fire extinguishing and flame retardant properties and lightweight, thereby improving the overall safety protection performance of the battery shell, while simplifying the production process and reducing production costs.
[0006] To solve this technical problem, the present invention adopts the following technical solution: a structurally stable, fire-extinguishing, and flame-retardant lightweight composite material sheet, characterized in that it comprises, from the outside to the inside, a protective surface layer, an energy-absorbing buffer layer, and a fire-extinguishing and flame-retardant inner layer, which are integrally formed into a sheet through a continuous hot-pressing composite process; the mass percentage of each layer is: protective surface layer 30%–45%, energy-absorbing buffer layer 25%–40%, and fire-extinguishing and flame-retardant inner layer 20%–35%; the protective surface layer is composed of the following components by mass percentage: resin matrix 40%. The energy-absorbing buffer layer comprises two layers of resin-impregnated fiber cloth and a lightweight core material located between the two layers of fiber cloth; the resin of the impregnated fiber cloth is compatible with the resin matrix of the protective surface layer, and the two have the same composition or are compatible; the fire-extinguishing and flame-retardant inner layer is composed of the following components by mass percentage: base carrier 45%–55%, fire-extinguishing functional filler 35%–45%, binder 5%–10%, and dispersant 1%–3%.
[0007] Furthermore, the resin matrix in the protective surface layer is specifically a thermosetting epoxy resin or a thermoplastic polypropylene; the reinforcing fiber in the protective surface layer is specifically basalt fiber or carbon fiber, with a length of 10–25 mm; the flame retardant synergist in the protective surface layer is specifically a compound of nano-magnesium hydroxide and expanded graphite, with a mass ratio of nano-magnesium hydroxide to expanded graphite of 1:1–2:1.
[0008] Furthermore, the fiber cloth in the energy-absorbing buffer layer is specifically glass fiber cloth; the core material in the energy-absorbing buffer layer is specifically aluminum foam or honeycomb polyimide foam with a density of 0.15–0.3 g / cm³.
[0009] Furthermore, the base carrier in the fire-extinguishing and flame-retardant inner layer is specifically modified epoxy resin or modified polypropylene resin; the fire-extinguishing functional filler in the fire-extinguishing and flame-retardant inner layer is specifically composed of fireproof cotton, fly ash and sodium tetraborate in a mass ratio of (2.5–3.5):(1.5–2.5):(0.8–1.2), wherein the fiber length of the fireproof cotton is less than 6 mm and the particle size of the fly ash is not greater than 200 mesh; the binder in the fire-extinguishing and flame-retardant inner layer is specifically water-based polyurethane; the dispersant in the fire-extinguishing and flame-retardant inner layer is specifically a compound of xanthan gum and guar gum, wherein the mass ratio of xanthan gum to guar gum is (1–3):(1–3).
[0010] The present invention relates to a method for preparing a structurally stable, fire-extinguishing, and flame-retardant lightweight composite material sheet, characterized by the following steps: Step 1, raw material pretreatment: After continuously unwinding the reinforcing fibers used to prepare the protective surface layer, the sheets are immersed in a silane coupling agent solution in an impregnation tank for 20–30 min, and then dried for later use; after continuously unwinding the fiber cloth used to prepare the energy-absorbing buffer layer, the sheets are immersed in resin in an impregnation tank for 10–30 min, and then dried for later use; other raw materials are selected, compounded, and prepared for later use; Step 2, preparation of continuous blanks for each layer: Continuous blanks for the protective surface layer, continuous blanks for the energy-absorbing buffer layer, and continuous blanks for the fire-extinguishing and flame-retardant inner layer are prepared; Step 3, integrated molding of continuous sheet: The three continuous blanks are stacked sequentially and fed into a continuous hot press unit at 120–160℃, 8–12 MPa, and a linear speed of 0.5–2. Continuous hot pressing is performed at a speed of m / min, and after cooling, a continuous sheet blank is obtained; Step 4, post-processing: the continuous sheet blank is cut to the preset size, the edges are trimmed and it is subjected to online ultrasonic C-scan inspection to ensure that the defect rate is less than 1%.
[0011] Furthermore, the method for preparing the continuous protective surface preform in step two is as follows: the resin matrix is heated and melted in a continuous extruder, and the pretreated reinforcing fibers and flame retardant synergist are continuously mixed and impregnated through an impregnation die to form the continuous protective surface preform.
[0012] Furthermore, the method for preparing the continuous blank of the energy-absorbing buffer layer in step two is as follows: the core material is continuously unwound, and the resin-impregnated fiber cloth is simultaneously conveyed from top to bottom. The fiber cloth and the core material are precisely composited and positioned by the guide roller to form the continuous blank of the energy-absorbing buffer layer.
[0013] Furthermore, the method for preparing the continuous blank of the fire extinguishing and flame retardant inner layer in step two is as follows: the base carrier is heated to 60–80°C in a continuous reaction vessel, fire extinguishing functional filler, binder and dispersant are added, and after being mixed evenly by high-speed stirring, it is coated by a continuous coating machine to form the continuous blank of the fire extinguishing and flame retardant inner layer.
[0014] The structurally stable, fire-extinguishing, and flame-retardant lightweight composite material sheet of this invention is applied to the casing of new energy batteries.
[0015] The composite material sheet prepared by the method of the present invention provides a structurally stable, fire-retardant, and lightweight composite material sheet that can be used in the casing of new energy batteries.
[0016] The positive effects of this invention are as follows: First, the composite material sheet of this invention adopts a three-layer composite structure design, realizing multi-functional integration and significantly improving safety performance. The protective surface layer has excellent impact and puncture resistance; the energy-absorbing buffer layer can efficiently absorb collision impact energy and reduce the risk of damage to the battery module; the fire-extinguishing and flame-retardant inner layer can quickly release fire-extinguishing components at high temperatures, forming a dense sealing layer to isolate oxygen and achieve cooling.
[0017] Secondly, the composite material sheet described in this invention exhibits outstanding lightweighting effects, which contributes to improved battery range. This sheet utilizes lightweight reinforcing fibers and a low-density core material. The overall density of the composite material is controlled at 1.25–1.3 g / cm³, which is only 46%–49% of the density of traditional battery casing materials (6061 aluminum alloy), achieving a weight reduction of 51%–54%. This significantly reduces the overall weight of the battery pack and effectively improves the range of new energy equipment.
[0018] Third, the composite material sheet of this invention exhibits strong structural stability and significantly improved interlayer bonding performance. By employing a silane coupling agent for modification, the interfacial bonding force between the reinforcing fibers and the resin matrix is significantly enhanced, with interlayer shear strength exceeding 42 MPa, outperforming traditional battery casing materials (6061 aluminum alloy). The fiber cloth is impregnated with a resin matching the resin matrix of the protective surface, ensuring the reliability of the interlayer composite. Simultaneously, the integrated hot-pressing molding process reduces the number of components, further improving the overall sealing and reliability of the structure.
[0019] Fourth, the composite material sheet described in this invention has achieved the advantages of cost control and environmental friendliness. This sheet can flexibly select different resins and fibers for combination according to application requirements, such as a low-cost glass fiber and PP resin system, which has a recyclability rate of 85% while maintaining strength performance close to that of aluminum alloys. Simultaneously, by utilizing industrial solid waste such as fly ash in the fire-extinguishing filler, raw material costs are effectively reduced, aligning with the environmental protection concept of resource recycling. Detailed Implementation
[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Embodiment 1
[0021] (1) Composition of composite material board A lightweight composite material board with stable structure and fire extinguishing and flame retardant properties includes a protective surface layer, an energy-absorbing buffer layer and a fire extinguishing and flame retardant inner layer, which are sequentially composited from the outside to the inside. Each layer is integrally formed into a board by continuous hot pressing composite process. The thickness of the finished board is 8 mm. The mass percentage of each layer is: 35% for the protective surface layer, 35% for the energy-absorbing buffer layer and 30% for the fire extinguishing and flame retardant inner layer.
[0022] The protective surface layer is a fiber-reinforced resin-based composite material, composed of the following components by weight percentage: 50% resin matrix, 42% reinforcing fibers, 2% silane coupling agent, and 6% flame retardant synergist (originally, the total was not 100%). The resin matrix is specifically a thermosetting epoxy resin; the reinforcing fibers are specifically basalt fibers, with a length of 15 mm. The basalt fiber is modified with a silane coupling agent and used in mm; the flame retardant synergist is a compound of nano-magnesium hydroxide and expanded graphite, with a mass ratio of nano-magnesium hydroxide to expanded graphite of 1.5:1; the energy-absorbing buffer layer is a sandwich structure, composed of two layers of resin-impregnated fiber cloth and a lightweight core material located between the two layers of fiber cloth; the fiber cloth is specifically glass fiber cloth; the resin impregnated with the fiber cloth is matched with the resin matrix of the protective surface layer, and both have the same composition, both being thermosetting epoxy resin; the core material is specifically aluminum foam with a density of 0.2 g / cm³; the fire-extinguishing and flame-retardant inner layer is composed of the following components by mass percentage: 50% base carrier, 40% fire-extinguishing functional filler, 8% binder and 2% dispersant (originally not 100% after addition); the base carrier is specifically modified epoxy resin; the fire-extinguishing functional filler is specifically a compound of fireproof cotton, fly ash and sodium tetraborate in a mass ratio of 3:2:1, and the fiber length of the fireproof cotton is 4 mm. mm, wherein the particle size of the fly ash is 180 mesh; the binder is specifically water-based polyurethane; the dispersant is specifically a compound of xanthan gum and guar gum, which are compounded in a mass ratio of 2:1.
[0023] (2) Preparation method of composite material board The preparation method of the structurally stable, fire-extinguishing and flame-retardant lightweight composite material board adopts a continuous hot-pressing composite production line, and the steps are as follows: Step 1, raw material pretreatment: After the basalt fiber used to prepare the protective surface layer is continuously unwound, it is placed in an impregnation tank and soaked in a silane coupling agent solution for 25 min, and then dried for later use. After the glass fiber cloth used to prepare the energy-absorbing buffer layer is continuously unwound, it is placed in an impregnation tank and soaked in thermosetting epoxy resin for 20 min, and then dried for later use. Fireproof cotton and fly ash are crushed and sieved to the specified particle size (fireproof cotton fiber length 4 mm, fly ash particle size 180 mesh), and mixed evenly with sodium tetraborate through a continuous mixer to obtain fire-extinguishing functional filler. Other raw materials are selected, compounded, and prepared as needed, and then set aside for use; Step 2, preparation of continuous blanks for each layer: preparation of continuous blanks for the protective surface layer, continuous blanks for the energy-absorbing buffer layer, and continuous blanks for the fire-extinguishing and flame-retardant inner layer; The specific method for preparing the continuous blank for the protective surface layer is as follows: the thermosetting epoxy resin is heated and melted in a continuous extruder, and the pretreated basalt fiber, nano-magnesium hydroxide, and expanded graphite compound are continuously mixed and impregnated through an impregnation die to form the continuous blank for the protective surface layer; The specific method for preparing the continuous blank for the energy-absorbing buffer layer is as follows: the core material is continuously unwound, and the glass impregnated with thermosetting epoxy resin is simultaneously conveyed from top to bottom. Fiber cloth is precisely composited and positioned with the core material using guide rollers to form a continuous blank for the energy-absorbing buffer layer. The specific method for preparing the continuous blank for the fire-extinguishing and flame-retardant inner layer is as follows: Modified epoxy resin is heated to 70°C in a continuous reactor, and pre-treated fire-extinguishing functional filler, water-based polyurethane, and a compound of xanthan gum and guar gum are added. After high-speed stirring and uniform mixing, it is coated using a continuous coating machine to form the continuous blank for the fire-extinguishing and flame-retardant inner layer. Step three: Integrated molding of the continuous sheet: The above three continuous blanks are precisely stacked in sequence using a guiding conveyor device and fed into a continuous hot press unit at a temperature of 140°C and a pressure of 10... Continuous hot pressing is performed under conditions of MPa and a linear speed of 1 m / min. After cooling to room temperature, a continuous composite material sheet blank is obtained. Step four, post-processing: The continuous sheet blank is cut into 1200 mm × 800 mm dimensions using a continuous cutting machine, the edges are trimmed using a continuous grinding machine, and internal defects are detected using an online ultrasonic C-scan detection device to ensure that the defect rate is less than 1%. Finally, a finished composite material sheet that can be directly used for battery casing processing is obtained. The scraps generated from cutting can be crushed and recycled as raw materials for inner layer preparation, improving the raw material utilization rate.
[0024] (3) Performance testing of composite material sheets The performance of the above-mentioned composite material sheets was tested, and the parameters obtained from the test results are as follows: 1. According to GB / T 1463-2005 standard, the density of the composite material sheets was tested by the impregnation method. The test result was: density is 1.3 g / cm³; 2. According to GB / T 31467.3-2015 standard, the extrusion load bearing capacity of the composite material sheets was tested by a universal testing machine with an extrusion speed of 5 mm / s and an extrusion stroke of 100 mm. The test result was: extrusion load bearing capacity is 110 kN; 3. According to GB / T 38031-2020 standard, thermal runaway was simulated with an initial temperature of 80℃ and a heating rate of 5℃ / min. The thermal runaway insulation time of the composite material sheets was tested. The test result was: thermal runaway insulation time is 65 min; 4. According to UL94-2021 standard, the flame retardancy rating of the composite material sheets was tested by the vertical burning method. The test result was: flame retardancy rating is UL94. V-0 grade; 5. According to GB / T 1450.1-2005 standard, the interlaminar shear strength of the composite material sheet was tested through a short beam shear test. The test result was: interlaminar shear strength of 45 MPa; 6. According to GB / T 39785-2021 standard, the recyclability of the composite material sheet was tested using a mechanical crushing-reforming process. The test result was: recyclability of 60%. Example 2
[0025] (1) The composition of the composite material board differs from that in Example 1 in that the finished board is 10 mm thick, and the mass percentage of each layer is: 30% for the protective surface layer, 40% for the energy-absorbing buffer layer, and 30% for the fire-extinguishing and flame-retardant inner layer; the protective surface layer is composed of the following components by mass percentage: 40% for the resin matrix, 50% for the reinforcing fiber, 3% for the silane coupling agent, and 7% for the flame-retardant synergist (originally, the total was not 100%); the resin matrix is specifically thermoplastic polypropylene (PP resin); the reinforcing fiber is specifically carbon fiber, with a length of 10 mm, and the carbon fiber is modified by the silane coupling agent before use; the flame-retardant synergist is specifically a compound of nano-magnesium hydroxide and expanded graphite, with a mass ratio of 1:1 between nano-magnesium hydroxide and expanded graphite; the resin impregnated with glass fiber cloth in the energy-absorbing buffer layer matches the resin matrix of the protective surface layer, and both have the same composition, which is thermoplastic polypropylene (PP resin); the core material is specifically honeycomb polyimide foam with a density of 0.15. g / cm³; the fire-extinguishing and flame-retardant inner layer is composed of the following components by mass percentage: 55% base carrier, 35% fire-extinguishing functional filler, 9% binder, and 1% dispersant (not 100% when added together); the base carrier is specifically modified polypropylene resin. The fire-extinguishing functional filler is specifically a compound of fireproof cotton, fly ash, and sodium tetraborate in a mass ratio of 2.5:1.5:0.8, with the fireproof cotton fiber length being 5 mm and the fly ash particle size being 200 mesh; the binder is specifically water-based polyurethane; the dispersant is specifically a compound of xanthan gum and guar gum in a mass ratio of 1:3.
[0026] (2) The preparation method of the composite material sheet differs from that in Example 1 in that: Step 1, raw material pretreatment: After the carbon fiber used to prepare the protective surface layer is continuously unwound, it is immersed in the silane coupling agent solution in the impregnation tank for 20 min, and then dried for later use. After the glass fiber cloth used to prepare the energy-absorbing buffer layer is continuously unwound, it is immersed in thermoplastic polypropylene (PP resin) in the impregnation tank for 10 min, and then dried for later use.
[0027] Step 2, Preparation of continuous blanks for each layer: The specific method for preparing the continuous blanks for the protective surface layer is as follows: Thermoplastic polypropylene (PP resin) is heated and melted in a continuous extruder, and the pretreated carbon fiber and the composite of nano magnesium hydroxide and expanded graphite are continuously mixed and impregnated through an impregnation die.
[0028] The specific method for preparing the continuous blank of the energy-absorbing buffer layer is as follows: glass fiber cloth impregnated with thermoplastic polypropylene (PP resin) is conveyed synchronously from top to bottom.
[0029] The specific method for preparing the continuous blank of the fire extinguishing and flame retardant inner layer is as follows: the modified polypropylene resin is heated to 60°C in a continuous reaction vessel.
[0030] Step 3, continuous sheet integral molding: continuous hot pressing is carried out under the conditions of temperature 120℃, pressure 8 MPa and linear speed 0.5 m / min; Step 4, post-processing: the continuous sheet blank is cut into 1500 mm × 1000 mm size by a continuous cutting machine.
[0031] (3) Performance testing of composite material sheets The performance of the above-mentioned composite material sheets was tested, and the parameters obtained from the test results are as follows: 1. According to GB / T 1463-2005 standard, the density of the composite material sheets was tested by the impregnation method. The test result was: density is 1.25 g / cm³; 2. According to GB / T 31467.3-2015 standard, the extrusion load bearing capacity of the composite material sheets was tested by a universal testing machine with an extrusion speed of 5 mm / s and an extrusion stroke of 100 mm. The test result was: extrusion load bearing capacity is 100 kN; 3. According to GB / T 38031-2020 standard, thermal runaway was simulated with an initial temperature of 80℃ and a heating rate of 5℃ / min. The thermal runaway insulation time of the composite material sheets was tested. The test result was: thermal runaway insulation time is 60 min; 4. According to UL94-2021 standard, the flame retardancy rating of the composite material sheets was tested by the vertical burning method. The test result was: flame retardancy rating is UL94. V-0 grade; 5. According to GB / T 1450.1-2005 standard, the interlaminar shear strength of the composite material sheet was tested through a short beam shear test. The test result was: interlaminar shear strength of 40 MPa; 6. According to GB / T 39785-2021 standard, the recyclability of the composite material sheet was tested using a mechanical crushing-reforming process. The test result was: recyclability of 85%. Example 3
[0032] (1) The difference between the composition of the composite material board and that of Example 1 is that the thickness of the finished board is 12 mm, and the mass percentage of each layer is: 45% for the protective surface layer, 25% for the energy-absorbing buffer layer, and 30% for the fire-extinguishing and flame-retardant inner layer; the protective surface layer is composed of the following components by mass percentage: 55% for the resin matrix, 35% for the reinforcing fiber, 2% for the silane coupling agent and 8% for the flame retardant synergist (the original sum is not 100%); the resin matrix is specifically thermosetting epoxy resin; the reinforcing fiber is specifically basalt fiber with a length of 25 mm, and the carbon fiber is modified by the silane coupling agent before use; the flame retardant synergist is specifically a compound of nano magnesium hydroxide and expanded graphite with a mass ratio of 1:2; the resin impregnated with glass fiber cloth in the energy-absorbing buffer layer is matched with the resin matrix of the protective surface layer, and the two have the same composition, which is thermosetting epoxy resin. The core material is specifically aluminum foam with a density of 0.3 g / cm³; the fire-extinguishing and flame-retardant inner layer is composed of the following components by mass percentage: 45% base carrier, 45% fire-extinguishing functional filler, 7% binder, and 3% dispersant (originally, the total is not 100%); the base carrier is specifically modified epoxy resin; the fire-extinguishing functional filler is specifically a compound of fireproof cotton, fly ash, and sodium tetraborate in a mass ratio of 3.5:2.5:1.2, with the fireproof cotton fiber length being 3 mm and the fly ash particle size being 150 mesh; the binder is water-based polyurethane; the dispersant is specifically a compound of xanthan gum and guar gum in a mass ratio of 3:1.
[0033] (2) The difference between the preparation method of the composite material plate and Example 1 is: Step 1, raw material pretreatment: After the basalt fiber used to prepare the protective surface layer is continuously unwound, it is placed in the impregnation tank and soaked in the silane coupling agent solution for 30 min, and then dried for later use. Step 1: After continuous unwinding, the glass fiber cloth used to prepare the energy-absorbing buffer layer is immersed in thermosetting epoxy resin in an impregnation tank for 30 min, and then dried for later use. Step 2: Preparation of continuous blanks for each layer: The method for preparing the continuous blank for the protective surface layer is as follows: Thermosetting epoxy resin is heated and melted in a continuous extruder, and the pretreated basalt fiber and the compound of nano-magnesium hydroxide and expanded graphite are continuously mixed and impregnated through an impregnation die. The method for preparing the continuous blank for the energy-absorbing buffer layer is as follows: Glass fiber cloth impregnated with thermosetting epoxy resin is conveyed synchronously from top to bottom. The method for preparing the continuous blank for the fire-extinguishing and flame-retardant inner layer is as follows: Modified epoxy resin is heated to 80℃ in a continuous reactor. Step 3: Integrated molding of continuous sheet: Continuous hot pressing is carried out under the conditions of temperature 160℃, pressure 12 MPa, and linear speed 2 m / min. Step 4: Post-processing: Cutting and inspection.
[0034] (3) Performance testing of composite material sheets The performance of the above-mentioned composite material sheets was tested, and the parameters obtained from the test results are as follows: 1. According to GB / T 1463-2005 standard, the density of the composite material sheets was tested by the impregnation method. The test result was: density is 1.28 g / cm³; 2. According to GB / T 31467.3-2015 standard, the extrusion load bearing capacity of the composite material sheets was tested by a universal testing machine with an extrusion speed of 5 mm / s and an extrusion stroke of 100 mm. The test result was: extrusion load bearing capacity is 115 kN; 3. According to GB / T 38031-2020 standard, thermal runaway was simulated with an initial temperature of 80℃ and a heating rate of 5℃ / min. The thermal runaway insulation time of the composite material sheets was tested. The test result was: thermal runaway insulation time is 70 min; 4. According to UL94-2021 standard, the flame retardancy rating of the composite material sheets was tested by the vertical burning method. The test result was: flame retardancy rating is UL94. V-0 grade; 5. According to GB / T 1450.1-2005 standard, the interlaminar shear strength of the composite material sheet was tested by short beam shear test. The test result was: interlaminar shear strength was 46 MPa; 6. According to GB / T 39785-2021 standard, the recyclability of the composite material sheet was tested by mechanical crushing-reforming process. The test result was: recyclability was 55%.
[0035] The composite material sheet product described in this invention is used in the casing of new energy batteries. The commonly used traditional battery casing material, 6061 aluminum alloy sheet, is used as a comparative example. To ensure the fairness of the comparative experiments, 6061 aluminum alloy sheets with the same nominal thickness (8 mm) as the finished product in Example 1 were selected. Parallel performance tests were conducted in the same laboratory, according to the same national standards, and using the same test methods and conditions. The comparative performance parameters are as follows: 1. Density test was conducted using the immersion method according to GB / T 1463-2005 standard. The result was a density of 2.7 g / cm³. 2. Extrusion load bearing capacity test was conducted using a universal testing machine according to GB / T 31467.3-2015 standard, with an extrusion speed of 5 mm / s and an extrusion stroke of 100 mm. The result was an extrusion load bearing capacity of 120 kN. 3. Thermal runaway insulation time test was conducted according to GB / T 38031-2020 standard, simulating thermal runaway, with an initial temperature of 80℃ and a heating rate of 5℃ / min. The result was a thermal runaway insulation time of <5 seconds. 4. According to UL94-2021 standard, the flame retardancy rating was tested using the vertical burning method. The test result showed that the material itself is non-combustible, but as an outer shell, it does not have flame retardant function and will soften, melt, and conduct heat at high temperatures. 5. According to GB / T 1450.1-2005 standard, its shear strength was tested through a short beam shear test as a reference comparison with the interlaminar bonding performance of composite materials. The test result showed that the shear strength was 38 MPa. 6. According to GB / T 39785-2021 standard, the recyclability rate was tested using a mechanical crushing-remelting process. The test result showed that the recyclability rate was 90%.
[0036] The performance test results of Examples 1, 2, and 3 were compared with the performance parameters of traditional battery casing materials (6061 aluminum alloy), and the results are shown in Table 1:
[0037] As shown in the table above: 1. Comparison of density: The densities of Examples 1, 2, and 3 are significantly lower than those of the comparative example, indicating that the composite material sheet of the present invention has a significant lightweight advantage compared to traditional battery casing materials (6061 aluminum alloy); 2. Comparison of compressive load bearing capacity: The compressive load bearing capacity of Examples 1 and 3 is close to that of the comparative example, while that of Example 2 is slightly lower but still meets the usage requirements, indicating that the composite material sheet of the present invention is comparable to or slightly lower than that of traditional aluminum alloy in terms of structural strength, but fully meets the structural strength standard requirements for battery casings; 3. Comparison of thermal runaway insulation time: The thermal runaway insulation time of the three examples is far greater than that of the comparative example (<5 min) and the national standard requirement of 5 min, indicating that the composite material sheet of the present invention has significant thermal protection and insulation advantages; 4. Comparison of flame retardant rating: The flame retardant rating of the three examples all reaches UL94. V-0 rating effectively suppresses the spread of fire, while aluminum alloy lacks flame retardancy, indicating that the composite material sheet described in this invention has a fundamental advantage in fire extinguishing and flame retardancy; 5. Comparison of interlaminar shear strength: The interlaminar shear strength of the three embodiments is higher than that of the comparative example, indicating that the interlaminar bonding of the composite material sheet described in this invention is stronger, the structural stability is better, and it has better energy absorption and explosion-proof potential; 6. Comparison of recyclability: The recyclability of Example 2 (PP system) is as high as 85%, close to the level of aluminum alloy; Although the recyclability of Examples 1 and 3 (epoxy system) is lower, they still have recyclable characteristics, and can be further improved through formulation and process optimization.
[0038] In summary, the composite material sheet of this invention is significantly superior to traditional aluminum alloy materials in terms of lightweighting, thermal protection, fire extinguishing and flame retardancy, and structural stability. While its extrusion load-bearing capacity is slightly lower than that of aluminum alloys, it fully meets or even exceeds the actual usage standards for battery casings. Furthermore, by flexibly selecting resin systems (such as PP systems), high recyclability and low cost can be achieved while maintaining excellent overall performance, fully meeting the comprehensive requirements of new energy battery casings for safety, lightweighting, environmental protection, and economy. It should be understood that technical features not detailed in this specification belong to the prior art. Although embodiments of this application have been described, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many more forms under the guidance of this application without departing from the spirit and scope of the claims, and these all fall within the scope of protection of this application.
Claims
1. A lightweight composite material sheet with stable structure and fire-retardant properties, characterized in that, The material comprises, from the outside in, a protective outer layer, an energy-absorbing buffer layer, and a fire-extinguishing and flame-retardant inner layer, all integrally formed into a sheet material through a continuous hot-pressing composite process. The mass percentages of each layer are: protective outer layer 30%–45%, energy-absorbing buffer layer 25%–40%, and fire-extinguishing and flame-retardant inner layer 20%–35%. The protective outer layer consists of the following components by mass percentage: resin matrix 40%–55%, reinforcing fibers 35%–50%, silane coupling agent 1%–3%, and flame-retardant synergist 3%–8%. The energy-absorbing buffer layer comprises two layers of resin-impregnated fiber cloth and a lightweight core material located between the two fiber cloth layers. The resin used to impregnate the fiber cloth is compatible with the resin matrix of the protective outer layer, and both have the same or compatible compositions. The fire-extinguishing and flame-retardant inner layer consists of the following components by mass percentage: base carrier 45%–55%, fire-extinguishing functional filler 35%–45%, binder 5%–10%, and dispersant 1%–3%.
2. The structurally stable, fire-retardant, lightweight composite material sheet according to claim 1, characterized in that, The resin matrix in the protective surface layer is specifically a thermosetting epoxy resin or a thermoplastic polypropylene; the reinforcing fiber in the protective surface layer is specifically basalt fiber or carbon fiber, with a length of 10–25 mm; the flame retardant synergist in the protective surface layer is specifically a compound of nano-magnesium hydroxide and expanded graphite, with a mass ratio of nano-magnesium hydroxide to expanded graphite of 1:1–2:
1.
3. The structurally stable, fire-retardant, lightweight composite material sheet according to claim 1, characterized in that, The fiber cloth in the energy-absorbing buffer layer is specifically glass fiber cloth; the core material in the energy-absorbing buffer layer is specifically aluminum foam or honeycomb polyimide foam with a density of 0.15–0.3 g / cm³.
4. The structurally stable, fire-retardant, lightweight composite material sheet according to claim 1, characterized in that, The base carrier in the fire extinguishing and flame retardant inner layer is specifically modified epoxy resin or modified polypropylene resin; the fire extinguishing functional filler in the fire extinguishing and flame retardant inner layer is specifically composed of fireproof cotton, fly ash and sodium tetraborate in a mass ratio of (2.5–3.5):(1.5–2.5):(0.8–1.2), wherein the fiber length of the fireproof cotton is less than 6 mm and the particle size of the fly ash is not greater than 200 mesh; the binder in the fire extinguishing and flame retardant inner layer is specifically water-based polyurethane; the dispersant in the fire extinguishing and flame retardant inner layer is specifically a compound of xanthan gum and guar gum, wherein the mass ratio of xanthan gum to guar gum is (1–3):(1–3).
5. The method for preparing the structurally stable, fire-extinguishing, flame-retardant lightweight composite material sheet according to any one of claims 1-4, characterized in that, The process includes the following steps: Step 1, raw material pretreatment: After continuously unwinding the reinforcing fibers used to prepare the protective surface layer, immerse them in a silane coupling agent solution in an impregnation tank for 20–30 min, and then dry them for later use; after continuously unwinding the fiber cloth used to prepare the energy-absorbing buffer layer, immerse it in resin in an impregnation tank for 10–30 min, and then dry it for later use; other raw materials are selected, compounded, and prepared for later use; Step 2, preparation of continuous blanks for each layer: Prepare continuous blanks for the protective surface layer, continuous blanks for the energy-absorbing buffer layer, and continuous blanks for the fire-extinguishing and flame-retardant inner layer; Step 3, integrated molding of continuous sheet: Stack the three continuous blanks in sequence, feed them into a continuous hot press unit, and continuously hot press them at 120–160℃, 8–12 MPa, and a linear speed of 0.5–2 m / min. After cooling, a continuous sheet blank is obtained; Step 4, post-processing: Cut the continuous sheet blank to the preset size, trim the edges, and perform online ultrasonic C-scan inspection to ensure that the defect rate is less than 1%.
6. The method for preparing a structurally stable, fire-extinguishing, flame-retardant lightweight composite material sheet according to claim 5, characterized in that, The specific method for preparing the continuous protective surface preform in step two is as follows: the resin matrix is heated and melted in a continuous extruder, and the pretreated reinforcing fibers and flame retardant synergist are continuously mixed and impregnated through an impregnation die to form the continuous protective surface preform.
7. The method for preparing a structurally stable, fire-extinguishing, flame-retardant lightweight composite material sheet according to claim 5, characterized in that, The specific method for preparing the continuous blank of the energy-absorbing buffer layer in step two is as follows: the core material is continuously unwound, and the resin-impregnated fiber cloth is simultaneously conveyed from top to bottom. The fiber cloth and the core material are precisely composited and positioned by the guide roller to form the continuous blank of the energy-absorbing buffer layer.
8. The method for preparing a structurally stable, fire-extinguishing, flame-retardant lightweight composite material sheet according to claim 5, characterized in that, The specific method for preparing the continuous blank of the fire extinguishing and flame retardant inner layer in step two is as follows: the base carrier is heated to 60–80°C in a continuous reaction vessel, fire extinguishing functional filler, binder and dispersant are added, and after being mixed evenly by high-speed stirring, it is coated by a continuous coating machine to form the continuous blank of the fire extinguishing and flame retardant inner layer.
9. The structurally stable, fire-extinguishing and flame-retardant lightweight composite material sheet according to any one of claims 1-4 is applied to the casing of new energy batteries.
10. The structurally stable, fire-extinguishing and flame-retardant lightweight composite material sheet prepared by the method for preparing composite material sheet according to any one of claims 5-8 is applied to the casing of new energy batteries.