A composite sheet material and its preparation method, a battery pack protective plate, and a vehicle.

Abstract

This invention relates to a composite sheet material and its preparation method, a battery pack protective plate, and a vehicle. The composite sheet material includes a first surface layer, a core layer, and a second surface layer stacked sequentially. The first surface layer and / or the second surface layer includes one or more layers of polyamide sheets and one or more layers of fiber fabric, wherein the multi-layer fiber fabric is disposed between the multi-layer polyamide sheets. The core layer includes a metal plate. The polyamide sheets have a melting point of 240–320°C and a shear rate of 1 second at 280–340°C. ‑1 The viscosity under certain conditions is 400–900 Pa·s. One embodiment of the composite board of the present invention uses polyamide sheets and fiber fabrics of specific viscosities as the surface layer and a metal plate as the core layer, thereby improving the interlayer bonding strength between the surface layer and the core layer and significantly enhancing the impact resistance of the composite board.

Description

Technical Field

[0001] This invention relates to composite materials, and more particularly to a composite material that can be used as a battery pack protective plate. Background Technology

[0002] With the rapid development of electric vehicles, the power battery pack, as the power source of electric vehicles, is generally located under the vehicle chassis and is largely exposed under the vehicle. This makes the bottom of the battery pack susceptible to impacts from flying stones and bricks, as well as scrapes from going uphill and over speed bumps during daily driving. These situations can all potentially cause the battery pack to crack and its protective structure to fail. Therefore, bottom protection is crucial. To cope with these complex operating conditions, a protective plate is usually installed at the bottom of the battery pack to protect its underside.

[0003] Traditionally, battery pack bottom protectors for electric vehicles are made of stamped steel sheets, which are then treated with electrophoresis to prevent corrosion. However, traditional steel is too heavy to meet the lightweight requirements of electric vehicles, and the steel sheets offer virtually no cushioning for the pallet, making them more susceptible to damage from vehicle bumps. To address this, sandwich panels made of fiber-reinforced PP prepreg tape as the surface layer and steel sheet as the core layer are commonly used as battery pack bottom protectors. However, these sandwich panels often suffer from insufficient interlayer bonding, leading to delamination and deformation after impacts or scratches, resulting in poor protection. Summary of the Invention

[0004] To overcome at least one of the defects of the prior art, in a first aspect, one embodiment of the present invention provides a composite board comprising a first surface layer, a core layer, and a second surface layer stacked sequentially, wherein the first surface layer and / or the second surface layer comprises one or more layers of polyamide sheets and one or more layers of fiber fabric, the multi-layer fiber fabric being disposed between the multi-layer polyamide sheets, and the core layer comprising a metal plate, wherein...

[0005] The polyamide sheet has a melting point of 240–320°C, and its melting point is between 280–340°C and a shear rate of 1 second. -1 The viscosity under these conditions is 400–900 Pa·s.

[0006] In a second aspect, one embodiment of the present invention provides a method for preparing the above-mentioned composite board, comprising: sequentially laying one or more layers of polyamide sheet and one or more layers of fiber fabric, an optional first adhesive layer, the metal plate, an optional second adhesive layer, one or more layers of polyamide sheet and one or more layers of fiber fabric, and then molding to obtain the composite board.

[0007] Thirdly, one embodiment of the present invention provides the application of the above-described composite material or the composite material prepared by the above-described preparation method as a battery pack protective plate.

[0008] Fourthly, one embodiment of the present invention provides a battery pack protective plate, comprising the composite material described above or the composite material prepared by the above preparation method.

[0009] Fifthly, one embodiment of the present invention provides a vehicle including the aforementioned battery pack guard plate.

[0010] The composite board of one embodiment of the present invention uses polyamide sheets and fiber fabrics of a specific viscosity as the surface layer and a metal plate as the core layer, which improves the interlayer bonding force between the surface layer and the core layer and significantly improves the impact resistance of the composite board. Attached Figure Description

[0011] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Wherein:

[0012] Figure 1 This is a schematic diagram of the structure of a composite board according to one embodiment of the present invention;

[0013] Figure 2 This is a schematic diagram of the structure of a composite board according to another embodiment of the present invention;

[0014] Figure 3 This is a schematic diagram of the structure of a composite board according to another embodiment of the present invention;

[0015] The annotations in the attached figures are explained as follows:

[0016] 100, First surface layer; 101, First polyamide sheet layer; 102, Second polyamide sheet layer; 103, First inner layer; 104, Second inner layer; 200, Metal plate; 201, First surface; 202, Second surface; 300, Second surface layer; 301, Third polyamide sheet layer; 302, Fourth polyamide sheet layer; 303, First intermediate layer; 304, Second intermediate layer; 305, Third intermediate layer; 306, Fourth intermediate layer; 307, Fifth intermediate layer; 308, Sixth intermediate layer; 40, First adhesive layer; 50, Second adhesive layer. Detailed Implementation

[0017] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the description herein is for illustrative purposes only and not intended to limit the present invention.

[0018] Reference Figure 1As shown, one embodiment of the present invention provides a composite board comprising a first surface layer 100, a core layer, and a second surface layer 300 stacked sequentially. The first surface layer 100 and / or the second surface layer 300 comprises one or more layers of polyamide sheets and one or more layers of fiber fabric. The core layer comprises a metal plate 200, the metal plate 200 comprising a first surface 201 and a second surface 202, the first surface 201 being in contact with the first surface layer 100, and the second surface 202 being in contact with the second surface layer 300.

[0019] The polyamide sheet has a melting point of 240–320°C, and its melting point is between 280–340°C and a shear rate of 1 second. -1 The viscosity under these conditions is 400–900 Pa·s.

[0020] In one embodiment, the composite board is obtained by molding a first surface layer, a metal plate, and a second surface layer. The first surface layer and / or the second surface layer includes one or more polyamide sheets and one or more fiber fabrics, wherein the one or more fiber fabrics are disposed between the polyamide sheets. After molding, the one or more polyamide sheets form a resin matrix, and the one or more fiber fabrics are located in the resin matrix and are in contact with the metal plate.

[0021] In one embodiment, the first and / or second surface layer comprises one or more layers (e.g., two layers) of polyamide sheet and one or more layers of fiber fabric stacked together. That is, the first and / or second surface layer is formed by laying up (e.g., alternating layers) one or more layers of polyamide sheet and one or more layers of fiber fabric. For example, both the first and second surface layers may comprise two layers of polyamide sheet and one layer of fiber fabric, arranged from bottom to top as polyamide sheet, fiber fabric, polyamide sheet, metal plate, polyamide sheet, fiber fabric, and polyamide sheet. As another example, the first surface layer may comprise four layers of polyamide sheet and one layer of fiber fabric, arranged from bottom to top as polyamide sheet, polyamide sheet, fiber fabric, polyamide sheet, and polyamide sheet; the second surface layer may comprise eight layers of polyamide sheet and two layers of fiber fabric, arranged from bottom to top as polyamide sheet, polyamide sheet, polyamide sheet, fiber fabric, polyamide sheet, polyamide sheet, fiber fabric, polyamide sheet, polyamide sheet, and polyamide sheet.

[0022] In one embodiment, the first surface layer and / or the second surface layer each include a laminated polyamide sheet layer, at least one intermediate layer, and a polyamide sheet layer, wherein the at least one intermediate layer includes a fibrous fabric.

[0023] In one embodiment, at least one intermediate layer of the first and / or second surface layer comprises one or more fabric layers and at least one or more polyamide sheets.

[0024] In one implementation, reference Figure 1 , 3 As shown, the first surface layer 100 includes a first polyamide sheet layer 101, a first inner layer 103 (fiber fabric), and a second polyamide sheet layer 102, which are stacked sequentially.

[0025] In one implementation, reference Figure 1 , 3 As shown, the second surface layer 300 includes a third polyamide sheet layer 301, a first intermediate layer 303 (polyamide sheet), a second intermediate layer 304 (fiber fabric), a third intermediate layer 305 (polyamide sheet), a fourth intermediate layer 306 (fiber fabric), a fifth intermediate layer 307 (polyamide sheet), and a fourth polyamide sheet layer 302, which are stacked sequentially.

[0026] In one implementation, reference Figure 1 As shown, the first surface 201 of the metal plate 200 is in contact with the second polyamide sheet layer 102 of the first surface layer 100, and the second surface 202 of the metal plate 200 is in contact with the third polyamide sheet layer 301 of the second surface layer 300.

[0027] In one implementation, reference Figure 3 As shown, a first adhesive layer 40 is provided between the first surface layer 100 and the core layer (or metal plate 200), and a second adhesive layer 50 is provided between the second surface layer 300 and the core layer (or metal plate 200).

[0028] In one implementation, reference Figure 3 As shown, the first surface 201 of the metal plate 200 is in contact with the first adhesive layer 40, and the second surface 202 of the metal plate 200 is in contact with the second adhesive layer 50.

[0029] In another implementation, refer to Figure 2 As shown, the first surface layer 100 includes a first polyamide sheet layer 101, a first inner layer 103 (fiber fabric), a second inner layer 104 (polyamide sheet), and a second polyamide sheet layer 102 stacked sequentially. The second polyamide sheet layer 102 is in contact with the first surface 201 of the metal plate 200.

[0030] In another implementation, refer to Figure 2As shown, the second surface layer 300 includes a third polyamide sheet layer 301, a first intermediate layer 303 (polyamide sheet), a second intermediate layer 304 (fiber fabric), a third intermediate layer 305 (polyamide sheet), a fourth intermediate layer 306 (polyamide sheet), a fifth intermediate layer 307 (fiber fabric), a sixth intermediate layer 308 (polyamide sheet), and a fourth polyamide sheet layer 302, which are stacked sequentially. The third polyamide sheet layer 301 is in contact with the second surface 202 of the metal plate 200.

[0031] In one embodiment, the polyamide sheet has a melting point of 240–270°C and a shear rate of 1 second at 300–330°C. -1 The viscosity under these conditions is 400–600 Pa·s.

[0032] In one embodiment, the polyamide sheet has a melting point of 260–270°C, and its shear rate is 1 second at 325–330°C. -1 The viscosity under the specified conditions is 400–500 Pa·s, further 400–450 Pa·s, and even further 400–430 Pa·s.

[0033] In one embodiment, the polyamide sheet has a melting point of 270–320°C, and its shear rate is 1 second at 300–340°C. -1 The viscosity under these conditions is 700–900 Pa·s.

[0034] In one embodiment, the polyamide sheet has a melting point of 295–300°C, and its shear rate is 338–340°C at a shear rate of 1 second. -1 The viscosity under the specified conditions is 800–900 Pa·s, further 850–900 Pa·s, and even further 870–895 Pa·s.

[0035] In one embodiment, the viscosity of the polyamide sheet can be measured using a rotational rheometer. Further, a rotational rheometer of the Anton Paar MCR302 type is used to measure the melt viscosity of the polyamide sheet, with a shear rate set to 1 s. -1 The frequency was 1 Hz, the heating rate was 3℃ / s, and the test temperature was from the melting point of the polyamide sheet to 20-100℃ above the melting point, and further to 30-80℃ above the melting point.

[0036] In one embodiment, the viscosity of the polyamide sheet can be adjusted by modifying the polyamide sheet manufacturing process and the viscosity of the polyamide resin used as the raw material. Furthermore, the viscosity of the polyamide resin can be controlled by solid-phase thickening, adjusting resin synthesis parameters, etc. In this invention, the viscosity of the polyamide sheet is generally the same as the viscosity of the polyamide resin.

[0037] In one embodiment, the elongation at break of the polyamide sheet is >50%, further >70%, and even further >90%.

[0038] In one embodiment, the polyamide sheet has a thickness of 0.05–1 mm, more preferably 0.05–0.3 mm, such as 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.5 mm, or 0.8 mm. Sheets with a thickness of 0.5 mm or less may also be referred to as "films".

[0039] In one embodiment, the density of the polyamide sheet is 1.0–1.2 g / cm³. 3 For example, 1.05 g / cm³ 3 1.1g / cm 3 1.14 g / cm 3 1.15g / cm 3 1.17g / cm 3 1.18 g / cm 3 .

[0040] In one embodiment, the moisture content of the polyamide sheet is below 500 ppm, and may further be 50 to 500 ppm, such as 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, or 450 ppm.

[0041] In one embodiment, the method for preparing a polyamide sheet includes: heating and melting a polyamide resin; casting the resulting polyamide melt (e.g., through a T-die) onto a cooling roller, and then drawing and winding it to obtain a polyamide cast sheet. Further, the surface temperature of the cooling roller can be, for example, 50°C.

[0042] In one embodiment, when the thickness of the polyamide sheet is 0.05 to 0.3 mm, it can be prepared by coating, blown film blowing or calendering.

[0043] In one embodiment, the polyamide sheet is made from a polyamide resin, the monomers of which include a diamine and a diacid, the diamine including pentanediamine; the diacid including one or more of an aliphatic diacid having 4 to 18 carbon atoms and an aromatic diacid having 8 to 10 carbon atoms (e.g., 9).

[0044] In one embodiment, the molar ratio of the diamine and the diacid used to prepare the polyamide resin can be (1 to 1.05):1, for example, 1.01:1, 1.02:1, 1.03:1, or 1.04:1.

[0045] In one embodiment, the diamine includes pentanediamine and other diamines, wherein the other diamines may be one or more aliphatic diamines (excluding pentanediamine) having 4 to 16 carbon atoms; further, the other diamines may be one or more of butanediamine, hexanediamine, heptadecanediamine, octanediamine, nonanediamine, decanedanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, and hexadecanediamine.

[0046] In one embodiment, the aliphatic dicarboxylic acid having 4 to 18 carbon atoms can be one or more of the following: oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid.

[0047] In one embodiment, the aromatic dicarboxylic acid may be one, two, or three of terephthalic acid, isophthalic acid, and phthalic acid.

[0048] In one embodiment, the polyamide resin is obtained by copolymerization of pentanediamine, hexamethylenediamine, adipic acid and terephthalic acid, and has a melting point of 240–320°C.

[0049] In one embodiment, the polyamide resin composition used to prepare polyamide sheets comprises a polyamide resin and functional additives, said functional additives including one or more of antioxidants, heat stabilizers, lubricants, flame retardants, inorganic fillers, flow modifiers, and antistatic agents. Examples include commercially available antioxidant 168 and flow modifiers consisting of aliphatic dicarboxylic acids with 12 to 16 carbon atoms.

[0050] In one embodiment, the amount of the functional additive added is 0.001 to 15 wt% of the total mass of the polyamide resin composition.

[0051] In one embodiment, the pentanediamine is bio-based pentanediamine, which refers to pentanediamine synthesized from compounds derived from biomass, such as glucose and lysine, through enzyme reactions, yeast reactions, or fermentation reactions during the monomer synthesis process.

[0052] In one embodiment, the thickness of the fibrous fabric can be 0.05 to 0.5 mm, and more specifically 0.1 to 0.4 mm, for example 0.2 mm, 0.3 mm, or 0.35 mm.

[0053] In one embodiment, the basis weight of the fiber fabric can be 650 g / m². 2 The following can be further expressed as 200–650 g / m³ 2 For example, 300g / m 2 400g / m2 500g / m 2 550g / m 2 580g / m 2 600g / m 2 620g / m 2 .

[0054] In one embodiment, the fiber fabric (i.e., continuous fiber fabric) includes continuous fibers, which include one or more of glass fibers, carbon fibers, basalt fibers, aramid fibers, polyolefin fibers, and natural fibers.

[0055] In one embodiment, the fibrous fabric includes continuous fibrous cloth and / or continuous fibrous yarn.

[0056] In one embodiment, the fiber fabric includes one or more of checkered fabric, non-crimped fabric, and three-dimensional fabric. Further, the checkered fabric may be selected from one or more of plain weave, twill weave, and satin weave; the non-crimped fabric may be selected from one or more of uniaxial, biaxial, triaxial, and quadriaxial structures; and the three-dimensional fabric may be selected from three-dimensional orthogonal structures and / or three-dimensional interlocking structures.

[0057] In one embodiment, the orientation of continuous fibers in the fibrous fabric is crossed at 0 to 90°, preferably 90° and / or 45°.

[0058] In one embodiment, the fiber fabric is a biaxial glass fiber fabric, wherein the continuous fiber orientation is 0° / 90° or +45° / -45°.

[0059] In one embodiment, the fiber fabric is a plain weave glass fiber cloth, wherein the continuous fiber orientation is 0° / 90° or +45° / -45°.

[0060] In one embodiment, the fiber fabric is a twill-weave glass fiber cloth, wherein the continuous fiber orientation is 0° / 90° or +45° / -45°.

[0061] In one embodiment, based on the total weight of the polyamide sheet and fiber fabric of the first or second surface layer, the mass content of the fiber fabric can be 50-85%, more specifically 60-70%, for example 55%, 60%, 65%, 70%, 75%, or 80%.

[0062] In one embodiment, the thickness of the metal plate is 0.4-1 mm, for example 0.6 mm, 0.8 mm, or 1 mm.

[0063] In one embodiment, the metal plate is preferably a steel plate.

[0064] In one embodiment, the first adhesive layer and / or the second adhesive layer comprises at least one of polyester compounds, polyvinyl acetate compounds, and polyolefin compounds, such as, but not limited to, EVA film.

[0065] In one embodiment, the thickness of the second adhesive layer and / or the second adhesive layer does not exceed 0.5 mm.

[0066] One embodiment of the present invention provides a method for preparing the above-mentioned composite board, comprising: sequentially laying one or more layers of polyamide sheet and one or more layers of fiber fabric, optional first adhesive layer, metal plate, optional second adhesive layer, one or more layers of polyamide sheet and one or more layers of fiber fabric, and then molding to obtain the composite board.

[0067] In one embodiment, the optional first adhesive layer and the optional second adhesive layer can be laid as needed.

[0068] In one embodiment, the compression molding process includes: controlling the compression molding temperature at 20-80°C above the melting point of the polyamide sheet, preheating at 1.5-5 MPa for 5-10 minutes, venting, and maintaining at a pressure of 5-10 MPa for 5-10 minutes.

[0069] In some embodiments, the polyamide sheet is dried to a moisture content of less than 1000 ppm, and further to 100-500 ppm, before compression molding.

[0070] In one embodiment, the polyamide resin has a melting point of 240–270°C, and the temperature is controlled at 280–330°C during compression molding. The resin is preheated at 1.5–5 MPa for 5–10 minutes, vented, and held at 8 MPa pressure for 5–10 minutes.

[0071] In one embodiment, the polyamide resin has a melting point of 260-270°C, and the temperature is controlled at 285-320°C during compression molding. It is preheated at 1.5-5 MPa for 5-10 minutes, vented, and held at 8 MPa pressure for 5-10 minutes.

[0072] In one embodiment, the polyamide sheet has a melting point of 270–320°C, and the molding temperature is controlled at 300–340°C. It is preheated at 1.5–5 MPa for 5–10 minutes, vented, and held at 8 MPa pressure for 5–10 minutes.

[0073] In one embodiment, the polyamide sheet has a melting point of 295–300°C, and the molding temperature is controlled at 338–340°C. It is preheated at 1.5–5 MPa for 5–10 minutes, vented, and held at 8 MPa pressure for 5–10 minutes.

[0074] In one embodiment, the apparatus used for compression molding can be a double steel strip compression molding machine or a flat vulcanizing machine.

[0075] One embodiment of the present invention provides the application of the above-described composite material as a battery pack protective plate.

[0076] One embodiment of the present invention provides a battery pack protective plate (e.g., a battery pack bottom protective plate) comprising the aforementioned composite material.

[0077] One embodiment of the present invention provides a vehicle including the battery pack guard described above.

[0078] One embodiment of the composite board of the present invention is made by hot pressing (e.g., molding) polyamide sheets, fiber fabrics and metal plates. During the molding process, the polyamide sheets are impregnated with the fiber fabric layer, thereby effectively bonding with the metal plate. The use of polyamide sheets with a specific shear viscosity can significantly improve the molding impregnation effect, further improving the interlayer bonding force between the surface layer and the metal plate, thereby significantly improving the impact resistance of the composite board and making it more suitable for application in battery pack protective plates. In addition, the peel strength and impact resistance of the product can be further improved by setting an adhesive layer.

[0079] The following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates a composite board according to an embodiment of the present invention and its preparation. The raw materials and testing methods involved in each embodiment and comparative example are as follows.

[0080] raw material

[0081] Bio-based pentanediamine and adipic acid were purchased from Kaisai (Jinxiang) Biomaterials Co., Ltd., and other raw materials not explicitly stated were commercially available.

[0082] The steel plate (grade DP780), 0.8mm thick, was purchased from Shanghai Baosteel; the PP was purchased from LG Chem in South Korea.

[0083] The viscosity of the polyamide resin used as the raw material for polyamide sheets was adjusted by solid-phase thickening. The solid-phase thickening temperature was 120–200℃, and the time was 4–24 h.

[0084] Twill fiberglass cloth (hereinafter referred to as twill fiberglass cloth): thickness 0.35mm, face weight 600g / m² 2 The continuous fiber orientation is 0° / 90°. The raw material glass fiber is China Jushi E6DR17-1200-352B; the twill glass fiber cloth is EWR600T twill and was purchased from Taian Juli Co., Ltd.

[0085] Plain weave fiberglass cloth (hereinafter referred to as plain weave fiberglass cloth): thickness 0.35mm, face weight 600g / m² 2 The continuous fiber orientation is 0° / 90°; the raw material glass fiber is China Jushi E6DR17-1200-352B; the plain weave glass fiber cloth is EWR600T plain weave, purchased from Taian Juli Co., Ltd.

[0086] EVA film: 100μm thick, purchased from Shanghai Sendi Chemical.

[0087] Test methods

[0088] 1. Viscosity: The viscosity of the polyamide sheet was measured using an Anton Paar MCR302 rheometer, with a shear rate of 1 s. -1 The frequency is 1Hz and the heating rate is 3℃ / s.

[0089] 2. Elongation at break: The reference test standard is ASTM D 3039. The main method is to use a universal testing machine to apply a tensile load to the specimen at a loading speed of 2 mm / s until the specimen breaks or reaches the predetermined elongation. Then, the ratio of the elongation after stretching to the length before stretching is measured and expressed as a percentage.

[0090] Preparation Example

[0091] Preparation Example 1 - Polyamide Sheet A1

[0092] Bio-based polyamide A1 (melting point 266℃) is heated and melted. The melt is cast through a T-die to a cooling roller with a surface temperature of 50℃. Then, it is drawn and wound to obtain polyamide sheet A1. Bio-based polyamide A1 is obtained by copolymerizing bio-based pentanediamine, hexamethylenediamine, adipic acid and terephthalic acid in a molar ratio of 5.05:5:4:6.

[0093] The resulting polyamide sheet A1 has a thickness of 0.1 mm and a density of 1.17 g / cm³. 3 It has a melting point of 266℃ and an elongation at break of >70%. At 330℃ and a shear rate of 1s... -1 The viscosity at that time was 413 Pa·s.

[0094] Preparation Example 2 - Polyamide Sheet A2

[0095] Polyamide sheet A2 (melting point 266°C) was prepared using the same process as in Preparation Example 1, except that the raw material used was bio-based polyamide resin A2 that had undergone solid-phase thickening.

[0096] The resulting polyamide sheet A2 has a thickness of 0.1 mm and a density of 1.17 g / cm³. 3It has a melting point of 266℃ and an elongation at break of >70%. At 330℃ and a shear rate of 1s... -1 The viscosity at that time was 583 Pa·s.

[0097] Preparation Example 3 - Polyamide Sheet A3

[0098] Polyamide sheet A3 (melting point 266°C) was prepared using the same process as in Preparation Example 1, except that the raw material used was bio-based polyamide resin A3 that had undergone solid-phase thickening.

[0099] The resulting polyamide sheet A3 has a thickness of 0.1 mm and a density of 1.17 g / cm³. 3 It has a melting point of 266℃ and an elongation at break of >70%. At 330℃ and a shear rate of 1s... -1 The viscosity at that time was 450 Pa·s.

[0100] Preparation Example 4 - Polyamide Sheet B1

[0101] Polyamide sheet B1 (melting point 300℃) was prepared using the same process as in Preparation Example 1, the only difference being that the raw material used was bio-based polyamide resin B1. Bio-based polyamide resin B1 was obtained by copolymerizing bio-based pentanediamine, hexamethylenediamine, adipic acid, and terephthalic acid in a molar ratio of 5.05:5:2.8:7.2.

[0102] The resulting polyamide sheet B1 has a thickness of 0.1 mm and a density of 1.18 g / cm³. 3 It has a melting point of 300℃ and an elongation at break of >50%. At 340℃ and a shear rate of 1s... -1 The viscosity at that time was 875 Pa·s.

[0103] Comparative Preparation Example 1 - Polyamide Sheet A4

[0104] Polyamide sheet A4 (melting point 266°C) was prepared using the same process as in Preparation Example 1, except that the raw material used was bio-based polyamide resin A4 that had undergone solid-phase thickening.

[0105] The resulting polyamide sheet A4 has a thickness of 0.1 mm and a density of 1.17 g / cm³. 3 It has a melting point of 266℃ and an elongation at break of >70%. At 330℃ and a shear rate of 1s... -1 The viscosity at that time was 1944 Pa·s.

[0106] Comparative Preparation Example 2 - Polyamide Sheet B2

[0107] Polyamide sheet B2 (melting point 300°C) was prepared using the same process as in Preparation Example 1, except that the raw material used was bio-based polyamide resin B2 that had undergone solid-phase thickening.

[0108] The resulting polyamide sheet B2 has a thickness of 0.1 mm and a density of 1.18 g / cm³. 3 It has a melting point of 300℃ and an elongation at break of >50%. At 340℃ and a shear rate of 1s... -1 The viscosity at that time was 1263 Pa·s.

[0109] Comparative Preparation Example 3 - Continuous Fiber Reinforced PP Unidirectional Prepreg Tape

[0110] The components of the continuous fiber reinforced PP unidirectional prepreg tape, by weight percentage, are: PP 30%, continuous long glass fiber (monofilament diameter 17μm, linear density 2400Tex, purchased from Taishan Glass Fiber Co., Ltd.) 65%, antioxidant 1010 0.3%, antioxidant 168 0.3%, lubricant (calcium stearate) 0.4%, and compatibilizer (PP-g-MAH) 4%.

[0111] The preparation method of the continuous fiber reinforced PP unidirectional prepreg tape:

[0112] (1) The raw materials of the continuous fiber reinforced PP unidirectional prepreg tape, excluding continuous long glass fibers, are mixed and melt-extruded using a twin-screw extruder. The extruded melt is filtered through a melt filter and enters the impregnation die. The twin-screw extruder is an eight-zone heating mode, with zone 1 to zone 8 (feeding to the die head) temperatures of 130℃, 150℃, 190℃, 230℃, 230℃, 230℃, 230℃, and 230℃ respectively. The screw speed is 400 r / min. The die head temperature is 230℃. The length-to-diameter ratio of the twin-screw extruder is 36:1. The temperature of the melt filter is 230℃.

[0113] (2) The continuous long glass fiber is unwound from the yarn frame by the tension controller, passes through the yarn splitting frame, and enters the yarn spreading system to fully spread each filament bundle. Then it enters the yarn drying device for preheating. The temperature of the yarn drying device is set at 85℃. Then it enters the impregnation die head, where the continuous long glass fiber is impregnated with the melt.

[0114] (3) The impregnated continuous long glass fibers are molded and cooled using a four-roll mill, with the circulating water temperature in the four-roll mill set to 40℃. Then, they enter a traction device for further cooling and edge trimming, with a traction speed of 8 m / min. Finally, they are wound into a roll in an automatic winding machine at a winding speed of 8 m / min, resulting in a unidirectional prepreg tape with a thickness of 0.2 mm. During the preparation process, the screw speed of the twin-screw extruder and the winding speed of the automatic winding machine are controlled to ensure that the content of continuous long glass fibers in the unidirectional prepreg tape is 65 wt%.

[0115] Example 1

[0116] Multiple polyamide sheets A1 and multiple twill fiberglass cloths prepared in Preparation Example 1 are cut into mold sizes. A release cloth is placed on the upper and lower layers of the mold, and polyamide sheets A1 and twill fiberglass cloths are placed in the middle. Polyamide sheets A1 serve as the first polyamide sheet layer 101. Twill fiberglass cloth is laid on the first polyamide sheet layer 101 as the first inner layer 103. Polyamide sheets A1 are laid on the first inner layer 103 as the second polyamide sheet layer 102. The polyamide sheets A1 and twill fiberglass cloth together serve as the first surface layer 100. Then, a steel plate 200 (with a smooth surface) is placed as the core layer. Polyamide sheets A1 and twill fiberglass cloths are placed in sequence on the core layer. A triamide sheet layer 301 is formed, on which a polyamide sheet A1 is laid as a first intermediate layer 303. A twill fiberglass cloth is laid as a second intermediate layer 304 on the first intermediate layer 303. A polyamide sheet A1 is laid as a third intermediate layer 305 on the second intermediate layer 304. A twill fiberglass cloth is laid as a fourth intermediate layer 306 on the third intermediate layer 305. A polyamide sheet A1 is laid as a fifth intermediate layer 307 on the fourth intermediate layer 306. A polyamide sheet A1 is laid as a fourth polyamide sheet layer 302 on the fifth intermediate layer 307. The polyamide sheet A1 and the twill fiberglass cloth together form a second surface layer 300. The resulting structure is then molded on a flat vulcanizing machine. The specific process is as follows:

[0117] The molding press temperature was controlled at 310℃, preheated at 3MPa for 8 minutes, vented, and held at 8MPa pressure for 6 minutes to produce a composite sheet with a thickness of 2.4mm. The structure of the composite sheet is as follows. Figure 1 As shown.

[0118] Example 2

[0119] The composite board was prepared using the same method as in Example 1, except that polyamide sheet A2 was used instead of polyamide sheet A1. The structure of the composite board is as follows. Figure 1 As shown.

[0120] Example 3

[0121] The composite board was prepared using the same method as in Example 1, except that polyamide sheet A3 was used instead of polyamide sheet A1. The structure of the composite board is as follows. Figure 1 As shown.

[0122] Example 4

[0123] The composite board was prepared using the same method as in Example 1, except that plain-weave fiberglass cloth was used instead of twill-weave fiberglass cloth. The structure of the composite board is as follows: Figure 1 As shown.

[0124] Example 5

[0125] Multiple polyamide sheets B1 prepared in Preparation Example 4 and multiple twill fiberglass cloths were cut to the size of a mold. A release cloth was placed on the upper and lower layers of the mold, and polyamide sheets B1 and twill fiberglass cloths were placed in the middle. Polyamide sheets B1 served as the first polyamide sheet layer 101. Twill fiberglass cloths were laid on the first polyamide sheet layer 101 as the first inner layer 103. Polyamide sheets B1 were laid on the first inner layer 103 as the second inner layer 104. Polyamide sheets B1 were laid on the second inner layer 104 as the second polyamide sheet layer 102. The polyamide sheets B1 and twill fiberglass cloths together served as the first surface layer 100. Then, a steel plate 200 (with a smooth surface) was placed as the core layer. Polyamide sheets B1 and twill fiberglass cloths were placed in sequence on the core layer. Polyamide sheets B1 served as the third surface layer 102. A polyamide sheet layer 301 is formed. A polyamide sheet B1 is laid on top of the third polyamide sheet layer 301 as a first intermediate layer 303. A twill fiberglass cloth is laid on top of the first intermediate layer 303 as a second intermediate layer 304. A polyamide sheet B1 is laid on top of the second intermediate layer 304 as a third intermediate layer 305. A polyamide sheet B1 is laid on top of the third intermediate layer 305 as a fourth intermediate layer 306. A twill fiberglass cloth is laid on top of the fourth intermediate layer 306 as a fifth intermediate layer 307. A polyamide sheet B1 is laid on top of the fifth intermediate layer 307 as a sixth intermediate layer 308. A polyamide sheet B1 is laid on top of the sixth intermediate layer 308 as a fourth polyamide sheet layer 302. The polyamide sheet B1 and the twill fiberglass cloth together form a second surface layer 300. The resulting structure is then molded on a flat vulcanizing machine. The specific process is as follows:

[0126] The molding press temperature was controlled at 340℃, preheated at 3MPa for 8 minutes, vented, and held at 8MPa pressure for 6 minutes to produce a composite sheet with a thickness of 2.6mm. The structure of the composite sheet is as follows. Figure 1 As shown.

[0127] Example 6

[0128] Multiple polyamide sheets A1, multiple twill fiberglass cloths, and multiple EVA films prepared in Preparation Example 1 are cut into mold sizes. A release cloth is placed on the upper and lower layers of the mold. Polyamide sheets A1, twill fiberglass cloths, and EVA films are then placed in the middle. Polyamide sheets A1 serve as the first polyamide sheet layer 101. Twill fiberglass cloths are laid on the first polyamide sheet layer 101 as the first inner layer 103. Polyamide sheets A1 are laid on the first inner layer 103 as the second polyamide sheet layer 102. The polyamide sheets A1 and twill fiberglass cloths together serve as the first surface layer 100. EVA films are then laid on the first surface layer 100 as the first adhesive layer 40. A steel plate 200 (with a smooth surface) is then placed as the core layer. EVA films, polyamide sheets A1, and twill fiberglass cloths are then placed on the core layer. The steel plate is first... An EVA film is laid on layer 200 as a second adhesive layer 50. A polyamide sheet A1 is laid on the second adhesive layer 50 as a third polyamide sheet layer 301. A polyamide sheet A1 is laid on the third polyamide sheet layer 301 as a first intermediate layer 303. A twill fiberglass cloth is laid on the first intermediate layer 303 as a second intermediate layer 304. A polyamide sheet A1 is laid on the second intermediate layer 304 as a third intermediate layer 305. A twill fiberglass cloth is laid on the third intermediate layer 305 as a fourth intermediate layer 306. A polyamide sheet A1 is laid on the fourth intermediate layer 306 as a fifth intermediate layer 307. A polyamide sheet A1 is laid on the fifth intermediate layer 307 as a fourth polyamide sheet layer 302. The polyamide sheet A1 and the twill fiberglass cloth together form the second surface layer 300. The resulting structure is then molded on a flat vulcanizing machine. The specific process is as follows:

[0129] The molding press temperature was controlled at 310℃, preheated at 3MPa for 8 minutes, vented, and held at 8MPa pressure for 6 minutes to produce a composite sheet with a thickness of 2.4mm. The structure of the composite sheet is as follows. Figure 2 As shown.

[0130] Comparative Example 1

[0131] The composite board was prepared using the same method as in Example 1, except that polyamide sheet A4 was used instead of polyamide sheet A1.

[0132] Comparative Example 2

[0133] The composite board was prepared using the same method as in Example 5, except that polyamide sheet B2 was used instead of polyamide sheet B1.

[0134] Comparative Example 3

[0135] The continuous fiber-reinforced PP unidirectional prepreg tape prepared in Comparative Preparation Example 3 was cut to the size of a template. A layer of release cloth or release paper was placed on the upper and lower layers of the template. Three layers of PP unidirectional prepreg tape were laid between the upper and lower layers at 0° and 90°. Then, a steel plate with a thickness of 0.8 mm (with a smooth surface) was placed as an intermediate layer. On the intermediate layer, five layers of PP unidirectional prepreg tape were laid at 0° and 90°. The resulting structure was then molded on a double steel strip molding composite machine. The specific process is as follows:

[0136] The temperature of the molding press was controlled at 200℃, preheated for 6 minutes at 1.5MPa, and then vented. The press was then held at 10MPa for 20 minutes to obtain a composite board with a thickness of 2.4mm.

[0137] The composite boards prepared in each embodiment and comparative example were tested respectively, and the test results are shown in Table 1.

[0138] I. Peel Performance Test: The peel strength test of the bottom panel of the battery pack composite protective structure was conducted according to the test method for roller peel strength of sandwich structures (GB / T 1457-2022). The peel strength of the adhesive bond between the panel and the core was determined by peeling the panel from the sandwich structure using a flanged cylinder. One end of the panel was attached to the cylinder, and the other end was attached to a clamp. A loading strip was connected to the flange. When the loading strip was stretched, the cylinder rolled upwards, thus peeling the panel from the sandwich structure. The loading strip on the flange and the panel on the cylinder were at a certain distance apart. The roller peel strength of the sandwich structure is actually the peel torque per unit width at which the panel separates from the core.

[0139] II. Impact Performance Test:

[0140] 1. A sphere is used as an impact head to impact the bottom protection plate of the battery pack to simulate the working condition of the bottom of the vehicle being hit by a foreign object. The diameter of the sphere is 25mm, the weight is 10kg, the impact energy is 300J, and the impact speed is 8.5m / s. The center point of the battery protection plate and four points around the center point are selected as impact points. Five impacts are performed. The surface of the bottom protection plate should not have any penetration cracks, and the internal aluminum plate should not have any cracks and the dent deformation should be <4mm.

[0141] The diameter of the delamination and hollow areas on the battery pack bottom protector after impact was measured using vernier calipers. Measurements were repeated three times for each impact point to determine the average value. The impact point with the largest hollow area diameter was selected and recorded as the hollow area size of the battery pack bottom protector. The degree of hollowness was determined according to the following grading standards:

[0142] R1: No layering;

[0143] R2: Slight delamination, hollow area diameter <4mm;

[0144] R3: Slight delamination, hollow area diameter <8mm;

[0145] R4: Layered, hollow area diameter > 8mm.

[0146] 2. Use a 50mm extrusion head to extrude the weakest part at the bottom of the power battery assembly at a speed of 1mm / s; when the outer shell deformation reaches Amm, the supporting force should exceed BkN. A is the maximum effective deformation space from the bottom of the power battery assembly outer shell to the cell, and B = 30kN. Fix the bottom guard plate on the grooved lower clamp, and use a 50mm extrusion ball head to extrude the bottom guard plate at a speed of 1mm / s. Record the force-displacement curve using a universal tensile testing machine, and read the deformation and supporting force from the curve.

[0147]

[0148] Comparing Examples 1 to 5 with Comparative Example 3, the main difference lies in the surface layer: Examples 1 to 5 use alternating layers of polyamide sheets and fiber fabrics with specific shear viscosities, while Comparative Example 3 uses PP unidirectional prepreg tape. According to Table 1, the peel strength and impact resistance of the composite panels from Examples 1 to 5 are significantly greater than those from Comparative Example 3. Therefore, Examples 1 to 5 of this invention, by using polyamide sheets with specific viscosities as raw materials, can achieve comprehensive optimization of the peel strength and impact resistance of the composite panels, facilitating their application as battery pack protective plates.

[0149] The difference between Example 1 and Comparative Example 1 is that the viscosity of the polyamide sheet used is different. In Example 1, the polyamide sheet A1 was viscosed at 300°C and a shear rate of 1 s. -1 The viscosity of the composite material was 413 Pa·s, while the corresponding viscosity of Comparative Example 1 was 1944 Pa·s. According to the results in Table 1, the peel strength and impact resistance of the composite material of Example 1 were significantly higher than those of Comparative Example 1. The performance comparison results of the composite materials of Example 5 and Comparative Example 2 were similar to those of Example 1 and Comparative Example 1. Therefore, by using polyamide sheets with specific viscosities under specific conditions to prepare composite materials while keeping the melting point of the polyamide sheet constant, it is possible to achieve comprehensive optimization of peel strength and impact resistance.

[0150] The difference between Example 1 and Example 4 is that Example 1 uses twill fiberglass cloth, while Example 4 uses plain fiberglass cloth. According to the results in Table 1, the peel strength and impact resistance of the composite board in Example 1 are significantly better than those in Example 4.

[0151] The difference between Example 1 and Example 6 is that Example 1 uses a polyamide sheet and fiber fabric laminate as the surface layer, while Example 6 adds an adhesive layer to the structure of Example 1. According to the results in Table 1, the composite material of Example 6 exhibits superior glass strength and impact resistance compared to Example 1.

[0152] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A composite board, characterized in that, The system comprises a first surface layer, a core layer, and a second surface layer stacked sequentially. The first surface layer and / or the second surface layer comprises one or more layers of polyamide sheets and one or more layers of fiber fabric, wherein the fiber fabric is disposed between the polyamide sheets. The core layer comprises a metal plate. The polyamide sheet has a melting point of 240–320°C, and its melting point is between 280–340°C and a shear rate of 1 second. -1 The viscosity under these conditions is 400–900 Pa·s.

2. The composite board according to claim 1, characterized in that, The polyamide sheet has a melting point of 240–270°C, and its melting point is within the range of 300–330°C with a shear rate of 1 second. -1 The viscosity under the given conditions is 400–600 Pa·s; and / or, The polyamide sheet has a melting point of 270–320°C, and its melting point is between 300–340°C and a shear rate of 1 second. -1 The viscosity under these conditions is 700–900 Pa·s.

3. The composite board according to claim 1, characterized in that, The polyamide sheet has a melting point of 260–270°C, and its melting point is 325–330°C with a shear rate of 1 second. -1 The viscosity under the given conditions is 400–500 Pa·s, more specifically 400–450 Pa·s; and / or, The polyamide sheet has a melting point of 295–300°C, and its melting point is 338–340°C with a shear rate of 1 second. -1 The viscosity under the given conditions is 800–900 Pa·s, more specifically 850–900 Pa·s; and / or, The density of the polyamide sheet is 1.0–1.2 g / cm³. 3 ; and / or, The polyamide sheet has a moisture content of less than 500 ppm, more specifically 50 to 500 ppm; and / or, The polyamide sheet has an elongation at break of >50%, further >70%, and even further >90%; and / or, The thickness of the polyamide sheet is 0.05–1 mm, and more specifically 0.05–0.3 mm.

4. The composite board according to claim 1, characterized in that, The composite board further includes a first adhesive layer disposed between the first surface layer and the core layer; and / or, The composite board further includes a second adhesive layer, which is disposed between the second surface layer and the core layer; and / or, The first adhesive layer and / or the second adhesive layer comprise at least one of polyester compounds, polyvinyl acetate compounds, and polyolefin compounds; and / or, The thickness of the second adhesive layer and / or the second adhesive layer does not exceed 0.5 mm; and / or, The metal plate is in contact with the first surface layer or the first adhesive layer through the first surface, and with the second surface layer or the second adhesive layer through the second surface.

5. The composite board according to claim 1, characterized in that, The polyamide sheet is made from polyamide resin, the monomers of which include diamines and diacids. The diamines include pentanediamine; the diacids include one or more aliphatic diacids with 4 to 18 carbon atoms and aromatic diacids with 8 to 10 carbon atoms; and / or, The diamine includes pentanediamine and other diamines, wherein the other diamines include one or more aliphatic diamines having 4 to 16 carbon atoms, and the aliphatic diamines having 4 to 16 carbon atoms do not include pentanediamine; further, the other diamines include one or more of butanediamine, hexanediamine, heptadecanediamine, octanediamine, nonanediamine, decanedanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, and hexadecanediamine; and / or, The aliphatic dicarboxylic acids having 4 to 18 carbon atoms include one or more of the following: oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid; and / or, The aromatic dicarboxylic acid includes one, two, or three of terephthalic acid, isophthalic acid, and phthalic acid; and / or, The polyamide resin is obtained by copolymerization of pentanediamine, hexamethylenediamine, adipic acid and terephthalic acid, and has a melting point of 240-320°C.

6. The composite board according to claim 1, characterized in that, Based on the total weight of the polyamide sheet and fiber fabric of the first or second outer layer, the fiber fabric has a mass content of 50-85%, more specifically 60-70%; and / or, The fiber fabric includes continuous fiber cloth and / or continuous fiber yarn; and / or, The fiber fabric comprises continuous fibers, which include one or more of glass fibers, carbon fibers, basalt fibers, aramid fibers, polyolefin fibers, and natural fibers; and / or, The fabric includes one or more of the following: checkered fabric, non-curling fabric, and three-dimensional fabric; and / or, The continuous fibers in the fibrous fabric cross at 0–90°; and / or, The thickness of the fiber fabric is 0.05–0.5 mm, more specifically 0.1–0.4 mm; and / or, The basis weight of the fiber fabric is 650 g / m². 2 The following values ​​are further specified as 200–650 g / m³. 2 .

7. A method for preparing a composite board according to any one of claims 1 to 6, characterized in that, include: The composite board is prepared by sequentially laying one or more polyamide sheets and one or more fiber fabrics, an optional first adhesive layer, the metal plate, an optional second adhesive layer, and one or more polyamide sheets and one or more fiber fabrics, followed by compression molding.

8. The preparation method according to claim 7, characterized in that, The compression molding process includes: controlling the compression molding temperature to be 20-80°C above the melting point of the polyamide sheet, preheating for 5-10 minutes under 1.5-5 MPa conditions, venting, and maintaining the pressure at 5-10 MPa for 5-10 minutes.

9. The composite material according to any one of claims 1 to 6 or the composite material prepared by the preparation method according to claim 7 or 8 as a battery pack protective plate.

10. A battery pack protective plate, comprising a composite material according to any one of claims 1 to 6 or a composite material prepared by the preparation method according to claim 7 or 8.

11. A vehicle comprising the battery pack guard of claim 10.

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