Multi-layer composite structure, preparation method, battery cover and electronic equipment

Abstract

The invention provides a multi-layer composite structure, a preparation method, a battery cover and electronic equipment, the multi-layer composite structure is formed by a plurality of stacked fiber layers, each fiber layer is formed by dipping a fiber sheet in a pre-polymerized glue solution and then curing the fiber sheet, the fiber sheet in at least one fiber layer adopts poly (p-phenylene benzobisoxazole) fiber, and the fiber sheet in the at least one fiber layer is made of a poly (p-phenylene benzobisoxazole) fiber. The PBO fiber is prepared from the PBO fiber. Therefore, the multi-layer composite structure has higher strength and modulus, energy is absorbed and dispersed when the multi-layer composite structure is impacted, the reliability of the multi-layer composite structure is not influenced when the multi-layer composite structure is impacted on the basis of thinning and weight reduction, and the battery cover formed by the multi-layer composite structure has better anti-puncture performance.

Description

Technical Field

[0001] The present application relates to the technical field of terminals, and in particular, to a multi-layer composite structure, a preparation method, a battery cover, and an electronic device. Background Art

[0002] The appearance shell parts for consumer electronic devices such as mobile phones, tablets, or PCs mainly play the roles of appearance decoration and protecting the use safety of components such as the built-in battery of the electronic device. At present, consumer electronic products, especially folding models, have strong demands for reducing the weight and thickness of the whole machine and high reliability, and the battery cover in the appearance shell parts is one of the main scenarios for reducing thickness and weight.

[0003] Under the current battery cover structure design of folding devices, traditional glass fiber composite materials can no longer meet the design requirements of reducing thickness and weight, and the reliability risk of the battery cover composed of glass fiber composite materials is relatively high. Especially in the scenario of the whole machine falling, the anti-puncture performance is poor, and it is impossible to complete the design of reducing the thickness and weight of the battery cover on the basis of providing reliable drop protection for the battery cover. Summary of the Invention

[0004] The present application provides a multi-layer composite structure, a preparation method, a battery cover, and an electronic device to solve the problem that the battery cover in an electronic device cannot provide reliable drop protection after reducing its thickness and weight.

[0005] According to a first aspect in an embodiment of the present invention, a multi-layer composite structure is provided, including: a plurality of fiber layers stacked, and each fiber layer is formed by curing after impregnating a fiber sheet with a prepolymer solution; wherein, the fiber sheet in at least one fiber layer is made of poly(p-phenylene benzobisoxazole) PBO fiber. In this way, due to the high strength and high modulus characteristics of PBO fiber relative to glass fiber, when the multi-layer composite structure is impacted, the absorption and dispersion of energy are better, and thus, on the basis of reducing thickness and weight, its reliability when being impacted is not affected.

[0006] In a feasible implementation manner, at least one fiber layer among the plurality of fiber layers is a first fiber layer; the fiber sheet in each first fiber layer is arranged by PBO fiber filaments with the same extending direction and in a straightened state. In this way, the density of the PBO fiber filaments in the first fiber layer can be increased through the unidirectional arrangement of the PBO fiber filaments, thereby reducing the influence of the prepolymer solution in the fiber layer on the strength and modulus of the fiber layer.

[0007] In a feasible implementation manner, each fiber layer among the plurality of fiber layers is a first fiber layer; the extending directions of the PBO fiber filaments in adjacent first fiber layers are different. In this way, the absorption and dispersion of energy by the formed multi-layer composite structure can be improved, and its anti-puncture effect can be enhanced.

[0008] In a feasible implementation manner, the included angle between the extending directions of the PBO fiber bundles in adjacent first fiber layers is a right angle.

[0009] In a feasible implementation manner, each of the multiple fiber layers is a first fiber layer; the PBO fiber bundles in the first fiber layers of the uppermost layer and the lowermost layer in the multi-layer composite structure extend in a first direction; the PBO fiber bundles in the other first fiber layers in the multi-layer composite structure extend in a second direction; the first direction is different from the second direction. In this way, the absorption and dispersion of energy by the formed multi-layer composite structure can be improved, and its anti-puncture effect can be enhanced.

[0010] In a feasible implementation manner, the included angle between the first direction and the second direction is a right angle.

[0011] In a feasible implementation manner, the mass ratio of the prepolymer glue solution in each first fiber layer is 30% - 45%; the thickness of each first fiber layer is 0.04 mm - 0.2 mm. In this way, while the first fiber layer can be cured by the prepolymer glue solution, the content of the prepolymer glue solution in the first fiber layer can be reduced, and the strength and modulus of the first fiber layer can be improved.

[0012] In a feasible implementation manner, the other fiber layers among the multiple fiber layers except the first fiber layer are third fiber layers; the fiber sheets in the third fiber layers are arranged by first fiber bundles with the same extending direction and in a straightened state, and the first fiber bundles are any one of glass fiber, aramid fiber, ceramic fiber, and carbon fiber; multiple third fiber layers are stacked, and at least one first fiber layer is arranged between adjacent third fiber layers. In this way, the bonding force between different fiber layers can be improved by combining PBO fiber with other fibers, and further the overall strength of the multi-layer composite structure can be enhanced.

[0013] In a feasible implementation manner, the PBO fiber bundles in the first fiber layer extend in a third direction; the first fiber bundles in the third fiber layer adjacent to the first fiber layer extend in a fourth direction; the extending directions of the first fiber bundles in adjacent third fiber layers are different; the third direction is different from the fourth direction. In this way, the strength of the fiber layer can be improved by weaving the fibers, and further the anti-puncture effect of the multi-layer composite structure can be enhanced.

[0014] In a feasible implementation manner, the included angle between the third direction and the fourth direction is a right angle.

[0015] In a feasible implementation manner, at least one of the multiple fiber layers is a second fiber layer; the fiber sheets in each second fiber layer are formed by weaving PBO fiber bundles with extending directions of a fifth direction and a sixth direction, and the fifth direction is different from the sixth direction. In this way, the fiber layer can be formed by the fiber sheets formed by weaving, so as to avoid the yarn dispersion of the fiber sheets composed of PBO fiber bundles.

[0016] In a feasible implementation, each of the multiple fiber layers is a second fiber layer; the included angle between the fifth direction and the sixth direction is a right angle.

[0017] In a feasible implementation, the mass percentage of the prepolymer adhesive solution in each second fiber layer is 45% - 55%; the thickness of each second fiber layer is 0.1 mm - 0.2 mm.

[0018] In a feasible implementation, the other fiber layers in the multiple fiber layers except the second fiber layer are fourth fiber layers; the fiber sheets in the fourth fiber layers are formed by weaving second fiber bundles with the extending directions of the fifth direction and the sixth direction, and the second fiber bundles are any one of glass fiber, aramid fiber, ceramic fiber, and carbon fiber; multiple fourth fiber layers are stacked, and at least one second fiber layer is arranged between adjacent fourth fiber layers. In this way, the binding force between different fiber layers can be improved by combining PBO fiber with other fibers, and further the strength of the overall multi-layer composite structure can be improved.

[0019] In a feasible implementation, the mass percentage of the prepolymer adhesive solution in each fiber layer is 30% - 60%, the thickness of each fiber layer is greater than or equal to 0.03 mm and less than or equal to 0.3 mm.

[0020] According to the second aspect of the embodiments of the present invention, a method for preparing a multi-layer composite structure is provided, including: placing epoxy resin monomer, curing agent, accelerator, dispersant, and filler in a prepreg and fully stirring and pre-curing to form a prepolymer adhesive solution; impregnating fiber sheets in the prepolymer adhesive solution and performing curing treatment to obtain fiber layers; cutting, stacking, and pressing multiple fiber layers to obtain a multi-layer composite structure; wherein, the fiber sheets in at least one fiber layer are made of PBO fiber.

[0021] In a feasible implementation, impregnating fiber sheets in the prepolymer adhesive solution and performing curing treatment to obtain fiber layers includes: placing a fiber bobbin in position, and arranging fiber bundles unidirectionally through yarn laying to make multiple fiber sheets; the fiber bundles in at least one fiber sheet are PBO fiber bundles; impregnating multiple fiber sheets in the prepolymer adhesive solution respectively; controlling the mass percentage of the prepolymer adhesive solution in the multiple impregnated fiber sheets and the thickness of the multiple impregnated fiber sheets; performing curing treatment on the multiple impregnated fiber sheets respectively to obtain multiple fiber layers.

[0022] In a feasible implementation, multiple fiber layers are cut, stacked, and pressed to obtain a multi-layer composite structure, including: cutting multiple fiber layers respectively to obtain multiple fiber layers of a preset size; stacking the cut multiple fiber layers; wherein, the extending directions of the fiber bundles in adjacent fiber layers are different, or, the fiber bundles in the topmost and bottommost fiber layers extend in a first direction, and the fiber bundles in the other fiber layers except the topmost and bottommost fiber layers extend in a second direction, and the first direction is different from the second direction; pressing the stacked multiple fiber layers to obtain a multi-layer composite structure.

[0023] In a feasible implementation, the mass ratio of the prepolymer solution in each fiber layer is 30% - 45%; the thickness of each fiber layer is 0.04 mm - 0.2 mm.

[0024] In a feasible implementation, impregnating fiber sheets in a prepolymer solution and performing a curing treatment to obtain fiber layers, including: making multiple woven fiber sheets by weaving fiber bundles; at least one of the fiber bundles in the woven fiber sheets is a PBO fiber bundle; impregnating the multiple woven fiber sheets in the prepolymer solution respectively; controlling the mass ratio of the prepolymer solution in the multiple impregnated woven fiber sheets and the thickness of the multiple impregnated woven fiber sheets; performing a curing treatment on the multiple impregnated woven fiber sheets respectively to obtain multiple fiber layers.

[0025] In a feasible implementation, multiple fiber layers are cut, stacked, and pressed to obtain a multi-layer composite structure, including: cutting multiple fiber layers respectively to obtain multiple fiber layers of a preset size; stacking the cut multiple fiber layers; pressing the stacked multiple fiber layers to obtain a multi-layer composite structure.

[0026] In a feasible implementation, the mass ratio of the prepolymer solution in each fiber layer is 45% - 55%; the thickness of each fiber layer is 0.1 mm - 0.2 mm.

[0027] In a feasible implementation, the grammage of the fiber sheet is 30 g / m 2 ~140 g / m 2 。

[0028] In a feasible implementation, the pressing treatment includes a hot pressing treatment, the temperature of the hot pressing treatment is 100°C - 200°C, the hot pressing time is 10 min - 30 min, and the hot pressing pressure is 0.2 MPa - 0.7 MPa.

[0029] In a feasible implementation, the mass ratio of the prepolymer solution in the fiber layer is 30% - 60%, and the thickness of the fiber layer is 0.03 mm - 0.3 mm.

[0030] In a feasible implementation manner, the cutting method can adopt laser cutting method.

[0031] According to the third aspect in the embodiments of the present invention, a battery cover is provided, including: a substrate layer, the substrate layer includes any one of the aforementioned multilayer composite structures; a decorative layer, the decorative layer is disposed on one side of the substrate layer; through holes are provided on the substrate layer and the decorative layer; a camera lens, the camera lens covers the through hole, and the camera lens is disposed on the side of the battery cover where the decorative layer is provided.

[0032] According to the fourth aspect in the embodiments of the present invention, an electronic device is provided, including: a front panel; a middle frame, the middle frame is disposed on one side of the front panel, and a battery slot is provided inside the middle frame; a battery, the battery is disposed in the battery slot; a battery cover as described above, the battery cover is disposed on the side of the middle frame away from the front panel, and the battery cover is used to protect the battery disposed in the battery slot.

[0033] In the present application, a multilayer composite structure, a preparation method, a battery cover and an electronic device are provided. The multilayer composite structure is formed by stacking a plurality of fiber layers. Each fiber layer is formed by curing a fiber sheet impregnated in a prepolymer solution, and the fiber sheet in at least one fiber layer is made of poly(p-phenylene benzobisoxazole) PBO fiber. In this way, the multilayer composite structure can have higher strength and modulus. When the multilayer composite structure is impacted, it can absorb and disperse energy, and thus, on the basis of reducing thickness and weight, it does not affect its reliability when being impacted. Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of a battery cover;

[0035] Figure 2 It is a schematic structural diagram of the substrate layer of a battery cover;

[0036] Figure 3 It is a schematic structural diagram of the substrate layer of another battery cover;

[0037] Figure 4 It is a schematic structural diagram of the substrate layer of yet another battery cover;

[0038] Figure 5 It is a schematic structural diagram of the substrate layer of yet another mobile phone cover;

[0039] Figure 6 It is a schematic diagram of a multilayer composite structure in an embodiment of the present application;

[0040] Figure 7 It is a schematic diagram of a multilayer composite structure provided with a first fiber layer in an embodiment of the present application;

[0041] Figure 8Schematic diagram of another multi-layer composite structure with a first fiber layer in the embodiments of the present application;

[0042] Figure 9 Schematic diagram of a multi-layer composite structure with a second fiber layer in the embodiments of the present application;

[0043] Figure 10 Schematic diagram of another multi-layer composite structure with a second fiber layer in the embodiments of the present application;

[0044] Figure 11 Schematic diagram of a multi-layer composite structure with multiple fiber layers in the embodiments of the present application;

[0045] Figure 12 Schematic diagram of another multi-layer composite structure with multiple fiber layers in the embodiments of the present application;

[0046] Figure 13 Schematic diagram of the preparation process of a multi-layer composite structure in the embodiments of the present application;

[0047] Figure 14 Schematic diagram of the structure of a battery cover in the embodiments of the present application;

[0048] Figure 15 Schematic diagram of the structure of an electronic device in the embodiments of the present application. Detailed implementation manners

[0049] Next, the technical solutions in the embodiments of the present application will be clearly described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all embodiments. Based on the embodiments of the present application, other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0050] Hereinafter, terms such as "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0051] In addition, in the present application, orientation terms such as "upper" and "lower" are defined relative to the orientation of the components shown in the drawings. It should be understood that these directional terms are relative concepts, which are used for relative description and clarification, and they may change accordingly with the change of the orientation of the components placed in the drawings.

[0052] The following is an explanation of the technical terms mentioned in the embodiments of the present application to facilitate the understanding of those skilled in the art.

[0053] PBO fiber, short for Poly-p-phenylene benzobisoxazole fiber, is a polyamide containing heterocyclic aromatic groups.

[0054] The outer shell parts for consumer electronic devices such as mobile phones, tablets or PCs mainly play the roles of appearance decoration and protecting the built-in batteries, processors and other components of the electronic devices in terms of usage safety. At present, consumer electronic products, especially folding models, have strong demands for reducing the weight and thickness of the whole machine and high reliability. Among the outer shell parts, the battery cover is one of the main scenarios for reducing thickness and weight.

[0055] The folding models described in the embodiments of the present application include, but are not limited to, foldable fixed terminals or mobile terminals such as mobile phones, foldable screen mobile phones, laptop computers, folding brackets, folding PADs, laptop computers, personal digital assistants or wearable devices.

[0056] It should be understood that the folding model electronic devices include inner folding type electronic devices and outer folding type electronic devices. Among them, the inner folding type electronic device is an electronic device in which the flexible screen is located inside the device when the device is in the folded state, and the outer folding type electronic device is an electronic device in which the flexible screen covers the outside of the device when the device is in the folded state.

[0057] Under the current battery cover structure design of folding devices, traditional glass fiber composite materials can no longer meet the design requirements of reducing thickness and weight, and the battery cover made of glass fiber composite materials has a relatively high reliability risk. Especially in the scenario of the whole machine falling, the anti-puncture performance of the battery cover is poor, resulting in a conflict between weight reduction and thickness reduction and protection, and thus the effect of weight reduction and thickness reduction is poor and the anti-puncture performance is also poor.

[0058] Figure 1 It is a schematic structural diagram of a battery cover. As Figure 1 shown, taking the battery cover of a smart phone as an example, the battery cover 1 may include a substrate layer 10 and a decorative layer 20. Among them, the substrate layer 10 is formed by multi-layer stacking of prepregs 11 composed of glass fiber, aramid or other fibers, and the decorative layer 20 can be made of ceramic, glass, leather or other materials, which is not limited in the present application. Since the decorative layer 20 is a structure provided on the surface of the substrate layer 10 for appearance decoration, compared with the substrate layer 10, the thickness of the decorative layer 20 is relatively thin. Therefore, in the process of reducing the thickness and weight of the battery cover 1, the main structural design is for the substrate layer 10, and at the same time, the substrate layer 10 is also an important component affecting the anti-puncture effect of the battery cover 1.

[0059] Figure 2 It is a schematic structural diagram of a substrate layer of a battery cover.Figure 3 It is a schematic structural diagram of another substrate layer of the battery cover. As Figure 2 shown, the common substrate layer 10 is a structure formed by laminating E-glass fiber prepreg 11a with E-glass fiber as the main body. Among them, E-glass fiber is a glass fiber composed of aluminoborosilicate glass. The E-glass fibers in each layer of E-glass fiber prepreg 11a are woven into a network structure to provide puncture resistance.

[0060] As Figure 3 shown, in one embodiment, the glass fiber in the substrate layer 10 can be replaced by S-glass fiber, that is, the substrate layer 10 is a structure formed by laminating S-glass fiber prepreg 11b with S-glass fiber as the main body.

[0061] Among them, S-glass fiber is a kind of aluminosilicate-magnesium glass fiber. Compared with E-glass fiber, S-glass fiber has higher modulus and strength. At the same time, the S-glass fibers in the S-glass fiber prepreg 11b are also woven into a network structure. And during the stacking process, by the way of cross-stacking, the extending directions of the S-glass fibers in adjacent S-glass fiber prepregs 11b are different, which improves the impact resistance of the substrate layer 10 itself. At the same time, the overlapping structure can reduce the generation of cracks during dropping, so as to achieve the effect of puncture resistance.

[0062] However, since the mechanical properties of S-glass fiber are only improved by about 20% compared with E-glass fiber, the actual improvement of the puncture resistance effect is limited. At the same time, since both S-glass fiber and E-glass fiber are glass fibers and their densities do not change significantly, the weight of the battery cover 1 composed of the substrate layer 10 of different glass fibers is basically the same, and the weight of the battery cover 1 cannot be optimized.

[0063] Figure 4 It is a schematic structural diagram of yet another substrate layer of the battery cover. As Figure 4 shown, in some embodiments, the substrate layer 10 can also be made by mixing and stacking multiple fiber prepregs. Exemplarily, the substrate layer 10 can be provided with five layers of prepregs 11, which may include glass fiber prepreg 11c, ceramic fiber prepreg 11d and aramid fiber prepreg 11e. One layer of glass fiber prepreg 11c is respectively provided on the upper and lower sides of the ceramic fiber prepreg 11d, and one layer of aramid fiber prepreg 11e can be respectively arranged on the sides of the two layers of glass fiber prepregs 11c away from the ceramic fiber prepreg 11d, so as to form the substrate layer 10 with a five-layer structure.

[0064] By using the mixed stacking of aramid fiber and ceramic fiber, the stiffness and toughness of the substrate layer 10 can be improved through the toughness of aramid fiber and the high modulus of ceramic fiber, increasing the impact resistance and puncture resistance effect of the substrate layer 10, and realizing the improvement of the puncture resistance effect of the battery cover 1.

[0065] However, due to the relatively high density of ceramic fibers, the weight of the substrate layer 10 provided with ceramic fibers will increase, affecting the overall weight of the battery cover 1 and being disadvantageous for weight reduction of the battery cover 1. Moreover, although the modulus of ceramic fibers is high, compared with glass fibers, ceramic fibers are relatively brittle and the improvement in puncture resistance is limited.

[0066] Figure 5 It is a schematic structural diagram of another substrate layer of a mobile phone cover. As Figure 5 shown, in some embodiments, due to the relatively high density of glass fibers themselves, in order to reduce weight and thickness, hollow glass microspheres 12 can also be added to the prepreg 11 of the substrate layer 10 to reduce the overall density of the prepreg 11.

[0067] Taking the example that the substrate layer 10 includes five layers of glass fiber prepregs, hollow glass microspheres with a density of about 0.4 g / cm 3 can be added to the glass fiber prepregs except the topmost and bottommost layers, so as to reduce the density of the substrate layer 10 from 1.9 g / cm 3 to about 1.4 g / cm 3 and thus reduce the weight of the battery cover 1.

[0068] It should be understood that in order to add hollow glass microspheres to the substrate layer 10, hollow glass microspheres must be added to the resin used to prepare the prepreg 11 when preparing the prepreg 11. And in order to accommodate the glass microspheres, the resin content in the prepreg 11 needs to be increased. Since the strength of the resin is quite different from that of the fibers, the puncture resistance and other safety performances of the substrate layer 10 itself will decline. At the same time, because the glass microspheres themselves are relatively brittle, adding them will reduce the toughness of the substrate layer 10, and it is easy to cause edge chipping and other situations during the processing, especially during operations such as cutting, reducing the yield rate of the production of the battery cover 1.

[0069] To solve the above problems, the embodiments of the present application provide a multi-layer composite structure, a preparation method, a battery cover and an electronic device, which can not only reduce the thickness and weight of the battery cover itself, but also optimize the puncture resistance of the battery cover, reduce the risk of damage to internal devices of the electronic device in the case of dropping or other scenarios, and improve the application safety of the electronic device.

[0070] Figure 6 It is a schematic diagram of a multi-layer composite structure in the embodiments of the present application. As Figure 6 shown, the embodiments of the present application provide a multi-layer composite structure 100, which includes a plurality of fiber layers 110 stacked, and each fiber layer 110 is formed by curing after impregnating a fiber sheet with a prepolymer solution, and the fiber sheet in at least one fiber layer 110 is made of PBO fibers.

[0071] In the embodiments of the present application, in order to cure the fiber sheet to form the fiber layer 110, the mass ratio of the prepolymer solution in each fiber layer 110 needs to be controlled. Specifically, in order to enable the fiber layer 110 to be formed and capable of operations such as hot pressing, the mass ratio of the prepolymer solution in the fiber layer 110 needs to be greater than or equal to 30%.

[0072] However, since the physical properties such as the structural strength of the cured prepolymer solution have a certain gap compared with the fiber sheet, an excessive amount of the prepolymer solution will cause a decrease in the structural strength of the formed fiber layer 110, which is not conducive to the improvement of the puncture resistance of the multi-layer composite structure 100. Therefore, the mass ratio of the prepolymer solution in the fiber layer 110 needs to be less than or equal to 60%, that is, the mass ratio of the prepolymer solution in the fiber layer 110 needs to be controlled between 30% and 60%, so as to reduce the influence of the prepolymer solution on the strength of the fiber layer 110 on the basis of being able to shape the fiber layer 110 and improve the structural strength of the obtained multi-layer composite structure 100.

[0073] It should be understood that the mass ratio of the prepolymer solution in the fiber layer 110 refers to the mass proportion of the solid structure formed by curing the prepolymer solution in the cured fiber layer 110 in the fiber layer 110.

[0074] At the same time, in order to meet the structural design requirements of thinning and weight reduction, the thickness of each fiber layer 110 is greater than or equal to 0.03 mm and less than or equal to 0.3 mm, so that the fiber layer 110 has a relatively thin thickness on the basis of providing a certain structural strength, thereby facilitating the realization of the structural design of a battery cover with thinning and weight reduction through the multi-layer composite structure 100.

[0075] PBO fibers have a density, strength and modulus close to those of carbon fibers, and have the same toughness as aramid fibers, and at the same time have the material properties of being lightweight and high-strength. Therefore, the fiber layer 110 composed of PBO fibers has the above advantages, can improve the overall structural strength of the multi-layer composite structure 100 while reducing the weight, and further improve the structural strength of the battery cover composed of the multi-layer composite structure 100 and reduce the weight, realizing the thinning and weight reduction of the battery cover.

[0076] It should be noted that the prepolymer solution is mainly used to shape and cure the fiber layer 110, and at the same time facilitate the processing of stacking to form the multi-layer composite structure 100. In some embodiments, the prepolymer solution may include materials such as epoxy monomers, curing agents, accelerators, dispersants, fillers, etc., and the present application does not limit the specific types of materials included in the prepolymer solution.

[0077] Exemplarily, during the actual preparation process of the multi-layer composite structure 100, multiple fiber pre-impregnated materials can be applied for cutting, stacking, and pressing treatments to obtain the multi-layer composite structure 100, wherein at least one fiber pre-impregnated material is a PBO fiber pre-impregnated material. It should be understood that the fiber pre-impregnated material is the fiber layer 110 in the foregoing embodiments.

[0078] Figure 7 It is a schematic diagram of a multi-layer composite structure provided with a first fiber layer in an embodiment of the present application. Figure 8 It is a schematic diagram of another multi-layer composite structure provided with a first fiber layer in an embodiment of the present application.

[0079] In some embodiments of the present application, the extending direction of the fibers in the fiber layer 110 can be unidirectional. As Figure 7 and Figure 8 shown, at least one of the multiple fiber layers 110 is a first fiber layer 110a, and the fiber sheets in each first fiber layer 110a are arranged by PBO fiber bundles 111 with the same extending direction and in a straightened state.

[0080] Exemplarily, as Figure 7 shown, the multi-layer composite structure 100 may include five fiber layers 110, and each fiber layer 110 is a first fiber layer 110a. The extending directions of the PBO fiber bundles 111 in adjacent first fiber layers 110a are different. Due to the different extending directions, the PBO fiber bundles 111 in adjacent first fiber layers 110a form a cross structure, thereby improving the puncture resistance of the multi-layer composite structure 100.

[0081] Therefore, during the preparation process of the multi-layer composite structure 100, multiple PBO fiber pre-impregnated materials need to be used for cutting, stacking, and pressing treatments to obtain the multi-layer composite structure 100 in which each fiber layer 110 is a first fiber layer 110a.

[0082] In some embodiments, the included angle between the extending directions of the PBO fiber bundles 111 in adjacent first fiber layers 110a is a right angle. As Figure 7 shown, taking the extending direction of the PBO fiber bundles 111 in the uppermost first fiber layer 110a as 0°, the extending direction of the PBO fiber bundles 111 in the adjacent first fiber layer 110a can be 90°. The PBO fiber bundles 111 in the five first fiber layers 110a can be arranged in the direction sequence of 0° / 90° / 0° / 90° / 0° to improve the overall strength of the multi-layer composite structure 100.

[0083] As Figure 8As shown, in some embodiments of the present application, the multi-layer composite structure 100 may further include four fiber layers 110, and each fiber layer 110 is a first fiber layer 110a. Among them, the PBO fiber bundles 111 in the topmost and bottommost first fiber layers 110a extend in the first direction, while the PBO fiber bundles 111 in the other first fiber layers 110a in the multi-layer composite structure 100 extend in the second direction, and the first direction is different from the second direction.

[0084] Compared with the multi-layer composite structure 100 in the foregoing embodiment, the multi-layer composite structure 100 in this embodiment reduces one first fiber layer 110a, thereby further thinning and lightening the battery cover formed by the multi-layer composite structure 100. Exemplarily, the included angle between the first direction and the second direction may also be a right angle. Taking the first direction as 0° as an example, the second direction can be 90°. Therefore, the PBO fiber bundles 111 in the four first fiber layers 110a can be arranged in the direction sequence of 0° / 90° / 90° / 0°, thereby improving the overall strength of the multi-layer composite structure 100.

[0085] It should be understood that, such as Figure 7 and Figure 8 the density of the fibers shown in is only an example for facilitating the display of the arrangement mode of the PBO fiber bundles.

[0086] In practical applications, the fiber density of the unidirectional arrangement is relatively high, thereby reducing the mass of the prepolymer solution required to form the first fiber layer 110, and the strength and modulus of the PBO fiber bundles themselves can be better retained. At the same time, the PBO fiber bundles in each first fiber layer 110a are in a straightened state, which can better control the thickness of the first fiber layer 110a, reduce the unevenness on the surface of the first fiber layer 110a, and facilitate the operation of thinning and lightening the battery cover through the multi-layer composite structure 100.

[0087] In some embodiments of the present application, in order to shape the fiber layer 110, the prepolymer solution contains resin. In the first fiber layer 110a, since the PBO fiber bundles 111 in the same first fiber layer 110a are in a straightened state and the fiber density is relatively high, the mass proportion of the prepolymer solution in the first fiber layer 110a is relatively low.

[0088] Exemplarily, in each first fiber layer 110a, the mass proportion of the prepolymer solution ranges from 30% to 45%, thereby reducing the influence of the prepolymer solution on the strength of the first fiber layer 110a, better retaining the strength and modulus of the PBO fiber bundle 111 itself, and improving its puncture resistance. At the same time, the unidirectional and straight PBO fiber bundle 111 can more precisely control the thickness of the first fiber layer 110a formed thereby. Exemplarily, in order to ensure the strength of the multi-layer composite structure 100, the thickness of each first fiber layer 110a can be 0.1 mm.

[0089] It should be noted that both the mass proportion of the prepolymer solution in the first fiber layer 110a and the thickness of the first fiber layer 110a are a feasible implementation manner in this application. The mass proportion of the prepolymer solution in the first fiber layer 110a and the thickness of the first fiber layer 110a can also be other values. This application does not limit the specific values of the mass proportion of the resin and the thickness of the first fiber layer 110a.

[0090] By the way that the PBO fiber bundles 111 extend in the same direction to form the first fiber layer 110a, a first fiber layer 110a with higher single-layer strength and modulus than that of glass fiber can be obtained, thereby improving the puncture resistance of the battery cover formed by the multi-layer composite structure 100. The battery cover obtained in this way can reduce the weight by 1 g to 1.5 g compared with the battery cover made of glass fiber, and at the same time, the puncture resistance can be improved by 100% to 200%.

[0091] Figure 9 It is a schematic diagram of a multi-layer composite structure with a second fiber layer in an embodiment of this application. Figure 10 It is a schematic diagram of another multi-layer composite structure with a second fiber layer in an embodiment of this application.

[0092] In a feasible implementation manner of this application, among the multiple fiber layers 110 of the multi-layer composite structure 100, at least one fiber layer 110 is a second fiber layer 110b. And the fiber sheets in each second fiber layer 110b are formed by weaving PBO fiber bundles 111 with the extending directions being the fifth direction and the sixth direction, and the fifth direction is different from the sixth direction.

[0093] As Figure 9 and Figure 10 shown, each fiber layer 110 in the multi-layer composite structure 100 is a second fiber layer 110b, and the multi-layer composite structure 100 may include four or five second fiber layers 110b. In some embodiments, the included angle between the fifth direction and the sixth direction is a right angle, that is, the PBO fiber bundles 111 in the second fiber layer 110b are vertically arranged.

[0094] The second fiber layer 110b can be directly stacked to form the multi-layer composite structure 100, or can be cross-stacked to improve the overall strength of the multi-layer composite structure 100. Specifically, as Figure 10 shown, the multi-layer composite structure 100 includes four second fiber layers 110b. In the second fiber layer 110b, the PBO fiber bundles 111 in the fifth direction are warp fibers, and the PBO fiber bundles 111 in the sixth direction are weft fibers. Taking the direction of the warp fibers in the uppermost second fiber layer 110b as 0°, the warp fibers in the four second fiber layers 110b from top to bottom can be arranged in the order of 0° / 45° / 90° / 135°, so as to form an intersecting grid structure, thereby improving the overall strength of the multi-layer composite structure 100.

[0095] It should be noted that Figure 9 and Figure 10 The weaving method of the PBO fiber bundles 111 shown in is only an example in this application. In actual application, the weaving density of the PBO fiber bundles 111 is higher, and the gap between the PBO fiber bundles 111 is smaller. The second fiber layer 110b formed by weaving has the effect of not being prone to yarn dispersion. However, since the weaving process will cause the intersecting PBO fiber bundles 111 to bend, the fiber sheet formed by weaving has a certain degree of unevenness. Therefore, during the filling and curing process of the prepolymer solution, the weight of the prepolymer solution will increase to a certain extent, and the thickness of the second fiber layer 110b will be limited by the thickness of at least two intersecting PBO fiber bundles 111. Compared with the first fiber layer 110a, the thickness and weight reduction of the multi-layer composite structure 100 constructed by the second fiber layer 110b are limited.

[0096] In some embodiments, the prepolymer solution used to form the second fiber layer 110b also contains resin. Due to the characteristics of the woven fibers, the mass ratio of the prepolymer solution in the second fiber layer 110b is higher than that in the first fiber layer 110a. Exemplarily, the mass ratio of the prepolymer solution in each second fiber layer 110b is 45% - 55%, and the thickness range of each second fiber layer 110b is 0.1mm - 0.2mm.

[0097] By the method of weaving the PBO fiber bundles 111 to form the second fiber layer 110b, a second fiber layer 110b with higher single-layer strength and modulus can be obtained compared with glass fiber, thereby improving the anti-puncture performance of the battery cover composed of the multi-layer composite structure 100. The battery cover obtained in this way can reduce the weight by 0.5g - 1g compared with the battery cover composed of glass fiber, and at the same time, the anti-puncture performance can be improved by 50% - 80%.

[0098] Figure 11 It is a schematic diagram of a multi-layer composite structure with multiple fiber layers in an embodiment of this application. Figure 12This is a schematic diagram of another multi-layer composite structure with multiple fiber layers in the embodiments of the present application. Since the cost of PBO fibers is relatively high, and the binding property between PBO fibers and the resin in the prepolymer solution is poorer than that of fibers such as glass fibers, in some embodiments, in order to improve the strength of the multi-layer composite structure 100 and reduce its weight to achieve weight reduction and thinning, as Figure 11 shown, a third fiber layer 110c can be provided in the multi-layer composite structure 100.

[0099] Specifically, among the multiple fiber layers 110 in the multi-layer composite structure 100, except for at least one first fiber layer 110a, the other fiber layers 110 are all third fiber layers 110c. The fiber sheet in the third fiber layer 110c is arranged by first fiber filaments 111a with the same extension direction and in a straightened state. The first fiber filament 111a can be any one of glass fiber, aramid fiber, ceramic fiber, and carbon fiber.

[0100] In the multi-layer composite structure 100, multiple third fiber layers 110c can be stacked, and at least one first fiber layer 110a can be provided between adjacent third fiber layers 110c. As Figure 11 shown, the multi-layer composite structure 100 includes five fiber layers 110, among which there is one first fiber layer 110a and four third fiber layers 110c. At this time, the four third fiber layers 110c can be stacked, and the first fiber layer 110a can be provided at the middle position of the multi-layer composite structure 100, that is, there are two third fiber layers 110c above and below the first fiber layer 110a.

[0101] It should be noted that the fiber types applied in different third fiber layers 110c can be the same or different. As Figure 11 shown, the first fiber layer 110a is provided at the middle position of the multi-layer composite structure 100. The first fiber filaments 111a in the two third fiber layers 110c on the upper and lower sides of the first fiber layer 110a can be aramid fibers, and the first fiber filaments 111a in the two third fiber layers 110c on the outermost upper and lower layers of the multi-layer composite structure 100 can be glass fibers or carbon fibers.

[0102] It should be understood that the material of the first fiber filaments 111a in the foregoing third fiber layer 110c and the arrangement of the third fiber layer 110c are only a feasible implementation manner. The present application may also include third fiber layers 110c with other materials and arrangement manners. Therefore, the material of the first fiber filaments 111a and the stacking and arrangement manner of the fiber layers 110c are not limited in the present application.

[0103] In some embodiments, in order to improve the puncture resistance of the multi-layer composite structure 100, the PBO fiber bundles 111 in the first fiber layer 110a may extend in a third direction, and the first fiber bundles 111a in the third fiber layer 110c adjacent to the first fiber layer 110a may extend in a fourth direction. The third direction is different from the fourth direction, and the extension directions of the first fiber bundles 111a in the adjacent third fiber layers 110c are different. Exemplarily, the included angle between the third direction and the fourth direction may be a right angle.

[0104] In this way, the fibers in different fiber layers 110 can be arranged in a cross pattern, thereby reducing the voids in the multi-layer composite structure 100 and improving the strength of the multi-layer composite structure 100.

[0105] It should be understood that in the process of constructing the multi-layer composite structure 100 using multiple fibers, the strength of the multi-layer composite structure 100 can also be improved by weaving the fibers. As Figure 12 shown, the fiber layers 110 in the multi-layer composite structure 100 may include at least one second fiber layer 110b and multiple fourth fiber layers 110d.

[0106] Exemplarily, among the multiple fiber layers 110 in the multi-layer composite structure 100, except for at least one second fiber layer 110b, the other fiber layers 110 are all fourth fiber layers 110d. The fiber sheets in the fourth fiber layer 110d are formed by weaving second fiber bundles 111b with extension directions in a fifth direction and a sixth direction. The second fiber bundles 111b can be any one of glass fibers, aramid fibers, ceramic fibers, and carbon fibers.

[0107] In the multi-layer composite structure 100, multiple fourth fiber layers 110d can be stacked, and at least one second fiber layer 110b can be disposed between adjacent fourth fiber layers 110d. As Figure 12 shown, the multi-layer composite structure 100 includes four fiber layers 110, among which there is one second fiber layer 110b and three fourth fiber layers 110d. At this time, the three fourth fiber layers 110d can be stacked, and the second fiber layer 110b can be disposed between two adjacent fourth fiber layers 110d, that is, there is one fourth fiber layer 110d on one side of the second fiber layer 110b and two fourth fiber layers 110d on the other side.

[0108] It should be understood that the fiber types applied in different fourth fiber layers 110d can be the same or different. Exemplarily, as Figure 12 shown, the second fiber bundles 111b in the three fourth fiber layers 110d can be glass fiber, aramid fiber, and carbon fiber respectively, or can be glass fiber, aramid fiber, and ceramic fiber, etc. In this application, there is no limitation on the type of the second fiber bundles 111b in the fourth fiber layer 110d.

[0109] Figure 13 This is a schematic diagram of the preparation process of a multi-layer composite structure in an embodiment of the present application.

[0110] On the basis of providing a multi-layer composite structure 100, the present application also provides a method for preparing a multi-layer composite structure.

[0111] As Figure 13 shown, the preparation method includes:

[0112] S100: Place epoxy resin monomer, curing agent, accelerator, dispersant, and filler in the prepreg and stir well and perform pre-curing to form a prepolymer solution.

[0113] Among them, the epoxy resin monomer can be bisphenol A epoxy resin, the curing agent can be an amine curing agent, the accelerator can be a polyamide resin accelerator, the dispersant can be a surfactant-based dispersant, and the filler can be talc powder. After the above reaction solution is stirred well and pre-cured, a prepolymer solution can be formed.

[0114] Exemplarily, the epoxy resin monomer can adopt an epoxy resin monomer with the brand number 618, and the heating temperature during the pre-curing process can be 70 °C. It should be understood that the types of the above epoxy resin monomers and the pre-curing temperature are only one feasible implementation manner, and other types of epoxy resin monomers and pre-curing temperatures can also be adopted in the present application to achieve the above effects.

[0115] S200: Immerse the fiber sheet in the prepolymer solution and perform curing treatment to obtain a fiber layer.

[0116] After obtaining the prepolymer solution, the fiber sheet can be immersed in the prepolymer solution for curing treatment to obtain a fiber layer. It should be noted that in the actual production process, after the fiber sheet is immersed in the prepolymer solution and cured, the obtained product is a fiber prepreg, and the fiber prepreg is an intermediate product for making a fiber composite structure. For example, by immersing a PBO fiber sheet in the prepolymer solution and performing curing treatment, a PBO fiber prepreg can be obtained. In the embodiment of the present application, one fiber layer 110 can be considered as one fiber prepreg, and the operations performed on multiple fiber layers 110 in the subsequent steps can be considered as operations on multiple fiber prepregs.

[0117] From the above embodiments of the multi-layer composite structure 100, it can be seen that the fiber sheet in the fiber layer 110 can be a fiber sheet with fibers arranged unidirectionally, or a woven fiber sheet formed by weaving fibers. Therefore, the preparation process of the fiber layer 110 can include preparation by using a fiber sheet with fibers arranged unidirectionally, and preparation by using a woven fiber sheet.

[0118] Exemplarily, to prepare the fiber layer 110 with unidirectional arrangement of fibers in the fiber sheet, the fiber bobbin yarn can be first placed and the fiber filaments can be arranged unidirectionally by yarn laying to form multiple fiber sheets, where at least one of the fiber filaments in the fiber sheets is a PBO fiber filament. It should be understood that in the fiber layer 110 in the embodiments of the present application, the types of fiber filaments used are single, that is, in each fiber layer 110, there is one and only one type of fiber filament forming the fiber sheet.

[0119] The multiple obtained fiber sheets are respectively impregnated in the prepolymer solution. At the same time, in order to reduce the influence of the prepolymer solution on the strength of the formed fiber layer 110 and the thickness of the subsequent formed multi-layer composite structure, it is necessary to control the mass ratio of the prepolymer solution in the multiple impregnated fiber sheets and the thickness of the multiple impregnated fiber sheets, so as to realize the control of the preparation product.

[0120] After the impregnation is completed, since the prepolymer solution has a large fluidity, it is also necessary to perform a curing treatment on the multiple impregnated fiber sheets respectively to obtain multiple fiber layers.

[0121] And to prepare the fiber layer 110 by weaving the fiber sheet, multiple woven fiber sheets can be made by weaving the fiber filaments, where at least one of the fiber filaments in the woven fiber sheets is a PBO fiber filament.

[0122] The multiple obtained woven fiber sheets are respectively impregnated in the prepolymer solution, and the mass ratio of the prepolymer solution in the multiple impregnated woven fiber sheets and the thickness of the multiple impregnated woven fiber sheets are controlled. Finally, the multiple impregnated woven fiber sheets are respectively subjected to a curing treatment to obtain multiple fiber layers.

[0123] Specifically, the curing treatment of the multiple impregnated fiber sheets can be realized by heating in an oven, and the curing temperature can be 100°C to 120°C.

[0124] It should be understood that compared with the fiber sheet with unidirectional arrangement of fibers, the fiber filaments in the woven fiber sheet have a certain bend, and due to the voids formed by the weaving structure, the mass ratio of the prepolymer solution in the impregnated woven fiber sheet and the thickness of the impregnated woven fiber sheet are larger than those of the fiber sheet with unidirectional arrangement of fibers.

[0125] In the embodiments of the present application, the grammage range of the fiber sheets in the fiber layer 110 can be within 30 g / m 2 ~140 g / m 2 . It should be understood that the arrangement mode of the fiber filaments affects the grammage of the fiber layer 110. Among them, the grammage range of the fiber sheet with unidirectional arrangement of fiber filaments can be within 30 g / m 2 ~140 g / m 2 , while the grammage range of the woven fiber sheet can be within 50 g / m 2~140 g / m 2 。Exemplarily, taking the fiber sheet composed of PBO fiber tows as an example, the fiber sheet with a grammage of 50 g / m 2 or the woven fiber sheet with a grammage of 60 g / m 2 can be preferably used to prepare the fiber layer 110.

[0126] Meanwhile, in order to facilitate the formation of the fiber layer 110 and reduce the influence of the prepolymer solution on the strength of the fiber layer 110, the mass ratio of the prepolymer solution in the fiber layer 110 is 30% - 60%, and the thickness of the fiber layer 110 is 0.03 mm - 0.3 mm. Preferably, in the fiber layer 110 prepared from the fiber sheet with unidirectional fiber arrangement, the mass ratio of the prepolymer solution in each fiber layer 110 is 30% - 45%, and the thickness of each fiber layer 110 is 0.04 mm - 0.2 mm. While in the fiber layer 110 prepared from the woven fiber sheet, the mass ratio of the prepolymer solution in each fiber layer 110 is 45% - 55%, and the thickness of each fiber layer 110 is 0.1 mm - 0.2 mm. It should be noted that the specific thickness of the fiber layer 110 can be adjusted as needed.

[0127] S300: Cut, stack, and press multiple fiber layers to obtain a multi-layer composite structure.

[0128] Among them, the fiber sheet in at least one fiber layer is made of PBO fiber. Since the multi-layer composite structure 100 obtained by processing multiple fiber layers 110 is a composite material, in practical applications, in order to facilitate subsequent operations, during the preparation of the multi-layer composite structure 100, it is necessary to control the size of the formed multi-layer composite structure 100. For example, taking the preparation of a mobile phone cover through the multi-layer composite structure 100 as an example, that is, a multi-layer composite structure 100 in a rectangular shape with both length and width slightly larger than the mobile phone is required. Therefore, the shape and size of the multi-layer composite structure 100 are related to the preset preparation target. Therefore, when preparing the multi-layer composite structure 100, it is necessary to cut the multiple fiber layers 110 respectively to obtain fiber layers of a preset size, where the preset size is related to the structure to be prepared by the multi-layer composite structure 100.

[0129] Then, the multiple cut fiber layers 110 are stacked, wherein the extending directions of the fiber bundles in adjacent fiber layers 110 are different. Further, the included angle between the extending directions of the fiber bundles in adjacent fiber layers 110 can be a right angle. Alternatively, the fiber bundles in the topmost and bottommost fiber layers 110 extend in a first direction, and the fiber bundles in the other fiber layers except the topmost and bottommost fiber layers extend in a second direction, and the first direction is different from the second direction. If the first direction is 0°, the second direction can be any value such as 45°, 60°, 90°, or other angles. In some embodiments, in order to achieve a regular arrangement and improve the overall strength of the formed multi-layer composite structure 100, based on the first direction being 0°, the second direction can be 90°. Finally, the multiple stacked fiber layers 110 can be pressed to obtain the multi-layer composite structure 100.

[0130] In some embodiments, if the fiber sheet in the fiber layer 110 is a woven fiber sheet, then in the process of preparing the multi-layer composite structure 100, first, the multiple fiber layers 110 can be cut respectively to obtain multiple fiber layers 110 of a preset size, then the multiple cut fiber layers 110 are stacked, and finally the multiple stacked fiber layers 110 are pressed to obtain the multi-layer composite structure 100. The stacking manner of the multiple fiber layers 110 can be Figure 10 as shown in, which will not be elaborated in this application.

[0131] Among them, the cutting method can adopt laser cutting. The pressing process can include hot pressing, and the temperature range of the hot pressing is 100°C to 200°C, the hot pressing time is 10 min to 30 min, and the hot pressing pressure is 0.2 MPa to 0.7 MPa.

[0132] Figure 14 is a schematic structural diagram of a battery cover in an embodiment of this application.

[0133] Based on providing a multi-layer composite structure 100 and a preparation method thereof, an embodiment of this application also provides a battery cover 210. As Figure 14 shown, the battery cover 210 includes a substrate layer 211 and a decorative layer 212. The substrate layer 211 includes the multi-layer composite structure 100 in any of the foregoing embodiments, and the decorative layer 212 is disposed on one side of the substrate layer 211. The decorative layer 212 can be glass, ceramic, resin, or other materials with decorative functions, and the material of the decorative layer 212 is not limited in this application.

[0134] In some embodiments, to meet the device installation requirements on some electronic devices, through holes 213 are provided on the substrate layer 211 and the decorative layer 212. The battery cover 210 further includes a camera lens 214. The shape of the camera lens 214 matches the shape of the through hole 213, and the camera lens 214 covers the through hole 213. To implement the shooting function of the electronic device, the material of the camera lens 214 can be glass or other transparent materials, and this application does not limit this.

[0135] It should be understood that the camera lens 214 is disposed on the side of the battery cover 210 where the decorative layer 212 is provided, thereby providing certain protection for the devices inside the electronic device.

[0136] The preparation process of the battery cover 210 will be described below through several embodiments.

[0137] Embodiment 1

[0138] (1) Since the substrate layer 211 is the multi-layer composite structure 100 in any of the foregoing embodiments, the preparation process of the substrate layer 211 is the same as that of the foregoing multi-layer composite structure 100. Exemplarily, the preparation of the substrate layer 211 may include:

[0139] Put the epoxy resin monomer of grade 618, amine curing agent, polyamide resin accelerator, surfactant dispersant, and talcum powder into the prepreg, stir well and heat to 70 °C, and then perform pre-curing to form a prepolymer solution; wherein, the ratio of the epoxy resin monomer, amine curing agent, polyamide resin accelerator, surfactant dispersant, and talcum powder is 100:10:20:10:18;

[0140] Place the PBO fiber bobbin in position, and change the fiber filament bundle into a unidirectional PBO fiber sheet with uniform thickness and width through yarn laying;

[0141] Immerse the unidirectional PBO fiber sheet in the prepolymer solution through a prepreg line body, and then control the mass ratio of the prepolymer solution in the unidirectional PBO fiber sheet to be 40% through a hot roller, and control the thickness of the impregnated unidirectional PBO fiber sheet to be 0.05 mm to obtain a unidirectional PBO fiber sheet impregnated with the prepolymer solution;

[0142] Put the unidirectional PBO fiber sheet impregnated with the prepolymer solution into an oven and cure it at 100 °C to 120 °C to obtain a unidirectional PBO fiber prepreg;

[0143] Use laser cutting to obtain a unidirectional PBO fiber prepreg sheet from the unidirectional PBO fiber prepreg, and the cutting directions are along the fiber direction and perpendicular to the fiber direction of the unidirectional PBO fiber prepreg, that is, 0° and 90°;

[0144] According to the design of the 0.4 mm battery cover base material layer, the unidirectional PBO fiber prepreg sheets are stacked in 4 layers in the order of 0° / 90° / 90° / 0° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min, and the pressure is 0.5 Mpa. After cooling, a PBO fiber composite board with a non-shaped edge is obtained as the base material layer 211.

[0145] (2) Preparation of the overall battery cover 210

[0146] The surface of the obtained base material layer 211 is subjected to appearance treatment to install the decorative layer 212 on the surface of the base material layer 211. The methods of installing the decorative layer 212 include spraying, stamping, or externally pasting PU leather, etc. Subsequently, the outer shape of the base material layer 211 is processed by laser cutting, the non-shaped surface is removed, and through holes 213 are made according to the design of the camera lens 214 to obtain the main structure of the battery cover 210.

[0147] The main structure of the obtained battery cover 210 is subjected to auxiliary material lamination and the camera lens 214 is assembled to finally obtain the battery cover 210.

[0148] The battery cover 210 prepared by this embodiment reduces the weight of the whole machine by 1.5 g and improves the anti-puncture effect by 100% compared with the 0.4 mm pure woven E-class glass fiber battery cover.

[0149] Example 2

[0150] Example 2 provides a battery cover 210. The difference between Example 2 and Example 1 lies in the different mass ratios of the prepolymer solution in the unidirectional PBO fiber sheet, the different thicknesses of the unidirectional PBO fiber sheet after impregnation, the different arrangement directions and the different number of layers of the unidirectional PBO fiber prepreg sheets. In this embodiment, the mass ratio of the prepolymer solution in the unidirectional PBO fiber sheet is 45%, the thickness of the unidirectional PBO fiber sheet after impregnation is controlled to be 0.1 mm, and the unidirectional PBO fiber prepreg sheets are stacked in 5 layers in the order of 0° / 90° / 0° / 90° / 0°.

[0151] The battery cover 210 prepared by this embodiment reduces the weight of the whole machine by 1 g and improves the anti-puncture effect by 200% compared with the 0.4 mm pure woven E-class glass fiber battery cover.

[0152] Example 3

[0153] Example 3 provides a battery cover 210. The difference between Example 3 and Example 1 is that according to the design of a 0.4 mm battery cover substrate, unidirectional PBO fiber prepreg sheets and other unidirectional fiber prepreg sheets are stacked, with one or more middle layers being unidirectional PBO fiber prepreg sheets. In this example, unidirectional glass fiber prepreg sheets, unidirectional aramid fiber prepreg sheets, unidirectional PBO fiber prepreg sheets, and unidirectional ceramic fiber prepreg sheets are stacked in 4 layers at 0° / 90° / 90° / 0° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min and the pressure is 0.5 Mpa. After cooling, a composite laminated sheet with a non-shaped edge is obtained as the substrate layer 211.

[0154] For the battery cover 210 produced in this example, compared with a 0.4 mm pure woven E-class glass fiber battery cover, the weight of the whole machine is reduced by 0.5 g, and the anti-puncture effect is improved by 120%.

[0155] Example 4

[0156] Example 4 provides a battery cover 210. The difference between Example 4 and Example 1 is that according to the design of a 0.4 mm battery cover substrate, unidirectional PBO fiber prepreg sheets and other unidirectional fiber prepreg sheets are stacked, with one or more middle layers being unidirectional PBO fiber prepreg sheets. In this example, unidirectional glass fiber prepreg sheets, unidirectional PBO fiber prepreg sheets, unidirectional PBO fiber prepreg sheets, and unidirectional carbon fiber prepreg sheets are stacked in 4 layers at 0° / 90° / 90° / 0° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min and the pressure is 0.5 Mpa. After cooling, a composite laminated sheet with a non-shaped edge is obtained as the substrate layer 211.

[0157] For the battery cover 210 produced in this example, compared with a 0.4 mm pure woven E-class glass fiber battery cover, the weight of the whole machine is reduced by 1 g, and the anti-puncture effect is improved by 80%.

[0158] Example 5

[0159] Example 5 provides a battery cover 210. The difference between Example 5 and Example 2 is that according to the design of a 0.4 mm battery cover substrate, unidirectional PBO fiber prepreg sheets and other unidirectional fiber prepreg sheets are stacked, with one or more middle layers being unidirectional PBO fiber prepreg sheets. In this example, unidirectional aramid fiber prepreg sheets, unidirectional glass fiber prepreg sheets, unidirectional PBO fiber prepreg sheets, unidirectional carbon fiber prepreg sheets, and unidirectional ceramic fiber prepreg sheets are stacked in 5 layers at 0° / 90° / 0° / 90° / 0° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min and the pressure is 0.5 Mpa. After cooling, a composite laminated sheet with a non-shaped edge is obtained as the substrate layer 211.

[0160] The battery cover 210 produced through this embodiment reduces the weight of the whole machine by 0.6 g compared with a 0.4 mm pure woven E-class glass fiber battery cover, and improves the anti-puncture effect by 100%.

[0161] Example 6

[0162] Example 6 provides a battery cover 210. The difference between Example 6 and Example 2 is that according to the design of a 0.4 mm battery cover substrate, unidirectional PBO fiber prepreg sheets and other unidirectional fiber prepreg sheets are stacked, with one or more middle layers being unidirectional PBO fiber prepreg sheets. In this embodiment, unidirectional aramid fiber prepreg sheets, unidirectional PBO fiber prepreg sheets, unidirectional PBO fiber prepreg sheets, unidirectional PBO fiber prepreg sheets, and unidirectional ceramic fiber prepreg sheets are stacked in 5 layers at 0° / 90° / 0° / 90° / 0° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min, and the pressure is 0.5 Mpa. After cooling, a composite laminated sheet containing a non-shaped edge is obtained as the substrate layer 211.

[0163] The battery cover 210 produced through this embodiment reduces the weight of the whole machine by 0.8 g compared with a 0.4 mm pure woven E-class glass fiber battery cover, and improves the anti-puncture effect by 120%.

[0164] Example 7

[0165] (1) Preparation of the substrate layer 211

[0166] Epoxy resin monomer of grade 618, amine curing agent, polyamide resin accelerator, surfactant dispersant, and talcum powder are placed in the prepreg, stirred thoroughly and heated to 70 °C, and then pre-cured to form a prepolymer solution; among them, the ratio of epoxy resin monomer, amine curing agent, polyamide resin accelerator, surfactant dispersant, and talcum powder is 100:10:20:10:18;

[0167] The woven PBO fiber sheet is impregnated with the prepolymer solution through a prepreg line body, and then the mass ratio of the prepolymer solution in the woven PBO fiber sheet is controlled to be 50% through a hot roller, and the thickness of the woven PBO fiber sheet after impregnation is controlled to be 0.1 mm to obtain a woven PBO fiber sheet impregnated with the prepolymer solution;

[0168] The woven PBO fiber sheet impregnated with the prepolymer solution is put into an oven and cured at 100 - 120 °C to obtain a woven PBO fiber prepreg;

[0169] The woven PBO fiber prepreg is laser cut to obtain woven PBO fiber prepreg sheets, and the laser cutting directions are 0°, 45°, 90°, and 135° along the warp direction;

[0170] According to the design of the 0.4 mm battery cover substrate, the woven PBO fiber prepreg sheets are stacked in 4 layers at 0° / 45° / 90° / 135° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min, and the pressure is 0.5 Mpa. After cooling, a PBO fiber composite sheet containing a non-shaped edge is obtained as the substrate layer 211.

[0171] (2) Preparation of the overall battery cover 210

[0172] The surface of the obtained substrate layer 211 is subjected to appearance treatment to install the decorative layer 212 on the surface of the substrate layer 211. The methods of installing the decorative layer 212 include spraying, stamping, or externally pasting PU leather, etc. Subsequently, the substrate layer 211 is subjected to laser cutting for contour processing to remove the non-shaped surface and make through holes 213 according to the design of the camera lens 214, obtaining the main structure of the battery cover 210.

[0173] The main structure of the obtained battery cover 210 is subjected to auxiliary material bonding and assembly of the camera lens 214, and finally the battery cover 210 is obtained.

[0174] The battery cover 210 prepared by this embodiment reduces the weight of the whole machine by 1 g and improves the anti-puncture effect by 50% compared with the 0.4 mm pure woven E-class glass fiber battery cover.

[0175] Example 8

[0176] Example 8 provides a battery cover 210. The difference between Example 8 and Example 7 lies in the different mass ratios of the prepolymer solution in the woven PBO fiber sheet and the thickness of the woven PBO fiber sheet after impregnation, as well as the different stacking arrangement directions and numbers of layers of the woven PBO fiber prepreg sheets. In this embodiment, the mass ratio of the prepolymer solution in the woven PBO fiber sheet is 55%, the thickness of the woven PBO fiber sheet after impregnation is controlled to be 0.2 mm, and the woven PBO fiber prepreg sheets are stacked in 5 layers at 0° / 45° / 90° / 135° / 0°.

[0177] The battery cover 210 prepared by this embodiment reduces the weight of the whole machine by 0.5 g and improves the anti-puncture effect by 80% compared with the 0.4 mm pure woven E-class glass fiber battery cover.

[0178] Example 9

[0179] Example 9 provides a battery cover 210. The difference between Example 9 and Example 7 is that according to the design of a 0.4 mm battery cover substrate, the woven PBO fiber prepreg sheet and other woven fiber prepreg sheets are stacked, with one or more middle layers being woven PBO fiber prepreg sheets. In this example, the woven aramid fiber prepreg sheet, woven PBO fiber prepreg sheet, woven ceramic fiber prepreg sheet, and woven carbon fiber prepreg sheet are stacked in 4 layers at 0° / 45° / 90° / 135° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min, and the pressure is 0.5 Mpa. After cooling, a composite laminate sheet with a non-shaped edge is obtained as the substrate layer 211.

[0180] The battery cover 210 produced by this example reduces the weight of the whole machine by 0.8 g and improves the anti-puncture effect by 100% compared with a 0.4 mm pure woven E-class glass fiber battery cover.

[0181] Example 10

[0182] Example 10 provides a battery cover 210. The difference between Example 10 and Example 7 is that according to the design of a 0.4 mm battery cover substrate, the woven PBO fiber prepreg sheet and other woven fiber prepreg sheets are stacked, with one or more middle layers being woven PBO fiber prepreg sheets. In this example, the woven aramid fiber prepreg sheet, woven PBO fiber prepreg sheet, woven PBO fiber prepreg sheet, and woven ceramic fiber prepreg sheet are stacked in 4 layers at 0° / 45° / 90° / 135° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min, and the pressure is 0.5 Mpa. After cooling, a composite laminate sheet with a non-shaped edge is obtained as the substrate layer 211.

[0183] The battery cover 210 produced by this example reduces the weight of the whole machine by 0.8 g and improves the anti-puncture effect by 100% compared with a 0.4 mm pure woven E-class glass fiber battery cover.

[0184] Example 11

[0185] Example 11 provides a battery cover 210. The difference between Example 10 and Example 8 is that according to the design of a 0.4 mm battery cover substrate, the woven PBO fiber prepreg sheet and other woven fiber prepreg sheets are stacked, with one or more middle layers being woven PBO fiber prepreg sheets. In this example, the woven carbon fiber prepreg sheet, woven ceramic fiber prepreg sheet, woven PBO fiber prepreg sheet, woven aramid fiber prepreg sheet, and woven glass fiber prepreg sheet are stacked in 5 layers at 0° / 45° / 90° / 135° / 0° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min, and the pressure is 0.5 Mpa. After cooling, a composite laminated sheet with a non-shaped edge is obtained as the substrate layer 211.

[0186] The battery cover 210 produced by this example reduces the weight of the whole machine by 0.5 g and improves the anti-puncture effect by 120% compared with a 0.4 mm pure woven E-class glass fiber battery cover.

[0187] Example 12

[0188] Example 12 provides a battery cover 210. The difference between Example 12 and Example 8 is that according to the design of a 0.4 mm battery cover substrate, the woven PBO fiber prepreg sheet and other woven fiber prepreg sheets are stacked, with one or more middle layers being woven PBO fiber prepreg sheets. In this example, the woven ceramic fiber prepreg sheet, woven PBO fiber prepreg sheet, woven PBO fiber prepreg sheet, woven PBO fiber prepreg sheet, and woven aramid fiber prepreg sheet are stacked in 5 layers at 0° / 45° / 90° / 135° / 0° and hot-pressed. The hot-pressing parameters are 150 °C / 20 min, and the pressure is 0.5 Mpa. After cooling, a composite laminated sheet with a non-shaped edge is obtained as the substrate layer.

[0189] The battery cover 210 produced by this example reduces the weight of the whole machine by 0.5 g and improves the anti-puncture effect by 120% compared with a 0.4 mm pure woven E-class glass fiber battery cover.

[0190] Figure 15 It is a schematic structural diagram of an electronic device in an embodiment of the present application.

[0191] On the basis of providing a multi-layer composite structure 100 and a battery cover 210, an embodiment of the present application also provides an electronic device 200. As Figure 15As shown, the electronic device 200 may include a front panel 220, a middle frame 230, a battery 240, and a battery cover 210. Among them, the middle frame 230 is disposed on one side of the front panel 220, and a battery slot 231 is provided in the middle frame 230. After the installation of the electronic device 200 is completed, the battery 240 is located in the battery slot 231. The battery cover 210 is disposed on the side of the middle frame 230 away from the front panel 220, and the battery cover 210 can be used to protect the battery 240 disposed in the battery slot 231.

[0192] In the embodiment of the present application, the chamber formed by enclosing the front panel 220, the middle frame 230, and the battery cover 210 further includes electronic components. The electronic components include, but are not limited to, devices such as a processor, an antenna, a sensor, a gyroscope, a speaker, etc., so that the electronic device 200 can operate normally.

[0193] It should be noted that those skilled in the art will readily think of other implementation manners of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present application. These variations, uses, or adaptations follow the general principles of the present application and include the common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and the embodiments are only regarded as exemplary, and the true scope of the present application is pointed out by the following claims.

[0194] It should be understood that the present application is not limited to the exact structure already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

Claims

1. A multi-layer composite structure, characterized in that, Comprising: A plurality of fiber layers arranged in a stack, each of the fiber layers being formed by curing a fiber sheet impregnated with a prepolymer solution; Wherein, the fiber sheet in at least one of the fiber layers is made of poly(p-phenylene benzobisoxazole) PBO fiber.

2. The multi-layer composite structure according to claim 1, wherein At least one of the plurality of fiber layers is a first fiber layer; The fiber sheet in each of the first fiber layers is arranged by PBO fiber filaments having the same extension direction and in a straightened state.

3. The multi-layer composite structure according to claim 2, wherein Each of the plurality of fiber layers is the first fiber layer; The extension directions of the PBO fiber filaments in adjacent first fiber layers are different.

4. The multi-layer composite structure according to claim 3, wherein The included angle between the extension directions of the PBO fiber filaments in adjacent first fiber layers is a right angle.

5. The multi-layer composite structure according to claim 2, wherein Each of the plurality of fiber layers is the first fiber layer; The PBO fiber filaments in the topmost and bottommost first fiber layers of the multi-layer composite structure extend in a first direction; The PBO fiber filaments in the other first fiber layers of the multi-layer composite structure extend in a second direction; The first direction is different from the second direction.

6. The multi-layer composite structure according to claim 5, wherein The included angle between the first direction and the second direction is a right angle.

7. The multi-layer composite structure according to any one of claims 2 to 6, wherein The mass ratio of the prepolymer solution in each of the first fiber layers is 30% to 45%; The thickness of each of the first fiber layers is 0.04 mm to 0.2 mm.

8. The multi-layer composite structure according to claim 2, wherein The other fiber layers in the plurality of fiber layers except the first fiber layer are third fiber layers; The fiber sheet in the third fiber layer is arranged by first fiber filaments having the same extension direction and in a straightened state, and the first fiber filaments are any one of glass fiber, aramid fiber, ceramic fiber and carbon fiber; A plurality of the third fiber layers are arranged in a stack, and at least one of the first fiber layers is arranged between adjacent third fiber layers.

9. The multi-layer composite structure according to claim 8, wherein The PBO fiber filaments in the first fiber layer extend in a third direction; The first fiber filaments in the third fiber layer adjacent to the first fiber layer extend in a fourth direction; The extension directions of the first fiber filaments in adjacent third fiber layers are different; The third direction is different from the fourth direction.

10. The multi-layer composite structure according to claim 9, wherein The included angle between the third direction and the fourth direction is a right angle.

11. The multi-layer composite structure according to claim 1, wherein At least one of the plurality of fiber layers is a second fiber layer; Each fiber sheet in each of the second fiber layers is formed by weaving PBO fiber bundles whose extending directions are the fifth direction and the sixth direction, and the fifth direction is different from the sixth direction.

12. The multi-layer composite structure according to claim 11, wherein each of the fiber layers in the plurality of fiber layers is the second fiber layer; the included angle between the fifth direction and the sixth direction is a right angle.

13. The multi-layer composite structure according to claim 11 or 12, wherein the mass proportion of the prepolymer solution in each of the second fiber layers is 45% - 55%; the thickness of each of the second fiber layers is 0.1 mm - 0.2 mm.

14. The multi-layer composite structure according to claim 11, wherein the other fiber layers in the plurality of fiber layers except the second fiber layer are fourth fiber layers; each fiber sheet in the fourth fiber layer is formed by weaving second fiber bundles whose extending directions are the fifth direction and the sixth direction, and the second fiber bundles are any one of glass fiber, aramid fiber, ceramic fiber, and carbon fiber; a plurality of the fourth fiber layers are stacked, and at least one of the second fiber layers is arranged between adjacent fourth fiber layers.

15. The multi-layer composite structure according to any one of claims 1 - 14, wherein the mass proportion of the prepolymer solution in each of the fiber layers is 30% - 60%; the thickness of each of the fiber layers is greater than or equal to 0.03 mm and less than or equal to 0.3 mm.

16. A method for preparing a multi-layer composite structure, characterized in that, Comprising: placing an epoxy resin monomer, a curing agent, an accelerator, a dispersant, and a filler in a prepreg and fully stirring and pre-curing to form a prepolymer solution; immersing a fiber sheet in the prepolymer solution and performing a curing treatment to obtain a fiber layer; performing cutting, stacking, and pressing treatments on a plurality of the fiber layers to obtain a multi-layer composite structure; wherein, the fiber sheet in at least one of the fiber layers is made of PBO fiber.

17. The method for preparing a multi-layer composite structure according to claim 16, wherein the immersing a fiber sheet in the prepolymer solution and performing a curing treatment to obtain a fiber layer comprises: positioning a fiber bobbin, and unidirectionally arranging fiber bundles through yarn laying to make a plurality of fiber sheets; at least one of the fiber bundles in the fiber sheets is a PBO fiber bundle; immersing the plurality of fiber sheets in the prepolymer solution respectively; controlling the mass proportion of the prepolymer solution in the plurality of impregnated fiber sheets and the thickness of the plurality of impregnated fiber sheets; performing a curing treatment on the plurality of impregnated fiber sheets respectively to obtain a plurality of fiber layers.

18. The method for preparing a multi-layer composite structure according to claim 17, wherein the performing cutting, stacking, and pressing treatments on a plurality of the fiber layers to obtain a multi-layer composite structure comprises: cutting the plurality of fiber layers respectively to obtain a plurality of fiber layers of a preset size; Stack the multiple cut fiber layers; wherein, the extending directions of the fiber bundles in adjacent fiber layers are different, or, the fiber bundles in the topmost and bottommost fiber layers extend in a first direction, and the fiber bundles in the other fiber layers except the topmost and bottommost fiber layers extend in a second direction, and the first direction is different from the second direction; Perform a pressing treatment on the multiple stacked fiber layers to obtain the multi-layer composite structure.

19. The method for preparing a multi-layer composite structure according to claim 17 or 18, wherein, The mass ratio of the prepolymer solution in each fiber layer is 30% to 45%; The thickness of each fiber layer is 0.04 mm to 0.2 mm.

20. The method for preparing a multi-layer composite structure according to claim 16, wherein, The step of impregnating the fiber sheet in the prepolymer solution and performing a curing treatment to obtain a fiber layer includes: Manufacture multiple woven fiber sheets by weaving fiber bundles; at least one of the fiber bundles in the woven fiber sheets is a PBO fiber bundle; Respectively impregnate the multiple woven fiber sheets in the prepolymer solution; Control the mass ratio of the prepolymer solution in the multiple impregnated woven fiber sheets and the thickness of the multiple impregnated woven fiber sheets; Perform a curing treatment on the multiple impregnated woven fiber sheets respectively to obtain multiple fiber layers.

21. The method for preparing a multi-layer composite structure according to claim 20, wherein, The step of cutting, stacking, and pressing the multiple fiber layers to obtain a multi-layer composite structure includes: Respectively cut the multiple fiber layers to obtain multiple fiber layers of a preset size; Stack the multiple cut fiber layers; Perform a pressing treatment on the multiple stacked fiber layers to obtain the multi-layer composite structure.

22. The method for preparing a multi-layer composite structure according to claim 20 or 21, wherein, The mass ratio of the prepolymer solution in each fiber layer is 45% to 55%; The thickness of each fiber layer is 0.1 mm to 0.2 mm.

23. The method for preparing a multi-layer composite structure according to any one of claims 17 to 22, wherein, The grammage of the fiber sheet is 30 g / m 2 to 140 g / m 2 .

24. The method for preparing a multi-layer composite structure according to claim 16, wherein, The pressing treatment includes a hot pressing treatment, the temperature of the hot pressing treatment is 100°C to 200°C, the hot pressing time is 10 min to 30 min, and the hot pressing pressure is 0.2 MPa to 0.7 MPa.

25. The method for preparing a multi-layer composite structure according to claim 16, wherein, The mass ratio of the prepolymer solution in the fiber layer is 30% to 60%, and the thickness of the fiber layer is 0.03 mm to 0.3 mm.

26. A battery cover, characterized in that, It includes: A substrate layer, the substrate layer includes the multi-layer composite structure according to any one of claims 1 to 15; A decorative layer, the decorative layer is arranged on one side of the substrate layer; through holes are provided on the substrate layer and the decorative layer; The camera lens covers the through hole, and the camera lens is disposed on the side of the battery cover where the decorative layer is provided.

27. An electronic device, characterized in that, It includes: The front panel; The middle frame is disposed on one side of the front panel, and a battery slot is provided inside the middle frame; The battery is disposed in the battery slot; The battery cover as claimed in claim 26, the battery cover is disposed on the side of the middle frame away from the front panel, and the battery cover is used to protect the battery disposed in the battery slot.

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