Polyurea resin-based fiber reinforced composite material as well as preparation method and application thereof

Abstract

The invention discloses a polyurea resin-based fiber reinforced composite material as well as a preparation method and application thereof. The composite material is of a multi-layer structure and comprises a main body layer formed by compounding a polyurea resin mixture and a fiber reinforcement and contact layers compounded on the upper surface and the lower surface of the main body layer, and the contact layers are formed by compounding fibrofelt and the polyurea resin mixture. According to the invention, a fiber reinforcement fabric weaving form matched with the wettability of the high-toughness polyurea resin mixture is selected, and the compounding of the polyurea resin mixture is combined, so that the technical problems of poor wettability of the polyurea resin in the composite material and difficult forming are solved. The composite material plate has the characteristics of excellent impact resistance, light weight, flame retardance and corrosion resistance, is particularly suitable for manufacturing a high-performance automobile battery bottom protection plate, and can effectively protect a battery pack from being impacted and damaged by a road surface.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, specifically to a polyurea resin-based fiber-reinforced composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the requirements for vehicle safety performance, lightweighting, and battery protection are increasing. As a key component protecting the vehicle chassis's power battery pack from road impacts, scratches, gravel collisions, and corrosive substances, the performance of the battery underbody protection plate is of paramount importance.

[0003] Currently, automotive underbody protection panels on the market are mainly made of metal (such as steel plates and aluminum alloy plates) or traditional fiber-reinforced composite materials. While metal underbody protection panels offer high strength, they are heavy, hindering vehicle weight reduction, impacting driving range, and are prone to corrosion. Traditional fiber-reinforced composite underbody protection panels typically use epoxy resin as the matrix and carbon fiber or glass fiber as reinforcement. Although epoxy resin-based composites have high specific strength, they have poor toughness and are brittle. Under sudden impact loads (such as bottoming out or gravel impacts), they are prone to cracking, delamination, or even breakage, resulting in insufficient protective reliability. Furthermore, the curing of epoxy resin systems usually requires high temperatures, generating thermal stress that may cause product deformation, and placing high demands on production equipment and energy consumption.

[0004] Polyurea resins, especially polyaspartic acid ester polyurea, have been used in protective coatings due to their excellent toughness, high impact resistance, corrosion resistance, and rapid curing at room temperature. However, using them as matrix resins in fiber-reinforced composites, particularly in the preparation of structural panels, presents significant challenges. The complex molecular structure and high reactivity of polyurea resins make them prone to cross-linking during the composite process, leading to a sharp increase in system viscosity. This results in poor wetting of the reinforcing fiber fabrics. Poor wetting can cause defects such as porosity, delamination, and bulging within the composite material, severely affecting the mechanical properties and appearance quality of the panel. This technical challenge limits the widespread application of high-performance polyurea resins in fiber-reinforced composites. Summary of the Invention

[0005] This invention aims to overcome the aforementioned deficiencies of the prior art and provides a polyurea resin-based fiber-reinforced composite material. This material exhibits excellent impact resistance, lightweight properties, and good surface quality. The invention also provides a method for preparing this material, which effectively solves the problems of poor wettability of polyurea resin to aramid fabrics and difficulties in molding. Furthermore, this invention provides an automotive battery underbody protection plate made from this material, which significantly improves its protective performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, a polyurea resin-based fiber-reinforced composite material is provided, comprising a main body layer and a contact layer. The main body layer is formed by combining a polyurea resin mixture with a fiber reinforcement. The contact layer is disposed on the upper and lower surfaces of the main body layer and is formed by combining a fiber felt and a polyurea resin mixture. The main body layer and the contact layer are integrally composited.

[0007] In another embodiment, the polyurea resin mixture comprises, by weight, 45-55 parts of a main agent, 45-55 parts of an elastic curing agent, and 0.2-0.3 parts of a catalyst; the main agent comprises, by weight, 70-100 parts of aspartic resin and 0-1 parts of diethyl maleate; the curing agent comprises, by weight, 20-50 parts of hexamethylene diisocyanate trimer, 50-70 parts of hexamethylene diisocyanate prepolymer, and 0-0.1 parts of hexamethylene diisocyanate monomer; and the catalyst is ethylene glycol.

[0008] In another embodiment, the fiber reinforcement is woven in the form of a unidirectional fabric or a plain weave fabric.

[0009] In another embodiment, the fiber reinforcement is an aramid unidirectional fabric or an aramid plain weave fabric.

[0010] Secondly, a method for preparing polyurea resin-based fiber-reinforced composite materials is provided, comprising the following steps: S11. Fiber felt, fiber reinforcement and fiber felt are laid on the mold in sequence to form a laminated preform; S12. Apply a polyurea resin mixture to the laminated preform to ensure that the polyurea resin mixture fully impregnates the laminated preform. S13. Compression Curing: The laminated preform impregnated with polyurea resin mixture is compression cured at room temperature to obtain a polyurea resin-based fiber-reinforced composite material.

[0011] In another embodiment, the fiber reinforcement is an aramid plain weave fabric or an aramid unidirectional fabric.

[0012] In another implementation, Teflon and release film are sequentially applied to the inner wall of the mold before the laminated preform is laid on the mold.

[0013] In another embodiment, the molding and curing pressure is 5-8 MPa, the holding time is 1-3 hours, and the temperature is 15-30°C.

[0014] Thirdly, a car battery underbody protection plate is provided, comprising an underbody protection plate body made of the above-mentioned polyurea resin-based fiber reinforced composite material, and a buffer layer disposed on one side of the underbody protection plate body, the buffer layer being spaced apart.

[0015] The buffer layer is a polyphenylene ether foam layer.

[0016] An adhesive layer is provided between the bottom protective plate body and the buffer layer.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention uses a composite material board prepared by combining a polyurea resin system with a fiber reinforcement. The polyurea resin system gives the composite material board extremely high elongation at break and energy absorption capacity, while the fiber reinforcement provides excellent tensile strength and stiffness. Under the synergistic effect of the polyurea resin system and the fiber reinforcement, the impact performance of the composite material board is improved by more than 60% compared with the traditional epoxy resin system composite material board. (2) By compounding the polyurea resin system and selecting fiber reinforcement with a specific weaving form (plain weave or unidirectional fabric), the present invention can quickly complete resin impregnation under normal temperature molding conditions, which solves the problems of poor impregnation of fiber reinforcement and short operation time caused by increased viscosity of polyurea resin in the process of molding composite parts, and breaks through the key process bottleneck of polyurea resin in the field of composite materials. (3) Using this resin system and unidirectional or plain weave fabric, curing can be completed under normal temperature molding conditions. Compared with heat curing molding with heat in and heat out, it can reduce the release of thermal stress in the product, avoid the risk of shrinkage and deformation of the material after molding, and reduce the cost of tooling and molds in the product development process. (4) As a further application of polyurea-based fiber reinforced sheet material, the underbody of the car battery is made of polyurea-based aramid fiber reinforced sheet material as the main body of the underbody, providing core mechanical strength, impact resistance and flame retardant performance; the buffer layer set on the main body of the underbody can further absorb and disperse impact energy, and provide buffer when a violent impact occurs, forming a multi-level protection mechanism, which greatly enhances the protection capability of the battery pack. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a polyurea fiber-reinforced board; Figure 2 This is a schematic diagram of the structure of the bottom protection plate for a car battery. Explanation of reference numerals in the attached drawings: 1-Composite material sheet; 11-Main layer; 12-Contact layer; 2-Bottom protective plate main body; 3-Buffer layer. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0020] Example 1

[0021] This embodiment provides a polyurea resin-based fiber-reinforced composite material and its preparation method.

[0022] like Figure 1 As shown, a polyurea resin-based fiber-reinforced composite material 1 includes a main layer 11 and a contact layer 12. The main layer 11 is composed of a polyurea resin mixture and a fiber reinforcement. The contact layer 12 is disposed on the upper and lower surfaces of the main layer 11 and is composed of a fiber felt and a polyurea resin mixture. The main layer and the contact layer are integrally composited.

[0023] The polyurea resin mixture comprises, by weight, 45-55 parts of main agent, 45-55 parts of elastic curing agent, and 0.25 parts of catalyst ethylene glycol; the main agent comprises, by weight, 70-100 parts of aspartic resin and 0-1 parts of diethyl maleate; the curing agent comprises, by weight, 20-50 parts of hexamethylene diisocyanate trimer, 50-70 parts of hexamethylene diisocyanate prepolymer, and 0-0.1 parts of hexamethylene diisocyanate monomer.

[0024] The fiber reinforcement is an aramid fabric, and the aramid fabric is a unidirectional fabric.

[0025] The preparation method of the above-mentioned polyurea resin-based fiber-reinforced composite material includes the following steps: S11. Fiberglass mat, aramid unidirectional fabric, and fiberglass mat are sequentially laid on the mold to form a laminated preform. The aramid fabric is laid in 5 layers, with the laying angle alternating between 0° and 90° (the product length direction is defined as 0°), and the thickness of each layer is 0.5 mm. Two layers of fiberglass mat are laid on the upper and lower surfaces respectively, with a single layer thickness of 0.1 mm. Before laying the laminated preform, Teflon and release film are first laid on the mold to facilitate subsequent product demolding. S12. Under normal temperature conditions, apply polyurea resin mixture to the laminated preform using a glue gun to ensure that the polyurea resin mixture fully impregnates the laminated preform. S13: Compression Curing: The laminated preform impregnated with polyurea resin mixture is compression cured at room temperature at a pressure of 7 MPa for 100 minutes to obtain a polyurea resin-based fiber-reinforced composite material.

[0026] During the preparation process, the polyurea resin mixture penetrates the laminated preform within 10 seconds; after 10 minutes, the viscosity of the polyurea resin mixture increases to 1426 mPa·s; the cured board is flat and smooth. In this invention, the penetration time refers to the time required for the polyurea resin mixture to wet from the resin application surface (i.e., the coating surface or the injection surface) of the laminated preform to the back surface of the laminated preform.

[0027] Example 2

[0028] The difference between this embodiment and Embodiment 1 is that the catalyst ethylene glycol in the polyurea resin mixture is 0.2 parts by weight.

[0029] During the preparation process, the polyurea resin mixture can autonomously penetrate the laminated preform within 10 seconds; after 10 minutes, the viscosity of the polyurea resin mixture increases to 1205 mPa.s; the cured and molded board is flat and smooth.

[0030] Example 3

[0031] The difference between this embodiment and Embodiment 1 is that the catalyst ethylene glycol in the polyurea resin mixture is 0.3 parts by weight.

[0032] During the preparation process, the polyurea resin mixture can autonomously penetrate the laminated preform within 10 seconds; after 10 minutes, the viscosity of the polyurea resin mixture increases to 1426 mPa.s; the cured and molded board is flat and smooth.

[0033] Example 4

[0034] The difference between this embodiment and Embodiment 1 is that the fiber reinforcement is an aramid plain weave fabric.

[0035] During the preparation process, the polyurea resin mixture can autonomously penetrate and laminate the preform within 10 seconds; the cured board is flat and smooth.

[0036] Example 5

[0037] This embodiment provides a car battery underbody protection plate.

[0038] See appendix Figure 2 An automotive battery underbody protection plate is disclosed, comprising an underbody protection plate body 2 made of polyurea resin-based fiber-reinforced composite material as described in Example 1, and a buffer layer 3 disposed on the underbody protection plate body 2; the buffer layer 3 is spaced apart on one side of the underbody protection plate body 2. The buffer layer 3 is a polyphenylene ether foam layer; an adhesive layer is disposed between the underbody protection plate body 2 and the buffer layer 3.

[0039] The method for preparing the automotive battery underbody protection plate includes the following steps: S1. Preparation of the main body of the bottom protective plate: S11. According to the size requirements of the automotive battery underbody plate, fiberglass mat, fiber reinforcement, and fiberglass mat are sequentially laid in the molded section to form a laminated preform. S12. Apply a polyurea resin mixture to the laminated preform to ensure that the polyurea resin mixture fully impregnates the laminated preform. S13: Compression Curing: The laminated preform impregnated with polyurea resin mixture is compression cured at room temperature to obtain the bottom protection plate body; S2. Prepare the buffer layer; S3. Roughen the surface of the buffer layer to be installed on the main body of the bottom guard plate, and then glue the buffer layer to the main body of the bottom guard plate to obtain the car battery bottom guard plate.

[0040] Performance tests were conducted on the automotive battery underbody protection plate in this embodiment: (1) Weight: Compared with steel plate bottom guards of the same size, the weight is reduced by about 30%; (2) Impact resistance: Compared with the bottom protection plate made of epoxy resin system of the same size, its impact resistance is improved by nearly 60%.

[0041] Comparative Example 1 As a comparative example of Example 1, the difference is that the catalyst has a weight of 0.1 parts.

[0042] During the molding process, polyurea resin can quickly penetrate the laminated preform. After 10 minutes, the viscosity of the polyurea resin mixture increases to 980 mPa.s. After 120 minutes of molding and curing, the product still fails to cure.

[0043] Comparative Example 2 As a comparative example of Example 1, the difference is that the catalyst has a weight of 0.4 parts.

[0044] During the preparation process, the polyurea resin mixture can penetrate the laminated preform on its own within 10 seconds; after 10 minutes, the viscosity of the polyurea resin mixture increases to 2420 mPa.s; the product can be cured, but because the resin viscosity is too high and the fluidity is poor in the initial stage of molding, the molded board exhibits phenomena such as bulging and glue accumulation.

[0045] Comparative Example 3 As a comparative example of Example 1, the difference is that the fiber reinforcement is made of aramid biaxial fabric.

[0046] During the preparation process, it takes at least 60 seconds for the polyurea resin mixture to fully penetrate the laminated preform, and the cured board has surface bulging defects.

[0047] Comparative Example 4 As a comparative example, the difference lies in that the fiber reinforcement is made of aramid biaxial warp-knitted laminate.

[0048] During the preparation process, it takes at least 60 seconds for the polyurea resin mixture to fully penetrate the laminated preform, and bulging defects may also appear on the surface.

[0049] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A polyurea resin-based fiber-reinforced composite material, characterized in that, It includes a main body layer and a contact layer. The main body layer is composed of a polyurea resin mixture and a fiber reinforcement. The contact layer is disposed on the upper and lower surfaces of the main body layer and is composed of a fiber felt and a polyurea resin mixture. The main body layer and the contact layer are integrally molded.

2. The polyurea resin-based fiber-reinforced composite material according to claim 1, characterized in that, The polyurea resin mixture comprises, by weight, 45-55 parts of main agent, 45-55 parts of elastic curing agent, and 0.2-0.3 parts of catalyst; the main agent comprises, by weight, 70-100 parts of polyaspartic acid ester resin and 0-1 parts of diethyl maleate; the curing agent comprises, by weight, 20-50 parts of hexamethylene diisocyanate trimer, 50-70 parts of hexamethylene diisocyanate prepolymer, and 0-0.1 parts of hexamethylene diisocyanate monomer; the catalyst is ethylene glycol.

3. The polyurea resin-based fiber-reinforced composite material according to claim 1, characterized in that, The fiber reinforcement is a unidirectional fabric or a plain weave fabric.

4. The polyurea resin-based fiber-reinforced composite material according to claim 3, wherein the fiber reinforcement is an aramid unidirectional fabric or an aramid plain weave fabric.

5. The method for preparing the polyurea resin-based fiber-reinforced composite material according to any one of claims 1-4, characterized in that, Includes the following steps: S11. Fiber felt, fiber reinforcement and fiber felt are laid on the mold in sequence to form a laminated preform; S12. Apply a polyurea resin mixture to the laminated preform to ensure that the polyurea resin mixture fully impregnates the laminated preform. S13. Compression Curing: The laminated preform impregnated with polyurea resin mixture is compression cured at room temperature to obtain a polyurea resin-based fiber-reinforced composite material.

6. The preparation method according to claim 5, characterized in that, In step S11, the fiber reinforcement is an aramid plain weave fabric or an aramid unidirectional fabric.

7. The preparation method according to claim 5, characterized in that, In step S13, the molding and curing pressure is 5-8 MPa, the holding time is 1-3 hours, and the temperature is 15-30℃.

8. A car battery underbody protection plate, characterized in that, It includes a bottom plate body made of polyurea resin-based fiber-reinforced composite material as described in any one of claims 1-4, and a buffer layer disposed on the bottom plate body, the buffer layer being spaced apart on one of the surfaces of the bottom plate body.

9. A car battery underbody protection plate according to claim 8, characterized in that, In the polyurea resin-based fiber-reinforced composite material, the fiber reinforcement is aramid plain weave fabric or aramid unidirectional fabric; the buffer layer is a polyphenylene ether foam layer.

10. A car battery underbody protection plate according to claim 8, characterized in that, An adhesive layer is also provided between the buffer layer and the main body of the bottom protective plate.

Images