Preparation method of a lightweight and high-strength composite board

Abstract

The present invention relates to the technical field of composite boards, and particularly relates to a preparation method of a lightweight and high-strength composite board. The preparation method of the lightweight and high-strength composite board comprises the following steps: (1) preparation of hyperbranched alumina; (2) preparation of the core material; (3) preparation of the board. By modifying hollow alumina, hyperbranched alumina is obtained, which is compounded with glass fibers and shaped to obtain the core material, and then compounded with an aluminum plate to obtain the lightweight and high-strength composite board.

Description

Technical Field

[0001] The present invention relates to the technical field of composite boards, and particularly relates to a preparation method of a lightweight and high-strength composite board. Background Art

[0002] In recent years, with the rapid development of fields such as new energy vehicles, aerospace, and architectural decoration, the market demand for structural materials with both light weight and high strength has been increasing. Although traditional metal plates (such as aluminum alloys and magnesium alloys) have relatively high mechanical strength, their density is large, making it difficult to meet the requirements of lightweight design; while single polymer materials (such as polypropylene and polyurethane foam) are light in weight, but their load-bearing capacity is insufficient, and they are prone to deformation or fracture. In addition, although ceramic matrix composites have excellent high-temperature resistance, their high brittleness and expensive processing costs limit their wide application. Currently, fiber-reinforced composite boards (such as glass fiber and carbon fiber reinforced plastics) are one of the main research directions of lightweight and high-strength materials. However, there are still problems in the prior art such as complex preparation processes, long curing times, and difficulty in recycling. Although thermoplastic matrix composite boards can be recycled, the interfacial bonding strength is insufficient, resulting in a decrease in interlaminar shear performance. To address the above problems, there is an urgent need to develop a preparation method for lightweight and high-strength composite boards to achieve lightweight while ensuring the mechanical properties of the materials. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention proposes a preparation method of a lightweight and high-strength composite board.

[0004] The present invention is achieved through the following technical solutions:

[0005] A preparation method of a lightweight and high-strength composite board, comprising the following steps:

[0006] S1. Preparation of hyperbranched alumina:

[0007] S11. Add 1-butyl-3-methylimidazolium chloride and AlCl3·6H2O to distilled water, stir at 300 - 400 rpm for 20 - 30 min, add citric acid monohydrate and urea, stir at 300 - 400 rpm for 30 min, transfer to a high-pressure autoclave with a polytetrafluoroethylene liner, seal and heat at 160 - 180 °C for 36 h, cool to room temperature, centrifuge at 8000 rpm for 10 - 15 min, wash the precipitate with deionized water and ethanol, dry in vacuum, heat to 550 °C at a rate of 2 °C / min, and calcine for 3 h to obtain hollow alumina;

[0008] S12. Take a 50 vol% ethanol solution, adjust the pH to 4 - 5 with 1 mol / L acetic acid solution, add silane coupling agent KH550, stir at 300 - 400 rpm for 3 - 5 min, let it stand for 1 h, add the hollow alumina obtained in step S11, disperse it by ultrasonic wave at 300 W for 30 min, heat up to 70 - 80 °C, stir and react at 300 rpm for 5 - 6 h, filter by suction, wash with absolute ethanol, and dry in vacuum at 60 °C to obtain amino alumina;

[0009] S13. Take EDC and NHS and dissolve them in DMSO / DMF solution. After fully dissolving gallic acid, add it dropwise to the above reaction solution, react for 2 h, add dropwise the amino alumina obtained in step S12 which is dispersed evenly by ultrasonic wave and react for 12 h, centrifuge at 8000 rpm for 10 - 15 min, wash the precipitate with DMF, and dry in vacuum to obtain gallic acid - alumina;

[0010] S14. Add gallic acid - alumina to epichlorohydrin, stir and heat up to 90 °C, add tetrabutylammonium iodide, react at 100 °C for 6 h, cool to 50 °C, add NaOH in four portions at intervals of 30 min each, react at 70 °C for 1 h, cool to room temperature, filter by suction, wash the filter cake with deionized water, and dry in vacuum to obtain epoxy - functionalized alumina;

[0011] S15. Add the epoxy - functionalized alumina obtained in step S14 to 1,2 - dichloroethane, perform ultrasonic wave at 300 W for 15 - 20 min to obtain an epoxy - functionalized alumina dispersion. Mix tris - glycidyl - p - aminophenol and 1,3 - diamino - 2 - propanol in 1,2 - dichloroethane, add it dropwise to the epoxy - functionalized alumina dispersion, reflux and react at 40 °C for 6 - 7 h, filter by suction, wash with absolute ethanol, and dry in vacuum to obtain hyperbranched alumina;

[0012] S2. Preparation of core material:

[0013] S21. Take hyperbranched alumina and mix it evenly in THF, dropwise add toluene diisocyanate at 50 °C, react for 1 h after dropping, add glass fibers with a length of 10 - 15 mm, and continue to react at 50 °C for 2 - 3 h;

[0014] S22. After the reaction in step S21 is completed, wash with ethanol, dry, spread it in a mold, and hot - press at 150 - 180 °C for 20 min to obtain the core material;

[0015] S3. Preparation of the plate: Place upper and lower polymer adhesive films and upper and lower aluminum panels on the upper and lower surfaces of the core material, pre - heat at 150 °C and then perform hot lamination and hot rolling so that the core material is located between two aluminum plates, and cold - press and shape at 2 MPa to obtain a lightweight and high - strength composite plate.

[0016] Further, in step S11, the dosage ratio of 1-butyl-3-methylimidazolium chloride, AlCl3·6H2O, distilled water, citric acid monohydrate and urea is 6 mmol: 2 mmol: 50 mL: 0.5 mmol: 4 mmol.

[0017] Further, in step S12, the dispersion concentration of the hollow alumina in the ethanol solution is 20 - 25 mg / mL.

[0018] Further, in step S12, the dosage of the silane coupling agent is 30 wt% of the hollow alumina.

[0019] Further, in step S13, in the DMSO / DMF solution, the volume ratio of DMSO to DMF is 1:3.

[0020] Further, in step S13, the dosage ratio of EDC, NHS and the DMSO / DMF solution is 1.5 g: 1 g: 180 - 200 mL.

[0021] Further, in step S13, the mass ratio of EDC, gallic acid and amino alumina is 1.5: 1: 1.

[0022] Further, in step S14, the dosage ratio of gallic acid-alumina, epichlorohydrin, tetrabutylammonium iodide and sodium hydroxide is 1 g: 8 mL: 2 mg: 0.2 g.

[0023] Further, in step S15, the dispersion concentration of the epoxy alumina in 1,2-dichloroethane is 20 - 25 mg / mL.

[0024] Further, in step S15, the mass ratio of the epoxy alumina, triglycidyl-p-aminophenol and 1,3-diamino-2-propanol is 3: 2: 2.

[0025] Further, in step S15, the mass concentration of 1,3-diamino-2-propanol in 1,2-dichloroethane is 20 - 25 mg / mL.

[0026] Further, in step S21, the dosage ratio of the hyperbranched alumina, THF, toluene diisocyanate and glass fiber is 1 g: 20 - 30 mL: 0.8 - 1 g: 1.5 - 2 g.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides a lightweight and high-strength composite board. A core material is obtained by compounding hyperbranched silica and glass fibers and hot-pressing them into shape. Glass fibers themselves have the characteristic of high strength and form a good synergistic effect with hyperbranched silica, resulting in a lightweight and high-mechanical-strength composite board. The present invention uses 1-butyl-3-methylimidazolium chloride ionic liquid to react with citric acid monohydrate and urea under heating conditions to form a precursor, and through subsequent calcination treatment, hollow alumina is obtained. The hollow structure greatly reduces the density of alumina, providing a basis for the lightweight of the composite board while ensuring strength, which is beneficial to improving the comprehensive performance of the composite board. The present invention uses a silane coupling agent to modify the hollow alumina, introducing amino groups onto the surface of alumina to obtain amino alumina. The introduction of amino groups endows the surface of alumina with active functional groups, enhancing the reactivity and binding force of alumina with subsequent reaction substances. The carboxyl group of gallic acid reacts with the amino group of amino alumina to prepare gallic acid-alumina. Gallic acid has rich phenolic hydroxyl functional groups and a rigid benzene ring group, and its introduction enriches the types and quantities of functional groups on the surface of alumina, enhancing the strength. The present invention converts the phenolic hydroxyl group of gallic acid on the surface of gallic acid-alumina into epoxy groups to obtain epoxy-group alumina. There are three epoxy groups on the gallic acid group, and the overall reactivity is high, which can form a high crosslinking density in the reaction system, providing reaction sites for subsequent construction of a hyperbranched structure and contributing to the formation of a more stable molecular structure, thereby improving the strength of the composite board. The present invention reacts epoxy-group alumina with triglycidyl-p-aminophenol and 1,3-diamino-2-propanol. Ring-opening polymerization reaction occurs between the epoxy group and the amino group, gradually constructing a hyperbranched structure and simultaneously introducing hydroxyl active groups. The hyperbranched structure has highly branched molecular chains, and the molecular chains are entangled with each other to form a three-dimensional network structure, effectively improving the mechanical properties and enhancing the overall strength and stability of the composite board. The present invention reacts hyperbranched alumina, toluene diisocyanate, and glass fibers. First, the hydroxyl group on hyperbranched alumina reacts with the isocyanate group on toluene diisocyanate, and then continues to react with the hydroxyl group on glass fibers to form a double-crosslinking system, significantly improving the strength of the core material. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only those of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 It is a schematic structural diagram of the composite board described in Embodiment 1 of the present invention;

[0031] Figure 2It is the flexural strength of the composite plates described in Examples 1-3 and Comparative Examples 1-3 of the present invention;

[0032] Figure 3 It is the tensile strength of the composite plates described in Examples 1-3 and Comparative Examples 1-3 of the present invention. Detailed implementation manners

[0033] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments. However, the present invention is not limited to the following embodiments. It should be noted that unless otherwise specified, the chemical reagents involved in the present invention are purchased through commercial channels.

[0034] Example 1: A preparation method of a lightweight and high-strength composite plate, comprising the following steps:

[0035] S1. Preparation of hyperbranched alumina:

[0036] S11. Add 6 mmol of 1-butyl-3-methylimidazolium chloride and 2 mmol of AlCl3·6H2O to 50 mL of distilled water, stir at 400 rpm for 30 min, add 0.5 mmol of citric acid monohydrate and 4 mmol of urea, stir at 400 rpm for 30 min, transfer to a high-pressure autoclave with a polytetrafluoroethylene lining, seal and heat at 180 °C for 36 h, cool to room temperature, centrifuge at 8000 rpm for 15 min, wash the precipitate with deionized water and ethanol, dry in vacuum, heat at a rate of 2 °C / min to 550 °C, and calcine for 3 h to obtain hollow alumina;

[0037] S12. Take 100 mL of a 50 vol% ethanol solution, adjust the pH to 5 with 1 mol / L acetic acid solution, add 0.75 g of silane coupling agent KH550, stir at 400 rpm for 5 min, let stand for 1 h, add 2.5 g of the hollow alumina obtained in step S11, ultrasonically disperse at 300 W for 30 min, heat to 80 °C, stir and react at 300 rpm for 6 h, filter by suction, wash with absolute ethanol, and dry in vacuum at 60 °C to obtain amino alumina;

[0038] S13. Take 1.5 g of EDC and 1 g of NHS and dissolve them in 200 mL of DMSO / DMF (v / v = 1:3) solution. After fully dissolving 1 g of gallic acid, add it dropwise to the above reaction solution, react for 2 h, add 1 g of the amino alumina obtained in step S12 that has been ultrasonically dispersed evenly and react for 12 h, centrifuge at 8000 rpm for 15 min, wash the precipitate with DMF, and dry in vacuum to obtain gallic acid-alumina;

[0039] S14. Add 1 g of gallic acid-aluminum oxide into 8 mL of epichlorohydrin, stir and heat up to 90 °C, add 2 mg of tetrabutylammonium iodide, react at 100 °C for 6 h, cool to 50 °C, add 0.2 g of NaOH in four portions with an interval of 30 min each time, react at 70 °C for 1 h, cool to room temperature, filter by suction, wash the filter cake with deionized water, and dry in vacuum to obtain epoxy group-aluminum oxide;

[0040] S15. Add 1.5 g of the epoxy group-aluminum oxide obtained in step S14 into 60 mL of 1,2-dichloroethane, ultrasonicate at 300 W for 20 min to obtain an epoxy group-aluminum oxide dispersion. Mix 1 g of triglycidyl p-aminophenol and 1 g of 1,3-diamino-2-propanol in 40 mL of 1,2-dichloroethane, and dropwise add the mixture into the epoxy group-aluminum oxide dispersion. React under reflux at 40 °C for 7 h, filter by suction, wash with absolute ethanol, and dry in vacuum to obtain hyperbranched aluminum oxide;

[0041] S2. Core material preparation:

[0042] S21. Take 1 g of hyperbranched aluminum oxide and mix it evenly in 30 mL of THF. Dropwise add 1 g of toluene diisocyanate at 50 °C. After the addition is complete, react for 1 h. Add 2 g of 15-mm glass fiber and continue to react at 50 °C for 3 h;

[0043] S22. After the reaction in step S21 is completed, wash with ethanol, dry, spread it in a mold, and hot press at 180 °C for 20 min to obtain the core material;

[0044] S3. Plate preparation: Place upper and lower polymer adhesive films and upper and lower aluminum panels on the upper and lower surfaces of the core material. After preheating at 150 °C, perform thermal lamination and hot rolling so that the core material is located between two aluminum plates, and cold press and shape at 2 MPa to obtain a lightweight and high-strength composite board. The structural schematic diagram is as Figure 1 shown.

[0045] Example 2: A method for preparing a lightweight and high-strength composite board, comprising the following steps:

[0046] S1. Hyperbranched aluminum oxide preparation:

[0047] S11. Add 6 mmol of 1-butyl-3-methylimidazolium chloride and 2 mmol of AlCl₃·6H₂O into 50 mL of distilled water, stir at 300 rpm for 20 min, add 0.5 mmol of citric acid monohydrate and 4 mmol of urea, stir at 300 rpm for 30 min, transfer to a high-pressure autoclave with a PTFE liner, seal and heat at 160 °C for 36 h, cool to room temperature, centrifuge at 8000 rpm for 10 min, wash the precipitate with deionized water and ethanol, dry in vacuum, heat to 550 °C at a rate of 2 °C / min, and calcine for 3 h to obtain hollow alumina;

[0048] S12. Take 100 mL of a 50 vol% ethanol solution, adjust the pH to 4 with 1 mol / L acetic acid solution, add 0.6 g of silane coupling agent KH550, stir at 300 rpm for 3 min, let stand for 1 h, add 2 g of the hollow alumina obtained in step S11, disperse by ultrasonic wave at 300 W for 30 min, heat to 70 °C, stir and react at 300 rpm for 5 h, filter by suction, wash with absolute ethanol, and dry in vacuum at 60 °C to obtain amino alumina;

[0049] S13. Dissolve 1.5 g of EDC and 1 g of NHS in 180 mL of DMSO / DMF (v / v = 1:3) solution, fully dissolve 1 g of gallic acid and then drop it into the above reaction solution, react for 2 h, drop and add 1 g of the amino alumina obtained in step S12 which is ultrasonically dispersed evenly and react for 12 h, centrifuge at 8000 rpm for 10 min, wash the precipitate with DMF, and dry in vacuum to obtain gallic acid-alumina;

[0050] S14. Add 1 g of gallic acid-alumina into 8 mL of epichlorohydrin, stir and heat to 90 °C, add 2 mg of tetrabutylammonium iodide, react at 100 °C for 6 h, cool to 50 °C, add 0.2 g of NaOH in four portions at intervals of 30 min each, react at 70 °C for 1 h, cool to room temperature, filter by suction, wash the filter cake with deionized water, and dry in vacuum to obtain epoxy-group alumina;

[0051] S15. Add 1.5 g of the epoxy-group alumina obtained in step S14 into 75 mL of 1,2-dichloroethane, ultrasonically disperse at 300 W for 15 min to obtain an epoxy-group alumina dispersion. Mix 1 g of triglycidyl p-aminophenol and 1 g of 1,3-diamino-2-propanol in 50 mL of 1,2-dichloroethane, and drop it into the epoxy-group alumina dispersion, reflux and react at 40 °C for 6 h, filter by suction, wash with absolute ethanol, and dry in vacuum to obtain hyperbranched alumina;

[0052] S2. Preparation of core material:

[0053] S21. Take 1 g of hyperbranched alumina, add it to 20 mL of THF and mix well. Dropwise add 0.8 g of toluene diisocyanate at 50 °C. After the addition is complete, react for 1 h. Then add 1.5 g of 10 mm fiberglass and continue to react at 50 °C for 2 h;

[0054] S22. After the reaction in step S21 is completed, wash with ethanol, dry, spread it in a mold, and hot press at 150 °C for 20 min to obtain the core material;

[0055] S3. Preparation of the plate: Place upper and lower polymer bonding films and upper and lower aluminum panels on the upper and lower surfaces of the core material. After preheating at 150 °C, perform thermal lamination and hot rolling so that the core material is located between two aluminum plates, and cold press and shape at 2 MPa to obtain the lightweight and high-strength composite plate.

[0056] Example 3: A method for preparing a lightweight and high-strength composite plate, comprising the following steps:

[0057] S1. Preparation of hyperbranched alumina:

[0058] S11. Add 6 mmol of 1-butyl-3-methylimidazolium chloride and 2 mmol of AlCl3·6H2O to 50 mL of distilled water, stir at 350 rpm for 25 min, add 0.5 mmol of citric acid monohydrate and 4 mmol of urea, stir at 350 rpm for 30 min, transfer to a high-pressure autoclave with a polytetrafluoroethylene lining, seal and heat at 170 °C for 36 h, cool to room temperature, centrifuge at 8000 rpm for 12 min, wash the precipitate with deionized water and ethanol, dry in vacuum, heat to 550 °C at a rate of 2 °C / min, and calcine for 3 h to obtain hollow alumina;

[0059] S12. Take 100 mL of 50 vol% ethanol solution, adjust the pH to 4.5 with 1 mol / L acetic acid solution, add 0.72 g of silane coupling agent KH550, stir at 350 rpm for 4 min, let stand for 1 h, add 2.4 g of the hollow alumina obtained in step S11, disperse by ultrasonic wave at 300 W for 30 min, heat to 75 °C, stir and react at 300 rpm for 5.5 h, filter by suction, wash with absolute ethanol, and dry in vacuum at 60 °C to obtain amino alumina;

[0060] S13. Take 1.5 g of EDC and 1 g of NHS and dissolve them in 190 mL of DMSO / DMF (v / v = 1:3) solution. After fully dissolving 1 g of gallic acid, dropwise add it to the above reaction solution, react for 2 h, then dropwise add 1 g of the amino alumina obtained in step S12 which is dispersed evenly by ultrasonic wave and react for 12 h, centrifuge at 8000 rpm for 12 min, wash the precipitate with DMF, and dry in vacuum to obtain gallic acid-alumina;

[0061] S14. Add 1 g of gallic acid-aluminum oxide to 8 mL of epichlorohydrin, stir and heat up to 90 °C, add 2 mg of tetrabutylammonium iodide, react at 100 °C for 6 h, cool to 50 °C, add 0.2 g of NaOH in four portions at intervals of 30 min each, react at 70 °C for 1 h, cool to room temperature, filter by suction, wash the filter cake with deionized water, and dry in vacuum to obtain epoxy group-aluminum oxide;

[0062] S15. Add 1.5 g of the epoxy group-aluminum oxide obtained in step S14 to 72 mL of 1,2-dichloroethane, ultrasonicate at 300 W for 18 min to obtain a dispersion of epoxy group-aluminum oxide. Mix 1 g of triglycidyl p-aminophenol and 1 g of 1,3-diamino-2-propanol in 48 mL of 1,2-dichloroethane, and dropwise add the mixture to the dispersion of epoxy group-aluminum oxide. React under reflux at 40 °C for 6.5 h, filter by suction, wash with absolute ethanol, and dry in vacuum to obtain hyperbranched aluminum oxide;

[0063] S2. Preparation of the core material:

[0064] S21. Take 1 g of hyperbranched aluminum oxide and mix it with 25 mL of THF. Dropwise add 0.9 g of toluene diisocyanate at 50 °C. After the addition is complete, react for 1 h, add 1.8 g of 12-mm glass fiber, and continue to react at 50 °C for 2.5 h;

[0065] S22. After the reaction in step S21 is completed, wash with ethanol, dry, spread it in a mold, and hot press at 160 °C for 20 min to obtain the core material;

[0066] S3. Preparation of the plate: Place upper and lower polymer adhesive films and upper and lower aluminum panels on the upper and lower surfaces of the core material. After preheating at 150 °C, perform hot lamination and hot rolling so that the core material is located between two aluminum plates, and cold press and shape at 2 MPa to obtain a lightweight and high-strength composite plate.

[0067] The difference between Comparative Example 1 and Example 1 is only that amino aluminum oxide is used instead of hyperbranched aluminum oxide.

[0068] The difference between Comparative Example 2 and Example 1 is only that epoxy group-aluminum oxide is used instead of hyperbranched aluminum oxide.

[0069] The difference between Comparative Example 3 and Example 1 is only that toluene diisocyanate is not added.

[0070] Experimental Example 1: Prepare lightweight and high-strength composite plates according to the methods of Examples 1-3 and Comparative Examples 1-3, and measure their flexural strength. The results are as Figure 2 shown.

[0071] Figure 2The results show that the flexural strength of the groups of Examples 1-3 is better than that of Comparative Examples 1-3. In Comparative Example 1, amino alumina was used to replace hyperbranched alumina, without introducing hyperbranched groups, resulting in a decrease in the degree of crosslinking and a reduction in mechanical strength. In Comparative Example 2, epoxy alumina was used to replace hyperbranched alumina, leading to a decrease in mechanical strength and flexural strength. In Comparative Example 3, toluene diisocyanate was not added, resulting in a decrease in crosslinking strength and flexural strength.

[0072] Experimental Example 2: Lightweight high-strength composite boards were prepared according to the methods of Examples 1-3 and Comparative Examples 1-3, and their tensile strengths were measured. The results are as Figure 3 shown.

[0073] Figure 3 The results show that the tensile strengths of Examples 1-3 are higher than those of Comparative Examples 1-3, indicating that the composite boards of Examples 1-3 have higher strength. In Comparative Example 1, amino alumina was used to replace hyperbranched alumina, resulting in a decrease in tensile strength; in Comparative Example 2, epoxy alumina was used to replace hyperbranched alumina, leading to a decrease in tensile strength; in Comparative Example 3, toluene diisocyanate was not added, resulting in a decrease in tensile strength. The above results show that a lightweight high-strength composite board prepared by the present invention has the advantages of high strength and light weight.

[0074] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a lightweight and high-strength composite board, characterized in that, It includes the following steps: S1. Preparation of hyperbranched alumina: S11. Add 1-butyl-3-methylimidazolium chloride and AlCl₃·6H₂O into distilled water, stir, add citric acid monohydrate and urea, stir, heat, cool, centrifuge, wash the precipitate, dry, and calcine to obtain hollow alumina; S12. Adjust the pH of the ethanol solution with acetic acid solution, add silane coupling agent KH550, stir, let stand, add the hollow alumina obtained in step S11, ultrasonicate, raise the temperature, stir and react, filter by suction, wash, and dry to obtain amino alumina; S13. Dissolve EDC and NHS in DMSO / DMF solution, add gallic acid dropwise, react, add amino alumina dropwise and react, centrifuge, wash the precipitate, and dry to obtain gallic acid-alumina; S14. Add gallic acid-alumina into epichlorohydrin, stir and raise the temperature, add tetrabutylammonium iodide, react, add NaOH, react, cool, filter by suction, wash, and dry to obtain epoxy alumina; S15. Add the epoxy alumina obtained in step S14 into 1,2-dichloroethane, ultrasonicate to obtain an epoxy alumina dispersion, add triglycidyl p-aminophenol and 1,3-diamino-2-propanol dropwise, reflux and react, filter by suction, wash, and dry under vacuum to obtain hyperbranched alumina; S2. Preparation of the core material: S21. Take hyperbranched alumina, mix it evenly in THF, add toluene diisocyanate dropwise, react, add glass fiber, and continue to react; S22. After the reaction in step S21 is completed, wash, dry, spread it in a mold, and hot press to obtain the core material; S3. Preparation of the board: Feed the core material, polymer adhesive film, and aluminum panel, perform hot lamination and hot rolling so that the core material is located between two aluminum plates, and cold press and shape to obtain a lightweight and high-strength composite board.

2. The preparation method of the light-weight and high-strength composite board according to claim 1, characterized in that In step S11, the dosage ratio of 1-butyl-3-methylimidazolium chloride, AlCl₃·6H₂O, distilled water, citric acid monohydrate, and urea is 6 mmol: 2 mmol: 50 mL: 0.5 mmol: 4 mmol.

3. The preparation method of the light-weight and high-strength composite board according to claim 2, characterized in that, In step S12, the dispersion concentration of the hollow alumina in the ethanol solution is 20 - 25 mg / mL; the dosage of the silane coupling agent is 30 wt% of the hollow alumina.

4. The preparation method of the lightweight and high-strength composite board according to claim 3, characterized in that, In step S13, the dosage ratio of EDC, NHS, and DMSO / DMF solution is 1.5 g: 1 g: 180 - 200 mL; the mass ratio of EDC, gallic acid, and amino alumina is 1.5: 1:

1.

5. The preparation method of the light-weight and high-strength composite board according to claim 4, characterized in that, In step S14, the dosage ratio of gallic acid-alumina, epichlorohydrin, tetrabutylammonium iodide, and sodium hydroxide is 1 g: 8 mL: 2 mg: 0.2 g.

6. The preparation method of the light-weight and high-strength composite board according to claim 5, characterized in that, In step S15, the dispersion concentration of the epoxy alumina in 1,2-dichloroethane is 20 - 25 mg / mL; the mass ratio of epoxy alumina, triglycidyl p-aminophenol, and 1,3-diamino-2-propanol is 3: 2:

2.

7. The preparation method of the light-weight and high-strength composite board according to claim 6, characterized in that, In step S21, the dosage ratio of the hyperbranched alumina, THF, toluene diisocyanate and glass fiber is 1 g: 20 - 30 mL: 0.8 - 1 g: 1.5 - 2 g.

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