High-strength thermosetting adhesive and preparation method thereof

Abstract

The invention discloses a high-strength thermosetting adhesive and a preparation method thereof, and relates to the technical field of adhesives. The microcapsules for packaging the Lewis acid are uniformly dispersed in the hydantoin epoxy resin, when the adhesive generates microcracks due to external force, the microcapsules are broken, and released titanium ions serve as a Lewis acid catalyst to quickly activate epoxy groups and trigger local cross-linking reaction; and after repairing, the bonding strength and the sealing performance are effectively recovered, and structural failure caused by accumulation of tiny damage is avoided. Nano-copper metal particles are deposited on the surface of the basalt fiber through a sol-gel method, the rough surface provides a mechanical anchoring point for a resin matrix, and interface slippage is hindered through a mechanical interlocking effect; in addition, hydroxyl groups or metal oxygen bonds on the surfaces of the nanoparticles and epoxy groups or hydroxyl groups in the hydantoin epoxy resin can form hydrogen bonds or covalent bonds, so that the tensile strength of the adhesive is improved, and the impact strength is improved. The adhesive prepared by the invention has the effects of self-repairing, high strength and high temperature resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and particularly to a high-strength thermosetting adhesive and a preparation method thereof. Background Art

[0002] Thermosetting adhesives (such as epoxy resins, polyurethanes, etc.) have been widely used in fields such as aerospace, automotive manufacturing, and the electronics industry due to their excellent adhesive properties, high temperature resistance, and chemical resistance. However, traditional thermosetting adhesives form a three-dimensional crosslinked network structure after curing. Although this irreversible chemical structure endows them with high strength and stability, it also brings significant technical limitations. Firstly, the cured adhesive is difficult to repair. Once damaged or aged, it cannot be self-repaired through simple heating or chemical treatment, resulting in a permanent decline in material properties. Secondly, traditional adhesives face great challenges during disassembly and recycling, and it is difficult to achieve efficient hierarchical recycling, which limits their application in the field of sustainable development.

[0003] In recent years, the introduction of dynamic chemical bonds has provided new ideas for solving these problems. By introducing dynamic covalent bonds (such as disulfide bonds, β-ester bonds, etc.) or dynamic non-covalent bonds (such as hydrogen bonds, metal ligand complexes, etc.) into the crosslinked network of the adhesive, reversible breakage and recombination of the crosslinked network can be achieved under specific external stimuli (such as light, heat, pH change), thereby endowing the adhesive with the ability of self-repair and controllable debonding. However, there are still deficiencies in the application of dynamic chemical bonds in the existing technology. For example, the stability of dynamic bonds is insufficient, the self-repair efficiency is low, and the responsiveness to external stimuli is limited. Therefore, developing a new type of thermosetting adhesive with both high strength, high temperature resistance, and self-repair function has become an important research direction. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-strength thermosetting adhesive and a preparation method thereof to solve the problems existing in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solution: A high-strength thermosetting adhesive, the adhesive is prepared with a self-healing microcapsule of encapsulated Lewis acid, combined with deposited particle-modified basalt fibers, and using hein epoxy resin as the matrix, and includes the following preparation steps:

[0006] (1) Mix the organotitanium chelate with absolute ethanol, then add 0.1 - 0.3% sorbitan oleate to the mixture and ultrasonically disperse it for 10 - 20 min at an ultrasonic power of 40 kHz to obtain the oil phase; dissolve 1 - 3% polyvinyl alcohol in deionized water, adjust the pH to 4 - 5 with a 5% dilute hydrochloric acid aqueous solution to obtain the water phase; slowly drop the oil phase into the water phase and perform high-speed shearing to obtain a water-in-oil emulsion; add isocyanate to the emulsion and stir and react at 40 °C for 2 h with a stirring speed of 120 - 240 rpm to form a polyurea shell layer, then centrifuge it at 3000 rpm for 10 min, take the solid after centrifugation and wash it 3 times with deionized water to remove unreacted monomers, and then freeze-dry it at -40 °C for 24 h to obtain microcapsules with a particle size of 10 - 50 μm;

[0007] (2) Immerse the pretreated basalt fibers in the sol, perform ultrasonic treatment for 10 - 30 min to ensure sufficient infiltration, and the ultrasonic power is 30 kHz; after the ultrasonic treatment, slowly volatilize the solvent at 60 °C for 4 - 8 h to form a uniform gel layer, and dry it in vacuum at 100 °C for 2 h to obtain a pre-deposited layer, and the vacuum degree is 0.085 MPa; in an H 2 / N 2 mixed atmosphere, heat-treat it at 300 °C for 1 - 3 h to reduce the Cu 2+ in the pre-deposited layer to metallic copper nanoparticles to obtain modified basalt;

[0008] (3) Dissolve the hydantoin epoxy resin in deionized water to make a resin solution with a solid content of 60%, and magnetically stir it at a speed of 120 rpm for 30 min; add 5 - 10 wt% microcapsules and 15 - 25 wt% surface-modified basalt fibers to the resin solution, and ultrasonically treat it at 40 kHz for 20 min to mix evenly to obtain a thermosetting adhesive.

[0009] Furthermore, in the step (1), the mass ratio of the organotitanium chelate to absolute ethanol is 1:9.

[0010] Furthermore, in the step (1), the concentration of the isocyanate is 5 wt% of the emulsion.

[0011] Furthermore, in the step (1), the mass ratio of the oil phase to the water phase in the high-speed shearing is 1:2 - 6, and then perform high-speed emulsification at 8000 - 12000 rpm for 10 - 20 min.

[0012] Further, the preparation method of the copper nano-composite sol in step (2) is as follows: Dissolve copper nitrate in anhydrous ethanol and mix them, then add 0.05M sodium citrate, which is the concentration of the copper nitrate ethanol solution, as a reducing agent. Then reflux at 60 - 80 °C for 30 - 90 min to form a copper nano-sol. Next, add tetraethoxysilane, and the addition amount is 5wt% of the copper nano-sol. Adjust the pH to 9 with ammonia water and stir at a speed of 240 rpm for 24 h to form a copper nano-composite sol encapsulated by SiO 2 -coated copper nano-composite sol.

[0013] Further, the concentration of the copper nitrate ethanol solution is 0.1M.

[0014] Further, the preparation method of the pretreated fiber in step (2) is as follows: Immerse the fiber in acetone and ultrasonically clean it for 20 min to remove surface oil stains and impurities. The ultrasonic power is 50 kHz, and then dry it at 80 °C for 2 h. Dissolve KH-550 in the ethanol / water mixture at 2 - 5wt%, adjust the pH to 4 - 5 with acetic acid, and stir at a speed of 240 rpm for 30 min to fully hydrolyze the silane to generate silanol. Immerse the dried fiber in the coupling agent solution, stir at a constant temperature of 60 °C for 1 - 3 h, and the stirring speed is 60 rpm. Then take out the fiber and dry it at 80 °C for 1 h to obtain the pretreated fiber.

[0015] Further, the single filament diameter of the basalt fiber is 10 - 20 μm and the length is 3 - 5 mm.

[0016] Further, the volume ratio of ethanol to water in the ethanol / water mixture is 1:1.

[0017] Further, 5% of the mixed atmosphere in step (2) is H 2 .

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0019] The present invention uses encapsulated Lewis acid as a self-healing microcapsule, combines deposited particle-modified basalt fibers, and uses a hein epoxy resin as a matrix to prepare a thermosetting adhesive to achieve the effects of self-healing, high strength, and high temperature resistance.

[0020] First, microcapsules encapsulating Lewis acid (such as organic titanium chelate) are uniformly dispersed in the hein epoxy resin. When the adhesive generates microcracks due to external forces, the stress at the crack tip causes the microcapsules to rupture, and the released titanium ions, as Lewis acid catalysts, quickly activate the epoxy groups, triggering a local cross-linking reaction. This process can be completed at room temperature or under moderate heating conditions without additional energy input, and the repair efficiency is high. The density of the cross-linked network after repair is close to that of the original material, effectively restoring the bonding strength and sealing performance, and avoiding structural failure caused by the accumulation of minor damages. It is particularly suitable for scenarios that long-term bear dynamic loads or extreme environments.

[0021] Secondly, nano copper metal particles are deposited on the surface of basalt fibers by sol-gel method. The rough surface provides mechanical anchor points for the resin matrix, and the interface slip is hindered by the mechanical interlocking effect. In addition, the hydroxyl groups or metal-oxygen bonds on the surface of the nanoparticles can form hydrogen bonds or covalent bonds with the epoxy groups or hydroxyl groups in the hein epoxy resin, further strengthening the interfacial chemical bonding. The introduction of basalt fibers greatly enhances the mechanical properties and heat resistance. Basalt fibers, with high modulus, high strength and excellent thermal stability, form a rigid-tough complementary composite structure with the hein epoxy resin. The fibers are tightly combined with the resin matrix through interfacial shear, hindering crack propagation and dispersing stress, thus improving the tensile strength and impact strength of the adhesive. Specific embodiments

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0023] In order to more clearly illustrate the method provided by the present invention, the following embodiments are used for detailed description. The test methods for each index of a high-strength thermosetting adhesive prepared in the following embodiments are as follows:

[0024] Peel strength: The examples and comparative examples are coated on aluminum alloy plates, and the glue application amount is controlled at 100 g / m 3 , and then the coated plates are cured at 80 °C for 2 h. The peel strength of the adhesive is detected according to the standard GB / T 39289-2020, and the average value is calculated by measuring 5 times.

[0025] Heat resistance: The examples and comparative examples are coated on aluminum alloy plates, and the glue application amount is controlled at 100 g / m 3 , and then the coated plates are cured at 80 °C for 2 h to measure the bonding strength; then it is placed in a blast drying oven for heat treatment at 300 °C for 30 min, and the bonding strength is tested again after cooling; calculate the retention rate of the bonding strength after heat treatment.

[0026] Self-healing situation: The examples and comparative examples are coated on aluminum alloy plates, and the glue application amount is controlled at 100 g / m 3 , and then the coated plates are cured at 80 °C for 2 h. Cracks with a length of 100 μm are made on the surface of the cured film, heated at 60 °C for 2 h, and the crack closure situation is observed under a microscope. Calculate the repair efficiency = (crack closure length / original crack length) × 100%.

[0027] Example 1

[0028] (1) Mix the organotitanium chelate and absolute ethanol at a mass ratio of 1:9, add 0.1% sorbitan oleate to the mixture and ultrasonically disperse for 10 min with an ultrasonic power of 40 kHz to obtain the oil phase; dissolve 1% polyvinyl alcohol in deionized water, adjust the pH to 4 with 5% dilute hydrochloric acid to obtain the water phase; slowly drop the oil phase into the water phase at a mass ratio of 1:2, and shear- emulsify at 8000 rpm for 10 min to form a water-in-oil emulsion; add 5 wt% isocyanate to the emulsion, and stir and react at 40 °C and 120 rpm for 2 h to form a polyurea shell layer; centrifuge at 3000 rpm for 10 min and then wash 3 times with deionized water to remove unreacted monomers, and freeze-dry at -40 °C for 24 h to obtain microcapsules with a particle size of 10 μm;

[0029] (2) Dissolve copper nitrate in absolute ethanol to make a 0.1 M solution, add 0.05 M sodium citrate as a reducing agent, reflux at 60 °C for 30 min to form copper nanosol, then add 5 wt% tetraethoxysilane, adjust the pH to 9 with ammonia water, and stir at 240 rpm for 24 h to form a SiO 2 -coated copper nanocomposite sol; Take basalt fibers with a monofilament diameter of 10 μm and a length of 3 mm, immerse them in acetone and ultrasonically clean for 20 min with an ultrasonic power of 50 kHz, and dry at 80 °C for 2 h; Dissolve KH-550 in an ethanol / water mixture at 2 wt%, adjust the pH to 4 with acetic acid, and stir at 240 rpm for 30 min to hydrolyze the silane to form silanol; Immerse the dried fibers in the coupling agent solution, stir at a constant temperature of 60 °C for 1 h with a stirring speed of 60 rpm, take them out and dry at 80 °C for 1 h to obtain pretreated fibers; Immerse the pretreated basalt fibers in the sol and ultrasonically treat for 10 min with an ultrasonic power of 30 kHz; After the ultrasonic treatment, slowly evaporate the solvent at 60 °C for 4 h to form a uniform gel layer, and vacuum dry at 100 °C for 2 h (vacuum degree 0.085 MPa) to obtain a pre-deposited layer; In H 2 / N 2 mixed atmosphere (5% H 2 ) heat-treat at 300 °C for 1 h to reduce the Cu 2+ in the pre-deposited layer to metallic copper nanoparticles to obtain modified basalt;

[0030] (3) Dissolve the hein epoxy resin in deionized water to make a resin solution with a solid content of 60%, and stir magnetically at 120 rpm for 30 min; add 5 wt% microcapsules and 15 wt% surface-modified basalt fibers, and ultrasonically treat at 40 kHz for 20 min to mix evenly to obtain a thermosetting adhesive.

[0031] Example 2

[0032] (1) Mix the organotitanium chelate and absolute ethanol at a mass ratio of 1:9, add 0.2% sorbitan oleate to the mixture and ultrasonically disperse for 15 min with an ultrasonic power of 40 kHz to obtain the oil phase; dissolve 2% polyvinyl alcohol in deionized water, adjust the pH to 4.5 with 5% dilute hydrochloric acid to obtain the water phase; slowly drop the oil phase into the water phase at a mass ratio of 1:4, and perform high-speed shear emulsification at 10,000 rpm for 15 min to form a water-in-oil emulsion; add 5 wt% isocyanate to the emulsion, and stir and react at 40 °C and 180 rpm for 2 h to form a polyurea shell layer; centrifuge at 3,000 rpm for 10 min and then wash 3 times with deionized water to remove unreacted monomers, and freeze-dry at -40 °C for 24 h to obtain microcapsules with a particle size of 30 μm;

[0033] (2) Dissolve copper nitrate in absolute ethanol to make a 0.1 M solution, add 0.05 M sodium citrate as a reducing agent, reflux at 70 °C for 60 min to form copper nanosol, then add 5 wt% tetraethoxysilane, adjust the pH to 9 with ammonia water, and stir at 240 rpm for 24 h to form SiO 2 -coated copper nanocomposite sol; Take basalt fibers with a single filament diameter of 15 μm and a length of 4 mm, immerse them in acetone and ultrasonically clean for 20 min with an ultrasonic power of 50 kHz, and dry at 80 °C for 2 h; Dissolve KH-550 at 3.5 wt% in an ethanol / water mixture, adjust the pH to 4.5 with acetic acid, and stir at 240 rpm for 30 min to hydrolyze the silane to generate silanol; Immerse the dried fibers in the coupling agent solution, stir at a constant temperature of 60 °C for 2 h with a stirring speed of 60 rpm, take them out and dry at 80 °C for 1 h to obtain pretreated fibers; Immerse the pretreated basalt fibers in the sol and ultrasonically treat for 20 min with an ultrasonic power of 30 kHz; After the ultrasonic treatment, slowly volatilize the solvent at 60 °C for 6 h to form a uniform gel layer, and vacuum dry at 100 °C for 2 h (vacuum degree 0.085 MPa) to obtain a pre-deposited layer; In H 2 / N 2 mixed atmosphere (5% H 2 ) heat-treat at 300 °C for 2 h to reduce the Cu 2+ in the pre-deposited layer to metallic copper nanoparticles to obtain modified basalt;

[0034] (3) Dissolve the hein epoxy resin in deionized water to make a resin solution with a solid content of 60%, and magnetically stir at 120 rpm for 30 min; add 7.5 wt% microcapsules and 20 wt% surface-modified basalt fibers, and ultrasonically treat at 40 kHz for 20 min to mix evenly to obtain a thermosetting adhesive.

[0035] Example 3

[0036] (1) Mix the organotitanium chelate and absolute ethanol at a mass ratio of 1:9, add 0.3% sorbitan oleate to the mixture and ultrasonically disperse for 20 min with an ultrasonic power of 40 kHz to obtain the oil phase; dissolve 3% polyvinyl alcohol in deionized water, adjust the pH to 5 with 5% dilute hydrochloric acid to obtain the water phase; slowly drop the oil phase into the water phase at a mass ratio of 1:6, and shear emulsify at a high speed of 12000 rpm for 20 min to form a water-in-oil emulsion; add 5 wt% isocyanate to the emulsion, and stir and react at 40 °C and 240 rpm for 2 h to form a polyurea shell; centrifuge at 3000 rpm for 10 min and then wash 3 times with deionized water to remove unreacted monomers, and freeze-dry at -40 °C for 24 h to obtain microcapsules with a particle size of 50 μm;

[0037] (2) Dissolve copper nitrate in absolute ethanol to make a 0.1 M solution, add 0.05 M sodium citrate as a reducing agent, reflux at 80 °C for 90 min to form copper nanosol, then add 5 wt% tetraethoxysilane, adjust the pH to 9 with ammonia water, and stir at 240 rpm for 24 h to form a SiO 2 -coated copper nanocomposite sol; Take basalt fibers with a single filament diameter of 20 μm and a length of 5 mm, immerse them in acetone and ultrasonically clean for 20 min with an ultrasonic power of 50 kHz, and dry at 80 °C for 2 h; Dissolve KH-550 at 5 wt% in an ethanol / water mixture, adjust the pH to 5 with acetic acid, and stir at 240 rpm for 30 min to hydrolyze the silane to generate silanol; Immerse the dried fibers in the coupling agent solution, stir at a constant temperature of 60 °C for 3 h with a stirring speed of 60 rpm, take them out and dry at 80 °C for 1 h to obtain pretreated fibers; Immerse the pretreated basalt fibers in the sol and ultrasonically treat for 30 min with an ultrasonic power of 30 kHz; After the ultrasonic treatment, slowly volatilize the solvent at 60 °C for 8 h to form a uniform gel layer, and vacuum dry at 100 °C for 2 h (vacuum degree 0.085 MPa) to obtain a pre-deposited layer; In H 2 / N 2 mixed atmosphere (5% H 2 ) heat-treat at 300 °C for 3 h to reduce the Cu 2+ in the pre-deposited layer to metallic copper nanoparticles to obtain modified basalt;

[0038] (3) Dissolve the hein epoxy resin in deionized water to make a resin solution with a solid content of 60%, and magnetically stir at 120 rpm for 30 min; add 10 wt% microcapsules and 25 wt% surface-modified basalt fibers, and ultrasonically treat at 40 kHz for 20 min to mix evenly to obtain a thermosetting adhesive.

[0039] Comparative Example 1

[0040] The difference between Comparative Example 1 and Example 2 is that step (1) is absent, and step (3) is changed to: Dissolve the hydantoin epoxy resin in deionized water to make a resin solution with a solid content of 60%, and stir magnetically at 120 rpm for 30 min; add 7.5 wt% of the organic titanium chelate and 20 wt% of the surface-modified basalt fibers, and ultrasonically treat at 40 kHz for 20 min to mix evenly to obtain the thermosetting adhesive; the remaining steps are the same as those in Example 2.

[0041] Comparative Example 2

[0042] The difference between Comparative Example 2 and Example 2 lies in the difference in step (1). Step (1) is changed to: Add 0.2% sorbitan oleate to the mixture in absolute ethanol and ultrasonically disperse for 15 min, with an ultrasonic power of 40 kHz to obtain the oil phase; dissolve 2% polyvinyl alcohol in deionized water, adjust the pH to 4.5 with 5% dilute hydrochloric acid to obtain the water phase; slowly drop the oil phase into the water phase at a mass ratio of 1:4, and perform high-speed shearing emulsification at 10,000 rpm for 15 min to form a water-in-oil emulsion; add 5 wt% isocyanate to the emulsion, and stir and react at 40 °C and 180 rpm for 2 h to form a polyurea shell layer; centrifuge at 3000 rpm for 10 min and then wash 3 times with deionized water to remove unreacted monomers, and freeze-dry at -40 °C for 24 h to obtain microcapsules with a particle size of 30 μm; the remaining steps are the same as those in Example 2.

[0043] Comparative Example 3

[0044] The difference between Comparative Example 3 and Example 2 lies in the difference in step (2). Step (2) is changed to: Dissolve copper nitrate in absolute ethanol to make a 0.1 M solution, add 0.05 M sodium citrate as a reducing agent, reflux at 70 °C for 60 min to form copper nanosol, then add 5 wt% tetraethoxysilane, adjust the pH to 9 with ammonia water, and stir at 240 rpm for 24 h to form a SiO 2 -coated copper nanocomposite sol; Immerse the basalt fibers in the sol and ultrasonically treat for 20 min, with an ultrasonic power of 30 kHz; after the ultrasonic treatment, slowly evaporate the solvent at 60 °C for 6 h to form a uniform gel layer, and vacuum dry at 100 °C for 2 h (vacuum degree 0.085 MPa) to obtain the pre-deposited layer; in H 2 / N 2 mixed atmosphere (5% H 2 ) at 300 °C for 2 h to reduce the Cu 2+ in the pre-deposited layer to metallic copper nanoparticles to obtain the modified basalt; the remaining steps are the same as those in Example 2.

[0045] Comparative Example 4

[0046] The difference between Comparative Example 4 and Example 2 is that step (2) is absent, and step (3) is modified as follows: Dissolve the hydantoin epoxy resin in deionized water to make a resin solution with a solid content of 60%, and stir magnetically at 120 rpm for 30 min; add 7.5 wt% microcapsules, and ultrasonically treat at 40 kHz for 20 min to mix evenly to obtain a thermosetting adhesive; the remaining steps are the same as those in Example 2.

[0047] Comparative Example 5

[0048] The difference between Comparative Example 5 and Example 2 lies in step (2). Modify step (2) as follows: Take basalt fibers with a monofilament diameter of 15 μm and a length of 4 mm, immerse them in acetone and ultrasonically clean for 20 min, with an ultrasonic power of 50 kHz, and dry at 80 °C for 2 h; dissolve KH-550 in an ethanol / water mixture at 3.5 wt%, adjust the pH to 4.5 with acetic acid, and stir at 240 rpm for 30 min to hydrolyze the silane to form silanol; immerse the dried fibers in the coupling agent solution, stir at a constant temperature of 60 °C for 2 h, with a stirring speed of 60 rpm, take them out and dry at 80 °C for 1 h to obtain modified basalt; the remaining steps are the same as those in Example 2.

[0049] Comparative Example 6(

[0050] The difference between Comparative Example 6 and Example 2 lies in step (3). Modify step (3) as follows: Dissolve the epoxy resin in deionized water to make a resin solution with a solid content of 60%, and stir magnetically at 120 rpm for 30 min; add 7.5 wt% microcapsules and 20 wt% surface-modified basalt fibers, and ultrasonically treat at 40 kHz for 20 min to mix evenly to obtain a thermosetting adhesive; the remaining steps are the same as those in Example 2.

[0051] Effect Example

[0052] The following Table 1 gives the performance analysis results of a high-strength thermosetting adhesive using Examples 1 to 3 and Comparative Examples 1 to 6 of the present invention.

[0053] Table 1

[0054]

[0055]

[0056] From the comparison of the experimental data of the repair rate between the examples and the comparative examples, it can be found that the microcapsules encapsulating the Lewis acid-organic titanium chelate of the present invention are uniformly dispersed in the hydantoin epoxy resin. When microcracks are generated in the adhesive due to external forces, the stress at the crack tip causes the microcapsules to rupture, and the released titanium ions act as Lewis acid catalysts to rapidly activate the epoxy groups, triggering a local cross-linking reaction. This process can be completed at room temperature or under moderate heating conditions without additional energy input, and has a high repair efficiency. The compactness of the cross-linked network after repair is close to that of the original material, effectively restoring the bonding strength and sealing performance, and avoiding structural failure caused by the accumulation of minor damages. From the comparison of the experimental data of the peel strength between the examples and the comparative examples, it can be found that the present invention deposits nano-copper metal particles on the surface of basalt fibers by the sol-gel method. The rough surface provides mechanical anchor points for the resin matrix, and hinders interface slippage through the mechanical interlocking effect. In addition, the hydroxyl groups or metal-oxygen bonds on the surface of the nanoparticles can form hydrogen bonds or covalent bonds with the epoxy groups or hydroxyl groups in the hydantoin epoxy resin, further strengthening the interfacial chemical bonding. From the comparison of the experimental data of the retention rate between the examples and the comparative examples, it can be found that the present invention significantly enhances the mechanical properties and heat resistance by introducing basalt fibers. Due to the high modulus, high strength and excellent thermal stability of basalt fibers, a rigid-tough complementary composite structure is formed with the hydantoin epoxy resin.

[0057] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims concerned.

Claims

1. A high-strength thermosetting adhesive, wherein the adhesive is prepared by embedding Lewis acid as a self-repairing microcapsule, combining sedimented particle-modified basalt fiber, and using hydantoin epoxy resin as a matrix, characterized in that: The method comprises the following preparation steps: (1) mixing an organic titanium chelate with anhydrous ethanol, then adding 0.1-0.3% sorbitan oleate to the mixture and ultrasonically dispersing for 10-20 minutes at an ultrasonic power of 40 kHz to obtain an oil phase; dissolving 1-3% polyvinyl alcohol in deionized water, adjusting the pH to 4-5 with a 5% dilute hydrochloric acid aqueous solution to obtain an aqueous phase; slowly dripping the oil phase into the aqueous phase, and shearing at high speed to obtain an oil-in-water emulsion; adding isocyanate to the emulsion, stirring and reacting at 40° C. for 2 hours at a stirring speed of 120-240 rpm to form a polyurea shell layer, and then centrifuging it at a speed of 3000 rpm for 10 minutes. After centrifugation, taking the solid and washing it with deionized water for 3 times to remove unreacted monomers, and then freeze-drying it at -40° C. for 24 hours to obtain microcapsules with a particle size of 10-50 μm; (2) The pretreated basalt fiber was immersed in the sol and ultrasonically treated for 10-30 min to ensure sufficient infiltration, with an ultrasonic power of 30 kHz; after the ultrasonic treatment, the solvent was slowly evaporated at 60 ° C for 4-8 h to form a uniform gel layer, and vacuum dried at 100 ° C for 2 h to obtain a pre-deposition layer with a vacuum degree of 0.085 MPa; in a H2 / N2 mixed atmosphere, the pre-deposition layer was heat treated at 300 ° C for 1-3 h to remove the Cu 2+ Reduction to metallic copper nanoparticles to produce modified basalt; (3) dissolving hydantoin epoxy resin in deionized water to prepare a resin solution with a solid content of 60%, and magnetically stirring the solution at a speed of 120 rpm for 30 min; adding 5-10 wt % microcapsules and 15-25 wt % surface-modified basalt fibers to the resin solution, ultrasonically treating the mixture at 40 kHz for 20 min to mix the mixture evenly, and preparing a thermosetting adhesive.

2. The method for preparing a high-strength thermosetting adhesive according to claim 1, characterized in that: In the step (1), the mass ratio of the organic titanium chelate to anhydrous ethanol is 1:

9.

3. The method for preparing a high-strength thermosetting adhesive according to claim 1, characterized in that: The isocyanate concentration in step (1) is 5 wt % of the emulsion.

4. The method for preparing a high-strength thermosetting adhesive according to claim 1, characterized in that: In the step (1), the mass ratio of the oil phase to the water phase during high-speed shearing is 1:2-6, and then high-speed emulsification is performed at 8000-12000 rpm for 10-20 minutes.

5. The method for preparing a high-strength thermosetting adhesive according to claim 1, characterized in that: The method for preparing the copper nanocomposite sol in step (2) is as follows: copper nitrate is dissolved in anhydrous ethanol and mixed, and then 0.05M sodium citrate in a copper nitrate ethanol solution is added as a reducing agent, and then refluxed at 60-80°C for 30-90min to form a copper nanocomposite sol, and then tetraethoxysilane is added in an amount of 5wt% of the copper nanosol, and the pH is adjusted to 9 with ammonia water, and stirred at 240rpm for 24h to form a SiO2-wrapped copper nanocomposite sol.

6. The method for preparing a high-strength thermosetting adhesive according to claim 5, characterized in that: The concentration of the copper nitrate ethanol solution is 0.1M.

7. The method for preparing a high-strength thermosetting adhesive according to claim 1, characterized in that: The method for preparing the pretreated fiber in step (2) is as follows: immersing the fiber in acetone for ultrasonic cleaning for 20 minutes to remove surface oil and impurities, the ultrasonic power is 50kHz, and then drying at 80°C for 2 hours; dissolving KH-550 in an ethanol / water mixture at 2-5wt%, adjusting the pH to 4-5 with acetic acid, stirring at 240rpm for 30 minutes to fully hydrolyze the silane to generate silanol; immersing the dried fiber in a coupling agent solution, stirring at a constant temperature of 60°C for 1-3 hours, and the stirring speed is 60rpm, then taking out the fiber and drying it at 80°C for 1 hour to obtain the pretreated fiber.

8. The method for preparing a high-strength thermosetting adhesive according to claim 7, characterized in that: The basalt fiber monofilament has a diameter of 10-20 μm and a length of 3-5 mm.

9. The method for preparing a high-strength thermosetting adhesive according to claim 7, characterized in that: The volume ratio of ethanol to water in the ethanol / water mixture is 1:

1.

10. The method for preparing a high-strength thermosetting adhesive according to claim 1, characterized in that: In the step (2), 5% of the mixed atmosphere is H2.

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