High-temperature-resistant hot-weldable epoxy glass polymer material as well as preparation and application thereof

Abstract

The invention relates to the technical field of high polymer materials, and discloses a high-temperature-resistant hot-weldable epoxy glass high polymer material and preparation and application thereof.The high-temperature-resistant hot-weldable epoxy glass high polymer material is prepared from tetrafunctional epoxy resin, an anhydride curing agent, an imidazole accelerant and a thermally induced phase change latent microcapsule catalyst; the microcapsule wall material keeps a solid-phase crystalline state and physically isolates the internal catalyst from the resin matrix, so that the material maintains a three-dimensional cross-linked network structure, thereby having excellent creep resistance and mechanical strength, and when a fracture interface is heated to exceed a melting phase change threshold value of the microcapsule wall material, the microcapsule disintegrates and releases the catalyst, so that the creep resistance of the material is improved. The reaction activation energy of attacking ester bonds by free hydroxyl groups in glass-like macromolecules is remarkably reduced, and a cross-linked network is driven to spontaneously perform dynamic ester exchange reaction and topology rearrangement. According to the method, the limitation that welding repair cannot be achieved after traditional thermosetting resin is fractured is broken, and in-situ non-adhesive hot welding repair of the macroscopic fracture interface is achieved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a high-temperature resistant, heat-weldable epoxy glass polymer material and its preparation and application. Background Technology

[0002] Thermosetting epoxy resins are widely used in the manufacture of high-reliability structural components in aerospace, automotive manufacturing, and electronic packaging due to their excellent mechanical strength, dimensional stability, and high-temperature resistance. These superior comprehensive physical and chemical properties mainly stem from the permanent three-dimensional cross-linked network formed after the resin matrix is ​​cured. However, due to this irreversible cross-linked network characteristic, traditional thermosetting epoxy resins cannot be melted or shaped by heating like thermoplastics after complete curing. When the material encounters macroscopic fracture due to external impact or fatigue load during service, its fracture interface cannot spontaneously repair itself. In engineering practice, damage to such structural components usually relies on physical repair with external adhesives or direct replacement. Traditional adhesive repair methods are not only cumbersome but also introduce a heterogeneous weak interface layer in the repair area, making it difficult to substantially restore the original mechanical load-bearing capacity of the component, while also increasing the overall weight of the structure.

[0003] To endow thermosetting resins with the ability to perform hot-melt welding and self-healing, the main technical approach is to introduce dynamic covalent bonds into the resin crosslinking network, enabling the material to exhibit network topological rearrangement under external stimuli such as high temperatures. In epoxy-anhydride systems, this typically relies on directly mixing free-state metal catalysts into the resin matrix to reduce the activation energy of transesterification reactions between hydroxyl groups and ester bonds. However, this conventional approach of directly blending free catalysts has revealed inherent physical contradictions in engineering applications. The free catalysts maintain high chemical activity within the polymer matrix, leading to uncontrollable and continuous dynamic relaxation of the crosslinking network within the normal service temperature range and even under lower heating conditions. This unintended microscopic topological evolution directly reflects the deterioration of macroscopic mechanical properties, resulting in a significant decrease in the material's storage modulus, a sharp deterioration in high-temperature creep resistance, and the easy occurrence of permanent deformation in originally rigid load-bearing components, making it completely unable to meet the stringent requirements of industrial structural components for dimensional stability and long-term load-bearing reliability.

[0004] Therefore, how to break through the limitations of permanent networks and achieve on-demand hot-melt welding and glue-free seamless splicing of fracture interfaces while maintaining the initial high mechanical strength, excellent creep resistance and high-temperature dimensional stability of cross-linked polymer materials has become a technical bottleneck to be solved in the field of structural polymer materials. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-temperature resistant, heat-weldable epoxy glass polymer material and its preparation and application. It solves the problems of existing thermosetting epoxy resins forming a permanent three-dimensional cross-linked network after curing, which cannot be heat-welded or self-healed after macroscopic fracture, and the direct introduction of dynamic covalent bonds and free catalysts leading to a decrease in the material's creep resistance and mechanical strength at normal service temperatures.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a high-temperature resistant, heat-weldable epoxy-based glass polymer material, employing the following technical solution: A high-temperature resistant, heat-weldable epoxy-based glass polymer material, comprising the following raw materials in parts by weight: 100 parts of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane; 125-138 parts of methylhexahydrophthalic anhydride; 0.8-1.5 parts of 1-(2-aminoethyl)-2-methylimidazole; and 8-22 parts of a thermo-induced phase change latent microcapsule catalyst. The thermo-induced phase change latent microcapsule catalyst is used to release the catalyst when the ambient temperature exceeds its phase change threshold, thereby reducing the activation energy of free hydroxyl groups attacking ester bonds, and driving the dynamic remodeling and heat-welding repair of the cross-linked covalent network.

[0007] By employing the above technical solution, this invention utilizes the synergistic effect of a thermally induced phase change latent microcapsule catalyst and an epoxy-anhydride crosslinking system to endow the material with high-temperature interface reconstruction and thermal repair capabilities while maintaining its original high mechanical strength. Specifically, at normal service temperatures, the wall material of the microcapsules, being in a solid crystalline state, effectively isolates the highly active catalyst inside from the external resin matrix. This physically locked state allows the matrix crosslinking network to maintain an irreversible static topological structure, thus exhibiting the creep resistance and high storage modulus expected of conventional thermosetting resins. When the material undergoes macroscopic fracture and requires repair, once a temperature exceeding the melting phase change threshold of the wall material is applied to the fracture surface, the wall material structure will endothermically disintegrate. At this time, the originally sealed catalyst is released and diffuses into the polymer matrix on both sides. Zinc ions act as catalysts by activating the carbonyl group of the ester and stabilizing the alkoxide group, bringing them closer together. The energy barrier of the nucleophilic attack of the hydroxyl oxygen atom on the carbonyl carbon atom of the adjacent ester bond is significantly weakened. Driven by both a thermal field and a catalyst, a high-frequency dynamic transesterification reaction spontaneously initiates within the cross-linked network. Free hydroxyl groups nucleophilically attack ester groups to form a tetrahedral intermediate, which then breaks down to generate new ester bonds and free hydroxyl groups, as shown in the following reaction equation: ; With this topological rearrangement at the molecular scale, solid macromolecular chain segments acquire the ability to flow across interfaces, the physical gaps at the fracture surface close, the chain segments on both sides become entangled with each other and construct a continuous covalent cross-linked network for the second time, and finally complete adhesive-free fracture healing at the macroscopic scale.

[0008] Preferably, the thermo-induced phase change latent microcapsule catalyst is a microcapsule with a polycaprolactam-polyhexamethylene adipamide block copolymer as the wall material and zinc acetylacetonate as the core material. In the thermo-induced phase change latent microcapsule catalyst, the mass ratio of the polycaprolactam-polyhexamethylene adipamide block copolymer to the zinc acetylacetonate is 5~15:1~5.

[0009] By employing the above technical solution, the selected polycaprolactam-polyhexamethylene adipamide block copolymer possesses a relatively concentrated melt phase transition range and a dense structure at room temperature. This ensures that zinc acetylacetonate, as the core material, will not leak prematurely during the early high-temperature curing stage of the epoxy resin. After the wall material melts at a specific high temperature, zinc acetylacetonate, acting as a highly efficient catalyst for the transesterification reaction, is released, thereby driving dynamic network rearrangement. Simultaneously, controlling the mass ratio of wall material to core material within this range balances the dense encapsulation rate during microcapsule formation with the effective diffusion concentration of the catalyst during later rupture.

[0010] Preferably, the thermally induced phase change latent microcapsule catalyst is prepared by the following method: the polycaprolactam-polyhexamethylene adipamide block copolymer is dissolved in a mixed solvent of dichloromethane and anhydrous ethanol, zinc acetylacetone is added and ultrasonically dispersed to form an oil phase; the oil phase is added dropwise to a polyvinyl alcohol aqueous solution for high-shear emulsification, and then the solvent is evaporated by heating to precipitate microcapsules; the microcapsules are collected by centrifugation, washed and dried to obtain the thermally induced phase change latent microcapsule catalyst.

[0011] By employing the above technical solution and utilizing a solvent evaporation process, dichloromethane and anhydrous ethanol in the mixed system effectively dissolve the block copolymer, while the polyvinyl alcohol aqueous solution acts as a continuous phase medium to constrain and control the droplet size of the dispersed oil phase. Based on this, high-shear emulsification and programmed temperature rise are used to drive the wall polymer to precipitate and solidify uniformly at the droplet interface, ultimately constructing a microcapsule structure with regular particle size and high retention rate.

[0012] Preferably, the application of a high-temperature resistant, heat-weldable epoxy-based glass polymer material as described above in the preparation of material compositions for on-demand heat-welding repair or glue-free splicing of structural components with fractures.

[0013] By adopting the above technical solution and relying on the inherent on-demand phase change catalytic mechanism of the material, it is possible to effectively overcome the engineering limitations of traditional irreversible thermosetting polymer materials that can only be repaired by adding external adhesives after fracture, thereby achieving in-situ seamless splicing of the damaged component's main structure and substantial restoration of its mechanical strength.

[0014] Secondly, this invention provides a method for preparing a high-temperature resistant, heat-weldable epoxy-based glass polymer material, employing the following technical solution: A method for preparing a high-temperature resistant, heat-weldable epoxy-based glass polymer material includes the following steps: S1, adding N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane and methylhexahydrophthalic anhydride to a reaction vessel, heating and mechanically stirring until uniformly mixed; S2, cooling the system, adding 1-(2-aminoethyl)-2-methylimidazole, and continuing mechanical stirring; S3, adding a thermo-induced phase change latent microcapsule catalyst to the mixture, and stirring at low speed until the microcapsules are uniformly dispersed in the system; S4, transferring the obtained mixture into a vacuum degassing chamber for degassing treatment to obtain a bubble-free prepolymer mixture; S5, pouring the prepolymer mixture into a preheated molding mold and performing stepped programmed thermosetting; S6, after the curing process is completed, cooling and demolding to obtain the high-temperature resistant, heat-weldable epoxy-based glass polymer material.

[0015] By adopting the above technical solution, this preparation process effectively avoids the risk of curing explosion caused by violent exothermic reactions through a step-by-step component addition strategy under specific temperature control. Specifically, the tetrafunctional epoxy resin and acid anhydride are first fully fused at a higher temperature, and then the imidazole accelerator and microcapsules are introduced after the system cools down. This staggered addition method not only prevents the microcapsule wall material from suffering thermal damage or swelling and rupture during the initial high-temperature mixing stage, but also ensures its uniform dispersion within the resin matrix. Subsequent vacuum degassing eliminates residual air bubbles entrained during the stirring stage, preventing microscopic pore defects within the cured material. The final step-programmed curing allows the three-dimensional cross-linked network to interweave smoothly and release internal thermal stress, thereby endowing the macroscopic polymer material with superior overall mechanical properties.

[0016] Preferably, in step S1, the heating temperature is 70°C, the stirring speed is 300 r / min, and the stirring time is 15 minutes; in step S2, the temperature is lowered to 45°C, the stirring speed is 200 r / min, and the stirring time is 10 minutes.

[0017] By adopting the above technical solution, the S1 stage is set with a moderate heating condition of 70℃, which aims to reduce the initial component viscosity of the high-functionality resin system and promote rapid homogenization of the material under mechanical shear. After mixing, the temperature is lowered to 45℃ before introducing the imidazole accelerator, mainly to keep the system temperature below the initiation critical line of the crosslinking and curing reaction, thereby providing a more generous operating window for the subsequent degassing and casting processes.

[0018] Preferably, in step S4, the vacuum degree of the vacuum degassing treatment is -0.09 MPa, and the degassing time is 20 minutes.

[0019] By adopting the above technical solution, the specific combination of negative pressure and holding time parameters is sufficient to completely remove the tiny air bubbles encapsulated inside the high-viscosity resin slurry, thereby improving the structural density and tensile and shear bearing capacity of the final molded part from the source of the process.

[0020] Preferably, in step S5, the curing process of the stepped programmed thermosetting is as follows: 120℃ for 2 hours, 150℃ for 2 hours, and 175~180℃ for 4 hours.

[0021] By employing the above technical solution, the initial stepped temperature holding at 120℃ and 150℃ allows the macromolecular chain segments to smoothly pass through the gel point and undergo preliminary cross-linking and shaping. Subsequently, the heating range of 175~180℃ forces all remaining viable groups to react, completing the cross-linking convergence. More importantly, the peak temperature of this curing process is strictly locked below the phase change melting threshold of the microcapsule wall material. This ensures that the microcapsules maintain reliable physical sealing throughout the long thermal processing cycle, preventing premature catalyst leakage and unexpected dynamic relaxation of the network structure.

[0022] Preferably, the thermally induced phase change latent microcapsule catalyst in step S3 is prepared by a preparation process comprising the following conditions: the volume ratio of the dichloromethane to anhydrous ethanol mixed solvent is 4~6:1; and the mass fraction of the polyvinyl alcohol aqueous solution is 1%~3%.

[0023] By employing the above technical solution, this specific ratio of mixed solvent precisely balances the solubility of the block copolymer with the kinetic rate of subsequent droplet evaporation and encapsulation. Simultaneously, the 1%–3% polyvinyl alcohol aqueous solution provides necessary steric hindrance and regulates interfacial tension, effectively suppressing the aggregation and agglomeration phenomena that easily occur in oil-phase droplets during strong shear emulsification and thermal evaporation stages, thus ensuring the physical regularity of the precipitated microcapsule particles.

[0024] This invention provides a high-temperature resistant, heat-weldable epoxy-based glass polymer material, its preparation, and its application. It possesses the following beneficial effects: 1. This invention solves the problem of balancing conventional mechanical stability and dynamic repairability of polymer materials by introducing a thermally induced phase change latent microcapsule catalyst into an epoxy-anhydride crosslinking system. Below the phase change threshold temperature, the microcapsule wall material remains solid and closed, and the system maintains a static three-dimensional crosslinking network. The material has the creep resistance and high tensile shear strength of conventional thermosetting resins. When a thermal field higher than the melting point of the wall material is applied to the fracture area, the microcapsule disintegrates and releases the zinc acetylacetonate catalyst, which promotes a spontaneous dynamic transesterification reaction inside the matrix. This causes the solid macromolecular chain segments to undergo topological rearrangement and cross-interfacial entanglement at the fracture interface. In-situ adhesive-free thermal welding healing of the fractured parts can be achieved by hot pressing.

[0025] 2. This invention selects polycaprolactam-polyhexamethylene adipamide block copolymer as the microcapsule wall material and combines it with zinc acetylacetone core material to ensure the physical encapsulation stability and later reaction activity of the catalytic system. The block copolymer has a clear melting phase transition range and a dense structure under normal conditions. It can resist the environmental heat field during the early high-temperature curing stage of epoxy resin, prevent the internal zinc complex from leaking out prematurely and interfering with the initial molding of the matrix crosslinking network. After encountering specific high temperature triggering deconstruction, the large-scale release of zinc acetylacetone can rapidly reduce the activation energy required for free hydroxyl groups around the fracture surface of the glass-like polymer to attack the ortho-ester bond, thereby improving the repair efficiency of material interface reconstruction while ensuring the molding strength of the component.

[0026] 3. The preparation process of this invention adopts a combination of step-by-step cooling and feeding with step-by-step programmed curing, which ensures the complete dispersion and structural density of the microcapsule catalyst in the resin matrix. By first mixing the base resin and acid anhydride at a higher temperature to reduce the viscosity of the system, and then introducing the microcapsules and accelerator after cooling, the risk of swelling and rupture of the microcapsules due to excessive heating in the early stage of mixing is avoided. Combined with vacuum degassing treatment and a step-by-step heating program with the maximum temperature strictly below the phase change threshold of the wall material, not only are residual bubbles eliminated during the curing and cross-linking process, but the internal stress during material molding is also released smoothly, so that the final product can obtain a continuous and defect-free solid network while fully retaining the latent phase change catalytic function. Attached Figure Description

[0027] Figure 1 This is a bar chart showing the viscosity change rate of the present invention; Figure 2 A bar chart to highlight the features of this invention; Figure 3 A bar chart to highlight the melt flow rate of the present invention; Figure 4 The bar chart is provided to highlight the energy storage modulus of this invention. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0030] N,N,N',N'-Tetracyclooxypropyl-4,4'-Diaminodiphenylmethane, CAS No. 28768-32-3, epoxy equivalent is 110-130 g / eq.

[0031] Methylhexahydrophthalic anhydride, CAS number 25550-51-0, purity greater than 99.0%, anhydride equivalent of 164-168 g / eq.

[0032] 1-(2-aminoethyl)-2-methylimidazole, CAS number 13230-66-5, purity greater than 98.0%.

[0033] Polycaprolactam-polyhexamethylene adipamide block copolymer, CAS No. 24993-04-2, is a block copolymer of caprolactam and hexamethylene adipamide salt, with a weight-average molecular weight of 25,000, a molecular weight distribution index of 1.8, a crystallinity of 40%, and a melting point of 195℃.

[0034] Zinc acetylacetone, CAS number 13709-65-4, purity greater than 99.0%.

[0035] Polyvinyl alcohol, CAS number 9002-89-5, degree of alcoholysis 87%-89%, degree of polymerization 1700.

[0036] Dichloromethane, CAS number 75-09-2, purity greater than 99.5%.

[0037] Anhydrous ethanol, CAS number 64-17-5, purity greater than 99.7%.

[0038] Preparation Example 1: This preparation example provides a method for preparing a thermally induced phase change latent microcapsule catalyst, including the following steps: (1) Weigh 10g of polycaprolactam-polyhexamethylene adipamide block copolymer and add it to 100mL of a mixture of dichloromethane and anhydrous ethanol in a volume ratio of 5:1. Stir magnetically in a sealed container at 30°C for 3 hours until completely dissolved to obtain a copolyamide solution. (2) Add 3g of zinc acetylacetone to the copolyamide solution and ultrasonically disperse for 45 minutes to form a uniform suspension as the oil phase; (3) Prepare 500g of a 2% polyvinyl alcohol aqueous solution as the aqueous phase. Place the aqueous phase in a constant temperature reactor with mechanical stirring and control the temperature at 25℃. Under a high shear dispersion rate of 1000r / min, add the oil phase dropwise to the aqueous phase at a rate of 2mL / min through a constant pressure dropping funnel. After the addition is complete, continue high shear emulsification for 20 minutes. (4) Reduce the stirring speed to 400 r / min, raise the system temperature to 42°C at a heating rate of 1°C / min, keep the reactor open and stir for 10 hours to allow dichloromethane and anhydrous ethanol to slowly evaporate and the microcapsules to gradually precipitate. (5) The reaction solution was centrifuged at 5000 r / min to collect the lower layer of microcapsules, which were washed 4 times alternately with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 70℃ for 16 hours to obtain thermally induced phase change latent microcapsule catalyst A1.

[0039] Preparation Example 2: This preparation example provides a method for preparing a thermally induced phase change latent microcapsule catalyst, including the following steps: (1) Weigh 15g of polycaprolactam-polyhexamethylene adipamide block copolymer and add it to 100mL of a mixture of dichloromethane and anhydrous ethanol in a volume ratio of 6:1. Stir magnetically in a sealed container at 35°C for 4 hours until completely dissolved to obtain a copolyamide solution. (2) Add 1g of zinc acetylacetone to the copolyamide solution and ultrasonically disperse for 60 minutes to form a uniform suspension as the oil phase; (3) Prepare 500g of a 3% polyvinyl alcohol aqueous solution as the aqueous phase. Place the aqueous phase in a constant temperature reactor with mechanical stirring and control the temperature at 20℃. Under a high shear dispersion rate of 1500r / min, add the oil phase to the aqueous phase dropwise through a constant pressure dropping funnel at a rate of 1mL / min. After the addition is complete, continue high shear emulsification for 30 minutes. (4) Reduce the stirring speed to 300 r / min, raise the system temperature to 45°C at a heating rate of 1°C / min, keep the reactor open and stir for 12 hours to allow dichloromethane and anhydrous ethanol to slowly evaporate and the microcapsules to gradually precipitate. (5) The reaction solution was centrifuged at 6000 r / min to collect the lower layer of microcapsules, which were washed 5 times alternately with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 80℃ for 12 hours to obtain thermally induced phase change latent microcapsule catalyst A2.

[0040] Preparation Example 3: This preparation example provides a method for preparing a thermally induced phase change latent microcapsule catalyst, including the following steps: (1) Weigh 5g of polycaprolactam-polyhexamethylene adipamide block copolymer and add it to 100mL of a mixture of dichloromethane and anhydrous ethanol in a volume ratio of 4:1. Stir magnetically in a sealed container at 25°C for 2 hours until completely dissolved to obtain a copolyamide solution. (2) Add 5g of zinc acetylacetone to the copolyamide solution, and ultrasonically disperse for 30 minutes to form a uniform suspension as the oil phase; (3) Prepare 500g of a 1% polyvinyl alcohol aqueous solution as the aqueous phase. Place the aqueous phase in a constant temperature reactor with mechanical stirring and control the temperature at 25℃. Under a high shear dispersion rate of 800r / min, add the oil phase dropwise to the aqueous phase at a rate of 3mL / min through a constant pressure dropping funnel. After the addition is complete, continue high shear emulsification for 10 minutes. (4) Reduce the stirring speed to 500 r / min, raise the system temperature to 40°C at a heating rate of 1°C / min, keep the reactor open and stir for 8 hours to allow dichloromethane and anhydrous ethanol to slowly evaporate and the microcapsules to gradually precipitate. (5) The reaction solution was centrifuged at 4000 r / min to collect the lower layer of microcapsules, washed three times alternately with deionized water and anhydrous ethanol, and dried in a vacuum drying oven at 60℃ for 24 hours to obtain thermally induced phase change latent microcapsule catalyst A3.

[0041] Example 1: This embodiment provides a high-temperature resistant, heat-weldable epoxy-based glass polymer material and its preparation method, including the following steps: S1. Add 100g of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane and 130g of methylhexahydrophthalic anhydride to a reaction vessel, heat to 70℃ and mechanically stir at 300r / min for 15 minutes to make the system uniformly mixed. S2. Cool the system to 45℃, add 1g of 1-(2-aminoethyl)-2-methylimidazole, and continue mechanical stirring at 200r / min for 10 minutes. S3. Add 12g of the thermally induced phase change latent microcapsule catalyst A1 obtained in Preparation Example 1 to the mixture, and stir at low speed for 5 minutes until the microcapsules are uniformly dispersed in the system. S4. Transfer the obtained mixture into a vacuum degassing chamber and degas for 20 minutes under a vacuum of -0.09MPa to obtain a bubble-free prepolymer mixture. S5. Pour the prepolymer mixture into a preheated molding mold and send it into a programmable temperature-controlled oven for step-by-step heat curing. The curing process is as follows: 120℃ for 2 hours, 150℃ for 2 hours, and 180℃ for 4 hours. S6. After the curing process is completed, the furnace is allowed to cool naturally to room temperature before demolding to obtain a high-temperature resistant and heat-weldable epoxy glass polymer material.

[0042] Example 2: This embodiment provides a high-temperature resistant, heat-weldable epoxy glass polymer material and its preparation method, including the following steps: S1. Add 100g of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane and 138g of methylhexahydrophthalic anhydride to a reaction vessel, heat to 70℃ and mechanically stir at 300r / min for 15 minutes to make the system uniformly mixed. S2. Cool the system to 45℃, add 0.8g of 1-(2-aminoethyl)-2-methylimidazole, and continue mechanical stirring at 200r / min for 10 minutes. S3. Add 8g of the thermally induced phase change latent microcapsule catalyst A2 obtained in Preparation Example 2 to the mixture, and stir at low speed for 5 minutes until the microcapsules are uniformly dispersed in the system. S4. Transfer the obtained mixture into a vacuum degassing chamber and degas for 20 minutes under a vacuum of -0.09MPa to obtain a bubble-free prepolymer mixture. S5. Pour the prepolymer mixture into a preheated molding mold and send it into a programmable temperature-controlled oven for step-by-step heat curing. The curing process is as follows: 120℃ for 2 hours, 150℃ for 2 hours, and 175℃ for 4 hours. S6. After the curing process is completed, the furnace is allowed to cool naturally to room temperature before demolding to obtain a high-temperature resistant and heat-weldable epoxy glass polymer material.

[0043] Example 3: This embodiment provides a high-temperature resistant, heat-weldable epoxy glass polymer material and its preparation method, including the following steps: S1. Add 100g of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane and 125g of methylhexahydrophthalic anhydride to a reaction vessel, heat to 70℃ and mechanically stir at 300r / min for 15 minutes to make the system uniformly mixed. S2. Cool the system to 45℃, add 1.2g of 1-(2-aminoethyl)-2-methylimidazole, and continue mechanical stirring at 200r / min for 10 minutes. S3. Add 22g of the thermally induced phase change latent microcapsule catalyst A3 obtained in Preparation Example 3 to the mixture, and stir at low speed for 5 minutes until the microcapsules are uniformly dispersed in the system. S4. Transfer the obtained mixture into a vacuum degassing chamber and degas for 20 minutes under a vacuum of -0.09MPa to obtain a bubble-free prepolymer mixture. S5. Pour the prepolymer mixture into a preheated molding mold and send it into a programmable temperature-controlled oven for step-by-step heat curing. The curing process is as follows: 120℃ for 2 hours, 150℃ for 2 hours, and 180℃ for 4 hours. S6. After the curing process is completed, the furnace is allowed to cool naturally to room temperature before demolding to obtain a high-temperature resistant and heat-weldable epoxy glass polymer material.

[0044] Example 4: This embodiment provides a high-temperature resistant, heat-weldable epoxy-based glass polymer material and its preparation method, including the following steps: S1. Add 100g of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane and 130g of methylhexahydrophthalic anhydride to a reaction vessel, heat to 70℃ and mechanically stir at 300r / min for 15 minutes to make the system uniformly mixed. S2. Cool the system to 45℃, add 1.5g of 1-(2-aminoethyl)-2-methylimidazole, and continue mechanical stirring at 200r / min for 10 minutes. S3. Add 12g of the thermally induced phase change latent microcapsule catalyst A1 obtained in Preparation Example 1 to the mixture, and stir at low speed for 5 minutes until the microcapsules are uniformly dispersed in the system. S4. Transfer the obtained mixture into a vacuum degassing chamber and degas for 20 minutes under a vacuum of -0.09MPa to obtain a bubble-free prepolymer mixture. S5. Pour the prepolymer mixture into a preheated molding mold and send it into a programmable temperature-controlled oven for step-by-step heat curing. The curing process is as follows: 120℃ for 2 hours, 150℃ for 2 hours, and 180℃ for 4 hours. S6. After the curing process is completed, allow it to cool naturally to room temperature, then demold to obtain a high-temperature resistant and heat-weldable epoxy glass polymer material.

[0045] Comparative Example 1: Compared with Example 1, the difference is that the "reaction-consuming accelerator" 1-(2-aminoethyl)-2-methylimidazole is replaced with an equal mass of conventional free accelerator (such as 2-methylimidazole or N,N-dimethylbenzylamine), otherwise the same.

[0046] Comparative Example 2: Compared with Example 1, the difference is that the thermally induced phase change latent microcapsule catalyst A1 obtained in Preparation Example 1 was not added. Instead, free "zinc acetylacetonate" catalyst with an equivalent effective ingredient content (i.e., the pure amount calculated based on the microcapsule loading rate) was directly added. All other aspects are the same.

[0047] Comparative Example 3: Compared with Example 1, the difference is that the wall material of the microcapsules was replaced with a polymer wall material with a lower melting point (e.g., Tm=150℃), while all other aspects are the same.

[0048] Comparative Example 4: The difference from Example 1 is that no thermally induced phase change latent microcapsule catalyst A1 was added (nor any zinc acetylacetonate catalyst was added), while all other aspects are the same.

[0049] Test Example 1: 1. The prepolymer mixtures from Example 1, Comparative Example 2 (direct addition of equivalent free catalyst), and Comparative Example 3 (low melting point microcapsule replacement group) were taken as test objects after the vacuum degassing step but before entering the programmed temperature curing stage.

[0050] 2. Dynamic curing heat analysis was performed using a differential scanning calorimeter. Approximately 10 mg of the sample was weighed and placed in an aluminum crucible, which was then pressed and sealed. Under a high-purity nitrogen purging atmosphere of 50 mL / min, the temperature was scanned from 30 °C to 250 °C at a heating rate of 10 °C / min. The heat flow curve of the system as a function of temperature was recorded, and the exothermic peak temperature, curing enthalpy, and endothermic phase transition peak temperature were extracted.

[0051] 3. Isothermal rheological properties were tested using a rotational rheometer. A parallel plate fixture with a diameter of 25 mm was selected, and the gap was set to 1.0 mm. The test chamber temperature was preheated and stabilized at 180℃. Then, the uncured prepolymer mixture was placed in the center of the test plate, and the test frequency was set to 1 Hz, with a strain of 0.1% (controlled within the linear viscoelastic region). The change in the storage modulus of the system over 120 minutes was recorded to obtain the gel time and storage modulus data in the plateau region.

[0052] Table 1. Dynamic thermal analysis and isothermal rheological test data of prepolymer mixture.

[0053] Reference Figure 1According to the data in Table 1 and the dynamic thermal analysis curves, Example 1 exhibited a main exothermic peak of 143.7℃ and a sharp endothermic peak of 194.2℃ during the temperature rise scan. This directly confirms that the phase change microcapsules maintain intact physical boundaries within the conventional curing range, effectively preventing leakage of the internal catalyst. This isolation effect was conversely confirmed in the test of Comparative Example 2. Due to the addition of a free catalyst, Comparative Example 2 not only caused the epoxy curing exothermic peak to shift abnormally forward to 136.2℃, but also showed a significant loss in the overall exothermic enthalpy of its system. The free zinc complex intervened in the epoxy-anhydride crosslinking process, which was in a competitive reaction state, in the early stage of matrix formation, inducing side reactions or irregular ring opening on the branches. This indicates that without the physical locking barrier of the microcapsules, conventional highly active transesterification catalysts would seriously interfere with the initial three-dimensional network construction of the polymer.

[0054] By combining isothermal rheological data, it can be observed that in Comparative Example 3, due to the use of a low-melting-point wall material, the microcapsules melted and ruptured at a constant temperature of 180℃, releasing catalyst that resulted in a final storage modulus of only 1.25 × 10⁻⁶. 9 Pa exhibits a network defect state similar to that of Comparative Example 2 with a free catalyst. After being held at 180°C for 2 hours, the storage modulus of Example 1 remained stable at 1.87 × 10⁻⁶. 9 The absence of significant modulus decay in the high-elasticity plateau region of Pa indicates that the first-path accelerator in the early curing stage has been completely consumed by the reaction and anchored in the network framework. This confirms that the massive number of ester bonds in the material's crosslinked structure exhibit extremely high thermodynamic stability when they are not in contact with a free catalyst. The decoupling mechanism established above this phase transition temperature threshold allows the material to retain the high modulus performance resulting from high crosslinking density while eliminating the mutual interference between different reaction pathways during the curing stage.

[0055] Test Example 2: 1. The molding materials obtained after curing and demolding in Example 1 and Comparative Example 4 were processed into standard rectangular test strips with dimensions of 30mm×5mm×2mm using precision cutting equipment, and the edges were polished to eliminate stress concentration defects.

[0056] 2. Perform wide-temperature-range stress relaxation tests using a dynamic thermomechanical analyzer (DMA) in tensile mode. After clamping and fixing the specimen, set the test chamber to heat to the preset isothermal plateaus (180℃, 200℃, 210℃, 220℃) at a rate of 5℃ / min, and hold at this temperature for 15 minutes to eliminate the internal thermal gradient of the sample.

[0057] 3. Apply a constant tensile strain of 1% instantaneously to the equilibrium sample and maintain this strain for 10,000 seconds, recording the attenuation of internal stress within the material. Extract the instantaneous stress at each time point and divide it by the initial maximum stress to obtain the stress relaxation modulus curve. Record the time corresponding to the initial modulus decaying to 1 / e (approximately 36.8%) as the characteristic relaxation time. 4. Based on the characteristic relaxation times obtained from the tests at different absolute temperatures (T), calculate 1000 and The value of is fitted by linear regression according to the Arrhenius equation, and the activation energy (Ea) of the material above the phase transition temperature is calculated by the slope of the fitted line.

[0058] Table 2. Stress relaxation and activation energy fitting data under different temperature conditions for Example 1 and Comparative Example 4.

[0059] Since Example 1 at 180°C and Comparative Example 4 at 220°C did not undergo effective relaxation during the test period, a clear characteristic relaxation time could not be extracted, and they did not participate in activation energy fitting.

[0060] Reference Figure 2 Based on the data in Table 2 and the wide-temperature-range test results under constant strain, the topological state of the cross-linked network inside the material exhibits obvious temperature-dependent boundary characteristics. Under isothermal conditions of 180°C, Example 1 showed virtually no significant stress relaxation within an observation window of 10,000 seconds, and the normalized modulus remained high. This typical mechanical response of a permanently cross-linked network indicates that the microcapsule shell is still in a complete crystalline frozen state. It was observed that in conventional resin system development, dynamic covalent materials lacking isolation mechanisms exhibit slow topological evolution even at service temperatures, leading to macroscopic deformation. However, the test data from Example 1 confirms that the physical locking mechanism below the phase transition threshold is sufficient to endow the material with creep resistance equivalent to that of traditional thermosetting resins. As the temperature crosses the melting phase transition range of the microcapsules and reaches 200°C and above, the mechanical behavior of the material undergoes a fundamental change.

[0061] Considering the glass transition temperature of 208.4°C in Example 1 as observed in the subsequent dynamic thermomechanical analysis (DMA) test, although the test point of 200°C is still slightly lower than the material's own Tg, and the matrix has not completely crossed the glassy state into the elastic region, the disassembly of the microcapsule barrier at this point has already released a large amount of highly active catalyst. This catalytic intervention driven by the strong physical phase transition allows the crosslinked network to cross the energy barrier and initiate topological evolution before it has completely softened thermally. The stress relaxation time rapidly decreased from 3185.4 seconds at 200°C to 465.7 seconds at 220°C. Compared to Comparative Example 4, which remained in a dead network state and refused to relax at 220°C, the rapid and thorough modulus decay exhibited by Example 1 reflects the high-frequency transesterification reactions occurring between polymer segments.

[0062] The Arrhenius kinetic equation fitting results, extracted based on characteristic relaxation times at different high-temperature points, show that the activation energy of the material during the remodeling activation period is approximately 102.46 kJ / mol. This relatively low activation energy, within a reasonable range, indicates that once the shell barrier disintegrates under thermodynamic drive, the bound zinc acetylacetonate can rapidly and effectively penetrate into the surrounding matrix, significantly reducing the energy barrier of free hydroxyl groups attacking ester bonds. This allows for a rapid transformation from a macroscopic solid state to a glassy polymer with interfacial flow healing capabilities. This binary topological behavior exhibited before and after the phase transition confirms that the entire system can reliably switch between application scenarios under temperature field control.

[0063] Test Example 3: 1. The polymer materials of Examples 1-3 and Comparative Examples 1-3 after complete curing and demolding were processed into DMA standard rectangular strips with dimensions of 35mm×5mm×3mm and TMA cylindrical creep specimens with a height of 10mm and a diameter of 8mm using a CNC engraving machine. After processing, all specimens were annealed to eliminate residual stress from machining.

[0064] 2. Modulus and transition temperature of the elastic and glassy states were tested using a dynamic thermomechanical analyzer (DMA). In single cantilever beam mode, the amplitude was set to 20 μm and the test frequency to 1 Hz. Dry nitrogen gas was introduced into the test chamber, and the temperature was continuously scanned from 50 °C to 250 °C at a heating rate of 3 °C / min. The storage modulus (E') and loss factor (tanδ) curves of the system were continuously recorded. The temperature corresponding to the peak value of the loss factor was recorded as the glass transition temperature (Tg), and the storage modulus value at the 160 °C isotherm was extracted.

[0065] 3. High-temperature creep and recovery tests were conducted using a thermomechanical analyzer (TMA). A cylindrical specimen was placed on the test platform, and the temperature was programmed to reach 160°C and held at that temperature for 20 minutes. Subsequently, a constant axial stress of 0.5 MPa was instantaneously applied to the specimen in compression mode, and this loading was maintained for 30 minutes, during which the maximum creep strain was recorded. After the loading phase, the stress was instantaneously unloaded, and the strain recovery curve was recorded again at 160°C for 30 minutes. The creep recovery rate of the specimen was calculated based on the residual strain before and after unloading.

[0066] Table 3. Thermomechanical properties and high-temperature creep test data of the examples and comparative examples.

[0067] Reference Figure 3 According to the data in Table 3, the example group exhibited significant thermodynamic stability in dynamic thermomechanical analysis, with glass transition temperatures generally exceeding 195°C. This reflects the formation of a dense and highly cross-linked three-dimensional network within the matrix. In conventional epoxy network construction, highly active free transesterification catalysts often intervene at lower temperatures and interfere with the cyclization or cross-linking reactions between acid anhydrides and epoxy groups, thereby consuming some of the active functional groups.

[0068] The data from Comparative Examples 2 and 3 directly confirm this deficiency. Due to the failure of physical isolation or premature failure of the microcapsule barrier, free zinc acetylacetonate triggered severe side reactions, resulting in a significant decrease in network crosslinking density. The Tg of both groups plummeted below 160°C, and the storage modulus at the 160°C service temperature was only a few hundred MPa, showing obvious signs of softening. In addition to the initial network construction mechanism, the creep behavior of the material under long-term high-temperature service conditions further exposes the profound impact of different catalytic mechanisms on network stability. In the high-temperature creep recovery test at 160°C, Example 1, relying on the curing of the reaction-consuming promoter and the locking of the phase change microcapsules, suppressed the maximum creep strain to 1.18%, and the recovery rate after unloading was as high as 96.2%, exhibiting the elastic characteristics of a pure thermosetting polymer.

[0069] In contrast, Comparative Example 1, despite its relatively complete early-stage crosslinking network and a Tg of 196.5℃, still exhibited weakly bound or free residual accelerators in the matrix after curing. These uncovalently anchored active residues, under sustained high temperatures and external stress fields, triggered weak transesterification or relaxation side reactions between polymer segments. This localized chemical bond breaking and recombination is directly reflected in its high irreversible deformation of 4.86% and a creep recovery rate of only 48.7%. This macroscopic deformation data reveals the engineering value of the dual-track decoupling mechanism designed in this invention. The complete deactivation of the first-track curing accelerator, combined with the physical preservation of the second-track reshaping catalyst, jointly blocks the topological rearrangement path of the material below the design threshold temperature, resolving the contradiction between high-temperature creep resistance and on-demand reshaping in traditional dynamic covalent materials.

[0070] Test Example 4: 1. The reference molded plates of Examples 1-3 and Comparative Example 4, after being completely cured and demolded, were processed into standard tensile shearing strips with dimensions of 100mm×25mm×2mm using a precision cutting machine. Each strip was then completely cut in half from the middle using a benchtop split saw to form two broken half strips. The cross-sections were lightly sanded with 400-grit sandpaper to simulate real material damage and fracture surfaces.

[0071] 2. Two corresponding half-strips are overlapped and spliced ​​in a special stainless steel overlapping mold, with the overlap area length set at 12.5mm. An extremely small constant contact pressure of about 0.1MPa is applied above the overlap area to ensure physical adhesion of the two fracture surfaces at the microscale.

[0072] 3. Place the assembled fixture in a forced convection hot air circulating oven preheated and stabilized at 215℃, and maintain the temperature for 30 minutes. After cooling to room temperature, disassemble the mold to obtain the hot weld repair template.

[0073] 4. Uniaxial tensile shear failure tests were conducted on the uncut original standard specimens and the repaired specimens after heat welding using a universal testing machine. The crosshead tensile displacement rate was set to 2 mm / min, and the maximum breaking load at the moment of specimen breakage was recorded. The corresponding tensile shear strength was calculated. Using the average data of 5 parallel specimens in each group as a benchmark, the shear strength of the repaired specimen was divided by the shear strength of the original specimen to calculate the heat welding repair efficiency of the interface.

[0074] Table 4 Tensile shear strength and healing data of the original and heat-welded repair samples in the examples and comparative examples.

[0075] Reference Figure 4According to the data in Table 4, the example group exhibited significant cross-interface remodeling and healing capabilities under high-temperature hot welding conditions of 215°C. Once conventional thermosetting resins are fractured or artificially cut, their three-dimensional covalent networks are permanently blocked in physical space. As shown in the test results of Comparative Example 4, the pure thermosetting dead cross-linked network lacking the catalytic center cannot spontaneously undergo topological rearrangement under pure thermal excitation. Its fracture surface still maintains an independent phase interface after high-temperature contact, resulting in an almost zero lap shear strength, and it even separates on its own when removed from the fixture.

[0076] In the system of this embodiment, when the ambient temperature exceeds the melting threshold of the phase change microcapsules, the zinc acetylacetone catalyst, which was previously firmly sealed by physical boundaries during the solidification stage and normal service life, is completely released and penetrates into the polymer matrix on both sides through molecular thermal motion at high temperature. Under the efficient catalytic intervention of the zinc complex, the free hydroxyl groups at the fracture interface significantly reduce the activation energy barrier required to attack adjacent ester bonds, prompting the previously locked polymer segments to undergo high-frequency dynamic transesterification reactions at the interfacial scale. This macromolecular chain-level reaction not only eliminates the physical gaps at the microscopic interface but also macroscopically reconstructs a continuous covalent bond network spanning the fracture surface. Test data show that Example 3, after dynamic formulation optimization, achieved a tensile shear strength of 15.22 MPa after hot-welding repair, with a single hot-welding healing efficiency as high as 85.41%.

[0077] Previous research on structural component repair has relied heavily on external adhesives, which often introduces uncontrollable weak interface layers and alters the original dimensions of the components. This solution, however, utilizes a remodeling process activated on demand by the material's endogenous catalytic system, directly transforming the bulk material into a reactive "hot melt adhesive." This macroscopic mechanical comparison thoroughly verifies the technical closed loop of the invention's dual-track decoupling mechanism, establishing that after the material undergoes first-track solidification and locking to form a high-modulus matrix, a second-track latent catalytic system can be precisely triggered by a temperature field. This endows traditionally irreversible polymer materials with the potential for secondary processing and adhesive-free splicing.

[0078] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-temperature resistant, heat-weldable epoxy-based glass polymer material, characterized in that, The polymer material is made from raw materials comprising the following parts by weight: 100 parts of N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane; 125-138 parts of methylhexahydrophthalic anhydride; 0.8 to 1.5 parts of 1-(2-aminoethyl)-2-methylimidazole; 8-22 parts of thermally induced phase change latent microcapsule catalyst; The thermally induced phase change latent microcapsule catalyst is used to release the catalyst when the ambient temperature exceeds its phase change threshold, thereby reducing the activation energy of free hydroxyl groups attacking ester bonds, and driving the cross-linked covalent network to undergo dynamic remodeling and thermal welding repair.

2. The high-temperature resistant, heat-weldable epoxy-based glass polymer material according to claim 1, characterized in that, The thermally induced phase change latent microcapsule catalyst is a microcapsule with polycaprolactam-polyhexamethylene adipamide block copolymer as the wall material and zinc acetylacetone as the core material.

3. The high-temperature resistant, heat-weldable epoxy glass polymer material according to claim 1, characterized in that, In the thermally induced phase change latent microcapsule catalyst, the mass ratio of polycaprolactam-polyhexamethylene adipamide block copolymer to zinc acetylacetonate is (5~15):(1~5).

4. The high-temperature resistant, heat-weldable epoxy-based glass polymer material according to claim 1, characterized in that, The thermally induced phase change latent microcapsule catalyst was prepared by the following method: The polycaprolactam-polyhexamethylene adipamide block copolymer was dissolved in a mixed solvent of dichloromethane and anhydrous ethanol, zinc acetylacetone was added and ultrasonically dispersed to form an oil phase; The oil phase was added dropwise to a polyvinyl alcohol aqueous solution for high-shear emulsification, followed by heating to evaporate the solvent and precipitate the microcapsules. The thermally induced phase change latent microcapsule catalyst was obtained by centrifugation, washing, and drying.

5. A method for preparing high-temperature resistant and heat-weldable epoxy-based glass polymer materials, characterized in that, The preparation of the high-temperature resistant, heat-weldable epoxy glass polymer material as described in any one of 1-4 includes the following steps: S1. Add N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane and methylhexahydrophthalic anhydride into a reaction vessel, heat and mechanically stir until the mixture is homogeneous; S2. Cool the system, add 1-(2-aminoethyl)-2-methylimidazole, and continue mechanical stirring; S3. Add the thermally induced phase change latent microcapsule catalyst to the mixture and stir at low speed until the microcapsules are uniformly dispersed in the system; S4. Transfer the obtained mixture into a vacuum degassing chamber for degassing treatment to obtain a bubble-free prepolymer mixture; S5. Pour the prepolymer mixture into a preheated molding mold and perform stepped programmed thermosetting. S6. After the curing process is completed, cool down and demold to obtain the high-temperature resistant and heat-weldable epoxy glass polymer material.

6. The method for preparing the high-temperature resistant, heat-weldable epoxy glass polymer material according to claim 5, characterized in that, In step S1, the heating temperature is 70℃, the stirring speed is 300r / min, and the stirring time is 15 minutes; in step S2, the temperature is lowered to 45℃, the stirring speed is 200r / min, and the stirring time is 10 minutes.

7. The method for preparing the high-temperature resistant, heat-weldable epoxy glass polymer material according to claim 5, characterized in that, In step S4, the vacuum degree of the vacuum degassing process is -0.09 MPa, and the degassing time is 20 minutes.

8. The method for preparing high-temperature resistant and heat-weldable epoxy glass polymer material according to claim 5, characterized in that, In step S5, the curing process of the stepped programmed thermosetting is as follows: heat preservation at 120℃ for 2 hours, heat preservation at 150℃ for 2 hours, and heat preservation at 175~180℃ for 4 hours.

9. The method for preparing the high-temperature resistant, heat-weldable epoxy glass polymer material according to claim 5, characterized in that, The thermally induced phase change latent microcapsule catalyst described in step S3 is prepared by a process including the following conditions: the volume ratio of dichloromethane to anhydrous ethanol mixed solvent is (4~6):1; and the mass fraction of polyvinyl alcohol aqueous solution is 1%~3%.

10. The use of a high-temperature resistant, heat-weldable epoxy glass polymer material as described in any one of claims 1-4 in the preparation of a material composition for on-demand heat-welding repair or glue-free splicing of structural components with fractures.

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