An adhesive, a preparation method and application thereof

Abstract

This invention relates to an adhesive, its preparation method, and its application. The adhesive comprises three components: A, B, and C. Component A includes: 5-15 parts of multifunctional epoxy resin; 3-10 parts of bio-based modified epoxy resin; 0.5-2.5 parts of environmentally friendly reactive diluent; 0.2-0.6 parts of silane coupling agent; and 0.6-2.4 parts of thixotropic agent. Component B includes: 2-6 parts of amine curing agent; 1.5-4 parts of bio-based phenolic amine curing agent; 0.5-2 parts of accelerator; 40-60 parts of high-strength, high-modulus inert filler; and 0.2-0.4 parts of environmentally friendly pigment. Component C includes: 10-30 parts of surfactant filler. Components A, B, and C are packaged separately and mixed in a weight ratio of 1:3:1 during application. The adhesive provided by this invention achieves a synergistic balance between low-temperature application performance and high-strength performance at room temperature, and can simultaneously maintain adhesive properties, rheological properties, and high strength under both room temperature and low-temperature conditions.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, especially adhesives. Specifically, it relates to an adhesive and its preparation and use methods and applications, which are suitable for construction in negative temperature environments and maintain high strength after the ambient temperature returns to normal. Background Technology

[0002] Currently, my country's energy system is undergoing a critical period of profound transformation, and vigorously developing renewable energy sources, represented by wind power, has become an important path to building a clean, low-carbon, safe, and efficient energy structure. As wind turbines develop towards larger, lighter, and more reliable designs, tower structures are constantly evolving. Among these, concrete-steel hybrid towers have become the mainstream structural form for ultra-high wind turbine towers due to their advantages of high load-bearing capacity and high construction efficiency. This type of structure typically uses precast concrete segments assembled on-site, and the quality of the segment joints directly affects the overall structure's load-bearing capacity and service life.

[0003] Epoxy adhesives are widely used in the assembly and connection of precast segments due to their excellent bonding and mechanical properties. However, my country's wind energy-rich areas are mainly concentrated in the "Three Norths" (Northeast, North, and Northwest China) and plateau regions. These areas experience low winter temperatures, large diurnal temperature variations, and short construction periods. Low-temperature construction conditions have become one of the key factors restricting the efficient construction of wind power projects. Under sub-zero temperatures of -20℃, conventional epoxy adhesives generally suffer from problems such as significantly reduced reaction rates, increased system viscosity, uneven mixing, shortened curing windows, or even failure to cure, making it difficult to meet the requirements of engineering construction.

[0004] Meanwhile, wind turbine towers must withstand complex loads and environmental effects over long periods of service, placing higher demands on the mechanical properties and durability of adhesives during normal-temperature service. Existing low-temperature curing epoxy systems typically improve low-temperature reactivity by reducing crosslinking density or introducing flexible segments, but this often leads to the material softening after the environment returns to normal temperature (due to diurnal temperature variations or the transition from winter to spring), making it difficult to achieve a balance between "low-temperature workability" and "high strength at normal temperature."

[0005] Furthermore, traditional solvent-based epoxy adhesives often release large amounts of volatile organic compounds (VOCs) during production and use, adversely affecting the environment and construction safety. Simultaneously, their main raw materials are highly dependent on petroleum-based systems, and the non-renewable nature of these resources limits their long-term sustainable development. Currently, the most widely used bisphenol A type epoxy resin on the market uses bisphenol A, a raw material with certain biotoxicity. Therefore, developing environmentally friendly epoxy systems based on renewable resources is of great significance for promoting the green and low-carbon transformation of the epoxy resin industry.

[0006] With the continuous expansion of engineering application needs, the application scenarios of epoxy adhesives have gradually extended from the assembly of wind power hybrid tower segments to the rapid prototyping and engineering repair of large-sized complex components, such as nonlinear irregular curved surface 3D printing, and interface reinforcement and modification of lightweight porous inorganic aggregates such as coral aggregate, shale aggregate, and fly ash ceramsite. These applications not only require materials with good mechanical properties, but also place higher demands on the rheological controllability, interfacial bonding ability, and high filler adaptability of the system.

[0007] Existing research, for example, Chinese patent application CN104449514A discloses a room-temperature curing epoxy resin adhesive for road and bridge construction. It includes component A and component B, with the following mass proportions: Component A: 100 parts epoxy resin; 30-40 parts flexible epoxy resin; 5-15 parts diluent; Component B: 60-70 parts curing agent; 3-5 parts toughening agent; 1-3 parts accelerator; 0.2-0.5 parts defoamer. CN104449514A focuses on bonding and waterproofing, but does not address the construction and curing issues at -20℃ low-temperature environments. It also does not take into account rheological properties, high-strength structural reinforcement mechanisms, synergistic control of multi-level particle size fillers, environmental friendliness, and efficient resource utilization. Therefore, it cannot be applied in various engineering scenarios such as complex curved surface 3D printing and lightweight porous aggregate reinforcement.

[0008] For example, Chinese patent application CN106281160A discloses a room-temperature curing flexible epoxy adhesive, composed of component A epoxy resin and component B epoxy curing agent. The raw material composition and weight percentages of component A epoxy resin are: 100.5–115 parts epoxy resin, 0.5–20 parts reactive diluent, and 0.5–20 parts epoxy accelerator. The raw material composition and weight percentages of component B epoxy curing agent are: 5–15 parts alicyclic amine curing agent, 28–100 parts polyether amine curing agent, 10–80 parts curing accelerator, and 0.5–2 parts bonding accelerator. CN106281160A focuses on room-temperature curing, high bonding strength, good low-temperature flexibility, and elastic bonding. However, it does not consider rheological properties, filler compatibility, environmental friendliness, and efficient resource utilization, and therefore cannot achieve the high strength performance and application in various engineering scenarios such as complex curved surface 3D printing and lightweight porous aggregate reinforcement.

[0009] For example, Chinese patent application CN106928891A discloses an epoxy-based low-temperature curing high-strength adhesive. The raw materials, by weight, include modified bisphenol A epoxy resin, modified bisphenol F epoxy resin, -SH-based modified amine curing agent, 692 epoxy reactive diluent, silane coupling agent, and special accelerator. CN106928891A focuses on low-temperature to room-temperature curing, low odor, and low toxicity. However, it does not take into account rheological properties, high strength, multi-level particle size filler synergistic control, and efficient resource utilization, making it unsuitable for application in various engineering scenarios such as complex curved surface 3D printing and lightweight porous aggregate reinforcement. Chinese patent application CN119639403A discloses a low-temperature two-component epoxy adhesive system for wind power hybrid towers, comprising an epoxy resin component (A) and a curing agent component (B) in a weight ratio of (1.5-2.2):1; the epoxy resin component (A) contains 80-150 parts by weight of epoxy resin (a1), 5-15 parts by weight of diluent (a2), 3-8 parts by weight of thixotropic agent (a3), and 150-300 parts by weight of filler I (a4); the curing agent component (B) contains 50-200 parts by weight of curing agent (b1) and 100-300 parts by weight of filler II (b2); CN119639403A focuses on achieving the construction and bonding of epoxy adhesive in a low-temperature environment of -15℃, but does not take into account the synergistic control of multi-level particle size fillers, environmental friendliness, and efficient resource utilization.

[0010] It is evident that existing epoxy adhesive systems generally suffer from low curing rates, short application windows, and difficulty in achieving effective cross-linking under sub-zero temperatures. While some low-temperature curing systems can improve low-temperature application performance, this is usually achieved by reducing cross-linking density or introducing a large number of flexible segments, leading to a decline in mechanical properties after the material returns to room temperature, making it difficult to meet the requirements of high strength and long-term durability for engineering structures. Furthermore, existing technologies in high-filler systems also suffer from poor flowability, easy settling, and application difficulties, making it difficult to simultaneously achieve high filler content, high strength, and good application performance. The extensive use of petroleum-based raw materials and organic solvents also results in insufficient environmental friendliness of the system.

[0011] Therefore, there is an urgent need to develop an epoxy adhesive system that can achieve normal construction and effective curing at -20℃, continue to cure and maintain high strength after the environment returns to normal temperature, and at the same time have interfacial bonding performance, good rheological properties, high strength, filler adaptability and environmental friendliness, so as to meet the engineering application needs of wind power hybrid tower assembly, complex curved surface 3D printing and lightweight porous aggregate reinforcement. Summary of the Invention

[0012] To address the problems of difficult construction under low temperature conditions, insufficient mechanical properties at room temperature, poor environmental friendliness, and poor fluidity of high filler systems in existing technologies, this invention provides an environmentally friendly epoxy adhesive that can be cured at low temperature, its preparation method, and its application, so as to achieve a synergistic unity between low-temperature (-20℃) construction performance and high-strength performance at room temperature, while also taking into account bonding performance, rheological properties, high strength (120 MPa), as well as green, low-carbon, and resource-efficient utilization.

[0013] To achieve the above objectives, the first aspect of the present invention provides an environmentally friendly epoxy adhesive that can be cured at low temperatures, comprising component A, component B, and component C, wherein: component A comprises the following components in parts by weight: 5-15 parts of multifunctional epoxy resin; 3-10 parts of bio-based modified epoxy resin; 0.5-2.5 parts of environmentally friendly reactive diluent; 0.2-0.6 parts of silane coupling agent; and 0.6-2.4 parts of thixotropic agent; component B comprises the following components in parts by weight: 2-6 parts of amine curing agent; 1.5-4 parts of bio-based phenolic amine curing agent; 0.5-2 parts of accelerator; 40-60 parts of high-strength, high-modulus inert filler; and 0.2-0.4 parts of environmentally friendly pigment; component C comprises the following components in parts by weight: 10-30 parts of surfactant filler; components A, B, and C are packaged separately and mixed in a weight ratio of 1:3:1 during application.

[0014] Preferably, component A is composed of the following raw materials in parts by weight: 10 parts of multifunctional epoxy resin, 5 parts of bio-based modified epoxy resin, 2.2 parts of environmentally friendly reactive diluent, 0.6 parts of silane coupling agent, and 2 parts of thixotropic agent.

[0015] Preferably, component B is composed of the following raw materials in parts by weight: 3 parts of amine curing agent, 1.5 parts of bio-based phenolic amine curing agent, 0.5 parts of accelerator, 55 parts of high-strength, high-modulus inert filler, and 0.2 parts of environmentally friendly pigment.

[0016] Preferably, component C is composed of the following raw materials in parts by weight: 20 parts of surface-active filler.

[0017] Preferably, the multifunctional epoxy resin is any one or more of pentaerythritol tetraglycidyl ether (PGE), 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE), phenolic epoxy resin (F-44), and tetraglycidyl-4,4'-diaminodiphenylmethane (TCDM).

[0018] Preferably, the bio-based modified epoxy resin is a vanillin-based epoxy resin, prepared by the following method: (1) Vanillin is added to a reaction vessel, and excess epichlorohydrin (ECH) is added at a speed of 400-800 rpm. An etherification reaction is carried out at 60-90℃ for 2-5 h to generate a β-chlorohydrin ether intermediate; (2) NaOH solution is slowly added dropwise at 40-60℃ to carry out an alkaline ring-closing reaction, causing the chlorohydrin structure to undergo a dehydrochlorination reaction to generate an epoxy group structure; (3) After the reaction is completed, the mixture is allowed to stand and separate into layers, washed with water until neutral to remove sodium chloride, and the unreacted epichlorohydrin is removed by vacuum distillation to obtain a high-purity vanillin-based epoxy resin with an epoxy equivalent of 190-260 g / eq.

[0019]

[0020] Preferably, the environmentally friendly reactive diluent is a compound system of cashew phenol glycidyl ether (CGE) and epoxidized soybean oil (ESO), with ESO accounting for 5%-20% of the total diluent. For example, 1.8 parts of CGE and 0.4 parts of ESO are added to a vacuum stirrer and mixed. CGE is used to reduce the viscosity of the system and improve the low-temperature reactivity, while ESO is used to improve the flexibility of the system.

[0021] Preferably, the silane coupling agent is KH560, which, as an interfacial reactive coupling agent for adhesives, mainly achieves interfacial reinforcement between inorganic fillers and organic resins through chemical bonding. Specifically, KH560 first undergoes a hydrolysis reaction to generate silanol groups (Si-OH), which then undergo a condensation reaction with the hydroxyl groups (-OH) on the surface of the inorganic filler to form MO-Si (M is Si, Al, Ca, etc.), thereby constructing a stable chemical bonding layer on the surface of the inorganic phase. Simultaneously, the epoxy functional groups in its molecules can undergo a ring-opening reaction with amine curing agents to form a covalent cross-linked structure, allowing the coupling agent molecules to further embed into the epoxy cross-linked network. Ultimately, a composite structure of "filler-inorganic interface layer-organic segment-epoxy network" is constructed between the inorganic and organic phases, thereby improving the interfacial compatibility, stress transmission capability, and overall mechanical properties of the system.

[0022] Preferably, the thixotropic agent is a compound system of organic bentonite and fumed silica. For example, 1.5 parts of organic bentonite and 0.5 parts of fumed silica are added to a vacuum stirrer and mixed. The organic bentonite constructs a three-dimensional lamellar skeleton structure, and the fumed silica forms an interparticle hydrogen bond network. The two work together to construct a multi-scale thixotropic network, so that the system exhibits a high yield stress structure in a static state and shear thinning behavior under shear action, thereby achieving excellent anti-sagging and anti-settling stability in a high-filler system.

[0023] Preferably, the amine curing agent is any one of triethylenetetramine (TETA), tetraethylenepentamine (TEPA), polyetheramine D230, phenolic amine curing agent (T31), and polyamide 650.

[0024] Preferably, the bio-based phenolic amine curing agent is prepared by cashew phenol, formaldehyde and aliphatic polyamine under Mannich condensation reaction conditions, wherein the aliphatic polyamine includes diethylenetriamine (DETA) and triethylenetetramine (TETA).

[0025] Preferably, the preparation method under the Mannich condensation reaction conditions includes: (1) mixing diethylenetriamine and triethylenetetramine in a reaction vessel at a set mass ratio of 3:2, premixing under a nitrogen atmosphere to obtain an amine mixture, with the premixing temperature controlled at 25-40℃ and the stirring rate at 300-600rpm; (2) slowly adding formaldehyde aqueous solution to the amine mixture under continuous stirring, controlling the reaction temperature at 40-60℃; (3) then slowly adding cashew phenol to the system, raising the temperature to 80-110℃, and reacting under a nitrogen atmosphere for 3-6 hours; (4) after the reaction is completed, raising the system to 100-110℃ for dehydration under reduced pressure to remove unreacted formaldehyde, water and low molecular weight amine, finally obtaining a dark to brownish viscous liquid with an active hydrogen equivalent of 85-115g / eq. In bio-based phenolic amine curing agents, the phenolic hydroxyl groups can activate the epoxy groups through hydrogen bonding, thereby increasing the electrophilicity of the epoxy carbon atoms, promoting the ring-opening reaction of the epoxy groups and reducing the activation energy of the reaction. At the same time, the hydrophobic alkyl segments in its molecular structure reduce the competitive adsorption of water molecules on the amine activity through steric hindrance, allowing the system to still undergo effective cross-linking reaction at -20℃.

[0026] Preferably, the accelerator is any one or a combination of trimethyldiamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 2-methylimidazole, which can effectively promote the ring-opening polymerization and cross-linking reaction between epoxy resin and curing agent, reduce the activation energy of the system, and increase the curing reaction rate.

[0027] Preferably, the high-strength, high-modulus inert filler is selected from any one or a combination of corundum powder (Al2O3), quartz powder (SiO2), basalt powder, diabase powder, and silicon carbide (SiC), and is obtained from industrial solid waste or natural rock through crushing, ball milling, and sieving. Here, the high-strength, high-modulus inert filler can form a rigid load-bearing skeleton structure in the epoxy resin curing network. Due to the filler's high elastic modulus and mechanical strength, it can effectively bear and disperse local stress under external loads, inhibit crack propagation, and thus improve the system's compressive and tensile strength. This invention employs a multi-level particle size high-filler system for synergistic control, where small-diameter fillers can fill the pore regions between large-diameter particles, thereby increasing the overall packing density of the system and reducing internal porosity, forming a denser composite structure. This multi-scale particle packing structure can effectively reduce the free volume and local stress concentration within the system, improve the overall mechanical properties and dimensional stability of the material, and simultaneously reduce the risk of system curing shrinkage. Furthermore, with a total filler content as high as approximately 80%, the synergistic regulation among a multi-stage particle size filler system, environmentally friendly reactive diluents, and thixotropic agents prevents a sharp increase in system viscosity and improves the system's rheological properties, ensuring good mixing uniformity, workability, and anti-sagging performance. Additionally, using industrial solid waste or natural minerals as sources of high-strength fillers achieves a high proportion of filler substitution and resource utilization, thereby reducing dependence on high-purity synthetic raw materials, significantly lowering material costs, and improving the comprehensive utilization efficiency of solid waste.

[0028] Preferably, the high-strength, high-modulus inert filler is selected from 5.5 parts of 5-20μm corundum powder, 13.75 parts of 10-50μm quartz powder, 19.25 parts of 50-150μm basalt powder, and 16.5 parts of 100-300μm diabase powder. It is easy to understand that the 5-20μm corundum powder and 10-50μm quartz powder are small-diameter particle fillers, while the 50-150μm basalt powder and 100-300μm diabase powder are large-diameter particle fillers.

[0029] Preferably, the environmentally friendly pigment is biomass carbon black, which is produced by pyrolysis and carbonization of straw, sawdust, or fruit shells at 500-700℃ under an inert atmosphere such as nitrogen or argon. The environmentally friendly pigment is used to distinguish components A and B, and the color of the adhesive is adjusted by controlling the amount of pigment added. The inert atmosphere can be nitrogen or argon, etc.

[0030] Preferably, the surface-active filler is obtained by acid activation or calcination activation treatment of silica fume, metakaolin, or mineral powder. Its surface is rich in hydroxyl groups or active silica-alumina sites, which can undergo condensation reaction with silane coupling agents, thereby enhancing the interfacial bonding strength between the organic and inorganic phases.

[0031] A second aspect of this invention also provides a method for preparing an epoxy adhesive, comprising the following steps: adding component A and component B in a 1:3 mass ratio to a vacuum stirrer and stirring at 600-800 rpm for 10-20 minutes to ensure the system is fully and uniformly dispersed and reacts to form a low-crosslinking prepolymer system; then slowly adding component C to the mixture over a period of 2-5 minutes, and continuing stirring for 5-10 minutes to obtain the epoxy adhesive. During this process, components A and B first form a low-crosslinking prepolymer network structure, and then component C is introduced. The curing reaction of the system exhibits a staged characteristic, transforming the concentrated release of curing exothermics into a gradient release, thereby reducing local exothermic peaks and the risk of local uncured areas under low-temperature conditions, and significantly extending the construction operation time at -20°C. The silane coupling agent undergoes a condensation reaction with the hydroxyl groups on the surface of the surfactant filler, forming a stable chemical bonding interface between the filler and the resin matrix. At the same time, under the synergistic effect of organobentonite and fumed silica, a multi-scale thixotropic structure composed of a particle-supported structure, a hydrogen-bonded associative network, and an epoxy prepolymer network is gradually constructed inside the system.

[0032] The curing reaction mechanism between bio-based modified epoxy resin and bio-based phenolic amine curing agent is shown in the following formula (the curing reaction mechanism between multifunctional epoxy resin and amine curing agent is the same). The epoxy groups undergo a ring-opening reaction under the action of amine groups to generate hydroxyl groups, further forming a three-dimensional cross-linked network structure. At -20℃, traditional epoxy systems are prone to hindered cross-linking reactions and incomplete curing due to decreased molecular chain mobility, increased system viscosity, and difficulty in overcoming the activation energy. In this invention, the flexible segments in the bio-based modified epoxy resin can improve the molecular chain mobility under low-temperature conditions, and the phenolic hydroxyl groups in the bio-based phenolic amine curing agent can pre-activate the epoxy groups through hydrogen bonding, increasing the electrophilicity of the epoxy carbon atoms and reducing the activation energy of the epoxy ring-opening reaction. This promotes the formation of an initial cross-linked network even at -20℃, achieving effective curing and application. After the ambient temperature returns to normal, the multifunctional epoxy resin and amine curing agent continue to undergo post-curing reaction, which further densifies the cross-linked network, improves the overall mechanical strength, interfacial adhesion and structural stability of the material, and achieves a synergistic unity of low-temperature workability and high-strength performance at room temperature.

[0033]

[0034] A third aspect of the present invention also provides the application of the epoxy adhesive described herein in prefabricated component assembly, 3D printing, and lightweight porous aggregate reinforcement.

[0035] It is easy to understand that the epoxy adhesive described in this invention can be used for the assembly and connection of prefabricated components, especially in high-altitude areas. Under negative temperature conditions of -20℃, it can combine low-temperature construction, high strength at room temperature and excellent bonding performance. It is suitable for bonding, repair and assembly of prefabricated segments of wind power hybrid towers in cold winter.

[0036] Furthermore, the epoxy adhesive described in this invention, in addition to its use in assembling and connecting prefabricated components, can also be used for the rapid prototyping and repair of large-size, complex curved surface structures, and is particularly suitable for 3D printing of nonlinear irregular curved surface structures. Through the synergistic regulation of environmentally friendly reactive diluents, thixotropic agents, and a multi-stage high-filler system, the rheological properties and curing kinetics of the system are optimized, enabling the material to be rapidly molded in the extrusion state and possessing interlayer self-supporting capabilities.

[0037] Furthermore, the epoxy adhesive described in this invention can be used in combination with lightweight porous inorganic aggregates to construct a lightweight, high-strength structural material system. The lightweight porous inorganic aggregates include, but are not limited to, coral aggregates, expanded shale aggregates, and fly ash ceramsite aggregates, which can significantly reduce the water absorption rate of the aggregates and improve their compressive strength, thereby achieving a synergistic optimization of lightweight and high strength.

[0038] Compared with existing technologies, this invention has the following significant advantages: This invention provides an environmentally friendly epoxy adhesive that can cure at low temperatures, its preparation method, and its applications. This adhesive combines low-temperature workability, high strength at room temperature, excellent bonding performance, and environmentally friendly characteristics, making it suitable for bonding, repair, prefabricated segment assembly of wind power hybrid towers in cold winters, 3D printing of nonlinear irregular curved surfaces, and lightweight porous aggregate reinforcement. Specifically, this can be better understood from the following aspects:

[0039] (1) This invention achieves curing and crosslinking reaction at low temperature (-20℃) by introducing bio-based modified epoxy resin and bio-based phenolic amine curing agent. Among them, the bio-based modified epoxy resin utilizes its flexible chain segment structure to improve the molecular chain mobility under low temperature conditions, and the phenolic hydroxyl groups in the bio-based phenolic amine curing agent pre-activate the epoxy group through hydrogen bonding, improve the electrophilicity of the epoxy carbon atom, and reduce the reaction activation energy, promote the crosslinking reaction and form an initial cured network structure, thus achieving low-temperature workability. This overcomes the problems of traditional technology (-15℃) where the system viscosity increases significantly, the molecular chain mobility decreases, and the curing reaction rate slows down significantly at -20℃, which easily leads to insufficient crosslinking and significant deterioration of workability.

[0040] (2) After the system recovers from the low temperature environment to the room temperature, the multifunctional epoxy resin and the amine curing agent can continue to undergo post-curing reaction, which further densifies the cross-linking network and improves the overall strength of the system. The compressive strength can reach 120MPa, which further realizes the synergistic unity of low temperature workability and room temperature high strength performance.

[0041] (3) In the prior art, systems with high filler content (usually exceeding 60%) are prone to problems such as a sharp increase in system viscosity, loss of fluidity, and construction difficulties, making it difficult to simultaneously achieve high filler content and good processing performance. This invention, by introducing environmentally friendly reactive diluents, thixotropic agents, and a multi-stage particle size high filler system for synergistic regulation, can effectively avoid a sharp increase in system viscosity and improve the system's rheological properties even when the total filler content (including components B and C) is as high as about 80%, thus maintaining good mixing uniformity, workability, and anti-sagging properties. In the multi-stage particle size high filler system, small-diameter fillers can fill the pore areas between large-diameter particles, thereby increasing the overall packing density of the system and reducing internal porosity, forming a denser composite structure; high-strength, high-modulus inert fillers further form a rigid load-bearing skeleton in the epoxy resin curing network, which can effectively bear and disperse local stress under external loads, inhibit crack propagation, thereby improving the system's compressive strength, tensile strength, and dimensional stability, and reducing the risk of system curing shrinkage. Meanwhile, the introduction of a high proportion of fillers significantly reduces the amount of epoxy resin used, achieving material cost reduction and solid waste utilization while ensuring mechanical properties.

[0042] (4) This invention uses industrial solid waste or natural minerals as sources of high-strength fillers, and achieves high-proportion replacement and resource utilization of fillers while ensuring mechanical properties, thereby reducing dependence on high-purity synthetic raw materials, significantly reducing material costs, and improving the comprehensive utilization efficiency of solid waste.

[0043] (5) By introducing bio-based modified epoxy resin, bio-based phenolic amine curing agent and environmentally friendly reactive diluent, the present invention reduces the proportion of traditional petroleum-based raw materials used, thereby reducing the risk of volatile organic compound (VOC) release during the preparation and curing process and improving the environmental friendliness of the system.

[0044] (6) Given its good rheological controllability and interfacial bonding ability at low temperature of -20℃, the epoxy adhesive of the present invention can not only be used for rapid prototyping and repair of large-size and complex curved surface structures at room temperature, but is also particularly suitable for 3D printing construction of nonlinear irregular curved surface structures and construction of lightweight and high-strength structural material systems. It can also be used for 3D printing and lightweight and high-strength structure construction in the special environment of low temperature of -20℃. This enables rapid construction of nonlinear irregular curved surface structures and significantly reduces aggregate water absorption and improves its compressive strength, thereby achieving synergistic optimization of lightweight and high strength.

[0045] It should be understood that the implementation of any embodiment of the present invention does not mean that it will simultaneously possess or achieve multiple or all of the above-mentioned beneficial effects. Attached Figure Description

[0046] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0047] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0048] Figure 1 A schematic diagram of the preparation of an epoxy adhesive according to the present invention is shown, wherein (a) and (b) show different stages of morphology;

[0049] Figure 2 A schematic diagram of a specimen obtained by molding an epoxy adhesive according to the present invention is shown, wherein (a) shows a specimen for compressive strength test and (b) shows a specimen for tensile strength test;

[0050] Figure 3 The diagram shows the strength test results of an epoxy adhesive according to the present invention, wherein (a) shows the compressive strength test, (b) shows the tensile strength test, (c) shows the concrete-to-concrete compressive shear strength test, (d) shows the steel-to-steel tensile shear strength test, and (e) shows the steel-to-concrete tensile bond strength test.

[0051] Figure 4 The image shows a microscopic morphology of the tensile fracture surface of an epoxy adhesive according to the present invention.

[0052] Figure 5 This diagram illustrates an epoxy adhesive for 3D printing nonlinear irregular curved surface structures according to the present invention.

[0053] Figure 6 The diagram shows a comparison of the epoxy adhesive of the present invention before and after modification of lightweight porous coral aggregate, wherein (a) shows untreated lightweight coral aggregate, (b) shows lightweight coral aggregate after vacuum impregnation, and (c) shows the coated and reinforced coral aggregate and its cross-sectional view. Detailed Implementation

[0054] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0055] All raw materials used in the embodiments of this invention are commercially available products, and their specific specifications are described in the text. Unless otherwise stated, all parts are parts by weight.

[0056] Example 1:

[0057] The materials prepared in this embodiment consist of the following components: Component A: 10 parts TDE-85 multifunctional epoxy resin, 5 parts vanillin-based epoxy resin, 1.8 parts cashew phenol glycidyl ether, 0.4 parts epoxidized soybean oil, 0.6 parts silane coupling agent, 1.5 parts organobentonite, and 0.5 parts fumed silica. Component B: 3 parts polyamide 650 curing agent, 1.5 parts bio-based phenolamine curing agent, 0.5 parts 2,4,6-tris(dimethylaminomethyl)phenol, 5.5 parts 5-20μm corundum powder, 13.75 parts 10-50μm quartz powder, 19.25 parts 50-150μm basalt powder, 16.5 parts 100-300μm diabase powder, and 0.2 parts biomass carbon black. Component C: 6 parts surface-hydroxylated silica fume, 10 parts calcined activated metakaolin, and 4 parts acid-activated mineral powder. First, add components A and B to a vacuum stirrer and stir at 600-800 rpm for 10 minutes to ensure the system is fully and evenly dispersed and reacts to form a low-crosslinking prepolymer system. Then, slowly add component C to the mixture over a period of 2-5 minutes and continue stirring for 5 minutes to obtain the epoxy adhesive.

[0058] The preparation process and finished product of this embodiment are as follows: Figure 1 As shown, Figure 1 The color and state of the prepared adhesive are shown. The prepared epoxy adhesive was further molded into specimens for testing compressive and tensile strength according to the requirements of "Epoxy Adhesives for Precast Concrete Segment Assembly" (GB / T 44543-2024), such as... Figure 2 As shown, the mechanical properties, adhesive properties, and workability were tested after curing at room temperature (25℃) or -20℃. Figure 3 As shown in the figure. The test results are shown in Table 1.

[0059] Table 1. Results of Adhesive Performance Tests in Example 1

[0060]

[0061] As shown in Table 1 above, the epoxy adhesive of this embodiment achieves a compressive strength of 120 MPa and a tensile strength of 41.9 MPa after 7 days of curing at room temperature, fully meeting national standards. After curing at -20℃ for 7 days and then at room temperature for 7 days, the compressive strength increased from 83.7 MPa to 110.5 MPa, and the tensile strength increased from 30.9 MPa to 38.6 MPa, both showing significant improvements. This is because the adhesive prepared in this invention introduces bio-based modified epoxy resin and bio-based phenolic amine curing agent to achieve a curing and cross-linking reaction at low temperature (-20℃). After the ambient temperature returns to room temperature, a post-curing reaction continues between the multifunctional epoxy resin and the amine curing agent, further densifying the cross-linking network and improving the overall strength of the system, achieving a synergistic unity of low-temperature workability and high-strength performance at room temperature. Meanwhile, as... Figure 4 As shown, the tensile fracture surface of the adhesive of the present invention exhibits a relatively rough microstructure. No obvious large-sized pores or filler detachment were observed in the fracture surface, indicating that a relatively dense cross-linked network structure has been formed inside the system. The concrete-to-concrete compressive shear strength, steel-to-steel tensile shear strength, and steel-to-concrete tensile bond strength of the adhesive all meet the national standard requirements under different environmental conditions, indicating that the adhesive can form a stable interfacial bonding layer at the interface of different substrates and has good interfacial bonding ability. At the same time, the system in this embodiment has an application time of more than 20 minutes at both 25℃ and -20℃ and has an anti-sagging property of 10-15mm, indicating that the adhesive still has good rheological controllability and workability under high filler conditions.

[0062] Example 2:

[0063] The materials prepared in this embodiment consist of the following components: Component A: 6 parts TDE-85 multifunctional epoxy resin, 6 parts vanillin-based epoxy resin, 1.2 parts cashew phenol glycidyl ether, 0.4 parts epoxidized soybean oil, 0.3 parts silane coupling agent, 1.0 part organobentonite, and 0.5 parts fumed silica. Component B: 5 parts polyamide 650 curing agent, 2.7 parts bio-based phenolamine curing agent, 1.5 parts 2,4,6-tris(dimethylaminomethyl)phenol, 5.5 parts 5-20μm corundum powder, 13.75 parts 10-50μm quartz powder, 19.25 parts 50-150μm basalt powder, 16.5 parts 100-300μm diabase powder, and 0.4 parts biomass carbon black. Component C: 6 parts surface-hydroxylated silica fume, 10 parts calcined activated metakaolin, and 4 parts acid-activated mineral powder. First, add components A and B to a vacuum stirrer and stir at 600-800 rpm for 10 minutes to ensure the system is fully and evenly dispersed and reacts to form a low-crosslinking prepolymer system. Then, slowly add component C to the mixture over a period of 2-5 minutes and continue stirring for 5 minutes to obtain the epoxy adhesive.

[0064] Using the same method, the epoxy adhesive of this embodiment was molded and cured according to the requirements of "Epoxy Adhesives for Precast Concrete Segment Assembly" (GB / T 44543-2024). It was cured at room temperature (25℃) or -20℃, and its mechanical properties, bonding properties and construction properties were tested. The test results are shown in Table 2.

[0065] Table 2. Results of Adhesive Performance Tests in Example 2

[0066]

[0067] As shown in Table 2 above, the epoxy adhesive of this embodiment exhibits good mechanical properties, interfacial adhesion properties, and workability under both room temperature and -20℃ conditions. After curing at 25℃ for 7 days, the compressive strength reaches 118.8 MPa, and the tensile strength reaches 39.7 MPa. Even after curing at -20℃ for 7 days, it still achieves effective curing, and upon transitioning to room temperature curing, the compressive strength increases from 81.3 MPa to 109.7 MPa, and the tensile strength increases from 32.4 MPa to 35.6 MPa. This demonstrates that the system of this invention possesses good low-temperature workability and high strength at room temperature. Compared to existing technologies (-15℃), this invention achieves effective construction and curing at -20℃. Although the difference is only 5℃, the transition from -15℃ to -20℃ represents a critical temperature range where the system viscosity increases significantly, molecular chain mobility decreases, and the curing reaction rate slows down considerably. This can easily lead to insufficient cross-linking and deterioration of construction performance. This invention can achieve stable curing at -20℃, overcoming the significantly increased difficulty of traditional technologies in this critical temperature range. Furthermore, the system meets national standards for concrete-to-concrete compressive shear strength, steel-to-steel tensile shear strength, and steel-to-concrete tensile bond strength under different environmental conditions, indicating good interfacial bonding performance. The adhesive has an application time of over 20 minutes at both 25℃ and -20℃, and its anti-sagging performance is 10-15mm, demonstrating good rheological controllability and workability even under high filler conditions.

[0068] Comparative Example 1:

[0069] The materials prepared in this comparative example consist of the following components: Component A: 15 parts TDE-85 multifunctional epoxy resin, 1.8 parts cashew phenol glycidyl ether, 0.4 parts epoxidized soybean oil, 0.6 parts silane coupling agent, 1.5 parts organobentonite, and 0.5 parts fumed silica. Component B: 4.5 parts polyamide 650 curing agent, 0.5 parts 2,4,6-tris(dimethylaminomethyl)phenol, 5.5 parts 5-20μm corundum powder, 13.75 parts 10-50μm quartz powder, 19.25 parts 50-150μm basalt powder, 16.5 parts 100-300μm diabase powder, and 0.2 parts biomass carbon black. Component C: 6 parts surface-hydroxylated silica fume, 10 parts calcined activated metakaolin, and 4 parts acid-activated mineral powder. First, add components A and B to a vacuum stirrer and stir at 600-800 rpm for 10 minutes to ensure the system is fully and evenly dispersed and reacts to form a low-crosslinking prepolymer system. Then, slowly add component C to the mixture over a period of 2-5 minutes and continue stirring for 5 minutes to obtain the epoxy adhesive.

[0070] The difference between this comparative example and Example 1 is that no bio-based modified epoxy resin and bio-based phenolic amine curing agent were added.

[0071] The epoxy adhesive of this comparative example was molded and cured according to the requirements of "Epoxy Adhesives for Precast Concrete Segment Assembly" (GB / T 44543-2024). It was cured at room temperature (25℃) or -20℃. Its mechanical properties, bonding properties and construction properties were tested. The test results are shown in Table 3.

[0072] Table 3. Test Results of Adhesive Performance in Comparative Example 1

[0073]

[0074] Note: Since Comparative Example 1 could not be cured at -20℃, its performance could not be measured, so relevant data were not listed.

[0075] Comparative Example 2:

[0076] The materials prepared in this comparative example consist of the following components: Component A: 15 parts vanillin-based epoxy resin, 1.8 parts cashew phenol glycidyl ether, 0.4 parts epoxidized soybean oil, 0.6 parts silane coupling agent, 1.5 parts organobentonite, and 0.5 parts fumed silica. Component B: 4.5 parts bio-based phenolamine curing agent, 0.5 parts 2,4,6-tris(dimethylaminomethyl)phenol, 5.5 parts 5-20μm corundum powder, 13.75 parts 10-50μm quartz powder, 19.25 parts 50-150μm basalt powder, 16.5 parts 100-300μm diabase powder, and 0.2 parts biomass carbon black. Component C: 6 parts surface-hydroxylated silica fume, 10 parts calcined activated metakaolin, and 4 parts acid-activated mineral powder. First, add components A and B to a vacuum stirrer and stir at 600-800 rpm for 10 minutes to ensure the system is fully and evenly dispersed and reacts to form a low-crosslinking prepolymer system. Then, slowly add component C to the mixture over a period of 2-5 minutes and continue stirring for 5 minutes to obtain the epoxy adhesive.

[0077] The difference between this comparative example and Example 1 is that no multifunctional epoxy resin and amine curing agent were added.

[0078] The epoxy adhesive of this comparative example was molded and cured according to the requirements of "Epoxy Adhesives for Precast Concrete Segment Assembly" (GB / T 44543-2024). It was cured at room temperature (25℃) or -20℃. Its mechanical properties, adhesive properties and construction properties were tested. The test results are shown in Table 4.

[0079] Table 4. Test results of adhesive performance in Comparative Example 2

[0080]

[0081] Comparative Example 3:

[0082] The materials prepared in this embodiment consist of the following components: Component A: 10 parts TDE-85 multifunctional epoxy resin, 5 parts vanillin-based epoxy resin, 1.8 parts cashew phenol glycidyl ether, 0.4 parts epoxidized soybean oil, 0.6 parts silane coupling agent, 1.5 parts organobentonite, and 0.5 parts fumed silica. Component B: 3 parts polyamide 650 curing agent, 1.5 parts bio-based phenolamine curing agent, 0.5 parts 2,4,6-tris(dimethylaminomethyl)phenol, 55 parts 10-50μm mineral powder, and 0.2 parts biomass carbon black. Component C: 6 parts surface-hydroxylated silica fume, 10 parts calcined activated metakaolin, and 4 parts acid-activated mineral powder. First, add components A and B to a vacuum stirrer and stir at 600-800 rpm for 10 minutes to ensure that the system is fully and evenly dispersed and reacts to form a low crosslinking prepolymer system. Then, slowly add component C to the mixture over a period of 2-5 minutes and continue stirring for 5 minutes to obtain the epoxy adhesive of Comparative Example 3.

[0083] The difference between this comparative example and Example 1 is that no high-strength, high-modulus inert filler was added.

[0084] The epoxy adhesive of this comparative example was molded and cured according to the requirements of "Epoxy Adhesives for Precast Concrete Segment Assembly" (GB / T 44543-2024). It was cured at room temperature (25℃) or -20℃. Its mechanical properties, bonding properties and construction properties were tested. The test results are shown in Table 5.

[0085] Table 5. Test results of adhesive performance in Comparative Example 3

[0086]

[0087] To verify the performance of the epoxy adhesive of the present invention, the mechanical properties of the epoxy adhesives obtained in Examples 1 and 2 were compared with those in Comparative Examples 1, 2 and 3, as shown in Table 6.

[0088] Table 6 Comparison of Mechanical Properties of Adhesives

[0089]

[0090] As shown in Table 6, in Comparative Example 1, due to the lack of bio-based modified epoxy resin and bio-based phenolic amine curing agent, the compressive and tensile strengths of the system could not be effectively measured under both "-20℃ curing for 7 days" and "-20℃ curing for 7 days + 25℃ curing for 7 days" conditions, indicating that the system could not achieve effective curing at -20℃. In Comparative Example 2, due to the lack of multifunctional epoxy resin and amine curing agent, although the system could be cured at -20℃, its compressive and tensile strengths after curing were significantly lower than those of Example 1. In Comparative Example 3, due to the absence of high-strength, high-modulus inert filler, the compressive and tensile strengths of the system decreased significantly.

[0091] In comparison, the epoxy adhesive proposed in this invention (taking Example 1 as an example) can achieve a compressive strength of 120 MPa after curing at room temperature for 7 days. It can be completely cured at -20℃ and has a strength of 83.7 MPa. After undergoing "curing at -20℃ for 7 days + curing at 25℃ for 7 days", its compressive strength is further improved to 110.5 MPa. This indicates that the system can continue to undergo post-curing reaction after returning to room temperature, which further densifies the crosslinking network and improves the overall mechanical properties of the material.

[0092] In addition, the system still has a 25-minute application time at -20℃, indicating that it still has good workability in negative temperature environments and can meet the needs of on-site construction.

[0093] Example 3:

[0094] The materials prepared in this embodiment consist of the following components: Component A: 15 parts TDE-85 multifunctional epoxy resin, 3 parts vanillin-based epoxy resin, 0.5 parts cashew phenol glycidyl ether, 0.4 parts epoxidized soybean oil, 0.2 parts silane coupling agent, 0.3 parts organobentonite, and 1.5 parts fumed silica. Component B: 2 parts polyamide 650 curing agent, 3.5 parts bio-based phenolamine curing agent, 2 parts 2,4,6-tris(dimethylaminomethyl)phenol, 5.5 parts 5-20μm corundum powder, 13.75 parts 10-50μm quartz powder, 19.25 parts 50-150μm basalt powder, 16.5 parts 100-300μm diabase powder, and 0.2 parts biomass carbon black. Component C: 6 parts surface-hydroxylated silica fume, 10 parts calcined activated metakaolin, and 4 parts acid-activated mineral powder. First, add components A and B to a vacuum stirrer and stir at 600-800 rpm for 10 minutes to ensure the system is fully and uniformly dispersed and reacts to form a low-crosslinking prepolymer system. Then, slowly add component C to the mixture over 2-5 minutes and continue stirring for 5 minutes to obtain a printing paste system with thixotropic properties. The resulting printing paste exhibits high yield stress under static conditions, resisting gravity collapse, and thins under shear, thus possessing both extrusion flowability and molding retention capabilities.

[0095] Under sub-zero temperatures of -20℃, an extrusion 3D printing system was used to deposit materials layer by layer, with the printing path generated based on a 3D surface model. This successfully printed a nonlinear, irregularly shaped surface structure, such as... Figure 5 As shown, during the printing process, the material maintained structural stability after extrusion without significant collapse, and the interlayer bonding was good. This demonstrates that the adhesive system proposed in this invention can not only be used for structural bonding, but also for extrusion 3D printing by controlling the system's rheological properties. This indicates that the adhesive still has good rheological controllability, shape retention, and adaptability to printing complex structures under low-temperature conditions, which is obviously something that traditional adhesives cannot achieve.

[0096] Example 4:

[0097] First, lightweight porous coral aggregate was selected and screened to obtain aggregate with a particle size of 5–20 mm. This aggregate was then dried to constant weight at 60–105℃ to remove free water from the pores and adsorbed water from the surface. Subsequently, the pretreated coral aggregate was added to the epoxy adhesive system of Example 1 at -20℃ and vacuum impregnated for 10–30 minutes, allowing the adhesive to penetrate the aggregate and connect the pores under negative pressure. After impregnation, the aggregate was removed and allowed to stand for 1–3 minutes to remove excess adhesive. Then, the outer surface of the aggregate was uniformly coated using a roller coating or stirring method to form a continuous adhesive layer. Finally, the aggregate was placed in a 110℃ oven and heated for 15 minutes to allow the adhesive to initially cure, resulting in the reinforced coral aggregate. Figure 6 As shown.

[0098] Test results show that the lightweight porous coral aggregate treated with the system of this invention exhibits a 30%–80% increase in compressive strength and a 20%–60% decrease in water absorption compared to untreated aggregate. This indicates that the epoxy adhesive of this invention can effectively penetrate the internal pores of the lightweight porous aggregate and form a dense coating layer on the aggregate surface, thereby improving the overall structural density and mechanical properties of the aggregate while reducing its water absorption. This further verifies that the adhesive of this invention possesses good rheological controllability, interfacial bonding ability, and high-strength structural reinforcement characteristics under low-temperature conditions.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An adhesive, characterized in that, It consists of component A, component B and component C, wherein: Component A comprises the following components in parts by weight: 5-15 parts of multifunctional epoxy resin; 3-10 parts of bio-based modified epoxy resin; wherein the bio-based modified epoxy resin is vanillin-based epoxy resin; 0.5-2.5 parts of environmentally friendly reactive diluent; 0.2-0.6 parts of silane coupling agent; Thixotropic agent 0.6-2.4 parts; Component B comprises the following components in parts by weight: 2-6 parts of amine curing agent; wherein the amine curing agent is any one or more of triethylenetetramine, tetraethylenepentamine, polyetheramine, phenolic amine curing agent, and polyamide; 1.5-4 parts of bio-based phenolic amine curing agent; the bio-based phenolic amine curing agent is prepared by cashew phenol, formaldehyde and aliphatic polyamine under Mannich condensation reaction conditions, wherein the aliphatic polyamine includes diethylenetriamine and triethylenetetramine; Accelerator 0.5-2 parts; 40-60 parts of high-strength, high-modulus inert filler; the high-strength, high-modulus inert filler is selected from any one or a combination of corundum powder, quartz powder, basalt powder, diabase powder, and silicon carbide. 0.2-0.4 parts of environmentally friendly pigment; Component C comprises the following components in parts by weight: 10-30 parts of surface-active filler; Components A, B, and C are packaged separately and mixed in a weight ratio of 1:3:1 during application.

2. The adhesive according to claim 1, characterized in that, The multifunctional epoxy resin is any one or more of pentaerythritol tetraglycidyl ether, 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester, phenolic epoxy resin, and tetraglycidyl-4,4'-diaminodiphenylmethane.

3. The adhesive according to claim 1, characterized in that, The bio-based modified epoxy resin was prepared by the following method: (1) Add vanillin to the reaction vessel, add excess epichlorohydrin at a speed of 400-800 rpm, and carry out etherification reaction at 60-90℃ for 2-5 h to generate β-chlorohydrin ether intermediate; (2) NaOH solution is slowly added dropwise at 40-60℃ to carry out an alkaline ring-closing reaction, causing the chlorohydrin structure to undergo a dehydrochlorination reaction to generate an epoxy group structure; (3) After the reaction is completed, the mixture is allowed to stand and separate into layers. It is washed with water until neutral to remove sodium chloride, and then the unreacted epichlorohydrin is removed by vacuum distillation to obtain high-purity vanillin-based epoxy resin.

4. The adhesive according to claim 1, characterized in that, The environmentally friendly reactive diluent is a compound system of cashew phenol glycidyl ether and epoxidized soybean oil, with epoxidized soybean oil accounting for 5%-20% of the total diluent.

5. The adhesive according to claim 1, characterized in that, The silane coupling agent is KH560.

6. The adhesive according to claim 1, characterized in that, The thixotropic agent is a compound system of organic bentonite and fumed silica.

7. The adhesive according to claim 1, characterized in that, The preparation method under the Mannich condensation reaction conditions includes: (1) Diethylenetriamine and triethylenetetramine are mixed in a reactor at a set mass ratio of 3:2 and premixed under a nitrogen atmosphere to obtain an amine mixture. The premixing temperature is controlled at 25-40℃ and the stirring rate is 300-600rpm. (2) While stirring continuously, slowly add the formaldehyde aqueous solution to the amine mixture, and control the reaction temperature at 40-60℃; (3) Slowly add cashew phenol, raise the temperature to 80-110℃, and react for 3-6 hours under a nitrogen atmosphere; (4) After the reaction is complete, the temperature is raised to 100-110℃ for dehydration under reduced pressure to remove unreacted formaldehyde, water and low molecular weight amines, and finally a dark to brownish viscous liquid is obtained.

8. The adhesive according to claim 1, characterized in that, The accelerator is any one or a combination of 2,4,6-tris(dimethylaminomethyl)phenol and 2-methylimidazole.

9. The adhesive according to claim 1, characterized in that, The high-strength, high-modulus inert filler is made from industrial solid waste or natural rock through crushing, ball milling, and screening.

10. The adhesive according to claim 1, characterized in that, The environmentally friendly pigment is biomass carbon black, which is produced by pyrolysis and carbonization of straw, sawdust, or fruit shells at 500-700℃ under an inert atmosphere.

11. The adhesive according to claim 1, characterized in that, The surface-active filler is obtained by acid activation or calcination activation treatment of silica fume, metakaolin, and mineral powder.

12. A method for preparing an adhesive according to any one of claims 1 to 11, characterized in that, include: Add components A and B to a vacuum stirrer and stir at 600-800 rpm for 10-20 minutes to ensure that the system is fully and uniformly dispersed and reacts to form a low crosslinking prepolymer system. Then slowly add component C to the mixture over a period of 2-5 minutes, and continue stirring for 5-10 minutes to obtain the adhesive.

13. The application of an adhesive according to any one of claims 1 to 11 in prefabricated segmental assembly, 3D printing, and lightweight porous aggregate reinforcement.

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