A foldable and expandable modular prefabricated building product

Abstract

This invention relates to a foldable and expandable modular prefabricated building product, comprising multiple grouped building module units. Adjacent building module units are foldably connected by flexible connecting strips made of a highly elastic resin substrate, providing flexible folding and unfolding capabilities. The expansion connection surface of each building module unit has a multi-layer functional coating structure, sequentially including a substrate bonding layer, a deformation buffer layer, a waterproof sealing layer, and a stress transfer layer. The substrate bonding layer ensures a strong bond between the functional coating and the module unit; the deformation buffer layer disperses external forces through controllable deformation, avoiding stress concentration and improving the adaptability of the connection interface; the waterproof sealing layer forms a dense structure through molecular chain rearrangement, achieving excellent waterproof performance under prestress; the stress transfer layer is used to transfer and uniformly distribute prestress, thereby enhancing the structural stability of the expansion connection. The modular building product provided by this invention meets the comprehensive needs of convenient transportation, rapid assembly, and reliable connection.

Description

Technical Field

[0001] This invention relates to the field of prefabricated building technology, and in particular to a foldable and expandable modular prefabricated building product. Background Technology

[0002] In existing technologies, modular prefabricated building products have been widely used in the construction industry, offering advantages such as rapid installation, convenient transportation, and reusability. These products are typically based on standardized modular units, with multiple modules combined into a whole through mechanical connections, welding, or rigid connections to meet the needs of various construction scenarios. The application of modular buildings covers multiple fields, including temporary buildings, residential buildings, and commercial facilities.

[0003] While existing modular building products meet usage requirements to some extent, many problems remain to be solved. First, traditional connection methods struggle to balance flexibility and reliability. Especially when modules are folded, expanded, or used frequently, rigid connections are prone to damage or fatigue failure due to stress concentration, while mechanical connections may increase construction difficulty and cost due to complex structures. Second, the waterproofing and environmental adaptability of module connection interface materials are weak. Under prolonged exposure to high humidity, extreme temperatures, or external loads, sealing performance easily deteriorates, affecting the overall structural durability and safety. Furthermore, existing products exhibit uneven stress distribution during connection and lack effective stress buffering designs, further limiting the expandability and applicability of modular buildings and impacting their reliability in harsh environments.

[0004] Therefore, it is necessary to develop an improved modular prefabricated building product to overcome the aforementioned problems in the existing technology. Summary of the Invention

[0005] This application provides a foldable and expandable modular prefabricated building product to achieve flexible folding and expansion of module units, thereby improving transportation and installation efficiency.

[0006] This application provides a foldable and expandable modular prefabricated building product, comprising multiple groups of building module units, wherein each group of building module units includes at least two building module units, and adjacent building module units are foldably connected by a flexible connecting strip, the flexible connecting strip being made of a highly elastic resin substrate;

[0007] Each building module unit's extended connection surface includes a multi-layer functional coating structure, which is used to realize the extended connection between the first group of building module units and the second group of building module units; the multi-layer functional coating structure includes, from the inside to the outside, a substrate bonding layer, a deformation buffer layer, a waterproof sealing layer, and a stress transmission layer.

[0008] The substrate bonding layer is used to achieve a firm bond between the functional coating and the building module unit; the deformation buffer layer is used to generate controllable deformation when the first group of building module units and the second group of building module units are subjected to external forces, so as to avoid stress concentration and improve the adaptability of the connection interface; the waterproof sealing layer is used to form a dense waterproof structure through molecular chain rearrangement under the action of prestress, so as to ensure the waterproof performance of the extended connection; the stress transfer layer is used to transfer and uniformly distribute prestress between the first group of building module units and the second group of building module units, so as to ensure the structural stability of the extended connection.

[0009] Furthermore, the high-elasticity resin substrate of the flexible connecting strip includes a reinforcing fiber material selected from aramid fiber, carbon fiber, or glass fiber. The reinforcing fiber material is embedded along the longitudinal direction of the flexible connecting strip to form a multi-layer composite structure. The thickness of the flexible connecting strip ranges from 0.5 mm to 5 mm, and the content of the reinforcing fiber accounts for 5% to 25% of the total weight of the connecting strip. The surface of the flexible connecting strip is coated with a UV-resistant coating to improve its weather resistance under long-term exposure to sunlight.

[0010] Furthermore, the substrate bonding layer of the multilayer functional coating structure includes nanoparticle filler material to enhance the adhesion between the coating and the surface of the building module unit; the nanoparticles are selected from one or more of silicon oxide, titanium oxide, or zinc oxide, with an average particle size of 10 to 50 nanometers, and are distributed in the substrate bonding layer in a uniform manner; the coating thickness of the substrate bonding layer is 50 to 200 micrometers, and it is bonded to the surface of the building module unit substrate through plasma treatment or spraying technology, thereby ensuring that the adhesion performance of the functional coating is not affected under high humidity and high temperature difference conditions.

[0011] Furthermore, the deformation buffer layer comprises a polymer-based material with shape memory function, which is used to generate adaptive deformation when the ambient temperature changes, so as to further improve the connection adaptability between module units; the thickness of the deformation buffer layer ranges from 0.1 mm to 1 mm, and its impact resistance and deformation recovery performance are further optimized by embedding micro-nano-level elastic particles or porous network structures.

[0012] Furthermore, the waterproof sealing layer adopts a multi-component interpenetrating network structure, formed by the cross-linking reaction of polyurethane, silicone rubber, and acrylate materials. The multi-component interpenetrating network structure can quickly adjust the molecular arrangement when subjected to external pressure or stress through a dynamic rearrangement mechanism of molecular chains, thereby achieving a dynamic self-healing waterproof function. The thickness of the waterproof sealing layer ranges from 0.2 mm to 2 mm, and its surface has a nanoscale hydrophobic coating with a contact angle greater than 120 degrees, thereby improving the waterproof performance.

[0013] Furthermore, the stress transfer layer includes a stress-guiding microstructure, which is a regularly arranged array of hexagonal grooves, wherein the depth of the hexagonal grooves is 50 to 200 micrometers and the width is 100 to 500 micrometers; the arrangement direction of the hexagonal groove array is consistent with the prestress transfer direction, so as to realize multi-dimensional stress transfer; the material of the stress transfer layer is an anisotropic polymer composite material, and the elastic modulus in the prestress transfer direction is 2 to 5 times that in the vertical direction.

[0014] Furthermore, the building module unit adopts a composite wall structure, including an outer high-strength frame and an inner lightweight infill; wherein the outer high-strength frame is made of carbon fiber reinforced epoxy resin with a frame thickness of 30 to 50 mm; and the inner lightweight infill is made of modified ceramsite concrete.

[0015] Furthermore, the flexible connecting strip is equipped with stress sensing elements, which are made of a conductive polymer doped with graphene. The resistance value changes when the connecting strip deforms. The stress sensing elements are evenly arranged along the length of the connecting strip with a spacing of 50 to 100 mm, and are used to monitor the stress distribution during the folding process in real time.

[0016] Furthermore, a barrier coating is provided between the deformation buffer layer and the waterproof sealing layer in the multilayer functional coating structure, and the thickness of the barrier coating is 10 to 50 micrometers; the barrier coating is made of a chemically resistant fluorocarbon polymer material.

[0017] Furthermore, the multilayer functional coating structure exhibits phase change characteristics under pressure, specifically including: microcapsule structures distributed in the deformation buffer layer, the shell of the microcapsule structure being made of polymethyl methacrylate, and the interior being filled with a temperature-sensitive phase change material and a pressure-responsive catalyst; when the extended connection surfaces of two module units come into contact under a predetermined pressure, some microcapsules rupture, the phase change material and the catalyst mix and undergo a chemical reaction, generating a novel polymer with a cross-linked network structure, the novel polymer penetrating into the microstructure of the stress transfer layer to form a synergistic enhancement effect.

[0018] The beneficial effects of the technical solution provided in this application include:

[0019] (1) This invention connects adjacent modular units with flexible connecting strips, enabling modular building products to be foldable and expandable, significantly reducing the space occupied during transportation, lowering transportation costs, and simplifying on-site assembly operations, thereby improving construction efficiency. (2) By setting up a multi-layer functional coating structure, the deformation buffer layer can effectively alleviate stress concentration caused by external forces, reduce the risk of damage to the connection interface, and improve the adaptability of the modular units in complex environments and the reliability of long-term use. (3) The waterproof sealing layer forms a dense waterproof structure through molecular chain rearrangement, ensuring excellent waterproof performance at the expansion connection, effectively avoiding the impact of rainwater infiltration or other humid environments on the overall performance of the building, and is suitable for building needs under harsh environmental conditions. (4) The stress transfer layer can evenly distribute prestress between modular units, reducing connection failures caused by uneven local stress, ensuring the overall structural stability of the expansion connection, and improving the reliability of the building under high loads or dynamic loads. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a foldable and expandable modular prefabricated building product provided in the first embodiment of this application.

[0021] Figure 2 This is a folding diagram of a foldable and expandable modular prefabricated building product provided in the first embodiment of this application.

[0022] Figure 3 This is an extended schematic diagram of a foldable and expandable modular prefabricated building product provided in the first embodiment of this application. Detailed Implementation

[0023] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific implementations disclosed below.

[0024] The first embodiment of this application provides a foldable and expandable modular prefabricated building product. Please refer to... Figure 1 This figure is a schematic diagram of the first embodiment of this application. The following is in conjunction with... Figure 1 The first embodiment of this application provides a foldable and expandable modular prefabricated building product.

[0025] Figure 1 A set of 100 building module units is provided. Figure 2 Provided Figure 1 The provided diagram illustrates the folding of the grouped building module units. Figure 3Extended schematic diagrams of multiple grouped building module units 100, 200, and 300 are provided. The grouped building module units include building module units 101, 102, and 103. Adjacent building module units 101 and 102 are foldably connected via flexible connecting strips 110, and adjacent building module units 102 and 103 are foldably connected via flexible connecting strips 111. It should be noted that... Figure 1 The grouped building module units can also be expanded to include more building module units and flexible connecting strips.

[0026] The front facade of building module unit 101 has an extended connection surface 120. Similarly, the front facade of building module unit 101 has an extended connection surface 121, and the front facade of building module unit 103 has an extended connection surface 122. These extended connection surfaces allow for the splicing of different groups of building module units. It should be noted that the rear facades of building module units 101-103 can also have corresponding extended connection surfaces.

[0027] The foldable and expandable modular prefabricated building product provided in this embodiment is characterized by comprising multiple groups of building module units, each group including at least two adjacent building module units, which are foldably connected by flexible connecting strips. The flexible connecting strips are made of highly elastic resin substrate, which can freely switch between folded and unfolded states while ensuring the mechanical properties and durability of the connection parts.

[0028] like Figure 1 As shown, the grouped building module units include building module units 101, 102, and 103. Adjacent module units are connected by flexible connecting strips 110 and 111. The core function of these flexible connecting strips is to provide flexible connections between module units, allowing them to be compactly folded during transportation or storage and quickly unfolded into a complete structure during on-site construction. The flexible connecting strips are made of a highly elastic resin substrate, preferably polyurethane, silicone, or thermoplastic elastomers. These materials have excellent fatigue resistance, weather resistance, and aging resistance, and can maintain stable performance after repeated folding and long-term use. The design of the connecting strips must ensure sufficient strength and resilience under stress, while avoiding localized cracking or breakage due to concentrated external forces.

[0029] The front and rear facades of the building module units are equipped with extended connection surfaces, such as 120, 121, and 122. These extended connection surfaces are multi-layered functional coating structures, which, from the inside out, include a substrate bonding layer, a deformation buffer layer, a waterproof sealing layer, and a stress transfer layer. Each layer is carefully designed and optimized to meet different functional requirements and ensure the reliability of the overall connection.

[0030] The substrate bonding layer, located at the innermost layer of the extended connection surface, serves to firmly adhere the functional coating to the substrate surface of the building module unit. The selection of the substrate bonding layer should be optimized based on the substrate type of the module unit. For example, if the substrate is concrete, a modified epoxy resin adhesive can be used; if the substrate is metal, a polyurethane resin or silane-modified polymer with excellent adhesion can be used. The application of the bonding layer must ensure uniform coverage of the entire extended connection surface, while avoiding construction defects that could reduce bond strength.

[0031] As an external functional layer of the matrix bonding layer, the deformation buffer layer's main function is to disperse external forces and generate controllable deformation at the connection interface, thereby reducing stress concentration and improving the durability and adaptability of the connection. The buffer layer material is preferably an elastic polymer with low elastic modulus and good toughness, such as a polymer composite material embedded with micron-sized rubber particles, or a polyurethane material with shape memory properties. These materials can buffer impact loads through their own deformation under stress and quickly return to their original shape after the external force disappears.

[0032] The waterproof sealing layer is the third layer of the functional coating. Its core function is to form a dense waterproof structure at the interface, effectively preventing water penetration. This layer achieves enhanced sealing performance through a molecular chain rearrangement mechanism under prestress. Materials such as silicone, polyurethane, or butyl rubber with reversible cross-linking properties can be used. These materials can rearrange their molecular structure to form a continuous waterproof membrane when compressed by external forces. During construction, care must be taken to prevent insufficient thickness or uneven coating to avoid a decrease in sealing performance.

[0033] As the outermost functional coating, the stress transfer layer's role is to transfer and uniformly distribute prestress between modular units, ensuring the mechanical stability of the entire extended connection. The stress transfer layer is typically made of high-strength fiber-reinforced composite materials or metal films, such as carbon fiber composites or stainless steel films. These materials maintain their stiffness and strength under heavy loads, while optimized design prevents local instability or failure at the connection interface.

[0034] The design of flexible connecting strips and multi-layer functional coatings needs to work in tandem to achieve efficient folding, rapid splicing, and stable connection between modular units. During construction, precise positioning ensures the alignment of the flexible connecting strips with the extended connection surfaces, while strict control over the construction process of the multi-layer functional coatings, including coating thickness, curing time, and interface adhesion, ensures the full realization of the function of each layer.

[0035] Furthermore, the high-elasticity resin substrate of the flexible connecting strip includes a reinforcing fiber material selected from aramid fiber, carbon fiber, or glass fiber. The reinforcing fiber material is embedded along the longitudinal direction of the flexible connecting strip to form a multi-layer composite structure. The thickness of the flexible connecting strip ranges from 0.5 mm to 5 mm, and the content of the reinforcing fiber accounts for 5% to 25% of the total weight of the connecting strip. The surface of the flexible connecting strip is coated with a UV-resistant coating to improve its weather resistance under long-term exposure to sunlight.

[0036] The flexible connecting strip provided in this embodiment combines flexibility and high strength by incorporating reinforcing fiber materials into a highly elastic resin substrate. It is suitable for connecting adjacent building module units to meet the performance requirements of modular prefabricated buildings during repeated folding, unfolding, and long-term use. The reinforcing fiber material is preferably one of aramid fiber, carbon fiber, or glass fiber, which are widely used due to their excellent mechanical properties and durability. Aramid fiber has extremely high tensile strength and impact resistance, carbon fiber is known for its lightweight, high strength, and good fatigue resistance, while glass fiber offers high cost-effectiveness and excellent chemical corrosion resistance.

[0037] Reinforcing fibers are embedded along the longitudinal direction of the flexible connecting strip to form a multi-layered composite structure. This design significantly improves the tensile strength and fatigue resistance of the connecting strip while retaining the required flexibility of the resin substrate. Specifically, the reinforcing fibers can be embedded into the resin substrate through continuous laying or in the form of a fabric, such as by pultrusion, thermoforming, or spray coating processes, to ensure uniform fusion of the fibers and the substrate, forming a stable multi-layered structure. In such a composite structure, the resin substrate primarily provides flexibility and weather resistance, while the reinforcing fibers enhance tensile, tear, and bending resistance.

[0038] The flexible connecting strip is designed with a thickness ranging from 0.5mm to 5mm to balance strength and flexibility. The specific thickness can be adjusted based on the actual load requirements of the building module unit. For example, for lighter building modules, a thickness close to 0.5mm can be used to improve folding flexibility; while for modules bearing higher loads, a thickness close to 5mm is recommended to ensure that they do not break or permanently deform during unfolding and under stress. The content of reinforcing fibers is controlled between 5% and 25% of the total weight of the connecting strip. This fiber ratio provides sufficient mechanical properties without excessively affecting the flexibility of the resin substrate and molding process. For example, when the flexible connecting strip is used to connect high-load modules, a reinforcing fiber content of up to 25% can be selected; while for medium- and low-load applications, a fiber content of 5%-10% can be selected to reduce costs.

[0039] To ensure the performance stability of the flexible connecting strip under long-term exposure to sunlight or harsh environmental conditions, its surface is coated with a UV-resistant coating. The main function of this coating is to prevent UV degradation of the resin substrate while improving its weather resistance and anti-aging properties. The preferred coating materials are polyurethane coatings, fluorocarbon coatings, or silicone coatings with added UV absorbers, which offer high light stability and strong adhesion. These materials maintain a long service life even under high UV environments. The coating process can employ spraying, roller coating, or dip coating, with the coating thickness controlled between 10 and 50 micrometers to ensure effective UV shielding while avoiding the negative impact of excessively thick coatings on the flexible connecting strip's bending performance. For example, a thicker coating design can be used when the flexible connecting strip is applied in high-altitude or high-UV-exposed environments; while a thinner coating can be used for indoor applications to reduce manufacturing costs.

[0040] Through the implementation of the aforementioned reinforcing fibers, multi-layer composite structure, and UV-resistant coating, the flexible connecting belt not only meets the basic connection function but also possesses excellent tensile strength, weather resistance, and long-term reliability.

[0041] In this embodiment, in order to meet the performance requirements of the flexible connecting strip in different application scenarios, while taking into account material costs and the operability of the manufacturing process, the following implementation scheme can also be adopted, involving the selection of reinforcing fiber materials, mixing ratio, and detailed steps of the manufacturing process, as follows:

[0042] In the specific design, the reinforcing fiber material of the flexible connecting strip adopts a combination of aramid fiber, carbon fiber and glass fiber, with the following proportions: aramid fiber accounts for 15% of the total weight of reinforcing fibers, carbon fiber accounts for 70%, and glass fiber accounts for 15%. This proportion design takes into account the mechanical properties and durability of various fibers: aramid fiber provides excellent impact resistance, carbon fiber provides high strength and lightweight properties, and glass fiber is used to enhance corrosion resistance and reduce overall cost.

[0043] The flexible connecting strip is set to a thickness of 3mm to achieve a balance between flexibility and strength. Reinforcing fibers are embedded in the resin substrate, forming a three-layer composite structure: the outermost layer is a 0.5mm thick glass fiber reinforcement layer, the middle layer is a 2mm thick carbon fiber main load-bearing layer, and the innermost layer is a 0.5mm thick aramid fiber buffer layer. This layered structure design ensures that the connecting strip provides high-strength support under various stresses while effectively mitigating stress concentration during external impacts.

[0044] During the manufacturing process, the embedding of reinforcing fibers is achieved through the following steps: First, three fiber materials are prepared according to the above proportions, and high-precision fiber placement equipment is used to arrange the fibers layer by layer into the mold. Second, polyurethane with an elastic modulus of 30 MPa is selected as the resin substrate and is uniformly injected into the mold to ensure complete impregnation between the fibers and the substrate. Subsequently, a high-temperature hot-pressing process is used, placing the mold in an environment of 150°C and pressurizing it for 3 hours to allow the resin to fully cure and form a stable composite structure. Finally, the cured flexible connecting strip is cut into the required size using CNC cutting equipment, such as a standardized connecting strip with a length of 500 mm and a width of 50 mm.

[0045] To enhance the weather resistance of the flexible connecting strip, its surface is coated with a UV-resistant coating. The coating uses a polyurethane-based light-stabilized material, has a thickness of 20 micrometers, and is applied evenly to the surface of the connecting strip using a spraying process. After coating, the flexible connecting strip maintains its mechanical properties and flexibility under long-term UV exposure, showing no significant aging or performance degradation.

[0046] The final flexible connecting strip maintained a tensile strength of over 98% after 5000 folding and unfolding cycles, with no significant fatigue damage. In a simulated 365-day sun exposure environmental aging test, its surface coating remained intact, and the internal reinforcing structure remained complete. Through precise material formulation, layered design, and manufacturing processes, the flexible connecting strip possesses high strength, weather resistance, and flexibility, making it suitable for connection needs in various modular building products.

[0047] Furthermore, the substrate bonding layer of the multilayer functional coating structure includes nanoparticle filler material to enhance the adhesion between the coating and the surface of the building module unit; the nanoparticles are selected from one or more of silicon oxide, titanium oxide, or zinc oxide, with an average particle size of 10 to 50 nanometers, and are distributed in the substrate bonding layer in a uniform manner; the coating thickness of the substrate bonding layer is 50 to 200 micrometers, and it is bonded to the surface of the building module unit substrate through plasma treatment or spraying technology, thereby ensuring that the adhesion performance of the functional coating is not affected under high humidity and high temperature difference conditions.

[0048] The substrate bonding layer design in this embodiment aims to significantly enhance the adhesion between the multilayer functional coating structure and the surface of the building module unit, thereby ensuring the reliability and durability of modular buildings in various complex environments. The substrate bonding layer incorporates nanoparticle filler materials, which enhance the adhesion between the coating and the substrate through multiple mechanisms, while providing additional physical and chemical stability.

[0049] In specific implementations, the nanoparticles in the substrate bonding layer are selected from one or more of silicon dioxide (SiO2), titanium dioxide (TiO2), or zinc oxide (ZnO). These materials are widely used in the field of functional coatings due to their high surface energy, small particle size, and good chemical inertness. In this invention, the average particle size of the nanoparticles is designed to be 30 nanometers to ensure that they can be uniformly dispersed within the substrate bonding layer, thereby maximizing the adhesion and filling effect of the coating.

[0050] The preparation process of the substrate bonding layer includes the dispersion of nanoparticles and the formation of the coating. First, selected nanoparticles are mixed with a polymer matrix material at a designed ratio (3% of the total coating mass). The polymer matrix can be epoxy resin or polyurethane resin. To ensure uniform dispersion of the nanoparticles, an appropriate amount of dispersant (such as polycarboxylate or silane coupling agent) can be added, and the mixture is treated using a high-shear stirring device or an ultrasonic dispersion device until a uniform nanoparticle dispersion is formed. Subsequently, the dispersion is uniformly coated onto the surface of the building module unit using a spraying device. The coating thickness is strictly controlled to 100 micrometers to ensure sufficient bonding strength without affecting the subsequent application of functional coatings.

[0051] Before coating, to further enhance the adhesion between the substrate bonding layer and the substrate surface, the surface of the building module unit can be subjected to plasma treatment or mechanical sandblasting. Plasma treatment activates the molecular bonds on the substrate surface, forming a high-energy active surface, thereby enhancing the bond between the substrate and the coating; mechanical sandblasting increases the adhesion area by increasing surface roughness. These pretreatment techniques can effectively remove oil or oxide layers from the substrate surface, ensuring a tight bond between the substrate bonding layer and the substrate surface.

[0052] After coating, a stable adhesive layer is formed on the substrate through a heating or room temperature curing process. For example, the coated module unit is placed in an environment of 80°C for 3 hours to ensure that the mechanical properties of the coating reach their optimal state. At this time, the presence of nanoparticles can significantly improve the adhesion strength of the coating through a dual mechanism of physical intercalation and chemical bonding. Under high humidity and temperature difference environments, such as exposure to continuous humid rainy seasons or areas with diurnal temperature differences exceeding 30°C, the coating still maintains excellent adhesion performance without peeling or cracking.

[0053] Through this design and fabrication process, the substrate bonding layer can meet the stringent requirements of building environments. For example, in actual testing, after immersing a module unit coated with the nanoparticle substrate bonding layer in a high humidity environment of 90% for 72 consecutive hours, the adhesion strength of the coating decreased by less than 5%. Meanwhile, in thermal cycling tests (200 cycles from -20°C to 60°C), the coating did not exhibit any significant peeling or cracking.

[0054] The substrate bonding layer design and its preparation method in this embodiment provide a strong guarantee for high-performance connection of modular buildings.

[0055] This embodiment also provides the specific composition and preparation method of the substrate bonding layer, thereby achieving high bonding strength between the functional coating and the building module unit.

[0056] The specific formulation of the substrate bonding layer is as follows: Epoxy resin is selected as the main component of the substrate material, accounting for 70% of the total weight of the substrate bonding layer. The nanoparticle filler material that enhances adhesion is a mixture of silicon dioxide (SiO2), titanium dioxide (TiO2), and zinc oxide (ZnO) in a weight ratio of 40:40:20, with the total amount of nanoparticles added being 10% of the total weight of the substrate bonding layer. In addition, to ensure uniform dispersion of the nanoparticles, 2% by mass of a silane coupling agent (such as γ-aminopropyltriethoxysilane) is added as a dispersant, and 18% by mass of xylene is added as a diluent to adjust the application viscosity of the coating.

[0057] The method for preparing the substrate bonding layer includes the following steps:

[0058] (1) Mixing and dispersion of nanoparticles:

[0059] After uniformly mixing the silica, titanium dioxide, and zinc oxide nanoparticles prepared in the above proportions, the mixture was added to xylene and treated with an ultrasonic dispersion device for 30 minutes to ensure that the nanoparticles were uniformly distributed in the solvent. Subsequently, a silane coupling agent was slowly added to the dispersion, and the mixture was continuously stirred at room temperature for 15 minutes to ensure that the coupling agent reacted fully with the surface of the nanoparticles, thereby improving the compatibility between the particles and the matrix resin.

[0060] (2) Preparation of matrix material:

[0061] The epoxy resin was heated to 40°C under stirring. The prepared nanoparticle dispersion was then slowly added dropwise to the epoxy resin while maintaining a stirring speed of 300 rpm. After the addition was complete, stirring continued for 30 minutes until the mixture became a homogeneous slurry.

[0062] (3) Coating and curing:

[0063] Prior to coating, the surface of the building module unit is subjected to plasma treatment using a plasma device at 100W power for 2 minutes to create highly active bonding sites on the substrate surface. Then, the prepared substrate bonding layer material is uniformly coated onto the surface of the building module unit using a spraying device, with the coating thickness controlled at 100 micrometers. After coating, the module unit is placed in an environment of 80°C for 2 hours to cure, allowing the coating to fully harden.

[0064] The prepared substrate bonding layer exhibited excellent adhesion properties in the tests. After immersion in 90% relative humidity for 72 hours, its adhesion strength was 8 MPa, which was 50% higher than that of the substrate material without nanoparticles. In the thermal cycling test (200 cycles from -20℃ to 60℃), the coating did not show peeling, blistering or cracking.

[0065] By providing the material ratios and process steps in this embodiment, the technical solution can be directly implemented to prepare a high-performance matrix bonding layer and ensure its reliability and stability in complex building environments.

[0066] Furthermore, the deformation buffer layer comprises a polymer-based material with shape memory function, which is used to generate adaptive deformation when the ambient temperature changes, so as to further improve the connection adaptability between module units; the thickness of the deformation buffer layer ranges from 0.1 mm to 1 mm, and its impact resistance and deformation recovery performance are further optimized by embedding micro-nano-level elastic particles or porous network structures.

[0067] In this embodiment, the main component of the deformation buffer layer is polyurethane-based shape memory polymer (SMPU), which possesses excellent shape memory properties and adaptive deformation capabilities. The polyurethane-based material, through its cross-linked molecular chain structure, imparts temperature responsiveness, enabling it to change shape and recover its original shape according to a preset transition temperature (Tg) when the ambient temperature changes. The Tg selected for the material is set to 35°C, a temperature range suitable for natural temperature differences in most architectural scenarios.

[0068] The specific formulation of the deformation buffer layer is as follows: shape memory polyurethane accounts for 80% of the total weight of the deformation buffer layer, micro / nano-level elastic particles account for 15%, and a pore-forming agent for a porous network structure accounts for 5%. The micro / nano-level elastic particles are spherical silicone rubber particles with an average diameter of 200 nanometers. Their addition increases the local elastic modulus of the deformation buffer layer and enhances its impact resistance. The porous network structure is achieved during the curing process by adding a pore-forming agent (such as polyethylene glycol), with the pore size controlled between 50 and 100 micrometers, to improve the material's flexibility and deformation recovery ability.

[0069] The preparation method is as follows: First, according to the above formulation ratio, the polyurethane shape memory polymer and silicone rubber particles are mixed and stirred for 30 minutes at 500 rpm using a high-speed shear mixer to ensure that the particles are uniformly distributed in the polymer matrix. Then, 5% pore-forming agent is added, and the mixture is continuously stirred at 60°C for 15 minutes to ensure thorough mixing of the pore-forming agent. After mixing, the material is injected into a mold and cured at 80°C for 2 hours, followed by a post-curing treatment at 120°C for 1 hour to achieve final mechanical property optimization.

[0070] The thickness of the deformation buffer layer is precisely controlled to 0.5 mm. A micro-coating device is used to uniformly coat the material onto the substrate bonding layer of the multi-layer functional coating structure, ensuring good adhesion between the material and the upper and lower coatings. The cured deformation buffer layer exhibits the following characteristics: when the ambient temperature is above Tg, the polyurethane substrate softens and can adjust its shape according to external pressure to adapt to the stress distribution at the bonding interface; when the temperature is below Tg, the material returns to its original state, thus providing stable support at the bonding interface.

[0071] In impact resistance testing, the prepared deformation buffer layer showed no cracks or permanent deformation after withstanding an impact energy of 10J, with a recovery rate exceeding 95%. In thermal cycling testing (100 cycles from -20℃ to 60℃), the material's shape memory properties remained stable without performance degradation. In practical applications, this deformation buffer layer effectively alleviates stress concentration between modular units caused by external forces, improving the adaptability of the connection interface and its long-term reliability.

[0072] Based on the above formula and process description, a deformation buffer layer can be implemented to prepare a buffer layer with shape memory function and excellent performance, thereby meeting the multiple requirements of modular buildings for flexibility, durability and environmental adaptability.

[0073] Furthermore, the waterproof sealing layer adopts a multi-component interpenetrating network structure, formed by the cross-linking reaction of polyurethane, silicone rubber, and acrylate materials. The multi-component interpenetrating network structure can quickly adjust the molecular arrangement when subjected to external pressure or stress through a dynamic rearrangement mechanism of molecular chains, thereby achieving a dynamic self-healing waterproof function. The thickness of the waterproof sealing layer ranges from 0.2 mm to 2 mm, and its surface has a nanoscale hydrophobic coating with a contact angle greater than 120 degrees, thereby improving the waterproof performance.

[0074] In this embodiment, the waterproof sealing layer forms a multi-component interpenetrating network (IPN) structure through the cross-linking reaction of polyurethane, silicone rubber, and acrylate materials. The material ratio is set as follows: polyurethane accounts for 50% of the total weight of the sealing layer, silicone rubber accounts for 30%, and acrylate accounts for 20%. Polyurethane provides excellent elasticity and durability, silicone rubber imparts flexibility and anti-aging properties, and acrylate enhances the strength and chemical stability of the network structure. The interpenetrating network structure of the materials is achieved through a multi-component cross-linking reaction, in which the dynamic molecular chain rearrangement mechanism enables the molecular chain segments to quickly adjust their arrangement when the material is subjected to external pressure or stress, thereby forming a self-healing waterproof barrier at the interface.

[0075] The preparation of the waterproof sealing layer includes the following steps: First, a polyurethane precursor and a silicone rubber matrix are mixed at a mass ratio of 5:3, and 1% of a catalyst (such as dibutyltin dilaurate) is added to promote the crosslinking reaction of the polyurethane. Subsequently, acrylate monomers (20% by mass) and 2% of an initiator (such as benzoyl peroxide) are added to initiate the free radical polymerization reaction of the acrylate. During the mixing process, the mixture is stirred at 600 rpm for 30 minutes using a mechanical stirrer to ensure uniform dispersion of all components.

[0076] After mixing, the material is injected into a coating device and uniformly coated onto the target surface using a spraying process, with the coating thickness precisely controlled to 1 mm. Subsequently, the coated material is placed in an environment of 80°C for initial curing for 2 hours to complete the crosslinking reaction of the polyurethane and acrylate. Next, the silicone rubber is fully cured at room temperature for 24 hours. The final waterproof sealant layer has a uniform interpenetrating network structure.

[0077] To further enhance the surface's waterproof performance, a nano-scale hydrophobic coating is applied to the surface of the waterproof sealant layer. This hydrophobic coating, made of modified fluorocarbon material, is 20 nanometers thick and has a contact angle greater than 120 degrees. The coating is prepared using a vacuum evaporation process, ensuring uniform and defect-free coverage during application. This hydrophobic coating effectively prevents the penetration of liquid water in long-term humid and water-immersed environments, further improving the overall waterproof effect.

[0078] The prepared waterproof sealing layer exhibited excellent performance in various testing environments. In the self-healing function test, after the coating was subjected to 10 artificial scratches with a diameter of 0.1 mm, the scratched areas completely closed within 2 minutes under a pressure of 1 MPa, and the water permeability recovered to more than 95% of its initial state. In the hydrophobic performance test, the water droplet roll-off angle on the coating surface was 5°, demonstrating excellent water repellency. Furthermore, after 100 cycles of thermal cycling (-40℃ to 80℃) and 1000 hours of UV aging, the waterproof layer did not show significant cracking or performance degradation, proving its long-term reliability in harsh environments.

[0079] Based on the above material ratios, preparation processes, and test results, a waterproof sealing layer technology solution can be implemented to prepare a sealing layer with dynamic self-healing and excellent waterproof performance, meeting the usage requirements of modular building products in various complex environments.

[0080] Furthermore, the stress transfer layer includes a stress-guiding microstructure, which is a regularly arranged array of hexagonal grooves, wherein the depth of the hexagonal grooves is 50 to 200 micrometers and the width is 100 to 500 micrometers; the arrangement direction of the hexagonal groove array is consistent with the prestress transfer direction, so as to realize multi-dimensional stress transfer; the material of the stress transfer layer is an anisotropic polymer composite material, and the elastic modulus in the prestress transfer direction is 2 to 5 times that in the vertical direction.

[0081] The core of the stress transfer layer is a stress-conducting microstructure, composed of a regularly arranged array of hexagonal grooves. These hexagonal grooves are geometrically designed to optimize the directionality and uniformity of stress transfer. The specific dimensions of the hexagonal grooves are set at a depth of 150 micrometers, a width of 300 micrometers, and a groove spacing of 100 micrometers. This dimensional design balances the stress transfer efficiency of the structure with material strength, ensuring that the layer structure will not fail due to excessive local stress concentration under high prestress conditions. The arrangement direction of the hexagonal array is strictly consistent with the prestress transfer direction, enabling effective stress transfer along the predetermined direction.

[0082] The stress transfer layer material is a polymer composite material with anisotropic mechanical properties. The base polymer matrix is ​​thermoplastic polyurethane (TPU), and the reinforcing material is oriented carbon fiber, which accounts for 30% of the total material weight. The carbon fibers are oriented in the prestress transfer direction through a stretching and orientation technique, so that the elastic modulus of the composite material in this direction is four times that in the vertical direction, thereby significantly improving the stress transfer efficiency.

[0083] The preparation method is as follows:

[0084] (1) Material preparation: First, thermoplastic polyurethane granules and chopped carbon fibers were mixed at a weight ratio of 70:30 and stirred at 180°C using a melt blending device at a stirring speed of 500 rpm for 20 minutes. Subsequently, the mixture was extruded into sheets with a thickness of 500 micrometers using a twin-screw extruder and cooled for later use.

[0085] (2) Hexagonal Groove Machining: A hexagonal groove array is machined on the surface of a thin sheet using laser etching technology. The laser etching equipment parameters are set as follows: laser power of 10W, scanning speed of 100mm / s, etching depth control of 150 micrometers, and the etching path is arranged strictly according to the geometric design of the hexagonal array. A groove array model is generated using computer-aided design (CAD) software, and CNC equipment is used to ensure machining accuracy and consistency.

[0086] (3) Composite layer forming: After the hexagonal groove is processed, the sheets are stacked to the target thickness (2 mm is recommended) and pressed into shape by a hot press at 200°C. The hot pressing process lasts for 30 minutes, and the pressure is set at 5 MPa to ensure the orientation stability of the carbon fibers and the overall density of the material.

[0087] The prepared stress transfer layer has an elastic modulus of 100 MPa in the stress direction and 25 MPa in the vertical direction, achieving the anisotropic mechanical performance design target. In the test, the layer was embedded into the connection interface of a modular building product and loaded under a prestress of 2000 N. The results showed that the stress distribution at the connection interface was uniform, with no local stress concentration or material failure.

[0088] In multi-dimensional stress transfer tests, the stress transfer capability of the stress transfer layer was verified by applying multi-directional loads. The results show that the hexagonal groove array can effectively distribute stress to multiple directions, and the material did not exhibit fatigue damage during 50 load cycles, maintaining stable stress transfer efficiency.

[0089] This stress transfer layer is suitable for modular building applications requiring high loads and strict uniformity of stress distribution, such as the splicing interfaces of bridge modules or the stress-bearing nodes of high-rise buildings. Furthermore, by adjusting the size and density of the hexagonal grooves, or changing the orientation ratio of the carbon fibers, the material properties can be further optimized to meet different engineering needs.

[0090] Furthermore, the building module unit adopts a composite wall structure, including an outer high-strength frame and an inner lightweight infill; wherein the outer high-strength frame is made of carbon fiber reinforced epoxy resin with a frame thickness of 30 to 50 mm; and the inner lightweight infill is made of modified ceramsite concrete.

[0091] The building module unit provided in this embodiment adopts a composite wall structure to achieve an optimized combination of high strength and lightweight, thereby improving the strength, stability, and ease of construction of modular prefabricated building products. This composite wall structure includes an outer high-strength frame and an inner lightweight infill, and its design incorporates precise material selection and structural optimization to meet the performance requirements of complex building scenarios.

[0092] The outer high-strength frame is the main load-bearing component of the composite wall structure, made of carbon fiber reinforced epoxy resin. Carbon fiber is the preferred material due to its extremely high specific strength and specific modulus, significantly improving the wall's flexural strength and impact resistance. Epoxy resin, as the matrix material, provides excellent bonding performance and durability, while its compatibility with carbon fiber ensures the overall mechanical properties of the composite material. The outer frame is designed to be 40 mm thick, a choice that balances strength and weight, allowing the wall to maintain sufficient rigidity while reducing the overall structural weight. To achieve high-precision and high-strength production of the outer frame, a pultrusion process is used to continuously mold the carbon fiber fabric and epoxy resin composite. During pultrusion, precise control of fiber alignment and resin content ensures the frame has uniform mechanical properties and stable dimensional accuracy.

[0093] The inner lightweight infill is made of modified expanded clay concrete, used to provide necessary thermal insulation and sound absorption properties without significantly increasing the weight of the wall. Expanded clay concrete is a lightweight concrete using expanded clay as aggregate; its excellent lightweight and thermal properties make it an ideal material for modular building products. In this invention, the expanded clay concrete undergoes special modification to further improve its strength and durability. During the modification process, a silicate-based material is coated on the surface of the expanded clay to enhance its interfacial bonding performance. Simultaneously, 5% fiber-reinforcing material (such as polypropylene fiber) and 8% silica fume are incorporated into the concrete paste to significantly improve the compressive strength and toughness of the infill. The final modified expanded clay concrete has a compressive strength of 15 MPa and a density of 1200 kg / m³. 3 Its excellent performance can effectively reduce the weight of the wall while meeting the requirements for structural stability.

[0094] The composite wall structure is formed using a step-by-step assembly process. First, an outer high-strength frame is prepared, ensuring its dimensional accuracy meets design requirements. Next, the inner lightweight infill is poured into the frame using a casting process, ensuring complete bonding between the infill and the frame. To this end, a 0.5 mm thick layer of epoxy resin adhesive is applied to the inner surface of the frame, and the expanded clay concrete is poured before the adhesive cures. After filling, the entire structure is placed in a steam curing chamber for 24 hours of moist heat curing at a controlled temperature of 60°C to accelerate the solidification of the infill and the bonding between the frame and the infill.

[0095] The molded composite wall underwent performance testing, demonstrating excellent mechanical and functional properties. In the compressive strength test, the composite wall could withstand a load of 100kN without significant deformation; in the flexural strength test, the maximum deflection of the wall was less than 3 mm. Furthermore, the low thermal conductivity of the ceramsite concrete (0.3W / m·K) endows the wall with good thermal insulation performance, while the sound absorption performance of the porous structure further enhances the acoustic comfort of the modular unit.

[0096] The composite wall structure provided in this embodiment, through the synergistic effect of a high-strength frame and a lightweight infill, not only meets the requirements of modular building products for high strength and lightweight, but also achieves significant optimization in thermal insulation and sound absorption performance.

[0097] Furthermore, the flexible connecting strip is equipped with stress sensing elements, which are made of a conductive polymer doped with graphene. The resistance value changes when the connecting strip deforms. The stress sensing elements are evenly arranged along the length of the connecting strip with a spacing of 50 to 100 mm, and are used to monitor the stress distribution during the folding process in real time.

[0098] The flexible connecting strip provided in this embodiment achieves real-time monitoring of stress distribution during folding and expansion by incorporating stress sensing elements internally. This design not only enhances the intelligence of modular prefabricated building products but also provides a technical solution that improves structural safety and service life. The stress sensing element is made of a graphene-doped conductive polymer, and its structural design and functional implementation have been precisely optimized.

[0099] The core material of the stress sensing element is a graphene-doped polymer composite material. The polymer matrix is ​​polyvinylidene fluoride (PVDF) due to its excellent flexibility and thermal stability, enabling it to maintain stable performance under a wide range of deformation conditions. The graphene doping ratio is 5% of the total weight of the matrix material. By improving the density and uniformity of the conductive network, sensitive changes in resistance under stress are achieved. Graphene exists in the form of nanosheets, with a size ranging from 1 to 5 micrometers, and is uniformly dispersed in the polymer matrix using a solution mixing method. To ensure the dispersion stability of graphene in the matrix, 1% dispersant (such as polyvinylpyrrolidone) is added during the mixing process, and the mixture is treated with an ultrasonic dispersion device until a uniform conductive slurry is formed.

[0100] The stress sensing elements are designed as elongated conductive films, 1 mm wide and 0.2 mm thick, evenly arranged along the length of the flexible connecting strip with a precise spacing of 75 mm to balance stress monitoring resolution and material cost. Each sensing element is fixed inside the flexible connecting strip using a micro-embedding process, with its end electrodes coated with silver paste and connected to the data acquisition system via a flexible circuit board. The embedding process employs multi-layer co-extrusion molding technology, embedding the sensing elements into the middle layer of a highly elastic resin substrate, thus ensuring sensor functionality without affecting the overall mechanical properties and flexibility of the connecting strip.

[0101] The sensing element operates based on changes in the conductive path caused by strain. When the flexible connecting strip deforms during folding or expansion, the conductive network within the graphene-doped conductive polymer adjusts due to stress changes, resulting in a corresponding change in the resistance of the sensing element. By monitoring the resistance change in real time, the stress distribution at various points on the connecting strip can be accurately reflected. To achieve high-precision data acquisition, the output signal of the sensing element is transmitted to an external processing unit via a flexible circuit. The processing unit uses a bridge circuit and an amplifier to process the signal, ultimately transmitting the stress data to the monitoring system in digital signal form.

[0102] After the flexible connecting strip was fabricated and equipped with an embedded stress sensing element, its performance was verified through actual testing. In static tensile testing, the sensing element exhibited a linear resistance response to strain changes ranging from 0.1% to 10%, with a sensitivity of 3.5%. In dynamic folding testing, after the flexible connecting strip was repeatedly folded 2000 times, the sensing element maintained stable response performance without significant fatigue damage. Furthermore, in environmental adaptability testing, the sensing element maintained a stable output signal without drift within a temperature range of -20℃ to 80℃.

[0103] Through this design, the flexible connecting strip not only achieves real-time stress monitoring but also maintains its original high elasticity and durability. In practical applications, this technology can provide important structural health monitoring capabilities for modular building products, enabling timely detection and early warning of potential stress concentration problems.

[0104] Furthermore, a barrier coating is provided between the deformation buffer layer and the waterproof sealing layer in the multilayer functional coating structure, and the thickness of the barrier coating is 10 to 50 micrometers; the barrier coating is made of a chemically resistant fluorocarbon polymer material.

[0105] In the multilayer functional coating structure provided in this embodiment, a barrier coating is provided between the deformation buffer layer and the waterproof sealing layer. Its design aims to improve the overall chemical corrosion resistance and interlayer stability of the coating structure. Through material selection and thickness control, this barrier coating achieves efficient isolation and protection, especially in complex chemical environments or under long-term humid conditions, further optimizing the service life and reliability of the multilayer functional coating structure.

[0106] The barrier coating is made of fluorocarbon polymer materials. Preferred fluorocarbon polymers are polyvinylidene fluoride (PVDF) or copolymers thereof. Fluorocarbon polymers are chosen as the main component of the barrier coating due to their extremely low surface energy, high chemical resistance, and excellent anti-aging properties. This material effectively blocks the migration of chemicals between the deformation buffer layer and the waterproof sealant layer, preventing performance degradation caused by interfacial penetration. Simultaneously, fluorocarbon polymers exhibit excellent adhesion, forming a stable barrier layer without affecting the overall adhesion performance of the multilayer structure.

[0107] The barrier coating thickness is designed to be 30 micrometers, representing an optimized choice between performance and ease of application. A coating that is too thin may result in insufficient isolation, while a coating that is too thick may compromise the flexibility and overall performance of the multilayer structure. The fluorocarbon polymer material is coated in solution form, prepared by dissolving PVDF resin in dimethylacetamide (DMAC) solvent at a concentration controlled at 20% (mass fraction). To improve coating uniformity and adhesion, 1% of a surfactant (such as a fluorinated surfactant) can be added, and the solution is treated with high-speed stirring and ultrasonic dispersion equipment for 30 minutes to ensure homogeneity and stability.

[0108] The coating process employs a spraying method, where the prepared fluorocarbon polymer solution is uniformly applied to the surface of the deformation buffer layer using precision spraying equipment. During coating, the distance between the nozzle and the substrate surface is maintained at 150 mm, and the spraying speed is 100 mm / s to achieve uniform coverage. After coating, the coating is dried at 100°C for 20 minutes to evaporate the solvent and achieve initial curing. Subsequently, a secondary heat treatment is performed at 150°C for 30 minutes to complete the full curing of the coating and form a dense barrier layer.

[0109] The completed multilayer functional coating structure demonstrated its superiority through practical performance testing. In chemical corrosion resistance tests, the barrier coating maintained its integrity and isolation properties after immersion in 10% hydrochloric acid solution and 5% sodium hydroxide solution for 72 hours, without any visible corrosion or discoloration. In damp heat resistance tests, after storing the sample in an environment with 95% relative humidity and 60°C for 100 hours, no peeling or performance degradation occurred between the coatings. Further adhesion tests showed that the bonding strength between the barrier coating and the upper and lower layers reached 5 MPa, meeting practical application requirements.

[0110] By adding a barrier coating between the deformation buffer layer and the waterproof sealing layer, the chemical corrosion resistance of the multilayer coating structure is improved, and the stability and long-term reliability of the interlayer interface are enhanced.

[0111] Furthermore, the multilayer functional coating structure exhibits phase change characteristics under pressure, specifically including: microcapsule structures distributed in the deformation buffer layer, the shell of the microcapsule structure being made of polymethyl methacrylate, and the interior being filled with a temperature-sensitive phase change material and a pressure-responsive catalyst; when the extended connection surfaces of two module units come into contact under a predetermined pressure, some microcapsules rupture, the phase change material and catalyst mix and undergo a chemical reaction, generating a novel polymer with a cross-linked network structure, the novel polymer penetrating into the microstructure of the stress transfer layer to form a synergistic enhancement effect; wherein the average particle size of the microcapsules is 1 to 5 micrometers, the mass percentage fraction in the deformation buffer layer is 3% to 8%, and the shell strength of the microcapsules is achieved by adjusting the wall thickness to ensure that rupture only within the predetermined pressure range.

[0112] The multilayer functional coating structure provided in this embodiment introduces a microcapsule structure into the deformation buffer layer, endowing the coating with phase transition characteristics under pressure. This enables adaptive enhancement and interface optimization during the expansion and connection of modular units. This design not only improves the connection performance of the modular units but also enhances the long-term reliability of the coating structure, ensuring excellent functional performance even after repeated use.

[0113] The design of the microcapsule structure is key to achieving this phase transition property. The shell of the microcapsule is made of polymethyl methacrylate (PMMA), which possesses good mechanical strength and controllable rupture characteristics, ensuring that it ruptures within a predetermined pressure range, thereby releasing the active material inside. The average particle size of the microcapsules is 3 micrometers, a size range that allows them to be uniformly distributed within the deformable buffer layer while maintaining sufficient reactivity and permeability. To control the shell strength, the thickness of the microcapsule shell is set to 200 nanometers, precisely controlled by adjusting the concentration of the PMMA solution and the emulsification stirring speed during microcapsule preparation.

[0114] The microcapsules are filled with a temperature-sensitive phase change material and a pressure-responsive catalyst. The phase change material is preferably a paraffin-based compound (e.g., n-octadecane), which possesses excellent energy storage performance and thermal stability, enabling solid-liquid transitions within a specific temperature range. The catalyst is a two-component cross-linking initiator (e.g., organic peroxide), capable of activating a chemical reaction under pressure to generate a novel polymer with a cross-linked network structure. This polymer not only exhibits excellent mechanical properties but also interacts with the microstructure of the stress-transfer layer, further enhancing the strength and stability of the interface.

[0115] The preparation process of the deformation buffer layer includes the uniform dispersion of microcapsules and coating formation. First, 5% by mass of microcapsules are mixed with a polyurethane matrix material and stirred at 500 rpm for 30 minutes using a high-speed shear mixer to ensure uniform distribution of the microcapsules within the matrix. Subsequently, the mixture is uniformly coated onto the substrate bonding layer surface using a blade coating process, with the coating thickness precisely controlled to 0.8 mm. After coating, initial curing is performed at 60°C for 2 hours, followed by a secondary curing at 120°C for 4 hours to improve the mechanical properties of the coating and the distribution stability of the microcapsules.

[0116] During the expansion and connection of the modular units, when the connection surface is subjected to a pressure of 500 kPa, the microcapsules distributed in the deformation buffer layer will rupture at the critical point of the shell strength, releasing the phase change material and catalyst inside. The phase change material rapidly penetrates into the microstructure of the surrounding stress transfer layer and undergoes a cross-linking reaction under the action of the catalyst. The resulting novel polymer forms a synergistic reinforcing effect with the surrounding materials, thereby further improving the strength and durability of the connection interface.

[0117] Actual performance tests show that this coating structure can significantly improve the connectivity of the module units. Under predetermined pressure, the adhesion strength of the coating increased by 30%, and the strength of the interface remained stable after 1000 loading cycles. Furthermore, the phase change reaction of the microcapsules remained stable under different temperature and humidity conditions, without premature rupture or functional failure.

[0118] By introducing microcapsule structures into the multilayer functional coating structure, not only were phase change characteristics under pressure achieved, but the connection performance of the module units was also optimized through an adaptive enhancement mechanism.

[0119] Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A foldable and expandable modular prefabricated building product, characterized in that, It includes multiple groups of building module units, wherein each group of building module units includes at least two building module units, and adjacent building module units are foldably connected by a flexible connecting strip, which is made of a highly elastic resin substrate; Each building module unit's extended connection surface includes a multi-layer functional coating structure, which is used to realize the extended connection between the first group of building module units and the second group of building module units; the multi-layer functional coating structure includes, from the inside to the outside, a substrate bonding layer, a deformation buffer layer, a waterproof sealing layer, and a stress transmission layer. The substrate bonding layer is used to achieve a firm bond between the functional coating and the building module unit; the deformation buffer layer is used to generate controllable deformation when the first group of building module units and the second group of building module units are subjected to external forces, avoiding stress concentration and improving the adaptability of the connection interface; the waterproof sealing layer is used to form a dense waterproof structure through molecular chain rearrangement under stress, ensuring the waterproof performance of the extended connection; the stress transfer layer is used to transfer and uniformly distribute stress between the first group of building module units and the second group of building module units, ensuring the structural stability of the extended connection. The flexible connecting strip's high-elasticity resin substrate includes a reinforcing fiber material selected from aramid fiber, carbon fiber, or glass fiber. The reinforcing fiber material is embedded along the longitudinal direction of the flexible connecting strip to form a multi-layer composite structure. The thickness of the flexible connecting strip ranges from 0.5 mm to 5 mm, and the content of the reinforcing fiber material accounts for 5% to 25% of the total weight of the flexible connecting strip. The surface of the flexible connecting strip is coated with a UV-resistant coating to improve its weather resistance under long-term exposure to sunlight.

2. The foldable and expandable modular prefabricated building product according to claim 1, characterized in that, The substrate bonding layer of the multilayer functional coating structure includes nanoparticle filler material to enhance the adhesion between the coating and the surface of the building module unit. The nanoparticles are selected from one or more of silicon oxide, titanium oxide, or zinc oxide, with an average particle size of 10 to 50 nanometers, and are distributed in the substrate bonding layer in a uniform manner. The coating thickness of the substrate bonding layer is 50 to 200 micrometers, and it is bonded to the surface of the building module unit substrate through plasma treatment or spraying technology, thereby ensuring that the adhesion performance of the functional coating is not affected under high humidity and high temperature difference conditions.

3. The foldable and expandable modular prefabricated building product according to claim 1, characterized in that, The deformation buffer layer comprises a polymer-based material with shape memory function, which is used to generate adaptive deformation when the ambient temperature changes, so as to further improve the connection adaptability between module units; the thickness of the deformation buffer layer ranges from 0.1 mm to 1 mm, and its impact resistance and deformation recovery performance are further optimized by embedding micro-nano-level elastic particles or porous network structures.

4. The foldable and expandable modular prefabricated building product according to claim 1, characterized in that, The waterproof sealing layer adopts a multi-component interpenetrating network structure, which is formed by the cross-linking reaction of polyurethane, silicone rubber and acrylate materials. The multi-component interpenetrating network structure can quickly adjust the molecular arrangement when subjected to external pressure or stress through the dynamic rearrangement mechanism of molecular chains, so as to achieve dynamic self-healing waterproof function. The thickness of the waterproof sealing layer ranges from 0.2 mm to 2 mm, and its surface has a nano-scale hydrophobic coating with a contact angle greater than 120 degrees, thereby improving the waterproof performance.

5. The foldable and expandable modular prefabricated building product according to claim 1, characterized in that, The stress transfer layer includes a stress-guiding microstructure, which is a regularly arranged array of hexagonal grooves. The depth of the hexagonal grooves is 50 to 200 micrometers, and the width is 100 to 500 micrometers. The arrangement direction of the hexagonal groove array is consistent with the stress transfer direction, which is used to achieve multi-dimensional stress transfer. The material of the stress transfer layer is an anisotropic polymer composite material, and the elastic modulus in the stress transfer direction is 2 to 5 times that in the vertical direction.

6. The foldable and expandable modular prefabricated building product according to claim 1, characterized in that, The building module unit adopts a composite wall structure, including an outer high-strength frame and an inner lightweight infill; wherein the outer high-strength frame is made of carbon fiber reinforced epoxy resin and the frame thickness is 30 to 50 mm; the inner lightweight infill is made of modified ceramsite concrete.

7. The foldable and expandable modular prefabricated building product according to claim 1, characterized in that, The flexible connecting strip is equipped with stress sensing elements, which are made of conductive polymer doped with graphene. The resistance value changes when the connecting strip deforms. The stress sensing elements are evenly arranged along the length of the connecting strip with a spacing of 50 to 100 mm, and are used to monitor the stress distribution in real time during the folding process.

8. The foldable and expandable modular prefabricated building product according to claim 1, characterized in that, A barrier coating is provided between the deformation buffer layer and the waterproof sealing layer in the multi-layer functional coating structure. The thickness of the barrier coating is 10 to 50 micrometers. The barrier coating is made of a chemically resistant fluorocarbon polymer material.

9. The foldable and expandable modular prefabricated building product according to claim 1, characterized in that, The multilayer functional coating structure exhibits phase change characteristics under pressure, specifically including: microcapsule structures distributed in the deformation buffer layer, the shell of the microcapsule structure being made of polymethyl methacrylate, and the interior being filled with a temperature-sensitive phase change material and a pressure-responsive catalyst; when the extended connection surfaces of two module units come into contact under a predetermined pressure, some microcapsules rupture, the phase change material and the catalyst mix and undergo a chemical reaction, generating a novel polymer with a cross-linked network structure, which penetrates into the microstructure of the stress transfer layer, forming a synergistic enhancement effect.

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