Fireproof and heat-insulating door core and filling process thereof

Abstract

This invention provides a fireproof and insulated door core and its filling process. The core is obtained by filling a door frame with a wet core material, followed by compression molding and curing. The wet core material, by weight, comprises: 4-12 parts closed-cell expanded perlite, 6-18 parts active magnesium oxide, 10-30 parts a 25%-35% (calculated as anhydrous magnesium sulfate) magnesium sulfate aqueous solution, 0.1-0.3 parts a modifier, 0.3-1.2 parts biomimetic interface hybrid modified reinforcing fibers, and 0.1-0.3 parts calcium stearate. The fireproof and insulated door core provided by this invention has low density and good thermal insulation performance, high matrix strength, density, and high-temperature stability, good flexural and impact resistance, low water absorption, good moisture resistance, and excellent overall fireproof and thermal insulation performance.

Description

Technical Field

[0001] This invention relates to the field of door core filling materials, specifically to a fireproof and insulating door core and its filling process. Background Technology

[0002] With increasingly stringent fire safety requirements for buildings, fire doors, as key components of fire-resistant partitions, directly impact the evacuation of personnel and the safety of property during a fire. Currently, most mainstream fire door core materials on the market use expanded perlite as lightweight aggregate and a magnesium oxide-magnesium sulfate cementitious system as the binder. These materials are widely used in the building fire protection field due to their excellent fire-resistant and heat-insulating properties and relatively low cost. Meanwhile, as the construction industry moves towards green and low-carbon development, lightweight building materials, which effectively reduce building weight, foundation load, and transportation energy consumption, have become an important development trend in the building materials industry. Fire door core materials are also evolving towards lightweight, high-strength, and multifunctional integrated materials.

[0003] However, existing perlite-based fireproof door core materials still have significant limitations in practical applications: on the one hand, in pursuit of lightweight properties, traditional formulations typically control the core density at 280 kg / m³. 3 The following issues lead to excessively high internal porosity and loose structure in the material, resulting in compressive strength generally below 0.5 MPa and extremely poor impact resistance. When subjected to the impact of fire hoses or external forces, the material is prone to cracking and perforation, making it difficult to meet the relevant standard requirements for the impact resistance performance of fire door cores. On the other hand, the modifiers used in existing technologies are mostly single-component, which are difficult to synergistically improve the strength, toughness, and high-temperature stability of the material. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a fireproof door core and its filling process.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a fireproof door core, which is obtained by filling a door core frame with a wet core material, followed by compression molding and curing. The wet core material, by weight, comprises the following raw materials: 4-12 parts of closed-cell expanded perlite, 6-18 parts of active magnesium oxide, 10-30 parts of an aqueous solution of magnesium sulfate with a mass fraction of 25%-35% (calculated as anhydrous magnesium sulfate), 0.1-0.3 parts of modifier, 0.3-1.2 parts of reinforcing fiber modified by biomimetic interface hybridization, and 0.1-0.3 parts of calcium stearate.

[0006] Using the above technical solution, closed-cell expanded perlite, as a lightweight aggregate, can reduce the overall density of the door core and improve thermal insulation performance; active magnesium oxide undergoes a hydration reaction with a 25%-35% magnesium sulfate aqueous solution to form a magnesium sulfate-oxygen cementitious system, which binds the components and provides matrix strength; the modifier improves the hydration process of the cementitious system, optimizes the microstructure of the matrix, and enhances the material's density and high-temperature stability; the biomimetic interface hybridized reinforcing fibers are dispersed in the matrix, bridging microcracks and improving the material's flexural strength and impact resistance; calcium stearate, as a hydrophobic agent, is uniformly distributed on the surface of the material's internal pores and the surface of hydration products, reducing surface energy through long-chain alkyl hydrophobic groups, preventing water penetration, significantly reducing the material's water absorption rate, and improving moisture-proof performance.

[0007] Preferably, the wet core material is prepared as follows: 1) Add closed-cell expanded perlite, active magnesium oxide, and calcium stearate to a mixer and dry mix at 120-150 r / min for 2-3 minutes to obtain a dry mix. 2) Add the dry mixture to the pre-mixed magnesium sulfate aqueous solution and modifier mixture, and stir at 80-100 r / min for 3-5 min; then add the reinforcing fiber modified by biomimetic interface hybridization, reduce the speed to 30-40 r / min, and continue stirring for 2-3 min until uniformly dispersed to obtain wet core material.

[0008] Using the above technical solution, firstly, dry-mix closed-cell expanded perlite, active magnesium oxide, and calcium stearate to achieve preliminary uniform dispersion of each solid component; then, add a mixture of magnesium sulfate aqueous solution and modifier and stir to ensure that the cementing component and modifier are fully contacted and mixed, providing a uniform reaction basis for subsequent hydration reaction; finally, add reinforcing fibers modified by biomimetic interface hybridization and reduce the stirring speed to reduce the breakage damage of reinforcing fibers during stirring, ensuring the effective length and dispersion uniformity of reinforcing fibers, so that the reinforcing fibers are evenly distributed in the wet core material system.

[0009] Preferably, the oven-dry density of the fireproof door core is 380-420 kg / m³. 3 .

[0010] By adopting the above technical solution, the overall weight of the fire door leaf can be kept within a reasonable range, reducing the requirements for installation process; the porosity of the material in this density range is moderate, which can effectively maintain the thermal insulation performance of the material; the internal structure of the material in this density range is relatively dense, which improves the compressive strength and impact resistance of the material; the internal structure of the material in this density range is relatively dense, the hydration reaction of the cementing system is sufficient, and the drying shrinkage rate is low.

[0011] Preferably, the closed-cell expanded perlite has a particle size of 0.5-2.5 mm and a bulk density of 110-130 kg / m³.3 The active magnesium oxide is lightly calcined magnesium oxide, with an activity (citric acid method) ≥75%.

[0012] By adopting the above technical solution, the parameters of closed-cell expanded perlite are limited, resulting in a reasonable aggregate particle size distribution and uniform pore distribution in the stacked state. At the same time, the lightweight characteristics of the core are maintained, and the filling density of the aggregate is improved. The hydration reaction activity of lightly calcined magnesium oxide is sufficient, and it reacts fully with magnesium sulfate aqueous solution to form a stable cementitious structure, thereby improving the bonding strength and structural stability of the matrix.

[0013] The present invention also provides a filling process for the core of a fireproof door, comprising the following steps: S1. Fill the door core frame with the above-mentioned wet core material, wherein the loose bulk density of the wet core material is 450-500 kg / m³. 3 Start the hydraulic press to press and shape, and obtain the pressed and shaped door core blank; S2. The pressed door core blank is left to stand for 5-7 days under an ambient temperature of 18-28℃ and a relative humidity of 60%-75% to obtain the finished fireproof and insulating door core.

[0014] By adopting the above technical solution, the loose bulk density of the wet core material is limited, which makes the core material filling in the door core frame uniform, providing a basis for obtaining a stable finished product density after compression molding; compression molding makes the wet core material dense, improving the structural density and dimensional stability of the compressed door core blank; static curing for 5-7 days under specific conditions promotes the full hydration reaction of the cementing system, so that the fireproof door core product obtains stable mechanical properties and structural integrity.

[0015] Preferably, in step S1, the compression molding is carried out under constant temperature conditions of 58-62℃, the pressure is increased to 2-3MPa within 30-40s, the pressure is held for 90-120min, and then the pressure is released within 20-30s.

[0016] Using the above technical solution, the core material is pressed and molded under a constant temperature of 58-62℃ to promote the hydration reaction of the gelling system and maintain the plastic flowability of the wet core material. The pressure is slowly increased to 2-3MPa within 30-40s to uniformly compact the wet core material and reduce internal stress concentration. The pressure is held for 90-120min to provide sufficient time for the gelling reaction, forming a stable gelling structure and ensuring that the core blank does not deform after demolding. The pressure is slowly released within 20-30s to prevent the core blank from bulging and cracking due to a sudden drop in pressure, thus maintaining its dimensional stability and structural integrity.

[0017] Preferably, in step S1, the door core frame is a flame-retardant wooden or metal rectangular frame structure, and the inner side of the door core frame is provided with a flared groove that is wider on the outside and narrower on the inside. The wet core material is embedded in the flared groove during the pressing process to form a firm mechanical interlocking structure.

[0018] Using the above technical solution, a flared groove with a wider outer side and a narrower inner side is set on the inner side of the door core frame, so that the wet core material can be fully embedded in the groove during the pressing process; the solid mechanical interlocking structure formed after curing effectively prevents delamination and slippage between the door core and the frame; this structure restricts the relative displacement between the door core and the frame, and enhances the overall structural stability of the door core.

[0019] Preferably, the raw materials for preparing the modifier, by mass percentage, include: 18%-25% aluminum dihydrogen phosphate, 25%-40% silica sol (calculated as SiO2) with a mass fraction of 30%, 3%-8% aluminum sol (calculated as Al2O3) with a mass fraction of 12%, 1.5%-3.0% citric acid, and the balance being deionized water.

[0020] Using the above technical solution, aluminum dihydrogen phosphate can react with active magnesium oxide to generate a magnesium phosphate cement phase. This cement phase forms a continuous and dense ceramic protective layer at high temperatures, effectively blocking heat transfer and flame spread. Silica particles in silica sol can fill the micropores inside the material and undergo a condensation reaction with the hydroxyl groups on the surface of magnesium oxysulfate cement hydration products to form Si-O-Mg chemical bonds, enhancing the interfacial bonding force between hydration products. At the same time, it transforms into a silica ceramic phase at high temperatures, improving high-temperature structural stability. Aluminum sol can undergo a condensation reaction with the silanol groups on the surface of silica sol to form a pre-bonded network, which transforms into an aluminosilicate ceramic phase at high temperatures. Citric acid can form a soluble complex with metal ions, slowing down the hydration exothermic rate of magnesium oxide, while providing an acidic buffer environment for the dispersion of silica sol and aluminum sol. The synergistic effect of each component improves the density, bonding strength, and high-temperature stability of the matrix.

[0021] Preferably, the modifier is prepared as follows: aluminum dihydrogen phosphate is added to deionized water, heated to 55-65°C, and stirred at 300-400 r / min for 20-30 min until completely dissolved; citric acid is added, and stirring is continued for 10-15 min; then the temperature is lowered to 25-35°C, and aluminum sol is slowly added dropwise while stirring at 200-300 r / min for 15-25 min; after the addition is complete, stirring is continued for 20-30 min; then the temperature is maintained and silica sol is slowly added dropwise for 15-25 min; after the addition is complete, stirring is continued for 40-60 min to obtain the modifier.

[0022] Using the above technical solution, aluminum dihydrogen phosphate is added to deionized water and heated and stirred until completely dissolved to ensure uniform dispersion of aluminum dihydrogen phosphate in the system; after adding citric acid, stirring is continued to promote thorough mixing of citric acid and the solution system; after cooling, aluminum sol is slowly added dropwise while stirring to control the dispersion rate of aluminum sol and prevent agglomeration; after the aluminum sol is added dropwise, stirring is continued to ensure sufficient contact between the aluminum sol and the system components and to allow for a preliminary reaction; while maintaining the temperature, silica sol is slowly added dropwise while extending the stirring time to promote the condensation reaction between silica sol and aluminum sol; throughout the preparation process, by controlling the temperature, stirring speed, and dropping rate, the components are ensured to be fully mixed and reacted to obtain a stable and uniform modifier.

[0023] Preferably, the biomimetic interface hybrid modified reinforcing fiber is basalt fiber synergistically modified with dopamine hydrochloride-silane coupling agent, and its preparation method is as follows: (1) Prepare a Tris-HCl buffer solution with a pH of 8.0-9.0, add dopamine hydrochloride, and prepare a solution with a concentration of 1.5-2.5 g / L. Stir at 50-60 r / min for 20-24 h until the solution changes from colorless to dark brown to obtain the dopamine self-polymerization treatment solution. (2) Immerse the basalt fiber in the dopamine self-polymerization treatment solution obtained in step (1) at a solid-liquid ratio of 1:15g / mL to 1:25g / mL, and disperse it with ultrasonic assistance for 10-15 min at an ultrasonic frequency of 35-40kHz and a power of 150-250W. Then soak it at 24-28℃ for 20-28 h. After taking it out, rinse it with deionized water 3-5 times and vacuum dry it at 50-60℃ for 2-3 h to obtain basalt fiber with a polydopamine layer on the surface. (3) Prepare an alcohol-water solution containing 1.5%-3.0% silane coupling agent KH-550, 15%-25% anhydrous ethanol, and the remainder being deionized water, by volume percentage, with the sum of the volume percentages of each component being 100%. Adjust the pH to 4.5-5.5 with a 36% acetic acid solution. (4) Immerse the basalt fiber obtained in step (2) into the alcohol-water solution obtained in step (3), stir at 240-260 r / min at 60-70℃ for 2-4 h, after the reaction is completed, vacuum filter under vacuum degree -0.09MPa (gauge pressure), wash with anhydrous ethanol 3-4 times, and then vacuum dry at 70℃ for 4 h, and cut to a length of 4-5 mm to obtain modified basalt fiber with an organic-inorganic hybrid grafted layer on the surface.

[0024] Using the above technical solution, a tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a pH of 8.0-9.0 was prepared and dopamine hydrochloride was added and stirred to provide a suitable environment for the self-polymerization of dopamine hydrochloride, resulting in a stable dopamine self-polymerization treatment solution. Basalt fibers were dispersed and soaked with ultrasonic assistance to ensure that polydopamine was uniformly coated on the surface of the basalt fibers. An alcohol-water solution containing the silane coupling agent γ-aminopropyltriethoxysilane with a specific pH was prepared to provide suitable conditions for the hydrolysis and grafting reaction of the silane coupling agent. The basalt fibers coated with the polydopamine layer were immersed in the alcohol-water solution for reaction, so that the silane coupling agent was grafted onto the surface of the polydopamine layer to form an organic-inorganic hybrid grafted layer. After vacuum filtration, rinsing, drying and cutting, modified basalt fibers with uniform surface modification and regular dimensions were obtained.

[0025] The beneficial effects of this invention are as follows: Closed-cell expanded perlite, as a lightweight aggregate, can reduce the overall density of the door core and improve thermal insulation performance. Active magnesium oxide undergoes a hydration reaction with a 25%-35% magnesium sulfate aqueous solution to form a magnesium sulfate-oxygen cementitious system, which binds the components and provides matrix strength. Modifiers improve the hydration process of the cementitious system, optimize the matrix microstructure, and enhance the material's density and high-temperature stability. Biomimetic interface hybridized reinforcing fibers are dispersed in the matrix, bridging microcracks and improving the material's flexural strength and impact resistance. Calcium stearate, as a hydrophobic agent, is uniformly distributed on the surface of the material's internal pores and hydration products. Through long-chain alkyl hydrophobic groups, it reduces surface energy, prevents water penetration, significantly reduces the material's water absorption rate, and improves moisture resistance. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure used to highlight the flared slot in an embodiment of the present invention.

[0027] In the picture: 1. Door core frame; 2. Trumpet-shaped slot. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The specific information on the raw materials used in the embodiments of the present invention is shown in Table 1.

[0030] Table 1

[0031] Example 1: This embodiment provides a fireproof door core, which is obtained by filling a door core frame 1 with a wet core material, followed by compression molding and curing. The wet core material, by weight, comprises: 4 parts closed-cell expanded perlite, 6 parts active magnesium oxide, 10 parts a 25% (calculated as anhydrous magnesium sulfate) magnesium sulfate aqueous solution, 0.1 parts modifier, 0.3 parts biomimetic interface hybridized reinforcing fiber, and 0.1 parts calcium stearate. The closed-cell expanded perlite has a particle size of 0.5 mm and a bulk density of 110 kg / m³. 3 The active magnesium oxide is lightly calcined magnesium oxide, with an activity (citric acid method) ≥75%.

[0032] The raw materials for preparing the modifier, by mass percentage, include: 18% aluminum dihydrogen phosphate, 25% silica sol (calculated as SiO2) at 30% mass, 3% aluminum sol (calculated as Al2O3) at 12% mass, 1.5% citric acid, and the balance being deionized water. The preparation method of the modifier is as follows: aluminum dihydrogen phosphate is added to deionized water, heated to 55℃, and stirred at 300 r / min for 20 min until completely dissolved; citric acid is added, and stirring continues for 10 min; then the temperature is lowered to 25℃, and aluminum sol is slowly added dropwise while stirring at 200 r / min for 15 min; after the addition is complete, stirring continues for 20 min; then the temperature is maintained while silica sol is slowly added dropwise for 15 min; after the addition is complete, stirring continues for 40 min to obtain the modifier.

[0033] The reinforcing fiber modified by biomimetic interface hybridization is a basalt fiber synergistically modified with dopamine hydrochloride-silane coupling agent, and its preparation method is as follows: (1) Prepare a Tris-HCl buffer solution with a pH of 8.0, add dopamine hydrochloride, prepare a solution with a concentration of 1.5 g / L, stir at 50 r / min for 20 h until the solution changes from colorless to dark brown, and obtain the dopamine self-polymerization treatment solution. (2) The basalt fiber was immersed in the dopamine self-polymerization treatment solution obtained in step (1) at a solid-liquid ratio of 1:15 g / mL. The fiber was ultrasonically dispersed for 10 min at an ultrasonic frequency of 35 kHz and a power of 150 W, and then soaked at 24 °C for 20 h. After taking it out, it was rinsed with deionized water three times and vacuum dried at 50 °C for 2 h to obtain basalt fiber with a polydopamine layer on the surface. (3) The sum of the volume percentages of each component is 100% by volume. Prepare an alcohol-water solution containing 1.5% silane coupling agent KH-550, 15% anhydrous ethanol, and the remainder is deionized water. Adjust the pH to 4.5 with a 36% acetic acid solution. (4) Immerse the basalt fiber obtained in step (2) into the alcohol-water solution obtained in step (3), stir at 240 r / min at 60℃ for 2 h, after the reaction is completed, vacuum filter under vacuum degree -0.09 MPa (gauge pressure), wash with anhydrous ethanol 3 times, and then vacuum dry at 70℃ for 4 h, cut to a length of 4 mm to obtain modified basalt fiber with organic-inorganic hybrid grafted layer on the surface.

[0034] The preparation method of wet core material is as follows: 1) Add closed-cell expanded perlite, activated magnesium oxide, and calcium stearate to a mixer and dry mix at 120 r / min for 2 min to obtain a dry mix. 2) Add the dry mixture to the pre-mixed magnesium sulfate aqueous solution and modifier mixture, and stir at 80 r / min for 3 min; then add the reinforcing fiber modified by biomimetic interface hybridization, reduce the speed to 30 r / min, and continue stirring for 2 min until uniformly dispersed to obtain wet core material.

[0035] This embodiment also provides a filling process for the core of a fireproof door, including the following steps: S1. Fill the door core frame 1 with the above-mentioned wet core material. The loose bulk density of the wet core material is 450 kg / m³. 3 Start the hydraulic press, press and shape the core, and carry out the process under a constant temperature of 58℃. Within 30 seconds, the pressure is increased to 2MPa, held for 90 minutes, and then the pressure is released within 20 seconds to obtain the pressed and shaped door core blank. Among them, the door core frame 1 is a fire-retardant wooden rectangular frame structure. The inner side of the door core frame 1 is provided with a flared groove 2 that is wider on the outside and narrower on the inside. The wet core material is embedded in the flared groove during the pressing process to form a firm mechanical interlocking structure. S2. The pressed door core blank is left to cure for 5 days at an ambient temperature of 18℃ and a relative humidity of 60% to obtain an oven-dry density of 380 kg / m³. 3 Fireproof and insulating door core finished products.

[0036] Example 2: This embodiment provides a fireproof door core, which is obtained by filling a door core frame 1 with a wet core material, followed by compression molding and curing. The wet core material, by weight, comprises: 12 parts closed-cell expanded perlite, 18 parts activated magnesium oxide, 30 parts a 35% (calculated as anhydrous magnesium sulfate) magnesium sulfate aqueous solution, 0.3 parts modifier, 1.2 parts biomimetic interface hybridized reinforcing fiber, and 0.3 parts calcium stearate. The closed-cell expanded perlite has a particle size of 2.5 mm and a bulk density of 130 kg / m³. 3 The active magnesium oxide is lightly calcined magnesium oxide, with an activity (citric acid method) ≥75%.

[0037] The raw materials for preparing the modifier, by mass percentage, include: 25% aluminum dihydrogen phosphate, 40% silica sol (calculated as SiO2) at 30% mass, 8% aluminum sol (calculated as Al2O3) at 12% mass, 3.0% citric acid, and the balance being deionized water. The preparation method of the modifier is as follows: aluminum dihydrogen phosphate is added to deionized water, heated to 65℃, and stirred at 400 r / min for 30 min until completely dissolved; citric acid is added, and stirring continues for 15 min; then the temperature is lowered to 35℃, and aluminum sol is slowly added dropwise while stirring at 300 r / min for 25 min; after the addition is complete, stirring continues for 30 min; then the temperature is maintained while silica sol is slowly added dropwise for 25 min; after the addition is complete, stirring continues for 60 min to obtain the modifier.

[0038] The reinforcing fiber modified by biomimetic interface hybridization is a basalt fiber synergistically modified with dopamine hydrochloride-silane coupling agent, and its preparation method is as follows: (1) Prepare a Tris-HCl buffer solution with a pH of 9.0, add dopamine hydrochloride, and prepare a solution with a concentration of 2.5 g / L. Stir at 60 r / min for 24 h until the solution changes from colorless to dark brown to obtain the dopamine self-polymerization treatment solution. (2) The basalt fiber was immersed in the dopamine self-polymerization treatment solution obtained in step (1) at a solid-liquid ratio of 1:25 g / mL. It was ultrasonically dispersed for 15 min under ultrasonic frequency of 40 kHz and power of 250 W, and then soaked at 28 °C for 28 h. After taking it out, it was rinsed 5 times with deionized water and vacuum dried at 60 °C for 3 h to obtain basalt fiber with polydopamine coating on the surface. (3) The sum of the volume percentages of each component is 100% by volume. Prepare an alcohol-water solution containing 3.0% silane coupling agent KH-550, 25% anhydrous ethanol, and the remainder is deionized water. Adjust the pH to 5.5 with a 36% acetic acid solution. (4) Immerse the basalt fiber obtained in step (2) into the alcohol-water solution obtained in step (3), stir at 260 r / min at 70℃ for 4 h, after the reaction is completed, vacuum filter under vacuum degree -0.09 MPa (gauge pressure), wash with anhydrous ethanol 4 times, and then vacuum dry at 70℃ for 4 h, cut to a length of 5 mm, to obtain modified basalt fiber with organic-inorganic hybrid grafted layer on the surface.

[0039] The preparation method of wet core material is as follows: 1) Add closed-cell expanded perlite, activated magnesium oxide, and calcium stearate to a mixer and dry mix at 150 r / min for 3 min to obtain a dry mix. 2) Add the dry mixture to the pre-mixed magnesium sulfate aqueous solution and modifier mixture, and stir at 100 r / min for 5 min; then add the reinforcing fiber modified by biomimetic interface hybridization, reduce the speed to 40 r / min, and continue stirring for 3 min until uniformly dispersed to obtain wet core material.

[0040] This embodiment also provides a filling process for the core of a fireproof door, including the following steps: S1. Fill the door core frame 1 with the above-mentioned wet core material. The loose bulk density of the wet core material is 500 kg / m³. 3 Start the hydraulic press, press and shape the core, and carry out the process under a constant temperature of 62℃. Within 40 seconds, the pressure is increased to 3MPa, and the pressure is maintained for 120 minutes. Then, the pressure is released within 30 seconds to obtain the pressed and shaped door core blank. Among them, the door core frame 1 is a metal rectangular frame structure. The inner side of the door core frame 1 is provided with a flared groove 2 that is wider on the outside and narrower on the inside. The wet core material is embedded in the flared groove during the pressing process to form a firm mechanical fitting and locking structure. S2. The pressed door core blank is left to cure for 7 days at an ambient temperature of 28℃ and a relative humidity of 75% to obtain an oven-dry density of 395 kg / m³. 3 Fireproof and insulating door core finished products.

[0041] Example 3: This embodiment provides a fireproof door core, which is obtained by filling a door core frame 1 with a wet core material, followed by compression molding and curing. The wet core material, by weight, comprises: 8 parts closed-cell expanded perlite, 12 parts active magnesium oxide, 20 parts a 30% (calculated as anhydrous magnesium sulfate) magnesium sulfate aqueous solution, 0.2 parts modifier, 0.8 parts biomimetic interface hybridized reinforcing fiber, and 0.2 parts calcium stearate. The closed-cell expanded perlite has a particle size of 1.5 mm and a bulk density of 120 kg / m³. 3 The active magnesium oxide is lightly calcined magnesium oxide, with an activity (citric acid method) ≥75%.

[0042] The raw materials for preparing the modifier, by mass percentage, include: 21% aluminum dihydrogen phosphate, 32% silica sol (calculated as SiO2) at 30% mass, 5% aluminum sol (calculated as Al2O3) at 12% mass, 2.2% citric acid, and the balance being deionized water. The preparation method of the modifier is as follows: aluminum dihydrogen phosphate is added to deionized water, heated to 60℃, and stirred at 350 r / min for 25 min until completely dissolved; citric acid is added, and stirring continues for 12 min; then the temperature is lowered to 30℃, and aluminum sol is slowly added dropwise while stirring at 250 r / min for 20 min; after the addition is complete, stirring continues for 25 min; then the temperature is maintained while silica sol is slowly added dropwise for 20 min; after the addition is complete, stirring continues for 50 min to obtain the modifier.

[0043] The reinforcing fiber modified by biomimetic interface hybridization is a basalt fiber synergistically modified with dopamine hydrochloride-silane coupling agent, and its preparation method is as follows: (1) Prepare a Tris-HCl buffer solution with a pH of 8.5, add dopamine hydrochloride to prepare a solution with a concentration of 2 g / L, stir at 55 r / min for 22 h until the solution changes from colorless to dark brown, and obtain the dopamine self-polymerization treatment solution. (2) The basalt fiber was immersed in the dopamine self-polymerization treatment solution obtained in step (1) at a solid-liquid ratio of 1:20 g / mL. It was ultrasonically dispersed for 12 min at an ultrasonic frequency of 38 kHz and a power of 200 W, and then soaked at 26 °C for 24 h. After taking it out, it was rinsed with deionized water 4 times and vacuum dried at 55 °C for 2.5 h to obtain basalt fiber with a polydopamine layer on the surface. (3) The sum of the volume percentages of each component is 100%. Prepare an alcohol-water solution containing 2.2% silane coupling agent KH-550, 20% anhydrous ethanol, and the remainder is deionized water. Adjust the pH to 5.0 with a 36% acetic acid solution. (4) Immerse the basalt fiber obtained in step (2) into the alcohol-water solution obtained in step (3), stir at 250 r / min at 65℃ for 3 h, after the reaction is completed, vacuum filter under vacuum degree -0.09 MPa (gauge pressure), wash with anhydrous ethanol 4 times, and then vacuum dry at 70℃ for 4 h, cut to a length of 5 mm to obtain modified basalt fiber with organic-inorganic hybrid grafted layer on the surface.

[0044] The preparation method of wet core material is as follows: 1) Add closed-cell expanded perlite, activated magnesium oxide, and calcium stearate to a mixer and dry mix at 135 r / min for 2.5 min to obtain a dry mix. 2) Add the dry mixture to the pre-mixed magnesium sulfate aqueous solution and modifier mixture, and stir at 90 r / min for 4 min; then add the reinforcing fiber modified by biomimetic interface hybridization, reduce the speed to 35 r / min, and continue stirring for 2.5 min until uniformly dispersed to obtain wet core material.

[0045] This embodiment also provides a filling process for the core of a fireproof door, including the following steps: S1. Fill the door core frame 1 with the above-mentioned wet core material. The loose bulk density of the wet core material is 475 kg / m³. 3 Start the hydraulic press, press and shape the core, and carry out the process under a constant temperature of 60℃. Within 35 seconds, the pressure is increased to 2.5MPa, held for 105 minutes, and then the pressure is released within 25 seconds to obtain the pressed and shaped door core blank. Among them, the door core frame 1 is a fire-retardant wooden rectangular frame structure. The inner side of the door core frame 1 is provided with a flared groove 2 that is wider on the outside and narrower on the inside. The wet core material is embedded in the flared groove during the pressing process to form a firm mechanical interlocking structure. S2. The pressed door core blank is left to cure for 6 days at an ambient temperature of 23℃ and a relative humidity of 68% to obtain an oven-dry density of 410 kg / m³. 3 Fireproof and insulating door core finished products.

[0046] Comparative Example 1: This comparative example corresponds to Formula A, which was previously tested by the inventors, and aims to simulate traditional low-density perlite door cores. By weight, the raw materials include: 15 parts closed-cell expanded perlite, 8 parts activated magnesium oxide, and 15 parts a 25% magnesium sulfate aqueous solution. No modifiers, reinforcing fibers, or water-repellent agents were added.

[0047] The preparation method is as follows: dry mix perlite and magnesium oxide for 2 minutes, add magnesium sulfate aqueous solution and stir for 3 minutes to obtain wet material; fill the wet material into a regular flat door core frame, press it at 25℃ with 1MPa pressure, hold the pressure for 30 minutes and then demold, and let it stand for 6 days for curing.

[0048] The resulting door core density is approximately 200 kg / m³. 3 The formula has an excessively high proportion of aggregate and insufficient cementitious material, resulting in high porosity, loose structure, and extremely low compressive strength. The resulting green body has an extremely loose structure and requires careful demolding; due to the lack of sufficient cementitious material for bonding, the green body has extremely low compressive strength and will chip or break even with slight impact.

[0049] Comparative Example 2: This comparative example corresponds to Formula B, which was previously tested by the inventors. The raw materials, by weight, include: 12 parts closed-cell expanded perlite, 10 parts activated magnesium oxide, and 18 parts a 28% magnesium sulfate aqueous solution. No modifiers, reinforcing fibers, or water-repellent agents were added.

[0050] The preparation method is the same as that of Comparative Example 1. A common flat frame is used, and the mold is formed by pressing at 1 MPa at 25°C. After holding the pressure for 30 minutes, the mold is demolded and left to cure for 6 days.

[0051] The resulting door core density is approximately 220 kg / m³. 3 Although this formulation contains more cementitious materials than formulation A, it still lacks effective toughening and interfacial reinforcement methods. The compressive strength is improved but still relatively low, and the impact resistance is poor.

[0052] Comparative Example 3: This comparative example corresponds to Formula C, which was previously tested by the inventors. The raw materials, by weight, include: 8 parts closed-cell expanded perlite, 14 parts active magnesium oxide, and 25 parts a 30% magnesium sulfate aqueous solution. No modifiers, reinforcing fibers, or water-repellent agents are added.

[0053] The preparation method is the same as that of Comparative Example 1. A common flat frame is used, and the mold is formed by pressing at 1 MPa at 25°C. After holding the pressure for 30 minutes, the mold is demolded and left to cure for 6 days.

[0054] The resulting door core density is approximately 280 kg / m³. 3 This formula increases density and strength by significantly increasing the amount of cementitious materials, but it also significantly increases brittleness, has a high drying shrinkage rate, is prone to cracking, and is too heavy, which does not conform to the development trend of lightweight fire doors.

[0055] Comparative Example 4: A fireproof door core and its filling process are disclosed, differing from Example 3 only in that: no biomimetic interface hybridized reinforcing fibers are added, and their weight is replaced by an equal amount of active magnesium oxide. All other raw material ratios, modifier preparation processes, pressing, and curing processes are the same as in Example 3.

[0056] The resulting door core density is approximately 405 kg / m³. 3 Due to the lack of fiber bridging and crack-preventing effect, the material is brittle and prone to sudden fracture upon impact.

[0057] Comparative Example 5: A fireproof door core and its filling process are disclosed, differing from Example 3 only in that no modifier is added, and its weight is replaced by an equal mass of magnesium sulfate aqueous solution to maintain a basically consistent overall liquid-solid ratio in the wet core material. The remaining raw material ratios, fiber pretreatment processes, pressing, and curing processes are the same as in Example 3.

[0058] The resulting door core density is approximately 400 kg / m³. 3 Due to the lack of synergistic modification effects of aluminum dihydrogen phosphate, silica sol, and citric acid, the matrix has high porosity, poor interfacial bonding, and significantly reduced compressive strength and fire resistance.

[0059] Comparative Example 6: A fireproof door core and its filling process are different from those in Example 3 only in that the added basalt fiber is treated with silane coupling agent (KH-550) in a conventional alcohol-water solution (i.e., without the dopamine biomimetic adhesion layer coating step, it is directly reacted in an alcohol-water solution at pH 5.0 at 65°C for 3 hours), and the other raw material ratios and processes are the same as those in Example 3.

[0060] The resulting door core density is approximately 400 kg / m³. 3 Due to the lack of a polydopamine biomimetic adhesion layer on the fiber surface, the direct binding sites between the silane coupling agent and the fiber surface are limited, resulting in a low interfacial chemical bond density. Furthermore, there is no catechol-Mg bond between the fiber and the matrix. 2+ Coordination bonding leads to a significant reduction in fiber toughening efficiency, with both impact strength and compressive strength being significantly lower than in Example 3.

[0061] Comparative Example 7: A fireproof door core and its filling process are disclosed, differing from Example 3 only in that the inner side of the door core frame does not have a flared slot, and a traditional flat-to-flat structure is used. All other raw material ratios and processes are the same as in Example 3.

[0062] The resulting door core density is approximately 395 kg / m³. 3 Because the core material and the frame only have planar contact and lack mechanical interlocking, gaps are prone to appear at the joint between the core material and the frame during impact tests. In severe cases, the entire core board may shift, significantly reducing the overall impact resistance.

[0063] Comparative Example 8: This comparative example uses a commercially available brand of ordinary magnesium sulfate perlite fireproof door core board (purchased from Dongguan Wanjiang Xiangxing Fireproof Board Factory), with a nominal density of 250 kg / m³. 3 The dimensions are the same as in Example 3. This product adopts a traditional flat-mouth structure and does not use the modifier, biomimetic interface hybridized reinforcing fiber, or flared tenon and mortise structure described in this invention.

[0064] The fireproof door cores obtained in Examples 1-3 and Comparative Examples 1-8 were subjected to the following related performance tests, and the test methods are as follows: (1) Density test: The test shall be conducted in accordance with GB / T 5486-2023 "Test Methods for Inorganic Rigid Thermal Insulation Products". The sample size is 100mm×100mm×original thickness. The mass per unit volume shall be calculated.

[0065] (2) Compressive strength test: The compression test was carried out according to GB / T 5486-2023. The sample size was 100mm×100mm×original thickness. The sample was loaded at a constant rate of 10mm / min. The maximum load when the sample failed was recorded and the compressive strength was calculated.

[0066] (3) Flexural strength test: The flexural test shall be carried out in accordance with GB / T 5486-2023. The sample size is 250mm×100mm×original thickness, the span is 200mm, and the loading rate is 10mm / min.

[0067] (4) Impact resistance test: The simply supported beam impact test method was adopted. The sample size was 80mm × 10mm × original thickness. The pendulum impact tester was used to test the sample. The impact energy absorbed when the sample failed was recorded, and the impact strength (kJ / m) was calculated. 2 Simultaneously, a drop ball impact test was conducted: a 1kg steel ball was dropped freely from a height of 1m, impacting the center of the door core surface, and the number of impacts at which the sample first showed a through crack or broke was recorded.

[0068] (5) Fire resistance limit test: The fire resistance test shall be conducted in accordance with GB / T 9978.1-2019 "Fire resistance test method for building components - Part 1: General requirements". The test specimen shall be made of the same material and structure as the actual door core, with a size of 1000mm×1000mm. The time from the start of fire exposure to the loss of fire resistance integrity or heat insulation shall be recorded.

[0069] (6) Core-frame bonding strength test: Fix the core and frame assembly on a universal testing machine, apply a tensile load in a direction perpendicular to the core surface, load at a rate of 5 mm / min, and determine the maximum stress when the core and frame peel off, i.e., the core-frame bonding strength.

[0070] (7) Thermal conductivity test: The test shall be conducted in accordance with GB / T 10294-2023 "Determination of steady-state thermal resistance and related properties of thermal insulation materials by protective hot plate method".

[0071] The results are shown in Table 2.

[0072] Table 2

[0073] Using Example 3 as the control group, the performance differences and causes of Comparative Examples 1-8 are analyzed as follows: Comparative Example 1 (Formula A, 200 kg / m³) 3 The formula described in this invention is a traditional low-density formulation tested by the inventors in the early stages. It does not utilize the modifier, reinforcing fibers, compression molding, or flared frame process described in this invention. Compared to Example 3, its density is lower than that of Example 410 kg / m³.3 Reduced to 205 kg / m 3 (Decrease of 50.0%), compressive strength decreased from 1.05 MPa to 0.22 MPa (decrease of 79.0%), flexural strength decreased from 0.58 MPa to 0.12 MPa (decrease of 79.3%), and impact strength decreased from 4.5 kJ / m. 2 Reduced to 0.8 kJ / m 2 (A decrease of 82.2%), core-frame bond strength decreased from 0.41 MPa to 0.08 MPa (a decrease of 80.5%), fire resistance limit decreased from 102 min to 58 min (a decrease of 43.1%), and thermal conductivity decreased from 0.055 W / (m·K) to 0.048 W / (m·K) (a decrease of 12.7%). Due to the excessively high proportion of aggregate and the severe lack of cementitious material, there was a lack of effective bonding between perlite particles, resulting in a large number of interconnected pores inside the material, leading to extremely poor mechanical properties and structural integrity. At the same time, the low-density, loose structure could not form a dense ceramic protective layer at high temperatures, allowing heat to penetrate rapidly and insulation properties to be lost quickly, thus significantly shortening the fire resistance limit.

[0074] Comparative Example 2 (Formula B, 220 kg / m³) 3 The formula described in this invention is a traditional medium-density formulation tested by the inventors in the early stages, which does not employ the modifier, reinforcing fibers, compression molding, and flared frame process described in this invention. Compared to Example 3, its density is 410 kg / m³. 3 Reduced to 218kg / m 3 (A decrease of 46.8%), compressive strength decreased from 1.05 MPa to 0.35 MPa (a decrease of 66.7%), flexural strength decreased from 0.58 MPa to 0.18 MPa (a decrease of 69.0%), and impact strength decreased from 4.5 kJ / m. 2 Reduced to 1.2 kJ / m 2 (A decrease of 73.3%), the core-frame bond strength decreased from 0.41 MPa to 0.10 MPa (a decrease of 75.6%), the fire resistance limit decreased from 102 min to 65 min (a decrease of 36.3%), and the thermal conductivity decreased from 0.055 W / (m·K) to 0.050 W / (m·K) (a decrease of 9.1%). Although the amount of cementitious material increased compared to Comparative Example 1, it still lacked toughening components and interface reinforcement methods, resulting in significant material brittleness. Furthermore, without compression densification and tenon-and-mortise interlocking, the core-frame interface was only in planar contact, resulting in weak bonding force. Under impact or thermal stress, relative slippage easily occurred, thus the impact resistance and core-frame bond strength were both at a low level.

[0075] Comparative Example 3 (Formula C, 280 kg / m³) 3The formula described in this invention is a high-density conventional formula tested by the inventors in the early stages. It does not employ the modifiers, reinforcing fibers, compression molding, and flared frame process described in this invention; instead, it increases density solely by increasing the amount of cementitious material. Compared to Example 3, its density is 410 kg / m³. 3 Reduced to 282kg / m 3 (A decrease of 31.2%), compressive strength decreased from 1.05 MPa to 0.58 MPa (a decrease of 44.8%), flexural strength decreased from 0.58 MPa to 0.28 MPa (a decrease of 51.7%), and impact strength decreased from 4.5 kJ / m. 2 Reduced to 1.5 kJ / m 2 (Reduction of 66.7%), core-frame bond strength decreased from 0.41 MPa to 0.12 MPa (reduction of 70.7%), fire resistance limit decreased from 102 min to 72 min (reduction of 29.4%), and thermal conductivity increased from 0.055 W / (m·K) to 0.068 W / (m·K) (increase of 23.6%). Simply increasing the amount of cementitious material increases density, but also significantly increases brittleness, high drying shrinkage rate, and susceptibility to cracking. If the formulation is press-formed, its density will increase further, resulting in excessive weight, which does not conform to the trend of lightweight fire doors. At the same time, although the density of Comparative Example 3 is lower than that of Example 3, because it is not press-formed, there are a large number of interconnected open pores and drying shrinkage cracks inside the matrix, increasing convective heat transfer. In addition, the amount of cementitious material is relatively large, and the thermal conductivity of the magnesium oxysulfate cement matrix is ​​significantly higher than that of closed-cell expanded perlite, increasing the proportion of solid heat conduction paths. In Example 3, the isothermal pressing molding process transformed most of the interconnected open pores inside the matrix into closed pores, significantly reducing convective heat transfer. The modifier further filled the micropores, reducing the gas heat conduction path. Although Example 3 had a higher density, the optimization of the pore structure offset the increase in thermal conductivity caused by the increased density, resulting in an overall lower thermal conductivity.

[0076] Comparative Example 4 (without reinforcing fibers) did not contain any reinforcing fibers modified with biomimetic interface hybridization compared to Example 3. Compared to Example 3, its compressive strength decreased from 1.05 MPa to 0.78 MPa (a decrease of 25.7%), its flexural strength decreased from 0.58 MPa to 0.35 MPa (a decrease of 39.7%), and its impact strength decreased from 4.5 kJ / m. 2 Reduced to 1.8 kJ / m 2(A decrease of 60.0%), core-frame bond strength decreased from 0.41 MPa to 0.32 MPa (a decrease of 22.0%), fire resistance limit decreased from 102 min to 85 min (a decrease of 16.7%), and thermal conductivity increased from 0.055 W / (m·K) to 0.060 W / (m·K) (an increase of 9.1%). Due to the lack of bridging and crack-preventing effect of basalt fibers, the drying shrinkage rate of the matrix increased, resulting in more microcracks inside. These microcracks increase the effective path of gas heat conduction at room temperature, while disrupting the continuity of the matrix, slightly increasing the thermal resistance of solid heat conduction. However, the overall increase in gas heat conduction is dominant, so the thermal conductivity at room temperature increases slightly. At high temperatures, crack channels accelerate heat transfer and destroy structural integrity, thus significantly reducing impact resistance, flexural strength, and fire resistance limit.

[0077] Comparative Example 5 (without modifier) ​​did not contain any modifier compared to Example 3. Compared to Example 3, the compressive strength decreased from 1.05 MPa to 0.52 MPa (a decrease of 50.5%), the flexural strength decreased from 0.58 MPa to 0.25 MPa (a decrease of 56.9%), and the impact strength decreased from 4.5 kJ / m. 2 Reduced to 2.0 kJ / m 2 (A decrease of 55.6%), core-frame bonding strength decreased from 0.41 MPa to 0.22 MPa (a decrease of 46.3%), fire resistance limit decreased from 102 min to 68 min (a decrease of 33.3%), and thermal conductivity increased from 0.055 W / (m·K) to 0.065 W / (m·K) (an increase of 18.2%). Due to the lack of synergistic effects of aluminum dihydrogen phosphate, silica sol, alumina sol, and citric acid, the matrix porosity increased and the interfacial bonding weakened. The absence of aluminum dihydrogen phosphate prevented the formation of both the room-temperature cementitious phase strength and the high-temperature ceramic protective layer. The absence of silica sol resulted in ineffective filling of micropores and a lack of hydrated magnesium silicate gel reinforcement. The absence of alumina sol hindered the formation of the aluminosilicate ceramic phase at high temperatures. Therefore, the matrix compactness, interfacial bonding strength, and high-temperature residual strength were all significantly reduced.

[0078] The difference between Comparative Example 6 (untreated fiber) and Example 3 is that the added basalt fiber was only treated with a silane coupling agent using conventional alcohol and water methods, without being coated with a dopamine biomimetic adhesion layer. Compared to Example 3, its compressive strength decreased from 1.05 MPa to 0.85 MPa (a decrease of 19.0%), its flexural strength decreased from 0.58 MPa to 0.40 MPa (a decrease of 31.0%), and its impact strength decreased from 4.5 kJ / m. 2 Reduced to 2.8 kJ / m 2(A decrease of 37.8%), core-frame bonding strength decreased from 0.41 MPa to 0.28 MPa (a decrease of 31.7%), fire resistance limit decreased from 102 min to 82 min (a decrease of 19.6%), and thermal conductivity increased from 0.055 W / (m·K) to 0.059 W / (m·K) (an increase of 7.3%). Due to the lack of a polydopamine biomimetic adhesion layer on the fiber surface, the direct chemical bonding strength between the silane coupling agent and the basalt fiber surface is limited. Furthermore, the lack of mechanical interlocking and metal ion coordination provided by the polydopamine transition layer prevents the formation of a multi-level interfacial hybrid structure of "fiber-polydopamine-silane-matrix," resulting in low interfacial bonding strength. Additionally, the catechol groups and Mg... 2+ Al 3+ The lack of coordination effect leads to the fiber being prone to interfacial debonding and pull-out under stress, resulting in a significant reduction in toughening efficiency and significantly inferior impact resistance and matrix toughness compared to Example 3.

[0079] The difference between Comparative Example 7 (flat-mouth structure) and Example 3 is that the inner side of the door core frame does not have a flared groove, and a traditional flat contact structure (flat-mouth structure) is used. Compared with Example 3, the impact resistance is increased from 4.5 kJ / m 2 Reduced to 2.6 kJ / m 2 (A decrease of 42.2%), the core-frame bonding strength decreased from 0.41 MPa to 0.15 MPa (a decrease of 63.4%), and the fire resistance limit decreased from 102 min to 95 min (a decrease of 6.9%). Since the formulation and preparation process of the door core material are exactly the same as in Example 3, its intrinsic properties (compressive strength, flexural strength, thermal conductivity) are consistent with those in Example 3; however, since the core material and the frame are only in planar contact and lack mechanical interlocking, the core board can only maintain its position by interfacial friction when subjected to impact, making it very easy to slip and detach from the frame; at the same time, the flat structure is more prone to gaps at the core-frame interface under thermal expansion and contraction or the impact of fire hoses, leading to the penetration of flames and high-temperature smoke. Therefore, the overall impact resistance and structural integrity are significantly reduced, the fire resistance limit is slightly reduced, and the decrease in core-frame bonding strength is particularly prominent.

[0080] Comparative Example 8 (commercially available ordinary perlite core board) is a commercially available brand of ordinary magnesium sulfate perlite fireproof core board, without the modifier, pre-treated reinforcing fibers, and flared tenon and mortise structure described in this invention. Compared with Example 3, its density is 410 kg / m³. 3 Reduced to 248kg / m 3 (A decrease of 39.5%), compressive strength decreased from 1.05 MPa to 0.42 MPa (a decrease of 60.0%), flexural strength decreased from 0.58 MPa to 0.22 MPa (a decrease of 62.1%), and impact strength decreased from 4.5 kJ / m. 2 Reduced to 1.3 kJ / m 2(Reduction of 71.1%), core-frame bond strength decreased from 0.41 MPa to 0.09 MPa (reduction of 78.0%), and fire resistance limit decreased from 102 min to 60 min (reduction of 41.2%). Commercially available products use traditional low-density formulations and flat-mouth structures, with unoptimized cementitious systems and aggregate ratios, lacking effective toughening and reinforcing methods and interface modification, and without tenon-and-mortise interlocking between the core and frame. Therefore, they are significantly inferior to this invention in terms of mechanical properties, impact resistance, fire resistance, and structural integrity.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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. Such 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. A fireproof and insulating door core, characterized in that, It is obtained by filling the door core frame (1) with wet core material, followed by compression molding and curing. The wet core material, by weight, includes the following raw materials: 4-12 parts of closed-cell expanded perlite, 6-18 parts of active magnesium oxide, 10-30 parts of magnesium sulfate aqueous solution with a mass fraction of 25%-35%, 0.1-0.3 parts of modifier, 0.3-1.2 parts of reinforcing fiber modified by biomimetic interface hybridization, and 0.1-0.3 parts of calcium stearate.

2. The fireproof door core according to claim 1, characterized in that, The preparation method of the wet core material is as follows: 1) Add closed-cell expanded perlite, active magnesium oxide, and calcium stearate to a mixer and dry mix at 120-150 r / min for 2-3 minutes to obtain a dry mix. 2) Add the dry mixture to the pre-mixed magnesium sulfate aqueous solution and modifier mixture, and stir at 80-100 r / min for 3-5 min; then add the reinforcing fiber modified by biomimetic interface hybridization, reduce the speed to 30-40 r / min, and continue stirring for 2-3 min until uniformly dispersed to obtain wet core material.

3. The fireproof door core according to claim 1, characterized in that, The dry density of the fireproof door core is 380-420 kg / m³. 3 .

4. The fireproof door core according to claim 1, characterized in that, The closed-cell expanded perlite has a particle size of 0.5-2.5 mm and a bulk density of 110-130 kg / m³. 3 The active magnesium oxide is lightly calcined magnesium oxide with an activity ≥75%.

5. A filling process for a fireproof and insulating door core, characterized in that, Includes the following steps: S1. Fill the door core frame (1) with the wet core material according to any one of claims 1-4, wherein the loose bulk density of the wet core material is 450-500 kg / m³. 3 Start the hydraulic press to press and shape, and obtain the pressed and shaped door core blank; S2. The pressed door core blank is left to stand for 5-7 days under an ambient temperature of 18-28℃ and a relative humidity of 60%-75% to obtain the finished fireproof and insulating door core.

6. The filling process of the fireproof door core according to claim 5, characterized in that, In step S1, the compression molding is carried out under constant temperature conditions of 58-62℃, the pressure is increased to 2-3MPa within 30-40s, the pressure is held for 90-120min, and then the pressure is released within 20-30s.

7. The filling process of the fireproof door core according to claim 5, characterized in that, In step S1, the door core frame (1) is a flame-retardant wooden or metal rectangular frame structure. The inner side of the door core frame (1) is provided with a flared groove (2) that is wider on the outside and narrower on the inside. The wet core material is embedded in the flared groove during the pressing process to form a firm mechanical interlocking structure.

8. The fireproof door core according to claim 1, characterized in that, The raw materials for preparing the modifier, by mass percentage, include: 18%-25% aluminum dihydrogen phosphate, 25%-40% silica sol, 3%-8% aluminum sol, 1.5%-3.0% citric acid, and the balance being deionized water.

9. The fireproof door core according to claim 8, characterized in that, The modifier is prepared by adding aluminum dihydrogen phosphate to deionized water, heating to 55-65℃, and stirring at 300-400 r / min for 20-30 min until completely dissolved; then adding citric acid and continuing to stir for 10-15 min. Then cool to 25-35℃, stir at 200-300r / min and slowly add aluminum sol dropwise over 15-25min; after the addition is complete, continue stirring for 20-30min; then maintain the temperature and slowly add silica sol dropwise over 15-25min; after the addition is complete, continue stirring for 40-60min to obtain the modifier.

10. The fireproof door core according to claim 1, characterized in that, The biomimetic interface hybridized reinforcing fiber is a basalt fiber synergistically modified with dopamine hydrochloride-silane coupling agent, and its preparation method is as follows: (1) Prepare a Tris-HCl buffer solution with a pH of 8.0-9.0, add dopamine hydrochloride, and prepare a solution with a concentration of 1.5-2.5 g / L. Stir at 50-60 r / min for 20-24 h until the solution changes from colorless to dark brown to obtain the dopamine self-polymerization treatment solution. (2) Immerse the basalt fiber in the dopamine self-polymerization treatment solution obtained in step (1) at a solid-liquid ratio of 1:15g / mL to 1:25g / mL, and disperse it with ultrasonic assistance for 10-15 min at an ultrasonic frequency of 35-40kHz and a power of 150-250W. Then soak it at 24-28℃ for 20-28 h. After taking it out, rinse it with deionized water 3-5 times and vacuum dry it at 50-60℃ for 2-3 h to obtain basalt fiber with a polydopamine layer on the surface. (3) Prepare an alcohol-water solution containing 1.5%-3.0% silane coupling agent KH-550, 15%-25% anhydrous ethanol, and the remainder being deionized water, with the sum of the volume percentages of each component being 100% by volume. Adjust the pH to 4.5-5.5 with acetic acid solution. (4) Immerse the basalt fiber obtained in step (2) into the alcohol-water solution obtained in step (3), stir at 240-260 r / min at 60-70℃ for 2-4 h, filter under vacuum after the reaction, wash with anhydrous ethanol 3-4 times, and dry under vacuum to obtain modified basalt fiber with an organic-inorganic hybrid grafted layer on the surface.

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