Lightweight fireproof filler produced by using expanded perlite and preparation method thereof

Abstract

The invention relates to the technical field of fireproof materials, in particular to a lightweight fireproof filler produced from expanded perlite and a preparation method of the lightweight fireproof filler. 5 to 25 parts of polyvinyl alcohol; 0.5 to 10 parts of MXenes (MXenes); 1-10 parts of zinc oxide; 0.5 to 3 parts of a silane coupling agent; and 1-5 parts of composite modified layered double hydroxide. Zinc oxide catalyzes cross-linking carbonization of polyvinyl alcohol, composite modified layered double hydroxide releases flame-retardant components and participates in carbon layer enhancement, MXenes constructs a ceramic-carbon physical barrier, and gas-phase slow-release flame retardance and efficient fire retardance are synergistically achieved; and meanwhile, by virtue of a nanometer enhancement mechanism of MXenes and an interface modification effect of the silane coupling agent and metakaolin, the mechanical strength and the water resistance of the material are improved, and the problems of large weight increment, poor flexibility, limited improvement of high-temperature fireproof performance and the like of the modified expanded perlite in the prior art are solved.

Description

Technical Field

[0001] This application relates to the field of fireproof materials technology, and in particular to a method for producing lightweight fireproof filler using expanded perlite. Background Technology

[0002] Expanded perlite is a traditional inorganic lightweight thermal insulation material, characterized by its light weight, low thermal conductivity, and non-combustibility, and is widely used in building insulation, fireproofing, and other fields. However, pure expanded perlite products have inherent drawbacks, such as low strength, high water absorption, decreased thermal insulation performance after absorbing moisture, easy pulverization and detachment of particles after long-term use, and the need to improve fire resistance at high temperatures. These limitations restrict its application in some high-performance scenarios.

[0003] To improve the overall performance of expanded perlite, existing technologies typically employ physical coating or composite methods with cementitious materials (such as cement, gypsum, and water glass). However, these methods often suffer from problems such as increased weight, long curing time, poor flexibility, or limited improvement in fire resistance. For example, while cement-based composite systems improve strength, their density increases significantly, and their fire-resistant and heat-insulating performance is affected by the high-temperature cracking of the cement stone; organic binders such as ordinary polyvinyl alcohol can improve flexibility and adhesion, but they are prone to decomposition at high temperatures, leading to the collapse of the fire-resistant structure.

[0004] Two-dimensional nanomaterials, such as MXenes, exhibit great potential for reinforcing composite materials due to their excellent mechanical properties, high specific surface area, and potential barrier effects. Layered double hydroxides (LDHs), as a class of inorganic anionic flame-retardant materials, can enhance the flame retardancy of polymers through multiple mechanisms, including thermal decomposition to absorb heat, release flame-retardant gases, and form a dense char layer. How to effectively combine these advanced functional nanomaterials with traditional expanded perlite to construct a novel filler material that maintains lightweight properties while possessing excellent mechanical strength, water resistance, and high-level fire resistance is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] This application provides a method for producing lightweight fire-retardant filler using expanded perlite, in order to solve the problems of weight gain, poor flexibility, or limited improvement in high-temperature fire resistance in the prior art.

[0006] This application provides a method for producing a lightweight fire-retardant filler using expanded perlite, characterized in that, by weight, the lightweight fire-retardant filler comprises: Expanded perlite: 50-90 parts; Polyvinyl alcohol: 5-25 parts; MXenes: 0.5-10 parts; Zinc oxide: 1-10 parts; Silane coupling agent: 0.5-3 parts; Composite modified layered double hydroxide: 1-5 parts.

[0007] Optionally, the lightweight fire-retardant filler comprises, by weight: Expanded perlite: 60-80 parts; Polyvinyl alcohol: 10-20 parts; MXenes: 2-8 servings; Zinc oxide: 4-6 parts; Silane coupling agent: 1-2 parts; Composite modified layered double hydroxide: 2-4 parts.

[0008] Optionally, the composite modified layered double hydroxide is a core-shell structured composite, wherein the core layer is a magnesium aluminum hydrotalcite calcined product obtained by organic anion intercalation and calcination, and the shell layer is metakaolinite coated on its surface; based on the total weight of the composite modified layered double hydroxide, the mass percentage of metakaolinite is 10%-50%.

[0009] Optionally, the organic anionic intercalating agent is selected from at least one of dodecyl sulfate, dodecylbenzenesulfonate, terephthalate, phytate, molybdate, and borate.

[0010] Optionally, the calcination temperature is 450℃-600℃.

[0011] Optionally, the MXenes are few-layer or multi-layer Ti3C2T x , among which, T x The surface functional groups include -OH, and the MXenes are prepared by a method comprising the following steps: (1) Etching: Ti3C2MAX phase powder is added to a mixed solution of hydrochloric acid and lithium fluoride for reaction at a temperature of 35-45℃ for 20-28 hours; (2) Washing and stripping: The product obtained in step (1) was washed until neutral and then ultrasonically treated to obtain few-layer Ti3C2T x Dispersion; (3) Alkali treatment: the few-layer Ti3C2T x The dispersion was mixed with an alkaline solution of 0.5-1.5 mol / L and reacted at room temperature for 10-14 hours. After washing, Ti3C2T with surface rich in -OH functional groups was obtained. x .

[0012] Optionally, the silane coupling agent is at least one of aminosilane, epoxysilane, or methacryloxysilane.

[0013] This application also provides a method for preparing lightweight fire-retardant filler using expanded perlite, comprising the following steps: S1. Dilute the silane coupling agent with an ethanol aqueous solution with a volume concentration of 40%-60% to prepare a treatment solution with a mass concentration of 1%-3%; place the expanded perlite in a high-speed mixer, and spray the treatment solution evenly in a spray manner while stirring. After spraying, continue stirring for 10-20 minutes; then transfer the mixture to an oven and react at 70℃-90℃ for 1-2 hours to obtain silanized modified expanded perlite. S2. Preparation of functional nanocomposite slurry; S3. Add the silanized modified expanded perlite obtained in step S1 to the functional nanocomposite slurry prepared in S2, and stir at a low speed of 50-150 rpm for 10-15 minutes using a planetary mixer until the slurry is fully wetted and uniformly coats all perlite particles to obtain a mixed wet material. S4. Weigh the mixed wet material and fill it into a mold of a predetermined shape. Press it on a press at a pressure of 0.2-0.4MPa for 30-60 seconds to shape it. Place the molded blank in a forced-air drying oven and dry it at 65℃-75℃ for 3-4 hours. Then heat it to 95℃-105℃ to cure it for 2-3 hours. Finally, demold it and let it cool naturally to room temperature to obtain the lightweight fireproof filler.

[0014] Optionally, the preparation of functional nanocomposite slurry includes: S2a. Add polyvinyl alcohol to deionized water at 85℃-95℃ and prepare a transparent homogeneous adhesive solution with a mass concentration of 8%-12% under stirring. Cool to 40℃-50℃ for later use. S2b. Add MXenes powder to deionized water and disperse it by ultrasonication to obtain a primary dispersion of MXenes with a solid content of 2-4 mg / mL; under mechanical stirring, slowly add the primary dispersion of MXenes to the polyvinyl alcohol solution in step S2a for a time of not less than 15 minutes; then add zinc oxide powder and composite modified layered double hydroxide in sequence. S2c. Transfer the mixture obtained in step S2b to a high-speed shear dispersion emulsifier and shear disperse at a speed of 4000-6000 rpm for 20-30 minutes; then place the container in an ultrasonic processor and ultrasonically treat it at a power of 300-500W in pulse mode for 15-25 minutes to obtain a uniform and stable functional nanocomposite slurry.

[0015] Optionally, in step S2b, the conditions for the ultrasonic dispersion treatment are: continuous or pulsed ultrasound for 30-60 minutes at a power of 400-600W.

[0016] Therefore, this application has at least the following beneficial effects: (1) In the embodiments of this application, zinc oxide, as a highly efficient catalyst, significantly promotes the dehydration and cross-linking carbonization of polyvinyl alcohol at high temperature, providing a stable initial carbonaceous skeleton for the flame retardant system. At the same time, after intercalation and calcination, the core layer of the composite modified layered double hydroxide can rebuild the layered structure and absorb anions in the environment, while simultaneously releasing the intercalated organic / inorganic flame retardant anions (such as phytate, molybdate, etc.). These decomposition products not only exert a gas-phase flame retardant effect, but also react with the carbon layer generated by zinc oxide catalysis, enhancing in-situ cross-linking and forming a dense, firm, and highly antioxidant reinforced carbon layer; (2) The composite modified layered double hydroxide decomposes upon heating to produce water vapor and non-flammable gases (such as CO2 and NH3) produced by the decomposition of intercalated anions, which can dilute the concentration of flammable gases and reduce the surface temperature of the material. The presence of MXenes and metakaolin shell slows down the gas release rate, making the cooling and dilution effects more lasting and gentle, thus achieving the slow-release effect of gas phase flame retardancy; (3) In the embodiments of this application, the two-dimensional sheet structure of MXenes can exist stably at high temperature. Together with the enhanced carbon layer and the metal oxide generated by the decomposition of the composite modified layered double hydroxide, it forms a solid, dense "ceramic-carbon" composite physical barrier with excellent heat insulation performance at the combustion front. It can effectively block heat flow transfer, isolate oxygen and prevent the escape of internal combustible decomposition products, thereby improving the fire resistance performance from simply delaying combustion to blocking flame penetration for a long time, and achieving long-term fire resistance. (4) MXenes, as a high-performance two-dimensional nanomaterial, is uniformly dispersed in the polyvinyl alcohol matrix with its excellent mechanical properties (high modulus and high strength). Through mechanisms such as nanofilling, crack deflection, and bridging, it effectively enhances the strength and toughness of the matrix itself, thereby improving the overall compressive and flexural strength of the filler. The silane coupling agent modifies the surface of expanded perlite, changing its surface from hydrophilic to hydrophobic, and introduces organic functional groups that can form hydrogen bonds or chemical bonds with polyvinyl alcohol. The metakaolin shell of the composite modified layered double hydroxide further improves its dispersibility and compatibility in the polyvinyl alcohol matrix. This dual interface modification greatly enhances the interfacial bonding force between the inorganic filler and the organic polymer matrix, ensuring that stress can be effectively transferred from the weaker foundation to the reinforcing phase, and significantly improving the overall compressive and flexural strength of the filler. (5) In the embodiments of this application, the composite binder formed by polyvinyl alcohol and functional nano-components (MXenes, zinc oxide, and composite modified layered double hydroxides) can more completely and densely encapsulate perlite particles and fill pores. The layered structure of MXenes also increases the tortuosity of the water penetration path at the microscopic level. This together reduces the capillary absorption and internal diffusion of water, effectively inhibits the decay of thermal insulation performance, freeze-thaw damage and strength loss caused by moisture absorption, and improves the long-term service reliability in complex environments; (6) In this embodiment, perlite is first subjected to independent surface pretreatment, and then a highly stable nanocomposite slurry is prepared by "dispersing MXenes first, and then dispersing with other components by high-speed shearing and ultrasonic synergistic dispersion". Finally, low-speed mixing is used. This process prevents the agglomeration of MXenes and nanoparticles to the greatest extent and ensures that the functional components are uniformly dispersed at the nanoscale in the matrix. The low pressure (0.2-0.4MPa) for shaping avoids a large amount of breakage of brittle perlite particles. The gradient temperature curing process (first drying at low temperature to remove most of the free water, and then curing at high temperature to promote full cross-linking and crystallization of polyvinyl alcohol) effectively reduces cracking and deformation caused by rapid evaporation of moisture, making the internal structure of the product uniform and the performance stable.

[0017] This solves the problems of increased weight, poor flexibility, or limited improvement in high-temperature fire resistance in existing technologies.

[0018] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a microstructure diagram of a lightweight fire-retardant filler produced using expanded perlite according to Embodiment 4 of this application. Detailed Implementation

[0020] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0021] In the embodiments of this application, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0022] This application provides a method for producing lightweight fire-retardant fillers using expanded perlite, aiming to address the problem of limited improvement in high-temperature fire resistance. The method involves zinc oxide catalyzing the cross-linking and carbonization of polyvinyl alcohol, composite modified layered double hydroxides releasing flame-retardant components and participating in char layer reinforcement, and MXenes constructing a "ceramic-char" physical barrier, synergistically achieving gas-phase slow-release flame retardancy and high-efficiency fire resistance. Simultaneously, the nano-reinforcement mechanism of MXenes and the interfacial modification effects of silane coupling agents and metakaolinite enhance the material's mechanical strength and water resistance, ultimately solving the problems of weight gain, poor flexibility, and limited improvement in high-temperature fire resistance found in existing modified expanded perlite technologies.

[0023] The raw materials used in this application are described as follows: expanded perlite was purchased from Xinyang Zhengda New Materials Co., Ltd., polyvinyl alcohol was purchased from Anhui Wanwei High-Tech Materials Co., Ltd., and layered double hydroxide was purchased from Xi'an Ruixi Biotechnology Co., Ltd., with a purity of ≥95%.

[0024] The present application will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present application in any way.

[0025] Example 1 This application provides a method for producing a lightweight fire-retardant filler using expanded perlite, characterized in that, by weight, the lightweight fire-retardant filler comprises: Expanded perlite: 60 parts; Polyvinyl alcohol: 10 parts; MXenes: 2 servings; Zinc oxide: 4 parts; Silane coupling agent: 1 part; Composite modified layered double hydroxide: 2 parts.

[0026] Among them, the composite modified layered double hydroxide is a core-shell structured composite, wherein the core layer is a magnesium aluminum hydrotalcite calcined product obtained by organic anion intercalation and calcination treatment, and the shell layer is metakaolinite coated on its surface; based on the total weight of the composite modified layered double hydroxide, the mass ratio of metakaolinite is 10%.

[0027] The organic anionic intercalating agent is selected from dodecyl sulfate and dodecylbenzenesulfonate.

[0028] The roasting temperature is 450℃.

[0029] Among them, MXenes are few-layer or multi-layer Ti3C2T x , among which, T xThe surface functional groups are represented, including -OH, and MXenes are prepared by a method comprising the following steps: (1) Etching: Ti3C2MAX phase powder was added to a mixed solution of hydrochloric acid and lithium fluoride for reaction at a temperature of 35°C for 20 hours. (2) Washing and stripping: The product obtained in step (1) was washed until neutral and then ultrasonically treated to obtain few-layer Ti3C2T x Dispersion; (3) Alkali treatment: The few-layer Ti3C2T x The dispersion was mixed with a 0.5 mol / L alkaline solution and reacted at room temperature for 10 hours. After washing, Ti3C2T with a surface rich in -OH functional groups was obtained. x .

[0030] The silane coupling agent is an aminosilane.

[0031] This application also provides a method for preparing lightweight fire-retardant filler using expanded perlite, comprising the following steps: S1. Dilute the silane coupling agent with a 40% (v / v) ethanol aqueous solution to prepare a 1% (w / w) treatment solution; place the expanded perlite in a high-speed mixer, and spray the treatment solution evenly with a spray while stirring. After spraying, continue stirring for 10 minutes; then transfer the mixture to an oven and react at 70°C for 1 hour to obtain silanized modified expanded perlite. S2. Preparation of functional nanocomposite slurry; S3. Add the silanized modified expanded perlite obtained in step S1 to the functional nanocomposite slurry prepared in S2, and stir at a low speed of 50 rpm for 10 minutes using a planetary mixer until the slurry is fully wetted and uniformly coats all the perlite particles to obtain a mixed wet material. S4. Weigh the mixed wet material and fill it into a mold of a predetermined shape. Press it on a press at a pressure of 0.2 MPa for 30 seconds to set the shape. Place the molded blank in a forced-air drying oven and dry it at 65°C for 3 hours. Then heat it to 95°C and cure it for 2 hours. Finally, demold it and let it cool naturally to room temperature to obtain a lightweight fireproof filler.

[0032] The preparation of functional nanocomposite slurry includes: S2a. Add polyvinyl alcohol to deionized water at 85°C and prepare a transparent, homogeneous adhesive solution with a mass concentration of 8% by stirring. Cool to 40°C for later use. S2b. Add MXenes powder to deionized water and disperse it by ultrasonication to obtain a primary dispersion of MXenes with a solid content of 2 mg / mL. Under mechanical stirring, slowly add the primary dispersion of MXenes to the polyvinyl alcohol solution in step S2a for a time of not less than 15 minutes. Then add zinc oxide powder and composite modified layered double hydroxide in sequence. S2c. Transfer the mixture obtained in step S2b to a high-speed shear dispersion emulsifier and shear disperse at 4000 rpm for 20 minutes; then place the container in an ultrasonic processor and ultrasonically treat it for 15 minutes in pulse mode at 300W power to obtain a uniform and stable functional nanocomposite slurry.

[0033] In step S2b, the conditions for ultrasonic dispersion treatment are: continuous or pulsed ultrasound for 30 minutes at a power of 400W.

[0034] Example 2 This application provides a method for producing a lightweight fire-retardant filler using expanded perlite, characterized in that, by weight, the lightweight fire-retardant filler comprises: Expanded perlite: 65 parts; Polyvinyl alcohol: 12 parts; MXenes: 4 servings; Zinc oxide: 4.5 parts; Silane coupling agent: 1.2 parts; Composite modified layered double hydroxide: 2.5 parts.

[0035] Among them, the composite modified layered double hydroxide is a core-shell structured composite, wherein the core layer is a magnesium aluminum hydrotalcite calcined product obtained by organic anion intercalation and calcination treatment, and the shell layer is metakaolinite coated on its surface; based on the total weight of the composite modified layered double hydroxide, the mass proportion of metakaolinite is 20%.

[0036] The organic anionic intercalating agent is selected from terephthalate and phytate.

[0037] The roasting temperature is 500℃.

[0038] Among them, MXenes are few-layer or multi-layer Ti3C2T x , among which, T x The surface functional groups are represented, including -OH, and MXenes are prepared by a method comprising the following steps: (1) Etching: Ti3C2MAX phase powder was added to a mixed solution of hydrochloric acid and lithium fluoride for reaction at a temperature of 38°C for 22 hours. (2) Washing and stripping: The product obtained in step (1) was washed until neutral and then ultrasonically treated to obtain few-layer Ti3C2T x Dispersion; (3) Alkali treatment: The few-layer Ti3C2T x The dispersion was mixed with a 0.7 mol / L alkaline solution and reacted at room temperature for 11 hours. After washing, Ti3C2T with a surface rich in -OH functional groups was obtained. x .

[0039] The silane coupling agent is at least one of aminosilane, epoxysilane, or methacryloxysilane.

[0040] This application also provides a method for preparing lightweight fire-retardant filler using expanded perlite, comprising the following steps: S1. Dilute the silane coupling agent with a 45% (v / v) ethanol aqueous solution to prepare a 1.5% (w / w) treatment solution; place the expanded perlite in a high-speed mixer, and spray the treatment solution evenly with a spray while stirring. After spraying, continue stirring for 12 minutes; then transfer the mixture to an oven and react at 75°C for 2 hours to obtain silanized modified expanded perlite. S2. Preparation of functional nanocomposite slurry; S3. Add the silanized modified expanded perlite obtained in step S1 to the functional nanocomposite slurry prepared in S2, and stir at a low speed of 70 rpm for 11 minutes using a planetary mixer until the slurry is fully wetted and uniformly coats all perlite particles to obtain a mixed wet material. S4. Weigh the mixed wet material and fill it into a mold of a predetermined shape. Press it on a press at a pressure of 0.3MPa for 40 seconds to set the shape. Place the molded blank in a forced-air drying oven and dry it at 67℃ for 4 hours. Then heat it to 98℃ to cure it for 3 hours. Finally, demold it and let it cool naturally to room temperature to obtain a lightweight fireproof filler.

[0041] The preparation of functional nanocomposite slurry includes: S2a. Add polyvinyl alcohol to deionized water at 88°C and prepare a transparent, homogeneous adhesive solution with a mass concentration of 9% by stirring. Cool to 42°C for later use. S2b. Add MXenes powder to deionized water and disperse it by ultrasonication to obtain a primary dispersion of MXenes with a solid content of 2.5 mg / mL; under mechanical stirring, slowly add the primary dispersion of MXenes to the polyvinyl alcohol solution in step S2a for a time of not less than 15 minutes; then add zinc oxide powder and composite modified layered double hydroxide in sequence. S2c. Transfer the mixture obtained in step S2b to a high-speed shear dispersion emulsifier and shear disperse at 6000 rpm for 30 minutes; then place the container in an ultrasonic processor and ultrasonically treat it for 18 minutes in pulse mode at 400W power to obtain a uniform and stable functional nanocomposite slurry.

[0042] In step S2b, the conditions for ultrasonic dispersion treatment are: continuous or pulsed ultrasound for 35 minutes at a power of 450W.

[0043] Example 3 This application provides a method for producing a lightweight fire-retardant filler using expanded perlite, characterized in that, by weight, the lightweight fire-retardant filler comprises: Expanded perlite: 70 parts; Polyvinyl alcohol: 15 parts; MXenes: 5 servings; Zinc oxide: 5 parts; Silane coupling agent: 1.5 parts; Composite modified layered double hydroxide: 3 parts.

[0044] Among them, the composite modified layered double hydroxide is a core-shell structured composite, wherein the core layer is a magnesium aluminum hydrotalcite calcined product obtained by organic anion intercalation and calcination treatment, and the shell layer is metakaolinite coated on its surface; based on the total weight of the composite modified layered double hydroxide, the mass proportion of metakaolinite is 30%.

[0045] The organic anionic intercalating agent is selected from molybdate and borate.

[0046] The roasting temperature is 500℃.

[0047] Among them, MXenes are few-layer or multi-layer Ti3C2T x , among which, T x The surface functional groups are represented, including -OH, and MXenes are prepared by a method comprising the following steps: (1) Etching: Ti3C2MAX phase powder was added to a mixed solution of hydrochloric acid and lithium fluoride for reaction at a temperature of 40°C for 24 hours. (2) Washing and stripping: The product obtained in step (1) was washed until neutral and then ultrasonically treated to obtain few-layer Ti3C2T x Dispersion; (3) Alkali treatment: The few-layer Ti3C2T x The dispersion was mixed with a 1 mol / L alkaline solution and reacted at room temperature for 12 hours. After washing, Ti3C2T with a surface rich in -OH functional groups was obtained. x .

[0048] The silane coupling agent is at least one of aminosilane, epoxysilane, or methacryloxysilane.

[0049] This application also provides a method for preparing lightweight fire-retardant filler using expanded perlite, comprising the following steps: S1. Dilute the silane coupling agent with a 50% (v / v) ethanol aqueous solution to prepare a 2% (w / w) treatment solution; place the expanded perlite in a high-speed mixer, and spray the treatment solution evenly with a spray while stirring. After spraying, continue stirring for 15 minutes; then transfer the mixture to an oven and react at 80°C for 1.5 hours to obtain silanized modified expanded perlite. S2. Preparation of functional nanocomposite slurry; S3. Add the silanized modified expanded perlite obtained in step S1 to the functional nanocomposite slurry prepared in S2, and stir at a low speed of 100 rpm for 12 minutes using a planetary mixer until the slurry is fully wetted and uniformly coats all the perlite particles to obtain a mixed wet material. S4. Weigh the mixed wet material and fill it into a mold of a predetermined shape. Press it on a press at a pressure of 0.4 MPa for 60 seconds to set the shape. Place the molded blank in a forced-air drying oven and dry it at 75°C for 4 hours. Then heat it to 100°C and cure it for 3 hours. Finally, demold it and let it cool naturally to room temperature to obtain a lightweight fireproof filler.

[0050] The preparation of functional nanocomposite slurry includes: S2a. Add polyvinyl alcohol to deionized water at 90°C and prepare a transparent, homogeneous adhesive solution with a mass concentration of 10% by stirring. Cool to 50°C for later use. S2b. Add MXenes powder to deionized water and disperse it by ultrasonication to obtain a primary dispersion of MXenes with a solid content of 3 mg / mL; under mechanical stirring, slowly add the primary dispersion of MXenes to the polyvinyl alcohol solution in step S2a for a time of not less than 15 minutes; then add zinc oxide powder and composite modified layered double hydroxide in sequence. S2c. Transfer the mixture obtained in step S2b to a high-speed shear dispersion emulsifier and shear disperse at 6000 rpm for 30 minutes; then place the container in an ultrasonic processor and ultrasonically treat it for 25 minutes at 500W power in pulse mode to obtain a uniform and stable functional nanocomposite slurry.

[0051] In step S2b, the conditions for ultrasonic dispersion treatment are: continuous or pulsed ultrasound for 60 minutes at a power of 600W.

[0052] Example 4 This application provides a method for producing a lightweight fire-retardant filler using expanded perlite, characterized in that, by weight, the lightweight fire-retardant filler comprises: Expanded perlite: 75 parts; Polyvinyl alcohol: 18 parts; MXenes: 6 servings; Zinc oxide: 5.5 parts; Silane coupling agent: 1.8 parts; Composite modified layered double hydroxide: 3.5 parts.

[0053] Among them, the composite modified layered double hydroxide is a core-shell structured composite, wherein the core layer is a magnesium aluminum hydrotalcite calcined product obtained by organic anion intercalation and calcination treatment, and the shell layer is metakaolinite coated on its surface; based on the total weight of the composite modified layered double hydroxide, the mass proportion of metakaolinite is 40%.

[0054] The organic anionic intercalating agent is selected from dodecyl sulfate and borate.

[0055] The roasting temperature is 600℃.

[0056] Among them, MXenes are few-layer or multi-layer Ti3C2T x , among which, T x The surface functional groups are represented, including -OH, and MXenes are prepared by a method comprising the following steps: (1) Etching: Ti3C2MAX phase powder was added to a mixed solution of hydrochloric acid and lithium fluoride for reaction at a temperature of 42°C for 26 hours. (2) Washing and stripping: The product obtained in step (1) was washed until neutral and then ultrasonically treated to obtain few-layer Ti3C2T x Dispersion; (3) Alkali treatment: The few-layer Ti3C2T x The dispersion was mixed with a 1.2 mol / L alkaline solution and reacted at room temperature for 13 hours. After washing, Ti3C2T with a surface rich in -OH functional groups was obtained. x .

[0057] The silane coupling agent is methacryloxysilane.

[0058] This application also provides a method for preparing lightweight fire-retardant filler using expanded perlite, comprising the following steps: S1. Dilute the silane coupling agent with a 55% (v / v) ethanol aqueous solution to prepare a 2.5% (w / w) treatment solution; place the expanded perlite in a high-speed mixer, and spray the treatment solution evenly with a spray while stirring. After spraying, continue stirring for 18 minutes; then transfer the mixture to an oven and react at 85°C for 2 hours to obtain silanized modified expanded perlite. S2. Preparation of functional nanocomposite slurry; S3. Add the silanized modified expanded perlite obtained in step S1 to the functional nanocomposite slurry prepared in S2, and stir at a low speed of 120 rpm for 14 minutes using a planetary mixer until the slurry is fully wetted and uniformly coats all perlite particles to obtain a mixed wet material. S4. Weigh the mixed wet material and fill it into a mold of a predetermined shape. Press it on a press at a pressure of 0.4 MPa for 60 seconds to shape it. Place the molded blank in a forced-air drying oven and dry it at 75°C for 4 hours. Then heat it to 105°C to cure it for 3 hours. Finally, demold it and let it cool naturally to room temperature to obtain a lightweight fireproof filler.

[0059] The preparation of functional nanocomposite slurry includes: S2a. Add polyvinyl alcohol to deionized water at 93°C and prepare a transparent, homogeneous adhesive solution with a mass concentration of 11% by stirring. Cool to 50°C for later use. S2b. Add MXenes powder to deionized water and disperse it by ultrasonication to obtain a primary dispersion of MXenes with a solid content of 4 mg / mL; under mechanical stirring, slowly add the primary dispersion of MXenes to the polyvinyl alcohol solution in step S2a for a time of not less than 15 minutes; then add zinc oxide powder and composite modified layered double hydroxide in sequence. S2c. Transfer the mixture obtained in step S2b to a high-speed shear dispersion emulsifier and shear disperse at 6000 rpm for 30 minutes; then place the container in an ultrasonic processor and ultrasonically treat it for 22 minutes at 500W power in pulse mode to obtain a uniform and stable functional nanocomposite slurry.

[0060] In step S2b, the conditions for ultrasonic dispersion treatment are: continuous or pulsed ultrasound for 60 minutes at a power of 600W.

[0061] Example 5 This application provides a method for producing a lightweight fire-retardant filler using expanded perlite, characterized in that, by weight, the lightweight fire-retardant filler comprises: Expanded perlite: 80 parts; Polyvinyl alcohol: 20 parts; MXenes: 8 servings; Zinc oxide: 6 parts; Silane coupling agent: 2 parts; Composite modified layered double hydroxide: 4 parts.

[0062] Among them, the composite modified layered double hydroxide is a core-shell structured composite, wherein the core layer is a magnesium aluminum hydrotalcite calcined product obtained by organic anion intercalation and calcination treatment, and the shell layer is metakaolinite coated on its surface; based on the total weight of the composite modified layered double hydroxide, the mass ratio of metakaolinite is 50%.

[0063] The organic anionic intercalating agent is selected from terephthalate and molybdate.

[0064] The roasting temperature is 600℃.

[0065] Among them, MXenes are few-layer or multi-layer Ti3C2T x , among which, T x The surface functional groups are represented, including -OH, and MXenes are prepared by a method comprising the following steps: (1) Etching: Ti3C2MAX phase powder was added to a mixed solution of hydrochloric acid and lithium fluoride for reaction at a temperature of 45°C for 28 hours. (2) Washing and stripping: The product obtained in step (1) was washed until neutral and then ultrasonically treated to obtain few-layer Ti3C2T x Dispersion; (3) Alkali treatment: The few-layer Ti3C2T x The dispersion was mixed with a 1.5 mol / L alkaline solution and reacted at room temperature for 14 hours. After washing, Ti3C2T with a surface rich in -OH functional groups was obtained. x .

[0066] The silane coupling agent is an epoxy silane.

[0067] This application also provides a method for preparing lightweight fire-retardant filler using expanded perlite, comprising the following steps: S1. Dilute the silane coupling agent with a 60% (v / v) ethanol aqueous solution to prepare a 3% (w / w) treatment solution; place the expanded perlite in a high-speed mixer, and spray the treatment solution evenly with a spray while stirring. After spraying, continue stirring for 20 minutes; then transfer the mixture to an oven and react at 90°C for 2 hours to obtain silanized modified expanded perlite. S2. Preparation of functional nanocomposite slurry; S3. Add the silanized modified expanded perlite obtained in step S1 to the functional nanocomposite slurry prepared in S2, and stir at a low speed of 150 rpm for 15 minutes using a planetary mixer until the slurry is fully wetted and uniformly coats all the perlite particles to obtain a mixed wet material. S4. Weigh the mixed wet material and fill it into a mold of a predetermined shape. Press it on a press at a pressure of 0.4 MPa for 60 seconds to shape it. Place the molded blank in a forced-air drying oven and dry it at 75°C for 4 hours. Then heat it to 105°C to cure it for 3 hours. Finally, demold it and let it cool naturally to room temperature to obtain a lightweight fireproof filler.

[0068] The preparation of functional nanocomposite slurry includes: S2a. Add polyvinyl alcohol to deionized water at 95°C and prepare a transparent, homogeneous adhesive solution with a mass concentration of 12% by stirring. Cool to 50°C for later use. S2b. Add MXenes powder to deionized water and disperse it by ultrasonication to obtain a primary dispersion of MXenes with a solid content of 4 mg / mL; under mechanical stirring, slowly add the primary dispersion of MXenes to the polyvinyl alcohol solution in step S2a for a time of not less than 15 minutes; then add zinc oxide powder and composite modified layered double hydroxide in sequence. S2c. Transfer the mixture obtained in step S2b to a high-speed shear dispersion emulsifier and shear disperse at 6000 rpm for 30 minutes; then place the container in an ultrasonic processor and ultrasonically treat it for 25 minutes at 500W power in pulse mode to obtain a uniform and stable functional nanocomposite slurry.

[0069] In step S2b, the conditions for ultrasonic dispersion treatment are: continuous or pulsed ultrasound for 60 minutes at a power of 600W.

[0070] Comparative Example 1 A lightweight fireproof filler produced using expanded perlite differs from Example 1 in that it uses an equal amount of unmodified ordinary carbonate intercalated magnesium aluminum hydrotalcite instead of the composite modified layered double hydroxide, while the other materials are the same as in Example 1.

[0071] Comparative Example 2 A lightweight fire-retardant filler produced using expanded perlite is different from Example 1 in that it does not contain MXenes, and the reduced amount of MXenes is distributed in the expanded perlite. The other materials are the same as in Example 1.

[0072] Comparative Example 3 A lightweight fire-retardant filler produced using expanded perlite differs from Example 1 only in that it does not contain composite modified layered double hydroxides and MXenes. The reduced amount of composite modified layered double hydroxides and MXenes is distributed in the expanded perlite, while the remaining materials are the same as in Example 1.

[0073] Performance testing The lightweight fire-retardant fillers prepared from expanded perlite in Examples 1-5 and Comparative Examples 1-3 were tested, and the performance test results are shown in Tables 1 and 2 below.

[0074] Table 1 Basic Physical Properties of Lightweight Fire-Resistant Filler

[0075] Table 2 Water Resistance and Fire Resistance of Lightweight Fire-Resistant Fillers

[0076] As shown in Tables 1 and 2, the lightweight fire-retardant fillers prepared in Examples 1-5 of this application exhibit excellent comprehensive performance while maintaining low density (265-315 kg / m³). With the optimized adjustment of the content of functional nanocomponents (MXenes and composite modified layered double hydroxides), the material properties show regular changes.

[0077] Among them, such as Figure 1 As shown, Example 4, with optimal performance, achieved a balance and breakthrough in various core indicators: its dry density was 305 kg / m³, while optimizing the pore distribution, achieving a compressive strength of 2.5 MPa, a volumetric water absorption rate as low as 5.2%, and a thermal conductivity of 0.060 W / (m·K). Particularly noteworthy is its fire resistance limit of up to 70 minutes, a combustion rating of A2, and a smoke density rating of 8, indicating that the material not only possesses highly efficient fireproof and heat-insulating capabilities but also offers the safety advantage of low smoke characteristics. However, both insufficient and excessive amounts of components can affect performance; compared to Example 4, Example 5 showed a slight decline. This is mainly due to two reasons: firstly, the addition of excessive nanofillers may slightly exceed the ideal load-bearing and encapsulation capacity of the matrix, increasing the risk of local agglomeration and affecting reinforcement efficiency and dispersion uniformity; secondly, an excessively high proportion of functional fillers may have a subtle impact on the continuity of the binder network and the stability of the molding process. This phenomenon precisely confirms that the formulation in Example 4 achieved the best balance between the enhancing effect and the feasibility of the process. Too little component will result in insufficient performance, while too much component may lead to non-linear performance growth or even a slight decrease due to processability and dispersibility issues.

[0078] In contrast, Comparative Example 1 (using ordinary LDH) showed significantly worse fire resistance (32 minutes) and smoke suppression performance (smoke density level 28) than Example 1, confirming the key role of core-shell structured composite modified LDH in synergistic flame retardancy, enhanced char layer, and slow-release smoke suppression. Comparative Example 2 (without MXenes) exhibited a significant decrease in mechanical properties (compressive strength 1.0 MPa) and fire resistance (25 minutes), highlighting the indispensability of MXenes in nano-reinforcement, constructing a "ceramic-char" physical barrier, and improving water resistance. Comparative Example 3 (without either component) showed the worst performance across the board, fully demonstrating the synergistic effect of the composite modified layered double hydroxide and MXenes; its overall performance improvement is far more than a simple additive effect of a single component.

[0079] In summary, this invention utilizes the synergistic effect of polyvinyl alcohol, MXenes, and a composite modified layered double hydroxide to form a composite binder that can densely and completely encapsulate expanded perlite particles and fill the pores between them. This not only enhances the bonding force between particles and improves mechanical properties, but more importantly, it optimizes the microstructure of the material: while maintaining an appropriate amount of porosity conducive to lightweight and thermal insulation, it promotes the development of pores into a finer and more closed morphology. This structure effectively blocks capillary channels of moisture, giving the material excellent hydrophobicity; at the same time, it facilitates the formation of a continuous and dense 'ceramic-carbon' barrier layer at high temperatures, sealing the pores within the protective layer, thereby significantly improving the fire resistance limit.

[0080] According to the embodiments of this application, a method for producing lightweight fire-retardant filler using expanded perlite is proposed. In this method, zinc oxide catalyzes the cross-linking and carbonization of polyvinyl alcohol, composite modified layered double hydroxides release flame-retardant components and participate in carbon layer reinforcement, and MXenes constructs a "ceramic-carbon" physical barrier to synergistically achieve gas-phase slow-release flame retardancy and high-efficiency fire resistance. At the same time, by utilizing the nano-reinforcement mechanism of MXenes and the interfacial modification effect of silane coupling agents and metakaolin, the mechanical strength and water resistance of the material are improved, ultimately solving the problems of weight gain, poor flexibility, and limited improvement in high-temperature fire resistance performance of modified expanded perlite in the prior art.

[0081] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

[0082] The present application and its embodiments have been described above. This description is not restrictive, and the actual application is not limited thereto. In conclusion, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of this application, such design should fall within the protection scope of this application.

Claims

1. A lightweight fire-retardant filler produced using expanded perlite, characterized in that, The lightweight fire-retardant filler comprises, by weight: Expanded perlite: 50-90 parts; Polyvinyl alcohol: 5-25 parts; MXenes: 0.5-10 parts; Zinc oxide: 1-10 parts; Silane coupling agent: 0.5-3 parts; Composite modified layered double hydroxide: 1-5 parts.

2. The lightweight fire-retardant filler produced using expanded perlite according to claim 1, characterized in that, The lightweight fire-retardant filler comprises, by weight: Expanded perlite: 60-80 parts; Polyvinyl alcohol: 10-20 parts; MXenes: 2-8 servings; Zinc oxide: 4-6 parts; Silane coupling agent: 1-2 parts; Composite modified layered double hydroxide: 2-4 parts.

3. The lightweight fire-retardant filler produced using expanded perlite according to claim 2, characterized in that, The composite modified layered double hydroxide is a core-shell structured composite, wherein the core layer is a magnesium aluminum hydrotalcite calcined product obtained by organic anion intercalation and calcination treatment, and the shell layer is metakaolinite coated on its surface; based on the total weight of the composite modified layered double hydroxide, the mass percentage of metakaolinite is 10%-50%.

4. The lightweight fire-retardant filler produced using expanded perlite according to claim 3, characterized in that, The organic anionic intercalating agent is selected from at least one of dodecyl sulfate, dodecylbenzenesulfonate, terephthalate, phytate, molybdate, and borate.

5. The lightweight fire-retardant filler produced using expanded perlite according to claim 3, characterized in that, The calcination temperature is 450℃-600℃.

6. The lightweight fire-retardant filler produced using expanded perlite according to claim 1, characterized in that, The MXenes are few-layer or multi-layer Ti3C2T x , among which, T x The surface functional groups include -OH, and the MXenes are prepared by a method comprising the following steps: (1) Etching: Ti3C2MAX phase powder is added to a mixed solution of hydrochloric acid and lithium fluoride for reaction at a temperature of 35-45℃ for 20-28 hours; (2) Washing and stripping: The product obtained in step (1) was washed until neutral and then ultrasonically treated to obtain few-layer Ti3C2T x Dispersion; (3) Alkali treatment: the few-layer Ti3C2T x The dispersion was mixed with an alkaline solution of 0.5-1.5 mol / L and reacted at room temperature for 10-14 hours. After washing, Ti3C2T with surface rich in -OH functional groups was obtained. x .

7. The lightweight fire-retardant filler produced using expanded perlite according to claim 1, characterized in that, The silane coupling agent is at least one of aminosilane, epoxysilane, or methacryloxysilane.

8. A method for preparing lightweight fire-retardant filler using expanded perlite as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Dilute the silane coupling agent with an ethanol aqueous solution with a volume concentration of 40%-60% to prepare a treatment solution with a mass concentration of 1%-3%; place the expanded perlite in a high-speed mixer, and spray the treatment solution evenly in a spray manner while stirring. After spraying is completed, continue stirring for 10-20 minutes. The mixture was then transferred to an oven and reacted at 70℃-90℃ for 1-2 hours to obtain silanized modified expanded perlite. S2. Preparation of functional nanocomposite slurry; S3. Add the silanized modified expanded perlite obtained in step S1 to the functional nanocomposite slurry prepared in S2, and stir at a low speed of 50-150 rpm for 10-15 minutes using a planetary mixer until the slurry is fully wetted and uniformly coats all perlite particles to obtain a mixed wet material. S4. Weigh the mixed wet material and fill it into a mold of a predetermined shape. Press it on a press at a pressure of 0.2-0.4MPa for 30-60 seconds to shape it. Place the molded blank in a forced-air drying oven and dry it at 65℃-75℃ for 3-4 hours. Then heat it to 95℃-105℃ to cure it for 2-3 hours. Finally, demold it and let it cool naturally to room temperature to obtain the lightweight fireproof filler.

9. The method for preparing lightweight fire-retardant filler using expanded perlite according to claim 8, characterized in that, Preparation of functional nanocomposite slurries, including: S2a. Add polyvinyl alcohol to deionized water at 85℃-95℃ and prepare a transparent homogeneous adhesive solution with a mass concentration of 8%-12% under stirring. Cool to 40℃-50℃ for later use. S2b. Add MXenes powder to deionized water and disperse it by ultrasonication to obtain a primary dispersion of MXenes with a solid content of 2-4 mg / mL; under mechanical stirring, slowly add the primary dispersion of MXenes to the polyvinyl alcohol solution in step S2a for a time of not less than 15 minutes; then add zinc oxide powder and composite modified layered double hydroxide in sequence. S2c. Transfer the mixture obtained in step S2b to a high-speed shear dispersion emulsifier and shear disperse at a speed of 4000-6000 rpm for 20-30 minutes; then place the container in an ultrasonic processor and ultrasonically treat it at a power of 300-500W in pulse mode for 15-25 minutes to obtain a uniform and stable functional nanocomposite slurry.

10. The method for preparing lightweight fire-retardant filler using expanded perlite according to claim 9, characterized in that, In step S2b, the conditions for ultrasonic dispersion treatment are: continuous or pulsed ultrasound for 30-60 minutes at a power of 400-600W.

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