Flexible fireproof material and preparation method thereof

Abstract

The invention relates to the technical field of fireproof materials, and discloses a flexible fireproof material and a preparation method thereof. The flexible fireproof material comprises the following components in parts by mass: 15-30 parts of stainless steel foil, 35-55 parts of an expansion material, 10-20 parts of nano aluminum oxide sol and 5-15 parts of a heat-proof coating, the expansion material comprises one or more of expanded graphite, expanded vermiculite or expanded perlite; the nano aluminum oxide sol is obtained by dissolving aluminum nitrate and citric acid in water, adding lactic acid and mixing; the heatproof coating includes ceramic particles, a flame retardant, and a silicone resin. Stainless steel foils and expansion materials which are alternately stacked in the flexible fireproof material are bonded through nanometer aluminum oxide sol, and the outermost layer of the flexible fireproof material is coated with a heat-proof coating. The flexible fireproof material has strength, flexibility and excellent fireproof and heat-insulating properties.

Description

Technical Field

[0001] This invention relates to the field of fire-resistant materials technology, and more specifically, to a flexible fire-resistant material and its preparation method. Background Technology

[0002] Fire hazards are ubiquitous in industrial production and daily life, making the application of fire-resistant materials crucial for protecting life and property. Especially in special circumstances, such as the fire protection of cables, pipes, and equipment, flexible fire-resistant materials are needed to conform to the shapes of the objects being protected.

[0003] There are many types of existing flexible fireproof materials: intumescent fireproof coatings, composite fiber materials, etc. Intumescent fireproof coatings can expand at high temperatures to form a heat insulation layer, but the strength and ablation resistance of the coating itself need to be improved; composite fiber materials usually have good flexibility, but it is difficult to balance fire resistance and structural stability; there is a contradiction between flexibility and fire resistance, such as the poor flexibility of glass fiber-based materials and the insufficient high-temperature resistance of organic flame retardants; the interlayer bonding is not strong, such as conventional resin adhesives softening above 200°C, leading to interlayer delamination; the surface has poor weather resistance, such as being susceptible to humidity / ultraviolet radiation after long-term exposure, resulting in a decrease in fire resistance.

[0004] The application of nanomaterials offers new avenues for improving the performance of fire-resistant materials. Nano-alumina sol possesses excellent bonding properties and high-temperature resistance, and has already been used in fields such as refractory binders. Using nano-alumina sol for interlayer bonding in multilayer fire-resistant materials is expected to improve interlayer bond strength and overall fire resistance.

[0005] Based on this, the present invention aims to provide a flexible fireproof material and its preparation method, which adopts an alternating layered structure of stainless steel foil and expansion material, is bonded by nano-alumina sol, and is coated with a heat-resistant coating on the outermost layer, in order to solve the shortcomings of existing flexible fireproof materials in terms of strength, fire resistance and structural stability. Summary of the Invention

[0006] In view of this, the present invention proposes a flexible fireproof material and its preparation method, aiming to solve the problems of insufficient strength, poor fireproof performance and poor structural stability of existing flexible fireproof materials in the current technology.

[0007] To achieve the above objectives, the present invention provides a flexible fire-resistant material, which comprises the following components in parts by weight: 15-30 parts stainless steel foil, 35-55 parts expanded material, 10-20 parts nano alumina sol, and 5-15 parts heat-resistant coating; The stainless steel foil and the expansion material are arranged in an alternating layered structure, and the layers are bonded together by the nano-alumina sol. The heat-resistant coating is applied to the outermost layer.

[0008] Furthermore, the expanded material is one or more of expanded graphite, expanded vermiculite, or expanded perlite, with a particle size of 100-300 mesh and a thickness of 0.1-0.5 mm.

[0009] Furthermore, the preparation method of the nano-alumina sol is as follows: Aluminum nitrate and ammonium citrate are dissolved in water at a mass ratio of 1:0.8-1.2 and mixed to obtain a premix. Add 0.5-2 wt% lactic acid to the premix, stir evenly, and adjust the pH value to obtain the nano-alumina sol.

[0010] Furthermore, the heat-resistant coating comprises the following components by mass fraction: Ceramic particles 20-30%, flame retardant 5-10%, silicone resin 60-75%; The ceramic particles are selected from one or two of titanium dioxide and silicon dioxide; The flame retardant is selected from one or two of aluminum hydroxide and phosphorus-based flame retardants.

[0011] Furthermore, the stainless steel foil has a thickness of 0.05-0.2 mm, and the surface of the stainless steel foil has an oxide layer with a thickness of 1-5 μm.

[0012] Furthermore, a method for preparing a flexible fire-resistant material includes the following steps: (1) Pretreatment: The stainless steel foil is cleaned to remove surface oil and impurities; (2) Preparation of nano-alumina sol: The nano-alumina sol is prepared at a solid content of 20%-40% and the pH value is adjusted to 3.5-11; (3) Lamination and composite: The surface of the pretreated stainless steel foil in step (1) is uniformly coated with the nano alumina sol in step (2), and the expansion material is laid on the surface of the stainless steel foil coated with the nano alumina sol. The stainless steel foil and the expansion material are alternately laminated to form a laminate. (4) Curing and molding: The laminate described in step (3) is cured under high pressure heating conditions; (5) Applying a heat-resistant coating: Apply a heat-resistant coating to the outermost layer of the cured laminate and dry it to obtain a flexible fireproof material.

[0013] Furthermore, the cleaning process in step (1) is ultrasonic cleaning in ethanol, and the ultrasonic cleaning parameters are: ultrasonic frequency 8~40 kHz, time 15-30 minutes, temperature 40~60℃; after cleaning, it is dried at 60-80℃ for 5-10 minutes. Furthermore, in the laminated body described in step (3), the number of stainless steel foil layers is 2-5, and the number of expansion material layers is 1-4; the coating method of the nano alumina sol is dip coating, spray coating or scraping coating, the coating thickness is 5-20μm, and the coating amount is 50-100g / m².

[0014] Furthermore, the curing process in step (4) is carried out under the protection of an inert gas, wherein the inert gas is nitrogen and the oxygen concentration in the nitrogen environment is 10~100ppm; the curing parameters are: pressure 0.5-2MPa, temperature 70-80℃, and time 25-30min.

[0015] Furthermore, the coating method in step (5) is electrostatic rotary cup spraying, with a coating thickness of 0.1-0.3 mm; the drying method is infrared drying, with the infrared drying employing a gradient temperature increase of 6~8℃ / min to 180-200℃.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention employs an alternating layered structure of stainless steel foil and expanding material, combined with the excellent bonding properties of nano-alumina sol, giving the material both good flexibility and high structural strength and interlayer bonding strength. The oxide layer on the surface of the stainless steel foil further improves its compatibility with the adhesive and enhances the interlayer bonding force.

[0017] 2. This invention uses one or more of expanded graphite, expanded vermiculite, or expanded perlite as the expanding material. Expanded graphite expands rapidly at high temperatures, increasing the interlayer distance from nanometers to millimeters, forming a loose, porous, worm-like structure. This worm-like structure has a certain degree of elasticity and, when combined with flexible materials, does not significantly reduce the material's flexibility or foldability, thus meeting the mechanical requirements of flexible fire-resistant materials. Expanded vermiculite, after high-temperature calcination, undergoes interlayer moisture vaporization, causing interlayer separation and forming a loose, porous, scaly or fibrous structure. Air is trapped within this porous structure. With extremely low thermal conductivity and inorganic components that do not decompose at high temperatures, it can maintain its insulation performance for a long time during a fire, protecting the substrate from high-temperature damage. The flake / fibrous structure can be evenly dispersed in the flexible substrate, inhibiting the shrinkage or deformation of the substrate at high temperatures without affecting the material's flexibility. Expanded perlite forms a large number of closed honeycomb-like pores after expanding at high temperatures, which can effectively block heat convection and heat conduction, improving insulation efficiency. These materials have good expansion properties and insulation effects, and can expand at high temperatures to form a dense insulation layer, preventing heat transfer.

[0018] 3. As an inorganic binder, nano-alumina sol has good high-temperature resistance, avoiding the problem of organic binders easily decomposing and failing at high temperatures, and improving the stability of materials in high-temperature environments.

[0019] 4. The heat-resistant coating incorporates ceramic particles, flame retardants, and silicone resin. The ceramic particles, consisting of one or both titanium dioxide and silicon dioxide, can block heat transfer through their porous or dense structure, reducing the conduction of external high temperatures to the coating interior and substrate. The flame retardants, consisting of one or both aluminum hydroxide and phosphorus-based flame retardants, release flame-retardant gases to dilute oxygen or capture free radicals in the combustion reaction, terminating the combustion chain reaction and reducing the likelihood of the coating itself igniting. The silicone resin, through its adhesiveness and curing reaction, firmly bonds the ceramic particles, flame retardants, and other dispersed phases together to form a continuous and uniform coating, preventing component detachment. The synergistic effect of these three components gives the heat-resistant coating high-temperature resistance, heat insulation, flame retardancy, structural stability, and flexible adaptability, providing reliable outer protection for the overall fireproof material. This not only improves the coating's hardness and scratch resistance but also enhances the overall fireproof and flame-retardant effect, extending the material's service life.

[0020] 5. The infrared drying method using gradient heating can improve the integrity of the coating structure, increase drying efficiency, reduce energy consumption costs, ensure the functional stability of the coating, extend the service life of the material, adapt to the characteristics of flexible substrates, and ensure the overall flexibility of the material.

[0021] 6. The preparation method of the present invention is simple, easy to operate and industrialized. By reasonably controlling the parameters of each step, the performance stability and consistency of the material can be ensured. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0023] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0027] This invention provides a flexible fire-resistant material, which comprises the following components by mass fraction: 15-30 parts stainless steel foil, 35-55 parts expanded material, 10-20 parts nano alumina sol, and 5-15 parts heat-resistant coating; The stainless steel foil and the expansion material are arranged in an alternating layered structure, and the layers are bonded together by the nano-alumina sol. The heat-resistant coating is applied to the outermost layer.

[0028] The flexible fireproof material described in this invention is further preferably composed of the following components by mass fraction: 20-30 parts stainless steel foil, 40-50 parts intumescent material, 10-15 parts nano-alumina sol, and 10-15 parts heat-resistant coating.

[0029] The expanded material of the present invention is one or more of expanded graphite, expanded vermiculite or expanded perlite, with a particle size of 100-300 mesh and a thickness of 0.1-0.5 mm.

[0030] This invention incorporates an expandable material into the flexible fireproof material. The expandable material is selected from one or more of expanded graphite, expanded vermiculite, or expanded perlite. Expanded graphite expands rapidly at high temperatures, increasing the interlayer distance from nanometers to millimeters, forming a loose, porous, worm-like structure. This worm-like structure possesses a certain degree of elasticity and, when combined with the flexible material, does not significantly reduce the material's flexibility or foldability, thus meeting the mechanical requirements of the flexible fireproof material. Expanded vermiculite, after high-temperature calcination, undergoes interlayer moisture vaporization, causing interlayer separation and forming a loose, porous flake or fibrous structure. In fire conditions, the air within its porous structure is sealed, resulting in extremely low thermal conductivity, and the inorganic components do not decompose at high temperatures, protecting the substrate from high-temperature damage. The flake / fibrous structure can be uniformly dispersed within the flexible substrate, inhibiting shrinkage or deformation of the substrate at high temperatures without affecting the material's flexibility, thus maintaining its thermal insulation performance for an extended period during a fire. Expanded perlite, after high-temperature expansion, forms numerous closed honeycomb-like pores inside, effectively blocking heat convection and conduction in fire conditions, thereby improving thermal insulation efficiency. The expandable material can expand at high temperatures to form a dense heat insulation layer, the stainless steel foil can provide support and resist ablation, and the heat-resistant coating can effectively block external heat. The three work together to give the material excellent fireproof and heat insulation properties, which can effectively delay heat transfer and protect the covered object in the event of a fire.

[0031] The preparation method of the nano-alumina sol of the present invention is as follows: Aluminum nitrate and ammonium citrate are dissolved in 60-70 wt% water at a mass ratio of 1:0.8-1.2 and mixed to obtain a premix. Add 0.5-2 wt% lactic acid to the premix, stir evenly, and adjust the pH value to obtain the nano-alumina sol.

[0032] This invention adds nano-alumina sol to the flexible fireproof material. The nano-alumina sol is prepared by mixing aluminum nitrate, ammonium citrate, water, and lactic acid. Aluminum nitrate provides uniformly dispersed Al³⁺, ensuring the sol's material basis. Ammonium citrate regulates hydrolysis and stabilizes particles through strong chelation, and is environmentally friendly. Lactic acid acts as an auxiliary optimizer, enhancing complexation stability, improving flowability, and inhibiting aggregation, further improving the sol's overall performance. The synergistic effect of these three components produces a nano-alumina sol with uniform particle size and high stability. As a binder, the prepared nano-alumina sol exhibits low viscosity, high transparency, good dispersibility, and good permeability, ensuring a strong bond between stainless steel foil and the expansion material. When the water evaporates, the colloidal particles firmly adhere to the object's surface, forming aluminum-oxygen bonds between the particles, greatly improving the bonding strength.

[0033] The heat-resistant coating of this invention comprises the following components by mass fraction: Ceramic particles 20-30%, flame retardant 5-10%, silicone resin 60-75%; The ceramic particles are selected from one or two of titanium dioxide and silicon dioxide; The flame retardant is selected from one or two of aluminum hydroxide and phosphorus-based flame retardants.

[0034] The heat-resistant coating described in this invention is further preferably composed of the following components by mass fraction: 25-30% ceramic particles, 6-8% flame retardant, and 62-69% organosilicon resin.

[0035] This invention adds a heat-resistant coating to the flexible fireproof material. This heat-resistant coating, through its high-temperature resistance, directly blocks the transfer of external high temperatures to the material's interior and the protected object, reducing heat conduction efficiency and delaying the temperature rise of the protected object. It also prevents the core functional components inside the material, such as the expansion material and stainless steel foil, from failing due to overheating in the initial high-temperature phase, ensuring that the expansion material can stably perform its expansion and foaming function at a suitable temperature. Simultaneously, it protects the structural integrity of the stainless steel foil to maintain its physical barrier properties. In synergy with components such as nano-alumina sol, it further enhances the overall high-temperature resistance and thermal stability of the material, reduces thermal oxidation or decomposition at high temperatures, extends fire protection time, and strengthens resistance to flames and high temperatures.

[0036] In this invention, the heat-resistant coating comprises ceramic particles, a flame retardant, and silicone resin. The ceramic particles are one or both of titanium dioxide and silicon dioxide, possessing low thermal conductivity. Their porous or dense structure blocks heat transfer, reducing the conduction of external high temperatures to the coating interior and substrate. They are not easily melted or decomposed at high temperatures, maintaining the integrity of the coating's physical structure and preventing softening or collapse due to high temperatures, thus avoiding the failure of the heat insulation barrier. The high hardness of the ceramic particles enhances the wear and impact resistance of the coating surface, extending its service life. The flame retardant is one or both of aluminum hydroxide and phosphorus-based flame retardants. By releasing flame-retardant gases to dilute oxygen or capturing free radicals in the combustion reaction, it terminates the combustion chain reaction, reducing the likelihood of the coating itself igniting. At high temperatures, the flame retardant promotes the formation of a dense char layer or an inflatable heat-insulating layer in the coating, further enhancing its heat resistance. The coating acts as a barrier against heat and oxygen transfer, protecting the underlying material. It decomposes or dilutes flammable components through heat absorption, lowering the temperature of the combustion zone and slowing the ignition rate of the material. The silicone resin, through its adhesiveness and curing reaction, firmly bonds the ceramic particles, flame retardants, and other dispersed phases together, forming a continuous and uniform coating that prevents component detachment. The silicone resin exhibits excellent high-temperature resistance (long-term operating temperature up to 200-300℃, short-term resistance to even higher temperatures), is not easily decomposed at high temperatures, and maintains the integrity of the coating. Simultaneously, the silicon-oxygen bonds (Si-O) in its molecules may further cross-link at high temperatures to form a more stable silicon-oxygen skeleton, enhancing the coating's heat resistance. The silicone resin has strong adhesion to substrates (such as stainless steel foil) and possesses a certain degree of flexibility after curing, adapting to the bending and folding requirements of flexible fireproof materials and preventing the coating from cracking due to material deformation. The synergistic effect of these three factors gives the heat-resistant coating high-temperature resistance, heat insulation, flame retardancy, structural stability, and flexible adaptability, providing reliable outer protection for the overall fireproof material.

[0037] The present invention adds ceramic particles to the flexible fireproof material. The selection of the mass fraction of ceramic particles is as follows: when the mass fraction of ceramic particles is <20%, the reflection / high temperature resistance effect is insufficient; when the mass fraction of ceramic particles is >30%, the flexibility of the coating decreases.

[0038] The present invention adds a flame retardant to the flexible fireproof material. When the amount of the flame retardant is less than 5%, the flame retardant effect is insufficient; when the amount of the flame retardant is greater than 10%, it affects the adhesion between the coating and the substrate, reduces the fluidity of the coating, and makes it easy to produce pinholes during coating.

[0039] This invention does not impose any specific limitations on the type of organosilicon resin; any resin well-known to those skilled in the art may be used.

[0040] This invention does not impose any specific limitations on the type of flame retardant; any type well known to those skilled in the art may be used.

[0041] The stainless steel foil of the present invention has a thickness of 0.05-0.2 mm, and the surface of the stainless steel foil has an oxide layer with a thickness of 1-5 μm.

[0042] The flexible fireproof material of the present invention incorporates stainless steel foil, which serves as a support layer. The stainless steel foil not only possesses certain strength and flexibility, but its surface oxide layer also enhances compatibility and adhesion with nano-alumina sol. Furthermore, the oxide layer provides certain heat insulation and anti-oxidation effects at high temperatures.

[0043] In this invention, the stainless steel foil has excellent flexibility and does not oxidize or deform at high temperatures; it is compatible with nano-alumina sol, and the surface hydroxyl groups can form chemical bonds with the sol, avoiding the use of easily rusting carbon steel foil or aluminum foil that melts at lower temperatures.

[0044] In addition, the oxide layer surface of the stainless steel foil is rich in hydroxyl groups, which can form hydrogen bonds / coordination bonds with the Al-O bonds in the nano alumina sol, thereby improving the bonding strength. When the oxide layer thickness is <1μm, the number of hydroxyl groups is insufficient, and the bonding enhancement effect is not obvious. When the oxide layer thickness is >5μm, the oxide layer becomes brittle and is easy to fall off when bent.

[0045] The present invention also provides a method for preparing the flexible fire-resistant material described above, comprising the following steps: (1) Pretreatment: The stainless steel foil is cleaned to remove surface oil and impurities; (2) Preparation of nano-alumina sol: The nano-alumina sol is prepared at a solid content of 20%-40% and the pH value is adjusted to 3.5-11; (3) Lamination and composite: The surface of the pretreated stainless steel foil in step (1) is uniformly coated with the nano alumina sol in step (2), and the expansion material is laid on the surface of the stainless steel foil coated with the nano alumina sol. The stainless steel foil and the expansion material are alternately laminated to form a laminate. (4) Curing and molding: The laminate described in step (3) is cured under high pressure heating conditions; (5) Applying a heat-resistant coating: Apply a heat-resistant coating to the outermost layer of the cured laminate and dry it to obtain a flexible fireproof material.

[0046] The cleaning process described in step (1) of the present invention is ultrasonic cleaning in ethanol. The ultrasonic cleaning parameters are further preferably: ultrasonic frequency 28~40 kHz, time 5-15 minutes, temperature 45~55℃; after cleaning, drying at 60-70℃ for 5-8 minutes. The solid content of the nano-alumina sol described in this invention is further preferably 30%~40%, and the pH value is further preferably adjusted to 7~11.

[0047] In the laminated body described in step (3) of the present invention, the number of stainless steel foil layers is 2-5, and the number of expansion material layers is 1-4; the coating method of the nano alumina sol is dip coating, spray coating or scraping coating, the coating thickness is 5-20μm, and the coating amount is 50-100g / m².

[0048] In this invention, the nano-alumina sol is coated by dip coating, spray coating, or scraping coating. In the selection of coating amount and thickness, insufficient coating amount will lead to poor adhesion between stainless steel foil and expansion material, easy separation between layers, and damage to the integrity and structural strength of the material; excessive amount will increase the rigidity of the material, reduce flexibility, and even affect the stability of interlayer bonding due to sol accumulation. The range of coating amount can ensure sufficient adhesion, while maintaining the flexibility of the material and ensuring the interlayer bonding force to resist the risk of delamination under stress or bending.

[0049] In this invention, the number of stainless steel foil layers in the laminate is preferably 2-4 layers, and the number of expansion material layers is preferably 1-3 layers; the coating thickness is preferably 5-10 μm, and the coating amount is preferably 80-100 g / m².

[0050] In step (4) of this invention, the curing and molding process is carried out under the protection of an inert gas, wherein the inert gas is nitrogen and the oxygen concentration in the nitrogen environment is 10~100ppm; the curing and molding parameters are: pressure 0.5-2MPa, temperature 70-80℃, and time 25-30min.

[0051] In this invention, the oxygen concentration in the nitrogen environment is further preferably 50-100 ppm; the curing and molding parameters are further preferably: pressure 1-2 MPa, temperature 75-80℃, and time 28-30 min.

[0052] The coating method in step (5) of this invention is electrostatic rotary cup spraying, and the coating thickness is 0.1-0.3 mm; the drying method is infrared drying, and the infrared drying adopts a gradient temperature increase of 6~8℃ / min to 180-200℃.

[0053] In this invention, the electrostatic rotary cup spraying ensures a uniform and strong adhesion of the heat-resistant coating, avoiding localized weak points and guaranteeing a uniform fireproof and heat-insulating effect. Insufficient coating thickness will weaken the heat insulation and high-temperature resistance capabilities, failing to effectively block heat transfer. Excessive coating thickness will increase the material's weight and rigidity, reduce flexibility, and may even cause cracking during drying or use. A coating thickness of 0.1-0.3 mm can balance the heat insulation and flame-retardant effect with the material's flexibility, ensuring that the outer layer effectively protects the internal structure and delays high-temperature damage.

[0054] Furthermore, this invention directly heats the interior of the coating through infrared radiation, achieving "synchronous preheating inside and outside." It can simultaneously heat the coating and the substrate, and the gradient heating allows the substrate and coating temperatures to gradually synchronize, enabling the interface moisture to escape fully. There is no need to preheat the air, and the radiant heat acts directly on the coating. Combined with the "segmented high-efficiency evaporation" of the gradient heating, it avoids the energy waste of "high power throughout" during constant temperature drying. The dried coating has low internal stress, a dense structure, and no visible cracks after ultraviolet aging. This invention utilizes "non-contact radiant heating" combined with the uniform transmission of a tunnel-type infrared drying oven to ensure uniform temperature distribution in the laminate and coating. After drying, the substrate deformation is <0.2mm / m, maintaining its original flexibility (no cracks after 100 bends), and can smoothly adapt to the wrapping requirements of curved substrates such as cables and curved pipes.

[0055] In this invention, unless otherwise specified, all raw materials required for preparation are commercially available products well known to those skilled in the art.

[0056] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0057] Example 1: 1. Raw material and parameter selection 20 parts stainless steel foil, 40 parts expanded material, 10 parts nano alumina sol, and 10 parts heat-resistant coating; Stainless steel foil: 0.1 mm thick, with a 3 μm thick oxide layer on the surface; Nano-alumina sol: solid content 30%, pH=7; Expanded material: expanded graphite, 0.3 mm thick; Heat-resistant coating: ceramic particles are 25% titanium dioxide by mass, flame retardant is 8% aluminum hydroxide by mass, and silicone resin is 67%. Layered structure: 2 layers of stainless steel foil, 1 layer of expanded material; Key process parameters: nano alumina sol coating amount 80g / m²; curing conditions: pressure 1MPa, temperature 75℃, time 28min; heat-resistant coating is applied by electrostatic rotary cup spraying, thickness 0.2mm.

[0058] 2. Preparation steps: (1) Pretreatment: Stainless steel foil with a thickness of 0.1 mm and a surface oxide layer thickness of 3 μm was ultrasonically cleaned in ethanol at a frequency of 28 kHz, a time of 5 minutes, and a temperature of 45 °C. After cleaning, it was rinsed with deionized water and dried at 60 °C for 5 minutes to remove surface oil and impurities. (2) Preparation of nano-alumina sol: Aluminum nitrate and ammonium citrate were dissolved in 70wt% water at a mass ratio of 1:0.8 and mixed to obtain a premix; Add 0.5 wt% lactic acid to the premix, stir evenly, and adjust the pH to 7 with dilute hydrochloric acid / sodium hydroxide to obtain the nano alumina sol; (3) Lamination and composite: The surface of the pretreated stainless steel foil in step (1) is uniformly coated with the nano alumina sol in step (2) with a coating amount of 80g / m². Expanded graphite with a thickness of 0.3mm is laid on the surface of the stainless steel foil coated with the nano alumina sol. The stainless steel foil and the expanded material are alternately laminated to form a laminate of 2 layers of stainless steel foil and 1 layer of expanded material. (4) Curing and molding: The laminate described in step (3) is cured under high pressure heating conditions of 50 ppm oxygen, 1 MPa pressure, 75 °C temperature and 28 min in a nitrogen environment; (5) Applying a heat-resistant coating: The outermost layer of the cured laminate is coated with a 0.2mm heat-resistant coating containing 20% ​​ceramic particles, 25% flame retardant, and 67% silicone resin by electrostatic rotary cup spraying. The coating is then dried by infrared drying at a gradient temperature of 6℃ / min to 180℃ to obtain a flexible fireproof material.

[0059] The core performance of the material in Example 1 was tested, and the results are as follows (Table 1): Table 1: Results of Core Performance Tests on Materials from Example 1

[0060] According to the material performance results of Example 1 in Table 1 above, the flexible fireproof material obtained in Example 1 is suitable for scenarios with high flexibility requirements and medium fire resistance, such as fireproof wrapping of building pipes and heat insulation layers for household appliances. Its advantages include lower cost (expanded graphite is cheaper than vermiculite, and requires less steel foil), good flexibility, and convenient construction.

[0061] Example 2: 1. Raw material and parameter selection 25 parts stainless steel foil, 45 parts expanded material, 13 parts nano alumina sol, and 12 parts heat-resistant coating; Stainless steel foil: 0.15 mm thick, with a 4 μm oxide layer on the surface; Nano-alumina sol: solid content 35%, pH=8; Expanding material: expanded vermiculite, 0.4mm thick; Heat-resistant coating: ceramic particles are 28% silicon dioxide by mass, flame retardant is 7% phosphorus-based flame retardant by mass, and 65% silicone resin. Layered structure: 3 layers of stainless steel foil, 2 layers of expanded material; Key process parameters: nano alumina sol coating amount 90g / m²; curing conditions: pressure 1.2MPa, temperature 78℃, time 28min; heat-resistant coating is applied by electrostatic rotary cup spraying, thickness 0.2mm.

[0062] 2. Preparation steps: (1) Pretreatment: Stainless steel foil with a thickness of 0.15 mm and a surface oxide layer thickness of 4 μm was ultrasonically cleaned in ethanol at a frequency of 35 kHz, a time of 10 minutes, and a temperature of 50 °C. After cleaning, it was rinsed with deionized water and dried at 65 °C for 6 minutes to remove surface oil and impurities. (2) Preparation of nano-alumina sol: Aluminum nitrate and ammonium citrate were dissolved in 65wt% water at a mass ratio of 1:1 and mixed to obtain a premix; Add 0.5 wt% lactic acid to the premix, stir evenly, and adjust the pH to 8 with dilute hydrochloric acid / sodium hydroxide to obtain the nano alumina sol; (3) Lamination and composite: The surface of the pretreated stainless steel foil in step (1) is uniformly coated with the nano alumina sol in step (2) with a coating amount of 90g / m². Expanded vermiculite with a thickness of 0.4mm is laid on the surface of the stainless steel foil coated with the nano alumina sol. The stainless steel foil and the expanded material are alternately laminated to form a laminate of 3 layers of foil and 2 layers of expanded graphite. (4) Curing and molding: The laminate described in step (3) is cured under high pressure heating conditions of 80 ppm oxygen, 1.2 MPa pressure, 78 °C temperature and 28 min in a nitrogen environment; (5) Applying a heat-resistant coating: The outermost layer of the cured laminate is coated with a 0.2mm heat-resistant coating containing 28% ceramic particles, 7% flame retardant and 65% silicone resin by electrostatic rotary cup spraying. The coating is then dried by infrared drying at a gradient temperature of 6℃ / min to 190℃ to obtain a flexible fireproof material.

[0063] The core performance of the material in Example 2 was tested, and the results are shown in Table 2: Table 2: Results of Core Performance Tests on Materials from Example 2

[0064] As shown in Table 2 above, the flexible fireproof material obtained in Example 2 is suitable for high-temperature industrial applications, such as fireproof covers for petrochemical equipment and heat insulation layers for new energy battery packs. Its advantages include high heat insulation, high temperature resistance, and high strength, enabling long-term use in harsh environments. Although the cost is slightly higher, its performance redundancy is more substantial.

[0065] Example 3: 1. Raw material and parameter selection 30 parts stainless steel foil, 50 parts expansion material, 15 parts nano alumina sol and 15 parts heat-resistant coating; Stainless steel foil: 0.2 mm thick, with a 5 μm oxide layer on the surface; Nano-alumina sol: solid content 40%, pH=11; Expanded material: expanded perlite, 0.5mm thick; Heat-resistant coating: ceramic particles are 30% titanium dioxide by mass, flame retardant is 6% aluminum hydroxide by mass, and silicone resin is 64% silicone resin. Layered structure: 4 layers of stainless steel foil, 3 layers of expanded material; Key process parameters: nano alumina sol coating amount 100g / m²; curing conditions: pressure 2MPa, temperature 80℃, time 30min; heat-resistant coating is applied by electrostatic rotary cup spraying, thickness 0.3mm.

[0066] 2. Preparation steps: (1) Pretreatment: Stainless steel foil with a thickness of 0.2 mm and a surface oxide layer thickness of 5 μm was ultrasonically cleaned in ethanol at a frequency of 40 kHz, a time of 15 minutes, and a temperature of 55 °C. After cleaning, it was rinsed with deionized water and dried at 70 °C for 8 minutes to remove surface oil and impurities. (2) Preparation of nano-alumina sol: Aluminum nitrate and ammonium citrate were dissolved in 60wt% water at a mass ratio of 1:1.2 and mixed to obtain a premix; Add 0.5 wt% lactic acid to the premix, stir evenly, and adjust the pH to 11 with dilute hydrochloric acid / sodium hydroxide to obtain the nano alumina sol; (3) Layered composite: The surface of the pretreated stainless steel foil in step (1) is uniformly coated with the nano alumina sol in step (2) with a coating amount of 100g / m². Expanded perlite with a thickness of 0.5mm is laid on the surface of the stainless steel foil coated with the nano alumina sol. The stainless steel foil and the expanded material are alternately layered in sequence to form a 4-layer foil and 3-layer expanded graphite laminate. (4) Curing and molding: The laminate described in step (3) is cured under high pressure heating conditions of 100 ppm oxygen concentration, 2 MPa pressure, 80℃ temperature and 30 min in a nitrogen environment; (5) Applying a heat-resistant coating: The outermost layer of the cured laminate is coated with a 0.3mm heat-resistant coating containing 30% ceramic particles, 6% flame retardant and 64% silicone resin by electrostatic rotary cup spraying. The coating is then dried by infrared drying at a gradient temperature of 8℃ / min to 200℃ to obtain a flexible fireproof material.

[0067] The core performance of the material in Example 3 was tested, and the results are shown in Table 3: Table 3: Results of Core Performance Tests on Materials from Example 3

[0068] Comparative example: 1. Selection of raw materials and parameters (same as in Example 1) 2. In the preparation steps, only step 5, i.e. the step of "missing the heat-resistant coating", is removed, and the remaining steps are the same as in Example 1.

[0069] The test results and effect analysis are as follows (Table 4): Table 4: Performance Comparison of Example 1 and Comparative Example

[0070] As shown in Tables 1-4 and the above content, by adjusting parameters (type of expanding material, number of steel foil layers, sol solid content, coating thickness), Examples 1-3 can achieve precise matching of the "performance-scenario" of flexible fireproof materials. The basic scheme balances cost and flexibility, while the optimized scheme enhances heat insulation and strength. All three meet the technical requirements of this invention and verify the effectiveness of the three core designs in this invention: "alternating layered structure," "nano-alumina sol bonding," and "heat-resistant coating"—through the synergy of multiple components, the comprehensive performance of fireproofing, heat insulation, and mechanical properties can be significantly improved.

[0071] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A flexible fireproof material, characterized in that, The flexible fireproof material comprises the following components in parts by weight: 15-30 parts stainless steel foil, 35-55 parts expanded material, 10-20 parts nano alumina sol, and 5-15 parts heat-resistant coating; The stainless steel foil and the expansion material are arranged in an alternating layered structure, and the layers are bonded together by the nano-alumina sol. The heat-resistant coating is applied to the outermost layer.

2. The flexible fireproof material according to claim 1, characterized in that, The expanded material is one or more of expanded graphite, expanded vermiculite, or expanded perlite, with a particle size of 100-300 mesh and a thickness of 0.1-0.5 mm.

3. The flexible fireproof material according to claim 1, characterized in that, The preparation method of the nano-alumina sol is as follows: Aluminum nitrate and ammonium citrate are dissolved in water at a mass ratio of 1:0.8-1.2 and mixed to obtain a premix. Add 0.5-2 wt% lactic acid to the premix, stir evenly, and adjust the pH value to obtain the nano-alumina sol.

4. The flexible fireproof material according to claim 1, characterized in that, The heat-resistant coating comprises the following components by mass fraction: Ceramic particles 20-30%, flame retardant 5-10%, silicone resin 60-75%; The ceramic particles are selected from one or two of titanium dioxide and silicon dioxide; The flame retardant is selected from one or two of aluminum hydroxide and phosphorus-based flame retardants.

5. The flexible fireproof material according to claim 1, characterized in that, The stainless steel foil has a thickness of 0.05-0.2 mm and an oxide layer on its surface, the oxide layer having a thickness of 1-5 μm.

6. A method for preparing a flexible fire-resistant material according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Pretreatment: The stainless steel foil is cleaned to remove surface oil and impurities; (2) Preparation of nano-alumina sol: The nano-alumina sol is prepared at a solid content of 20%-40% and the pH value is adjusted to 3.5-11; (3) Lamination and composite: The surface of the pretreated stainless steel foil in step (1) is uniformly coated with the nano alumina sol in step (2), and the expansion material is laid on the surface of the stainless steel foil coated with the nano alumina sol. The stainless steel foil and the expansion material are alternately laminated to form a laminate. (4) Curing and molding: The laminate described in step (3) is cured under high pressure heating conditions; (5) Applying a heat-resistant coating: Apply a heat-resistant coating to the outermost layer of the cured laminate and dry it to obtain a flexible fireproof material.

7. The method for preparing a flexible fireproof material according to claim 6, characterized in that, The cleaning process described in step (1) is ultrasonic cleaning in ethanol. The ultrasonic cleaning parameters are: ultrasonic frequency 8~40 kHz, time 15-30 minutes, temperature 40~60℃; after cleaning, dry at 60-80℃ for 5-10 minutes.

8. The method for preparing a flexible fireproof material according to claim 6, characterized in that, In step (3), the number of stainless steel foil layers in the laminate is 2-5, and the number of expansion material layers is 1-4; the coating method of the nano alumina sol is dip coating, spray coating or scraping coating, the coating thickness is 5-20μm, and the coating amount is 50-100g / m².

9. A method for preparing a flexible fireproof material according to claim 6, characterized in that, The curing process in step (4) is carried out under the protection of an inert gas, namely nitrogen, and the oxygen concentration in the nitrogen environment is 10~100ppm; the curing parameters are: pressure 0.5-2MPa, temperature 70-80℃, and time 25-30min.

10. A method for preparing a flexible fireproof material according to claim 6, characterized in that, The coating method in step (5) is electrostatic rotary cup spraying, and the coating thickness is 0.1-0.3 mm; the drying method is infrared drying, and the infrared drying adopts a gradient temperature increase of 6~8℃ / min to 180-200℃.

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