A flexible fire-resistant and flame-retardant inorganic intumescent composite fireproof material and its preparation method and application

Abstract

The present invention relates to the field of fire-resistant and flame-retardant technology, and specifically to a flexible fire-resistant and flame-retardant inorganic expansion composite fireproof material, and its preparation method and application. The present invention provides a flexible fire-resistant and flame-retardant inorganic expansion composite fireproof material, comprising a tightly fitted silicon-based ceramic outer layer and an inorganic flexible expansion layer; wherein the silicon-based ceramic outer layer comprises a high-temperature resistant fiber substrate and a silicon-based ceramic coating coated on the surface of the high-temperature resistant fiber substrate, and the inorganic flexible expansion layer is an expansion sheet made by a slurry dehydration process, and the raw materials include sepiolite, brucite fiber, expanded graphite, adhesive and plasticizer. The composite fireproof material provided by the present invention has both good fire-resistant and flame-retardant functions, is not easy to burn in a fire, has low smoke toxicity, produces very little smoke, and can achieve live construction, which brings great convenience to the transformation of existing projects.

Description

Technical Field

[0001] The present invention relates to the technical field of fire resistance and flame retardancy, and in particular to a flexible fire-resistant and flame-retardant inorganic expansion composite fireproof material and a preparation method and application thereof. Background Art

[0002] A cable is a device that transmits electrical energy or signals, typically consisting of several conductors or groups of conductors. Cable fire protection generally has two distinct requirements: flame retardancy, which means the cable itself should not, or should participate as little as possible in combustion under fire or ignition sources, minimizing its impact on the expansion and spread of the fire; and fire resistance, which means the cable should maintain its basic function of carrying electricity under certain external fire conditions.

[0003] Currently, cable flame retardancy is generally achieved by adding flame-retardant materials to the cable sheath or applying fire-retardant coatings. Cable fire resistance is generally achieved by modifying the cable structure or adding fire-resistant materials. However, the following issues remain: 1. Whether flame-retardant or fire-resistant, cable fire retardancy only achieves flame retardancy, while fire resistance only achieves fire resistance. Therefore, it is currently impossible to achieve both flame retardancy and fire resistance simultaneously. 2. According to current national standards, the testing costs and cycle times for cable fire retardant coatings or cable sheaths are high, making it difficult to screen out substandard products, leading to a flood of substandard products on the market. Furthermore, due to the complex formulations of these materials, product consistency control is difficult. 3. As a key component of cable flame retardancy, cable fire retardant coatings are highly dependent on construction quality, and are prone to cracking and shedding due to environmental factors such as humidity, ultraviolet radiation, and alternating hot and cold temperatures. Consequently, their actual performance and service life are extremely low. 4. Due to the low compatibility between paints applied at different times or with different formulas, it is difficult to perform live operations without damaging or replacing the cables when repairing problems with cable fire retardant coatings or when the cable fire rating needs to be upgraded. 5. The current solutions and materials used for cable flame retardancy and cable fire resistance, whether it is the cable's own materials or structural design, or the cable fire retardant coating, are not recyclable and cannot be recycled. 6. The smoke toxicity of existing materials or coatings is relatively high, and the smoke production (smoke density) is relatively high. Once a fire occurs, it is easy to cause the risk of suffocation to people. 7. When a fire occurs outside the cable sheath, existing products cannot achieve "non-destructive" protection of the internal cables for a certain period of time, and the post-disaster repair cost is high; when a fire occurs inside the sheath, existing products cannot achieve internal "fire extinguishing" function. Summary of the Invention

[0004] In view of this, the present invention provides a flexible fire-resistant, flame-retardant inorganic expanded composite fireproof material and its preparation method and application. The composite fireproof material has both good fire-resistant and flame-retardant functions, is not easy to burn in a fire, has low smoke toxicity, produces very little smoke, and can realize live construction, making it easy to use.

[0005] To solve the above technical problems, the present invention provides a flexible fire-resistant, flame-retardant inorganic intumescent composite fireproof material, comprising a tightly fitted silicon-based ceramic outer layer and an inorganic flexible intumescent layer; wherein the silicon-based ceramic outer layer comprises a high-temperature resistant fiber substrate and a silicon-based ceramic coating coated on the surface of the high-temperature resistant fiber substrate; the inorganic flexible intumescent layer is an intumescent sheet made by a slurry dehydration process, and the raw materials include 40wt% to 60wt% of sepiolite, 5wt% to 25wt% of brucite fiber, 10wt% to 30wt% of expanded graphite, 5wt% to 20wt% of adhesive, and 1wt% to 10wt% of plasticizer.

[0006] The composite fireproofing material provided by the present invention has a structure of at least two layers, wherein an inorganic flexible expansion layer composed of specific components can undergo physical and chemical synergistic changes under high temperatures of fire, generating an expanded body with a large number of pores and excellent thermal stability. This composite fireproofing material is applied as a coating to the surface of an object to be fireproofed. Not only can it provide thermal insulation protection for objects inside the coating, such as cables, under conditions of external fire, but it can also achieve fire extinguishing function through the suffocating effect of the expansion body when a fire occurs inside the coating, while also achieving flame retardancy and fire resistance. The material selection of the inorganic flexible expansion layer provided by the present invention not only breaks through the current expanded graphite fireproofing and sealing material system based on organic carriers such as PVC, EVA, and EPDM rubber, but also avoids the problems of high smoke production and high smoke toxicity caused by the presence of a large amount of organic carriers.

[0007] Regarding the materials used in the inorganic flexible expansion layer of the present invention, sepiolite is a fibrous hydrous magnesium silicate with a unique layered chain structure. Its fiber bundles form a three-dimensional network skeleton, significantly improving the material's tensile strength and tear resistance. Furthermore, sepiolite possesses pores throughout its structure and active surfaces (such as Si-OH groups) that can absorb resins or adhesives, strengthening its interfacial bonding with the substrate and reducing internal defects. Sepiolite maintains a stable structure below 400°C, and at high temperatures, its internal pores absorb gases produced by thermal decomposition, delaying combustion. Brucite fiber is a fibrous magnesia hydroxide with a single fiber strength of 2-3 GPa. Its needle-columnar structure disperses stress and inhibits crack propagation. Brucite fiber decomposes at a temperature exceeding 800°C, maintaining its integrity even at high temperatures. It also contains no asbestos or radioactive substances, making it suitable for use in extreme environments.

[0008] The inorganic flexible expansion layer in the composite fireproof material provided by the present invention uses sepiolite, brucite fiber and expanded graphite as main raw materials, wherein the sepiolite and brucite fiber are solidified through hydrogen bonds or intermolecular van der Waals forces to form a planar flexible material, which gives the inorganic flexible expansion layer excellent comprehensive performance, and the two can also produce a synergistic effect. The main principle is: sepiolite (flexible fiber) and brucite (rigid fiber) are compounded to form a three-dimensional network, which improves the overall tensile strength; the porous structure of sepiolite can also absorb adhesives, and cooperate with the brucite fibers that provide skeleton support to inhibit material deformation; secondly, the Si-OH groups contained in sepiolite can react with the Mg of brucite to form a three-dimensional network, which improves the overall tensile strength; 2+ Covalent bonds are formed to further improve the interfacial bonding strength; in addition, sepiolite can adsorb gases produced by thermal decomposition, while the rigidity of brucite can inhibit high-temperature deformation of the material, enhance the stability of the carbon layer structure, and enable the composite system to retain a certain strength at 600°C; in addition, the combination of sepiolite and expandable graphite can play a main flame retardant effect and enhance the flame retardant effect of fireproof materials.

[0009] Preferably, the mass ratio of sepiolite to brucite fiber is 3:1 to 8:1. If sepiolite or brucite fiber is not added, a synergistic effect cannot be produced, resulting in reduced high-temperature stability and flame retardant effect of the inorganic flexible expansion layer; if the amount of sepiolite added relative to brucite fiber is too much or too little, it will affect the molding effect of the sheet, and will also increase the granularity of the sheet surface quality, reduce the tensile strength of the sheet, and increase the ablation rate at high temperature, resulting in a series of negative effects.

[0010] Preferably, the adhesive includes but is not limited to white latex and sodium silicate, and the adhesive can improve the surface strength and early bonding strength of the inorganic flexible expansion layer sheet.

[0011] Preferably, the plasticizer includes but is not limited to glycerin, and the plasticizer can improve the toughness of the inorganic flexible expansion layer sheet.

[0012] In practical applications, the inorganic flexible expansion layer can also be surface treated according to the actual application scenario. Surface treatment agents, such as anti-wear coatings, explosion-proof coatings, or waterproof coatings, can be applied to the surface of the inorganic flexible expansion layer. These coatings can strengthen the surface of the inorganic flexible expansion layer according to different needs. For example, when used in places with waterproofing requirements, a waterproof coating can be brushed or sprayed on the surface; when used in places with explosion-proof requirements, an explosion-proof coating can be brushed or sprayed on the surface; when used in places with wear resistance requirements, a layer of hardness or good elasticity materials such as silicone or polyurethane can be brushed on the surface.

[0013] Furthermore, the silicon-based ceramic outer layer provided by the present invention possesses sufficient structural strength to support the inorganic flexible expansion layer. It also exhibits excellent resistance to UV rays, alternating heat and cold, and water resistance. In the event of a fire, the silicon-based ceramic outer layer undergoes a chemical-physical reaction to ceramicize, absorbing heat while simultaneously blocking convection, achieving flame retardancy and fire resistance.

[0014] In combination with the first aspect, the fiber length of the sepiolite is 1-5 mm, the length of the brucite fiber is 10-30 mm, the particle size of the expanded graphite is 30-1000 mesh, and the expansion ratio is 50-500 times; the thickness of the silicon-based ceramic coating is 0.1-2 mm; and the thickness of the inorganic flexible expansion layer is 0.25-5 mm.

[0015] Under high temperatures of fire, expanded graphite can form a structure with large porosity, low thermal conductivity and high thermal stability in the cavity between the high-temperature resistant fiber substrate of the silicon-based ceramic outer layer and the object inside the sheath, such as a cable, through the synergistic effect between intercalation reaction and high-temperature thermal decomposition, thereby producing a flame retardant effect.

[0016] In combination with the first aspect, the raw material of the inorganic flexible expansion layer further includes at least one of ceramic fiber, glass fiber and basalt fiber with a length of 0.1-20 mm, and the mass proportion of the ceramic fiber, glass fiber and basalt fiber is 5wt%-10wt%.

[0017] In practical applications, ceramic fibers, glass fibers and basalt fibers can be added according to actual conditions. These fibers have a long-term temperature resistance of at least 300°C and are longer than sepiolite. Their addition can help improve the toughness and tensile strength of composite fireproof materials under conventional working conditions in non-fire scenarios. At the same time, the addition of these fibers can also play a role in enhancing the thermal stability of the material and filling the internal space structure of the material in the synergistic effect of sepiolite and brucite fibers.

[0018] In combination with the first aspect, the inorganic flexible expansion layer is prepared as follows: the sepiolite and brucite fibers are uniformly mixed according to a preset ratio, and microwave-treated at a microwave power of 400 to 1000 W for 1 to 3 minutes; thereafter, the fibers are uniformly mixed with the expanded graphite, a solvent, a binder, and a plasticizer are added to obtain a slurry, and the slurry is uniformly stirred until it becomes a paste; and then, the inorganic flexible expansion layer is formed by a coating method or a papermaking method to obtain the inorganic flexible expansion layer.

[0019] The solvent used may be water or a water-alcohol mixture. The inclusion of alcohols (such as ethanol) in the solvent is beneficial for reducing surface tension and improving the wettability and dispersion uniformity of the fibers used.

[0020] Microwave treatment of sepiolite and brucite fibers (and other fibers if incorporated) can remove impurities such as organic matter and water between the materials and expand the micropores between the fibers, facilitating subsequent mixing and the fiber's adsorption of expanded graphite, binders, and plasticizers. The power used in microwave treatment must be controlled within a certain range. Excessive power can alter the physical and chemical properties of the fibers, leading to deterioration and thermal decomposition. Excessive power fails to completely remove impurities such as organic matter and water, nor can it expand the micropores between the fibers. This can reduce the strength, toughness, and thermal stability of the inorganic flexible expansion layer at high temperatures.

[0021] When the inorganic flexible expansion layer sheet is formed by the coating method or the papermaking method, the coating method is to first stir the slurry into a paste and then evenly apply it on the surface of the base cloth with a coating thickness of 0.25~5mm. If necessary, a layer of non-woven fabric or gauze can be covered on the surface to prevent the coating from cracking. The sheet is then formed by natural drying or baking. The papermaking method is to stir the slurry into a paste and pour it into a screen, and use the traditional papermaking process to form it. It is then dehydrated and shaped by natural drying, baking or extrusion.

[0022] Preferably, the substrate cloth used can be selected from at least one of ceramic fiber fireproof cloth, glass fiber cloth, high silica cloth and basalt fiber cloth, with a thickness of 0.2-5 mm and a mass per unit area of ​​20-5000 g / m 2 .

[0023] In combination with the first aspect, the high temperature resistant fiber substrate is selected from at least one of ceramic fiber fireproof cloth, glass fiber cloth, high silica cloth and basalt fiber cloth, with a thickness of 0.2-5 mm and a mass per unit area of ​​20-5000 g / m 2 The above-mentioned high-temperature resistant fiber substrates all have a certain degree of thermal stability and provide mechanical strength for the applied coating. They are characterized by being non-flammable, having good thermal stability, high tensile strength, good toughness, and strong surface adhesion. Their oxygen index is ≥40%, and their long-term temperature resistance is ≥400°C.

[0024] In combination with the first aspect, the silicon-based ceramic coating includes 30wt%~60wt% of a silica gel matrix, 20wt%~40wt% of aluminum oxide, 15wt%~30wt% of glass powder or glass beads, 0.5wt%~2wt% of zinc oxide and 0.3wt%~3wt% of a curing agent.

[0025] The coating matrix of the silicon-based ceramic coating provided by the present invention is silica gel. Unlike the existing scheme of directly making the cable sheath flame retardant and fire resistant, the silica gel matrix used in the present invention has the function of bonding and solidifying the effective ingredients; moreover, silica gel has good ultraviolet resistance, resistance to alternating hot and cold temperatures, and water resistance, good elasticity, and good adhesion to high-temperature resistant fiber substrates. In addition, silica gel will pyrolyze under high temperature conditions of fire to form amorphous SiO2, thereby enhancing the flame retardant effect.

[0026] In addition, the silicon-based ceramic coating provided by the present invention also contains aluminum oxide, glass powder or glass microbeads, and zinc oxide. Aluminum oxide reacts with SiO2 formed by silica gel under high fire conditions to form a ceramic phase, which provides structural strength to the coating under high fire temperatures. It also reduces the transfer of fire heat to objects within the coating by blocking heat convection and reducing radiant heat. Glass powder or glass microbeads can achieve ceramicization or quasi-ceramicization reactions at lower temperatures through physical-chemical synergistic reactions such as melting within a temperature range of 300-800°C, bridging the temperature difference between the high-temperature resistant fiber substrate and the ceramicization of silica gel and aluminum oxide in the late stages of a fire, thereby providing fire protection for objects within the coating in the middle stages of a fire or in low-load fire scenarios. Zinc oxide has ultraviolet shielding and free radical quenching functions, absorbing ultraviolet rays with a wavelength less than 387nm and converting them into harmless heat energy, reducing the breakage of silica gel molecular chains. At the same time, the ZnO surface can capture free radicals excited by ultraviolet rays, inhibiting the occurrence of oxidation reactions. Furthermore, ZnO acts as an interface reinforcement and moisture barrier. It bonds to the Si-OH groups of silica gel through surface hydrogen bonds, forming a dense protective layer on the surface of the high-temperature-resistant fiber substrate, which blocks water vapor penetration. Therefore, the addition of zinc oxide can effectively improve UV resistance and heat and humidity resistance. Regarding UV resistance, under UV irradiation testing, coatings without zinc oxide exhibited significant surface cracking and a tensile strength loss of approximately 42%. However, after adding zinc oxide powder, the number and width of surface cracks were significantly reduced, with a tensile strength loss of approximately 28%. After 30 days of exposure to high temperature and humidity (75°C, 95% RH), the coating without zinc oxide exhibited significant adhesion, while the coating with zinc oxide did not exhibit adhesion.

[0027] In combination with the first aspect, the preparation steps of the silicon-based ceramic outer layer include: premixing zinc oxide and silica gel, adding an ethanol solution of a silane coupling agent, stirring thoroughly to ensure that the zinc oxide is evenly dispersed, then adding aluminum oxide, and glass powder or glass beads, stirring evenly, adding a curing agent and continuing to stir evenly to obtain a liquid coating, and then evenly applying the liquid coating to one side of the high-temperature resistant fiber substrate by roller coating, scraping, brushing or rolling, and allowing the coating to fully react and solidify on the high-temperature resistant fiber substrate by natural standing or baking acceleration.

[0028] Coating can be performed on a single sheet or continuously via rollers. In locations with lower fire protection requirements, the silicon-based ceramic outer layer can be replaced with a single- or double-sided silicone cloth of the same thickness. Colorants and fillers can also be added to the silicone as needed.

[0029] In combination with the first aspect, the composite fireproof material further includes an inner decorative layer, and the inorganic flexible expansion layer is sandwiched between the inner decorative layer and the silicon-based ceramic outer layer.

[0030] The decorative inner layer has the function of protecting the inorganic flexible expansion layer, improving the aesthetics of the product, and improving the weather resistance of the product. The inner decorative layer can be made of materials such as glass fiber cloth, basalt fiber cloth or ceramic fiber cloth with good thermal stability. In actual application, the inner decorative layer is used for the side of the composite fireproof material facing the object to be coated, and is in direct contact with the object to be coated. According to the needs of the application scenario, an inner decorative layer can be optionally provided. For fireproof materials without an inner decorative layer, their fire retardant properties will not be affected. When the actual application scenario has a high requirement for the fire protection level, or the fire-exposed surface is uncertain, a silicon-based ceramic outer layer can be used to replace the inner decorative layer. At this time, the entire composite fireproof material forms a completely symmetrical structure.

[0031] The second aspect of the present invention provides a method for preparing the above-mentioned flexible fire-resistant and flame-retardant inorganic expansion composite fireproof material, specifically: using high-temperature resistant flame-retardant thread to sew the inorganic flexible expansion layer and the silicon-based ceramic outer layer.

[0032] For the composite fireproof material including the inner decorative layer, the silicon-based ceramic outer layer and the inner decorative layer with the inorganic flexible expansion layer sandwiched therebetween are sewn together using high-temperature resistant flame-retardant thread.

[0033] In combination with the second aspect, the intervals between the high temperature resistant flame retardant lines are 1 to 100 cm, and the edges of the composite fireproof material are seamed as needed.

[0034] In actual applications, if the composite fireproofing material is used to be placed vertically after unfolding, in order to ensure the structural stability of the composite fireproofing material, the stitching should be performed at least along the horizontal parallel direction.

[0035] The third aspect of the present invention provides an application of the above-mentioned flexible fire-resistant, flame-retardant inorganic expanding composite fireproof material in steel cable fire protection, cable trough box fire protection, steel structure fire protection, aluminum alloy structure fire protection, concrete structure fire protection, wooden structure flame retardant and fire-resistant protection, fireproof sealing, lithium battery fire protection, new energy vehicle and energy storage facility fire protection, specifically: the composite fireproof material is wrapped on the surface of the object to be fire-protected by bundling, Velcro, button or mechanical fixation.

[0036] The present invention has developed a flexible, high-performance fire-resistant and flame-retardant material. In addition to its application in the field of cable fire protection, this material can also be used in areas requiring fire zoning and fire-resistant separation, such as building fire separation, fire sealing of power facility holes, and fire-resistant separation of new energy vehicles and facilities.

[0037] Preferably, for the bundling fixing method, metal cable ties such as stainless steel or non-metal cable ties such as high-temperature resistant fiber can be used to bundle the composite fireproof material coating on the surface of the object to be fire-protected. For the Velcro fixing method, the composite fireproof material can be cut to a suitable width according to the needs of the project, and the A and B sides of the flame-retardant Velcro can be sewn to the two ends of the composite fireproof material with high-temperature resistant thread respectively, and the Velcro can be used to form an enclosure structure for the protected object. For the button fixing method, the composite fireproof material can be cut to a suitable width according to the needs of the project, and the two ends can be fixed with buttons (such as buttons, snaps, etc.) to form an enclosure structure for the protected object. For the mechanical fixing method, the composite fireproof material can be cut to a suitable width according to the needs of the project, and the composite fireproof material can be directly fixed to the surface of the protected object by mechanical fixing methods such as strips and screws.

[0038] The present invention achieves beneficial effects: Through the specific selection of materials and unique structural design, a composite fireproofing material with both fire-resistant and flame-retardant properties is produced. This composite fireproofing material boasts an oxygen index of ≥40%, smoke toxicity reaching AQ2, and a smoke density rating (SDR) of ≤3. It is non-combustible, produces minimal smoke toxicity, and exhibits excellent weather resistance and environmental adaptability. Furthermore, this composite fireproofing material exhibits excellent insulation properties and, depending on the application scenario, can be used for live construction when voltage requirements are met, making it ideal for fireproofing upgrades in existing projects. When coated on the surface of a protected object, such as a cable, this composite fireproofing material significantly improves its flame retardancy (from B3 to B1) and significantly extends its fireproofing duration (from 6 minutes for base cable to 105 minutes of continuous fireproofing), reaching a maximum fireproofing duration of at least 240 minutes. Furthermore, this composite fireproofing material can be used not only for flame-retardant and fireproof protection of cables in new construction projects, but also for fireproofing upgrades in existing projects and flexible fireproof partitions in new energy applications, offering broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a photo of the composite fireproof material obtained in Example 3 of the present invention;

[0040] Figure 2 This is a photo of the composite fireproof material obtained in Example 1 of the present invention before coating the base cable;

[0041] Figure 3This is an on-site photograph of the composite fireproof material obtained in Example 1 of the present invention at the beginning of the fire resistance test after the base cable is coated;

[0042] Figure 4 This is an on-site photo of a base cable coated with the composite fireproof material obtained in Example 1 of the present invention and subjected to a fire resistance test for 240 minutes;

[0043] Figure 5 This is a photograph of the monitoring equipment display after the base cable was coated with the composite fireproof material obtained in Example 1 of the present invention and subjected to a fire resistance test for 240 minutes;

[0044] Figure 6 This is a photo of monitoring equipment during a 240-minute fire resistance test after the composite fireproof material obtained in Example 1 of the present invention was coated on a base cable;

[0045] Figure 7 This is a photo of the coated body after the composite fireproof material obtained in Example 1 of the present invention was coated on a base cable and subjected to a fire resistance test for 240 minutes. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art in the art to which the present invention pertains. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with those in the context of the prior art and, unless specifically defined, will not be interpreted in an idealized or overly formal sense.

[0048] At present, the products used for cable fire protection cannot take into account both flame retardancy and fire resistance at the same time, and the consistency of product quality is difficult to ensure. The flame retardant effect of fire retardant coatings is easily affected by construction quality and environmental factors. The coatings are prone to cracking and falling off, and the actual service life is short. Moreover, the compatibility of coatings from different batches or formulas is poor, which makes it difficult to perform live operations when repairing the coating or improving the fire protection level, and the cable needs to be replaced or shut down. Existing flame retardant / fire resistant materials (such as cable bodies or coatings) are not recyclable and do not conform to the concept of a circular economy. In addition, existing flame retardant or fire resistant materials are mostly based on organic matter as a carrier, which has the disadvantages of large smoke production and high toxicity during combustion. They can easily cause suffocation in fires and cause serious secondary hazards. Moreover, current fire retardant materials cannot protect cables from high-temperature losses, and the cost of post-disaster repair is high. At the same time, they lack "active" fire extinguishing functions and cannot effectively suppress the spread of fire.

[0049] The currently available "cable flame retardant tape" products mainly use PVC, EVA or EPDM rubber as base materials, which have high smoke toxicity and large smoke production. They can only be used for cable flame retardancy and cannot achieve cable fire protection. At the same time, they require winding construction, and the risk of live construction is relatively high. For existing projects, cables need to be moved, which makes construction difficult.

[0050] In view of this, the present invention provides a flexible fire-resistant, flame-retardant inorganic expanded composite fireproof material. The composite fireproof material has both flame-retardant and fire-resistant functions, has the advantages of high oxygen index, low smoke production and low smoke toxicity, and also has excellent weather resistance and insulation properties. It can upgrade other objects such as cables that do not have fireproof functions to higher flame retardant and fire-resistant levels, and has greater cost advantages. Moreover, for cables that already have fire-retardant coatings, the composite fireproof material will not be incompatible with the existing coatings, and is very suitable for fireproof upgrade and renovation projects of existing projects.

[0051] Unless otherwise specified, the chemical reagents, raw materials, and mechanical equipment used in the following examples and comparative examples are conventional commercially available products.

[0052] Example 1

[0053] This embodiment provides a flexible, fire-resistant, flame-retardant inorganic intumescent composite fireproofing material. This composite fireproofing material comprises a tightly bonded silicon-based ceramic outer layer, an inorganic flexible intumescent layer, and an inner decorative layer, all sewn together using high-temperature-resistant, flame-retardant thread. The silicon-based ceramic outer layer is made of ceramic fiber fireproofing cloth (3-4 mm thick) and a 0.5-1.5 mm thick silicon-based ceramic coating applied to the surface of the ceramic fiber fireproofing cloth. The coating comprises 40 wt% silica gel, 30 wt% aluminum oxide, 28 wt% glass powder, 1.5 wt% zinc oxide, and 0.5 wt% curing agent. The inorganic flexible intumescent layer is 3-4 mm thick and is made of 50 wt% sepiolite (1-5 mm fiber length), 10 wt% brucite fiber (10-30 mm fiber length), 5 wt% ceramic fiber (2-10 mm length), 20 wt% expanded graphite (500 mesh particle size, 200x expansion ratio), 10 wt% white latex, and 5 wt% glycerin.

[0054] The preparation method of the silicon-based ceramic outer layer is as follows:

[0055] S1. Stretching of high temperature resistant fiber substrate before coating: Lay the ceramic fiber fireproof cloth flat on the coating platform.

[0056] S2. Prepare the outer coating material: Premix zinc oxide and silica gel, add a 1% silane coupling agent solution in ethanol, and stir thoroughly with a stirring rod to ensure the zinc oxide is evenly dispersed. Pour the silica gel and zinc oxide powder mixture into a mixing tank, add aluminum oxide and glass powder, and stir to evenly distribute them throughout the silica gel. Add the curing agent and stir thoroughly to obtain the coating.

[0057] S3, applying outer coating: the coating obtained in step S2 is evenly applied on one side of the ceramic fiber fireproof cloth by roller coating, and allowed to stand naturally to allow the coating to fully react and solidify on the ceramic fiber fireproof cloth.

[0058] The preparation method of the inorganic flexible expansion layer is as follows:

[0059] S1. Microwave pretreatment: A mixture of sepiolite, brucite fiber and ceramic fiber was stirred in a drum at room temperature for 30 minutes to fully mix the three fiber powders, and then placed in a microwave oven for microwave treatment. The treatment conditions were 600 W microwave power for 2 minutes per 10 kg of the mixture.

[0060] S2. Slurry preparation: Mix the three pre-treated high-temperature formed fibers and expanded graphite, add water, white latex and glycerin, and stir until a uniform paste is formed.

[0061] S3, sheet forming: the slurry obtained in step S2 is evenly applied to the surface of the ceramic fiber fireproof cloth by a coating method, with a coating thickness of 0.5-3 mm, and a layer of non-woven fabric is covered on the surface to prevent cracking, and the sheet is naturally dried to form.

[0062] The inner decorative layer used is glass fiber cloth.

[0063] Example 2

[0064] This embodiment provides a flexible, fire-resistant, flame-retardant inorganic intumescent composite fireproofing material. This composite fireproofing material comprises a tightly bonded silicon-based ceramic outer layer and an inorganic flexible intumescent layer, sewn together using high-temperature-resistant, flame-retardant thread. The silicon-based ceramic outer layer is made of glass fiber cloth (1-2.5 mm thick) and a 0.1-1 mm thick silicon-based ceramic coating applied to the surface of the glass fiber cloth. The coating comprises 30 wt% silica gel, 40 wt% aluminum oxide, 27 wt% glass microspheres, 0.5 wt% zinc oxide, and 2.5 wt% curing agent. The inorganic flexible intumescent layer is 0.3-2 mm thick and is made of 60 wt% sepiolite (1-5 mm fiber length), 5 wt% brucite fiber (10-30 mm fiber length), 10 wt% glass fiber (2-5 mm length), 10 wt% expanded graphite (50 mesh particle size, 50x expansion ratio), 14 wt% sodium silicate, and 1 wt% glycerin.

[0065] The preparation method of the silicon-based ceramic outer layer is as follows:

[0066] S1. Stretching of high temperature resistant fiber substrate before coating: Lay the glass fiber cloth flat on the coating platform.

[0067] S2. Prepare the outer coating material: Premix zinc oxide and silicone, add a 1% silane coupling agent solution in ethanol, and stir thoroughly with a stirring rod to ensure the zinc oxide is evenly dispersed. Pour the silicone and zinc oxide powder mixture into a mixing tank, add aluminum oxide and glass beads, and stir to evenly distribute them throughout the silicone. Add the curing agent and stir thoroughly to obtain the coating.

[0068] S3, applying outer coating: the coating obtained in step S2 is evenly scraped and brushed on one side of the glass fiber cloth by roller coating, and left to stand naturally to allow the coating to fully react and solidify on the glass fiber cloth.

[0069] The preparation method of the inorganic flexible expansion layer is as follows:

[0070] S1. Microwave pretreatment: A mixture of sepiolite, brucite fiber and glass fiber was stirred in a drum at room temperature for 20 minutes to fully mix the three fiber powders, and then placed in a microwave oven for microwave treatment. The treatment conditions were 1000 W microwave power for 1 minute per 10 kg of the mixture.

[0071] S2. Slurry preparation: Mix the three pre-treated high-temperature formed fibers and expanded graphite, add water, white latex and glycerin, and stir until a uniform paste is formed.

[0072] S3, sheet forming: the slurry obtained in step S2 is evenly applied to the surface of the glass fiber cloth by a coating method, with a coating thickness of 1-2 mm, and a layer of non-woven fabric is covered on the surface to prevent cracking, and the sheet is naturally dried to form the sheet.

[0073] Example 3

[0074] This embodiment provides a flexible fire-resistant, flame-retardant inorganic expansion composite fireproof material, which includes a tightly fitted silicon-based ceramic outer layer, an inorganic flexible expansion layer and an inner decorative layer, which are sewn together with high-temperature resistant flame-retardant thread, wherein the inorganic flexible expansion layer is sandwiched as an intermediate layer between the silicon-based ceramic outer layer and the inner decorative layer. The raw materials of the silicon-based ceramic outer layer include basalt fiber cloth (thickness 3~5mm) and a 0.2~2mm thick silicon-based ceramic coating coated on the surface of the basalt fiber cloth. The silicon-based ceramic coating includes 60wt% of silica gel, 20wt% of aluminum oxide, 17wt% of glass powder, 2wt% of zinc oxide, and 1wt% of curing agent. The thickness of the inorganic flexible expansion layer is 3~4mm, and the raw materials include: sepiolite (fiber length 1~5mm) 40wt%, brucite fiber (fiber length 10~30mm) 25wt%, basalt fiber (length 2~10mm) 5wt%, expanded graphite (particle size 1000 mesh, expansion ratio 500 times) 24wt%, white latex 5wt% and glycerin 1wt%.

[0075] The preparation method of the silicon-based ceramic outer layer is as follows:

[0076] S1. Stretching of high temperature resistant fiber substrate before coating: Lay the basalt fiber cloth flat on the coating platform.

[0077] S2. Prepare the outer coating material: Premix zinc oxide and silica gel, add a 1% silane coupling agent solution in ethanol, and stir thoroughly with a stirring rod to ensure the zinc oxide is evenly dispersed. Pour the silica gel and zinc oxide powder mixture into a mixing tank, add aluminum oxide and glass powder, and stir to evenly distribute them throughout the silica gel. Add the curing agent and stir thoroughly to obtain the coating.

[0078] S3. Applying an outer coating: The coating obtained in step S2 is evenly applied to one side of the basalt fiber cloth by roller pressing, and allowed to stand naturally to allow the coating to fully react and solidify on the basalt fiber cloth.

[0079] The preparation method of the inorganic flexible expansion layer is as follows:

[0080] S1. Microwave pretreatment: A mixture of sepiolite, brucite fiber and basalt fiber was stirred in a drum at room temperature for 30 minutes to fully mix the three fiber powders, and then placed in a microwave oven for microwave treatment. The treatment conditions were 400 W microwave power for 3 minutes per 10 kg of the mixture.

[0081] S2. Slurry preparation: Mix the three pre-treated high-temperature formed fibers and expanded graphite, add a mixture of ethanol and water, white latex and glycerin, and stir until a uniform paste is formed.

[0082] S3, sheet forming: the slurry obtained in step S2 is evenly applied to the surface of the high-silica cloth by a coating method, with a coating thickness of 0.5-3 mm, and a layer of non-woven fabric is covered on the surface to prevent cracking, and the sheet is naturally dried to form.

[0083] The inner decorative layer used is glass fiber cloth.

[0084] Comparative Example 1

[0085] This comparative example provides a flexible fire-resistant, flame-retardant inorganic intumescent composite fireproofing material. The composition and structure of the composite fireproofing material are basically similar to those of Example 1, except that the raw materials for preparing the inorganic flexible intumescent layer do not contain sepiolite, but are replaced by an equal amount of brucite fiber. The remaining raw material composition and preparation method are the same as those of Example 1.

[0086] Comparative Example 2

[0087] This comparative example provides a flexible fire-resistant, flame-retardant inorganic intumescent composite fireproofing material. The composition and structure of the composite fireproofing material are basically similar to those of Example 1, except that the mass proportion of sepiolite in the inorganic flexible intumescent layer is 58wt%, and the mass proportion of brucite fiber is 2wt%. The remaining raw material composition and preparation method are the same as those of Example 1.

[0088] Comparative Example 3

[0089] This comparative example provides a flexible fire-resistant, flame-retardant inorganic intumescent composite fireproofing material. The composition and structure of the composite fireproofing material are the same as those in Example 1, except that, when preparing the inorganic flexible intumescent layer, the sepiolite, brucite fiber, and ceramic fiber are not subjected to microwave pretreatment but are directly used in the preparation of the slurry. The remaining preparation methods are the same as those in Example 1.

[0090] Comparative Example 4

[0091] This comparative example provides a cable with a surface coated with a fire retardant coating, wherein the base cable is a cross-linked polyethylene insulated and polyethylene sheathed power cable YJV22-0.6 / 1kV-3*50+1*25 commonly used in engineering projects, and the components of the fire retardant coating coated on the surface of the base cable include 10wt%~40wt% of ammonium polyphosphate, 5wt%~20wt% of melamine, 2wt%~12wt% of pentaerythritol and 10wt%~30wt% of acrylic emulsion, and the balance is a mixture of ethanol and water, and the coating thickness is 1mm.

[0092] Comparative Example 5

[0093] This comparative example provides a cable provided with a protective sheath, wherein the base cable is a cross-linked polyethylene insulated polyethylene sheathed power cable YJV22-0.6 / 1kV-3*50+1*25 commonly used in engineering projects, and the material of the protective sheath used is glass fiber with a silicone coating on the surface and a ceramic fiber cloth lining, with a thickness of 3~4mm.

[0094] Test Example

[0095] The composite fireproof materials obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were respectively bundled and coated with high-temperature resistant fiber ties on the surface of a base cable having a cross-linked polyethylene insulated and polyethylene sheathed power cable YJV22-0.6 / 1kV-3*50+1*25 and no flame retardant function, which is commonly used in engineering projects, and the fire resistance and flame retardant properties were measured. At the same time, the uncoated base cable was used as a control, and the following properties of the different cables provided in Comparative Examples 4 to 5 were tested.

[0096] Among them, the flame retardant grade of the cable before and after coating is tested according to GB 31247-2014 "Classification of Fire Performance of Electric Cables and Optical Fiber Cables"; the fire resistance grade of the cable before and after coating is tested according to GB / T 19216.21-2003 "Line integrity test of electric or optical cables under flame conditions Part 21: Test procedures and requirements - Cables with rated voltage of 0.6 / 1.0kV and below"; Weathering test 1 includes corrosion resistance, water resistance, oil resistance, acid resistance, water resistance, moisture and heat resistance, and freeze-thaw cycle resistance tests according to GB 23864-2023 "Fireproof sealing materials"; Weathering test 2 includes heat exposure resistance, moisture and heat resistance, freeze-thaw cycle resistance, acid resistance, alkali resistance, salt spray corrosion resistance, and ultraviolet radiation resistance according to GB 14907-2018 "Fire retardant coatings for steel structures"; The oil resistance, salt water resistance, moisture and heat resistance, and freeze-thaw cycle resistance tests were carried out in accordance with GB / T 20285-2006 "Hazard Classification of Toxicity of Smoke Generation of Materials", the oxygen index of the material was tested in accordance with GB / T 2406.2-2009 "Determination of Combustion Behavior of Plastics by the Oxygen Index Method - Part 2: Room Temperature Test", and the smoke density level of the material was tested in accordance with GB / T 20284-2006 "Single-Unit Combustion Test for Building Materials or Products". The insulation performance of the material was tested using a multimeter. The test results are shown in Table 1.

[0097] Table 1

[0098]

[0099] As can be seen in Table 1, Examples 1-3 not only maintain their weather resistance but also significantly improve their combustion performance compared to non-fire-resistant base cables. More importantly, according to cable fire resistance test methods, the coated silicon-based sheathing materials provided by the present invention fully meet the requirements for fire-resistant cables, with fire resistance limits exceeding 240 minutes. The smoke toxicity of the base cable sheath is increased from ZA3 to AQ2, and the smoke density is reduced to ≤3, while maintaining no significant degradation in insulation.

[0100] Comparing Example 1 with Comparative Examples 1-2 reveals that significant changes in the components lead to a loss of coordination and coordination between them, resulting in a decrease in the physical and chemical properties, weatherability, and combustion performance of the resulting composite fireproofing material. The smoke density level and smoke toxicity also decrease to varying degrees. Furthermore, with regard to the critical fire resistance performance, while the composite fireproofing materials obtained in Comparative Examples 1-2 still meet the requirements of fire-resistant cable testing, their fire resistance limit duration is significantly shortened compared to Example 1.

[0101] Comparing Example 1 with Comparative Example 3, it can be seen that when the sepiolite, brucite fibers, and ceramic fibers are not subjected to the microwave pretreatment process, their weather resistance, fire resistance limit, and smoke density level are all reduced, indicating that microwave pretreatment of the inorganic fibers in advance has a significant improvement effect on the fire resistance and smoke density of the final composite fireproofing material.

[0102] Comparing Examples 1-3 with Comparative Example 4, a commonly used cable fire protection method—coating a cable fire retardant coating on the base cable surface—the present invention not only addresses the difficulties of cable fire retardant coating application and the impossibility of live work, but also addresses the poor weather resistance of cable fire retardant coatings. Furthermore, the present invention significantly improves fire resistance, smoke toxicity, and smoke density compared to Comparative Example 4.

[0103] Comparing Examples 1 to 3 with Comparative Example 5, which is a commonly used cable protection and fire prevention method at present, in which a cable protection sleeve is coated on the outer surface of the base cable, it can be seen that the flame retardant performance of Comparative Example 5 is worse than that of the present invention. At the same time, although the fire resistance limit is improved compared with the base cable, it still cannot meet the performance indicators of the fire-resistant cable, and the gap in fire resistance and flame retardant performance is large compared with the present invention.

[0104] In addition, the photos of the fire resistance test are as follows: Figures 1 to 5 As shown, Figure 1 The composite fireproof material provided in Example 3 of the present invention comprises, from top to bottom, an inner decorative layer, an inorganic flexible expansion layer, and a silicon-based ceramic outer layer; Figure 2 This is a photo taken on site before the composite fireproof material obtained in Example 1 was bundled and wrapped around the base cable; Figure 3 and Figure 4The following are on-site photos of the composite fireproof material obtained in Example 1 being bundled and wrapped around the above-mentioned base cable before the fire resistance test and after the fire resistance test was continuously carried out for 240 minutes; Figure 5 and Figure 6 They are photos of the monitoring equipment display and monitoring equipment during the fire resistance test; Figure 7 This is a photo of the cable after 240 minutes of fire resistance test. Figures 2 to 7 It can be seen that after the composite fireproof material provided by the present invention is used to coat the base cable without flame retardant performance, after a fire resistance test of up to 240 minutes, the composite fireproof material will expand, but it itself will not burn, and the base cable coated inside will be intact, indicating that the composite fireproof material provided by the present invention has excellent flame retardancy and fire resistance, and can protect the coated object from being ignited for a long time. Figure 4 It can be seen that during the fire resistance test, no large amount of black smoke or thick smoke was produced, which also shows that the smoke toxicity and smoke density of the composite fireproof material are low. In the event of an actual fire, it provides a strong guarantee for the victims to quickly and safely escape from the fire scene. Figure 6 It can be seen that the base cable protected by the composite fireproof material can always remain energized (the four red bulbs in the top row are all lit, indicating that the cable is still energized). This shows that after the base cable is coated with the composite fireproof material, even if a fire occurs, the base cable can maintain normal working conditions for a long time, reducing the losses caused by power outages due to fire.

[0105] The above is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A flexible fire-resistant, flame-retardant inorganic intumescent composite fireproof material, characterized in that: It includes a tightly fitting silicon-based ceramic outer layer and an inorganic flexible expansion layer; The silicon-based ceramic outer layer includes a high-temperature resistant fiber substrate and a silicon-based ceramic coating coated on the surface of the high-temperature resistant fiber substrate, wherein the silicon-based ceramic coating includes 30wt% to 60wt% of a silica gel matrix, 20wt% to 40wt% of aluminum oxide, 15wt% to 30wt% of glass powder or glass microbeads, 0.5wt% to 2wt% of zinc oxide, and 0.3wt% to 3wt% of a curing agent; The inorganic flexible expansion layer is an expansion sheet made by a slurry dehydration process, and the raw materials include 40wt% to 60wt% of sepiolite, 5wt% to 25wt% of brucite fiber, 10wt% to 30wt% of expanded graphite, 5wt% to 20wt% of adhesive and 1wt% to 10wt% of plasticizer; The preparation method of the inorganic flexible expansion layer is as follows: S1: mixing the sepiolite and brucite fibers uniformly according to a preset ratio, and subjecting the mixture to microwave treatment at a microwave power of 400-1000 W for 1-3 min; S2: then mix evenly with the expanded graphite, add a solvent, a binder and a plasticizer to obtain a slurry, and stir evenly until it becomes a paste; S3: forming the inorganic flexible expansion layer by coating or papermaking.

2. The flexible fire-resistant, flame-retardant inorganic intumescent composite fireproofing material according to claim 1, characterized in that: The fiber length of the sepiolite is 1-5 mm, the length of the brucite fiber is 10-30 mm, the particle size of the expanded graphite is 30-1000 mesh, and the expansion ratio is 50-500 times; the thickness of the silicon-based ceramic coating is 0.1-2 mm; and the thickness of the inorganic flexible expansion layer is 0.25-5 mm.

3. The flexible fire-resistant, flame-retardant inorganic intumescent composite fireproofing material according to claim 1, characterized in that: The raw materials of the inorganic flexible expansion layer further include a fiber material of at least one of ceramic fiber, glass fiber, and basalt fiber with a length of 0.1 to 20 mm, and the mass proportion of the fiber material is 5 wt% to 10 wt%. Step S1 in the method for preparing the inorganic flexible expansion layer is replaced by: uniformly mixing the sepiolite, brucite fiber, and the above fiber materials according to a preset proportion, and microwave-treating them at a microwave power of 400 to 1000 W for 1 to 3 minutes.

4. The flexible fire-resistant and flame-retardant inorganic intumescent composite fireproofing material according to any one of claims 1 to 3, characterized in that: The high temperature resistant fiber substrate is selected from at least one of ceramic fiber fireproof cloth, glass fiber cloth, high silica cloth and basalt fiber cloth, with a thickness of 0.2-5 mm and a mass per unit area of ​​20-5000 g / m 2 .

5. The flexible fire-resistant, flame-retardant inorganic intumescent composite fireproofing material according to claim 1, characterized in that: The composite fireproof material further comprises an inner decorative layer, and the inorganic flexible expansion layer is sandwiched between the inner decorative layer and the silicon-based ceramic outer layer.

6. The method for preparing the flexible fire-resistant and flame-retardant inorganic intumescent composite fireproofing material according to any one of claims 1 to 5, characterized in that: When the inner decorative layer is not included, the inorganic flexible expansion layer and the silicon-based ceramic outer layer are sewn together using high-temperature resistant flame-retardant thread; when the inner decorative layer is included, the silicon-based ceramic outer layer and the inner decorative layer with the inorganic flexible expansion layer sandwiched between them are sewn together using high-temperature resistant flame-retardant thread.

7. The method for preparing the flexible fire-resistant and flame-retardant inorganic intumescent composite fireproofing material according to claim 6, characterized in that: The intervals between the high temperature resistant flame retardant lines are 1 to 100 cm, and the edges of the composite fireproof material are seamed as needed.

8. Use of the flexible fire-resistant, flame-retardant inorganic intumescent composite fireproofing material according to any one of claims 1 to 5 in fire protection of steel cables, fire protection of cable trough boxes, fire protection of steel structures, fire protection of aluminum alloy structures, fire protection of concrete structures, flame retardant and fire-resistant protection of wooden structures, fireproof sealing, fire protection of lithium batteries, fire protection of new energy vehicles and energy storage facilities, characterized in that: The composite fireproof material is wrapped around the surface of the object to be fire-protected by bundling, Velcro, button or mechanical fixing. The mechanical fixing is to cut the composite fireproof material into a suitable width according to the project needs, and directly fix the composite fireproof material on the surface of the protected object by means of pressure strips and screws.

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