Flame-retardant and high-temperature-resistant material for fireproof air duct and preparation method thereof

Abstract

The invention discloses a flame-retardant and high-temperature-resistant material for a fireproof air duct and a preparation method of the flame-retardant and high-temperature-resistant material, and the flame-retardant and high-temperature-resistant material comprises the following raw materials in parts by weight: 60-70 parts of magnesium oxide, 35-45 parts of magnesium sulfate, 45-60 parts of water, 15-25 parts of expanded perlite, 10-15 parts of mica powder, 10-15 parts of modified mineral fiber, 8-12 parts of quartz powder, 3-5 parts of silica fume, 0.5-0.8 part of a retarder and 1-1.5 parts of a waterproof modifier. The flame-retardant and high-temperature-resistant material of the fireproof air duct is a multi-component composite inorganic material system, magnesium sulfate cement with the natural fireproof advantage is used as the basis, basic physical properties are optimized by compounding and using multiple functional fillers with light weight, heat resistance, activity and the like, and modified mineral fiber prepared by a specific method is added as a key reinforcing phase, so that the flame-retardant and high-temperature-resistant fireproof air duct is obtained. The mechanical property and the structural stability of the material at high temperature are remarkably improved, so that the prepared material has the characteristics of good flame retardance, high temperature resistance, good mechanical property, light weight and durability, and is particularly suitable for a fireproof air pipe material.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a flame-retardant and high-temperature resistant material for fire-proof air ducts and a preparation method thereof. Background Art

[0002] Air ducts are widely used in environments such as commercial buildings, industrial facilities, residential buildings, public places and special places, etc., for transporting and distributing air to ensure indoor air quality and comfort. With the development of building technology and the improvement of people's requirements for air quality, the air duct system is also constantly evolving, moving towards a more efficient, more energy-saving and more environmentally friendly direction. Among them, fire-proof air ducts, also known as fire-resistant air ducts, are air duct systems specifically designed to maintain structural integrity and functionality in the event of a fire, and are widely used in high-rise buildings, underground facilities, tunnels and other places with strict fire protection requirements; the main function of fire-proof air ducts is to prevent flames and harmful gases from spreading through the air ducts during a fire, protecting the safety of personnel and reducing property losses.

[0003] The fire-proof air ducts used in buildings mainly include two categories: galvanized iron sheet air ducts and inorganic glass fiber reinforced plastic air ducts. Although these air ducts meet the requirements of relevant fire protection codes for the combustion performance of their used materials, their fire-resistant performance is not ideal enough, and they are prone to distortion, collapse, cracks, holes, etc. in a fire, resulting in flames and thick smoke passing through the damaged air ducts, causing the spread of the fire. In addition, iron sheet air ducts are prone to rust and damage, and inorganic glass fiber reinforced plastic air ducts are prone to deformation and damage due to moisture absorption and aging. These drawbacks seriously affect the service life of such air ducts in actual projects and increase the maintenance and repair costs of the air ducts.

[0004] Chinese Patent Application CN102515678A discloses an algae calcium composite material, a decorative board and a production method. The algae calcium composite material is composed of the hydration gel of diatomite and a calcium-containing inorganic building material matrix; the calcium-containing inorganic building material matrix is one or more of calcium hemisulfate, calcium phosphate, and calcium aluminate; preferably, each component is mixed according to a weight ratio, and the ratio is calcium-containing inorganic building material matrix: diatomite: short cut filaments of reinforcing fiber: aqueous glue solution: tributyl phosphate = 100: 10 - 50: 1.2 - 2.0: 50 - 65: 5 - 10; the above raw materials are made into decorative material products through raw material pretreatment, mixing and stirring, pouring and molding, curing and drying, and surface treatment, fully stimulating the excellent plasticity and environmental coordination of the composite new material, and at the same time, using the multi-microporous property of diatomite to endow the material with good environmental protection functions such as humidity adjustment, adsorption of harmful gases such as formaldehyde, and sterilization. Chinese Patent Application CN114412130A discloses a fireproof board and a ventilation duct, wherein the fireproof board includes a fireproof layer and an outer surface layer; the outer surface layer is fixed on one side of the fireproof layer, and the side of the fireproof layer in contact with the outer surface layer is provided with sound absorption holes, and the sound absorption holes are all filled with sound absorption materials, and the fireproof layer includes component A, a curing agent, and an adhesive; the fireproof layer is formed by mixing component A, perlite, and expanded vermiculite and then pouring them into a forming mold for pressing. The fireproof board is a fireproof and heat-insulating material with good fireproof performance and heat-insulating performance, and at the same time has the characteristics of environmental protection, low carbon, energy saving, and renewable. The ventilation duct includes a duct body and fireproof boards provided on the inner and outer surfaces of the duct body, and the ventilation duct can effectively play a fireproof role and avoid the risk that the ventilation duct will be ignited in case of a fire. However, the above patents, but the above technologies do not take into account the flame retardancy, high temperature resistance, and mechanical properties of the fireproof duct material, and its comprehensive performance still needs to be improved.

[0005] Based on this, the deficiencies of the existing fireproof duct materials in terms of flame retardancy, high temperature resistance, etc. restrict the improvement of the building fire protection safety level. Therefore, it is of great significance to develop a fireproof duct material in this field that combines high-efficiency flame retardancy, high temperature resistance, light weight, environmental protection, and easy construction. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a flame retardant and high temperature resistant material for fireproof ducts and its preparation method.

[0007] To achieve the above purpose, the present invention provides the following technical solutions: A flame retardant and high temperature resistant material for fireproof ducts, by weight, includes the following raw materials: 60 - 70 parts of magnesium oxide, 35 - 45 parts of magnesium sulfate, 45 - 60 parts of water, 15 - 25 parts of expanded perlite, 10 - 15 parts of mica powder, 10 - 15 parts of modified mineral fiber, 8 - 12 parts of quartz powder, 3 - 5 parts of silica fume, 0.5 - 0.8 parts of retarder, 1 - 1.5 parts of waterproof modifier.

[0008] In the present invention, the flame - retardant and high - temperature resistant material for fire - proof air ducts is a multi - component composite inorganic material system. Based on magnesium sulfate cement with natural fire - proof advantages, it optimizes the basic physical properties by compounding various functional fillers such as lightweight, heat - resistant, and active fillers, and adds modified mineral fibers prepared by a specific method as the key reinforcing phase to significantly improve the mechanical properties and structural stability of the material at high temperatures. At the same time, by adding a certain amount of chemical admixtures to regulate the construction performance (retarding setting) and improve the durability (waterproofing), the prepared material has the characteristics of good flame - retardancy, high - temperature resistance, good mechanical properties, lightweight, and durability, and is particularly suitable for fire - proof air duct materials.

[0009] Preferably, a flame - retardant and high - temperature resistant material for fire - proof air ducts, by weight, comprises the following raw materials: 65 - 70 parts of magnesium oxide, 40 - 45 parts of magnesium sulfate, 50 - 55 parts of water, 10 - 25 parts of expanded perlite, 12 - 15 parts of mica powder, 13 - 15 parts of modified mineral fiber, 8 - 10 parts of quartz powder, 3 - 4 parts of silica fume, 0.7 - 0.8 parts of retarder, 1.2 - 1.5 parts of waterproof modifier.

[0010] Preferably, the retarder is one or two of sodium tetraborate and sodium citrate, and the waterproof modifier is one or two of calcium stearate and zinc stearate.

[0011] Preferably, the preparation method of the modified mineral fiber comprises the following steps: S1. Add basalt fiber into nitric acid solution for impregnation treatment. After the treatment, filter, wash, and dry to obtain pretreated basalt fiber. Add the pretreated basalt fiber into ethanol, then add phenolic resin, and carry out constant - temperature stirring. After the stirring is completed, filter and dry to obtain organic basalt fiber; S2. Add the organic basalt fiber in step S1 into deionized water, then add boric acid and melamine for hydrothermal reaction. After the reaction is completed, filter, wash, dry, and calcine to obtain composite fiber; S3. Add the composite fiber in step S2 into an ethanol - aqueous solution, then add γ - mercaptopropyltrimethoxysilane for stirring reaction. After the reaction is completed, filter, wash, and dry to obtain organically modified composite fiber; S4. Add the organic composite fiber in step S3 into toluene, then add lauryl methacrylate and azobisisobutyronitrile, carry out a constant-temperature reaction, and after the reaction is completed, filter, wash, and dry to obtain modified mineral fibers.

[0012] Preferably, in step S1, the mass concentration of the nitric acid solution is 15 - 20%, the temperature of the impregnation treatment is 30 - 40°C, and the time is 1 - 2 h; the mass ratio of the pretreated basalt fiber, ethanol, and phenolic resin is 50 - 60:300 - 400:20 - 30, the temperature of the constant-temperature stirring is 60 - 70°C, and the time is 1 - 2 h.

[0013] In the present invention, through nitrate impregnation treatment, the surface roughness and specific surface area of the basalt fiber are increased, improving the subsequent binding performance with phenolic resin. Subsequently, phenolic resin is used as a coating layer. With its high char residue rate, it is pyrolyzed at high temperature during the subsequent calcination process to form a relatively dense carbon layer. This carbon layer can serve as a transition layer or binding layer between boron nitride and basalt fiber, improving the interfacial binding strength between the two, thereby enhancing the high-temperature resistance of the basalt fiber.

[0014] Preferably, in step S2, the mass ratio of the organic basalt fiber, deionized water, boric acid, and melamine is 50 - 60:900 - 1000:30 - 40:10 - 20, the temperature of the hydrothermal reaction is 150 - 180°C, and the time is 4 - 5 h. The calcination process is as follows: under an inert atmosphere, raise the temperature to 250 - 300°C at a heating rate of 2 - 3°C / min, hold for 2 - 3 h, then raise the temperature to 500 - 600°C at a heating rate of 4 - 5°C / min, hold for 1 - 2 h, and finally raise the temperature to 850 - 900°C at a heating rate of 20 - 25°C / min, and hold for 20 - 30 min.

[0015] In the present invention, boron nitride is in-situ generated on the organic basalt fiber by the hydrothermal method. Through specific stepwise calcination, while ensuring the formation of the coating, the thermal damage to the basalt fiber matrix itself is minimized. At the same time, the problem of defects or pores generated at the interface due to the gas released by the decomposition of phenolic resin, which weakens the binding force, can also be reduced; both boron nitride and the carbon layer are highly refractory materials with extremely high melting points, delaying the softening and strength loss of the material at high temperatures.

[0016] Preferably, in step S3, the volume ratio of ethanol to water in the ethanol aqueous solution is 3:1, the mass ratio of the composite fiber to γ-mercaptopropyltrimethoxysilane is 60 - 70:5 - 8, the temperature of the stirring reaction is 50 - 60°C, and the time is 3 - 4 h.

[0017] In the present invention, the composite fiber is modified by γ-mercaptopropyltrimethoxysilane, providing mercapto reaction sites, which is beneficial to the subsequent reactions.

[0018] Preferably, in step S4, the mass ratio of the organic composite fiber, lauryl methacrylate, and azobisisobutyronitrile is 60 - 70:4 - 5:0.3 - 0.5, the temperature of the constant-temperature reaction is 80 - 90 °C, and the time is 1.5 - 2.5 h.

[0019] In the present invention, through the thiol-ene reaction, lauryl methacrylate is introduced onto the composite fiber, introducing a flexible organic long chain. This hydrophobic surface can effectively prevent moisture from penetrating along the fiber-matrix interface, significantly reducing the water absorption rate of the composite material, thereby greatly improving the service life and performance stability of the air duct in a humid environment, and reducing the strength reduction, deformation, or powdering caused by moisture absorption; at the same time, the boron nitride / carbon coating itself is an inorganic substance, and its physical and chemical compatibility with the magnesium sulfate matrix is better than that of the bare basalt fiber, which helps to form a stronger physical engagement and improve the mechanical properties of the material.

[0020] The present invention also protects a preparation method of a flame-retardant and high-temperature-resistant material for a fireproof air duct as described above, comprising the following steps: Weigh the raw materials according to the formula, add magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, and a waterproof modifier into a mixer, and mix for 5 - 10 min to obtain a premix. Add the retarder into water and stir evenly to obtain a mixed solution; then add the mixed solution into the premix, mix in a forced mixer for 5 - 8 min, and finally add the modified mineral fiber and continue to stir for 3 - 5 min to obtain a slurry; add the slurry into a mold, perform pressure molding and then curing, and the flame-retardant and high-temperature-resistant material is obtained after the curing is completed.

[0021] Preferably, the pressure of the pressure molding is 2 - 3 MPa, and the time is 3 - 7 min; the curing method is: cure for 24 h under the conditions of a curing temperature of 20 - 25 °C and a humidity of 60 - 70% HR, and then cure for 7 days under the conditions of a temperature of 30 °C and a humidity of 60% HR after demolding.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1)The flame-retardant and high-temperature resistant material for fireproof air ducts provided by the present invention uses a magnesium sulfate cement system with good fire resistance as the base material, and compoundly adds functional fillers such as expanded perlite, mica powder, quartz powder, and silica fume. In particular, basalt fibers that have undergone special multi-step surface modification treatment are introduced as the reinforcement, and a retarder and a waterproof modifier are added at the same time. The finally obtained material not only has excellent flame-retardant performance and significantly improved high-temperature stability, can effectively meet the structural integrity requirements of fireproof air ducts under fire conditions, but also takes into account good mechanical properties, low density, and improved water resistance and durability, overcoming the deficiencies in the comprehensive performance of existing fireproof air duct materials.

[0023] (2)The flame-retardant and high-temperature resistant material for fireproof air ducts provided by the present invention utilizes magnesium oxide and magnesium sulfate to form a magnesium sulfate cement matrix with natural non-combustibility, and compoundly uses expanded perlite to reduce the material density and increase the thermal resistance. Silica fume with high reactivity is introduced to fill the pores between particles and participate in the secondary hydration reaction to generate a denser gel phase. At the same time, high-temperature resistant inert fillers such as mica powder and quartz powder are used in combination. The components act synergistically to prepare a composite material matrix with a dense structure, good thermal stability, and excellent basic fireproof performance. By adding a stearate-based waterproof modifier, the inherent defect of poor water resistance of the magnesium sulfate cement system is effectively improved, and the long-term use durability of the material is enhanced.

[0024] (3)For the flame-retardant and high-temperature resistant material for fireproof air ducts provided by the present invention, the added modified mineral fibers are first activated by nitric acid and pre-coated with phenolic resin to lay a foundation for subsequent treatment and introduce a carbon source. Then, through hydrothermal reaction and stepwise calcination, a dense and high-temperature stable ceramic-like coating is in-situ generated on the fiber surface. By selecting phenolic resin and specific stepwise calcination, the problem of defects or pores generated at the interface due to the gas released by the decomposition of phenolic resin, which weakens the bonding force, is reduced. This coating significantly improves the high-temperature resistance and strength retention rate of basalt fibers themselves. Subsequently, through the bridging action of γ-mercaptopropyltrimethoxysilane and the grafting of lauryl methacrylate, the stress transfer between the fiber and the magnesium sulfate cement matrix is improved by forming a flexible interface, the toughness of the material is increased, and the interface durability may be enhanced. Through multi-step modification, the mineral fibers are endowed with excellent high-temperature stability and interface bonding with the matrix material, enabling them to play a more effective role in bearing and inhibiting crack propagation in fireproof air duct materials, thus significantly improving the overall mechanical properties (especially the mechanical properties at high temperatures), thermal shock resistance, and comprehensive performance of resisting fire damage of the final fireproof air duct materials. Detailed implementation mode

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased through market channels or synthesized from raw materials purchased through market channels.

[0027] In the present invention, the particle size of the magnesium oxide is 300 mesh, the particle size of the expanded perlite is 325 mesh; the length of the basalt fiber is 500 - 700 μm, and the diameter is 10 - 15 μm; the phenolic resin is purchased from Greenlink (Jining) Chemical Technology Co., Ltd., with the brand number TY - 2124; the particle size of the quartz powder is 400 mesh; the particle size of the silica fume is 325 mesh.

[0028] Example 1

[0029] A flame - retardant and high - temperature resistant material for fire - resistant air ducts, by weight, comprises the following raw materials: 65 parts of magnesium oxide, 40 parts of magnesium sulfate, 55 parts of water, 20 parts of expanded perlite, 12 parts of mica powder, 13 parts of modified mineral fiber, 10 parts of quartz powder, 4 parts of silica fume, 0.7 part of sodium tetraborate, 1.3 parts of calcium stearate.

[0030] Among them, the preparation method of the modified mineral fiber comprises the following steps: S1. Add basalt fiber into a nitric acid solution with a mass fraction of 20%, impregnate it at 35 °C for 1.5 h, after the treatment, filter, wash, and dry to obtain pretreated basalt fiber; add 55 g of pretreated basalt fiber into 350 g of ethanol, then add 25 g of phenolic resin, stir at a constant temperature of 65 °C for 1.5 h, after stirring, filter and dry to obtain organic basalt fiber; S2. Add 55 g of the organic basalt fiber in step S1 into 950 g of deionized water, then add 35 g of boric acid and 15 g of melamine, carry out hydrothermal reaction at 170 °C for 4.5 h, after the reaction, filter, wash, and dry. Under an inert atmosphere, raise the temperature to 280 °C at a heating rate of 2.5 °C / min, keep the temperature for 2.5 h, then raise the temperature to 550 °C at a heating rate of 4.5 °C / min, keep the temperature for 1.5 h, and finally raise the temperature to 880 °C at a heating rate of 25 °C / min, keep the temperature for 25 min to obtain composite fiber; S3. Add 65 g of the composite fiber in step S2 into an ethanol aqueous solution (volume ratio of ethanol to water is 3:1), then add 7 g of γ-mercaptopropyltrimethoxysilane, and stir and react at 55 °C for 3.5 h. After the reaction is completed, filter, wash, and dry to obtain the organic composite fiber; S4. Add 65 g of the organic composite fiber in step S3 into 800 mL of toluene, then add 4.5 g of lauryl methacrylate and 0.4 g of azobisisobutyronitrile, and react at a constant temperature of 85 °C for 2 h. After the reaction is completed, filter, wash, and dry to obtain the modified mineral fiber.

[0031] A preparation method of a flame-retardant and high-temperature resistant material for a fire-proof air duct, comprising the following steps: Weigh the raw materials according to the formula. Add magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, and calcium stearate into a blender and mix for 8 min to obtain a premix. Add sodium tetraborate into water and stir evenly to obtain a mixed solution; then add the mixed solution into the premix, mix in a forced blender for 7 min, and finally add the modified mineral fiber and continue to stir for 4 min to obtain a slurry; add the slurry into a mold, press at a pressure of 2.5 MPa for 5 min and then cure. The curing method is: cure for 24 h under the conditions of a curing temperature of 25 °C and a humidity of 65% HR, and then cure for 7 days under the conditions of a temperature of 30 °C and a humidity of 60% HR after demolding to obtain the product.

[0032] Example 2

[0033] A flame-retardant and high-temperature resistant material for a fire-proof air duct, by weight, comprises the following raw materials: 60 parts of magnesium oxide, 35 parts of magnesium sulfate, 45 parts of water, 15 parts of expanded perlite, 10 parts of mica powder, 10 parts of modified mineral fiber, 8 parts of quartz powder, 3 parts of silica fume, 0.5 part of sodium citrate, and 1 part of zinc stearate.

[0034] The preparation method of the modified mineral fiber therein comprises the following steps: S1. Add basalt fiber into a nitric acid solution with a mass fraction of 15%, impregnate and treat at 30 °C for 2 h. After the treatment is completed, filter, wash, and dry to obtain pretreated basalt fiber; add 50 g of the pretreated basalt fiber into 300 g of ethanol, then add 20 g of phenolic resin, and stir at a constant temperature of 60 °C for 2 h. After stirring is completed, filter and dry to obtain organic basalt fiber; S2. Add 50 g of organic basalt fibers in step S1 into 900 g of deionized water, then add 30 g of boric acid and 10 g of melamine, carry out hydrothermal reaction at 150 °C for 5 h. After the reaction is completed, filter, wash, and dry. Under an inert atmosphere, raise the temperature to 250 °C at a heating rate of 2 °C / min, keep the temperature for 3 h, then raise the temperature to 500 °C at a heating rate of 4 °C / min, keep the temperature for 2 h, and finally raise the temperature to 850 °C at a heating rate of 20 °C / min, keep the temperature for 30 min to obtain composite fibers; S3. Add 60 g of the composite fibers in step S2 into an ethanol aqueous solution (volume ratio of ethanol to water is 3:1), then add 5 g of γ-mercaptopropyltrimethoxysilane, stir and react at 50 °C for 4 h. After the reaction is completed, filter, wash, and dry to obtain organically modified composite fibers; S4. Add 60 g of the organically modified composite fibers in step S3 into 800 mL of toluene, then add 4 g of lauryl methacrylate and 0.3 g of azobisisobutyronitrile, carry out a constant-temperature reaction at 80 °C for 2.5 h. After the reaction is completed, filter, wash, and dry to obtain modified mineral fibers.

[0035] A preparation method of a flame-retardant and high-temperature resistant material for a fireproof air duct, comprising the following steps: Weigh raw materials according to the formula. Add magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, calcium stearate, and zinc stearate into a mixer and mix for 5 min to obtain a premix. Add sodium tetraborate and sodium citrate into water, stir evenly to obtain a mixed solution; then add the mixed solution into the premix, mix in a forced mixer for 5 min, and finally add the modified mineral fibers and continue to stir for 3 min to obtain a slurry; add the slurry into a mold, press at a pressure of 2 MPa for 7 min and then carry out curing. The curing method is: cure at a curing temperature of 20 °C and a humidity of 60% HR for 24 h, and after demolding, cure at a temperature of 30 °C and a humidity of 60% HR for 7 days to obtain the product.

[0036] Example 3

[0037] A flame-retardant and high-temperature resistant material for a fireproof air duct, by weight, comprises the following raw materials: 70 parts of magnesium oxide, 45 parts of magnesium sulfate, 60 parts of water, 25 parts of expanded perlite, 15 parts of mica powder, 15 parts of modified mineral fibers, 12 parts of quartz powder, 5 parts of silica fume, 0.8 part of sodium tetraborate, 1.5 parts of zinc stearate.

[0038] The preparation method of the modified mineral fibers therein comprises the following steps: S1. Add basalt fibers to a nitric acid solution with a mass fraction of 20%, immerse and treat at 40 °C for 1 h. After treatment, filter, wash, and dry to obtain pretreated basalt fibers. Add 60 g of the pretreated basalt fibers to 400 g of ethanol, then add 30 g of phenolic resin, stir at a constant temperature of 70 °C for 1 h. After stirring, filter and dry to obtain organic basalt fibers; S2. Add 60 g of the organic basalt fibers in step S1 to 1000 g of deionized water, then add 40 g of boric acid and 20 g of melamine, and carry out a hydrothermal reaction at 180 °C for 4 h. After the reaction, filter, wash, and dry. Under an inert atmosphere, raise the temperature to 300 °C at a heating rate of 3 °C / min, hold for 2 h, then raise the temperature to 600 °C at a heating rate of 5 °C / min, hold for 1 h, and finally raise the temperature to 900 °C at a heating rate of 25 °C / min, hold for 20 min to obtain composite fibers; S3. Add 70 g of the composite fibers in step S2 to an ethanol aqueous solution (volume ratio of ethanol to water is 3:1), then add 8 g of γ-mercaptopropyltrimethoxysilane, and stir and react at 60 °C for 3 h. After the reaction, filter, wash, and dry to obtain organically modified composite fibers; S4. Add 70 g of the organically modified composite fibers in step S3 to 800 mL of toluene, then add 5 g of lauryl methacrylate and 0.5 g of azobisisobutyronitrile, and react at a constant temperature of 90 °C for 1.5 h. After the reaction, filter, wash, and dry to obtain modified mineral fibers.

[0039] A preparation method of a flame-retardant and high-temperature resistant material for a fireproof air duct, comprising the following steps: Weigh raw materials according to the formula. Add magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, calcium stearate, and zinc stearate to a mixer, mix for 10 min to obtain a premix. Add sodium tetraborate and sodium citrate to water, stir evenly to obtain a mixed solution. Then add the mixed solution to the premix, mix in a forced mixer for 8 min, and finally add the modified mineral fibers and continue to stir for 5 min to obtain a slurry. Add the slurry to a mold, press at a pressure of 3 MPa for 3 min and then cure. The curing method is: cure for 24 h under the conditions of a curing temperature of 25 °C and a humidity of 70% HR, and cure for 7 days under the conditions of a temperature of 30 °C and a humidity of 60% HR after demolding to obtain the product.

[0040] Comparative Example 1

[0041] A flame-retardant and high-temperature resistant material for a fireproof air duct, by weight, comprises the following raw materials: 65 parts of magnesium oxide, 40 parts of magnesium sulfate, 55 parts of water, 20 parts of expanded perlite, 12 parts of mica powder, 13 parts of modified mineral fiber, 10 parts of quartz powder, 4 parts of silica fume, 0.7 part of sodium tetraborate, 1.3 parts of calcium stearate.

[0042] The preparation method of the modified mineral fiber includes the following steps: S1. Add basalt fiber into a nitric acid solution with a mass fraction of 20%, impregnate it at 35°C for 1.5 h, filter, wash, and dry after the treatment to obtain pretreated basalt fiber; S2. Add 55 g of the pretreated basalt fiber in step S1 into 950 g of deionized water, then add 35 g of boric acid and 15 g of melamine, carry out hydrothermal reaction at 170°C for 4.5 h, filter, wash, and dry after the reaction. Under an inert atmosphere, raise the temperature to 280°C at a heating rate of 2.5°C / min, keep it warm for 2.5 h, then raise the temperature to 550°C at a heating rate of 4.5°C / min, keep it warm for 1.5 h, and finally raise the temperature to 880°C at a heating rate of 25°C / min, keep it warm for 25 min to obtain a composite fiber; S3. Add 65 g of the composite fiber in step S2 into an ethanol aqueous solution (the volume ratio of ethanol to water is 3:1), then add 7 g of γ-mercaptopropyltrimethoxysilane, stir and react at 55°C for 3.5 h, filter, wash, and dry after the reaction to obtain an organic composite fiber; S4. Add 65 g of the organic composite fiber in step S3 into 800 mL of toluene, then add 4.5 g of lauryl methacrylate and 0.4 g of azobisisobutyronitrile, carry out a constant-temperature reaction at 85°C for 2 h, filter, wash, and dry after the reaction to obtain a modified mineral fiber.

[0043] A preparation method of a flame-retardant and high-temperature resistant material for a fire-proof air duct includes the following steps: Weigh the raw materials according to the formula, add magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, and calcium stearate into a blender, mix for 8 min to obtain a premix. Add sodium tetraborate into water, stir evenly to obtain a mixed solution; then add the mixed solution into the premix, mix in a forced blender for 7 min, and finally add the modified mineral fiber, continue to stir for 4 min to obtain a slurry; add the slurry into a mold, press for 5 min under a pressure of 2.5 MPa and then carry out curing. The curing method is: cure for 24 h under the conditions of a curing temperature of 25°C and a humidity of 65% HR, and cure for 7 days under the conditions of a temperature of 30°C and a humidity of 60% HR after demolding, then it is obtained.

[0044] Compared with Example 1, phenolic resin was not coated on the pretreated basalt fiber in this comparative example.

[0045] Comparative Example 2

[0046] A flame-retardant and high-temperature resistant material for fire-proof air ducts, by weight, comprises the following raw materials: 65 parts of magnesium oxide, 40 parts of magnesium sulfate, 55 parts of water, 20 parts of expanded perlite, 12 parts of mica powder, 13 parts of modified mineral fiber, 10 parts of quartz powder, 4 parts of silica fume, 0.7 part of sodium tetraborate, and 1.3 parts of calcium stearate.

[0047] The preparation method of the modified mineral fiber comprises the following steps: S1. Add basalt fiber into a nitric acid solution with a mass fraction of 20%, impregnate at 35°C for 1.5 h, filter, wash, and dry after the treatment to obtain pretreated basalt fiber; add 55 g of the pretreated basalt fiber into 350 g of ethanol, then add 25 g of phenolic resin, stir at a constant temperature of 65°C for 1.5 h, filter and dry after the stirring to obtain organic basalt fiber; S2. Add 55 g of the organic basalt fiber in step S1 into 950 g of deionized water, then add 35 g of boric acid and 15 g of melamine, carry out hydrothermal reaction at 170°C for 4.5 h, filter, wash, and dry after the reaction. Under an inert atmosphere, raise the temperature to 880°C at a heating rate of 25°C / min, and keep the temperature for 25 min to obtain composite fiber; S3. Add 65 g of the composite fiber in step S2 into an ethanol aqueous solution (volume ratio of ethanol to water is 3:1), then add 7 g of γ-mercaptopropyltrimethoxysilane, stir and react at 55°C for 3.5 h, filter, wash, and dry after the reaction to obtain organic composite fiber; S4. Add 65 g of the organic composite fiber in step S3 into 800 mL of toluene, then add 4.5 g of lauryl methacrylate and 0.4 g of azobisisobutyronitrile, carry out a constant-temperature reaction at 85°C for 2 h, filter, wash, and dry after the reaction to obtain modified mineral fiber.

[0048] A preparation method of a flame-retardant and high-temperature resistant material for fire-proof air ducts comprises the following steps: Weigh the raw materials according to the formula, add magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, and calcium stearate into a mixer, mix for 8 min to obtain a premix. Add sodium tetraborate into water, stir evenly to obtain a mixed solution; then add the mixed solution into the premix, mix in a forced mixer for 7 min, and finally add the modified mineral fiber, continue to stir for 4 min to obtain a slurry; add the slurry into a mold, press at a pressure of 2.5 MPa for 5 min and then carry out curing. The curing method is: cure for 24 h under the conditions of a curing temperature of 25°C and a humidity of 65%HR, and cure for 7 days under the conditions of a temperature of 30°C and a humidity of 60%HR after demolding, thus obtaining the product.

[0049] Compared with Example 1, this comparative example is obtained by one-step calcination in the preparation of composite fibers.

[0050] Comparative Example 3

[0051] A flame-retardant and high-temperature resistant material for fireproof air ducts, by weight, comprises the following raw materials: 65 parts of magnesium oxide, 40 parts of magnesium sulfate, 55 parts of water, 20 parts of expanded perlite, 12 parts of mica powder, 13 parts of modified mineral fiber, 10 parts of quartz powder, 4 parts of silica fume, 0.7 part of sodium tetraborate, 1.3 parts of calcium stearate.

[0052] The preparation method of the modified mineral fiber comprises the following steps: S1. Add basalt fiber into a nitric acid solution with a mass fraction of 20%, impregnate at 35°C for 1.5 h, filter, wash, and dry after treatment to obtain pretreated basalt fiber; add 55 g of pretreated basalt fiber into 350 g of ethanol, then add 25 g of phenolic resin, stir at a constant temperature of 65°C for 1.5 h, filter and dry after stirring to obtain organic basalt fiber; S2. Add 55 g of the organic basalt fiber in step S1 into 950 g of deionized water, then add 35 g of boric acid and 15 g of melamine, carry out hydrothermal reaction at 170°C for 4.5 h, filter, wash, and dry after the reaction. Under an inert atmosphere, raise the temperature to 280°C at a heating rate of 2.5°C / min, keep the temperature for 2.5 h, then raise the temperature to 550°C at a heating rate of 4.5°C / min, keep the temperature for 1.5 h, and finally raise the temperature to 880°C at a heating rate of 25°C / min, keep the temperature for 25 min to obtain the modified mineral fiber.

[0053] A preparation method of a flame-retardant and high-temperature resistant material for fireproof air ducts comprises the following steps: Weigh the raw materials according to the formula, add magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, and calcium stearate into a blender, mix for 8 min to obtain a premix. Add sodium tetraborate into water, stir evenly to obtain a mixed solution; then add the mixed solution into the premix, mix in a forced blender for 7 min, and finally add the modified mineral fiber, continue to stir for 4 min to obtain a slurry; add the slurry into a mold, press for 5 min under a pressure of 2.5 MPa and then carry out curing. The curing method is: cure for 24 h under the conditions of a curing temperature of 25°C and a humidity of 65% HR, and cure for 7 days under the conditions of a temperature of 30°C and a humidity of 60% HR after demolding to obtain the product.

[0054] Compared with Example 1, lauryl methacrylate was not introduced onto the modified mineral fiber in this comparative example.

[0055] The flame-retardant and high-temperature resistant materials for fireproof air ducts prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. Among them, the flexural strength at room temperature was tested according to GB / T 3001-2017 "Refractory materials - Test method for flexural strength at room temperature"; the flexural strength at high temperature was tested according to GB / T 3002-2017 "Refractory materials - Test method for flexural strength at high temperature"; the impact strength was tested according to GB / T 1043.1-2008, and unnotched specimens were selected; the fire resistance was tested according to the standard GB / T 9978.1-2008 and judged according to GB 8624-2012 "Classification of the burning behavior of building materials and products"; Water absorption: The sample was dried to a constant weight at room temperature, and its dry weight was recorded. Then the sample was completely immersed in water for 24 hours, taken out and air-dried, and then its wet weight was weighed. The water absorption was calculated by the following formula: W = (W1 - W2) / W2 × 100%; where W1 is the wet weight and W2 is the dry weight. The test results are shown in Table 1 below.

[0056] Table 1

[0057] As can be seen from Table 1 above, the flame-retardant and high-temperature resistant materials for fireproof air ducts prepared by the present invention have excellent high-temperature resistance and fire resistance, and at the same time have good mechanical properties and waterproof properties, and have good application prospects.

[0058] The above content is a further detailed description of the present invention in combination with specific implementation examples. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

[0059] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A flame-retardant and high-temperature resistant material for fireproof air ducts, characterized in that, By weight, it includes the following raw materials: 60 - 70 parts of magnesium oxide, 35 - 45 parts of magnesium sulfate, 45 - 60 parts of water, 15 - 25 parts of expanded perlite, 10 - 15 parts of mica powder, 10 - 15 parts of modified mineral fiber, 8 - 12 parts of quartz powder, 3 - 5 parts of silica fume, 0.5 - 0.8 part of retarder, 1 - 1.5 parts of waterproof modifier.

2. The flame-retardant and high-temperature resistant material for a fire-proof air duct according to claim 1, characterized in that, By weight, it includes the following raw materials: 65 - 70 parts of magnesium oxide, 40 - 45 parts of magnesium sulfate, 50 - 55 parts of water, 10 - 25 parts of expanded perlite, 12 - 15 parts of mica powder, 13 - 15 parts of modified mineral fiber, 8 - 10 parts of quartz powder, 3 - 4 parts of silica fume, 0.7 - 0.8 part of retarder, 1.2 - 1.5 parts of waterproof modifier.

3. The flame-retardant and high-temperature resistant material for fire-proof air ducts according to claim 1, characterized in that, The retarder is one or two of sodium tetraborate and sodium citrate, and the waterproof modifier is one or two of calcium stearate and zinc stearate.

4. The flame-retardant and high-temperature resistant material for a fireproof air duct according to claim 1, wherein, The preparation method of the modified mineral fiber includes the following steps: S1. Add basalt fiber into nitric acid solution for impregnation treatment. After the treatment is completed, add it into ethanol, then add phenolic resin and carry out constant temperature stirring to obtain organic basalt fiber; S2. Add the organic basalt fiber into deionized water, then add boric acid and melamine for hydrothermal reaction. After the reaction is completed, filter, wash, dry and calcine to obtain composite fiber; S3. Add the composite fiber into an ethanol aqueous solution, then add γ-mercaptopropyltrimethoxysilane and carry out stirring reaction to obtain an organic composite fiber; S4. Add the organic composite fiber into toluene, then add lauryl methacrylate and azobisisobutyronitrile for constant temperature reaction to obtain modified mineral fiber.

5. The flame-retardant and high-temperature resistant material for a fire-proof air duct according to claim 4, wherein, In step S1, the mass concentration of the nitric acid solution is 15 - 20%, the temperature of the impregnation treatment is 30 - 40°C, and the time is 1 - 2 h; the mass ratio of the pretreated basalt fiber, ethanol and phenolic resin is 50 - 60:300 - 400:20 - 30, and the temperature of the constant temperature stirring is 60 - 70°C, and the time is 1 - 2 h.

6. The flame-retardant and high-temperature resistant material for a fire-proof air duct according to claim 4, characterized in that, In step S2, the mass ratio of the organic basalt fiber, deionized water, boric acid and melamine is 50 - 60:900 - 1000:30 - 40:10 - 20, the temperature of the hydrothermal reaction is 150 - 180°C, and the time is 4 - 5 h. The calcination process is: under an inert atmosphere, raise the temperature to 250 - 300°C at a heating rate of 2 - 3°C / min, keep it warm for 2 - 3 h, then raise the temperature to 500 - 600°C at a heating rate of 4 - 5°C / min, keep it warm for 1 - 2 h, and finally raise the temperature to 850 - 900°C at a heating rate of 20 - 25°C / min, and keep it warm for 20 - 30 min.

7. The flame-retardant and high-temperature resistant material for a fireproof air duct according to claim 4, characterized in that, In step S3, the volume ratio of ethanol to water in the ethanol aqueous solution is 3:1, the mass ratio of the composite fiber to γ-mercaptopropyltrimethoxysilane is 60 - 70:5 - 8, and the temperature of the stirring reaction is 50 - 60°C, and the time is 3 - 4 h.

8. The flame-retardant and high-temperature resistant material for a fireproof air duct according to claim 4, characterized in that, In step S4, the mass ratio of the organic composite fiber, lauryl methacrylate, and azobisisobutyronitrile is 60-70:4-5:0.3-0.5, the temperature of the constant temperature reaction is 80-90 °C, and the time is 1.5-2.5 h.

9. A method for preparing a flame-retardant and high-temperature resistant material for a fire-proof air duct according to any one of claims 1-8, characterized in that, It includes the following steps: Weigh the raw materials according to the formula. Add magnesium oxide, magnesium sulfate, expanded perlite, mica powder, quartz powder, silica fume, and waterproof modifier into a mixer and mix for 5-10 min to obtain a premix. Add the retarder into water and stir evenly to obtain a mixed solution. Subsequently, add the mixed solution into the premix, mix in a forced mixer for 5-8 min, and finally add the modified mineral fiber and continue to stir for 3-5 min to obtain a slurry. Add the slurry into a mold, perform pressure molding and then curing. After the curing is completed, it is obtained.

10. The preparation method according to claim 9, characterized in that, The pressure of the pressure molding is 2-3 MPa and the time is 3-7 min; the curing method is: cure for 24 h under the conditions of a curing temperature of 20-25 °C and a humidity of 60-70% HR, and cure for 7 days under the conditions of a temperature of 30 °C and a humidity of 60% HR after demolding.

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