Heat-insulating non-combustible material as well as preparation method and application thereof

Abstract

The invention discloses a heat-insulating non-combustible material as well as a preparation method and application thereof, and belongs to the technical field of heat-insulating non-combustible materials. The preparation method of the material comprises the following steps: (1) mixing and modifying an inorganic flame retardant and a surface modifier to obtain a modified inorganic flame retardant with the particle size of 100-500nm; (2) adding the modified inorganic flame retardant into the graphene oxide solution to obtain a graphene oxide coated modified inorganic flame retardant; (3) mixing 50-60 parts of polyether polyol, 20-30 parts of polyester polyol, 3-5 parts of a foam stabilizer, 2-3 parts of a catalyst, 15-18 parts of a foaming agent, 65-80 parts of modified expandable graphite, 150-200 parts of a graphene oxide coated modified inorganic flame retardant and 0.9-1.5 parts of water to obtain a mixed solution; and (4) adding 100-150 parts of diisocyanate into the mixed solution, stirring, pouring into a mold, foaming and curing, thereby obtaining the polyurethane foaming material. According to the heat-insulating non-combustible material, polyurethane is taken as a matrix, and the graphene-coated inorganic flame retardant is introduced, so that the heat retaining property, the mechanical property and the heat stability of the material are improved on the premise of ensuring the flame retardant property.

Description

[0001] This application claims the priority of a Chinese patent application titled "An adiabatic and non-combustible material, its preparation method and application" with the application number "202410570217.X" filed with the Chinese Patent Office on May 9, 2024. The entire content thereof is incorporated herein by reference. Technical Field

[0002] This application relates to an adiabatic and non-combustible material, its preparation method and application, belonging to the technical field of adiabatic and non-combustible materials. Background Art

[0003] Polyurethane is a commonly used high-quality thermal insulation material with an extremely low thermal conductivity, but its flame retardancy is poor. Currently, its flame retardancy is mainly improved by adding flame retardants to it. Graphene oxide flakes are the products of chemical oxidation and exfoliation of graphite powder. The oxygen-containing groups endow graphene oxide with chemical stability, and also provide surface modification active sites and a large specific surface area for the synthesis of graphene oxide-based materials. During the compounding process with polymer polymers, it can provide a large specific surface area to effectively disperse and adhere to materials, preventing agglomeration. Moreover, graphene oxide flakes have the characteristics of insulation, relatively low thermal conductivity, and certain flame retardancy. Inorganic flame retardants are an important type of flame retardants, widely used in various polymer materials to improve their flame retardancy. However, the compatibility between inorganic flame retardants and polymer materials is poor, which often affects the mechanical properties of the materials. The existing solutions mainly involve compounding graphene with other flame retardants through physical mixing or chemical bonding methods to improve the flame retardancy and compatibility of the flame retardants.

[0004] For example, Patent 201610891811.4 provides a graphene-modified polyurethane thermal insulation board. First, the white material is premixed with graphite powder, graphene, and a flame retardant at normal temperature and pressure in a high-speed disperser to form a white material premix; then the white material premix and the black material are subjected to a polyaddition reaction and foaming in a high-pressure foaming machine to form a foaming mixture; finally, while the foaming mixture is being shaped in a laminator, cement fireproof cloth is laid on the upper and lower surfaces of the mixture to form a graphene-modified polyurethane thermal insulation board. The problem with this technology is that only by the method of high-speed dispersion, the graphite powder, graphene, and white material are mixed, and the mixed solution cannot form a uniform and stable state. The flame retardant will settle, and the graphite powder is also prone to forming aggregates, significantly affecting the product performance.

[0005] Another example is Patent 202010395609.9, which provides a reactive nitrogen and phosphorus modified graphene-modified polyurethane flame retardant material, including: nitrogen and phosphorus modified graphene, isophorone diisocyanate, polyester polyol, catalyst dibutyltin dilaurate, chain extender 1,4-butanediol, and dimethylolpropionic acid.

[0006] In this material, the pentaerythritol bisphosphamide polyol compound is tightly combined with graphene oxide to form a nitrogen and phosphorus modified graphene composite flame retardant. During the polymerization process of isophorone diisocyanate and polyester polyol as monomers, the isocyanate group reacts with the hydroxyl group of the pentaerythritol bisphosphamide polyol compound, enabling the nitrogen and phosphorus modified graphene to enter the molecular chain of polyurethane as a reactive flame retardant. During the combustion process, it promotes the char formation rate and carbonization process on the material surface, endowing the polyurethane material with excellent flame retardant properties.

[0007] Although existing technologies have improved the flame retardant properties and compatibility of flame retardants to a certain extent, there are still some problems and drawbacks. First, existing compounding methods often require complex process conditions and are costly. Second, the flame retardant properties and heat insulation properties of existing composite flame retardants still need to be improved. Finally, existing composite flame retardants may have an adverse impact on other properties of polymer materials (such as mechanical properties, thermal stability, etc.). Summary of the Invention

[0008] To solve the above problems, an adiabatic non-combustible material, its preparation method and application are provided. This adiabatic non-combustible material uses a polyurethane rigid foam material with excellent heat preservation performance as the matrix, and introduces an inorganic flame retardant wrapped with graphene, improving the heat preservation, mechanical properties and thermal stability of the material while ensuring excellent flame retardant properties of the polyurethane rigid foam.

[0009] According to one aspect of the present application, a preparation method of an adiabatic non-combustible material is provided, including the following steps:

[0010] (1) Add an inorganic flame retardant and a surface modifier to a wet grinding mill, conduct primary grinding and modification using zirconium balls, then obtain a powder through spray drying, conduct secondary grinding and screening on the powder to obtain a modified inorganic flame retardant with a particle size of 100 - 500 nm;

[0011] (2) Add the secondary ground modified inorganic flame retardant to a graphene oxide solution, treat it at 30 - 60 °C for 30 - 120 min, and then obtain a modified inorganic flame retardant coated with graphene oxide through spray drying;

[0012] (3) Mix 50 - 60 parts of polyether polyol, 20 - 30 parts of polyester polyol, 3 - 5 parts of foam stabilizer, 2 - 3 parts of catalyst, 15 - 18 parts of blowing agent, 65 - 80 parts of modified expandable graphite, 150 - 200 parts of modified inorganic flame retardant coated with graphene oxide, and 0.9 - 1.5 parts of water to obtain a mixed solution;

[0013] (4) Add 100 - 150 parts of diisocyanate to the mixed solution, stir and then pour it into a mold for foaming and curing to obtain the adiabatic non-combustible material.

[0014] The modified inorganic flame retardant coated with graphene oxide in this application is a composite flame retardant. It uses graphene as the outer layer of the composite flame retardant. Since graphene and expanded graphite have similar chemical structures and surface properties, the modified inorganic flame retardant coated with graphene oxide and the modified expandable graphite can form a suspension solution in the organic phase, effectively solving the problem of uneven mixing of the flame retardant and expanded graphite.

[0015] After the multilayer graphene oxide in the graphene oxide solution is exfoliated, it forms a soft film-like structure, which can coat the inorganic flame retardant. Due to the extremely large specific surface area of graphene oxide, the increase in surface area is conducive to improving the compatibility between the inorganic flame retardant and the polymer material. At the same time, a huge local barrier layer is formed to block the transfer of heat. And graphene oxide has a large number of functional groups such as hydroxyl groups and epoxy groups, as well as vacancy defects, so it can improve the heat insulation performance of the material.

[0016] The modified inorganic flame retardant is at the nanoscale, which can reduce the usage amount of the inorganic flame retardant, effectively reduce the product density, so that there are closed cavities inside the polyurethane material, which can preserve the heat insulation characteristics of the polyurethane to the greatest extent. And after being coated with graphene oxide, it makes the adiabatic non-combustible material locally have the second-phase strengthening characteristics, improves the compressive strength of the material, and reduces the density.

[0017] Preferably, in step (2), the modified inorganic flame retardant is added to the graphene oxide solution after secondary sanding, treated at 40 - 50 °C for 30 - 120 min, and then spray-dried to obtain the modified inorganic flame retardant coated with graphene oxide.

[0018] Optionally, in step (1), the surface modifier is selected from at least one of titanate, silane, and aluminate, and the weight ratio of the inorganic flame retardant to the surface modifier is (8 - 10):1. The above types and dosages of surface modifiers are beneficial to improving the modification effect of the inorganic flame retardant, facilitating the subsequent coating of graphene oxide, and improving the consistency of the graphene oxide coating.

[0019] Optionally, in step (1), the inorganic flame retardant is selected from at least one of alumina, magnesia, aluminum hydroxide, magnesium hydroxide, silicon oxide, and aluminum silicate;

[0020] Preferably, the inorganic flame retardant is selected from alumina and silicon oxide with a weight ratio of 1:1.

[0021] Optionally, in step (2), the concentration of the graphene oxide solution is 0.5 - 0.7%.

[0022] Optionally, in step (2), the weight ratio of the modified inorganic flame retardant to the graphene oxide solution is (50 - 100):1.

[0023] The concentration of the above graphene oxide solution and its ratio with the modified inorganic flame retardant are beneficial to improving the coating efficiency and coating uniformity of graphene oxide on the modified inorganic flame retardant, thereby improving the production efficiency and compatibility with the modified expandable graphite, and thus synergistically improving the flame retardancy, mechanical strength, heat preservation and thermal stability of the material.

[0024] The modified expanded graphite acts as a charring agent, a barrier agent and a smoke suppressant. During the heating process, it will expand violently, with its volume expanding by more than 300 times, forming a good flame isolation layer to prevent the transfer of flame and heat. At the same time, the expanded specific surface area is large, which can adsorb a large amount of smoke.

[0025] Optionally, the particle size of the modified expandable graphite is 0.5 - 10 μm, and the expansion coefficient is 250 - 290 ml / g.

[0026] Optionally, the modification method of the modified expandable graphite is as follows:

[0027] S10: Mix phosphoric acid and urea with a molar ratio of (0.5 - 1):1, react at 80 - 100 °C to obtain urea phosphate, add expandable graphite, a dispersant and an emulsifier to the urea phosphate, continue stirring at 80 - 100 °C to obtain a colloid, emulsify the colloid in an emulsifier and then transfer it to a polymerization furnace to polymerize at 150 - 240 °C and 10 - 45 Kpa to obtain a composite material, cool, dry and crush the composite material to obtain intermediate microspheres A;

[0028] S20: Mix the intermediate microspheres A and N-aminoethyl-3-aminopropyltriethoxysilane in a solvent and heat to 80 °C for reaction, filter, wash and dry to obtain intermediate microspheres B with amino groups;

[0029] S30: React monomer A, a formaldehyde compound and the intermediate microspheres B under an acidic catalyst, filter, wash and dry to obtain intermediate microspheres C, where monomer A is selected from at least one of p-acetoxystyrene, diacetone acrylamide, and benzalacetone;

[0030] S40: Place the intermediate microspheres C in a 3-mercaptopropyltriethoxysilane solution, react under a radical initiator, filter, wash and dry to obtain the modified expandable graphite.

[0031] In this preparation method, ammonium polyphosphate is contained between the graphite layers in the intermediate microsphere A obtained in step S10, which can improve the adhesion force between expandable graphite, thereby enhancing the flame retardant effect of expandable graphite. In step S20, N-aminoethyl-3-aminopropyltriethoxysilane reacts with the intermediate microsphere A to obtain the intermediate microsphere B. Firstly, it can improve the compatibility between the intermediate microsphere B and the polyurethane substrate, enabling the expandable graphite and the matrix to form a uniform and stable state, avoiding the sedimentation and agglomeration of expandable graphite, and thus enhancing the performance uniformity of the polymer matrix and the flame retardant uniformity of expandable graphite on the matrix. Secondly, the intermediate microsphere B contains NH and NH2 groups, which can not only absorb toxic gases, reducing the combustion hazard, but also participate in the reaction of isocyanate to form polyurethane, forming a chemical bond connection with the polyurethane matrix, enhancing the binding force between expandable graphite and the matrix, so that the flame retardant carbon layer is tightly combined with the matrix, enhancing the protection of the matrix, and can also react with the monomer A formaldehyde compound in step S30 to obtain the intermediate microsphere C. Due to the presence of the monomer A substance in the intermediate microsphere C prepared in step S30, functional groups such as benzene rings, carbonyl groups, ester groups, and amino groups can be introduced into the expandable graphite. The benzene ring can strengthen the matrix, improving the mechanical properties of the matrix. The carbonyl group and ester group can further increase the compatibility with the polyurethane matrix, and the amino group can further increase the number of binding sites with the polyurethane matrix and enhance the adsorption of toxic gases. Since the monomer A in step S30 all contains double bonds, in step S40, 3-mercaptopropyltriethoxysilane reacts with the double bonds to obtain a silane-capped modified expandable graphite, which can further improve the dispersibility and stability of expandable graphite in the matrix, and enhance the adhesion force between expandable graphite, increasing the strength and compactness of the flame retardant carbon layer, thereby adsorbing and effectively blocking toxic gases, reducing the harm of toxic gases to the human body.

[0032] In the above step S10, the intermediate microsphere A obtained makes ammonium polyphosphate contained between the graphite layers, not only enhancing the binding force between expandable graphite, increasing the strength of the flame retardant carbon layer, but also synchronously enhancing the flame retardant characteristics of expandable graphite because ammonium polyphosphate itself has flame retardancy. In steps S20 - S40, the surface of expandable graphite contains modified molecular chains. Firstly, it can achieve the adsorption of toxic gases. Secondly, it can improve the compatibility between expandable graphite and the matrix, improve the dispersion uniformity of expandable graphite, avoid the sedimentation or agglomeration of expandable graphite, and also enhance the performance uniformity of the polyurethane composite material. Thirdly, it can chemically combine with the polyurethane matrix, making the flame retardant carbon layer tightly combined with the matrix, achieving the effective blocking of toxic gases, and can also improve the compactness, uniformity, and mechanical strength of the flame retardant carbon layer, being able to resist the impact of open fire or heat convection.

[0033] Due to the more uniform dispersion of the modified expandable graphite prepared by the above method, when it is used as a flame retardant, the usage amount can be effectively reduced, thereby reducing the density of the material, and also avoiding the problem of shedding due to excessive mass when used as an exterior wall of a building.

[0034] Optionally, in step S10, the expandable graphite accounts for 5-30% of the weight of urea phosphate, the dispersant accounts for 0.5% of the weight of urea phosphate, and the emulsifier accounts for 0.5% of the weight of urea phosphate.

[0035] In step S10 above, the homogeneous emulsification process is used to obtain the intermediate microsphere A, which can solve the problem of difficult dispersion between expandable graphite and ammonium polyphosphate emulsion. Under the high shear force of the homogenizing emulsifier, numerous small droplets are formed inside the emulsion, realizing the microstructure of ammonium polyphosphate emulsion wrapping expandable graphite particles. During the polymerization process, the expandable graphite particles can be evenly dispersed, thereby improving the modification effect of ammonium polyphosphate on expandable graphite.

[0036] Since ammonium polyphosphate is contained between the layers of expandable graphite, when ammonium polyphosphate decomposes upon heating, it decomposes into ammonia gas and polymeric phosphoric acid. Ammonia gas can dilute the oxygen concentration, and polymeric phosphoric acid has good thermal stability. After expandable graphite is heated, its volume expands rapidly, which can effectively isolate the oxygen required for combustion. At the same time, it has a porous structure inside, which can absorb the combustion flue gas, reducing the possibility of re-combustion, and can also effectively isolate the oxygen for combustion, improving the flame retardant properties of the material.

[0037] Optionally, in step S20, the weight ratio of intermediate microsphere A to N-aminoethyl-3-aminopropyltriethoxysilane is 1:(1-2);

[0038] The heating reaction time in step S20 is 8-10h.

[0039] A large number of hydroxyl groups are present on the surface of expandable graphite. Through the reaction of N-aminoethyl-3-aminopropyltriethoxysilane and intermediate microsphere A, N-aminoethyl-3-aminopropyltriethoxysilane can react with the hydroxyl groups to achieve the grafting of N-aminoethyl-3-aminopropyltriethoxysilane on the surface of expandable graphite. The above reaction conditions can improve the reaction rate of N-aminoethyl-3-aminopropyltriethoxysilane with intermediate microsphere A and control the amount of N-aminoethyl-3-aminopropyltriethoxysilane on the surface of expandable graphite, thereby synergistically improving the flame retardant, strengthening, adsorption of toxic gases, and densification effects of the modified expandable graphite on the matrix.

[0040] If the weight of N-(2-aminoethyl)-3-aminopropyltriethoxysilane is excessive, the amount of N-(2-aminoethyl)-3-aminopropyltriethoxysilane on the surface of expandable graphite increases. Combining with the reactions in subsequent steps S30 and S40, an excessive number of molecular chains are introduced on the surface of expandable graphite, which instead weakens the binding force between expandable graphite particles. As a result, cracks still exist in the flame-retardant carbon layer, and the flame-retardant and toxic gas barrier effects are reduced. If the weight of N-(2-aminoethyl)-3-aminopropyltriethoxysilane is too small, the modification effect of expandable graphite will be reduced, and the effects of flame-retarding, strengthening, adsorbing toxic gases, and improving compactness on the matrix will all decline.

[0041] Optionally, the weight ratio of monomer A, formaldehyde compound, and intermediate microsphere B in step S30 is (1 - 2):(1 - 3):1;

[0042] The reaction temperature of step S30 is 50 - 60 °C, and the reaction time is 8 - 12 h;

[0043] Preferably, the acidic catalyst is selected from at least one of nicotinic acid, sulfuric acid, acetic acid, and nitric acid.

[0044] The above weight ratio and reaction conditions can improve the reaction efficiency of monomer A, formaldehyde compound, and intermediate microsphere B, promote the reaction of monomer A and formaldehyde compound with the amino group in N-(2-aminoethyl)-3-aminopropyltriethoxysilane, thereby introducing new functional groups, increasing the number of functional groups in intermediate microsphere B, and synergistically improving the flame-retardant and strengthening effects of expandable graphite on the matrix.

[0045] Optionally, monomer A is selected from diacetone acrylamide and benzalacetone;

[0046] The formaldehyde compound is selected from trioxane and / or paraformaldehyde.

[0047] Optionally, the molar ratio of diacetone acrylamide to benzalacetone is 3:1.

[0048] It has been verified that when a single type of monomer A reacts with a formaldehyde-based compound and intermediate microsphere B, after monomer A is attached to intermediate microsphere B, it will hinder the subsequent reaction of monomer A, resulting in a decrease in the reaction participation rate of monomer A. As a result, in the molecular chain on the surface of intermediate microsphere C, a part is capped with monomer A, and the other part is still capped with N-aminoethyl-3-aminopropyltriethoxysilane. Selecting the above-mentioned diacetone acrylamide and benzylidene acetone with a molar ratio of 3:1 as monomer A can increase the reaction participation rate of monomer A, making the reaction rate between N-aminoethyl-3-aminopropyltriethoxysilane on the surface of intermediate microsphere B and monomer A greater than 98%. And it can also endow intermediate microsphere C with two functional groups, amino and benzene ring at the same time, enhancing the mechanical strength of the matrix and the chemical binding property with the matrix, so as to achieve a tight and uniform connection between the modified expandable graphite and the matrix.

[0049] Optionally, in step S40, the weight ratio of intermediate microsphere C to 3-mercaptopropyltriethoxysilane is 1:(5 - 10);

[0050] Preferably, the radical initiator is AIBN, the reaction temperature is 60 - 70 °C, and the reaction lasts for at least 5 h.

[0051] Capping the surface of intermediate microsphere C with monomer A can make the surface of the intermediate microsphere contain a large number of double bonds. In step S40, the reaction between the double bond and the mercapto group can reintroduce the siloxane molecular chain into the modified expandable graphite. At this time, both ends of the molecular chain on the surface of the modified expandable graphite are siloxane molecular chains, which can improve the dispersibility and stability of the modified expandable graphite in the matrix. On the premise of dispersion stability, it can improve the reaction uniformity of the amino group and isocyanate in the molecular chain on the surface of the modified expandable graphite, and further improve the uniformity of chemical binding with the matrix. Embed the modified expandable graphite evenly in the matrix. In a high-temperature environment, the binding force between the modified expandable graphite and the matrix is strong, and it can adsorb and block the toxic matrix of the matrix in the first time, improving the use safety of the material.

[0052] Optionally, the foam stabilizer is hydroxy silicone oil.

[0053] Hydroxy silicone oil has good compatibility with polyurethane materials, can reduce the surface tension of the solid-gas two phases during the foaming process of polyurethane materials, make the bubbles of the material uniform and fine, thereby improving the heat insulation performance, mechanical properties and thermal stability of the material. While playing the role of foam stabilization, it maximally exerts the flame retardant performance, making the material have excellent flame retardant performance, heat insulation performance, mechanical properties and thermal stability.

[0054] The polyol is selected from polyether polyol and polyester polyol, and the hydroxyl value of the polyol is 350 - 650 mg KOH / g.

[0055] The blowing agent is selected from at least one of n-pentane, n-hexane, and cyclohexane;

[0056] The catalyst is selected from at least one of dibutyltin dilaurate, bis(dimethylaminoethyl) ether, N,N-dimethylcyclohexylamine, and 1,4-dimethylpiperazine.

[0057] Preferably, the polyether polyol is selected from polyether triol or polyether tetrol; the polyester polyol is selected from polycaprolactone polyol, polycarbonate polyol, or polyacrylate polyol.

[0058] According to another aspect of the present application, there is provided an adiabatic non-combustible material prepared by the preparation method of the adiabatic non-combustible material described in any one of the above.

[0059] According to still another aspect of the present application, there is provided an application of the adiabatic non-combustible material described above in the field of building thermal insulation materials.

[0060] The beneficial effects of the present application include but are not limited to:

[0061] 1. In the preparation method of the adiabatic non-combustible material of the present application, the problem of uniform dispersion of the inorganic flame retardant is effectively solved by the microcapsule embedding technology. The flame retardant and modified expandable graphite expand into carbon to form a flame barrier layer, effectively preventing the transfer of flame and heat. Under the synergistic flame retardant effect of the above substances, the fire resistance performance can reach Class A non-combustible.

[0062] 2. In the preparation method of the adiabatic non-combustible material of the present application, coating the inorganic flame retardant with graphene oxide can not only solve the problems of dispersion and compatibility of the inorganic flame retardant, but also improve the heat insulation, heat preservation, and mechanical strength of the material, obtaining a material with excellent performance in all directions.

[0063] 3. In the preparation method of the adiabatic non-combustible material of the present application, the foam stabilizer can reduce the surface tension of the solid-gas two phases during the foaming process of the material, making the bubbles of the material uniform and fine, and can also improve the compatibility with the inorganic flame retardant and modified expandable graphite, promoting the uniform dispersion of the inorganic flame retardant and modified expandable graphite during the foaming process, and improving the consistency and various performances of the material.

[0064] 4. The adiabatic non-combustible material of the present application can not only achieve efficient flame retardancy, but also inhibit the smoke generation during combustion, and can adsorb the generated toxic gases to reduce the harmfulness. Detailed Embodiments

[0065] The present application will be described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0066] Unless otherwise specified, the raw materials in the embodiments of the present application are all purchased through commercial channels, and the phosphoric acid is 85% phosphoric acid solution.

[0067] Unless otherwise specified, the methods used in the embodiments of the present application are conventional methods in the prior art.

[0068] The graphene oxide used in Example 2 was prepared by the Hummers method.

[0069] Example 1

[0070] This example relates to the preparation of modified expandable graphite, which includes the following steps:

[0071] S10: Mix phosphoric acid and urea with a molar ratio of (0.5 - 1):1, react at 80 - 100 °C to obtain urea phosphate, add expandable graphite, a dispersant, and an emulsifier to the urea phosphate, continue stirring at 80 - 100 °C to obtain a colloid, emulsify the colloid in an emulsifier and then transfer it to a polymerization furnace to polymerize at 150 - 240 °C and 10 - 45 Kpa to obtain a composite material, cool, dry, and crush the composite material to obtain intermediate microspheres A;

[0072] S20: Mix intermediate microspheres A and N-aminoethyl-3-aminopropyltriethoxysilane in a solvent and heat to 80 °C for reaction, filter, wash, and dry to obtain amino-group-containing intermediate microspheres B;

[0073] S30: React monomer A, a formaldehyde compound, and intermediate microspheres B under an acidic catalyst, filter, wash, and dry to obtain intermediate microspheres C, where monomer A is selected from at least one of p-acetoxystyrene, diacetone acrylamide, and benzalacetone;

[0074] S40: Place intermediate microspheres C in a 3-mercaptopropyltriethoxysilane solution, react under a radical initiator, filter, wash, and dry to obtain the modified expandable graphite.

[0075] Prepare modified expandable graphite 1# - 8# and comparative modified expandable graphite D1# - D4# according to the above preparation steps, specifically as follows:

[0076] Modified expandable graphite 1#

[0077] The preparation method of this modified expandable graphite 1# includes the following steps:

[0078] S10: Mix phosphoric acid and urea with a molar ratio of 0.5:1 and react at 100 °C to obtain urea phosphate. Add expandable graphite, a dispersant, and an emulsifier to the urea phosphate. The expandable graphite accounts for 5% of the weight of the urea phosphate, the dispersant accounts for 0.5% of the weight of the urea phosphate, and the emulsifier accounts for 0.5% of the weight of the urea phosphate. Continue to stir at 100 °C to obtain a colloid. Emulsify the colloid in the emulsifier and then transfer it to a polymerization furnace to polymerize at 240 °C and 10 Kpa to obtain a composite material. Cool, dry, and pulverize the composite material to obtain intermediate microspheres A, and the particle size of the intermediate microspheres A is 0.5 μm;

[0079] S20: Mix intermediate microspheres A and N-aminoethyl-3-aminopropyltriethoxysilane with a weight ratio of 1:1 in N,N-dimethylformamide and heat to 80 °C. React under nitrogen protection for 10 h, filter, wash, and dry to obtain amino-group-containing intermediate microspheres B;

[0080] S30: Mix p-acetoxystyrene, trioxymethylene, and intermediate microspheres B with a weight ratio of 1:1:1 in methanol, slowly add 37% concentrated hydrochloric acid, and the addition amount of the concentrated hydrochloric acid is 30% of the weight of the intermediate microspheres B. Then react at 50 °C under nitrogen protection for 12 h. Neutralize the reaction solution with sodium bicarbonate to neutrality, filter, wash, and dry to obtain intermediate microspheres C;

[0081] S40: Place intermediate microspheres C with a weight ratio of 1:5 in a solution of 3-mercaptopropyltriethoxysilane. The solvent uses a mixed solvent of ethanol and water with a volume ratio of 5:1. Then add AIBN accounting for 1% of the weight of the intermediate microspheres. React at 70 °C under nitrogen protection for 5 h, filter, wash, and dry to obtain modified expandable graphite 1#.

[0082] Modified expandable graphite 2#

[0083] The preparation method of this modified expandable graphite 2# includes the following steps:

[0084] S10: Mix phosphoric acid and urea with a molar ratio of 1:1 and react at 80 °C to obtain urea phosphate. Add expandable graphite, a dispersant, and an emulsifier to the urea phosphate. The expandable graphite accounts for 30% of the weight of the urea phosphate, the dispersant accounts for 0.5% of the weight of the urea phosphate, and the emulsifier accounts for 0.5% of the weight of the urea phosphate. Continue to stir at 80 °C to obtain a colloid. Emulsify the colloid in the emulsifier and then transfer it to a polymerization furnace to polymerize at 150 °C and 45 Kpa to obtain a composite material. Cool, dry, and pulverize the composite material to obtain intermediate microspheres A, and the particle size of the intermediate microspheres A is 10 μm;

[0085] S20: Mix intermediate microspheres A and N-aminoethyl-3-aminopropyltriethoxysilane with a weight ratio of 1:2 in N,N-dimethylformamide and heat to 80 °C. React for 8 h under nitrogen protection, then perform suction filtration, washing, and drying to obtain intermediate microspheres B with amino groups. The reaction equation is as follows:

[0086]

[0087] S30: Mix monomer A, trioxane, and intermediate microspheres B with a weight ratio of 2:3:1 in methanol, slowly add 37% concentrated hydrochloric acid, and the addition amount of concentrated hydrochloric acid is 30% of the weight of intermediate microspheres B. Then react at 60 °C under nitrogen protection for 8 h. Neutralize the reaction solution to neutral with sodium bicarbonate, perform suction filtration, washing, and drying to obtain intermediate microspheres C. Monomer A is selected from diacetone acrylamide and benzalacetone with a molar ratio of 3:1. The reaction equation is as follows:

[0088]

[0089] Wherein R represents monomer A. In this step, both amino groups in intermediate microspheres B can participate in the reaction, thus obtaining two compounds with the structures of formula 1 and formula 2. The proportion of the compound with the structure of formula 1 in the above reaction is greater than 70%;

[0090] S40: Place intermediate microspheres C with a weight ratio of 1:10 in a solution of 3-mercaptopropyltriethoxysilane. The solvent is a mixed solvent of ethanol and water with a volume ratio of 5:1. Then add AIBN accounting for 1% of the weight of intermediate microspheres. React at 60 °C under nitrogen protection for 8 h, and then perform suction filtration, washing, and drying to obtain modified expandable graphite 2#. In this step, the carbon-carbon double bond in monomer A undergoes an addition reaction with 3-mercaptopropyltriethoxysilane.

[0091] Modified expandable graphite 3#

[0092] The difference between this modified expandable graphite 3# and modified expandable graphite 2# is that in step S10, expandable graphite accounts for 40% of the weight of urea phosphate, and the remaining steps are the same as those of modified expandable graphite 2#.

[0093] Modified expandable graphite 4#

[0094] The difference between this modified expandable graphite 4# and modified expandable graphite 2# is that in step S20, the weight ratio of intermediate microspheres A and N-aminoethyl-3-aminopropyltriethoxysilane is 1:0.5, and the remaining steps are the same as those of modified expandable graphite 2#.

[0095] Modified expandable graphite 5#

[0096] The difference between this modified expandable graphite No. 5 and the modified expandable graphite No. 2 is that in step S30, the weight ratio of monomer A, formaldehyde compound and intermediate microsphere B is 0.8:3:1, and the remaining steps are the same as those of the modified expandable graphite No. 2.

[0097] Modified expandable graphite No. 6

[0098] The difference between this modified expandable graphite No. 6 and the modified expandable graphite No. 2 is that in step S30, monomer A is selected from diacetone acrylamide and benzylidene acetone with a molar ratio of 1:3, and the remaining steps are the same as those of the modified expandable graphite No. 2.

[0099] Modified expandable graphite No. 7

[0100] The difference between this modified expandable graphite No. 7 and the modified expandable graphite No. 2 is that in step S40, the weight ratio of intermediate microsphere C and 3-mercaptopropyltriethoxysilane is 1:3, and the remaining steps are the same as those of the modified expandable graphite No. 2.

[0101] Modified expandable graphite No. 8

[0102] The difference between this modified expandable graphite No. 8 and the modified expandable graphite No. 2 is that the particle size of intermediate microsphere A is 15 μm, and the remaining steps are the same as those of the modified expandable graphite No. 2.

[0103] Comparative modified expandable graphite D1#

[0104] The difference between this comparative modified expandable graphite D1# and the modified expandable graphite No. 2 is that step S10 is not carried out, and in step S20, expandable graphite with a weight ratio of 1:2 and N-aminoethyl-3-aminopropyltriethoxysilane are directly reacted. The particle size of the expandable graphite is 10 μm, and the remaining steps are the same as those of the modified expandable graphite No. 2.

[0105] Comparative modified expandable graphite D2#

[0106] The difference between this comparative modified expandable graphite D2# and the modified expandable graphite No. 2 is that steps S20 - S40 are not carried out, and intermediate microsphere A is the final modified expandable graphite, and the remaining steps are the same as those of the modified expandable graphite No. 2.

[0107] Comparative modified expandable graphite D3#

[0108] The difference between this comparative modified expandable graphite D3# and the modified expandable graphite No. 2 is that step S40 is not carried out, and intermediate microsphere C is the final modified expandable graphite, and the remaining steps are the same as those of the modified expandable graphite No. 2.

[0109] Comparative modified expandable graphite D4#

[0110] The difference between this comparative modified expandable graphite D4# and modified expandable graphite 2# is that in step S20, 3-aminopropyltriethoxysilane is used to replace N-aminoethyl-3-aminopropyltriethoxysilane, and the remaining steps are the same as those of modified expandable graphite 2#.

[0111] Test Example 1

[0112] The gas adsorption test was carried out on the above-prepared modified expandable graphite, and the test results are shown in Table 1. The test method is as follows:

[0113] Experimental group: Place 1 g of modified expandable graphite in the non-combustible plate of the reactor, fix and hang the polyurethane board (5 cm long * 5 cm wide * 1 cm thick) without adding a flame retardant in the reactor, introduce oxygen (100 ml / min) into the reactor, and use a lighter device to ignite the polyurethane board for combustion until it burns completely, and test the concentrations of HCN, CO2, CO, NO, and NO2 in the reactor.

[0114] Blank group: Fix and hang the polyurethane board of the same material and size in the reactor, and do not place anything in the non-combustible plate. After the combustion is over, record the concentrations of HCN, CO2, CO, NO, and NO2 in the reactor.

[0115] The polyurethane boards in the experimental group and the blank group were prepared by placing polyether polyol, foam stabilizer, catalyst, foaming agent, and water with a weight ratio of 75:2.7:1.5:1.5:1 in a container, mixing and stirring with a high-speed stirrer for 2 min to obtain a uniformly mixed liquid, and then adding PAPI and stirring at high speed for 20 s. The weight ratio of PAPI to water is 100:1. The mixture was quickly added to the mold for foaming, the temperature of the closed mold was controlled at 65 °C, and it was allowed to cure for 30 min. After the foaming was over, the mold was opened and cut into 5 cm long * 5 cm wide * 1 cm thick.

[0116] The modified expandable graphite prepared in Example 1 was successively tested in the experimental group. According to the comparison of the measured gas concentrations with those of the blank group, the adsorption rate of various gases was calculated. The calculation method is as follows:

[0117] HCN adsorption rate = (blank group HCN concentration - experimental group HCN concentration) / blank group HCN concentration * 100;

[0118] CO2 adsorption rate = (blank group CO2 concentration - experimental group CO2 concentration) / blank group CO2 concentration * 100;

[0119] CO adsorption rate = (blank group CO concentration - experimental group CO concentration) / blank group CO concentration * 100;

[0120] NO adsorption rate = (NO concentration in the blank group - NO concentration in the experimental group) / NO concentration in the blank group * 100;

[0121] NO₂ adsorption rate = (NO₂ concentration in the blank group - NO₂ concentration in the experimental group) / NO₂ concentration in the blank group * 100.

[0122] Table 1

[0123]

[0124] According to the data in Table 1, it can be seen that the modified expandable graphite can adsorb HCN, CO₂, CO, NO, and NO₂. Therefore, when it is used in polyurethane boards, it can adsorb and block the toxic gases generated in the initial stage of combustion, reducing the combustion hazard.

[0125] Example 2

[0126] This example relates to a preparation method of an adiabatic non-combustible material, including the following steps:

[0127] (1) Add the inorganic flame retardant and the surface modifier into a wet sand mill, and perform primary pulverization and modification using zirconium balls. Then, obtain a powder through spray drying. Pulverize the powder for the second time and screen it to obtain a modified inorganic flame retardant with a particle size of 100 - 500 nm;

[0128] (2) Add the modified inorganic flame retardant after secondary sanding into the graphene oxide solution, and treat it at 30 - 60 °C for 30 - 120 min. Then, obtain the modified inorganic flame retardant coated with graphene oxide through spray drying;

[0129] (3) Mix 50 - 60 parts of polyether polyol, 20 - 30 parts of polyester polyol, 3 - 5 parts of foam stabilizer, 2 - 3 parts of catalyst, 15 - 18 parts of foaming agent, 65 - 80 parts of modified expandable graphite, 150 - 200 parts of the modified inorganic flame retardant coated with graphene oxide, and 0.9 - 1.5 parts of water to obtain a mixed solution;

[0130] (4) Add 100 - 150 parts of diisocyanate into the mixed solution, stir it, pour it into a mold for foaming and curing, and then obtain the adiabatic non-combustible material.

[0131] Prepare materials 1# - 6# and comparative material D1# according to the above preparation method. The specific preparation method is as follows:

[0132] Material 1#

[0133] Preparation of modified expandable graphite:

[0134] Expandable graphite with a particle size of 0.5 μm was placed in a vinyltris(β-methoxyethoxy)silane solution. The weight ratio of expandable graphite to vinyltris(β-methoxyethoxy)silane was 8:1. It was stirred at 60 °C for 3 h, and then centrifuged and dried to obtain modified expandable graphite.

[0135] The preparation of Material 1# includes the following steps:

[0136] (1) Magnesium oxide and isopropyl triisostearoyl titanate with a weight ratio of 10:1 were added to a wet sand mill, and were first pulverized and modified using 2 mm zirconium balls. After that, it was spray-dried to obtain a powder, and the powder was secondarily pulverized and sieved by a jet mill to obtain a modified inorganic flame retardant with a particle size of 500 nm;

[0137] (2) The modified inorganic flame retardant was secondarily sanded using 0.3 mm zirconium balls and then added to a graphene oxide solution. The concentration of the graphene oxide solution was 0.7%, and the weight ratio of the modified inorganic flame retardant to the graphene oxide solution was 50:1. It was treated at 30 °C for 120 min, and then spray-dried to obtain a modified inorganic flame retardant coated with graphene oxide;

[0138] (3) By weight, 50 parts of polyether tetrol (hydroxyl value of 400 mg KOH / g), 20 parts of polyacrylate polyol (hydroxyl value of 650 mg KOH / g), 3 parts of hydroxyl silicone oil, 2 parts of dibutyltin dilaurate, 15 parts of n-hexane, 65 parts of modified expandable graphite, 150 parts of modified inorganic flame retardant coated with graphene oxide, and 0.9 parts of water were mixed to obtain a mixed solution;

[0139] (4) 100 parts of hexamethylene diisocyanate were added to the mixed solution. After stirring, it was poured into a mold, heated to 65 °C for foaming and curing for 30 min, and the mold was opened to obtain a heat-insulating and non-combustible material.

[0140] Material 2#

[0141] The particle size of the expandable graphite was 10 μm, and the steps and dosage of the modified expandable graphite were the same as those of Material 1#.

[0142] The preparation of Material 2# includes the following steps:

[0143] (1) Aluminum hydroxide and isopropyl triisostearoyl titanate with a weight ratio of 8:1 were added to a wet sand mill, and were first pulverized and modified using 2 mm zirconium balls. After that, it was spray-dried to obtain a powder, and the powder was secondarily pulverized and sieved by a jet mill to obtain a modified inorganic flame retardant with a particle size of 100 nm;

[0144] (2) The modified inorganic flame retardant is added to the graphene oxide solution after being secondarily sanded with 0.3 mm zirconium balls. The concentration of the graphene oxide solution is 0.5%, and the weight ratio of the modified inorganic flame retardant to the graphene oxide solution is 100:1. It is treated at 60 °C for 30 min, and then spray-dried to obtain the modified inorganic flame retardant coated with graphene oxide;

[0145] (3) By weight, 60 parts of polyether triol (hydroxyl value 350 mg KOH / g), 30 parts of polycarbonate polyol (hydroxyl value 500 mg KOH / g), 5 parts of hydroxyl silicone oil, 3 parts of dibutyltin dilaurate, 18 parts of n-hexane, 80 parts of modified expandable graphite, 200 parts of the modified inorganic flame retardant coated with graphene oxide, and 1.5 parts of water are mixed to obtain a mixed solution;

[0146] (4) 150 parts of hexamethylene diisocyanate are added to the mixed solution. After stirring, it is poured into a mold, heated to 65 °C for foaming and cured for 30 min, and the mold is opened to obtain the adiabatic non-combustible material.

[0147] Material 3#

[0148] The difference between this Material 3# and Material 2# is that aluminum oxide and silicon oxide with a weight ratio of 1:1 are used to replace aluminum hydroxide, and the rest is the same as Material 2#.

[0149] Material 4#

[0150] The difference between this Material 4# and Material 3# is that the modified expandable graphite 2# of Example 1 is used as the modified expandable graphite, and the rest is the same as Material 3#.

[0151] Material 5#

[0152] The difference between this Material 5# and Material 3# is that the comparative modified expandable graphite D1# of Example 1 is used as the modified expandable graphite, and the rest is the same as Material 3#.

[0153] Material 6#

[0154] The difference between this Material 6# and Material 3# is that the comparative modified expandable graphite D2# of Example 1 is used as the modified expandable graphite, and the rest is the same as Material 3#.

[0155] Comparative Material D1#

[0156] The difference between this Comparative Material D1# and Material 3# is that the inorganic flame retardant is not modified and coated with graphene oxide in steps (1) and (2), and aluminum oxide and silicon oxide with a weight ratio of 1:1 are directly used as the inorganic flame retardant in step (3), and the rest is the same as Material 3#.

[0157] Test Example 2

[0158] The materials prepared in Example 2 were tested for density, thermal conductivity, flame retardancy and mechanical properties. The results are shown in Table 2 below. The flame retardancy performance was carried out in accordance with the GB8624-2012 standard.

[0159] Table 2

[0160]

[0161] Test Example 3

[0162] The materials prepared in Example 2 were placed at 60 °C and 50% humidity for 30 days, and then the compressive strength of the materials was tested. The test results are shown in Table 3 below. And the materials prepared in Example 2 were tested for dimensional stability in accordance with GBT8811-2008. The test results are shown in Table 3 below.

[0163] Table 3

[0164]

[0165] As described above, only the embodiments of the present application are concerned. The protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the technical idea and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A preparation method of an adiabatic and non-combustible material, characterized in that, It includes the following steps: (1) Add an inorganic flame retardant and a surface modifier into a wet sand mill, conduct primary pulverization and modification using zirconium balls, then obtain a powder through spray drying. Pulverize the powder again and screen it to obtain a modified inorganic flame retardant with a particle size of 100 - 500 nm; (2) Add the modified inorganic flame retardant after secondary sanding into a graphene oxide solution, treat it at 30 - 60 °C for 30 - 120 min, and then obtain a modified inorganic flame retardant coated with graphene oxide through spray drying; (3) Mix 50 - 60 parts of polyether polyol, 20 - 30 parts of polyester polyol, 3 - 5 parts of foam stabilizer, 2 - 3 parts of catalyst, 15 - 18 parts of blowing agent, 65 - 80 parts of modified expandable graphite, 150 - 200 parts of modified inorganic flame retardant coated with graphene oxide, and 0.9 - 1.5 parts of water to obtain a mixed liquid; (4) Add 100 - 150 parts of diisocyanate into the mixed liquid, stir and then pour it into a mold for foaming and curing to obtain a heat-insulating non-combustible material.

2. The preparation method according to claim 1, characterized in that, In step (1), the surface modifier is selected from at least one of titanate, silane, and aluminate. The weight ratio of the inorganic flame retardant to the surface modifier is (8 - 10):

1.

3. The preparation method according to claim 1, wherein In step (1), the inorganic flame retardant is selected from at least one of aluminum oxide, magnesium oxide, aluminum hydroxide, magnesium hydroxide, silicon oxide, and aluminum silicate.

4. The preparation method according to claim 3, wherein The inorganic flame retardant is selected from aluminum oxide and silicon oxide with a weight ratio of 1:

1.

5. The preparation method according to claim 1, wherein In step (2), the concentration of the graphene oxide solution is 0.5 - 0.7%.

6. The preparation method according to claim 1, characterized in that, In step (2), the weight ratio of the modified inorganic flame retardant to the graphene oxide solution is (50 - 100):

1.

7. The preparation method according to any one of claims 1, characterized in that, The foam stabilizer is hydroxy silicone oil.

8. The preparation method according to claim 1, characterized in that, The modification method of the modified expandable graphite is as follows: S10: Mix phosphoric acid and urea with a molar ratio of (0.5 - 1):1, react at 80 - 100 °C to obtain urea phosphate. Add expandable graphite, dispersant, and emulsifier into the urea phosphate, continue to stir at 80 - 100 °C to obtain a colloid. Emulsify the colloid in an emulsifier and then transfer it to a polymerization furnace to polymerize at 150 - 240 °C and 10 - 45 Kpa to obtain a composite material. Cool, dry, and pulverize the composite material to obtain intermediate microspheres A; S20: Mix the intermediate microspheres A and N - aminoethyl - 3 - aminopropyltriethoxysilane in a solvent and heat to react at 6 to 80 °C, filter, wash, and dry to obtain intermediate microspheres B with amino groups; S30: React monomer A, formaldehyde compound, and the intermediate microspheres B under an acidic catalyst, filter, wash, and dry to obtain intermediate microspheres C. Monomer A is selected from at least one of p - acetoxystyrene, diacetone acrylamide, and benzalacetone; S40: Place the intermediate microspheres C in a 3 - mercaptopropyltriethoxysilane solution, react under a radical initiator, filter, wash, and dry to obtain the modified expandable graphite.

9. A heat-insulating non-combustible material prepared by the preparation method of the heat-insulating non-combustible material according to any one of claims 1 - 8.

10. Application of the heat-insulating non-combustible material according to claim 9 in the field of building thermal insulation materials.

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