Fireproof coating for building structure and preparation method thereof

Abstract

The invention relates to the technical field of building coatings, and discloses a fireproof coating for a building structure and a preparation method thereof.Industrial solid waste silica fume is used as a base material, zinc phytate, graphene oxide and molybdenum disulfide are used as synergistic flame retardants, melamine is used as a synergist, a flame-retardant system is constructed, and the fireproof coating for the building structure is prepared. The silica fume-based composite fireproof coating is prepared by adopting a sol-gel method, the problems that an existing coating is incompatible with a building wall surface and poor in dispersity are solved, and dimethyl silicone oil and polyacrylamide are used as film forming substances, so that the adhesive force of the coating to a base material is increased, and the prepared building coating has very good heat insulation and heat preservation effects; through the synergistic effect of multiple substances, the prepared fireproof coating has a uniform and stable expansion structure and smaller pores, can effectively inhibit transfer of external heat and oxygen to a base material, provides long-time protection for the base material, prolongs the service life of the fireproof coating, synchronously realizes resource utilization of industrial solid wastes, and reduces pollution to the environment.

Description

Technical Field

[0001] The present invention relates to the technical field of building coatings, in particular to a fire retardant coating for building structures and a preparation method thereof. Background Art

[0002] Fire-retardant coatings serve as the "outer coat" of buildings, combustible substrates, and steel structures. They become the first barrier when a fire strikes. This requires that the coatings have more diversified functions. They must not only have a finishing effect, but also have higher requirements for fire retardancy, waterproofing, thermal insulation, and self-cleaning. Intumescent water-based fire-retardant coatings use water-based polymers as film-forming substances and intumescent materials as flame retardant systems. They work through the condensed phase flame retardant mechanism. However, traditional intumescent fire-retardant coatings are rough and loose in film, which can easily cause water seepage and air permeability. Once the building walls are damp and the steel structure is rusted, the fire-retardant coating will crack and fall off, thus losing its fire protection effect.

[0003] In the existing technology, the combustion performance of inorganic thermal insulation materials such as rock wool, mineral wool, glass wool, foam concrete, and vitrified microspheres can reach Class A, have excellent fireproofing effects, stable anti-aging properties, and good bonding with wall bases and plastering layers. However, due to the poor thermal conductivity of inorganic thermal insulation materials, poor thermal insulation performance, and insufficient compatibility with organic resins, pores exist inside the coating, affecting the thermal insulation performance. For example, some coatings use unmodified expanded graphite, which has poor hydrophilicity and is unevenly dispersed in aqueous solutions, forming local defects, shortening the fireproofing period, and making it difficult to achieve ideal thermal insulation and energy-saving effects. The materials may even fail when exposed to water.

[0004] Patent No. CN114806249A discloses a building fire-retardant coating and a preparation method thereof, comprising a functional filler and a base resin; wherein the functional filler comprises ammonium polyphosphate, melamine and titanium dioxide, and the base resin comprises a water-based acrylic resin and pentaerythritol; the patent uses a water-based acrylic resin as the main film-forming substance, and the resin has relatively good adhesion, but the coating achieves its fire-retardant effect through a single intumescent flame retardant mechanism. The coating is prone to carbonization and detachment at high temperatures, and cannot provide continuous heat insulation, making it difficult to meet the fire protection standards of high-rise buildings or industrial plants; Patent No. CN108059898B discloses an environmentally friendly building fire-retardant coating and a preparation method thereof, which uses a calixarene-based organic fluorosilicone film-forming polymer. Although it is environmentally friendly, it has poor adhesion and is prone to debonding after long-term use, resulting in the failure of the fire-retardant function; in addition, the existing coatings also have the problem of poor construction adaptability, that is, the coating is incompatible with the building, the coating is prone to sagging when applied thickly, making it difficult to achieve uniform coating, and the coating is insufficiently thick when applied thinly, resulting in reduced fire-retardant performance.

[0005] The present invention uses industrial solid waste silica fume as a base material, zinc phytate, graphene oxide and molybdenum disulfide as synergistic flame retardants, and melamine as a synergist to construct a flame retardant system, and adopts a sol-gel method to prepare a silica fume-based composite fire-retardant coating, thereby improving the problems of incompatibility and poor dispersibility of existing coatings with building walls, and using dimethyl silicone oil and polyacrylamide as film-forming substances to increase the adhesion of the coating to the substrate, so that the prepared building coating has excellent thermal insulation effect and achieves an excellent finishing effect, while extending the service life of the fire-retardant coating, simultaneously realizing the resource utilization of industrial solid waste, and reducing pollution to the environment. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a fire retardant coating for building structures and a preparation method thereof. The coating can be tightly bonded to the wall, has good bonding performance, is not easy to age, has a small amount of addition, and has excellent wear reduction and anti-wear properties and long-term use.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a fire retardant coating for a building structure is carried out according to the following steps:

[0009] Step (1), weighing melamine, KH560 and zinc phytate modified nano hybrid material, adding them into deionized water, stirring at 80-95° C. and 700-900 r / min for 25-40 min, to obtain phosphorus-nitrogen modified nano hybrid material.

[0010] Step (2), weighing the phosphorus-nitrogen modified nano-hybrid material and adding it to the alkali-activated silica sol, stirring at 1000-1500 r / min for 30-60 min, adding dimethyl silicone oil and polyacrylamide, and continuing to stir for 5-10 min to obtain a fire retardant coating for building structures.

[0011] Preferably, in step (1), the mass ratio of melamine, KH560, and zinc phytate-modified nano-hybrid material is 100:45-55:30-40.

[0012] Preferably, the preparation method of the alkali-activated silica sol in step (2) is: weigh 14.2g of Na2SiO3·9H2O, 5.6g of KOH, 30g of silica ash and 30g of deionized water, mix them, and stir them at 70°C and 1100r / min for 20min to obtain the alkali-activated silica sol.

[0013] Preferably, in step (2), the mass ratio of the phosphorus-nitrogen modified nano-hybrid material, the alkali-activated silica sol, the dimethyl silicone oil, and the polyacrylamide is 20-30:100:3-8:2-5.

[0014] Preferably, the preparation method of the zinc phytate modified nano hybrid material in step (1) is:

[0015] Step S1: Using a hydrothermal method, graphene oxide, hexadecyl ammonium bromide, ammonium molybdate tetrahydrate, thiourea and deionized water are placed in an ultrasonic reactor. After ultrasonic dispersion, the mixture is transferred to a hydrothermal reactor, reacted at 180-200°C for 12-24h, cooled to room temperature, centrifuged at high speed, washed with ethanol and deionized water, and dried to obtain a graphene oxide / MoS2 hybrid material.

[0016] Step S2: Mix polyhydroxy phytate zinc and pentaerythritol glycidyl ether evenly, perform ultrasonic treatment for 20-35 minutes, then add graphene oxide / MoS2 hybrid material, place in a high-speed shear dispersion homogenizer, and vigorously homogenize at room temperature for 20-40 minutes to obtain zinc phytate modified nano hybrid material.

[0017] Preferably, in step S1, the mass ratio of graphene oxide, hexadecylammonium bromide, ammonium molybdate tetrahydrate, and thiourea is 100:20-30:25-35:30-40.

[0018] Preferably, in step S1, the ultrasonic dispersion power is 60-80 kW, and the ultrasonic dispersion time is 1-3 h.

[0019] Preferably, the preparation method of polyhydroxy phytate zinc in step S2 is: 1.5g of pentaerythritol and 10g of phytate zinc are mixed evenly, reacted at 130°C for 3h, vacuum filtered and freeze-dried to obtain.

[0020] Preferably, in step S2, the mass ratio of polyhydroxy phytate zinc, pentaerythritol glycidyl ether, and graphene oxide / MoS2 hybrid material is 100:40-50:10-30.

[0021] By adopting the above technical solution, the beneficial effects of the present invention are:

[0022] (1) Good flame retardancy: The hydroxyl groups of polyhydroxy phytate zinc in phosphorus-nitrogen modified nanohybrid materials can chemically link with the carboxyl groups of graphene oxide / MoS2 hybrid materials. At the same time, melamine as a synergist and KH560 as a modifier can further cross-link with the hydroxyl groups on the surface of silica fume, resulting in good compatibility and improving the bonding strength between the coating material and the substrate material, making the coating have good integrity and not easy to fall off. Zinc phytate can decompose to generate phosphoric acid, metaphosphoric acid and other phosphoric acid groups after heating, which accelerates the dehydration process of the coating and the escape of combustible gases and volatile components. It can form a non-flammable interpenetrating network structure with Si(OH)4 in alkali-activated geopolymers at high temperatures, which helps to promote the formation of a dense and complete silicon-carbon-phosphorus shielding layer. At the same time, the Si-O-Si interpenetrating network structure formed during the combustion of the alkali-activated silica fume-based coating and the Zn 2+ The coordination occurs to form a non-flammable cross-linked network structure, thereby enhancing the strength and density of the shielding layer and improving the flame retardant properties of the composite fire-retardant coating; graphene oxide tends to form a continuous network structure during the combustion process, acting as a "skeleton framework" to support carbonaceous carbon and filling some carbon voids during the formation of the carbon layer; MoS2 has low thermal conductivity and excellent thermal stability, which can improve the strength and thermal insulation properties of the coating; the ammonia released by melamine during thermal decomposition can play an expansion role; the synergistic effect of multiple substances makes the prepared fire-retardant coating have a uniform and stable expansion structure and smaller pores, which can effectively inhibit the transfer of external heat and oxygen to the substrate, providing long-term protection for the substrate.

[0023] (2) Excellent resistance to moisture and heat, aging, scrub and adhesion: The hydroxyl groups of polyhydroxy phytate zinc can chemically link with the carboxyl groups of graphene oxide / MoS2 hybrid materials to form a cross-linked structure, which has excellent wear resistance; at the same time, the epoxy or silyl groups on the surface of the material modified by KH560 can further cross-link with the hydroxyl groups on the surface of silica fume, and have good compatibility. The increase in the cross-linking density of the coating increases the density of the coating, making the coating have good integrity and not easy to fall off; at the same time, graphene oxide not only has the functions of a cross-linking agent and a skeleton agent, but also is an excellent preservative. When graphene oxide is uniformly dispersed in a permeable polymer matrix, because graphene oxide exists in the matrix as a barrier, the infiltration path of corrosive molecules such as H2O and O2 can only diffuse along the gaps and surfaces between the graphene oxide sheets, and they have to pass through a longer and more tortuous path to escape, so that the prepared coating has good aging resistance and long-term fire resistance. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to specific examples; the following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in this application are commercially available or can be prepared by known methods.

[0025] Unless otherwise stated, the raw materials and reagents used in this application are commercially available or can be prepared by known methods.

[0026] Zinc phytate: industrial grade, purchased from Hubei Nona Technology Co., Ltd.

[0027] Preparation of polyhydroxy phytate zinc: 4.36 g of pentaerythritol and 27.23 g of phytate zinc were added to a 250 mL three-necked flask and mixed evenly. The mixture was then heated to 130° C. and reacted for 3 h to obtain a crude product. The crude product was then vacuum filtered and freeze-dried to obtain polyhydroxy phytate zinc.

[0028] Preparation of alkali-activated silica sol: 142.1 g of Na2SiO3·9H2O, 56.1 g of KOH, 300 g of silica ash and 300 g of water were weighed, mixed and then mechanically stirred at 70°C and 1100 r / min for 20 min to obtain alkali-activated silica sol.

[0029] Example 1

[0030] (1) Using the hydrothermal method, 100 g of graphene oxide, 25 g of hexadecyl ammonium bromide, 30 g of ammonium molybdate tetrahydrate, 35 g of thiourea and 1650 mL of deionized water were placed in an ultrasonic reactor. After ultrasonic dispersion at 70 kW for 2 h, the mixture was transferred to a hydrothermal reactor and reacted at 190 ° C for 16 h. The mixture was cooled to room temperature, centrifuged at high speed, washed with ethanol and deionized water, and dried to obtain graphene oxide / MoS2 hybrid material.

[0031] (2) 100 g of polyhydroxy phytate zinc and 45 g of pentaerythritol glycidyl ether were mixed evenly and ultrasonically treated for 25 min. Then, 10 g of graphene oxide / MoS2 hybrid material was added and placed in a high-speed shear dispersion homogenizer. The mixture was vigorously homogenized at room temperature for 30 min to obtain phytate-modified nanohybrid material.

[0032] (3) Weigh 100 g of melamine, 50 g of KH560 and 30 g of zinc phytate-modified nanohybrid material and add them into deionized water. Stir at 85° C. and 800 r / min for 35 min to obtain phosphorus-nitrogen modified nanohybrid material.

[0033] (4) Weigh 20 g of phosphorus-nitrogen modified nanohybrid material and add it to 100 g of alkali-activated silica sol, stir it at 1200 r / min for 45 min, add 5 g of dimethyl silicone oil and 3 g of polyacrylamide, and continue stirring for 8 min to obtain a fire retardant coating for building structures.

[0034] Example 2

[0035] (1) Using the hydrothermal method, 100 g of graphene oxide, 20 g of hexadecyl ammonium bromide, 35 g of ammonium molybdate tetrahydrate, 30 g of thiourea and 1500 mL of deionized water were placed in an ultrasonic reactor. After ultrasonic dispersion at 80 kW for 1 h, the mixture was transferred to a hydrothermal reactor and reacted at 200 °C for 12 h. The mixture was cooled to room temperature, separated by high-speed centrifugation, washed with ethanol and deionized water, and dried to obtain graphene oxide / MoS2 hybrid material.

[0036] (2) 100 g of polyhydroxy phytate zinc and 40 g of pentaerythritol glycidyl ether were mixed evenly and ultrasonically treated for 20 min. Then, 15 g of graphene oxide / MoS2 hybrid material was added and placed in a high-speed shear dispersion homogenizer. The mixture was vigorously homogenized at room temperature for 20 min to obtain phytate-modified nanohybrid material.

[0037] (3) Weigh 100 g of melamine, 45 g of KH560 and 33 g of zinc phytate-modified nanohybrid material and add them into deionized water. Stir at 95° C. and 900 rpm for 25 min to obtain phosphorus-nitrogen modified nanohybrid material.

[0038] (4) Weigh 23 g of phosphorus-nitrogen modified nanohybrid material and add it to 100 g of alkali-activated silica sol, stir it at 1500 r / min for 30 min, add 3 g of dimethyl silicone oil and 5 g of polyacrylamide, and continue stirring for 5 min to obtain a fire retardant coating for building structures.

[0039] Example 3

[0040] (1) Using the hydrothermal method, 100 g of graphene oxide, 30 g of hexadecyl ammonium bromide, 25 g of ammonium molybdate tetrahydrate, 40 g of thiourea and 1800 mL of deionized water were placed in an ultrasonic reactor. After ultrasonic dispersion at 60 kW for 3 h, the mixture was transferred to a hydrothermal reactor and reacted at 180 ° C for 24 h. The mixture was cooled to room temperature, centrifuged at high speed, washed with ethanol and deionized water, and dried to obtain graphene oxide / MoS2 hybrid material.

[0041] (2) 100 g of polyhydroxy phytate zinc and 50 g of pentaerythritol glycidyl ether were mixed evenly and ultrasonically treated for 35 min. Then, 20 g of graphene oxide / MoS2 hybrid material was added and placed in a high-speed shear dispersion homogenizer. The mixture was vigorously homogenized at room temperature for 40 min to obtain phytate-modified nanohybrid material.

[0042] (3) Weigh 100 g of melamine, 55 g of KH560 and 35 g of zinc phytate-modified nanohybrid material and add them into deionized water. Stir at 80° C. and 700 rpm for 40 min to obtain phosphorus-nitrogen modified nanohybrid material.

[0043] (4) Weigh 25 g of phosphorus-nitrogen modified nanohybrid material and add it to 100 g of alkali-activated silica sol, stir at 1100 r / min for 60 min, add 8 g of dimethyl silicone oil and 2 g of polyacrylamide, and continue stirring for 10 min to obtain a fire retardant coating for building structures.

[0044] Example 4

[0045] (1) Using the hydrothermal method, 100 g of graphene oxide, 28 g of hexadecyl ammonium bromide, 32 g of ammonium molybdate tetrahydrate, 36 g of thiourea and 1700 mL of deionized water were placed in an ultrasonic reactor. After ultrasonic dispersion at 75 kW for 2 h, the mixture was transferred to a hydrothermal reactor and reacted at 185 ° C for 15 h. The mixture was cooled to room temperature, centrifuged at high speed, washed with ethanol and deionized water, and dried to obtain graphene oxide / MoS2 hybrid material.

[0046] (2) 100 g of polyhydroxy phytate zinc and 48 g of pentaerythritol glycidyl ether were mixed evenly and ultrasonically treated for 25 min. Then, 25 g of graphene oxide / MoS2 hybrid material was added and placed in a high-speed shear dispersion homogenizer. The mixture was vigorously homogenized at room temperature for 35 min to obtain phytate-modified nanohybrid material.

[0047] (3) Weigh 100 g of melamine, 48 g of KH560 and 38 g of zinc phytate-modified nanohybrid material, add them into deionized water, and stir at 90° C. and 850 r / min for 30 min to obtain phosphorus-nitrogen modified nanohybrid material.

[0048] (4) Weigh 28 g of phosphorus-nitrogen modified nanohybrid material and add it to 100 g of alkali-activated silica sol, stir it at 1200 r / min for 50 min, add 6 g of dimethyl silicone oil and 4 g of polyacrylamide, and continue stirring for 8 min to obtain a fire retardant coating for building structures.

[0049] Example 5

[0050] (1) Using the hydrothermal method, 100 g of graphene oxide, 24 g of hexadecyl ammonium bromide, 28 g of ammonium molybdate tetrahydrate, 36 g of thiourea and 1600 mL of deionized water were placed in an ultrasonic reactor. After ultrasonic dispersion at 65 kW for 3 h, the mixture was transferred to a hydrothermal reactor and reacted at 200 °C for 24 h. The mixture was cooled to room temperature, separated by high-speed centrifugation, washed with ethanol and deionized water, and dried to obtain graphene oxide / MoS2 hybrid material.

[0051] (2) 100 g of polyhydroxy phytate zinc and 48 g of pentaerythritol glycidyl ether were mixed evenly and ultrasonically treated for 30 min. Then, 30 g of graphene oxide / MoS2 hybrid material was added and placed in a high-speed shear dispersion homogenizer. The mixture was vigorously homogenized at room temperature for 35 min to obtain phytate-modified nanohybrid material.

[0052] (3) Weigh 100 g of melamine, 52 g of KH560 and 40 g of zinc phytate-modified nanohybrid material and add them into deionized water. Stir at 90° C. and 750 r / min for 35 min to obtain phosphorus-nitrogen modified nanohybrid material.

[0053] (4) Weigh 30 g of phosphorus-nitrogen modified nanohybrid material and add it to 100 g of alkali-activated silica sol, stir at 1350 r / min for 45 min, add 7 g of dimethyl silicone oil and 5 g of polyacrylamide, and continue stirring for 10 min to obtain a fire retardant coating for building structures.

[0054] Comparative Example 1

[0055] 20 g of zinc phytate-modified nanohybrid material (prepared in Example 1) was weighed and added to 100 g of alkali-activated silica sol, and stirred at 1200 r / min for 45 min. 5 g of dimethyl silicone oil and 3 g of polyacrylamide were added, and stirring was continued for 8 min to obtain a coating for building structures.

[0056] Comparative Example 2

[0057] Weigh 20 g of graphene oxide / MoS2 hybrid material (prepared in Example 1) and add it to 100 g of alkali-activated silica sol. Stir at 1200 r / min for 45 min. Add 5 g of dimethyl silicone oil and 3 g of polyacrylamide, and continue stirring for 8 min to obtain a coating for building structures.

[0058] Comparative Example 3

[0059] 20 g of graphene oxide was weighed and added to 100 g of alkali-activated silica sol, and the mixture was stirred at 1200 r / min for 45 min. 5 g of dimethyl silicone oil and 3 g of polyacrylamide were added, and the mixture was stirred for another 8 min to obtain a coating for building structures.

[0060] Flame retardant performance test: The flame retardant time test (large plate burning method) is carried out in accordance with the provisions of standard GB 12441-2018. During the experiment, the large plate burning method of vertical combustion method can be used for fire resistance limit detection, and the alcohol burner burning method is used to determine the fire retardant performance of the prepared fire retardant coating; the test method is: apply the coating evenly on the test board, place it for 24 hours, and dry it in a drying oven for 48 hours for use. During the experiment, fix the board on the iron frame, turn the painted side down, and align the lamp mouth with the center of the board. Then use an alcohol burner to test the flame retardant performance of the board, with the nozzle 9 cm away from the board. Record the time from burning to cracking and the mass loss at this time.

[0061] Table 1 Flame retardant performance test

[0062] Mass loss (g) Flame retardant time (min) Example 1 4.18 143.8 Example 2 3.63 164.1 Example 3 3.28 170.5 Example 4 2.74 188.3 Example 5 2.51 190.6 Comparative Example 1 4.45 128.0 Comparative Example 2 5.10 112.3 Comparative Example 3 8.32 75.4

[0063] It can be seen from the test results in the above table that with the increase of the content of phosphorus-nitrogen modified nano-hybrid material, the flame retardant performance of the building coating is gradually enhanced, wherein the flame retardant time in Example 4 reaches 188.3min, which is because the hydroxyl group of the polyhydroxy phytic acid zinc in the phosphorus-nitrogen modified nano-hybrid material can produce chemical linkage with the carboxyl group of the graphene oxide / MoS2 hybrid material, while melamine as a synergist and KH560 as a modifier can further produce cross-linking with the hydroxyl group on the surface of the silica fume, with good compatibility, thereby improving the bonding force between the coating material and the substrate material, making the coating have good integrity and not easy to fall off; wherein phytic acid zinc can decompose to generate phosphate groups such as phosphoric acid and metaphosphoric acid after being heated, which accelerates the dehydration process of the coating and the escape of combustible gases and volatile components, and can form a non-flammable interpenetrating network structure with Si(OH)4 in the alkali-activated geopolymer at high temperature, which helps to promote the formation of a dense and complete silicon-carbon-phosphorus shielding layer, while the Si-O-Si interpenetrating network structure formed by the alkali-activated silica fume-based coating during the combustion process and the Zn 2+ The coordination occurs to form a non-flammable cross-linked network structure, thereby enhancing the strength and density of the shielding layer and improving the flame retardant properties of the composite fire-retardant coating; on the other hand, graphene oxide tends to form a continuous network structure during the combustion process, acting as a "skeleton framework" to support carbonaceous carbon and filling part of the carbon voids during the formation of the carbon layer. MoS2 has low thermal conductivity and excellent thermal stability, which can improve the strength and thermal insulation properties of the coating. The ammonia released by melamine during thermal decomposition can play an expansion role; the synergistic effect of multiple substances makes the prepared fire-retardant coating have a uniform and stable expansion structure and smaller pores, which can effectively inhibit the transfer of external heat and oxygen to the substrate, providing long-term protection for the substrate.

[0064] Comparative Example 1 does not contain melamine and has not been modified with KH560, and its flame retardant properties are average; Comparative Example 2 contains only graphene oxide and MoS2, and does not contain phosphorus and nitrogen flame retardant elements, and only exerts flame retardant effect through heat insulation; Comparative Example 3 contains only graphene oxide, and does not produce chemical bonds with any substance. Its layers have strong π-π stacking and hydrophobicity, resulting in poor dispersibility in the coating and the shortest flame retardant time.

[0065] Moisture and heat resistance test: Tested in accordance with GB / T 1740-2007 standard.

[0066] Aging resistance test: Tested in accordance with GB / T 13893-2008 standard.

[0067] Bond strength test: Tested in accordance with GB / T 23445-2009 standard.

[0068] Scrub resistance test: Tested in accordance with GB / T 9756-2018 standard.

[0069] Table 2 Coating performance test

[0070]

[0071]

[0072] The test results in the table above show that with the increase in the content of phosphorus-nitrogen modified nanohybrid materials, the moisture and heat resistance, aging resistance, scrub resistance and adhesion properties of the architectural coatings are gradually enhanced, indicating that the hydroxyl groups of polyhydroxy phytate can chemically link with the carboxyl groups of graphene oxide / MoS2 hybrid materials to form a cross-linked structure, which has excellent wear resistance. At the same time, the epoxy or silyl groups on the surface of the KH560-modified material can further cross-link with the hydroxyl groups on the surface of silica fume, and have good compatibility. The increase in the cross-linking density of the coating increases the density of the coating, making the coating have good integrity and not easy to fall off. At the same time, graphene oxide not only has the functions of a cross-linking agent and a skeleton agent, but also is an excellent preservative. When graphene oxide is uniformly dispersed in a permeable polymer matrix, because graphene oxide exists in the matrix as a barrier, the infiltration path of corrosive molecules such as H2O and O2 can only diffuse along the gaps and surfaces between the graphene oxide sheets, and they have to pass through a longer and more tortuous path to escape, making the prepared coating have good aging resistance and long-term fire resistance.

[0073] The above embodiments are used to illustrate the technical solutions of the present invention rather than to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a fire retardant coating for a building structure, characterized in that: The preparation method is carried out according to the following steps: Step (1), weighing melamine, KH560 and zinc phytate modified nano hybrid material, adding them to deionized water, stirring at 80-95° C. and 700-900 r / min for 25-40 min to obtain a phosphorus-nitrogen modified nano hybrid material; Step (2), weighing the phosphorus-nitrogen modified nano-hybrid material and adding it to the alkali-activated silica sol, stirring at 1000-1500 r / min for 30-60 min, adding dimethyl silicone oil and polyacrylamide, and continuing to stir for 5-10 min to obtain a fire retardant coating for building structures.

2. The method for preparing a fire retardant coating for a building structure according to claim 1, wherein: In the step (1), the mass ratio of melamine, KH560 and zinc phytate modified nano hybrid material is 100:45-55:30-40.

3. The method for preparing a fire retardant coating for a building structure according to claim 1, wherein: The preparation method of the alkali-activated silica sol in step (2) is as follows: 14.2 g of Na2SiO3·9H2O, 5.6 g of KOH, 30 g of silica ash and 30 g of deionized water are weighed, mixed and stirred at 70°C and 1100 r / min for 20 min to obtain the alkali-activated silica sol.

4. The method for preparing a fire retardant coating for a building structure according to claim 1, wherein: In the step (2), the mass ratio of the phosphorus-nitrogen modified nano-hybrid material, the alkali-activated silica sol, the dimethyl silicone oil, and the polyacrylamide is 20-30:100:3-8:2-5.

5. The method for preparing a fire retardant coating for a building structure according to claim 1, wherein: The preparation method of the zinc phytate modified nano hybrid material in step (1) is: Step S1, using a hydrothermal method, graphene oxide, hexadecyl ammonium bromide, ammonium molybdate tetrahydrate, thiourea and deionized water are placed in an ultrasonic reactor, and after ultrasonic dispersion, the mixture is transferred to a hydrothermal reactor, reacted at 180-200° C. for 12-24 hours, cooled to room temperature, centrifuged at high speed, washed with ethanol and deionized water, and dried to obtain a graphene oxide / MoS2 hybrid material; Step S2: Mix polyhydroxy phytate zinc and pentaerythritol glycidyl ether evenly, perform ultrasonic treatment for 20-35 minutes, then add graphene oxide / MoS2 hybrid material, place in a high-speed shear dispersion homogenizer, and vigorously homogenize at room temperature for 20-40 minutes to obtain zinc phytate modified nano hybrid material.

6. The method for preparing a fire retardant coating for a building structure according to claim 5, wherein: In step S1, the mass ratio of graphene oxide, hexadecyl ammonium bromide, ammonium molybdate tetrahydrate, and thiourea is 100:20-30:25-35:30-40.

7. The method for preparing a fire retardant coating for a building structure according to claim 5, wherein: In step S1, the ultrasonic dispersion power is 60-80 kW, and the ultrasonic dispersion time is 1-3 h.

8. The method for preparing a fire retardant coating for a building structure according to claim 5, wherein: The preparation method of polyhydroxy phytate zinc in step S2 is as follows: 1.5 g of pentaerythritol and 10 g of phytate zinc are uniformly mixed, reacted at 130° C. for 3 h, and vacuum filtered and freeze-dried to obtain the polyhydroxy phytate zinc.

9. The method for preparing a fire retardant coating for a building structure according to claim 5, wherein: In step S2, the mass ratio of polyhydroxy phytate zinc, pentaerythritol glycidyl ether, and graphene oxide / MoS2 hybrid material is 100:40-50:10-30.

10. A fire retardant coating for building structures, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 9.

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