Inorganic anticorrosion, antifreezing and flame retardant and its preparation method

Abstract

The application belongs to the technical field of flame retardants, and relates to an inorganic corrosion-resistant and anti-freezing flame retardant and a preparation method thereof.The preparation method comprises the following steps: dissolving polycarbosilane in tetrahydrofuran to obtain a polycarbosilane solution; adding modified boron nitride nanosheets and modified nano magnesium hydroxide into the polycarbosilane solution and mixing and stirring, and then drying after the stirring is completed to obtain the inorganic corrosion-resistant and anti-freezing flame retardant.The inorganic corrosion-resistant and anti-freezing flame retardant provided by the application takes modified nano magnesium hydroxide as a main flame retardant, and is compounded with modified boron nitride nanosheets, polycarbosilane and a small amount of ethylene glycol, so that a synergistic effect is generated with magnesium hydroxide, and the flame retardant performance, the corrosion-resistant performance and the anti-freezing performance of the composite material are improved together.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flame retardants, and relates to an inorganic corrosion-resistant and anti-freezing flame retardant and a preparation method thereof. BACKGROUND

[0002] In today's society, with the rapid development of industrialization and urbanization, fire safety has become the focus of people's increasing concern. Although traditional fire-fighting technology can meet the needs of fire extinguishing and protection to a certain extent, it often appears to be inadequate when facing complex and variable fire environments and extreme climate conditions. Especially in the three key areas of corrosion resistance, anti-freezing and flame retardation, existing technologies can only address one of them individually, and there is a lack of innovative products that can comprehensively solve these problems.

[0003] Firstly, in terms of flame retardation, with the increasing application of new synthetic materials, the complexity and danger of fires are also increasing. Although traditional flame retardants can suppress the spread of fire to a certain extent, they often have poor environmental performance and are harmful to the human body.

[0004] Secondly, in terms of corrosion resistance, many fire-fighting equipment and pipelines are easily eroded by various chemicals due to long-term exposure to harsh environments, leading to performance degradation or even failure. Traditional fire-fighting agents often only focus on fire extinguishing effects, ignoring their corrosive effects on equipment and pipelines, thereby increasing maintenance costs and safety hazards.

[0005] Thirdly, in terms of anti-freezing, fire-fighting systems in cold regions face severe challenges. In low-temperature environments, fire-fighting water and extinguishing agents are prone to freezing, causing pipeline blockage and equipment malfunction, which seriously affects the emergency response capability of the fire-fighting system. Although the anti-freezing products on the market can solve certain freezing problems, they often conflict with the performance of fire-fighting agents, making it difficult to meet the needs of anti-freezing and fire extinguishing. At the same time, the combination of flame retardants with corrosion resistance and anti-freezing performance has always been a technical difficulty.

[0006] In summary, existing fire-fighting technology has obvious shortcomings and limitations in corrosion resistance, anti-freezing and flame retardation. In order to meet the growing demand for fire safety, there is an urgent need for a new type of fire-fighting product that can simultaneously solve these three problems. SUMMARY

[0007] In view of the shortcomings of the prior art, the purpose of the present application is to provide an inorganic corrosion-resistant and anti-freezing flame retardant and a preparation method thereof. The inorganic corrosion-resistant and anti-freezing flame retardant provided by the present application uses modified nano-magnesium hydroxide as the main flame retardant, and is compounded with modified boron nitride nanosheets, polycarbosilane and a small amount of ethylene glycol. The synergistic effect of magnesium hydroxide improves the flame retardation, corrosion resistance and anti-freezing performance of the composite material.

[0008] To achieve the above object, the present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a preparation method of an inorganic anticorrosion antifreezing flame retardant, which comprises:

[0010] (I) calcining hexagonal boron nitride to obtain a calcined product, dispersing the calcined product and 2-amino-5-mercapto-1,3,4-thiadiazole in deionized water and performing ultrasonic exfoliation to obtain a boron nitride suspension; centrifuging the boron nitride suspension, taking the supernatant, performing suction filtration and drying to obtain boron nitride nanosheets; modifying the boron nitride nanosheets with dopamine to obtain modified boron nitride nanosheets;

[0011] (II) dissolving magnesium chloride hexahydrate in an ethanol aqueous solution to obtain a magnesium chloride solution, adding polyethylene glycol 2000 to the magnesium chloride solution, mixing uniformly to obtain a magnesium chloride mother liquor; under the conditions of stirring and heating, dropping the magnesium chloride mother liquor into an ammonia water solution to cause a precipitation reaction, obtaining a magnesium hydroxide suspension after the reaction, centrifuging, washing and drying the magnesium hydroxide suspension to obtain nanometer magnesium hydroxide; modifying the nanometer magnesium hydroxide with oleic acid to obtain modified nanometer magnesium hydroxide;

[0012] (III) dissolving polycarbosilane in tetrahydrofuran to obtain a polycarbosilane solution; adding the modified boron nitride nanosheets obtained in step (I), the modified nanometer magnesium hydroxide obtained in step (II) and ethylene glycol to the polycarbosilane solution and mixing and stirring to obtain the inorganic anticorrosion antifreezing flame retardant.

[0013] The inorganic anticorrosion antifreeze flame retardant provided by the application takes modified nanometer magnesium hydroxide as a main flame retardant, and is compounded with modified boron nitride nanosheet, polycarbosilane and a small amount of ethylene glycol, so that the inorganic anticorrosion antifreeze flame retardant produces a synergistic effect with magnesium hydroxide and improves the flame retardation performance, anticorrosion performance and antifreeze performance of the composite material. The addition of the modified boron nitride nanosheet significantly inhibits the heat release behavior and smoke release behavior of the composite material, greatly reduces the peak heat release rate, total heat release, smoke release rate and total smoke release amount of the composite material, and increases the residual carbon amount. In addition, the boron nitride nanosheet is fully dispersed in the coating and can play a physical barrier role on the corrosive medium, form a "labyrinth" effect in the coating, enhance the anticorrosion performance of the coating, make the diffusion channel of the corrosive medium (such as H2O, O2 and Cl-) penetrating into the coating more tortuous, and thus improve the barrier and anticorrosion performance of the coating. The addition of the polycarbosilane promotes the thermal degradation of the composite material into carbon, is conducive to reducing the thermal weight loss rate of the composite material, improves the stability of the carbon layer, effectively inhibits the degradation of the main chain, and significantly reduces the release of heat and smoke in combustion. The ethylene glycol as an antifreeze can endow the inorganic anticorrosion antifreeze flame retardant with certain antifreeze performance.

[0014] The inorganic anticorrosion antifreeze flame retardant provided by the application can be added into wood paint, industrial paint and wall paint. When the inorganic anticorrosion antifreeze flame retardant is added into wood paint, the flame retardation performance of the wood paint can be significantly improved, the limiting oxygen index is more than 30%, and the inorganic anticorrosion antifreeze flame retardant can be widely used in furniture wood products, wooden structure houses, ancient wood buildings and ancient building group protection buildings. When the inorganic anticorrosion antifreeze flame retardant is added into industrial paint, the anticorrosion performance of the industrial paint can be significantly improved, and the paint film formed has high hardness, high gloss and strong adhesion, and the inorganic anticorrosion antifreeze flame retardant can be widely used in the anticorrosion of steel structures, pipelines, storage tanks, tank cars and equipment surfaces in the chemical, mechanical, shipbuilding and metallurgical industries. When the inorganic anticorrosion antifreeze flame retardant is added into wall paint, the antifreeze performance of the wall paint can be significantly improved, the wall paint can withstand long-term freezing at a low temperature below-15 DEG C without changing properties, and the inorganic anticorrosion antifreeze flame retardant can effectively prevent the occurrence of phenomena such as cracking and peeling of the wall paint caused by freezing.

[0015] The boron nitride nanosheet has a unique sheet structure and a large specific surface area, can promote the formation of a carbon layer in the combustion process of the composite material, play an effective barrier role, and improve the flame retardant performance of the composite material. Meanwhile, the boron nitride nanosheet also has excellent thermal conductivity, and after being compounded with the modified nano magnesium hydroxide, the contact thermal resistance between the modified nano magnesium hydroxide is reduced by increasing the action area, thereby being beneficial to the formation of a continuous and stable thermal conduction network structure. In addition, the barrier effect of the boron nitride nanosheet inhibits the overflow of combustible substances generated in the combustion process of the composite material, and the uniform heat dispersion makes the surface migration and aggregation of the two-dimensional inorganic filler increase, which is beneficial to promoting the formation of a carbon layer. The boron nitride nanosheet and the thermal oxidative degradation product of polycarbosilane jointly form a dense carbon layer, inhibit the heat release behavior, and reduce the smoke release during the combustion of the material, which shows that the boron nitride nanosheet and the polycarbosilane have a synergistic flame retardant effect, and can jointly inhibit the combustion behavior of the composite material.

[0016] In the process of preparing the boron nitride nanosheet, first, the hexagonal boron nitride is subjected to high-temperature calcination treatment. The hexagonal boron nitride without high-temperature calcination treatment has coarse particles, is tightly packed, and the single particle is in a flat block shape, and the surface and edge are relatively smooth. After high-temperature calcination treatment, the hexagonal boron nitride is in a sheet structure, the edge and surface become rough, and the packing becomes loose, which is beneficial to subsequent peeling into a two-dimensional sheet structure by external force. The reason for this change in morphology is that, under high-temperature conditions, oxygen atoms in the air penetrate into the sheet layers of the hexagonal boron nitride, destroy the original dense lattice structure of the hexagonal boron nitride, effectively weaken the van der Waals force between adjacent sheet structures, so that the interaction between the layers of the hexagonal boron nitride is weakened, and then the morphology of the hexagonal boron nitride changes obviously. This change in morphology enables the hexagonal boron nitride to more quickly and effectively form boron nitride nanosheets in subsequent ultrasonic peeling.

[0017] The boron nitride nanosheet with a two-dimensional sheet structure has high permeation resistance and a specific surface area, and when it is uniformly dispersed in a coating system, it can effectively block the penetration of water molecules, oxygen, and corrosive ions, can play a physical barrier role on corrosive media, form a “labyrinth” effect in the coating, enhance the corrosion resistance of the coating, and make the diffusion channel of the corrosive medium (such as H2O, O2, Cl - ) penetrating into the coating more tortuous, thereby enhancing the barrier and corrosion resistance of the coating.

[0018] But on the one hand, due to the difference in electronegativity between B atoms and N atoms in boron nitride nanosheets, there is strong interaction between layers, which makes boron nitride nanosheets prone to serious aggregation in the coating, resulting in uneven dispersion and unable to form an effective "labyrinth" effect. In addition, in the case of boron nitride nanosheet aggregation, the penetration of water and corrosive medium will cause the corrosion of the substrate and the decrease of the adhesion between the coating and the substrate, and finally the coating loses the protective performance. In order to avoid the occurrence of boron nitride nanosheet aggregation in the substrate material and make its excellent performance unable to be fully played, dopamine is used to modify the surface of boron nitride nanosheet.

[0019] On the other hand, the coating itself cannot inhibit the corrosion process of the metal, when the seawater and other corrosive media penetrate into the interface between the coating and the substrate due to capillary phenomenon, mechanical scratching of the coating and other reasons, the corrosion protection ability of the coating will be weakened or even lost. Therefore, the physical barrier effect of boron nitride nanosheet can only play a passive protection role, which is far from enough to improve the long-term corrosion resistance of the coating. In order to further improve the active protection ability of the coating itself, the present application uses corrosion inhibitor 2-amino-5-mercapto-1,3,4-thiadiazole (ATT) as the intercalating agent of hexagonal boron nitride, under the condition of liquid phase assisted ultrasonic, ATT is used to exfoliate hexagonal boron nitride, and boron nitride nanosheet modified by intercalation of corrosion inhibitor is obtained. The modification and exfoliation of ATT increase the interlayer spacing of hexagonal boron nitride, weaken the interlayer force, alleviate the aggregation of boron nitride nanosheet, and improve the dispersion uniformity of boron nitride nanosheet in the coating, so that boron nitride nanosheet can be uniformly dispersed in the coating and fully play its physical barrier effect. At the same time, by intercalating hexagonal boron nitride with ATT, ATT is encapsulated between the layers of boron nitride nanosheet, and boron nitride nanosheet becomes the corrosion container of ATT. Compared with directly adding ATT in the flame retardant, encapsulating ATT by boron nitride nanosheet can realize the controlled release of ATT, so as to protect ATT to a certain extent. In addition, by encapsulating ATT with boron nitride nanosheet, ATT is isolated from other coating raw materials, avoiding the reaction of ATT with other raw materials in the coating for a long time, which may cause coating damage or ATT decomposition failure.

[0020] The application utilizes high-temperature calcination combined with liquid-phase ultrasonic-assisted ATT intercalation and exfoliation to prepare boron nitride nanosheets intercalated by ATT, the addition of the boron nitride nanosheets fully plays the physical barrier effect of two-dimensional nanofillers, and the diffusion path of the corrosion medium is extended by being uniformly dispersed in the coating to produce a "labyrinth effect". ATT diffuses in the coating to the interface between the coating and the substrate, and is adsorbed on the surface of the substrate to form a dense protective film, thereby delaying the corrosion process of the substrate metal, and the passive protection mechanism of the boron nitride nanosheets is combined with the active protection mechanism of ATT to synergistically enhance the long-acting corrosion resistance of the inorganic corrosion-resistant, anti-freezing and flame-retardant agent.

[0021] The flame-retardant effect of magnesium hydroxide is related to its morphology, particle size, purity and the like, the superfine nanometer magnesium hydroxide prepared by the application has a smaller particle size and a larger specific surface area, can increase the contact area between the nanometer magnesium hydroxide and the base material, effectively play the flame-retardant effect of the nanometer magnesium hydroxide, and at the same time, the surface modification of the nanometer magnesium hydroxide can improve the interfacial compatibility between the nanometer magnesium hydroxide and the base material, effectively alleviate or even avoid the agglomeration of the nanometer magnesium hydroxide in the base material, which not only can reduce the addition amount of the nanometer magnesium hydroxide, but also is beneficial to improving the mechanical properties and processing properties of the composite material.

[0022] Since the magnesium hydroxide itself has a positive charge and a high potential, the negatively charged anionic surfactant oleic acid is used to change the interfacial properties of the magnesium hydroxide, the carboxyl in the molecular structure of the oleic acid can undergo a weak esterification reaction with the hydroxyl on the surface of the nanometer magnesium hydroxide, and the unsaturated double bond in the molecular structure of the oleic acid can undergo a polymerization reaction with the base material, thereby improving the compatibility and dispersibility of the nanometer magnesium hydroxide in the coating, and making the nanometer magnesium hydroxide become the active center of the composite and be wrapped by the base material, so as to effectively improve the mechanical properties and processing rheological properties of the composite material.

[0023] The Si-O bond on the molecular chain of polycarbosilane has good thermal stability and unique low-temperature ceramicization capability, which can significantly improve the thermal stability and flame retardancy of the composite material; in addition, polycarbosilane will undergo crosslinking and organic-inorganic transformation in the process of thermal oxidative degradation, thereby participating in the formation of a carbon layer; at the same time, polycarbosilane can form Si-O-Si and Si-C-Si structures in the process of thermal oxidative degradation, which is beneficial to improving the carbon layer structure and plays a certain supporting role for the carbon layer, generating a composite carbon layer with oxygen and heat insulation, preventing the diffusion of flammable gas, so as to achieve the flame-retardant effect.

[0024] During the thermal oxidative degradation of the composite material, the modified boron nitride nanosheets accumulated on the surface of the carbon layer, resulting in a high content of modified boron nitride nanosheets on the surface of the carbon layer. At the same time, the Si-O-Si crosslinking network formed by the thermal oxidative degradation of polycarbosilane was generated on the surface of the carbon layer. The accumulation of modified boron nitride nanosheets and the Si-O-Si crosslinking network on the surface of the carbon layer together promoted the formation of the condensed phase surface carbon layer. The large specific surface area and lamellar structure of the modified boron nitride nanosheets and the Si-O-Si structure with high thermal stability together formed a dense and stable condensed phase carbon layer. The surface pores and cracks of the condensed phase carbon layer formed after combustion were less, and the carbon layer showed high density and continuity. The internal structure of the carbon layer formed a rich pore structure, and the holes in the carbon layer section changed from vertical holes connected to the outside to bubble structures connected to each other inside the carbon layer. The stability and thermal insulation of this carbon layer structure were higher, which could effectively inhibit the escape of thermal degradation gas, help to inhibit the conduction of combustion heat and the rise of the substrate temperature, thereby inhibiting the heat release and smoke release during the combustion of the composite material.

[0025] As a preferred technical solution of the present application, in step (I), the calcination temperature of the hexagonal boron nitride is 800-900℃, for example, it can be 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃ or 900℃, but not limited to the listed values, other values not listed in this range are also applicable.

[0026] In some optional examples, the calcination time of the hexagonal boron nitride is 1-2h, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but not limited to the listed values, other values not listed in this range are also applicable.

[0027] In some optional examples, the mixing ratio of the calcination product, 2-amino-5-mercapto-1,3,4-thiadiazole and deionized water is 1g:(1.3-1.5)g:(200-300)mL, for example, it can be 1g:1.3g:200mL, 1g:1.32g:210mL, 1g:1.34g:220mL, 1g:1.36g:230mL, 1g:1.38g:240mL, 1g:1.4g:250mL, 1g:1.42g:260mL, 1g:1.44g:270mL, 1g:1.46g:280mL, 1g:1.48g:290mL or 1g:1.5g:300mL, but not limited to the listed values, other values not listed in this range are also applicable.

[0028] In some optional examples, the ultrasonic peeling ultrasonic power is 500-600W, for example, can be 500W, 510W, 520W, 530W, 540W, 550W, 560W, 570W, 580W, 590W or 600W, but not limited to the listed values, other values in the range of values are also applicable.

[0029] In some optional examples, the ultrasonic peeling time is 4-5h, for example, can be 4.0h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5.0h, but not limited to the listed values, other values in the range of values are also applicable.

[0030] In some optional examples, the centrifugal speed of the boron nitride suspension is 2000-3000r / min, for example, can be 2000r / min, 2100r / min, 2200r / min, 2300r / min, 2400r / min, 2500r / min, 2600r / min, 2700r / min, 2800r / min, 2900r / min or 3000r / min, but not limited to the listed values, other values in the range of values are also applicable.

[0031] In some optional examples, the centrifugal time of the boron nitride suspension is 30-40min, for example, can be 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min or 40min, but not limited to the listed values, other values in the range of values are also applicable.

[0032] As a preferred technical solution of the present application, in step (I), the modified boron nitride nanosheet is prepared by the following method:

[0033] The boron nitride nanosheet is added to the Tris-HCl buffer solution, ultrasonic dispersion is carried out to obtain a modified boron nitride suspension, dopamine is added to the modified boron nitride suspension, and mixing and stirring are carried out to react, and after the reaction is completed, the modified boron nitride nanosheet is obtained after filtration, washing and drying.

[0034] As a preferred technical solution of the present application, the pH value of the Tris-HCl buffer solution is 7-8, for example, can be 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9 or 8.0, but not limited to the listed values, other values in the range of values are also applicable.

[0035] In some optional examples, the ratio of the boron nitride nanosheets to the Tris-HCl buffer solution is (0.3-0.5) g: 100 mL, which can be 0.3 g: 100 mL, 0.32 g: 100 mL, 0.34 g: 100 mL, 0.36 g: 100 mL, 0.38 g: 100 mL, 0.4 g: 100 mL, 0.42 g: 100 mL, 0.44 g: 100 mL, 0.46 g: 100 mL, 0.48 g: 100 mL, or 0.5 g: 100 mL, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0036] In some optional examples, the power of the ultrasonic dispersion of the boron nitride nanosheets and the Tris-HCl buffer solution is 200-300 W, which can be 200 W, 210 W, 220 W, 230 W, 240 W, 250 W, 260 W, 270 W, 280 W, 290 W, or 300 W, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0037] In some optional examples, the time of the ultrasonic dispersion of the boron nitride nanosheets and the Tris-HCl buffer solution is 50-60 min, which can be 50 min, 51 min, 52 min, 53 min, 54 min, 55 min, 56 min, 57 min, 58 min, 59 min, or 60 min, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0038] In some optional examples, the mass ratio of the boron nitride nanosheets in the modified boron nitride suspension to the dopamine is (1.8-2): 1, which can be 1.8: 1, 1.82: 1, 1.84: 1, 1.86: 1, 1.88: 1, 1.9: 1, 1.92: 1, 1.94: 1, 1.96: 1, 1.98: 1, or 2.0: 1, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0039] In some optional examples, the time of the mixing and stirring of the modified boron nitride suspension and the dopamine is 5-8 h, which can be 5.0 h, 5.5 h, 6.0 h, 6.5 h, 7.0 h, 7.5 h, 8.0 h, 8.5 h, 9.0 h, 9.5 h, or 10.0 h, but is not limited to the listed values, and other non-listed values within the range are also applicable.

[0040] In some optional examples, the temperature of the mixing and stirring of the modified boron nitride suspension and dopamine is 20-30℃, for example, it can be 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃ or 30℃, but not limited to the listed values, and other values not listed in the range are also applicable.

[0041] As a preferred technical solution of the present application, in step (II), the volume ratio of ethanol to water in the aqueous ethanol solution is 1:(1.5-2), for example, it can be 1:1.5, 1:1.55, 1:1.6, 1:1.65, 1:1.7, 1:1.75, 1:1.8, 1:1.85, 1:1.9, 1:1.95 or 1:2.0, but not limited to the listed values, and other values not listed in the range are also applicable.

[0042] In some optional examples, the concentration of magnesium chloride hexahydrate in the magnesium chloride solution is 0.3-0.4 g / mL, for example, it can be 0.3 g / mL, 0.31 g / mL, 0.32 g / mL, 0.33 g / mL, 0.34 g / mL, 0.35 g / mL, 0.36 g / mL, 0.37 g / mL, 0.38 g / mL, 0.39 g / mL or 0.4 g / mL, but not limited to the listed values, and other values not listed in the range are also applicable.

[0043] The present application particularly limits the concentration of magnesium chloride hexahydrate in the magnesium chloride solution to be 0.3-0.4 g / mL, as the concentration of magnesium chloride hexahydrate increases, the average particle size of the nano-magnesium hydroxide tends to gradually increase, because as the concentration of magnesium ions in the magnesium chloride solution increases, the supersaturation of the crystal slurry rapidly increases, the hydration reaction speed accelerates, the crystal nucleation speed is greater than the crystal growth speed, and the fine crystal nuclei are aggregated with each other to reduce the surface energy; and as the concentration of magnesium ions increases, the probability of mutual collision during the nucleation and growth of the nano-magnesium hydroxide crystals also increases, which also easily leads to the aggregation of particles to generate larger particles due to collision, and the dispersibility also decreases, finally obtaining larger nano-magnesium hydroxide crystal particles.

[0044] In some optional examples, the mass ratio of magnesium chloride hexahydrate to polyethylene glycol 2000 in the magnesium chloride solution is 10:(0.07-0.08), for example, it can be 10:0.07, 10:0.071, 10:0.072, 10:0.073, 10:0.074, 10:0.075, 10:0.076, 10:0.077, 10:0.078, 10:0.079 or 10:0.08, but not limited to the listed values, and other values not listed in the range are also applicable.

[0045] The present application particularly limits the mass ratio of magnesium chloride hexahydrate to polyethylene glycol 2000 in the magnesium chloride solution to 10:(0.07-0.08). With the increase of the amount of PEG 2000, the average particle size of the nano-magnesium hydroxide particles gradually decreases, and when the amount of PEG 2000 is within the range defined in the present application, the particle size of the generated nano-magnesium hydroxide tends to be stable. When the amount of PEG 2000 exceeds the upper limit of the range defined in the present application, further increasing the amount of PEG 2000 has no obvious effect on the average particle size of the nano-magnesium hydroxide. This is because PEG 2000 is an excellent dispersant that can coat the just-generated crystal nucleus when the amount is small, and as a surfactant, it can reduce the interfacial tension to reduce the viscosity of the liquid phase system in the reaction, and the resistance during stirring is also reduced. When the amount of PEG 2000 reaches the upper limit of the range defined in the present application, the surface of the nano-magnesium hydroxide is covered with a monolayer, at which time the viscosity of the liquid phase in the reaction system is at a minimum. At this time, if the amount of PEG 2000 is further increased, more physical adsorption layers will be formed on the surface of the nano-magnesium hydroxide, which has no positive effect on the dispersibility of the nano-magnesium hydroxide product, and even increases the viscosity and shear force of the nano-magnesium hydroxide in the system, resulting in poor dispersibility of the magnesium hydroxide and causing the small crystal nuclei to agglomerate. Therefore, when the amount of PEG 2000 exceeds the upper limit of the range defined in the present application, not only will the average particle size of the nano-magnesium hydroxide increase, but also the production cost will increase.

[0046] In some optional examples, the mass fraction of the ammonia solution is 20-30 wt%, for example, it can be 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt% or 30 wt%, but is not limited to the listed values, and other values not listed in this range are also applicable.

[0047] Compared with the sodium hydroxide solution used in the traditional chemical precipitation method, the present application preferably uses an ammonia solution with a mass fraction of 20-30 wt%. This is because when sodium hydroxide solution is used as a raw material for reaction, the generated nano-magnesium hydroxide product is prone to agglomeration and clumping, which is due to the fact that after sodium hydroxide is dissolved in water, OH - is completely ionized, which easily causes the local OH - concentration to be too high, thereby causing the Mg - part of the OH 2+ reacts rapidly with OH -The reaction produces a large number of nanometer magnesium hydroxide crystal nucleus adhesion, resulting in the final preparation of nanometer magnesium hydroxide crystal grain for sheet structure, sheet layer close packing, a large number of agglomeration. When using ammonia solution as raw material reaction, because ammonia is a weak base, in the reaction system ionization OH - The rate is slow, it is not easy to produce local OH - Concentration is too high, therefore, the reaction system Mg 2+ And OH - The rate of generating crystal nucleus is relatively slow, with the reaction, the growth rate of nanometer magnesium hydroxide crystal is greater than the nucleation rate, the final preparation of nanometer magnesium hydroxide is also by single sheet layer grain accumulation, but there is a large pore between the sheet layer, no obvious agglomeration phenomenon.

[0048] In some optional examples, the ammonia solution is heated to 60-70 before the magnesium chloride mother liquor is dropped into the ammonia solution, the obtained reaction liquid is continuously stirred and always kept at a constant temperature of 60-70 during the dropping process of the magnesium chloride mother liquor, for example, it can be 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃ or 70℃, but not limited to the listed values, other values not listed in the range are also applicable.

[0049] In some optional examples, the dropping speed of the magnesium chloride mother liquor is 3-5 mL / min, for example, it can be 3.0 mL / min, 3.2 mL / min, 3.4 mL / min, 3.6 mL / min, 3.8 mL / min, 4.0 mL / min, 4.2 mL / min, 4.4 mL / min, 4.6 mL / min, 4.8 mL / min or 5.0 mL / min, but not limited to the listed values, other values not listed in the range are also applicable.

[0050] In some optional examples, when the pH value of the obtained reaction liquid reaches 10-12 during the dropping process of the magnesium chloride mother liquor, the dropping of the magnesium chloride solution is stopped, and then the stirring is continued at a constant temperature of 60-70 for 1-3 h, wherein the pH value can be 10, 10.2, 10.4, 10.6, 10.8, 11, 11.2, 11.4, 11.6, 11.8 or 12, the temperature can be 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃ or 70℃, and the stirring time can be 1.0 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2.0 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h or 3.0 h, but not limited to the listed values, other values not listed in the range are also applicable.

[0051] The present application particularly limits the reaction temperature to 60-70℃. With the increase of the reaction temperature, the average particle size of the nano magnesium hydroxide first decreases and then increases. When the reaction temperature is lower than 60℃, the energy required for the growth of the nano magnesium hydroxide crystals cannot be provided, at this time, the supersaturation degree of the solution in the reaction system is insufficient, the nucleation rate of the nano magnesium hydroxide is less than the growth rate of the crystals, resulting in the generation of larger nano magnesium hydroxide crystals. When the reaction temperature is higher than 70℃, the Brownian motion of the nano magnesium hydroxide crystals is heated during the growth, the probability of collision between the crystals increases, the particle polarity increases, thereby the aggregation occurs, forming larger particles with poor dispersibility.

[0052] The present application particularly limits the reaction time to 1-3h. With the extension of the reaction time, the average particle size of the nano magnesium hydroxide first decreases and then increases. When the reaction time is within the range of 1-3h, the nucleation rate of the nano magnesium hydroxide is greater than the growth rate, at this time, the number of the generated nano magnesium hydroxide crystals is large and the particle size is small. With the extension of the reaction time, when the reaction time is more than 3h, the growth rate of the nano magnesium hydroxide crystals accelerates, which is greater than the nucleation rate, at this time, the growth rate gradually dominates in the process of the formation of the nano magnesium hydroxide crystals, making the small crystals grow again, resulting in the increase of the average particle size of the nano magnesium hydroxide.

[0053] In some optional examples, the centrifugal speed of the magnesium hydroxide suspension is 800-1000r / min, for example, it can be 800r / min, 820r / min, 840r / min, 860r / min, 880r / min, 900r / min, 920r / min, 940r / min, 960r / min, 980r / min or 1000r / min, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0054] In some optional examples, the centrifugal time of the magnesium hydroxide suspension is 30-40min, for example, it can be 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min or 40min, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0055] As a preferred technical solution of the present application, in step (II), the modified nano magnesium hydroxide is prepared by the following method:

[0056] The nano magnesium hydroxide is mixed with oleic acid and heated to react, and after the reaction is completed, washing and drying are performed to obtain the modified nano magnesium hydroxide.

[0057] In some alternative examples, the mass ratio of the modified nano-hydrogenated magnesium hydroxide to oleic acid is 1:(0.02-0.03), which can be 1:0.02, 1:0.021, 1:0.022, 1:0.023, 1:0.024, 1:0.025, 1:0.026, 1:0.027, 1:0.028, 1:0.029 or 1:0.03, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0058] The present application particularly limits the mass ratio of the modified nano-hydrogenated magnesium hydroxide to oleic acid to be 1:(0.02-0.03). As the amount of oleic acid increases, the activation index of the modified nano-hydrogenated magnesium hydroxide gradually increases and gradually stabilizes. When the amount of oleic acid is less than the lower limit of the range defined by the present application, the area of the nano-hydrogenated magnesium hydroxide surface coated with oleic acid is small. As the amount of oleic acid increases, the area of the nano-hydrogenated magnesium hydroxide surface coated with oleic acid increases, and the activation index rapidly increases. When the amount of oleic acid exceeds the upper limit of the range defined by the present application, the nano-hydrogenated magnesium hydroxide surface is almost completely coated, and the probability of adsorption of oleic acid on the nano-hydrogenated magnesium hydroxide surface decreases, resulting in a decrease in the change in the activation index of the modified nano-hydrogenated magnesium hydroxide.

[0059] In some alternative examples, the mixing and stirring time of the modified nano-hydrogenated magnesium hydroxide and oleic acid is 10-20 min, which can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0060] The present application particularly limits the mixing and stirring time of the modified nano-hydrogenated magnesium hydroxide and oleic acid to be 10-20 min. As the modification time increases, the activation index of the modified nano-hydrogenated magnesium hydroxide gradually increases and stabilizes. When the modification time is less than 10 min, the coating layer on the surface of the nano-hydrogenated magnesium hydroxide has not yet been completely formed. As the modification time increases, the coated area on the surface of the nano-hydrogenated magnesium hydroxide gradually increases. When the modification time reaches 20 min, the surface of the nano-hydrogenated magnesium hydroxide is completely covered with oleic acid molecules, forming a complete coating layer. At this time, the activation index of the modified nano-hydrogenated magnesium hydroxide is the largest. When the modification time continues to increase, the activation index of the modified nano-hydrogenated magnesium hydroxide remains almost unchanged.

[0061] In some optional examples, the stirring speed of the modified nanometer magnesium hydroxide and the oleic acid is 2400-2500 r / min, for example, it can be 2400 r / min, 2410 r / min, 2420 r / min, 2430 r / min, 2440 r / min, 2450 r / min, 2460 r / min, 2470 r / min, 2480 r / min, 2490 r / min or 2500 r / min, but not only limited to the listed values, other values not listed in the range are also applicable.

[0062] In some optional examples, the heating temperature of the modified nanometer magnesium hydroxide and the oleic acid is 150-160℃, for example, it can be 150℃, 151℃, 152℃, 153℃, 154℃, 155℃, 156℃, 157℃, 158℃, 159℃ or 160℃, but not only limited to the listed values, other values not listed in the range are also applicable.

[0063] The heating temperature of the modified nanometer magnesium hydroxide and the oleic acid is 150-160℃, and the activation index of the modified nanometer magnesium hydroxide increases with the increase of the modification temperature. When the modification temperature is lower than 150℃, it is difficult for the oleic acid to form an effective adsorption layer on the surface of the nanometer magnesium hydroxide, and the energy provided is not enough to meet the energy peak required for the reaction between the oleic acid and the surface of the nanometer magnesium hydroxide, resulting in poor modification effect on the nanometer magnesium hydroxide.

[0064] As a preferred technical solution of the present application, in step (III), the mass ratio of polycarbosilane to tetrahydrofuran is 1:(2-3), for example, it can be 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3.0, but not only limited to the listed values, other values not listed in the range are also applicable.

[0065] In some optional examples, the mass ratio of the modified boron nitride nanosheet, the modified nanometer magnesium hydroxide, the ethylene glycol and the polycarbosilane in the polycarbosilane solution is (30-40):(60-70):(1-10):10, for example, it can be 30:60:1:10, 31:61:2:10, 32:62:3:10, 33:63:4:10, 34:64:5:10, 35:65:6:10, 36:66:7:10, 37:67:8:10, 38:68:9:10, 39:69:10:10 or 40:70:10:10, but not only limited to the listed values, other values not listed in the range are also applicable.

[0066] In some optional examples, the mixing and stirring of the modified boron nitride nanosheets, the modified nanometer magnesium hydroxide and the polycarbosilane solution is performed at a rotation speed of 1000-2000 r / min, for example, 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min, 1500 r / min, 1600 r / min, 1700 r / min, 1800 r / min, 1900 r / min or 2000 r / min, but not limited to the listed values, and other values not listed in the range are also applicable.

[0067] In some optional examples, the mixing and stirring of the modified boron nitride nanosheets, the modified nanometer magnesium hydroxide and the polycarbosilane solution is performed for 3-5 min, for example, 3.0 min, 3.2 min, 3.4 min, 3.6 min, 3.8 min, 4.0 min, 4.2 min, 4.4 min, 4.6 min, 4.8 min or 5.0 min, but not limited to the listed values, and other values not listed in the range are also applicable.

[0068] In a second aspect, the present application provides an inorganic anti-corrosion anti-freezing flame retardant prepared by the preparation method of the first aspect, wherein the inorganic anti-corrosion anti-freezing flame retardant has a pH value of 7-8, for example, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9 or 8.0, but not limited to the listed values, and other values not listed in the range are also applicable.

[0069] Compared with the prior art, the present application has the following advantages:

[0070] The inorganic anti-corrosion anti-freezing flame retardant provided by the present application uses modified nanometer magnesium hydroxide as the main flame retardant, and is compounded with modified boron nitride nanosheets, polycarbosilane and a small amount of ethylene glycol, which produces a synergistic effect with magnesium hydroxide and improves the flame retardant performance, anti-corrosion performance and anti-freezing performance of the composite material. The addition of modified boron nitride nanosheets significantly inhibits the heat release behavior and smoke release behavior of the composite material, greatly reduces the peak heat release rate, total heat release, smoke release rate and total smoke release amount of the composite material, and increases the amount of residual carbon. In addition, the boron nitride nanosheets are fully dispersed in the coating and can play a physical barrier role against corrosive media, form a "labyrinth" effect in the coating, and enhance the anti-corrosion performance of the coating, so that the corrosive media (such as H2O, O2, Cl -The diffusion channel to the substrate surface is more tortuous, thereby improving the barrier and corrosion resistance of the coating. The addition of polycarbosilane promotes the thermal degradation of the composite into carbon, which is beneficial to reduce the thermal weight loss rate of the composite and improve the stability of the carbon layer, effectively inhibits the degradation of the main chain, and significantly reduces the release of heat and smoke in combustion. Ethylene glycol as an antifreeze agent can impart the inorganic corrosion-resistant and antifreeze flame retardant with certain antifreeze performance.

[0071] The inorganic corrosion-resistant and antifreeze flame retardant provided by the present application can be added to wood paint, industrial paint and wall paint. When it is added to wood paint, the flame retardant performance of the wood paint can be significantly improved, the limiting oxygen index is more than 30%, and it can be widely used in furniture wood products, wood structure houses, ancient wood buildings and ancient building group protection buildings. When it is added to industrial paint, the corrosion resistance of the industrial paint can be significantly improved, and the formed paint film is hard, has high gloss and strong adhesion, and can be widely used in steel structures, pipelines, storage tanks, tank cars and equipment surfaces in the chemical, mechanical, shipbuilding, metallurgical and other industries. When it is added to wall paint, the antifreeze performance of the wall paint can be significantly improved, and it can withstand long-term freezing at-15 DEG C or below without changing its properties, effectively preventing the occurrence of phenomena such as cracking and peeling of the wall paint due to freezing. BRIEF DESCRIPTION OF DRAWINGS

[0072] Figure 1 The preparation process flow chart of the inorganic corrosion-resistant and antifreeze flame retardant provided by the present application is shown in the following embodiment 1-5. DETAILED DESCRIPTION

[0073] The technical solutions of the present application will be described in detail below in combination with specific embodiments and their accompanying drawings. The embodiments described herein are specific specific embodiments of the present application, which are used to illustrate the concept of the present application; these descriptions are all explanatory and exemplary, and should not be understood as limiting the embodiments of the present application and the protection scope of the present application. The polycarbosilane used in the specific embodiments of the present application: CAS No. 62306-27-8, Mw = 1400, Polycarbomethylsilane (polycarbomethylsilane), Henan Weitixi Chemical Technology Co., Ltd.

[0074] Embodiment 1

[0075] The present embodiment provides a preparation method of an inorganic corrosion-resistant and antifreeze flame retardant, as shown in Figure 1 The preparation method specifically comprises the following steps:

[0076] (1) The hexagonal boron nitride was calcined at 800℃ for 2h to obtain a calcined product. The calcined product, 2-amino-5-mercapto-1, 3, 4-thiadiazole and deionized water were dispersed in deionized water, the mixing ratio of the calcined product, 2-amino-5-mercapto-1, 3, 4-thiadiazole and deionized water was 1g:1.3g:200mL, and ultrasonic exfoliation was carried out under a ultrasonic power of 500W for 5h to obtain a boron nitride suspension; the boron nitride suspension was centrifuged at a speed of 2000r / min for 40min, and the supernatant was filtered and dried to obtain boron nitride nanosheets;

[0077] The boron nitride nanosheets were added into a Tris-HCl buffer solution with a pH value of 7, the ratio of the boron nitride nanosheets to the Tris-HCl buffer solution was 0.3g:100mL, and ultrasonic dispersion was carried out under a ultrasonic power of 200W for 60min to obtain a modified boron nitride suspension; dopamine was added into the modified boron nitride suspension, the mass ratio of the boron nitride nanosheets to the dopamine was 1.8:1, and mixing and stirring were carried out under a constant temperature condition of 20℃ for 8h to react, and the modified boron nitride nanosheets were obtained after filtration, washing and drying;

[0078] (2) The magnesium chloride hexahydrate was dissolved in an ethanol aqueous solution to obtain a magnesium chloride solution with a concentration of 0.3g / mL, the volume ratio of ethanol to water in the ethanol aqueous solution was 1:1.5, the polyethylene glycol 2000 was added into the magnesium chloride solution, the mass ratio of the magnesium chloride hexahydrate to the polyethylene glycol 2000 was 10:0.07, and the magnesium chloride mother liquor was obtained after mixing uniformly;

[0079] The 20wt% ammonia solution was heated to 60℃, the magnesium chloride mother liquor was added into the ammonia solution at a dropping speed of 3mL / min under stirring to react, the obtained reaction liquid was continuously stirred and kept at a constant temperature of 60℃ during the dropping of the magnesium chloride mother liquor, when the pH value of the obtained reaction liquid reached 10, the dropping of the magnesium chloride solution was stopped, and then the stirring was continuously carried out under a constant temperature condition of 60℃ for 3h; the magnesium hydroxide suspension was obtained after the reaction, and the nanometer magnesium hydroxide was obtained after centrifugation, washing and drying of the magnesium hydroxide suspension, the centrifugation speed was 800r / min, and the centrifugation time was 40min;

[0080] The nanometer magnesium hydroxide and the oleic acid were mixed at a mass ratio of 1:0.02, and the mixing was carried out under a constant temperature condition of 150℃ at a stirring speed of 2400r / min for 20min to react, and the modified nanometer magnesium hydroxide was obtained after washing and drying;

[0081] (3) poly-carbosilane is dissolved in tetrahydrofuran, the mass ratio of poly-carbosilane to tetrahydrofuran is 1:2, after being uniformly mixed, a poly-carbosilane solution is obtained; the modified boron nitride nanosheet obtained in step (1), the modified nano-magnesium hydroxide obtained in step (2) and ethylene glycol are added into the poly-carbosilane solution, the mass ratio of the modified boron nitride nanosheet, the modified nano-magnesium hydroxide, the ethylene glycol and the poly-carbosilane in the poly-carbosilane solution is 30:70:1:10, and the mixture is stirred at a rotating speed of 1000 r / min for 5 min to obtain the inorganic anti-corrosion anti-freezing flame retardant.

[0082] Example 2

[0083] The embodiment provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, as shown in the following scheme: Figure 1 The preparation method specifically comprises the following steps:

[0084] (1) hexagonal boron nitride is calcined at 820℃ for 1.8h to obtain a calcined product, the calcined product, 2-amino-5-mercapto-1,3,4-thiadiazole and deionized water are dispersed in deionized water, the mixing ratio of the calcined product, 2-amino-5-mercapto-1,3,4-thiadiazole and deionized water is 1g:1.35g:220mL, and ultrasonic peeling is performed under an ultrasonic power of 520W for 4.8h to obtain a boron nitride suspension; the boron nitride suspension is centrifuged at a rotating speed of 2200 r / min for 38 min, the supernatant is filtered and dried to obtain boron nitride nanosheets;

[0085] The boron nitride nanosheets are added into a Tris-HCl buffer solution with a pH value of 7.2, the ratio of the boron nitride nanosheets to the Tris-HCl buffer solution is 0.35g:100mL, ultrasonic dispersion is performed under an ultrasonic power of 220W for 58 min to obtain a modified boron nitride suspension; dopamine is added into the modified boron nitride suspension, the mass ratio of the boron nitride nanosheets to the dopamine is 1.85:1, and the mixture is stirred under a constant temperature condition of 22℃ for 7h to react, and the modified boron nitride nanosheets are obtained after filtration, washing and drying;

[0086] (2) magnesium chloride hexahydrate is dissolved in an ethanol aqueous solution to obtain a magnesium chloride solution with a concentration of 0.32g / mL, the volume ratio of ethanol to water in the ethanol aqueous solution is 1:1.6, polyethylene glycol 2000 is added into the magnesium chloride solution, the mass ratio of the magnesium chloride hexahydrate to the polyethylene glycol 2000 is 10:0.072, and the mixture is uniformly mixed to obtain a magnesium chloride mother liquor;

[0087] The 22wt% ammonia solution was heated to 62℃, and the magnesium chloride mother liquor was added dropwise into the ammonia solution at a dropwise adding speed of 3.5mL / min under stirring to cause a precipitation reaction, the obtained reaction liquid was continuously stirred during the dropwise adding of the magnesium chloride mother liquor and was kept at a constant temperature of 62℃, when the pH value of the obtained reaction liquid reached 10.5, the dropwise adding of the magnesium chloride solution was stopped, and then the stirring was continuously carried out at a constant temperature of 62℃ for 2.5h; after the reaction was completed, a magnesium hydroxide suspension was obtained, and after centrifugation, washing and drying of the magnesium hydroxide suspension, nano magnesium hydroxide was obtained, the centrifugal speed was 850r / min, and the centrifugal time was 38min;

[0088] The nano magnesium hydroxide was mixed with oleic acid at a mass ratio of 1:0.022, and the mixture was stirred at a constant temperature of 152℃ and a speed of 2420r / min for 18min to cause a reaction, and after the reaction was completed, the mixture was washed and dried to obtain modified nano magnesium hydroxide;

[0089] (3) Polycarbosilane was dissolved in tetrahydrofuran, and the mass ratio of polycarbosilane to tetrahydrofuran was 1:2.2. After uniform mixing, a polycarbosilane solution was obtained. The modified boron nitride nanosheet obtained in step (1), the modified nano magnesium hydroxide obtained in step (2), and ethylene glycol were added to the polycarbosilane solution. The mass ratio of the modified boron nitride nanosheet, the modified nano magnesium hydroxide, the ethylene glycol, and the polycarbosilane in the polycarbosilane solution was 32:68:3:10. The mixture was stirred at a speed of 1200r / min for 4.5min to obtain the inorganic anti-corrosion, anti-freezing and flame-retardant agent.

[0090] Example 3

[0091] The present embodiment provides a preparation method of an inorganic anti-corrosion, anti-freezing and flame-retardant agent, as shown in Figure 1 The preparation method specifically comprises the following steps:

[0092] (1) Hexagonal boron nitride was calcined at 850℃ for 1.5h to obtain a calcined product. The calcined product and 2-amino-5-mercapto-1,3,4-thiadiazole were dispersed in deionized water, and the mixing ratio of the calcined product, 2-amino-5-mercapto-1,3,4-thiadiazole and deionized water was 1g:1.4g:250mL. Ultrasonic peeling was carried out under an ultrasonic power of 550W for 4.5h to obtain a boron nitride suspension. The boron nitride suspension was centrifuged at a speed of 2500r / min for 35min, and the supernatant was filtered and dried to obtain boron nitride nanosheets;

[0093] The boron nitride nanosheets are added into a Tris-HCl buffer solution with a pH value of 7.5, the ratio of the boron nitride nanosheets to the Tris-HCl buffer solution is 0.4 g:100 mL, ultrasonic dispersion is carried out at an ultrasonic power of 250 W for 55 min to obtain a modified boron nitride suspension; dopamine is added into the modified boron nitride suspension, the mass ratio of the boron nitride nanosheets to the dopamine is 1.9:1, mixing and stirring are carried out at a constant temperature of 25 ℃ for 7 h to cause a reaction, and after the reaction is completed, the modified boron nitride nanosheets are obtained through filtration, washing and drying.

[0094] (2) Magnesium chloride hexahydrate is dissolved in an ethanol aqueous solution to obtain a magnesium chloride solution with a concentration of 0.35 g / mL, the volume ratio of ethanol to water in the ethanol aqueous solution is 1:1.7, polyethylene glycol 2000 is added into the magnesium chloride solution, the mass ratio of the magnesium chloride hexahydrate to the polyethylene glycol 2000 is 10:0.075, and the magnesium chloride mother liquor is obtained after uniform mixing.

[0095] The ammonia water solution with a concentration of 25 wt% is heated to 65 ℃, the magnesium chloride mother liquor is added into the ammonia water solution at a dropping speed of 4 mL / min under stirring to cause a precipitation reaction, the obtained reaction liquid is continuously stirred and kept at a constant temperature of 65 ℃ during the dropping of the magnesium chloride mother liquor, the dropping of the magnesium chloride solution is stopped when the pH value of the obtained reaction liquid reaches 11, and then the stirring is continuously carried out at a constant temperature of 65 ℃ for 2 h; the magnesium hydroxide suspension is obtained after the reaction is completed, and the nanometer magnesium hydroxide is obtained after centrifugation, washing and drying of the magnesium hydroxide suspension, the centrifugation speed is 900 r / min, and the centrifugation time is 35 min.

[0096] The nanometer magnesium hydroxide and the oleic acid are mixed at a mass ratio of 1:0.025, the stirring is carried out at a speed of 2450 r / min at a constant temperature of 155 ℃ for 15 min to cause a reaction, and the modified nanometer magnesium hydroxide is obtained after washing and drying.

[0097] (3) Polycarbosilane is dissolved in tetrahydrofuran, the mass ratio of the polycarbosilane to the tetrahydrofuran is 1:2.5, and the polycarbosilane solution is obtained after uniform mixing; the modified boron nitride nanosheets obtained in step (1), the modified nanometer magnesium hydroxide obtained in step (2) and ethylene glycol are added into the polycarbosilane solution, the mass ratio of the modified boron nitride nanosheets, the modified nanometer magnesium hydroxide, the ethylene glycol and the polycarbosilane in the polycarbosilane solution is 35:65:5:10, and the mixing and stirring are carried out at a speed of 1500 r / min for 4 min to obtain the inorganic anticorrosion antifreeze flame retardant.

[0098] Example 4

[0099] The embodiment provides a preparation method of an inorganic anticorrosion antifreeze flame retardant, as shown in Figure 1As shown, the preparation method specifically comprises the following steps:

[0100] (1) Hexagonal boron nitride is calcined at 880℃ for 1.2h to obtain a calcined product, the calcined product and 2-amino-5-mercapto-1, 3, 4-thiadiazole are dispersed in deionized water, the mixing ratio of the calcined product, 2-amino-5-mercapto-1, 3, 4-thiadiazole and deionized water is 1g: 1.45g: 280mL, and ultrasonic peeling is carried out at an ultrasonic power of 580W for 4.2h to obtain a boron nitride suspension; the boron nitride suspension is centrifuged at a speed of 2800r / min for 32min, and the supernatant is taken to perform suction filtration and then drying to obtain boron nitride nanosheets;

[0101] The boron nitride nanosheets are added into a Tris-HCl buffer solution with a pH value of 7.8, the ratio of the boron nitride nanosheets to the Tris-HCl buffer solution is 0.45g: 100mL, ultrasonic dispersion is carried out at an ultrasonic power of 280W for 52min to obtain a modified boron nitride suspension; dopamine is added into the modified boron nitride suspension, the mass ratio of the boron nitride nanosheets to the dopamine is 1.85: 1, and mixing and stirring are carried out at a constant temperature of 28℃ for 6h to react, and after the reaction is completed, the modified boron nitride nanosheets are obtained after filtration, washing and drying;

[0102] (2) Magnesium chloride hexahydrate is dissolved in an ethanol aqueous solution to obtain a magnesium chloride solution with a concentration of 0.38g / mL, the volume ratio of ethanol to water in the ethanol aqueous solution is 1: 1.8, polyethylene glycol 2000 is added into the magnesium chloride solution, the mass ratio of magnesium chloride hexahydrate to polyethylene glycol 2000 is 10: 0.078, and the mixture is uniformly mixed to obtain a magnesium chloride mother liquor;

[0103] The 28wt% ammonia solution is heated to 68℃, under stirring, the magnesium chloride mother liquor is added into the ammonia solution at a dropping speed of 4.5mL / min to react, the obtained reaction liquid is continuously stirred and kept at a constant temperature of 68℃ during the dropping of the magnesium chloride mother liquor, when the pH value of the obtained reaction liquid reaches 11.5, the dropping of the magnesium chloride solution is stopped, and then the stirring is continuously carried out at a constant temperature of 68℃ for 1.5h; after the reaction is completed, a magnesium hydroxide suspension is obtained, and after centrifugation, washing and drying, the magnesium hydroxide suspension is obtained, the centrifugation speed is 950r / min, and the centrifugation time is 32min;

[0104] The nanometer magnesium hydroxide and oleic acid are mixed at a mass ratio of 1: 0.028, stirring is carried out at a speed of 2480r / min at a constant temperature of 158℃ for 12min to react, and after the reaction is completed, the modified nanometer magnesium hydroxide is obtained after washing and drying;

[0105] (3) poly-carbosilane is dissolved in tetrahydrofuran, the mass ratio of poly-carbosilane to tetrahydrofuran is 1:2.8, after being uniformly mixed, a poly-carbosilane solution is obtained; the modified boron nitride nanosheet obtained in step (1), the modified nano-magnesium hydroxide obtained in step (2) and ethylene glycol are added into the poly-carbosilane solution, the mass ratio of the modified boron nitride nanosheet, the modified nano-magnesium hydroxide, ethylene glycol and poly-carbosilane in the poly-carbosilane solution is 38:62:7:10, and the mixture is stirred at a rotating speed of 1800 r / min for 3.5 min to obtain the inorganic anti-corrosion anti-freezing flame retardant.

[0106] Example 5

[0107] The embodiment provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, as shown in the following scheme: Figure 1 The preparation method specifically comprises the following steps:

[0108] (1) hexagonal boron nitride is calcined at 900℃ for 1h to obtain a calcined product, the calcined product, 2-amino-5-mercapto-1,3,4-thiadiazole and deionized water are dispersed in deionized water, the mixing ratio of the calcined product, 2-amino-5-mercapto-1,3,4-thiadiazole and deionized water is 1g:1.5g:300mL, and ultrasonic peeling is performed under an ultrasonic power of 600W for 4h to obtain a boron nitride suspension; the boron nitride suspension is centrifuged at a rotating speed of 3000 r / min for 30 min, the supernatant is filtered and dried to obtain boron nitride nanosheets;

[0109] The boron nitride nanosheets are added into a Tris-HCl buffer solution with a pH value of 8, the ratio of the boron nitride nanosheets to the Tris-HCl buffer solution is 0.5g:100mL, ultrasonic dispersion is performed under an ultrasonic power of 300W for 50 min to obtain a modified boron nitride suspension; dopamine is added into the modified boron nitride suspension, the mass ratio of the boron nitride nanosheets to the dopamine is 2:1, and the mixture is stirred under a constant temperature condition of 30℃ for 5h to react, and the modified boron nitride nanosheets are obtained after filtration, washing and drying;

[0110] (2) magnesium chloride hexahydrate is dissolved in an ethanol aqueous solution to obtain a magnesium chloride solution with a concentration of 0.4g / mL, the volume ratio of ethanol to water in the ethanol aqueous solution is 1:2, polyethylene glycol 2000 is added into the magnesium chloride solution, the mass ratio of magnesium chloride hexahydrate to polyethylene glycol 2000 is 10:0.08, and the mixture is uniformly mixed to obtain a magnesium chloride mother liquor;

[0111] The 30wt% ammonia solution was heated to 70°C, and the magnesium chloride mother liquor was added dropwise into the ammonia solution at a dropping speed of 5mL / min under stirring to cause a precipitation reaction, the obtained reaction liquid was continuously stirred and kept at a constant temperature of 70°C during the dropping of the magnesium chloride mother liquor, when the pH value of the obtained reaction liquid reached 12, the dropping of the magnesium chloride solution was stopped, and then the stirring was continued at a constant temperature of 70°C for 1h; after the reaction was completed, a magnesium hydroxide suspension was obtained, and after centrifugation, washing and drying, nano magnesium hydroxide was obtained, the centrifugal speed was 1000r / min, and the centrifugal time was 30min;

[0112] The nano magnesium hydroxide and the oleic acid were mixed at a mass ratio of 1:0.03, and the mixture was stirred at a speed of 2500r / min at a constant temperature of 160°C for 10min to cause a reaction, and after the reaction was completed, the mixture was washed and dried to obtain modified nano magnesium hydroxide;

[0113] (3) The polycarbosilane was dissolved in tetrahydrofuran, and the mass ratio of the polycarbosilane to the tetrahydrofuran was 1:3, and after uniform mixing, a polycarbosilane solution was obtained; the modified boron nitride nanosheet obtained in step (1), the modified nano magnesium hydroxide obtained in step (2) and ethylene glycol were added into the polycarbosilane solution, and the mass ratio of the modified boron nitride nanosheet, the modified nano magnesium hydroxide, the ethylene glycol and the polycarbosilane in the polycarbosilane solution was 40:60:10:10, and the mixture was stirred at a speed of 2000r / min for 3min to obtain the inorganic anti-corrosion anti-freezing flame retardant.

[0114] Comparative Example 1

[0115] This comparative example provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, which is different from Example 1 in that in step (2), the concentration of the magnesium chloride solution is adjusted to 0.2g / mL, and other process parameters and operation steps are completely the same as those of Example 1.

[0116] Comparative Example 2

[0117] This comparative example provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, which is different from Example 1 in that in step (2), the concentration of the magnesium chloride solution is adjusted to 0.5g / mL, and other process parameters and operation steps are completely the same as those of Example 1.

[0118] Comparative Example 3

[0119] This comparative example provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, which is different from Example 1 in that in step (2), the mass ratio of the magnesium chloride solution to the polyethylene glycol 2000 is adjusted to 10:0.05, and other process parameters and operation steps are completely the same as those of Example 1.

[0120] Comparative Example 4

[0121] The present comparative example provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, which is different from example 1 in that in step (2), the mass ratio of magnesium chloride hexahydrate in the magnesium chloride solution to polyethylene glycol 2000 is adjusted to 10:0.1, and other process parameters and operation steps are completely same as example 1.

[0122] Comparative Example 5

[0123] The present comparative example provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, which is different from example 1 in that in step (2), the mass ratio of modified nano-magnesium hydroxide to oleic acid is adjusted to 1:0.01, and other process parameters and operation steps are completely same as example 1.

[0124] Comparative Example 6

[0125] The present comparative example provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, which is different from example 1 in that in step (2), the mass ratio of modified nano-magnesium hydroxide to oleic acid is adjusted to 1:0.04, and other process parameters and operation steps are completely same as example 1.

[0126] Comparative Example 7

[0127] The present comparative example provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, which is different from example 1 in that in step (1), 2-amino-5-mercapto-1,3,4-thiadiazole is not added, and the calcined product is directly dispersed in deionized water for ultrasonic exfoliation, and other process parameters and operation steps are completely same as example 1.

[0128] Comparative Example 8

[0129] The present comparative example provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, which is different from example 1 in that step (1) is omitted, and modified boron nitride nanosheet is not added in the inorganic anti-corrosion anti-freezing flame retardant, and other process parameters and operation steps are completely same as example 1.

[0130] Comparative Example 9

[0131] The present comparative example provides a preparation method of an inorganic anti-corrosion anti-freezing flame retardant, which is different from example 1 in that steps (2) and (3) are omitted, and modified nano-magnesium hydroxide is not added in the inorganic anti-corrosion anti-freezing flame retardant, and other process parameters and operation steps are completely same as example 1.

[0132] Application Example 1

[0133] The inorganic corrosion-resistant antifreezing flame retardant obtained from the application examples 1-5 and the comparative examples 1-9 is used in the wood paint, which can effectively improve the flame retardant performance of the coating, and the formula of the wood paint is as follows:

[0134] The water-based acrylic resin is 60wt%, the film-forming aid is 3wt% of dipropylene glycol methyl ether, the defoaming agent is 1wt% of BYK019, the leveling agent is 1wt% of BYK306, the inorganic corrosion-resistant antifreezing flame retardant is 10wt% of the inorganic corrosion-resistant antifreezing flame retardant prepared in the application examples 1-5 and the comparative examples 1-9, and the balance is deionized water.

[0135] The iron mountain wood standard template for experiment is polished flat, and the wood paint prepared in the application examples is uniformly coated on the surface of the iron mountain wood, and the film thickness is 0.5mm. The prepared standard sample is placed in a drying oven and dried at 25℃ for 7 days to obtain a standard sample for experiment.

[0136] The standard sample is subjected to limiting oxygen index test and cone calorimeter test, and the specific test steps are as follows:

[0137] (1) Limiting oxygen index test

[0138] The limiting oxygen index of the sample is determined by a JF-3 type oxygen index tester according to the test standard GB / T1406-93, and the test sample is 80mm. The oxygen index is an experimental method for determining the minimum oxygen concentration required to maintain the combustion of the sample in a mixture of oxygen and nitrogen gas. It is an important means of evaluation and classification of flammability, and also an important indicator of flammability.

[0139] (2) Cone calorimeter test

[0140] Cone calorimeter method is an important method for evaluating the combustion performance of materials. The working principle of the cone calorimeter is the oxygen consumption principle, which is that when the material burns, 1g of oxygen is consumed, and a certain amount of heat is generated. When the standard sample is subjected to the cone calorimeter experiment, the combustion conditions of the material are very close to the combustion conditions of the material in a fire. The combustion of the material in the cone calorimeter experiment can reflect the combustion of the material in the fire. The cone calorimeter experiment can measure many data of the material during combustion, such as heat release rate and total heat release. When analyzing the combustion performance of the material, the heat release rate and total heat release of the material are analyzed comprehensively, which can better judge the combustion performance of the material.

[0141] Heat release rate: refers to the heat release rate per square meter of material during combustion in the cone calorimeter experiment, unit: KW / m 2 .

[0142] Total heat release: refers to the total heat release of the material from the beginning of combustion to the complete end of the material combustion when the material is subjected to a cone calorimetric experiment, and the unit is MJ / m 2 .

[0143] The data of limiting oxygen index, maximum heat release rate and total heat release obtained by testing are shown in Table 1.

[0144] Table 1: limiting oxygen index, maximum heat release rate and total heat release

[0145]

[0146]

[0147] It can be seen from the test data provided in Table 1 that the inorganic anti-corrosion and anti-freezing flame retardant prepared by Examples 1-5 has excellent flame retardant performance.

[0148] It can be seen from the test data of Example 1, Comparative Example 1 and Comparative Example 2 that the concentration of magnesium chloride hexahydrate is too high or too low, which will affect the flame retardant performance of the inorganic anti-corrosion and anti-freezing flame retardant prepared.

[0149] It can be seen from the test data of Example 1, Comparative Example 3 and Comparative Example 4 that the mass ratio of magnesium chloride hexahydrate to polyethylene glycol 2000 is too high or too low, which will affect the flame retardant performance of the inorganic anti-corrosion and anti-freezing flame retardant prepared.

[0150] It can be seen from the test data of Example 1, Comparative Example 5 and Comparative Example 6 that the mass ratio of modified nano-magnesium hydroxide to oleic acid is too high or too low, which will affect the flame retardant performance of the inorganic anti-corrosion and anti-freezing flame retardant prepared.

[0151] It can be seen from the test data of Example 1 and Comparative Example 7 that by adding 2-amino-5-mercapto-1,3,4-thiadiazole for intercalation modification in the process of liquid phase ultrasonic assisted exfoliation of hexagonal boron nitride, the flame retardant performance of the inorganic anti-corrosion and anti-freezing flame retardant can be effectively improved.

[0152] It can be seen from the test data of Example 1, Comparative Example 8 and Comparative Example 9 that when the modified boron nitride nanosheet and the modified nano-magnesium hydroxide are added at the same time, the flame retardant performance of the inorganic anti-corrosion and anti-freezing flame retardant can be significantly improved.

[0153] Application Example 2

[0154] The inorganic anti-corrosion and anti-freezing flame retardant obtained by Examples 1-5 and Comparative Examples 1-9 of the present application can be used in industrial paint to effectively improve the corrosion resistance of the coating. The formula of the industrial paint is as follows:

[0155] Acrylic resin 70 wt%, anti-rust pigment 10 wt%, BYK162 wetting dispersant 1 wt%, BYK019 defoaming agent 0.3 wt%, BYK306 leveling agent 0.5 wt%, and 3 wt% of the inorganic anticorrosion antifreeze flame retardant obtained in Examples 1-5 and Comparative Examples 1-9, and the balance is deionized water.

[0156] The stainless steel plate for experiment was polished flat, and the industrial paint prepared in the application example was uniformly coated on the surface of the stainless steel plate, the coating film thickness was 20, and the prepared standard sample was placed in a drying oven and dried at 25℃ for 7 days to obtain a standard sample for experiment.

[0157] The acid resistance test and salt spray test method are used to evaluate the corrosion resistance of the coating. The acid resistance test method is as follows: the carbon steel block coated with the coating is wrapped with adhesive tape around the cutting part and the back surface without coating, and then placed in a sulfuric acid solution with different concentrations to test the acid resistance of the coating.

[0158] Table 2 is the acid immersion result of the coating. After immersion for 240 hours at room temperature under three different concentrations of 5%, 10% and 15%, the surface coating film is still complete. After immersion at 50℃ and 90℃ for 48 hours, the coating film is still complete. The corrosion resistant coating prepared in this experiment meets the general requirements of corrosion resistant paint in corrosion resistance, and has excellent acid resistance.

[0159] Table 2 Corrosion resistance

[0160]

[0161] The applicant declares that the above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing an inorganic anticorrosive antifreezing flame retardant, characterized by, The preparation method comprises: (I) calcining hexagonal boron nitride to obtain a calcined product, dispersing the calcined product and 2-amino-5-mercapto-1,3,4-thiadiazole in deionized water and performing ultrasonic exfoliation to obtain a boron nitride suspension; centrifuging the boron nitride suspension, taking the supernatant, performing suction filtration and drying to obtain boron nitride nanosheets; and modifying the boron nitride nanosheets with dopamine to obtain modified boron nitride nanosheets; (II) dissolving magnesium chloride hexahydrate in an ethanol aqueous solution to obtain a magnesium chloride solution, the concentration of the magnesium chloride hexahydrate in the magnesium chloride solution being 0.3-0.4 g / mL; adding polyethylene glycol 2000 to the magnesium chloride solution, uniformly mixing and obtaining a magnesium chloride mother liquor, the mass ratio of the magnesium chloride hexahydrate to the polyethylene glycol 2000 in the magnesium chloride solution being 10:(0.07-0.08); under stirring and heating, dropping the magnesium chloride mother liquor into an aqueous ammonia solution to perform a precipitation reaction, obtaining a magnesium hydroxide suspension after the reaction, and performing centrifugation, washing and drying on the magnesium hydroxide suspension to obtain nanometer magnesium hydroxide; and modifying the nanometer magnesium hydroxide with oleic acid to obtain modified nanometer magnesium hydroxide; The modified nanometer magnesium hydroxide is prepared by the following method: mixing and stirring the nanometer magnesium hydroxide and oleic acid and heating to perform a reaction, the mass ratio of the nanometer magnesium hydroxide to the oleic acid being 1:(0.02-0.03), washing and drying after the reaction to obtain modified nanometer magnesium hydroxide; (III) dissolving polycarbosilane in tetrahydrofuran to obtain a polycarbosilane solution; adding the modified boron nitride nanosheets obtained in step (I), the modified nanometer magnesium hydroxide obtained in step (II) and ethylene glycol to the polycarbosilane solution, mixing and stirring to obtain the inorganic corrosion-resistant, anti-freezing and flame-retardant agent.

2. The production method according to claim 1, characterized by, In step (I), the calcination temperature of the hexagonal boron nitride is 800-900°C; The calcination time of the hexagonal boron nitride is 1-2 h; The mixing ratio of the calcined product, 2-amino-5-mercapto-1,3,4-thiadiazole and deionized water is 1 g:(1.3-1.5) g:(200-300) mL; The ultrasonic power for the ultrasonic exfoliation is 500-600 W; The ultrasonic exfoliation time is 4-5 h; The centrifugation speed of the boron nitride suspension is 2000-3000 r / min; The centrifugation time of the boron nitride suspension is 30-40 min.

3. The preparation method according to claim 1, characterized in that, In step (I), the modified boron nitride nanosheets are prepared by the following method: adding the boron nitride nanosheets to a Tris-HCl buffer solution, ultrasonic dispersion to obtain a modified boron nitride suspension, adding dopamine to the modified boron nitride suspension, mixing and stirring to perform a reaction, and filtering, washing and drying after the reaction to obtain modified boron nitride nanosheets.

4. The production method according to claim 3, characterized by, The pH value of the Tris-HCl buffer solution is 7-8; The ratio of the boron nitride nanosheets to the Tris-HCl buffer solution is (0.3-0.5) g:100 mL; The ultrasonic dispersion power of the boron nitride nanosheets and the Tris-HCl buffer solution is 200-300 W; The ultrasonic dispersion time of the boron nitride nanosheets and the Tris-HCl buffer solution is 50-60 min.

5. The preparation method according to claim 3, characterized in that, The mass ratio of the boron nitride nanosheets in the modified boron nitride suspension to the dopamine is (1.8-2):1; The mixing and stirring time of the modified boron nitride suspension and the dopamine is 5-8 h; The mixing and stirring temperature of the modified boron nitride suspension and the dopamine is 20-30℃.

6. The method of claim 1, wherein, In step (II), the volume ratio of ethanol to water in the aqueous ethanol solution is 1:(1.5-2); The mass fraction of the aqueous ammonia solution is 20-30 wt%; Before the magnesium chloride mother liquor is dropped into the aqueous ammonia solution, the aqueous ammonia solution is heated to 60-70℃, and the obtained reaction liquid is continuously stirred and kept at a constant temperature of 60-70℃ during the dropping process of the magnesium chloride mother liquor; The dropping speed of the magnesium chloride mother liquor is 3-5 mL / min; During the dropping process of the magnesium chloride mother liquor, when the pH value of the obtained reaction liquid reaches 10-12, the dropping of the magnesium chloride solution is stopped, and then the stirring is continued at a constant temperature of 60-70℃ for 1-3 h; The centrifugal speed of the magnesium hydroxide suspension is 800-1000 r / min; The centrifugal time of the magnesium hydroxide suspension is 30-40 min.

7. The preparation method according to claim 1, characterized in that, In step (II), the mixing and stirring time of the nano-magnesium hydroxide and the oleic acid is 10-20 min; The mixing and stirring speed of the nano-magnesium hydroxide and the oleic acid is 2400-2500 r / min; The heating temperature during the mixing and stirring of the nano-magnesium hydroxide and the oleic acid is 150-160℃.

8. The method of claim 1, wherein, In step (III), the mass ratio of the polycarbosilane to the tetrahydrofuran is 1:(2-3); The mass ratio of the modified boron nitride nanosheets, the modified nano-magnesium hydroxide, the ethylene glycol, and the polycarbosilane in the polycarbosilane solution is (30-40):(60-70):(1-10):10; The mixing and stirring speed of the modified boron nitride nanosheets, the modified nano-magnesium hydroxide, and the polycarbosilane solution is 1000-2000 r / min; The mixing and stirring time of the modified boron nitride nanosheets, the modified nano-magnesium hydroxide, and the polycarbosilane solution is 3-5 min.

9. An inorganic anticorrosion, antifreezing, and flame-retardant agent prepared by the preparation method of any one of claims 1-8.

10. The inorganic anticorrosion, antifreeze, and flame retardant according to claim 9, characterized by, The pH value of the inorganic anticorrosion, antifreezing, and flame-retardant agent is 7-8.

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