Outdoor intumescent steel structure fireproof coating and preparation method thereof

Abstract

The application provides an outdoor intumescent steel structure fireproof coating and a preparation method thereof, and relates to the field of fireproof coatings.The fireproof coating comprises a matrix and a curing agent, and the matrix raw materials are bisphenol A type epoxy resin, low-viscosity aromatic epoxy resin, aerogel, ammonium polyphosphate, ammonium pentaborate, pretreated expanded graphite, composite filler, polyamide wax, dispersant and reactive diluent; and the curing agent raw materials are polyamide resin, low-viscosity aromatic epoxy resin, reactive diluent, melamine, carbon black powder, glass fiber, hydrogenated castor oil and attapulgite.The fireproof coating can form a uniform and stable coating layer, has strong adhesion to the steel structure, is resistant to high temperature and humid heat, effectively avoids problems such as peeling, bulging and cracking during use, and has excellent freeze-thaw resistance, acid resistance, alkali resistance, salt mist resistance and ultraviolet radiation resistance, so that the fireproof performance of the coating does not attenuate during long-term outdoor use, and the service life of the coating is effectively prolonged.

Description

Technical Field

[0001] This invention relates to the field of fire-retardant coating technology, and in particular to an outdoor intumescent fire-retardant coating for steel structures and its preparation method. Background Technology

[0002] Steel structures possess advantages such as high strength, high toughness, earthquake resistance, light weight, small size, and low price, making them one of the most widely used steel materials in the construction industry. Although steel is not easily combustible, it is a highly conductive material and not fire-resistant. Furthermore, when the temperature rises to the critical temperature of the steel structure, its yield stress is only 40% of the value at room temperature, leading to a sharp decrease in load-bearing capacity. Therefore, unprotected steel structures will rapidly collapse and be destroyed in the event of a fire, causing significant fire damage. Consequently, the protection of steel structures is receiving increasing attention.

[0003] Intumescent fire-retardant coatings are widely used in the fire protection of steel structures due to their advantages such as light weight, thin coating thickness, and good workability. Since most steel structure buildings are located outdoors, they are significantly affected by environmental changes; therefore, the requirements for coatings must be adapted to these environmental variations. Common fire-retardant systems in intumescent fire-retardant coatings include ammonium polyphosphate (APP), melamine (MEL), and pentaerythritol (PE). However, existing intumescent fire-retardant coatings still suffer from problems such as blistering and cracking after application, resulting in poor flame-retardant performance. Therefore, it is necessary to develop a high-performance intumescent fire-retardant coating to address these issues. Summary of the Invention

[0004] In view of this, the present invention proposes an outdoor intumescent fireproof coating for steel structures and its preparation method.

[0005] The technical solution of this invention is implemented as follows: An outdoor intumescent fireproof coating for steel structures includes a matrix and a curing agent. The matrix comprises the following raw materials in parts by weight: 24-28 parts of bisphenol A type epoxy resin, 8-10 parts of low-viscosity aromatic epoxy resin, 9-11 parts of aerogel, 16-18 parts of ammonium polyphosphate, 12-14 parts of ammonium pentaborate, 4-7 parts of pretreated expanded graphite, 10-13 parts of composite filler, 0.2-0.3 parts of polyamide wax, 1-2 parts of dispersant, and 5-7 parts of reactive diluent. The curing agent comprises the following raw materials in parts by weight: 50-60 parts of polyamide resin, 2-3 parts of low-viscosity aromatic epoxy resin, 12-16 parts of reactive diluent, 7-10 parts of melamine, 0.1-0.2 parts of carbon black powder, 1-1.8 parts of glass fiber, 0.2-0.5 parts of hydrogenated castor oil, and 5-8 parts of attapulgite.

[0006] Furthermore, the mass ratio of the matrix to the curing agent is 3-4:1; the dispersant is one or more of polyethylene glycol, sodium dodecylbenzenesulfonate, and sodium polycarboxylate; the polyamide resin is DOMIDEG-650; the low-viscosity aromatic epoxy resin is EPON RESIN 8111; and the reactive diluent is selected from one or more of Grilonit RV 1812 and Araldite DY-H.

[0007] Furthermore, the aerogel is a SiO2 aerogel with a D90 ≤ 50 μm.

[0008] Furthermore, the glass fiber is alkali-free chopped glass fiber with a length of 3-6 mm and a diameter of 9-13 μm.

[0009] Furthermore, the glass fiber is T436H alkali-free chopped glass fiber.

[0010] Furthermore, the pretreated expanded graphite is obtained by grinding expanded graphite with dimethyldimethoxysilane; the mass ratio of expanded graphite to dimethyldimethoxysilane is 8~9:1~1.2.

[0011] Furthermore, the method for preparing the composite filler is as follows: (1) Carbon nanotubes were added to a mixed acid solution and ultrasonically treated, then washed and vacuum dried to obtain carboxylated carbon nanotubes; (2) Hexadecyltrimethoxysilane was added to an ethanol solution for hydrolysis to obtain a hydrolysate. Then, carboxylated carbon nanotubes and basalt fibers were added to the hydrolysate for stirring, washing, and vacuum drying to obtain a mixture. (3) Add ethylenediamine polyoxyethylene polyoxypropylene ether to an ethanol solution, and then add the mixture and sonicate to obtain a composite filler.

[0012] Furthermore, the composite filler comprises the following raw materials in parts by weight: 8-10 parts carbon nanotubes, 13-15 parts basalt fiber, 3-5 parts hexadecyltrimethoxysilane, and 6-8 parts ethylenediamine polyoxyethylene polyoxypropylene ether.

[0013] Furthermore, the mixed acid comprises a nitric acid solution and a sulfuric acid solution in a volume ratio of 1:3~4; the concentration of the nitric acid solution is 80~90 wt% v / v; the concentration of the sulfuric acid solution is 90~95% v / v; the volume ratio of the carbon nanotubes to the mixed acid solution is 1:4~5 g / mL; the concentration of the ethanol solution is 90~95% v / v; the weight of the hexadecyltrimethoxysilane is 1%~2% of the weight of the hydrolysate; and the weight of the ethylenediamine polyoxyethylene polyoxypropylene ether is 2%~4% of the weight of the ethanol solution.

[0014] Furthermore, the stirring temperature is 60~70℃, the stirring speed is 80~120r / min, and the stirring time is 4~5h.

[0015] The preparation method of outdoor intumescent fire-retardant coating for steel structures includes the following steps: S1. Mix bisphenol A type epoxy resin, low viscosity aromatic epoxy resin, and reactive diluent. Add aerogel, ammonium polyphosphate, ammonium pentaborate, and dispersant and stir to obtain a mixture. Mix the mixture with pretreated expanded graphite, composite filler, and polyamide wax to obtain a matrix. S2. Mix polyamide resin, low-viscosity aromatic epoxy resin and reactive diluent, add carbon black powder and glass fiber and mix well, then add hydrogenated castor oil and attapulgite clay and mix well, and finally add melamine and mix well to obtain curing agent. S3. Mix the matrix and curing agent evenly to obtain the outdoor intumescent steel structure fireproof coating.

[0016] Furthermore, in step S1, the stirring speed is 200~700 r / min and the stirring time is 15~30 min; in step S2, the stirring speed is 300~500 r / min and the stirring time is 10~30 min.

[0017] Furthermore, the basalt fibers have a diameter of 10 μm and a length of 80 μm.

[0018] Compared with the prior art, the beneficial effects of the present invention are: The fire-retardant coating of this invention uses a specific matrix and curing agent in a two-component formula that is rationally and scientifically formulated. It can form a uniform and stable coating with strong adhesion to steel structures. It is resistant to heat and damp heat, effectively preventing problems such as peeling, bulging, and cracking during use. Furthermore, the coating has excellent freeze-thaw resistance, acid resistance, alkali resistance, salt spray resistance, and UV radiation resistance, ensuring that the fire-retardant performance of the coating does not decrease during long-term outdoor use, effectively extending the service life of the coating.

[0019] This invention improves the stability of fire-retardant coatings, enhances the adhesion between the coating and steel structures, and improves outdoor weather resistance through the synergistic effect of raw materials such as aerogel, pretreatment, and composite fillers during the preparation of the matrix. At the same time, it can significantly enhance the fire resistance of the fire-retardant coating and enhance the density of the char layer during combustion, effectively preventing the char layer from cracking or collapsing, thereby improving the fireproof and heat insulation effect.

[0020] This invention employs hexadecyltrimethoxysilane and ethylenediamine polyoxyethylene polyoxypropylene ether to treat carbon nanotubes and basalt fibers during matrix preparation. This improves their compatibility and stability in coatings, enhances their adhesion to the coating, and improves the protection of steel structures in harsh outdoor environments such as strong ultraviolet radiation, high humidity, and coastal salt spray. Furthermore, it helps the coating maintain a dense structure during combustion, preventing cracking or collapse. Pretreatment of expanded graphite enhances its dispersibility and stability in coatings, improves the interfacial bonding between expanded graphite and other raw materials, and further improves the coating's outdoor weather resistance and performance. Detailed Implementation

[0021] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0022] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0023] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0024] The polyamide resin of this invention is DOMIDEG-650, and the low-viscosity aromatic epoxy resin is EPON RESIN 8111.

[0025] Example 1 An outdoor intumescent fireproof coating for steel structures, comprising a matrix and a curing agent in a mass ratio of 3:1; The matrix comprises the following raw materials in parts by weight: 24 parts bisphenol A type epoxy resin, 9 parts low-viscosity aromatic epoxy resin, 11 parts aerogel, 17 parts ammonium polyphosphate, 14 parts ammonium pentaborate, 7 parts pretreated expanded graphite, 10 parts composite filler, 0.3 parts polyamide wax, 1 part dispersant, and 5 parts reactive diluent; the dispersant is composed of polyethylene glycol and sodium polycarboxylate in a mass ratio of 1:1; the aerogel is SiO2 aerogel with D90 ≤ 50 μm; and the reactive diluent is Grilonit RV 1812. The curing agent comprises the following raw materials in parts by weight: 50 parts polyamide resin, 2 parts low-viscosity aromatic epoxy resin, 16 parts reactive diluent, 7 parts melamine, 0.2 parts carbon black powder, 1.6 parts glass fiber, 0.5 parts hydrogenated castor oil, and 5 parts attapulgite clay; the reactive diluent is composed of Araldite DY-H.

[0026] The pretreated expanded graphite is obtained by grinding expanded graphite with dimethyldimethoxysilane, wherein the mass ratio of expanded graphite to dimethyldimethoxysilane is 9:1.

[0027] The composite filler comprises the following raw materials in parts by weight: 9 parts carbon nanotubes, 13 parts basalt fiber, 5 parts hexadecyltrimethoxysilane, and 7 parts ethylenediamine polyoxyethylene polyoxypropylene ether.

[0028] The method for preparing the composite filler is as follows: (1) Carbon nanotubes were added to a mixed acid solution consisting of nitric acid solution (concentration 80wt%v / v) and sulfuric acid solution (concentration 95wt%v / v) with a volume ratio of 1:3 and ultrasonically treated. Then, the solution was washed and vacuum dried to obtain carboxylated carbon nanotubes. The ratio of carbon nanotubes to mixed acid was 1:5 g / mL. (2) Hexadecyltrimethoxysilane was added to an ethanol solution (concentration 90wt%v / v) for hydrolysis to obtain a hydrolysate. The weight of hexadecyltrimethoxysilane was 2% of the weight of the hydrolysate. Then, carboxylated carbon nanotubes and basalt fibers were added to the hydrolysate and stirred at a stirring speed of 120r / min, a temperature of 60℃ and a time of 5h. After stirring, the mixture was washed and dried under vacuum to obtain a mixture. (3) Add ethylenediamine polyoxyethylene polyoxypropylene ether to an ethanol solution (concentration 90wt%v / v), the weight of ethylenediamine polyoxyethylene polyoxypropylene ether is 2% of the weight of the ethanol solution, and then add the mixture and sonicate to obtain the composite filler.

[0029] The preparation method of outdoor intumescent fire-retardant coating for steel structures includes the following steps: S1. Bisphenol A type epoxy resin, low viscosity aromatic epoxy resin, and reactive diluent are stirred at 300 r / min for 10 min. Aerogel, ammonium polyphosphate, ammonium pentaborate, and dispersant are added and stirred for 25 min to obtain a mixture. The mixture is then stirred with pretreated expanded graphite, composite filler, and polyamide wax at 700 r / min for 15 min to obtain a matrix. S2. Mix polyamide resin, low-viscosity aromatic epoxy resin and reactive diluent at 300 r / min for 15 min. Add carbon black powder and glass fiber and mix for 15 min. Then add hydrogenated castor oil and attapulgite clay and mix. Finally, add melamine and mix at 400 r / min and 60℃ for 30 min to obtain curing agent. S3. Mix the matrix and curing agent evenly to obtain the outdoor intumescent steel structure fireproof coating.

[0030] Example 2 An outdoor intumescent fireproof coating for steel structures, comprising a matrix and a curing agent in a mass ratio of 4:1; The matrix comprises the following raw materials in parts by weight: 25 parts bisphenol A type epoxy resin, 8 parts low-viscosity aromatic epoxy resin, 9 parts aerogel, 18 parts ammonium polyphosphate, 12 parts ammonium pentaborate, 5 parts pretreated expanded graphite, 13 parts composite filler, 0.3 parts polyamide wax, 2 parts dispersant, and 7 parts reactive diluent; the dispersant is composed of polyethylene glycol and sodium dodecylbenzenesulfonate in a mass ratio of 2:1; the aerogel is SiO2 aerogel with D90 ≤ 50 μm; the reactive diluent is Grilonit RV 1812; The curing agent comprises the following raw materials in parts by weight: 60 parts polyamide resin, 3 parts low-viscosity aromatic epoxy resin, 15 parts reactive diluent, 8 parts melamine, 0.2 parts carbon black powder, 1.8 parts glass fiber, 0.3 parts hydrogenated castor oil, and 8 parts attapulgite clay; the reactive diluent is composed of Grilonit RV 1812 and Araldite DY-H in a mass ratio of 1:2.

[0031] The pretreated expanded graphite is obtained by grinding expanded graphite with dimethyldimethoxysilane, wherein the mass ratio of expanded graphite to dimethyldimethoxysilane is 8:1.2.

[0032] The composite filler comprises the following raw materials in parts by weight: 8 parts carbon nanotubes, 15 parts basalt fiber, 3 parts hexadecyltrimethoxysilane, and 6 parts ethylenediamine polyoxyethylene polyoxypropylene ether.

[0033] The method for preparing the composite filler is as follows: (1) Carbon nanotubes were added to a mixed acid solution consisting of nitric acid solution (concentration 85wt%v / v) and sulfuric acid solution (concentration 90wt%v / v) with a volume ratio of 1:4 and ultrasonically treated. Then, the solution was washed and vacuum dried to obtain carboxylated carbon nanotubes. The ratio of carbon nanotubes to mixed acid was 1:4 g / mL. (2) Hexadecyltrimethoxysilane was added to an ethanol solution (concentration 95wt%v / v) for hydrolysis to obtain a hydrolysate. The weight of hexadecyltrimethoxysilane was 1% of the weight of the hydrolysate. Then, carboxylated carbon nanotubes and basalt fibers were added to the hydrolysate and stirred at a stirring speed of 100r / min, a temperature of 70℃ and a time of 4h. After stirring, the mixture was washed and dried under vacuum to obtain a mixture. (3) Add ethylenediamine polyoxyethylene polyoxypropylene ether to an ethanol solution (concentration 95wt%v / v), the weight of ethylenediamine polyoxyethylene polyoxypropylene ether is 3% of the weight of the ethanol solution, and then add the mixture and sonicate to obtain the composite filler.

[0034] The preparation method of outdoor intumescent fire-retardant coating for steel structures includes the following steps: S1. Bisphenol A type epoxy resin, low viscosity aromatic epoxy resin, and reactive diluent are stirred at 260 r / min for 25 min. Aerogel, ammonium polyphosphate, ammonium pentaborate, and dispersant are added and stirred for 25 min to obtain a mixture. The mixture is then mixed with pretreated expanded graphite, composite filler, and polyamide wax at 600 r / min for 20 min to obtain a matrix. S2. Mix polyamide resin, low-viscosity aromatic epoxy resin and reactive diluent at 300 r / min for 12 min. Add carbon black powder and glass fiber and mix for 20 min. Then add hydrogenated castor oil and attapulgite clay and mix. Finally, add melamine and mix at 500 r / min and 60℃ for 25 min to obtain curing agent. S3. Mix the matrix and curing agent evenly to obtain the outdoor intumescent steel structure fireproof coating.

[0035] Example 3 An outdoor intumescent fireproof coating for steel structures, comprising a matrix and a curing agent in a mass ratio of 3:1; The matrix comprises the following raw materials in parts by weight: 28 parts bisphenol A type epoxy resin, 10 parts low-viscosity aromatic epoxy resin, 10 parts aerogel, 16 parts ammonium polyphosphate, 13 parts ammonium pentaborate, 6 parts pretreated expanded graphite, 12 parts composite filler, 0.2 parts polyamide wax, 1.8 parts dispersant, and 6 parts reactive diluent; the dispersant is composed of sodium dodecylbenzenesulfonate and sodium polycarboxylate in a mass ratio of 1:3; the aerogel is SiO2 aerogel with D90 ≤ 50 μm; the reactive diluent is Grilonit RV 1812; The curing agent comprises the following raw materials in parts by weight: 58 parts polyamide resin, 3 parts low-viscosity aromatic epoxy, 14 parts reactive diluent, 10 parts melamine, 0.1 parts carbon black powder, 1.5 parts glass fiber, 0.4 parts hydrogenated castor oil, and 7 parts attapulgite clay; the reactive diluent is composed of Grilonit RV 1812 and Araldite DY-H in a mass ratio of 3:1.

[0036] The pretreated expanded graphite is obtained by grinding expanded graphite with dimethyldimethoxysilane, wherein the mass ratio of expanded graphite to dimethyldimethoxysilane is 8:1.

[0037] The composite filler comprises the following raw materials in parts by weight: 10 parts carbon nanotubes, 14 parts basalt fiber, 4 parts hexadecyltrimethoxysilane, and 8 parts ethylenediamine polyoxyethylene polyoxypropylene ether.

[0038] The method for preparing the composite filler is as follows: (1) Carbon nanotubes were added to a mixed acid solution consisting of nitric acid solution (concentration 90wt%v / v) and sulfuric acid solution (concentration 90wt%v / v) with a volume ratio of 1:3 and ultrasonically treated. Then, the solution was washed and vacuum dried to obtain carboxylated carbon nanotubes. The ratio of carbon nanotubes to mixed acid was 1:5 g / mL. (2) Hexadecyltrimethoxysilane was added to an ethanol solution (concentration 95wt%v / v) for hydrolysis to obtain a hydrolysate. The weight of hexadecyltrimethoxysilane was 1.8% of the weight of the hydrolysate. Then, carboxylated carbon nanotubes and basalt fibers were added to the hydrolysate and stirred at a stirring speed of 80r / min, a temperature of 60℃ and a time of 4h. After stirring, the mixture was washed and dried under vacuum to obtain a mixture. (3) Add ethylenediamine polyoxyethylene polyoxypropylene ether to an ethanol solution (concentration 90wt%v / v), the weight of ethylenediamine polyoxyethylene polyoxypropylene ether is 4% of the weight of the ethanol solution, and then add the mixture and sonicate to obtain the composite filler.

[0039] The preparation method of outdoor intumescent fire-retardant coating for steel structures includes the following steps: S1. Bisphenol A type epoxy resin, low viscosity aromatic epoxy resin, and reactive diluent are stirred at 200 r / min for 30 min. Aerogel, ammonium polyphosphate, ammonium pentaborate, and dispersant are added and stirred for 25 min to obtain a mixture. The mixture is then stirred with pretreated expanded graphite, composite filler, and polyamide wax at 500 r / min for 15 min to obtain a matrix. S2. Mix polyamide resin, low-viscosity aromatic epoxy resin and reactive diluent at 400 r / min for 10 min. Add carbon black powder and glass fiber and mix for 20 min. Then add hydrogenated castor oil and attapulgite clay and mix. Finally, add melamine and mix at 500 r / min and 60℃ for 20 min to obtain curing agent. S3. Mix the matrix and curing agent evenly to obtain the outdoor intumescent steel structure fireproof coating.

[0040] Comparative Example 1 Based on Comparative Example 3, the preparation method of the composite filler in this comparative example matrix is ​​different, while the rest remains the same. The composite filler is obtained by mixing 10 parts of carbon nanotubes and 14 parts of basalt fiber.

[0041] Comparative Example 2 Based on Comparative Example 3, this comparative example matrix does not contain composite fillers, while the rest remains the same.

[0042] The matrix comprises the following raw materials in parts by weight: 28 parts of bisphenol A type epoxy resin, 10 parts of aerogel, 16 parts of ammonium polyphosphate, 13 parts of ammonium pentaborate, 15 parts of melamine, 6 parts of pretreated expanded graphite, 0.2 parts of polyamide wax, 1.8 parts of dispersant, and 110 parts of deionized water.

[0043] Comparative Example 3 Based on Comparative Example 3, this comparative example changes the proportion of the matrix raw materials, while keeping the rest the same.

[0044] The matrix comprises the following raw materials in parts by weight: 20 parts of bisphenol A type epoxy resin, 1 part of low-viscosity aromatic epoxy resin, 18 parts of aerogel, 10 parts of ammonium polyphosphate, 24 parts of ammonium pentaborate, 22 parts of pretreated expanded graphite, 1 part of composite filler, 0.8 parts of polyamide wax, 0.2 parts of dispersant, and 0 parts of reactive diluent.

[0045] Comparative Example 4 Based on Comparative Example 3, this comparative example changes the ratio of the curing agent raw materials, while keeping the rest the same.

[0046] The curing agent comprises the following raw materials in parts by weight: 36 parts polyamide resin, 12 parts low-viscosity aromatic epoxy resin, 24 parts reactive diluent, 10 parts melamine, 9 parts carbon black powder, 0.2 parts glass fiber, 0.4 parts hydrogenated castor oil, and 2.4 parts attapulgite.

[0047] The outdoor intumescent fireproof coatings for steel structures obtained in Examples 1-3 and Comparative Examples 1, 2, 3, and 4 were subjected to performance tests according to GB14907-2018 "Fireproof Coatings for Steel Structures". The results are shown in Table 1 below.

[0048] Table 1

[0049] The results above show that the outdoor intumescent steel structure fireproof coatings prepared in Examples 1-3 achieve good performance through scientific and reasonable raw material ratios. After drying, they are free of cracks and have strong adhesion. They also exhibit a uniform and delicate fluid state after stirring, without clumping. After treatments such as exposure to heat, damp heat, freeze-thaw cycles, acid and alkali treatment, salt spray corrosion, and ultraviolet irradiation, the coatings have a good appearance and are free from delamination, peeling, hollowing, cracking, and powdering. The reduction in heat insulation efficiency meets the relevant requirements, ensuring that the fireproof performance of the coating does not decrease during long-term outdoor use, effectively extending the service life of the coating. Its fire resistance time is >90 minutes, indicating good fireproof performance.

[0050] Compared with Example 3, Comparative Example 1 had a different preparation method for the composite filler in the matrix, Comparative Example 2 did not contain composite filler in its matrix, Comparative Example 3 changed the raw material ratio of the matrix, and Comparative Example 4 changed the raw material ratio of the curing agent. These differences resulted in the raw materials failing to achieve a synergistic effect, affecting the performance of the prepared fire-retardant coating. In terms of weather resistance, varying degrees of delamination, peeling, blistering, and cracking occurred, impacting the use of the fire-retardant coating on steel structures. Therefore, this invention uses a matrix and curing agent with a specific composition for a two-component combination. Furthermore, the use of hexadecyltrimethoxysilane and ethylenediamine polyoxyethylene polyoxypropylene ether to treat carbon nanotubes and basalt fibers during matrix preparation improves their compatibility and stability in the coating, enhances their adhesion to the coating, and improves the protective effect of steel structures in harsh outdoor environments such as strong ultraviolet radiation, high humidity, and coastal salt spray. It also helps the coating maintain a dense structure during combustion, preventing cracking or collapse, further improving the outdoor weather resistance and performance of the coating.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An outdoor intumescent fireproof coating for steel structures, comprising a matrix and a curing agent, characterized in that, The matrix comprises the following raw materials in parts by weight: 24-28 parts of bisphenol A type epoxy resin, 8-10 parts of low-viscosity aromatic epoxy resin, 9-11 parts of aerogel, 16-18 parts of ammonium polyphosphate, 12-14 parts of ammonium pentaborate, 4-7 parts of pretreated expanded graphite, 10-13 parts of composite filler, 0.2-0.3 parts of polyamide wax, 1-2 parts of dispersant, and 5-7 parts of reactive diluent; the curing agent comprises the following raw materials in parts by weight: 50-60 parts of polyamide resin, 2-3 parts of low-viscosity aromatic epoxy resin, 12-16 parts of reactive diluent, 7-10 parts of melamine, 0.1-0.2 parts of carbon black powder, 1-1.8 parts of glass fiber, 0.2-0.5 parts of hydrogenated castor oil, and 5-8 parts of attapulgite.

2. The outdoor intumescent fireproof coating for steel structures according to claim 1, characterized in that, The mass ratio of the matrix to the curing agent is 3-4:1; the dispersant is one or more of polyethylene glycol, sodium dodecylbenzenesulfonate, and sodium polycarboxylate; the polyamide resin is DOMIDEG-650; the low-viscosity aromatic epoxy resin is EPON RESIN 8111; and the reactive diluent is one or more of Grilonit RV 1812 and Araldite DY-H.

3. The outdoor intumescent fireproof coating for steel structures according to claim 1, characterized in that, The aerogel is a SiO2 aerogel with a diameter of 90 ≤ 50 μm.

4. The outdoor intumescent fireproof coating for steel structures according to claim 1, characterized in that, The pretreated expanded graphite is obtained by grinding expanded graphite with dimethyldimethoxysilane; the mass ratio of expanded graphite to dimethyldimethoxysilane is 8~9:1~1.

2.

5. The outdoor intumescent fireproof coating for steel structures according to claim 1, characterized in that, The method for preparing the composite filler is as follows: (1) Carbon nanotubes were added to a mixed acid solution and ultrasonically treated, then washed and vacuum dried to obtain carboxylated carbon nanotubes; (2) Hexadecyltrimethoxysilane was added to an ethanol solution for hydrolysis to obtain a hydrolysate. Then, carboxylated carbon nanotubes and basalt fibers were added to the hydrolysate for stirring, washing, and vacuum drying to obtain a mixture. (3) Add ethylenediamine polyoxyethylene polyoxypropylene ether to an ethanol solution, and then add the mixture and sonicate to obtain a composite filler.

6. The outdoor intumescent fireproof coating for steel structures according to claim 5, characterized in that, The composite filler comprises the following raw materials in parts by weight: 8-10 parts carbon nanotubes, 13-15 parts basalt fiber, 3-5 parts hexadecyltrimethoxysilane, and 6-8 parts ethylenediamine polyoxyethylene polyoxypropylene ether.

7. The outdoor intumescent fireproof coating for steel structures according to claim 5, characterized in that, The mixed acid comprises a nitric acid solution and a sulfuric acid solution in a volume ratio of 1:3 to 4; the concentration of the nitric acid solution is 80 to 90 wt% v / v; the concentration of the sulfuric acid solution is 90 to 95% v / v; the ratio of carbon nanotubes to the mixed acid solution in g / mL is 1:4 to 5; the concentration of the ethanol solution is 90 to 95% v / v; the weight of the hexadecyltrimethoxysilane is 1% to 2% of the weight of the hydrolysate; and the weight of the ethylenediamine polyoxyethylene polyoxypropylene ether is 2% to 4% of the weight of the ethanol solution.

8. The outdoor intumescent fireproof coating for steel structures according to claim 5, characterized in that, The stirring temperature is 60~70℃, the stirring speed is 80~120r / min, and the stirring time is 4~5h.

9. The method for preparing the outdoor intumescent fire-retardant coating for steel structures according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Mix bisphenol A type epoxy resin, low viscosity aromatic epoxy resin, and reactive diluent. Add aerogel, ammonium polyphosphate, ammonium pentaborate, and dispersant and stir to obtain a mixture. Mix the mixture with pretreated expanded graphite, composite filler, and polyamide wax to obtain a matrix. S2. Mix polyamide resin, low-viscosity aromatic epoxy resin and reactive diluent, add carbon black powder and glass fiber and mix well, then add hydrogenated castor oil and attapulgite clay and mix well, and finally add melamine and mix well to obtain curing agent. S3. Mix the matrix and curing agent evenly to obtain the outdoor intumescent steel structure fireproof coating.

10. The preparation method of the outdoor intumescent fireproof coating for steel structures according to claim 9, characterized in that, In step S1, the stirring speed is 200~700 r / min and the stirring time is 15~30 min; in step S2, the stirring speed is 300~500 r / min and the stirring time is 10~30 min.

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