High-strength fire-resistant steel for fireproof door and preparation method of high-strength fire-resistant steel

Abstract

The invention discloses high-strength fireproof steel for a fireproof door and a preparation method of the high-strength fireproof steel, and relates to the technical field of fireproof paints.The high-strength fireproof steel comprises steel and a fireproof coating arranged on the surface of the steel; the fireproof coating is formed by coating and curing a fireproof coating; the fireproof coating comprises the following components: 10-20 parts of a fiber filler, 30-50 parts of a particle filler, 30-40 parts of a resin material and 1-3 parts of an auxiliary agent. The inorganic fibers and the inorganic particles are compounded, the phosphorus-containing compound is introduced into a resin system, the fireproof coating is prepared, and fire resistance, mechanical strength and construction feasibility can be considered.

Description

Technical Field

[0001] The present invention relates to the technical field of fire retardant coatings, in particular to a high-strength fire-resistant steel material for fire doors and a preparation method thereof. Background Art

[0002] Preventing and blocking fires is crucial to preventing the spread of fire and smoke. Fire doors, as key components of fire protection systems, often incorporate steel structures. However, steel structures have poor fire resistance. While steel itself does not burn, its fire resistance limit is extremely low. Under the high temperatures caused by fire, its strength and rigidity decrease significantly. At temperatures around 540°C, steel's strength drops to 50%, making it difficult to withstand loads. Above 600°C, steel essentially loses its load-bearing capacity. Fire temperatures can reach 800-1000°C, quickly softening and collapsing steel, thus compromising the proper use of fire doors. To improve the fire resistance of steel, a conventional method is to apply a fire-retardant coating to the steel surface. Therefore, we propose a high-strength, fire-resistant steel for fire doors and a method for its preparation. Summary of the Invention

[0003] The object of the present invention is to provide a high-strength fire-resistant steel material for fire doors and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions: a high-strength fire-resistant steel material for fire doors, comprising a steel material and a fire-resistant coating provided on the surface of the steel material; The fire retardant coating is formed by applying and curing a fire retardant paint.

[0005] Furthermore, the fire retardant coating comprises the following components: fiber filler, particle filler, resin material, additives and solvent.

[0006] Furthermore, the fiber filler is a mixture of one or more of glass fiber, ceramic fiber, basalt fiber, sepiolite fiber, aramid fiber, benzimidazole fiber, carbon fiber, mineral wool fiber, and cellulose fiber.

[0007] Furthermore, the particle filler is a mixture of one or more of aluminum hydroxide, magnesium hydroxide, borate, phosphate, hollow microspheres, montmorillonite, mica powder, expanded graphite, silicon dioxide, antimony oxide, titanium dioxide, and perlite.

[0008] Furthermore, the resin material includes a mixture of one or more of epoxy resin, phenolic resin, polyacrylate resin, and curing agent.

[0009] Furthermore, the auxiliary agents include leveling agents, dispersants, defoaming agents, and surfactants.

[0010] Furthermore, the fire retardant coating comprises the following components: 10 to 20 parts of fiber filler, 30 to 50 parts of particle filler, 30 to 40 parts of resin material and 1 to 3 parts of additives.

[0011] Furthermore, the fiber filler is a mixture of sepiolite fiber and glass fiber, with a mass ratio of (2-4): (6-8); The length of the sepiolite fiber is 100 to 150 μm, and the length of the glass fiber is 100 to 300 μm.

[0012] Furthermore, the particle filler is a mixture of aluminum hydroxide, magnesium hydroxide, and zinc borate, with a mass ratio of (6-7): (2-3): 1; The particle size of aluminum hydroxide is 5 to 20 μm, the particle size of magnesium hydroxide is 1 to 10 μm, and the particle size of zinc borate is 10 to 50 μm.

[0013] Furthermore, the thickness of the fire retardant coating is 1.8 to 5.5 mm.

[0014] Furthermore, the steel material is one of 304, 316, 201 stainless steel and galvanized steel plate.

[0015] In the above technical solution, the filler is a combination of fibrous and granular fillers. The fibers can form a stable three-dimensional skeleton structure at high temperatures, while the decomposition products of the particles effectively fill the pores of the skeleton, thereby constructing a multi-layered three-dimensional thermal insulation barrier, achieving a synergistically enhanced fire retardant effect and significantly improving the fire resistance of the coating. At the same time, the macro-reinforcement effect of the fibrous filler and the micro-reinforcement effect of the granular filler work together to not only improve the mechanical strength of the coating, but also increase its surface hardness and enhance the chemical stability of the coating.

[0016] The fiber fillers are sepiolite and glass fiber. The sepiolite fiber's nanoporous structure enhances the coating's thermal insulation, and its excellent thixotropic properties prevent sagging during application. Glass fiber creates a three-dimensional reinforcement network, ensuring the coating's structural integrity at high temperatures and preventing cracking in the carbon layer. The granular fillers are aluminum hydroxide, magnesium hydroxide, and zinc borate. Aluminum hydroxide serves as the primary flame retardant, providing heat-absorbing flame retardancy at low to medium temperatures. Magnesium hydroxide supplements flame retardancy requirements at high temperatures, broadening the coating's effective flame retardant temperature range. Zinc borate melts at high temperatures to form a dense, glassy barrier that effectively isolates oxygen. The synergistic effect of this multi-component granular filler ensures full flame retardancy across the entire temperature range, ensuring reliable and durable fire protection.

[0017] The resin system provides adhesion and film-forming properties for the coating, as well as chemical resistance and stability after curing.

[0018] A method for preparing high-strength fire-resistant steel for fire doors, comprising the following process steps: Mixing fiber filler, particle filler, resin system, additives and solvent, stirring and dispersing to obtain coating; The paint is applied to the surface of the steel and solidified to form a fire-resistant coating to obtain fire-resistant steel.

[0019] Furthermore, the resin system includes the following components: by mass, 60 to 70 parts of waterborne epoxy resin emulsion, 30 to 40 parts of polyacrylate emulsion, 3 to 5 parts of curing agent, and 0.5 to 2 parts of accelerator.

[0020] Furthermore, the resin system is prepared by the following process: taking a curing agent and an accelerator, stirring and dissolving them in a polyacrylate emulsion; and adding a water-based epoxy resin emulsion to obtain.

[0021] Furthermore, the curing agent is dicyandiamide curing agent; the accelerator is organic urea; The solid content of the waterborne epoxy resin emulsion is 40 to 60 wt %.

[0022] Furthermore, the curing process is: keeping warm at 60°C for 1 hour; keeping warm at 100°C for 1 hour; keeping warm at 125°C for 2 hours.

[0023] Furthermore, the polyacrylate emulsion is prepared by the following process: Mix 1 / 2 of the emulsifier solution and the mixed monomer to obtain a pre-emulsion; Mix 1 / 10 of the pre-emulsion and the remaining emulsifier solution, add sodium bicarbonate and 1 / 2 of the initiator solution, heat to 78-82°C, stir and react until a blue phase appears, and keep warm for 10-20 minutes after the blue phase is obvious; add the remaining initiator and the remaining pre-emulsion, keep warm and react for 90-120 minutes; cool, adjust the pH of the system to 7-8, and sieve to obtain a polyacrylate emulsion.

[0024] Furthermore, the polyacrylate emulsion includes the following components: 40 to 45 parts by mass of a mixed monomer, 0.2 to 0.5 parts by mass of an initiator, and 1.0 to 1.5 parts by mass of an emulsifier.

[0025] Furthermore, the emulsifier is a mixture of alkylphenol polyoxyethylene ether (OP-10) and sodium lauryl sulfonate (SLS) in a mass ratio of 1:1; The mass concentration of the emulsifier solution is 2% to 4%; the mass concentration of the initiator solution is 1% to 5%; The solid content of the polyacrylate emulsion is 45-55wt%.

[0026] Furthermore, the mixed monomer includes the following components: in parts by mass, 20 to 23 parts of n-butyl acrylate, 11 to 13 parts of methyl methacrylate, 5 to 7 parts of styrene, 1.5 to 2.5 parts of vinyltriethoxysilane, 1.5 to 2.5 parts of octamethylcyclotetrasiloxane, 1 to 3 parts of glycidyl methacrylate and 1 to 10 parts of a phosphorus-containing olefinic compound.

[0027] Furthermore, the phosphorus-containing alkenyl compound is prepared by the following process: (1) Tripolyphosphazene chloride, acetaminophen, and a catalyst are mixed in acetone, and the mixture is heated to 60-80°C under a nitrogen atmosphere and kept warm for 8-96 hours. After the reaction, the mixture is filtered, washed, and vacuum-dried to obtain hexaacetylcyclotriphosphazene. (2) Hexaacetylcyclotriphosphazene, alcohol aqueous solution and sodium hydroxide are mixed and refluxed at 70-75°C for 4-36 hours; after the reaction, the mixture is cooled, filtered, washed and vacuum dried to obtain hexaphenylaminocyclotriphosphazene; (3) Propylenebenzaldehyde and hexaphenylaminocyclotriphosphazene are mixed in N,N-dimethylformamide and reacted at 60-65°C for 30-60 min under nitrogen atmosphere; the temperature is lowered to 50±5°C, DOPO and triethylamine are added, and the temperature is raised to 80-85°C and the reaction is continued for 1-3 h; after the reaction, the mixture is washed and vacuum dried to obtain a phosphorus-containing olefin compound.

[0028] Furthermore, in step (1), the molar ratio of tripolyphosphazene chloride (CAS No. 940-71-6), acetaminophen (CAS No. 103-90-2), and the catalyst is 1: (6.5-7.2): (0.1-7.2); The catalyst is one of triethylamine, DBU (1,8-diazabicycloundec-7-ene), and tetrabutylammonium bromide; The ratio of tripolyphosphazene chloride to acetone is (3-8) g / 100 mL.

[0029] Furthermore, in step (2), the mass ratio of the amide group in the hexaacetylcyclotriphosphazene to the sodium hydroxide is 1:(0.7-1.1); The ratio of hexaacetylcyclotriphosphazene to alcohol aqueous solution is (10-15) g / 100 mL; The alcohol-water solution is a mixture of ethanol and water in a volume ratio of 7:3; Sodium hydroxide is added in the form of a 10-20 wt% aqueous solution.

[0030] Furthermore, in step (3), the mass ratio of hexaphenylaminocyclotriphosphazene, propenylbenzaldehyde (CAS No. 77785-94-5), DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, CAS No. 35948-25-5), and triethylamine is 1: (1.1-1.2): (1.5-1.7): (0.8-1.2); The ratio of hexaphenylaminocyclotriphosphazene and N,N-dimethylformamide is (10-12) g / 100 mL; Propylene benzaldehyde contains 0.1% of the polymerization inhibitor hydroquinone and 0.05% of tetramethylpiperidinyl oxide (TEMPO).

[0031] In the above technical solution, under the action of a catalyst, the chlorine groups in tripolychlorophosphazene and acetaminophen react with the phenolic hydroxyl group to generate PO-Ph to obtain hexaacetylcyclotriphosphazene; the hexaacetylcyclotriphosphazene is hydrolyzed in an alkaline solution to generate amino groups to obtain hexaphenylaminocyclotriphosphazene. The hexaphenylamino cyclotriphosphazene then reacts with propenylbenzaldehyde, and the lone pair of electrons of the amino group in the system nucleophilically attacks the carbonyl carbon of the aldehyde group to form a hydroxylamine intermediate, which is then dehydrated to form an imine (C=N bond). The amino group preferentially undergoes a nucleophilic addition-elimination reaction with the aldehyde group to generate an imine group, forming a hexaldehyde cyclotriphosphazene compound, which is recorded as compound A. DOPO is then added, and its PH group preferentially undergoes a nucleophilic addition reaction with the imine (C=N) in compound A. The lone pair of electrons of the phosphorus atom in the PH bond nucleophilically attacks the electron-deficient carbon of the C=N bond to form a PC bond and an NH bond, thereby obtaining a cyclotriphosphazene compound with structures such as polyene, DOPO, triazine, phenyl, and elements such as nitrogen and phosphorus, which is recorded as a phosphorus-containing olefin compound.

[0032] By introducing it into a mixed monomer mixture and participating in the emulsion preparation, a polyacrylate emulsion is produced. DOPO, a triazine structure, and phosphorus and nitrogen elements are embedded in the polymer backbone. At high temperatures, they decompose to produce phosphoric acid and non-flammable gases, promoting carbon formation and releasing free radicals to interrupt the combustion chain, diluting combustible gases and heat. This, in synergy with silicone, enhances both gas-phase and condensed-phase flame retardancy, achieving intrinsic flame retardancy. Furthermore, the polyolefinic structure of the phosphorus-containing olefinic compound facilitates the formation of branched structures in the polyacrylate, increasing crosslinking points. This allows the resulting polyacrylate emulsion to be mixed with epoxy resin and cured under the action of a curing agent and heat, increasing the crosslink density. This contributes to improved mechanical properties of the resulting coating. In addition, in the mixed monomers, octamethylcyclotetrasiloxane (D4) undergoes ring-opening polymerization to form Si-O-Si segments, which react with Si-OH formed after the hydrolysis of vinyltriethoxysilane (VTES) to generate flexible silicone, which interpenetrates with the rigid epoxy network. The rotational freedom of the Si-O bond gives the coating toughness, offsets the brittleness of the epoxy resin, and can effectively improve the impact resistance of the coating; it also helps to improve the epoxy / polyacrylate phase separation and enhance the uniformity of the coating.

[0033] Furthermore, the fiber filler and the particle filler are both modified with a coupling agent.

[0034] Compared with the prior art, the present invention has the following beneficial effects: The high-strength fire-resistant steel material for fire doors of the present invention is prepared by compounding inorganic fibers and inorganic particles and introducing phosphorus-containing compounds into a resin system to prepare a fire-resistant coating, which can take into account fire resistance, mechanical strength and construction feasibility. DETAILED DESCRIPTION

[0035] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0036] In the following specific embodiments, all are laboratory tests and can be scaled up; The curing agent is dicyandiamide curing agent DYHARD-100S; the accelerator is organic urea 500SF; Water-based epoxy resin emulsion: F0704, solid content 53wt%; The emulsifier is a mixture of alkylphenol polyoxyethylene ether (OP-10) and sodium lauryl sulfonate (SLS) with a mass ratio of 1:1; Propylene benzaldehyde contains 0.1% of polymerization inhibitor hydroquinone and 0.05% of tetramethylpiperidinyl oxide; 4-hydroxystyrene contains 0.1% of polymerization inhibitor hydroquinone; The average length of sepiolite fibers is 120 μm, and the average length of glass fibers is 200 μm; The average particle size of aluminum hydroxide is 15 μm, the average particle size of magnesium hydroxide is 7.5 μm, and the average particle size of zinc borate is 30 μm; Both the fiber filler and the particle filler were modified with a coupling agent. The specific process was as follows: 1.5 wt% KH-560, a coupling agent, and an ethanol-water solution (V / V = 9:1) were mixed, the pH of the system was adjusted to 5, and the mixture was hydrolyzed for 10 minutes. An equal volume of filler was added and mixed for 20 minutes. The mixture was then dried at 80°C for 30 minutes. Propylene benzaldehyde contains 0.1% of the polymerization inhibitor hydroquinone and 0.05% of tetramethylpiperidinoxide; The thickness of the fire retardant coating is 2.0mm; the steel material is galvanized steel sheet; The additives include leveling agent BYK-354, dispersant EFKA-4010, defoamer TEGO Airex 902W, and surfactant TEGO Wet 270, with a mass ratio of 3:7:1:2.

[0037] Example 1: A method for preparing high-strength fire-resistant steel for fire doors, comprising the following process steps: Step (1): 1.1. Mix 3 g of tripolyphosphazene chloride, acetaminophen, and catalyst DBU in 100 mL of acetone, and heat to 60°C under nitrogen atmosphere for 16 h. After the reaction, filter, wash, and vacuum dry to obtain hexaacetylcyclotriphosphazene. The molar ratio of tripolyphosphazene chloride, acetaminophen, and catalyst is 1:6.5:0.1. 10 g of hexaacetylcyclotriphosphazene, 100 mL of ethanol aqueous solution (v / v = 7:3), and 10 wt% sodium hydroxide aqueous solution were mixed and refluxed at 70°C for 36 h. After the reaction, the mixture was cooled, filtered, washed, and vacuum dried to obtain hexaphenylaminocyclotriphosphazene. The mass ratio of amide group to sodium hydroxide in the hexaacetylcyclotriphosphazene was 1:0.7. 10 g of propenylbenzaldehyde and hexaphenylaminocyclotriphosphazene were mixed in 100 mL of N,N-dimethylformamide and reacted at 60°C for 60 min under nitrogen atmosphere. The temperature was then lowered to 50°C, DOPO and triethylamine were added, and the temperature was raised to 80°C and the reaction was continued for 3 h. After the reaction, the mixture was washed and dried under vacuum to obtain a phosphorus-containing olefin compound. The mass ratio of hexaphenylaminocyclotriphosphazene, propenylbenzaldehyde, DOPO, and triethylamine was 1:1.1:1.5:0.8. 1.2 Mix 1 / 2 of the emulsifier solution (4wt%) and the mixed monomers, stir for 30 minutes to obtain a pre-emulsion; mix 1 / 10 of the pre-emulsion and the remaining emulsifier solution, add sodium bicarbonate and 1 / 2 of the initiator solution (5wt%), heat to 80°C, stir and react until a blue phase appears, and keep warm for 15 minutes after the blue phase is obvious; slowly add the remaining initiator and the remaining pre-emulsion, add the initiator within 90 minutes, and add the pre-emulsion within 2 hours; then keep warm and react for 90 minutes; cool the reaction to below 40°C, adjust The system pH was adjusted to 7, the mixture was passed through a 100-mesh sieve, and water was added to obtain a polyacrylate emulsion with a solid content of 50 wt %; the polyacrylate emulsion comprised the following components, in parts by mass: 40 parts of a mixed monomer, 0.2 parts of an initiator, and 1.0 parts of an emulsifier; the mixed monomer comprised the following components, in parts by mass: 20 parts of n-butyl acrylate, 11 parts of methyl methacrylate, 5 parts of styrene, 1.5 parts of vinyltriethoxysilane, 1.5 parts of octamethylcyclotetrasiloxane, 1 part of glycidyl methacrylate, and 1 part of a phosphorus-containing alkenyl compound; 1.3 Take a curing agent and an accelerator, stir and dissolve them in the polyacrylate emulsion; add the waterborne epoxy resin emulsion to obtain a resin system; the resin system comprises the following components, by mass: 70 parts of waterborne epoxy resin emulsion, 30 parts of polyacrylate emulsion, 5 parts of curing agent, and 2 parts of accelerator; Step (2) mixing fiber filler, particle filler, resin system, additive and solvent, stirring and dispersing to obtain coating; applying the coating on the surface of steel, curing to form a fire-retardant coating, and obtaining fire-resistant steel; the curing process is: keeping warm at 60°C for 1 hour; keeping warm at 100°C for 1 hour; keeping warm at 125°C for 2 hours; the fire-retardant coating comprises the following components: 15 parts of fiber filler, 40 parts of particle filler, 35 parts of resin material and 2 parts of additive; the fiber filler is a mixture of sepiolite fiber and glass fiber, with a mass ratio of 4:6; the particle filler is a mixture of aluminum hydroxide, magnesium hydroxide and zinc borate, with a mass ratio of 7:2:1.

[0038] Example 2: A method for preparing high-strength fire-resistant steel for fire doors, comprising the following process steps: Step (1): 1.1. Mix 5 g of tripolyphosphazene chloride, acetaminophen, and catalyst DBU in 100 mL of acetone, and heat to 70°C under nitrogen atmosphere for 12 h. After the reaction, filter, wash, and vacuum dry to obtain hexaacetylcyclotriphosphazene. The molar ratio of tripolyphosphazene chloride, acetaminophen, and catalyst is 1:6.9:0.2. 12 g of hexaacetylcyclotriphosphazene, 100 mL of ethanol aqueous solution (v / v = 7:3), and 15 wt% sodium hydroxide aqueous solution were mixed and refluxed at 72°C for 30 h. After the reaction, the mixture was cooled, filtered, washed, and vacuum dried to obtain hexaphenylaminocyclotriphosphazene. The mass ratio of amide group to sodium hydroxide in the hexaacetylcyclotriphosphazene was 1:0.9. 11 g of propenylbenzaldehyde and hexaphenylaminocyclotriphosphazene were mixed in 100 mL of N,N-dimethylformamide and reacted at 62°C for 45 min under a nitrogen atmosphere. The temperature was then lowered to 50°C, DOPO and triethylamine were added, and the temperature was raised to 82°C and the reaction was continued for 2 h. After the reaction, the mixture was washed and dried under vacuum to obtain a phosphorus-containing olefin compound. The mass ratio of hexaphenylaminocyclotriphosphazene, propenylbenzaldehyde, DOPO, and triethylamine was 1:1.15:1.6:1.0. 1.2 Mix 1 / 2 of the emulsifier solution (3 wt%) and the mixed monomers, stir for 30 minutes to obtain a pre-emulsion; mix 1 / 10 of the pre-emulsion and the remaining emulsifier solution, add sodium bicarbonate and 1 / 2 of the initiator solution (3 wt%), heat to 80°C, stir and react until a blue phase appears, and keep warm for 15 minutes after the blue phase is obvious; slowly add the remaining initiator and the remaining pre-emulsion, add the initiator within 90 minutes, and add the pre-emulsion within 2 hours; then keep warm and react for 90 minutes; cool the reaction to 40°C. The solution was filtered through a 100-mesh sieve to obtain a polyacrylate emulsion having a solid content of 45 wt %; the polyacrylate emulsion comprised the following components: 42 parts by weight of a mixed monomer, 0.3 parts by weight of an initiator, and 1.2 parts by weight of an emulsifier; and the mixed monomer comprised the following components: 21 parts by weight of n-butyl acrylate, 12 parts by weight of methyl methacrylate, 6 parts by weight of styrene, 2 parts by weight of vinyltriethoxysilane, 2 parts by weight of octamethylcyclotetrasiloxane, 2 parts by weight of glycidyl methacrylate, and 5 parts by weight of a phosphorus-containing olefinic compound. 1.3 Take a curing agent and an accelerator, stir and dissolve them in the polyacrylate emulsion; add the waterborne epoxy resin emulsion to obtain a resin system; the resin system comprises the following components, by mass: 65 parts of waterborne epoxy resin emulsion, 35 parts of polyacrylate emulsion, 4 parts of curing agent, and 1.2 parts of accelerator; Step (2) mixing fiber filler, particle filler, resin system, additive and solvent, stirring and dispersing to obtain coating; applying the coating on the surface of steel, curing to form a fire-retardant coating, and obtaining fire-resistant steel; the curing process is: keeping warm at 60°C for 1 hour; keeping warm at 100°C for 1 hour; keeping warm at 125°C for 2 hours; the fire-retardant coating comprises the following components: 15 parts of fiber filler, 40 parts of particle filler, 35 parts of resin material and 2 parts of additive; the fiber filler is a mixture of sepiolite fiber and glass fiber, with a mass ratio of 3:7; the particle filler is a mixture of aluminum hydroxide, magnesium hydroxide and zinc borate, with a mass ratio of 6.5:2.5:1.

[0039] Example 3: A method for preparing high-strength fire-resistant steel for fire doors, comprising the following process steps: Step (1): 1.1. 8 g of tripolyphosphazene chloride, acetaminophen, and catalyst DBU were mixed in 100 mL of acetone, and the mixture was heated to 80° C. under nitrogen atmosphere and kept warm for 8 h. After the reaction, the mixture was filtered, washed, and vacuum-dried to obtain hexaacetylcyclotriphosphazene. The molar ratio of tripolyphosphazene chloride, acetaminophen, and catalyst was 1:7.2:0.2. 15 g of hexaacetylcyclotriphosphazene, 100 mL of ethanol aqueous solution (v / v = 7:3), and 20 wt% sodium hydroxide aqueous solution were mixed and refluxed at 75°C for 24 h. After the reaction, the mixture was cooled, filtered, washed, and vacuum dried to obtain hexaphenylaminocyclotriphosphazene. The mass ratio of amide group to sodium hydroxide in the hexaacetylcyclotriphosphazene was 1:1.1. 12 g of propenylbenzaldehyde and hexaphenylaminocyclotriphosphazene were mixed in 100 mL of N,N-dimethylformamide and reacted at 65°C for 30 min under a nitrogen atmosphere. The temperature was then lowered to 50°C, DOPO and triethylamine were added, and the temperature was raised to 85°C and the reaction was continued for 1 h. After the reaction, the mixture was washed and dried under vacuum to obtain a phosphorus-containing olefin compound. The mass ratio of hexaphenylaminocyclotriphosphazene, propenylbenzaldehyde, DOPO, and triethylamine was 1:1.2:1.7:1.2. 1.2 Mix 1 / 2 of the emulsifier solution (4wt%) and the mixed monomers, stir for 30 minutes to obtain a pre-emulsion; mix 1 / 10 of the pre-emulsion and the remaining emulsifier solution, add sodium bicarbonate and 1 / 2 of the initiator solution (5wt%), heat to 80°C, stir and react until a blue phase appears, and keep warm for 15 minutes after the blue phase becomes obvious; slowly add the remaining initiator and the remaining pre-emulsion, add the initiator within 90 minutes, and add the pre-emulsion within 2 hours; then keep warm and react for 90 minutes; cool the reaction to below 40°C , adjusting the pH of the system to 8, passing through a 100-mesh sieve to obtain a polyacrylate emulsion with a solid content of 50 wt%; the polyacrylate emulsion comprises the following components: in parts by mass, 45 parts of a mixed monomer, 0.5 parts of an initiator, and 1.5 parts of an emulsifier; the mixed monomer comprises the following components: in parts by mass, 23 parts of n-butyl acrylate, 13 parts of methyl methacrylate, 7 parts of styrene, 2.5 parts of vinyltriethoxysilane, 2.5 parts of octamethylcyclotetrasiloxane, 3 parts of glycidyl methacrylate, and 10 parts of a phosphorus-containing alkenyl compound; 1.3 Take a curing agent and an accelerator, stir and dissolve them in the polyacrylate emulsion; add the waterborne epoxy resin emulsion to obtain a resin system; the resin system comprises the following components, by mass: 60 parts of waterborne epoxy resin emulsion, 40 parts of polyacrylate emulsion, 3 parts of curing agent, and 0.5 parts of accelerator; Step (2) mixing fiber filler, particle filler, resin system, additive and solvent, stirring and dispersing to obtain coating; applying the coating on the surface of steel, curing to form a fire-retardant coating, and obtaining fire-resistant steel; the curing process is: keeping warm at 60°C for 1 hour; keeping warm at 100°C for 1 hour; keeping warm at 125°C for 2 hours; the fire-retardant coating comprises the following components: 15 parts of fiber filler, 40 parts of particle filler, 35 parts of resin material and 2 parts of additive; the fiber filler is a mixture of sepiolite fiber and glass fiber, with a mass ratio of 2:8; the particle filler is a mixture of aluminum hydroxide, magnesium hydroxide and zinc borate, with a mass ratio of 6:3:1.

[0040] Comparative Example 1: A method for preparing high-strength fire-resistant steel for fire doors, comprising the following process steps: Step (1): 1.1. Mix 3 g of tripolyphosphazene chloride, acetaminophen, and catalyst DBU in 100 mL of acetone, and heat to 60°C under nitrogen atmosphere for 16 h. After the reaction, filter, wash, and vacuum dry to obtain hexaacetylcyclotriphosphazene. The molar ratio of tripolyphosphazene chloride, acetaminophen, and catalyst is 1:6.5:0.1. 10 g of hexaacetylcyclotriphosphazene, 100 mL of ethanol aqueous solution (v / v = 7:3), and 10 wt% sodium hydroxide aqueous solution were mixed and refluxed at 70°C for 36 h. After the reaction, the mixture was cooled, filtered, washed, and vacuum dried to obtain hexaphenylaminocyclotriphosphazene. The mass ratio of amide group to sodium hydroxide in the hexaacetylcyclotriphosphazene was 1:0.7. 10 g of propenylbenzaldehyde and hexaphenylaminocyclotriphosphazene were mixed in 100 mL of N,N-dimethylformamide and reacted at 60°C for 60 min under a nitrogen atmosphere. After the reaction, the mixture was washed and vacuum dried to obtain a phosphorus-containing olefinic compound. The mass ratio of hexaphenylaminocyclotriphosphazene to propenylbenzaldehyde was 1:1.1. Steps 1.2-1.3 and (2) are the same as those in Example 1 to obtain refractory steel.

[0041] Comparative Example 2: A method for preparing high-strength fire-resistant steel for fire doors, comprising the following process steps: Step (1): 1.1. Mix 3 g of tripolyphosphazene chloride, 4-hydroxystyrene, and catalyst DBU in 100 mL of acetone, and heat to 60°C under nitrogen atmosphere for 16 h. After the reaction, filter, wash, and vacuum dry to obtain a phosphorus-containing olefin compound. The molar ratio of tripolyphosphazene chloride, 4-hydroxystyrene, and catalyst is 1:6.5:0.1. Steps 1.2-1.3 and (2) are the same as those in Example 1 to obtain refractory steel.

[0042] Comparative Example 3: A method for preparing high-strength fire-resistant steel for fire doors, comprising the following process steps: Step (1) The polyacrylate emulsion comprises the following components: in parts by mass, 40 parts of mixed monomers, 0.2 parts of initiator, and 1.0 parts of emulsifier; the mixed monomer comprises the following components: in parts by mass, 20 parts of n-butyl acrylate, 11 parts of methyl methacrylate, 5 parts of styrene, 1.5 parts of vinyltriethoxysilane, 1.5 parts of octamethylcyclotetrasiloxane, and 1 part of glycidyl methacrylate; The other process steps are the same as those in Example 1 to obtain refractory steel.

[0043] Comparative Example 4: A method for preparing high-strength fire-resistant steel for fire doors, comprising the following process steps: Step (1) The polyacrylate emulsion comprises the following components: by weight, 40 parts of mixed monomers, 0.2 parts of initiator, and 1.0 parts of emulsifier; the mixed monomer comprises the following components: by weight, 20 parts of n-butyl acrylate, 11 parts of methyl methacrylate, 5 parts of styrene, and 1 part of glycidyl methacrylate; The other process steps are the same as those in Example 1 to obtain refractory steel.

[0044] Comparative Example 5: A method for preparing high-strength fire-resistant steel for fire doors, comprising the following process steps: Step (1) The resin system comprises the following components: 100 parts by mass of waterborne epoxy resin emulsion, 5 parts by mass of curing agent, and 2 parts by mass of accelerator; The other process steps are the same as those in Example 1 to obtain refractory steel.

[0045] Experiment: The fire-retardant coatings and fire-resistant steels obtained in Examples 1-3 and Comparative Examples 1-5 were used to prepare samples, and their properties were tested and the test results were recorded: The fire resistance of the samples was tested with reference to GB / T 14907; the impact resistance of the samples was tested with reference to GB / T 1732; the tensile strength of the samples was tested with reference to GB / T 1040; and the adhesion grade of the samples was tested with reference to GB / T 9286.

[0046]

[0047] According to the data in the above table, we can clearly draw the following conclusions: The fire retardant coatings obtained in Examples 1-3 were compared with those obtained in Comparative Examples 1-5. The test results show that: Compared with the comparative example, the fire-retardant coatings obtained in Examples 1-3 have better fire resistance limit time, impact resistance height, tensile strength, and adhesion grade data, which fully demonstrates that the present invention achieves improvements in fire resistance, strength, impact resistance, and adhesion of the fire-retardant coatings.

[0048] Compared to Example 1, in Comparative Example 1, DOPO was not included in the phosphorus-containing alkenyl compound; in Comparative Example 2, the phosphorus-containing alkenyl compound was prepared from tripolyphosphazene chloride and 4-hydroxystyrene; in Comparative Example 3, the polyacrylate emulsion did not include the phosphorus-containing alkenyl compound; in Comparative Example 4, the polyacrylate emulsion did not include the phosphorus-containing alkenyl compound, vinyltriethoxysilane, or octamethylcyclotetrasiloxane; and in Comparative Example 5, the resin system did not include the polyacrylate emulsion. The fire-resistant coatings obtained in Comparative Examples 1-5 showed deterioration in their fire resistance limit time, impact resistance height, tensile strength, and adhesion rating. This indicates that the present invention's design of the fire-resistant coating process and its components can promote comprehensive improvements in fire resistance, strength, impact resistance, and adhesion.

[0049] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing high-strength fire-resistant steel for fire doors, characterized by: It includes steel and a fire-retardant coating provided on the surface of the steel; the fire-retardant coating is formed by applying and curing the fire-retardant paint; The fire retardant coating comprises the following components: 10 to 20 parts of fiber filler, 30 to 50 parts of particle filler, 30 to 40 parts of resin material and 1 to 3 parts of auxiliary agent.

2. The method for preparing a high-strength fire-resistant steel material for fire doors according to claim 1, characterized in that: The fiber filler is a mixture of sepiolite fiber and glass fiber, with a mass ratio of (2-4): (6-8).

3. The method for preparing a high-strength fire-resistant steel material for fire doors according to claim 1, characterized in that: The particle filler is a mixture of aluminum hydroxide, magnesium hydroxide and zinc borate, with a mass ratio of (6-7): (2-3):

1.

4. A method for preparing high-strength fire-resistant steel for fire doors, characterized by: The process steps include: Mixing fiber filler, particle filler, resin system, additives and solvent, stirring and dispersing to obtain coating; The paint is applied to the surface of the steel and solidified to form a fire-resistant coating to obtain fire-resistant steel.

5. The method for preparing a high-strength fire-resistant steel material for fire doors according to claim 1, characterized in that: The resin system comprises the following components: by mass, 60 to 70 parts of waterborne epoxy resin emulsion, 30 to 40 parts of polyacrylate emulsion, 3 to 5 parts of curing agent, and 0.5 to 2 parts of accelerator.

6. The method for preparing a high-strength fire-resistant steel material for fire doors according to claim 1, characterized in that: The polyacrylate emulsion is prepared by the following process: Mix 1 / 2 of the emulsifier solution and the mixed monomer to obtain a pre-emulsion; Mix 1 / 10 of the pre-emulsion and the remaining emulsifier solution, add sodium bicarbonate and 1 / 2 of the initiator solution, heat to 78-82°C, stir and react until a blue phase appears, and keep warm for 10-20 minutes after the blue phase is obvious; add the remaining initiator and the remaining pre-emulsion, keep warm and react for 90-120 minutes; cool, adjust the pH of the system to 7-8, and sieve to obtain a polyacrylate emulsion.

7. The method for preparing a high-strength fire-resistant steel material for fire doors according to claim 1, characterized in that: The polyacrylate emulsion comprises the following components: by mass, 40 to 45 parts of mixed monomers, 0.2 to 0.5 parts of initiator, and 1.0 to 1.5 parts of emulsifier.

8. The method for preparing a high-strength fire-resistant steel material for fire doors according to claim 1, characterized in that: The composite monomer includes the following components: in parts by mass, 20 to 23 parts of n-butyl acrylate, 11 to 13 parts of methyl methacrylate, 5 to 7 parts of styrene, 1.5 to 2.5 parts of vinyltriethoxysilane, 1.5 to 2.5 parts of octamethylcyclotetrasiloxane, 1 to 3 parts of glycidyl methacrylate and 1 to 10 parts of a phosphorus-containing olefinic compound.

9. The method for preparing a high-strength fire-resistant steel material for fire doors according to claim 1, characterized in that: Phosphorus-containing olefinic compounds are prepared by the following process: (1) Tripolyphosphazene chloride, acetaminophen, and a catalyst are mixed in acetone, and the temperature is raised to 60-80°C under a nitrogen atmosphere, and the temperature is kept to react for 8-96 hours to obtain hexaacetylcyclotriphosphazene; (2) Hexaacetylcyclotriphosphazene, alcohol aqueous solution, and sodium hydroxide are mixed and refluxed at 70-75° C. for 4-36 hours to obtain hexaphenylaminocyclotriphosphazene; (3) Propylenebenzaldehyde and hexaphenylaminocyclotriphosphazene are mixed in N,N-dimethylformamide and reacted at 60-65°C for 30-60 min under nitrogen atmosphere; the temperature is lowered to 50±5°C, DOPO and triethylamine are added, and the temperature is raised to 80-85°C and the reaction is continued for 1-3 h to obtain a phosphorus-containing olefin compound.

10. The method for preparing high-strength fire-resistant steel for fire doors according to claim 1, characterized in that: The molar ratio of tripolyphosphazene chloride and acetaminophen is 1: (6.5-7.2); The mass ratio of anilinocyclotriphosphazene, propenylbenzaldehyde, and DOPO is 1:(1.1-1.2):(1.5-1.7).

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