Salen-based polyphosphazene p, n, si ternary hybrid flame retardant and fireproof coating

Abstract

The application discloses a Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant and fireproof coating, and belongs to the field of reactive halogen-free flame retardants. The Salen-PZN-Ni is subjected to one-pot reaction with IPTS and PMHS, P and Si elements with flame retardant properties are simultaneously introduced into the Salen-PZN-Ni, and a P, N, Si ternary hybrid flame retardant Salen-PZN-Ni-PMIP is generated, which has high efficient synergistic flame retardant properties. The Salen-PZN-Ni-PMIP has the characteristics of environment-friendly, insoluble in water and high compatibility with polymers as a new type of halogen-free flame retardant. The fireproof coating prepared by using the Salen-PZN-Ni-PMIP can resist hydrocarbon flame, has long fire resistance time, good substrate adhesion, and does not fall off, and the strength and toughness are significantly improved. The thick coating layer is not prone to cracking, and in the fireproof test, the carbon layer almost does not delaminate. The Salen-PZN-Ni-PMIP is carbonized into a carbon-rich skeleton at high temperature in the fireproof coating, has high carbon residue, can replace conventional ammonium polyphosphate and part of pentaerythritol, and reduces the addition amount of the flame retardant and the smoke release amount in the fireproof coating.

Description

Technical Field

[0001] This invention belongs to the field of reactive halogen-free flame retardants, and specifically relates to a Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant and fire-retardant coating. Background Technology

[0002] Fire-retardant coatings are a type of special functional coating that effectively prevents or delays the spread of fire. Compared with other fire-resistant materials, fire-retardant coatings have advantages such as easy application, low cost, and good heat insulation, and are widely used in steel structure buildings, cable protection, highway tunnels, airports, and many other places. Traditionally, fire-retardant coatings involve adding large amounts of flame retardants to achieve intumescent fire-retardant coatings with flame-retardant properties and minimal impact on the basic properties of the material. While halogenated flame retardants possess excellent flame-retardant properties, they produce large amounts of smoke, corrosive gases, and toxic substances during thermal decomposition and combustion, seriously endangering human health. Therefore, they are gradually being replaced by halogen-free, green flame retardants. Phosphorus-based flame retardants have come into view due to their high efficiency, halogen-free and environmentally friendly characteristics. Currently, the most commonly used flame retardant system on the market is an intumescent flame retardant system composed of ammonium polyphosphate, melamine and pentaerythritol. However, in production and construction, this intumescent flame retardant system has the following drawbacks: large addition amount, large smoke output, and significant lack of moisture absorption of the PO structure and ammonium salt groups in the ammonium polyphosphate structure. These defects directly affect the durability and weather resistance of fireproof coatings.

[0003] Furthermore, for hydrocarbon flames, thermosetting resins are typically chosen for fire-retardant coatings. Epoxy resins are the most widely used due to their excellent adhesion, hardness, chemical corrosion resistance, and salt spray resistance. Especially during a fire, they can withstand the impact of fire without easily peeling off, maintaining their fire-retardant properties. However, conventional nitrogen and phosphorus-based flame retardants have poor compatibility with epoxy resins and tend to migrate to the surface over time, thus losing their effectiveness. Moreover, the total design thickness of hydrocarbon fire-retardant coatings is typically 5-7 mm. At this thickness, the epoxy fire-retardant coating film is quite brittle and prone to cracking, splitting, and peeling. Summary of the Invention

[0004] The purpose of this invention is to address the problems of large amounts of various flame retardants added in existing intumescent fire-retardant coatings and insufficient moisture absorption of the PO structure and ammonium salt groups in the ammonium polyphosphate structure. This invention proposes a Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant and fire-retardant coating, which introduces phosphorus, nitrogen, and silicon—flame-retardant elements—into the same flame retardant, developing a novel flame retardant with highly efficient synergistic flame-retardant effects. Simultaneously, it solves the problems of large amounts of flame retardants added in existing intumescent fire-retardant coatings, high smoke production, and brittle paint film, which are prone to cracking, splitting, and peeling.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant, with the following structural formula:

[0007]

[0008] in,

[0009]

[0010] This invention also provides a method for preparing the above-mentioned Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant, comprising:

[0011] Salen-PZN-Ni was mixed with solvent 1 and ultrasonically stirred. Propyl ethoxysilane isocyanate (IPTS) was added to react, and then a catalyst was added. Polymethylhydrosiloxane (PMHS) was added dropwise to react again. The synthesized product was subjected to vacuum distillation to remove solvent 1. The product was washed, centrifuged, and dried to obtain Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant (Salen-PZN-Ni-PMIP).

[0012] As a further improvement of the present invention, the ratio of Salen-PZN-Ni to propyl ethoxysilane is 1 mol: 30 mL, the molar ratio of polymethylhydrosiloxane (PMHS) to propyl ethoxysilane (IPTS) is 1: 1.1 to 1.3, and the mass concentration of the catalyst is 60 to 80 ppm.

[0013] As a further improvement of the present invention, the solvent 1 is at least one selected from benzene, toluene, xylene, tetrahydrofuran, acetonitrile, acetone, methanol, ethanol, and isopropanol.

[0014] As a further improvement of the present invention, the catalyst is a catalyst containing Pt and / or Pd.

[0015] As a further improvement of the present invention, the ultrasonic stirring time is 30 minutes.

[0016] As a further improvement of the present invention, propyl ethoxysilane isocyanate is added and the mixture is heated to 60°C for 9 hours.

[0017] As a further improvement of the present invention, polymethylhydrosiloxane was added dropwise and then heated to 100°C for 8 hours.

[0018] As a further improvement of the present invention, the preparation steps of the Salen-PZN-Ni are as follows:

[0019] Step 1: Mix dihydroxybenzaldehyde, solvent 2, and o-phenylenediamine, and stir the mixture at 30°C for 12 hours under inert gas protection. Filter to obtain a yellow precipitate. The yellow precipitate is then subjected to vacuum filtration, washing with solvent 2, and vacuum drying to obtain Salen.

[0020] Step 2: Mix Salen, acid-binding agent, and solvent 3, and add hexachlorocyclotriphosphazene dropwise at 30°C under inert gas protection and stir for 6 hours. After evaporating solvent 3 under reduced pressure, extract with dichloromethane 3 times in sequence, wash the organic phase with deionized water 3 times, and then evaporate dichloromethane under reduced pressure to obtain a yellow liquid. After separation and purification, Salen-PZN is obtained.

[0021] Step 3: Mix Salen-PZN and solvent 4, and add nickel nitrate hexahydrate aqueous solution dropwise. Stir at 30°C for 4 hours under inert gas protection. The precipitate is then subjected to vacuum filtration, washing with solvent 4, and vacuum drying to obtain Salen-PZN-Ni.

[0022] Preferably, in steps 1-3, the molar ratio of o-phenylenediamine, dihydroxybenzaldehyde, and hexachlorocyclotriphosphazene is 1:2.0-2.3:0.3-1; the molar ratio of hexachlorocyclotriphosphazene to the acid-binding agent is 1:1.0-2.0; and the molar ratio of Salen-PZN to nickel nitrate hexahydrate is 1:1.0-1.3.

[0023] Preferably, in step 1, the solvent 2 is at least one of pentaerythritol, methanol, and ethanol.

[0024] Preferably, in steps 1 to 3, the inert gas is at least one of argon, helium, and nitrogen.

[0025] Preferably, in step 2, the acid-binding agent is at least one of pyridine, sodium hydroxide, potassium hydroxide, triethylamine, sodium carbonate, and potassium carbonate.

[0026] Preferably, in step 2, the solvent 3 is at least one of benzene, toluene, xylene, dichloromethane, chloroform, tetrahydrofuran, acetone, and N,N-dimethylformamide.

[0027] Preferably, in step 3, the solvent 4 is at least one selected from benzene, toluene, xylene, dichloromethane, chloroform, tetrahydrofuran, acetonitrile, acetone, methanol, ethanol, and isopropanol.

[0028] The present invention also provides a high-efficiency intumescent fireproof coating for steel structures, comprising component A and component B, wherein the mass ratio of component A to component B is 4 to 6:1;

[0029] Component A comprises the following components by weight: 25-30 parts epoxy resin, 2-5 parts melamine, 4-8 parts pentaerythritol, 15-20 parts synergistic flame retardant, 2-4 parts refractory fiber, 10-15 parts pigments and fillers, 1.5-2.5 parts additives, 0.5-4 parts toughening agent a, and 10-30 parts organic solvent a; wherein the synergistic flame retardant is a Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant.

[0030] Component B comprises the following components by weight: 40-50 parts curing agent, 3-5 parts accelerator, 1-3 parts toughening agent b, and 40-50 parts organic solvent b.

[0031] As a further improvement of the present invention, the epoxy value of the epoxy resin is 0.18 to 0.55, and the epoxy resin is one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic modified epoxy resin, preferably a bisphenol A type epoxy resin with moderate cost and performance.

[0032] As a further improvement of the present invention, the refractory fiber is one or more of the following: aluminosilicate fiber, sepiolite fiber, alumina fiber, basalt fiber, and high silica-oxygen fiber. The diameter of the refractory fiber is 7-10 μm and the aspect ratio is 10:1-15:1.

[0033] As a further improvement of the present invention, the pigment or filler is at least one of titanium dioxide, kaolin, aluminum hydroxide, magnesium hydroxide, and talc.

[0034] As a further improvement of the present invention, the toughening agent a is one or more of nano-silica, nano-titanium dioxide, and resorcinol diglycidyl ether; the toughening agent b is at least one of nano-silica, nano-titanium dioxide, and resorcinol diglycidyl ether.

[0035] As a further improvement of the present invention, the additive is at least one of dispersant, defoamer, leveling agent, viscosity reducer, and antisettling agent.

[0036] As a further improvement of the present invention, the organic solvent a is one or more of xylene, butyl acetate, butanol, ethyl acetate, propylene glycol methyl ether, and propylene glycol methyl ether acetate; and the organic solvent b is at least one of xylene, butyl acetate, butanol, ethyl acetate, propylene glycol methyl ether, and propylene glycol methyl ether acetate.

[0037] As a further improvement of the present invention, the curing agent is at least one selected from polyamide, phenolic amine, aromatic amine, and alicyclic amine.

[0038] As a further improvement of the present invention, the accelerator is at least one selected from triethanolamine, diethanolamine, ethanolamine, tri-(dimethylaminomethyl)phenol (DMP30), and triethylamine.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] 1. This invention involves a one-pot reaction of Salen-PZN-Ni with (3-isocyanopropyl)triethoxysilane (IPTS) and polymethylhydrosiloxane (PMHS) to simultaneously introduce phosphorus (P) and silicon (Si) elements with flame-retardant properties into Salen-PZN-Ni, generating a P, N, Si ternary hybrid flame retardant, Salen-PZN-Ni-PMIP, which exhibits highly efficient synergistic flame-retardant properties.

[0041] 2. The high-efficiency intumescent fire-retardant coating for steel structures containing Salen-PZN-Ni-PMIP prepared by this invention can withstand hydrocarbon flames when applied to steel structures, with a maximum fire resistance time of 120 minutes. The char layer after combustion is dense and continuous. Compared with fire-retardant coatings made from existing flame retardants, it has better adhesion to the substrate, does not peel off, and has significantly improved strength and toughness. Thick coatings are less prone to cracking, and the char layer hardly delaminates during fire resistance tests.

[0042] 3. The Salen-PZN-Ni-PMIP prepared by this invention, as a novel halogen-free flame retardant, has the characteristics of being environmentally friendly, insoluble in water, and highly compatible with polymers, thus avoiding the migration and precipitation of flame retardants. At the same time, it is carbonized at high temperature in fire-retardant coatings into a carbon-rich skeleton with a high residual carbon content, which can replace conventional ammonium polyphosphate and part of pentaerythritol, reducing the amount of flame retardant added and the amount of smoke released in fire-retardant coatings. Attached Figure Description

[0043] Figure 1 This is a process route diagram for the synthesis of Salen-PZN-Ni-PMIP in this invention;

[0044] Figure 2 The infrared spectra of Salen-PZN-Ni, IPTS, PMHS, and Salen-PZN-Ni-PMIP in Example 1 of this invention;

[0045] Figure 3 The images shown are electron microscope images of Salen-PZN-Ni and Salen-PZN-Ni-PMIP in Embodiment 1 of the present invention. (a) and (c) are Salen-PZN-Ni; (b) and (d) are Salen-PZN-Ni-PMIP. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] Please see Figure 1 As shown, the present invention provides a method for synthesizing Salen-PZN-Ni, the steps of which are as follows:

[0048] Step 1: Mix dihydroxybenzaldehyde, solvent 2, and o-phenylenediamine, and stir the mixture at 30°C for 12 hours under inert gas protection. Filter to obtain a yellow precipitate. The yellow precipitate is then subjected to vacuum filtration, washing with solvent 2, and vacuum drying to obtain Salen.

[0049] Step 2: Mix Salen, acid-binding agent, and solvent 3, and add hexachlorocyclotriphosphazene dropwise at 30°C under inert gas protection and stir for 6 hours. After evaporating solvent 3 under reduced pressure, extract with dichloromethane 3 times in sequence, wash the organic phase with deionized water 3 times, and then evaporate dichloromethane under reduced pressure to obtain a yellow liquid. After separation and purification, Salen-PZN is obtained.

[0050] Step 3: Mix Salen-PZN and solvent 4, and add nickel nitrate hexahydrate aqueous solution dropwise. Stir at 30°C for 4 hours under inert gas protection. The precipitate is then subjected to vacuum filtration, washing with solvent 4, and vacuum drying to obtain Salen-PZN-Ni.

[0051] Preferably, in steps 1-3, the molar ratio of o-phenylenediamine, dihydroxybenzaldehyde, and hexachlorocyclotriphosphazene is 1:2.0-2.3:0.3-1; the molar ratio of hexachlorocyclotriphosphazene to the acid-binding agent is 1:1.0-2.0; and the molar ratio of Salen-PZN to nickel nitrate hexahydrate is 1:1.0-1.3.

[0052] Specifically, solvent 2 is at least one of pentaerythritol, methanol, and ethanol; the inert gas is at least one of argon, helium, and nitrogen; the acid-binding agent is at least one of pyridine, sodium hydroxide, potassium hydroxide, triethylamine, sodium carbonate, and potassium carbonate; solvent 3 is at least one of benzene, toluene, xylene, dichloromethane, chloroform, tetrahydrofuran, acetone, and N,N-dimethylformamide; and solvent 4 is at least one of benzene, toluene, xylene, dichloromethane, chloroform, tetrahydrofuran, acetonitrile, acetone, methanol, ethanol, and isopropanol.

[0053] Please continue reading. Figure 1As shown, the present invention provides a method for synthesizing Salen-PZN-Ni-PMIP, specifically using a one-pot reaction method. Salen-PZN-Ni is mixed with solvent 1, ultrasonically stirred for 30 min, propyl ethoxysilane isocyanate (IPTS) is added, and the reaction is carried out at 60°C for 9 h. A catalyst is added, and polymethylhydrosiloxane (PMHS) is added dropwise. After stirring at 100°C for 8 h, the synthesized product is subjected to vacuum distillation to remove solvent 1, washed, centrifuged, and dried to obtain Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant (Salen-PZN-Ni-PMIP).

[0054] Specifically, the ratio of Salen-PZN-Ni to propyl ethoxysilane is 1 mol: 30 mL, the molar ratio of polymethylhydrosiloxane (PMHS) to propyl ethoxysilane (IPTS) is 1:1.1–1.3, and the mass concentration of the catalyst is 60–80 ppm; the solvent 1 is at least one selected from benzene, toluene, xylene, tetrahydrofuran, acetonitrile, acetone, methanol, ethanol, and isopropanol; and the catalyst is a Pt and / or Pd-containing catalyst.

[0055] Example 1

[0056] In a reactor equipped with a stirrer, heater, and temperature control device, 2.0 mol of 2,4-dihydroxybenzaldehyde, ethanol, and 1.0 mol of o-phenylenediamine were added. After the addition was complete, the mixture was stirred at 30°C for 12 h under nitrogen protection. The yellow precipitate was filtered under reduced pressure, washed with ethanol, and dried to obtain the intermediate product Salen. In a reaction vessel equipped with a stirrer, heater, and temperature control device, 1.0 mol of Salen, 0.45 mol of triethylamine, and dichloromethane were added. At 0°C, 0.3 mol of hexachlorocyclotriphosphazene (HCCP) was added dropwise to the system. After the addition was complete, the mixture was stirred at 30°C for 6 h under nitrogen protection. The dichloromethane was evaporated to dryness under reduced pressure, and the product was extracted three times with dichloromethane. The organic phase was washed three times with deionized water, and the dichloromethane was evaporated to dryness under reduced pressure to obtain a yellow liquid. The product was purified by column chromatography with a volume ratio of petroleum ether:ethyl acetate = 1:1 or a volume ratio of dichloromethane:methanol = 20:1. The yellow liquid was Salen-PZN. 1.0 mol Salen-PZN and ethanol were added to a reaction vessel equipped with a stirrer, heater, and temperature control device. 1.1 mol Ni(NO3)2·6H2O aqueous solution was added dropwise to the system. The reaction was carried out under inert gas protection at 30°C with stirring for 4 h. After vacuum filtration, washing with ethanol, and drying, Salen-PZN-Ni was obtained. 1 mol Salen-PZN-Ni and toluene were added to a reaction vessel equipped with a stirrer, heater, and temperature control device. 30 ml of a mixture of propyl ethoxysilane isocyanate and toluene was added dropwise. After stirring at 60°C for 9 h, chloroplatinic acid and 1 g of polymethylhydrosiloxane were added. The mixture was stirred at 100°C for 8 h. The synthesized product was then subjected to vacuum distillation, washing, centrifugation, and drying to obtain the product Salen-PZN-Ni-PMIP.

[0057] The Salen-PZN-Ni, IPTS, PMHS, and Salen-PZN-Ni-PMIP obtained in this embodiment were irradiated using an infrared spectrometer, and the resulting infrared spectra are shown below. Figure 2 As shown; the Salen-PZN-Ni and Salen-PZN-Ni-PMIP obtained in this embodiment were scanned using a scanning electron microscope (SEM), and the resulting SEM images are shown below. Figure 3 As shown.

[0058] Example 2

[0059] 2.1 mol of 2,4-dihydroxybenzaldehyde, ethanol, and 1.0 mol of o-phenylenediamine were added to a reactor equipped with a stirrer, heater, and temperature control device. After the addition was complete, the mixture was stirred at 30°C for 12 h under nitrogen protection. The yellow precipitate was filtered under reduced pressure, washed with ethanol, and dried to obtain the intermediate product Salen. 1.0 mol of Salen, 0.8 mol of triethylamine, and dichloromethane were added to a reaction vessel equipped with a stirrer, heater, and temperature control device. 0.5 mol of hexachlorocyclotriphosphazene (HCCP) was added dropwise to the system at 0°C. After the addition was complete, the mixture was stirred at 30°C for 6 h under nitrogen protection. The dichloromethane was evaporated to dryness under reduced pressure, and the product was extracted three times with dichloromethane. The organic phase was washed three times with deionized water, and the dichloromethane was evaporated to dryness under reduced pressure to obtain a yellow liquid. The product was purified by column chromatography with a volume ratio of petroleum ether:ethyl acetate = 1:1 or a volume ratio of dichloromethane:methanol = 20:1. The yellow liquid was Salen-PZN. 1.0 mol Salen-PZN and ethanol were added to a reaction vessel equipped with a stirrer, heater, and temperature control device. 1.2 mol Ni(NO3)2·6H2O aqueous solution was added dropwise to the system. The reaction was carried out under inert gas protection at 30°C with stirring for 4 h. After vacuum filtration, washing with ethanol, and drying, Salen-PZN-Ni was obtained. 1 mol Salen-PZN-Ni and toluene were added to a reaction vessel equipped with a stirrer, heater, and temperature control device. 30 ml of a mixture of propyl ethoxysilane isocyanate and toluene was added dropwise. After stirring at 60°C for 9 h, chloroplatinic acid and 1.1 g of polymethylhydrosiloxane were added. The mixture was stirred at 100°C for 8 h. The synthesized product was then subjected to vacuum distillation, washing, centrifugation, and drying to obtain the product Salen-PZN-Ni-PMIP.

[0060] Example 3

[0061] 2.3 mol of 2,4-dihydroxybenzaldehyde, ethanol, and 1.0 mol of o-phenylenediamine were added to a reactor equipped with a stirrer, heater, and temperature control device. After the addition was complete, the mixture was stirred at 30°C for 12 h under nitrogen protection. The yellow precipitate was filtered under reduced pressure, washed with ethanol, and dried to obtain the intermediate product Salen. 1.0 mol of Salen, 2.0 mol of triethylamine, and dichloromethane were added to a reaction vessel equipped with a stirrer, heater, and temperature control device. 1 mol of hexachlorocyclotriphosphazene (HCCP) was added dropwise to the system at 0°C. After the addition was complete, the mixture was stirred at 30°C for 6 h under nitrogen protection. The dichloromethane was evaporated to dryness under reduced pressure, and the product was extracted three times with dichloromethane. The organic phase was washed three times with deionized water, and the dichloromethane was evaporated to dryness under reduced pressure to obtain a yellow liquid. The product was purified by column chromatography with a volume ratio of petroleum ether:ethyl acetate = 1:1 or a volume ratio of dichloromethane:methanol = 20:1. The yellow liquid was Salen-PZN. 1.0 mol Salen-PZN and ethanol were added to a reaction vessel equipped with a stirrer, heater, and temperature control device. 1.3 mol Ni(NO3)2·6H2O aqueous solution was added dropwise to the system. The reaction was carried out under inert gas protection at 30°C with stirring for 4 h. After vacuum filtration, washing with ethanol, and drying, Salen-PZN-Ni was obtained. 1 mol Salen-PZN-Ni and toluene were added to a reaction vessel equipped with a stirrer, heater, and temperature control device. 30 ml of a mixture of propyl ethoxysilane isocyanate and toluene was added dropwise. After stirring at 60°C for 9 h, chloroplatinic acid and 1.2 g of polymethylhydrosiloxane were added. The mixture was stirred at 100°C for 8 h. The synthesized product was then subjected to vacuum distillation, washing, centrifugation, and drying to obtain the product Salen-PZN-Ni-PMIP.

[0062] Example 4

[0063] The high-efficiency intumescent fireproof coating for steel structures in this embodiment comprises the following raw materials in parts by weight:

[0064] Component A: 30 parts E51 epoxy resin, 5 parts melamine, 8 parts pentaerythritol, 18 parts synergistic flame retardant, 2 parts alumina fiber, 10 parts titanium dioxide, 0.5 parts dispersant, 0.5 parts defoamer, 0.5 parts anti-settling agent, 0.5 parts leveling agent, 0.5 parts toughening agent nano silica, 24.5 parts organic solvent;

[0065] Component B: 40 parts polyamide curing agent, 3 parts DMP30 accelerator, 1 part resorcinol diglycidyl ether, and 56 parts organic solvent.

[0066] Component A and Component B are mixed in a weight ratio of 5:1 to form the high-efficiency intumescent fireproof coating for steel structures in this embodiment.

[0067] Example 5

[0068] The high-efficiency intumescent fireproof coating for steel structures in this embodiment comprises the following raw materials in parts by weight:

[0069] Component A: 28 parts E20 epoxy resin, 2 parts melamine, 6 parts pentaerythritol, 15 parts synergistic flame retardant, 3 parts aluminum silicate fiber, 10 parts titanium dioxide, 5 parts aluminum hydroxide, 0.5 parts dispersant, 0.4 parts defoamer, 0.4 parts anti-settling agent, 0.3 parts leveling agent, 2 parts toughening agent titanium dioxide, 27.4 parts organic solvent;

[0070] Component B: 45 parts aromatic amine curing agent, 4 parts triethanolamine accelerator, 2 parts resorcinol diglycidyl ether, and 49 parts organic solvent.

[0071] Component A and Component B are mixed in a weight ratio of 4:1 to form the high-efficiency intumescent fireproof coating for steel structures in this embodiment.

[0072] Example 6

[0073] The high-efficiency intumescent fireproof coating for steel structures in this embodiment comprises the following raw materials in parts by weight:

[0074] Component A: 25 parts phenolic epoxy resin, 4 parts melamine, 4 parts pentaerythritol, 20 parts synergistic flame retardant, 4 parts high-silica fiber, 10 parts titanium dioxide, 2 parts kaolin, 0.5 parts dispersant, 0.4 parts defoamer, 0.6 parts anti-settling agent, 0.2 parts leveling agent, 0.5 parts viscosity reducer, 2.5 parts resorcinol diglycidyl ether, 26.3 parts organic solvent;

[0075] Component B: 50 parts of alicyclic amine curing agent, 5 parts of DMP30 accelerator, 4 parts of resorcinol diglycidyl ether, and 42 parts of organic solvent.

[0076] Component A and Component B are mixed in a weight ratio of 6:1 to form the high-efficiency intumescent fireproof coating for steel structures in this embodiment.

[0077] Comparative Example 1

[0078] An intumescent fire-retardant coating for steel structures comprises the following raw materials in parts by weight:

[0079] The composition includes 28 parts bisphenol A epoxy resin, 8 parts melamine, 9 parts pentaerythritol, 22 parts ammonium polyphosphate, 10 parts pigments and fillers, 5.5 parts additives, 6 parts reactive diluent, and 11.5 parts organic solvent.

[0080] Component B: 55 parts curing agent, 2 parts accelerator, 4 parts refractory fiber, 2 parts additives, and 37 parts organic solvent.

[0081] Component A and Component B are mixed in a weight ratio of 6:1.

[0082] Comparative Example 2

[0083] An intumescent fire-retardant coating for steel structures comprises the following raw materials in parts by weight:

[0084] 26 parts phenolic epoxy resin, 8 parts melamine, 6 parts pentaerythritol, 10 parts synergistic flame retardant, 5 parts refractory fiber, 15 parts titanium dioxide, 2 parts talc, 0.4 parts dispersant, 0.4 parts defoamer, 0.5 parts anti-settling agent, 0.1 parts leveling agent, and 26.6 parts organic solvent;

[0085] Component B: 50 parts curing agent, 5 parts accelerator, and 45 parts organic solvent.

[0086] Component A and Component B are mixed in a weight ratio of 6:1.

[0087] Experimental Example

[0088] (1) Coating performance test

[0089] The film performance of the samples from Examples 4 to 6 and Comparative Examples 1 to 2 was tested according to GB14907-2018, and the specific test results are shown in the table below.

[0090]

[0091]

[0092] As can be seen from the table above, both the existing intumescent fireproof coatings for steel structures and the high-efficiency intumescent fireproof coating for steel structures containing Salen-PZN-Ni-PMIP flame retardant of the present invention have a smooth and flat film appearance without bubbling, wrinkling, or cracking. However, the high-efficiency intumescent fireproof coating for steel structures containing Salen-PZN-Ni-PMIP of the present invention has stronger substrate adhesion, no cracks during the initial drying crack resistance test, and better overall flexibility and compatibility of the coating.

[0093] (2) Fire resistance test

[0094] The fire resistance performance of samples from Examples 4 to 6 and Comparative Examples 1 to 2 was tested according to GB14907-2018 standard. The specific test results are shown in the table below.

[0095] Example 4 120min Continuous, dense, hard 8.0 Example 5 118min Continuous, dense, hard 7.6 Example 6 124min Continuous, dense, hard 8.6 Comparative Example 1 72min Loose, porous, soft 12.0 Comparative Example 2 92min Loose, porous, hard 5.1

[0096] As can be seen from the table above, the high-efficiency intumescent steel structure fireproof coatings containing Salen-PZN-Ni-PMIP flame retardant provided in Examples 4 to 6 have a continuous and dense char layer, which is hard and strong, and has a high degree of expansion, thus having a high fire resistance time. Although the char layer expansion height of Comparative Example 1 is high, the char layer has large pores, poor continuity, and is mostly loose, resulting in poor fire resistance. Comparative Example 2 contains 10% Salen-PZN-Ni and also contains a high-efficiency flame retardant with high nitrogen and phosphorus content, but the overall addition amount is insufficient. At the same time, it has poor compatibility with the resin base, the char layer is loose and discontinuous, and the fire resistance is insufficient.

[0097] Flame retardant performance test

[0098] The flame retardant properties of the flame retardant materials were tested using a cone calorimeter according to ISO 5660-1 standard. The specific test results are shown in the table below.

[0099] Comparative Example 1 Ammonium polyphosphate-pentaerythritol-melamine system 90.6 20.4 V-1 Example 4 15% Salen-PZN-Ni-PMIP (Example 1) 84.9 26.1 V-0 Example 5 18% Salen-PZN-Ni-PMIP (Example 2) 84.5 26.8 V-0 Example 6 20% Salen-PZN-Ni-PMIP (Example 3) 85.5 25.3 V-0 Comparative Example 2 10% Salen-PZN-Ni 88.3 24.7 V-1

[0100] By comparing the components of Examples 4-6 and Comparative Examples 1-2, and referring to the table above, it can be seen that the high-efficiency intumescent fire-retardant coating for steel structures containing Salen-PZN-Ni-PMIP flame retardant provided by the present invention has a lower amount of flame retardant added, while the total heat release (THR) is reduced more significantly. The limiting oxygen index (LOI, according to standard: ASTM D2863-97) and vertical flammability rating (UL-94, according to standard: ASTM D3801) test results are also significantly improved compared with Comparative Examples 1 and 2. This indicates that after adding synergistic flame retardants, a lower amount of flame retardant system can achieve a higher flame retardant effect.

[0101] 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 and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant, characterized in that, The structural formula is as follows: ； in, ; ， 。 2. A method for preparing the Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant as described in claim 1, characterized in that, include: Salen-PZN-Ni was mixed with solvent 1 and ultrasonically stirred. Propyl ethoxysilane isocyanate was added to react, and then a catalyst was added. Polymethylhydrosiloxane was added dropwise to react again. The synthesized product was subjected to vacuum distillation to remove solvent 1. The product was washed, centrifuged, and dried to obtain Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant.

3. The preparation method according to claim 2, characterized in that: The ratio of Salen-PZN-Ni to propyl ethoxysilane is 1 mol: 30 mL, the molar ratio of polymethylhydrosiloxane to propyl ethoxysilane is 1:1.1 to 1.3, and the mass concentration of the catalyst is 60 to 80 ppm.

4. The preparation method according to claim 2, characterized in that: The solvent 1 is at least one of benzene, toluene, xylene, tetrahydrofuran, acetonitrile, acetone, methanol, ethanol, and isopropanol; the catalyst is a catalyst containing Pt and / or Pd.

5. The preparation method according to claim 2, characterized in that: The ultrasonic stirring time was 30 min. After adding propyl ethoxysilane isocyanate, the mixture was heated to 60°C and reacted for 9 h. After adding polymethylhydrosiloxane dropwise, the mixture was heated to 100°C and reacted for 8 h.

6. The preparation method according to claim 2, characterized in that, The preparation steps of the Salen-PZN-Ni are as follows: Step 1: Mix dihydroxybenzaldehyde, solvent 2, and o-phenylenediamine, and stir the mixture at 30°C for 12 hours under inert gas protection. Filter to obtain a yellow precipitate. The yellow precipitate is then subjected to vacuum filtration, washing with solvent 2, and vacuum drying to obtain Salen. Step 2: Mix Salen, acid-binding agent, and solvent 3, and add hexachlorocyclotriphosphazene dropwise at 30°C under inert gas protection with stirring for 6 h. After evaporating solvent 3 under reduced pressure, extract with dichloromethane three times, wash the organic phase three times with deionized water, and then evaporate dichloromethane under reduced pressure to obtain a yellow liquid. After separation and purification, Salen-PZN is obtained. Step 3: Mix Salen-PZN and solvent 4, and add nickel nitrate hexahydrate aqueous solution dropwise. Stir at 30°C for 4 h under inert gas protection. The precipitate is then subjected to vacuum filtration, washing with solvent 4, and vacuum drying to obtain Salen-PZN-Ni.

7. The preparation method according to claim 6, characterized in that: In steps 1-3, the molar ratio of o-phenylenediamine, dihydroxybenzaldehyde, and hexachlorocyclotriphosphazene is 1:2.0-2.3:0.3-1; the molar ratio of hexachlorocyclotriphosphazene to the acid-binding agent is 1:1.0-2.0; the molar ratio of Salen-PZN to nickel nitrate hexahydrate is 1:1.0-1.3; solvent 2 is at least one of methanol and ethanol; the inert gas is at least one of argon, helium, and nitrogen; the acid-binding agent is at least one of pyridine, sodium hydroxide, potassium hydroxide, triethylamine, sodium carbonate, and potassium carbonate; solvent 3 is at least one of benzene, toluene, xylene, dichloromethane, chloroform, tetrahydrofuran, acetone, and N,N-dimethylformamide; solvent 4 is at least one of benzene, toluene, xylene, dichloromethane, chloroform, tetrahydrofuran, acetonitrile, acetone, methanol, ethanol, and isopropanol.

8. A high-efficiency intumescent fireproof coating for steel structures, characterized in that: It includes component A and component B, wherein the mass ratio of component A to component B is 4 to 6:1; Component A comprises, by weight, the following components: 25-30 parts epoxy resin, 2-5 parts melamine, 4-8 parts pentaerythritol, 15-20 parts synergistic flame retardant, 2-4 parts refractory fiber, 10-15 parts pigments and fillers, 1.5-2.5 parts additives, 0.5-4 parts toughening agent a, and 10-30 parts organic solvent a; wherein the synergistic flame retardant is the Salen-based polyphosphazene P, N, Si ternary hybrid flame retardant as described in claim 1. Component B comprises the following components by weight: 40-50 parts curing agent, 3-5 parts accelerator, 1-3 parts toughening agent b, and 40-50 parts organic solvent b; The refractory fiber is one or more of aluminosilicate fiber, sepiolite fiber, alumina fiber, basalt fiber, and high-silica fiber, with a diameter of 7-10 μm and an aspect ratio of 10:1-15:1; the pigment and filler is at least one of titanium dioxide, kaolin, aluminum hydroxide, magnesium hydroxide, and talc; toughening agent a is one or more of nano-silica, nano-titanium dioxide, and resorcinol diglycidyl ether; toughening agent b is at least one of nano-silica, nano-titanium dioxide, and resorcinol diglycidyl ether; the additives... The organic solvent a is at least one of the following: dispersant, defoamer, leveling agent, viscosity reducer, and anti-settling agent; the organic solvent a is one or more of xylene, butyl acetate, butanol, ethyl acetate, propylene glycol methyl ether, and propylene glycol methyl ether acetate; the organic solvent b is at least one of xylene, butyl acetate, butanol, ethyl acetate, propylene glycol methyl ether, and propylene glycol methyl ether acetate; the curing agent is at least one of polyamide, phenolic amine, aromatic amine, and alicyclic amine; and the accelerator is at least one of triethanolamine, diethanolamine, ethanolamine, tri-(dimethylaminomethyl)phenol, and triethylamine.

9. The high-efficiency intumescent fireproof coating for steel structures according to claim 8, characterized in that: The epoxy value of the epoxy resin is 0.18 to 0.55, and the epoxy resin is one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and phenolic modified epoxy resin.

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