A preparation method of a bimetallic prussian blue complex boron nitride-based fireproof coating

Abstract

This invention discloses a method for preparing a bimetallic Prussian blue complex boron nitride-based fire-retardant coating. The preparation steps are as follows: (1) preparation of the base material; (2) BN / PCP@PBA composite flame retardant; (3) preparation of the bimetallic Prussian blue complex boron nitride-based fire-retardant coating. This invention first deposits hexachlorocyclotriphosphide and p-phenylenediamine on the surface of boron nitride through polymerization reaction, giving the surface of boron nitride abundant N and P flame-retardant functional groups; then, Co-Fe / PBA nanoparticles with catalytic carbonization function are uniformly loaded onto the surface of BN, and a novel composite flame retardant (BN / PCP@PBA) with high barrier properties and catalytic carbonization function is successfully prepared. Then, the BN / PCP@PBA composite flame retardant is added to the epoxy resin matrix, and an ultra-thin epoxy intumescent fire-retardant coating with good fire resistance and smoke suppression effect is successfully prepared.

Description

Technical Field

[0001] This invention belongs to the field of preparation of water-based ultrathin epoxy intumescent fire-retardant coatings, specifically relating to a method for preparing a bimetallic Prussian blue complex boron nitride-based fire-retardant coating. Background Technology

[0002] Intumescent fire-retardant coatings consist of resin, curing agent, and intumescent components (carbon source, acid source, and gas source). At high temperatures, these three intumescent components work together to produce an expanded porous carbon layer that adheres to the substrate surface, thus protecting the steel substrate. Due to its excellent fire-retardant performance and cost-effectiveness, it is considered an effective means of protecting steel substrates. In recent years, due to stringent environmental protection requirements, the polymer components in intumescent fire-retardant coatings have shifted from solvent-based to water-based, with water-based epoxy resin (EP) gaining popularity due to its excellent adhesion, mechanical properties, and chemical stability. It has attracted widespread attention; unfortunately, the strength and thermal insulation performance of the residual char layer in pure epoxy intumescent fire-retardant coatings are limited, resulting in weak protection for steel; however, by adding some multifunctional inorganic nano-flame retardant materials (such as graphene, carbon nanotubes, layered bimetallic hydroxides, etc.), the flame retardant ability of polymers can be effectively improved; boron nitride (BN) is a nanomaterial with a two-dimensional layered structure, mainly composed of B and N atoms; due to its excellent barrier ability, thermal stability and oxidation resistance, it is considered a very promising inorganic nano-flame retardant. Summary of the Invention

[0003] Prussian blue complex (PBA), as a cubic metal-organic framework, possesses advantages such as structural stability, simple preparation, and low cost. Furthermore, its structure contains abundant transition metal elements, playing a crucial role in the formation of residual carbon, thus making it a highly promising inorganic flame retardant material. However, the limited size of PBA particles in polymers leads to poor barrier efficiency against external flames and heat. Therefore, combining PBA with multifunctional nanomaterials possessing high barrier properties is particularly important for further improving the fire safety of polymers. This invention first utilizes a polymerization reaction... Hexachlorocyclotriphosphide (HCCP) and p-phenylenediamine (p-PDA) were deposited on the surface of boron nitride (BN) to endow the surface of boron nitride with abundant N and P flame-retardant functional groups. Then, Co-Fe / PBA nanoparticles with catalytic carbonization were uniformly loaded onto the BN surface to successfully prepare a novel composite flame retardant (BN / PCP@PBA) with high barrier properties and catalytic carbonization function. Then, the novel composite flame retardant (BN / PCP@PBA) was added to an epoxy resin matrix to successfully prepare an ultra-thin epoxy intumescent fireproof coating with good fire resistance and smoke suppression effect.

[0004] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problems is as follows.

[0005] A method for preparing a bimetallic Prussian blue complex boron nitride-based fire-retardant coating includes the following steps.

[0006] 1. Preparation of base material.

[0007] Weigh out waterborne epoxy resin (EP), curing agent, and expansion system and stir until uniform to obtain a uniformly mixed base material, wherein the expansion system includes polyphosphate (APP), pentaerythritol (PER), and melamine (MEL).

[0008] 2. Preparation of BN / PCP@PBA composite flame retardant.

[0009] (1) Preparation process of BN / PCP: BN was ultrasonically dispersed in 100 mL of tetrahydrofuran (THF) solvent; then, 10 mL of triethylamine as acid acceptor and p-phenylenediamine as reaction monomer were added to the BN dispersion and stirred for 20 minutes; subsequently, 10 mL of hexachlorocyclophosphamide THF solution was added to the BN dispersion and reacted at 60 °C for 6 hours; finally, the obtained precipitate was washed 3-4 times with THF and hot deionized water, and finally vacuum dried at 80 °C for 12 hours to obtain BN / PCP hybrid.

[0010] (2) Preparation process of BN / PCP@PBA composite flame retardant: The BN / PCP hybrid was ultrasonically dispersed in 100 mL of water; cobalt nitrate hexahydrate and sodium citrate were dissolved in the BN / PCP dispersion and magnetically stirred for 10 minutes; then, 10 mL of an aqueous solution containing K3[Fe(CN)6] was added to the BN / PCP mixture and stirred for 12 hours; finally, the obtained product was repeatedly washed three times by centrifugation with pure water to obtain the BN / PCP@PBA composite flame retardant. The specific preparation diagram is shown below. Figure 1 As shown.

[0011] 3. Preparation of bimetallic Prussian blue complex boron nitride-based fire-retardant coating.

[0012] Weigh out the BN / PCP@PBA composite flame retardant and mix it with the base material. Stir it evenly with mechanical stirring to form a uniform coating system. Then, brush the uniformly mixed BN / PCP@PBA-based water-based intumescent fire retardant coating onto the surface of a steel sheet with a pretreatment grade of Sa2. After brushing, cure at room temperature for 7 days to obtain a bimetallic Prussian blue complex boron nitride-based fire retardant coating.

[0013] Furthermore, in step 1, the mass ratio of epoxy resin to the expansion system is 1:1-1.2.

[0014] Furthermore, in step 1, the mass ratio of epoxy resin to curing agent is 2:1-1.2.

[0015] Furthermore, the curing agent in step 1 can be ethylenediamine, diethylenetriamine, or triethylenetetramine.

[0016] Furthermore, in step 1, the ratio of polyphosphate, pentaerythritol, and melamine is 5.5-6.5:2.5-3.5:1-1.2.

[0017] Furthermore, in step 2(1), the mass ratio of BN to p-phenylenediamine is 1:4-6.

[0018] Furthermore, in step 2(1), the mass-to-volume ratio (g / mL) of p-phenylenediamine to triethylamine is 1:5-10.

[0019] Furthermore, in step 2(1), the mass-volume concentration of the hexachlorocyclophosphamide THF solution is 0.15-0.2 g / mL.

[0020] Furthermore, in step 2(2), the mass ratio of BN / PCP hybrid to cobalt nitrate hexahydrate is 1:0.8-1.

[0021] Furthermore, in step 2(2), the mass ratio of cobalt nitrate hexahydrate to sodium citrate is 1:0.8-1.

[0022] Furthermore, in step 2(2), the mass-volume concentration of the K3[Fe(CN)6] aqueous solution is 0.08-0.1 g / mL.

[0023] Furthermore, in step 3, the BN / PCP@PBA composite flame retardant accounts for 2.0-5.0% of the total mass of the base coating system and the BN / PCP@PBA composite flame retardant.

[0024] The present invention provides a method for preparing a bimetallic Prussian blue complex boron nitride-based fire-retardant coating, which has the following beneficial effects.

[0025] (1) The two-dimensional layered structure of boron nitride can increase the path for oxygen to enter and for combustible gases generated by polymer pyrolysis to escape, slow down the contact time between oxygen and combustible gases, and effectively block some heat from going to the outside and delay the damage of heat to the internal resin matrix, thereby improving the flame retardant properties of the polymer.

[0026] (2) PCP in the composite flame retardant begins to decompose, producing some nitrogen-containing inert gases, which can reduce the temperature and concentration of combustible gases in the local combustion zone. Meanwhile, phosphorus-containing free radicals produced by phosphorus-containing groups can combine with reactive groups released during the combustion reaction, thereby interrupting the rapid combustion reaction chain and slowing down the entire combustion reaction process.

[0027] (3) During the combustion of bimetallic Prussian blue complex, metal oxides are generated, which promote the cross-linking of more small molecule intermediates into carbon, thereby ensuring that more residual carbon participates in resisting external heat. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the preparation process of BN / PCP@PBA composite flame retardant.

[0029] Figure 2 FT-IR spectra of BN, BN / PCP, Co-Fe / PBA, and BN / PCP@PBA.

[0030] Figure 3 XRD patterns of BN, BN / PCP, Co-Fe / PBA, and BN / PCP@PBA.

[0031] Figure 4 SEM images and EDS images of BN / PCP@PBA for different samples, where (a) BN, (b) BN / PCP, (c) Co-Fe / PBA, (d, e) BN / PCP@PBA and (fl) BN / PCP@PBA are EDS images.

[0032] Figure 5 XPS spectrum of BN / PCP@PBA composite flame retardant.

[0033] Figure 6 This is a graph showing the temperature change on the back side of the steel sheet and the coated sample.

[0034] Figure 7 The expansion height and expansion rate of different samples.

[0035] Figure 8 (a) Absorbance curves and (b) Smoke density ratios for different samples.

[0036] Figure 9 The images show the XRD patterns of the carbon layers after combustion of different coatings.

[0037] Figure 10 SEM images and EDS spectra of the remaining char layers after combustion tests of different samples are shown, including SEM images of the char layers of (a) EP, (b) BN / EP, (c) BN / PCP / EP, (d) Co-Fe / PBA / EP, (e) BN / PCP@PBA / EP and EDS-Mapping image of (fl) BN / PCP@PBA / EP. Detailed Implementation

[0038] Example 1.

[0039] A method for preparing a bimetallic Prussian blue complex boron nitride-based fire-retardant coating includes the following steps.

[0040] 1. Preparation of base material.

[0041] Weigh out waterborne epoxy resin (EP), curing agent, and expansion system and stir until uniform to obtain a uniformly mixed base material, wherein the expansion system includes polyphosphate (APP), pentaerythritol (PER), and melamine (MEL).

[0042] 2. Preparation of BN / PCP@PBA composite flame retardant.

[0043] (1) Preparation process of BN / PCP: 0.35 g of BN was ultrasonically dispersed in 100 mL of tetrahydrofuran (THF) solvent; then, 10 mL of triethylamine as acid acceptor and 1.5 g of p-phenylenediamine as reaction monomer were added to the BN dispersion and stirred for 20 minutes; subsequently, 10 mL of hexachlorocyclophosphamide (0.18 g / mL) THF solution was added to the BN dispersion and reacted at 60 °C for 6 hours; finally, the precipitate was washed 3-4 times with THF and hot deionized water, and then vacuum dried at 80 °C for 12 hours to obtain BN / PCP hybrid.

[0044] (2) Preparation process of BN / PCP@PBA composite flame retardant: 0.2g of BN / PCP hybrid was ultrasonically dispersed in 100mL of water; 1.92g of cobalt nitrate hexahydrate and 1.8g of sodium citrate were dissolved in the BN / PCP dispersion and magnetically stirred for 10 minutes; then, 10mL of aqueous solution containing K3[Fe(CN)6] (0.092g / mL) was added to the BN / PCP mixture and stirred for 12 hours; finally, the obtained product was repeatedly washed three times by centrifugation with pure water to obtain BN / PCP@PBA composite flame retardant.

[0045] 3. Preparation of bimetallic Prussian blue complex boron nitride-based fire-retardant coating.

[0046] Weigh out the BN / PCP@PBA composite flame retardant and mix it with the base material. Stir it mechanically until uniform to form a uniform coating system. Then, brush the uniformly mixed BN / PCP@PBA-based water-based intumescent fire retardant coating onto the surface of a steel sheet with a pretreatment grade of Sa2. After brushing, cure at room temperature for 7 days to obtain a bimetallic Prussian blue complex boron nitride-based fire retardant coating. The composition of different intumescent fire retardant coatings is shown in Table 1.

[0047] Table 1 Composition of different intumescent fire-retardant coatings

[0048]

[0049] Experimental Example 1.

[0050] This experimental example demonstrates the experimental analysis results related to the preparation method of a bimetallic Prussian blue complex boron nitride-based fire-retardant coating.

[0051] 2.0 wt.% of BN, BN / PCP, Co-Fe / PBA, and BN / PCP@PBA hybrids were uniformly mixed with the matrix coating system to prepare 2.0 wt.% BN / EP, BN / PCP / EP, Co-Fe / PBA / EP, and BN / PCP@PBA / EP coatings, respectively. Then, the uniformly dispersed coating system was brushed onto the surface of a steel sheet with a pretreatment grade of Sa2. After brushing, the coating was cured at room temperature for 7 days to obtain the sample coating. In addition, a pure EP coating was used as a control in the experiment.

[0052] (1) The FT-IR spectra of BN, BN / PCP, Co-Fe / PBA and BN / PCP@PBA are as follows: Figure 2 As shown; with 1375cm -1 and 815cm -1 The signal peak in a pure BN centered at 3320 cm corresponds to the in-plane and out-of-plane vibrations of the BN; for BN / PCP, 3320 cm -1 The broad peak at 1633 cm⁻¹ is attributed to the NH bond in PCP. -1 and 1515cm -1 The peak at 1148 cm⁻¹ is related to the benzene ring skeleton. -1 937cm -1 and 554cm -1 The peak at 2110 cm⁻¹ originates from the P=N, PN, and P-Cl bonds in the HCCP structure; these characteristic absorption peaks confirm the successful coverage of p-PDA and HCCP on BN; for the Co-Fe / PBA hybrid, the peak at 2110 cm⁻¹ is located at 2110 cm⁻¹. -1 and 1080cm -1 The nearby peaks are attributed to -CN- and COC bonds, respectively, which verifies the successful synthesis of Co-Fe / PBSA. In addition, BN / PCP@PBA has all the absorption signals of BN, PCP and Co-Fe / PBA, confirming the successful preparation of the BN / PCP@PBA composite flame retardant.

[0053] (2) XRD patterns of BN, BN / PCP, Co-Fe / PBA and BN / PCP@PBA are as follows: Figure 3As shown, pure BN exhibits five main diffraction peaks at 26.7°, 41.6°, 43.7°, 50.1°, and 55.2°, corresponding to the (002), (100), (101), (102), and (004) crystal planes of BN, respectively. After loading the PCP organic layer onto the surface, it can be found that the characteristic diffraction peaks at each position still exist, indicating that the crystal structure of BN remains intact. For the Co-Fe / PBA sample, the diffraction peaks at 17.7°, 25.2°, 35.9°, 40.3°, 44.3°, 51.5°, 55.3°, and 58.4° belong to the (200), (220), (400), (420), (422), (440), (600), and (620) crystal planes, which are consistent with JCPDS. The results of 73-0687 are highly consistent, indicating the successful preparation of the PBA structure; for the BN / PCP@PBA hybrid, all diffraction peaks of BN and Co-Fe / PBA can be detected, further proving the successful combination of BN and PBA.

[0054] (3) The microstructures of BN, BN / PCP, Co-Fe / PBA, and BN / PCP@PBA were recorded by SEM, such as... Figure 4 As shown; from Figure 4 (a) As can be seen, the original BN exhibits a smooth, typical two-dimensional layered structure; in Figure 4 In (b), the surface of the BN nanosheets appears to be coated with organic matter, which visually demonstrates that the PCP organic layer was successfully loaded onto the BN surface; from Figure 4 (c) It can be seen that the prepared Co-Fe / PBA exhibits a regular cubic structure, which is highly consistent with the reports in the literature, indicating that the preparation of PBA was successful; for the BN / PCP@PBA composite flame retardant ( Figure 4 (e) It can be observed that a large number of Co-Fe / PBA nanoparticles are uniformly anchored on the BN surface, indicating that Co-Fe / PBA is firmly bonded to BN through chemical bonds; the elemental distribution and composition of the BN / PCP@PBA composite flame retardant are as follows: Figure 4 As shown in (fl), it can be clearly seen that the response signals of elements C, N, O, P, Co and Fe are very uniformly distributed in the scanning area, which further confirms the uniform loading of PCP and Co-Fe / PBA on the BN surface.

[0055] (4) XPS plot of BN / PCP@PBA as follows Figure 5 As shown; from Figure 5 (a) It can be seen that BN / PCP@PBA is mainly composed of C1s, N1s, O1s, B1s, P2p, Fe2p, and Co2p; Figure 5In (b), the C1s spectrum has five signal peaks at 284.7 eV, 285.3 eV, 286.1 eV, 287.1 eV, and 288.6 eV, corresponding to the CC, CN, CO, C=O, and OC=O bonds, respectively; from Figure 5 (c) It can be seen that the peaks at 397.8 eV, 398.4 eV, and 399.1 eV in the N1s spectrum can be attributed to NB, cN, and NP / NH bonds, with CN and NP / NH originating from the PCP structure; while the O1s ( Figure 5 (d) consists of three fitted signals: PO (531.8 eV), OC=O (533.3 eV), and C=O (534.2 eV); for P2p high-resolution spectra ( Figure 5 (e) captured three signals at 131.5 eV, 132.4 eV, and 133.3 eV, corresponding to PO, PN, and P=N in the HCCP structure, respectively; in the Fe2p spectrum ( Figure 5 (f) The peaks at 708.5 eV, 721.3 eV, and 722.9 eV are attributed to Fe2p3 / 2, respectively. 2+ Fe2p1 / 2 2+ and Fe 3+ Co2p high-resolution spectrum ( Figure 5 (g) can be decomposed into four peaks, with peaks at 782.3 eV (Co2p3 / 2 Co). 3+ 785.6 eV (Co 2p3 / 2), 788.1 eV (Sat.), and 797.6 eV (Co 2p1 / 2). 2+ The signals from Fe2p and Co2p confirmed the successful synthesis of Co-Fe / PBA.

[0056] (5) The trend of back surface temperature change during combustion of pure EP, BN / EP, BN / PCP / EP, Co-Fe / PBA / EP and BN / PCP@PBA / EP is as follows: Figure 6As shown; due to the good thermal conductivity of bare steel sheets, the back surface temperature rises continuously to over 500℃ in a short period of time during combustion; after applying an EP protective layer to the bare steel surface, the rapid temperature rise is prevented, and the temperature eventually stabilizes at 259.2℃, indicating that EP is effective in protecting the steel from heat; for the BN / EP coating, the back surface temperature eventually stabilizes at 208.5℃, and this significant reduction proves the effectiveness of BN nanosheets in blocking heat; in the case of BN / PCP reinforced EP, the back surface temperature drops to 187.4℃, which can be attributed to The abundant N and P flame-retardant groups in PCP inhibit the combustion reaction chain. In addition, Co-Fe / PBA / EP exhibits significant thermal insulation performance, with the back side temperature significantly reduced to 178.6℃. This can be attributed to the ability of Co / Fe metal oxides to catalyze the formation of residual char, thereby better preventing heat dissipation. The back side temperature of BN / PCP@PBA / EP is further reduced and eventually reaches the lowest value (165.9℃), which is closely related to the high barrier effect of BN, the gas-phase flame-retardant function of PCP, and the catalytic char formation of Co-Fe / PBA.

[0057] (6) The expansion parameters obtained from the experiment are as follows: Figure 7 As shown; through comparison, it was found that the expansion height and expansion rate of pure EP were only 8.3 mm and 6.34, respectively. This poor expansion performance resulted in poor insulation against heat / flame. With the addition of BN, the expansion height and expansion rate increased to 10.4 mm and 8.13, respectively, indicating that BN nanosheets have a positive impact on the expansion properties of the coating. For the BN / PCP / EP coating, the expansion height and expansion rate significantly increased to 16.1 mm and 12.38, respectively. This is mainly attributed to the fact that the introduction of a large amount of N and P flame-retardant elements can effectively block the combustion reaction chain, thereby reducing the further decomposition of intermediate cracking products. Furthermore, the Co-Fe / PBA / EP coating exhibits considerable expansion, with an expansion height of 20.4 mm and an expansion rate of 15.81. This is mainly attributed to the fact that Co / Fe metal oxides can promote the formation of residual carbon during the coating foaming process, thereby increasing the expansion height of the carbon layer. In contrast, BN / PCP@PBA / EP has the largest expansion height and expansion rate (27.6 mm, 21.07), which can be attributed to the high barrier properties of BN, which prevents the propagation of cracks to the external space. In addition, the flame-retardant elements of N and P and the Co / Fe metal oxides promote the participation of more residual carbon in the foaming process.

[0058] (7) The properties of smoke generated during the combustion of EP, BN / EP, BN / PCP / EP, Co-Fe / PBA / EP, and BN / PCP@PBA / EP were tested, and the results are as follows: Figure 8 As shown; throughout the combustion process, the absorbance of pure EP was greater than that of other samples with added inorganic nanomaterials, indicating that it produced the largest amount of smoke; in Figure 8 In (b), the smoke density ratings of EP, BN / EP, BN / PCP / EP, Co-Fe / PBA / EP, and BN / PCP@PBA / EP were 64.7%, 58.2%, 49.6%, 44.8%, and 36.9%, respectively. The decrease in smoke density of BN / EP can be attributed to the restriction of smoke diffusion by BN nanosheets, while the decrease in smoke density of BN / PCP / EP is related to the gas-phase flame retardant effect of N and P elements in PCP and the inhibitory effect of phosphorus-containing free radicals on the combustion reaction chain. For Co-Fe / PBA / EP, the lower smoke release is mainly attributed to the fact that Co / Fe oxides induce more intermediates to be converted into solid carbon residues at high temperatures, thereby reducing the generation of volatiles. In contrast, BN / PCP@PBA / EP has the lowest smoke generation mainly due to the beneficial synergistic effect of the components in the composite flame retardant.

[0059] (8) XRD patterns of residual char after combustion of EP, BN / EP, BN / PCP / EP, Co-Fe / PBA / EP and BN / PCP@PBA / EP are as follows: Figure 9 As shown; pure EP exhibits only a weak and broad characteristic peak near 24.7°, corresponding to the typical amorphous structure of the residual carbon; for BN / EP, peaks belonging to the (002), (100), (101), (102), and (004) crystal planes of BN can be seen at 2θ = 26.7°, 41.6°, 43.9°, 50.1°, and 55.2°, indicating that BN is retained in the residual carbon framework after high temperature; in the residual carbon of BN / PCP / EP, the intensity of the individual peaks of BN is significantly lower, which is related to the reduction of BN content; for the Co-Fe / PBA / EP composite coating, the intensity of the individual peaks is significantly lower at 35.6° and 57.2°. The diffraction peaks at 2θ = 29.5° correspond to the (311), (511), and (440) crystal planes of FeO, while the peaks at 36.9° and 43.2° can be traced back to the (111) and (200) crystal planes of CoO (number 48-1719), which strongly proves the formation of metal oxides. In addition, the peak at 2θ = 29.5° is due to the characteristic diffraction of Co(PO3)2, which is caused by the interaction of Co ions with the phosphate source in the expanded component at high temperature. Diffraction features of BN and metal oxides can be observed in the residual carbon of BN / PCP@PBA / EP, which provides the basis for the excellent barrier properties of residual carbon.

[0060] (9) The microscopic surface of residual carbon in EP, BN / EP, BN / PCP / EP, Co-Fe / PBA / EP and BN / PCP@PBA / EP is as follows: Figure 10 As shown; it can be seen that the residual carbon surface of pure EP has a large number of large pores ( Figure 10(a)), which determines that it cannot effectively prevent external heat from penetrating into the steel matrix, thus resulting in its weak thermal insulation capacity; after introducing BN nanosheets into EP ( Figure 10 (b) The number of large pores on the surface of the residual carbon is significantly reduced, but large cracks still exist, which limits its thermal insulation effect; for BN / PCP / EP ( Figure 10 (c)) The large cracks on the surface of the residual carbon are replaced by many small cavities, resulting in a better thermal layer; Figure 10 In (d), the voids and other defects on the residual carbon surface of the Co-Fe / PBA-filled EP are further reduced. This can be attributed to the fact that Fe / Co oxide induces more small molecules to crosslink into carbon at high temperatures, thereby improving the integrity of the residual carbon; the residual carbon surface of BN / PCP@PBA / EP is more complete. Figure 10 (e)) retains only a very small number of pores, which means that it can effectively limit heat penetration into the substrate; Figure 10 (fl) shows the elemental distribution in the residual carbon of BN / PCP@PBA / EP; it can be seen that C, N, B, P, O, Co and Fe are uniformly distributed in the specified scan area, indicating that the residual BN and metal oxides are uniformly embedded in the carbon skeleton, which significantly improves the barrier ability and strength of the residual carbon.

Claims

1. A method for preparing a bimetallic Prussian blue complex boron nitride-based fire-retardant coating, comprising the following steps: (1) Preparation of base material Weigh 38.6g of waterborne epoxy resin, 19.4g of curing agent, and 40g of expansion system and stir until uniform to obtain a uniformly mixed base material, wherein the expansion system includes 20g of polyphosphate, 10g of pentaerythritol, and 10g of melamine. (2) Preparation of BN / PCP@PBA composite flame retardant a. Preparation process of BN / PCP: 0.35 g of boron nitride (BN) was ultrasonically dispersed in 100 mL of tetrahydrofuran; then, 10 mL of triethylamine as an acid acceptor and 1.5 g of p-phenylenediamine as a reactant monomer were added to the boron nitride BN dispersion and stirred for 20 minutes; subsequently, 10 mL of a hexachlorocyclotriphosphazene tetrahydrofuran solution with a mass-volume concentration of 0.18 g / mL was added to the boron nitride BN dispersion and reacted at 60 °C for 6 hours; finally, the obtained precipitate was washed 3-4 times with tetrahydrofuran and hot deionized water, and then vacuum dried at 80 °C for 12 hours to obtain the BN / PCP hybrid. b. Preparation process of BN / PCP@PBA composite flame retardant: 0.2 g of BN / PCP hybrid was ultrasonically dispersed in 100 mL of water; 1.92 g of cobalt nitrate hexahydrate and 1.8 g of sodium citrate were dissolved in the BN / PCP dispersion and magnetically stirred for 10 minutes; then, 10 mL of K3[Fe(CN)6] aqueous solution with a mass-volume concentration of 0.092 g / mL was added to the BN / PCP mixture and stirred for 12 hours; finally, the obtained product was repeatedly washed three times by centrifugation with pure water to obtain the BN / PCP@PBA composite flame retardant; (3) Preparation of bimetallic Prussian blue complex boron nitride-based fire-retardant coating Weigh 2g of BN / PCP@PBA composite flame retardant and mix it with the base material. Stir mechanically until uniform to form a uniform coating system. Then, brush the uniformly mixed BN / PCP@PBA-based water-based intumescent fire retardant coating onto the surface of a steel sheet with a pretreatment grade of Sa2. After brushing, cure at room temperature for 7 days to obtain a bimetallic Prussian blue complex boron nitride-based fire retardant coating.

2. The bimetallic Prussian blue complex boron nitride-based fire-retardant coating prepared by the method described in claim 1.

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