An oil-based fireproof paint and a method for preparing the same

Abstract

The present application relates to the technical field of paint, and relates to an oil-based fireproof paint and a preparation method thereof.The oil-based fireproof paint comprises the following components in parts by weight: modified epoxy resin 15-19, organic silicon modified acrylic resin 5-7, silane modified ammonium polyphosphate 10-12, pentaerythritol 5-8, zinc borate 3-5, hydrotalcite coated zinc stannate composite material 10-12, boron nitride 9-11, dispersing agent 0.8-1.2, leveling agent 0.2-0.4, polyamide wax anti-settling agent 0.6-0.8, and solvent 40-60.The oil-based fireproof paint provided by the present application improves the fire resistance limit and the flame retardancy of the paint, and achieves the best fireproof protection effect;the compatibility of the ammonium polyphosphate and the oil-based resin matrix is improved, and the fireproof performance, the long-term storage stability and the medium corrosion resistance of the cured coating are improved.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to an oil-based fire-retardant coating and its preparation method. Background Technology

[0002] Oil-based fire-retardant coatings offer numerous advantages, such as a smooth and even coating appearance with good decorative properties, meeting the aesthetic requirements of various locations; relatively simple application processes, allowing for brushing, spraying, and other methods, suitable for substrates of various shapes; and rapid drying due to the use of organic solvents as the dispersion medium, enabling the formation of a protective layer in a short time and improving construction efficiency. These advantages make oil-based fire-retardant coatings play a vital role in building fire protection, such as for steel and wood structures; they are also widely used in industrial applications, such as fire-retardant coatings for petrochemical equipment and power facilities.

[0003] Existing oil-based fire-retardant coatings often fail to meet ideal fire resistance requirements in complex fire scenarios. While some traditional oil-based fire-retardant coatings can form an expanded char layer to some extent in the early stages of a fire, this structure is easily damaged as the fire continues, leading to cracking and peeling. This results in a significant decrease in thermal insulation performance and an inability to effectively prevent heat transfer, causing the substrate to reach dangerous temperatures in a short period. This is mainly due to the uneven dispersion of flame-retardant components in existing coatings. During a fire, the components cannot work synergistically to form a high-quality, structurally stable expanded char layer, thus affecting the overall fire resistance and flame-retardant performance of the coating. Furthermore, under high-temperature conditions, the char layer formed by existing oil-based fire-retardant coatings is prone to damage to its integrity and a decrease in thermal insulation. Some coatings form char layers with a loose structure and low strength at high temperatures, making them susceptible to cracking and pulverization under thermal stress and oxygen. This inability to effectively prevent heat and oxygen transfer leads to rapid heating of the substrate and a significant reduction in fire resistance. This is mainly because existing coatings lack components that can effectively improve the high-temperature performance of the char layer, or the amount and mode of action of these components fail to achieve the desired effect, thus failing to form a dense and stable char layer structure, thereby limiting the application of coatings in high-temperature fire scenarios. Based on this, the present invention proposes an oil-based fire-retardant coating and its preparation method. Summary of the Invention

[0004] This invention proposes an oil-based fire-retardant coating and its preparation method, which improves the coating's fire resistance limit and flame retardancy, achieving the best fire protection effect; improves the compatibility between ammonium polyphosphate and oil-based resin matrix, enhancing fire resistance, long-term storage stability, and resistance to media corrosion of the cured coating; improves the high-temperature integrity and lateral thermal insulation capacity of the char layer; and also improves product storage stability, ensuring workability and batch consistency.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention provides an oil-based fire-retardant coating, comprising, by weight, the following components: 15-19 parts modified epoxy resin, 5-7 parts silicone-modified acrylic resin, 10-12 parts silane-modified ammonium polyphosphate, 5-8 parts pentaerythritol, 3-5 parts zinc borate, 10-12 parts hydrotalcite-coated zinc stannate composite material, 9-11 parts boron nitride, 0.8-1.2 parts dispersant, 0.2-0.4 parts leveling agent, 0.6-0.8 parts polyamide wax anti-settling agent, and 40-60 parts solvent.

[0007] As a further technical solution, the preparation method of the hydrotalcite-coated zinc stannate composite material includes:

[0008] (1) Magnesium aluminum hydrotalcite was calcined at 400-500℃ for 4-5 hours and then ground to obtain magnesium aluminum mixed metal oxide;

[0009] (2) Dissolve SnCl2·2H2O and ZnSO4·7H2O together in deionized water to prepare a mixed salt solution; slowly add hydrogen peroxide to the mixed salt solution; and add magnesium and aluminum mixed metal oxides to the solution and ultrasonically disperse to form a suspension;

[0010] (3) Adjust the pH of the suspension system to 11.5±0.1 with alkaline solution, then carry out hydrothermal reaction, centrifuge, wash and dry to obtain the product.

[0011] In the preparation of the hydrotalcite-coated zinc stannate composite material, each step works in concert. First, magnesium-aluminum hydrotalcite is calcined and ground to obtain a magnesium-aluminum mixed metal oxide, providing a suitable reactant base for subsequent reactions. Then, a mixed salt solution is prepared, and hydrogen peroxide is added dropwise. The magnesium-aluminum mixed metal oxide is then added and ultrasonically dispersed to form a suspension. In this process, hydrogen peroxide may participate in the redox reaction, adjusting the redox environment of the solution and facilitating subsequent reactions. After adjusting the pH of the suspension system with an alkaline solution, a hydrothermal reaction is carried out. The suitable pH value and hydrothermal reaction conditions promote the reaction between the magnesium-aluminum mixed metal oxide and tin and zinc ions, forming a uniformly coated composite structure. This synergistic effect of the preparation process ensures the synthesis of the hydrotalcite-coated zinc stannate composite material, guaranteeing its excellent performance in fire-retardant coatings.

[0012] As a further technical solution, the hydrogen peroxide concentration is 25-35wt%, and the ratio of magnesium-aluminum mixed metal oxide, SnCl2·2H2O, ZnSO4·7H2O, deionized water and hydrogen peroxide is 9-11g:6-8g:8-10g:450-550mL:10-13mL.

[0013] As a further technical solution, the hydrothermal reaction conditions are: to carry out the hydrothermal reaction at a temperature of 115-125℃ for 10-11 hours.

[0014] As a further technical solution, the preparation method of the silane-modified ammonium polyphosphate includes: adding ammonium polyphosphate powder to a first anhydrous ethanol, and mechanically stirring and dispersing it at 300-500 rpm for 0.5-1.5 hours at room temperature to obtain a uniformly dispersed ammonium polyphosphate suspension; adding a silane coupling agent to a mixed solvent composed of a second anhydrous ethanol and deionized water, and adjusting the pH of the mixed system to 4-6 using glacial acetic acid, and performing pre-hydrolysis at 200-300 rpm for 20-40 minutes to obtain a silane hydrolysate; slowly adding the silane hydrolysate dropwise to the ammonium polyphosphate suspension under stirring, and then heating and stirring the mixed system; after the reaction is completed, separating the product by vacuum filtration, washing it 2-3 times with anhydrous ethanol, and vacuum drying it at 80-100℃ for 4-6 hours to obtain the silane-modified ammonium polyphosphate.

[0015] As a further technical solution, the temperature after heating is 55-65℃, and the stirring time is 2-4 hours.

[0016] As a further technical solution, the silane coupling agent is octyltriethoxysilane; the ratio of the amount of ammonium polyphosphate powder, the first anhydrous ethanol, the silane coupling agent, the second anhydrous ethanol, and deionized water is 1 g: 16-20 mL: 0.08-0.15 g: 4-6 mL: 0.1-0.2 mL.

[0017] As a further technical solution, the dispersant is BYK110; the leveling agent is polyether-modified polydimethylsiloxane; and the solvent includes xylene, n-butanol, and propylene glycol methyl ether acetate in a weight ratio of 3-5:1:1.

[0018] Secondly, this invention proposes a method for preparing an oil-based fire-retardant coating, comprising the following steps:

[0019] S1. Mix 50%-55% of the total solvent with all the dispersant and stir at 400-600 rpm until homogeneous; first add the hydrotalcite-coated zinc stannate composite material and boron nitride, and disperse at 1000-1200 rpm for 15-20 minutes until initially homogeneous; then add silane-modified ammonium polyphosphate, pentaerythritol, and zinc borate, and disperse at 800-1000 rpm for 10-15 minutes to obtain homogeneous slurry A;

[0020] S2. While stirring the remaining solvent at 400-600 rpm, first add the silicone-modified acrylic resin and stir for 10 minutes to completely dissolve it. Then add the modified epoxy resin and continue stirring for 15-20 minutes until it is completely dissolved and homogeneous to obtain transparent resin liquid B.

[0021] S3. While stirring at 300-400 rpm, slowly add slurry A to resin solution B. After the addition is complete, increase the speed to 600-800 rpm and continue stirring for 10-15 minutes to make it initially uniform. Then transfer the mixture to a sand mill and grind it until the fineness is ≤40μm to obtain base slurry C.

[0022] S4. First, add the leveling agent to the base slurry C at 300-400 rpm and stir for 5 minutes; then slowly add the polyamide wax anti-settling agent to ensure uniform dispersion; after curing, filter with a 150-250 mesh screen to obtain the oil-based fireproof coating.

[0023] As a further technical solution, the maturation is carried out by continuous stirring at a speed of 200-300 rpm for 30-40 minutes.

[0024] In this invention, the curing process promotes further reaction and stabilization of the components, while filtration removes any impurities and uneven particles, thus ensuring the storage stability and performance consistency of the final product. The synergistic operation of the entire preparation process ensures that each component of the oil-based fire-retardant coating can fully function, resulting in a high-performance fire-retardant coating product.

[0025] The working principle and beneficial effects of this invention are as follows:

[0026] In this invention, the hydrotalcite-coated zinc stannate composite material is a key component in achieving high-efficiency fire resistance and thermal insulation performance in this fireproof system. This composite structure is not a simple physical superposition; this coating structure allows the flame-retardant components to be more evenly dispersed within the system, enabling each component to participate in the reaction more efficiently during a fire. The evenly dispersed components can more fully exert their respective functions, promoting the formation of a char layer, and the resulting expanded char layer is of superior quality, possessing better structural strength and thermal insulation performance. This effectively improves the coating's fire resistance limit and flame retardancy, achieving optimal fire protection.

[0027] In this invention, silane-modified ammonium polyphosphate is used as the main intumescent flame retardant. After modification with a silane coupling agent, the grafted silane coupling agent effectively improves the compatibility of ammonium polyphosphate with the oil-based resin matrix. The modified ammonium polyphosphate can more effectively exert its foaming and expansion effect, rapidly forming a heat-insulating char layer. Unmodified ammonium polyphosphate, due to its poor compatibility with the matrix, cannot participate well in the reaction, resulting in the coating failing to effectively form a heat-insulating char layer in the early stages of a fire, and its fire-resistant function is essentially lost. Therefore, silane modification is crucial for improving the fire resistance, long-term storage stability, and corrosion resistance of the cured coating.

[0028] This invention utilizes boron nitride to significantly improve the integrity and lateral insulation of the char layer at high temperatures. Under high-temperature conditions, the lamellar structure of boron nitride facilitates the formation of a denser char layer. This dense char layer structure exhibits better thermal stability and effectively prevents the transfer of heat and oxygen. In contrast, without boron nitride, the char layer is more prone to cracking and peeling under prolonged high temperatures because the lack of support and reinforcement from the boron nitride lamellar structure reduces the overall fire resistance time. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] It should also be noted that the modified epoxy resin was purchased from Wuhan Shiquanxing New Material Technology Co., Ltd., item number SZ-2360; the silicone-modified acrylic resin was purchased from Wanjia Huixin Surface Materials Co., Ltd., model S-611; the ammonium polyphosphate was purchased from Guangzhou Haoyu International Trade Co., Ltd.; the magnesium aluminum hydrotalcite was purchased from Maoming Chuizi New Material Co., Ltd., CAS number RH-01339; and the polyamide wax was purchased from Shanghai Tongshi Technology Co., Ltd., model PA-103.

[0031] Example 1

[0032] This embodiment provides an oil-based fire-retardant coating, comprising the following components by weight: 17 parts modified epoxy resin, 6 parts silicone-modified acrylic resin, 11 parts silane-modified ammonium polyphosphate, 6.5 parts pentaerythritol, 4 parts zinc borate, 11 parts hydrotalcite-coated zinc stannate composite material, 10 parts boron nitride, 1.0 part BYK110 dispersant, 0.3 parts leveling agent polyether-modified polydimethylsiloxane, 0.7 parts polyamide wax anti-settling agent, and 50 parts solvent (including 30 parts xylene, 10 parts n-butanol, and 10 parts propylene glycol methyl ether acetate).

[0033] The preparation steps of the hydrotalcite-coated zinc stannate composite material include:

[0034] Magnesium-aluminum hydrotalcite was calcined at 450℃ for 4.5 h and then ground to obtain a magnesium-aluminum mixed metal oxide. 7 g of SnCl2·2H2O and 9 g of ZnSO4·7H2O were dissolved in 500 mL of deionized water to prepare a mixed salt solution. 12 mL of 30 wt% hydrogen peroxide was slowly added dropwise to the mixed salt solution, and 10 g of magnesium-aluminum mixed metal oxide was added to the solution. The solution was ultrasonically dispersed for 30 minutes to form a uniform suspension. The pH of the suspension system was adjusted to 11.5 ± 0.1 with 1 mol / L NaOH solution, and then transferred to a high-pressure reactor for hydrothermal reaction at 120℃ for 10.5 h. After the reaction, the mixture was centrifuged, washed three times each with deionized water and anhydrous ethanol, and vacuum dried at 80℃ for 12 h to obtain a hydrotalcite-coated zinc stannate composite material.

[0035] The preparation steps of silane-modified ammonium polyphosphate include:

[0036] 100g of ammonium polyphosphate powder was added to 1800mL of anhydrous ethanol and mechanically stirred at 400rpm for 1 hour at room temperature to obtain a uniformly dispersed ammonium polyphosphate suspension. 10g of octyltriethoxysilane was added to a mixed solvent consisting of 500mL of anhydrous ethanol and 15mL of deionized water. The pH of the mixture was adjusted to 5.0 using glacial acetic acid, and pre-hydrolyzed at 250rpm for 30 minutes to obtain a silane hydrolysate. The silane hydrolysate was slowly added dropwise to the ammonium polyphosphate suspension while stirring at 200rpm. The mixture was then heated to 60℃ and stirred continuously at this temperature for 3 hours. After the reaction was completed, the product was separated by filtration, washed three times with anhydrous ethanol, and vacuum dried at 90℃ for 5 hours to obtain silane-modified ammonium polyphosphate.

[0037] The preparation method of the oil-based fire-retardant coating in this embodiment includes the following steps:

[0038] Mix 52% of the total solvent volume with the dispersant and stir at 500 rpm for 10 minutes. First, add the hydrotalcite-coated zinc stannate composite material and boron nitride, and disperse at 1100 rpm for 18 minutes until initially homogeneous. Then, add silane-modified ammonium polyphosphate, pentaerythritol, and zinc borate, and disperse at 900 rpm for 13 minutes to obtain a uniform slurry A. With the remaining solvent, stir at 500 rpm, first add the organosilicon-modified acrylic resin, and stir for 10 minutes to completely dissolve it. Then, add the modified epoxy resin and continue stirring for 18 minutes until completely dissolved and homogeneous to obtain a transparent resin solution B. With stirring at 350 rpm, slowly add slurry A to resin solution B, controlling the addition time within 15 minutes. After the addition is complete, increase the speed to 700 rpm and continue stirring for 13 minutes to initially mix and homogeneous. The mixture was then transferred to a sand mill for grinding, using zirconia beads (1.0-1.2 mm in diameter) as the grinding media. Grinding time was 2 hours, with the temperature controlled to not exceed 45°C, until the fineness was ≤40 μm, yielding base slurry C. Polyether-modified polydimethylsiloxane leveling agent was added to base slurry C at 350 rpm, and the mixture was stirred for 5 minutes to ensure uniform dispersion. Then, polyamide wax anti-settling agent was slowly added, controlling the feeding speed to prevent clumping and ensure uniform dispersion. Finally, the mixture was continuously stirred at 250 rpm for 35 minutes to mature. After maturation, it was filtered through a 200-mesh filter to obtain the oil-based fire-retardant coating of this embodiment.

[0039] Example 2

[0040] This embodiment provides an oil-based fire-retardant coating, comprising the following components by weight: 19 parts modified epoxy resin, 7 parts silicone-modified acrylic resin, 12 parts silane-modified ammonium polyphosphate, 8 parts pentaerythritol, 5 parts zinc borate, 12 parts hydrotalcite-coated zinc stannate composite material, 11 parts boron nitride, 1.2 parts BYK110 dispersant, 0.4 parts leveling agent polyether-modified polydimethylsiloxane, 0.8 parts polyamide wax anti-settling agent, and 60 parts solvent (including 36 parts xylene, 12 parts n-butanol, and 12 parts propylene glycol methyl ether acetate).

[0041] The preparation steps of the hydrotalcite-coated zinc stannate composite material include:

[0042] Magnesium-aluminum hydrotalcite was calcined at 500℃ for 5 hours and then ground to obtain a magnesium-aluminum mixed metal oxide. 8g of SnCl2·2H2O and 10g of ZnSO4·7H2O were dissolved in 550mL of deionized water to prepare a mixed salt solution. 13mL of 35wt% hydrogen peroxide was slowly added dropwise to the mixed salt solution, and 11g of the magnesium-aluminum mixed metal oxide was added to the solution. The mixture was ultrasonically dispersed for 30 minutes to form a uniform suspension. The pH of the suspension system was adjusted to 11.5±0.1 with 1mol / L NaOH solution, and then transferred to a high-pressure reactor for hydrothermal reaction at 125℃ for 11 hours. After the reaction, the mixture was centrifuged, washed three times each with deionized water and anhydrous ethanol, and then vacuum dried at 80℃ for 12 hours to obtain a hydrotalcite-coated zinc stannate composite material.

[0043] The preparation steps of silane-modified ammonium polyphosphate include:

[0044] 100g of ammonium polyphosphate powder was added to 2000mL of anhydrous ethanol and mechanically stirred at 500rpm for 1.5 hours at room temperature to obtain a uniformly dispersed ammonium polyphosphate suspension. 12g of octyltriethoxysilane was added to a mixed solvent consisting of 600mL of anhydrous ethanol and 20mL of deionized water. The pH of the mixture was adjusted to 6 using glacial acetic acid, and pre-hydrolyzed at 300rpm for 40 minutes to obtain a silane hydrolysate. The silane hydrolysate was slowly added dropwise to the ammonium polyphosphate suspension while stirring at 200rpm. The mixture was then heated to 65℃ and stirred continuously at this temperature for 4 hours. After the reaction was completed, the product was separated by filtration, washed three times with anhydrous ethanol, and vacuum dried at 100℃ for 6 hours to obtain silane-modified ammonium polyphosphate.

[0045] The preparation method of the oil-based fire-retardant coating in this embodiment includes the following steps:

[0046] Mix 55% of the total solvent volume with the dispersant and stir at 600 rpm for 10 minutes. First, add the hydrotalcite-coated zinc stannate composite material and boron nitride, and disperse at 1200 rpm for 20 minutes until initially homogeneous. Then, add silane-modified ammonium polyphosphate, pentaerythritol, and zinc borate, and disperse at 1000 rpm for 15 minutes to obtain a homogeneous slurry A. With the remaining solvent, stir at 600 rpm, first add the organosilicon-modified acrylic resin, and stir for 10 minutes to completely dissolve it. Then, add the modified epoxy resin and continue stirring for 20 minutes until completely dissolved and homogeneous to obtain a transparent resin solution B. With stirring at 400 rpm, slowly add slurry A to resin solution B, controlling the addition time within 15 minutes. After the addition is complete, increase the speed to 800 rpm and continue stirring for 15 minutes to initially mix and homogeneous. The mixture was then transferred to a sand mill for grinding, using zirconia beads (1.0-1.2 mm in diameter) as the grinding media. Grinding time was 2 hours, with the temperature controlled to not exceed 45°C, until the fineness was ≤40 μm, yielding base slurry C. Polyether-modified polydimethylsiloxane leveling agent was added to base slurry C at 400 rpm, and the mixture was stirred for 5 minutes to ensure uniform dispersion. Then, polyamide wax anti-settling agent was slowly added, controlling the feeding speed to prevent clumping and ensure uniform dispersion. Finally, the mixture was continuously stirred at 300 rpm for 40 minutes to mature. After maturation, it was filtered through a 250-mesh filter to obtain the oil-based fire-retardant coating of this embodiment.

[0047] Example 3

[0048] This embodiment provides an oil-based fire-retardant coating, comprising the following components by weight: 15 parts modified epoxy resin, 5 parts silicone-modified acrylic resin, 10 parts silane-modified ammonium polyphosphate, 5 parts pentaerythritol, 3 parts zinc borate, 10 parts hydrotalcite-coated zinc stannate composite material, 9 parts boron nitride, 0.8 parts BYK110 dispersant, 0.2 parts leveling agent polyether-modified polydimethylsiloxane, 0.6 parts polyamide wax anti-settling agent, and 40 parts solvent (including 24 parts xylene, 8 parts n-butanol, and 8 parts propylene glycol methyl ether acetate).

[0049] The preparation steps of the hydrotalcite-coated zinc stannate composite material include:

[0050] Magnesium-aluminum hydrotalcite was calcined at 400℃ for 4 hours and then ground to obtain a magnesium-aluminum mixed metal oxide. 6g of SnCl2·2H2O and 8g of ZnSO4·7H2O were dissolved in 450mL of deionized water to prepare a mixed salt solution. 10mL of 25wt% hydrogen peroxide was slowly added dropwise to the mixed salt solution, and 9g of the magnesium-aluminum mixed metal oxide was added to the solution. The mixture was ultrasonically dispersed for 30 minutes to form a uniform suspension. The pH of the suspension system was adjusted to 11.5±0.1 with 1mol / L NaOH solution, and then transferred to a high-pressure reactor for hydrothermal reaction at 115℃ for 10 hours. After the reaction, the mixture was centrifuged, washed three times each with deionized water and anhydrous ethanol, and then vacuum dried at 80℃ for 12 hours to obtain a hydrotalcite-coated zinc stannate composite material.

[0051] The preparation steps of silane-modified ammonium polyphosphate include:

[0052] 100g of ammonium polyphosphate powder was added to 1600mL of anhydrous ethanol and mechanically stirred at 300rpm for 0.5 hours at room temperature to obtain a uniformly dispersed ammonium polyphosphate suspension. 8g of octyltriethoxysilane was added to a mixed solvent consisting of 400mL of anhydrous ethanol and 10mL of deionized water. The pH of the mixture was adjusted to 4 using glacial acetic acid, and pre-hydrolyzed at 200rpm for 20 minutes to obtain a silane hydrolysate. The silane hydrolysate was slowly added dropwise to the ammonium polyphosphate suspension while stirring at 200rpm. The mixture was then heated to 55℃ and stirred continuously at this temperature for 2 hours. After the reaction was completed, the product was separated by filtration, washed three times with anhydrous ethanol, and vacuum dried at 80℃ for 4 hours to obtain silane-modified ammonium polyphosphate.

[0053] The preparation method of the oil-based fire-retardant coating in this embodiment includes the following steps:

[0054] Mix 50% (20 parts) of the total solvent (containing 12 parts xylene, 4 parts n-butanol, and 4 parts propylene glycol methyl ether acetate) with the dispersant and stir at 400 rpm for 10 minutes. First, add the hydrotalcite-coated zinc stannate composite material and boron nitride, and disperse at 1000 rpm for 15 minutes until initially homogeneous. Then, add silane-modified ammonium polyphosphate, pentaerythritol, and zinc borate, and disperse at 800 rpm for 10 minutes to obtain a homogeneous slurry A. With the remaining solvent, stir at 400 rpm, first add the silicone-modified acrylic resin, and stir for 10 minutes until completely dissolved. Then, add the modified epoxy resin and continue stirring for 15 minutes until completely dissolved and homogeneous to obtain a transparent resin solution B. With stirring at 300 rpm, slowly add slurry A to resin solution B, controlling the addition time within 15 minutes. After the addition is complete, increase the speed to 600 rpm and continue stirring for 10 minutes to initially mix and homogeneous. The mixture was then transferred to a sand mill for grinding, using zirconia beads (1.0-1.2 mm in diameter) as the grinding media. Grinding time was 2 hours, with the temperature controlled to not exceed 45°C, until the fineness was ≤40 μm, yielding base slurry C. Polyether-modified polydimethylsiloxane leveling agent was added to base slurry C at 300 rpm, and the mixture was stirred for 5 minutes to ensure uniform dispersion. Then, polyamide wax anti-settling agent was slowly added, controlling the feeding speed to prevent clumping and ensure uniform dispersion. Finally, the mixture was continuously stirred at 200 rpm for 30 minutes to mature. After maturation, it was filtered through a 150-mesh filter to obtain the oil-based fire-retardant coating of this embodiment.

[0055] Comparative Example 1

[0056] Based on Example 1, adjustments were made. Unlike Example 1, Comparative Example 1 did not include the hydrotalcite-coated zinc stannate composite material, and its proportion was removed from the formula. The rest was the same as in Example 1.

[0057] Comparative Example 2

[0058] Based on Example 1, adjustments were made. Unlike Example 1, silane-modified ammonium polyphosphate was not added in Comparative Example 2, and its proportion was removed from the formula. Otherwise, it was the same as Example 1.

[0059] Comparative Example 3

[0060] Based on Example 1, adjustments were made. Unlike Example 1, boron nitride was not added in Comparative Example 3, and its proportion was removed from the formula. Otherwise, it was the same as Example 1.

[0061] Comparative Example 4

[0062] Based on Example 1, adjustments were made. The difference from Example 1 is that in Comparative Example 4, unmodified ammonium polyphosphate was used to replace an equal amount of silane-modified ammonium polyphosphate, while the rest was the same as in Example 1.

[0063] Comparative Example 5

[0064] Based on Example 1, adjustments were made. The difference was that in Comparative Example 5, when preparing the hydrotalcite-coated zinc stannate composite material, 10g of the magnesium-aluminum mixed metal oxide was replaced with an equal mass of physically mixed magnesium-aluminum hydrotalcite (5.5g) and zinc stannate (5.5g), and the hydrothermal reaction was carried out according to the same steps. The resulting physical mixture replaced the hydrotalcite-coated zinc stannate composite material in Example 1, and the rest remained the same as in Example 1.

[0065] Comparative Example 6

[0066] Based on Example 1, adjustments were made. Unlike Example 1, in the final step of the preparation method in Comparative Example 6, after adding the leveling agent and polyamide wax anti-settling agent and dispersing them evenly, the mixture was discharged directly without filtration or curing.

[0067] Test Example: The oil-based fire-retardant coatings prepared in Examples 1-3 and Comparative Examples 1-6 were tested as follows:

[0068] Adhesion: The adhesion was tested according to GB / T5210-2006 "Paints and Varnishes - Pull-off Adhesion Test". The maximum pull-off strength between the coating and the substrate was determined using an automatic pull-off adhesion tester, and the unit is megapascal (MPa).

[0069] Impact resistance: Tested according to GB / T20624.2-2006 "Paints and varnishes rapid deformation (impact resistance) test part 2: drop hammer test (small area punch)" standard, using a 1kg weight hammer to drop freely from a height of 50cm to impact the coating, and check the condition of the paint film in the impact area.

[0070] Water resistance: According to GB / T1733-2023 "Test Method for Water Resistance of Paint Film", the test panel was immersed in deionized water at (40±1)℃ for 168 hours (7 days) and then taken out to check whether there was any blistering, discoloration, peeling or other phenomena in the paint film, and the adhesion retention rate was tested.

[0071] Salt water resistance: The test was conducted by immersion method in GB / T9274-2016 "Determination of resistance to liquid media of paints and varnishes". The test panel was immersed in a sodium chloride (NaCl) solution with a mass fraction of (40±1)℃ for 168 hours (7 days) and then evaluated.

[0072] Storage stability: The coating samples were tested according to GB / T6753.3-2023 "Test Method for Storage Stability of Coatings". The coating samples were placed in a constant temperature oven at (50±2)℃ for accelerated storage for 30 days. The viscosity changes, sedimentation and agglomeration were checked and recorded regularly.

[0073] Small chamber method flame retardancy: The test was conducted according to GB / T15442.4-1995 "Classification and Test Methods of Fire Retardant Performance of Decorative Fire Retardant Coatings - Small Chamber Method". The coated test panel was vertically burned in a combustion chamber of specified size, and the mass loss rate (%) was measured and recorded.

[0074] Fire resistance limit of large-panel method: Referring to GB / T9978.1-2008 "Fire resistance test method for building components - Part 1: General requirements" and GB14907-2018 "Fire retardant coatings for steel structures" standards, a 2.0 mm dry film thickness of the coating was applied to a standard I36b I-beam steel component. The component was placed in a standard fire resistance test furnace, and the temperature was increased according to the standard time-temperature curve. The time it took for the average temperature of the unexposed surface of the steel component to reach 540℃ was taken as the fire resistance limit (min). The results are shown in Table 1 below.

[0075] Table 1

[0076]

[0077] Based on the above, it can be seen that the fire resistance limit and flame retardancy of the zinc stannate composite material without hydrotalcite coating in Comparative Example 1 are significantly worse than those in Example 1. This indicates that the hydrotalcite-coated zinc stannate composite material is a key component for achieving high-efficiency fire resistance and heat insulation performance in this fire protection system; its absence leads to reduced char layer catalytic formation efficiency, insufficient char layer structural strength and heat insulation, and thus fails to achieve the best fire protection effect.

[0078] Comparative Example 2 shows that the lack of silane-modified ammonium polyphosphate resulted in deteriorated fire resistance, a sharp drop in fire resistance limit, and a high mass loss rate; this directly demonstrates the core role of silane-modified ammonium polyphosphate as a major intumescent flame retardant. Its absence prevents the coating from effectively foaming and expanding to form a heat-insulating char layer in the early stages of a fire, leading to a near-complete loss of fire resistance.

[0079] The fire resistance limit of Comparative Example 3, lacking boron nitride, was lower than that of Example 1. This indicates that boron nitride makes a significant contribution to improving the integrity and lateral insulation of the char layer at high temperatures. Its lamellar structure helps to form a denser char layer with better thermal stability. Without boron nitride, the char layer is more prone to cracking and peeling under prolonged high temperatures, thus reducing the overall fire resistance time.

[0080] Comparative Example 4 (using unmodified ammonium polyphosphate) showed decreased fire resistance, poor storage stability, and severely reduced salt water resistance (significant foaming). This fully demonstrates the necessity of silane modification. Grafting with silane coupling agents effectively improves the compatibility of ammonium polyphosphate with oily resin matrices, significantly enhancing the long-term storage stability of the coating and the corrosion resistance of the cured coating—achievements that unmodified products cannot.

[0081] Comparative Example 5, which used a physical mixture instead of a coated composite material, showed significantly worse fire resistance and flame retardancy than Example 1. This indicates that the synergistic catalytic and flame-retardant effect produced by the composite structure of hydrotalcite-coated zinc stannate is far superior to that of simple physical mixing; this coating structure may allow for more uniform dispersion and more efficient reaction of the flame-retardant components, thereby forming a higher quality expanded char layer.

[0082] Comparative Example 6, omitting the curing and filtration steps, exhibited fire resistance similar to Example 1, but its storage stability decreased to medium, with slight sedimentation and viscosity instability. This indicates that the curing and filtration process is crucial for obtaining a final product with stable storage and consistent performance. Omitting this step does not affect the basic function, but it leads to instability in the product's physical state, impacting workability and batch consistency.

[0083] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An oil-based fire-retardant coating, characterized in that, The product comprises, by weight, the following components: 15-19 parts modified epoxy resin, 5-7 parts silicone modified acrylic resin, 10-12 parts silane coupling agent modified ammonium polyphosphate, 5-8 parts pentaerythritol, 3-5 parts zinc borate, 10-12 parts hydrotalcite-coated zinc stannate composite material, 9-11 parts boron nitride, 0.8-1.2 parts dispersant, 0.2-0.4 parts leveling agent, 0.6-0.8 parts polyamide wax anti-settling agent, and 40-60 parts solvent; The preparation method of the hydrotalcite-coated zinc stannate composite material includes: (1) calcining magnesium aluminum hydrotalcite at 400-500℃ for 4-5h and then grinding it to obtain magnesium aluminum mixed metal oxide; (2) dissolving SnCl2·2H2O and ZnSO4·7H2O together in deionized water to prepare a mixed salt solution; slowly adding hydrogen peroxide to the mixed salt solution; and adding the magnesium aluminum mixed metal oxide to the solution and ultrasonically dispersing it to form a suspension; (3) adjusting the pH of the suspension system to 11.5±0.1 with alkali solution, and then carrying out a hydrothermal reaction, centrifuging, washing, and drying to obtain the final product.

2. The oil-based fire-retardant coating according to claim 1, characterized in that, The hydrogen peroxide concentration is 25-35 wt%, and the ratio of magnesium-aluminum mixed metal oxide, SnCl2·2H2O, ZnSO4·7H2O, deionized water and hydrogen peroxide is 9-11 g: 6-8 g: 8-10 g: 450-550 mL: 10-13 mL.

3. The oil-based fire-retardant coating according to claim 1, characterized in that, The hydrothermal reaction conditions are as follows: the hydrothermal reaction is carried out at a temperature of 115-125℃ for 10-11 hours.

4. The oil-based fire-retardant coating according to claim 1, characterized in that, The preparation method of the silane coupling agent modified ammonium polyphosphate includes: adding ammonium polyphosphate powder to a first anhydrous ethanol, and mechanically stirring and dispersing it at 300-500 rpm for 0.5-1.5 hours at room temperature to obtain a uniformly dispersed ammonium polyphosphate suspension; adding the silane coupling agent to a mixed solvent composed of a second anhydrous ethanol and deionized water, and adjusting the pH of the mixed system to 4-6 using glacial acetic acid, and performing pre-hydrolysis at 200-300 rpm for 20-40 minutes to obtain a silane hydrolysate; slowly adding the silane hydrolysate dropwise to the ammonium polyphosphate suspension under stirring, and then heating and stirring the mixed system; after the reaction is completed, separating the product by vacuum filtration, washing it 2-3 times with anhydrous ethanol, and vacuum drying it at 80-100℃ for 4-6 hours to obtain the silane coupling agent modified ammonium polyphosphate.

5. The oil-based fire-retardant coating according to claim 4, characterized in that, The temperature after heating is 55-65℃, and the stirring time is 2-4 hours.

6. The oil-based fire-retardant coating according to claim 4, characterized in that, The silane coupling agent is octyltriethoxysilane; the ratio of the amount of ammonium polyphosphate powder, first anhydrous ethanol, silane coupling agent, second anhydrous ethanol, and deionized water is 1g:16-20mL:0.08-0.15g:4-6mL:0.1-0.2mL.

7. The oil-based fire-retardant coating according to claim 1, characterized in that, The dispersant is BYK110; the leveling agent is polyether-modified polydimethylsiloxane; the solvent includes xylene, n-butanol and propylene glycol methyl ether acetate in a weight ratio of 3-5:1:

1.

8. A method for preparing an oil-based fire-retardant coating according to any one of claims 1-7, characterized in that, The steps include: S1. Mix 50%-55% of the total solvent with all the dispersant and stir at 400-600 rpm until homogeneous. First, add the hydrotalcite-coated zinc stannate composite material and boron nitride, and disperse at 1000-1200 rpm for 15-20 minutes until initially homogeneous. Then add the silane coupling agent-modified ammonium polyphosphate, pentaerythritol, and zinc borate, and disperse at 800-1000 rpm for 10-15 minutes to obtain a homogeneous slurry A. S2. Stir the remaining solvent at 400-600 rpm. First, add the silicone-modified acrylic resin and stir for 10 minutes until it is completely dissolved. Then, add the modified epoxy resin and continue stirring for 15-20 minutes until it is completely dissolved and homogeneous, to obtain transparent resin liquid B. Next, while stirring at 300-400 rpm, slowly add slurry A to resin liquid B. After the addition is complete, increase the speed to 600-800 rpm and continue stirring for 10-15 minutes to initially mix it evenly. Then, transfer the mixture to a sand mill and grind it until the fineness is ≤40μm to obtain base slurry C. S4. First, add the leveling agent to the base slurry C at 300-400 rpm and stir for 5 minutes; then slowly add the polyamide wax anti-settling agent to ensure uniform dispersion; after curing, filter with a 150-250 mesh screen to obtain the oil-based fireproof coating.

9. The method for preparing the oil-based fire-retardant coating according to claim 8, characterized in that, The maturation process involves continuous stirring at 200-300 rpm for 30-40 minutes.

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