Flame-retardant self-repairing water-based paint and preparation method thereof

Abstract

The application provides a kind of fire-retardant self-repairing water-based paint and its preparation method, fire-retardant self-repairing water-based paint is prepared from polyurethane emulsion and core-shell structure fire-retardant self-repairing filler;Core-shell structure fire-retardant self-repairing filler is with styrene as shell, polyimide aerogel as core;Styrene shell is loaded with nano titanium dioxide particles, and polyimide aerogel absorbs air-drying alkyd resin.The application uses ultraviolet irradiation when the coating is first scratched or damaged, photocatalytic nano titanium dioxide catalyzes the degradation of styrene shell, makes it break and release air-drying alkyd resin, reacts with air to form film, and repairs the damaged place in time;When the coating is scratched or damaged for the second or third time, use a hair dryer to heat the polyimide aerogel, which will cause the adsorption capacity of air-drying alkyd resin to decrease, and the air-drying alkyd resin will overflow to continue repairing the coating, achieving the effect of sustainable multiple repairs of the coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building coatings, in particular to a fire-retardant self-repairing water-based coating and a preparation method thereof. BACKGROUND

[0002] At present, the use of coatings is closely related to the interface, and the coating is a multi-component system, including resin (base material), pigment and filler, solvent and additive, etc. There are many interfaces in the system, especially between the pigment and filler and the resin, solvent; at the same time, the coating is a semi-finished product, which must be coated on the workpiece, product, structure, etc. to provide protection, decoration, function, etc. Therefore, there must be a certain interface state, and at the same time, it also puts forward certain requirements for the use of the coating. In addition, after the coating is applied, there is a drying and curing process, in which the contact between the coating film (wet) surface and the air must be considered to ensure that a good coating film appearance can be provided and surface defects can be prevented.

[0003] Wood products are prone to cause fire due to their low ignition point and flammable characteristics. In order to avoid this disadvantage, the current method mainly adds fire-retardant chemicals or applies fire-retardant coatings to the wood. However, the existing fire-retardant coatings cannot effectively protect the wood products from heat, have no smoke prevention effect, and even some fire-retardant materials release toxic gases containing halogen when they are decomposed. Moreover, when the fire-retardant coating building materials are damaged and peeled off during use, the fire-retardant effect will be lost. At the same time, the existing fire-retardant coatings cannot meet the production needs of the assembly line. Therefore, in order to ensure and improve the fire-retardant and repair effects of the coating film and make it have a longer service life, the existing technology must be improved. SUMMARY

[0004] The technical problem to be solved: In order to solve the technical problem that the fire-retardant effect will be lost when the coating of the building material is damaged and peeled off during use, a fire-retardant self-repairing filler with a core-shell structure is added, the shell is made of styrene, and the core is made of polyimide aerogel; the nano titanium dioxide particles are loaded on the styrene shell, and the gas-drying alkyd resin is adsorbed in the polyimide aerogel. When the coating is damaged for the first time, ultraviolet light is used to irradiate and photocatalyze the nano titanium dioxide on the styrene shell to catalyze the degradation of the styrene shell, so that it is broken to release the gas-drying alkyd resin, which reacts with the air to form a film and timely repair the damaged part, so that the damaged part of the coating will not continue to extend; when the coating is damaged for the second time or the third time, a hot air blower is used to heat the polyimide aerogel to make its temperature rise and the adsorption amount of the gas-drying alkyd resin decrease, so that the gas-drying alkyd resin overflows to continue to repair the coating, realizing the sustainable and multiple repair effect of the coating.

[0005] Technical scheme: A fire-retardant self-repairing water-based coating is prepared from a polyurethane emulsion and a fire-retardant self-repairing filler with a core-shell structure.

[0006] The core-shell structured flame-retardant self-healing filler uses styrene as the shell and polyimide aerogel as the core; nano-titanium dioxide particles are loaded on the styrene shell, and air-drying alkyd resin is adsorbed in the polyimide aerogel.

[0007] Furthermore, the flame-retardant self-healing filler of the core-shell structure has a particle size of 1-20 μm.

[0008] Furthermore, the adsorption capacity of the polyimide aerogel for the air-drying alkyd resin decreases with increasing temperature.

[0009] Furthermore, the flame-retardant self-healing water-based coating is composed of the following components in weight percentages:

[0010]

[0011] The polyurethane emulsion is a silicone-modified polyurethane emulsion.

[0012] Furthermore, the preparation steps of the core-shell structured flame-retardant self-healing filler are as follows:

[0013] S1: Add 10 mL of thionyl chloride to 1.28 g of polyimide containing carboxylic acid side groups, reflux for 0.5 h, reduce pressure and gradually heat to 150 °C; add 0.18 g of terminal aminopropyl polydimethylsiloxane, 0.32 g of aminopropyltrimethoxysilane, 0.20 g of triethylamine, 15 mL of N,N-dimethylformamide and 15 mL of tetrahydrofuran, stir the reaction for 30 min, centrifuge to obtain the solution;

[0014] S2: Add 0.16g water, 0.015g HCl, 7.5mL N,N-dimethylformamide and 7.5mL tetrahydrofuran to the solution, stir rapidly for 3min and let stand for 3d. Take out the gel formed, replace it twice with a mixed solvent of N,N-dimethylformamide and tetrahydrofuran in a volume ratio of 1:1, and then replace it four times with tert-butanol.

[0015] S3: Freeze at -25℃, then dry and crush using a freeze dryer to obtain polyimide aerogel;

[0016] S4: Impregnate the polyimide aerogel in an air-drying alkyd resin for adsorption until saturation;

[0017] S5: Remove and dry at a low temperature of 20-30℃ to obtain polyimide aerogel that has adsorbed air-drying alkyd resin;

[0018] S6: Take 800g of styrene monomer and 6g of azobisisobutyronitrile, mix them, stir and dissolve them by ultrasonication, add 50-100g of nano titanium dioxide, stir evenly, and obtain a mixed dispersion containing nano titanium dioxide.

[0019] S7: The polyimide aerogel adsorbed with air-drying alkyd resin is impregnated in a mixed dispersion containing nano-titanium dioxide, sealed, and reacted in a vacuum drying oven at 70°C for 18 hours and then at 80°C for 18 hours to obtain a core-shell structured flame-retardant self-healing filler. Further, the mass-to-volume ratio of the polyimide aerogel adsorbed with air-drying alkyd resin and the mixed dispersion containing nano-titanium dioxide in S7 is 20 g:(3-5) mL.

[0020] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0021] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product;

[0022] Step 2: Curing with a hot air gun;

[0023] Step 3: Finished product packaging on the assembly line.

[0024] Furthermore, the coating method includes roller coating, electrostatic spraying, vacuum spraying, curtain coating, dip coating, spin coating, and suction coating.

[0025] Furthermore, in step 2, the curing temperature is 50-60℃ and the curing time is 30-40s.

[0026] Beneficial effects:

[0027] 1. The flame-retardant self-healing waterborne coating of the present invention is prepared using a flame-retardant self-healing filler with a core-shell structure, with styrene as the shell and polyimide aerogel as the core. Nano-titanium dioxide particles are loaded on the styrene shell, and air-drying alkyd resin is adsorbed in the polyimide aerogel. When the coating is scratched or damaged for the first time, ultraviolet irradiation is used to photocatalyze the degradation of the styrene shell by the nano-titanium dioxide on the styrene shell, causing it to break and release air-drying alkyd resin, which reacts with air to form a film, repairing the damaged area in time and preventing the crack from extending further. When the coating is scratched or damaged a second or third time, a hot air blower is used to heat the polyimide aerogel, increasing the temperature and reducing the adsorption of air-drying alkyd resin, causing the resin to overflow and continue to repair the coating, achieving a sustainable multiple repair effect.

[0028] 2. This invention uses a flame-retardant self-healing filler with a core-shell structure to coat styrene onto the outer layer of a polyimide aerogel that has adsorbed air-drying alkyd resin, thereby achieving initial protection of the polyimide aerogel and preventing the air-drying alkyd resin in the polyimide aerogel from overflowing during the curing process of the coating using a hot air blower.

[0029] 3. When the present invention is exposed to fire and burns, as the temperature rises, the polyimide aerogel melts to form a fluid, which forms an interpenetrating network with the organosilicon-modified polyurethane, and finally forms a dense char layer, improving the flame retardant performance. At the same time, the nano-titanium dioxide particles on the styrene shell can enter the pores of the char layer, further isolating the air and promoting the organosilicon-modified polyurethane to produce a denser char layer, reducing the toxic fumes produced during combustion.

[0030] 4. The flame-retardant self-healing water-based coating of this invention uses polyimide aerogel, which has good heat insulation effect, can delay or prevent the spread of fire, block heat conduction, and increase the heat insulation effect. Detailed Implementation

[0031] Example 1

[0032] The preparation steps of a core-shell structured flame-retardant self-healing filler are as follows:

[0033] S1: Add 1L of thionyl chloride to 128g of polyimide containing carboxylic acid side groups, reflux for 0.5h, reduce pressure and gradually heat to 150℃; add 18g of terminal aminopropyl polydimethylsiloxane, 32g of aminopropyltrimethoxysilane, 20g of triethylamine, 1.5L of N,N-dimethylformamide and 1.5L of tetrahydrofuran, stir the reaction for 30min, centrifuge to obtain the solution;

[0034] S2: Add 16 mL of water, 1.5 g of HCl, 750 mL of N,N-dimethylformamide and 750 mL of tetrahydrofuran to the solution, stir rapidly for 3 min and let stand for 3 days. Take out the gel formed and replace it twice with a mixed solvent of N,N-dimethylformamide and tetrahydrofuran in a volume ratio of 1:1, and then replace it four times with tert-butanol.

[0035] S3: Freeze at -25℃, then dry and crush using a freeze dryer to obtain polyimide aerogel;

[0036] S4: Impregnate the polyimide aerogel in an air-drying alkyd resin for adsorption until saturation;

[0037] S5: Remove and dry at a low temperature of 25°C to obtain polyimide aerogel that has adsorbed air-drying alkyd resin.

[0038] S6: Take 800g of styrene monomer and 6g of azobisisobutyronitrile, mix them, and sonicate them to dissolve. Add 50g of nano titanium dioxide and stir evenly to obtain a mixed dispersion containing nano titanium dioxide.

[0039] S7: 20g of polyimide aerogel that has been adsorbed with air-drying alkyd resin was impregnated in 4mL of a mixed dispersion containing nano-titanium dioxide, sealed, and reacted in a vacuum drying oven at 70℃ for 18h and then at 80℃ for 18h to obtain a core-shell structured flame-retardant self-healing filler.

[0040] Example 2

[0041] The preparation steps of a core-shell structured flame-retardant self-healing filler are as follows:

[0042] S1: Add 1L of thionyl chloride to 128g of polyimide containing carboxylic acid side groups, reflux for 0.5h, reduce pressure and gradually heat to 150℃; add 18g of terminal aminopropyl polydimethylsiloxane, 32g of aminopropyltrimethoxysilane, 20g of triethylamine, 1.5L of N,N-dimethylformamide and 1.5L of tetrahydrofuran, stir the reaction for 30min, centrifuge to obtain the solution;

[0043] S2: Add 16 mL of water, 1.5 g of HCl, 750 mL of N,N-dimethylformamide and 750 mL of tetrahydrofuran to the solution, stir rapidly for 3 min and let stand for 3 days. Take out the gel formed and replace it twice with a mixed solvent of N,N-dimethylformamide and tetrahydrofuran in a volume ratio of 1:1, and then replace it four times with tert-butanol.

[0044] S3: Freeze at -25℃, then dry and crush using a freeze dryer to obtain polyimide aerogel;

[0045] S4: Impregnate the polyimide aerogel in an air-drying alkyd resin for adsorption until saturation;

[0046] S5: Remove and dry at a low temperature of 25°C to obtain polyimide aerogel that has adsorbed air-drying alkyd resin.

[0047] S6: Take 800g of styrene monomer and 6g of azobisisobutyronitrile, mix them, and dissolve them by ultrasonic stirring. Add 80g of nano titanium dioxide and stir evenly to obtain a mixed dispersion containing nano titanium dioxide.

[0048] S7: 20g of polyimide aerogel that has been adsorbed with air-drying alkyd resin was impregnated in 4mL of a mixed dispersion containing nano-titanium dioxide, sealed, and reacted in a vacuum drying oven at 70℃ for 18h and then at 80℃ for 18h to obtain a core-shell structured flame-retardant self-healing filler.

[0049] Example 3

[0050] The preparation steps of a core-shell structured flame-retardant self-healing filler are as follows:

[0051] S1: Add 1L of thionyl chloride to 128g of polyimide containing carboxylic acid side groups, reflux for 0.5h, reduce pressure and gradually heat to 150℃; add 18g of terminal aminopropyl polydimethylsiloxane, 32g of aminopropyltrimethoxysilane, 20g of triethylamine, 1.5L of N,N-dimethylformamide and 1.5L of tetrahydrofuran, stir the reaction for 30min, centrifuge to obtain the solution;

[0052] S2: Add 16 mL of water, 1.5 g of HCl, 750 mL of N,N-dimethylformamide and 750 mL of tetrahydrofuran to the solution, stir rapidly for 3 min and let stand for 3 days. Take out the gel formed and replace it twice with a mixed solvent of N,N-dimethylformamide and tetrahydrofuran in a volume ratio of 1:1, and then replace it four times with tert-butanol.

[0053] S3: Freeze at -25℃, then dry and crush using a freeze dryer to obtain polyimide aerogel;

[0054] S4: Impregnate the polyimide aerogel in an air-drying alkyd resin for adsorption until saturation;

[0055] S5: Remove and dry at a low temperature of 25°C to obtain polyimide aerogel that has adsorbed air-drying alkyd resin.

[0056] S6: Take 800g of styrene monomer and 6g of azobisisobutyronitrile, mix them, stir and dissolve them by ultrasonication, add 100g of nano titanium dioxide, stir evenly, and obtain a mixed dispersion containing nano titanium dioxide.

[0057] S7: 20g of polyimide aerogel that has been adsorbed with air-drying alkyd resin was impregnated in 4mL of a mixed dispersion containing nano-titanium dioxide, sealed, and reacted in a vacuum drying oven at 70℃ for 18h and then at 80℃ for 18h to obtain a core-shell structured flame-retardant self-healing filler.

[0058] Comparative Example 1

[0059] The difference between this embodiment and Embodiment 2 is that the polyimide aerogel is not hydrophobically modified, as detailed below:

[0060] The preparation steps of a core-shell structured flame-retardant self-healing filler are as follows:

[0061] S1: Add 1L of thionyl chloride to 128g of polyimide containing carboxylic acid side groups, reflux for 0.5h, reduce pressure and gradually heat to 150℃; add 20g of triethylamine, 1.5L of N,N-dimethylformamide and 1.5L of tetrahydrofuran, stir the reaction for 30min, centrifuge to obtain the solution;

[0062] S2: Add 16 mL of water, 1.5 g of HCl, 750 mL of N,N-dimethylformamide and 750 mL of tetrahydrofuran to the solution, stir rapidly for 3 min and let stand for 3 days. Take out the gel formed and replace it twice with a mixed solvent of N,N-dimethylformamide and tetrahydrofuran in a volume ratio of 1:1, and then replace it four times with tert-butanol.

[0063] S3: Freeze at -25℃, then dry and crush using a freeze dryer to obtain polyimide aerogel;

[0064] S4: Impregnate the polyimide aerogel in an air-drying alkyd resin for adsorption until saturation;

[0065] S5: Remove and dry at a low temperature of 25°C to obtain polyimide aerogel that has adsorbed air-drying alkyd resin.

[0066] S6: Take 800g of styrene monomer and 6g of azobisisobutyronitrile, mix them, and dissolve them by ultrasonic stirring. Add 80g of nano titanium dioxide and stir evenly to obtain a mixed dispersion containing nano titanium dioxide.

[0067] S7: 20g of polyimide aerogel that has been adsorbed with air-drying alkyd resin was impregnated in 4mL of a mixed dispersion containing nano-titanium dioxide, sealed, and reacted in a vacuum drying oven at 70℃ for 18h and then at 80℃ for 18h to obtain a core-shell structured flame-retardant self-healing filler.

[0068] The adsorption capacity of polyimide aerogel for air-drying alkyd resin in Example 2 was measured at different temperatures, and the results are shown in Table 1:

[0069] Table 1

[0070]

[0071] As can be seen from Table 1, the adsorption capacity of polyimide aerogel for air-drying alkyd resin decreases with increasing temperature. This means that high-temperature heating can cause air-drying alkyd resin to overflow from the polyimide aerogel.

[0072] Example 4

[0073] A flame-retardant self-healing waterborne coating is composed of the following components in weight percentage: 50% silicone-modified polyurethane emulsion, 20% flame-retardant self-healing filler with a core-shell structure and a particle size of 1-20 μm prepared in Example 2, 8% BYK-192 (a chemical product of BYK Corporation), 3% BYK-022 (a chemical product of BYK Corporation), and the balance being purified water.

[0074] Mix all ingredients together to obtain a self-healing flame-retardant water-based coating.

[0075] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0076] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product by roller coating to a thickness of 150μm;

[0077] Step 2: Curing is performed using a hot air gun at a temperature of 50°C for 40 seconds.

[0078] Step 3: Finished product packaging on the assembly line.

[0079] Example 5

[0080] A flame-retardant self-healing waterborne coating is composed of the following components in weight percentage: 50% silicone-modified polyurethane emulsion, 25% flame-retardant self-healing filler with a core-shell structure and a particle size of 1-20 μm prepared in Example 2, 8% dispersant BYK-192 (a chemical product of BYK Company), 3% BYK-022 (a chemical product of BYK Company), and the balance being purified water.

[0081] Mix all ingredients together to obtain a self-healing flame-retardant water-based coating.

[0082] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0083] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product by roller coating to a thickness of 150μm;

[0084] Step 2: Curing is performed using a hot air gun at a temperature of 50°C for 40 seconds.

[0085] Step 3: Finished product packaging on the assembly line.

[0086] Example 6

[0087] A flame-retardant self-healing waterborne coating is composed of the following components in weight percentage: 50% silicone-modified polyurethane emulsion, 30% flame-retardant self-healing filler with a core-shell structure and a particle size of 1-20 μm prepared in Example 2, 8% dispersant BYK-192 (a chemical product of BYK Company), 3% BYK-022 (a chemical product of BYK Company), and the balance being purified water.

[0088] Mix all ingredients together to obtain a self-healing flame-retardant water-based coating.

[0089] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0090] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product by roller coating to a thickness of 150μm;

[0091] Step 2: Curing is performed using a hot air gun at a temperature of 50°C for 40 seconds.

[0092] Step 3: Finished product packaging on the assembly line.

[0093] Example 7

[0094] A flame-retardant self-healing waterborne coating is composed of the following components in weight percentage: 50% silicone-modified polyurethane emulsion, 25% flame-retardant self-healing filler with a core-shell structure and a particle size of 1-20 μm prepared in Example 2, 8% dispersant BYK-192 (a chemical product of BYK Company), 3% BYK-022 (a chemical product of BYK Company), and the balance being purified water.

[0095] Mix all ingredients together to obtain a self-healing flame-retardant water-based coating.

[0096] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0097] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product by roller coating to a thickness of 100μm;

[0098] Step 2: Curing is performed using a hot air gun at a temperature of 50°C for 40 seconds.

[0099] Step 3: Finished product packaging on the assembly line.

[0100] Example 8

[0101] A flame-retardant self-healing waterborne coating is composed of the following components in weight percentage: 50% silicone-modified polyurethane emulsion, 25% flame-retardant self-healing filler with a core-shell structure and a particle size of 1-20 μm prepared in Example 2, 8% dispersant BYK-192 (a chemical product of BYK Company), 3% BYK-022 (a chemical product of BYK Company), and the balance being purified water.

[0102] Mix all ingredients together to obtain a self-healing flame-retardant water-based coating.

[0103] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0104] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product by roller coating to a thickness of 200μm;

[0105] Step 2: Curing is performed using a hot air gun at a temperature of 50°C for 40 seconds.

[0106] Step 3: Finished product packaging on the assembly line.

[0107] Example 9

[0108] A flame-retardant self-healing waterborne coating is composed of the following components in weight percentage: 50% silicone-modified polyurethane emulsion, 25% flame-retardant self-healing filler with a core-shell structure and a particle size of 1-20 μm prepared in Example 1, 8% dispersant BYK-192 (a chemical product of BYK Company), 3% BYK-022 (a chemical product of BYK Company), and the balance being purified water.

[0109] Mix all ingredients together to obtain a self-healing flame-retardant water-based coating.

[0110] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0111] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product by roller coating to a thickness of 150μm;

[0112] Step 2: Curing is performed using a hot air gun at a temperature of 50°C for 40 seconds.

[0113] Step 3: Finished product packaging on the assembly line.

[0114] Example 10

[0115] A flame-retardant self-healing waterborne coating is composed of the following components in weight percentage: 50% silicone-modified polyurethane emulsion, 25% flame-retardant self-healing filler with a core-shell structure and a particle size of 1-20 μm prepared in Example 3, 8% dispersant BYK-192 (a chemical product of BYK Company), 3% BYK-022 (a chemical product of BYK Company), and the balance being purified water.

[0116] Mix all ingredients together to obtain a self-healing flame-retardant water-based coating.

[0117] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0118] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product by roller coating to a thickness of 150μm;

[0119] Step 2: Curing is performed using a hot air gun at a temperature of 50°C for 40 seconds.

[0120] Step 3: Finished product packaging on the assembly line.

[0121] Comparative Example 2

[0122] The difference between this comparative example and Example 5 is the direct addition of air-drying alkyd resin self-healing microcapsules, as detailed below:

[0123] A flame-retardant self-healing waterborne coating is composed of the following components in weight percentage: 50% silicone-modified polyurethane emulsion, 25% air-drying alkyd resin self-healing microcapsules, 8% dispersant BYK-192 (BYK chemical product), 3% BYK-022 (BYK chemical product), and the balance being purified water.

[0124] The preparation method of air-drying alkyd resin self-healing microcapsules is as follows: 10g of gelatin solution and 20g of air-drying alkyd resin are added to a reaction vessel and stirred for 90min at 400r / min and 60℃. 3g of sodium sulfate solution is added, and stirring is continued for 30min under ice-water bath conditions. 3g of glutaraldehyde is added, and stirring is continued for 3min. After standing for 10min, the mixture is filtered and dried to obtain the final product. All components are mixed and stirred to obtain a self-healing flame-retardant waterborne coating.

[0125] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0126] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product by roller coating to a thickness of 150μm;

[0127] Step 2: Curing is performed using a hot air gun at a temperature of 50°C for 40 seconds.

[0128] Step 3: Finished product packaging on the assembly line.

[0129] Comparative Example 3

[0130] The difference between this comparative example and Example 5 is that it uses a flame-retardant self-healing filler with a core-shell structure and a particle size of 1-20 μm prepared in Comparative Example 1, as detailed below:

[0131] A flame-retardant self-healing waterborne coating is composed of the following components in weight percentage: 50% silicone-modified polyurethane emulsion, 25% flame-retardant self-healing filler with a core-shell structure and a particle size of 1-20 μm prepared in Comparative Example 1, 8% BYK-192 (a chemical product of BYK Corporation), 3% BYK-022 (a chemical product of BYK Corporation), and the balance being purified water.

[0132] Mix all ingredients together to obtain a self-healing flame-retardant water-based coating.

[0133] The application method of the above-mentioned flame-retardant self-healing water-based coating includes the following steps:

[0134] Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product by roller coating to a thickness of 150μm;

[0135] Step 2: Curing is performed using a hot air gun at a temperature of 50°C for 40 seconds.

[0136] Step 3: Finished product packaging on the assembly line.

[0137] The self-healing performance of embodiments of the present invention was measured:

[0138] Self-healing performance test: First scratch: The coating was scratched with a scalpel blade, and the scratched coating was irradiated with ultraviolet light for 10 hours. The wound healing status was observed using an optical microscope. Second scratch: The coating was scratched with a scalpel blade, and the scratched coating was heated to 80℃ with a hot air gun for 40 minutes. The wound healing status was observed using an optical microscope. Third scratch: The coating was scratched with a scalpel blade, and the scratched coating was heated to 120℃ with a hot air gun for 40 minutes. The wound healing status was observed using an optical microscope. The results are shown in Table 2 below.

[0139] Table 2

[0140]

[0141] The flame retardant properties of embodiments of the present invention were measured:

[0142] According to GB / T2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics", the limiting oxygen index (LOI) was tested to evaluate the flame retardant performance of the material.

[0143] The heat release performance of flame-retardant poplar plywood was tested using a cone calorimeter in accordance with ISO 5660 standard. The sample size was 100mm × 100mm × 3mm, and the radiation intensity was 35kW / m². 2 .

[0144] The results are shown in Table 3 below:

[0145] Table 3

[0146]

Claims

1. A flame-retardant, self-healing water-based coating, characterized in that: It is prepared from polyurethane emulsion and core-shell structured flame-retardant self-healing filler; The core-shell structured flame-retardant self-healing filler uses styrene as the shell and polyimide aerogel as the core; nano-titanium dioxide particles are loaded on the styrene shell, and air-drying alkyd resin is adsorbed in the polyimide aerogel. The preparation steps of the core-shell structured flame-retardant self-healing filler are as follows: S1: Add 10 mL of thionyl chloride to 1.28 g of polyimide containing carboxylic acid side groups, reflux for 0.5 h, reduce pressure and gradually heat to 150 °C; add 0.18 g of terminal aminopropyl polydimethylsiloxane, 0.32 g of aminopropyltrimethoxysilane, 0.20 g of triethylamine, 15 mL of N,N-dimethylformamide and 15 mL of tetrahydrofuran, stir the reaction for 30 min, centrifuge to obtain the solution; S2: Add 0.16g water, 0.015g HCl, 7.5mL N,N-dimethylformamide and 7.5mL tetrahydrofuran to the solution, stir rapidly for 3min and let stand for 3d. Take out the gel formed, replace it twice with a mixed solvent of N,N-dimethylformamide and tetrahydrofuran in a volume ratio of 1:1, and then replace it four times with tert-butanol. S3: Freeze at -25℃, then dry and crush using a freeze dryer to obtain polyimide aerogel; S4: Impregnate the polyimide aerogel in an air-drying alkyd resin for adsorption until saturation; S5: Remove and dry at a low temperature of 20-30℃ to obtain polyimide aerogel that has adsorbed air-drying alkyd resin; S6: Take 800g of styrene monomer and 6g of azobisisobutyronitrile, mix them, stir and dissolve them by ultrasonication, add 50-100g of nano titanium dioxide, stir evenly, and obtain a mixed dispersion containing nano titanium dioxide. S7: The polyimide aerogel that has been adsorbed with air-drying alkyd resin is impregnated in a mixed dispersion containing nano-titanium dioxide, sealed, and reacted in a vacuum drying oven at 70°C for 18 hours and at 80°C for 18 hours to obtain a core-shell structured flame-retardant self-healing filler. The mass-to-volume ratio of the polyimide aerogel containing air-drying alkyd resin and the mixed dispersion containing nano-titanium dioxide in S7 is 20 g: (3-5) mL.

2. The flame-retardant self-healing water-based coating according to claim 1, characterized in that: The flame-retardant self-healing filler of the core-shell structure has a particle size of 1-20 μm.

3. The flame-retardant self-healing water-based coating according to claim 1, characterized in that: The adsorption capacity of the polyimide aerogel for the air-drying alkyd resin decreases with increasing temperature.

4. The flame-retardant self-healing water-based coating according to claim 1, characterized in that: It consists of the following components in the following weight percentages: Polyurethane emulsion 40%–50% Flame-retardant self-healing filler with core-shell structure: 20%–30% Dispersant BYK-192 5%~10% Defoamer 1%–5% Remaining purified water; The polyurethane emulsion is a silicone-modified polyurethane emulsion.

5. The method of using a flame-retardant self-healing water-based coating according to any one of claims 1-4, characterized in that: Includes the following steps: Step 1: Apply flame-retardant self-healing water-based coating to the surface of the wood product; Step 2: Curing with a hot air gun; Step 3: Finished product packaging on the assembly line.

6. The method of using a flame-retardant self-healing water-based coating according to claim 5, characterized in that: The coating methods include roller coating, electrostatic spraying, vacuum spraying, curtain coating, dip coating, spin coating, and suction coating.

7. The method of using a flame-retardant self-healing water-based coating according to claim 5, characterized in that: In step 2, the curing temperature is 50-60℃ and the curing time is 30-40s.

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