Waterborne polyurethane flame-retardant coating as well as preparation method and application thereof

Abstract

The invention discloses a waterborne polyurethane flame-retardant coating as well as a preparation method and application thereof. According to the coating, a flame retardant emulsion containing alkyl phosphinate is adopted as a flame retardant component, the flame retardant emulsion further comprises a dispersing agent and an anti-settling agent, and the dispersing agent is composed of a nonionic dispersing agent and an anionic dispersing agent; the nonionic dispersant, the anionic dispersant, and the anti-settling agent are specific types. By selecting specific types of nonionic dispersing agent, anionic dispersing agent and anti-settling agent and controlling the mass ratio of the nonionic dispersing agent to the anionic dispersing agent, the flame retardant emulsion is stable and does not agglomerate in the coating, so that the coating is high in stability and can maintain a stable and uniform emulsion state after being stored for a long time, and the flame retardant performance is improved. And the coating has excellent flame retardant property after long-term storage, still has excellent flame retardant property after water washing, and can be used in the field of flame retardant textiles with high requirements on flame retardant property after water washing.

Description

Technical Field

[0001] This invention relates to a waterborne polyurethane flame-retardant coating, its preparation method, and its application. Background Technology

[0002] Waterborne polyurethane coatings are characterized by their environmental friendliness, high strength, high weather resistance, and corrosion resistance, making them widely used in industry, particularly in the automotive, furniture, outdoor construction, and apparel sectors. However, waterborne polyurethane has a limiting oxygen index (LOI) of only 18%, classifying it as a flammable polymer. This limitation restricts its application in certain fields, and flame-retardant modification is typically performed for practical applications.

[0003] Patent CN118165636A discloses a ceramizable polyurethane fire-retardant coating, composed of component A and component B. Component A includes polyols, chain extenders, flame-retardant powders, etc., while component B is isocyanate. The flame-retardant powder is composed of organic phosphonates, phosphates, and borates in a mass ratio of (4-11):(25-35):(15-27). Although this coating has excellent flame-retardant properties, it is prone to demulsification due to the aggregation of hydrophobic organic phosphonates, making long-term stable storage impossible.

[0004] When waterborne polyurethane flame-retardant coatings are applied to the textile industry, a key challenge arises: washability. Textile products require multiple washes, and the flame-retardant properties of conventional waterborne polyurethane coatings often decrease significantly after washing, failing to meet flame-retardant standards. This is because if the polyurethane coating uses hydrophilic flame retardants, they are easily detached during washing, leading to a decline in flame-retardant performance. Conversely, if the coating uses hydrophobic flame retardants, such as aluminum diethylphosphinate, they are difficult to disperse in waterborne coatings and tend to agglomerate, typically forming large particles. These coarse particles have weak bonding to the polymer matrix and are easily detached and washed away during water rinsing, resulting in reduced flame-retardant efficiency and failure to meet flame-retardant requirements after washing. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing technologies, this invention provides an improved waterborne polyurethane flame-retardant coating. This flame-retardant coating exhibits high stability, maintaining a stable and uniform emulsion state even after prolonged storage. Furthermore, the coating demonstrates excellent flame-retardant properties after long-term storage and retains these properties even after water washing.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A waterborne polyurethane flame-retardant coating, comprising a waterborne polyurethane resin and a flame-retardant emulsion; the flame-retardant emulsion comprising alkyl phosphonates, a dispersant, an anti-settling agent, and water; the dispersant comprising a nonionic dispersant and an anionic dispersant; the nonionic dispersant being selected from one or more combinations of alkylphenol polyoxyethylene ethers, dodecyl glycosides, Tween compounds, and fatty alcohol polyoxyethylene ethers; the anionic dispersant being selected from one or more combinations of sodium polyacrylate, sodium dioctyl succinate sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate; the mass ratio of the anionic dispersant to the nonionic dispersant being 1:1-9; the anti-settling agent being selected from one or more combinations of organobentonite, modified hydrogenated castor oil, polyamide wax, fumed silica, and sodium carboxymethyl cellulose; and the sodium polyacrylate having a weight-average molecular weight of 2000-1000000.

[0007] In this invention, the waterborne polyurethane resin can be of conventional types, such as various commercially available waterborne polyurethane coatings, and this invention does not impose any particular limitation on its type. Organo-bentonite refers to bentonite modified with organic matter, such as products obtained by intercalation modification of bentonite with organic matter, etc., where the organic matter can be, for example, a hydrophilic organic matter. Modified hydrogenated castor oil refers to products modified with hydrogenated castor oil. Both are known substances.

[0008] In this invention, by adding a specific flame retardant emulsion to an aqueous polyurethane flame retardant coating, the emulsion contains an alkyl phosphonate flame retardant. Due to the use of specific components, such as specific nonionic dispersants, anionic dispersants, and anti-settling agents, and by controlling a specific mass ratio of nonionic and anionic dispersants, the emulsion of hydrophobic flame retardant can achieve long-term stability. The aqueous polyurethane flame retardant coating containing it is also stable during storage, and its flame retardant performance remains at a high level even after long-term storage and after washing with water.

[0009] In some embodiments, the organic bentonite is BP-188B modified bentonite.

[0010] In some embodiments, the modified hydrogenated castor oil is THIXATROL ST modified hydrogenated castor oil.

[0011] In some embodiments, the mass ratio of the anionic dispersant to the nonionic dispersant is 1:1-3.

[0012] In some embodiments, the alkylphosphines are selected from one or more combinations of the respective aluminum salts, zinc salts, magnesium salts, calcium salts, ferrous salts, and sodium salts.

[0013] In some embodiments, the alkyl group in the alkylphosphinate is selected from one or more combinations of straight-chain or branched C1-C6 alkyl groups and C4-C8 cycloalkyl groups.

[0014] In some embodiments, the alkyl phosphinate is selected from one or more combinations of aluminum diethylphosphinate, zinc dibutylphosphinate, aluminum diisobutylphosphinate, aluminum isobutylphosphinate, zinc methylethylphosphinate, zinc methylcyclohexylphosphinate, and aluminum monoethylphosphinate.

[0015] In some embodiments, the alkylphosphinate is selected from aluminum diethylphosphinate.

[0016] In some embodiments, the alkyl phosphonates have a D50 particle size of 1-35 micrometers and a D95 particle size of 5-55 micrometers. That is, the alkyl phosphonate flame retardants of the present invention can use particles with larger sizes.

[0017] In some embodiments, the flame retardant emulsion comprises, by weight, 20-80 parts of alkylphosphinate, 0.1-5 parts of antisettling agent, and 20-80 parts of water; the dispersant consists of 0.1-5 parts of nonionic dispersant and 0.1-5 parts of anionic dispersant.

[0018] In some embodiments, the flame retardant emulsion comprises, by weight, 50-70 parts of alkylphosphinate, 1-3 parts of antisettling agent, and 30-50 parts of water; the dispersant consists of 1-3 parts of nonionic dispersant and 0.5-2 parts of anionic dispersant.

[0019] In some embodiments, the flame retardant emulsion further includes a pH adjuster.

[0020] In some embodiments, the pH adjuster is selected from one or more combinations of ammonia, sodium hydroxide, and potassium hydroxide.

[0021] In some embodiments, the flame retardant emulsion comprises 0.1-10 parts by weight of the pH adjuster.

[0022] In some embodiments, the waterborne polyurethane flame-retardant coating further includes at least one of a defoamer, a leveling agent, a thickener, and a film-forming aid. These additives are commonly used in coatings. The thickener can further stabilize the stability of the flame-retardant emulsion in the waterborne polyurethane coating, further ensuring that the hydrophobic flame retardant does not agglomerate in the waterborne polyurethane coating, and ensuring that the coating does not break down.

[0023] In some embodiments, the defoamer is selected from one or more combinations of AFCONA-2505, AFCONA-2508, RH-9210, BYK-1710, and Sago-1900.

[0024] In some embodiments, the leveling agent is selected from one or more combinations of Deqian 810, HY-6410 and Synde-1248.

[0025] In some embodiments, the thickener is selected from one or more combinations of waterborne polyamide wax, montmorillonite, and organobentonite.

[0026] In some embodiments, the film-forming aid is selected from one or more combinations of propylene glycol butyl ether, dipropylene glycol methyl ether, and dipropylene glycol butyl ether.

[0027] In some embodiments, the waterborne polyurethane flame-retardant coating comprises, by weight, 40-60 parts of waterborne polyurethane resin, 35-55 parts of flame-retardant emulsion, 0.1-0.8 parts of defoamer, 0.2-1.0 parts of leveling agent, 0.3-1.2 parts of thickener, 0.5-1.5 parts of film-forming aid, and 1-8 parts of water. The waterborne polyurethane flame-retardant coating of the present invention may contain a high amount of flame-retardant emulsion, but the coating still remains stable.

[0028] This invention also provides a method for preparing the aforementioned waterborne polyurethane flame-retardant coating. The preparation method includes the following steps: 1) stirring and dispersing the nonionic dispersant, anionic dispersant, water, and alkyl phosphinate in the flame retardant emulsion to obtain a mixture; 2) adding the anti-settling agent and pH adjuster to the mixture, stirring and dispersing to obtain the flame retardant emulsion; 3) stirring and dispersing the waterborne polyurethane resin, leveling agent, film-forming aid, and part of the defoamer to obtain a first liquid; 4) adding the flame retardant emulsion and the remaining defoamer to the first liquid, stirring and dispersing to obtain a second liquid; 5) adding an aqueous dispersion of thickener to the second liquid, stirring and dispersing to obtain the waterborne polyurethane flame-retardant coating. This invention first prepares a flame retardant emulsion, then uses it as a flame retardant, mixing it with other components of the waterborne polyurethane flame-retardant coating.

[0029] In some implementations, steps 1) and 2) are both performed at 20-50°C.

[0030] In some embodiments, the stirring speed in step 1) is 500-8000 r / min.

[0031] In some embodiments, the stirring, mixing and dispersion time in step 1) is 10-200 min.

[0032] In some embodiments, the stirring speed in step 2) is 100-1500 r / min.

[0033] In some embodiments, the stirring and dispersion time in step 2) is 10-100 min.

[0034] In some embodiments, the stirring speed in step 3) is 800-1200 r / min.

[0035] In some embodiments, the stirring, mixing and dispersion time in step 3) is 20-40 minutes.

[0036] In some embodiments, the stirring speed in step 4) is 400-1000 r / min.

[0037] In some embodiments, the stirring, mixing and dispersion time in step 4) is 20-60 minutes.

[0038] In some embodiments, the stirring speed in step 5) is 200-500 r / min.

[0039] In some embodiments, the stirring and dispersion time in step 5) is 10-30 minutes.

[0040] The present invention also provides an application of the aforementioned waterborne polyurethane flame-retardant coating in textile coatings. The waterborne polyurethane flame-retardant coating of the present invention retains excellent flame-retardant properties even after long-term storage and washing, and therefore can be used in the textile industry where frequent washing is required.

[0041] Compared with the prior art, the present invention has the following advantages: The waterborne polyurethane coating of the present invention has good stability and retains emulsion stability after long-term storage. It also has excellent flame retardant properties, and the flame retardant properties remain excellent after the coating is washed. It can be used in the field of flame-retardant textiles where high flame retardancy after washing is required. Attached Figure Description

[0042] Figure 1 The appearance of the emulsion in Example 1 is shown in the diagrams, where a is the front view and b is the top view. Figure 2 For comparison, the appearance diagrams of Preparation Example 1 are shown, where a is the front view and b is the top view; Figure 3 For comparison, the appearance of preparation example 2 is shown, where a is the front view and b is the top view; Figure 4 In the diagram, a is a photograph showing the stability of the emulsion of Preparation Example 1 after 30 days; b is a photograph showing the stability of the emulsion of Comparative Preparation Example 3 after 30 days; c is a photograph showing the stability of the emulsion of Comparative Preparation Example 4 after 30 days; and d is a photograph showing the stability of the emulsion of Comparative Preparation Example 5 after 30 days.

[0043] Figure 5In the figures, a is a photograph of the waterborne polyurethane flame retardant coating of Example 1 after 7 days of storage; b is a photograph of the waterborne polyurethane flame retardant coating of Comparative Example 1 after 7 days of storage; c is a photograph of the waterborne polyurethane flame retardant coating of Comparative Example 2 after 7 days of storage; and d is a photograph of the waterborne polyurethane flame retardant coating of Comparative Example 4 after demulsification. Detailed Implementation

[0044] In existing technologies, oil-based halogen-free flame retardants such as aluminum diethylphosphonate can typically only be used in oil-based systems. Their structures contain numerous hydrophobic groups, making them difficult to disperse uniformly in aqueous systems. In aqueous systems, such as waterborne polyurethane coatings, they tend to agglomerate, failing to disperse and remain stable. This easily leads to demulsification and sedimentation in waterborne polyurethane coatings, resulting in their inability to be stored for long periods. However, in practical applications, coatings require storage and transportation. Therefore, the existing technology makes it difficult to industrialize hydrophobic flame retardants such as aluminum diethylphosphonate in waterborne polyurethane coatings.

[0045] This invention provides an improved waterborne polyurethane flame-retardant coating containing a flame-retardant emulsion, which includes a hydrophobic flame-retardant alkyl phosphinate. By improving the composition of the flame-retardant emulsion, this invention enables the emulsion to be stored stably for extended periods. When used as a flame-retardant component in a waterborne polyurethane flame-retardant coating, the coating maintains excellent flame-retardant properties even after storage and washing.

[0046] This invention employs a combination of specific types of nonionic and anionic dispersants in flame retardant emulsions. Nonionic dispersants such as alkylphenol polyoxyethylene ethers, dodecyl glycosides, Tween compounds, and fatty alcohol polyoxyethylene ethers all possess a sufficient number of hydrophilic groups. Anionic dispersants such as sodium polyacrylate, sodium dioctyl succinate sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate possess longer hydrophobic segments. Hydrogen bonding, hydrophobic interactions, and van der Waals forces exist between the nonionic dispersants, anionic dispersants, and aluminum diethylphosphinate, enabling aluminum diethylphosphinate to be stably dispersed in water in the presence of these two specific dispersants.

[0047] This invention employs specific types of anti-settling agents in flame retardant emulsions. The anti-settling agents used in this invention, such as organobentonite, modified hydrogenated castor oil, polyamide wax, fumed silica, and sodium carboxymethyl cellulose, can effectively inhibit the sedimentation of oily, halogen-free flame retardants such as aluminum diethylphosphonate in aqueous emulsions. Simultaneously, the combined effect of nonionic and anionic dispersants enables the flame retardant emulsion to exhibit excellent dispersion stability.

[0048] This invention controls the mass ratio of nonionic dispersant to anionic dispersant in flame retardant emulsions. In this invention, controlling the mass ratio of anionic dispersant to nonionic dispersant to be 1:1-9 further improves the dispersion stability of the flame retardant emulsion. The nonionic dispersant does not dissociate in aqueous emulsions and has good salt resistance, while the anionic dispersant's anionic functional groups have good temperature resistance. By combining the two and controlling their specific mass ratio, the flame retardant emulsion can simultaneously possess excellent temperature and salt resistance, enabling it to withstand high-temperature and high-salt environments.

[0049] In flame retardant emulsions, when sodium polyacrylate is selected as the anionic dispersant, its weight-average molecular weight needs to be controlled between 2,000 and 1,000,000. Excessively high weight-average molecular weight of sodium polyacrylate is detrimental to the stability of the flame retardant emulsion, thus affecting the storage stability of the final single-component waterborne polyurethane flame-retardant coating. Excessively high molecular weight sodium polyacrylate, due to its long chains, results in high viscosity, slow dissolution, easy gelation, and even bridging flocculation effects, severely impacting the dispersion effect.

[0050] In the waterborne polyurethane flame-retardant coating of the present invention, due to the addition of a stable flame-retardant emulsion, the flame-retardant particles do not agglomerate in the coating, resulting in a smooth, particle-free coating surface even after long-term storage. Furthermore, the coating achieves a VTM-0 flame-retardant rating and still passes the flame-retardant test after being washed with warm water.

[0051] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific applications, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0052] Preparation Examples 1-11 and Comparative Preparation Examples 1-5: First, flame retardant emulsions were prepared, which were used as one of the raw materials for the waterborne polyurethane coatings in the subsequent examples or comparative examples.

[0053] All the following quantities are by weight.

[0054] The organic bentonite used in the following flame retardant emulsions and waterborne polyurethane flame retardant coatings was purchased from Zhejiang Huatai New Materials Co., Ltd. as BP-188B modified bentonite.

[0055] In the examples and comparative examples, the waterborne polyurethane resin was a single-component waterborne polyurethane sourced from Wuhan Shiquanxing New Material Technology Co., Ltd. (R107); the Synde-1248 leveling agent was sourced from Zhuhai Xiande New Material Technology Co., Ltd.; the RH-9210 defoamer was sourced from Jiujiang Runhe Synthetic Materials; the HY-6410 was sourced from Mair Chemical; and the Sago-1900 was sourced from Shanggao. Preparation Example 1

[0056] In a reaction vessel (water bath heating temperature 35℃), add 2 parts octylphenol polyoxyethylene ether OP-10, 2 parts sodium polyacrylate (Mw=3000), and 43 parts deionized water, and stir until homogeneous. Then, slowly add 50 parts aluminum diethylphosphonate (particle size D50 of 2 μm, D95 of 7 μm), and disperse at 2000 rpm for 80 min to ensure uniform dispersion of aluminum diethylphosphonate in water. Finally, add 2 parts organobentonite and 1 part ammonia to adjust the pH, and stir at 1500 rpm for 30 min to obtain the flame retardant emulsion. Its appearance is shown in the figure below. Figure 1 As shown, the flame retardant particles are well wetted and dispersed. Preparation Example 2

[0057] In a reaction vessel (water bath heating temperature 35℃), 1.8 parts of polyoxyethylene sorbitan monolaurate Tween-20, 1.2 parts of sodium polyacrylate (Mw=4000), and 44 parts of deionized water were added and stirred until homogeneous. Then, 50 parts of aluminum diethylphosphonate (particle size D50 of 2 μm and D95 ​​of 7 μm) were slowly added and dispersed at 2000 rpm for 80 min to ensure uniform dispersion of the aluminum diethylphosphonate in water. Finally, 2 parts of fumed silica and 1 part of ammonia were added to adjust the pH, and the mixture was stirred at 1500 rpm for 30 min to obtain the flame retardant emulsion. Preparation Example 3

[0058] In a reaction vessel (water bath heating temperature 35℃), add 2.1 parts of fatty alcohol polyoxyethylene ether AEO-9, 0.9 parts of sodium polyacrylate (Mw=8000), and 45 parts of deionized water, and stir until homogeneous. Then, slowly add 50 parts of aluminum diethylphosphonate (particle size D50 of 2 μm, D95 of 7 μm), and disperse at 2000 rpm for 60 min to ensure uniform dispersion of aluminum diethylphosphonate in water. Finally, add 1 part of organobentonite and 1 part of ammonia to adjust the pH, and stir at 1500 rpm for 30 min to obtain the flame retardant emulsion. Preparation Example 4

[0059] In a reaction vessel (heated in a water bath at 35°C), add 2 parts dodecyl glycoside, 2 parts sodium dioctyl succinate sulfonate, and 43 parts deionized water, and stir until homogeneous. Then, slowly add 50 parts aluminum diethylphosphonate (particle size D50 of 2 μm and D95 ​​of 7 μm), and disperse at 2000 rpm for 80 min to ensure uniform dispersion of the aluminum diethylphosphonate in water. Finally, add 2 parts organobentonite and 1 part ammonia to adjust the pH, and stir at 1500 rpm for 30 min to obtain the flame retardant emulsion. Preparation Example 5

[0060] In a reaction vessel (water bath heating temperature 35℃), add 2.4 parts of dodecyl glycoside, 1.6 parts of sodium fatty alcohol polyoxyethylene ether sulfate, and 43 parts of deionized water, and stir until homogeneous. Then, slowly add 50 parts of aluminum diethylphosphonate (particle size D50 of 2 μm, D95 of 7 μm), and disperse at 2000 rpm for 80 min to ensure uniform dispersion of aluminum diethylphosphonate in water. Finally, add 2 parts of sodium carboxymethyl cellulose and 1 part of ammonia to adjust the pH, and stir at 1500 rpm for 30 min to obtain the flame retardant emulsion. Preparation Example 6

[0061] In a reaction vessel (water bath heating temperature 35℃), add 2 parts OP-10, 2 parts sodium polyacrylate (Mw=450000), and 33 parts deionized water, and stir until homogeneous. Then, slowly add 60 parts aluminum diethylphosphonate (particle size D50 of 2 μm, D95 of 7 μm), and disperse at 2000 rpm for 80 min to ensure uniform dispersion of the aluminum diethylphosphonate in water. Finally, add 2 parts organobentonite and 1 part ammonia to adjust the pH, and stir at 1500 rpm for 30 min to obtain the flame retardant emulsion. Preparation Example 7

[0062] In a reaction vessel (heated in a water bath at 35°C), add 2 parts dodecyl glycoside, 2 parts sodium dioctyl succinate sulfonate, and 34 parts deionized water, and stir until homogeneous. Then, slowly add 60 parts aluminum diethylphosphonate (particle size D50 of 2 μm and D95 ​​of 7 μm), and disperse at 2000 rpm for 80 min to ensure uniform dispersion of the aluminum diethylphosphonate in water. Finally, add 1 part polyamide wax and 1 part ammonia to adjust the pH, and stir at 1500 rpm for 30 min to obtain the flame retardant emulsion. Preparation Example 8

[0063] In a reaction vessel (water bath heating temperature 35℃), add 2 parts OP-10, 2 parts sodium polyacrylate (Mw=150000), and 33 parts deionized water, and stir until homogeneous. Then, slowly add 60 parts aluminum diethylphosphonate (particle size D50 4.0 μm, D95 12.5 μm), and disperse at 2000 rpm for 80 min to ensure uniform dispersion of aluminum diethylphosphonate in water. Finally, add 2 parts sodium carboxymethyl cellulose and 1 part ammonia to adjust the pH, and stir at 1500 rpm for 30 min to obtain the flame retardant emulsion. Preparation Example 9

[0064] In a reaction vessel (water bath heating temperature 35℃), add 1.2 parts AEO-9, 0.8 parts sodium polyacrylate (Mw=2000), and 45 parts deionized water, and stir until homogeneous. Then, slowly add 50 parts aluminum diethylphosphonate (particle size D50 30.0 μm, D95 45.0 μm), and disperse at 2000 rpm for 80 min to ensure uniform dispersion of the aluminum diethylphosphonate in water. Finally, add 2 parts organic polyamide wax and 1 part ammonia to adjust the pH, and stir at 1500 rpm for 30 min to obtain the flame retardant emulsion. Preparation Example 10

[0065] In a reaction vessel (water bath heating temperature 35℃), add 2 parts OP-10, 2 parts sodium polyacrylate (Mw=3000), and 42 parts deionized water, and stir until homogeneous. Then, slowly add 50 parts aluminum diethylphosphonate (particle size D50 30.0 μm, D95 45.0 μm), and disperse at 2000 rpm for 80 min to ensure uniform dispersion of the aluminum diethylphosphonate in water. Finally, add 3 parts organobentonite and 1 part ammonia to adjust the pH, and stir at 1500 rpm for 30 min to obtain the flame retardant emulsion. Preparation Example 11

[0066] The preparation method is basically the same as in Example 1, except that the antisettling agent is replaced by modified hydrogenated castor oil (THIXATROL ST product manufactured by Hemings Deqian) instead of organic bentonite. Comparative Preparation Example 1

[0067] The preparation method is basically the same as in Example 1, except that OP-10 is replaced with sorbitan monostearate Span-60. The appearance of the resulting mixture is shown in the figure below. Figure 2 As shown, aluminum diethylphosphonate cannot be dispersed in water and almost all of it floats on the water surface, making it impossible to prepare an emulsion of aluminum diethylphosphonate dispersed in water. Comparative Preparation Example 2

[0068] The preparation method is basically the same as in Example 2, except that sodium polyacrylate is replaced with sodium dodecylbenzenesulfonate. The appearance of the resulting mixture is shown in the figure below. Figure 3 As shown, aluminum diethylphosphonate cannot be dispersed in water and almost all of it floats on the water surface, making it impossible to prepare an emulsion of aluminum diethylphosphonate dispersed in water. Comparative preparation example 3

[0069] The preparation method is basically the same as in Example 1, except that sodium polyacrylate (Mw=3000) is replaced with sodium polyacrylate (Mw=1200000). Comparative preparation example 4

[0070] The preparation method is basically the same as in Example 5, except that sodium carboxymethyl cellulose is replaced with gelatin. Comparative preparation example 5

[0071] The preparation method is basically the same as in Example 9, except that the amount of AEO-9 is replaced by 0.2 parts instead of 1.2 parts, and the amount of sodium polyacrylate (Mw=2000) is replaced by 1.8 parts instead of 0.8 parts.

[0072] The flame retardant emulsions prepared in each preparation example and comparative preparation examples 3-5 were subjected to the following stability, temperature resistance and salt resistance tests. Since comparative preparation examples 1-2 could not form an emulsion, this test was not performed.

[0073] (1) Particle size test The flame retardant emulsions of Preparation Examples 1-11 and Comparative Preparation Examples 3-5, which were stored at room temperature in a sealed environment for 1-30 days, were tested using a laser particle size analyzer. The results are shown in Table 1.

[0074]

[0075] As shown in Table 1, the particle size of Preparation Examples 1-11 remained consistent with that of the aluminum diethylphosphinate powder used within 30 days, with no significant increase, indicating that the flame retardant particles did not agglomerate, demonstrating good emulsion stability. In contrast, the particle size of Preparation Examples 3-5 was significantly larger than that of the flame retardant powder, and the particle size increased significantly with prolonged storage time, indicating poor storage stability.

[0076] (2) Settlement stability test 100 mL of the flame retardant emulsions from Preparation Examples 1-11 and Comparative Preparation Examples 3-5 were injected into graduated test tubes, and the test tubes were sealed. The tubes were left to stand at room temperature for 1-30 days. The volume V of the clear liquid after separation was recorded, and the sedimentation stability coefficient K = (100-V) / 100 was calculated. The results are shown in Table 2 below. The photographs taken after 30 days are shown below. Figure 4 As shown.

[0077]

[0078] A higher settling stability coefficient K value indicates better settling stability of the flame retardant emulsion. (See Table 2) Figure 4 It can be seen that the sedimentation stability of the flame retardant emulsions in the prepared examples is much higher than that in the comparative prepared examples. Within 30 days, the sedimentation stability coefficients of prepared examples 1-11 were all above 0.9, while the sedimentation stability coefficient of comparative prepared example 3 was only 0.54, the sedimentation stability coefficient of comparative prepared example 4 was only 0.64, and the sedimentation stability coefficient of comparative prepared example 5 was only 0.71, indicating that the halogen-free flame retardant emulsions in the prepared examples have good sedimentation stability.

[0079] (3) Viscosity test The dynamic viscosity of the flame retardant emulsions of Preparation Examples 1-11 and Comparative Preparation Examples 3-5, which were stored at room temperature in a sealed environment, was tested using a rotational viscometer. The viscosity unit is mPa·s, and the results are shown in Table 3.

[0080]

[0081] As shown in Table 3, the emulsions of Preparation Examples 1-11 have lower viscosity and show no significant increase within 30 days, while the viscosity of the emulsions of Comparative Preparation Examples 3-5 is higher and increases significantly after 10-15 days. This indicates that the halogen-free flame-retardant emulsions of the prepared examples have good emulsion stability.

[0082] (4) Temperature resistance test 100g of the flame retardant emulsions from Preparation Examples 1-11 and Comparative Preparation Examples 3-5 were injected into fluorinated bottles. The bottles were sealed and placed in ovens at 25℃, 40℃, 60℃, 80℃, and 100℃ for 48 hours. The particle size was then measured, and the results are shown in Table 4.

[0083]

[0084] As shown in Table 4, with increasing temperature, the emulsion particle size of Preparation Examples 1-11 showed no significant difference from that at room temperature, indicating no particle aggregation and good temperature stability. In contrast, compared to Preparation Examples 3-5, the emulsion particle size increased significantly at 60°C compared to 25°C, resulting in poorer temperature stability. Generally, as temperature increases, surfactant molecular motion intensifies, intermolecular interactions weaken, and hydrogen bonds break more easily, increasing the probability of collisions between aluminum diethylphosphinic acid particles and making them more prone to aggregation and sedimentation, thus reducing emulsion stability. However, the flame retardant emulsions in the preparation examples, due to the selection of specific anionic and nonionic surfactants and the control of their ratio, achieved high-temperature resistance.

[0085] (5) Salt tolerance test Take 100g of the flame retardant emulsions from Preparation Examples 1-11 and Comparative Preparation Examples 3-5, and add 2%, 4%, 6%, and 8% of sodium chloride or calcium chloride saturated solution by mass of the emulsion, respectively. Test the particle size, and the results are shown in Tables 5 (sodium chloride) and 6 (calcium chloride), respectively.

[0086]

[0087] As shown in Tables 5 and 6, the halogen-free flame-retardant emulsions in the prepared examples maintained their original particle size even when the salt content increased to 8%, demonstrating good salt resistance. In contrast, the particle size of prepared examples 3-5 increased significantly upon the addition of sodium or calcium salts, and particle aggregation began to occur, resulting in poorer salt resistance. Example 1

[0088] This embodiment provides a water-based polyurethane flame-retardant coating: First, 50 parts of single-component waterborne polyurethane resin, 0.7 parts of Synde-1248 leveling agent, 0.8 parts of propylene glycol butyl ether, and 0.1 parts of RH-9210 defoamer were mixed and dispersed at 800 r / min for 25 minutes to obtain solution a. Then, 45 parts of the flame retardant emulsion prepared in Preparation Example 1 and left for 5 days, and the remaining 0.1 parts of RH-9210 defoamer were added to solution a. The stirring speed was reduced to 600 r / min and stirred for 25 minutes to obtain solution b. Finally, 0.3 parts of organic bentonite were dispersed in 3 parts of water to form a dispersion, which was then slowly and evenly added dropwise to solution b. The mixture was stirred at 300 r / min for 20 minutes until the system was completely homogeneous and the viscosity was stable, thus obtaining the waterborne polyurethane flame retardant coating. Example 2

[0089] This embodiment provides a water-based polyurethane flame-retardant coating: The process is basically the same as in Example 1, except that the added flame retardant emulsion is the same as that prepared in Example 1 and left to stand for 30 days. Example 3

[0090] This embodiment provides a water-based polyurethane flame-retardant coating: First, 41 parts of single-component waterborne polyurethane resin, 1 part of Deqian 810, 1.2 parts of dipropylene glycol butyl ether, and 0.25 parts of BYK-1710 defoamer were stirred and dispersed at 1000 r / min for 20 minutes to obtain solution a. Then, 50.85 parts of the flame retardant emulsion prepared in Preparation Example 2 and left for 30 days, and the remaining 0.2 parts of BYK-1710 defoamer were added to solution a. The stirring speed was reduced to 800 r / min and stirred for 25 minutes to obtain solution b. Finally, 0.5 parts of waterborne polyamide wax were dispersed in 5 parts of water to form a dispersion, and then slowly and evenly added to solution b. The mixture was stirred at 400 r / min for 15 minutes until the system was completely homogeneous and the viscosity was stable, thus obtaining the waterborne polyurethane flame retardant coating. Example 4

[0091] This embodiment provides a water-based polyurethane flame-retardant coating: First, 50 parts of single-component waterborne polyurethane resin, 0.6 parts of HY-6410, 1.1 parts of dipropylene glycol methyl ether, and 0.15 parts of AFCONA-2508 defoamer were stirred and mixed at 800 r / min for 30 minutes to obtain solution a. Then, 44.7 parts of the flame retardant emulsion prepared in Preparation Example 3 and left for 30 days, and the remaining 0.15 parts of AFCONA-2508 defoamer were added to solution a. The stirring speed was reduced to 600 r / min and stirred for 20 minutes to obtain solution b. Finally, 0.3 parts of organic bentonite were dispersed in 3 parts of water to form a dispersion, which was then slowly and evenly added dropwise to solution b. The mixture was stirred at 350 r / min for 20 minutes until the system was completely homogeneous and the viscosity was stable, thus obtaining the waterborne polyurethane flame retardant coating. Example 5

[0092] This embodiment provides a water-based polyurethane flame-retardant coating: First, 50 parts of single-component waterborne polyurethane resin, 0.8 parts of Synde-1248 leveling agent, 0.8 parts of propylene glycol butyl ether, and 0.2 parts of Sago-1900 defoamer were stirred and dispersed at 1000 r / min for 30 minutes to obtain solution a. Then, 44.8 parts of the flame retardant emulsion prepared in Preparation Example 4 and left for 30 days, and the remaining 0.1 parts of Sago-1900 defoamer were added to solution a. The stirring speed was reduced to 600 r / min and stirred for 35 minutes to obtain solution b. Finally, 0.3 parts of waterborne polyamide wax were dispersed in 3 parts of water to form a dispersion, which was then slowly and evenly added dropwise to solution b. The mixture was stirred at 400 r / min for 20 minutes until the system was completely homogeneous and the viscosity was stable, thus obtaining the waterborne polyurethane flame retardant coating. Example 6

[0093] This embodiment provides a water-based polyurethane flame-retardant coating: First, 50 parts of single-component waterborne polyurethane resin, 0.8 parts of Synde-1248 leveling agent, 1 part of dipropylene glycol methyl ether, and 0.15 parts of AFCONA-2505 defoamer were stirred and dispersed at 1100 r / min for 20 minutes to obtain solution a. Then, 43.5 parts of the flame retardant emulsion prepared in Preparation Example 5 and left for 30 days, and the remaining 0.15 parts of AFCONA-2505 defoamer were added to solution a. The stirring speed was reduced to 900 r / min and stirred for 20 minutes to obtain solution b. Finally, 0.4 parts of montmorillonite were dispersed in 4 parts of water to form a dispersion, which was then slowly and evenly added dropwise to solution b. The mixture was stirred at 300 r / min for 20 minutes until the system was completely homogeneous and the viscosity was stable, thus obtaining the waterborne polyurethane flame retardant coating. Example 7

[0094] This embodiment provides a water-based polyurethane flame-retardant coating: First, 50 parts of waterborne polyurethane resin, 0.5 parts of HY-6410, 1 part of propylene glycol butyl ether, and 0.1 parts of AFCONA-2508 defoamer were stirred and mixed at 800 r / min for 35 minutes to obtain solution a. Then, 41.65 parts of the flame retardant emulsion prepared in Preparation Example 9 and left for 30 days, and the remaining 0.15 parts of AFCONA-2508 defoamer were added to solution a. The stirring speed was reduced to 500 r / min and stirred for 25 minutes to obtain solution b. Finally, 0.6 parts of montmorillonite were dispersed in 6 parts of water to form a dispersion, which was then slowly and evenly added dropwise to solution b. The mixture was stirred at 300 r / min for 20 minutes until the system was completely homogeneous and the viscosity was stable, thus obtaining the waterborne polyurethane flame retardant coating. Example 8

[0095] This embodiment provides a water-based polyurethane flame-retardant coating: First, 55 parts of single-component waterborne polyurethane resin, 0.6 parts of Synde-1248 leveling agent, 1.3 parts of propylene glycol butyl ether, and 0.12 parts of RH-9210 defoamer were stirred and dispersed at 1200 r / min for 20 minutes to obtain solution a. Then, 39.58 parts of the flame retardant emulsion prepared in Preparation Example 6 and left for 30 days, and the remaining 0.1 parts of RH-9210 defoamer were added to solution a. The stirring speed was reduced to 800 r / min and stirred for 25 minutes to obtain solution b. Finally, 0.3 parts of organic bentonite were dispersed in 3 parts of water to form a dispersion, which was then slowly and evenly added dropwise to solution b. The mixture was stirred at 300 r / min for 25 minutes until the system was completely homogeneous and the viscosity was stable, thus obtaining the waterborne polyurethane flame retardant coating. Example 9

[0096] This embodiment provides a water-based polyurethane flame-retardant coating: First, 55 parts of single-component waterborne polyurethane resin, 0.8 parts of Synde-1248 leveling agent, 1 part of propylene glycol butyl ether, and 0.1 parts of RH-9210 defoamer were mixed and dispersed at 1000 r / min for 20 minutes to obtain solution a. Then, 37.4 parts of the flame retardant emulsion prepared in Preparation Example 8 and left for 30 days, and the remaining 0.2 parts of RH-9210 defoamer were added to solution a. The stirring speed was reduced to 600 r / min and stirred for 30 minutes to obtain solution b. Finally, 0.5 parts of organic bentonite were dispersed in 5 parts of water to form a dispersion, which was then slowly and evenly added dropwise to solution b. The mixture was stirred at 300 r / min for 20 minutes until the system was completely homogeneous and the viscosity was stable, thus obtaining the waterborne polyurethane flame retardant coating. Example 10

[0097] This embodiment provides a water-based polyurethane flame-retardant coating: First, 58 parts of single-component waterborne polyurethane resin, 1 part of Synde-1248 leveling agent, 1.2 parts of propylene glycol butyl ether, and 0.15 parts of RH-9210 defoamer were mixed and dispersed at 1200 r / min for 20 minutes to obtain solution a. Then, 35.05 parts of the flame retardant emulsion prepared in Preparation Example 8 and left for 30 days, and the remaining 0.2 parts of RH-9210 defoamer were added to solution a. The stirring speed was reduced to 600 r / min and stirred for 35 minutes to obtain solution b. Finally, 0.4 parts of organic bentonite were dispersed in 4 parts of water to form a dispersion, which was then slowly and evenly added dropwise to solution b. The mixture was stirred at 400 r / min for 20 minutes until the system was completely homogeneous and the viscosity was stable, thus obtaining the waterborne polyurethane flame retardant coating. Comparative Example 1

[0098] The process is basically the same as in Example 1, except that the flame retardant emulsion used is replaced with the flame retardant emulsion that was just prepared in Comparative Preparation Example 3. Comparative Example 2

[0099] The process is basically the same as in Example 6, except that the flame retardant emulsion used is replaced with the flame retardant emulsion that was just prepared in Comparative Preparation Example 4. Comparative Example 3

[0100] The process is basically the same as in Example 7, except that the flame retardant emulsion used is replaced with the flame retardant emulsion that was just prepared in Comparative Preparation Example 5. Comparative Example 4

[0101] 50 parts of single-component waterborne polyurethane resin, 0.9 parts of emulsifier octylphenol polyoxyethylene ether OP-10, 0.9 parts of sodium polyacrylate (Mw=3000), 0.2 parts of RH-9210 defoamer, 19.35 parts of deionized water, 0.7 parts of Synde-1248 leveling agent, and 22.5 parts of aluminum diethylphosphinic acid (particle size D50 of 2 micrometers and D95 ​​of 7 micrometers) were added to a container and stirred to disperse evenly. Then, 1.2 parts of organic bentonite were dispersed in 12 parts of water to form a dispersion, which was then slowly and evenly added dropwise to the above mixture. The mixture was emulsified at high speed using an emulsifier at room temperature to obtain a waterborne polyurethane emulsion coating.

[0102] After storing the waterborne polyurethane flame-retardant coatings prepared in each embodiment and comparative example in a sealed container for a period of time (7 days or 25 days), the coating film properties and flame-retardant properties of each coating were tested. (1) Using a 100μm applicator, apply the single-component waterborne polyurethane flame retardant coating evenly to the polyimide film (the film is smooth to facilitate observation of the coating state, and the film shows a certain degree of orange color), place it in an 80℃ forced-air drying oven to dry for 30 minutes, and observe the coating state.

[0103] (2) Flame retardancy test: The flame retardancy rating of the above coating was tested using the VTM (Video Vertical Burning Test) method specified in UL 94 standard (the standard requires 5 samples to be tested, and each sample to be burned twice). The flame retardancy of the above coating was tested according to the BS5852 flame retardancy test standard after washing in 40°C warm water for 30 minutes. Specific test conditions were as follows: ignition source was source #1 (35mm butane flame), flame height was 35mm, ignition time was 20s, substrate was nylon fiber textile, and coating amount was 100g / m². 2 ±5g / m 2 .

[0104] The test results of the coatings after 7 days of storage are shown in Table 7 (coating condition, BS5852 performance) and Table 8 (VTM, where T1 is the first combustion data and T2 is the second combustion data), where "-" indicates no test. The coating photographs of Example 1, Comparative Example 1, Comparative Example 2, and the demulsification photograph of the single-component waterborne polyurethane flame-retardant coating of Comparative Example 4 are shown below. Figure 5 As stated above.

[0105]

[0106]

[0107] As shown in Tables 7 and 8, the waterborne polyurethane flame-retardant coatings prepared in Examples 1-10 can be stably stored for 7 days and all can pass the VTM (Vertical Burning Test) test specified in UL 94 standard and the BS5852 flame retardancy test. This indicates that the flame retardant emulsion used as a flame retardant is suitable for single-component waterborne polyurethane coating systems, and the flame retardancy of the coating is water-resistant, maintaining a high level of flame retardancy even after washing. Therefore, this coating can be applied in the textile industry. In contrast, the flame retardant emulsion used in Comparative Example 1, even though the emulsion itself was not stored and was used to prepare the coating immediately after preparation, showed significant agglomeration of the flame retardant components after 7 days of storage. This resulted in a significant increase in the particle size of the polyurethane coating emulsion, ultimately leading to a rough coating surface with noticeable particles. Furthermore, due to the uneven dispersion of the flame retardant and the agglomeration between particles, the flame retardant performance was poor. The agglomerated particles were easily washed away during water washing, causing the coating to fail the water-wash flame retardancy test after washing. The flame retardant components used in Comparative Examples 2 and 3 were also freshly formulated. After 7 days of storage, a small number of particles remained on the coating surface, indicating slight agglomeration of the flame retardant. Although they passed the VTM (Vertical Burning Test) specified in the UL 94 standard, they failed the BS5852 test after washing, indicating poor flame retardancy and water resistance of the coating. This is because the curing process of the coating on the fabric involves polymer chains (single-component waterborne polyurethane resin) winding and penetrating into the gaps in the fabric fibers, forming a mechanical "anchoring" effect after cooling or cross-linking. In Comparative Examples 2 and 3, the flame retardant agglomeration resulted in larger particle sizes, making it difficult to fully embed into the polymer network and fiber microstructure, resulting in poor anchoring. During washing, the water flow easily caused the flame retardant particles to detach, thus failing the BS5852 test. The coating in Comparative Example 4 was demulsified and unusable; further testing was unnecessary.

[0108] The test results of the paint after 25 days of storage are shown in Tables 9 and 10 below, where “-” indicates that it was not tested.

[0109]

[0110]

[0111] Tables 9 and 10 show that the waterborne polyurethane flame-retardant coatings prepared in Examples 1-10, after 25 days of storage, passed the VTM (Vertical Burning Test) test specified in UL 94 and the BS 5852 flame retardancy test. This indicates that the flame retardant emulsion, as a flame retardant component, has good compatibility with the waterborne polyurethane coating, allowing for long-term storage and transportation of the single-component waterborne polyurethane coating. This facilitates the industrial application of hydrophobic alkylphosphinate aluminum and other flame retardants in waterborne coatings. The single-component waterborne polyurethane coatings in Comparative Examples 1, 2, and 4 experienced demulsification, indicating poor compatibility between the flame retardant and the coating. These coatings could not be stored for extended periods, hindering the industrial application of flame retardants in coatings; therefore, flame retardancy tests were not conducted on them. In Comparative Example 3, the single-component waterborne polyurethane flame-retardant coating agglomerated and became unevenly dispersed after 25 days of storage, resulting in a rough coating surface and decreased flame retardant performance; it failed the flame retardancy test after washing.

[0112] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0113] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A water-based polyurethane flame-retardant coating, characterized in that: The waterborne polyurethane flame-retardant coating comprises a waterborne polyurethane resin and a flame-retardant emulsion; the flame-retardant emulsion comprises alkyl phosphonates, dispersants, anti-settling agents, and water; the dispersant is composed of nonionic and anionic dispersants; the nonionic dispersant is selected from one or more combinations of alkylphenol polyoxyethylene ethers, dodecyl glycosides, Tween compounds, and fatty alcohol polyoxyethylene ethers; the anionic dispersant is selected from one or more combinations of sodium polyacrylate, sodium dioctyl succinate sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate; the mass ratio of the anionic dispersant to the nonionic dispersant is 1:1-9; the anti-settling agent is selected from one or more combinations of organobentonite, modified hydrogenated castor oil, polyamide wax, fumed silica, and sodium carboxymethyl cellulose; the weight-average molecular weight of the sodium polyacrylate is 2000-1000000.

2. The waterborne polyurethane flame-retardant coating according to claim 1, characterized in that: The mass ratio of the anionic dispersant to the nonionic dispersant is 1:1-3.

3. The waterborne polyurethane flame-retardant coating according to claim 1, characterized in that: The alkylphosphinate is selected from one or more of the corresponding aluminum salt, zinc salt, magnesium salt, calcium salt, ferrous salt, and sodium salt; and / or, the alkyl group in the alkylphosphinate is selected from one or more of straight-chain or branched C1-C6 alkyl groups and C4-C8 cycloalkyl groups.

4. The waterborne polyurethane flame-retardant coating according to claim 1, characterized in that: The alkyl phosphinate is selected from one or more combinations of aluminum diethylphosphinate, zinc dibutylphosphinate, aluminum diisobutylphosphinate, aluminum isobutylphosphinate, zinc methylethylphosphinate, zinc methylcyclohexylphosphinate, and aluminum monoethylphosphinate.

5. The waterborne polyurethane flame-retardant coating according to claim 1, characterized in that: The alkylphosphonates have a D50 particle size of 1-35 micrometers and a D95 particle size of 5-55 micrometers.

6. The waterborne polyurethane flame-retardant coating according to claim 1, characterized in that: According to the weight percentages, the flame retardant emulsion comprises 20-80 parts of alkyl phosphonate, 0.1-5 parts of anti-settling agent, and 20-80 parts of water; the dispersant consists of 0.1-5 parts of nonionic dispersant and 0.1-5 parts of anionic dispersant.

7. The waterborne polyurethane flame-retardant coating according to claim 6, characterized in that: According to the weight percentages, the flame retardant emulsion comprises 50-70 parts of alkyl phosphonate, 1-3 parts of anti-settling agent, and 30-50 parts of water; the dispersant consists of 1-3 parts of nonionic dispersant and 0.5-2 parts of anionic dispersant.

8. The waterborne polyurethane flame-retardant coating according to claim 1, characterized in that: The flame retardant emulsion also includes a pH adjuster.

9. The waterborne polyurethane flame-retardant coating according to claim 1, characterized in that: The waterborne polyurethane flame retardant coating also includes at least one of the following: defoamer, leveling agent, thickener, and film-forming aid.

10. The waterborne polyurethane flame-retardant coating according to claim 9, characterized in that: The defoamer is selected from one or more combinations of AFCONA-2505, AFCONA-2508, RH-9210, BYK-1710 and Sago-1900; and / or, the leveling agent is selected from one or more combinations of Deqian 810, HY-6410 and Synde-1248; and / or, the thickener is selected from one or more combinations of waterborne polyamide wax, montmorillonite, and organobentonite; and / or, the film-forming aid is selected from one or more combinations of propylene glycol butyl ether, dipropylene glycol methyl ether, and dipropylene glycol butyl ether.

11. The waterborne polyurethane flame-retardant coating according to claim 9, characterized in that: According to the weight percentages, the waterborne polyurethane flame retardant coating comprises 40-60 parts of waterborne polyurethane resin, 35-55 parts of flame retardant emulsion, 0.1-0.8 parts of defoamer, 0.2-1.0 parts of leveling agent, 0.3-1.2 parts of thickener, 0.5-1.5 parts of film-forming aid, and 1-8 parts of water.

12. A method for preparing a waterborne polyurethane flame-retardant coating according to any one of claims 1-11, characterized in that: The preparation method includes the following steps: 1) stirring and dispersing the nonionic dispersant, anionic dispersant, water and alkyl phosphinate in the flame retardant emulsion to obtain a mixture; 2) adding the anti-settling agent and pH adjuster to the mixture, stirring and dispersing to obtain the flame retardant emulsion; 3) stirring and dispersing the waterborne polyurethane resin, leveling agent, film-forming aid and part of defoamer to obtain a first liquid; 4) adding the flame retardant emulsion and the remaining defoamer to the first liquid, stirring and dispersing to obtain a second liquid; 5) adding an aqueous dispersion of thickener to the second liquid, stirring and dispersing to obtain the waterborne polyurethane flame retardant coating.

13. The preparation method according to claim 12, characterized in that: Both steps 1) and 2) are performed at 20-50℃.

14. The preparation method according to claim 12, characterized in that: The stirring speed in step 1) is 500-8000 r / min; and / or the stirring, mixing and dispersing time in step 1) is 10-200 min; and / or the stirring speed in step 2) is 100-1500 r / min; and / or the stirring and dispersing time in step 2) is 10-100 min.

15. The preparation method according to claim 12, characterized in that: The stirring speed in step 3) is 800-1200 r / min; and / or the stirring, mixing and dispersing time in step 3) is 20-40 min; and / or the stirring speed in step 4) is 400-1000 r / min; and / or the stirring, mixing and dispersing time in step 4) is 20-60 min; and / or the stirring speed in step 5) is 200-500 r / min; and / or the stirring and dispersing time in step 5) is 10-30 min.

16. Use of the waterborne polyurethane flame-retardant coating according to any one of claims 1-11 for textile coating.

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